# pos

id: cord-032174-qu5mm9r1
pos: NNP
token:
  ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

lemma:
  ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi


# ent

id: cord-006892-n2ncamqh
type: PROTEIN
entity:
  norovirus GI I GII 4 bivalent virus like particle VLP vaccine in adults NCT03039790 Takeda Safety and immunogenicity of norovirus GI 1 GII 4 bivalent virus like particle vaccine


id: cord-006892-n2ncamqh
type: PROTEIN
entity:
  Chimeric GII 4 Norovirus Virus Like Particle Based Vaccines Induce Broadly Blocking Immune Responses Chimeric bivalent virus like particle vaccine


id: cord-006947-nrzjedhi
type: CELL_LINE
entity:
  human red blood cell membrane Proc Equilibrium physics breakdown reveals the active nature of red blood cell flickering Receptor


id: cord-006947-nrzjedhi
type: WORK_OF_ART
entity:
  Math On the attraction of floating particles Effective capillary interaction of spherical particles at fluid interfaces Force


id: cord-007363-h8xa83nw
type: ORG
entity:
  JSPS Japan Society for the Promotion of Science Fund for the Promotion of Joint International Research Grant


id: cord-008454-8brxpotx
type: GGP
entity:
  Sadakane 1975 al 19771 but as yet there has only been one report of a successful negative stain diagnosis Goodfellow and Calvert 1979 Laryngeal wart thin sections have shown scanty papillomavirus


id: cord-008454-8brxpotx
type: CHEMICAL
entity:
  N 11972 Oral Surg Oral Med Oral A m A m Viral Immunodiagnosis A m A m A m A m A m Viral Immunodiagnosis Viral Immunodiagnosis Lancet 2 1007 Der Virus Morphology Lancet 2 124 Madeley A m A m Lancet 2 318 Proc Int


id: cord-009769-cql7go58
type: WORK_OF_ART
entity:
  Flow and Particle Dispersion in Lung Acini Effect of Geometric and Dynamic Parameters During Synchronous Ventilation


id: cord-009769-cql7go58
type: FAC
entity:
  the Human Lung Structural Aspects of Postnatal Lung Development Alveolar Formation and Growth Axial Dispersion in Respiratory Bronchioles and Alveolar Ducts Gas


id: cord-009769-cql7go58
type: EVENT
entity:
  Aerosol Kinetics II Gravitational Sedmimentation and Inertial Impaction Chaotic Mixing of Alveolated Duct Flow in Rhythmically Expanding Pulmonary Acinus Recirculating Flow


id: cord-009825-6cargkwy
type: DISEASE
entity:
  influenza A virus a review of new studies Effects of room furnishings and air speed on particle deposition


id: cord-032165-nyj72o21
type: GGP
entity:
  K 0 ¼ 5 Â 10 À10 cm 3 s 24 From the above data when initial concentration is less than 10 6 pc cm 3 the influence of coagulation can be neglected during measurement with time period 10 min If the measurement time is 2 days the concentration should be less than 10 3 pc cm 3 so that the coagulation effect can be ignored This aspect should be noticed during the experimental study leakage detection of air filter and selfpurification time with smoke release The above sections have discussed various movement situations of single particle and the influence generated by local airflow Now the further study is presented about the particle distribution with particles released by the source in the flow field The simplest case is the particle distribution with the point source in the parallel flow field The specific aim is to determine the boundary of particle distribution namely the range of pollution Here


id: cord-022504-tk7v4hoj
type: CELL_TYPE
entity:
  anterior nasal passage posterior nasal passage pharynx larynx trachea main bronchi bronchi bronchioles terminal bronchioles alveolar duct


id: cord-022504-tk7v4hoj
type: ORG
entity:
  Occupational Exposure Limits WHO Environmental Health Series 4 World Health Organization Summaries Evaluations Nickel and


id: cord-280272-mn596x1p
type: DNA
entity:
  Taq Man probe 5 6 carboxyfluorescein TGTTGGAAGGGAAGATAAACGGCTACGC 6 carboxy N N N N tetramethylrhodamine 3


id: cord-280272-mn596x1p
type: ORG
entity:
  George Mason University Institutional Animal Care and Use Committee Containing and Preventing Biological


id: cord-265642-7mu530yp
type: DNA
entity:
  human immunodeficiency virus HIV 1 envelope glycoprotein 18 19 and influenza virus haemagglutinin 20


id: cord-265642-7mu530yp
type: ORG
entity:
  Galina Podzolkova Institute for Statistical Studies and Economics of Knowledge ISSEK National Research University Higher School of Economics


id: cord-265642-7mu530yp
type: DISEASE
entity:
  human immunodeficiency virus type 1 Gag ubiquitination Global landscape of HIV human protein complexes Viruslike nanoparticle vaccine


id: cord-310948-nt378esz
type: WORK_OF_ART
entity:
  Recommendation Regarding the Use of Cloth Face Coverings Especially in Areas of Significant Community Based Transmission Use of Cloth Face Coverings


id: cord-274355-6hiutrct
type: WORK_OF_ART
entity:
  Documentation ASHRAE Standard Ventilation for Health Care Facilities ASHRAE Fundamentals SI Handbook


id: cord-313825-bbjxd86y
type: GGP
entity:
  processes 3 4 7 14 24 Anthropogenic sources of outdoor PM are hightemperature processes e g welding smelting combustion e g power generation land traffic residential


id: cord-222700-yof5x4ct
type: WORK_OF_ART
entity:
  An Overview of Their Replication and Pathogenesis in Coronaviruses Principles of Neural Science Particle


id: cord-311486-auuyjct6
type: ORG
entity:
  Centers for Disease Control and Prevention Interim Infection Prevention and Control Recommendations for Patients with Suspected


id: cord-292928-a4bn30ul
type: PROTEIN
entity:
  bacteria bacterial endotoxins mycotoxins peptidoglycans β 1 3 glucans viruses high molecular weight allergens pollens


id: cord-318495-1w74wf02
type: ORG
entity:
  Low Fidelity Polymerases of Alphaviruses Recombine at Higher Rates To Overproduce Defective Interfering Particles


id: cord-318495-1w74wf02
type: ORG
entity:
  Sarcoma Associated Herpesvirus Activate Lytic Replication by Triggering Differentiation Signaling Ultrastructural


id: cord-340639-hdn85mik
type: DISEASE
entity:
  Willeke 1992 Huang Willeke Qian Grinshpun Ulevicius 1998 Johnston Myers Colton Birkner Campbell 2001


id: cord-289521-zun6tp2o
type: ORG
entity:
  Department of Health and Social Care Public Health Wales Public Health Agency Northern Ireland Health Protection Scotland Public Health England Guidance


id: cord-289521-zun6tp2o
type: ORG
entity:
  High Velocity Nasal Insufflation Therapy Using a Simple Surgical Mask Implications for High Flow Nasal Cannula Aerosol


id: cord-324585-2rx84imv
type: WORK_OF_ART
entity:
  Article How to Sew a Fabric Face Mask Transmission Routes of Respiratory Viruses Among Humans Exhalation of Respiratory Viruses by Breathing Coughing and Talking National Academies of Sciences Medicine Rapid Expert Consultation on the Possibility of Bioaerosol Spread of SARS CoV 2 for the COVID 19 Pandemic A Cluster Randomised Trial of Cloth Masks


id: cord-324585-2rx84imv
type: ORG
entity:
  the University of Nebraska Documentary Research of Human Respiratory Droplet Characteristics Procedia Eng World Health Organization Annex C Respiratory


id: cord-324585-2rx84imv
type: ORG
entity:
  Health Care Considerations for Routine and Surge Use A Strategy for Assessing and Managing Occupational


id: cord-339475-okw6la2b
type: DISEASE
entity:
  respiratory tract gastrointestinal tract hematopoietic system liver kidney bones endocrine system and nervous system Herbicides pesticides


id: cord-314009-7t1bzc7f
type: DISEASE
entity:
  influenza A virus and nanoemulsion Efficacy immunogenicity and stability of a novel intranasal nanoemulsion adjuvanted influenza vaccine


id: cord-282858-zikoui4h
type: ORG
entity:
  Respiratory Pathogen Emissions Potential Implications for Reducing Transmission of Airborne Transmission of Communicable Infection


id: cord-282858-zikoui4h
type: ORG
entity:
  the Severe Acute Respiratory Syndrome Virus Transmission of the Severe Acute Respiratory Syndrome on Aircraft A


id: cord-311311-rmv5rfst
type: WORK_OF_ART
entity:
  The Sugar Tube Method of Determining Rock Dust in Air A New Instrument for Sampling Aerial Dusts Bureau of Mines Midget Impinger Filter Paper Method for Obtaining Dust Concentration Results Comparable


id: cord-311311-rmv5rfst
type: FAC
entity:
  the Airmon Modern Principles of Workplace Air Monitoring Large Particle and Wall Deposition Effects in Inhalable Samplers Health and Safety Executive HSE Contract Research Report


id: cord-311311-rmv5rfst
type: ORG
entity:
  Occupational Safety and Health Administration OSHA Department of Labor Occupational Exposure to Respirable Crystalline Silica


id: cord-261908-olcuq6tm
type: ORG
entity:
  WHO Severe Acute Respiratory Illness SARI Surveillance Influenza Report FIFA Soccer Would Cup South Africa Communicable Disease Risks


id: cord-313971-czcs1y9w
type: DISEASE
entity:
  Aspergillus sp Alternaria sp Cladosporium sp Penicillium sp Fusarium sp Scopulariopsis sp and yeast Chang


id: cord-306371-jmaqkovs
type: ORG
entity:
  the Commission of the European Communities Priority 3 Nanotechnologies and Nanosciences Knowledge Based Multifunctional Materials New Production Processes and Devices of the Sixth Framework Programme for Research and Technological Development Targeted Delivery of Nanomedicine NMP4 CT 2006


id: cord-329137-5pw07qje
type: WORK_OF_ART
entity:
  Immature and Mature Human Astrovirus Structure Conformational Changes and Similarities to Hepatitis E Virus


id: cord-319221-x834qscq
type: ORG
entity:
  American Society of Heating Refrigerating and Air Conditioning Engineers American Society of Heating Refrigerating and Air Conditioning Engineers Development


id: cord-286878-5nv3ec5l
type: ORG
entity:
  the Difficult Airway Society the Association of Anaesthetists the Intensive Care Society the Faculty of Intensive Care Medicine


id: cord-355883-uyrn281a
type: ORG
entity:
  Air Quality Study Description and Relation to Key Meteorological Gas Phase Aerosol Parameters Special Issue


id: cord-355883-uyrn281a
type: EVENT
entity:
  Resources 770 Conservation and Recycling Scanning Electrical Mobility Spectrometer Characteristics 775


id: cord-325915-dw989txm
type: DNA
entity:
  VSV G pseudotyped retroviral vector AC Fractogel EMD heparin S 61 66 Filtration UF DF AC SEC Fractogel EMD heparin S Sepharose CL 4B Retroviridae vector MoMLV


id: cord-325915-dw989txm
type: DISEASE
entity:
  abnormal cervical cytology A correlation with histological study The pH stability of the papilloma virus protein The removal of phages T1 and PP7 and poliovirus from fluids with hollow fiber


# bib

id: cord-005112-9mxqwqty
title: Methods for counting particles in microfluidic applications
author: Zhang, Hongpeng
date: 2009-08-20
txt: ./txt/cord-005112-9mxqwqty.txt
cache: ./cache/cord-005112-9mxqwqty.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7088397/
doi: 10.1007/s10404-009-0493-7
summary:
  Nanopore-based methods are used for single DNA molecule analysis and the capacitance counter is useful in liquids of low electrical conductivity and in sensing the changes of cell contents. In this paper, we review the major advancement of microfluidic particle counting techniques: microfluidic resistive repulse sensors, nanopore sensors, capacitance counters, light-scattering and light-blocking detectors, fluorescent detectors, and micro particle image velocimetry (PIV) counters. The microfluidic resistive pulse technique applies the basic working principle of the Coulter counter to microchannels for counting micro-and sub-micron particles. The key advantages of the microfluidic RPS include label-free particle detection and simplicity without other peripheral complex instruments other than a simple electric circuit and a micro-or nano-scale sized channel. They coupled the RPS with laser fiber-optic fluorescence technique to demonstrate a flow cytometer LOC that is able to detect fluorescent and non-fluorescent particles simultaneously, and the RPS signal-to-noise ratio is improved significantly.

abstract:
  Microfluidic particle counters are important tools in biomedical diagnostic applications such as flow cytometry analysis. Major methods of counting particles in microfluidic devices are reviewed in this paper. The microfluidic resistive pulse sensor advances in sensitivity over the traditional Coulter counter by improving signal amplification and noise reduction techniques. Nanopore-based methods are used for single DNA molecule analysis and the capacitance counter is useful in liquids of low electrical conductivity and in sensing the changes of cell contents. Light-scattering and light-blocking counters are better for detecting larger particles or concentrated particles. Methods of using fluorescence detection have the capability for differentiating particles of similar sizes but different types that are labeled with different fluorescent dyes. The micro particle image velocimetry method has also been used for detecting and analyzing particles in a flow field. The general limitation of microfluidic particle counters is the low throughput which needs to be improved in the future. The integration of two or more existing microfluidic particle counting techniques is required for many practical on-chip applications.


id: cord-006892-n2ncamqh
title: Virus-like particle vaccines: immunology and formulation for clinical translation
author: Donaldson, Braeden
date: 2018-09-19
txt: ./txt/cord-006892-n2ncamqh.txt
cache: ./cache/cord-006892-n2ncamqh.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7103734/
doi: 10.1080/14760584.2018.1516552
summary:
  For example, chemical conjugation of mannoside-based saccharides on the surface of Rabbit hemorrhagic disease virus (RHDV) VLP selectively targets the mannose receptor expressed on the surface of APCs, inducing increased uptake and alteration of antigen cross-presentation in murine dendritic cells [57] . While the induction of a potent humoral immune response and the subsequent production of anti-VLP antibodies is the primary desired outcome of most commercial VLP vaccines, these is increasing appreciation for the role of vaccine-induced cell-mediated immunity [123] [124] [125] . Novel Epstein-Barr virus-like particles incorporating gH/gL-EBNA1 or gB-LMP2 induce high neutralizing antibody titers and EBV-specific T-cell responses in immunized mice Induction of immune memory following administration of a prophylactic quadrivalent human papillomavirus (HPV) types 6/11/16/18 L1 virus-like particle (VLP) vaccine. Antigen incorporated in virus-like particles is delivered to specific dendritic cell subsets that induce an effective antitumor immune response in vivo

abstract:
  Introduction: Virus-like particle (VLP) vaccines face significant challenges in their translation from laboratory models, to routine clinical administration. While some VLP vaccines thrive and are readily adopted into the vaccination schedule, others are restrained by regulatory obstacles, proprietary limitations, or finding their niche amongst the crowded vaccine market. Often the necessity to supplant an existing vaccination regimen possesses an immediate obstacle for the development of a VLP vaccine, despite any preclinical advantages identified over the competition. Novelty, adaptability and formulation compatibility may prove invaluable in helping place VLP vaccines at the forefront of vaccination technology. Areas covered: The purpose of this review is to outline the diversity of VLP vaccines, VLP-specific immune responses, and to explore how modern formulation and delivery techniques can enhance the clinical relevance and overall success of VLP vaccines. Expert commentary: The role of formation science, with an emphasis on the diversity of immune responses induced by VLP, is underrepresented amongst clinical trials for VLP vaccines. Harnessing such diversity, particularly through the use of combinations of select excipients and adjuvants, will be paramount in the development of VLP vaccines.


id: cord-006947-nrzjedhi
title: Nano- and microparticles at fluid and biological interfaces
author: Dasgupta, S
date: 2017-09-20
txt: ./txt/cord-006947-nrzjedhi.txt
cache: ./cache/cord-006947-nrzjedhi.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7104866/
doi: 10.1088/1361-648x/aa7933
summary:
  Keywords: membranes, nanoparticles, capillary interactions, lipid bilayers, emulsions, viruses, interfaces (Some figures may appear in colour only in the online journal) For micrometer-sized particles, the contrib ution of the line tension is negligible; the trapping energy is proportional to the liquid-vapor interface tension γ v and decreases with decreasing contact angle, see figure 6 . Reprinted with permission from [78] copyright of The Royal Society of Chemistry (f) Deformation profiles of an interface around a particle with Hauser''s cube shape at contact angle θ = 56.28 Whether a particle stabilizes or destabilizes a film furthermore depends on the orientation that the particle assumes at the interface [102] , see section 2.4. Because the energy for an orientation where only one spherical particle is in contact with an interface does not depend on the tilt angle, an arrest in such a state could be caused by surface roughness.

abstract:
  Systems with interfaces are abundant in both technological applications and biology. While a fluid interface separates two fluids, membranes separate the inside of vesicles from the outside, the interior of biological cells from the environment, and compartmentalize cells into organelles. The physical properties of interfaces are characterized by interface tension, those of membranes are characterized by bending and stretching elasticity. Amphiphilic molecules like surfactants that are added to a system with two immiscible fluids decrease the interface tension and induce a bending rigidity. Lipid bilayer membranes of vesicles can be stretched or compressed by osmotic pressure; in biological cells, also the presence of a cytoskeleton can induce membrane tension. If the thickness of the interface or the membrane is small compared with its lateral extension, both can be described using two-dimensional mathematical surfaces embedded in three-dimensional space. We review recent work on the interaction of particles with interfaces and membranes. This can be micrometer-sized particles at interfaces that stabilise emulsions or form colloidosomes, as well as typically nanometer-sized particles at membranes, such as viruses, parasites, and engineered drug delivery systems. In both cases, we first discuss the interaction of single particles with interfaces and membranes, e.g. particles in external fields, non-spherical particles, and particles at curved interfaces, followed by interface-mediated interaction between two particles, many-particle interactions, interface and membrane curvature-induced phenomena, and applications.


id: cord-007131-q0cy9dej
author: Shimazaki, Yasuhiro
date: 2006-05-05
txt: ./txt/cord-007131-q0cy9dej.txt
cache: ./cache/cord-007131-q0cy9dej.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7108767/
doi: 10.1063/1.2204538
summary:
  It is important to predict the environment around the breathing human because inhalation of virus (avian influenza, SARS) is recently severe worldwide problem, and air pollution caused by diesel emission particle (DEP) and asbestos attract a great deal of attention. In the present study, three‐dimensional numerical simulation was carried out to predict unsteady flows around a breathing human and how suspended particulate matter (SPM, diameter∼1 μm) reaches the human nose in inhalation and exhalation. In the calculation, we find out smaller breathing angle and the closer distance between the human nose and pollutant region are effective in the inhalation of SPM. (3) The particle captured efficiency tends to become higher and particles tend to reach the human nose faster as the breathing angle becomes smaller. (3) The particle captured efficiency tends to become higher and particles tend to reach the human nose faster as the breathing angle becomes smaller.

title:
  Three‐dimensional Numerical Simulation of Gas‐particulate Flow around Breathing Human and Particulate Inhalation

abstract:
  It is important to predict the environment around the breathing human because inhalation of virus (avian influenza, SARS) is recently severe worldwide problem, and air pollution caused by diesel emission particle (DEP) and asbestos attract a great deal of attention. In the present study, three‐dimensional numerical simulation was carried out to predict unsteady flows around a breathing human and how suspended particulate matter (SPM, diameter∼1 μm) reaches the human nose in inhalation and exhalation. In the calculation, we find out smaller breathing angle and the closer distance between the human nose and pollutant region are effective in the inhalation of SPM.


id: cord-007363-h8xa83nw
author: Yan, Yihuan
date: 2019-05-09
txt: ./txt/cord-007363-h8xa83nw.txt
cache: ./cache/cord-007363-h8xa83nw.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7111533/
doi: 10.1007/s42757-019-0016-z
summary:
  On the other hand, the Eulerian approach, which treats the dispersed particles as a continuous phase, has gained relatively higher reputation in saving computational cost and simulating pollutant concentration, whilst it cannot predict particle motions or provide particle transport tracks. Rim and Novoselac (2009) once investigated experimentally the airflow field and human thermal plume in a displacement ventilated room containing a seated manikin, which had a very similar setup with the model of this study. In terms of the PSI-C method, the computational domain needs firstly to be divided into a number of small control volumes (or cells, which are for post-processing purpose only and are different to the computational meshes), then a number of particle trajectories are selected for concentration calculation from the numerical results yielded from the E-L model. Both the Eulerian-Eulerian model and the Eulerian-Lagrangian model were employed in this study to simulate particulate contaminant transport in a displacement ventilated room containing a thermal manikin.

title:
  Numerical investigation of indoor particulate contaminant transport using the Eulerian-Eulerian and Eulerian-Lagrangian two-phase flow models

abstract:
  Transport of micron particles in a displacement ventilated room was simulated using both the Eulerian-Eulerian model and the Eulerian-Lagrangian model. The same inter-phase action mechanisms were included in both models. The models were compared against each other in the aspects of air velocity, particle concentration, and particle-wall interactions. It was found that the two models have similar accuracy in predicting the airflow field while each of them has its own advantage and drawback in modelling particle concentration and particle-wall interactions. The E-E model is capable of providing a mechanistic description of the inter-phase interactions, whilst the E-L model has obvious advantage in modelling particle-wall interactions. Advices were given for choosing an appropriate model for modelling particulate contaminant transport in indoor environments.


id: cord-008454-8brxpotx
title: Diagnostic Virology Using Electron Microscopic Techniques
author: Field, Anne M.
date: 2008-04-09
txt: ./txt/cord-008454-8brxpotx.txt
cache: ./cache/cord-008454-8brxpotx.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7131171/
doi: 10.1016/s0065-3527(08)60432-7
summary:
  The morphology of negatively stained virus particles is sufficient for grouping purposes but it is necessary to use immune electron microscopy (IEM) to differentiate morphologically identical but antigenically distinct viruses. Virus particles are sometimes present in such large numbers in clinical specimens that they can be detected directly by electron microscopy and negative staining methods in particular can be used to provide a rapid diagnosis. Immune electron microscopy on sectioned material presents considerable technical difficulties and viral content of tissue homogenates may be too low for negative stain IEM so a virus seen in the tissue cannot always be sufficiently well identified for diagnostic purposes. Similarly, thin section studies on livers of marmosets infected with hepatitis A virus showed cytoplasmic picornavirus-like particles which could be extracted for use as antigen to detect antibodies by negative stain IEM (Provost et al., 197513) and by complement fixation (Provost et al., 1975a) .

abstract:
  This chapter illustrates the development of the use of electron microscopy in viral diagnosis. The field covered is confined to medical viral diagnosis, but parallel developments have taken place in both veterinary and botanical fields and techniques derived from both these sources are also included where relevant. It is reported that the scanning transmission mode of operation, which can induce image contrast changes electronically, may enhance studies with unstained sections and perhaps facilitate thin section immune electron microscopy (IEM). The application of negative stain IEM has been particularly useful for the study of the antigenic nature of some of the newly discovered noncultivable viruses. Viral antigens can also be detected in thin sections of infected cells by IEM with suitably labeled specific antibodies. Confirmation of viral infection by electron microscopy on tissues originally processed for light microscopy is also frequently useful.


id: cord-008917-ek8rp4kh
title: CORONAVIRUS-LIKE PARTICLES IN DIARRHOEA STOOLS
author: Caul, E.O.
date: 1980-12-06
txt: ./txt/cord-008917-ek8rp4kh.txt
cache: ./cache/cord-008917-ek8rp4kh.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7134874/
doi: 10.1016/s0140-6736(80)92509-x
abstract: nan
summary:
  971) report that they have seen pleomorphic coronavirus-like particles in a specimen of human faeces and postulate that these may have derived from an intestinal yeast-like organism and suggest Blastocystis (now believed to be a protozoon 1). Moreover, in general, there exists a large species variation in therapeutic or toxic effects of chemical substances, and additionally an interspecies difference exists in drug metabolism and pharmacological response, especially to liposoluble drugs 2-all of which points should be considered when extrapolating our findings in rats to man. Nevertheless, we feel very strongly that those drugs which evoke a positive response in our rat model are potentially harmful in the hereditary porphyrias and should be avoided. In our experience, 25% of patients with premyxoedema have a normal basal TSH but exaggerated response to thyrotrophin-releasing hormone (TRH). Coronavirus particles in faeces from patients with gastroenteritis


id: cord-009769-cql7go58
author: Chhabra, Sudhaker
date: 2011-07-01
txt: ./txt/cord-009769-cql7go58.txt
cache: ./cache/cord-009769-cql7go58.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164511/
doi: 10.1115/1.4004362
summary:
  In order to characterize alveolar flow patterns and inhaled particle transport during synchronous ventilation, we have conducted measurements for a range of dimensionless parameters physiologically relevant to the upper acini. The current work focuses on the effect of geometric and dynamic parameters on fluid flow and particle transport in the upper acini (respiratory bronchioles). Since the alveolar geometry, Reynolds and Womersley numbers, and the resulting flow patterns vary along the acinar tree, fluid mixing and dispersion, and particle transport may exhibit differences across acinar generations. Despite an overall similarity between the flow patterns, the alveolar fluid exhibits smaller velocities for smaller DV/V at each time step during a complete breathing cycle: the inward/outward velocities during peak inhalation/exhalation are smaller and show that particle deposition is highest for DV/V 5 0.5 after 5 and 10 cycles. This paper presents alveolar flow patterns and particle transport results for a range of geometric and dynamic parameters within the acinar region of the human lung.

title:
  Flow and Particle Dispersion in Lung Acini: Effect of Geometric and Dynamic Parameters During Synchronous Ventilation

abstract:
  The human lung comprises about 300 million alveoli which are located on bronchioles between the 17th to 24th generations of the acinar tree, with a progressively higher population density in the deeper branches (lower acini). The alveolar size and aspect ratio change with generation number. Due to successive bifurcation, the flow velocity magnitude also decreases as the bronchiole diameter decreases from the upper to lower acini. As a result, fluid dynamic parameters such as Reynolds (Re) and Womersley (α) numbers progressively decrease with increasing generation number. In order to characterize alveolar flow patterns and inhaled particle transport during synchronous ventilation, we have conducted measurements for a range of dimensionless parameters physiologically relevant to the upper acini. Acinar airflow patterns were measured using a simplified in vitro alveolar model consisting of a single transparent elastic truncated sphere (representing the alveolus) mounted over a circular hole on the side of a rigid circular tube (representing the bronchiole). The model alveolus was capable of expanding and contracting in-phase with the oscillatory flow through the bronchiole thereby simulating synchronous ventilation. Realistic breathing conditions were achieved by exercising the model over a range of progressively varying geometric and dynamic parameters to simulate the environment within several generations of the acinar tree. Particle image velocimetry was used to measure the resulting flow patterns. Next, we used the measured flow fields to calculate particle trajectories to obtain particle transport and deposition statistics for massless and finite-size particles under the influence of flow advection and gravity. Our study shows that the geometric parameters (β and ΔV/V) primarily affect the velocity magnitudes, whereas the dynamic parameters (Re and α) distort the flow symmetry while also altering the velocity magnitudes. Consequently, the dynamic parameters have a greater influence on the particle trajectories and deposition statistics compared to the geometric parameters. The results from this study can benefit pulmonary research into the risk assessment of toxicological inhaled aerosols, and the pharmaceutical industry by providing better insight into the flow patterns and particle transport of inhalable therapeutics in the acini.


id: cord-009825-6cargkwy
title: Indoor bioaerosol dynamics
author: Nazaroff, William W
date: 2014-12-27
txt: ./txt/cord-009825-6cargkwy.txt
cache: ./cache/cord-009825-6cargkwy.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7165847/
doi: 10.1111/ina.12174
summary:
  The review summarizes knowledge about size‐dependent particle deposition in different regions of the respiratory tract, techniques for measuring indoor bioaerosols, and evidence for diseases caused by airborne exposure to bioaerosols. Then, the article proceeds to discuss several additional processes that can affect indoor bioaerosol levels: deposition onto room surfaces, bioaerosol intrusion from outdoor air, indoor emission sources, and other factors, including bioaerosol control, airborne growth and decay, and indoor transport and mixing. In the summaries to follow, I highlight several field-sampling studies whose results provide important clues about bioaerosol concentrations, associated particle-size distributions, and potential influencing factors. The importance of deposition as a removal mechanism for airborne bioaerosol particles can be explored by comparing b to the air exchange rate. For these larger particles, deposition is an important mechanism influencing the fate of bioaerosols even for buildings with relatively high air exchange rates.

abstract:
  Inhaling indoor air is the primary means by which humans are exposed to bioaerosols. Considering bacteria, fungi, and viruses, this study reviews the dynamic processes that govern indoor concentrations and fates of biological particulate material. Bioaerosol behavior is strongly coupled to particle size; this study emphasizes the range 0.1–10 μm in aerodynamic diameter. The principle of material balance allows concentrations to be determined from knowledge of important source and removal processes. Sources reviewed here include outdoor air introduced by air exchange plus indoor emission from occupants, occupant activities, and moldy materials. Important mechanisms that remove bioaerosols from indoor air include air exchange, deposition onto indoor surfaces, and active filtration. The review summarizes knowledge about size‐dependent particle deposition in different regions of the respiratory tract, techniques for measuring indoor bioaerosols, and evidence for diseases caused by airborne exposure to bioaerosols. Future research challenges and opportunities are highlighted.


id: cord-010022-e19vm7vp
title: Negative Staining and Immune Electron Microscopy as Techniques for Rapid Diagnosis of Viral Agents
author: RIEPENHOFF‐TALTY, M.
date: 2006-12-16
txt: ./txt/cord-010022-e19vm7vp.txt
cache: ./cache/cord-010022-e19vm7vp.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7168088/
doi: 10.1111/j.1749-6632.1983.tb22228.x
abstract: nan
summary:
  This technique was termed immune electron microscopy and the virus-like particles were called Norwalk agent.* It is estimated that these two agents account for 50% of hitherto undiagnosed gastroenteritis around the world. Even more recently electron microscopy and immune electron microscopy have been shown to be critical techniques for detecting new virus-like particles associated with gastroenteritis in humans. Caliciviruses, also approximately 28 to 30 nm in size, have been associated with diarrhea in human infants according to several Additional small round viruses (27 to 40 nm) have been distinguished by electron microscopy in fecal specimens from infants with nonbacterial gastroenteritis. Visualization by immune electron microscopy of a 27-nm particle associated with acute infectious nonbacterial gastroenteritis Small round virus-like particles associated with acute gastroenteritis in Japanese children Detection by immune electron microscopy of 26-27 nm virus-like particles associated with two family outbreaks of gastroenteritis


id: cord-010910-hz2vyw6c
author: Huang, Xinyue
date: 2020-01-08
txt: ./txt/cord-010910-hz2vyw6c.txt
cache: ./cache/cord-010910-hz2vyw6c.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7223038/
doi: 10.1007/s11051-019-4720-1
summary:
  title: Macrophage-like THP-1 cells show effective uptake of silica nanoparticles carrying inactivated diphtheria toxoid for vaccination Porous silica has been identified as an effective adjuvant for more than a decade, and we have therefore investigated the take up rate by an immortalized macrophage-like cell line of a number of mesoporous silica nanoparticles (MSNPs) with differing diameter and pore size. Our previous work compared the antigen loading and unloading capacity of mesoporous silica nanoparticles (MSNPs), with a variety of different pore sizes, and external diameters (Huang et al. To assess the uptake of the different silica nanoparticles, and to determine whether this was affected by size, porosity or loading, we tested the ability of the particles to be taken up into macrophage-like cells. We investigated a range of sizes of silica nanoparticles to determine the effect on uptake by THP-1 macrophage-like cells.

title:
  Macrophage-like THP-1 cells show effective uptake of silica nanoparticles carrying inactivated diphtheria toxoid for vaccination

abstract:
  Nanoparticles may be used in vaccinology as an antigen delivery and/or an immunostimulant to enhance immunity. Porous silica has been identified as an effective adjuvant for more than a decade, and we have therefore investigated the take up rate by an immortalized macrophage-like cell line of a number of mesoporous silica nanoparticles (MSNPs) with differing diameter and pore size. The MSNPs were synthesized using a sol-gel reaction and post-synthesis removal of the template. The MSNPs showed a clear distribution in take up rate peaking at 217 nm, whereas a comparison with solid spherical nanoparticles showed a similar distribution peaking at 377 nm. The MSNPs were investigated before and after loading with antigen. Diphtheria toxoid was used as a proof-of-concept antigen and showed a peak macrophage internalization of 53.42% for loaded LP3 particles which had a diameter of 217.75 ± 5.44 nm and large 16.5 nm pores. Optimal MSNP sizes appeared to be in the 200–400 nm range, and larger pores showed better antigen loading. The mesoporous silica particles were shown to be generally biocompatible, and cell viability was not altered by the loading of particles with or without antigen. [Figure: see text]


id: cord-022504-tk7v4hoj
title: Environmental and safety issues with nanoparticles
author: nan
date: 2012-03-16
txt: ./txt/cord-022504-tk7v4hoj.txt
cache: ./cache/cord-022504-tk7v4hoj.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7158170/
doi: 10.1016/b978-0-444-56336-1.50007-2
abstract: nan
summary:
  During the process, large volumes of ultrapure water are consumed to clean the surface of the wafer, which generates large quantity of CMP wastewater typically having high solid content resulting from slurry abrasive particles of SiO 2 , Al 2 O 3 , or CeO 2 , depending on the nature of the CMP application. 7.2.6.2 Industrial processes with cleanrooms Cleanrooms and associated controlled environments (e.g., in the case of an ISO Class 3 cleanroom, the maximum permissible airborne particle concentration is less than 10 3 particles/m 3 for particles with the size of 0.1 m or larger, while the airborne particle concentration in ordinary indoor environments is on the order of 10 9 particles/m 3 or higher) are usually adopted to avoid particle contamination in industrial processes where precision products such as engineered nanoparticles, semiconductors, and other electronic or optical devices are fabricated because the deposition of particles onto product surfaces causes their yield reduction and quality deterioration.


id: cord-022538-1g9kmpdi
title: ENVIRONMENTAL AND SAFETY ISSUES WITH NANOPARTICLES
author: Makino, Hisao
date: 2008-05-20
txt: ./txt/cord-022538-1g9kmpdi.txt
cache: ./cache/cord-022538-1g9kmpdi.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7158284/
doi: 10.1016/b978-044453122-3.50010-6
summary:
  During the process, large volumes of ultrapure water are consumed to clean the surface of the wafer, which generates large quantity of CMP wastewater typically having high solid content resulting from slurry abrasive particles of SiO 2 , Al 2 O 3 , or CeO 2 , depending on the nature of the CMP application. Cleanrooms and associated controlled environments (e.g., in the case of an ISO Class 3 cleanroom, the maximum permissible airborne particle concentration is less than 10 3 particles/m 3 for particles with the size of 0.1 m or larger, while the airborne particle concentration in ordinary indoor environments is on the order of 10 9 particles/m 3 or higher) are usually adopted to avoid particle contamination in industrial processes where precision products such as engineered nanoparticles, semiconductors, and other electronic or optical devices are fabricated because the deposition of particles onto product surfaces causes their yield reduction and quality deterioration.

abstract:
  This chapter evaluates the relationship between nanoparticles and the environment, and describes the trouble caused by nanoparticles as well as the safety issues. The relationship between nanoparticles and the environment is clarified from the viewpoint of the kind of influence nanoparticles generated either artificially or naturally have on the environment, such as in atmosphere, groundwater, wastewaters, and exhaust gases. Indoor nanoparticles originate from the several sources such as products of chemical reactions, nonvolatile residues (NVRs) of liquid droplets, printers/photocopiers, combustion, bioaerosols, and infiltration of outdoor air. The influence of nanoparticles on the indoor environment is discussed in the chapter. It describes the sources of nanoparticle generation in general industrial processes such as grinding processes, and in cleanroom or controlled environment industrial processes, such as exhaled air, ionizers, and haze by chemical reaction on solid surfaces. The chapter discusses safety issues related to nanoparticles such as possibility of dust explosion, health risks and biological effects of nanoparticle materials such as carbon nanotubes, fullerenes, nanosized metal oxides, and carbon black. The chapter also discusses methods for removing nanoparticles from gas and liquid as technology to control the influence of nanoparticles on the environment.


id: cord-031037-up0z1yaf
title: A New Natural Defense Against Airborne Pathogens
author: Edwards, David
date: 2020-07-07
txt: ./txt/cord-031037-up0z1yaf.txt
cache: ./cache/cord-031037-up0z1yaf.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7453358/
doi: 10.1017/qrd.2020.9
summary:
  In an open-labeled randomized controlled human study of 68 subjects with common cold infections including rhinoviruses and coronaviruses, as well as enterovirus and influenza A virus, nasal delivery of 2-3% hypertonic saline 2-8 times a day (median thricea-day) significantly lowered duration of illness, as well as use of over-the-counter medications, household transmissions, and viral shedding (Ramalingam et al., 2019) . Suppression of bioaerosol by delivery of the FEND aerosol relative to placebo control occurred particularly at the high dose (see Supplemental Material for lower doses), as shown in Fig. 5a , with six of the eight subjects breathing out over the duration of 12 h post treatment, a significantly lower mean particle count per liter relative to placebo (p < 0.05). Our finding that nasal inspiration of FEND in a group of 10 healthy human subjects reduces exhaled particles between 45 and 99% by way of an aerosol too large to penetrate the lower airways (Figs 8 and 9) , suggests that the upper airways are a primary source of expired bioaerosol.

abstract:
  We propose the nasal administration of calcium-enriched physiological salts as a new hygienic intervention with possible therapeutic application as a response to the rapid and tenacious spread of COVID-19. We test the effectiveness of these salts against viral and bacterial pathogens in animals and humans. We find that aerosol administration of these salts to the airways diminishes the exhalation of the small particles that face masks fail to filter and, in the case of an influenza swine model, completely block airborne transmission of disease. In a study of 10 human volunteers (5 less than 65 years and 5 older than 65 years), we show that delivery of a nasal saline comprising calcium and sodium salts quickly (within 15 min) and durably (up to at least 6 h) diminishes exhaled particles from the human airways. Being predominantly smaller than 1 μm, these particles are below the size effectively filtered by conventional masks. The suppression of exhaled droplets by the nasal delivery of calcium-rich saline with aerosol droplet size of around 10 μm suggests the upper airways as a primary source of bioaerosol generation. The suppression effect is especially pronounced (99%) among those who exhale large numbers of particles. In our study, we found this high-particle exhalation group to correlate with advanced age. We argue for a new hygienic practice of nasal cleansing by a calcium-rich saline aerosol, to complement the washing of hands with ordinary soap, use of a face mask, and social distancing.


id: cord-032161-sbtu48c2
title: Particle and Size Distribution
author: Xu, Zhonglin
date: 2013-08-07
txt: ./txt/cord-032161-sbtu48c2.txt
cache: ./cache/cord-032161-sbtu48c2.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498888/
doi: 10.1007/978-3-642-39374-7_1
summary:
  • The summit point can be obtained from the lognormal distribution curve of light scattering probably depends on the particle area or volume; when the problem is related to the light refraction property, arithmetic average diameter D 1 should be used, because this property depends on the dimension of particle length. If particle diameters follow normal distribution, a straight line will be obtained when the abscissa represents the particle size and the ordinate means the cumulative distribution frequency. If particle size distribution is quite different from normal distribution, such as an extreme case shown in Fig. 1 .23 which represents the sampled particle size distribution curve in the cleanroom air, large deviation could be found when the lognormal probability graph paper is plotted.

abstract:
  The purpose of air cleaning technology is to get rid of airborne particles as much as possible. Gaseous medium containing dispersed airborne particles is one kind of dispersed systems, which is termed as aerosol.


id: cord-032165-nyj72o21
title: Movement of Indoor Fine Particle
author: Xu, Zhonglin
date: 2013-08-08
txt: ./txt/cord-032165-nyj72o21.txt
cache: ./cache/cord-032165-nyj72o21.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498892/
doi: 10.1007/978-3-642-39374-7_6
summary:
  So the total deposition amount of particles on the surface with area 1 cm 2 per hour can be obtained in the cleanroom, where the airborne particle concentration is 1,000 pc/L and the air velocity is 0.3 m/s. Table 6 .11 shows the comparison of measured data and calculated data about the deposition amount of particles on the surface with unit area in the room with air supply. In the flowing air, small particles will follow the movement of airflow with the same velocity [10] . From the above analysis, when there is air supply with a certain speed in the room where the indoor area is very small, the buoyant flow generated will cause very large influence, when the fluorescent lamp was installed at a relative high position of the vertical wall (such as above 1.5 m).

abstract:
  Only when indoor airborne particles move towards the nearby of the precision product and then deposit onto the sensitive area, damage may be caused for the product. So it is important to understand the mechanism of particle movement and deposition for the control of environment.


id: cord-032174-qu5mm9r1
title: Sampling Theory
author: Xu, Zhonglin
date: 2013-08-14
txt: ./txt/cord-032174-qu5mm9r1.txt
cache: ./cache/cord-032174-qu5mm9r1.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498907/
doi: 10.1007/978-3-642-39374-7_16
summary:
  The reading value of the flowmeter 20 L/min is the indication value in the calibration condition, so the actual flow rate q 1 through the flowmeter should be According to the actual collected particle concentration 18.31 L/min after correction, the calculated indoor particle concentration is 371.4#/L, so the indoor air cleanliness level does not reach Class 7. The example of the application of Fig. 16 .10 is shown as follows: When the particle counter with small sampling volume 2.83 L/min is used to detect particles with diameter 5 μm (only for this particle size) from airflow with velocity 0.5 m/s, should any correction be made? For the common particle counters with large, medium, and small sampling flow rates at home and abroad, Reynolds numbers Re in the sampling tube are shown in Table 16 .3. So the following requirement must be satisfied: For particle counter with medium and low sampling flow rates, calculation results are shown in Table 16 .4.

abstract:
  In order to ensure the reliability of the measurement results of particle concentration, except for the reasonable detecting method and the sophisticated detection equipment, the correct sampling principle to minimize the sampling errors must be followed, which requires that people who carry out the measurement should master the correct sampling theory.


id: cord-032188-y02b92pe
title: Characteristics of Air Filters
author: Xu, Zhonglin
date: 2013-08-14
txt: ./txt/cord-032188-y02b92pe.txt
cache: ./cache/cord-032188-y02b92pe.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498932/
doi: 10.1007/978-3-642-39374-7_4
summary:
  When the air filter is operated under lower flow rate, the efficiency increases and the pressure drop decreases. This is because the dust deposited is comparatively large for air filters with low efficiency and the filter medium is sparse, which will cause particles to penetrate when pressure drop increases and cause deposited particles to rebound and resuspend. Particle counting efficiency of glass fibrous medium-efficiency air filter (d f ¼ 16 μm, H ¼ 20 mm, α ¼ 0.037, v ¼ 0.28 m/s) with atmospheric dust was performed at Institute of HVAC of China Academy of Building Research, which is shown in Table 4 .13. The pressure drop of nuclear microporous membrane is large, so it is not suitable for common air filter, but it is very useful for special filtration (for the application field where particles with diameter larger than certain value are not allowed to penetrate).

abstract:
  Air filter is the main equipment in the field of air cleaning technology, and it is an indispensible equipment to create the clean air environment. So it is necessary to know the characteristic of air filters and its design principle so as to use it correctly and effectively.


id: cord-102908-sr7j8z9c
author: Mersmann, Sophia F.
date: 2020-07-24
txt: ./txt/cord-102908-sr7j8z9c.txt
cache: ./cache/cord-102908-sr7j8z9c.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1101/2020.07.23.217745
doi: 10.1101/2020.07.23.217745
summary:
  We used differential binary labelling and statistical modelling to extract estimates of stoichiometry, our strategy is outlined in Figure 1 ; note that this approach can be generalised to apply to many other multi-component systems (i.e. how many protein x are found in assembly y?). As described above, our experimental design utilizes antibody labelled with spectrally distinct dyes allowing binary scoring of individual virus particles as positive if they interact with at least one Ab B molecule ( Figure 1 ). We have demonstrated quantitative analysis of 9C12 interaction with individual Adv particles ( Figure 3) ; we have confirmed that differential labelling of antibody does not bias binding ( Figure 4A & B) ; and that we could detect single molecules of 9C12 Biotin allowing discrimination of positive and negative AdV-9C12 complexes ( Figure 4C & D). However, using stoichiometric estimates to calibrate fluorescent data revealed population heterogeneity with a small proportion of virus particles binding ∼200 antibody molecules.

title:
  Learning to count: determining the stoichiometry of bio-molecular complexes using fluorescence microscopy and statistical modelling

abstract:
  Cellular biology occurs through myriad interactions between diverse molecular components, many of which assemble in to specific complexes. Various techniques can provide a qualitative survey of which components are found in a given complex. However, quantitative analysis of the absolute number of molecules within a complex (known as stoichiometry) remains challenging. Here we provide a novel method that combines fluorescence microscopy and statistical modelling to derive accurate molecular counts. We have devised a system in which a given biomolecule is differentially labelled with spectrally distinct fluorescent dyes (label A or B), which are then mixed such that B-labelled molecules are vastly outnumbered by those with label A. Complexes, containing this component, are then simply scored as either being positive or negative for label B. The frequency of positive complexes is directly related to the stoichiometry of interaction and molecular counts can be inferred by statistical modelling. We demonstrate this method using complexes of Adenovirus particles and monoclonal antibodies, achieving counts that are in excellent agreement with previous estimates. Beyond virology, this approach is readily transferable to other experimental systems and, therefore, provides a powerful tool for quantitative molecular biology. The statistical models used in our analysis are available here: https://github.com/sophiamersmann/molecular-counting, the raw data used for molecular counting can be found here: 10.5281/zenodo.3955142.


id: cord-222700-yof5x4ct
title: Tunable particle separation via deterministic absolute negative mobility
author: Slapik, Aleksandra
date: 2020-08-31
txt: ./txt/cord-222700-yof5x4ct.txt
cache: ./cache/cord-222700-yof5x4ct.txt
extension: .txt
mime: text/plain
url: https://arxiv.org/pdf/2008.13706v1.pdf
doi: nan
summary:
  We reveal an efficient separation strategy via the counterintuitive effect of negative mobility when particles of a given size are transported in a direction opposite to the applied constant force. Motivated by the large size range encountered in biochemical applications, a crucial result of this work is a demonstration of a tunable separation strategy, in which the size of the particle undergoing separation may be effectively controlled by variation of the parameters characterizing the external force applied to the particle, e.g. the magnitude of the static bias. Therefore, in contrast, in this work we harvest the negative mobility effect to develop the particle separation strategy in which the particle size intended for isolation will be controlled by changing only the parameters characterizing the externally applied force, namely, the static bias f or the amplitude a or the frequency ω of the harmonic driving.

abstract:
  Particle isolation techniques are in the spotlight of many areas of science and engineering. In food industry, a harmful bacterial activity can be prevented with the help of separation schemes. In health care, isolation techniques are used to distinguish cancer and healthy cells or in therapy for Alzheimer's and Parkinson's diseases. We consider a cloud of Brownian particles of different sizes moving in a periodic potential and subjected to an unbiased driving as well as a constant force. We reveal an efficient separation strategy via the counterintuitive effect of negative mobility when particles of a given size are transported in a direction opposite to the applied constant force. We demonstrate a tunable separation solution in which size of the particle undergoing separation may be controlled by variation of the parameters of the external force applied to the system. This approach is an important step towards the development of point-of-care lab-on-a-chip devices.


id: cord-233294-jnic4o2j
author: Ravazi, Maryam
date: 2020-08-19
txt: ./txt/cord-233294-jnic4o2j.txt
cache: ./cache/cord-233294-jnic4o2j.txt
extension: .txt
mime: text/plain
url: https://arxiv.org/pdf/2008.10998v1.pdf
doi: nan
summary:
  We studied the effects of air purification (on/off), door condition (open/close), and particle sizes on the temporal concentration distribution of particles. Furthermore, research on the effects of air purifiers is needed to develop guidelines and protocols to reduce waiting time between patients and ensure the safe operation of dental offices. Figure 4a shows the lowest particle concentrations in the room when the high-speed air purifier is running from the beginning of the operation. The particle removal time varies with particle size although the air purifier and open door help reduce the concentration of all-size particles in the generation zone. • In the worst-scenario scenario with no protection system in the closed-door office and continuous high-speed drilling, it takes 95 min for 0.5 m particles to return to background level and that it takes a shorter time for particles larger than 0.5 m to be removed from the air. Running high-speed air purifier at the beginning of the operation is the most effective scenario in reducing airborne particle concentrations.

title:
  In situ Measurement of Airborne Particle Concentration in a Real Dental Office: Implications for Disease Transmission

abstract:
  Recent guidelines by WHO recommend delaying non-essential oral health care amid COVID-19 pandemic and call for research on aerosol generated during dental procedures. Thus, this study aims to assess the mechanisms of dental aerosol dispersion in dental offices and to provide recommendations based on a quantitative study to minimize infection transmission in dental offices. The spread and removal of aerosol particles generated from dental procedures in a dental office are measured near the source and at the corner of the office. We studied the effects of air purification (on/off), door condition (open/close), and particle sizes on the temporal concentration distribution of particles. The results show that in the worst-scenario scenario it takes 95 min for 0.5 um particles to settle, and that it takes a shorter time for the larger particles. The indoor air purifier tested expedited the removal time at least 6.3 times faster than the scenario air purifier off. Airborne particles may be transported from the source to the rest of the room, even when the particle concentrations in the generation zone return to the background level. These results are expected to be valuable to related policy making and technology development for infection disease control in dental offices and similar built environments.


id: cord-252147-bvtchcbt
title: Engineered Biological Entities for Drug Delivery and Gene Therapy: Protein Nanoparticles
author: Domingo-Espín, Joan
date: 2011-11-15
txt: ./txt/cord-252147-bvtchcbt.txt
cache: ./cache/cord-252147-bvtchcbt.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1016/b978-0-12-416020-0.00006-1
doi: 10.1016/b978-0-12-416020-0.00006-1
summary:
  Modular protein engineering, virus-like particles (VLPs), and other self-assembling entities are envisioned as modulatable novel protein nanoparticles able to include many desirable properties in the correct delivery of drugs and nucleic acids. 120 Modular fusion proteins that combine distinct functions required for cell type-specific uptake and intracellular delivery of DNA or drugs present an attractive approach for the development of self-assembling vectors for targeted gene or drug delivery. 215, 216 Although VLP-based vaccines have been primarily developed for their use against the corresponding virus, in the last decades genetic engineering or chemical modifications have been applied in order to generate chimeric VLPs. Thus, on the one hand, commonly short heterologous peptide epitopes or full proteins that are unable to form VLPs or that are unsafe for vaccination have been presented on surface-exposed loops or fused to N-or C-exposed termini of structural viral capsid proteins on VLPs. 154, 161, 210 Different HPV, 217-219 HBV, 220,221 parvovirus, 222, 223 and chimeric polyoma VLPs have been engineered 170, 175 and tested for different applications including vaccination against viral or bacterial diseases, against virus-induced tumors, and more recently, for immunotherapy of nonviral cancer.

abstract:
  The development of genetic engineering techniques has speeded up the growth of the biotechnological industry, resulting in a significant increase in the number of recombinant protein products on the market. The deep knowledge of protein function, structure, biological interactions, and the possibility to design new polypeptides with desired biological activities have been the main factors involved in the increase of intensive research and preclinical and clinical approaches. Consequently, new biological entities with added value for innovative medicines such as increased stability, improved targeting, and reduced toxicity, among others have been obtained. Proteins are complex nanoparticles with sizes ranging from a few nanometers to a few hundred nanometers when complex supramolecular interactions occur, as for example, in viral capsids. However, even though protein production is a delicate process that imposes the use of sophisticated analytical methods and negative secondary effects have been detected in some cases as immune and inflammatory reactions, the great potential of biodegradable and tunable protein nanoparticles indicates that protein-based biotechnological products are expected to increase in the years to come.


id: cord-253092-igic5pxc
title: Multi-zone simulation of outdoor particle penetration and transport in a multi-story building
author: Lee, Byung Hee
date: 2016-12-20
txt: ./txt/cord-253092-igic5pxc.txt
cache: ./cache/cord-253092-igic5pxc.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1007/s12273-016-0340-1
doi: 10.1007/s12273-016-0340-1
summary:
  The objective of this study is to analyze outdoor particle penetration and transport, and their impact on indoor air, in a multi-zone and multi-story building using a CONTAMW simulation. The results of the particle simulation also indicated that the airflow characteristics, combined with deposition rates, cause the lower floors of a multi-story building to be exposed to higher fine particle concentrations compared with the upper floors of the building. A careful computer simulation study with reliable inputs for key simulation parameters, such as the particle penetration coefficient and deposition rate, may be capable of providing comprehensive insights for understanding particle transport in multi-story buildings. In this study, a field test on the reference building was conducted using the natural decay method to identify the particle size-resolved penetration coefficient and deposition rate; the obtained values were used as simulation parameters.

abstract:
  In areas with poor ambient air quality, indoor particle concentrations can be significantly affected by particulate matter originating outdoors. The indoor environments of multi-zone and multi-story buildings are affected differently by outdoor particles compared with single-family houses, because of the buildings’ more complicated airflow characteristics. The objective of this study is to analyze outdoor particle penetration and transport, and their impact on indoor air, in a multi-zone and multi-story building using a CONTAMW simulation. For the airflow and particle transport analysis, the building leakage, penetration coefficients, and deposition rates were determined by on-site experiments. The results of airflow simulations for cold winters show that outdoor air infiltrates through the lower part of building and exfiltrates from the upper part. The results of the particle simulation also indicated that the airflow characteristics, combined with deposition rates, cause the lower floors of a multi-story building to be exposed to higher fine particle concentrations compared with the upper floors of the building. The study demonstrated that the CONTAMW simulation can be useful in analyzing the impact of outdoor particles on indoor environments through the identification of key particle transport parameters and validated airflow simulations.


id: cord-253922-qjsd3whg
title: Shedding of “virus-like” particles in canine faeces
author: Hamilton, R. C.
date: 1995-09-30
txt: ./txt/cord-253922-qjsd3whg.txt
cache: ./cache/cord-253922-qjsd3whg.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/037811359500095R
doi: 10.1016/0378-1135(95)00095-r
summary:
  title: Shedding of "virus-like" particles in canine faeces Abstract Diarrhoeic faeces from about 500 dogs were examined by negative stain electron microscopy. As well as parvovirus, and some of the other recognised viral causes of gastroenteritis, unusual "virus-like" particles were observed in about 8% of the samples. An additional 74 samples of normal faeces yielded no "virus-like" particles. During this work we observed unusual "virus-like" particles similar to those recorded by Hamilton et al. The "virus-like" particles were usually spherical and had a thick wall which was penetrated by numerous pores (Fig. I ) . Parvovirus particles were observed in some samples containing the viruslike particles ( Fig. 8) We have observed these "virus-like" particles in diarrhoeic canine faeces from 198 1 to 1994. Perhaps the "virus-like" particles are some structures associated with bacteria or parasites in the gut of dogs. Viruses and virus-like particles in the faeces of dogs with and without diarrhoea

abstract:
  Abstract Diarrhoeic faeces from about 500 dogs were examined by negative stain electron microscopy. As well as parvovirus, and some of the other recognised viral causes of gastroenteritis, unusual “virus-like” particles were observed in about 8% of the samples. The particles were spherical, 100 nm to 300 nm in diameter, and surrounded by a thick wall penetrated by numerous pores. An additional 74 samples of normal faeces yielded no “virus-like” particles. We do not know the nature of these particles.


id: cord-255314-mqexsqzj
title: Impact of Health on Particle Size of Exhaled Respiratory Aerosols: Case‐control Study
author: Hersen, Guillaume
date: 2008-04-29
txt: ./txt/cord-255314-mqexsqzj.txt
cache: ./cache/cord-255314-mqexsqzj.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32313583/
doi: 10.1002/clen.200700189
summary:
  title: Impact of Health on Particle Size of Exhaled Respiratory Aerosols: Case‐control Study A setup composed of a modified hood connected to an electrical low pressure impactor, which allows for the study of a wide range of particle sizes (from 7 nm to 10 μm), has been developed in order to collect exhaled breaths. As a consequence, further research on the exhaled breath should be undertaken with symptomatic volunteers and would require the analysis of this wide range of particle sizes. In particular, it is not possible at present to determine the impact of volunteer health on the particle size of exhaled respiratory aerosols. The experimental approach consisted of firstly developing a system that allows measurement of fine particles exhaled from a greater numbers of volunteers (78 individuals), with and without, symptoms. Following this, the size differences between aerosols emitted by symptomatic volunteers and controls were determined.

abstract:
  Individuals with viral infection could possibly emit an infectious aerosol. The distinction between exhaled breaths of infected and healthy individuals should facilitate an understanding of the airborne transmission of infections. In this context, the present study is aimed at distinguishing healthy individuals from symptomatic ones by the study of their exhaled breath. A setup composed of a modified hood connected to an electrical low pressure impactor, which allows for the study of a wide range of particle sizes (from 7 nm to 10 μm), has been developed in order to collect exhaled breaths. This setup has been used with seventy eight volunteers. The results obtained using Principal Component Analysis (PCA) showed that exhaled breaths of individuals without symptoms have statistical similarities and are different from those of individuals with symptoms. This separation was made by the greater proportional emission by individuals with symptoms of particles collected on stages 3 (D (50) = 0.09 μm), 6 (D (50 )= 0.38 μm), 8 (D (50) = 0.95 μm), 10 (D (50 )= 2.40 μm), and 12 (D (50 )= 4.02 μm) of the impactor. There was not a specific size distribution obtained for the individuals with symptoms. As a consequence, further research on the exhaled breath should be undertaken with symptomatic volunteers and would require the analysis of this wide range of particle sizes.


id: cord-258118-j26v354r
author: Karuppal, Raju
date: 2020-05-16
txt: ./txt/cord-258118-j26v354r.txt
cache: ./cache/cord-258118-j26v354r.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S0972978X20301963?v=s5
doi: 10.1016/j.jor.2020.05.013
summary:
  Apart from the numerous chemicals, surgical smoke had been shown to harbour intact bacterial and virus particles especially COVID-19 in the current time. OBJECTIVE: To identify the inhalational, infectious, chemical, and mutagenic risks of surgical smoke and suggest evidence-based hazard reduction strategies. Heating of tissues causes vaporisation of protein and fat which results surgical smoke(2) which contain particles from combustion and numerous chemicals like hydrocarbons, acrylonitrile, phenols and fatty acids and biological particles, viruses, and bacteria which are known to be potentially hazardous. In COVID-19 outbreak scenario, the use of surgical diathermy has to be minimised or avoided due to the very high risk of viral spread among operating room personals. Multiple precautions like use of a standard surgical mask, laser or high filtration mask, masks coated with nanoparticles, operating room ventilation guidelines, and use of wall suction have been using to reduce the health hazards, but each one has its own limitations.

title:
  It is time for a more cautious approach to surgical diathermy, especially in COVID-19 outbreak: A schematic review

abstract:
  BACKGROUND: Many surgeons are unaware of the risks posed by the surgical diathermy. Apart from the numerous chemicals, surgical smoke had been shown to harbour intact bacterial and virus particles especially COVID-19 in the current time. OBJECTIVE: To identify the inhalational, infectious, chemical, and mutagenic risks of surgical smoke and suggest evidence-based hazard reduction strategies. Also to cogitate on the very high risk of viral spread spread by the use of surgical diathermy in COVID-19 outbreak. METHODS: A review of articles indexed for MEDLINE on PubMed using the keywords surgical smoke, diathermy, electrocautery, surgical smoke hazards, smoke evacuator, and guidelines for surgical smoke safety was performed. The review included evidences from 50 articles from the dermatology, surgery, infectious disease, obstetrics, and cancer biology literature. RESULTS: There are risks associated with surgical smoke. Although some surgeons were aware, majority were not keen in the hazard reduction strategies. CONCLUSION: Many chemical and biological particles have been found in surgical smoke. It is highly recommended to follow the standardised guidelines for surgical smoke safety. Surgical smoke carries full virus particle(such as COVID-19 virus), it is strongly recommended to minimise or avoid electrocautery during the COVID-19 outbreak.


id: cord-258762-vabyyx01
author: Garbey, Marc
date: 2020-07-27
txt: ./txt/cord-258762-vabyyx01.txt
cache: ./cache/cord-258762-vabyyx01.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.3390/ijerph17155404
doi: 10.3390/ijerph17155404
summary:
  To address the clinical implication over a long period of time, the systems approach is built upon previous work on multi-scale modeling of surgical flow in a large operating room suite and takes into account human behavior factors. Clinical environments are too complex to model with the traditional modeling method of airflow and particle transportation because both the source intensity of surgical smoke [19] as well as the mechanism of propagation via door openings [20] are largely dominated by human factors. The indoor air quality is a linear set of differential equations that will be slightly more complex than a standard compartment model since the coefficient will be stochastic, the sources and output/leaks of the particles term will have a time delay built in, and the hallway will require a transport equation.

title:
  A Systems Approach to Assess Transport and Diffusion of Hazardous Airborne Particles in a Large Surgical Suite: Potential Impacts on Viral Airborne Transmission

abstract:
  Airborne transmission of viruses, such as the coronavirus 2 (SARS-CoV-2), in hospital systems are under debate: it has been shown that transmission of SARS-CoV-2 virus goes beyond droplet dynamics that is limited to 1 to 2 m, but it is unclear if the airborne viral load is significant enough to ensure transmission of the disease. Surgical smoke can act as a carrier for tissue particles, viruses, and bacteria. To quantify airborne transmission from a physical point of view, we consider surgical smoke produced by thermal destruction of tissue during the use of electrosurgical instruments as a marker of airborne particle diffusion-transportation. Surgical smoke plumes are also known to be dangerous for human health, especially to surgical staff who receive long-term exposure over the years. There are limited quantified metrics reported on long-term effects of surgical smoke on staff’s health. The purpose of this paper is to provide a mathematical framework and experimental protocol to assess the transport and diffusion of hazardous airborne particles in every large operating room suite. Measurements from a network of air quality sensors gathered during a clinical study provide validation for the main part of the model. Overall, the model estimates staff exposure to airborne contamination from surgical smoke and biological material. To address the clinical implication over a long period of time, the systems approach is built upon previous work on multi-scale modeling of surgical flow in a large operating room suite and takes into account human behavior factors.


id: cord-261908-olcuq6tm
title: Propagation of Respiratory Aerosols by the Vuvuzela
author: Lai, Ka-Man
date: 2011-05-23
txt: ./txt/cord-261908-olcuq6tm.txt
cache: ./cache/cord-261908-olcuq6tm.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1371/journal.pone.0020086
doi: 10.1371/journal.pone.0020086
summary:
  The fate of the droplet nuclei on inhalation also depends on their size; particles greater than five microns are likely to remain in the upper airways but smaller particles are more likely to deposit in the alveoli and so may transmit infections of the lower respiratory tract such as tuberculosis [22, 23] . The large number of aerosols emitted by the vuvuzela raises the possibility that, if used by persons with an infection of the respiratory tract, they could act a conduit for the spread of infectious particles. To obtain the desired trumpet sound when blowing the vuvuzela air is forced through the lips into the opening of the instrument which may serve to create further aerosols, or alter the size of droplets produced elsewhere in the respiratory tract. Exhale duration, peak air velocity, particle concentration and mean particle diameter recorded during playing the vuvuzela and shouting by four male and four female volunteers.

abstract:
  Vuvuzelas, the plastic blowing horns used by sports fans, recently achieved international recognition during the FIFA World Cup soccer tournament in South Africa. We hypothesised that vuvuzelas might facilitate the generation and dissemination of respiratory aerosols. To investigate the quantity and size of aerosols emitted when the instrument is played, eight healthy volunteers were asked to blow a vuvuzela. For each individual the concentration of particles in expelled air was measured using a six channel laser particle counter and the duration of blowing and velocity of air leaving the vuvuzela were recorded. To allow comparison with other activities undertaken at sports events each individual was also asked to shout and the measurements were repeated while using a paper cone to confine the exhaled air. Triplicate measurements were taken for each individual. The mean peak particle counts were 658×10(3) per litre for the vuvuzela and 3.7×10(3) per litre for shouting, representing a mean log(10) difference of 2.20 (95% CI: 2.03,2.36; p<0.001). The majority (>97%) of particles captured from either the vuvuzela or shouting were between 0.5 and 5 microns in diameter. Mean peak airflows recorded for the vuvuzela and shouting were 6.1 and 1.8 litres per second respectively. We conclude that plastic blowing horns (vuvuzelas) have the capacity to propel extremely large numbers of aerosols into the atmosphere of a size able to penetrate the lower lung. Some respiratory pathogens are spread via contaminated aerosols emitted by infected persons. Further investigation is required to assess the potential of the vuvuzela to contribute to the transmission of aerosol borne diseases. We recommend, as a precautionary measure, that people with respiratory infections should be advised not to blow their vuvuzela in enclosed spaces and where there is a risk of infecting others.


id: cord-265164-ybh5yljw
title: Numerical study of the transport of droplets or particles generated by respiratory system indoors
author: Zhao, Bin
date: 2004-11-24
txt: ./txt/cord-265164-ybh5yljw.txt
cache: ./cache/cord-265164-ybh5yljw.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S0360132304003038
doi: 10.1016/j.buildenv.2004.09.018
summary:
  The drift flux model, which considers the settling of particles or droplets under the effect of gravitational sedimentation, is adopted to simulate the droplets transport and distribution indoors during respiration and sneezing or coughing process, while the simplified model for solving the continuous fluid flow is combined. The results show that droplets or particles generated by normal breathing process transport a relatively short distance, while droplets or particles generated during coughing or sneezing may travel much longer distances, which may pose adverse effect on human bodies for defending the SARS or other infectious diseases. To calculate the three-dimensional and non-isothermal airflow inside ventilated rooms, a well validated simplified methodology combined with N-point air supply opening model [4] , a zero equation turbulence model [5] is applied. Numerical studies on the transport and distribution of particles or droplets generated by normal respiration and sneezing or coughing indoors result in the following conclusions:

abstract:
  The outbreak of atypical pneumonia, referred to as severe acute respiratory syndrome (SARS), has spread to many countries in the world. SARS may infect human bodies by the tiny droplets or particles carrying various virus and bacteria, which are generated by the respiratory system of infected patients. This paper presents the numerical analysis of the influence of generating ways of the droplets or particles on the transport and distribution of the droplets or particles indoors. The drift flux model, which considers the settling of particles or droplets under the effect of gravitational sedimentation, is adopted to simulate the droplets transport and distribution indoors during respiration and sneezing or coughing process, while the simplified model for solving the continuous fluid flow is combined. Two different cases considering the normal respiration and coughing or sneezing are studied, respectively, and two different outlet velocities from the mouth for the sneezing or coughing process are considered. The results show that droplets or particles generated by normal breathing process transport a relatively short distance, while droplets or particles generated during coughing or sneezing may travel much longer distances, which may pose adverse effect on human bodies for defending the SARS or other infectious diseases.


id: cord-265642-7mu530yp
title: Virus-Like Particles as an Instrument of Vaccine Production
author: Syomin, B. V.
date: 2019-06-17
txt: ./txt/cord-265642-7mu530yp.txt
cache: ./cache/cord-265642-7mu530yp.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1134/s0026893319030154
doi: 10.1134/s0026893319030154
summary:
  Using protein expression systems it is possible to produce virus-like particles (VLPs), which are made up of monomers, which are able to multimerize into VLPs, and display the antigenic determinants of target pathogens on their surface. For example, in different laboratories different eukaryotic systems for viral protein expression, including plant cells, are used to produce VLPs which are used for vaccination against the hepatitis C virus (HCV) [36] . Antigen of the duck hepatitis A virus produced in the baculovirus expression system assembles into VLPs immediately in the cultured Spodoptera frugiperda (sf9) cells, while immunization of ducklings with the obtained VLPs induces a high level humoral immune response and protects them from developing the disease [46] . Expression vectors for foreign protein production in plants have been developed based on plant viruses, which allows obtaining plant-producing recombinant viruses or VLPs displaying the target antigen on their surface [101, 102] .

abstract:
  The paper discusses the techniques which are currently implemented for vaccine production based on virus-like particles (VLPs). The factors which determine the characteristics of VLP monomers assembly are provided in detail. Analysis of the literature demonstrates that the development of the techniques of VLP production and immobilization of target antigens on their surface have led to the development of universal platforms which make it possible for virtually any known antigen to be exposed on the particle surface in a highly concentrated form. As a result, the focus of attention has shifted from the approaches to VLP production to the development of a precise interface between the organism’s immune system and the peptides inducing a strong immune response to pathogens or the organism’s own pathological cells. Immunome-specified methods for vaccine design and the prospects of immunoprophylaxis are discussed. Certain examples of vaccines against viral diseases and cancers are considered.


id: cord-271616-h6iauddk
title: Disassembly of the cystovirus ϕ6 envelope by montmorillonite clay
author: Block, Karin A
date: 2013-12-19
txt: ./txt/cord-271616-h6iauddk.txt
cache: ./cache/cord-271616-h6iauddk.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/24357622/
doi: 10.1002/mbo3.148
summary:
  We hypothesize that the surface charge distribution of the clay and virus envelope dictates how the components react and affect aggregation, viral stability, and infectivity. Edge-attached viral envelopes distort to increase contact area with the positively charged platelet edges indicating that the virion surface is negatively charged. The MMT-mediated sequestration and disassembly result in reduced infectivity, suggesting that clays may reduce infectivity of enveloped pathogenic viruses in soils and sediments. Figure 4 shows an aggregate of clay platelets and partially disassembled virions (dashed arrows) and MMT-NCs (solid arrows). As the detergent-isolated NC particles in the aggregates retain their original morphology, the interaction with the clay is likely weaker than that between the MMT and the partially disassembled virions. Interactions between colloidal clay and suspended viral particles result in the stripping of the viral envelope and a consequent loss of infectivity of the phage φ6.

abstract:
  Prior studies of clay–virus interactions have focused on the stability and infectivity of nonenveloped viruses, yielding contradictory results. We hypothesize that the surface charge distribution of the clay and virus envelope dictates how the components react and affect aggregation, viral stability, and infectivity. The bacteriophage Cystoviridae species φ6 used in this study is a good model for enveloped pathogens. The interaction between φ6 and montmorillonite (MMT) clay (the primary component of bentonite) is explored by transmission electron microscopy. The analyses show that MMT–φ6 mixtures undergo heteroaggregation, forming structures in which virtually all the virions are either sequestered between MMT platelet layers or attached to platelet edges. The virions swell and undergo disassembly resulting in partial or total envelope loss. Edge-attached viral envelopes distort to increase contact area with the positively charged platelet edges indicating that the virion surface is negatively charged. The nucleocapsid (NCs) remaining after envelope removal also exhibit distortion, in contrast to detergent-produced NCs which exhibit no distortion. This visually discernible disassembly is a mechanism for loss of infectivity previously unreported by studies of nonenveloped viruses. The MMT-mediated sequestration and disassembly result in reduced infectivity, suggesting that clays may reduce infectivity of enveloped pathogenic viruses in soils and sediments.


id: cord-272248-d0ybu9o3
title: Airborne pathogen projection during ophthalmic examination
author: Bostanci Ceran, Basak
date: 2020-06-25
txt: ./txt/cord-272248-d0ybu9o3.txt
cache: ./cache/cord-272248-d0ybu9o3.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32588166/
doi: 10.1007/s00417-020-04815-4
summary:
  In consideration of these occasions, the present study aims to simulate airborne pathogen projection through breathing, coughing, and sneezing during the ophthalmic examination and suggest preventive measures for diminishing transmission. In order to understand the social distancing phenomenon and airborne pathogen spread during the ophthalmic examination, two scenarios with two different conditions based on exit flow velocities were considered: The configurations for these cases are depicted in Fig. 2 . For instance, in case of an exit flow of~12,000 mm/s without any preventive action, Fig. 4 Airborne particle projection during the ophthalmic examination with the protective breath shield: a exhalation (the maximum flow velocity at the exit from the patient''s mouth is~1000 mm/s), b coughing/sneezing (the maximum flow velocity at the exit from the patient''s mouth is~12,000 mm/s) the average horizontal distance of the flow front was obtained to be~1300 mm.

abstract:
  PURPOSE: Microscale droplets act as coronaviruses (CoV) carriers in the air when released from an infected person and may infect others during close contact such as ophthalmic examination. The main objective of the present work is to demonstrate how CoV deposited droplets are projected during biomicroscopy and to discuss what kind of precautions should be taken in ophthalmic practice. METHODS: A coupled fluid-structure system comprising smoothed particle hydrodynamics and the finite element method has been built to assess the projection of droplets spreading from an infected person. Different conditions based on the maximum exit flow velocity from the infector’s mouth during the ophthalmic examination were modeled. RESULTS: During exhalation, for which the exit flow is ~ 1000 mm/s, the average horizontal distance of the flow front was ~ 200 mm while individual particles can reach up to ~ 500 mm. In case of coughing or sneezing (corresponding to an exit flow of ~ 12,000 mm/s), the average horizontal distance of the flow front was ~ 1300 mm. CONCLUSION: During the ophthalmic examination, the proximity to the patient’s nose and mouth was observed to be less than the horizontal distance of flow front particles. Even though mounted breath shields are used, particles flew beyond the shield and contaminate the ophthalmologist. Compared with the current protective breath shields, the use of a larger shield with a minimum radius of 18 cm is needed to decrease viral transmission. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00417-020-04815-4) contains supplementary material, which is available to authorized users.


id: cord-273382-7w8fli6w
author: Guderian, Daniela B.
date: 2020-09-07
txt: ./txt/cord-273382-7w8fli6w.txt
cache: ./cache/cord-273382-7w8fli6w.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32895799/
doi: 10.1007/s00405-020-06330-y
summary:
  title: In vitro comparison of surgical techniques in times of the SARS-CoV-2 pandemic: electrocautery generates more droplets and aerosol than laser surgery or drilling Five typical surgical intervention techniques (mechanical stress with a passive instrument with and without suction, CO(2) laser treatment, drilling and bipolar electrocoagulation) were examined and compared regarding resulting particle release. The aim of the presented study was therefore to develop an experimental setup for the simultaneous assessment of aerosol and particle formation in various typical ENT interventions. Similarly, no particle or aerosol formation was detected during mechanical impact by use of a passive instrument in direct tissue contact with additional suction (cf. The laser treatment of the tissue did not lead to a detectable particle formation at any of the three points in time of the analysis (see Fig. 3 , third line).

title:
  In vitro comparison of surgical techniques in times of the SARS-CoV-2 pandemic: electrocautery generates more droplets and aerosol than laser surgery or drilling

abstract:
  INTRODUCTION: Based on current knowledge, the SARS-CoV-2 is transmitted via droplet, aerosols and smear infection. Due to a confirmed high virus load in the upper respiratory tract of COVID-19 patients, there is a potential risk of infection for health care professionals when performing surgical procedures in this area. The aim of this study was the semi-quantitative comparison of ENT-typical interventions in the head and neck area with regard to particle and aerosol generation. These data can potentially contribute to a better risk assessment of aerogenic SARS-CoV-2-transmission caused by medical procedures. MATERIALS AND METHODS: As a model, a test chamber was created to examine various typical surgical interventions on porcine soft and hard tissues. Simultaneously, particle and aerosol release were recorded and semi-quantitatively evaluated time-dependently. Five typical surgical intervention techniques (mechanical stress with a passive instrument with and without suction, CO(2) laser treatment, drilling and bipolar electrocoagulation) were examined and compared regarding resulting particle release. RESULTS: Neither aerosols nor particles could be detected during mechanical manipulation with and without suction. The use of laser technique showed considerable formation of aerosol. During drilling, mainly solid tissue particles were scattered into the environment (18.2 ± 15.7 particles/cm(2)/min). The strongest particle release was determined during electrocoagulation (77.2 ± 30.4 particles/cm(2)/min). The difference in particle release between electrocoagulation and drilling was significant (p < 0.05), while particle diameter was comparable. In addition, relevant amounts of aerosol were released during electrocoagulation (79.6% of the maximum flue gas emission during laser treatment). DISCUSSION: Our results demonstrated clear differences comparing surgical model interventions. In contrast to sole mechanical stress with passive instruments, all active instruments (laser, drilling and electrocoagulation) released particles and aerosols. Assuming that particle and aerosol exposure is clinically correlated to the risk of SARS-CoV-2-transmission from the patient to the physician, a potential risk for health care professionals for infection cannot be excluded. Especially electrocautery is frequently used for emergency treatment, e.g., nose bleeding. The use of this technique may, therefore, be considered particularly critical in potentially infectious patients. Alternative methods may be given preference and personal protective equipment should be used consequently.


id: cord-274305-mnyy41po
title: Demystifying the mist: Sources of microbial bioload in dental aerosols
author: Kumar, Purnima S
date: 2020-07-27
txt: ./txt/cord-274305-mnyy41po.txt
cache: ./cache/cord-274305-mnyy41po.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32662070/
doi: 10.1002/jper.20-0395
summary:
  The purpose of this review, therefore, is to examine (1) what is currently known regarding the physics of aerosol creation, (2) the types of environmental contaminants generated by dental procedures, (3) the nature, quantity, and sources of microbiota in these contaminants and (4) the risk of disease transmission from patients to dental healthcare workers. Well‐controlled, large‐scale, multi center studies using atraumatic air harvesters, open‐ended methods for microbial characterization and integrated data modeling are urgently needed to characterize the microbial constituents of aerosols created during dental procedures and to estimate time and extent of spread of these infectious agents. The purpose of this review, therefore, is to examine what is currently known regarding the physics of aerosol creation, the types of aerosols generated by dental procedures, the nature, quantity, and sources of microbiota in these aerosols and the probability of disease transmission from patients to dental healthcare workers.

abstract:
  The risk of transmitting airborne pathogens is an important consideration in dentistry and has acquired special significance in the context of recent respiratory disease epidemics. The purpose of this review, therefore, is to examine (1) what is currently known regarding the physics of aerosol creation, (2) the types of environmental contaminants generated by dental procedures, (3) the nature, quantity, and sources of microbiota in these contaminants and (4) the risk of disease transmission from patients to dental healthcare workers. Most dental procedures that use ultrasonics, handpieces, air‐water syringes, and lasers generate sprays, a fraction of which are aerosolized. The vast heterogeneity in the types of airborne samples collected (spatter, settled aerosol, or harvested air), the presence and type of at‐source aerosol reduction methods (high‐volume evacuators, low volume suction, or none), the methods of microbial sampling (petri dishes with solid media, filter paper discs, air harvesters, and liquid transport media) and assessment of microbial bioload (growth conditions, time of growth, specificity of microbial characterization) are barriers to drawing robust conclusions. For example, although several studies have reported the presence of microorganisms in aerosols generated by ultrasonic scalers and high‐speed turbines, the specific types of organisms or their source is not as well studied. This paucity of data does not allow for definitive conclusions to be drawn regarding saliva as a major source of airborne microorganisms during aerosol generating dental procedures. Well‐controlled, large‐scale, multi center studies using atraumatic air harvesters, open‐ended methods for microbial characterization and integrated data modeling are urgently needed to characterize the microbial constituents of aerosols created during dental procedures and to estimate time and extent of spread of these infectious agents.


id: cord-274355-6hiutrct
author: Satheesan, Manoj Kumar
date: 2020-02-22
txt: ./txt/cord-274355-6hiutrct.txt
cache: ./cache/cord-274355-6hiutrct.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1007/s12273-020-0623-4
doi: 10.1007/s12273-020-0623-4
summary:
  This study investigates the transport mechanism and deposition patterns of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) within a typical six bedded general inpatient ward cubicle through numerical simulation. Although it is widely assumed that increasing the air change rate (ACH) can reduce infection risks, it was shown that the risk of exposure to pathogens could increase with an increased ventilation rate under certain circumstances BUILD SIMUL https://doi.org/10.1007/s12273-020-0623-4 Satheesan et al. As the number of research studies on ventilation systems for general inpatient wards with respect to air change rate and exhaust airflow rate is limited, this study evaluates the combined impacts of these two parameters on the airflow as well as infection risk distributions of droplet nuclei of size 0.167 μm (i.e. MERS-CoV) within an air-conditioned general inpatient ward cubicle. Furthermore, the randomness associated with particle deposition rates (r w , r c , and r f ) under different air change rate conditions can be attributed to the asymmetric airflow distribution patterns and locations of the infected patients.

title:
  A numerical study of ventilation strategies for infection risk mitigation in general inpatient wards

abstract:
  Aerial dispersion of human exhaled microbial contaminants and subsequent contamination of surfaces is a potential route for infection transmission in hospitals. Most general hospital wards have ventilation systems that drive air and thus contaminants from the patient areas towards the corridors. This study investigates the transport mechanism and deposition patterns of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) within a typical six bedded general inpatient ward cubicle through numerical simulation. It demonstrates that both air change and exhaust airflow rates have significant effects on not only the airflow but also the particle distribution within a mechanically ventilated space. Moreover, the location of an infected patient within the ward cubicle is crucial in determining the extent of infection risk to other ward occupants. Hence, it is recommended to provide exhaust grilles in close proximity to a patient, preferably above each patient’s bed. To achieve infection prevention and control, high exhaust airflow rate is also suggested. Regardless of the ventilation design, all patients and any surfaces within a ward cubicle should be regularly and thoroughly cleaned and disinfected to remove microbial contamination. The outcome of this study can serve as a source of reference for hospital management to better ventilation design strategies for mitigating the risk of infection.


id: cord-274780-fmnro0kw
title: Detection of astroviruses in feces of a cat with diarrhea
author: Hoshino, Y.
date: 1981
txt: ./txt/cord-274780-fmnro0kw.txt
cache: ./cache/cord-274780-fmnro0kw.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/6798953/
doi: 10.1007/bf01320252
summary:
  Astroviruses were detected by electron microscopy in the feces from a 4 month old kitten with diarrhea. Astroviruses were detected by electron microscopy in the feces from a 4 month old kitten with diarrhea. The clinical disease manifested by the cat and the observed morphology of the viral particles are consistent with previous reports on astroviruses of other species. The clinical disease manifested by the cat and the observed morphology of the viral particles are consistent with previous reports on astroviruses of other species. Viral antigen was detected by indirect immunofluorescent staining within the cytoplasm of cultured cells infected with fecal material of human (10, 11) and bovine (23) astroviruses. Studies on the pathogenesis of astrovirus infection in lambs have shown the site of virus multiplication to be the mature villous epithelial cells of the small intestine (21, 22) .

abstract:
  Astroviruses were detected by electron microscopy in the feces from a 4 month old kitten with diarrhea. The mean diameter of the viral particles was 28.7 nm, and they showed characteristic five- or six-pointed star-shaped surface configurations. The clinical disease manifested by the cat and the observed morphology of the viral particles are consistent with previous reports on astroviruses of other species.


id: cord-276323-0n4aws2q
title: ARE CORONAVIRUS-LIKE PARTICLES SEEN IN DIARRHŒA STOOLS REALLY VIRUSES?
author: Dourmashkin, R. R
date: 1980-11-01
txt: ./txt/cord-276323-0n4aws2q.txt
cache: ./cache/cord-276323-0n4aws2q.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S0140673680921236
doi: 10.1016/s0140-6736(80)92123-6
abstract: nan
summary:
  Examination of the differentially centrifuged ultracentrifugation pellet of the patient''s stool by electrorimicroscopy with negative staining revealed large numbers of "coronavirus-1ike particles" type 34 ( fig. Those vesicles that were separate from the rest showed projections from their surface that were similar to the projections seen in the coronavirus-like particles visualised by negative staining, (fig. SiR,&mdash;An endogenous opioid neurotransmitter system whose activation mimics exogenous opiate action had been postulated for many years but has only recently been describe.1,2 There is now compelling evidence that corticotrophin (ACTH) and (3-lipotropin/ (3-endorphin are formed from a larger recursor protein which has been called pro-ACTH/endorphin..5 ACTH and &bgr;-LHP/&bgr;endorphin are located and stored in the same cells and secretory granules within the pituitary, and under all stimulatory and inhibitory conditions all fragments are released together.3-5 In animals the major source of plasma &bgr;-LPH/&bgr;-endorphin is the pituitary so that a reduced concentration in the pituitary causes reductions in circulating blood levels of P-LPH, (3-endorphin, ACTH, and cortisol.


id: cord-279716-kxfc4npg
title: Bioaerosol sampling for the detection of aerosolized influenza virus
author: Blachere, Francoise M.
date: 2007-10-22
txt: ./txt/cord-279716-kxfc4npg.txt
cache: ./cache/cord-279716-kxfc4npg.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/19453416/
doi: 10.1111/j.1750-2659.2007.00020.x
summary:
  Background Influenza virus was used to characterize the efficacy of a cyclone‐based, two‐stage personal bioaerosol sampler for the collection and size fractionation of aerosolized viral particles. Results Based on qPCR results, we demonstrate that aerosolized viral particles were efficiently collected and separated according to aerodynamic size using the two‐stage bioaerosol sampler. In order to quantify the relative amount of viral particles or fungal spores collected at each stage of the bioaerosol sampler, qPCR was performed in parallel using either serial 10-fold dilutions of cDNA generated from a single dose of non-aerosolized FluMist Ò containing approximately 10 7 TCID 50 per influenza strain or genomic DNA isolated from 10 7 spores. In this study, by aerosolizing FluMist Ò , we demonstrate the recovery of aerosolized viral particles using the bioaerosol sampler and detection of influenza by qPCR.

abstract:
  Background Influenza virus was used to characterize the efficacy of a cyclone‐based, two‐stage personal bioaerosol sampler for the collection and size fractionation of aerosolized viral particles. Methods A Collison single‐jet nebulizer was used to aerosolize the attenuated FluMist® vaccine into a calm‐air settling chamber. Viral particles were captured with bioaerosol samplers that utilize 2 microcentrifuge tubes to collect airborne particulates. The first tube (T1) collects particles greater than 1.8 μm in diameter, while the second tube (T2) collects particles between 1.0 and 1.8 μm, and the back‐up filter (F) collects submicron particles. Following aerosolization, quantitative PCR was used to detect and quantify H1N1 and H3N2 influenza strains. Results Based on qPCR results, we demonstrate that aerosolized viral particles were efficiently collected and separated according to aerodynamic size using the two‐stage bioaerosol sampler. Most viral particles were collected in T2 (1‐1.8 μm) and on the back‐up filter (< 1 μm) of the bioaerosol sampler. Furthermore, we found that the detection of viral particles with the two‐stage sampler was directly proportional to the collection time. Consequently, viral particle counts were significantly greater at 40 minutes in comparison to 5, 10 and 20 minute aerosol collection points. Conclusions Due to a lack of empirical data, aerosol transmission of influenza is often questioned. Using FluMist®, we demonstrated that a newly developed bioaerosol sampler is able to recover and size fractionate aerosolized viral particles. This sampler should be an important tool for studying viral transmission in clinical settings and may significantly contribute towards understanding the modes of influenza virus transmission.


id: cord-280272-mn596x1p
author: Akhrymuk, Ivan
date: 2020-01-28
txt: ./txt/cord-280272-mn596x1p.txt
cache: ./cache/cord-280272-mn596x1p.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32064269/
doi: 10.3389/fvets.2019.00509
summary:
  We have tested the ability of magnetic Nanotrap® (NT) particles to improve stability and detection of Venezuelan equine encephalitis virus (VEEV), viral capsid protein, and viral genomic RNA in whole human blood at elevated temperature and prolonged storage conditions. We have tested the ability of magnetic Nanotrap ® (NT) particles to improve stability and detection of Venezuelan equine encephalitis virus (VEEV), viral capsid protein, and viral genomic RNA in whole human blood at elevated temperature and prolonged storage conditions. In this study, we sought to apply new magnetic NT particles that consist of NIPAm copolymers functionalized with reactive red 120 to evaluate the efficacy of preservation of infectious VEEV, viral RNA, and VEEV capsid protein in whole blood samples at ambient and elevated temperature as well as at low and high humidity conditions.

title:
  Magnetic Nanotrap Particles Preserve the Stability of Venezuelan Equine Encephalitis Virus in Blood for Laboratory Detection

abstract:
  Most of the modern techniques used for identification of viral-induced disease are based on identification of viral antigens and/or nucleic acids in patient's blood. Diagnosis in the field or in remote locations can be challenging and alternatively samples are shipped to diagnostic labs for testing. Shipments must occur under controlled temperature conditions to prevent loss of sample integrity. We have tested the ability of magnetic Nanotrap® (NT) particles to improve stability and detection of Venezuelan equine encephalitis virus (VEEV), viral capsid protein, and viral genomic RNA in whole human blood at elevated temperature and prolonged storage conditions. NT particles have previously been shown to capture and enrich multiple pathogens including respiratory syncytial virus, influenza virus, coronavirus, and Rift Valley fever virus. Our study indicates that samples incubated with NT particles had detectable levels of infectious VEEV in blood equal to or greater than samples without NT treatment across all temperatures. Viral RNA detection was increased in the presence of NT particles at later time points (72 h) and higher temperature (40°C) conditions. Likewise, detection of VEEV capsid protein was enhanced in the presence of NT particles up to 72 h at 40°C. Finally, we intranasally infected C3H mice with TC-83, the live attenuated vaccine strain of VEEV, and demonstrated that NT particles could substantially increase the detection of VEEV capsid in infected blood incubated up to 72 h at 40°C. Samples without NT particles had undetectable capsid protein levels. Taken together, our data demonstrate the ability of NT particles to preserve and enable detection of VEEV in human and mouse blood samples over time and at elevated temperatures.


id: cord-282858-zikoui4h
title: SARS-CoV-2. Long Distance Airborne Transmission and its Public Health Implications
author: Graudenz, Gustavo Silveira
date: 2020-11-02
txt: ./txt/cord-282858-zikoui4h.txt
cache: ./cache/cord-282858-zikoui4h.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.6061/clinics/2020/e2343
doi: 10.6061/clinics/2020/e2343
abstract: nan
summary:
  Its predecessor, SARS-CoviD-1, the agent that caused Severe Acute Respiratory Syndrome (SARS) in Hong Kong in 2003, showed strong evidence of opportunistic airborne transmission in different environments, such as collective housing environments (8) , indoor environments such as airplanes (9), and health service institutions (10) . (12) that suggested transmission of SARS-CoV-2 through infected surfaces and contaminated individual protection equipment as well as long distance environment contamination. In health care settings, the Center for Disease Control''s recommendations for prevention of airborne transmission include maintaining a negative pressure environment, fine filtering of exhaust air from infected patients'' rooms, maintaining high air exchange rates (12 air exchanges per hour), shutting recirculation ducts, and establishing pressure cascades (2) in these settings until further evidence of long distance transmission is obtained Unfortunately, these precautionary measures have not yet been applied in most health care facilities in Brazil. Evidence of Airborne Transmission of the Severe Acute Respiratory Syndrome Virus


id: cord-285077-okwck5sv
author: Sayahi, Tofigh
date: 2020-09-15
txt: ./txt/cord-285077-okwck5sv.txt
cache: ./cache/cord-285077-okwck5sv.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32928037/
doi: 10.1177/0194599820957966
summary:
  CONCLUSION: Coblation and electrocautery procedures generate >100-fold increases in aerosol concentrations over background; only coblation and drilling produce aerosolized viral DNA. Coblation and electrocautery procedures generate .100-fold increases in aerosol concentrations over background; only coblation and drilling produce aerosolized viral DNA. 10, 11 We proposed to build on these studies by measuring particle size and concentration and by trying to detect aerosolized viral DNA and viable virus during common otolaryngology procedures, using a murine model for cytomegalovirus (CMV) infection. The results also indicated that drilling and microdebrider did not cause statistically significant increases in aerosol concentrations and total counts when compared with background (.870 \ Tukey-adjusted P value \ .930; Figures 2 and 3 , Table 3 ). The results from our study demonstrate that a number of these procedures can generate relatively large concentrations of aerosolized particles and that a significant percentage are small enough to pass unimpeded through conventional surgical and even N95 masks.

title:
  Airborne Aerosolized Mouse Cytomegalovirus From Common Otolaryngology Procedures: Implications for COVID-19 Infection

abstract:
  OBJECTIVES: To determine whether common otolaryngology procedures generate viable aerosolized virus through a murine cytomegalovirus (mCMV) model for infection. STUDY DESIGN: mCMV model of infection. SETTING: University of Utah laboratory. METHODS: Three-day-old BALB/c mice were inoculated with mCMV or saline. Five days later, each mouse underwent drilling, microdebrider, coblation, and electrocautery procedures. Particle size distribution and PM(2.5) (particulate matter <2.5 µm) concentration were determined with a scanning mobility particle sizer and an aerosol particle sizer in the range of 15 nm to 32 µm. Aerosolized samples from these procedures were collected with an Aerosol Devices BioSpot sampler for viral titer based on polymerase chain reaction and for viable virus through viral culture. RESULTS: As compared with the background aerosol concentrations, coblation and electrocautery showed statistically significant increases in airborne aerosols (Tukey-adjusted P value <.040), while microdebrider and drilling at 30,000 rpm did not (.870 < Tukey-adjusted P value < .930). We identified viral DNA in samples from coblation and drilling procedures, although we did not identify viable viruses in aerosol samples from any of the 4 procedures. CONCLUSION: Coblation and electrocautery procedures generate >100-fold increases in aerosol concentrations over background; only coblation and drilling produce aerosolized viral DNA. The high concentration of aerosols from coblation and electrocautery suggests the need for appropriate safeguards against particle exposure to health care workers. The presence of viral DNA from drilling and coblation procedures warrants the need for appropriate protection against droplet and aerosol exposure.


id: cord-286878-5nv3ec5l
author: Simpson, J.P.
date: 2020-06-19
txt: ./txt/cord-286878-5nv3ec5l.txt
cache: ./cache/cord-286878-5nv3ec5l.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1111/anae.15188
doi: 10.1111/anae.15188
summary:
  Using an in‐situ simulation model, we evaluated laryngoscopist exposure of airborne particles sized 0.3 ‐ 5.0 microns using five aerosol containment devices (aerosol box; sealed box with and without suction; vertical drape; and horizontal drape) compared with no aerosol containment device. Compared with no device use, the aerosol box showed an increase in 1.0, 2.5 and 5.0 micron airborne particle exposure at 300 seconds (p = 0.002, 0.008, 0.002, respectively). To guide our institutional protocols for the airway management of patients with suspected or confirmed COVID-19, we sought to test whether different aerosol containment devices confer any protective advantage to the laryngoscopist specifically with respect to airborne particle dispersal. Our primary research question was how aerosol containment devices (aerosol boxes and plastic drapes) placed over a patient during tracheal intubation compare to no intervention with respect to exposure of the laryngoscopist to airborne particles?

title:
  Measurement of airborne particle exposure during simulated tracheal intubation using various proposed aerosol containment devices during the COVID‐19 pandemic

abstract:
  The COVID‐19 pandemic has led to the production of novel devices intended to protect airway managers during the aerosol‐generating procedure of tracheal intubation. Using an in‐situ simulation model, we evaluated laryngoscopist exposure of airborne particles sized 0.3 ‐ 5.0 microns using five aerosol containment devices (aerosol box; sealed box with and without suction; vertical drape; and horizontal drape) compared with no aerosol containment device. Nebulised saline was used as the aerosol‐generating model for 300 seconds, at which point, the devices were removed to assess particle spread. Primary outcome was the quantity and size of airborne particles measured at the level of the laryngoscopist’s head at 30, 60, 120, and 300 seconds, as well as 360 seconds (60 seconds after device removal). Airborne particles sizes of 0.3, 0.5, 1.0, 2.5 and 5.0 microns were quantified using an electronic airborne particle counter. Compared with no device use, the sealed intubation box with suction resulted in a decrease in 0.3, 0.5, 1.0 and 2.5 micron, but not 5.0 micron, particle exposure over all time‐periods (p = 0.003 for all time periods). Compared with no device use, the aerosol box showed an increase in 1.0, 2.5 and 5.0 micron airborne particle exposure at 300 seconds (p = 0.002, 0.008, 0.002, respectively). Compared with no device use, neither horizontal nor vertical drapes showed any difference in any particle size exposure at any time. Finally, when the patient coughed, use of the aerosol box resulted in a marked increase in airborne particle exposure compared with other devices or no device use. In conclusion, novel devices intended to protect the laryngoscopist require objective testing to ensure they are fit for purpose and do not result in increased airborne particle exposure.


id: cord-287708-0qvwjejv
author: Gera, Tamás
date: 2020-09-25
txt: ./txt/cord-287708-0qvwjejv.txt
cache: ./cache/cord-287708-0qvwjejv.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1038/s41598-020-72865-z
doi: 10.1038/s41598-020-72865-z
summary:
  We studied the application of pulsed laser ablation (PLA) for particle size reduction in non-steroidal anti-inflammatory drugs (NSAIDs). In this work, three NSAIDs (ibuprofen, meloxicam and niflumic acid) with different chemical structures but similar solubility, dissociation constant, particle size and crystallinity were selected as targets to study the effect of a high-energy pulsed laser beam on the chemical degradation and particle size distribution of the ablated drug particles. We studied the chemical composition and particle size distribution of the ablated particles, the optical absorption of the target drugs and made fast photography measurements too. Size distribution (measured by SMPS) of ibuprofen particles produced by laser ablation at 532 nm and 1064 nm wavelengths can be seen in Fig. 6 . conclusion PLA can be applied for the size reduction of poorly water-soluble NSAIDs. In the case of meloxicam, ibuprofen and niflumic acid, submicron to nanometer size particles can be produced by careful selection of the laser parameters, reducing the initial mean average sizes by orders of magnitude.

title:
  Application of pulsed laser ablation (PLA) for the size reduction of non-steroidal anti-inflammatory drugs (NSAIDs)

abstract:
  We studied the application of pulsed laser ablation (PLA) for particle size reduction in non-steroidal anti-inflammatory drugs (NSAIDs). Grinding of the poorly water-soluble NSAID crystallites can considerably increase their solubility and bioavailability, thereby the necessary doses can be reduced significantly. We used tablets of ibuprofen, niflumic acid and meloxicam as targets. Nanosecond laser pulses were applied at various wavelengths (KrF excimer laser, λ = 248 nm, FWHM = 18 ns and Nd:YAG laser, λ(1) = 532 nm/λ(2) = 1064 nm, FWHM = 6 ns) and at various fluences. FTIR and Raman spectra showed that the chemical compositions of the drugs had not changed during ablation at 532 nm and 1064 nm laser wavelengths. The size distribution of the ablated products was established using two types of particle size analyzers (SMPS and OPC) having complementary measuring ranges. The mean size of the drug crystallites decreased from the initial 30–80 µm to the submicron to nanometer range. For a better understanding of the ablation mechanism we made several investigations (SEM, Ellipsometry, Fast photography) and some model calculations. We have established that PLA offers a chemical-free and simple method for the size reduction of poorly water-soluble drugs and a possible new way for pharmaceutical drug preformulation for nasal administration.


id: cord-287751-52e0tlcu
author: Dai, Qili
date: 2020-11-06
txt: ./txt/cord-287751-52e0tlcu.txt
cache: ./cache/cord-287751-52e0tlcu.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S0048969720370790?v=s5
doi: 10.1016/j.scitotenv.2020.143548
summary:
  To reduce the influence of dilution on quantitative source estimates, a methodology for improving the accuracy of source apportionment results by incorporating a measure of dispersion, the ventilation coefficient, into the PMF analysis (called dispersion normalized PMF, DN-PMF) was applied to a PNC dataset measured from a field campaign that includes the Spring Festival event and the start of the COVID-19 lockdown in Tianjin, China. In addition to measured PNC data, auxiliary variables include gaseous pollutants (SO 2 , NO 2 , CO and O 3 ), PM 1 , PM 1-2.5 (PM 2.5 -PM 1 ), radiation and selected potential source tracer species (OC, EC, NO 3 -analyses to support factor interpretation. The best solution with the optimal number of factors was evaluated with selection criteria of appropriately narrow distributions of scaled residuals of PNCs and the physical interpretability of factors in terms of (a) examination of size factor profiles and its association with external variables, (b) source directionality from CBPF plots, and (c) diel patterns.

title:
  Changes in source contributions to particle number concentrations after the COVID-19 outbreak: Insights from a dispersion normalized PMF

abstract:
  Factor analysis models use the covariance of measured variables to identify and apportion sources. These models, particularly positive matrix factorization (PMF), have been extensively used for analyzing particle number concentrations (PNCs) datasets. However, the variation of observed PNCs and particle size distribution are driven by both the source emission rates and atmospheric dispersion as well as chemical and physical transformation processes. This variation in the observation data caused by meteorologically induced dilution reduces the ability to obtain accurate source apportionment results. To reduce the influence of dilution on quantitative source estimates, a methodology for improving the accuracy of source apportionment results by incorporating a measure of dispersion, the ventilation coefficient, into the PMF analysis (called dispersion normalized PMF, DN-PMF) was applied to a PNC dataset measured from a field campaign that includes the Spring Festival event and the start of the COVID-19 lockdown in Tianjin, China. The data also included pollutant gases and hourly PM2.5 compositional data. Eight factors were resolved and interpreted as municipal incinerator, traffic nucleation, secondary inorganic aerosol (SIA), traffic emission, photonucleation, coal combustion, residential heating and festival emission. The DN-PMF enhanced the diel patterns of photonucleation and the two traffic factors by enlarging the differences between daytime peak values and nighttime concentrations. The municipal incinerator plant, traffic emissions, and coal combustion have cleaner and more clearly defined directionalities after dispersion normalization. Thus, dispersion normalized PMF is capable of enhancing the source emission patterns. After the COVID-19 lockdown began, PNC of traffic nucleation and traffic emission decreased by 41% and 44%, respectively, while photonucleation produced more particles likely due to the reduction in the condensation sink. The significant changes in source emissions indicate a substantially reduced traffic volume after the implement of lockdown measures.


id: cord-289521-zun6tp2o
author: Leonard, Scott
date: 2020-05-29
txt: ./txt/cord-289521-zun6tp2o.txt
cache: ./cache/cord-289521-zun6tp2o.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32838373/
doi: 10.1002/emp2.12158
summary:
  title: Reducing aerosol dispersion by High Flow Therapy in COVID‐19: High Resolution Computational Fluid Dynamics Simulations of Particle Behavior during High Velocity Nasal Insufflation with a Simple Surgical Mask Here, we present a subsequent high‐resolution simulation (higher complexity/reliability) to provide a more accurate and precise particle characterization on the effect of surgical masks on patients during HVNI, Low‐Flow Oxygen therapy (LFO2), and tidal breathing. METHODS: This in‐silico modeling study of HVNI, LFO2, and tidal breathing presents ANSYS Fluent Computational Fluid Dynamics simulations that evaluate the effect of Type I surgical mask use over patient face on particle/droplet behavior. The in-silico model included a room simulation to evaluate the fluid dynamic behavior of the effect of a surgical mask on particles which may be generated in the airway while receiving HVNI therapy. Simulations were performed on control cases modeling a patient on HVNI (40L•min -1 ), Low Flow Oxygen (LFO2) therapy (6L•min -1 via Nasal Cannula), and simulated breathing (tidal breathing, no therapy) without a surgical mask.

title:
  Reducing aerosol dispersion by High Flow Therapy in COVID‐19: High Resolution Computational Fluid Dynamics Simulations of Particle Behavior during High Velocity Nasal Insufflation with a Simple Surgical Mask

abstract:
  OBJECTIVE: All respiratory care represents some risk of becoming an Aerosol Generating Procedure (AGP) during COVID‐19 patient management. Personal Protective Equipment (PPE) and Environmental Control/Engineering is advised. High Velocity Nasal Insufflation (HVNI) and High Flow Nasal Cannula (HFNC) deliver High Flow Oxygen (HFO) therapy, established as a competent means of supporting oxygenation for acute respiratory distress patients, including that precipitated by COVID‐19. Although unlikely to present a disproportionate particle dispersal risk, AGP from HFO continues to be a concern. Previously, we published a preliminary model. Here, we present a subsequent high‐resolution simulation (higher complexity/reliability) to provide a more accurate and precise particle characterization on the effect of surgical masks on patients during HVNI, Low‐Flow Oxygen therapy (LFO2), and tidal breathing. METHODS: This in‐silico modeling study of HVNI, LFO2, and tidal breathing presents ANSYS Fluent Computational Fluid Dynamics simulations that evaluate the effect of Type I surgical mask use over patient face on particle/droplet behavior. RESULTS: This in‐silico modeling simulation study of HVNI (40L∙min(‐1)) with a simulated surgical mask suggests 88.8% capture of exhaled particulate mass in the mask, compared to 77.4% in LFO2 (6L∙min(‐1)) capture, with particle distribution escaping to the room (>1m from face) lower for HVNI+Mask versus LFO2+Mask (8.23% versus 17.2%). The overwhelming proportion of particulate escape was associated with mask‐fit designed model gaps. Particle dispersion was associated with lower velocity. CONCLUSIONS: These simulations suggest employing a surgical mask over the HVNI interface may be useful in reduction of particulate mass distribution associated with AGPs. This article is protected by copyright. All rights reserved


id: cord-292928-a4bn30ul
author: Ghosh, Bipasha
date: 2015-10-03
txt: ./txt/cord-292928-a4bn30ul.txt
cache: ./cache/cord-292928-a4bn30ul.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1016/j.envint.2015.09.018
doi: 10.1016/j.envint.2015.09.018
summary:
  This review also provides the information on the concentration levels of various airborne microorganisms in different indoor environments, their associated health effects as well as various bioaerosol control mechanisms worked upon till now. A recently developed electrostatic precipitator had no charging unit in the inlet while the physical collection efficiency strongly depended on the precipitation voltage which eventually depended on the charge present on the airborne microbes naturally due to aerosolization (Kunkel, 1950; Flagan, 2001 ) thereby making collection possible by differentiating between the positively and negatively charged microorganisms by adding a signature to the bioaerosol particle sampled (Lee et al., 2004a; ; Lee et al., 2004b) . Whole genome sequencing has also been applied to study the airborne microbial community in various indoor and outdoor environments of NYC after collecting air samples using a Wet Cyclone Portable Air Sampler at the flow rate of 450 L/min (Yooseph et al., 2013) .

title:
  Review of bioaerosols in indoor environment with special reference to sampling, analysis and control mechanisms

abstract:
  Several tiny organisms of various size ranges present in air are called airborne particles or bioaerosol which mainly includes live or dead fungi and bacteria, their secondary metabolites, viruses, pollens, etc. which have been related to health issues of human beings and other life stocks. Bio-terror attacks in 2001 as well as pandemic outbreak of flue due to influenza A H1N1 virus in 2009 have alarmed us about the importance of bioaerosol research. Hence characterization i.e. identification and quantification of different airborne microorganisms in various indoor environments is necessary to identify the associated risks and to establish exposure threshold. Along with the bioaerosol sampling and their analytical techniques, various literatures revealing the concentration levels of bioaerosol have been mentioned in this review thereby contributing to the knowledge of identification and quantification of bioaerosols and their different constituents in various indoor environments (both occupational and non-occupational sections). Apart from recognition of bioaerosol, developments of their control mechanisms also play an important role. Hence several control methods have also been briefly reviewed. However, several individual levels of efforts such as periodic cleaning operations, maintenance activities and proper ventilation system also serve in their best way to improve indoor air quality.


id: cord-297377-yy1dq81q
title: Efficacy of slit lamp breath shields
author: Poostchi, Ali
date: 2020-05-12
txt: ./txt/cord-297377-yy1dq81q.txt
cache: ./cache/cord-297377-yy1dq81q.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1038/s41433-020-0940-y
doi: 10.1038/s41433-020-0940-y
abstract: nan
summary:
  Breath shields have long been a standard feature of slit lamps and act as a physical barrier between the examiner and subject but there is an absence of evidence on their effectiveness in reducing droplet transmission and respiratory infections. We then tested the effect of placing a fluid resistant surgical facemask (BARRIER 4313, Mölnlycke Healthcare, Sweden) over the nebuliser mouthpiece alone and in combination with the large shield. The surgical facemask and large shield offered the best protection, while the small standard shield seemed to be effective for larger particles (Fig. 2) . Evidence from a large-clusterbased randomised control trial showed no benefit from using N95 masks compared to surgical facemasks to reduce influenza and other respiratory viral illnesses [8] . Despite the close proximity of slit lamp examinations, the effectiveness of shielding together with the short contact time and lack of aerosol generation, leads us to expect the risk of transmission from this route to be low.


id: cord-300435-vs0ntcsb
author: Katz, Al
date: 2018-10-01
txt: ./txt/cord-300435-vs0ntcsb.txt
cache: ./cache/cord-300435-vs0ntcsb.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1016/j.scitotenv.2018.04.425
doi: 10.1016/j.scitotenv.2018.04.425
summary:
  Four sediments in the colloidal size range: goethite, montmorillonite, illite, and kaolinite, were suspended with the bacteriophage φ6, a model enveloped virus, to determine relative rates of heteroaggregation and the effect of aggregation on virus viability. A study of heteroaggregation of the non-enveloped cowpea mosaic virus with colloidal hematite revealed that at pH 6, at which hematite carries a positive surface charge and the virus a negative charge, the aggregates accumulated four times as many viruses as hematite particles Vilker et al. In this work, we employ turbidity measurements to investigate the heteroaggregation of a model envelope virus, the bacteriophage φ6, with colloidal goethite and three clay minerals: illite, kaolinite and montmorillonite. Although imprecise knowledge of doublet shape complicates calculations of heteroaggregation rates, analysis of the turbidity slope coupled with particle concentrations allows one to determine relative aggregation rates between φ6 and the four sediment types, elucidating the nature of the interaction.

title:
  Heteroaggregation of an enveloped bacteriophage with colloidal sediments and effect on virus viability

abstract:
  Four sediments in the colloidal size range: goethite, montmorillonite, illite, and kaolinite, were suspended with the bacteriophage φ6, a model enveloped virus, to determine relative rates of heteroaggregation and the effect of aggregation on virus viability. Turbidity was measured on combinations of virus and each sediment type at low concentration to determine aggregation rates. Aggregation of sediment with virus occurred regardless of mineral type, and larger fraction of virus is expected to aggregate with increasing sediment concentration leading to higher deposition rates. The negatively charged sediments, aggregated with φ6 (also negatively charged at neutral pH) at a faster rate than the positively charged sediments, yielding turbidity slopes of 4.94 × 10(−3) s(−1) and 7.50 × 10(−4) s(−1) for φ6-montmorillonite and φ6-illite aggregates, respectively, and 2.98 × 10(−5) s(−1) and 2.84 × 10(−5) s(−1), for φ6-goethite and φ6-kaolinite, respectively. This indicates that the interaction between sediments and virus is hydrophobic, rather than electrostatic. Large numbers of virions remained viable post-aggregation, despite the fragility of the viral envelope, indicating that small-sized aggregates, which may travel more readily through porous media, may pose an infection risk. The fraction of φ6 that remained viable varied with sediment type, with montmorillonite-φ6 aggregates experiencing the greatest reduction in infectivity at 35%. TEM analyses reveal that in all sediment-φ6 combinations, infectivity loss was likely due to disassembly of the viral envelope as a result of aggregation.


id: cord-304048-wncau6zm
title: A numerical study of bend-induced particle deposition in and behind duct bends
author: Sun, Ke
date: 2011-12-23
txt: ./txt/cord-304048-wncau6zm.txt
cache: ./cache/cord-304048-wncau6zm.txt
extension: .txt
mime: text/plain
url: https://api.elsevier.com/content/article/pii/S0360132311004252
doi: 10.1016/j.buildenv.2011.12.009
summary:
  This paper investigated the microparticle deposition and distribution due to the presence of duct bends by employing the Eulerian approach with Reynolds stress turbulent model and a Lagrangian trajectory method. Furthermore, models of fast power and exponential decay trend are demonstrated to uncover the relationship among enhancement factor of deposition velocity behind bend, dimensionless distance behind bends and particle Stokes number. Where N d and N f are the particle number deposited in a bend and those in the straight duct of fully developed flow section with a length D, respectively. Particle deposition distribution and deposition velocity in 90 ventilation bends with different surface materials were analyzed numerically, and the simulation results were also validated with experimental data.

abstract:
  This paper investigated the microparticle deposition and distribution due to the presence of duct bends by employing the Eulerian approach with Reynolds stress turbulent model and a Lagrangian trajectory method. The air velocity, particle velocity and particle deposition velocity were validated with available experimental data. Several particle deposition ratios were proposed to describe the particle accumulation due to bends. Particle deposition velocities in and behind bends were analyzed numerically. It is found that bend walls with surfaces of higher capture velocity tend to accumulate more contaminant particles as seen with an increased factor of 1.2 times on particle deposition velocity. Particle deposition reaches a maximum value near bend outlet, e.g. 15.2 times deposition ratio for particles of d(p) = 23 μm, and decay exponentially to a status of fully developed deposition in approximately 10D length. Compared to traditional consideration of sole deposition in bends, a new general concept of total deposition including that in bends and behind bends is proposed to better describe the particle deposition induced by bends since the enhancement deposition ratios behind bends compose 42–99% in the total ratios for particles of d(p) = 3–23 μm. Furthermore, models of fast power and exponential decay trend are demonstrated to uncover the relationship among enhancement factor of deposition velocity behind bend, dimensionless distance behind bends and particle Stokes number. The present study can contribute to the understanding and controlling of contaminant aerosol flow behavior in ducts, e.g. particle sampling, removal and associated epidemiologic study between particle and human health.


id: cord-306371-jmaqkovs
title: Spray drying of siRNA-containing PLGA nanoparticles intended for inhalation
author: Jensen, Ditte Marie Krohn
date: 2010-02-25
txt: ./txt/cord-306371-jmaqkovs.txt
cache: ./cache/cord-306371-jmaqkovs.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1016/j.jconrel.2009.10.010
doi: 10.1016/j.jconrel.2009.10.010
summary:
  The present study evaluated parameters of importance for spray drying of siRNA-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) into nanocomposite microparticles intended for inhalation. The identified optimum conditions were applied for spray drying of siRNA-loaded nanocomposite microparticles, resulting in a product with a low water content (0.78% w/w) and an aerodynamic particle diameter considered suitable for inhalation. In conclusion, the present results show that spray drying is a suitable technique for producing nanocomposite microparticles comprising siRNA-containing PLGA NPs for potential use in inhalation therapy. To overcome the macrophage clearance and still benefit from a particle size suitable for deep lung deposition and sustained release, the present study employs nanocomposite microparticles consisting of co-spray-dried PLGA NPs and a carbohydrate excipient. The optimum formulation found to provide a low water content, a sufficient yield and a small particle size was with mannitol as the carbohydrate excipient, a total dry substance concentration of 30 mg/ mL and a ratio of NPs to excipient of 0.2.

abstract:
  Local delivery of small interfering RNA (siRNA) to the lungs constitutes a promising new area in drug delivery. The present study evaluated parameters of importance for spray drying of siRNA-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) into nanocomposite microparticles intended for inhalation. The spray drying process was optimised using a statistical design of experiment and by evaluating powder characteristics upon systematic variation of the formulation parameters. Concentration, carbohydrate excipient (trehalose, lactose and mannitol) and the ratio of NP to excipient were varied to monitor the effects on moisture content, particle morphology, particle size and powder yield. The identified optimum conditions were applied for spray drying of siRNA-loaded nanocomposite microparticles, resulting in a product with a low water content (0.78% w/w) and an aerodynamic particle diameter considered suitable for inhalation. The use of mannitol in the formulation allowed a significantly lower moisture content than trehalose and lactose. The inclusion of 50% (w/w) or higher amounts of NPs resulted in a marked change in the surface morphology of the spray-dried particles. Importantly, the integrity and biological activity of the siRNA were preserved during the spray drying process. In conclusion, the present results show that spray drying is a suitable technique for producing nanocomposite microparticles comprising siRNA-containing PLGA NPs for potential use in inhalation therapy.


id: cord-310948-nt378esz
title: Quantifying Respiratory Airborne Particle Dispersion Control Through Improvised Reusable Masks
author: Edwards, N. J.
date: 2020-07-14
txt: ./txt/cord-310948-nt378esz.txt
cache: ./cache/cord-310948-nt378esz.txt
extension: .txt
mime: text/plain
url: http://medrxiv.org/cgi/content/short/2020.07.12.20152157v1?rss=1
doi: 10.1101/2020.07.12.20152157
summary:
  Objective: To determine the effectiveness of non-medical grade washable masks or face coverings in controlling airborne dispersion from exhalation (both droplet and aerosol), and to aid in establishing public health strategies on the wearing of masks to reduce COVID-19 transmission. If the SARS-CoV-2 aerosol is considered with an ability to infect for more than 3 hours with TCID50 of greater than 10 2 as noted in a recent laboratory study [1] then the understanding the effectiveness of non-medical masks and face coverings to control human exhalation aerosol dispersion has significant importance for broad public health infectious disease strategy, especially with asymptomatic or pre-symptomatic populations. The goal of this research is to determine the statistically significant factors and effectiveness of non-medical grade washable masks or face coverings in the control of aerosol dispersion of human exhalation, and to aid in establishing public health strategies or policies on the wearing of masks.

abstract:
  Objective: To determine the effectiveness of non-medical grade washable masks or face coverings in controlling airborne dispersion from exhalation (both droplet and aerosol), and to aid in establishing public health strategies on the wearing of masks to reduce COVID-19 transmission. Design: This comparative effectiveness study using an exhalation simulator to conduct 94 experiment runs with combinations of 8 different fabrics, 5 mask designs, and airflows for both talking and coughing. Setting: Non-airtight fume hood and multiple laser scattering particle sensors. Participants: No human participants. Exposure: 10% NaCl nebulized solution delivered by an exhalation simulator through various masks and fabrics with exhalation airflows representative of "coughing" and "talking or singing." Main Outcomes and Measures: The primary outcome was reduction in aerosol dispersion velocity, quantity of particles, and change in dispersion direction. Measurements used in this study included peak expiratory flow (PEF), aerosol velocity, concentration area under curve (AUC), and two novel metrics of expiratory flow dispersion factor (EDF) and filtration efficiency indicator (FEI). Results: Three-way multivariate analysis of variance establishes that factors of fabric, mask design, and exhalation breath level have a statistically significant effect on changing direction, reducing velocity or concentration (Fabric: P = < .001, Wilks' {Lambda} = .000; Mask design: P = < .001, Wilks' {Lambda} = .000; Breath level: P = < .001, Wilks' {Lambda} = .004). There were also statistically significant interaction effects between combinations of all primary factors. Conclusions and Relevance: The application of facial coverings or masks can significantly reduce the airborne dispersion of aerosolized particles from exhalation. The results show that wearing of non-medical grade washable masks or face coverings can help increase the effectiveness of non-pharmaceutical interventions (NPI) especially where infectious contaminants may exist in shared air spaces. However, the effectiveness varies greatly between the specific fabrics and mask designs used.


id: cord-311311-rmv5rfst
title: Recent Advances in Occupational Exposure Assessment of Aerosols
author: Harper, Martin
date: 2020-09-18
txt: ./txt/cord-311311-rmv5rfst.txt
cache: ./cache/cord-311311-rmv5rfst.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.3390/ijerph17186820
doi: 10.3390/ijerph17186820
summary:
  Three advances to be discussed in detail are (1) recognition and inclusion of sampler wall deposits; (2) development of a new sampling and analytical procedure for respirable crystalline silica that allows non-destructive field analysis at the end of the sampling period; and (3) development of a new sampler to collect the portion of sub-300 nm aerodynamic diameter particles that would deposit in human airways. Three advances to be discussed in detail are (1) recognition and inclusion of sampler wall deposits; (2) development of a new sampling and analytical procedure for respirable crystalline silica that allows non-destructive field analysis at the end of the sampling period; and (3) development of a new sampler to collect the portion of sub-300 nm aerodynamic diameter particles that would deposit in human airways. RCS is collected on a direct-on-filter (DoF) sampler (EoS™ Silica Cassette, Zefon International, Inc.) attached to any one of several different cyclones to select the respirable dust fraction.

abstract:
  Exposure science is underpinned by characterization (measurement) of exposures. In this article, six recent advances in exposure characterization by sampling and analysis are reviewed as tools in the occupational exposure assessment of aerosols. Three advances discussed in detail are (1) recognition and inclusion of sampler wall deposits; (2) development of a new sampling and analytical procedure for respirable crystalline silica that allows non-destructive field analysis at the end of the sampling period; and (3) development of a new sampler to collect the portion of sub-300 nm aerodynamic diameter particles that would deposit in human airways. Three additional developments are described briefly: (4) a size-selective aerosol sampler that allows the collection of multiple physiologically-relevant size fractions; (5) a miniaturized pump and versatile sampling head to meet multiple size-selective sampling criteria; and (6) a novel method of sampling bioaerosols including viruses while maintaining viability. These recent developments are placed in the context of the historical evolution in sampling and analytical developments from 1900 to the present day. While these are not the only advances in exposure characterization, or exposure assessment techniques, they provide an illustration of how technological advances are adding more tools to our toolkit. The review concludes with a number of recommended areas for future research, including expansion of real-time and end-of-shift on-site measurement, development of samplers that operate at higher flow-rates to ensure measurement at lowered limit values, and development of procedures that accurately distinguish aerosol and vapor phases of semi-volatile substances.


id: cord-311486-auuyjct6
title: Personal protective equipment during the COVID‐19 pandemic: a reply
author: Cook, T. M.
date: 2020-06-04
txt: ./txt/cord-311486-auuyjct6.txt
cache: ./cache/cord-311486-auuyjct6.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1111/anae.15158
doi: 10.1111/anae.15158
abstract: nan
summary:
  For clarity, I neither stated that particles above 5 µm were large nor referred at all to whether these are visible or not and I am unclear why these are referred to in Professor Murphy''s letter. However, the behaviour of particles is highly complex, not dependent only on size and much debated: as I stated in my article "the dichotomy into> 5 and < 5 µm particles leading to droplet or airborne spread, respectively, is likely to be simplistic, with aerosols being maintained over a wider range of particle size". I infer that Professor Murphy''s concerns are that larger particles than described contribute to aerosols and therefore that airborne transmission is a significant risk, and that the 2 m ''droplet zone'' is insufficient. Personal protective equipment during the coronavirus disease (COVID) 2019 pandemic -a narrative review Personal protective equipment during the coronavirus disease (COVID) 2019 pandemic -a narrative review The role of particle size in aerosolised pathogen transmission: a review


id: cord-312223-qgwzgazd
author: Shafagati, Nazly
date: 2013-07-04
txt: ./txt/cord-312223-qgwzgazd.txt
cache: ./cache/cord-312223-qgwzgazd.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/23861988/
doi: 10.1371/journal.pntd.0002296
summary:
  RESULTS: Screening of NanoTrap particles indicated that one particle, NT53, was the most efficient at RVFV capture as demonstrated by both qRT-PCR and plaque assays. RVFV that was inactivated through either detergent or heat treatment was still found bound to NT53, indicating the ability to use NanoTrap particles for viral capture prior to transport to a BSL-2 environment. Our study demonstrates that NanoTrap particles are capable of capturing whole virus, and can be assayed with both qRT-PCR and plaque assays. A) Seven different types of NanoTrap particles were incubated with viral supernatants containing RVFV (1E+7 pfu/ml) for 30 minutes at room temperature and washed 4 times with water. In order to determine if the amplification observed in the qRT-PCR assay was due to the NanoTrap particle capturing intact viral particles or association of viral RNA (presumably due to lysed virus) with the particles, plaque assays were performed.

title:
  The Use of NanoTrap Particles as a Sample Enrichment Method to Enhance the Detection of Rift Valley Fever Virus

abstract:
  BACKGROUND: Rift Valley Fever Virus (RVFV) is a zoonotic virus that is not only an emerging pathogen but is also considered a biodefense pathogen due to the threat it may cause to public health and national security. The current state of diagnosis has led to misdiagnosis early on in infection. Here we describe the use of a novel sample preparation technology, NanoTrap particles, to enhance the detection of RVFV. Previous studies demonstrated that NanoTrap particles lead to both 100 percent capture of protein analytes as well as an improvement of more than 100-fold in sensitivity compared to existing methods. Here we extend these findings by demonstrating the capture and enrichment of viruses. RESULTS: Screening of NanoTrap particles indicated that one particle, NT53, was the most efficient at RVFV capture as demonstrated by both qRT-PCR and plaque assays. Importantly, NT53 capture of RVFV resulted in greater than 100-fold enrichment from low viral titers when other diagnostics assays may produce false negatives. NT53 was also capable of capturing and enhancing RVFV detection from serum samples. RVFV that was inactivated through either detergent or heat treatment was still found bound to NT53, indicating the ability to use NanoTrap particles for viral capture prior to transport to a BSL-2 environment. Furthermore, both NP-40-lysed virus and purified RVFV RNA were bound by NT53. Importantly, NT53 protected viral RNA from RNase A degradation, which was not observed with other commercially available beads. Incubation of RVFV samples with NT53 also resulted in increased viral stability as demonstrated through preservation of infectivity at elevated temperatures. Finally, NanoTrap particles were capable of capturing VEEV and HIV, demonstrating the broad applicability of NanoTrap particles for viral diagnostics. CONCLUSION: This study demonstrates NanoTrap particles are capable of capturing, enriching, and protecting RVFV virions. Furthermore, the use of NanoTrap particles can be extended to a variety of viruses, including VEEV and HIV.


id: cord-312236-8eaqn8eu
title: Study of expiratory droplet dispersion and transport using a new Eulerian modeling approach
author: Lai, Alvin C.K.
date: 2007-06-02
txt: ./txt/cord-312236-8eaqn8eu.txt
cache: ./cache/cord-312236-8eaqn8eu.txt
extension: .txt
mime: text/plain
url: https://api.elsevier.com/content/article/pii/S1352231007005031
doi: 10.1016/j.atmosenv.2007.05.045
summary:
  Aerosol droplet dispersion and transport in a ventilated enclosure depend on the ventilation scheme, particle size, density, concentration, source location, etc. The key objectives of the present work are (i) to apply the new Eulerian approach to study droplet dispersion and transport in a ventilated room, and (ii) to highlight the influence of droplet sizes and ventilation scheme on mixing characteristics. To investigate droplet nuclei dispersion and transport using the new drift-flux approach, an enclosure with two identical model occupants with heat energy dissipated is selected (Fig. 1 ). Fig. 4 shows the combined results modeled by the drift-flux and Lagrangian approaches at the breathing plane and the mid-plane for 0.75 and 2 s elapsing from the commencing of the droplet emitting process. Inferring from the results presented, it can be observed that for the well-mixed ventilation scheme, the dispersion pattern is dominated by the high velocity airflow, and the different between droplet sizes is not obvious.

abstract:
  Understanding of droplet nuclei dispersion and transport characteristics can provide more engineering strategies to control transmission of airborne diseases. Droplet dispersion in a room under the conventional well-mixed and displacement ventilation is simulated. Two droplet nuclei sizes, 0.01 and 10 μm, are selected as they represent very fine and coarse droplets. The flow field is modeled using k–ε RNG model. A new Eulerian drift-flux methodology is employed to model droplet phase. Under the conventional ventilation scheme, both fine and coarse droplets are homogeneously dispersed within approximately 50 s. Droplet nuclei exhibit distinctive dispersion behavior, particularly for low airflow microenvironment. After 270 s of droplet emission, gravitational settling influences the dispersion for 10 μm droplets, and concentration gradient can still be observed for displacement ventilation.


id: cord-313825-bbjxd86y
author: Xia, Tian
date: 2016-10-08
txt: ./txt/cord-313825-bbjxd86y.txt
cache: ./cache/cord-313825-bbjxd86y.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1093/nsr/nww064
doi: 10.1093/nsr/nww064
summary:
  The lung is the first target organ for air pollution and PM exposure is associated with reduced lung function, increased lung inflammation, asthma, respiratory infections, lung cancer and exacerbation of COPD, which lead to systemic inflammation and oxidative stress affecting blood, vasculature, heart and brain, ultimately contribute to the premature mortality ( Fig. 2) [3, 8, 14, 16] . These specific features of UFPs can significantly contribute to the adverse effects through ROS over-production by the redox-active organic chemicals and metals on particle surface, resulting in cellular oxidative stress [18, 19, 21, 44, 48] . These include: (i) carbon core of PM and UFPs could induce ROS generation and oxidative stress; (ii) catalytic conversion of PAHs to quinones by cytochrome P450 in the endoplasmic reticulum; (iii) quinone redox cycling by NADPH-dependent P450 reductase in microsomes; (iv) mitochondrial perturbation leading to electron leakage in the inner membrane; and (v) NADPH oxidase activity in the macrophage surface membrane and associated phagosomes.

title:
  Pulmonary diseases induced by ambient ultrafine and engineered nanoparticles in twenty-first century

abstract:
  Air pollution is a severe threat to public health globally, affecting everyone in developed and developing countries alike. Among different air pollutants, particulate matter (PM), particularly combustion-produced fine PM (PM(2.5)) has been shown to play a major role in inducing various adverse health effects. Strong associations have been demonstrated by epidemiological and toxicological studies between increases in PM(2.5) concentrations and premature mortality, cardiopulmonary diseases, asthma and allergic sensitization, and lung cancer. The mechanisms of PM-induced toxicological effects are related to their size, chemical composition, lung clearance and retention, cellular oxidative stress responses and pro-inflammatory effects locally and systemically. Particles in the ultrafine range (<100 nm), although they have the highest number counts, surface area and organic chemical content, are often overlooked due to insufficient monitoring and risk assessment. Yet, ample studies have demonstrated that ambient ultrafine particles have higher toxic potential compared with PM(2.5). In addition, the rapid development of nanotechnology, bringing ever-increasing production of nanomaterials, has raised concerns about the potential human exposure and health impacts. All these add to the complexity of PM-induced health effects that largely remains to be determined, and mechanistic understanding on the toxicological effects of ambient ultrafine particles and nanomaterials will be the focus of studies in the near future.


id: cord-313971-czcs1y9w
title: Airborne Microorganisms From Livestock Production Systems and Their Relation to Dust
author: Zhao, Yang
date: 2014-04-16
txt: ./txt/cord-313971-czcs1y9w.txt
cache: ./cache/cord-313971-czcs1y9w.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32288664/
doi: 10.1080/10643389.2012.746064
summary:
  Specifically, in section 2, we identify the sources, species, size distributions, and concentrations of Identifying the source of microorganisms and dust in livestock production systems helps to elucidate how airborne transmission is generated, and ultimately can help to develop and implement strategies that prevent such transmission from beginning (Bull et al., 2006; Cambra-Lopez, 2010) . Investigations of the size distribution of microorganisms and dust in livestock production systems may provide a useful overview of their quantitative importance, indicate the health risk for human and animals, and facilitate the establishment and evaluation of control techniques. Previous studies showed that the biological decay of airborne microorganisms was species-dependent and was determined by many external factors, such as humidity, oxygen concentration, temperature, ozone concentration, radiation (UV, γ -ray, X-ray), air ions, and air pollutants (CO, SO 2 , and NO x ; Benbough, 1971; Lighthart, 1973) .

abstract:
  Large amounts of airborne microorganisms are emitted from livestock production. These emitted microorganisms may associate with dust, and are suspected to pose a risk of airborne infection to humans in vicinity and to animals on other farms. However, the extent to which airborne transmission may play a role in the epidemic, and how dust acts as a carrier of microorganisms in the transmission processes is unknown. The authors present the current knowledge of the entire process of airborne transmission of microorganisms—from suspension and transportation until deposition and infection—and their relation to dust. The sampling and the mitigation techniques of airborne microorganisms and dust in livestock production systems are introduced as well.


id: cord-314009-7t1bzc7f
title: Vaccine Adjuvant Nanotechnologies
author: Barclay, T.
date: 2016-10-07
txt: ./txt/cord-314009-7t1bzc7f.txt
cache: ./cache/cord-314009-7t1bzc7f.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/B9780323399814000075
doi: 10.1016/b978-0-323-39981-4.00007-5
summary:
  The modern definition of an adjuvant includes not only classical immune stimulators but also any aspects of particle size, shape, and surface chemistry that enhance vaccine immunogenicity. 71 A self-assembling nanofibrous hydrogel induced an antibody response when tested as a vaccine delivery platform, either alone or formulated with CpG adjuvant (TLR9 agonist) as a delivery system for recombinant hepatitis B surface antigen (HBsAg). 73, 74 For example, 165 nm-diameter liposomes assembled from cationic lipid, cationic polymer, and plasmid DNA were shown to target antigen to draining lymph nodes, resulting in enhanced DC activation and immunity. These particles were specifically designed to electrostatically interact with commercial hemagglutinin antigens to generate an influenza vaccine with enhanced immune responses compared with the hemagglutinin alone. Advax, a polysaccharide adjuvant derived from delta inulin, provides improved influenza vaccine protection through broad-based enhancement of adaptive immune responses

abstract:
  The increasing sophistication of vaccine adjuvant design has been driven by improved understanding of the importance of nanoscale features of adjuvants to their immunological function. Newly available advanced nanomanufacturing techniques now allow very precise control of adjuvant particle size, shape, texture, and surface chemistry. Novel adjuvant concepts include self-assembling particles and targeted immune delivery. These individual concepts can be combined to create a single integrated vaccine nanoparticle-combining antigen, adjuvants, and DC-targeting elements. In the process, the concept of an adjuvant has broadened to include not only immune-stimulatory substances but also any design features that enhance the immune response against the relevant vaccine antigen. The modern definition of an adjuvant includes not only classical immune stimulators but also any aspects of particle size, shape, and surface chemistry that enhance vaccine immunogenicity. It even includes purely physical processes such as texturing of particle surfaces to maximize immunogenicity. Looking forward, adjuvants will increasingly be seen not as separate add-on items but as wholly integrated elements of a complete vaccine delivery package. Hence, vaccine systems will increasingly approach the complexity and sophistication of pathogens themselves, incorporating highly specific particle properties, contents, and behaviors, all designed to maximize immune system recognition and drive the immune response in the specific direction that affords maximal protection.


id: cord-318495-1w74wf02
title: Defective viral genomes are key drivers of the virus–host interaction
author: Vignuzzi, Marco
date: 2019-06-03
txt: ./txt/cord-318495-1w74wf02.txt
cache: ./cache/cord-318495-1w74wf02.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1038/s41564-019-0465-y
doi: 10.1038/s41564-019-0465-y
summary:
  The demonstration of hotspots for the generation of copyback DVGs from respiratory syncytial virus (RSV) and the identification of specific nucleotides that determine where copy-back DVGs rejoin further demonstrate that the generation of copy-back DVGs is not completely random, but instead that specific sequences encoded in the viral genome direct or facilitate their formation 50 in some infections, DVG generation is not a completely stochastic process and, instead, virus-encoded sequences favour the production and/or amplification of predominant DVGs. It remains to be determined whether conservation is a property of certain DVG types and which specific sequences and/or RNA structures lead to DVG generation in these conditions. Persistent infection with infectious pancreatic necrosis virus mediated by defective-interfering (DI) virus particles in a cell line showing strong interference but little DI replication I Interferon-inducing defective-interfering particles as mediators of cell sparing: possible role in persistent infection by vesicular stomatitis virus

abstract:
  Viruses survive often harsh host environments, yet we know little about the strategies they utilize to adapt and subsist given their limited genomic resources. We are beginning to appreciate the surprising versatility of viral genomes and how replication-competent and -defective virus variants can provide means for adaptation, immune escape and virus perpetuation. This Review summarizes current knowledge of the types of defective viral genomes generated during the replication of RNA viruses and the functions that they carry out. We highlight the universality and diversity of defective viral genomes during infections and discuss their predicted role in maintaining a fit virus population, their impact on human and animal health, and their potential to be harnessed as antiviral tools.


id: cord-319221-x834qscq
title: Numerical investigation of aerosol transport in a classroom with relevance to COVID-19
author: Abuhegazy, Mohamed
date: 2020-10-01
txt: ./txt/cord-319221-x834qscq.txt
cache: ./cache/cord-319221-x834qscq.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1063/5.0029118
doi: 10.1063/5.0029118
summary:
  The present study investigates aerosol transport and surface deposition in a realistic classroom environment using computational fluid-particle dynamics simulations. Other strategies for COVID-19 mitigation may include the use of glass screens as barriers to reduce aerosol transport between people in the room, opening windows, and redistributing students in classrooms, but the ability of these measures to reduce aerosol transmission from one person to another needs to be carefully evaluated. The objective of the present work is to investigate aerosol transport and surface deposition in a model classroom environment using computational fluid-particle dynamics (CFPD) simulations. Figure 4 shows the effect of particle size on the fraction of aerosol particles released from student 5''s mouth that deposit on different surfaces in the room, such as ground, ceiling and walls, desks, and students, or escape from the outlet of the air conditioning system.

abstract:
  The present study investigates aerosol transport and surface deposition in a realistic classroom environment using computational fluid-particle dynamics simulations. Effects of particle size, aerosol source location, glass barriers, and windows are explored. While aerosol transport in air exhibits some stochasticity, it is found that a significant fraction (24%–50%) of particles smaller than 15 µm exit the system within 15 min through the air conditioning system. Particles larger than 20 µm almost entirely deposit on the ground, desks, and nearby surfaces in the room. Source location strongly influences the trajectory and deposition distribution of the exhaled aerosol particles and affects the effectiveness of mitigation measures such as glass barriers. Glass barriers are found to reduce the aerosol transmission of 1 µm particles from the source individual to others separated by at least 2.4 m by ∼92%. By opening windows, the particle exit fraction can be increased by ∼38% compared to the case with closed windows and reduces aerosol deposition on people in the room. On average, ∼69% of 1 µm particles exit the system when the windows are open.


id: cord-322880-zfc9w5y6
author: Rohit, Anusha
date: 2020-06-09
txt: ./txt/cord-322880-zfc9w5y6.txt
cache: ./cache/cord-322880-zfc9w5y6.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32575016/
doi: 10.1016/j.mehy.2020.109958
summary:
  title: Respiratory droplets get suspended longer and spread wider in temperate environments compared to tropics and implications for SARS-CoV-2 transmission The combined effect of change in size of the droplet as well as the density amplifies the influence that environmental relative humidity would have on the particle settling velocity. It is possible that droplets discharged from infected individuals in places like New York City could shrink in size quickly and remain airborne for considerable period of time. A simple understanding of the mechanics of droplet size, dispersion and displacement could help infection control and public health measures to minimize spread and mitigate the risk of people getting infected especially in hotspots like hospital environments or other closed spaces. A simple understanding of the mechanics of droplet size, dispersion and displacement could help infection control and public health measures to minimize spread and mitigate the risk of people getting infected especially in hotspots like hospital environments or other closed spaces.

title:
  Respiratory droplets get suspended longer and spread wider in temperate environments compared to tropics and implications for SARS-CoV-2 transmission

abstract:
  The new pandemic of SARS-CoV-2 has shown stark differences in number of affected patients between countries in the tropics and those with temperate environments. Though there have been many theories on reasons for these differences, we hypothesise that this could be due to differences in the fate of respiratory droplets in the two environments. A simple understanding of the mechanics of droplet size, dispersion and displacement could help infection control and public health measures to minimize spread and mitigate the risk of people getting infected especially in hotspots like hospital environments or other closed spaces. This paper discusses the possibility of differences in number of infections and spread between different countries based on the spread of droplets.


id: cord-324585-2rx84imv
title: Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks
author: Konda, Abhiteja
date: 2020-04-24
txt: ./txt/cord-324585-2rx84imv.txt
cache: ./cache/cord-324585-2rx84imv.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1021/acsnano.0c03252
doi: 10.1021/acsnano.0c03252
summary:
  13 −16 In this paper, we report the results of experiments where we measure the filtration efficiencies of a number of common fabrics, as well as selective combinations for use as hybrid cloth masks, as a function of aerosol sizes ranging from ∼10 nm to 6 μm. 25 There have been a few studies reported on the use of cloth face masks mainly during or after the Influenza Pandemic in 2009; [8] [9] [10] [11] [12] 26 However, there is still a lack of information that includes (i) the performance of various fabrics as a function of particle size from the nanoscale to the micron sized (particularly important because this covers the ∼10 nm to ∼5 μm size scale for aerosols) and (ii) the effect of hybrid multilayer approaches for masks that can combine the benefits of different filtering mechanisms across different aerosol size ranges.

abstract:
  [Image: see text] The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10 μm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton–silk, cotton–chiffon, cotton–flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mechanical and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of “fit” and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.


id: cord-325915-dw989txm
title: Downstream processing of cell culture-derived virus particles
author: Wolf, Michael W
date: 2014-01-09
txt: ./txt/cord-325915-dw989txm.txt
cache: ./cache/cord-325915-dw989txm.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1586/erv.11.111
doi: 10.1586/erv.11.111
summary:
  The number of publications [24, [38] [39] [40] [41] [42] [43] [44] [45] [46] and patents [301] [302] [303] describing the purification or concentration of virus particles by centrifugation methods demonstrates that these procedures are extensively used at industrial-and small-scale levels for viral vectors and vaccine production processes. In summary, the main advantages of ultrafiltration compared with other methods are their high-throughput and (for the concentration of active virus particles) the gentle processing at optimal operating conditions [43, 47] that results in improved efficacies for purification of viral vectors for gene therapy. Considering a complete purification train for the production of vaccines or gene therapy vectors (Figure 1) , current improvements of the dynamic binding capacities in chromatography media might facilitate the removal of the initial concentration step within the downstream process.

abstract:
  Manufacturing of cell culture-derived virus particles for vaccination and gene therapy is a rapidly growing field in the biopharmaceutical industry. The process involves a number of complex tasks and unit operations ranging from selection of host cells and virus strains for the cultivation in bioreactors to the purification and formulation of the final product. For the majority of cell culture-derived products, efforts focused on maximization of bioreactor yields, whereas design and optimization of downstream processes were often neglected. Owing to this biased focus, downstream procedures today often constitute a bottleneck in various manufacturing processes and account for the majority of the overall production costs. For efficient production methods, particularly in sight of constantly increasing economic pressure within human healthcare systems, highly productive downstream schemes have to be developed. Here, we discuss unit operations and downstream trains to purify virus particles for use as vaccines and vectors for gene therapy.


id: cord-326409-m3rgspxc
author: Lai, Alvin C.K.
date: 2007-03-24
txt: ./txt/cord-326409-m3rgspxc.txt
cache: ./cache/cord-326409-m3rgspxc.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1016/j.atmosenv.2006.05.088
doi: 10.1016/j.atmosenv.2006.05.088
summary:
  authors: Lai, Alvin C.K.; Chen, F.Z. title: Comparison of a new Eulerian model with a modified Lagrangian approach for particle distribution and deposition indoors Results reveal that the standard k–ε Lagrangian model over-predicts particle deposition compared to the present turbulence-corrected Lagrangian approach. In the present work, we compared particle distribution and deposition rates for a small model chamber by the two approaches. (1), while within the concentration boundary layer, the particle wall flux is determined with a one-dimensional semi-empirical particle deposition model (Lai and Nazaroff, 2000) and the results are substituted into Eq. Overall speaking, the results modeled by the two approaches agree well with each other; as the particle size increases, the deposition fraction increases. For submicron particles, the deposition fractions predicted by Lagrangian (without near-wall turbulent correction) is higher than those predicted with correction and Eulerian drift flux prediction follows. Modeling indoor particle deposition from turbulent flow onto smooth surfaces

title:
  Comparison of a new Eulerian model with a modified Lagrangian approach for particle distribution and deposition indoors

abstract:
  Understanding of aerosol dispersion characteristics has many scientific and engineering applications. It is recognized that Eulerian or Lagrangian approach has its own merits and limitations. A new Eulerian model has been developed and it adopts a simplified drift–flux methodology in which external forces can be incorporated straightforwardly. A new near-wall treatment is applied to take into account the anisotropic turbulence for the modified Lagrangian model. In the present work, we present and compare both Eulerian and Lagrangian models to simulate particle dispersion in a small chamber. Results reveal that the standard k–ε Lagrangian model over-predicts particle deposition compared to the present turbulence-corrected Lagrangian approach. Prediction by the Eulerian model agrees well with the modified Lagrangian model.


id: cord-327507-ic3tdx59
author: Kirschbaum, Stephanie
date: 2020-11-09
txt: ./txt/cord-327507-ic3tdx59.txt
cache: ./cache/cord-327507-ic3tdx59.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/33165633/
doi: 10.1007/s00167-020-06344-3
summary:
  The present prospective study investigated the quantitative and qualitative particle load in the operating room (OR) depending on location, time of surgery and use of laminar air flow (LAF) system. However, recommendations of existing reviews or meta-analyses examining the use of LAF systems in reduction of surgical site infection (SSI) are usually based on inhomogeneous studies with different types and sizes of LAF systems [13, 14, 17, 18] , where there may also be a lack of standardization of possible cofounders (antibiotic prophylaxis, patient related risk factors). The aim of the present study is therefore to evaluate the quantitative and qualitative particle load in the operating room depending on the measurement location (inside LAF area, margin of LAF area and outside LAF panel), the time of surgery and the use of a LAF system.

title:
  Laminar air flow reduces particle load in TKA—even outside the LAF panel: a prospective, randomized cohort study

abstract:
  PURPOSE: Released particles are a major risk of airborne contamination during surgery. The present prospective study investigated the quantitative and qualitative particle load in the operating room (OR) depending on location, time of surgery and use of laminar air flow (LAF) system. METHODS: The particle load/m(3) was measured during the implantation of 12 total knee arthroplasties (6 × LAF, 6 × Non-LAF) by using the Met One HHPC 6 + device (Beckmann Coulter GmbH, Germany). Measurement was based on the absorption and scattering of (laser) light by particles and was performed at three different time-points [empty OR, setting up, ongoing operation) at 3 fixed measurement points [OR table (central LAF area), anaesthesia tower (marginal LAF area), surgical image amplifier (outside LAF area)]. RESULTS: Independent of time and location, all measurements showed a significantly higher particle load in the Non-LAF group (p < 0.01). With ongoing surgical procedure both groups showed increasing particle load. While there was a major increase of fine particles (size < 1 µm) with advancing activity in the LAF group, the Non-LAF group showed higher particle gain with increasing particle size. The lowest particle load in the LAF group was measured at the operating column, increasing with greater distance from the operating table. The Non-LAF group presented a significantly higher particle load than the LAF group at all locations. CONCLUSION: The use of a LAF system significantly reduces the particle load and therefore potential bacterial contamination regardless of the time or place of measurement and therefore seems to be a useful tool for infection prevention. As LAF leads to a significant decrease of respirable particles, it appears to be a protective factor for the health of the surgical team regardless of its use in infection prevention. LEVEL OF EVIDENCE: I.


id: cord-329135-g8fuax6p
title: Bioaerosol sampling: sampling mechanisms, bioefficiency and field studies
author: Haig, C.W.
date: 2016-04-01
txt: ./txt/cord-329135-g8fuax6p.txt
cache: ./cache/cord-329135-g8fuax6p.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S0195670116300044
doi: 10.1016/j.jhin.2016.03.017
summary:
  Numerous successful studies are described that point to best practice in bioaerosol sampling, from the use of small personal samplers to monitor workers'' pathogen exposure through to large static samplers collecting airborne microbes in various healthcare settings. 11, 53 If the target microbe is unknown and a general assessment of bioaerosol particles present in an environment is sought, then the use of different types of sampling devices will mitigate the limitations of individual samplers, making a comprehensive study more likely. Correlation between active and passive sampling was also described during a study comparing different ventilation regimes in OTs. 12 Using a Surface Air System sampler (SAS, International Pbi, Milan, Italy) operating at 180 L/min and settle plates, both with tryptic soy agar, the study showed that unidirectional airflows within OTs did not guarantee low counts of airborne bacteria. Effect of sampling time and air humidity on the bioefficiency of filter samplers for bioaerosol collection

abstract:
  Investigations into the suspected airborne transmission of pathogens in healthcare environments have posed a challenge to researchers for more than a century. With each pathogen demonstrating a unique response to environmental conditions and the mechanical stresses it experiences, the choice of sampling device is not obvious. Our aim was to review bioaerosol sampling, sampling equipment, and methodology. A comprehensive literature search was performed, using electronic databases to retrieve English language papers on bioaerosol sampling. The review describes the mechanisms of popular bioaerosol sampling devices such as impingers, cyclones, impactors, and filters, explaining both their strengths and weaknesses, and the consequences for microbial bioefficiency. Numerous successful studies are described that point to best practice in bioaerosol sampling, from the use of small personal samplers to monitor workers' pathogen exposure through to large static samplers collecting airborne microbes in various healthcare settings. Of primary importance is the requirement that studies should commence by determining the bioefficiency of the chosen sampler and the pathogen under investigation within laboratory conditions. From such foundations, sampling for bioaerosol material in the complexity of the field holds greater certainty of successful capture of low-concentration airborne pathogens. From the laboratory to use in the field, this review enables the investigator to make informed decisions about the choice of bioaerosol sampler and its application.


id: cord-329137-5pw07qje
author: Dryden, Kelly A.
date: 2012-10-05
txt: ./txt/cord-329137-5pw07qje.txt
cache: ./cache/cord-329137-5pw07qje.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/22743104/
doi: 10.1016/j.jmb.2012.06.029
summary:
  In addition, immature HAstV bears a striking resemblance to the structure of hepatitis E virus (HEV)-like particles, as previously predicted from structural similarity of the crystal structure of the astrovirus spike domain with the HEV P-domain [Dong, J., Dong, L., Méndez, E. Similarities between their capsid shells and dimeric spikes and between the sequences of their capsid proteins suggest that these viral families are phylogenetically related and may share common assembly and activation mechanisms. Immature, uncleaved particles, which are strikingly similar in appearance to HEV-like particles (HEV-lp), 14 Trypsin cleavage of the coat protein between the conserved (white boxes) and variable (shaded boxes) domains is required for viral maturation. If the cleaved proteins remain noncovalently associated with the capsid shell, then one would still expect to see surface density in the images of individual particles, even if the polypeptides do not conform to icosahedral symmetry.

title:
  Immature and Mature Human Astrovirus: Structure, Conformational Changes, and Similarities to Hepatitis E Virus

abstract:
  Abstract Human astroviruses (HAstVs) are a major cause of gastroenteritis. HAstV assembles from the structural protein VP90 and undergoes a cascade of proteolytic cleavages. Cleavage to VP70 is required for release of immature particles from cells, and subsequent cleavage by trypsin confers infectivity. We used electron cryomicroscopy and icosahedral image analysis to determine the first experimentally derived, three-dimensional structures of an immature VP70 virion and a fully proteolyzed, infectious virion. Both particles display T =3 icosahedral symmetry and nearly identical solid capsid shells with diameters of ~350Å. Globular spikes emanate from the capsid surface, yielding an overall diameter of ~440Å. While the immature particles display 90 dimeric spikes, the mature capsid only displays 30 spikes, located on the icosahedral 2-fold axes. Loss of the 60 peripentonal spikes likely plays an important role in viral infectivity. In addition, immature HAstV bears a striking resemblance to the structure of hepatitis E virus (HEV)-like particles, as previously predicted from structural similarity of the crystal structure of the astrovirus spike domain with the HEV P-domain [Dong, J., Dong, L., Méndez, E. & Tao, Y. (2011). Crystal structure of the human astrovirus capsid spike. Proc. Natl. Acad. Sci. USA 108, 12681–12686]. Similarities between their capsid shells and dimeric spikes and between the sequences of their capsid proteins suggest that these viral families are phylogenetically related and may share common assembly and activation mechanisms.


id: cord-332255-7sxioviw
title: Electron microscopy of the intestine of gnotobiotic piglets infected with porcine rotavirus
author: Narita, M.
date: 1982-10-31
txt: ./txt/cord-332255-7sxioviw.txt
cache: ./cache/cord-332255-7sxioviw.txt
extension: .txt
mime: text/plain
url: https://api.elsevier.com/content/article/pii/0021997582900111
doi: 10.1016/0021-9975(82)90011-1
summary:
  The pathogenesis of porcine rotavirus in gnotobiotic piglets was studied by light microscopy (LM) , fl uorescent antibody technique (FA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and it was demonstrated that clinical signs were correlated with viral replication and with induced virus lesions in the small intestine (McAdaragh, Bergeland, Meyer, Johnshoy, Stotz, Benfield and Hammer, 1980; Narita, Fukusho, Konno and Shimizu, 1982; Pearson and McNulty, 1979; Theil, Bohl, Cross, Kohler and Agnes, 1978; Torres-Medina and Underdahl, 1980) . The present paper describes the morphological changes in infected intestinal cells of 2-day-old piglets inoculated orally with porcine rotavirus and discusses the penetration of virus into the absorptive cells. These infected cells had lost most of their staining density and contained many virus particles within the distended RER. In the cytoplasm of the infected cells, non-membrane bound, granular matrices containing an electron-dense virus core were present (Fig. 8) .

abstract:
  Abstract Five gnotobiotic piglets inoculated orally with porcine rotavirus developed an enteric lesion. Electron microscopy of the mucosal epithelium 12 h after inoculation showed that the virus penetrates into the absorptive cells between microvilli, possibly by a pinocytic mechanism. Afterwards, virus particles were most often seen within dilated cisternae of the rough endoplasmic reticulum (RER). These infected cells showed a range of changes, such as disruption of the microvilli, loss of cytoplasmic density and deposition of lipid droplets. Subsequently, most of the epithelial cells were desquamated from the villi. The interaction of virus and intestinal cells thus indicates that rotavirus is pathogenic for the epithelial cells.


id: cord-336901-q6kgzuob
title: Integrated micro-optofluidic platform for real-time detection of airborne microorganisms
author: Choi, Jeongan
date: 2015-11-02
txt: ./txt/cord-336901-q6kgzuob.txt
cache: ./cache/cord-336901-q6kgzuob.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/26522006/
doi: 10.1038/srep15983
summary:
  To apply this method to real-time detection of airborne microorganisms, airborne Escherichia coli, Bacillus subtilis, and Staphylococcus epidermidis cells were introduced into the micro-optofluidic platform via bioaerosol generation, and a liquid-type particle collection setup was used. In comparison with traditional microscopy cell counting and colony culture methods, this micro-optofluidic platform is not only more accurate in terms of the detection efficiency for airborne microorganisms but it also provides additional information on the total particle number concentration. Our optofluidic system involves the following steps: (1) sampling of airborne microorganisms; (2) mixing and reacting in a microchannel for staining; and (3) real-time detection and analysis of the particle by means of light scattering (SC) and bacterial fluorescence (FL). To evaluate the particle detection efficiency for airborne microorganisms, the total concentration of bacteria obtained from the FL signal of the micro-optofluidic platform was compared with the conventional fluorescence microscopy cell counting and colony counting methods.

abstract:
  We demonstrate an integrated micro-optofluidic platform for real-time, continuous detection and quantification of airborne microorganisms. Measurements of the fluorescence and light scattering from single particles in a microfluidic channel are used to determine the total particle number concentration and the microorganism number concentration in real-time. The system performance is examined by evaluating standard particle measurements with various sample flow rates and the ratios of fluorescent to non-fluorescent particles. To apply this method to real-time detection of airborne microorganisms, airborne Escherichia coli, Bacillus subtilis, and Staphylococcus epidermidis cells were introduced into the micro-optofluidic platform via bioaerosol generation, and a liquid-type particle collection setup was used. We demonstrate successful discrimination of SYTO82-dyed fluorescent bacterial cells from other residue particles in a continuous and real-time manner. In comparison with traditional microscopy cell counting and colony culture methods, this micro-optofluidic platform is not only more accurate in terms of the detection efficiency for airborne microorganisms but it also provides additional information on the total particle number concentration.


id: cord-336948-8yqdhcnz
title: Detailed simulation of viral propagation in the built environment
author: Löhner, Rainald
date: 2020-08-05
txt: ./txt/cord-336948-8yqdhcnz.txt
cache: ./cache/cord-336948-8yqdhcnz.txt
extension: .txt
mime: text/plain
url: https://doi.org/10.1007/s00466-020-01881-7
doi: 10.1007/s00466-020-01881-7
summary:
  If, for the sake of argument, we consider Stoke''s law for the drag of spherical particles, valid below Reynolds numbers of Re = 1, the terminal sink velocity (also known as the settling velocity) of particles will be given by [26] : where ρ p , ρ g , g, μ, d denote the density of the particles (essentially water in the present case), density of the gas (air), gravity, dynamic viscosity of the gas and diameter of the particle respectively. -Spatial discretization using unstructured grids (in order to allow for arbitrary geometries and adaptive refinement); -Spatial approximation of unknowns with simple linear finite elements (in order to have a simple input/output and code structure); -Edge-based data structures (for reduced access to memory and indirect addressing); -Temporal approximation using implicit integration of viscous terms and pressure (the interesting scales are the ones associated with advection); -Temporal approximation using explicit, high-order integration of advective terms; -Low-storage, iterative solvers for the resulting systems of equations (in order to solve large 3-D problems); and -Steady results that are independent from the timestep chosen (in order to have confidence in convergence studies).

abstract:
  A summary is given of the mechanical characteristics of virus contaminants and the transmission via droplets and aerosols. The ordinary and partial differential equations describing the physics of these processes with high fidelity are presented, as well as appropriate numerical schemes to solve them. Several examples taken from recent evaluations of the built environment are shown, as well as the optimal placement of sensors.


id: cord-337957-z9ssp0rs
author: Berrouk, Abdallah S.
date: 2009-06-26
txt: ./txt/cord-337957-z9ssp0rs.txt
cache: ./cache/cord-337957-z9ssp0rs.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S0360132309001590
doi: 10.1016/j.buildenv.2009.06.016
summary:
  In this work, a well-resolved Large Eddy Simulation (LES) was performed to compute the concentration profiles of monodisperse aerosols in non-isothermal low-Reynolds turbulent flow taking place in an enclosed environment. In the present work, measurements and numerical simulations of contaminant particle concentration evolution in a mechanically ventilated room with heated sources have been carried out. However, the aim of this work is twofold: (i) to test the capabilities of the in-house code Code_Saturne to investigate aerosol transport under displacement ventilation with two heated human models using LES, (ii) to compare the aerosol concentration fields computed by both the Lagrangian and the drift-flux Eulerian approaches in the framework of LES, and (iii) to compare the experimental results with model predictions. Both measurements and numerical simulations of airflow field and particle concentration were carried out in a downscaled chamber with two identical model occupants as depicted in Fig. 1 .

title:
  Experimental measurements and large eddy simulation of expiratory droplet dispersion in a mechanically ventilated enclosure with thermal effects

abstract:
  Understanding of droplet transport in indoor environments with thermal effects is very important to comprehend the airborne pathogen infection through expiratory droplets. In this work, a well-resolved Large Eddy Simulation (LES) was performed to compute the concentration profiles of monodisperse aerosols in non-isothermal low-Reynolds turbulent flow taking place in an enclosed environment. Good care was taken to ensure that the main dynamical features of the continuous phase were captured by the present LES. The particle phase was studied in both Lagrangian and Eulerian frameworks. Steady temperature and velocity were measured prior to droplet emission. Evolution of aerosol concentration was measured by a particle counter. Results of the present LES were to compare reasonably well with the experimental findings for both phases.


id: cord-339475-okw6la2b
title: Chapter 11 Health effects
author: nan
date: 2005-12-31
txt: ./txt/cord-339475-okw6la2b.txt
cache: ./cache/cord-339475-okw6la2b.txt
extension: .txt
mime: text/plain
url: https://api.elsevier.com/content/article/pii/S1573428505800158
doi: 10.1016/s1573-4285(05)80015-8
summary:
  As an indication of their effectiveness, about one half of all 3-~tm particles inhaled through the mouth deposit in the alveolar region. As an indication of their effectiveness, about one half of all 3-~tm particles inhaled through the mouth deposit in the alveolar region. The diseases resulting from exposure to ambient aerosols include pulmonary emphysema, bronchitis, and, perhaps, lung cancer. However, none of the harmful components mentioned above exists in ambient particles at sufficiently high concentration levels to cause a specific disease. Complexity in chemical characteristics of ambient particles has led to considerable difficulty in identifying the components responsible for adverse health effects. Aerosol particles can serve as an effective carrier for ambient peroxides and reactive oxygen species to reach the alveolar region. When these reactive species are adsorbed on particle surfaces, they can easily reach the alveolar region and thereby lead to an adverse effect greater than in tracheobronchial airways. Pulmonary effects of inhaled ultrafine particles

abstract:
  Abstract There are beneficial as well as harmful aerosols. According to their nature, harmful particles can be classified into three categories: chemically toxic, infectious, and radioactive. In general, there is a relationship between the response and the dose received. A biochemically active particle may contain only a small amount of active agents. In this respect, an inhaled particle simply acts as a carrier that facilitates delivery of deleterious or beneficial components to specific surface areas of lung airways. In view of the tortuous narrow passageways and sharp turns they have to go through, aerosol particles are an effective carrier. As an indication of their effectiveness, about one half of all 3-m particles inhaled through the mouth deposit in the alveolar region.


id: cord-340639-hdn85mik
title: Unipolar ion emission enhances respiratory protection against fine and ultrafine particles
author: Uk Lee, Byung
date: 2004-11-30
txt: ./txt/cord-340639-hdn85mik.txt
cache: ./cache/cord-340639-hdn85mik.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32287371/
doi: 10.1016/j.jaerosci.2004.05.006
summary:
  The use of an improperly ÿt-tested tight-ÿtting respirator may further decrease the respiratory protection level because of the additional particle penetration that occurs through the face-seal leaks (Chen et al., 1990; Chen & Willeke, 1992; Oestenstad, Dillion, & Perkins, 1990a; Oestenstad, Perkins, & Rose, 1990b) . A breathing manikin with a face-sealed respiratory mask was exposed to the airborne polydisperse surrogate aerosols that simulated viral and bacterial particles with respect to their aerodynamic size. The natural aerosol concentration in the indoor test chamber was not su cient, particularly for the measurement inside the mask, because the ÿlter removed considerable number of ambient airborne particles. The drastic decrease of the particle penetration through the respirator ÿlter due to continuous unipolar ion emission may be critical in providing additional respiratory protection by existing masks against viral and bacterial particles.

abstract:
  Abstract We developed a novel concept that allows to considerably improve the performance of conventionally used filtering-facepiece respirators against fine and ultrafine aerosols including airborne viral and bacterial agents. The concept is based on the continuous emission of unipolar ions. The effect was evaluated through the real-time monitoring of the concentration and size distribution of fine and ultrafine aerosol particles. The measurements were conducted inside and outside of a respiratory mask that was face sealed on a breathing manikin. A commonly used Type N95 respirator and surgical mask were utilized for the tests. The manikin was placed in a 24.3-m3 indoor test chamber and exposed to polydisperse surrogate aerosols simulating viral and bacterial particles with respect to the aerodynamic size. The particle penetration through the mask was found to decrease by one-to-two orders of magnitude as a result of continuous unipolar ion emission in the chamber. The flux of air ions migrated to the breathing zone and imparted electrical charges of the same polarity to the aerosol particles and the respirator filter surface. This created an electrostatic shield along the external surface of the filter, thus enhancing the protection characteristics provided by the respirator. The above performance enhancement effect is crucial for minimizing the infectious risk in the cases when the conventional filtering-facepiece respirators are not able to provide an adequate protection against airborne viruses and bacteria.


id: cord-352743-goier9an
author: Habchi, Carine
date: 2015-07-31
txt: ./txt/cord-352743-goier9an.txt
cache: ./cache/cord-352743-goier9an.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/32288033/
doi: 10.1016/j.buildenv.2015.07.028
summary:
  In this work, a transient mathematical multi-region zonal transport model of particle behavior resulting from high momentum respiratory activities (HMRA) is developed focusing on the transient inter-personal exposure (IPE) in indoor spaces ventilated by displacement ventilation (DV) systems. Furthermore, many efforts have been made to reveal the effect of ventilation types, relative orientation between the occupants, sneezing and coughing velocities, in addition to droplet size distribution on the transient spread of exhaled droplets in variable types of indoor environments using CFD and experimental simulations. In order to assess the risk of HMRA, the effect of different variables such DV flow rate, coughing velocity, particle diameter, and distance between the occupants on cross-infection is studied. The coughing velocity largely affected the exposure during the first Fig. 8a and b illustrate respectively the effect of the particle diameter on the variation with time of the normalized concentration at the breathing level of the exposed person and the infection index.

title:
  Transient transport model of particles resulting from high momentum respiratory activities: Inter-personal exposure

abstract:
  In this work, a transient mathematical multi-region zonal transport model of particle behavior resulting from high momentum respiratory activities (HMRA) is developed focusing on the transient inter-personal exposure (IPE) in indoor spaces ventilated by displacement ventilation (DV) systems. The developed model was validated by experimentation and by published empirical data. Three stages are identified with respect to time for the variation of the IPE: a first stage dominated by the propagation and decay of the exhaled jet, a particles' redistribution stage, and a particles' removal stage. The inhaled dose is affected by the DV flow rate, cough velocity, particle diameter and distance between the occupants. The DV system with a flow rate of 100 L/s reduced significantly the inhaled dose during particle redistribution and removal stages decreasing the total inhaled dose by 83% compared to a flow rate of 50 L/s. IPE is higher when particle diameter is increased from 1 to 20 μm due to the opposition of particle removal by the upward DV. A comparison between steady and transient modeling of the IPE showed that steady modeling captures the physics affecting particle spread due to HMRA but it over-predicts the inhaled dose. It is found that for a DV flow rate of 100 L/s and a cough velocity of 22 m/s during 1 s, and 1 μm particles, the minimum required distance between the occupants for a threshold inhaled dose of 10(−5) kg is nearly 0.5 m by transient modeling while it is 2.15 m by steady state modeling.


id: cord-355883-uyrn281a
author: Zimmerman, Alyssa
date: 2020-08-07
txt: ./txt/cord-355883-uyrn281a.txt
cache: ./cache/cord-355883-uyrn281a.txt
extension: .txt
mime: text/plain
url: https://www.sciencedirect.com/science/article/pii/S1352231020305690?v=s5
doi: 10.1016/j.atmosenv.2020.117835
summary:
  title: Observations of new particle formation, modal growth rates, and direct emissions of sub-10 nm particles in an urban environment Ambient measurements were carried out at North Carolina State University in Raleigh, NC between April to June 2019 and November 2019 to May 2020 to investigate the temporal variability of size distribution and number concentration of ultrafine particles. Finally, if 227 there were nucleation mode particles present, resulting in an increase in the ultrafine particle 228 number concentration, but growth was not continuous or sustained, this event was classified as 229 Class C. Due to the 5 nm lower limit in the size distribution data, the growth rates calculated 259 between 5-10 nm were used to estimate the approximate start time of each Class A event. The general start time of all Class A events was 367 also pronounced in the diurnal variation of particle number concentration plots shown in Figure 368 5a.

title:
  Observations of new particle formation, modal growth rates, and direct emissions of sub-10 nm particles in an urban environment

abstract:
  Ultrafine particles with diameters less than 100 nm suspended in the air are a topic of interest in air quality and climate sciences. Sub-10 nm particles are of additional interest due to their health effects and contribution to particle growth processes. Ambient measurements were carried out at North Carolina State University in Raleigh, NC between April to June 2019 and November 2019 to May 2020 to investigate the temporal variability of size distribution and number concentration of ultrafine particles. A mobile lab was deployed between March and May 2020 to characterize the spatial distribution of sub-10 nm particle number concentration. New particle formation and growth events were observed regularly. Also observed were direct emissions of sub-10 nm particles. Analysis against meteorological variables, gas-phase species, and particle concentrations show that the sub-10nm particles dominated number concentration during periods of low planetary boundary layer height, low solar radiation, and northeast winds. The spatial patterns observed during mobile deployments suggest that multiple temporally stable and spatially confined point sources of sub-10 nm particles are present within the city. These sources likely include the campus utility plants and the Raleigh-Durham International Airport. Additionally, the timing of data collection allowed for investigation of variations in the urban aerosol number size distribution due to reduced economic activity during the COVID-19 pandemic.


id: cord-356116-c40e3zp7
title: Western Cold and Flu (WeCoF) aerosol study – preliminary results
author: Savory, Eric
date: 2014-08-23
txt: ./txt/cord-356116-c40e3zp7.txt
cache: ./cache/cord-356116-c40e3zp7.txt
extension: .txt
mime: text/plain
url: https://www.ncbi.nlm.nih.gov/pubmed/25148847/
doi: 10.1186/1756-0500-7-563
summary:
  FINDINGS: A novel experimental cough chamber facility – the FLUGIE – has been developed to study the far-field aerodynamics and aerosol transport of droplets produced by the coughs from humans naturally-infected with influenza. The novelty of the current collaborative research projectthe Western Cold and Flu (WeCoF) aerosol studylies in the fact that the fluid dynamics of the jet aerosols produced by a minimally-confined cough is being examined concurrently with the biological processes associated with virus droplet formation and transmission, using human subjects when they are naturally infected by influenza virus and, again, when they return to health. A novel experimental facilitythe FLUGIEhas been designed to study the far-field aerodynamics of human coughs produced by subjects naturally-infected with respiratory viruses, together with measurement of the viral content of the droplets produced by those coughs, in order to quantify the factors relating to person-toperson airborne transmission of virus.

abstract:
  BACKGROUND: Influenza virus is responsible for annual deaths due to seasonal epidemics and is the cause of major pandemics which have claimed millions of human lives over the last century. Knowledge about respiratory virus transmission is advancing. Spread is likely through the air, but much work remains to be done to characterize the aerosols produced by infected individuals, including viral particle survival and infectivity. Although coughs have been characterized, little work has been done to examine coughs from infected individuals. The WeCoF project aims at providing evidence to support prevention measures to mitigate person-to-person influenza transmission in critical locations, such as hospitals, and during pandemics. FINDINGS: A novel experimental cough chamber facility – the FLUGIE – has been developed to study the far-field aerodynamics and aerosol transport of droplets produced by the coughs from humans naturally-infected with influenza. The flow field of each cough is measured using Particle Image Velocimetry (PIV). A preliminary study involving 12 healthy individuals has been carried out in order to quantify the strengths of their coughs at a distance of 1 m from the mouth. The spatially averaged maximum velocity was determined and the average value was 0.41 m/s across 27 coughs of good data quality. The peak value of velocity was also extracted and compared with the average velocity. CONCLUSIONS: Preliminary results show that there is significant air motion associated with a cough (on the order of 0.5 m/s) as far away as 1 m from the mouth of the healthy person who coughs. The results from this pilot study provide the framework for a more extensive participant recruitment campaign that will encompass a statistically-significant cohort.


