Investigating Magnetic Excitation-induced Spin Current in Chromium Trihalides

A general formula that can calculate the spin current induced by oscillating magnetic fields in magnetic materials and aid our understanding of novel spintronics functionality has been developed by researchers from Tokyo Tech and Chiba University. The formula predicts large spin currents arising from a hitherto unknown contribution in antiferromagnetic chromium trihalides, opening doors to material design for novel spintronics devices.

An ingenious approach toward developing low-power, high-speed, and high-density memory devices is based on spintronics, an emerging frontier in technology that harnesses a degree of freedom of electrons known as "spin." Put simply, electrons, along with their negative charge, possess a "spin" whose orientation can be controlled using magnetic fields. This is particularly relevant for magnetic insulators, in which the electrons cannot move around, but the "spin" remains controllable. In these materials, the magnetic excitations can give rise to a "spin current," which forms the basis of spintronics.

Scientists have been looking for efficient methods to generate the spin current. The "photogalvanic effect," a phenomenon characterized by the generation of dc current from light illumination, is particularly useful in this regard. Studies have found that a "photogalvanic" spin current can be generated similarly using the magnetic fields in electromagnetic waves. However, we currently lack candidate materials and a general mathematical formulation for exploring this phenomenon.

Soil Temperature Can Predict Pest Spread in Crops

Corn earworm attacks a corn plant.
Photo Credit: Anders Huseth, NC State University.

A new study from North Carolina State University shows soil temperature can be used to effectively monitor and predict the spread of the corn earworm (Helicoverpa zea), an important pest that ravages corn, cotton, soybeans, peppers, tomatoes and other vegetable crops. The ability to better monitor the pest and make predictions about where it will appear could help farmers control the pest more effectively, which would reduce the financial and environmental impacts of pesticide use.

The researchers combined historical soil temperature data with long-term corn earworm monitoring data and information on how the pest survives cold conditions in a lab setting to better understand “overwintering success,” or how well the pest can survive underground during the colder winter months.

Greater overwintering success can expand the areas where the pest can live and thrive, the researchers say, as the pest can migrate long distances. Generally, greater overwintering success in more northern latitudes increases the potential for crop damage from this pest further north. Climate change also affects overwintering success.

“There is a preconceived notion that pests have little overwintering success north of 40 degrees latitude,” said Douglas Lawton, a former NC State postdoctoral researcher and co-corresponding author of a paper that describes the research, published in Proceedings of the National Academy of Sciences. “That may have been true in the 1930s, but now we have more data-guided evidence to ask and answer the question, ‘Where can this species actually overwinter?’”

Finding antigens that trigger specific immune cells

The microwells in each experiment, seen in this micrograph by the black outlines, were loaded with spherical beads (the large grey circle in each well), and T cells (the smaller circles adhering to some of the beads).
Image credit: Yinnian Feng

Their approach, which mimics the physical forces exerted by immune cells as they crawl over host cells, could help scientists develop more effective cancer immunotherapies.

A cell’s secrets can be divulged by its surface, decorated with tens to hundreds of thousands of molecules that help immune cells determine friend from foe. Some of those protruding molecules are antigens that trigger the immune system to attack, but it can be difficult for scientists to identify those antigens, which often vary across individuals, in the molecular forest.

A team of Stanford scientists led by Polly Fordyce, an Institute Scholar at Sarafan ChEM-H, has developed a new method to faster and more accurately predict which antigens will lead to a strong immune response. Their approach, which was reported in Nature Methods on Sept. 5, could help scientists develop more effective cancer immunotherapies.

T cells, a class of immune cells, crawl along and squish past other cells as they patrol the body, using T cell receptors to molecularly read peptides, or short pieces of proteins – which are cradled within larger proteins called major histocompatibility complexes (pMHCs) that project from cell surfaces. Healthy host cells display an array of pMHCs that do not trigger an immune response, but once T cells recognize disease-indicating peptides, they become activated to find and kill cells bearing these foreign signatures. Understanding how T cells sensitively distinguish these antigenic peptides from host peptides to avoid mistakenly killing host cells has long been a mystery.

Archaeologists discover monumental evidence of prehistoric hunting across Arabian desert

Distribution of kite structures in the Levant and in northern Arabia. White: previously documented kites. Red: kites recorded by EAMENA.
Credit: EAMENA

Archaeologists at the University of Oxford’s School of Archaeology have used satellite imagery to identify and map over 350 monumental hunting structures known as ‘kites’ across northern Saudi Arabia and southern Iraq – most of which had never been previously documented.

Led by Dr Michael Fradley, a team of researchers in the Endangered Archaeology in the Middle East and North Africa (EAMENA) project used a range of open-source satellite imagery to carefully study the region around the eastern Nafud desert, an area little studied in the past. The surprising results, published in the journal The Holocene, have the potential to change our understanding of prehistoric connections and climate change across the Middle East.

Termed kites by early aircraft pilots, these structures consist of low stone walls making up a head enclosure and a number of guiding walls, sometimes kilometers long. They are believed to have been used to guide game such as gazelles into an area where they could be captured or killed. There is evidence that these structures may date back as far as 8,000 BCE in the Neolithic period.

Kites cannot be observed easily from the ground, however the advent of commercial satellite imagery and platforms such as Google Earth have enabled recent discoveries of new distributions. While these structures were already well-known from eastern Jordan and adjoining areas in southern Syria, these latest results take the known distribution over 400km further east across northern Saudi Arabia, with some also identified in southern Iraq for the first time.

Scientists Found Luminescence in Unique Dielectric Material

Hafnium dioxide was studied in the Ural Federal University Research Center Nanomaterials and Nanotechnologies.
Photo credit: Ilya Safarov

Scientists from the UrFU studied the luminescent properties of hafnium dioxide, a material with high dielectric permittivity. This compound is used in the micro- and nanoelectronics industry. Physicists found that due to the presence of exotic quasiparticles in their electronic structure, the compound exhibits intense luminescence at extremely low temperatures. The discovery will help in the creation of future electronic devices, such as lasers, optical sensors, or biomedical sensors. The results are presented in the Journal of Luminescence.

"We studied the temperature effect on the luminescence properties of the nanostructured hafnium dioxide powder. When we cooled the compound to 40 K (-233°C), we recorded ultraviolet luminescence in the compound, which became brighter as the sample cooled. We were able to build a model that describes at what point in the compound additional luminescence is formed, how the intensity of the luminescence changes and is characterized. This model can be useful in the development of highly sensitive sensors in modern optoelectronic devices or compact biosensors for visualization of various processes," notes Artyom Shilov, Junior Researcher at the Nanotech Research Center at UrFU Ural Interregional Research and Scientific Center.

A Novel Approach to Creating Tailored Odors and Fragrances Using Machine Learning

Can we use machine learning methods to predict the sensing data of odor mixtures and design new smells? A new study by researchers from Tokyo Tech does just that. The novel method is bound to have applications in the food, health, beauty, and wellness industries, where odors and fragrances are of keen interest.

The sense of smell is one of the basic senses of animal species. It is critical to finding food, realizing attraction, and sensing danger. Humans detect smells, or odorants, with olfactory receptors expressed in olfactory nerve cells. These olfactory impressions of odorants on nerve cells are associated with their molecular features and physicochemical properties. This makes it possible to tailor odors to create an intended odor impression. Current methods only predict olfactory impressions from the physicochemical features of odorants. But that method cannot predict the sensing data, which is indispensable for creating smells.

To tackle this issue, scientists from Tokyo Institute of Technology (Tokyo Tech) have employed the innovative strategy of solving the inverse problem. Instead of predicting the smell from molecular data, this method predicts molecular features based on the odor impression. This is achieved using standard mass spectrum data and machine learning (ML) models. "We used a machine-learning-based odor predictive model that we had previously developed to obtain the odor impression. Then we predicted the mass spectrum from odor impression inversely based on the previously developed forward model," explains Professor Takamichi Nakamoto, the leader of the research effort by Tokyo Tech. The findings have been published in PLoS One.

Researchers devise tunable conducting edge

In their experiments, the researchers stacked monolayer WTe2 with Cr2Ge2Te6, or
CGT. Credit: Shi lab/UC Riverside

A research team led by a physicist at the University of California, Riverside, has demonstrated a new magnetized state in a monolayer of tungsten ditelluride, or WTe2, a new quantum material. Called a magnetized or ferromagnetic quantum spin Hall insulator, this material of one-atom thickness has an insulating interior but a conducting edge, which has important implications for controlling electron flow in nanodevices.

In a typical conductor, electrical current flows evenly everywhere. Insulators, on the other hand, do not readily conduct electricity. Ordinarily, monolayer WTe2 is a special insulator with a conducting edge; magnetizing bestows upon it more unusual properties.

“We stacked monolayer WTe2 with an insulating ferromagnet of several atomic layer thickness — of Cr2Ge2Te6, or simply CGT — and found that the WTe2 had developed ferromagnetism with a conducting edge,” said Jing Shi, a distinguished professor of physics and astronomy at UCR, who led the study. “The edge flow of the electrons is unidirectional and can be made to switch directions with the use of an external magnetic field.”

Shi explained that when only the edge conducts electricity, the size of the interior of the material is inconsequential, allowing electronic devices that use such materials to be made smaller — indeed, nearly as small as the conducting edge. Because devices using this material would consume less power and dissipate less energy, they could be made more energy efficient. Batteries using this technology, for example, would last longer.

Bronchodilators don’t improve smoking-related respiratory symptoms in people without COPD

Credit: Ralph from Pixabay

Researchers supported by the National Institutes of Health have found that dual bronchodilators – long-lasting inhalers that relax the airways and make it easier to breathe – do little to help people who do not have chronic obstructive pulmonary disease (COPD), but who do have respiratory symptoms and a history of smoking.

COPD, a lung disease that obstructs the airways and leads to coughing, wheezing, and shortness of breath, affects about 15 million Americans. However, millions of others who smoke or used to smoke and have some symptoms of COPD have also been prescribed bronchodilators.

“We’ve assumed these medications worked in patients who don’t meet lung function criteria for COPD, but we never checked,” said MeiLan K. Han, M.D., a principal investigator and first author of the study. “We now know these existing medications don’t work for these patients.”

The findings of the study, which was funded by the National Heart, Lung, and Blood Institute (NHLBI), were published in the New England Journal of Medicine and simultaneously presented at the European Respiratory Society International Congress.

According to scientists, the implications are significant. First, they show the importance of diagnosing lung conditions through spirometry, a lung function test Han noted is underutilized in clinical practice. Second, they show the need for new, effective therapies for patients without COPD.

New treatment could result in more donor lungs

Sandra Lindstedt, Snejana Hyllén, and Leif Pierre
Credit: Lund University

A large number of lungs donated cannot be used for transplantation. Researchers at Lund University in Sweden and Skåne University Hospital have conducted an animal study bringing hope that more donor lungs could be used in the future. Researchers have launched a pilot study to investigate whether the treatment will have the same positive effects on human beings.

About 190 organs are donated in Sweden every year. Due to injuries to the lungs, only about 30 percent of them can be used for transplantation. Adding to that, the mortality rate is high: about half of the patients pass away within five years of transplant.

” The results from our study indicate that a certain treatment can help us use a larger part of a donor lung, and that there is an improved outcome during the first two days after surgery”, says Sandra Lindstedt, senior consultant in thoracic surgery at Skåne University Hospital and adjunct professor at Lund University.

In their study on pigs, the researchers investigated the effects of reducing the levels of cytokines in lungs. Cytokines are small proteins that are produced by specific cells of the immune system.

High plant diversity is often found in the smallest of areas

This meadow in Romania is one of the most species-rich regions on earth - in 2009, a research team found 98 plant species here.
Credit: Jürgen Dengler

It might sound weird, but it's true: the steppes of Eastern Europe are home to a similar number of plant species as the regions of the Amazon rainforest. However, this is only apparent when species are counted in small sampling areas, rather than hectares of land. An international team of researchers led by the Martin Luther University Halle-Wittenberg (MLU) and the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig has now shown how much estimates of plant diversity change when the sampling area ranges from a few square meters to hectares. Their results have been published in the journal "Nature Communications" and could be utilized in new, more tailored nature conservation concepts.

In their study, the team analyzed a dataset of around 170,000 vegetation plots from all of the Earth’s climate zones. The data included information on all of the plant species found at a location and the coordinates of the respective area under study. The data was taken from the globally unique vegetation database "sPlot", which is located at iDiv.

"Most studies on global biodiversity are conducted on a relatively large scale, for example at a state or provincial scale. We wanted to find out how much results differ when smaller areas are examined," says Professor Helge Bruelheide from MLU. The team used artificial intelligence to investigate, among other things, the relationship between the number of plant species and the size of the area under study.