In a surprising finding, light can make water evaporate without heat

 Evaporation is happening all around us all the time, from the sweat cooling our bodies to the dew burning off in the morning sun. But science's understanding of this ubiquitous process may have been missing a piece all this time.

In recent years, some researchers have been puzzled upon finding that water in their experiments, which was held in a sponge-like material known as a hydrogel, was evaporating at a higher rate than could be explained by the amount of heat, or thermal energy, that the water was receiving. And the excess has been significant -- a doubling, or even a tripling or more, of the theoretical maximum rate.

After carrying out a series of new experiments and simulations, and reexamining some of the results from various groups that claimed to have exceeded the thermal limit, a team of researchers at MIT has reached a startling conclusion: Under certain conditions, at the interface where water meets air, light can directly bring about evaporation without the need for heat, and it actually does so even more efficiently than heat. In these experiments, the water was held in a hydrogel material, but the researchers suggest that the phenomenon may occur under other conditions as well.

The findings are published this week in a paper in PNAS, by MIT postdoc Yaodong Tu, professor of mechanical engineering Gang Chen, and four others.

The phenomenon might play a role in the formation and evolution of fog and clouds, and thus would be important to incorporate into climate models to improve their accuracy, the researchers say. And it might play an important part in many industrial processes such as solar-powered desalination of water, perhaps enabling alternatives to the step of converting sunlight to heat first.

The new findings come as a surprise because water itself does not absorb light to any significant degree. That's why you can see clearly through many feet of clean water to the surface below. So, when the team initially began exploring the process of solar evaporation for desalination, they first put particles of a black, light-absorbing material in a container of water to help convert the sunlight to heat.

Then, the team came across the work of another group that had achieved an evaporation rate double the thermal limit -- which is the highest possible amount of evaporation that can take place for a given input of heat, based on basic physical principles such as the conservation of energy. It was in these experiments that the water was bound up in a hydrogel. Although they were initially skeptical, Chen and Tu starting their own experiments with hydrogels, including a piece of the material from the other group. "We tested it under our solar simulator, and it worked," confirming the unusually high evaporation rate, Chen says. "So, we believed them now." Chen and Tu then began making and testing their own hydrogels.

They began to suspect that the excess evaporation was being caused by the light itself -- that photons of light were actually knocking bundles of water molecules loose from the water's surface. This effect would only take place right at the boundary layer between water and air, at the surface of the hydrogel material -- and perhaps also on the sea surface or the surfaces of droplets in clouds or fog.

In the lab, they monitored the surface of a hydrogel, a JELL-O-like matrix consisting mostly of water bound by a sponge-like lattice of thin membranes. They measured its responses to simulated sunlight with precisely controlled wavelengths.

The researchers subjected the water surface to different colors of light in sequence and measured the evaporation rate. They did this by placing a container of water-laden hydrogel on a scale and directly measuring the amount of mass lost to evaporation, as well as monitoring the temperature above the hydrogel surface. The lights were shielded to prevent them from introducing extra heat. The researchers found that the effect varied with color and peaked at a particular wavelength of green light. Such a color dependence has no relation to heat, and so supports the idea that it is the light itself that is causing at least some of the evaporation.

The researchers tried to duplicate the observed evaporation rate with the same setup but using electricity to heat the material, and no light. Even though the thermal input was the same as in the other test, the amount of water that evaporated never exceeded the thermal limit. However, it did so when the simulated sunlight was on, confirming that light was the cause of the extra evaporation.

Though water itself does not absorb much light, and neither does the hydrogel material itself, when the two combine they become strong absorbers, Chen says. That allows the material to harness the energy of the solar photons efficiently and exceed the thermal limit, without the need for any dark dyes for absorption.

Having discovered this effect, which they have dubbed the photomolecular effect, the researchers are now working on how to apply it to real-world needs. They have a grant from the Abdul Latif Jameel Water and Food Systems Lab to study the use of this phenomenon to improve the efficiency of solar-powered desalination systems, and a Bose Grant to explore the phenomenon's effects on climate change modeling

.Tu explains that in standard desalination processes, "it normally has two steps: First we evaporate the water into vapor, and then we need to condense the vapor to liquify it into fresh water." With this discovery, he says, potentially "we can achieve high efficiency on the evaporation side." The process also could turn out to have applications in processes that require drying a material.

Chen says that in principle, he thinks it may be possible to increase the limit of water produced by solar desalination, which is currently 1.5 kilograms per square meter, by as much as three- or fourfold using this light-based approach. "This could potentially really lead to cheap desalination," he says.

Tu adds that this phenomenon could potentially also be leveraged in evaporative cooling processes, using the phase change to provide a highly efficient solar cooling system.

Meanwhile, the researchers are also working closely with other groups who are attempting to replicate the findings, hoping to overcome skepticism that has faced the unexpected findings and the hypothesis being advanced to explain them.

The research team also included Jiawei Zhou, Shaoting Lin, Mohammed Alshrah, and Xuanhe Zhao, all in MIT's Department of Mechanical Engineering.

Protein interaction causing rare but deadly vaccine-related clotting found

 A mechanism that led some patients to experience cases of deadly clotting following some types of Covid-19 vaccination has been identified in new research.

In a paper published in Blood, scientists from the University of Birmingham funded by the National Institute for Health and Care Research and the British Heart Foundation have been able to identify how deadly blood clots, in the disease known as Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT), occur.

Previous studies have shown that patients with VITT produce antibodies that stick to a protein called Platelet factor 4 (PF4) to create a large cluster of molecules called an immune complex. Following the development of a complex, platelets and cells of the immune system causing clotting and inflammation are activated, but the precise nature of what PF4 does in this event was unknown.

In this latest study, the team used blood taken from healthy donors, as well as serum and plasma from patients with VITT, and have been able to learn for the first time how PF4 was directly involved in the activation of platelets and resulted in thrombotic events. By sticking to a receptor called c-Mpl on the surface of platelets, PF4 triggered the production of the small cells known to cause clotting.

Dr Pip Nicolson, Associate Clinical Professor in Cardiovascular Medicine at the University of Birmingham and senior author of the study said: "The major advances seen in vaccine development during the global Covid-19 pandemic were thrown into sharp relief following the tragic, rare cases of vaccine-induced immune thrombosis. While there were alternative vaccines available to continue to provide protection against the coronavirus in some countries around the world, understanding the mechanisms behind these cases is critical to ensuring that the technology for delivering vaccines can be used with confidence in the future."

Dr Richard Buka, Research Fellow in the Institute of Cardiovascular Sciences and co-lead author "As well as identifying a new way in which platelets are being activated in a potentially deadly manner in VITT, our research has also been able to find how this mechanism may lead to new drugs to protect against blood clots in VITT and blood clots in general."

Variations on a drug used to treat bone marrow cancers could be developed to protect VITT patients from deadly clotting, the research also found.

The team used ruxolitinib, a drug used to treat some types of blood cancer, to block the receptor being triggered by PF4 following the vaccine-induced event. Although they note that the current form of the drug is unsuitable for use in VITT patients, the team nevertheless identified that blocking the pathway through ruxolitinib slowed down platelet aggregation and demonstrates a potential future way to protect patients from blood clots.

Dr Samantha Montague, Research Fellow in the Institute of Cardiovascular Sciences at the University of Birmingham and co-lead author of the paper said: "It is gratifying that we have been able to identify a new, important biological mechanism through trying to thoroughly understand a new disease. This work helps us to understand more fundamental things about how blood clots form and may also be relevant in other related diseases that are more common.

"Our ongoing research funded by the British Heart Foundation is looking at how we can identify patients who may develop VITT, with a view that future vaccine programmes around the world can be delivered while understanding and 

Contraceptive pill users less likely to report depression

 A new study has shown that women who are taking the oral contraceptive pill are less likely to report depression.

The research, which analysed data from 6,239 women in the United States aged 18-55 years old, found that the prevalence of major depression amongst users of the oral contraceptive pill (OCP) was significantly lower, at 4.6%, compared to former OCP users (11.4%).

The study was led by researchers at Anglia Ruskin University (ARU), alongside experts from the Dana-Farber Cancer Institute in Boston and University of California, Davis.

The researchers suggest two possible explanations for their findings, which are contrary to a commonly held belief that OCP can cause depression.

One is that taking the pill can remove concerns about unwanted pregnancy, therefore helping to improve the mental health of OCP users. It is also possible the results could be influenced by "survivor bias," where women who experience signs of depression while using OCP stop taking it, moving them into the category of former users.

The cross-sectional study, which used data collected by the Center for Disease Control and Prevention in the United States, controlled for demographic characteristics, chronic conditions, and the use of antidepressants.

In both users and former users, widowed, divorced or separated women, obese women or those with a history of cancer were more likely to report depression. In addition, in former users, depression was more commonly reported in women who were Black or Hispanic, were smokers, had lower levels of education, or were experiencing poverty.

Lead author Dr Julia Gawronska, a Postdoctoral Research Fellow at Anglia Ruskin University (ARU), said: "Contraception is a crucial component of preventive health care. Most women tolerate taking the oral contraceptive pill without experiencing depressive symptoms but there is a subset of women that may experience adverse mood side effects and even develop depression, and the reasons are not entirely clear.

"Unlike some previous studies, we found that women currently taking the oral contraceptive pill were much less likely to report clinically relevant depression compared to women who previously took the pill.

"Taking the pill could provide positive mental health benefits for some women, simply by removing their concerns about becoming pregnant. The 'survivor effect' could also play a part, with women who experience symptoms of depression more likely to discontinue taking it, placing them into the group of former users.

"However, stopping taking the pill without a suitable alternative increases the risk of unintended pregnancy. It is important that women are fully supported, provided with full information

Breakthrough discovery sheds light on heart and muscle health

 The human heart, often described as the body's engine, is a remarkable organ that tirelessly beats to keep us alive. At the core of this vital organ, intricate processes occur when it contracts, where thick and thin protein-filaments interact within the sarcomere, the fundamental building block of both skeletal and heart muscle cells. Any alterations in thick filament proteins can have severe consequences for our health, leading to conditions such as hypertrophic cardiomyopathy and various other heart and muscle diseases.

In a remarkable scientific achievement, an international team, led by Stefan Raunser, Director at the Max Planck Institute of Molecular Physiology in Dortmund, in collaboration with Mathias Gautel at King's College London, has achieved a groundbreaking milestone. They have successfully obtained the world's first high-resolution 3D image of the thick filament in its natural cellular environment, utilizing a cutting-edge technique known as electron cryo-tomography. This unprecedented accomplishment offers a glimpse into the molecular organization and arrangement of the components within the thick filament. This newfound insight is nothing short of a crucial framework for comprehending how muscles operate in both health and disease. By understanding the intricate mechanics at play, scientists are now better equipped to develop innovative pharmacological approaches and treatments that can target heart and muscle disorders, potentially revolutionizing medical intervention in these areas.

Atrial fibrillation, heart failure and stroke -- hypertrophic cardiomyopathy can lead to many serious health conditions and is a major cause of sudden cardiac death in people younger than 35. "The heart muscle is a central engine of the human body. Of course, it is easier to fix a broken engine, if you know how it is built and how it functions," says Stefan Raunser. "At the beginning of our muscle research we have successfully visualized the structure of the essential muscle building blocks and how they interact using electron cryo-microscopy. However, these were static images of proteins taken out of the living cell. They only tell us little about how the highly variable, dynamic interplay of muscle components moves the muscle in its native environment," says Raunser.

Through thick and thin

Skeletal and heart muscles contract upon the interaction of two types of parallel protein filaments in the sarcomere: thin and thick. The sarcomere is subdivided in several regions, called zones and bands, in which these filaments are arranged in different ways. The thin filament consists of F-actin, troponin, tropomyosin, and nebulin. The thick filament is formed of myosin, titin and myosin binding protein C (MyBP-C). The latter can form links between the filaments, whereas myosin, the so-called motor protein interacts with the thin filament to generate force and muscle contraction. Alterations in the thick filament proteins are associated with muscle diseases. A detailed picture of the thick filament would be of immense importance for developing therapeutical strategies to cure these diseases, but has been missing so far.

Milestones in muscle research

"If you want to fully understand how the muscle works on the molecular level, you need to picture its components in their natural environment -- one of the biggest challenges in biological research nowadays that cannot be tackled by traditional experimental approaches," says Raunser. To overcome this obstacle his team developed an electron cryo-tomography workflow specifically tailored to the investigation of muscle samples: The scientists flash-freeze mammalian heart muscle samples, produced by the Gautel group in London, at a very low temperature (- 175 °C). This preserves their hydration and fine structure and thus their native state. A focused ion beam (FIB milling) is then applied to thin out the samples to an ideal thickness of around 100 nanometers for the transmission electron microscope, which acquires multiple images as the sample is tilted along an axis. Finally, computational methods reconstruct a three-dimensional picture at high resolution. In recent years, Raunser's group successfully applied the customized workflow, resulting in two recent groundbreaking publications: They produced the first high-resolution images of the sarcomere and of a so far nebulous muscle protein called nebulin. Both studies provide unprecedented insights into the 3D organization of muscle proteins in the sarcomere, e. g. how myosin binds to actin to control muscle contraction and how nebulin binds to actin to stabilize it and to determine its length.

Completing the painting

In their current study the scientists produced the first high-resolution image of the cardiac thick filament spanning across several regions in the sarcomere. "With 500 nm length this makes for the longest and biggest structure ever resolved by cryo-ET," says Davide Tamborrini from the MPI Dortmund, first-author of the study. Even more impressive are the newly gained insights into the thick filament's molecular organization and thus into its function. The arrangement of the myosin molecules depends on their position in the filament. The scientists suspect, that this allows the thick filament to sense and process numerous muscle-regulating signals and thus to regulate the strength of muscle contraction depending on the sarcomere region. They also revealed how titin chains run along the filament. Titin chains intertwine with myosin, acting as a scaffold for its assembly and probably orchestrating a length-depending activation of the sarcomere.

"Our aim is to paint a complete picture of the sarcomere one day. The image of the thick filament in this study is 'only' a snapshot in the relaxed state of the muscle. To fully understand how the sarcomere functions and how it is regulated, we want to analyze it in different states e. g. during contraction," says Raunser. Comparison with samples from patients with muscle disease will ultimately contribute to a better understanding of diseases like hypertrophic cardiomyopathy and to the development of innovative therapies.

First mice engineered to survive COVID-19 like young, healthy humans

 Researchers have genetically engineered the first mice that get a human-like form of COVID-19, according to a study published online November 1in Nature.

Led by researchers from NYU Grossman School of Medicine, the new work created lab mice with human genetic material for ACE2 -- a protein snagged by the pandemic virus so it can attach to human cells as part of the infection. The mice with this genetic change developed symptoms similar to young humans infected with the virus causing COVID-19, instead of dying upon infection as had occurred with prior mouse models.

"That these mice survive creates the first animal model that mimics the form of COVID-19 seen in most people -- down to the immune system cells activated and comparable symptoms," said senior study author Jef Boeke, the Sol and Judith Bergstein Director of the Institute for Systems Genetics at NYU Langone Health. "This has been a major missing piece in efforts to develop new drugs against this virus."

"Given that mice have been the lead genetic model for decades," added Boeke, "there are thousands of existing mouse lines that can now be crossbred with our humanized ACE2 mice to study how the body reacts differently to the virus in patients with diabetes or obesity, or as people age."

Problem of Large DNA

The new study revolves around a new method to edit DNA, the 3 billion "letters" of the genetic code that serve as instructions for building our cells and bodies.

While famous techniques like CRISPR enable the editing of DNA editing just one or a few letters at a time, some challenges require changes throughout genes that can be up to 2 million letters long. In such cases, it may be more efficient to build DNA from scratch, with far-flung changes made in large swaths of code pre-assembled and then swapped into a cell in place of its natural counterpart. Because human genes are so complex, Boeke's lab first developed its "genome writing" approach in yeast, one-celled fungi that share many features with human cells but that are simpler and easier to study.

More recently, Boeke's team adapted their yeast techniques to the mammalian genetic code, which is made up of not just of genes that encode proteins, but also of many switches that turn on different genes at different levels in different cell types. By studying this poorly understood "dark matter" that regulates genes, the research team was able to design living mice with cells that had more human-like levels of ACE gene activity for the first time. The study authors used yeast cells to assemble DNA sequences of up to 200,000 letters in a single step, and then delivered these "naked" DNAs into mouse embryonic stem cells using their new delivery method, mSwAP-In.

Overcoming the size limits of past methods, mSwAP-In delivered a humanized mouse model of COVID-19 pathology by "overwriting" 72 kilobases (kb) of mouse Ace2 code with 180 kb of the human ACE2 gene and its regulatory DNA.

To accomplish this cross-species swap, the study method cut into a key spot in the DNA code around the natural gene, swapped in a synthetic counterpart in steps, and with each addition, added a quality control mechanism so that only cells with the synthetic gene survived. The research team then worked with Sang Yong Kim at NYU's Rodent Genome Engineering Lab using a stem cell technique called "tetraploid complementation" to create a living mouse whose cells included the overwritten genes.

In addition, the researchers had previously designed a synthetic version of the gene Trp53, the mouse version of the human gene TP53, and swapped it into mouse cells. The protein encoded by this gene coordinates the cell's response to damaged DNA, and can even instruct cells containing it to die to prevent the build-up of cancerous cells. When this "guardian of the genome" itself becomes faulty, it is a major contributor to human cancers.

Whereas the ACE2 experiments had swapped in an unchanged version of a human gene, the synthetic, swapped-in Trp53 gene had been designed to no longer include a combination of molecular code letters -- cytosine (C) next to guanine (G) -- known to be vulnerable to random, cancer-causing changes. The researchers overwrote key CG "hotspots" with code containing a different DNA letter in adenine (A).

"The AG switch left the gene's function intact, but lessened its vulnerability to mutation, with the swap predicted to lead to a 10-to-50 fold lower mutation rate," said first author Weimin Zhang, PhD, a post-doctoral scholar in Boeke's lab. "Our goal is to demonstrate in a living test animal that this swap leads to fewer mutations and fewer resulting tumors, and those experiments are being planned."

The work was funded by National Institutes of Health CEGS grant 1RM1HG009491 and Perlmutter Cancer Center Support Grant P30CA016087. Boeke is a founder of CDI Labs, Inc., a founder of Neochromosome, Inc.; a founder of ReOpen Diagnostics, LLC, and serves or has served on the scientific advisory boards of Logomix Inc., Modern Meadow, Inc., Rome Therapeutics, Inc., Sample6, Inc., Sangamo, Inc., Tessera Therapeutics, Inc. and the Wyss Institute. Boeke also receives consulting fees and royalties from OpenTrons, and holds equity in the company. These relationships are managed in accordance with the policies of NYU.