(Press-News.org) WASHINGTON, March 9, 2021 -- One of the primary ways the COVID-19 virus is transmitted is via airborne diffusion of saliva microdroplets, so it is paramount to find methods to kill the virus in airborne microdroplets.
The extreme confusion that abounded at the beginning of the pandemic about safe social distances, mask wearing, and social behavior inspired Marche Polytechnic University researchers, who happen to be intrigued by saliva droplet diffusion, to search for answers and ways to help.
In Physics of Fluids, from AIP Publishing, Valerio D'Alessandro and colleagues describe using a supercomputer to do numerical modeling of cough droplets irradiated by UV-C light. They also report exploring the social distances required to prevent virus transmission.
The researchers zeroed in on the evolution of a saliva droplet cloud, accounting for the inertia, buoyancy, and weight of each droplet and its aerodynamic interaction with the environment.
"We are interested in the possibility of deactivating virus particles via UV-C light," D'Alessandro said. "So, we explored the interaction of saliva droplets with an external source of UV-C radiation, a lamp."
UV-C is a well-established germicidal technique, because it interferes with virus RNA replication.
"UV-A and UV-B also kill germs and are present within the sun's rays, but with these, it takes 15 to 20 minutes to kill a virus," said D'Alessandro. "The sun's rays disinfect surfaces during the summer, which is one reason why transmission is reduced then, but it can't be used for real-time disinfection. That's why we decided to explore the effect of UV-C radiation on viruses."
The researchers' work addresses key points still not completely understood. First, they determined that 1 meter (3.2 feet) of social distancing is not completely safe to avoid virus transmission. This is particularly important, because this is the social distancing rule in Italy and its schools.
"While 1 meter of distance can suffice in a one-on-one situation, you can still get hit with cough droplets from the chest down," D'Alessandro said. "It's necessary to avoid touching your eyes, nose, or mouth with your hands. We found 2 meters (6.5 feet) to be a much safer distance."
D'Alessandro and colleagues stress that the largest droplets travel about 1 meter. Over this distance they discovered only smaller droplets, which transport a reduced amount of the virus.
"It's important to emphasize that these results were obtained without any background wind, and if this is present, the distance is almost doubled," he said. "So we need to wear face masks, especially when in close proximity."
They also found "it is possible to reduce the contamination risk by about 50% when irradiating saliva droplet clouds with UV-C radiation -- without providing a dangerous dose to people," said D'Alessandro. "This is critically important, because disinfection systems based on UV-C are not always acceptable. UV-C kills the virus, but higher doses for humans can be dangerous."
High exposures to UV-C are known to cause skin and eye tumors.
"Our work helps correct the understanding of safe social distancing," said D'Alessandro. "Also, our computations can help to design new real-time disinfection devices based on UV-C that can reduce the risk of COVID-19 transmission and other viruses within particular situations, such as for supermarket cashiers or people in similar situations."
INFORMATION:
The article "Eulerian-Lagrangian modeling of cough droplets irradiated by ultraviolet-C light in relation to SARS-CoV-2 transmission" is authored by V. D'Alessandro, M. Falone, L. Giammichele, and R. Ricci. It will appear in Physics of Fluids on March 9, 2021 (DOI: 10.1063/5.0039224). After that date, it can be accessed at https://aip.scitation.org/doi/10.1063/5.0039224.
ABOUT THE JOURNAL
Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex fluids. See https://aip.scitation.org/journal/phf.
(COLUMBUS, Ohio) - To minimize transmission of COVID-19, in spring 2020, most U.S. states passed policies promoting social distancing through stay-at-home orders prohibiting non-essential travel. Vehicle-miles traveled in the U.S. decreased by 41% in April 2020 compared to 2019. A new study led by researchers at the Center for Injury Research and Policy at Nationwide Children's Hospital estimated associations between COVID-19-related social-distancing policies, traffic volume, and motor vehicle crash-related outcomes in Ohio.
The study, published today in JAMA, found the number of individuals involved in a motor vehicle crash, sustaining injury, sustaining ...
WASHINGTON, March 9, 2021 -- Researchers at Toshiba Corporation in Japan have studied the operation of a small device fabricated in the write gap of a hard disk drive's write head to extend its recording density. The device, developed by HWY Technologies, is based on a design concept known as microwave-assisted magnetic recording, or MAMR.
This technology, reported in the Journal of Applied Physics, by AIP Publishing, uses a microwave field generator known as a spin-torque oscillator. The spin-torque oscillator emits a microwave field causing the magnetic particles of the recording medium to wobble the way a spinning top does. This makes them much easier to flip over when the write head applies a recording magnetic ...
People over 65 shouldn't take three or more medicines that act on their brain and nervous system, experts strongly warn, because the drugs can interact and raise the risk of everything from falls to overdoses to memory issues.
But a new study finds that 1 in 7 people with dementia who live outside nursing homes are taking at least three of these drugs.
Even if they received the drugs to calm some of dementia's more troubling behavioral issues, the researchers say, taking them in combination could accelerate their loss of memory and thinking ability, and raise their chance of ...
PITTSBURGH, 9 March 2021 - If approved, the monthly dapivirine vaginal ring would be the first biomedical HIV prevention method designed specifically for cisgender women, as well as the first long-acting method. Looking to the future, researchers from the National Institutes of Health-funded END ...
Researchers from the group of Hans Clevers identified and characterized rare cell types in the upper gastrointestinal tract. Using single cell RNA sequencing, they studied the cellular composition of the esophagus, stomach and upper part of the small intestine. They provide detailed gene expression analyses for all epithelial cells in these organs. Furthermore, they identified a rare cell type that is most likely responsible for the secretion of high volumes of water in humans. This cell type provides a link to gastrointestinal defects in patients with cystic fibrosis. The paper was published in Cell Reports on the 9th ...
What The Study Did: Researchers compared traffic volume and motor vehicle crash injuries before, during and after COVID-19-related state-of-emergency and stay-at-home orders in Ohio from January to July last year with the same period in 2019.
Authors: Motao Zhu, Ph.D., of the Abigail Wexner Research Institute at Nationwide Children's Hospital in Columbus, Ohio, is the corresponding author.
To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/
(doi:10.1001/jama.2020.25770)
Editor's Note: The article includes conflicts of interest and funding/support disclosures. Please see the article ...
Bioengineers at the University of California San Diego and San Diego State University have discovered a key feature that allows cancer cells to break from typical cell behavior and migrate away from the stiffer tissue in a tumor, shedding light on the process of metastasis and offering possible new targets for cancer therapies.
It has been well documented that cells typically migrate away from softer tissue to stiffer regions within the extracellular matrix-- a process called durotaxis. Metastatic cancer cells are the rare exception to this rule, moving away from the stiffer tumor tissue to softer tissue, and spreading ...
WASHINGTON, March 9, 2021 -- Spinal cord injuries can be life-changing and alter many important neurological functions. Unfortunately, clinicians have relatively few tools to help patients regain lost functions.
In APL Bioengineering, by AIP Publishing, researchers from UCLA have developed materials that can interface with an injured spinal cord and provide a scaffolding to facilitate healing. To do this, scaffolding materials need to mimic the natural spinal cord tissue, so they can be readily populated by native cells in the spinal cord, essentially filling in gaps left by injury.
"In this study, we demonstrate that incorporating a regular network of pores throughout these materials, where pores are sized similarly to normal cells, increases infiltration of cells from spinal cord tissue ...
Astronauts face many challenges to their health, due to the exceptional conditions of spaceflight. Among these are a variety of infectious microbes that can attack their suppressed immune systems.
Now, in the first study of its kind, Cheryl Nickerson, lead author Jennifer Barrila and their colleagues describe the infection of human cells by the intestinal pathogen Salmonella Typhimurium during spaceflight. They show how the microgravity environment of spaceflight changes the molecular profile of human intestinal cells and how these expression patterns are further changed in response to infection. In another first, the researchers were also able to detect ...
PORTOLA VALLEY, CA, March 9, 2021 -- Bay Area Lyme Foundation, a leading sponsor of Lyme disease research in the U.S., today announced the publication of new data finding that five herbal medicines had potent activity compared to commonly-used antibiotics in test tubes against Babesia duncani, a malaria-like parasite found on the West Coast of the U.S. that causes the disease babesiosis. Published in the journal Frontiers in Cellular and Infection Microbiology, the laboratory study was funded in part by the Bay Area Lyme Foundation. Collaborating researchers were from Johns Hopkins Bloomberg School of Public Health, California Center for Functional Medicine, and FOCUS Health Group, Naturopathic.
"This research is particularly important ...
