Tech

ITHACA, N.Y. - Wines and table grapes exist thanks to a genetic exchange so rare that it's only happened twice in nature in the last 6 million years. And since the domestication of the grapevine 8,000 years ago, breeding has continued to be a gamble.

When today's growers cultivate new varieties - trying to produce better-tasting and more disease-resistant grapes - it takes two to four years for breeders to learn whether they have the genetic ingredients for the perfect flower.

Females set fruit, but produce sterile pollen. Males have stamens for pollen, but lack fruit. The perfect flower, however, carries both sex genes and can self-pollinate. These hermaphroditic varieties generally yield bigger and better-tasting berry clusters, and they're the ones researchers use for additional cross-breeding.

Now, Cornell University scientists have worked with the University of California, Davis, to identify the DNA markers that determine grape flower sex. In the process, they also pinpointed the genetic origins of the perfect flower. Their paper, "Multiple Independent Recombinations Led to Hermaphroditism in Grapevine," published April 13 in the Proceedings of the National Academy of Science.

"This is the first genomic evidence that grapevine flower sex has multiple independent origins," said Jason Londo, corresponding author on the paper and a research geneticist in the USDA-Agricultural Research Service (USDA-ARS) Grape Genetics Unit, located at Cornell AgriTech. Londo is also an adjunct associate professor of horticulture in the School of Integrative Plant Science (SIPS), part of the College of Agriculture and Life Sciences.

"This study is important to breeding and production because we designed genetic markers to tell you what exact flower sex signature every vine has," Londo said, "so breeders can choose to keep only the combinations they want for the future."

Today, most cultivated grapevines are hermaphroditic, whereas all wild members of the Vitis genus have only male or female flowers. As breeders try to incorporate disease-resistance genes from wild species into new breeding lines, the ability to screen seedlings for flower sex has become increasingly important. And since grape sex can't be determined from seeds alone, breeders spend a lot of time and resources raising vines, only to discard them several years down the line upon learning they're single-sex varieties.

In the study, the team examined the DNA sequences of hundreds of wild and domesticated grapevine genomes to identify the unique sex-determining regions for male, female and hermaphroditic species. They traced the existing hermaphroditic DNA back to two separate recombination events, occurring somewhere between 6 million and 8,000 years ago.

Londo theorizes that ancient viticulturists stumbled upon these high yielding vines and collected seeds or cuttings for their own needs - freezing the hermaphroditic flower trait in domesticated grapevines that are used today.

Many wine grapes can be traced back to either the first or second event gene pool. Cultivars such as cabernet franc, cabernet sauvignon, merlot and Thompson seedless are all from the first gene pool. The pinot family, sauvignon blanc and gamay noir originate from the second gene pool.

What makes chardonnay and riesling unique is that they carry genes from both events. Londo said this indicates that ancient viticulturalists crossed grapes between the two gene pools, which created some of today's most important cultivars.

Documenting the genetic markers for identifying male, female and perfect flower types will ultimately help speed cultivar development and reduce the costs of breeding programs.

"The more grape DNA markers are identified, the more breeders can advance the wine and grape industry," said Bruce Reisch, co-author and professor in both the Horticulture and the Plant Breeding and Genetics sections of SIPS. "Modern genetic sequencing technologies and multi-institutional research collaborations are key to making better grapes available to growers."

Due to climate change, the average global temperature will rise in the coming decades. This should also significantly increase the number of so-called cooling degree days. These measure the number of hours, in which the ambient temperature is above a certain threshold, at which a building must be cooled to keep the indoor temperature at a comfortable level. The rising values may lead to an increased installation of AC systems in households. This could lead to a higher energy demand for cooling buildings, which is already expected to increase due to climate change and population growth.

Nip-and-tuck race between heating and cooling

To get a better understanding of how massive this increase will be in Switzerland, Empa researchers analyzed the heating and cooling requirements of the NEST research and innovation building. "By including ambient temperatures, we were able to make a projection of the future thermal energy demand of buildings based on the climate scenarios for Switzerland. In addition to climate change, we also took population growth and the increasing use of AC devices into account," explains Robin Mutschler, postdoc at Empa's Urban Energy Systems lab.

The results forecast a significant increase in the demand for cooling energy: In an extreme scenario where the whole of Switzerland would rely on air conditioning, almost as much energy would be needed for cooling as for heating by the middle of the century. In figures, this corresponds to about 20 terawatt hours (TWh) per year for heating and 17.5 TWh for cooling. The required cooling energy was calculated without regard to the technology. If this is provided by reversing a heat pump process, e.g. with COP 3 for cooling, the electricity demand for 17.5 TWh cooling energy is about 5.8 TWh.

The heating demand of the residential units of NEST is comparable to a modern apartment building. These figures are therefore representative if is assumed that the average Swiss building is comparable to the NEST building. When this will be the case depends on the renovation rate. However, even in a more moderate scenario, the cooling demand in Switzerland will increase significantly. The researchers assume an additional energy demand of five TWh per year in this scenario.

Strong impact on the Swiss energy system

The energy demand of Swiss buildings today accounts for around 40 percent of the total energy demand. The main part of this is used for heating. This will probably remain this way until at least the middle of the 21st century, while the energy demand for cooling buildings is expected to increase significantly. If thermal energy is provided by heat pumps that can also cool, this potentially has a strong impact on the overall energy system and especially on electricity as an energy carrier.

It is assumed that only a small amount of Swiss households currently own an AC unit or system. However, the number of houses with heat pumps is growing. The Empa researchers estimate that the number of households with cooling systems could rise to over 50 percent due to the increase in cooling degree days. This could lead to significant demand peaks on hot days. An additional five TWh of energy demand for cooling would be equivalent to about two percent of today's electricity demand if cooling is provided by heat pumps. In the more extreme scenario, the electricity demand for cooling could even approach ten percent of today's total demand. However, this will not be evenly distributed throughout the year, but will correlate with hot periods, which can lead to demand peaks. On a positive note, cooling demand is relatively well matched by electricity production from photovoltaic systems. The impact of cooling residential buildings will be significantly higher compared to office buildings, as they account for about two-thirds of the building area.

Based on these findings, it is evident to the researchers that these developments must be taken into account when constructing new buildings and that the possibilities of passive cooling must be fully exploited. "Building architecture should no longer focus only on optimizing heat losses, especially in winter, but also on reducing heat gains in summer," says Mutschler. This could be achieved, for example, through urban planning measures for climate adaptation at district level, the implementation of programs for heat reduction, or the reduction of glazing in buildings. "Moreover, it is crucial that policymakers also address this development and investigate ways to best meet the increasing cooling energy demand while minimizing the impact on the future decarbonized energy system," Mutschler adds. One possible contribution to cooling buildings could come from district cooling systems, which have already been successfully implemented in Switzerland - for example in Geneva. Others are emerging, for instance in Zug.

WASHINGTON, May 18, 2021 -- Wake steering is a strategy employed at wind power plants involving misaligning upstream turbines with the wind direction to deflect wakes away from downstream turbines, which consequently increases the net production of wind power at a plant.

In Journal of Renewable and Sustainable Energy, by AIP Publishing, researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) illustrate how wake steering can increase energy production for a large sampling of commercial land-based U.S. wind power plants.

While some plants showed less potential for wake steering due to unfavorable meteorological conditions or turbine layout, several wind power plants were ideal candidates that could benefit greatly from wake steering control.

Overall, a predicted average annual production gain of 0.8% was found for the set of wind plants investigated. In addition, the researchers found that on wind plants using wake steering, wind turbines could be placed more closely together, increasing the amount of power produced in a given area by nearly 70% while maintaining the same cost of energy generation.

"We were surprised to see that that there was still a large amount of variability in the potential energy improvement from wake steering, even after accounting for the wake losses of different wind plants," said author David Bensason.

Just as umbrellas may cast a shadow, wind turbines create a region of slower, more turbulent air flow downstream of their rotor, which is known as a wake. When these wakes flow into another turbine, they reduce its power production capacity.

The wake steering strategy "steers" these wakes away from turbines by offsetting the angle between the rotor face and the incoming wind direction. This technique sacrifices the power efficiencies of a few turbines in order to increase the performance of the wind power plant as a whole. Wake steering can only increase energy production if there are wake losses to start. Consequently, the benefits of wake steering tend to increase for wind plants with higher wake losses.

The study is one of the first to use the Gauss-Curl-Hybrid wake model, which NREL developed. This model predicts wake behavior in a wind plant more accurately than prior models and captures effects that are more prominent in large-scale plants. The researchers also combined several publicly available databases and tools that together make the investigation of wake steering potential for a large sample of U.S. wind plants possible.

"We hope that this study, which highlighted the potential for wake steering for a large sample of existing commercial wind plants in the U.S., motivates wind plant owners to implement wake steering in their wind plants to increase energy production and contribute to making wind energy a widely deployed affordable clean energy source," said co-author Eric Simley.

What The Study Did: Telemedicine use grew rapidly during the COVID-19 pandemic but there was geographic variation in its use so researchers in this study examined the association of county-level telemedicine use with community factors among people with commercial or Medicare Advantage insurance.

Authors: Ateev Mehrotra, M.D., M.P.H., of Harvard Medical School in Boston, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2021.10330)

Editor's Note: The article includes funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

Eating a Western diet impairs the immune system in the gut in ways that could increase risk of infection and inflammatory bowel disease, according to a study from researchers at Washington University School of Medicine in St. Louis and Cleveland Clinic.

The study, in mice and people, showed that a diet high in sugar and fat causes damage to Paneth cells, immune cells in the gut that help keep inflammation in check. When Paneth cells aren't functioning properly, the gut immune system is excessively prone to inflammation, putting people at risk of inflammatory bowel disease and undermining effective control of disease-causing microbes. The findings, published May 18 in Cell Host & Microbe, open up new approaches to regulating gut immunity by restoring normal Paneth cell function.

"Inflammatory bowel disease has historically been a problem primarily in Western countries such as the U.S., but it's becoming more common globally as more and more people adopt Western lifestyles," said lead author Ta-Chiang Liu, MD, PhD, an associate professor of pathology & immunology at Washington University. "Our research showed that long-term consumption of a Western-style diet high in fat and sugar impairs the function of immune cells in the gut in ways that could promote inflammatory bowel disease or increase the risk of intestinal infections."

Paneth cell impairment is a key feature of inflammatory bowel disease. For example, people with Crohn's disease, a kind of inflammatory bowel disease characterized by abdominal pain, diarrhea, anemia and fatigue, often have Paneth cells that have stopped working.

Liu and senior author Thaddeus Stappenbeck, MD, PhD, chair of the Department of Inflammation and Immunity at Cleveland Clinic, set out to find the cause of Paneth cell dysfunction in people. They analyzed a database containing demographic and clinical data on 400 people, including an assessment of each person's Paneth cells. The researchers found that high body mass index (BMI) was associated with Paneth cells that looked abnormal and unhealthy under a microscope. The higher a person's BMI, the worse his or her Paneth cells looked. The association held for healthy adults and people with Crohn's disease.

To better understand this connection, the researchers studied two strains of mice that are genetically predisposed to obesity. Such mice chronically overeat because they carry mutations that prevent them from feeling full even when fed a regular diet. To the researchers' surprise, the obese mice had Paneth cells that looked normal.

In people, obesity is frequently the result of eating a diet rich in fat and sugar. So the scientists fed normal mice a diet in which 40% of the calories came from fat or sugar, similar to the typical Western diet. After two months on this chow, the mice had become obese and their Paneth cells looked decidedly abnormal.

"Obesity wasn't the problem per se," Liu said. "Eating too much of a healthy diet didn't affect the Paneth cells. It was the high-fat, high-sugar diet that was the problem."

The Paneth cells returned to normal when the mice were put back on a healthy mouse diet for four weeks. Whether people who habitually eat a Western diet can improve their gut immunity by changing their diet remains to be seen, Liu said.

"This was a short-term experiment, just eight weeks," Liu said. "In people, obesity doesn't occur overnight or even in eight weeks. People have a suboptimal lifestyle for 20, 30 years before they become obese. It's possible that if you have Western diet for so long, you cross a point of no return and your Paneth cells don't recover even if you change your diet. We'd need to do more research before we can say whether this process is reversible in people."

Further experiments showed that a molecule known as deoxycholic acid, a secondary bile acid formed as a byproduct of the metabolism of gut bacteria, forms the link between a Western diet and Paneth cell dysfunction. The bile acid increases the activity of two immune molecules -- farnesoid X receptor and type 1 interferon -- that inhibit Paneth cell function.

Liu and colleagues now are investigating whether fat or sugar plays the primary role in impairing Paneth cells. They also have begun studying ways to restore normal Paneth cell function and improve gut immunity by targeting the bile acid or the two immune molecules.

Australian scientists have compared an ancient Greek technique of memorising data to an even older technique from Aboriginal culture, using students in a rural medical school.

The study found that students using a technique called memory palace in which students memorised facts by placinthem into a memory blueprint of the childhood home, allowing them to revisit certain rooms to recapture that data. Another group of students were taught a technique developed by Australian Aboriginal people over more than 50,000 years of living in a custodial relationship with the Australian land.

The students who used the Aboriginal method of remembering had a significantly improved retention of facts compared to the control and the "memory palace" group.

The study led by Dr David Reser, from the Monash University School of Rural Health and Dr Tyson Yunkaporta, from Deakin University's NIKERI Institute, has just been published in PLOS One.

Medical students, and doctors, need to retain large amounts of information from anatomy to diseases and medications.

Because one of the main stressors for medical students is the amount of information they have to rote learn, we decided to see if we can teach them alternate, and better, ways to memorise data," Dr Reser said.

The memory palace technique dates back to the early Greeks and was further utilised by Jesuit priests. Handwritten books were scarce and valuable, and one reading would have to last a person's lifetime, so ways to remember the contents were developed.

In Aboriginal culture, which relies on oral history, important facts like navigation, food sources, tool use and inter and intra tribal political relationships are important for survival. Aboriginal methods of memorising also used the idea of attaching facts to the landscape, but with added stories which describe the facts and the placement to facilitate recall.

Working with Dr Yunkaporta, formerly at the Monash School of Rural Health, the research team randomly divided 76 medical students attending Monash's Churchill Campus, in rural Victoria, into three groups. The students were given 30 minutes of training in the memory palace, Aboriginal techniques, or were in a control group who watched a video rather than undergo training. The students were then asked to memorize 20 common butterfly names (to dissociate from medical curriculum).

They were then tested on their recalls at 10 minutes and then 30 minutes after using their assigned techniques to memorize the list.

The researchers found the students who used the Aboriginal technique for remembering ie a narrative plus locations from around the campus were almost three times more likely to correctly remember the entire list than they were prior to training (odds ratio: 2.8). The students using the memory palace technique were about twice as likely to get a perfect score after training (2.1), while the control group improved by about 50% (1.5) over their pre-training performance.

Importantly a qualitative survey found the students using the Aboriginal technique found it more enjoyable, "both as a way to remember facts but also as a way to learn more about Aboriginal culture," Dr Reser said.

Dr Reser said the Monash School of Rural Health is considering incorporating these memory tools into the medical curriculum once teaching returns to a post-COVID normal. "This year we hope to offer this to students as a way to not only facilitate their learning but to reduce the stress associated with a course that requires a lot of rote learning,"he said.

The research team, led by Academician GUO Guangcan from University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, collaborating with LI Bo from Shangrao Normal University and CHEN Jingling from Nankai University, achieved the masking of optical quantum information. The researchers concealed quantum information into non-local quantum entangled states. The study was published in the journal Physical Review Letters.

Quantum information masking as one of the new information processing protocol transfers quantum information from a single quantum carrier to the quantum entangled state between multiple carriers avoiding the information decode from single quantum carrier. Not all the kind of quantum states can achieve masking, but the variety of that helps people to select.

The quantum information masking can be used in a wide situation, not only in actual quantum information tasks such as quantum secret sharing but also the further understanding in the conservation of quantum information.

In this research, the team realized quantum information masking for the first time based on the linear optics research platform.

Compared with the theoretical value, the fidelity of the entangled state can be 97.7%, meaning that the secure transmission of simple images can be complete for the three-party quantum secret sharing based on quantum information masking.

This study has great significance for theoretical research and practical application of secure quantum communication. Based on it, the feasibility of quantum information masking as a brand-new quantum information processing protocol is improved.

Urban megaprojects tend to be the antithesis of good urban planning. They have a negative impact on local water systems, deprive local communities of water-related human rights, and their funders and sponsors have little accountability for their impact.

These are the findings of the University of Adelaide's Dr Scott Hawken from the School of Architecture and Built Environment who led a review of the impact of urban megaprojects on water justice in South East Asia.

"Urban megaprojects have severe implications for environmental processes," said Dr Hawken.

"They have a major impact on hydrological systems and during all phases of development affect water security and human rights.

"As well as interrupting urban water flows and waste removal, they cause biodiversity degradation and loss of arable landscapes, and increase pollution and change the flood regimes of rivers."

The study, published in the journal Cities, focussed on the Phu My Hung project in Vietnam, the Amarapura project in Myanmar and Boeung Kak Lake in Cambodia, and is the result of Dr Hawken's engagement with recent calls from the United Nations for greater accountability in megaprojects globally.

Urban megaprojects have been a key mode of development in Southeast Asia since the 1980s. Between three and 14 per cent of GDP is invested in these kind of developments in SE Asia and eight per cent globally. They can include urban regeneration schemes, transport and energy infrastructure, industrial corridors, city clusters, new towns, innovation districts, science and technology parks and sports infrastructure.

"The projects we looked at are typical of most major cities in Southeast Asia in that they are located near coasts or major rivers which exposes people who live there to extreme weather events such as floods and erosion," said Dr Hawken.

"At every stage of these projects there needs to be a more systematic approach to sustainability especially when assessing their impact on water security. The community needs to be more involved and funders and sponsors need to be more accountable for the impact.

"Wealthier residents tend to benefit from these urban enclaves while they dramatically displace and disrupt existing economics and social relations. Poor socio-economic urban residents are disproportionately adversely affected."

Megaprojects are often publicly positioned as economic benefactors for cities with governments and developers framing them as delivering wealth and new technologies to urban regions.

"Considering the prominence of this development model, it is unacceptable that there is so little information or recourse when these projects do not deliver on their promises," said Dr Hawken.

"Existing urban issues are rarely solved by these projects so a new approach is needed to better engage with communities and their socio-ecological relationships with natural water systems. Considering where they are built such projects also expose cities to future climate related disasters such as sea-level rise and flooding.

"Our findings and recommendations are relevant to cities around the world which are in semi-aquatic, delta environments and sensitive water catchment areas.

"Developers need to be accountable for such projects now and into the future."

Graphene nanoribbons (GNRs), narrow strips of single-layer graphene, have interesting physical, electrical, thermal, and optical properties because of the interplay between their crystal and electronic structures. These novel characteristics have pushed them to the forefront in the search for ways to advance next-generation nanotechnologies.

While bottom-up fabrication techniques now allow the synthesis of a broad range of graphene nanoribbons that feature well-defined edge geometries, widths, and heteroatom incorporations, the question of whether or not structural disorder is present in these atomically precise GNRs, and to what extent, is still subject to debate. The answer to this riddle is of critical importance to any potential applications or resulting devices.

Collaboration between Oleg Yazyev's Chair of Computational Condensed Matter Physics theory group at EPFL and Roman Fasel's experimental nanotech@surfaces Laboratory at Empa has produced two papers that look at this issue in armchair-edged and zigzag-edged graphene nano ribbons.

"Imperfections are known to play an important role in shaping a number of functionalities in crystals," said Michele Pizzochero, formerly a PhD student in the lab of Oleg Yazyev at EPFL and now a post-doctoral researcher at Harvard University. "In these papers, we have revealed ubiquitous "bite" defects, namely missing groups of carbon atoms, as the main type of structural disorder in graphene nanoribbons fabricated via on-surface synthesis. Although we found that "bite" defects degrade the performance of electronic devices based on graphene nanoribbons, in some cases these imperfections may offer exciting opportunities for spintronic applications thanks to their peculiar magnetic properties."

Armchair graphene nanoribbons

The paper "Quantum electronic transport across "bite" defects in graphene nanoribbons," recently published in 2D Materials, specifically looks at 9-atom wide armchair graphene nanoribbons (9-AGNRs). The mechanical robustness, long-term stability under ambient conditions, easy transferability onto target substrates, scalability of fabrication, and suitable band-gap width of these GNRs has made them one of the most promising candidates for integration as active channels in field-effect transistors (FETs). Indeed, among the graphene-based electronic devices realized so far, 9-AGNR-FETs display the highest performance.

While the detrimental role of defects on electronic devices is well known, Schottky barriers, potential energy barriers for electrons formed at metal-semiconductor junctions, both limit the performance of current GNR-FETs and prevent experimental characterization of the impact of defects on device performance. In the 2D Materials paper, the researchers combine experimental and theoretical approaches to investigate defects in bottom-up AGNRs.

Scanning-tunnelling and atomic-force microscopies first allowed the researchers to identify missing benzene rings at the edges as a very common defect in 9-AGNR and to estimate both the density and spatial distribution of these imperfections, which they have dubbed "bite" defects. They quantified the density and found that they have a strong tendency to aggregate. The researchers then used first-principles calculations to explore the effect of such defects on quantum charge transport, finding that these imperfections significantly disrupt it at the band edges by reducing conductance.

These theoretical findings are then generalized to wider nanoribbons in a systematic manner, allowing the researchers to establish practical guidelines for minimizing the detrimental role of these defects on charge transport, an instrumental step towards the realization of novel carbon-based electronic devices.

Zigzag graphene nanoribbons

In the paper "Edge disorder in bottom-up zigzag graphene nanoribbons: implications for magnetism and quantum electronic transport," recently published in The Journal of Physical Chemistry Letters, the same team of researchers combines scanning probe microscopy experiments and first-principles calculations to examine structural disorder and its effect on magnetism and electronic transport in so-called bottom-up zigzag GNRs (ZGNRs).

ZGNRs are unique because of their unconventional metal-free magnetic order that, according to predictions, is preserved up to room temperature. They possess magnetic moments that are coupled ferromagnetically along the edge and antiferromagnetically across it and it has been shown that the electronic and magnetic structures can be modulated to a large extent by, for example, charge doping, electric fields, lattice deformations, or defect engineering. The combination of tunable magnetic correlations, sizable band gap width and weak spin?orbit interactions has made these GNRs promising candidates for spin logic operations. The study specifically looks at six-carbon zigzag lines wide graphene nanoribbons (6-ZGNRs), the only width of ZGNRs that has been achieved with a bottom-up approach so far.

Again using scanning-tunnelling and atomic-force microscopies, the researchers first identify the presence of ubiquitous carbon vacancy defects located at the edges of the nanoribbons and then resolve their atomic structure. Their results indicate that each vacancy comprises a missing m-xylene unit, that is, another "bite" defect, which, as with those seen in AGNRs, comes from the scission of the C?C bond that occurs during the cyclodehydrogenation process of the reaction. Researchers estimate the density of "bite" defects in the 6-ZGNRs to be larger than that of the equivalent defects in bottom-up AGNRs.

The effect of these bite defects on the electronic structure and quantum transport properties of 6-ZGNRs is again examined theoretically. They find that the introduction of the defect, similarly to AGNRs, causes a significant disruption of the conductance. Furthermore, in this nanostructure, these unintentional defects induce sublattice and spin imbalance, causing a local magnetic moment. This, in turn, gives rise to spin-polarized charge transport that makes defective zigzag nanoribbons optimally suited for applications in all-carbon logic spintronics in the ultimate limit of scalability.

A comparison between ZGNRs and AGNRs of equal width shows that transport across the former is less sensitive to the introduction of both single and multiple defects than in the latter. Overall, the research provides global picture of the impact of these ubiquitous "bite" defects on the low-energy electronic structure of bottom-up graphene nanoribbons. Future research might focus on the investigation of other types of point defects experimentally observed at the edges of such nanoribbons, the researchers said.

With the rise of the digital age, the amount of WiFi sources to transmit information wirelessly between devices has grown exponentially. This results in the widespread use of the 2.4GHz radio frequency that WiFi uses, with excess signals available to be tapped for alternative uses.

To harness this under-utilised source of energy, a research team from the National University of Singapore (NUS) and Japan's Tohoku University (TU) has developed a technology that uses tiny smart devices known as spin-torque oscillators (STOs) to harvest and convert wireless radio frequencies into energy to power small electronics. In their study, the researchers had successfully harvested energy using WiFi-band signals to power a light-emitting diode (LED) wirelessly, and without using any battery.

"We are surrounded by WiFi signals, but when we are not using them to access the Internet, they are inactive, and this is a huge waste. Our latest result is a step towards turning readily-available 2.4GHz radio waves into a green source of energy, hence reducing the need for batteries to power electronics that we use regularly. In this way, small electric gadgets and sensors can be powered wirelessly by using radio frequency waves as part of the Internet of Things. With the advent of smart homes and cities, our work could give rise to energy-efficient applications in communication, computing, and neuromorphic systems," said Professor Yang Hyunsoo from the NUS Department of Electrical and Computer Engineering, who spearheaded the project.

The research was carried out in collaboration with the research team of Professor Guo Yong Xin, who is also from the NUS Department of Electrical and Computer Engineering, as well as Professor Shunsuke Fukami and his team from TU. The results were published in Nature Communications on 18 May 2021.

Converting WiFi signals into usable energy

Spin-torque oscillators are a class of emerging devices that generate microwaves, and have applications in wireless communication systems. However, the application of STOs is hindered due to a low output power and broad linewidth.

While mutual synchronisation of multiple STOs is a way to overcome this problem, current schemes, such as short-range magnetic coupling between multiple STOs, have spatial restrictions. On the other hand, long-range electrical synchronisation using vortex oscillators is limited in frequency responses of only a few hundred MHz. It also requires dedicated current sources for the individual STOs, which can complicate the overall on-chip implementation.

To overcome the spatial and low frequency limitations, the research team came up with an array in which eight STOs are connected in series. Using this array, the 2.4 GHz electromagnetic radio waves that WiFi uses was converted into a direct voltage signal, which was then transmitted to a capacitor to light up a 1.6-volt LED. When the capacitor was charged for five seconds, it was able to light up the same LED for one minute after the wireless power was switched off.

In their study, the researchers also highlighted the importance of electrical topology for designing on-chip STO systems, and compared the series design with the parallel one. They found that the parallel configuration is more useful for wireless transmission due to better time-domain stability, spectral noise behaviour, and control over impedance mismatch. On the other hand, series connections have an advantage for energy harvesting due to the additive effect of the diode-voltage from STOs.

Commenting on the significance of their results, Dr Raghav Sharma, the first author of the paper, shared, "Aside from coming up with an STO array for wireless transmission and energy harvesting, our work also demonstrated control over the synchronising state of coupled STOs using injection locking from an external radio-frequency source. These results are important for prospective applications of synchronised STOs, such as fast-speed neuromorphic computing."

Next steps

To enhance the energy harvesting ability of their technology, the researchers are looking to increase the number of STOs in the array they had designed. In addition, they are planning to test their energy harvesters for wirelessly charging other useful electronic devices and sensors.

The research team also hopes to work with industry partners to explore the development of on-chip STOs for self-sustained smart systems, which can open up possibilities for wireless charging and wireless signal detection systems.

A new study may have uncovered why wall lizards have become the most successful reptile in the Mediterranean region. The results reveal how drastic changes in sea levels and climate 6 million years ago affected species formation in the area. The researchers believe they can now explain why the lizards became so diverse and widespread, something that has puzzled biologists since the 19th century. The study is published in Nature Communications.

The evolution of wall lizards offers clues on how major events in the Mediterranean climate and geology millions of years ago affected how species formed or became extinct, and also paved the way for biodiversity.

Wall lizards date back around 20 million years. However, species formation seems to have picked up speed shortly after the Messinian Salinity Crisis 6 million years ago. During this period the Mediterranean almost dried out, only to rapidly fill up with water again as the Strait of Gibraltar opened.

"Our results show that the dramatic changes at the time probably contributed to the emergence of new species. They also shed light on why biodiversity looks the way it does today", says Tobias Uller, professor of evolutionary ecology at Lund University who led the international study.

The research indicates that species isolated from each other for millions of years occasionally have found each other and shared genes. By comparing DNA sequences from 26 species and 8 subspecies, the team successfully mapped the major features of the evolution of wall lizards. This included what parts of the genome were transferred from other species through hybridization.

One example is the wall lizards found in Ibiza. Half of their genes come from wall lizards that today live on the Iberian Peninsula, and the other half from those found in the Balkans and among the Greek islands. The species in Ibiza thus originated as a hybrid, which provided evolution with great opportunities to combine old genes in new ways.

According to the researchers, this probably explains why species like the Ibiza wall lizard are so strikingly variable in colouration: despite close relationships and geographic proximity, they are a single colour on one island, but a variety of colours on the next, for example.

"We believe that hybridization has fuelled evolution, promoting biodiversity and extraordinary adaptability among certain species", concludes Tobias Uller.

Scientists have developed a mathematical model that predicts how the number and effects of bacterial mutations leading to drug resistance will influence the success of antibiotic treatments.

Their model, described today in the journal eLife, provides new insights on the emergence of drug resistance in clinical settings and hints at how to design novel treatment strategies that help avoid this resistance occurring.

Antibiotic resistance is a significant public health challenge, caused by changes in bacterial cells that allow them to survive drugs that are designed to kill them. Resistance often occurs through new mutations in bacteria that arise during the treatment of an infection. Understanding how this resistance emerges and spreads through bacterial populations is important to preventing treatment failure.

"Mathematical models are a crucial tool for exploring the outcome of drug treatment and assessing the risk of the evolution of antibiotic resistance," explains first author Claudia Igler, Postdoctoral Researcher at ETH Zurich, Switzerland. "These models usually consider a single mutation, which leads to full drug resistance, but multiple mutations that increase antibiotic resistance in bacteria can occur. So there are some mutations that lead to a high level of resistance individually, and some that provide a small level of resistance individually but can accumulate to provide high-level resistance."

For their study, Igler and her team gathered experimental evidence that drug resistance evolution follows these two patterns: a single mutation and multiple mutations. They then used this information to create an informed modelling framework which predicts the evolution of 'single-step' resistance versus 'multi-step' resistance in bacteria cells in response to drug type, pharmacokinetics (how the drug decays in the body), and treatment strategies. They investigated how the risk of treatment failure changes when taking into account multiple mutational steps, instead of a single one, and how many different bacterial lineages (bacteria with different mutations) would emerge during the treatment period.

Using their model, the team found that the evolution of drug resistance is limited substantially if more than two mutations are required by the bacteria. Additionally, the extent of this limitation, and therefore the probability of treatment failure, depends strongly on the combination of the drug type and the route of administration, such as orally or via IV infusion.

"Our work provides a crucial step in understanding the emergence of antibiotic resistance in clinically relevant treatment settings," says senior author Roland Regoes, Group Leader at ETH Zurich. "Together, our findings highlight the importance of measuring the level of antibiotic resistance granted by single mutations to help inform effective antimicrobial treatment strategies."

Researchers of Peter the Great St.Petersburg Polytechnic University (SPbPU) developed a new approach to determine the best electrode materials composition for Solid-state lithium-ion batteries. The results of the study were published in the first quartile journal Nanomaterials, MDPI. The Russian Science Foundation supports the project.

The development of miniature devices such as sensors and Internet of things (IoT) devices requires establishing small and complex power supplies with a high energy density. According to experts, traditional technologies for lithium-ion battery production reach their limits. It is difficult to reduce the size and control the shape of the power source any further in the required nano and micron dimensions. Meanwhile, micro and nanoelectronic technologies, such as Atomic Layer Deposition, can assist in producing miniature solid-state lithium-ion batteries with high specific energy.

Studying the new nanoscale materials for electrodes of lithium-ion batteries, the research group of St. Petersburg Polytechnic University developed a method to determine the electrochemical capacity of each component of the "nickel-cobalt oxide" system. Transition metal oxides have a high capacity and relatively low costs, which is required to develop lithium-ion batteries. In the investigation of thin films obtained by atomic layer deposition (ALD) were used as anode materials and demonstrated a high charge capacity at high current densities.

"We obtained nickel-cobalt oxide materials in the wide range of compositions from nickel oxide to cobalt oxide and proposed a method to determine the contribution of the capacity of each of the electrochemically active components of the charge/discharge process. This multipurpose technique can be used to determine the best materials' compositions for lithium-ion batteries" notes Dr. Maximov of High School of Materials Physics and Technologies, Institute of Mechanical Engineering, Materials and Transport SPbPU.

In the future, the scientists plan to use their developments to create improved cathodes and solid electrolytes to produce a prototype of thin-film solid-state lithium-ion batteries.

Analysing the forces at work behind the obstructions that cause heart attacks is crucial for identifying patients at risk of these events, says a study published today in eLife.

The findings suggest that bringing such biomechanical analyses into clinical practice could allow cardiologists to predict a future heart attack in patients by simulating the distribution of stress within diseased heart vessels.

A myocardial infarction, commonly known as a heart attack, occurs when the supply of blood to the heart is blocked by a blood clot or similar obstruction. A build-up of fatty deposits (lipids) over time forms plaques in the heart's arteries. If the plaque ruptures, it can form a blood clot that blocks the arteries and causes a heart attack.

Previous studies have identified some characteristics of these lipid deposits which put them at high risk of rupturing. These studies involved examining the obstructed coronary arteries of patients who died from infarction, or using special imaging techniques to view these vessels from the inside. But the exact mechanism of plaque rupture, and especially the forces at work behind it, are still not known.

"This may limit our ability to recognise and treat those high-risk lipid deposits before they cause a myocardial infarction," says Andrea Milzi, Doctor of Medicine at the Department of Cardiology, University Hospital of the RWTH Aachen, Germany, and a co-first author of the study alongside Enrico Domenico Lemma (Karlsruhe Institute of Technology, Karlsruhe, Germany) and Rosalia Dettori (RWTH Aachen). "We wanted to analyse the forces that cause plaque rupture, taking into account a single patient heart vessel with all of its characteristics considered at once. This is important, because it may potentially allow the in-depth analysis of vessels which - even due to a combination of factors - are particularly at risk of developing a myocardial infarction."

Milzi and the team began by gathering high-quality images of coronary plaques in 20 patients with type 2 diabetes and either stable coronary artery disease or acute myocardial infarction. "These analyses are particularly important in high-risk patients with type 2 diabetes," says Nikolaus Marx, Head of the Department of Cardiology at the University Hospital of the RWTH Aachen. The images were taken using optical coherence tomography (OCT), an established intravascular imaging technique which, due to its extremely high resolution, can depict cardiac structures with high resolution.

The team carried out OCT on all 20 patients prior to coronary intervention at the Department of Cardiology, University Hospital of the RWTH Aachen. Based on these images, they then generated patient-specific reconstructions of coronary plaques, which they used as a basis to analyse stress concentration as a possible predictor of plaque rupture.

Analysing the biomechanics of these reconstructions allowed them to predict the presence of plaque rupture, as their OCT images showed significantly greater stress concentrations in ruptured plaques compared to non-ruptured plaques. Additionally, by highlighting stress concentrations within the arteries, their analyses also indicated the exact place where a rupture was likely to happen. "In other words, the force exerted on the superficial layers of the plaque plays a pivotal role in plaque rupture, which in turn causes myocardial infarction," says Sebastian Reith, Consultant at the Department of Cardiology, University Hospital of the RWTH Aachen, and a co-senior author of the study.

"Our pilot study is hypothesis-generating and shows that OCT-based analysis of the forces within the vessel wall is a feasible tool to carry out patient-specific assessment of biomechanics in coronary lesions," adds co-senior author Mathias Burgmaier, Consultant at the Department of Cardiology, University Hospital of the RWTH Aachen. "Including such analyses in clinical practice might eventually improve the treatment of coronary artery disease, allowing cardiologists to predict a future myocardial infarction by looking - among other factors - at the stress distributions in diseased vessels. However, this approach first needs to be automated and confirmed in larger, prospective studies before we can carry it into clinical practice."

A research group led by Prof. LUO Tianzhi from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, collaborating with Prof. WANG Zhengzhi's team from Wuhan University, explored the natural defenses in the tail spike of mantis shrimps and left chela of hermit crabs.

They revealed the chemical gradients from nanometer to centimeter and the correlation between micro-structure and mechanical properties. Also, they confirmed toughening mechanism and optimized structure principles through a 3D printing technique and finite-element analysis. The results were published in ACS Applied Materials & Interfaces and Acta Biomaterialia, respectively.

Nature endows many animals with hierarchical structural "tools" for defense and attack, which also inspires the researchers and engineers to design and fabricate bio-mimetic materials and structures with superior properties.

In these studies, the researchers found that the exoskeleton of mantis shrimps embraces four different layers, in which there are distinctive micro-structure and chemical characteristics.

The local mechanical properties of these layers correlate well with the micro-structures and chemical compositions, a combination of which effectively restricts the crack propagation while maximizing the release of strain energy during deformation. As a result, the whole toughness and strength is improved.

Besides, the researchers fabricated many bio-mimetic structures of the tail spike by 3D printing, and verified that the combination of Bounligand structure with radially oriented parallel sheets greatly improves the toughness and strength during compression tests. This case guides high-performance composites fabrication towards a new path.

In the similar way, the left chela of hermit crabs is also naturally endowed with the optimized mechanical properties in against the compression and attack, which provides new ideas to sharpen the design in anti-attack structures.