Liquid droplets and very fine particles can trap light — similar to how light can be caught between two mirrors. As a result, the intensity of the light inside them is amplified. This also happens in very fine water droplets and solid particles in our atmosphere, i.e. aerosols. Using modern X-ray microscopy, chemists at ETH Zurich and the Paul Scherrer Institute (PSI) have now investigated how light amplification affects photochemical processes that take place in the aerosols. They were able to demonstrate that light amplification causes these chemical processes to be two to three times faster on average than they would be without this effect.

Using the Swiss Light Source at the PSI, the researchers studied aerosols consisting of tiny particles of iron(III) citrate. Exposure to light reduces this compound to iron(II) citrate. X-ray microscopy makes it possible to distinguish areas within the aerosol particles composed of iron(III) citrate from those made up of iron(II) citrate down to a precision of 25 nanometres. In this way, the scientists were able to observe and map in high resolution the temporal sequence of this photochemical reaction in individual aerosol particles.

Decay upon exposure to light

“For us, iron(III) citrate was a representative compound that was easy to study with our method,” says Pablo Corral Arroyo, a postdoc in the group headed by ETH Professor Ruth Signorell and a lead author of the study. Iron(III) citrate stands in for a whole range of other chemical compounds that can occur in the aerosols of the atmosphere. Many organic and inorganic compounds are light-sensitive, and when exposed to light, they can break down into smaller molecules, which can be gaseous and therefore escape. “The aerosol particles lose mass in this way, changing their properties,” Signorell explains. Among other things, they scatter sunlight differently, which affects weather and climate phenomena. In addition, their characteristics as condensation nuclei in cloud formation change.

As such, the results also have an effect on climate research. “Current computer models of global atmospheric chemistry don’t yet take this light amplification effect into account,” ETH Professor Signorell says. The researchers suggest incorporating the effect into these models in future.

Non-uniform reaction times in the particles

Now precisely mapped and quantified, the light amplification in the particles comes about through resonance effects. The light intensity is greatest on the side of the particle opposite the one the light is shining on. “In this hotspot, photochemical reactions are up to ten times faster than they would be without the resonance effect,” says Corral Arroyo. Averaged over the entire particle, this gives an acceleration by the above-mentioned factor of two to three. Photochemical reactions in the atmosphere usually last several hours or even days.

Using the data from their experiment, the researchers were able to create a computer model to estimate the effect on a range of other photochemical reactions of typical aerosols in the atmosphere. It turned out that the effect does not pertain just to iron(III) citrate particles, but all aerosols — particles or droplets — made of compounds that can react with light. And these reactions are also two to three times faster on average.

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Materials provided by ETH Zurich. Original written by Fabio Bergamin. Note: Content may be edited for style and length.

The study, published in the Journal of Occupational Health Psychology recently, also found that working on a day when you feel ill drains mental energy which cannot be recovered the next day.

The study seeks to shed further light on the phenomenon of ‘presenteeism’ — defined by the researchers as continuing to work when experiencing ill-health. The practice has been labelled an ‘800-pound gorilla’ by researchers in occupational health psychology because of the tremendous costs it inflicts on employees and organisations alike. These costs include burnout, impaired workability, and productivity loss.

This study led by Dr Wladislaw Rivkin, Associate Professor in Organisational Behaviour, Trinity, deepens our understanding of the harmful impact of presenteeism on employee effectiveness by demonstrating that depletion of mental resources is a key mechanism responsible for these harmful effects.

The research involved 126 employees logging their daily productivity across 12 workdays, resulting in 995 daily work observations. It was conducted during the COVID-19 lockdown in 2020 when all participants were working from home.

Dr Rivkin commented:

“It is crucial to tackle daily presenteeism, especially for remote workers. Managers should openly discourage presenteeism by reassuring team members that if they feel unwell it is acceptable to reduce their daily work goals and instead tend to their health. In light of the energy-depleting nature of presenteeism if employees engage in presenteeism they should work on tasks that are inherently pleasant rather than tedious tasks that further drain their energy.

“So, while it may seem a good idea to work despite ill health to deliver on work goals our research shows that this has a knock-on effect for remote workers’ performance on the next day as presenteeism drains employees’ psychological energy, which cannot be fully recovered after work.”

The full paper was entitled “Should I stay or should I go? The role of daily presenteeism as an adaptive response to perform at work despite somatic complaints for employee effectiveness.”

Wlad Rivkin is an Associate Professor in Organisational Behaviour and Work Psychology whose research focuses on burnout, stress and other demands that people experience at work as well as what organisations can do to protect employee wellbeing and maintain their effectiveness. Other recent research projects include studies on the impact of commuting on employee wellbeing, the role of willpower in overcoming the negative effects of a bad night’s sleep and how smartphone use during non-work time impacts on sleep quality.

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Materials provided by Trinity College Dublin. Note: Content may be edited for style and length.

The pandemic’s toll on older adults, especially those in nursing homes and other long-term care facilities, has brought the issue of living independently at home into the national spotlight. So have policy proposals around changing the ability of Medicare and Medicaid to pay for virtual care and in-home help.

But the new findings from the National Poll on Healthy Aging suggest many people in their 50s, 60s and 70s need to do more to modify their homes or plan for services they may need if they want to avoid or delay needing to move. The poll also shows differences in aging-in-place readiness among the 28% of older adults who told the poll that they live alone.

The poll is based at U-M’s Institute for Healthcare Policy and Innovation and supported by AARP and Michigan Medicine, the University of Michigan’s academic medical center.

In all, 88% of people between the ages of 50 and 80 said it was very or somewhat important to them that they live in their homes as long as possible. But only 15% said they’ve given a lot of consideration to how their home may need to be modified as they age, while 47% have given it little or no thought.

Meanwhile, 48% of those who live alone said they don’t have someone in their lives who could help them with personal care such as bathing and dressing if needed, compared with 27% of those who live with others.

As for hiring help, 19% of older adults are very confident they could afford to pay someone to help with household chores, grocery shopping, personal care or managing their finances. On the other hand, nearly two-thirds of those who called their current physical or mental health status fair or poor said they were not confident or not very confident that they could afford to pay for such help.

“The pandemic’s impact on older adults, and policy proposals about home-based services at the federal and state level, mean this is a topic of immediate importance,” said Sheria Robinson-Lane, assistant professor at the U-M School of Nursing and IHPI member who worked with the poll team on the report. “Especially for those without as much social support, or with more health needs, it’s important to take a proactive approach and plan for the future now.”

Poll director Preeti Malani, U-M Medical School infectious disease professor also trained in geriatrics, said that older adults should explore with their health care providers and local social service agencies the kinds of support available to them, and talk with loved ones about their goals.

“Taking steps to understand what’s available in the community, through the national Eldercare Locator, the Area Agency on Aging that serves your region, nonprofit organizations and other sources could help older adults be more prepared,” she said.

“Family members can help encourage older adults to find out what’s available, to invest in home improvements, and to aid them in installing safety devices and technologies that can help keep them aging in place. Think of it as a positive investment toward current safety and future independence — that can help older adults get past the temptation to put it off for another day.”

More findings

The poll finds that 1 in 5 older adults had moved in the past five years. About half of those who moved said they had moved to a home that was easier to get around, while half also said their new home was smaller.

Wherever they live now, 34% said their home definitely has the necessary features that would let them age in place, and 49% said they had at least one ‘smart home’ device.

But the poll drilled down to ask about specific features and technologies. While 88% had a main-floor bathroom and 78% had a bedroom on the main floor, which could reduce the need to climb stairs and reduce fall risk, fewer older adults had other features.

For instance, 32% said they had grab bars in the bathroom, and less than 10% had safety-focused technologies such as alarms on their stoves or personal emergency response systems. Only 7% said they had a barrier-free shower, and 9% said that it was difficult to use the main rooms in their home because of clutter or large amounts of possessions there.

“AARP research consistently shows that the majority of older adults want to stay in their homes and communities for as long as possible,” said Indira Venkat, vice president of consumer insights at AARP. “Unfortunately, most houses weren’t built to support the needs of people across the many stages of life. The best way to continue living in the home you love is to plan ahead and make changes that will accomodate your needs today and in the future.”

In late 2021, AARP published a report on the preferences of adults over 18 about their future home and community circumstances, including the ability to age in place.

The poll report is based on findings from a nationally representative survey conducted by NORC at the University of Chicago for IHPI, and administered online and via phone in January and February 2022 among nearly 2,277 older adults ages 50-80. The sample was subsequently weighted to reflect the U.S. population.

Poll: https://www.healthyagingpoll.org/reports-more

Designed computationally and refined in the laboratory, the new protein therapies thwarted infection by interfering with the virus’ ability to enter cells. The top protein neutralized the virus with similar or greater potency than antibody treatments with Emergency Use Authorization status from the U.S. Food and Drug Administration (FDA). Notably, the top protein also neutralized all tested SARS-CoV-2 variants, something that many clinical antibodies have failed to do.

When researchers administered the treatment to mice as a nasal spray, they found that the best of these antiviral proteins reduced symptoms of infection — or even prevented infection outright.

The findings were published yesterday (April 12) in the journal Science Translational Medicine.

This work was led by Northwestern’s Michael Jewett; David Baker and David Veesler at the University of Washington School of Medicine; and Michael S. Diamond at WashU.

To begin, the team first used supercomputers to design proteins that could stick to vulnerable sites on the surface of the novel coronavirus, targeting the spike protein. This work was originally reported in 2020 in the journal Science.

In the new work, the team reengineered the proteins — called minibinders — to make them even more potent. Rather than targeting just one site of the virus’ infectious machinery, the minibinders simultaneously bind to three sites, making the drug less likely to detach.

“SARS-CoV-2’s spike protein has three binding domains, and common antibody therapies may only block one,” Jewett said. “Our minibinders sit on top of the spike protein like a tripod and block all three. The interaction between the spike protein and our antiviral is among the tightest interactions known in biology. When we put the spike protein and our antiviral therapeutic in a test tube together for a week, they stayed connected and never fell apart.”

Jewett is a professor of chemical and biological engineering at Northwestern’s McCormick School of Engineering and director of Northwestern’s Center for Synthetic Biology. Andrew C. Hunt, a graduate research fellow in Jewett’s laboratory, is the paper’s co-first author.

As the SARS-CoV-2 virus has mutated to create new variants, some treatments have become less effective in fighting the ever-evolving virus. Just last month, the FDA paused several monoclonal antibody treatments, for example, due to their failure against the BA.2 omicron subvariant.

Unlike these antibody treatments, which failed to neutralize omicron, the new minibinders maintained potency against the omicron variant of concern. By blocking the virus’ spike protein, the new antiviral prevents it from binding to the human angiotensin-converting enzyme 2 (ACE2) receptor, which is the entry point for infecting the body. Because the novel coronavirus and its mutant variants cannot infect the body without binding to the ACE2 receptor, the antiviral also should work against future variants.

“To enter the body, the spike protein and ACE2 receptor engage in a handshake,” Jewett said. “Our antiviral blocks this handshake and, as a bonus, has resistance to viral escape.”

In addition to losing effectiveness, current antibody therapies also come with several problems: They are difficult to develop, expensive and require a healthcare professional to administer. They also require complicated supply chains and extreme refrigeration, which is often unavailable in low-resource settings.

The new antiviral solves all these problems. As opposed to monoclonal antibodies, which are made by cloning and culturing living mammalian cells, the new antiviral treatment is produced large-scale in microorganisms like E. coli, making them more cost-effective to manufacture. Not only is the new therapy stable in high heat, which could further streamline manufacturing and decrease the cost of goods for clinical development, it also holds promise for being self-administered as a one-time nasal spray, bypassing the need for medical professionals.

The researchers imagine that it could be available at the pharmacy and used as a preventative measure to treat infections.

This study, “Multivalent designed proteins neutralize SARS-CoV-2 variants of concern and confer protection against infection in mice,” was supported by The Audacious Project at the Institute for Protein Design; Bill & Melinda Gates Foundation (OPP1156262, INV-004949); Burroughs Wellcome Fund; Camille Dreyfus Teacher-Scholar Program; David and Lucile Packard Foundation; Helen Hay Whitney Foundation; Open Philanthropy Project; Pew Biomedical Scholars Award; Schmidt Futures; Wu Tsai Translational Investigator Fund; Howard Hughes Medical Institute, including a fellowship from the Damon Runyon Cancer Research Foundation; Department of Defense (NDSEG-36373, W81XWH-21-1-0006, W81XWH-21-1-0007, W81XWH-20-1-0270-2019, AI145296, and AI143265); Defense Advanced Research Project Agency (HR0011835403 contract FA8750-17-C-0219); Defense Threat Reduction Agency (HDTRA1-15-10052, HDTRA1-20-10004); European Commission (MSCA CC-LEGO 792305); National Institutes of Health (1P01GM081619, R01GM097372, R01GM083867, T32GM007270, S10OD032290); National Institute of Allergy and Infectious Diseases (DP1AI158186, HHSN272201700059C, R37 AI1059371, R01 AI145486); National Institute of Diabetes and Digestive and Kidney Diseases (R01DK117914, R01DK130386, U01DK127553, F31DK130550); National Institute of General Medical Sciences (R01GM120553); NHLBI Progenitor Cell Biology Consortium (U01HL099997, UO1HL099993); National Center for Advancing Translational Sciences (UG3TR002158); United World Antiviral Research Network; Fast Grants; T90 Training Grant; and with federal funds from the Department of Health and Human Services (HHSN272201700059C).

L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology, and of Physics, learned the mechanics of combing years ago while brushing his young daughter’s hair.

“I recall that detangling spray seemed to work sometimes, but I still had to be careful to comb gently, by starting from the free ends,” said Mahadevan. “But I was soon fired from the job as I was not very patient.”

While Mahadevan lost his role as hairdresser, he was still a scientist and the topology, geometry and mechanics of detangling posed interesting mathematical questions that are relevant to a range of applications including textile manufacturing and chemical processes such as polymer processing.

In a new paper, published in the journal Soft Matter, Mahadevan and co-authors Thomas Plumb Reyes and Nicholas Charles, explore the mathematics of combing and explain why the brushing technique used by so many is the most effective method to detangle a bundle of fibers.

To simplify the problem, the researchers simulated two helically entwined filaments, rather than a whole head of hair.

“Using this minimal model, we study the detangling of the double helix via a single stiff tine that moves along it, leaving two untangled filaments in its wake,” said Plumb-Reyes, a graduate student at SEAS. “We measured the forces and deformations associated with combing and then simulated it numerically.”

“Short strokes that start at the free end and move towards the clamped end remove tangles by creating a flow of a mathematical quantity called the ‘link density’ that characterizes the amount that hair strands that are braided with each other, consistent with simulations of the process” said Nicholas Charles, a graduate student at SEAS.

The researchers also identified the optimal minimum length for each stroke — any smaller and it would take forever to comb out all the tangles and any longer and it would be too painful.

The mathematical principles of brushing developed by Plumb-Reyes, Charles and Mahadevan were recently used by Professor Daniela Rus and her team at MIT to design algorithms for brushing hair by a robot.

Next, the team aims to study the mechanics of brushing curlier hair and how it responds to humidity and temperature, which may lead to a mathematical understanding of a fact every person with curly hair knows: never brush dry hair.

This research was supported by funds from the US National Science Foundation, and the Henri Seydoux Fund.