Tech

Lithium is an energy-critical element that is considered to be a geopolitically significant resource. However, the supply of lithium may not be enough to meet continuously increasing demand. As a result, scientists are looking for new ways to extract lithium ions.

Ion selective membranes have already been used extensively for water treatment and ion sieving in electrodialysis technology. However, conventional membranes exhibit low and useless Li+ selectivity, making them insufficient for meeting industry requirements.

Chinese scientists have recently made progress in the preparation and application of a bioinspired material that is capable of achieving controlled ion transport and sieving, especially for lithium-ion extraction.

This work, published in Matter, was completed by Prof. WEN Liping's team at the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences and Prof. ZHANG Qianfan's team from Beihang University.

In this research, scientists utilized nanofibers, such as from natural silk and polyethyleneimine, to decorate 2D nanosheets. Inspired by the biological structure in nature, the 2D nanosheets are self-assembled layer-by-layer to form a nacre-like stacked structure. The composited membrane acts as an ion-gating heterojunction with opposite charges and asymmetrical nanochannels.

"To be more detailed, the composited membrane shows higher toughness than other reported materials and natural nacre structures. The membrane is also able to efficiently control interlayer spacing and achieve stable ordered nanostructures," said Prof. WEN.

The typical brick-and-mortar structure formed by nanofibers and nanosheets exhibits a long-time use in solutions. Meanwhile, the confined dehydration and charge-exclusion effects conduct Li+ through composited channels rapidly.

Experimental and theoretical results indicate Li+ shows an excellent permeation rate that is far higher than Na+, K+, Mg2+ and Ca2+ due to its small radius and low charge.

Compared with mobilities in bulk, Li+ remains basically consistent with the bulk value. In stark contrast, other ions become less mobile than Li+ in bulk.

The methodology of using tailor-made 2D membranes with chemical, geometrical, and electrostatic heterostructures allows further exploration of nanofluidic phenomena inside nanochannel membranes for water treatment or power generation.

COLUMBUS, Ohio - The introduction of computer simulation to the identification of symptoms in children with attention deficit/hyperactivity disorder (ADHD) has potential to provide an additional objective tool to gauge the presence and severity of behavioral problems, Ohio State University researchers suggest in a new publication.

Most mental health disorders are diagnosed and treated based on clinical interviews and questionnaires - and, for about a century, data from cognitive tests has been added to the diagnostic process to help clinicians learn more about how and why people behave in a certain way.

Cognitive testing in ADHD is used to identify a variety of symptoms and deficits, including selective attention, poor working memory, altered time perception, difficulties in maintaining attention and impulsive behavior. In the most common class of performance tests, children are told to either press a computer key or avoid hitting a key when they see a certain word, symbol or other stimulus.

For ADHD, however, these cognitive tests often don't capture the complexity of symptoms. The advent of computational psychiatry - comparing a computer-simulated model of normal brain processes to dysfunctional processes observed in tests - could be an important supplement to the diagnostic process for ADHD, the Ohio State researchers report in a new review published in the journal Psychological Bulletin.

The research team reviewed 50 studies of cognitive tests for ADHD and described how three common types of computational models could supplement these tests.

It is widely recognized that children with ADHD take longer to make decisions while performing tasks than children who don't have the disorder, and tests have relied on average response times to explain the difference. But there are intricacies to that dysfunction that a computational model could help pinpoint, providing information clinicians, parents and teachers could use to make life easier for kids with ADHD.

"We can use models to simulate the decision process and see how decision-making happens over time - and do a better job of figuring out why children with ADHD take longer to make decisions," said Nadja Ging-Jehli, lead author of the review and a graduate student in psychology at Ohio State.

Ging-Jehli completed the review with Ohio State faculty members Roger Ratcliff, professor of psychology, and L. Eugene Arnold, professor emeritus of psychiatry and behavioral health.

The researchers offer recommendations for testing and clinical practice to achieve three principal goals: better characterizing ADHD and any accompanying mental health diagnoses such as anxiety and depression, improving treatment outcomes (about one-third of patients with ADHD do not respond to medical treatment), and potentially predicting which children will "lose" the ADHD diagnosis as adults.

Decision-making behind the wheel of a car helps illustrate the problem: Drivers know that when a red light turns green, they can go through an intersection - but not everyone hits the gas pedal at the same time. A common cognitive test of this behavior would repeatedly expose drivers to the same red light-green light scenario to arrive at an average reaction time and use that average, and deviations from it, to categorize the typical versus disordered driver.

This approach has been used to determine that individuals with ADHD are typically slower to "start driving" than those without ADHD. But that determination leaves out a range of possibilities that help explain why they're slower - they could be distracted, daydreaming, or feeling nervous in a lab setting. The broad distribution of reactions captured by computer modeling could provide more, and useful, information.

"In our review, we show that this method has multiple problems that prevent us from understanding the underlying characteristics of a mental-health disorder such as ADHD, and that also prevent us from finding the best treatment for different individuals," Ging-Jehli said. "We can use computational modeling to think about the factors that generate the observed behavior. These factors will broaden our understanding of a disorder, acknowledging that there are different types of individuals who have different deficits that also call for different treatments.

"We are proposing using the entire distribution of the reaction times, taking into consideration the slowest and the fastest reaction times to distinguish between different types of ADHD."

The review also identified a complicating factor for ADHD research going forward - a broader range of externally evident symptoms as well as subtle characteristics that are hard to detect with the most common testing methods. Understanding that children with ADHD have so many biologically based differences suggests that a single task-based test is not sufficient to make a meaningful ADHD diagnosis, the researchers say.

"ADHD is not only the child who is fidgeting and restless in a chair. It's also the child who is inattentive because of daydreaming. Even though that child is more introverted and doesn't express as many symptoms as a child with hyperactivity, that doesn't mean that child doesn't suffer," Ging-Jehli said. Daydreaming is especially common in girls, who are not enrolled in ADHD studies nearly as frequently as boys, she said.

Ging-Jehli described computational psychiatry as a tool that could also take into account - continuing the analogy - mechanical differences in the car, and how that could influence driver behavior. These dynamics can make it harder to understand ADHD, but also open the door to a broader range of treatment options.

"We need to account for the different types of drivers and we need to understand the different conditions to which we expose them. Based on only one observation, we cannot make conclusions about diagnosis and treatment options," she said.

"However, cognitive testing and computational modeling should not be seen as an attempt to replace existing clinical interviews and questionnaire-based procedures, but as complements that add value by providing new information."

According to the researchers, a battery of tasks gauging social and cognitive characteristics should be assigned for a diagnosis rather than just one, and more consistency is needed across studies to ensure the same cognitive tasks are used to assess the appropriate cognitive concepts.

Finally, combining cognitive testing with physiological tests - especially eye-tracking and EEGs that record electrical activity in the brain - could provide powerful objective and quantifiable data to make a diagnosis more reliable and help clinicians better predict which medicines would be most effective.

Ging-Jehli is putting these suggestions to the test in her own research, applying a computational model in a study of a specific neurological intervention in children with ADHD.

"The purpose of our analysis was to show there's a lack of standardization and so much complexity, and symptoms are hard to measure with existing tools," Ging-Jehli said. "We need to understand ADHD better for children and adults to have a better quality of life and get the treatment that is most appropriate."

Kraków, 30 December 2020

The map of nuclear deformation takes the form of a mountain landscape

Until recently, scientists believed that only very massive nuclei could have excited zero-spin states of increased stability with a significantly deformed shape. Meanwhile, an international team of researchers from Romania, France, Italy, the USA and Poland showed in their latest article that such states also exist in much lighter nickel nuclei. Positive verification of the theoretical model used in these experiments allows describing the properties of nuclei unavailable in Earth laboratories.

More than 99.9 per cent of the mass of an atom comes from the atomic nucleus, the volume of which is over a trillion times smaller than the volume of the entire atom. Hence, the atomic nucleus has an amazing density of about 150 million tons per cubic centimetre. This means that one tablespoon of nuclear matter weighs almost as much as a cubic kilometre of water. Despite their very small size and incredible density, atomic nuclei are complex structures made of protons and neutrons. One may expect that such extremely dense objects would always take spherical form. In reality, however, the situation is quite different: most nuclei are deformed - they exhibit shape flattened or elongated along one or even two axes, simultaneously. To find the favourite form of a given nucleus, it is customary to construct a landscape of the potential energy as a function of deformation. One may visualize such landscape by drawing a map on which the plane coordinates are the deformation parameters, i.e. degrees of elongation or flattening along the two axes, while the colour indicates the amount of energy needed to bring the nucleus to a given shape. Such a map is a full analogy to a geographical map of mountain terrain.

If a nucleus is formed in the nuclear reaction, it appears at a given point of the landscape - it takes specific deformation. It then starts to slide (change deformation) towards the lowest energy point (stable deformation). In some cases, however, before reaching the ground state, it may be stopped for a while in some local minimum, a trap, which corresponds to metastable deformation. This is very similar to water that springs in a particular location in the mountain area and flows downward. Before it reaches the lowest valley, it may be trapped in local depressions for some time. If a stream connects the local depression to the lowest point of the landscape, water will flow down. If the depression is well isolated, the water will stay there for a very long time.

Experiments have shown that local minima in the nuclear deformation landscape at spin zero exist only in massive nuclei with atomic numbers larger than 89 (actinium) and a total number of protons and neutrons well above 200. Such nuclei can be trapped in these secondary minima at metastable deformation for a period even tens of millions of times longer than the time needed to reach the ground state without being slowed down by the trap. Until a few years ago, an excited zero-spin state associated with metastable deformation had never been observed among nuclei of lighter elements. The situation changed a few years ago when a state with sizeable deformation characterized by increased stability was found in nickel-66, the nucleus with 28 protons and 38 neutrons. This identification was stimulated by calculations performed with the sophisticated Monte Carlo shell model developed by Tokyo University theorists, which predicted this deformation trap.

"The calculations performed by our Japanese colleagues also provided another unexpected result," says Prof. Bogdan Fornal (IFJ PAN). "They showed that a deep, local depression (trap) associated with sizeable deformation should be present also in the potential energy landscape of nickel-64, the nucleus with two neutrons less than nickel-66, which until now was considered to have only one main minimum with a spherical shape. The problem was that in nickel-64 the depression was predicted at high excitation energy - at high altitude in the mountain terrain analogy - and it was extremely difficult to find an experimental method to place the nucleus in this trap."

A tour de force took place involving four complementary experiments, jointly conducted by a collaboration lead by experimentalists from Romania (IFIN-HH in Bucharest), France (Institut Laue-Langevin, Grenoble), Italy (University of Milan), USA (the University of North Carolina and TUNL) and Poland (IFJ PAN, Krakow). Measurements were performed at four different laboratories in Europe and the USA: Institut Laue-Langevin (Grenoble, France), IFIN-HH Tandem Laboratory (Romania), Argonne National Laboratory (Chicago, USA) and the Triangle Universities Nuclear Laboratory (TUNL, North Carolina, USA). Different reaction mechanisms were employed including proton and neutron transfer, thermal-neutron capture, Coulomb excitation and nuclear-resonance fluorescence, in combination with state-of-the-art gamma-ray detection techniques.

All the data taken together allowed to establish the existence of two secondary minima in the potential energy landscape of nickel-64, corresponding to oblate (flattened) and prolate (elongated) ellipsoidal shapes, with the prolate one being deep and well isolated as indicated by the significantly retarded transition to the main spherical minimum.

"The extension of time which the nucleus spends when trapped in the prolate minimum of the Ni-64 nucleus is not as spectacular as that of the heavy nuclei, where it reaches tens of millions of times. We recorded the increase of only a few tens of times; yet the fact that this increase is close to the one provided by the new theoretical model, is a great achievement," states Prof. Fornal.

A particularly valuable outcome of the study is identifying a previously unconsidered component of the force acting between nucleons in complex nuclear systems, the so-called tensor monopole, which is responsible for the multifaceted landscape of deformation in the nickel isotopes. Scientists expect that this interaction is accountable to a large extent for shaping the structure of many nuclei that have not yet been discovered.

In a broader perspective, the presented investigation indicates that the theoretical approach applied here, being able to adequately predict the unique characteristics of the nickel nuclei, has great potential in describing the properties of hundreds of nuclear systems which are not accessible in the laboratory on the Earth today, but continually produced in stars.

LOS ANGELES (Dec. 30, 2020) -- People who move due to unaffordable housing are at increased risk of failing to receive the medical care they need, according to a new study from Cedars-Sinai and the University of California, Los Angeles. The study, published online in the Journal of General Internal Medicine, concludes that the result could be long-term health problems.

The findings were based on 146,417 adults who responded from 2011 to 2017 to the California Health Interview Survey, the largest such state survey in the U.S. The study compared those who had moved their residences in the last five years to those who had not. It found those who had moved due to cost, as opposed to other reasons, were more likely to report delaying or not receiving prescribed medicines and needed medical care during the previous 12 months.

"While our research did not include data after 2017, the findings have never been more relevant, given the financial strains posed by the COVID-19 (coronavirus) pandemic," said the study's corresponding author, Katherine Chen, MD, a fellow in the UCLA National Clinician Scholars Program, who led the research in partnership with and supported by Cedars-Sinai. A recent study from the Aspen Institute in Washington, D.C., estimated that 30 million to 40 million renters in the U.S. could be at risk of eviction in the next few months.

"I am worried about long-term clinical consequences of the backlog of unmet medical needs that could result from the pending wave of evictions and moves," Chen said. "As a physician at a community clinic, I've seen patients who had stressful moves put their medical care on hold. Some ended up coming back to the clinic with serious conditions, including untreated hypertension or diabetes, which can lead to kidney failure."

Investigators said they undertook the research because few studies have examined the healthcare access consequences of cost-related moves. Within their study sample, they found the odds of unmet medical needs were increased by 38% for people with cost-related moves and 17% for people with non-cost-related moves, compared with people who did not move.

"The magnitude of the association between unmet medical needs and moves was significantly larger for cost-related moves than for other moves," Chen said.

The study also found that people with cost-related moves were generally younger, less likely to be white, more likely to have several children, less educated, lower income, more often unemployed and uninsured, and in worse health than those in other categories. However, the association between cost-related moves and unmet medical needs persisted across these individual socioeconomic and health variables.

"We were surprised to find that even people who moved within the same neighborhood for cost reasons experienced disruption of medical care," said the study's senior author, Frederick J. Zimmerman, PhD, from the Fielding School of Public Health at UCLA. "And having a higher income did not insulate movers from the negative effects."

Investigators emphasized that their data did not prove cost-related moves cause poorer access to needed healthcare and drugs or explain why the relationship exists. But given the strong association, and the frequency of such residence changes, they suggested preventive action is needed.

"In our study sample of California adults, nearly 1 in 20 reported moving due to unaffordable housing costs in the past five years-equivalent to a staggering 1.4 million people per year in California alone," said Teryl Nuckols, MD, MSHS, director of the Division of General Internal Medicine in the Cedars-Sinai Department of Medicine. "Policymakers seeking to improve population health should consider strategies to limit cost-related moves and to mitigate their adverse effects on healthcare access."

Toronto - With the arrival of effective vaccines for the COVID-19 virus, the end of the pandemic is on the horizon but in the short term the virus continues to spread.

A timely new study published today by PLOS ONE examines the effectiveness of COVID-19 control policies in 40 jurisdictions including countries and U.S. states.

Among the conclusions is that significant social costs must be incurred to reduce the growth of the virus below zero. In most jurisdictions examined, policies with a lesser social impact including cancellation of public events, restrictions of gatherings to fewer than 100 people, and recommendations to stay at home, are not enough in themselves to control COVID-19. Socially intolerable measures such as stay-at-home orders, targeted or full workplace and school closings are also required.

The study is authored by Anita M. McGahan, University Professor and the George E. Connell Chair in Organizations & Society at the University of Toronto's Rotman School of Management and Munk School of Global Affairs and Public Policy, Wesley Wu-Yi Koo, an assistant professor of strategy at INSEAD, and Phebo Wibbens, an assistant professor of strategy at INSEAD.

The study used a model to generate estimates of the marginal impact of each policy in a jurisdiction after accounting for the overall portfolio of policies adopted by the jurisdiction, the levels at which the policies are implemented, the rigorousness of compliance within the jurisdiction, the jurisdiction's COVID-19 infections, COVID-19 deaths, and excess deaths, and the performance of the portfolio of policies in other jurisdictions. Eleven categories of COVID-19 control policies were examined including school closings, workplace closings, cancellation of public events, restrictions on gatherings, closing of public transport, stay-at-home requirements, restrictions on internal movement, international travel controls, public information campaigns, testing, and contact tracing.

The study is online at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0244177.

The Rotman School of Management is part of the University of Toronto, a global centre of research and teaching excellence at the heart of Canada's commercial capital. Rotman is a catalyst for transformative learning, insights, and public engagement, bringing together diverse views and initiatives around a defining purpose: to create value for business and society. For more information, visit http://www.rotman.utoronto.ca.

Leesburg, VA, December 29, 2020--According to an article in ARRS' American Journal of Roentgenology (AJR), because patients with ballistic embedded fragments are frequently denied MRI (due to indeterminate bullet composition sans shell casings), radiography and CT can be used to identify nonferromagnetic projectiles that are safe for MRI.

"Commercially available handgun and shotgun ammunition representing projectiles commonly encountered in a clinical setting was fired into ballistic gelatin as a surrogate for human tissue," explained first author Arthur J. Fountain from the department of radiology and imaging sciences at Emory University.

After obtaining radiographs and CT images of these gelatin blocks, Fountain and colleagues then obtained MR images of unfired bullets suspended in gelatin blocks using T1- and T2-weighted sequences. Magnetic attractive force, rotational torque, and heating effects of unfired bullets were assessed at 1.5 T.

Based upon debris trail and primary projectile deformation, the team separated the fired bullets into two groups: ferromagnetic and nonferromagnetic. Although ferromagnetic bullets showed mild torque forces and marked imaging artifacts at 1.5 T, nonferromagnetic bullets did not exhibit these effects.

Importantly, heating above the Food and Drug Administration limit of 2°C was not observed in any of the projectiles tested.

Additionally, the authors of this AJR article presented a triage algorithm for patients with retained ballistic fragments. "In particular," Fountain et al. described, "a projectile that leaves a metallic debris trail from entry to final position or has been appreciably deformed is of copper, copper-alloy, or lead composition with a partial jacketed configuration or represents lead shotgun shot and does not pose a significant risk for imaging at 1.5 T or less, regardless of when the injury occurred."

"Nonferromagnetic ballistic projectiles do not undergo movement or heating during MRI, and the imaging modality can be performed when medically necessary without undue risk and with limited artifact susceptibility on the resulting images, even when the projectile is in or near a vital structure," the authors concluded.

What happens in the brain when our conscious awareness fades during general anesthesia and normal sleep? Finnish scientists studied this question with novel experimental designs and functional brain imaging. They succeeded in separating the specific changes related to consciousness from the more widespread overall effects, and discovered that the effects of anesthesia and sleep on brain activity were surprisingly similar. These novel findings point to a common central core brain network fundamental for human consciousness.

Explaining the biological basis of human consciousness is one of the greatest challenges of science. While the loss and return of consciousness, as regulated by drugs or physiological sleep, have been employed as model systems in the study of human consciousness, previous research results have been confounded by many experimental simplifications.

"One major challenge has been to design a set-up, where brain data in different states differ only in respect to consciousness. Our study overcomes many previous confounders, and for the first time, reveals the neural mechanisms underlying connected consciousness," says Harry Scheinin, Docent of Pharmacology, Anesthesiologist, and the Principal Investigator of the study from the University of Turku, Finland.

A new and innovative experimental set-up

Brain activity was measured with positron emission tomography (PET) imaging during different states of consciousness in two separate experiments in the same group of healthy subjects. Measurements were made during wakefulness, escalating and constant levels of two anesthetic agents, and during sleep-deprived wakefulness and Non-Rapid Eye Movement (NREM) sleep.

In the first experiment, the subjects were randomly allocated to receive either propofol or dexmedetomidine (two anesthetic agents with different molecular mechanisms of action) at stepwise increments until the subjects no longer responded. In the sleep study, they were allowed to fall asleep naturally. In both experiments, the subjects were roused to achieve rapid recovery to a responsive state, followed by immediate and detailed interviews of subjective experiences from the preceding unresponsive period. Unresponsive anesthetic states and verified NREM sleep stages, where a subsequent report of mental content included no signs of awareness of the surrounding world, indicated a disconnected state in the study participants. Importantly, the drug dosing in the first experiment was not changed before or during the shift in the behavioral state of the subjects.

"This unique experimental design was the key idea of our study and enabled us to distinguish the changes that were specific to the state of consciousness from the overall effects of anesthesia," explains Annalotta Scheinin, Anesthesiologist, Doctoral Candidate and the first author of the paper.

Researchers discovered a common central core brain network

When PET images of responsive and connected brains were compared with those of unresponsive and disconnected, the scientists found that activity of the thalamus, cingulate cortices and angular gyri were affected independently of the used anesthetic agent, drug concentration and direction of change in the state of consciousness (see figure). Strikingly analogous findings were obtained when physiological sleep was compared with sleep-deprived wakefulness. Brain activity changes were much more extensive when the disconnected states were compared with a fully awake state. State-specific findings were thus distinct and separable from the overall effects of drug-induced anesthesia and natural sleep, which included widespread suppression of brain activity across cortical areas.

These findings identify a central core brain network that is fundamental for human consciousness.

"General anesthesia seems to resemble normal sleep more than has traditionally been thought. This interpretation is, however, well in line with our recent electrophysiological findings in another anesthesia study," says Harry Scheinin.

Subjective experiences are common during general anesthesia

Interestingly, unresponsiveness rarely denoted unconsciousness (i.e., total absence of subjective experiences), as most participants reported internally generated experiences, such as dreams, in the interviews. This is not an entirely new finding as dreams are commonly reported by patients after general anesthesia.

"However, because of the minimal delay between the awakenings and the interviews, the current results add significantly to our understanding of the nature of the anesthetic state. Against a common belief, full loss of consciousness is not needed for successful general anesthesia, as it is sufficient to just disconnect the patient's experiences from what is going on in the operating room," explains Annalotta Scheinin.

The new study sheds light on the fundamental nature of human consciousness and brings new information on brain functions in intermediate states between wakefulness and complete unconsciousness. These findings may also challenge our current understanding of the essence of general anesthesia.

A fascinating substance with unique properties, ice has intrigued humans since time immemorial. Unlike most other materials, ice at very low temperature is not as ordered as it could be. A collaboration between the Scuola Internazionale Superiore di Studi Avanzati (SISSA), the Abdus Salam International Centre for Theoretical Physics (ICTP), the Institute of Physics Rosario (IFIR-UNR), with the support of the Istituto Officina dei Materiali of the Italian National Research Council (CNR-IOM), made new theoretical inroads on the reasons why this happens and on the way in which some of the missing order can be recovered. In that ordered state the team of scientists have described a relatively obscure and yet fundamental property of very low temperature ice, ferroelectricity. The results, published in PNAS, are likely to extend to ice surfaces, a possibility that could be relevant to the agglomeration of ice particles in interstellar space.

"In an ideally ordered piece of ice the hydrogen atoms of each water molecule should point in the same direction, like soldiers in a platoon looking in front of them," explains Alessandro Laio, physicist of SISSA and ICTP. "If that was the case, ice would exhibit a macroscopic electric polarization ? it would be ferroelectric. Instead, water molecules in ice, even at very low temperature, behave like unruly soldiers, and all look in different directions."

This anomalous behaviour, discovered experimentally in the 1930s, was immediately and famously explained by Linus Pauling: the lack of discipline is an effect of the 'ice rule' constraint ? every oxygen atom should at any moment possess two and only two protons to make it H2O. The difficult kinetics created by that constraint causes the ordering process to become infinitely slow, as in a platoon where each soldier had four neighbours and had to keep two hands on the shoulders of two of them.

"Were it not for impurities or defects, which turned out to play a revealing role, one would still today not know whether proton order and ferroelectricity of bulk crystalline ice is a real possibility or a figment of the imagination, since neither experiments nor simulations could overcome the ice rule-generated kinetic slowdown," points out Erio Tosatti, physicist of SISSA, ICTP and CNR-IOM Democritos.

Impurities, such as one KOH replacing H2O, are in fact known to allow the ordering process to nucleate and ice to turn ordered and ferroelectric at very low temperature, although only partly and sluggishly. Once again, the 'ice rule' was suspected to be behind the sluggishness of this process, but exactly how that worked was not really known.

Together with Jorge Lasave and Sergio Koval of the IFIR-UNR in Argentina, both of them ICTP associate members, Alessandro Laio and Erio Tosatti designed a theoretical model and a strategy to explain the behaviour of both pure and doped ice.

"According to this model," the scientists explain, "once an impurity is introduced inside an initial non-equilibrium low temperature disordered state, it acts as a seed for the ordered phase, but in a peculiar manner: not all the 'soldiers' around the impurity start looking in the correct direction, but only those in front or behind the impurity. Thus, at the end of the process only a string of soldiers inside the platoon will become ordered." This highly atypical process has many of the characteristics that can explain the sluggish and incomplete onset of ferroelectric order in real doped ice.

"Although the study is restricted for now to bulk ice," Tosatti and Laio conclude, "the mechanism highlighted is likely to extend to ice surfaces, where strings of ordered protons could nucleate at low temperatures, explaining a long known small amount of local ferroelectric polarization, a phenomenon also mentioned as possibly relevant to the agglomeration of ice particles in interstellar space."

Osaka, Japan - Researchers at Osaka University synthesized twisted molecular wires just one molecule thick that can conduct electricity with less resistance compared with previous devices. This work may lead to carbon-based electronic devices that require fewer toxic materials or harsh processing methods.

Organic conductors, which are carbon-based materials that can conduct electricity, are an exciting new technology. Compared with conventional silicon electronics, organic conductors can be synthesized more easily, and can even be made into molecular wires. However, these structures suffer from reduced electrical conductivity, which prevents them from being used in consumer devices. Now, a team of researchers from The Institute of Scientific and Industrial Research and the Graduate School of Engineering Science at Osaka University has developed a new kind of molecular wire made from oligothiophene molecules with periodic twists that can carry electric current with less resistance.

Molecular wires are composed by several-nanometer-scale long molecules that have alternating single and double chemical bonds. Orbitals, which are states that electrons can occupy around an atom or molecule, can be localized or extended in space. In this case, the pi orbitals from individual atoms overlap to form large "islands" that electrons can hop between. Because electrons can hop most efficiently between levels that are close in energy, fluctuations in the polymer chain can create energy barriers. "The mobility of charges, and thus the overall conductivity of the molecular wire, can be improved if the charge mobility can be improved by suppressing such fluctuations," first author Yutaka Ie says.

The overlap of pi orbitals is very sensitive to the rotation of the molecule. Adjacent segments of the molecule that are aligned in the same plane form one large hopping site. By purposely adding twists to the chain, the molecule is broken into nanometer-sized sites, but because they are close in energy, the electrons can hop easily between them. This was accomplished by inserting a 3,3'-dihexyl-2,2'-bithiophene unit after every stretch of 6 or 8 oligothiophene units.

The team found that, overall, creating smaller islands that are closer in energy maximized the conductivity. They also measured how temperature affects the conductivity, and showed that it was indeed based on electron hopping. "Our work is applicable to single-molecule wires, as well as organic electronics in general," senior author Yoshikazu Tada says. This research may lead to improvements in conductivity that will allow nanowires to become incorporated into a wide array of electronics, such as tablets or computers.

In a study that looked at suicide deaths during 2020's first wave of the COVID-19 pandemic in Maryland, Johns Hopkins Medicine researchers found that, contrary to general predictions of suicides skyrocketing, suicides in the overall population actually dropped, relative to previous years. However, the researchers also discovered that suicide deaths increased dramatically among Black Marylanders during the same period.

The researchers say that their findings, published Dec. 16, 2020, in JAMA Psychiatry, highlight the importance of timely identification of high-risk groups and vulnerable populations to reduce suicide numbers.

Black Americans have been disproportionately affected by the COVID-19 pandemic, underlining long-standing health and social inequities. "Looking at suicide trends by race emphasizes the economic divide we're seeing in America and unfortunately, that divide also is a racial one," says Paul Nestadt, M.D., assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.

According to Nestadt, the increase in suicides among Black Marylanders -- during the period when COVID-19 deaths peaked and the state was locked down -- could be reflective of a socioeconomic divide. In comparison, he adds, the unexpected decrease in suicides in white Marylanders could be due to greater capacity for remote work or benefit from economic relief efforts.

"I think we're all in this COVID-19 storm together, but not everyone is having the same experience," says Nestadt. "Folks who are in places of economic privilege have been able to continue working more or less remotely, to take time off for themselves, reconnect with family, start a new hobby and so on, but it's a very different story for people working in service industry jobs."

In their study, the researchers looked at suicide deaths from Jan. 1 through July 7, 2020. The data were divided into three periods: a pre-COVID-19 period 1 (Jan. 1 to March 4, 2020); a "progressive closure" (lockdown) period 2 (March 5 to May 7, 2020); and a "progressive reopening" period 3 (May 8 to July 7, 2020). Daily suicide mortality was divided by race and compared with the same periods, from 2017 through 2019.

During period 1, daily suicide mortality did not differ from the same period in 2017 through 2019 for either race, and, in period 3, the rates did not differ for Black residents compared with previous years. However, period 2 daily suicide deaths among Blacks increased by 94% and decreased 45% among whites, compared with the same period in 2017 through2019.

"The implications of our findings are more far-reaching than just suicidology," says Nestadt. "It should help policymakers recognize the importance of things like economic relief and increasing access to equal care, so that there's an end to such disproportionate deaths."

Nestadt says further research is needed to characterize these trends. As continuing pandemic restrictions drive public health priorities, he says, policy interventions and targeted resource allocation are needed to mitigate disparities affecting Black Americans.

Big bumblebees take time to learn the locations of the best flowers, new research shows.

Meanwhile smaller bumblebees - which have a shorter flight range and less carrying capacity - don't pay special attention to flowers with the richest nectar.

University of Exeter scientists examined the "learning flights" which most bees perform after leaving flowers.

Honeybees are known to perform such flights - and the study shows bumblebees do the same, repeatedly looking back to memorise a flower's location.

"It might not be widely known that pollinating insects learn and develop individual flower preferences, but in fact bumblebees are selective," said Natalie Hempel de Ibarra, Associate Professor at Exeter's Centre for Research in Animal Behaviour.

"On leaving a flower, they can actively decide how much effort to put into remembering its location.

"The surprising finding of our study is that a bee's size determines this decision making and the learning behaviour."

In the study, captive bees visited artificial flowers containing sucrose (sugar) solution of varying concentrations.

The larger the bee, the more its learning behaviour varied depending on the richness of the sucrose solution.

Smaller bees invested the same amount of effort in learning the locations of the artificial flowers, regardless of whether sucrose concentration was high or low.

"The differences we found reflect the different roles of bees in their colonies," said Professor Hempel de Ibarra.

"Large bumblebees can carry larger loads and explore further from the nest than smaller ones.

"Small ones with a smaller flight range and carrying capacity cannot afford to be as selective, so they accept a wider range of flowers.

"These small bees tend to be involved more with tasks inside the nest - only going out to forage if food supplies in the colony are running low."

The study was conducted in collaboration with scientists from the University of Sussex.

The bees were observed in greenhouses at the University of Exeter's award-winning Streatham Campus, and Professor Hempel de Ibarra thanked the university's Grounds and Gardens team for their continued support.

The study was funded by the Leverhulme Trust.

The paper, published in the journal Current Biology, is entitled: "Small and large bumblebees invest differently when learning about flowers."

What The Viewpoint Says: This Viewpoint reviews the potential neurologic consequences of any restriction of blood flow or oxygen to the brain and calls for an examination of the safety and appropriateness of the use of neck restraints by law enforcement.

Authors: Altaf Saadi, M.D., M.Sc., of Mass General Brigham, 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/jamaneurol.2020.4669)

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

What The Study Did: Researchers looked at whether health outcomes of white citizens living in the richest U.S. counties were better than that of average individuals in other developed countries.

Authors: Ezekiel J. Emanuel, M.D., Ph.D., of the University of Pennsylvania in Philadelphia, 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/jamainternmed.2020.7484)

Editor's Note: The article includes conflicts of interest 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.

A fast, green and one-step method for producing porous carbon spheres, which are a vital component for carbon capture technology and for new ways of storing renewable energy, has been developed by Swansea University researchers.

The method produces spheres that have good capacity for carbon capture, and it works effectively at a large scale.

Carbon spheres range in size from nanometers to micrometers. Over the past decade they have begun to play an important role in areas such as energy storage and conversion, catalysis, gas adsorption and storage, drug and enzyme delivery, and water treatment.

They are also at the heart of carbon capture technology, which locks up carbon rather than emitting it into the atmosphere, thereby helping to tackle climate change.

The problem is that existing methods of making carbon spheres have drawbacks. They can be expensive or impractical, or they produce spheres that perform poorly in capturing carbon. Some use biomass, making them more environmentally friendly, but they require a chemical to activate them.

This is where the work of the Swansea team, based in the University's Energy Safety Research Institute, represents a major advance. It points the way towards a better, cleaner and greener way of producing carbon spheres.

The team adapted an existing method known as CVD - chemical vapour deposition. This involves using heat to apply a coating to a material. Using pyromellitic acid as both carbon and oxygen source, they applied the CVD method at different temperatures, from 600-900 °C. They then studied how efficiently the spheres were capturing CO2 at different pressures and temperatures

They found that:

800 °C was the optimum temperature for forming carbon spheres

The ultramicropores in the spheres that were produced gave them a high carbon capture capacity at both atmospheric and lower pressures

Specific surface area and total pore volume were influenced by the deposition temperature, leading to an appreciable change in overall carbon dioxide capture capacity

At atmospheric pressure the highest CO2 adsorption capacities, measured in millimolars per gram, for the best carbon spheres, were around 4.0 at 0 °C and 2.9 at 25 °C.

This new approach brings several advantages over existing methods of producing carbon spheres. It is alkali-free and it doesn't need a catalyst to trigger the shaping of the spheres. It uses a cheap and safe feedstock which is readily available in the market. There is no need for solvents to purify the material. It is also a rapid and safe procedure.

Dr Saeid Khodabakhshi of the Energy Safety Research Institute at Swansea University, who led the research, said:

"Carbon spheres are fast becoming vital products for a green and sustainable future. Our research shows a green and sustainable way of making them.

We demonstrated a safe, clean and rapid way of producing the spheres. Crucially, the micropores in our spheres means they perform very well in capturing carbon.
Unlike other CVD methods, our procedure can produce spheres at large scale without relying on hazardous gas and liquid feedstocks.

Carbon spheres are also being examined for potential use in batteries and supercapacitors. So in time, they could become essential to renewable energy storage, just as they already are for carbon capture."

In a series of commissions awarded by the Federal Joint Committee (G-BA) to the Institute for Quality and Efficiency in Health Care (IQWiG), the question is whether for certain surgical procedures, a correlation can be shown between the volume of services provided per hospital and the quality of treatment results. IQWiG's rapid report on heart transplantations is now available.

According to the findings, a positive correlation can be inferred between the volume of services and the quality of treatment results for heart transplantations in adults: In hospitals with larger case volumes, fewer of the transplanted patients die, both in timely association with the intervention and in respect of total mortality. However, the three observational studies included in the report show only a low informative value of results.

318 heart transplantations in Germany in 2018

Heart transplantation may be medically indicated in the event of severe cardiac failure that, despite the use of all other treatment options, is progressing and endangers the life of the patient concerned or extremely restricts his or her quality of life. After transplantation, lifelong immunosuppression is required to prevent organ loss due to transplant rejection. In the Eurotransplant region, the average survival time after surgery is currently eleven years.

According to the Eurotransplant statistics, a total of 318 heart transplantations were performed in Germany in 2018. The demand was considerably higher, but could not be met due to the shortage of donor organs.

For heart transplantations in adults in Germany, the G-BA has not yet established minimum volume standards for the provision of services in hospitals.

Positive correlation between case volumes and survival probabilities

In its worldwide literature searches, IQWiG identified three observational studies containing usable data for investigating the correlation between volume of services and quality of treatment results for heart transplantations. All three studies analyse this correlation exclusively at the hospital level and not at the level of the surgeons involved in the transplantation.

For the outcome category "mortality", data are available for two outcomes: "all-cause mortality" and "intra- and perioperative mortality" (mortality before, during and immediately after surgery). For both outcomes, a reduction in the number of deaths in hospitals with more heart transplants per year can be inferred from the data.

For the outcomes "in-hospital mortality", "need for retransplantation", "health-related quality of life" (including activities of daily living and dependence on the help of others), as well as "length of hospital stay", the studies evaluated did not contain any data. Data were available for the outcome "adverse effects of treatment", but no statistically significant results could be inferred.

For heart transplantations in adults, IQWiG found no meaningful studies examining the effects of specific minimum case volumes introduced into the health care system on the quality of treatment results.