MIT team reports giant response of semiconductors to light

MIT graduate student Jiahao Dong with the nanoindentation machine used in recent MIT work on the response of semiconductors to light.
Credits: Elizabeth Thomson/Materials Research Laboratory

In an example of the adage “everything old is new again,” MIT engineers report a new discovery in semiconductors, well-known materials that have been the focus of intense study for over 100 years thanks to their many applications in electronic devices.

The team found that these important materials not only become much stiffer in response to light, but the effect is reversible when the light is turned off. The engineers also explain what is happening at the atomic scale, and show how the effect can be tuned by making the materials in a certain way — introducing specific defects — and using different colors and intensities of light.

“We’re excited about these results because we’ve uncovered a new scientific direction in an otherwise very well-trod field. In addition, we found that the phenomenon may be present in many other compounds,” says Rafael Jaramillo, the Thomas Lord Associate Professor of Materials Science and Engineering at MIT and leader of the team.

Says Ju Li, another MIT professor involved in the work, "to see defects having such big effects on elastic response is very surprising, which opens the door to a variety of applications. Computation could help us screen many more such materials." Li is the Battelle Energy Alliance Professor in Nuclear Science and Engineering (NSE) with a joint appointment in the Department of Materials Science and Engineering (DMSE). Both Jaramillo and Li are also affiliated with the Materials Research Laboratory.

Thirdhand Smoke Exposures Surpass Health Risk Guideline Levels

Cigarettes and other tobacco products produce chemicals that linger in indoor environments, putting all other occupants in harm’s way. Credit: Gerd Altmann from Pixabay

Some smells seem to seep into everything they touch. Tobacco smoke is one of the worst offenders.

Thirdhand smoke refers to residual nicotine and other hazardous chemicals that contaminate the indoor environment after smoking. Think of the lingering smell you’ve probably encountered when handling the clothes of a person who smokes a pack a day, or when checking into a tidy but cigarette-friendly hotel room.

Scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) first identified thirdhand smoke as a potential health hazard a decade ago. Their newest study develops more quantitative insights into its long-term health risks. They found that concentrations of toxic chemicals lingering in indoor environments where cigarettes have been smoked can exceed risk guidelines from the State of California, meaning that non-smokers can be exposed to health risks by living in contaminated spaces.

The study was published in the journal Environmental Science & Technology. Alongside Berkeley Lab scientists, co-authors on this work include collaborators from UC San Francisco, UC Riverside, and San Diego State University. These teams are members of the California Consortium on Thirdhand Smoke, funded by the Tobacco-Related Disease Research Program, which is managed by the University of California.

Berkeley Lab’s researchers previously discovered that aerosolized nicotine, released during smoking and vaping, adsorbs to indoor surfaces, where it can interact with a compound present in indoor air called nitrous acid (HONO) to form strongly carcinogenic compounds called tobacco-specific nitrosamines (TSNAs). Accumulated nicotine on household surfaces can continuously generate TSNAs, long after smoke clears the room.

Researchers identify a hormone from fat cells that restrains tumor growth in mice

Normal liver tissue (top) and a liver cancer nodule (bottom) containing many dividing cells (labeled in green). Red indicates blood vessels.
Photo credit: Jiandie Lin, Ph.D., University of Michigan Life Sciences Institute

A hormone secreted by fat cells can restrain the growth of liver tumors in mice, according to a new study from the University of Michigan Life Sciences Institute.

The findings offer proof-of-concept for developing therapies against hepatocellular carcinoma, the most common form of liver cancer.

Jiandie Lin and his team use mice as a model to study how molecular and cellular changes are affected by nonalcoholic fatty liver disease, and how these changes consequently lead to the progression of this disease. While it begins as a relatively benign accumulation of fat in the liver, the disorder can develop into nonalcoholic steatohepatitis, or NASH, which increases the risk for liver cancer.

The liver contains scores of different cell types, including various immune cells. Using single-cell RNA sequencing, a technology for probing gene expression of individual cells within complex tissues, Lin and his team previously constructed a liver cell atlas and a blueprint of intercellular signaling in healthy and NASH mouse livers.

For this latest study, scheduled to be published Aug. 15 in Cell Metabolism, the scientists wanted to identify specific molecular changes in the NASH state that disrupt balance and interactions of these cell types, as potential therapeutic targets to reverse the progression from NASH to cancer.

Weird and wonderful world of fungi shaped by evolutionary bursts

Fungi
Scientific Frontline Fungi Gallery
Credit: Heidi-Ann Fourkiller

Scientists at the University of Bristol have discovered that the vast anatomical variety of fungi stems from evolutionary increases in multicellular complexity.

Most people recognize that fungi come in an assortment of shapes and sizes. However, these differences, often referred to as the disparity of a group, had never been analyzed collectively.

Researcher Thomas Smith, who conducted the study while at Bristol’s School of Earth Sciences, explained: “Prior to our analyses, we didn’t know how this variety was distributed across the different types of fungi. Which groups are the most varied when considering all parts of the fungal body plan? Which are the least? How has this variety accumulated and diminished through time? What has shaped these patterns in disparity? These are the questions we sought to answer.”

What they found was that fungal disparity has evolved episodically through time, and that the evolution of multicellularity in different fungi appears to open the door for greater morphological variety. They saw increases in disparity associated with both the emergence of the first multicellular fungi, and then the evolution of complex fruiting bodies such as mushrooms and saddles in dikaryotic species. These fungi are defined by the inclusion of a dikaryon, a cell with two separate nuclei, in their life cycles.

Underwater Snow Gives Clues About Europa’s Icy Shell

An illustration of NASA’s Europa Clipper spacecraft flying by Jupiter’s moon Europa. The spacecraft, which is planned to launch in 2024, will carry an ice-penetrating radar instrument developed by scientists at the University of Texas Institute for Geophysics.
Credit: NASA/JPL-Caltech.

Below Europa’s thick icy crust is a massive, global ocean where the snow floats upwards onto inverted ice peaks and submerged ravines. The bizarre underwater snow is known to occur below ice shelves on Earth, but a new study shows that the same is likely true for Jupiter’s moon, where it may play a role in building its ice shell.

The underwater snow is much purer than other kinds of ice, which means Europa’s ice shell could be much less salty than previously thought. That’s important for mission scientists preparing NASA’s Europa Clipper spacecraft, which will use radar to peek beneath the ice shell to see if Europa’s ocean could be hospitable to life. The new information will be critical because salt trapped in the ice can affect what and how deep the radar will see into the ice shell, so being able to predict what the ice is made of will help scientists make sense of the data.

The study, published in the August edition of the journal Astrobiology, was led by The University of Texas at Austin, which is also leading the development of Europa Clipper’s ice penetrating radar instrument. Knowing what kind of ice Europa’s shell is made of will also help decipher the salinity and habitability of its ocean.

“When we’re exploring Europa, we’re interested in the salinity and composition of the ocean, because that’s one of the things that will govern its potential habitability or even the type of life that might live there,” said the study’s lead author Natalie Wolfenbarger, a graduate student researcher at the University of Texas Institute for Geophysics (UTIG) in the UT Jackson School of Geosciences.

Northernmost Neolithic Fortifications Found

The group of archaeologists in the project under the state order of the Ministry of Science and Education of Russia is headed by Victor Borzunov.
Photo from Victor Borzunov's personal archive

To establish and characterize in detail the livelihood strategies of the primitive population of the Trans-Urals and Western Siberia of the Stone, Bronze and Early Iron eras. This is the task archeologists at Ural Federal University have set for themselves within the interdisciplinary project "Regional Identity of Russia: Comparative Historical and Philological Studies". Scientists have found that during the New Stone Age, the aborigines of the forest belt of the north of the Eurasian continent continued to maintain an appropriate economy and could not rise to the level of a fundamentally new production economy.

Scientists conduct research in this area under the state order of the Ministry of Science and Education of Russia (№ FEUZ-2020-0056) and under a grant from the Russian Science Foundation. The group in the project is headed by Victor Borzunov, a Senior Researcher of the Fundamental Research Archaeological Laboratory of UrFU.

The work, which continued many years of research by the laboratory personnel, is carried out in three main directions. The first is the study of neolithization of the societies of the Ural-West Siberian Region. In other words, the peculiarities of ancient groups of 6th-4th millennia B.C. to the advanced innovations of the Old World, such as productive economy, more or less strong sedentary life, large stationary settlements, ceramic production, defense architecture, fundamentally different house-building, stone processing, new social structures etc.

The second direction is the analysis of the origin and development of the ancient defensive architecture of the north of Eurasia in the 7th millennium B.C. - 3rd century A.D., its place and role in the general system of origin and development of fortified settlements, proto-cities and cities of the Old World.

Road signs for immune defense cells

The mechanism of MHC I assembly, epitope editing and quality control within the peptide loading complex (PLC). The fully assembled PLC machinery of antigen processing is formed by the antigen transport complex TAP1/2, the chaperones calreticulin, ERp57, and tapasin, and the heterodimeric MHC I (heavy and light chain in teal and green, respectively).
Credit: Christoph Thomas & Robert Tampé

How do killer T cells recognize cells in the body that have been infected by viruses? Matter foreign to the body is presented on the surface of these cells as antigens that act as a kind of road sign. A network of accessory proteins – the chaperones – ensure that this sign retains its stability over time. Researchers at Goethe University have now reached a comprehensive understanding of this essential cellular quality control process. Their account of the structural and mechanistic basis of chaperone networks has just appeared in the prestigious science journal Nature Communications. These new findings could be harbingers of progress in areas such as vaccine development.

Organisms are constantly invaded by pathogens such as viruses. Our immune system swings into action to combat these pathogens immediately. The innate non-specific immune response is triggered first, and the adaptive or acquired immune response follows. In this second defense reaction, specialized cytotoxic T lymphocytes known as killer T cells destroy cells in the body that have been infected and thus prevent damage from spreading. Humans possess a repertoire of some 20 million T cell clones with varying specificity to counter the multitude of infectious agents that exist. But how do the killer T cells know where danger is coming from? How do they recognize that something is wrong inside a cell in which viruses are lurking? They can't just have a quick peek inside.

Transplant hope for minority communities as researchers alter donor kidney blood type

Credit Sasin Tipchai via Pixabay

Researchers at the University of Cambridge have successfully altered the blood type on three deceased donor kidneys in a ground-breaking discovery that could have major implications for kidney patients. The project, which is funded by charity Kidney Research UK, could increase the supply of kidneys available for transplant, particularly within ethnic minority groups who are less likely to be a match for the majority of donated kidneys.

Professor Mike Nicholson and PhD student Serena MacMillan used a normothermic perfusion machine (a device which connects with a human kidney to pass oxygenated blood through the organ to better preserve it for future use) to flush blood infused with an enzyme through the deceased kidney. The enzyme acted like “molecular scissors” to remove the blood type markers that line the blood vessels of the kidney resulting in the organ being converted to the most common O type.

A kidney from someone with an A blood type cannot be transplanted to someone with a B blood type, nor the other way around. But changing the blood type to the universal O will allow more transplants to take place as O can be used for people with any blood group.

MacMillan said: “Our confidence was really boosted after we applied the enzyme to a piece of human kidney tissue and saw very quickly that the antigens were removed. After this, we knew that the process is feasible, and we just had to scale up the project to apply the enzyme to full-size human kidneys. By taking B type human kidneys and pumping the enzyme through the organ using our normothermic prefusion machine, we saw in a matter of just a few hours that we had converted a B type kidney into an O type. It’s very exciting to think about how this could potentially impact so many lives.”

Climate change could lead to larger algal blooms

algal blooms
Credit: Hardebeck Media from Pixabay

Griffith-led research has revealed that both the decreases in wind and the higher temperatures predicted with climate change can cause bigger algal blooms in the future.

Published in Water Research, the study found that a 20% decrease in wind speed will result in algal blooms of the freshwater cyanobacteria Microcystis that are almost one and a half times the current size.

“The impact this decrease in wind will have on algal blooms is more than six times that of a 2°C increase in air temperature associated with climate change,” said lead author Mohammad Hassan Ranjbar, a PhD candidate at the Australian Rivers Institute.

“Harmful algal blooms of the freshwater cyanobacteria Microcystis are a global problem and are expected to intensify with climate change, however, to date the impact of atmospheric stilling, the decrease in near-surface wind speed, has not been considered.

“Our research is the first to demonstrate that atmospheric stilling along with increasing air temperature can favor blooms of these buoyant, colony-forming cyanobacteria.”

$148K project to digitize thousands of rare, native plant specimens

UH Mānoa student Chase Kane prepares a plant specimen to be photographed and digitally accessible to researchers around the world.
Credit: University of Hawaiʻi

A University of Hawaiʻi at Mānoa project to digitize tens of thousands of plant specimens from Hawaiʻi, across the vast Pacific Ocean and around the world, received a major boost by the National Science Foundation. The three-year, $148,882 grant will help School of Life Sciences Assistant Professor Karolina Heyduk and her team to digitize and catalog more than 55,000 plant specimens, many of which are extinct, to preserve and improve access worldwide to one of the oldest collections of Pacific plants.

“Our goal for the project is to get all 55,000 plant specimens digitized for the whole world to see and facilitate research on Hawaiian plants across the globe,” Heyduk said. “The herbarium represents a really unique collection that is used by both researchers and also used in classes and teaching on campus.”

Hawaiʻi has some of the greatest biodiversity in the world and there are approximately 1,400 plant taxa (species, subspecies and varieties) native to the state, according to the Hawaiʻi Department of Land and Natural Resources. Nearly 90% are found nowhere else in the world. However, more than 100 plant taxa have gone extinct, and more than 200 have 50 or fewer individuals remaining in the wild.

UH Mānoa’s Joseph F. Rock Herbarium was established in 1908 and is home to many rare and endemic plant specimens from Hawaiʻi and other Pacific islands, some of which have since become extinct. The herbarium serves as a crucial record of biodiversity and is an invaluable resource for species that are extinct, threatened or endangered.