Tech

In United Nations Sustainable Development Goals, Number 6, addresses the need for access to clean water and sanitation for all. In the worldwide situation, one in three people do not have access to safe drinking water, and two out of five do not have basic hand-washing facilities with soap and water.

Water quality also address to elements dissolved. In the case of fluoride, controlled amount are recommended for protect tooth, e.g. included in toothpaste. Higher levels can cause fluorosis, interfere in tooth enamel formation, correct growth of the bones, and cause crippling deformities of the spine and joints. The incidence of higher concentrations of fluoride in water is higher in rural areas without access to an appropriate water network.

Fluoride in water sources has a geogenic origin instead of anthropogenic, the fluoride concentration in water is determined by geological formations in riverbeds. This, making the fluoride distribution inhomogeneous in the affected regions, finding water sources with safe and unsafe fluoride levels in a close distance. In this case, the fluoride problem could be solved by the local population provided with specific equipment to detect the levels of fluoride in the water and help them to consume safe water.

The equipment cost for fluoride detection is moderate to high, and requires training to be used effectively. This cost is not affordable for the populations in rural areas. For these reasons, the group led by Professor Mutsumi Kimura and Dr. Eugenio Otal from Shinshu University decided to develop an affordable portable equipment which can detect fluoride in a simple manner at low costs, which was recently published in Chemistry - A European Journal. The cost of the developed tech-demo is about US$23, but this price can be reduced to less than the half if production is scaled up. The main cost is related to electronics which is useful for many determinations.

Lanthanide-based metal-organic frameworks (MOFs) offer a good platform for fluoride sensing due to their high affinity by fluoride and intense emission in the visible spectrum. The strong affinity of lanthanides by fluorides transforms the MOFs into the corresponding fluorides, quenching the lanthanide fluorescence. This intensity change can be used to determine the fluoride level in drinking water. Researchers at Shinshu University chose cotton as a substrate for their hydrophilic nature, allowing a good synergy with the porous MOFs and a good control over the amount of liquid sample introduced in the device, making the results reproducible and simplifying the previous systems used.

These innovations are compatible with the group's previous developments, which were published in ACS-Sensors in January of this year. In this previous article, they present the electronic platform based on an Arduino microcontroller, which uses a smartphone as a power source and data acquisition platform. This innovation eliminates the battery and screen, reducing the costs and allowing to transfer the fluoride quantification information directly to the smartphone. The Arduino code used in the device can be also modified according to the requirements of the local population.

To transfer the information, a friendly graphical interface was developed (https://hello.fridie.de/zensorics-app/), it collects the fluoride quantification data, the time, date, and position from the smartphone GPS and transfer them via email, SMS, WhatsApp or any instant messaging service to be included in a safe-water map to be shared with the rest of the local population.

This novel system accomplishes the 4.0 Industry concepts, it is 3D printable, Arduino programmable, open-source, and the device can be produced locally and distributed. All this innovation produced a low-cost device which can be easily operated by non-trained users.

Many times, science and technology are dissociated, but represents two aspects of the same search. Science provides intellectual satisfaction, feeds our curiosity, while technology provides the ability to implement science to achieve comfort, and health, among other things. The research group used both to find new ways to reduce the impact of fluorosis in areas without access to safe water, like synchrotron measurements, to understand the basics phenomena in the material and helped them to design a more sensitive and reliable sensing device. To the device development also contributed, Hideki Tanaka (Shinshu University), Manuela L. Kim (Shinshu University), Juan P. Hinestroza (Cornell University).

The next step is to implement a MOF with even better performance. The actual system uses a UV LED for excitation of the lanthanide MOF and detects the green emission. First author Eugenio Otal states, "we developed a modification of this MOF which can be excited with visible light and the signal will be detected in the Infrared. This innovation could reduce the cost of the electronics and use cheaper and more sensitive detectors in the infrared region of electromagnetic spectra."

Their final goal is to develop a portable device for water quality using the same concepts they used here, making it modular according to the requirements of each region and make their contribution to the Goal 6 of the UN Sustainable Development Goals: Ensure access to water and sanitation for all a reality, with a portable and affordable device.

Eczema, or atopic dermatitis (AD), is sometimes called "the itch that rashes." Often, the itch begins before the rash appears, and, in many cases, the itchiness of the skin condition never really goes away. Approximately 9.6 million children and 16.5 million adults in the U.S. have AD, which can have a serious effect on quality of life for patients. Although much has been learned about the uncomfortable sensation that triggers the desire to scratch, many mysteries remain about chronic itch, making it a challenge to treat. A paper by authors from Brigham and Women's Hospital and Harvard Medical School published in The Proceedings of the National Academy of Sciences, offers new clues about the underlying mechanisms of itch. Findings suggest a key molecular player known as cysteine leukotriene receptor 2 (CysLT2R) that may be a new target for intractable chronic itch.

"In atopic dermatitis, the itching can be horrific and it can aggravate disease," said co-corresponding author K. Frank Austen, MD, a senior physician in the Division of Allergy and Clinical Immunology at the Brigham. Austen is also the AstraZeneca Professor of Respiratory and Inflammatory Diseases, Emeritus, at Harvard Medical School. "We began collaborating for two reasons: one is an interest in science -- I wandered into the study of what is now the cysteine leukotriene pathway decades ago, and I've been pursuing it ever since. The second reason is itch -- understanding its cause and connections to neurons."

Austen and his lab, which focuses on the molecular components that contribute to allergic inflammation, collaborated with Isaac Chiu, PhD, an assistant professor of Immunology at Harvard Medical School. The team also included researchers at the Center for Immunology & Inflammatory Diseases at Massachusetts General Hospital and at the University of Texas at Dallas.

"As a neuro-immunologist, I'm interested in how the nervous system and immune system cross-talk," said Chiu, co-corresponding author of the study. "Itch arises from a subset of neurons, and acute itch may be a protective response to help us remove something that's irritating the skin. However, chronic itch is not protective and can be pathological. The underlying mechanism that activates neurons and causes chronic itch is not well understood and new treatment is needed."

Chiu, Austen and colleagues set out to elucidate the molecular mechanisms that may trigger chronic itch. To do so, they looked for gene activity in dorsal root ganglia (DRG) neurons linked to itch in mice. They found a striking level of CysLT2R, which was uniquely and highly expressed in these specific neurons. They also found expression of this receptor in human DRG neurons. This led the researchers to focus their analysis on the receptor's role in itch signaling. Additional studies showed that activating this receptor induced itching in a mouse model of AD, but not in other mouse models. Mice that lacked CysLT2R showed decrease itching. Collectively, their findings pointed to the receptor's key role in causing itch and potentially contributing to AD.

Lead author Tiphaine Voisin, PhD, carried out many of the preclinical experiments in mouse models of AD during her time in the Chiu lab at HMS.

"The last ten years or so of research in the field of chronic itch have shown the importance and the complexity of the interactions between the immune system and the nervous system," said Voisin. "It was very exciting to explore the contribution of cysteine leukotrienes in these neuro-immune cross-talks leading to itch, including in a mouse model of AD."

Leukotrienes are a class of lipid molecules that originate from white blood cells, such as mast cells, which are involved in allergy and inflammation. Today, the leukotriene inhibitor montelukast, which targets CysLT1R, is used to treat asthma but does not provide relief from itch. No clinically approved inhibitors of CysLT2R currently exist and, while the researchers have seen evidence of the receptors in humans, until an inhibitor is developed and trialed in humans, it will remain an open question as to whether the new target can lead to a therapy for patients.

While Chiu and Austen are eager to see their findings prompt treatment improvements, Austen, who has been pursuing leukotrienes since the 1970s, also notes the importance of making new discoveries and unexpected connections through research.

"I do believe that science is bottom up, not top down," said Austen. "The joy of research is doing it for the pleasure of finding out something you didn't know. The immune system is far more complex than we give it credit for. Understanding the involvement of nerves is an immense step forward -- it's been a missing piece in the study of inflammation. In my view, this is immensely important to connect neuroscience with those of us committed to studying inflammation."

Purely organic room-temperature phosphorescence (RTP) materials have been a hot research topic. Currently, the pure RTP materials have been realized by the introduction of heavy halogen atoms, carbonyls groups or some heteroatoms, hydrogen bonding, H-aggregation, strong intermolecular electronic coupling, molecular packing, host-guest interaction, etc. However, the complicated synthesis and high expenditure are still inevitable in these systems. In addition, their performances in air are not satisfactory and the introduction of halogen atoms is generally necessary. Therefore, a new facile and robust host-guest strategy utilizing only electron-rich materials is a promising alternative for constructing RTP systems.

Very recently, Zheng and Qin et al. developed a series of novel host-guest organic phosphorescence systems, in which N,N,N',N'-tetraphenylbenzidine (TPB) acted as a guest, triphenylphosphine (TPP) or triphenylamine (TPA) served as a host. The maximum phosphorescence efficiency and the longest lifetime could reach 23.6% and 362 ms, respectively. Experimental results and theoretical calculation revealed that the host molecules not only play a vital role in providing a rigid environment and suppressing non-radiative decay of the guest, but also show a synergistic effect to the guest in the photo-physical process through Förster resonance energy transfer (FRET). These new host-guest RTP systems enjoy the integrated merits of commercially available compounds with electron-rich features and low cost, absence of halogen atoms, facile preparation and excellent performances, etc., which shows great potentials in practical applications. Therefore, this work broadens the way for the fabrication of purely organic RTP materials and offers a novel platform for the development of diverse applications.

The directly catalytic oxidation of alkanes has high atomic economy and application value to form corresponding chemical organic products such as alcohols, aldehydes, ketones and carboxylic acid. It is challenging to achieve efficient and selective oxidation of alkane under mild conditions due to the inert C-H bonds of alkanes.

Many researchers have developed a series of supported iron based catalysts to simulate the alkane biological monooxygenase with iron center atoms. However, traditional methods, such as impregnation method, ion exchange method, etc., are difficult to control the dispersion and the deposition position of iron species on the catalyst support.

Generally, iron species can easily replace the H+ of Brønsted acid sites to reduce the number of Brønsted acid sites, and many types of iron species will be formed on other different potential sites of ZSM-5 (Lewis acid sites and defect sites, etc.). The coexistence of multiple active centers on the catalyst is one of the main reasons for the low selectivity.

Atomic layer deposition (ALD) is an advanced thin film technology by single-layer chemisorption and reaction of vapor precursors on the surface of substrates with atomic and molecular control precision.

Recently, Dr. Bin Zhang and colleagues in the Institute of Coal Chemistry, Chinese Academy of Sciences, report a general strategy to selectively deposit high-dispersed Fe species into the micropores of ZSM-5 to prepare FeOx/ZSM-5 catalysts.

The obtained FeOx/ZSM-5 catalysts perform high selectivity of cyclohexanone (92%-97%), and the catalyst activity is significantly higher than those of the iron-based catalysts reported in the literature. Ferrocene (Fe(Cp)2) is used as a precursor for the deposition since its kinetic diameter is smaller than the pore size of ZSM-5. The framework of ZSM-5 and the Brønsted acid sites are intact during ALD, and the Fe species are selectively deposited onto the defect and Lewis acid sites of ZSM-5. The loading, size and surface electronic state of FeOx species can be precisely controlled by merely changing ALD cycles. The Fe content in the FeOx/ZSM-5 catalyst increases linearly with the increase of ALD cycles. Fe-O-Si bonds are dominantly formed over FeOx/ZSM-5 with a low loading of Fe, while FeOx nanoparticles are generated at a high Fe loading. Compared with the FeOx nanoparticles, the Fe-O-Si species performs higher turnover frequency and stability in the oxidation reaction.

Ishikawa, Japan - Any high-performance computing should be able to handle a vast amount of data in a short amount of time -- an important aspect on which entire fields (data science, Big Data) are based. Usually, the first step to managing a large amount of data is to either classify it based on well-defined attributes or--as is typical in machine learning--"cluster" them into groups such that data points in the same group are more similar to one another than to those in another group. However, for an extremely large dataset, which can have trillions of sample points, it is tedious to even group data points into a single cluster without huge memory requirements.

"The problem can be formulated as follows: Suppose we have a clustering tool that can process up to lmax samples. The tool classifies l (input) samples into M(l) groups (as output) based on some attributes. Let the actual number of samples be L and G = M(L) be the total number of attributes we want to find. The problem is that if L is much larger than lmax, we cannot determine G owing to limitations in memory capacity," explains Professor Ryo Maezono from the Japan Advanced Institute of Science and Technology (JAIST), who specializes in computational condensed matter theory.

Interestingly enough, very large sample sizes are common in materials science, where calculations involving atomic substitutions in a crystal structure often involve possibilities ranging in trillions! However, a mathematical theorem called "Polya's theorem," which utilizes the symmetry of the crystal, often simplifies the calculations to a great extent. Unfortunately, Polya's theorem only works for problems with symmetry and is, therefore, of limited scope.

In a recent study published in Advanced Theory and Simulations, a team of scientists led by Prof. Maezono and his colleague, Keishu Utimula, PhD in material science from JAIST (In 2020) and first author of the study, proposed an approach based on statistical randomness to identify G for sample sizes much larger (~ trillion) than lmax. The idea, essentially, is to pick a sample of size l that is much smaller than L, identify M(l) using machine learning "clustering," and repeat the process by varying l. As l increases, the estimated M(l) converges to M(L) or G, provided G is considerably smaller than lmax (which is almost always satisfied). However, this is still a computationally expensive strategy, because it is tricky to know exactly when convergence has been achieved.

To address this issue, the scientists implemented another ingenious strategy: they made use of the "variance", or the degree of spread, in M(l). From simple mathematical reasoning, they showed that the variance of M(l), or V[M(l)], should have a peak for a sample size ~ G. In other words, the sample size corresponding to a maximum in V[M(l)] is approximately G! Furthermore, numerical simulations revealed that the peak variance itself scaled as 0.1 times G, and was thus a good estimate of G.

While the results are yet to be mathematically verified, the technique shows promise of finding applications in high-performance computing and machine learning. "The method described in our work has much wider applicability than Polya's theorem and can, therefore, handle a broader category of problems. Moreover, it only requires a machine learning clustering tool for sorting the data and does not require a large memory or whole sampling. This can make AI recognition technology feasible for larger data sizes even with small-scale recognition tools, which can improve their convenience and availability in the future," comments Prof. Maezono excitedly.

Sometimes, statistics is nothing short of magic, and this study proves that!

Osaka, Japan - Most electronic devices aren't waterproof, much to your irritation if a sprinkler suddenly sprays you while you're talking outside on your cellphone. Some electronics can be made at least water-resistant by, for example, using special glues to fuse outer components together. Flexible electronics are another story. Their sealant materials must be able to bend, yet with current technology it's inevitable that eventually such a sealant will crack or separate from the device—and there goes your water-resistant coating.

Researchers are determined to come up with a solution. Cellulose nanofibers are a proposed polymer coating for flexible electronics. These fibers are made from renewable resources and are environmentally friendly. However, they usually absorb water—commonly thought to be a fatal limitation for imparting water resistance.

In a study recently published in ACS Applied Nano Materials, researchers from Osaka University developed self-healing cellulose nanofibers that slightly disperse in water and act to protect a copper electrode, enabling the electrode to function for an extended period. The researchers' flexible circuit protection mechanism retains electrode function underwater and can undergo hundreds of bending cycles.

"In our initial work, an unprotected copper electrode failed after 5 minutes of dripping water onto it," says Takaaki Kasuga, lead author. "Remarkably, a cellulose nanofiber coating prevented failure over at least a day of the same water challenge."

Why is this? Remember that cellulose fibers don't repel water. Instead, this polymer coating migrates in the electrode in such a way to prevent formation of conductive metal filaments that cause short-circuits. The electrodes even maintained their function after the celluose coating was scratched to simulate bending damage.

"Our results aren't attributable to simple ion-exhange or nanofiber length," explains Masaya Nogi, senior author. "The nanofibers aggregate in water into a protective layer made cohesive by locally acidic conditions and polymer cross-linking."

A more rigorous test of the polymer coating was its performance after 300 cycles of bending underwater over the course of an hour. A conventional polymer coating usually failed, but the cellulose nanofibers continued to power LEDs.

"You'll be able to stretch, bend, and fold electronics with our coating, and they'll still retain their water resistance," says Kasuga. "This is critical for use in applications under extreme conditions where device failure is unacceptable—for example, medical devices used in emergency disaster response."

In preliminary work, even an ultrathin polymer coating thickness of only 1.5 micrometers, and some other polymers, performed similarly to the originally tested setup. They'll become a staple of wearable electronics, and perhaps even medical devices, in the coming years.

Glassy materials play an integral role in the modern world, but inherent brittleness has long been the Achilles' heel that severely limits their usefulness. Due to the disordered amorphous structure of glassy materials, many mysteries remain. These include the fracture mechanisms of traditional glasses, such as silicate glasses, as well as the origin of the intriguing patterned fracture morphologies of metallic glasses.

Cavitation has been widely assumed to be the underlying mechanism governing the fracture of metallic glasses, as well as other glassy systems. Up until now, however, scientists have been unable to directly observe the cavitation behavior of fractures, despite their intensive efforts.

This situation changed with recent work by Dr. SHEN Laiquan, Prof. BAI Haiyang, Prof. SUN Baoan, and others from Prof. WANG Weihua's group at the Institute of Physics of the Chinese Academy of Sciences (CAS), who have successfully observed the effect of cavitation on fracture behavior in glasses. They revealed that crack propagation is dominated by the self-organized nucleation, growth, and coalescence of nanocavities in metallic glasses.

They showed the evolutionary process of crack morphologies from separated nanocavities to wave-like nanocorrugations, and confirmed that cavitation is the origin of periodic fracture surface patterns.

In addition, they found that cavitation-induced nanopatterns are also prevalent in typical polymer glass (polycarbonate) and silicate glass (silica), indicating that the cavitation mechanism is common in the fracture of glasses. Plastic flow exhibited by the cavitation process thus proves that nanoscale ductility is involved in the breakage of nominally brittle glasses.

The discovery of cavitation behavior in the fracture of glasses challenges the traditional concept of how glasses break. The researchers' findings have significant implications for the understanding of the fundamental process of failure in disordered systems, and provides incentives for engineering better glasses.

A study by KAIST researchers revealed that an ionized gas jet blowing onto water, also known as a 'plasma jet', produces a more stable interaction with the water's surface compared to a neutral gas jet. This finding reported in the April 1 issue of Nature will help improve the scientific understanding of plasma-liquid interactions and their practical applications in a wide range of industrial fields in which fluid control technology is used, including biomedical engineering, chemical production, and agriculture and food engineering.

Gas jets can create dimple-like depressions in liquid surfaces, and this phenomenon is familiar to anyone who has seen the cavity produced by blowing air through a straw directly above a cup of juice. As the speed of the gas jet increases, the cavity becomes unstable and starts bubbling and splashing.

"Understanding the physical properties of interactions between gases and liquids is crucial for many natural and industrial processes, such as the wind blowing over the surface of the ocean, or steelmaking methods that involve blowing oxygen over the top of molten iron," explained Professor Wonho Choe, a physicist from KAIST and the corresponding author of the study.

However, despite its scientific and practical importance, little is known about how gas-blown liquid cavities become deformed and destabilized.

In this study, a group of KAIST physicists led by Professor Choe and the team's collaborators from Chonbuk National University in Korea and the Jožef Stefan Institute in Slovenia investigated what happens when an ionized gas jet, also known as a 'plasma jet', is blown over water. A plasma jet is created by applying high voltage to a nozzle as gas flows through it, which causes the gas to be weakly ionized and acquire freely-moving charged particles.

The research team used an optical technique combined with high-speed imaging to observe the profiles of the water surface cavities created by both neutral helium gas jets and weakly ionized helium gas jets. They also developed a computational model to mathematically explain the mechanisms behind their experimental discovery.

The researchers demonstrated for the first time that an ionized gas jet has a stabilizing effect on the water's surface. They found that certain forces exerted by the plasma jet make the water surface cavity more stable, meaning there is less bubbling and splashing compared to the cavity created by a neutral gas jet.

Specifically, the study showed that the plasma jet consists of pulsed waves of gas ionization propagating along the water's surface so-called 'plasma bullets' that exert more force than a neutral gas jet, making the cavity deeper without becoming destabilized.

"This is the first time that this phenomenon has been reported, and our group considers this as a critical step forward in our understanding of how plasma jets interact with liquid surfaces. We next plan to expand this finding through more case studies that involve diverse plasma and liquid characteristics," said Professor Choe.

University of Warwick physicists set out to find Skyrmions, only to find near-identical object with distinctive qualities that they have named an incommensurate spin crystal

Scientists looked for the signs of the magnetic spin texture in ultra-thin materials only a few atoms thick

Physicists have great interest in the potential of Skyrmions frequently detected by their ambiguous, bulk electrical measurements.

This new discovery could point the way for a new basis for technologies in computer memory and storage

Physicists on the hunt for a rarely seen magnetic spin texture have discovered another object that bears its hallmarks, hidden in the structure of ultra-thin magnetic films, that they have called an incommensurate spin crystal.

A team from the University of Warwick reports the findings in the journal Nature Communications, which could offer new possibilities for technologies such as computer memory and storage.

The researchers initially set out to find a Skyrmion, a whirling magnetic spin texture theorised to exist in particular magnetic materials and that are of great interest to physicists due to their unique properties and potential for a new generation of energy efficient data storage. To find them, scientists look for abnormal behaviour of the Hall effect; this causes electrons moving through a conducting material to behave differently, measured as resistivity.

To induce this effect, the team created samples by combining an extremely thin film of a ferroelectric material, lead titanate, with another thin film of a ferromagnet, strontium ruthanate. These layers are atomically flat, a mere five to six unit cells (3 nanometres) thick.

The ferroelectric layer induces an electric field that warps the atomic structure of the ferromagnet, breaking its symmetry. Using atomical precision electron microscopy, they measured this symmetry breaking, and were also able to separately measure the electrical resistivity of the material and confirmed the presence of features akin to the Topological Hall effect, as would be expected for a Skyrmion.

Then the researchers used Magnetic Force Microscopy to examine the topology of the material's atomic structure, which formed a lattice based on rectangles - not hexagons, as they would expect. Within this lattice are magnetic domains where Skyrmions would be found as individual, isolated particles. Instead, these domains formed more like beads on a string or necklace, with beads that never quite form a perfect circle.

Lead author Sam Seddon, a PhD student in the University of Warwick Department of Physics, said: "Once you make careful examination of the images, you realise, actually, this doesn't present like a Skyrmion at all.

"A Skyrmion causes its own complicated Hall effect and when similar-looking effects are observed it is often treated as a signature of the Skyrmion. We've found a very ordered domain structure, just as a Skyrmion lattice would form, however they are simply chiral and not topologically protected. What this shows with real-space imaging evidence is that you don't need a topological domain to cause a Hall effect of this kind."

Ferroelectric and ferromagnetic materials are important for technologies such as computer memory and storage. For example, materials very similar to lead titanate are often used for the computer memory in the electronic systems in cars, due to their robustness and ability to operate at extreme temperatures.

Co-author Professor Marin Alexe from the University of Warwick said: "There is interest in these types of interfaces between ferroelectric and ferromagnet materials, such as for new types of computer memory. Because ferroelectric polarisation can be switched permanently, this modifies a quantum effect in a ferromagnet and that might give us direction for materials for the next quantum computers. These will need stable materials which work at extreme temperatures, are low-power consumption, and can store information for a long time, so all the ingredients are here.

"Topology is the translation of certain mathematical concepts into real life and is now at the core of new discoveries in physics. At the University of Warwick we have an extraordinary and advanced infrastructure which allows us to tackle a problem from theoretical point of view, to looking at atomic structure, right up to looking into functional properties at extreme temperatures and fields, especially magnetic fields. We are able to offer foundations for engineers to develop new technologies from."

Grain boundaries (GBs) in PSCs have been found to be detrimental to the photovoltaic performance of the devices. Numerous papers reported that the defects in perovskite GBs should be passivated by suitable materials, such as quaternary ammonium halide, fullerene derivatives and CH3NH3I, to alleviate carrier recombination and consequently improve the device performance.

In a new paper published in Light: Science & Applications, a team of scientists, led by Professor Feng Yan from Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, and co-workers have developed a novel method to overcome the drawback of perovskite GBs without defect passivation on them. Several 2-D materials, including black phosphorus (BP), MoS2 and graphene oxide (GO), are specifically modified on the edge of perovskite GBs by a solution process. The 2-D materials have high carrier mobilities, ultrathin thicknesses and smooth surfaces without dangling bonds. The PCEs of the devices are substantially enhanced by the 2-D flakes, in which BP flakes can induce the highest relative enhancement of about 15%. More interestingly, they find that, under certain conditions, GBs modified with the 2-D materials are favorable for the device performance. Therefore, a synergistic effect between the 2-D flakes and perovskite GBs is observed for the first time. Although the nanotechnology of using 2-D materials in PSCs has been reported in some papers, the synergistic effect between the 2-D flakes and perovskite GBs has not been reported until now. To better understand the underlying mechanism of the above effect, device simulation was conducted by using a commercial software. The hole conduction processes from GBs to 2-D flakes in PSCs are clearly demonstrated, showing that the GBs and 2-D flakes all act as hole channels in the devices. The simulation results confirm that the performance enhancement induced by BP is higher than that by other 2-D materials because of the highest hole mobility of BP. In addition, the modification of the 2-D flakes on the perovskite grains away from GBs has little effect on the device performance, indicating that the synergistic effect of 2-D flakes and perovskite GBs is essential to the performance enhancement in our devices.

Although the coverage of the 2-D flakes on the perovskite films is only several percent, most of the flakes are located on perovskite GBs. Due to the high carrier mobilities of the 2-D materials especially BP, hole transfer from GBs is dramatically enhanced in the PSCs, resulting in substantial improvements of the efficiency as well as the stability of the devices. These results also indicate that GBs in PSCs are not detrimental to the device performance if the accumulated holes in the GBs can be conducted out efficiently. Under certain conditions, GBs even can be favorable for the photovoltaic performance of PSCs due to the built-in electric fields around them, which can facilitate photocarrier separation and transfer in the devices. Therefore, perovskite GBs are electrically benign, which is consistent with some theoretical calculations reported before. More importantly, they observed the synergic effect of the 2D flakes on the GBs in PSCs for the first time. Both the carrier mobility and the location of the 2D flakes on the perovskite surface are essential to the performance enhancement. This work provides a guideline of modifying perovskite layers with novel high-mobility 2-D materials to improve the photovoltaic performance as well as the stability of PSCs.

The research team led by Prof. GUO Guangcan and Dr. DONG Chunhua from the University of Science and Technology of China realized synthetic gauge fields in a single optomechanical resonator by controlling geometric phase with the multimode interaction in the micro-resonator.

By engineering a Hamiltonian, uncharged particles or bosonic excitations can acquire a path-dependent phase which realizes a synthetic magnetic field. Such synthetic gauge field can improve the precision of quantum many-body simulation and control over bosons.

Previous works have realized synthetic gauge fields through coupled resonators, while this time the team realized synthetic gauge field in a single optomechanical resonator based on multimode interaction of microcavity.

The team proposed to employ clockwise and counterclockwise driving lasers into the microcavity simultaneously, which realized the coherent coupling between optical photons and phonons and achieved complete control over the coupling phase.

In the experiment, researchers proved that the coupling transport of optical photons between multiple modes would obtain a path-dependent phase, which can realize the equivalent synthetic magnetic field of optical photons.

Thanks to the advantages of microcavity optical field modulation, the team further realized the time-varying canonical phase and demonstrated the synthetic electric field of optical photons in a single optomechanical resonator.

Higher dimensional synthetic gauge field is indicated by the experiment results, in consideration of the strong coherent optomechanical coupling interaction and coherent nonlinear optical effects in microcavities.

The study was published on Physics Review Letters.

The synthetic fields shown in this work shed light on the topological properties of optical photons and realization of chiral edge states and topological protection.

DARIEN, IL - The American Academy of Sleep Medicine recently published an update on the use of telemedicine for the diagnosis and treatment of sleep disorders to reflect lessons learned from the transition to telemedicine during the COVID-19 pandemic and the benefits of continuing to utilize remote care when appropriate.

While the technology to remotely connect doctor and patient has been in place for years, its use was limited until the spread of COVID-19. In 2020, the Centers for Medicare & Medicaid Services (CMS) lifted restrictions on telemedicine reimbursement, and private insurance companies followed suit. Telemedicine has been critical to ensuring safe, timely care for patients during the pandemic, and the field of sleep medicine has proven to be a specialty that can offer complete and quality care remotely.

"Delivering care during the pandemic has proven to providers and insurers that telemedicine offers patients safe, secure and effective sleep care," said Dr. Douglas Kirsch, chair of the AASM Telemedicine Presidential Committee, which wrote the update. "The AASM will continue to advocate for permanent coverage and reimbursement of telemedicine services with CMS and third-party payers."

Published online as an accepted paper in the Journal of Clinical Sleep Medicine, the update addresses several key issues in the delivery of sleep care using telemedicine, including quality and value, privacy and safety, health advocacy, and future directions. The paper shares new evidence that telemedicine is effective in the diagnosis and management of obstructive sleep apnea and improves adherence to CPAP therapy. Telemedicine also has been widely used to provide care to patients with insomnia through cognitive behavioral therapy and brief behavioral therapy, with results similar to in-person treatment.

The paper also acknowledges opportunities for improvement in the adoption and use of telemedicine. Those include compliance with patient privacy laws, additional training for providers, and awareness of limited access among disadvantaged populations.

"Telemedicine improves access to care, but we need to be cautious that its use doesn't introduce new health inequities in underserved communities that may lack the necessary technologies," said Kirsch. "Improved connectivity and increased access to high-speed internet need to grow together with telehealth expansion."

MADISON - Bipolar disorder affects millions of Americans, causing dramatic swings in mood and, in some people, additional effects such as memory problems.

While bipolar disorder is linked to many genes, each one making small contributions to the disease, scientists don't know just how those genes ultimately give rise to the disorder's effects.

However, in new research, scientists at the University of Wisconsin-Madison have found for the first time that disruptions to a particular protein called Akt can lead to the brain changes characteristic of bipolar disorder. The results offer a foundation for research into treating the often-overlooked cognitive impairments of bipolar disorder, such as memory loss, and add to a growing understanding of how the biochemistry of the brain affects health and disease.

The Cahill lab and their colleagues at Michigan State University published their findings March 24 in Neuron.

Akt is a kinase, a type of protein that adds tags of the molecule phosphate to other proteins. These phosphate tags can act as on or off switches, changing how other proteins work, ultimately influencing vital functions. In neurons, those functions can include how cells signal to one another, which can affect thinking and mood. When the Akt pathway is revved up, a lot of other proteins get phosphate tags. When it's quieter, those phosphate tags are absent.

The researchers discovered that men with bipolar disorder have reduced activity of this pathway, known at Akt-mTOR, in a brain region crucial for attention and memory. And when the researchers disrupted the pathway in mice, the rodents developed memory problems and crucial brain connections withered away, simulating changes in humans with bipolar disorder.

"This loss of Akt pathway function in people with bipolar disorder is probably contributing to cognitive impairment," says Michael Cahill, a professor of neuroscience in the UW-Madison School of Veterinary Medicine, who led the research. "The idea is that maybe we can target pathways like this one pharmacologically to help alleviate core symptoms of bipolar disorder."

To assess activity of the Akt pathway, the Cahill lab acquired brain tissue samples from deceased donors who had schizophrenia, bipolar disorder without psychosis, and bipolar disorder with psychosis, as well as healthy donors. The tissue samples came from the prefrontal cortex, known to control high-level functions, which is affected by bipolar disorder and the related disorder schizophrenia.

By measuring the number and variety of phosphate tags on proteins controlled by Akt in the tissue samples, the researchers could get a sense of the overall activity of the Akt-mTOR pathway.

Although they were originally expecting to see the biggest changes in patients with schizophrenia -- which has the strongest genetic links to the Akt gene among the three related disorders -- the researchers found that activity of the Akt-mTOR pathway was diminished in just one group of patients: men with bipolar disorder without psychosis.

"It was very different than we thought, which is kind of a good example of how in science you don't really know what you're going to get," says Cahill.

After seeing this correlation between bipolar disorder and a quieter Akt pathway, Cahill's group then asked what effect this diminished Akt pathway would have in the brain. To answer that question, they used viruses to deliver broken Akt proteins to the prefrontal cortexes of mice. The broken Akt proteins would override working ones, gumming up the Akt pathway.

In behavioral tests, the mice with gummed up Akt pathways demonstrated memory problems, no longer exploring changes to familiar environments.

Spending a lot of time investigating objects or other features that have changed their location is "their way of telling us that they recognize something is different," says Cahill. "That was impaired when we disrupted the Akt pathway."

But mice with less active Akt pathways still showed typical social behaviors, suggesting that the pathway wasn't responsible for other high-level brain functions.

When the scientists looked in the brains of mice with diminished Akt pathways, they found that the connections that neurons use to interact with other neurons, known as dendritic spines, had withered.

Dendritic spines are like intersections between the roads that information in the brain travels on. "With the number of intersections being reduced, it's harder to get where you want to go," Cahill says.

That disrupting the Akt pathway in mice seemed to replicate aspects of bipolar disorder that also occur in humans -- memory problems, weaker neuron connections --provides the first clear link from this gene to the effects of bipolar disorder.

Yet, many questions remain. Women with bipolar disorder did not show the same changes in Akt-mTOR activity as men did. Nor did people with bipolar disorder with psychosis or those with schizophrenia, despite similar genetic links between the Akt pathway and these disorders.

Untangling these differences and fleshing out the path from genes to disease will require much more research. For instance, many other genes contribute to bipolar disorder, and those genes may play a larger role in these groups.

Going forward, Cahill's lab plans to follow individual circuits in the brain to discover just how the Akt pathway influences memory. That additional research should help unravel some of the enduring riddles surrounding bipolar disorder and how subtle genetic changes can lead to big differences in how people experience the world.

Buildings are responsible for 40 percent of primary energy consumption and 36 percent of total CO2 emissions. And, as we know, CO2 emissions trigger global warming, sea level rise, and profound changes in ocean ecosystems. Substituting the inefficient glazing areas of buildings with energy efficient smart glazing windows has great potential to decrease energy consumption for lighting and temperature control.

Harmut Hillmer et al. of the University of Kassel in Germany demonstrate that potential in "MOEMS micromirror arrays in smart windows for daylight steering," a paper published recently in the inaugural issue of the Journal of Optical Microsystems.

"Our smart glazing is based on millions of micromirrors, invisible to the bare eye, and reflects incoming sunlight according to user actions, sun positions, daytime, and seasons, providing a personalized light steering inside the building," Hillmer said.

The micromirror array is invulnerable to wind, window cleaning, or any weather conditions because it is located in the space between the windowpanes filled with noble gas such as argon or krypton. The glazing provides free solar heat in winter and overheating prevention in summer, and it enables healthy natural daylight, huge energy savings (up to 35 percent), massive CO2 reduction (up to 30 percent), and a reduction of 10 percent steel and concrete in high-rise buildings.

Apart from the energy problem, artificial lighting also has consequences for health and well-being. Various studies have linked artificial lighting to lack of concentration, high susceptibility to illness, disturbed biorhythms, and sleeplessness. Smart glass can reduce reliance on artificial lighting by optimizing natural daylight in a room.

Current state-of-the-art smart glazings are currently optimized either for winter or for summer-and not able to ensure energy-saving performance year-round. There has been a need for a smart and automatic technology that can react to local climate (daytime, season), uses available sunlight, regulates light and temperature, and saves substantial energy.

The researchers' MEMS micromirror arrays are integrated inside insulation glazing and are operated by an electronic control system. The orientation of mirrors is controlled by the voltage between respective electrodes. Motion sensors in the room detect the number, position, and movement of users in the room.

The results include much higher actuation speed in the sub-ms range, 40-times lower power consumption than electrochromic or liquid crystal concepts, reflection instead of absorption, and color neutrality. Rapid aging tests of the micromirror structure were performed to study reliability and revealed sustainability, robustness, and long lifetimes of the micromirror arrays.

And with positive results like that, the benefits of this smart glass are crystal clear.

A highly contagious SARS-CoV-2 variant was unknowingly spreading for months in the United States by October 2020, according to a new study from researchers with The University of Texas at Austin COVID-19 Modeling Consortium. Scientists first discovered it in early December in the United Kingdom, where the highly contagious and more lethal variant is thought to have originated. The journal Emerging Infectious Diseases, which has published an early-release version of the study, provides evidence that the coronavirus variant B117 (501Y) had spread across the globe undetected for months when scientists discovered it.

"By the time we learned about the U.K. variant in December, it was already silently spreading across the globe," said Lauren Ancel Meyers, the director of the COVID-19 Modeling Consortium at The University of Texas at Austin and a professor of integrative biology. "We estimate that the B117 variant probably arrived in the U.S. by October of 2020, two months before we knew it existed."

Analyzing data from 15 countries, researchers estimated the chance that travelers from the U.K. introduced the variant into 15 countries between Sept. 22 and Dec. 7, 2020. They found that the virus variant had almost certainly arrived in all 15 countries by mid-November. In the U.S., the variant probably had arrived by mid-October.

"This study highlights the importance of laboratory surveillance," Meyers said. "Rapid and extensive sequencing of virus samples is critical for early detection and tracking of new variants of concern."

In conjunction with the paper's publication, consortium members developed a new tool that decision-makers anywhere in the United States can use in planning for genetic sequencing that helps to detect the presence of variants. To help the U.S. expand national surveillance of variants, the new online calculator indicates the number of virus samples that must be sequenced in order to detect new variants when they first emerge. For example, if the goal is to detect an emerging variant by the time it is causing 1 out of every 1,000 new COVID-19 infections, approximately 3,000 SARS-CoV-2 positive specimens per week need to be sequenced.

"Health officials are looking for better ways to manage the unpredictability of this virus and future variants," said Spencer Woody, a postdoctoral fellow at the UT COVID-19 Modeling Consortium. "Our new calculator determines how many positive SARS-CoV-2 specimens must be sequenced to ensure that new threats are identified as soon as they start spreading."

He explained that the calculator has a second feature. "It also helps labs figure out how quickly they will detect new variants, given their current sequencing capacity."

"We created this tool to support federal, state and local health officials in building credible early warning systems for this and future pandemic threats," Meyers said.