Diamonds are a chip's best friend

Highly precise optical absorption spectra of diamond reveal ultra-fine splitting
Illustration Credit: KyotoU/Nobuko Naka

Besides being "a girl's best friend," diamonds have broad industrial applications, such as in solid-state electronics. New technologies aim to produce high-purity synthetic crystals that become excellent semiconductors when doped with impurities as electron donors or acceptors of other elements.

These extra electrons -- or holes -- do not participate in atomic bonding but sometimes bind to excitons -- quasi-particles consisting of an electron and an electron hole -- in semiconductors and other condensed matter. Doping may cause physical changes, but how the exciton complex -- a bound state of two positively-charged holes and one negatively-charged electron -- manifests in diamonds doped with boron has remained unconfirmed. Two conflicting interpretations exist of the exciton's structure.

An international team of researchers led by Kyoto University has now determined the magnitude of the spin-orbit interaction in acceptor-bound excitons in a semiconductor.

"We broke through the energy resolution limit of conventional luminescence measurements by directly observing the fine structure of bound excitons in boron-doped blue diamond, using optical absorption," says team leader Nobuko Naka of KyotoU's Graduate School of Science.

Walleye struggle with changes to timing of spring thaw

Within a few days of ice-off, when a lakes’ frozen lid has melted away, walleye begin laying eggs and fertilizing them. When lakes thaw earlier than usual, the young walleye that hatch in Midwestern waters may have a more difficult time surviving.
Image Credit: Copilot AI

Walleye are one of the most sought-after species in freshwater sportfishing, a delicacy on Midwestern menus and a critically important part of the culture of many Indigenous communities. They are also struggling to survive in the warming waters of the Midwestern United States and Canada.

According to a new study published in the journal Limnology and Oceanography Letters, part of the problem is that walleye are creatures of habit, and the seasons — especially winter — are changing so fast that this iconic species of freshwater fish can’t keep up.

The timing of walleye spawning — when the fish mate and lay their eggs — has historically been tied to the thawing of frozen lakes each spring, says the study’s lead author, Martha Barta, a research technician at the University of Wisconsin–Madison. Now, due to our changing climate, walleye have been “unable to keep up with increasingly early and more variable ice-off dates,” Barta says.

Within a few days of ice-off, when a lakes’ frozen lid has melted away, walleye begin laying eggs and fertilizing them. In a normal year, that timing sets baby fish up for success once they hatch. But, Barta says, “climate change is interrupting the historical pairing of ice-off and walleye spawning, and that threatens the persistence of walleye populations across the Upper Midwest.”

You may be breathing in more tiny nanoparticles from your gas stove than from car exhaust

Brandon Boor, a Purdue associate professor of civil engineering, studies how everyday activities like cooking on a gas stove can affect indoor air quality.
Photo Credit: Kelsey Lefever / Purdue University

Cooking on your gas stove can emit more nano-sized particles into the air than vehicles that run on gas or diesel, possibly increasing your risk of developing asthma or other respiratory illnesses, a new Purdue University study has found.

“Combustion remains a source of air pollution across the world, both indoors and outdoors. We found that cooking on your gas stove produces large amounts of small nanoparticles that get into your respiratory system and deposit efficiently,” said Brandon Boor, an associate professor in Purdue’s Lyles School of Civil Engineering, who led this research.

Based on these findings, the researchers would encourage turning on a kitchen exhaust fan while cooking on a gas stove. 

The study, published in the journal PNAS Nexus, focused on tiny airborne nanoparticles that are only 1-3 nanometers in diameter, which is just the right size for reaching certain parts of the respiratory system and spreading to other organs. 

Recent studies have found that children who live in homes with gas stoves are more likely to develop asthma. But not much is known about how particles smaller than 3 nanometers, called nanocluster aerosol, grow and spread indoors because they’re very difficult to measure.

“These super tiny nanoparticles are so small that you’re not able to see them. They’re not like dust particles that you would see floating in the air,” Boor said. “After observing such high concentrations of nanocluster aerosol during gas cooking, we can’t ignore these nano-sized particles anymore.”

Glacier melting destroys important climate data archive

Corbassière glacier at Grand Combin in the canton of Valais
Photo Credit: Peter Meyer-Herzog

As part of the Ice Memory initiative, PSI researchers, with colleagues from the University of Fribourg and Ca’ Foscari University of Venice as well as the Institute of Polar Sciences of the Italian National Research Council (CNR), analyzed ice cores drilled in 2018 and 2020 from the Corbassière glacier at Grand Combin in the canton of Valais. A comparison of the two sets of ice cores published in Nature Geoscience shows: Global warming has made at least this glacier unusable as a climate archive.

Reliable information about the past climate and air pollution can no longer be obtained from the Corbassière glacier in the Grand Combin massif, because alpine glacier melting is progressing more rapidly than previously assumed. This sobering conclusion was reached by researchers led by Margit Schwikowski, head of the Laboratory for Environmental Chemistry at PSI, and Carla Huber, PhD student and first author of the study, when they compared the signatures of particulate matter locked in the annual layers of the ice. Glaciers are invaluable for climate research. The climatic conditions and atmospheric compositions of past ages are preserved in their ice. Therefore, they can serve, in much the same way as tree rings and ocean sediments, as a so-called climate archive for research.

Normally, the amount of particle-bound trace substances in ice fluctuates with the seasons. SubstPeter Meyer-Herzogances such as ammonium, nitrate, and sulfate come from the air and are deposited on the glacier through snowfall: The concentrations are high in summer and low in winter, because lower amounts of polluted air can rise from the valley when the air is cold. The 2018 ice core, which was drilled from depths of up to 14 meters during a preliminary study and contains deposits dating back to 2011, shows these fluctuations as expected. But the core from 2020, from a depth of up to 18 metres – drilled under the leadership of PSI researcher Theo Jenk – shows those fluctuations only for the upper three or four annual layers. Deeper in the ice – that is, farther in the past – the curve indicating the concentration of trace substances becomes noticeably flatter, and the total amount is lower. Schwikowski’s team reports on this in the current issue of the journal Nature Geoscience.

Vital Seagrasses in Gulf of Mexico Are Retreating Amid Rapid Sea Level Rise

Marine Science professor Ken Dunton (left) and doctoral student Kyle Capistrant-Fossa (right) in the Gulf of Mexico.
Photo Credit: Courtesy of University of Texas at Austin

The Gulf of Mexico is experiencing sea level rise two to three times as fast as the global average due to a combination of warmer waters and wind circulation patterns. Now, a newly released long-term study from marine scientists at The University of Texas at Austin has found rising sea levels can be linked to a loss of valuable seagrass habitats in Texas.

The paper appears in Communications Earth & Environment.

Seagrasses are recognized globally as a foundation species that play a key role in supporting fisheries and mitigating climate change, efficiently storing substantial amounts of carbon. Meadows occur in shallow waters, and the species are dependent on light for photosynthesis and growth. The researchers are the first to find that sea level rise is yet another human impact that is responsible for the worldwide decline in seagrasses.

Ken Dunton, a professor in UT’s Marine Science Institute, and Kyle Capistrant-Fossa, a doctoral student, made the discovery while examining a 30-year database of observations that Dunton had collected at his study site in the Laguna Madre next to Padre Island. Capistrant-Fossa found that the slow loss of vegetation at the site during the past decade was also coincident with an unprecedented rise in sea level. They also found that seagrasses were disappearing from their historical deeper water ranges throughout the Upper Laguna Madre. But they noted that these losses could be compensated by plant expansion into areas that were once too shallow.

Bariatric surgery provides long-term blood glucose control, type 2 diabetes remission

Photo Credit: Fernando Zhiminaicela

NIH-supported study shows long-term benefits of surgery compared to medication and lifestyle change.

People with type 2 diabetes who underwent bariatric surgery achieved better long-term blood glucose control compared to people who received medical management plus lifestyle interventions, according to a new study supported by the National Institutes of Health. The participants who underwent bariatric surgery, also called metabolic or weight-loss surgery, were also more likely to stop needing diabetes medications and had higher rates of diabetes remission up to 12 years post-surgery. Results of the study were published in JAMA and funded by the National institute of Diabetes, Digestive and Kidney Diseases (NIDDK), part of NIH.

“While there are many factors involved, and not all of them are completely understood, bariatric surgery typically results in greater weight loss that effects a person’s metabolic hormones, which improves the body’s response to insulin and ability to maintain healthy blood glucose levels,” said Dr. Jean Lawrence, NIDDK project scientist. “These results show that people with overweight or obesity and type 2 diabetes can make long-term, improvements in their health and change the trajectory of their diabetes through surgery.”

Significant glacial retreat in West Antarctica began in 1940s

Thwaites Glacier from above.
Photo Credit: Ted Scambos.

A new study, involving researchers from British Antarctic Survey, has found that significant thinning and retreat of the vast Thwaites Glacier began in the 1940s.

Accelerating ice loss has been observed since the 1970s, but its unclear when this significant melting initiated – until now. These results coincide with previous work that found the Pine Island Glacier also began its retreat at this time. Climate models indicate that anthropogenic warming has increasingly driven West Antarctic ice loss since that time, and has prevented these glaciers from recovering.

James Smith, a marine geologist at British Antarctic Survey said:

“Our previous work in 2016 provided the first direct evidence that neighbouring Pine Island Glacier started to retreat in the 1940s. However, that was just one glacier draining into the huge Amundsen Sea Embayment. Now that we know Thwaites glacier also started to retreat around the same time is really significant. It demonstrates that glaciers in this area were responding synchronously to an external climatic driver.”

“A significant implication of our findings is that once an ice sheet retreat is set in motion it can continue for decades, even if what started it gets no worse. It is possible that the changes we see today on Thwaites and Pine Island glaciers – and potentially across the entire Amundsen Sea Embayment – were essentially set in motion in the 1940s.”

Merons realized in synthetic antiferromagnets

Direct observation of antiferromagnetic merons and antimerons
Illustration Credit: Mona Bhukta

Researchers in Germany and Japan have been able for the first time to identify collective topological spin structures called merons in layered synthetic antiferromagnets

The electronic devices we use on a day-to-day basis are powered by electrical currents. This is the case with our living room lights, washing machines, and televisions, to name but a few examples. Data processing in computers also relies on information provided by tiny charge carriers called electrons. The field of spintronics, however, employs a different concept. Instead of the charge of electrons, the spintronic approach is to exploit their magnetic moment, in other words, their spin, to store and process information – aiming to make the computers of the future more compact, fast, and sustainable. One way of processing information based on this approach is to use the magnetic vortices called skyrmions or, alternatively, their still little understood and rarer cousins called 'merons'. Both are collective topological structures formed of numerous individual spins. Merons have to date only been observed in natural antiferromagnets, where they are difficult to both analyze and manipulate.

New quantum entangled material could pave way for ultrathin quantum technologies

Artistic illustration depicts heavy-fermion Kondo matter in a monolayer material.
Illustration Credit: Adolfo Fumega/Aalto University

Researchers reveal the microscopic nature of the quantum entangled state of a new monolayer van der Waals material

Two-dimensional quantum materials provide a unique platform for new quantum technologies, because they offer the flexibility of combining different monolayers featuring radically distinct quantum states. Different two-dimensional materials can provide building blocks with features like superconductivity, magnetism, and topological matter. But so far, creating a monolayer of heavy-fermion Kondo matter – a state of matter dominated by quantum entanglement – has eluded scientists. Now, researchers at Aalto University have shown that it’s theoretically possible for heavy-fermion Kondo matter to appear in a monolayer material, and they’ve described the microscopic interactions that produces its unconventional behavior. These findings were published in Nano Letters.

“Heavy-fermion materials are promising candidates to discover unconventional topological superconductivity, a potential building block for quantum computers robust to noise,” says Adolfo Fumega, the first author of the paper and a post-doctoral researcher at Aalto University.

These materials can feature two phases: one analogous to a conventional magnet, and one where the state of the system is dominated by quantum entanglement, known as the heavy-fermion Kondo state. At the transition between the magnetic phase and the heavy-fermion state, macroscopic quantum fluctuations appear, leading to exotic states of matter including unconventional superconducting phases.

Out of the desert, a quantum powerhouse rises

Postdoctoral researcher Caitlin McCowan inspects pieces of silicon at the atomic level. She uses a scanning tunneling microscope to spot imperfections as part of a quantum research project at Sandia National Laboratories.
Photo Credit: Craig Fritz

They knew it was an ambitious goal. But by the time they announced it in 2022, Sandia National Laboratories and The University of New Mexico — two of the state’s largest research institutions — had been working out their strategy for more than a year.

Their goal: transform the state into a global powerhouse in the emerging quantum technology market. Success would mean the arrival of tech companies and startups, jobs and investments — an economic resurgence for the southwestern state.

The plan is picking up steam.

In January, Sandia and UNM created the Quantum New Mexico Institute, a cooperatively run research center headquartered at the university. This marks a major milestone in the comprehensive strategy to advance research, court businesses and train a quantum-ready workforce.

“Our vision is to make New Mexico a destination for quantum companies and scientists across the world,” said Setso Metodi, institute co-director and Sandia manager of quantum computer science.