MLU physicists solve mystery of two-dimensional quasicrystal formation from metal oxides

A substructure consisting of rings of different sizes embeds itself seamlessly into a hexagonal structure
 Photo Credit: Dr. Stefan Förster

The structure of two-dimensional titanium oxide breaks up at high temperatures by adding barium; instead of regular hexagons, rings of four, seven and ten atoms are created that order periodically. A team at Martin Luther University Halle-Wittenberg (MLU) made this discovery in collaboration with researchers from the Max Planck Institute (MPI) for Microstructure Physics, the Université Grenoble Alpes and the National Institute of Standards and Technology (Gaithersburg, USA), thereby solving the riddle of two-dimensional quasicrystal formation from metal oxides. Their findings have been published in the renowned journal "Nature Communications".

Hexagons are frequently found in nature. The best-known example is honeycomb, but graphene or various metal oxides, such as titanium oxide, also form this structure. "Hexagons are an ideal pattern for periodic arrangements," explains Dr Stefan Förster, researcher in the Surface and Interface Physics group at MLU’s Institute of Physics. "They fit together so perfectly that there are no gaps." In 2013, this group made an astonishing discovery upon depositing an ultrathin layer containing titanium oxide and barium on a platinum substrate and heating it to around 1,000 degrees centigrade in an ultra-high vacuum. The atoms arranged themselves into triangles, squares and rhombuses that group in even larger symmetrical shapes with twelve edges. A structure with 12-fold rotational symmetry was created, instead of the expected 6-fold periodicity. According to Förster, "Quasicrystals were created that have an aperiodic structure. This structure is made of basic atomic clusters that are highly ordered, even if the systematics behind this ordering is difficult for the observer to discern." The physicists from Halle were the first worldwide to demonstrate the formation of two-dimensional quasicrystals in metal oxides. 

Humans have influenced the growth of blue-green algae in lakes for thousands of years

TERENO Monitoring Station on Lake Tiefer See, Germany (weather station, water probes, sediment traps).
Photo Credit: A. Brauer

In recent years, there have been increasing reports of toxic blue-green algae blooms in summer, even in German lakes, caused by climate warming and increased nutrient inputs. But humans have not only had an influence on the development of blue-green algae since modern times, but already since the Bronze Age from about 2,000 B.C. This is the result of a study by researchers from the German Research Centre for Geosciences GFZ and colleagues, published in the scientific journal “Communications Biology”. Since some blue-green algae, also known as cyanobacteria, leave no visible fossil traces in sediments due to their small size, little is known about how they evolved in our lakes during the last centuries and millennia. Using DNA from sediments, the researchers have now been able to decipher for the first time the history of blue-green algae over the last 11,000 years in the sediments of a lake in Mecklenburg.

Artificial photosynthesis uses sunlight to make biodegradable plastic

Fumaric acid synthesis from CO2 using solar energy. Using sunlight to power the photoredox system pyruvic acid and CO2 are converted into fumaric acid, by malate dehydrogenase and fumarase.
Illustration Credit: Yutaka Amao, Osaka Metropolitan University

In recent years, environmental problems caused by global warming have become more apparent due to greenhouse gases such as CO2. In natural photosynthesis, CO2 is not reduced directly, but is bound to organic compounds which are converted to glucose or starch. Mimicking this, artificial photosynthesis could reduce CO2 by combining it into organic compounds to be used as raw materials, which can be converted into durable forms such as plastic.

A research team led by Professor Yutaka Amao from the Research Center for Artificial Photosynthesis and graduate student Mika Takeuchi, from the Osaka Metropolitan University Graduate School of Science, have succeeded in synthesizing fumaric acid from CO2, a raw material for plastics, powered—for the first time—by sunlight. Their findings were published in Sustainable Energy & Fuels.

Probe can measure both cell stiffness and traction, researchers report

Professor Ning Wang, front right, is joined by researchers, from left, Fazlur Rashid, Kshitij Amar and Parth Bhala.
Photo Credit: Fred Zwicky

Scientists have developed a tiny mechanical probe that can measure the inherent stiffness of cells and tissues as well as the internal forces the cells generate and exert on one another. Their new “magnetic microrobot” is the first such probe to be able to quantify both properties, the researchers report, and will aid in understanding cellular processes associated with development and disease.

They detail their findings in the journal Science Robotics.

“Living cells generate forces through protein interactions, and it’s very hard to measure these forces,” said Ning Wang, a professor of mechanical science and engineering at the University of Illinois Urbana-Champaign who led the research. “Most probes can either measure the forces actively generated by the tissues and cells themselves, a trait we call traction, or they can measure their stiffness – but not both.”

To measure cell stiffness, researchers need a relatively rigid probe that can compress, stretch or twist the tissues and quantify how robustly they resist. But to measure the cells’ own internally generated contractions or expansions, a probe must be relatively soft and supple.

Like other scientists, Wang and his colleagues had already developed probes to measure each of these qualities individually. But he said he wanted to develop a more universal probe that could tackle both at once. Such a probe would allow a better understanding of how these properties influence diseases like arteriosclerosis or cancer, or how an embryo develops, for example.

Risk of developing heart failure much higher in rural areas vs. urban

Photo Credit: Tumisu

Large NIH-supported study showed that rural-dwelling Black men are at greatest risk.

Adults living in rural areas of the United States have a 19% higher risk of developing heart failure compared to their urban counterparts, and Black men living in rural areas have an especially higher risk – 34%, according to a large observational study supported by the National Institutes of Health.

The study, one of the first to look at the link between living in rural America and first-time cases of heart failure, underscores the importance of developing more customized approaches to heart failure prevention among rural residents, particularly Black men. The study was largely funded by the National Heart, Lung, and Blood Institute (NHLBI), part of NIH, and the findings, produced in collaboration with Vanderbilt University Medical Center, Nashville, Tennessee, published today in JAMA Cardiology.

“We did not expect to find a difference of this magnitude in heart failure among rural communities compared to urban communities, especially among rural-dwelling Black men,” said Véronique L. Roger, M.D., M.P.H., the study’s corresponding author and a senior investigator with the Epidemiology and Community Health Branch in NHLBI’s Division of Intramural Research. “This study makes it clear that we need tools or interventions specifically designed to prevent heart failure in rural populations, particularly among Black men living in these areas.”

What crocodile DNA reveals about the Ice Age

McGill University postdoctoral fellow José Avila-Cervantes with an American Crocodile (Crocodylus acutus).
Photo Credit: Hans Larsson

What drives crocodile evolution? Is climate a major factor or changes in sea levels? Determined to find answers to these questions, researchers from McGill University discovered that while changing temperatures and rainfall had little impact on the crocodiles’ gene flow over the past three million years, changes to sea levels during the Ice Age had a different effect.

“The American crocodile tolerates huge variations in temperature and rainfall. But about 20,000 years ago – when much of the world's water was frozen, forming the vast ice sheets of the last glacial maximum – sea levels dropped by more than 100 meters. This created a geographical barrier that separated the gene flow of crocodiles in Panama,” says postdoctoral fellow José Avila-Cervantes, working under the supervision of McGill professor Hans Larsson.

Thermal motions and oscillation modes determine the uptake of bacteria in cells

Photo of a membrane bubble with different oscillation modes in the background and experimental scheme in the foreground. Optical tweezers (laser focus in red) bring a thermally fluctuating particle into contact with a membrane bubble (green) until the particle is invaginated into the membrane and taken up.
Graphic Credit: AG Rohrbach

How and with what effort does a bacterium - or a virus - enter a cell and cause an infection? Researchers from Freiburg have now made an important contribution to answering this question: A team led by physicist Prof. Dr. Alexander Rohrbach and his collaborator Dr. Yareni Ayala was able to show how thermal fluctuations of a model bacterium and membrane oscillation modes of a model cell influence the energy with which the model bacteria dock and enter the membrane. The results have just been published in the journal Nature Communications.

Like a sticky piece of candy on a wobbly balloon

“To understand how a bacterium or virus enters a cell, you can imagine a sticky candy on a floppy, wobbly balloon. When a child shakes the rubber balloon around, the candy sticks even tighter to its surface,” said Rohrbach, a professor of -Bio- and Nano-Photonics at the Department of Microsystems Engineering at the University of Freiburg. In his lab, the laser and bio-physicists set up a similar experiment to study the physics of infection processes. The wobbly balloon corresponds to a giant uni-lamellar vesicle (GUV), which serves as a biological model cell. The membrane vesicle is the size of a tiny grain of sand about 20 micrometers in diameter.

COVID-19 conspiracy theories that spread fastest focused on evil, secrecy

Covid 19 Conspiracy Initiated
Image Credit: Dr StClaire

In the early pandemic, conspiracy theories that were shared the most on Twitter highlighted malicious purposes and secretive actions of supposed bad actors behind the crisis, according to an analysis of nearly 400,000 posts. 

In the study, researchers identified commonalities in five of the most popular conspiracy theories: those related to Bill Gates, 5G Networks, vaccinations, QAnon and Agenda 21.

While each theory appears to have a different subject, the social media narratives often overlapped, said Porismita Borah, associate professor in Washington State University’s Murrow College of Communications.

“The conspiracy theories might be using different strategies, but the narratives are often connected,” said Borah, the corresponding author on the study published in the journal New Media and Society. “These theories have a lot in common in that they try to make the stories part of a bigger conspiracy so that if people believe in one conspiracy, then they tend to believe in the other.”

Spinning food processing waste into ‘gold’

Among the waste types analyzed in the study was fried donut waste, a potential candidate for anaerobic fermentation to biogas.
Photo Credit: Pexels

There is money to be made – and potential to reduce greenhouse gas emissions – by finding a second life for the potato peels, fried dough particles, cheese whey and other industrial food-processing waste products that routinely end up in landfills, according to new research.

Scientists have taken the first step at estimating the best large-scale uses for food processing waste, first analyzing its contents and, based on those findings, proposing production opportunities ranging from sustainable fuels, biogas and electricity to useful chemicals and organic fertilizer.

This work is known as valorization, or determining the potential value of something “that is otherwise valueless or even a drain on resources for a company – when you have to spend money to get rid of it,” said Katrina Cornish, senior author of the study and professor of horticulture and crop science and food, agricultural and biological engineering at The Ohio State University. 

“The bioeconomy is becoming much more prevalent as a topic of conversation. In this case, don’t get rid of food waste – make some money from it,” said Cornish, also an Ohio Research Scholar of Bio-Emergent Materials. “Here, we’re putting the base model in place for food manufacturers who are wondering, ‘What can I do with this stuff?’ Our flow chart guides them in a specific direction and prevents them from wasting time trying something we know won’t work.” 

Wolves eliminate deer on Alaskan Island then quickly shift to eating sea otters

Wolves on an Alaskan island caused a deer population to plummet and switched to primarily eating sea otters in just a few years, a finding scientists at Oregon State University and the Alaska Department of Fish and Game believe is the first case of sea otters becoming the primary food source for a land-based predator.

Using methods such as tracking the wolves with GPS collars and analyzing their scat, the researchers found that in 2015 deer were the primary food of the wolves, representing 75% of their diet, while sea otters comprised 25%. By 2017, wolves transitioned to primarily consuming sea otters (57% of their diet) while the frequency of deer declined to 7%. That pattern held through 2020, the end of the study period.

“Sea otters are this famous predator in the near-shore ecosystem and wolves are one of the most famous apex predators in terrestrial systems,” said Taal Levi, an associate professor at Oregon State. “So, it’s pretty surprising that sea otters have become the most important resource feeding wolves. You have top predators feeding on a top predator.”