quantified the entropy produced by a system evolving in quantum superposition of processes with opposite time arrows. We found this most often results in projecting the system onto a well-defined time's direction, corresponding to the most likely process of the two. And yet, when small amounts of entropy are involved (for instance, when there is so little toothpaste spilled that one could see it being reabsorbed into the tube), then one can physically observe the consequences of the system having evolved along the forward and backward temporal directions at the same time.

Aside from the fundamental feature that time itself might not be well-defined, the work also has practical implications in quantum thermodynamics. Placing a quantum system in a superposition of alternative time's arrows could offer advantages in the performance of thermal machines and refrigerators.

Although time is often treated as a continuously increasing parameter, this study shows the laws governing its flow in quantum mechanical contexts are much more complex. This may suggest that we need to rethink the way we represent this quantity in all those contexts where quantum laws play a crucial role.

Quantum superposition of thermodynamic evolutions with opposing time's arrows, Communications Physics (2021). DOI: 10.1038/s42005-021-00759-1

https://phys.org/news/2021-11-quantum-realm.html?utm_source=nwlette...

Part 2

**

COVID-19 : Measuring viral RNA to predict which patients will die

The amount of a SARS-CoV-2 genetic material—viral RNA—in the blood is a reliable indicator in detecting which patients will die of the disease, a team  of researchers has found.

In this study, scientists were able to determine which biomarkers are predictors of mortality in the 60 days following the onset of symptoms. They have successfully developed and validated a statistical model based on one blood biomarker, viral RNA.  Several biomarkers have been identified in other studies, but juggling the profusion of parameters is not possible in a clinical setting and hinders doctors' ability to make quick medical decisions.

Using blood samples collected from 279 patients during their hospitalization for COVID-19, ranging in degrees of severity from moderate to critical, the  team measured amounts of inflammatory proteins, looking for any that stood out.

At the same time, they measured the amounts of viral RNA and  the levels of antibodies targeting the virus. Samples were collected 11 days after the onset of symptoms and patients were monitored for a minimum of 60 days after that.

The goal: to test the hypothesis that immunological indicators were associated with increased mortality. Among all of the biomarkers they evaluated, they showed that the amount of viral RNA in the blood was directly associated with mortality and provided the best predictive response, once their model was adjusted for the age and sex of the patient. They even found that including additional biomarkers did not improve predictive quality.

It made no difference which hospital the patients were treated at, nor which period of the pandemic they fell into: in all cases, the predictive model worked. Now the researchers  want to put it to practical use.

Elsa Brunet-Ratnasingham et al, Integrated immunovirological profiling validates plasma SARS-CoV-2 RNA as an early predictor of COVID-19 mortality, Science Advances (2021). DOI: 10.1126/sciadv.abj5629. www.science.org/doi/10.1126/sciadv.abj5629

https://medicalxpress.com/news/2021-11-covid-viral-rna-patients-die...

Using molecules and atoms to conduct the double-slit experiment

A team of researchers  has developed a way to conduct the famous double-slit experiment at the molecular level. In their paper published in the journal Science, the group describes their technique and suggest that it could be used to assist with other molecular experiments.

In 1801, Thomas Young conducted what has come to be known as the double-slit experiment. At the time, he used it as a means to prove that light behaves as a wave. Since that time, light has been found to also behave as a particle of course, and the double-slit experiment has since been conducted in various ways under various conditions. Others have shown that electrons and atoms and molecules exhibit the same type of behavior. In this new effort, the researchers have taken the experiment to a new level by using nothing but molecules, single atoms and lasers. In the original double-slit experiment, the light passed through both slits in a superposition of trajectories. In this new method, there is only one slit, but it is in a superposition of positions.

Part 1

The experiment by the team involved creating a beam of deuterium and helium molecules in a chamber cooled to –272°C. They then used pairs of polarized laser bursts to push deuterium molecules into a certain vibrational and rotational state with different orientations—at right angles to one another. These served as the slits for the experiment. The team also forced other deuterium molecules into a state where they were suppositions of both of the orientations of the slits. As helium atoms scattered off the superposed molecules (along different paths that interfered with one another), the deuterium could in a sense "feel" them both at the same time. And as the helium atoms collided with the molecules, the deuterium atoms were released back to their original state at which point, they were ionized and studied by the research team.

The researchers suggest that in addition to conducting the double-slit experiment in a new way, their work also lays the groundwork for studying quantum behavior in a new way—by preparing new types of matter. They conclude by suggesting that their techniques could also be adapted for use in studying decoherence.

Haowen Zhou et al, Quantum mechanical double slit for molecular scattering, Science (2021). DOI: 10.1126/science.abl4143

https://phys.org/news/2021-11-molecules-atoms-double-slit.html?utm_...

Part 2

**

Warm weather or bright lights can influence tree greening

How both global warming and bright city lights can impact phenology in trees (when they begin to grow leaves in the spring?

 In her paper published in the journal Science, Meng, the Science & SciLifeLab Prize  for young scientist's award winner, outlines her study of satellite data showing green areas in cities along with artificial light sources and also trees growing in the Alps.

Prior research has shown that higher temperatures in cities can impact vegetation growth. In this new effort, Meng wondered what city warming, combined with global warming might be doing to the times that trees "green up" in the spring each year. To find out, she obtained and analyzed satellite data that showed when trees begin producing leaves in the spring each year for 85 U.S. cities over the years 2001 to 2014.

She found that tree green-up happens on average 6 days earlier in urban areas compared to rural areas. She also found that trees in the city are responding to climate change faster than trees in rural areas.

Meng also wondered about the impact of bright lights on trees and whether they might make trees start growing their leaves earlier in the spring each year. She studied trees growing in the Alps in Europe—noting that it is a place with a rather uniform temperature distribution but also has changing lengths of daylight across latitudes. She found evidence of a reduction in an early green-up likely due to global warming. She then studied data from NASA's Black Marble satellite, which measures artificial light in cities and also phenology data from the USA National Phenology Network. This allowed her to compare conditions in cities both with and without artificial light in the U.S., and she found that artificial light pushed spring green-up by nine days in the most extreme cases.

Meng concludes by suggesting that artificial light, by supplementing day length, leads to additions of earlier spring greening in cities, adding to the impact of earlier greening due to global warming. 

Lin Meng, Green with phenology, Science (2021). DOI: 10.1126/science.abm8136

https://phys.org/news/2021-11-weather-bright-tree-greening.html?utm...

**

Supercomputer Simulations Test Star-destroying Black Holes

Water disinfection byproduct disrupts reproductive hormones, damages pituitary in female mice

 Chemical disinfection makes water from both natural sources and wastewater streams drinkable; however, the process also creates byproducts, not all of which are understood or regulated. A new study from University of Illinois Urbana-Champaign researchers has found that one byproduct disrupts hormones in the brain that regulate the female reproductive cycle in mice and also damages cells in the pituitary gland.

Iodoacetic acid, or IAA, is created when an oxidizing disinfectant such as chlorine reacts with the iodide naturally present in water, said study leader Lori Raetzman, a professor of molecular and integrative physiology. The new study’s findings of IAA’s effects on reproductive regulation in the brain complement previous work by study co-author Jodi Flaws, a professor of comparative biosciences, which found that IAA also disrupts function in and causes damage to ovary cells, indicating that the chemical could impact the entire reproductive system.

We know we need to disinfect water, but the water that’s coming out of our taps isn’t pure – regulators only screen for the things they know about. Water regulatory bodies have not been looking for IAA. This study is contributing to the growing body of evidence that suggests that IAA may impact reproduction, so it might be reasonable to have screening for this too, and to establish a safe level for it.

In the new study, published in the journal Toxological Sciences, the researchers gave mice drinking water containing IAA at levels comparable to possible human exposure, as well as a control group of mice that were given water with no IAA present, for 35-40 days. Then they measured the production of reproduction-regulating factors in two key parts of the neuroendocrine system – the hypothalamus and the pituitary.

“Mice are often used as models for the human reproductive system because they have estrous cycles that are similar to human menstrual cycles. The hypothalamus and the pituitary are the master regulators of the endocrine system. It’s a good foundation to say that a human exposed to a certain amount of IAA could potentially have similar effects.

The researchers found that, even at low levels, IAA disrupted production of a key reproduction-regulating factor in the hypothalamus. At higher levels, IAA reduced pituitary production of follicle stimulating hormone, a key hormone for promoting egg maturation in the ovaries leading up to ovulation. The hormone also is linked to estrogen production.

n addition, the researchers saw toxic effects, including DNA damage, in the pituitaries of the mice that consumed IAA. Because of this finding and the earlier findings from the Flaws lab regarding ovarian cell damage, the researchers are now investigating whether and how exposing pregnant mice to IAA in drinking water affects their pups.

https://pubmed.ncbi.nlm.nih.gov/34453833/

DOI: 10.1093/toxsci/kfab106

https://researchnews.cc/news/10224/Water-disinfection-byproduct-dis...

Study suggests Sun is likely an unaccounted source of the Earth's water

Researchers have helped unravel the enduring mystery of the origins of the Earth's water, finding the Sun to be a surprising likely source. They found the solar wind, comprised of charged particles from the Sun largely made of hydrogen ions, created water on the surface of dust grains carried on asteroids that smashed into the Earth during the early days of the Solar System.

 Earth 's very water-rich compared to other rocky planets in the Solar System, with oceans covering more than 70 percent of its surface, and scientists had long puzzled over the exact source of it all.

An existing theory is that water was carried to Earth in the final stages of its formation on C-type asteroids, however previous testing of the isotopic 'fingerprint' of these asteroids found they, on average, didn't match with the water found on Earth meaning there was at least one other unaccounted for source.

New work  suggests the solar wind created water on the surface of tiny dust grains and this isotopically lighter water likely provided the remainder of the Earth's water.

This new solar wind theory is based on meticulous atom-by-atom analysis of miniscule fragments of an S-type near-Earth asteroid known as Itokawa, samples of which were collected by the Japanese space probe Hayabusa and returned to Earth in 2010. A world-class atom probe tomography system allowed the researchers to take an incredibly detailed look inside the first 50 nanometres or so of the surface of Itokawa dust grains, which they found contained enough water that, if scaled up, would amount to about 20 liters for every cubic meter of rock.

Luke Daly, Solar wind contributions to Earth's oceans, Nature Astronomy (2021). DOI: 10.1038/s41550-021-01487-w. www.nature.com/articles/s41550-021-01487-w

Researchers discover how water is regenerated on asteroids

https://phys.org/news/2021-11-sun-unaccounted-source-earth.html?utm...

Salt grain size camera!

Micro-sized cameras have great potential to spot problems in the human body and enable sensing for super-small robots, but past approaches captured fuzzy, distorted images with limited fields of view.

But now, researchers  have overcome these obstacles with an ultracompact camera the size of a coarse grain of salt. The new system can produce crisp, full colour images on par with a conventional compound camera lens 500,000 times larger in volume, the researchers reported in a paper published Nov. 29 in Nature Communications.

Enabled by a joint design of the camera's hardware and computational processing, the system could enable minimally invasive endoscopy with medical robots to diagnose and treat diseases, and improve imaging for other robots with size and weight constraints. Arrays of thousands of such cameras could be used for full-scene sensing, turning surfaces into cameras.

While a traditional camera uses a series of curved glass or plastic lenses to bend light rays into focus, the new optical system relies on a technology called a metasurface, which can be produced much like a computer chip. Just half a millimeter wide, the metasurface is studded with 1.6 million cylindrical posts, each roughly the size of the human immunodeficiency virus (HIV).

Each post has a unique geometry, and functions like an optical antenna. Varying the design of each post is necessary to correctly shape the entire optical wavefront. With the help of machine learning-based algorithms, the posts' interactions with light combine to produce the highest-quality images and widest field of view for a full-color metasurface camera developed to date.

A key innovation in the camera's creation was the integrated design of the optical surface and the signal processing algorithms that produce the image. This boosted the camera's performance in natural light conditions.

 Ethan Tseng et al, Neural nano-optics for high-quality thin lens imaging, Nature Communications (2021). DOI: 10.1038/s41467-021-26443-0

https://phys.org/news/2021-11-camera-size-salt-grain.html?utm_sourc...

Living robots that can reproduce!

To persist, life must reproduce.

Over billions of years, organisms have evolved many ways of replicating, from budding plants to sexual animals to invading viruses.

Now scientists have discovered an entirely new form of biological reproduction—and applied their discovery to create the first-ever, self-replicating living robots.

The same team that built the first living robots ("Xenobots," assembled from frog cells—reported in 2020) has discovered that these computer-designed and hand-assembled organisms can swim out into their tiny dish, find single cells, gather hundreds of them together, and assemble "baby" Xenobots inside their Pac-Man-shaped "mouth"—that, a few days later, become new Xenobots that look and move just like themselves.

And then these new Xenobots can go out, find cells, and build copies of themselves. Again and again.

Sam Kriegman el al., "A scalable pipeline for designing reconfigurable organisms," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1910837117

https://techxplore.com/news/2020-01-team-robots.html

Flu virus shells could improve delivery of mRNA into cells

Nanoengineers  have developed a new and potentially more effective way to deliver messenger RNA (mRNA) into cells. Their approach involves packing mRNA inside nanoparticles that mimic the flu virus—a naturally efficient vehicle for delivering genetic material such as RNA inside cells.

The new mRNA delivery nanoparticles are described in a paper published recently in the journal Angewandte Chemie International Edition.

The work addresses a major challenge in the field of drug delivery: Getting large biological drug molecules safely into cells and protecting them from organelles called endosomes. These tiny acid-filled bubbles inside the cell serve as barriers that trap and digest large molecules that try to enter. In order for biological therapeutics to do their job once they are inside the cell, they need a way to escape the endosomes.

Current mRNA delivery methods do not have very effective endosomal escape mechanisms, so the amount of mRNA that actually gets released into cells and shows effect is very low. The majority of them are wasted when they get administered. Achieving efficient endosomal escape would be a game changer for mRNA vaccines and therapies. If you can get more mRNA into cells, this means you can take a much lower dose of an mRNA vaccine, and this could reduce side effects while achieving the same efficacy. It could also improve delivery of small interfering RNA (siRNA) into cells, which is used in some forms of gene therapy.

In nature, viruses do a very good job of escaping the endosome. The influenza A virus, for example, has a special protein on its surface called hemagglutinin, that when activated by acid inside the endosome, triggers the virus to fuse its membrane with the endosomal membrane. This opens up the endosome, enabling the virus to release its genetic material  into the host cell without getting destroyed.

part 1

A research team developed mRNA delivery nanoparticles that mimic the flu virus's ability to do this. To make the nanoparticles, the researchers genetically engineered cells in the lab to express the hemagglutinin protein on their cell membranes. They then separated the membranes from the cells, broke them into tiny pieces, and coated them onto nanoparticles made from a biodegradable polymer that has been pre-packed with mRNA molecules inside.

The finished product is a flu virus-like nanoparticle that can get into a cell, break out of the endosome, and free its mRNA payload to do its job: Instruct the cell to produce proteins.

The researchers tested the nanoparticles in mice. The flu-virus like nano particles effectively delivered their mRNA payloads into cells in vivo.

 Joon Ho Park et al, Virus‐Mimicking Cell Membrane‐Coated Nanoparticles for Cytosolic Delivery of mRNA, Angewandte Chemie International Edition (2021). DOI: 10.1002/anie.202113671

https://phys.org/news/2021-11-flu-virus-shells-delivery-mrna.html?u...

Part 2

Filtering microplastics trash from water with acoustic waves

Microplastics are released into the environment by cosmetics, clothing, and industrial processes or from larger plastic products as they break down naturally.

The pollutants eventually find their way into rivers and oceans, posing problems for marine life. Filtering and removing the small particles from water is a difficult task, but acoustic waves may provide a solution.

A research team used two speakers to create acoustic waves. The force produced by the waves separates the microplastics from the water by creating pressure on a tube of inflowing water. As the tube splits into three channels, the microplastic particles are pressed toward the center as the clean water flows toward the two outer channels.

The prototype device cleaned 150 liters per hour of polluted water and was tested with three different microplastics. Each plastic was filtered with a different efficiency, but all were above 56% efficient in pure water and 58% efficient in seawater. Acoustic frequency, speaker-to-pipe distance, and density of the water all affected the amount of force generated and therefore the efficiency.

The acoustic waves may impact marine life if the wave frequency is in the audible range. The group is currently studying this potential issue.

Source: News Agencies

https://www.eurekalert.org/news-releases/935152

acousticalsociety.org/asa-meetings/

https://phys.org/news/2021-11-filtering-microplastics-trash-acousti...

Engineers create perching bird-like robot

Study links high cholesterol, cardiovascular disease to plastics

Plastics, part of modern life, are useful but can pose a significant challenge to the environment and may also constitute a health concern. Indeed, exposure to plastic-associated chemicals, such as base chemical bisphenol A and phthalate plasticizers, can increase the risk of human cardiovascular disease. What underlying mechanisms cause this, however, remain elusive.

Now in a mouse study,  researchers found a phthalate—a chemical used to make plastics more durable—led to increased plasma cholesterol levels. Dicyclohexyl phthalate, or DCHP, strongly binds to a receptor called pregnane X receptor, or PXR.

DCHP 'turns on' PXR in the gut, inducing the expression of key proteins required for cholesterol absorption and transport. Experiments show that DCHP elicits high cholesterol by targeting intestinal PXR signaling.

Mice exposed to DCHP had in their intestines higher circulating "ceramides"—a class of waxy lipid molecules associated with increased cardiovascular disease risk  in humans—in a way that was PXR-dependent.

This, too, points to the potentially important role of PXR in contributing to the harmful effects of plastic-associated chemicals on cardiovascular health in humans.

"Effects of dicyclohexyl phthalate exposure on PXR activation and lipid homeostasis in miceEnvironmental Health Perspectives (2021). " doi.org/10.1289/EHP9262

https://medicalxpress.com/news/2021-12-links-high-cholesterol-cardi...

Safely delivering radiation to cancer patients in a 'FLASH'

Researchers at Lawrence Livermore National Laboratory (LLNL) have shown for the first time the potential for linear induction accelerators (LIAs) to deliver effective, targeted doses of "FLASH" radiation to cancer patients. The new technique selectively kills cancer cells with minimal damage to healthy cells. The approach is outlined in a Scientific Reports paper.

Efforts to deliver a rapid, high, targeted dose of therapy radiation, or FLASH radiotherapy (FLASH-RT) at the required depth, have required large, complex machines the size of gymnasiums and have so far proven impractical for clinical use. In the Scientific Reports paper, the authors note that LIAs powerful enough to deliver the necessary dose rate to cancer cells can be built only 3 meters long.

Researchers have combined technologies that were developed for weapons—either diagnostics or weapon design itself—and spinning off something that could potentially be a major breakthrough in cancer radiotherapy.

 Stephen E. Sampayan et al, Megavolt bremsstrahlung measurements from linear induction accelerators demonstrate possible use as a FLASH radiotherapy source to reduce acute toxicity, Scientific Reports (2021). DOI: 10.1038/s41598-021-95807-9

https://phys.org/news/2021-12-safely-cancer-patients.html?utm_sourc...

When variations in Earth's orbit drive biological evolution

Coccolithophores are microscopic algae that form tiny limestone plates, called coccoliths, around their single cells. The shape and size of coccoliths varies according to the species. After their death, coccolithophores sink to the bottom of the ocean and their coccoliths accumulate in sediments, which faithfully record the detailed evolution of these organisms over geological time.

A team of scientists led by CNRS researchers show, in an article published in Nature on December 1, 2021, that certain variations in Earth's orbit have influenced the evolution of coccolithophores. To achieve this, no less that 9 million coccoliths, spanning an interval of 2.8 million years and several locations in the tropical ocean, were measured and classified using automated microscope techniques and artificial intelligence.

The researchers observed that coccoliths underwent cycles of higher and lower diversity in size and shape, with rhythms of 100 and 400 thousand years. They also propose a cause: the more or less circular shape of Earth's orbit around the Sun, which varies at the same rhythms. Thus, when Earth's orbit is more circular, as is the case today (this is known as low eccentricity), the equatorial regions show little seasonal variation and species that are not very specialized dominate all the oceans. Conversely, as eccentricity increases and more pronounced seasons appear near the equator, coccolithophores diversify into many specialized species, but collectively produce less limestone.

Crucially, due to their abundance and global distribution, these organisms are responsible for half of the limestone (calcium carbonate, partly composed of carbon) produced in the oceans and therefore play a major role in the carbon cycle and in determining ocean chemistry. It is therefore likely that the cyclic abundance patterns of these limestone producers played a key role in ancient climates, and may explain hitherto mysterious climate variations in past warm periods.

In other words, in the absence of ice, the biological evolution of micro-algae could have set the tempo of climates. This hypothesis remains to be confirmed.

Luc Beaufort, Cyclic evolution of phytoplankton forced by changes in tropical seasonality, Nature (2021). DOI: 10.1038/s41586-021-04195-7. www.nature.com/articles/s41586-021-04195-7

https://phys.org/news/2021-12-variations-earth-orbit-biological-evo...

Pharmaceutical waste contaminates India's main rivers

India's major rivers are thick with heavy metals, dyes, toxic chemicals and pharmaceutical products, a study shows.

The study, published in December in the journal Science of the Total Environment, found high concentrations of pharmaceutical waste as well as toxic metals such as arsenic, zinc, chromium, lead and nickel in the Cauvery, a major river in southern India.

These  observations are alarming. The researchers' environmental risk assessment has shown that pharmaceutical contaminants pose medium to high risk to selected aquatic lifeforms of the riverine system.

Pharmaceutical products found in the river included anti-inflammatories like ibuprofen and diclofenac, anti-hypertensives such as atenolol and isoprenaline, enzyme inhibitors like perindopril, stimulants like caffeine, antidepressants such as carbamazepine, and antibiotics such as ciprofloxacin.

India is among the world's biggest producers of pharmaceutical drugs. Although there are regulations governing effluents from manufacturing units, there is very little real monitoring by regulators such as the state pollution control boards. For instance, the Karnataka State Pollution Control Board takes samples only once in every three months and only during the day whereas illegal dumping of effluents is often done at night.

"Clearly there is a need to ensure that wastewater treatment systems are working optimally to reduce the level of contaminants reaching the rivers," the researchers said.

Jayakumar Renganathan et al, Spatio-temporal distribution of pharmaceutically active compounds in the River Cauvery and its tributaries, South India, Science of The Total Environment (2021). DOI: 10.1016/j.scitotenv.2021.149340

https://phys.org/news/2021-12-pharmaceutical-contaminates-india-mai...

Provided by SciDev.Net

Device instantly detects sepsis via sweat

 Every year, millions of  adults develop sepsis, a life-threatening complication that arises when the body has an overwhelming immune response to an infection. According sepsis causes more than 20 percent of all deaths worldwide.

A crucial aspect of treating sepsis is to catch it at an early stage when a patient’s infection is still curable. Current methods to diagnose sepsis, however, rely on tests that can take days to yield results, while early sepsis can turn into full-blown septic shock within only one hour after the first symptoms emerge.

This means that doctors often need to wait for the results of a test, and the results may not even be accurate if the patient developed a condition after the sample was taken.

The students consulted with sepsis survivors, scientists, and clinicians at the University of Rochester Medical Center to design a sepsis-sensing device, which they named “Bio-Spire,” a combination of “biology” and “perspire.” Bio-Spire is a biosensor that continuously monitors the levels of biomarkers in sweat. Unlike blood, sweat is a noninvasive medium to collect, and unlike saliva or urine, biomarkers in sweat can be continuously analyzed. The levels of biomarkers in blood and in sweat are correlated, so changes in the amount of biomarkers in sweat are indicative of changes in the blood.

That is, a change in biomarker levels in a patient’s sweat can signify a deterioration of the patient’s condition—and may signify sepsis.

Doctors use many different tools to diagnose patients, one of which is the presence and concentration of certain biomarkers—molecules such as proteins or sugar that are associated with a particular disease, condition, or biological process. There are several ways to measure biomarker concentrations, including test strips and lab-on-a-chip devices, but many of these approaches only show biomarker concentrations at one specific point in time. These methods can also be expensive, and many take hours to perform.

In order to address this problem, a team of 12 undergraduate students  developed a novel device that instantaneously diagnoses sepsis based on biomarkers in a person’s sweat. The device offers a noninvasive way to monitor sepsis in real-time and uses materials that are environmentally friendly and affordable, making the device easily deployable in low-income countries.

Bio-Spire is designed to collect a tiny amount of sweat from a patient’s skin and wick the sweat past an integrated set of electrodes covered in biomarker detectors. The biomarker detectors consist of short pieces of DNA receptors attached to a small sheet of graphene—an ultra-thin layer of material that is highly conductive. The students synthetically created their own graphene and DNA in an environmentally-friendly manner by using engineered biological components.

When the sleeve-like device is placed on a patient’s arm, biomarkers associated with sepsis bind to the DNA receptors, changing the conductivity of the graphene sheet and triggering an electrical resistance in the electrodes, which is then recorded on a computer. The students created software that displays the concentrations of sepsis biomarkers in real time, permitting health care workers to receive up-to-the-minute updates on a patient’s condition.

https://www.rochester.edu/newscenter/what-is-sepsis-diagnosis-devic...

https://researchnews.cc/news/10312/Rochester-students--award-winnin...

Some tissues can 'breathe' without oxygen

Humans need oxygen molecules for a process called cellular respiration, which takes place in our cells' mitochondria. Through a series of reactions called the electron transport chain, electrons are passed along in a sort of cellular relay race, allowing the cell to create ATP, the molecule that gives our cells energy to complete their vital functions.

At the end of this chain, two electrons remain, which are typically passed off to oxygen, the "terminal electron acceptor." This completes the reaction and allows the process to continue with more electrons entering the electron transport chain.

In the past, however, scientists have noticed that cells are able to maintain some functions of the electron transport chain, even in the absence of oxygen. "This indicated that mitochondria could actually have partial function, even when oxygen is not the electron acceptor. How does this work? How are mitochondria capable of maintaining these electron inputs when oxygen is not the terminal electron acceptor?"

Scientists  have found the answer to these questions recently. Their research shows that when cells are deprived of oxygen, another molecule called fumarate can step in and serve as a terminal electron acceptor to enable mitochondrial function in this environment. 

The research answers a long-standing mystery in the field of cellular metabolism, and could potentially inform research into diseases that cause low oxygen levels in tissues, including ischemia, diabetes and cancer.

Jessica B. Spinelli et al, Fumarate is a terminal electron acceptor in the mammalian electron transport chain, Science (2021). DOI: 10.1126/science.abi7495

Part 1

The researchers began their investigation into how cells can maintain mitochondrial function without oxygen by using mass spectrometry to measure the quantities of molecules called metabolites that are produced through cellular respiration in both normal and low-oxygen conditions. When cells were deprived of oxygen, researchers noticed a high level of a molecule called succinate.

When you add electrons to oxygen at the end of the electron transport chain, it picks up two protons and becomes water. When you add electrons to fumarate, it becomes succinate. This led the researchers to think that maybe this accumulation of succinate that's occurring could actually be caused by fumarate being used as an electron acceptor, and that this reaction could explain the maintenance of mitochondrial functions in hypoxia.

Usually, the fumarate-succinate reaction runs the other direction in cells—a protein complex called the SDH complex takes away electrons from succinate, leaving fumarate. For the opposite to happen, the SDH complex would need to be running in reverse.

Through a series of assays, however, the researchers were able to ascertain that this complex was indeed running in reverse in cultured cells, largely due to accumulation of a molecule called ubiquinol, which the researchers observed to build up under low-oxygen conditions.

https://phys.org/news/2021-12-tissues-oxygen.html?utm_source=nwlett...

Part 2

A Fusion Reaction Has Generated More Energy Than Absorbed by The Fuel

For the first time, a fusion reaction has achieved a record 1.3 megajoule energy output – and for the first time, exceeding energy absorbed by the fuel used to trigger it.

Inertial confinement fusion involves creating something like a tiny star. It starts with a capsule of fuel, consisting of deuterium and tritium – heavier isotopes of hydrogen. This fuel capsule is placed in a hollow gold chamber about the size of a pencil eraser called a hohlraum.

Then, 192 high-powered laser beams are blasted at the hohlraum, where they are converted into X-rays. These X-rays implode the fuel capsule, heating and compressing it to conditions comparable to those in the center of a star – temperatures in excess of 100 million degrees Celsius (180 million Fahrenheit) and pressures greater than 100 billion Earth atmospheres – turning the fuel capsule into a tiny blob of plasma.

And, just as hydrogen fuses into heavier elements in the heart of a main-sequence star, so too does the deuterium and tritium in the fuel capsule. The whole process takes place in just a few billionths of a second. The goal is to achieve ignition – a point at which the energy generated by the fusion process exceeds the total energy input.

The experiment, conducted on 8 August, fell just short of that mark; the input from the lasers was 1.9 megajoules. But it's still tremendously exciting, because according to the team's measurements, the fuel capsule absorbed over five times less energy than it generated in the fusion process. The result also opens up new avenues for experimental research.

https://meetings.aps.org/Meeting/DPP21/Session/AR01.1

https://www.sciencealert.com/for-the-first-time-a-fusion-reaction-h...

Humans Are Doomed to Go Extinct

Habitat degradation, low genetic variation and declining fertility are setting Homo sapiens up for collapse 

The first international framework on open science was adopted by 193 countries attending UNESCO’s General Conference. By making science more transparent and more accessible, the UNESCO Recommendation on Open Science will make science more equitable and inclusive. 

Through open science, scientists and engineers use open licenses to share their publications and data, software and even hardware more widely. Open science should, thus, enhance international scientific cooperation. 

Researchers develop ice cube that doesn't melt or grow mold

Researchers have developed a new type of cooling cube that could revolutionize how food is kept cold and shipped fresh without relying on ice or traditional cooling packs.

These plastic-free, "jelly ice cubes" do not melt, are compostable and anti-microbial, and prevent cross-contamination.

The cooling cubes contain more than 90 percent water and other components to retain and stabilize the structure. They are soft to the touch like a gelatin dessert and change color depending on temperature. These reusable cubes can be designed or cut to any shape and size needed. You can use it for 13 hours for cooling, collect it, rinse it with water and put it in the freezer to freeze again for the next use.

The jelly ice cubes offer an alternative to traditional ice and could potentially reduce water consumption and environmental impact. They also offer stable temperatures to reduce food spoilage and could be ideal for meal prep companies, shipping businesses and food producers who need to keep items cold.

The application could potentially reduce water consumption in the food supply chain and food waste by controlling microbial contaminations. The research was published in the American Chemical Society's journal, Sustainable Chemistry & Engineering.

Jiahan Zou et al, Sustainable and Reusable Gelatin-Based Hydrogel "Jelly Ice Cubes" as Food Coolant. II: Ideal Freeze–Thaw Conditions, ACS Sustainable Chemistry & Engineering (2021). DOI: 10.1021/acssuschemeng.1c06309

https://phys.org/news/2021-11-ice-cube-doesnt-mold.html?utm_source=...

Scientists discover potential cause of Alzheimer's disease

Prevailing theories posit plaques in the brain cause Alzheimer's disease. New research instead points to cells' slowing ability to clean themselves as the likely cause of unhealthy brain buildup.

Along with signs of dementia, doctors make a definitive Alzheimer's diagnosis if they find a combination of two things in the brain: amyloid plaques and neurofibrillary tangles. The plaques are a buildup of amyloid peptides, and the tangles are mostly made of a protein called tau.

Roughly 20% of people have the plaques, but no signs of dementia. This makes it seem as though the plaques themselves are not the cause.

For this reason, researchers investigated understudied aspects of tau protein. They wanted to understand whether a close examination of tau could reveal more about the mechanism behind the plaques and tangles.

A key but difficult-to-detect difference in the form of tau allowed the scientists to distinguish between people who expressed no outward signs of dementia from those who did. These results have now been published in the Journal of Proteome Research.

Researchers scanned all the proteins in donated brain samples. Those with brain buildup but no dementia had normal tau while a different-handed form of tau was found in those who developed plaques or tangles as well as dementia.

Most proteins in the body have a half-life of less than 48 hours. However, if the protein hangs out too long, certain amino acids can convert into the other-handed isomer.

In general, the process of clearing spent or defective proteins from cells, known as autophagy, slows down in people over the age of 65. 

 Evan E. Hubbard et al, Does Data-Independent Acquisition Data Contain Hidden Gems? A Case Study Related to Alzheimer's Disease, Journal of Proteome Research (2021). DOI: 10.1021/acs.jproteome.1c00558

https://medicalxpress.com/news/2021-11-scientists-potential-alzheim...

Evidence emerges for dark-matter free galaxies

An international team of astronomers led by researchers from the Netherlands has found no trace of dark matter in the galaxy AGC 114905, despite taking detailed measurements over a course of forty hours with state-of-the-art telescopes. They will present their findings in Monthly Notices of the Royal Astronomical Society.

discovered six galaxies with little to no dark matter, they were told "measure again, you'll see that there will be dark matter around your galaxy". However, after forty hours of detailed observations using the Very Large Array (VLA) in New Mexico (United States), the evidence for a dark matter-free galaxy only became stronger.

The galaxy in question, AGC 114905, is about 250 million light-years away. It is classified as an ultra-diffuse dwarf galaxy, with the name 'dwarf galaxy' referring to its luminosity and not to its size. The galaxy is about the size of our own Milky Way but contains a thousand times fewer stars. The prevailing idea is that all galaxies, and certainly ultra-diffuse dwarf galaxies, can only exist if they are held together by dark matter.

The researchers collected data on the rotation of gas in AGC 114905 for 40 hours between July and October 2020 using the VLA telescope. Subsequently, they made a graph showing the distance of the gas from the center of the galaxy on the x-axis and the rotation speed of the gas on the y-axis. This is a standard way to reveal the presence of dark matter. The graph shows that the motions of the gas in AGC 114905 can be completely explained by just normal matter.

Part1

In their scientific publication, the researchers list the possible explanations for the lack of dark matter one by one. For example, AGC 114905 could have been stripped of dark matter by large nearby galaxies. Mancera Piña: "But there are none. And in the most reputed galaxy formation framework, the so called cold dark matter model, we would have to introduce extreme parameter values that are far beyond the usual range. Also with modified Newtonian dynamics, an alternative theory to cold dark matter, we cannot reproduce the motions of the gas within the galaxy."

According to the researchers, there is one more assumption that could change their conclusions. That is the estimated angle at which they think they are observing the galaxy. "But that angle has to deviate very much from our estimate before there is room for dark matter again," says co-author Tom Oosterloo (ASTRON).

Meanwhile, the researchers are examining a second ultra-diffuse dwarf galaxy in detail. If again observe no trace of dark matter in that galaxy, it will make the case for dark matter poor galaxies even stronger.

The research of Mancera Piña and colleagues is not an isolated case. Earlier, for example, the Dutch American Pieter van Dokkum (Yale University, U.S.) discovered a galaxy with hardly any dark matter. The techniques and measurements of Mancera Piña and colleagues are more robust.

No need for dark matter: resolved kinematics of the ultra-diffuse galaxy AGC 114905 arXiv:2112.00017 [astro-ph.GA] arxiv.org/abs/2112.00017 . Accepted for publication in Monthly Notices of the Royal Astronomical Society.

https://phys.org/news/2021-12-evidence-emerges-dark-matter-free-gal...

Part 2

**

How SARS-CoV-2 evades the immune system

Researchers have found SARS-CoV-2 can knock out an important molecular pathway linked to an immune complex called MHC class I. The finding should help scientists better understand how COVID-19 infection takes hold.

Scientists used a bioinformatics approach to look at how SARS-CoV-2, the virus that causes COVID-19, changes gene expression in the immune systems of COVID-19 patients compared to uninfected individuals. This is a useful way to look into the function of complicated cell signaling pathways that trigger immune responses to fight off harmful bacteria and viruses.

MHC (major histocompatibility complex) class I molecules are a central weapon in the immune response against viruses. When a virus infects a cell, the cell facilitates the expression of viral antigens on the surface of infected cells, drawing the attention of immune cells called cytotoxic T cells. These immune cells zero in on and destroy the infected cells, together with the invading virus inside them. In addition to analyzing gene expression in COVID-19 patients, the research team also infected human cell lines with the SARS-CoV-2 virus to validate their findings.

The results showed that a protein from the SARS-CoV-2 virus, called ORF 6, suppresses a host cell protein, called NLRC5, responsible for activating the MHC class I pathway.

The study showed this happens in two ways. ORF6 hampers cell signaling, which turns off the expression of NLRC5. ORF6 also blocks the function of NLRC5.

Other infectious viruses, including HIV and MERS, are known to also target the MHC class I pathway. Researchers believed that SARS-CoV-2 probably did as well, but this study is the first to unravel the mechanism.

"Without the activation of the MHC class I pathway, viruses in the infected cells are essentially hidden from the immune system. That helps to explain why SARS-CoV-2 virus persists in the body and why it keeps infecting others, leading to the pandemic.

Further research could help find and test drugs that block the activity of the ORF6 viral protein, to restore host cell ability to activate the major histocompatibility complex. If successful, such drugs could encourage the host immune system to clear the virus itself, effectively boosting immune responses.

Ji-Seung Yoo et al, SARS-CoV-2 inhibits induction of the MHC class I pathway by targeting the STAT1-IRF1-NLRC5 axis, Nature Communications (2021). DOI: 10.1038/s41467-021-26910-8

https://medicalxpress.com/news/2021-12-sars-cov-evades-immune.html?...

Researchers develop a world-first antibody-drug delivery system

Imagine this: a man-made crystal that can be attached to antibodies and then supercharge them with potent drugs or imaging agents that can seek out diseased cells with the highest precision, resulting in fewer adverse effects for the patient.

That is precisely what researchers  have developed: the world's first metal-organic framework (MOFs) antibody-drug delivery system that has the potential to fast-track potent new therapies for cancer, cardiovascular and auto-immune diseases.

The in vitro study showed that when MOF antibody crystals bind to their target cancer cells and if exposed to the low pH in the cells, they break down, delivering the drugs directly and solely to the desired area.   

The metal-organic framework, a mixture of metal (zinc) and carbonate ions, and a small organic molecule (an imidazole, a colorless solid compound that is soluble in water) not only keeps the payload attached to the antibody but can also acts as a reservoir of personalized therapeutics. This is a benefit with the potential to become a new medical tool to target specific diseases with customized drugs and optimized doses.

With just 0.01 per cent of chemotherapy currently reaching the cancer tissue, this revolutionary new method can boost the potency of the drugs reaching their target.

With over 80 different monoclonal antibodies approved for clinical use, this approach has enormous potential to improve these antibodies for the targeted delivery of diagnostic agents and therapeutic drugs. The goal is that ultimately the clinical translation of this technology will improve the quality of life for patients suffering from serious diseases.

Karen Alt et al, Self‐Assembly of Oriented Antibody‐Decorated Metal‐Organic Framework Nanocrystals for Active Targeting Applications, Advanced Materials (2021). DOI: 10.1002/adma.202106607

https://phys.org/news/2021-12-world-first-antibody-drug-delivery.ht...

Transverse sound wave discovered

The physics textbooks tell us there are two kinds of waves. In transverse waves like light, the vibrations are perpendicular to the direction of wave propagation. In longitudinal waves like sound, the vibrations are parallel to the direction of wave propagation. But the latest discovery by scientists  changes this understanding of sound waves.

Imagine sound traveling in the same way as light does.

A research team  has discovered a new type of sound wave: The airborne sound wave vibrates transversely and carries both spin and orbital angular momentum like light does. The findings shattered scientists' previous thinking about the sound wave, opening an avenue to the development of novel applications in acoustic communications, acoustic sensing and imaging.

While the airborne sound is a longitudinal wave in usual cases,  this new study demonstrated for the first time that it can be a transverse wave under certain conditions. And physicists  investigated its spin-orbit interactions (an important property only exists in transverse waves), i.e. the coupling between two types of angular momentum. The finding provides new degrees of freedom for sound manipulations.

The absence of shear force in the air, or fluids, is the reason why sound is a longitudinal wave .  Researchers had been exploring whether it is possible to realize transverse sound, which requires shear force. Then they conceived the idea that synthetic shear force may arise if the air is discretized into "meta-atoms," i.e., volumetric air confined in small resonators with size much smaller than the wavelength. The collective motion of these air "meta-atoms" can give rise to a transverse sound on the macroscopic scale.

Shubo Wang et al, Spin-orbit interactions of transverse sound, Nature Communications (2021). DOI: 10.1038/s41467-021-26375-9

https://phys.org/news/2021-12-physicists-special-transverse.html?ut...

Evidence emerges for dark-matter free galaxies

 An international team of astronomers has found no trace of dark matter in the galaxy AGC 114905, despite taking detailed measurements over a course of forty hours with state-of-the-art telescopes.

When Researchers discovered six galaxies with little to no dark matter, they were told "measure again, you'll see that there will be dark matter around your galaxy". However, after forty hours of detailed observations using the Very Large Array (VLA) in New Mexico (United States), the evidence for a dark matter-free galaxy only became stronger.

The galaxy in question, AGC 114905, is about 250 million light-years away. It is classified as an ultra-diffuse dwarf galaxy, with the name 'dwarf galaxy' referring to its luminosity and not to its size. The galaxy is about the size of our own Milky Way but contains a thousand times fewer stars. The prevailing idea is that all galaxies, and certainly ultra-diffuse dwarf galaxies, can only exist if they are held together by dark matter.

The researchers collected data on the rotation of gas in AGC 114905 for 40 hours between July and October 2020 using the VLA telescope. Subsequently, they made a graph showing the distance of the gas from the center of the galaxy on the x-axis and the rotation speed of the gas on the y-axis. This is a standard way to reveal the presence of dark matter. The graph shows that the motions of the gas in AGC 114905 can be completely explained by just normal matter.

In their scientific publication, the researchers list the possible explanations for the lack of dark matter one by one. For example, AGC 114905 could have been stripped of dark matter by large nearby galaxies.

But there are none. And in the most reputed galaxy formation framework, the so called cold dark matter model, they would have to introduce extreme parameter values that are far beyond the usual range. Also with modified Newtonian dynamics, an alternative theory to cold dark matter, they cannot reproduce the motions of the gas within the galaxy.

According to the researchers, there is one more assumption that could change their conclusions. That is the estimated angle at which they think they are observing the galaxy. But that angle has to deviate very much from their estimate before there is room for dark matter again.

Meanwhile, the researchers are examining a second ultra-diffuse dwarf galaxy in detail. If again observe no trace of dark matter in that galaxy, it will make the case for dark matter poor galaxies even stronger.

https://researchnews.cc/news/10404/Evidence-emerges-for-dark-matter...

**

The World's Most Dangerous Blood Type

Scientists Observe Quantum Spin Liquids: A State of Matter We've Never Seen Before

An exotic and totally new state of matter called a quantum spin liquid has been hypothesized for decades, and now scientists have been able to observe it in a laboratory for the first time.

The 'liquid' part refers to electrons that are constantly changing and fluctuating inside a magnetic material at low temperatures. Unlike regular magnets, in this case the electrons don't stabilize or settle into the structured lattice of a solid as they are cooled.

The 'quantum spin' refers to orientation of angular momentum (up or down) carried by particles, which are entangled in pairs with opposing spins. Now that the state has been observed for the first time, it's hoped that the discovery can advance progress in the development of quantum computers.

Normal magnets feature electrons whose spin is orientated in the same direction either up or down, which is what generates magnetism.

In quantum spin liquids, a third electron is introduced, so while two opposing spins will stabilize each other, the spin from the third electron throws out the balance. It creates a 'frustrated' magnet where the spins can't all stabilize in one direction.

To produce their own frustrated lattice pattern, the team used a programmable quantum simulator built in 2017. The simulator uses a quantum computer program to hold atoms in custom shapes using lasers – like squares, triangles, or honeycombs – and can be used to engineer different quantum interactions and processes.

The simulator uses tightly focussed laser beams to arrange atoms individually, and by arranging the atoms of rubidium in a triangle-patterned lattice the researchers were able to produce a frustrated magnet with properties of quantum entanglement – where changes in one atom are matched in a second entangled atom.

The connections between the atoms indicated that a quantum spin liquid had indeed been created.

https://www.science.org/doi/10.1126/science.abi8794

https://www.sciencealert.com/scientists-document-quantum-spin-liqui...

Blood from marathoner mice boosts brain function in their couch-potato counterparts

Physical exercise is great for a mouse's brain, and for yours. Numerous studies conducted in mice, humans and laboratory glassware have made this clear. Now, a new study shows it's possible to transfer the brain benefits enjoyed by marathon-running mice to their couch-potato peers.

Researchers have shown that blood from young adult mice that are getting lots of exercise benefits the brains of same-aged, sedentary mice. A single protein in the blood of exercising mice seems largely responsible for that benefit.

The discovery could open the door to treatments that—by taming brain inflammation in people who don't get much exercise—lower their risk of neurodegenerative disease or slow its progression.

Researchers compared blood samples from exercising and sedentary mice of the same age. They showed that transfusions of blood from running mice reduced neuroinflammation in the sedentary mice and improved their cognitive performance. In addition, the researchers isolated a blood-borne protein that appears to play an important role in the anti-neuroinflammatory exercise effect.

Neuroinflammation has been strongly tied to neurodegenerative diseases in humans.  Animal studies have indicated that neuroinflammation precipitates neurodegenerative disorders and that reversing or reducing neuroinflammation can prolong cognitive health

part1

Removing a single protein, clusterin, from marathoner mice's plasma largely negated its anti-inflammatory effect on sedentary mice's brains. No other protein the scientists similarly tested had the same effect.

Clusterin, an inhibitor of the complement cascade, was significantly more abundant in the marathoners' blood than in the couch potatoes' blood.

Further experiments showed that clusterin binds to receptors that abound on brain endothelial cells, the cells that line the blood vessels of the brain. These cells are inflamed in the majority of Alzheimer's patients

Research has shown that blood endothelial cells are capable of transducing chemical signals from circulating blood, including inflammatory signals, into the brain.

Tony Wyss-Coray, Exercise plasma boosts memory and dampens brain inflammation via clusterin, Nature (2021). DOI: 10.1038/s41586-021-04183-x. www.nature.com/articles/s41586-021-04183-x

https://medicalxpress.com/news/2021-12-blood-marathoner-mice-boosts...

Part 2

Plants buy us time to slow climate change—but not enough to stop it

Plants take up carbon dioxide from the atmosphere and convert it into food, forests and other similar ecosystems are considered to be some of the planet's most important carbon sinks.

As human activities cause more carbon dioxide to be emitted into the atmosphere, scientists have debated whether plants are responding by photosynthesizing more and sucking up even more carbon dioxide than they already do—and if so, is it a little or a lot more. Now an international team of researchers led by Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have used a novel methodology combining remote sensing, machine learning, and terrestrial biosphere models to find that plants are indeed photosynthesizing more, to the tune of 12% higher global photosynthesis from 1982 to 2020. In that same time period, global carbon dioxide concentrations in the atmosphere grew about 17%, from 360 parts per million (ppm) to 420 ppm.

The 12% increase in photosynthesis translates to 14 petagrams of additional carbon taken out of the atmosphere by plants each year, roughly the equivalent of the carbon emitted worldwide from burning fossil fuels in 2020 alone. Not all of the carbon taken out of the atmosphere through photosynthesis is stored in ecosystems, as much is later released back to the atmosphere through respiration, but the study reports a direct link between the increased photosynthesis and increased global carbon storage. The study was published in Nature.

This is a very large increase in photosynthesis, but it's nowhere close to removing the amount of carbon dioxide we're putting into the atmosphere. It's not stopping climate change by any means, but it is helping us slow it down.

Trevor Keenan, A constraint on historic growth in global photosynthesis due to rising CO2 (N&V), Nature (2021). DOI: 10.1038/s41586-021-04096-9. www.nature.com/articles/s41586-021-04096-9

https://phys.org/news/2021-12-climate-changebut.html?utm_source=nwl...

A new view of the Universe

Engineers build in-pipe sewer robot

Scientists from the Division of Mechanical Science and Engineering at Kanazawa University developed a prototype pipe maintenance robot that can unclog and repair pipes with a wide range of diameters. Using a cutting tool with multiple degrees of freedom, the machine is capable of manipulating and dissecting objects for removal. This work may be a significant step forward for the field of sewerage maintenance robots.

Various sewer pipes that are essential to the services of buildings require regular inspection, repair, and maintenance. Current robots that move inside pipes are primarily designed only for visual surveying or inspection. Some robots were developed for maintenance, but they couldn't execute complicated tasks. In-pipe robots that can also clear blockages or perform complex maintenance tasks are highly desirable, especially for pipes that are too narrow for humans to traverse. Now, a team of researchers at Kanazawa University have developed and tested a prototype with these capabilities. 

This robot can help civic and industrial workers by making their job much safer. It can operate in small pipes that humans either cannot access or are dangerous.

Thaelasutt Tugeumwolachot et al, Development of a compact sewerage robot with multi-DOF cutting tool, Artificial Life and Robotics (2021). DOI: 10.1007/s10015-021-00694-y

https://techxplore.com/news/2021-12-in-pipe-sewer-robot.html?utm_so...

**

Scientists solve the grass leaf conundrum

Grass is cut regularly by our mowers and grazed on by cows and sheep, yet continues to grow back. The secret to its remarkable regenerative powers lies in part in the shape of its leaves, but how that shape arises has been a topic of longstanding debate. 

The debate is relevant to our staple crops wheat, rice and maize, because they are members of the grass family with the same type of leaf.

The mystery of grass leaf formation has now been unraveled by a research team.

Flowering plants can be categorized into monocots and eudicots. Monocots, which include the grass family, have leaves that encircle the stem at their base and have parallel veins throughout. Eudicots, which include brassicas, legumes and most common garden shrubs and trees, have leaves that are held away from the stem by stalks, termed petioles, and typically have broad laminas with net-like veins.

In grasses, the base of the leaf forms a tube-like structure, called the sheath. The sheath allows the plant to increase in height while keeping its growing tip close to the ground, protecting it from the blades of lawnmowers or incisors of herbivores. Using recent advances in computational modeling and developmental genetics, the team revisited the problem of grass development. They modeled different hypotheses for how grass leaves grow, and tested the predictions of each model against experimental results. To their surprise, they found that the model based on the 19^th century idea of sheath-petiole equivalence was much more strongly supported than the current view.

The grass study shows how simple modulations of growth rules, based on a common pattern of gene activities, can generate a remarkable diversity of different leaf shapes, without which our gardens and dining tables would be much poorer.

Annis Richardson et al, Evolution of the grass leaf by primordium extension and petiole-lamina remodeling, Science (2021). DOI: 10.1126/science.abf9407. www.science.org/doi/10.1126/science.abf9407

https://phys.org/news/2021-12-scientists-grass-leaf-conundrum.html?...

Why global tech turns to Indian talent

Twitter's new CEO Parag Agrawal is the latest alumnus of India's prestigious technical universities appointed to head a multi-billion-dollar US tech firm.

Google-parent Alphabet's 49-year-old CEO Sundar Pichai. Other Indians at the highest corporate tech echelons include IBM's Arvind Krishna and Palo Alto Networks' Nikesh Arora—both IIT alumni—along with Satya Nadella of Microsoft and Shantanu Narayen at Adobe.

If you ask why Indians are succeeding like hell, here is what the experts say:

beyond the South Asian nation's sheer size, the phenomenon is due to multiple push-pull factors and skillsets including a culture of problem-solving, the English language, and relentless hard work. 

after growing up with multiple communities, customs and languages, Indians have the ability to "navigate complex situations".

"Educational competition in India and societal chaos helps hone their skills in addition to the rigorous technical education at the IITs.

Silicon Valley demands technical expertise, managing diverse communities, and entrepreneurship in the face of uncertainty from its top executives.

"In innovation, you have to be able to break the rules, you're fearless. And... you can't survive a day in India without having to break one rule or the other or dealing with incompetent bureaucracy or corruption. Those skills are very useful when you're innovating in Silicon Valley, because you have to constantly challenge authority. The contest for such prizes begins early in a country of more than 1.3 billion people with a longstanding focus on education.

Agrawal, Pichai and Nadella spent a decade or more working their way through the ranks of their respective companies, building up insider knowledge while gaining the trust of the firms' American founders.

And for years, more than half the applicants for US H1-B skilled immigrant visas have been from India, and mostly from the tech sector.

The phenomenon may wane in time as India's own tech sector thrives, offering the country's best and brightest minds greater domestic opportunities.

https://techxplore.com/news/2021-12-global-tech-indian-talent.html?...

New prime editing system inserts entire genes in human cells

Researchers  have developed a new version of prime editing that can install or swap out gene-sized DNA sequences. First developed in 2019, prime editing is a precise method of making a wide diversity of gene edits in human cells, including small substitutions, insertions, and deletions.

In a study published recently in Nature Biotechnology, the team describes twin prime editing (twinPE), a technique that makes two adjacent prime edits to introduce larger sequences of DNA at specific locations in the genome with few unwanted byproducts. With further development, the technology could potentially be used as a new form of gene therapy to insert therapeutic genes in a safe and highly targeted manner to replace mutated or missing genes.

The researchers demonstrated the therapeutic potential of twinPE by editing, in human cells, a gene linked to Hunter syndrome, a rare genetic disorder. This disease is caused by an inversion of a specific 40,000 base pair long stretch of DNA. The team used twinPE to introduce an inversion of a similar length at the same site in the genome, showing how the method could be used to correct the disease-causing mutation. The team also used twin PE to precisely insert gene-sized DNA cargo of thousands of base pairs into therapeutically relevant sites in the genome.

The approach addresses a limitation of the original prime editing system, which can edit only several dozen base pairs. However, the study or treatment of some genetic diseases could require larger edits. Like the original prime editing method, twinPE also does not completely sever the DNA double helix by cutting both strands simultaneously at the same location, which can induce poorly controlled editing outcomes and harmful chromosomal abnormalities.

TwinPE could be a potentially safer and more precise way to insert whole genes of therapeutic interest into positions we specify, such as the location of the native gene in healthy individuals or 'safe harbor' sites thought to minimize the risk of side-effects.

Prime editing, developed by Liu's lab, enables DNA substitutions, insertions, and deletions, and promises to correct the majority of known disease-causing genetic variations. Recent improvements to prime editing technology increased its efficiency, edging it closer to therapeutic applications. But editing sequences longer than 100 base pairs remained inefficient.

Twin prime editing fills this gap. The system uses a prime editor protein and two prime editing guide RNAs, which guide the editing machinery and encode the edits. Each of the two guide RNAs direct the editing protein to make a single-stranded nick in the DNA at different targeted sites in the genome, avoiding the kind of double-strand break that creates unwanted byproducts in other methods. The system then synthesizes two new complementary DNA strands containing the desired sequence in between the two nicks. Using this approach, the researchers were able to insert, substitute, or delete sequences up to about 800 base pairs long.

Part 1

To edit even larger sequences, the researchers used their twin prime editing system to install "landing sites" in the genome for enzymes called site-specific recombinases, which catalyze the integration of DNA at specific sites in the genome. The team then treated the cells with a recombinase enzyme and introduced the long pieces of DNA they wanted to insert into the genome. Combining twinPE and recombinase enzymes allowed the scientists to edit sequences thousands of base pairs long—the length of entire genes.

 Andrew V. Anzalone et al, Programmable deletion, replacement, integration and inversion of large DNA sequences with twin prime editing, Nature Biotechnology (2021). DOI: 10.1038/s41587-021-01133-w

https://phys.org/news/2021-12-prime-inserts-entire-genes-human.html...

Inching closer towards "living biotherapeutics"

The human gut is home to thousands of species of bacteria, and some of those bacteria have the potential to treat a variety of gastrointestinal diseases. Some species may help to combat colon cancer, while others could help treat or prevent infections such as C. difficile.

One of the obstacles to developing these "living biotherapeutics" is that many of the species that could be beneficial are harmed by oxygen, making it difficult to manufacture, store, and deliver them. Chemical engineers have now shown that they can protect those bacteria with a coating that helps them to survive the manufacturing process.

In a study appearing today in the Journal of the American Chemical Society, the researchers showed they could use the coating on a strain of E. coli as well as another species that may aid in digestion of plant starches. The coating could be applied to many other species as well, they say. They think this coating could be used to protect pretty much any microbe of interest.

Most of the microbes that live in the human gut are anaerobic, and they have varying degrees of sensitivity to oxygen. Some can tolerate a little bit of oxygen, while for others, oxygen is deadly.

This makes it difficult to test their potential as treatments for human disease, because bacteria need to be freeze-dried and formulated as capsules in order to be used therapeutically. In this study, researchers decided to try protecting anaerobic bacteria by coating them with a material made from metal ions and organic compounds called polyphenols.

When polyphenols and metal ions are put into a solution, they form a two-dimensional, grid-like sheet. For this study, the researchers used iron, which is safe for human consumption, and three polyphenols that are all classified as GRAS (generally regarded as safe) : gallic acid, tannic acid, and epigallocatechin (EGCG), all of which are found in tea and other plant products.

If bacteria are also added to the solution, the material self-assembles into a coating on individual bacterial cells. This coating protects bacteria during the freeze-drying and manufacturing process. The researchers showed that the coated cells were healthy and able to perform normal cellular activities, although their growth was temporarily inhibited.

When exposed to an acidic environment, such as that of the stomach, the coating breaks down and releases the bacteria. Coating the bacteria with a protective layer could eliminate the need for cold storage and make distribution easier. This would make a lot of therapeutics more widely available.

Gang Fan et al, Protection of Anaerobic Microbes from Processing Stressors Using Metal–Phenolic Networks, Journal of the American Chemical Society (2021). DOI: 10.1021/jacs.1c09018

https://phys.org/news/2021-12-biotherapeutics.html?utm_source=nwlet...

Science with Webb: the nearby cosmos

Scientists Smash Temperature Record on Keeping 'Freezing Cold' Water in Liquid Form

Scientists have just proven that the freezing temperature of water can be even lower than what we thought was possible.

Taking tiny droplets of water, up to just 150 nanometers in size, a team of engineers at the University of Houston has pushed the critical temperature threshold to -44 degrees Celsius (-47.2 degrees Fahrenheit) – and, more saliently, accurately measured it.

common H₂O is actually pretty weird; it doesn't behave like any other liquid. Even the way it freezes is weird: where other liquids increase in density as they cool, water actually becomes less dense as it freezes.

Water's behavior has been fairly well characterized and studied. We know, for example, that it tends to nucleate, or form ice crystals, at a variety of temperatures, sometimes resisting the process as far as -38 degrees Celsius. Any colder, and even the most stubborn water molecules will stick together as ice.

pushed that temperature downwards by placing nanodroplets of water on a soft surface, like a gel or a lipid. Then, they probed the droplets using electrical resistance metrology and Fourier transform infrared spectroscopy to take their temperature as they froze.

The soft interface between the surface and the tiny droplet seemed to play a role in the suppression of ice nucleation, possibly because of the way the interface generates a large pressure on the droplet.

This is because the freezing temperature of water drops as ambient pressure rises. The most pronounced effect was seen in a droplet of water just 2 nanometers across.

If a water droplet is in contact with a soft interface, freezing temperature could be significantly lower than hard surfaces. And a few-nanometer water droplet could avoid freezing down to -44 degrees Celsius if it is in contact with a soft interface.

The way tiny water droplets freeze is vitally important to cryopreservation, since the freezing of tiny droplets within cells can cause those cells to rupture and die. Learning how to slow or halt that process could help scientists find ways to mitigate that effect. It could also help us better understand how nucleation happens in the atmosphere, where microscopic droplets of water freeze. And it could also help us to better design technology that suffers from ice exposure, such as aircraft and wind turbines.

https://www.nature.com/articles/s41467-021-27346-w

https://www.sciencealert.com/scientists-break-a-temperature-record-...

Synthetic Food Dyes and health risk

Early-onset colorectal cancer incidence among the young, defined as those under age 50, has been rising globally since the early 1990s. Rates for colon and rectal cancers are expected to increase by 90 percent and 124 percent, respectively, by 2030.

One suspected reason behind this trend is increased global consumption of a Westernized diet that consists heavily of red and processed meats, added sugar, and refined grains. Modern day diet is made up of ultra-processed food such as industrial baked sweets, soft drinks, and processed meat. It is associated with an increased risk of colorectal cancer.

One aspect of ultra-processed foods I'm concerned about is how colorful they are. This characteristic is on full display in many delicious foods and treats present during the year-end holidays.

However, many of the colours that make up candy canes, sugar cookies, and even cranberry sauce and roast ham, are synthetic. And there's some evidence that these artificial food dyes may trigger cancer-causing processes in the body.

Part 1

The food industry uses synthetic dyes because they make food look better. The first food dyes were created from coal tar in the late 1800s. Today, they are often synthesized from a chemical derived from petroleum called naphthalene to make a final product called an azo dye.

Food manufacturers prefer synthetic dyes over natural dyes like beet extract because they are cheaper, brighter, and last longer. While manufacturers have developed hundreds of synthetic food dyes over the past century, the majority of them are toxic. Only nine are approved for use in food under U.S. Food and Drug Administration policy, and even fewer pass European Union regulations.

What drives colorectal cancer?

DNA damage is the primary driver of colorectal cancer. When DNA damage occurs on cancer driver genes, it can result in a mutation that tells the cell to divide uncontrollably and turn cancerous.

Another driver of colorectal cancer is inflammation. Inflammation occurs when the immune system sends out inflammatory cells to begin healing an injury or capture disease-causing pathogens.

When this inflammation persists over time, it can harm otherwise healthy cells by releasing molecules called free radicals that can damage DNA.

Another type of molecule called cytokines can prolong inflammation and drive increased cell division and cancer development in the gut when there isn't an injury to heal.

Long-term poor dietary habits can lead to a simmering low-grade inflammation that doesn't produce noticeable symptoms, even while inflammatory molecules continue to damage otherwise healthy cells.

Part 2