Researchers have completed a new study of how well a variety of natural and synthetic fabrics filter particles of a similar size to the virus that causes COVID-19. Of the 32 cloth materials tested, three of the five most effective at blocking particles were 100% cotton and had a visible raised fiber or nap, such as found on flannels. Four of the five lowest performers were synthetic materials. The testing also showed that multiple fabric layers could improve cotton’s effectiveness even further. None of the materials came close to the efficiency of N95 masks.
Although the sample size was relatively small, the researchers noticed that tighter woven fabrics generally filtered better than knits and loosely woven fabrics. The 100% cotton fabrics with many raised fibers also appeared to filter better than cotton fabrics that lacked this feature. The raised fibers often form web-like structures similar to those in medical grade masks.
Three researchers from the National Institute of Standards and Technology (NIST) — Christopher Zangmeister, James Radney and Jamie Weaver — teamed up with Edward Vicenzi of the Smithsonian Institution’s Museum Conservation Institute to evaluate materials and determine both their ability to filter particles and their breathability. Their results appear in the journal ACS Nano.
The U.S. Centers for Disease Control and Prevention (CDC) recommends that people wear cloth face coverings in public settings where social distancing is difficult, primarily to prevent a person who doesn’t know they’re infected from spreading the virus.
The virus that causes COVID-19 is primarily spread through respiratory droplets that are expelled when a person sneezes, coughs or even talks. However, some research also suggests the virus can spread through much smaller aerosols — smaller than 1/100th the width of a human hair — that are also expelled, and which can linger in air much longer than droplets.
“It turns out that off-the-shelf materials provide some protection from aerosols if you use multiple layers of cloth and a face covering fits snugly,” said Zangmeister. “But none are as good as an N95 mask.”
The project measured a common way to determine how well a material captures particles, called filtration efficiency. Zangmeister and Radney, who are experts at measuring aerosols, set up a relatively simple experiment that relied on extremely sensitive equipment for sizing and counting aerosol particles.
The experiments used fabric samples, or swatches, rather than complete masks. “Basically, we take a swatch of material and flow a stream of particles of a known size at it,” said Zangmeister. “We count the number of particles in the air before and after it’s passed through the fabric. That tells us how effective the material is at capturing particles.”
Instead of real (and dangerous) samples of the SARS-CoV-2 virus, the team used table salt, or sodium chloride (NaCl), the recommended stand-in for virus particles by the CDC’s National Institute for Occupational Safety and Health (NIOSH), which establishes testing standards for N95 and other masks. The airflow rates used in the experiments were also from NIOSH test recommendations.
The researchers tested each material against particles ranging from 50 to 825 nanometers (nm) to chart its relative performance.
Meanwhile, Weaver, a materials chemist with a background in textiles, and Vicenzi, an expert in microscopy, studied each piece of fabric to determine its yarn count, weave and mass in the hopes of establishing a relationship between these characteristics and the fabric’s ability to filter particles.
The SARS-CoV-2 virus particles are about 110 nm in diameter. N95 masks are rigorously tested to ensure they block at least 95% of particles in this size range. A HEPA (high-efficiency particulate air) filter such as those you might find in an air purifier blocks 99.97% of particles that are about 300 nm in size, and an even higher percentage of smaller particles. Of the fabrics tested in the NIST study, the best-performing single fabric layer blocked 20% of particles in the size range of the virus.
While Zangmeister and Radney conducted the aerosol experiments at NIST’s Gaithersburg, Maryland, campus, Weaver and Vicenzi were able to conduct their imaging work at home where they have been working since mid-March.
“We intentionally used inexpensive digital microscopes and freeware to do our part of the research from home,” said Weaver. “One motivation for this was to develop imaging methods that would allow citizen scientists to better study fabrics for relatively little startup costs.”
In addition to the fabrics, the team looked at materials including a HEPA filter, N95 mask, a surgical mask and even coffee filters, which have been suggested for use in homemade face coverings, for comparison. The team also tested combinations of fabrics (a cotton and a synthetic layer), which did not show increased effectiveness.
By combining imaging and aerosol measurements, the team found that some fabrics that filter the most particles are also the hardest to breathe through, and some even fail to meet health and safety recommendations for breathability.
“The texture turned out to be one of the more useful parameters to look at because we found that most of the cotton fabrics with raised threads tended to filter best,” said Weaver. “Our findings suggest that a fabric’s ability to filter particles is based on a complex interplay between material type, fiber and weave structures, and yarn count.”
This research adds to the body of knowledge on fabrics and filtration that dates back to the 1918 flu pandemic that killed an estimated 20 to 50 million people worldwide and prompted the first research into fabric masks and their potential to protect against viruses. It also supports subsequent research suggesting that cloth filters would not be suitable for health-care settings.
But despite decades of research on the topic, the team found that a lack of standard test methods and the broad range of materials tested made it difficult to directly compare the results of previously published studies. They hope their work will provide a method for rapidly screening materials.
“We didn’t know the answer when we started this project,” said Zangmeister. “But the bottom line is that none of these fabrics are as good as an N95 mask. Still, cloth face coverings can help slow the spread of coronavirus. We hope this research will help manufacturers and DIYers determine the best fabrics for the job and serve as a basis for additional research.”
The team plans to begin another round of testing on a new set of materials in the near future. Weaver and Vicenzi have upgraded their imaging hardware and plan to employ more sophisticated textural analysis for the next round of fabrics.
Paper: C.D. Zangmeister, J.G. Radney, E.P. Vicenzi and J.L. Weaver. Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS CoV-2. ACS Nano. June 25, 2020. DOI: 10.1021/acsnano.0c05025
Brandless, the SoftBank-backed direct to consumer startup, relaunches to give the D2C experiment another try
Early this year, we wrote about Brandless when the SoftBank-backed direct to consumer (D2C) startup shut down its operation after burning through $292.5 million of investors’ money. Now, it seems the four-year old startup has risen from the ashes and wants to give it another try.
In a simple message on its website, the company said this: “Brandless is returning.” Brandless, formerly Dhosi, is a fresh approach to consumer commerce. The original concept Brandless’ mission is selling competitively priced products with plain packaging.
Brandless decided to close its operations in February due to the “fiercely competitive” market, rendering its business model to be unsustainable despite raising a substantial funding of $240 million under SoftBank’s Vision Fund, valuing the company at a little over $500 million.
Founded in 2016 by Ido Leffler and Tina Sharkey, the San Francisco-based Brandless aimed to eradicate the concept and costs of branding to maintain its initial uniform price of $3 across its array of non-perishable food and household goods. Below is what the company said back in February:
“After more than two amazing years of bringing customers across the country better for you and better for the planet products, Brandless is halting operations. While the Brandless team set a new bar for the types of products consumers deserve and at prices they expect, the fiercely competitive direct-to-consumer market has proven unsustainable for our current business model.
The good news is that although Brandless products will no longer be available on our website, they will still exist in homes and kitchens everywhere thanks to you, our supporters and fans.
To all of our customers: thank you for trusting Brandless to bring you innovative products created with quality materials and clean ingredients that help you live well and take better care of yourself, your family and your home. We’re hopeful the future holds a new version of Brandless and that we see you again.”
US economy gained 4.8 million jobs in June smashes expectations; unemployment rate falls to 11.1% as America roars back
America is back! With all the bad news about coronavirus, for the first time in the history of this great country, the nonfarm payrolls jumped by 4.8 million in June and the unemployment rate fell to 11.1% as the U.S. This is the biggest job growth on record, according to report from the Department of Labor.
Economists surveyed by Dow Jones had been expecting a 2.9 million increase and a jobless rate of 12.4%. The report was released a day earlier than usual due to the July Fourth U.S. holiday.
The jobs growth marked a big leap from the 2.7 million in May, which was revised up by 190,000. The June total is easily the largest single-month gain in U.S. history.
London-based Kennet raises $250M funding for its Fifth Fund to invest in ‘bootstrapped’ tech startup companies
Kennet Partners, a London-based European technology growth equity investor focused on bootstrapped and capital efficient technology startup companies, has raised $250 million (€223m) for its fifth fund, Kennet V* in partnership with Edmond de Rothschild. The Fund exceeded its target and secured new investors from across Europe and Asia.
Kennet V has already started to deploy the capital into new investments in Business to Business (B2B) Software-as-a-Service (SaaS) companies. The Fund has made investments in four companies in the UK, Europe and the US and has a strong pipeline for further investments.
Founded over 20 years ago, Kennet is a leading international growth equity firm that invests in high-growth companies in Europe and North America. Kennet specializes in investing in established, high growth technology companies which are founder-owned and ‘bootstrapped’ – built without significant external capital. Typically, the investment from Kennet is the first external funding that companies receive and is used to finance sales and marketing expansion, particularly internationally.
With offices in London and Silicon Valley, the firm supports entrepreneurial technology businesses with expansion capital to accelerate growth and build exceptional shareholder value. Kennet is one of the longest established technology growth investors in Europe with over 20 years of experience and a proven track record across multiple technology cycles. Kennet’s cumulative assets managed are approximately $1 billion.
Kennet V’s investments include companies such as Eloomi, a fast growth cloud-based Performance Management and Learning Management System and Codility, a remote-first platform for hiring software engineers. Investments from previous funds include Receipt Bank, the leading pre-accounting tool for accountants and bookkeepers, Nuxeo, a leading content services platform, Rimilia, a financial automation software platform as well as numerous exited companies.
Commenting on the funding, Michael Elias, Managing Director, Kennet Partners, said: “This fund raise is an important milestone for Kennet and demonstrates the success of our partnership with Edmond de Rothschild, which has provided us access to a range of new investors. Our experience investing in technology companies through multiple market cycles, has shown that it is a good time to invest during times of profound change. We therefore believe that the coming 2-3 years will be a very interesting time to deploy a fund.”
“The current pandemic has significantly accelerated the move to digitisation. COVID has required that people around the world change the way that they live and work. These changes are creating a structural shift that is forcing companies to turn to technological solutions. This has created strong longer-term opportunities for software businesses,” Hillel Zidel, Managing Director, Kennet Partners, said.
Johnny El-Hachem, CEO, Edmond de Rothschild Private Equity1, said: “Convinced that technology plays a critical role in the transformation of our economies and societies, our group has always been committed to promoting the emergence of innovative and value-creating companies. We partnered with Kennet, because we liked the dynamism of the team coupled with their strategy of financing businesses providing mission critical technology solutions. The COVID crisis has underscored the importance of many of these tools to business continuity.”
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