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1
Lin, Kaisen, Chase R. Schulte et Linsey C. Marr. « Survival of MS2 and Φ6 viruses in droplets as a function of relative humidity, pH, and salt, protein, and surfactant concentrations ». PLOS ONE 15, no 12 (8 décembre 2020) : e0243505. http://dx.doi.org/10.1371/journal.pone.0243505.
Texte intégralRésumé :
The survival of viruses in droplets is known to depend on droplets’ chemical composition, which may vary in respiratory fluid between individuals and over the course of disease. This relationship is also important for understanding the persistence of viruses in droplets generated from wastewater, freshwater, and seawater. We investigated the effects of salt (0, 1, and 35 g/L), protein (0, 100, and 1000 μg/mL), surfactant (0, 1, and 10 μg/mL), and droplet pH (4.0, 7.0, and 10.0) on the viability of viruses in 1-μL droplets pipetted onto polystyrene surfaces and exposed to 20%, 50%, and 80% relative humidity (RH) using a culture-based approach. Results showed that viability of MS2, a non-enveloped virus, was generally higher than that of Φ6, an enveloped virus, in droplets after 1 hour. The chemical composition of droplets greatly influenced virus viability. Specifically, the survival of MS2 was similar in droplets at different pH values, but the viability of Φ6 was significantly reduced in acidic and basic droplets compared to neutral ones. The presence of bovine serum albumin protected both MS2 and Φ6 from inactivation in droplets. The effects of sodium chloride and the surfactant sodium dodecyl sulfate varied by virus type and RH. Meanwhile, RH affected the viability of viruses as shown previously: viability was lowest at intermediate to high RH. The results demonstrate that the viability of viruses is determined by the chemical composition of carrier droplets, especially pH and protein content, and environmental factors. These findings emphasize the importance of understanding the chemical composition of carrier droplets in order to predict the persistence of viruses contained in them.
2
Vejerano, Eric P., et Linsey C. Marr. « Physico-chemical characteristics of evaporating respiratory fluid droplets ». Journal of The Royal Society Interface 15, no 139 (février 2018) : 20170939. http://dx.doi.org/10.1098/rsif.2017.0939.
Texte intégralRésumé :
The detailed physico-chemical characteristics of respiratory droplets in ambient air, where they are subject to evaporation, are poorly understood. Changes in the concentration and phase of major components in a droplet—salt (NaCl), protein (mucin) and surfactant (dipalmitoylphosphatidylcholine)—may affect the viability of any pathogens contained within it and thus may affect the efficiency of transmission of infectious disease by droplets and aerosols. The objective of this study is to investigate the effect of relative humidity (RH) on the physico-chemical characteristics of evaporating droplets of model respiratory fluids. We labelled these components in model respiratory fluids and observed evaporating droplets suspended on a superhydrophobic surface using optical and fluorescence microscopy. When exposed to continuously decreasing RH, droplets of different model respiratory fluids assumed different morphologies. Loss of water induced phase separation as well as indication of a decrease in pH. The presence of surfactant inhibited the rapid rehydration of the non-volatile components. An enveloped virus, ϕ 6, that has been proposed as a surrogate for influenza virus appeared to be homogeneously distributed throughout the dried droplet. We hypothesize that the increasing acidity and salinity in evaporating respiratory droplets may affect the structure of the virus, although at low enough RH, crystallization of the droplet components may eliminate their harmful effects.
3
Yang, Yafeng, Yiping Wang, Linli Tian, Chuqi Su, Zhixin Chen et Yuanyi Huang. « Effects of purifiers on the airborne transmission of droplets inside a bus ». Physics of Fluids 34, no 1 (janvier 2022) : 017108. http://dx.doi.org/10.1063/5.0081230.
Texte intégralRésumé :
During an airborne infectious disease outbreak, bus passengers can be easily infected by the dispersion of exhaled droplets from an infected passenger. Therefore, measures to control the transport of droplets are necessary, such as a mask or purifier. The current research examined aerosol transport in a bus with air-conditioning. To determine the dispersion path, deposition distribution, and droplet escape time, the computational fluid dynamics were used to predict the flow field and the dispersion of droplets considering the effects of droplet size, location of the infected person, and purifier type. In addition, based on the viability and the number of virus particles in a droplet, the total number of virus particles inhaled by passengers over a 4-h journey was obtained by the superposition method. The Wells–Riley equation was then used to assess the infection risk of the passengers in the bus cabin. The results showed that droplets with a size of 1–20 μm have essentially the same deposition characteristics, and the location of the infected passenger affects the distribution of droplets' transport and the effectiveness of a purifier in removing droplets. A purifier can effectively remove droplets from passengers' coughs and reduce the infection risk of passengers. The performance of the smaller purifiers is not as stable as that of the larger purifiers, and the performance is influenced by the airflow structure where the infected passenger is located.
4
Ahlawat, Ajit, Sumit Kumar Mishra, Hartmut Herrmann, Pradhi Rajeev, Tarun Gupta, Vikas Goel, Yele Sun et Alfred Wiedensohler. « Impact of Chemical Properties of Human Respiratory Droplets and Aerosol Particles on Airborne Viruses’ Viability and Indoor Transmission ». Viruses 14, no 7 (8 juillet 2022) : 1497. http://dx.doi.org/10.3390/v14071497.
Texte intégralRésumé :
The airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as a potential pandemic challenge, especially in poorly ventilated indoor environments, such as certain hospitals, schools, public buildings, and transports. The impacts of meteorological parameters (temperature and humidity) and physical property (droplet size) on the airborne transmission of coronavirus in indoor settings have been previously investigated. However, the impacts of chemical properties of viral droplets and aerosol particles (i.e., chemical composition and acidity (pH)) on viability and indoor transmission of coronavirus remain largely unknown. Recent studies suggest high organic content (proteins) in viral droplets and aerosol particles supports prolonged survival of the virus by forming a glassy gel-type structure that restricts the virus inactivation process under low relative humidity (RH). In addition, the virus survival was found at neutral pH, and inactivation was observed to be best at low (<5) and high pH (>10) values (enveloped bacteriophage Phi6). Due to limited available information, this article illustrates an urgent need to research the impact of chemical properties of exhaled viral particles on virus viability. This will improve our fundamental understanding of indoor viral airborne transmission mechanisms.
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Chan, K. H., J. S. Malik Peiris, S. Y. Lam, L. L. M. Poon, K. Y. Yuen et W. H. Seto. « The Effects of Temperature and Relative Humidity on the Viability of the SARS Coronavirus ». Advances in Virology 2011 (2011) : 1–7. http://dx.doi.org/10.1155/2011/734690.
Texte intégralRésumé :
The main route of transmission of SARS CoV infection is presumed to be respiratory droplets. However the virus is also detectable in other body fluids and excreta. The stability of the virus at different temperatures and relative humidity on smooth surfaces were studied. The dried virus on smooth surfaces retained its viability for over 5 days at temperatures of 22–25°C and relative humidity of 40–50%, that is, typical air-conditioned environments. However, virus viability was rapidly lost (>3 log10) at higher temperatures and higher relative humidity (e.g., 38°C, and relative humidity of >95%). The better stability of SARS coronavirus at low temperature and low humidity environment may facilitate its transmission in community in subtropical area (such as Hong Kong) during the spring and in air-conditioned environments. It may also explain why some Asian countries in tropical area (such as Malaysia, Indonesia or Thailand) with high temperature and high relative humidity environment did not have major community outbreaks of SARS.
6
Alexander, Robert W., Jianghan Tian, Allen E. Haddrell, Henry P. Oswin, Edward Neal, Daniel A. Hardy, Mara Otero-Fernandez et al. « Mucin Transiently Sustains Coronavirus Infectivity through Heterogenous Changes in Phase Morphology of Evaporating Aerosol ». Viruses 14, no 9 (24 août 2022) : 1856. http://dx.doi.org/10.3390/v14091856.
Texte intégralRésumé :
Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential to understanding and developing methods of restricting their dissemination. Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with a comparative kinetics electrodynamic balance (CKEDB) measurements allow for a direct comparison between viral viability and evaporation kinetics of the aerosol with a time resolution of seconds. Here, we report the airborne survival of mouse hepatitis virus (MHV) and determine a comparable loss of infectivity in the aerosol phase to our previous observations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Through the addition of clinically relevant concentrations of mucin to the bioaerosol, there is a transient mitigation of the loss of viral infectivity at 40% RH. Increased concentrations of mucin promoted heterogenous phase change during aerosol evaporation, characterised as the formation of inclusions within the host droplet. This research demonstrates the role of mucus in the aerosol phase and its influence on short-term airborne viral stability.
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Samaranayake, Lakshman. « COVID-19 and Dentistry : Aerosol and Droplet Transmission of SARS-CoV-2, and Its Infectivity in Clinical Settings ». Dental Update 47, no 7 (2 juillet 2020) : 600–602. http://dx.doi.org/10.12968/denu.2020.47.7.600.
Texte intégralRésumé :
In the last inaugural issue of the Commentary we discussed the origins of the SARS-CoV-2, the probable reasons for its emergence, and how the virus spreads due to the rapid, inter-continental, mass transportation, as well as the human behaviour leading to deforestation and massive urbanization and environmental changes. Here, we outline the issues surrounding infectivity of the SARS-CoV-2, plus its spread through aerosols, droplets and aerosol generating procedures (AGPs) in the dental clinic milieu, as well as its viability in the ambient environment.
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Joshi, Anushka. « Long Term Complications Associated with Covid-19 : A Review ». Volume 5 - 2020, Issue 9 - September 5, no 9 (20 septembre 2020) : 324–26. http://dx.doi.org/10.38124/ijisrt20sep144.
Texte intégralRésumé :
The covid-19 has spread rapidly throughout the china and globally. This highly transmissible disease till date has infected around 17 million people worldwide. The infection spreads through the sputum or the droplets generated by the infected person by sneezing, coughing or talking. The droplets can settle down on the surfaces and floors or can remain in air where the viability of the virus varies from few minutes to several days. People can also get infected on coming in close proximity of the infected person. The patients experience mild to high fever, sore throat, headache, myalgia, tastelessness and shortness of breath along with pneumonia like symptoms in serious cases. A large number of asymptomatic cases were also reported making the detection difficult in early stages. The recovery rate as of now has reached to 78%, and fatality rates are low, still people are prone to various other long term symptoms after recovery which is a matter of concern. The researchers and scientists have found prominent effect on nervous system and other vital functions of the body, this article gives a brief review of such complications.
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Chacín-Bonilla, Leonor, et Nathalie Chacón. « SARS-CoV-2 : Potential feco-oral transmission and implications on the spread and severity of COVID-19 in Venezuela. Mini-review ». Investigación Clínica 62 (30 juillet 2021) : 58–68. http://dx.doi.org/10.22209/ic.v62s2a05.
Texte intégralRésumé :
The recognized human-to-human transmission of SARS-CoV-2 is through respiratory droplets and contact with contaminated surfaces. However, the high transmissibility of the virus and the pattern of symptoms of COVID-19 suggest the likelihood of other forms of spread. Increasing evidence suggests that SARS‐CoV‐2 could be transmitted by the feco‐oral route. SARS-CoV-2 is known to infect gastrointestinal epithelial cells and a significant number of infected people have gastrointestinal symptoms. Viable viruses, viral RNA, and prolonged shedding of viral RNA have been detected in the feces of COVID-19 patients. The virus has been found in sewage and surface waters of several countries. The possible feco-oral transmission of SARS-CoV-2 could be significant in low-income countries. High poverty levels and the collapse of health and other public services might increase the risk of Venezuelans to suffer a more devastating impact from COVID-19 than other populations. In conclusion, the feco-oral transmission of SARS-CoV-2 has not been demonstrated. However, it is conceivable and the impact of COVID-19 could be high in low-income countries, especially in Venezuela due to its humanitarian crisis. The lack of information on the viability and infectivity of the virus in wastewaters and surface waters and the risk of transmission of the infection are important gaps in knowledge that deserve further investigation.
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Micochova, Petra, Ambika Chadha, Timi Hesseloj, Franca Fraternali, Jeremy J. Ramsden et Ravindra K. Gupta. « Rapid inactivation of SARS-CoV-2 by titanium dioxide surface coating ». Wellcome Open Research 6 (11 mars 2021) : 56. http://dx.doi.org/10.12688/wellcomeopenres.16577.1.
Texte intégralRésumé :
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission occurs via airborne droplets and surface contamination. Titanium dioxide (TiO2) coating of surfaces is a promising infection control measure, though to date has not been tested against SARS-CoV-2. Methods: Virus stability was evaluated on TiO2- and TiO2–Ag (Ti:Ag atomic ratio 1:0.04)-coated 45 x 45 mm ceramic tiles. After coating the tiles were stored for 2–4 months before use. We tested the stability of both SARS-CoV-2 Spike pseudotyped virions based on a lentiviral system, as well as fully infectious SARS-CoV-2 virus. For the former, tile surfaces were inoculated with SARS-CoV-2 spike pseudotyped HIV-1 luciferase virus. At intervals virus was recovered from surfaces and target cells infected. For live virus, after illuminating tiles for 0–300 min virus was recovered from surfaces followed by infection of Vero E6 cells. % of infected cells was determined by flow cytometry detecting SARS-CoV-2 nucleocapsid protein 24 h post-infection. Results: After 1 h illumination the pseudotyped viral titre was decreased by four orders of magnitude. There was no significant difference between the TiO2 and TiO2–Ag coatings. Light alone had no significant effect on viral viability. For live SARS-CoV-2, virus was already significantly inactivated on the TiO2 surfaces after 20 min illumination. After 5 h no detectable active virus remained. Significantly, SARS-CoV-2 on the untreated surface was still fully infectious at 5 h post-addition of virus. Overall, tiles coated with TiO2 120 days previously were able to inactivate SARS-CoV-2 under ambient indoor lighting with 87% reduction in titres at 1h and complete loss by 5h exposure. Conclusions: In the context of emerging viral variants with increased transmissibility, TiO2 coatings could be an important tool in containing SARS-CoV-2, particularly in health care facilities where nosocomial infection rates are high.
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Micochova, Petra, Ambika Chadha, Timi Hesseloj, Franca Fraternali, Jeremy J. Ramsden et Ravindra K. Gupta. « Rapid inactivation of SARS-CoV-2 by titanium dioxide surface coating ». Wellcome Open Research 6 (9 septembre 2021) : 56. http://dx.doi.org/10.12688/wellcomeopenres.16577.2.
Texte intégralRésumé :
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission occurs via airborne droplets and surface contamination. Titanium dioxide (TiO2) coating of surfaces is a promising infection control measure, though to date has not been tested against SARS-CoV-2. Methods: Virus stability was evaluated on TiO2- and TiO2–Ag (Ti:Ag atomic ratio 1:0.04)-coated 45 x 45 mm ceramic tiles. After coating the tiles were stored for 2–4 months before use. We tested the stability of both SARS-CoV-2 Spike pseudotyped virions based on a lentiviral system, as well as fully infectious SARS-CoV-2 virus. For the former, tile surfaces were inoculated with SARS-CoV-2 spike pseudotyped HIV-1 luciferase virus. At intervals virus was recovered from surfaces and target cells infected. For live virus, after illuminating tiles for 0–300 min virus was recovered from surfaces followed by infection of Vero E6 cells. % of infected cells was determined by flow cytometry detecting SARS-CoV-2 nucleocapsid protein 24 h post-infection. Results: After 1 h illumination the pseudotyped viral titre was decreased by four orders of magnitude. There was no significant difference between the TiO2 and TiO2–Ag coatings. Light alone had no significant effect on viral viability. For live SARS-CoV-2, virus was already significantly inactivated on the TiO2 surfaces after 20 min illumination. After 5 h no detectable active virus remained. Significantly, SARS-CoV-2 on the untreated surface was still fully infectious at 5 h post-addition of virus. Overall, tiles coated with TiO2 120 days previously were able to inactivate SARS-CoV-2 under ambient indoor lighting with 87% reduction in titres at 1h and complete loss by 5h exposure. Conclusions: In the context of emerging viral variants with increased transmissibility, TiO2 coatings could be an important tool in containing SARS-CoV-2, particularly in health care facilities where nosocomial infection rates are high.
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Florea, Radu Marian, et Camelia Madalina Sultana. « COVID-19 and breastfeeding : can SARS-CoV-2 be spread through lactation ? » Discoveries 9, no 2 (30 juin 2021) : e132. http://dx.doi.org/10.15190/d.2021.11.
Texte intégralRésumé :
SARS-CoV-2 is a new betacoronavirus that was first reported in the Hubei province, China, in December 2019. The virus is likely transmitted through air droplets. However, there are reported cases where SARS-CoV-2-RNA was found in other samples, such as blood or stool. Nonetheless, there is limited information concerning the presence of viral RNA in pregnancy-related samples, specifically breast milk. However unlikely, there is still uncertainty regarding the possibility of vertical transmission from mother to infant through breastfeeding. This review aims to synthetize the literature written so far on this topic. Despite not being extensively researched, vertical transmission through breast milk seems unlikely. Case series showed that milk samples from mothers with COVID-19 were almost entirely negative. So far, there have been only 9 recorded cases of viral shedding in milk samples, uncertain however of the viability of the particles. Furthermore, WHO and UNICEF strongly encourage commencing breastfeeding after parturition, underlining the benefits of lactation. Moreover, some studies have proven the existence of IgG and IgA anti-SARS-CoV-2-antibodies in the maternal milk that could possibly play an important part in the neonate’s protection against the virus. Vertical transmission through lactation seems unlikely, most studies pointing towards the safety of breastfeeding. However, further larger-scale studies need to be performed in order to clarify a yet uncertain matter.
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Cano Pérez, Eder, Jaison Torres-Pacheco, Génesis García-Díaz et María Carolina Fragozo-Ramos. « Faecal-oral transmission of SARS-CoV-2 : a threat to Latin America ? » Journal of Medical Care Research and Review 3, no 7 (29 juillet 2020) : 401–3. http://dx.doi.org/10.15520/mcrr.v3i7.118.
Texte intégralRésumé :
We are living in times when a viral pandemic has stopped normal life in much of the world. The new viral agent named Coronavirus 2 of the Severe Acute Respiratory Syndrome (SARS-CoV-2), was found to be the cause of the so-called Coronavirus Disease 2019 (COVID-19). This new coronavirus is closely related to other emerging zoonotic coronaviruses, such as the etiological agent of Severe Acute Respiratory Syndrome (SARS-CoV) and the Coronavirus related to the Middle East Respiratory Syndrome (MERS-CoV), which can cause disease severe in humans (1). Early symptoms in most COVID-19 patients include fever, dyspnea, cough, and sore throat, which can progress to pneumonia in severe cases. Other symptoms such as some gastrointestinal manifestations, including diarrhea, are less frequent (2).
Respiratory droplets and contact transmission are considered the most important routes of transmission of COVID-19 but do not fully explain the occurrence of all cases and the rapid spread of this new virus (3). Recently, some studies have reported evidence of the presence of SARS-CoV-2 RNA in feces and wastewater, which raises the possibility of faecal-oral transmission of COVID-19. Some investigations have shown that the positivity of SARS-CoV-2 in the feces remains between 7 and 33 days after the samples of nasopharyngeal swabs were negative, increasing the possibility that the virus is transmitted through contaminated fomites (4, 5). Other studies have managed to isolate the virus present in the feces, determining the viability of the virus in these samples, showing the potential risk of faecal-oral contagion (3). Another associated intrinsic concern is the possibility of mechanical transmission of insect-mediated SARS-CoV-2. Vectors such as flies and cockroaches circulate in environments where feces are present and may carry viruses on their body and in their intestinal tract, contaminating surfaces (6).
In recent months, studies have emerged where they detect the genetic material of SARS-CoV-2 in wastewater (7). However, there is still no evidence of the viability of SARS-CoV-2 in these water sources. A study conducted on SARS-CoV during the outbreak in 2003 showed that the virus remains active in running water for 10 days at 23°C, while at low temperatures of 4°C the viability of the virus can reach up to 100 days. In wastewater, the viability of the virus decreases by 99.99% between 2-3 days at temperatures ~20°C and up to 14 days at 4°C (8). Considering the above, three possible environmental routes have been proposed for faecal-oral transmission of SARS-CoV-2 in humans from the feces. Within the main routes, it is found, the water, the surfaces, and the contact with the places where the vector insects circulate. From these environments, through different routes, viruses can reach the mouth and infect the intestinal and respiratory tracts of a susceptible host (9).
To date, there have been no reports of humans contracting the SARS-CoV-2 virus through faecal-oral transmission, however, this possible mechanism itself represents a potential risk for the spread and transmission of COVID-19 in the Latin American context, considering that about 191 million people are living in poverty and 72 million in extreme poverty. This means that 30.8% of Latin Americans are poor, and 11.5% are extremely poor. This supposes that part of the population does not have the necessary resources such as food, drinking water, or managed sanitation (10). Additionally, disadvantaged people are more likely to live in overcrowded accommodation, with poor housing conditions, limited access to personal outdoor space, and overcrowding, factors that increase exposure to COVID-19.
In conclusion, despite the need for more studies, if the "faecal-oral hypothesis" is confirmed as a transmission mechanism for COVID-19, it may result in far-reaching consequences for public health and pandemic control, especially in regions with fragile health systems such as Latin America, so studies are required to evaluate the influence of environmental factors on COVID-19 in the region.
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Brahim Belhaouari, Djamal, Nathalie Wurtz, Clio Grimaldier, Alexandre Lacoste, Gabriel Augusto Pires de Souza, Gwilherm Penant, Sihem Hannat, Jean-Pierre Baudoin et Bernard La Scola. « Microscopic Observation of SARS-Like Particles in RT-qPCR SARS-CoV-2 Positive Sewage Samples ». Pathogens 10, no 5 (24 avril 2021) : 516. http://dx.doi.org/10.3390/pathogens10050516.
Texte intégralRésumé :
The ongoing outbreak of novel coronavirus pneumonia (COVID-19) caused by SARS-CoV-2 infection has spread rapidly worldwide. The major transmission routes of SARS-CoV-2 are recognised as inhalation of aerosol/droplets and person-to-person contact. However, some studies have demonstrated that live SARS-CoV-2 can be isolated from the faeces and urine of infected patients, which can then enter the wastewater system. The currently available evidence indicates that the viral RNA present in wastewater may become a potential source of epidemiological data. However, to investigate whether wastewater may present a risk to humans such as sewage workers, we investigated whether intact particles of SARS-CoV-2 were observable and whether it was possible to isolate the virus in wastewater. Using a correlative strategy of light microscopy and electron microscopy (CLEM), we demonstrated the presence of intact and degraded SARS-like particles in RT-qPCR SARS-CoV-2-positive sewage sample collected in the city of Marseille. However, the viral infectivity assessment of SARS-CoV-2 in the wastewater was inconclusive, due to the presence of other viruses known to be highly resistant in the environment such as enteroviruses, rhinoviruses, and adenoviruses. Although the survival and the infectious risk of SARS-CoV-2 in wastewater cannot be excluded from our study, additional work may be required to investigate the stability, viability, fate, and decay mechanisms of SARS-CoV-2 thoroughly in wastewater.
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Ratnayake Mudiyanselage, Vilanya, Kevin Lee et Alireza Hassani. « Integration of IoT Sensors to Determine Life Expectancy of Face Masks ». Sensors 22, no 23 (3 décembre 2022) : 9463. http://dx.doi.org/10.3390/s22239463.
Texte intégralRésumé :
Personal protective equipment (PPE) is widely used around the world to protect against environmental hazards. With the emergence of the COVID-19 virus, the use of PPE domestically has increased dramatically. People use preventive and protective mechanisms now more than ever, leading to the important question of how protective is the PPE that is being used. Face masks are highly recommended or mandatory during the time of the COVID-19 pandemic due to their protective features against aerosol droplets. However, an issue faced by many users of face masks is that they are entirely manual, with users having to decide for themselves whether their mask is still protective or if they should replace their mask. Due to the difficulty in determining this, people tend to overuse masks beyond their optimal usage. The research presented in this paper is an investigation of the viability of integrating IoT sensors into masks that are capable of collecting data to determine its usage. This paper demonstrates the usage of humidity and temperature sensors for the purpose of determining a mask’s usage status based on changes in these variables when a mask is put on and taken off. An evaluation was made on the usage of the two sensors, with the conclusion that a humidity sensor provides more accurate results. From this, we present a framework that takes into consideration the factors that affect a mask’s performance, such as time, humidity and temperature, to calculate the life expectancy of a mask.
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Zhen, Qi, Anxiao Zhang, Qiong Huang, Jing Li, Yiming Du et Qi Zhang. « Overview of the Role of Spatial Factors in Indoor SARS-CoV-2 Transmission : A Space-Based Framework for Assessing the Multi-Route Infection Risk ». International Journal of Environmental Research and Public Health 19, no 17 (2 septembre 2022) : 11007. http://dx.doi.org/10.3390/ijerph191711007.
Texte intégralRésumé :
The COVID-19 pandemic has lasted from 2019 to 2022, severely disrupting human health and daily life. The combined effects of spatial, environmental, and behavioral factors on indoor COVID-19 spread and their interactions are usually ignored. Especially, there is a lack of discussion on the role of spatial factors in reducing the risk of virus transmission in complex and diverse indoor environments. This paper endeavours to summarize the spatial factors and their effects involved in indoor virus transmission. The process of release, transport, and intake of SARS-CoV-2 was reviewed, and six transmission routes according to spatial distance and exposure way were classified. The triangular relationship between spatial, environmental and occupant behavioral parameters during virus transmission was discussed. The detailed effects of spatial parameters on droplet-based, surface-based and air-based transmission processes and virus viability were summarized. We found that spatial layout, public-facility design and openings have a significant indirect impact on the indoor virus distribution and transmission by affecting occupant behavior, indoor airflow field and virus stability. We proposed a space-based indoor multi-route infection risk assessment framework, in which the 3D building model containing detailed spatial information, occupant behavior model, virus-spread model and infection-risk calculation model are linked together. It is also applicable to other, similar, respiratory infectious diseases such as SARS, influenza, etc. This study contributes to developing building-level, infection-risk assessment models, which could help building practitioners make better decisions to improve the building’s epidemic-resistance performance.
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Pourchez, Jérémie, Aurélien Peyron, Gwendoline Sarry, Lara Leclerc, Paul O. Verhoeven, Peter Choi, Claude Pierson, Olivier Petit, Francisco Hernández et Carmen Dumitrescu. « Antimicrobial Performance of an Innovative Technology of Atmospheric Plasma Reactors against Bioaerosols : Effectiveness in Removing Airborne Viable Viruses ». Buildings 12, no 10 (1 octobre 2022) : 1587. http://dx.doi.org/10.3390/buildings12101587.
Texte intégralRésumé :
Reducing the exposure to airborne contaminants, including bioaerosols containing viruses, is a key challenge in the context of indoor air quality. This study aims to assess the effectiveness of innovative Atmospheric Plasma Reactor (APR) technology, which can be included in air cleaner devices, as an engineering control tool for reducing the concentration of viable airborne viruses. We investigated the KillViDTM APR technology that uses ultra-high electric fields and pulsed power plasma to directly electroporate living cells and produce advanced oxidizing species in situ within the micro-droplet aerosols containing the pathogens to be treated. An experimental setup was developed in order to aerosolize a high concentration of virus suspension directly into the air cleaner, containing 3 or 6 modules of 215 atmospheric plasma micro-reactors. As a virus surrogate, we used the phi11 bacteriophage which was aerosolized using a vibrating mesh nebulizer. The viability of airborne viruses after a single pass through the air cleaner was assessed by quantifying the lysis of a specific Staphylococcus aureus host strain. We were able to demonstrate that our virucidal results were robust and showed a 5-log reduction (99.999%) in terms of virucidal activity for the 3-module configuration, while we observed at least a 6-log reduction (from an initial viral load of 9.25 × 105 PFU to 0) for the 6-module configuration.
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Domingues, Joana M., Marta O. Teixeira, Marta A. Teixeira, David Freitas, Samira F. da Silva, Shafagh D. Tohidi, Rui D. V. Fernandes et al. « Inhibition of Escherichia Virus MS2, Surrogate of SARS-CoV-2, via Essential Oils-Loaded Electrospun Fibrous Mats : Increasing the Multifunctionality of Antivirus Protection Masks ». Pharmaceutics 14, no 2 (27 janvier 2022) : 303. http://dx.doi.org/10.3390/pharmaceutics14020303.
Texte intégralRésumé :
One of the most important measures implemented to reduce SARS-CoV-2 transmission has been the use of face masks. Yet, most mask options available in the market display a passive action against the virus, not actively compromising its viability. Here, we propose to overcome this limitation by incorporating antiviral essential oils (EOs) within polycaprolactone (PCL) electrospun fibrous mats to be used as intermediate layers in individual protection masks. Twenty EOs selected based on their antimicrobial nature were examined for the first time against the Escherichia coli MS2 virus (potential surrogate of SARS-CoV-2). The most effective were the lemongrass (LGO), Niaouli (NO) and eucalyptus (ELO) with a virucidal concentration (VC) of 356.0, 365.2 and 586.0 mg/mL, respectively. PCL was processed via electrospinning, generating uniform, beadless fibrous mats. EOs loading was accomplished via two ways: (1) physisorption on pre-existing mats (PCLaEOs), and (2) EOs blending with the polymer solution prior to fiber electrospinning (PCLbEOs). In both cases, 10% v/v VC was used as loading concentration, so the mats’ stickiness and overwhelming smell could be prevented. The EOs presence and release from the mats were confirmed by UV-visible spectroscopy (≈5257–631 µg) and gas chromatography-mass spectrometry evaluations (average of ≈14.3% EOs release over 4 h), respectively. PCLbEOs mats were considered the more mechanically and thermally resilient, with LGO promoting the strongest bonds with PCL (PCLbLGO). On the other hand, PCLaNO and PCLaELO were deemed the least cohesive combinations. Mats modified with the EOs were all identified as superhydrophobic, capable of preventing droplet penetration. Air and water-vapor permeabilities were affected by the mats’ porosity (PCL < PCLaEOs < PCLbEOs), exhibiting a similar tendency of increasing with the increase of porosity. Antimicrobial testing revealed the mats’ ability to retain the virus (preventing infiltration) and to inhibit its action (log reduction averaging 1). The most effective combination against the MS2 viral particles was the PCLbLGO. These mats’ scent was also regarded as the most pleasant during sensory evaluation. Overall, data demonstrated the potential of these EOs-loaded PCL fibrous mats to work as COVID-19 active barriers for individual protection masks.
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Gu, Alan Y., Yanzhe Zhu, Jing Li et Michael R. Hoffmann. « Speech-generated aerosol settling times and viral viability can improve COVID-19 transmission prediction ». Environmental Science : Atmospheres 2, no 1 (2022) : 34–45. http://dx.doi.org/10.1039/d1ea00013f.
Texte intégralRésumé :
Speech generates droplets averaged 6 μm in size. Their settling time and SARS-CoV-2 viral viability inside those droplets, both calculated from temperature and relative humidity, predict COVID transmission rates within one-sigma interval.
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Ng, Wei Long, Xi Huang, Viktor Shkolnikov, Guo Liang Goh, Ratima Suntornnond et Wai Yee Yeong. « Controlling Droplet Impact Velocity and Droplet Volume : Key Factors to Achieving High Cell Viability in Sub-Nanoliter Droplet-based Bioprinting ». International Journal of Bioprinting 8, no 1 (28 octobre 2021) : 424. http://dx.doi.org/10.18063/ijb.v8i1.424.
Texte intégralRésumé :
Three-dimensional (3D) bioprinting systems serve as advanced manufacturing platform for the precise deposition of cells and biomaterials at pre-defined positions. Among the various bioprinting techniques, the drop-on-demand jetting approach facilitates deposition of pico/nanoliter droplets of cells and materials for study of cell-cell and cell-matrix interactions. Despite advances in the bioprinting systems, there is a poor understanding of how the viability of primary human cells within sub-nanoliter droplets is affected during the printing process. In this work, a thermal inkjet system is utilized to dispense sub-nanoliter cell-laden droplets, and two key factors – droplet impact velocity and droplet volume – are identified to have significant effect on the viability and proliferation of printed cells. An increase in the cell concentration results in slower impact velocity, which leads to higher viability of the printed cells and improves the printing outcome by mitigating droplet splashing. Furthermore, a minimum droplet volume of 20 nL per spot helps to mitigate evaporation-induced cell damage and maintain high viability of the printed cells within a printing duration of 2 min. Hence, controlling the droplet impact velocity and droplet volume in sub-nanoliter bioprinting is critical for viability and proliferation of printed human primary cells.
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Netz, Roland R., et William A. Eaton. « Physics of virus transmission by speaking droplets ». Proceedings of the National Academy of Sciences 117, no 41 (24 septembre 2020) : 25209–11. http://dx.doi.org/10.1073/pnas.2011889117.
Texte intégralRésumé :
To make the physics of person-to-person virus transmission from emitted droplets of oral fluid while speaking easily understood, we present simple and transparent algebraic equations that capture the essential physics of the problem. Calculations with these equations provide a straightforward way of determining whether emitted droplets remain airborne or rapidly fall to the ground, after accounting for the decrease in droplet size from water evaporation. At a relative humidity of 50%, for example, droplets with initial radii larger than about 50 μm rapidly fall to the ground, while smaller, potentially virus-containing droplets shrink in size from water evaporation and remain airborne for many minutes. Estimates of airborne virion emission rates while speaking strongly support the proposal that mouth coverings can help contain the COVID-19 pandemic.
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Kaviani, Behzad, et Dariusz Kulus. « Cryopreservation of Endangered Ornamental Plants and Fruit Crops from Tropical and Subtropical Regions ». Biology 11, no 6 (31 mai 2022) : 847. http://dx.doi.org/10.3390/biology11060847.
Texte intégralRésumé :
Horticultural crops comprise various economic species extending from fruits, nuts, vegetables, spices and condiments, ornamentals, aromatic, and medicinal plants. Ornamental and fruit plants are produced mainly for their nutritional and aesthetic values, respectively. Unfortunately, many tropical and subtropical species are in danger of extinction because of climate change and (a)biotic stresses. It is imperative to preserve the germplasms of these species for the present and future genetic improvement programs. Cryopreservation, i.e., maintenance of tissues at the ultralow temperature of liquid nitrogen, is a promising long-term preservation technique, alternative to seed or in vitro banks, which can be applied for both vegetatively and generatively (through seeds) propagated crops, including those with recalcitrant seeds. It is a technology of choice not only for the preservation of plant biodiversity but also for virus elimination in the proficient administration of large-scale micropropagation. The main advantages of cryopreservation are the lowering of in vitro culture expenditures, needed space, contamination risk, and operator errors. However, tropical species are temperature delicate and one of the foremost challenging issues is preconditioning treatments that stimulate physiological reactions to sufficiently enhance tolerance to dehydration and cryogenic procedures. In recent years, several cryopreservation methods based on encapsulation-vitrification, droplet-vitrification, the use of aluminum cryo-plates, and cryo-mesh have been established. Combined cryo-techniques, gene/DNA conservation, as well as studies on perceiving bio-molecular events and exploring the multistage process from the beginning to end of cryopreservation are receiving more emphasis. The development of cryobiomics delivers a conceptual framework to assess the significance of cell signaling mechanisms on cellular functions, the influence of cryoinjury factors on sample viability, and the implications for genetic stability following cryo-storage. The aim of this mini-review article is to provide a succinct synthesis of the developed cryogenic procedures and their use for the storage and exchange of genetic resources of tropical and subtropical horticultural crops, particularly fruit crops and ornamental plants under the threat of extinction.
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Mohd Isa, Nur Suaidah, Hani El Kadri, Daniele Vigolo et Konstantinos Gkatzionis. « The Effect of Bacteria on the Stability of Microfluidic-Generated Water-in-Oil Droplet ». Micromachines 13, no 12 (25 novembre 2022) : 2067. http://dx.doi.org/10.3390/mi13122067.
Texte intégralRésumé :
Microencapsulation in emulsion droplets has great potential for various applications such as food which require formation of highly stable emulsions. Bacterial-emulsion interactions affect the physiological status of bacteria while bacterial cell characteristics such as surface-active properties and metabolic activity can affect emulsion stability. In this study, the viability and growth of two different bacterial species, Gram-negative Escherichia coli and Gram-positive Lactobacillus paracasei, encapsulated in water-in-oil (W/O) droplets or as planktonic cells, were monitored and their effect on droplet stability was determined. Microencapsulation of bacteria in W/O droplets with growth media or water was achieved by using a flow-focusing microfluidic device to ensure the production of highly monodispersed droplets. Stability of W/O droplets was monitored during 5 days of storage. Fluorescence microscopy was used to observe bacterial growth behaviour. Encapsulated cells showed different growth to planktonic cells. Encapsulated E. coli grew faster initially followed by a decline in viability while encapsulated L. paracasei showed a slow gradual growth throughout storage. The presence of bacteria increased droplet stability and a higher number of dead cells was found to provide better stability due to high affinity towards the interface. The stability of the droplets is also species dependent, with E. coli providing better stability as compared to Lactobacillus paracasei.
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Osna, Natalia. « Hepatitis C virus, alcohol and lipid droplets ». International Journal of Hepatobiliary and Pancreatic Diseases 5 (2015) : 1. http://dx.doi.org/10.5348/ijhpd-2015-26-ed-1.
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McLauchlan, John. « Lipid droplets and hepatitis C virus infection ». Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids 1791, no 6 (juin 2009) : 552–59. http://dx.doi.org/10.1016/j.bbalip.2008.12.012.
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Bhavani Balasundaraekar, R Akash Pande, P. Karthikeyan et P. Dhasarathan. « Investigation of self-assembly and topological changes in the sessile droplets of Klebsiella oxytoca by Chronological study ». international journal of engineering technology and management sciences 6, no 6 (28 novembre 2022) : 278–85. http://dx.doi.org/10.46647/ijetms.2022.v06i06.045.
Texte intégralRésumé :
The infectious droplet from the patient self-assembles into a novel pattern depending on bacterial interaction with substrate and liquid. The spatial location of bacteria inside the droplet fluctuates depending on the non-covalent forces. The deformation and dehydration induced stress on bacteria in evaporating contagious-fluid droplets alters the viability and infectivity. The self-assembly of Klebsiella oxytoca (KO) in contagious sessile droplets was studied by natural evaporation. KO forms novel patterns as the droplets exsiccate, thus revealing the unexplored topological changes that govern its survival and infection strategies. The droplets of both bacterial suspension in Milli-Q and SRF of volume 0.95 ± 0.1 μl were placed on the glass material for assessment of the self-assembly. The bacterial suspension was stained before allowing them to desicate. The bacterial chemotaxis and deposition near the end of evaporation are recorded using the bright and dark field optical method. The random time interval is also measured to track the bacterial movement. The investigation shows that the majority of the bacterial population moves toward the rim of the droplet because of edge closely packing, leading to enhanced viability and pathogenesis on the famously known “coffee ring” and few bacteria are present at the centre of the droplet which represents chemotaxis of bacteria. The mechanistic insight gained via our study can have far-reaching implications for bacterial infection through droplets e.g., through open wounds.
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Boulant, Steeve, Paul Targett-Adams et John McLauchlan. « Disrupting the association of hepatitis C virus core protein with lipid droplets correlates with a loss in production of infectious virus ». Journal of General Virology 88, no 8 (1 août 2007) : 2204–13. http://dx.doi.org/10.1099/vir.0.82898-0.
Texte intégralRésumé :
In infected cells, hepatitis C virus (HCV) core protein is targeted to lipid droplets, which serve as intracellular storage organelles. Using a tissue culture system to generate infectious HCV, we have shown that the coating of lipid droplets by the core protein occurs in a time-dependent manner and coincides with higher rates of virus production. At earlier times, the protein was located at punctate sites in close proximity to the edge of lipid droplets. Investigations by using Z-stack analysis have shown that many lipid droplets contained a single punctate site that could represent positions where core transfers from the endoplasmic reticulum membrane to droplets. The effects of lipid droplet association on virus production were studied by introducing mutations into the domain D2, the C-terminal region of the core protein necessary for droplet attachment. Alteration of a phenylalanine residue that was crucial for lipid droplet association generated an unstable form of the protein that could only be detected in the presence of a proteasome inhibitor. Moreover, converting two proline residues in D2 to alanines blocked coating of lipid droplets by core, although the protein was directed to punctate sites that were indistinguishable from those observed at early times for wild-type core protein. Neither of these virus mutants gave rise to virus progeny. By contrast, mutation at a cysteine residue positioned 2 aa upstream of the phenylalanine residue did not affect lipid droplet localization and produced wild-type levels of infectious progeny. Taken together, our findings indicate that lipid droplet association by core is connected to virus production.
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Miao, Hanwen. « Safe Distance Mathematical Calculation and Quantitative Analysis on Covid-19 Using Einstein Equation and Gaussian Distribution ». Journal of Physics : Conference Series 2083, no 4 (1 novembre 2021) : 042055. http://dx.doi.org/10.1088/1742-6596/2083/4/042055.
Texte intégralRésumé :
Abstract Most of the diseases caused by virus mainly spread through droplets in the air. The pathogen bearing droplets go deep into people’s lungs and cause infection. In this paper, we analyze the safe distance, the minimum range to keep droplets containing virus particles from entering lungs, and thereby carrying the virus inside the lung. Einstein equation for diffusivity of a particle and the wide of the Gaussian distribution of the particles in Brownian movement are used in the calculation of the range a virus-containing mucosal vary droplet can reach. Moreover, we used datas recorded in a previous paper named “Visualization of sneeze ejecta: steps of fluid fragmentation leading to respiratory droplets” by B. E. Scharfman et. all to generate our results.
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BARDELL, D. « Herpes Simplex Virus Type 1 Applied Experimentally to Gloves Used for Food Preparation ». Journal of Food Protection 58, no 10 (1 octobre 1995) : 1150–52. http://dx.doi.org/10.4315/0362-028x-58.10.1150.
Texte intégralRésumé :
Droplets of saliva containing herpes simplex virus type 1 were placed on latex disposable gloves. The temperature at the surface of the gloved hand was 34°C. There was no loss of infectious virus before 15 min. Between 15 and 30 min there was a 2-log-cycle drop in titer, and infectious virus could still be recovered after 1 h, the longest period tested. The drop in titer was due to drying of the saliva, which occurred at approximately 21 min. Infectious virus was transferred by touch to lettuce and ham at 0 min when the virus-containing droplets were in a liquid condition, and after 30 and 60 min when the droplets were dry.
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Clément, Sophie, Catherine Fauvelle, Emilie Branche, Vincent Kaddai, Stéphanie Conzelmann, Tujana Boldanova, Birke Bartosch, Kaori Minehira et Francesco Negro. « Role of seipin in lipid droplet morphology and hepatitis C virus life cycle ». Journal of General Virology 94, no 10 (1 octobre 2013) : 2208–14. http://dx.doi.org/10.1099/vir.0.054593-0.
Texte intégralRésumé :
Infectious hepatitis C virus (HCV) particle assembly starts at the surface of lipid droplets, cytoplasmic organelles responsible for neutral fat storage. We analysed the relationship between HCV and seipin, a protein involved in lipid droplet maturation. Although seipin overexpression did not affect the total mean volume occupied by lipid droplets nor the total triglyceride and cholesterol ester levels per cell, it caused an increase in the mean diameter of lipid droplets by 60 %, while decreasing their total number per cell. The latter two effects combined resulted in a 34 % reduction of the total outer surface area of lipid droplets per cell, with a proportional decrease in infectious viral particle production, probably due to a defect in particle assembly. These results suggest that the available outer surface of lipid droplets is a critical factor for HCV release, independent of the neutral lipid content of the cell.
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Jones, Gareth, Philip H. King, Hywel Morgan, Maurits R. R. de Planque et Klaus-Peter Zauner. « Autonomous Droplet Architectures ». Artificial Life 21, no 2 (mai 2015) : 195–204. http://dx.doi.org/10.1162/artl_a_00156.
Texte intégralRésumé :
The quintessential living element of all organisms is the cell—a fluid-filled compartment enclosed, but not isolated, by a layer of amphiphilic molecules that self-assemble at its boundary. Cells of different composition can aggregate and communicate through the exchange of molecules across their boundaries. The astounding success of this architecture is readily apparent throughout the biological world. Inspired by the versatility of nature's architecture, we investigate aggregates of membrane-enclosed droplets as a design concept for robotics. This will require droplets capable of sensing, information processing, and actuation. It will also require the integration of functionally specialized droplets into an interconnected functional unit. Based on results from the literature and from our own laboratory, we argue the viability of this approach. Sensing and information processing in droplets have been the subject of several recent studies, on which we draw. Integrating droplets into coherently acting units and the aspect of controlled actuation for locomotion have received less attention. This article describes experiments that address both of these challenges. Using lipid-coated droplets of Belousov-Zhabotinsky reaction medium in oil, we show here that such droplets can be integrated and that chemically driven mechanical motion can be achieved.
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Abbas, Shahzada Nadeem, Umber Rauf, Afshan Saleem, Natasha Saleem, Tayyba Basheer, Sidra Yaseen, Nida Irfan et Asif Naushad. « COVID-19 Pandemic : A Remedial Measure Through Convalescent Serum ». International Journal of Innovations in Science and Technology 2, no 2 (21 juin 2020) : 46–50. http://dx.doi.org/10.33411/ijist/2020020202.
Texte intégralRésumé :
An acute respiratory syndrome Corona Virus 2 has affected humanity throughout the world. Scientifically, Corona Virus 2 is known as SARS-COV-2 which is abbreviated as COVID-2019. China was the first victim of this outbreaks in December 2019 [1] which was later recognized as pandemic on March 11, 2020 by World Health Organization (WHO) [2,3]. At the time of this writing, about 8.75 million individuals of 188 countries [4] have been effected by COVID resulting in 463000 deaths primarily, corona virus communicates from one body to another body through close contacts via droplets produced by sneezing, coughing or taking by infected badly within a buffer zone of 3 to 6 feet [5,6,7]. These droplets fall onto a surface and can survive up to 72 hours [8]. Various studies have proved that droplets may travel up to 37 feet by an uncovered cough [9,10,11]. Corona virus is not an airborne, however it may transport through respiratory droplets during talking and breathing [12].
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Doke, Onkar, Anagha Kaldhone, Rupali Karkar, Raisa Shaikh et Salani Sahani. « AN APPRAISAL OUTLINE ON CORONA VIRUS ». International Journal of Research in Ayurveda and Pharmacy 12, no 1 (2 mars 2021) : 118–23. http://dx.doi.org/10.7897/2277-4343.120126.
Texte intégralRésumé :
A respiratory infection owing to a novel corona virus was first identified in Wuhan, China in December 2019. World health organization declared name for this novel corona virus as “COVID-19” is now a worldwide pandemic and has been recognized in more than 200 countries. Corona viruses are virus that is known to cause infection varying from the common cold to more critical diseases like Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). It is known to transmit by respiratory droplets released when corona virus patient coughs, sneezes or talks and if another person inhales the droplets or touches these surfaces and further touches his face, eyes or mouth can get an infection. Currently there are no specific vaccines or medicines for Corona virus disease and treatment given based on symptoms. But many vaccines are under investigation.
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Qin, Zhao-Ling, Qiu-Feng Yao, Hao Ren, Ping Zhao et Zhong-Tian Qi. « Lipid Droplets and Their Participation in Zika Virus Infection ». International Journal of Molecular Sciences 23, no 20 (20 octobre 2022) : 12584. http://dx.doi.org/10.3390/ijms232012584.
Texte intégralRésumé :
Lipid droplets (LDs) are highly conserved and dynamic intracellular organelles. Their functions are not limited to serving as neutral lipid reservoirs; they also participate in non-energy storage functions, such as cell lipid metabolism, protection from cell stresses, maintaining protein homeostasis, and regulating nuclear function. During a Zika virus (ZIKV) infection, the viruses hijack the LDs to provide energy and lipid sources for viral replication. The co-localization of ZIKV capsid (C) protein with LDs supports its role as a virus replication platform and a key compartment for promoting the generation of progeny virus particles. However, in view of the multiple functions of LDs, their role in ZIKV infection needs further elucidation. Here, we review the basic mechanism of LD biogenesis and biological functions and discuss how ZIKV infection utilizes these effects of LDs to facilitate virus replication, along with the future application strategy of developing new antiviral drugs based on the interaction of ZIKV with LDs.
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Roingeard, P., et C. Hourioux. « Hepatitis C virus core protein, lipid droplets and steatosis ». Journal of Viral Hepatitis 15, no 3 (17 décembre 2007) : 157–64. http://dx.doi.org/10.1111/j.1365-2893.2007.00953.x.
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Das, Santosh K., Jan-e. Alam, Salvatore Plumari et Vincenzo Greco. « Transmission of airborne virus through sneezed and coughed droplets ». Physics of Fluids 32, no 9 (1 septembre 2020) : 097102. http://dx.doi.org/10.1063/5.0022859.
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Filipe, Ana, et John McLauchlan. « Hepatitis C virus and lipid droplets : finding a niche ». Trends in Molecular Medicine 21, no 1 (janvier 2015) : 34–42. http://dx.doi.org/10.1016/j.molmed.2014.11.003.
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Fukasawa, Masayoshi. « Cellular Lipid Droplets and Hepatitis C Virus Life Cycle ». Biological & ; Pharmaceutical Bulletin 33, no 3 (2010) : 355–59. http://dx.doi.org/10.1248/bpb.33.355.
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Sharma, Kamlesh, Ram Lal Sharma et Vanita Sharma. « Corona virus epidemiology : a review article ». International Journal Of Community Medicine And Public Health 7, no 12 (25 novembre 2020) : 5219. http://dx.doi.org/10.18203/2394-6040.ijcmph20205207.
Texte intégralRésumé :
Corona virus disease-2019 is an infectious disease caused by SARS-Co-2. The disease started in December 2019 in Wuhan, China resulting in pandemic. Common symptoms are fever, cough and shortness of breath. Loss of apetite, anosmia, conjunctivitis and diarrhoea are fewer common symptoms. The disease is mild in most people but may progress to pneumonia, acute respiratory distress syndrome in elderly patients and those with co-morbidities. The infection is spread from one person to another via respiratory droplets or contact with infected droplets. Preventive measures include frequent and thorough hand washing, maintaining distance from potential transmitter and not touching one’s face. Mask is recommended to suspects and to their caregivers. Presently there is no vaccine or specific treatment for COVID-19. Management involves treatment of symptoms, supportive care. World health organisation declared the 2019-2020 CoV outbreak a pandemic and a Public Health Emergency of International concern with death rate of 3.4%.
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Seprianto, Seprianto, Molani Paulina Hasibuan et Ratih Permana Sari. « PEMBUATAN MASKER WATERPROOF BERBAHAN POLYESTER UNTUK MENCEGAH PENULARAN DROPLET BAKTERI DAN VIRUS DALAM UPAYA PEMUTUSAN MATA RANTAI PENULARAN COVID-19 ». Martabe : Jurnal Pengabdian Kepada Masyarakat 4, no 1 (26 mars 2021) : 235. http://dx.doi.org/10.31604/jpm.v4i1.235-239.
Texte intégralRésumé :
The Covid-19 pandemic has plagued almost all parts of the world. The virus is transmitted by droplets, droplets, or in medical terms known as droplets when someone coughs, sneezes, or talks. There are two ways of transmitting the corona virus through droplets, namely directly and indirectly. The use of masks in preventing direct transmission of the virus is an important thing to do. Making waterproof masks made from polyester fabrics that are waterproof, splash or droplet seepage is an alternative for people to get proper masks without having to spend a lot of money. The use of a waterproof mask made from polyester cloth is not only more economical, but also more environmentally friendly because it can be reused. The simple manufacturing process and easy and inexpensive materials allow this business to be accepted by the community. This waterproof mask making training can improve the readiness of the people of Langsa City, especially Lhokbanie Village, to face the Covid-19 pandemic. The mask products produced from this training can also be used repeatedly so that they can protect the environment.
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Püschell, K., F. Mohsenian, R. Laufs, S. Polywka et M. Ermer. « Postmortem viability of the human immunodeficiency virus ». International Journal of Legal Medicine 104, no 2 (mars 1991) : 109–10. http://dx.doi.org/10.1007/bf01626041.
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Yadav, Vibha. « An Overview On Transmission Of Diseases In Special Reference To COVID-19 And Potential Targets To Control This Pandemic ». Advances in Microbiology Research 4, no 1 (30 septembre 2020) : 1–6. http://dx.doi.org/10.24966/amr-694x/100015.
Texte intégralRésumé :
With its initial outbreak in China, the virus was referred as "coronavirus". WHO has named it "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). It has been described as the successor to SARS-CoV-1 which is a positive-sense single-stranded RNA virus. The virus spreads mainly between people who are in close contact (less than two metres or six feet) through small droplets produced during coughing, sneezing, or talking. Infected people exhale the contaminated droplets which are then inhaled into the lungs, or settle on other non- infected people's faces his/her mucosae (mouth and nose) or conjunctiva (eyes) get exposed to potentially infective respiratory droplets to cause new infection. Organism may enter to human cells by binding to the receptor angiotensin converting enzyme 2 (ACE2). Research works are in progress to find potential targets to control the pandemic. To control and treat the virus various targets are under study and these targets range from modulating host cell receptor for the virus entry to generate an effective adaptive immune response.
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Sussman, Roberto A., Eliana Golberstein et Riccardo Polosa. « Modeling Aerial Transmission of Pathogens (Including the SARS-CoV-2 Virus) through Aerosol Emissions from E-Cigarettes ». Applied Sciences 11, no 14 (9 juillet 2021) : 6355. http://dx.doi.org/10.3390/app11146355.
Texte intégralRésumé :
We examine the plausibility of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets that might be carried by exhaled e-cigarette aerosol (ECA). Given the lack of empiric evidence on this phenomenon, we consider available evidence on cigarette smoking and respiratory droplet emission from mouth breathing through a mouthpiece as convenient proxies to infer the capacity of vaping to transport pathogens in respiratory droplets. Since both exhaled droplets and ECA droplets are within the Stokes regime, the ECA flow acts effectively as a visual tracer of the expiratory flow. To infer quantitatively the direct exposure distance, we consider a model that approximates exhaled ECA flow as an axially symmetric intermittent steady starting jet evolving into an unstable puff, an evolution that we corroborate by comparison with photographs and videos of actual vapers. On the grounds of all this theoretical modeling, we estimate for low-intensity vaping (practiced by 80–90% of vapers) the emission of 6–210 (median 39.9, median deviation 67.3) respiratory submicron droplets per puff and a horizontal distance spread of 1–2 m, with intense vaping possibly emitting up to 1000 droplets per puff in the submicron range with a distance spread over 2 m. The optical visibility of the ECA flow has important safety implications, as bystanders become instinctively aware of the scope and distance of possible direct contagion through the vaping jet.
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McLauchlan, John. « Hepatitis C virus : viral proteins on the move ». Biochemical Society Transactions 37, no 5 (21 septembre 2009) : 986–90. http://dx.doi.org/10.1042/bst0370986.
Texte intégralRésumé :
There is now increasing evidence that LDs (lipid droplets) play a central role in the production of infectious HCV (hepatitis C virus) and participate in virus assembly. Two viral proteins, namely core, which forms the capsid, and NS5A (non-structural 5A protein), a component of complexes engaged in viral RNA synthesis, are detected at LD surfaces in infected cells. Interactions between the two proteins may be critical for anchoring RNA replication sites to droplets for initiating virus assembly. The requirements for targeting of core in particular has received considerable attention since the nature of its interaction with LDs could play a key role in determining the efficiency of virion production. As well as attaching to droplets, core is able to alter their intracellular distribution and direct them towards the microtubule organizing centre. Inhibitors that disrupt microtubules block this redistribution by core and there is a concomitant decrease in virus production. Therefore altered dynamics of LDs may contribute to HCV assembly and release. The purpose of targeting LDs by HCV may be linked to their contribution to the formation of VLDLs (very-low-density lipoproteins) in hepatocytes since virus circulating in infected patients is associated with lipoprotein. Thus HCV may utilize the role played by LDs in the formation of lipoprotein particles as part of its life cycle and access this pathway by direct interaction of viral components with these intracellular storage organelles.
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SÁDLOVÁ, J., et P. VOLF. « Occurrence of Leishmania major in sandfly urine ». Parasitology 118, no 5 (mai 1999) : 455–60. http://dx.doi.org/10.1017/s0031182099004254.
Texte intégralRésumé :
Promastigotes of Leishmania major were frequently detected in the urine droplets discharged by infected Phlebotomus papatasi and P. duboscqi females during feeding. Parasites were present in the urine of 37·5% P. papatasi and 16·1% P. duboscqi females, even in those with low intensity gut infections. Free-swimming forms (elongated nectomonads, short slender promastigotes and metacyclic forms) predominated in excreted droplets. Viability of excreted parasites was proved by cultivation on blood agar, and the presence of metacyclic forms in urine droplets was confirmed by specific fluorescence assay with 3F12 antibodies. While the release of promatigotes from the anus of the sandfly was frequent, these were rarely egested from the mouth-parts of sandfly females (1·3% for P. duboscqi and 0% for P. papatasi) fed on microcapillaries, even if the females were heavily infected. The possible role and significance of the discharge of parasites in sandfly urine are discussed.
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BARDELL, D. « Survival of Herpes Simplex Virus Type 1 on Some Common Foods Routinely Touched before Consumption ». Journal of Food Protection 60, no 10 (1 octobre 1997) : 1259–61. http://dx.doi.org/10.4315/0362-028x-60.10.1259.
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Droplets of saliva containing herpes simplex virus type 1 were placed on the skin of tomatoes and the upper surface of lettuce leaves. There was no loss of virus infectivity titer at refrigerator temperature (2°C) at any time examined up to 1 h, the longest period tested. At room temperature (22 to 24°C) there was a 2-log drop in titer between 30 and 60 min, but some infectious virus was still present at 1 h. The virus-containing saliva remained in a liquid state at 2°C. At 22 to 24°C the droplets became dry at approximately 50 min. Implications of the findings are discussed.
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TZENG, Y. L., L. E. MARTIN et D. S. STEPHENS. « Environmental survival ofNeisseria meningitidis ». Epidemiology and Infection 142, no 1 (10 avril 2013) : 187–90. http://dx.doi.org/10.1017/s095026881300085x.
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SUMMARYNeisseria meningitidisis transmitted through the inhalation of large human respiratory droplets, but the risk from contaminated environmental surfaces is controversial. Compared toStreptococcus pneumoniaeandAcinetobacter baumanni, meningococcal viability after desiccation on plastic, glass or metal surfaces decreased rapidly, but viable meningococci were present for up to 72 h. Encapsulation did not provide an advantage for meningococcal environmental survival on environmental surfaces.
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Bhat, Sourabh P., B. V. Rathish Kumar, Shainath Ramesh Kalamkar, Vinay Kumar, Sudhir Pathak et Walter Schneider. « Modeling and simulation of the potential indoor airborne transmission of SARS-CoV-2 virus through respiratory droplets ». Physics of Fluids 34, no 3 (mars 2022) : 031909. http://dx.doi.org/10.1063/5.0085495.
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Respiratory viruses are transported from an infected person to other neighboring people through respiratory droplets. These small droplets are easily advected by air currents in a room and can potentially infect others. In this work, the spread of droplets released during coughing, talking, and normal breathing is numerically analyzed in a typical conference room setting. The room space is occupied by ten people, with eight people sitting around a conference table and two people standing. Four different scenarios are considered, with the air-conditioning turned on/off and people wearing/not-wearing masks, to understand the spread of respiratory droplets inside the room. The flow in the room is simulated using a multiphase mixture model with properties computed for the inhaled and exhaled air using fundamental gas relations. The transport of respiratory droplets is analyzed using the discrete phase model with a range of droplet sizes fitted to data from previous experimental studies. The mask is modeled as porous media with the properties of a woven fabric computed using a newly developed model for multilayered homemade masks. The human inhalation and exhalation are modeled using analytical functions to mimic the biological flow patterns during breathing, coughing, and talking. Important observations about the air flow and dispersion of respiratory droplets in the conference room are presented based on the numerical analysis. Animations of all the results are included to provide insight into flow physics of the various dynamic conditions occurring in the room during an ongoing meeting. Although this study is conducted for a typical conference room, the newly developed models and techniques can be applied to other confined environments.
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Chandra Shekar, N. V., B. Abhinay, C. Raj Pavan et R. Harish. « Controlling virus droplets diffusion in an isolated room using CFD ». IOP Conference Series : Materials Science and Engineering 1128, no 1 (1 avril 2021) : 012003. http://dx.doi.org/10.1088/1757-899x/1128/1/012003.
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Farías, Mónica A., Benjamín Diethelm-Varela, Areli J. Navarro, Alexis M. Kalergis et Pablo A. González. « Interplay between Lipid Metabolism, Lipid Droplets, and DNA Virus Infections ». Cells 11, no 14 (17 juillet 2022) : 2224. http://dx.doi.org/10.3390/cells11142224.
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Lipid droplets (LDs) are cellular organelles rich in neutral lipids such as triglycerides and cholesterol esters that are coated by a phospholipid monolayer and associated proteins. LDs are known to play important roles in the storage and availability of lipids in the cell and to serve as a source of energy reserve for the cell. However, these structures have also been related to oxidative stress, reticular stress responses, and reduced antigen presentation to T cells. Importantly, LDs are also known to modulate viral infection by participating in virus replication and assembly. Here, we review and discuss the interplay between neutral lipid metabolism and LDs in the replication cycle of different DNA viruses, identifying potentially new molecular targets for the treatment of viral infections.