The inactivation of viruses in aerosol particles (aerosols) and droplets depends on many factors, but the precise mechanisms of inactivation are not known. The system involves complex physical and biochemical interactions. We reviewed the literature to establish current knowledge about these mechanisms and identify knowledge gaps. We identified 168 relevant papers and grouped results by the following factors: virus type and structure, aerosol or droplet size, temperature, relative humidity (RH) and evaporation, chemical composition of the aerosol or droplet, pH and atmospheric composition. These factors influence the dynamic microenvironment surrounding a virion and thus may affect its inactivation. Results indicate that viruses experience biphasic decay as the carrier aerosols or droplets undergo evaporation and equilibrate with the surrounding air, and their final physical state (liquid, semi-solid or solid) depends on RH. Virus stability, RH and temperature are interrelated, but the effects of RH are multifaceted and still not completely understood. Studies on the impact of pH and atmospheric composition on virus stability have raised new questions that require further exploration. The frequent practice of studying virus inactivation in large droplets and culture media may limit our understanding of inactivation mechanisms that are relevant for transmission, so we encourage the use of particles of physiologically relevant size and composition in future research.

In this study, we review various strategies to couple sample processing in microfluidic droplets with different separation techniques, including liquid chromatography, mass spectrometry, and capillary electrophoresis. Separation techniques interfaced with droplet microfluidics represent an emerging trend in analytical chemistry, in which micro to femtoliter droplets serve as microreactors, a bridge between analytical modules, as well as carriers of target analytes between sample treatment and separation/detection steps. This allows to overcome the hurdles encountered in separation science, notably the low degree of module integration, working volume incompatibility, and cross contamination between different operational stages. For this droplet-separation interfacing purpose, this review covers different instrumental designs from all works on this topic up to May 2023, together with our viewpoints on respective advantages and considerations. Demonstration and performance of droplet-interfaced separation strategies for limited sample volumes are also discussed.

BACKGROUND: With the COVID-19 pandemic, the idea of universal mask wearing to prevent infecting others when one becomes infected has prevailed among people. In general, any workplace is not exempt and workers are required to wear a mask while working at the sites.
OBJECTIVE: This study aims to integrate information to assist workers to select effective protectors for the prevention of droplet infection even at workplaces without occupational health personnel.
METHODS: A total of 94 studies were included in this study: 91 studies were identified in MEDLINE, which was used for the literature search, and an additional three studies were identified from other information sources. The studies were checked to eliminate duplication and narrowed down to 31 based on the titles and abstracts. The contents of the 31 studies were read through and then 19 studies were extracted for careful reading.
CONCLUSIONS: Regarding the protectors used at workplaces, it was suggested that (1) workers continue to use respiratory protectors as needed at sites where respiratory protectors such as an N95 respirator had to be used even before the spread of COVID-19 and (2) wear surgical masks, multi-layer cloth masks, or hybrid fabric masks made of several types of fabrics that are recommended in terms of preventing dissemination of droplets and protecting against inhalation of droplets, selected according to the working conditions, taking account of air permeability, breathability, and durability.

Covid-19 has triggered an unprecedented global health crisis. The highly contagious nature and airborne transmission route of SARS-CoV-2 virus requires extraordinary measures for its containment. It is necessary to know the behaviour of aerosols carrying the virus to avoid this contagion. This paper describes the behaviour of aerosols and their role in the transmission of SARS-CoV-2 according to published models using a scoping review based on the PubMed, Scopus, and WOS databases. From an initial 530 references, 9 papers were selected after applying defined inclusion criteria. The results reinforce the airborne transmission route as a means of contagion of the virus and recommend the use of face masks, extending social distance to more than 2 metres, and natural ventilation of enclosed spaces as preventive measures. These results contribute to a better understanding of SARS-CoV-2 and help design effective strategies to prevent its spread.

Scientists across disciplines, policymakers, and journalists have voiced frustration at the unprecedented polarization and misinformation around coronavirus disease 2019 (COVID-19) pandemic. Several false dichotomies have been used to polarize debates while oversimplifying complex issues. In this comprehensive narrative review, we deconstruct six common COVID-19 false dichotomies, address the evidence on these topics, identify insights relevant to effective pandemic responses, and highlight knowledge gaps and uncertainties. The topics of this review are: 1) Health and lives vs. economy and livelihoods, 2) Indefinite lockdown vs. unlimited reopening, 3) Symptomatic vs. asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, 4) Droplet vs. aerosol transmission of SARS-CoV-2, 5) Masks for all vs. no masking, and 6) SARS-CoV-2 reinfection vs. no reinfection. We discuss the importance of multidisciplinary integration (health, social, and physical sciences), multilayered approaches to reducing risk (\"Emmentaler cheese model\"), harm reduction, smart masking, relaxation of interventions, and context-sensitive policymaking for COVID-19 response plans. We also address the challenges in understanding the broad clinical presentation of COVID-19, SARS-CoV-2 transmission, and SARS-CoV-2 reinfection. These key issues of science and public health policy have been presented as false dichotomies during the pandemic. However, they are hardly binary, simple, or uniform, and therefore should not be framed as polar extremes. We urge a nuanced understanding of the science and caution against black-or-white messaging, all-or-nothing guidance, and one-size-fits-all approaches. There is a need for meaningful public health communication and science-informed policies that recognize shades of gray, uncertainties, local context, and social determinants of health.

Three-dimensional (3D) bioprinting has become mainstream for precise and repeatable high-throughput fabrication of complex cell cultures and tissue constructs in drug testing and regenerative medicine, food products, dental and medical implants, biosensors, and so forth. Due to this tremendous growth in demand, an overwhelming amount of hardware manufacturers have recently flooded the market with different types of low-cost bioprinter models-a price segment that is most affordable to typical-sized laboratories. These machines range in sophistication, type of the underlying printing technology, and possible add-ons/features, which makes the selection process rather daunting (especially for a nonexpert customer). Yet, the review articles available in the literature mostly focus on the technical aspects of the printer technologies under development, as opposed to explaining the differences in what is already on the market. In contrast, this paper provides a snapshot of the fast-evolving low-cost bioprinter niche, as well as reputation profiles (relevant to delivery time, part quality, adherence to specifications, warranty, maintenance, etc.) of the companies selling these machines. Specifically, models spanning three dominant technologies-microextrusion, droplet-based/inkjet, and light-based/crosslinking-are reviewed. Additionally, representative examples of high-end competitors (including up-and-coming microfluidics-based bioprinters) are discussed to highlight their major differences and advantages relative to the low-cost models. Finally, forecasts are made based on the trends observed during this survey, as to the anticipated trickling down of the high-end technologies to the low-cost printers. Overall, this paper provides insight for guiding buyers on a limited budget toward making informed purchasing decisions in this fast-paced market.

In the current scenario of the COVID 19 pandemic, the protective reflexes, namely sneeze and cough, have received great importance. However, it is not in terms of protection but in terms of the spread of infection. The present review tries to bring out the correlation between the physiology of sneeze and cough, taking into consideration the various receptors that initiate the two reflexes, then correlating it with the formation of expelled droplets and the significance of various aspects of droplets that lead to the spread of infection.
For the compilation of the present review, we searched the terms \"Physiology of cough\", \"Physiology of sneeze\", \"droplets\", \"aerosols\" and \"Aerosols in COVID 19\". The above-mentioned terms were extensively searched on PubMed, Google Scholar, and google search engine. After reviewing the various available material, the most significant research has been considered for this review.
Through this review, we conclude that there are various factors responsible for the initiation of sneeze and cough, but in the case of infection, it is mainly the inflammatory reaction that directly stimulates the receptors to produce the reflex outburst air. As the flow of air during expiration is turbulent, it causes damage to the Epithelial Lining Fluid present in the respiratory conduit. In addition, it gets admixed with the saliva in the oropharynx and oral cavity and mucus in the nose to form droplets of various sizes. Large droplets settle close and are responsible for droplet and fomite transmission, but the smaller droplets remain suspended in the air and travel farther distances to cause airborne transmission. The spread of droplet cloud in sneezing may range to 6m or more as compared to cough; hence the concept of 1m to 2m of social distancing does not hold reliable if the patient is sneezing.

Since the widespread of severe acute respiratory syndrome of coronavirus 2 (SARS-CoV-2) disease, the utilization of face masks has become omnipresent all over the world. Face masks are believed to contribute to an adequate protection against respiratory infections spread through micro-droplets among the infected person to non-infected others. However, due to the very high demands of face masks, especially the N95-type mask typically worn by medical workers, the public faces a shortage of face masks. Many papers have been published recently that focus on developing new and facile techniques to reuse and reinforce commercially available face masks. For instance, the N95 mask uses a polymer-based (membrane) filter inside, and the filter membrane can be replaced if needed. Another polymer sputtering technique by using a simple cotton candy machine could provide a cheap and robust solution for face mask fabrication. This review discuss the novel approaches of face mask reuse and reinforcement specifically by using membrane-based technology. Tuning the polymeric properties of face masks to enhance filterability and virus inactivity is crucial for future investigation.

There is no specific treatment for SARS-CoV-2, and all infection control strategies are based on breaking the transmission chain of virus. The high transmission rate of SARS-CoV-2 has raised many questions about the possible routes of infection transmission. Due to uncertainty of the main transmission routes, the infection control policies faced with more challenges. The possible main route of transmission is thought to be the close contact and respiratory droplets. Therefore, it is necessary to maintain physical distance and using the face mask. Another routes of transmission are through contaminated surfaces as well as airborne, fecal-oral transmission.

Peptide assembly is an increasingly important field of study due to the versatility, tunability and vast design space of amino acid based biomolecular assemblies. Peptides can be precisely engineered to possess various useful properties such as the ability to form supramolecular assemblies, desired response to pH, or thermal stability. These peptide supramolecular assemblies have diverse morphologies including vesicles, nanotubes, nanorods and ribbons. Of specific interest is the domain of engineering peptides that aggregate into spherical nanostructures due to their encapsulation properties: the ability to hold, transport and release chemical payloads in a controllable manner. This is invaluable to the fields of nanomedicine and targeted drug delivery. In this review, the state of the art in the domain of peptide-based vesicles and nanospheres is summarized. Specifically, an overview of the assembly of peptides into nanovesicles and nanospheres is provided. Both aromatic as well as aliphatic side chain amino acids are discussed. The domain of aromatic side chained amino acid residues is largely dominated by phenylalanine based peptides and variants thereof. Tyrosine also demonstrates similar aggregation properties. Both experimentally and computationally driven approaches are discussed. The domain of aliphatic amino acid residues based vesicles and droplets is broader, and details multiple amino acid residues such as alanine, valine, lysine, glycine, proline, and aspartic acid. Finally, a discussion on potential future directions is provided.