Brain

A team of researchers at the Department of Energy's Oak Ridge and Argonne national laboratories has performed the first room-temperature X-ray measurements on the SARS-CoV-2 main protease -- the enzyme that enables the virus to reproduce.

The X-ray measurements mark an important first step in the researchers' ultimate goal of building a comprehensive 3D model of the enzymatic protein. The model will be used to advance supercomputing simulations aimed at finding drug inhibitors to block the virus's replication mechanism and help end the COVID-19 pandemic. Their research results are publicly available and have been published in the journal Nature Communications.

SARS-CoV-2 is the virus that causes the disease COVID-19. The virus reproduces by expressing long chains of proteins that must be cut into smaller lengths by the protease enzyme.

"The protease is indispensable for the virus life-cycle. The protein is shaped like a valentine's heart, but it really is the heart of the virus that allows it to replicate and spread. If you inhibit the protease and stop the heart, the virus cannot produce the proteins that are essential for its replication. That's why the protease is considered such an important drug target," said ORNL's Andrey Kovalevsky, corresponding author. While the structure is known from cryogenically preserved crystals, "This is the first time the structure of this enzyme has been measured at room temperature, which is significant because it's near the physiological temperature where the cells operate."

Building a complete model of the protein structure requires identifying each element within the structure and how they are arranged. X-rays are ideal for detecting heavy elements such as carbon, nitrogen and oxygen atoms. Because of the intensity of the X-ray beams at most large-scale synchrotron facilities, biological samples typically must be cryogenically frozen to around 100 K, or approximately minus 280 degrees Fahrenheit, to withstand the radiation long enough for data to be collected.

To extend the lifetime of the crystallized protein samples and measure them at room temperature, ORNL researchers grew crystals larger than required for synchrotron cryo-studies and used an in-house X-ray machine that features a less intense beam.

"Growing protein crystals and collecting data is a tedious and time-consuming process. In the time it typically takes to prepare and ship the sample to a synchrotron, we were able to grow the crystals, take the measurements and begin analyzing the data," said ORNL's Daniel Kneller, the study's first author. "And, when there's a pandemic with many scientists mobilizing to study this problem, there's not a day to spare."

The protease enzyme consists of chains of amino acids with a repeating pattern of nitrogen-carbon-carbon atoms that form the backbone of the protein. Side groups of the amino acid building blocks, or "residues", extend from each of the central backbone carbon atoms. The enzyme is folded into a specific 3D shape, creating special pockets where a drug molecule would attach.

The study revealed significant structural disparities between the orientations of the backbone and some of the residues in the room-temperature and cryogenic samples. The research suggests that freezing the crystals may introduce structural artifacts that could result in a less accurate understanding of the protease structure.

The team's results are being shared with researchers, led by ORNL-University of Tennessee Governor's Chair Jeremy Smith, who are conducting drug docking simulations using Summit at ORNL -- the nation's fastest supercomputer.

"What researchers are doing on Summit is taking known drug compounds and trying to computationally bind them to the main protease for drug repurposing, as well as looking for new leads into other potential drug candidates," said ORNL corresponding author Leighton Coates. "Our room temperature data is being used to build a more accurate model for those simulations and improve drug design activities."

The researchers' next step in completing the 3D model of the SARS-CoV-2 main protease is to use neutron scattering at ORNL's High Flux Isotope Reactor and the Spallation Neutron Source. Neutrons are essential in locating the hydrogen atoms, which play a critical role in many of the catalytic functions and drug design efforts.

The protease plasmid DNA used to make the enzyme was provided by Argonne's Structural Biology Center at the Advanced Photon Source. Crystallization of the proteins used in the X-ray scattering experiments was performed at ORNL's Center for Structural and Molecular Biology.

In addition to Kovalevsky, Kneller, and Coates, the paper's authors are ORNL's Gwyndalyn Phillips, Hugh M. O'Neill and Paul Langan; and Argonne's Robert Jedrzejczak, Lucy Stols and Andrzej Joachimiak.

It is not unusual to come across headlines about pollution or global warming and find that they reach different conclusions depending upon the data source.

Researchers at Washington University in St. Louis used a harmonized approach, incorporating data from multiple satellites and ground monitors with computer modeling to compile a comprehensive, consistent map of pollution across the globe. Their data spans 1998-2018, providing a current picture of the state of the world's air quality that reveals some surprises, both for better and for worse.

The research was led by Melanie Hammer, a postdoctoral research fellow in the lab of Randall Martin, professor of energy, environmental and chemical engineering in the McKelvey School of Engineering.

Results of their study that looked at PM2.5 -- tiny particles that are able to make their way deep into a person's respiratory system -- were published June 3 in Environmental Science & Technology.

"Prior studies that look at long-term PM2.5 haven't used data as recent as we have," Hammer said. Older data can't capture the results of many programs aimed at curbing pollution -- even if they have been in effect for nearly a decade.

That turned out to be the case in China, where a significant drop in pollution in the recent past was the result of strategies begun in earnest around 2011. Other data sets don't capture the drop.

And in India -- another area of concern -- the story was not as positive. "It seems there's a bit of a plateau of PM2.5 levels," Hammer said. Though still, levels are not rising as steeply as other reports may suggest.

PM2.5 refers to the size of particles -- 2.5 microns. These tiny particles are created in nature, but also by human activities, including some manufacturing processes, car exhaust and the use of wood-burning cookstoves.

It's not easy to measure the amount of PM2.5 on the ground because there isn't any kind of comprehensive monitoring network covering the globe. North America and Europe have extensive monitoring systems, as does China. But, Martin said, "There are large gaps in ground-based monitoring. People can be living hundreds of kilometers away from monitors."

To develop a comprehensive pollution map, then, ground-based monitors are simply insufficient.

To capture a global snapshot, Martin's team started with satellite images of columns of atmosphere that spanned the ground to the edge of space. Using the established GEOS-Chem model, which simulates atmospheric composition, they could infer how much PM2.5 should be on the ground, at the bottom of any given column.

When comparing the predictions to actual levels measured by ground monitors, the agreement was striking. In fact, Martin said, "It's the best level of agreement found to date."

But the researchers still went a step further.

The agreement was great, but not perfect. So Hammer added the differences between the observed and predicted amounts of PM2.5 and expanded the ground-based predictions across the globe, filling in the massive gaps between monitors.

This extra step brought the observed and predicted levels of PM2.5 from 81% to 90% agreement.

Once they were able to take a good look at the most recent pollution levels around the world, the researchers saw some stark changes from previous trends. Particularly in China.

"We're used to seeing just large, increasing trends in pollution," Hammer said. But in China, "What we found, from 2011 to 2018, is that there actually is a particularly large negative trend."

Elsewhere in Asia, the picture wasn't as positive.

While pollution levels did not seem to be increasing in India, the country seems to be in a plateau phase. "The broad plateau of very high concentrations, to which a large population is exposed, is quite concerning," Martin said. "It affects the health of a billion people."

However, the takeaway from this research can be, on the balance, a hopeful one: It seems to show one possible way forward.

"The data Melanie's analysis reveals is a real success story for air quality controls," Martin said. "It shows they can be remarkably effective at reducing PM2.5." Although scientists have known these controls contain the potential to make an impact, he said, "The changes in China are very dramatic, larger than we have seen anywhere in the world over the observational record.

"It illustrates a real opportunity to improve air quality through effective controls."

Pollution, health around the world

In people already sick with illness such as asthma, PM2.5 can have immediate health consequences. Long-term, however, breathing in these particles carries consequences for everyone.

"PM2.5 is a major public health concern globally," said Melanie Hammer, postdoctoral researcher in the lab of Randall Martin in the McKelvey School of Engineering. "It's important to get accurate exposure estimates to estimate health impacts."

That's why organizations, including World Health Organization and Global Burden of Disease, use data from Martin's lab.

Despite reports that children and young people may be less likely to get coronavirus disease 2019 (COVID-19) than older adults, there may be substantial indirect adverse effects of the disease on their physical and mental health, according to an analysis in CMAJ (Canadian Medical Association Journal). http://www.cmaj.ca/lookup/doi/10.1503/cmaj.201008

"While children and young people seem rarely to be victims of severe COVID-19, we should anticipate that they will experience substantial indirect physical, social and mental health effects related to reduced access to health care and general pandemic control measures," says Dr. Neil Chanchlani, University of Exeter, United Kingdom.

The authors describe a range of potential adverse effects and contributing factors as well as mitigation strategies for health care providers and health systems.

Adverse effects include

Delays in seeking care for non-COVID-19-related illnesses, which can lead to severe illness and even death

Widespread delays or omissions of routine childhood vaccinations, which can threaten herd immunity

Missed detection of delayed development milestones, which are usually identified during routine child health checks

"Delays in bringing children and young people to medical attention may be due to parental fears of exposure to COVID-19 in hospitals or on public transit, lack of childcare for other children, lack of access to primary care due to closures, or changes to hospital visitation policies," says Dr. Peter Gill, The Hospital for Sick Children (SickKids), Toronto, Canada.

However, reduced social contact because of travel and quarantine restrictions may reduce transmission of other commonly acquired illnesses.

Factors affecting social and mental health

Families living in inadequate or crowded housing may experience heightened stress or conflict, which can affect the mental and physical health of children. Refugees, some Indigenous communities and low-income families living with financial strain and food insecurity are particularly vulnerable.

Restrictions and cancellations of child welfare visits to at-risk families can reduce visits of birth parents and children in foster care, leading to harms.

Forced isolation and economic uncertainty may lead to increases in family violence, contributing to mental and physical trauma.

School cancellations may heighten food insecurity for children who depend on meal programs and increase vulnerablity with the loss of school as a safe place.

Lost social interaction and lack of structured routines may lead to increased screen time, decreased physical activity, lack of concentration, anxiety and early depression.

Reductions in support for children with additional health care needs, such as those with developmental delays, can lead to delayed diagnosis and support.

""We need to better understand what goes into the decisions families make regarding the complex needs of their children during this pandemic and how we can better support them," says Francine Buchanan, a coauthor and Research Patient & Family Engagement Coordinator at SickKids. "Both practical and personal considerations need to be taken into account."

The authors suggest several mitigation strategies, including

Clear communication that health services are open for children and young people if needed

Alternative ways for hospital-based programs to deliver vital services, such as different locations or online

Adequate data collection to assess readiness to return to school, how children and young people contract and spread COVID-19, and hospital use and admission.

"We owe it to our children and young people to proactively measure the COVID-19 pandemic's indirect effects on their health and to take steps to mitigate the collateral damage," urge the authors.

"Addressing the indirect effects of COVID-19 on the health of children and young people" is published June 25, 2020.

Exposure to wildfire smoke affects the body's respiratory and cardiovascular systems almost immediately, according to new research from the University of British Columbia's School of Population and Public Health.

In a study published today in Environmental Health Perspectives, researchers found that exposure to elevated levels of fine particulate matter during wildfire seasons in British Columbia was associated with increased odds of ambulance dispatches related to respiratory and cardiovascular conditions, with increased ambulance dispatches occurring within only one hour after exposure. Among people with diabetes, the researchers found that the odds of health complications increased within 48 hours following exposure to wildfire smoke.

"We have long known about the harmful health effects of wildfire smoke," says Jiayun Angela Yao, the study's lead author who conducted this research while completing her PhD in the UBC School of Population and Public Health. "But it's alarming to see just how quickly fine particular matter seems to affect the respiratory and cardiovascular system. And the acute effects for people with diabetes is relatively new to us."

Particulate matter, also called particle pollution, is made up of tiny pieces of dust, dirt, and smoke in the air. While larger particles can irritate the eyes and throat, fine particles are more dangerous as they can reach deep parts of the lungs and even enter the bloodstream.

For the study, the researchers used statistical modelling to evaluate the relationship between ambulance dispatches, paramedic assessments and hospital admissions related to respiratory, circulatory and diabetic conditions with levels of fine particulate matter during wildfire seasons in B.C. from 2010 to 2015. A total of more than 670,000 ambulance dispatch calls from more than 500,000 individuals were included in the study.

The researchers say this study adds to the limited previous evidence on how quickly exposure to wildfire smoke can have harmful health effects. The findings are especially timely now during the COVID-19 pandemic, as air pollution from wildfire smoke can make viral infections affecting the respiratory and cardiovascular systems even more severe.

With wildfire season quickly approaching in B.C., the researchers say their research underscores the need for rapid public health actions to limit exposure to wildfire smoke.

"It is vital that everyone start preparing for wildfire smoke events to ensure that they are ready, especially since COVID-19 still a serious public health threat in B.C.," says Yao. "Anyone with pre-existing heart and lung disease and diabetes is especially vulnerable and should consider purchasing air cleaners, and ensuring that they have adequate supplies of medication at home."

RESEARCH TRIANGLE PARK, N.C. -- Two U.S. Army research projects advance quantum networking, which will likely play a key role in future battlefield operations.

Quantum networks will potentially deliver multiple novel capabilities not achievable with classical networks, one of which is secure quantum communication. In quantum communication protocols, information is typically sent through entangled photon particles. It is nearly impossible to eavesdrop on quantum communication, and those who try leave evidence of their tampering; however, sending quantum information via photons over traditional channels, such as fiber-optic lines, is difficult - the photons carrying the information are often corrupted or lost, making the signals weak or incoherent.

In the first project, the University of Chicago research team, funded and managed by the U.S. Army's Combat Capability Development's Army Research Laboratory's Center for Distributed Quantum Information, demonstrated a new quantum communication technique that bypasses those traditional channels. The research linked two communication nodes with a channel and sent information quantum-mechanically between the nodes--without ever occupying the linking channel.

"This result is particularly exciting not only because of the high transfer efficiency the team achieved, but also because the system they developed will enable further exploration of quantum protocols in the presence of variable signal loss," said Dr. Sara Gamble, program manager at the lab's Army Research Office and co-manager of the Center for Distributed Quantum Information. "Overcoming loss is a key obstacle in realizing robust quantum communication and quantum networks."

The research, published in the journal Physical Review Letters, developed a system that entangled two communication nodes using microwave photons--the same photons used in cell phones--through a microwave cable. For this experiment, they used a microwave cable about a meter in length. By turning the system on and off in a controlled manner, they were able to quantum-entangle the two nodes and send information between them--without ever having to send photons through the cable.

"We transferred information over a one-meter cable without sending any photons to do this, a pretty unusual achievement," said Dr. Andrew Cleland, the John A. MacLean Sr. Professor of Molecular Engineering at Pritzker Molecular Engineering at University of Chicago and a senior scientist at Argonne National Laboratory. "In principle, this would also work over a much longer distance. It would be much faster and more efficient than systems that send photons through fiber-optic channels."

Though the system has limitations, it must be kept very cold, at temperatures a few degrees above absolute zero, the researchers said it could also potentially work at room temperature with atoms instead of photons.

The team is now conducting experiments that would entangle several photons together in a more complicated state, which could ultimately enable enhanced quantum communication protocols and capabilities.

Entangled particles aren't just limited to photons or atoms, however. In a second paper published June 12 in the peer-reviewed journal Physical Review X, the same Chicago team entangled two phonons--the quantum particle of sound--for the first time.

Using a system built to communicate with phonons, similar to the photon quantum communication system, the team entangled two microwave phonons, which have roughly a million times higher pitch than can be heard with the human ear.

Once the phonons were entangled, the team used one of the phonons as a herald, which was used to affect how their quantum system used the other phonon. The herald allowed the team to perform a so-called quantum eraser experiment, in which information is erased from a measurement, even after the measurement has been completed.

"Phonons give you a much bigger time window to do things and relieve some of the challenges in doing a quantum eraser experiment," Cleland said.

Though phonons have a lot of disadvantages over photons--for example, they tend to be shorter-lived--they interact strongly with a number of solid-state quantum systems that may not interact strongly with photons. As a result, phonons could provide a better way to couple to these systems.

This coupling is a critical capability for many quantum networking applications, and may also benefit other quantum information science applications such as quantum computing. Additionally, the wavelengths of phonons are shorter than those of photons for the same frequency, potentially enabling smaller quantum circuits.

"Together, these experiments provide multiple avenues for future research into how we construct quantum networks that function in non-ideal environments, and reliably transfer quantum information between systems," said Dr. Fredrik Fatemi, researcher at the laboratory and co-manager of the Center for Distributed Quantum Information. "Both are critically important for developing future quantum technologies."

Scientists working at the Department for Functional Nanomaterials at the Institute of Nuclear Physics of the Polish Academy of Sciences designed and synthesized a functional ternary Pt/Re/SnO2/C catalyst as an anode material in a direct ethanol fuel cell. It was possible by synthesizing platinum, rhenium and tin oxide nanoparticles of a spherical shape and ensuring physical contact between them. This finding will lead to the production of more efficient, greener and cheaper fuel cell catalysts.

One of the biggest challenges modern science faces today is the development of new, efficient and environmentally friendly technologies for converting chemical energy into electricity. Ethanol fuel cells are becoming such an alternative source of energy. Ethanol seems to be the ideal fuel of the future, because, compared to methanol or hydrogen, it has significantly lower toxicity, poses no problems or threats in storage and transport, and can also be obtained from biomass. However, the catalysts used in direct ethanol fuel cells (DEFCs) are not sufficiently effective and mainly produce by-products instead of the expected ethanol final product, such as carbon dioxide. These substances strongly adsorb on the surface of platinum, which is the most commonly used catalyst. As a result, they block the catalytically active sites preventing a further reaction, thus causing so-called catalyst poisoning and lowering the overall efficiency of the device. Therefore, the key challenge is to develop the appropriate type of catalysts.

Platinum and platinum-based catalysts are widely used in DEFCs. Ethanol adsorption occurs on the platinum surface, which triggers its oxidation reaction (Ethanol Oxidation Reaction - EOR). Poisoning problems can be solved by adding other components to platinum, such as metallic rhodium and tin oxides, which improve the efficiency of the EOR because they play a unique and individual role in the ethanol oxidation pathway. The function of rhodium is to split the carbon-carbon bond in the ethanol molecule, while tin dioxide provides hydroxyl groups for oxidizing intermediates and helps unblock the inactive surface of platinum. In addition to rhodium and tin, elements such as Ru, Ir, Cu, Fe, Co, Ni and many others are also used. A ternary nanocatalyst containing platinum and rhodium nanoalloys deposited on tin oxide, which is currently considered one of the most efficient and selective configurations in the ethanol oxidation reaction, has also been extensively studied. It is also suggested that physical contact between nanoparticles plays a crucial role.

Scientists from the Department for Functional Nanomaterials at the Institute of Nuclear Physics of the Polish Academy of Sciences, led by Prof. Eng. Magdalena Parlinska-Wojtan, undertook the task of designing and synthesizing a new material, which could play the role of an anode catalyst. For this purpose, they decided to analyze the effect of rhenium, used as one of the three catalyst components, on improving the efficiency of the EOR. Moreover, the researchers assumed that by using intermolecular interactions and electrokinetic potential measurements, it would be possible to assemble the separately synthesized Pt, Re and SnO2 nanoparticles into double and triple combinations to ensure their physical contact. This assembling is possible due to the opposite values of the electrokinetic potential of each type of nanoparticles. While performing stability studies, the researchers also focused on the durability of the catalyst because the degradation of nanocatalyst components is a serious factor limiting the stability and commercialization of catalysts.

"In the first stage of our work, we optimized the processes for obtaining individual nanoparticles: platinum, rhenium and tin oxide, which were intended to be the components of an anode catalyst," says Dr. Eng. Elzbieta Drzymala from IFJ PAN, the leading author of the scientific publication, describing the details of the conducted studies. "Then, using intermolecular interactions, we put individually synthesized nanoparticles together to ensure physical contact between them. In this way, we obtained binary and ternary nanoparticle combinations, which were then deposited on carbon substrates with even distribution to provide ethanol molecules with the best access to active surfaces. The next step was to study the electrochemical properties of selected binary and ternary combinations given their potential use as anode material in ethanol fuel cells. Finally, we compared the results of our work with a commercial platinum catalyst."

The obtained results turned out to be very important and encouraged further research on this type of materials. The catalyst developed by the IFJ PAN group made of Pt, Re and SnO2 nanoparticles can be successfully used as an anode catalyst in DEFCs. Analyzes carried out with transmission electron microscopy (TEM) in combination with EDS spectroscopy confirmed the physical contact between the nanoparticles forming the ternary Pt/Re/SnO2/C catalyst (see figure). It has been experimentally proven by voltammetric techniques that this ternary catalyst exhibits more than ten times higher activity in the ethanol oxidation reaction compared to a commercial platinum catalyst. Besides, it has been shown that the Pt/Re/SnO2/C catalyst features the best stability - after testing, it preserved nearly 96 % of the electrochemically active surface (compared to 12 % for the commercial catalyst). It is also important that the ternary catalyst shows the lowest value of onset potential - the value of the initial oxidation potential is almost 0.3 V lower compared to a commercial platinum catalyst. Thus, the use of rhenium as the third component and connecting nanoparticles in such a way that they remain in physical contact generated the desired effect of improving the efficiency of the EOR.

"Our further research will continue to focus on fuel cell catalysts," explains Dr. Eng. Drzymala. "However, going a step further, we would like to solve the economic issues and develop a catalytic system with better or at least comparable properties but without the addition of platinum. I believe that the use of platinum-free nanoparticles decorated with small 2-nanometer SnO2 nanoparticles as components of such a catalyst will bring us closer to creating a fully functional material for the fuel cell anode. I hope that the catalyst without platinum will be synthesized soon at the Department for Functional Nanomaterials at the Institute of Nuclear Physics of the Polish Academy of Sciences."

A new study by researchers at the Johns Hopkins Bloomberg School of Public Health found that the odds of a fatal opioid overdose were 1.5 times higher for individuals with one to two visits to the emergency department for any medical issue than for people with no hospital visits. The researchers also found that individuals with a hospital visit where opioid use disorder was addressed were 2.9 times more likely to die from an overdose over the coming year, compared with other people.

For their analysis, the researchers matched de-identified individual records across five Maryland-based databases that encompassed hospital visits, prescription-drug monitoring, treatment programs, and criminal justice records from 2015. Maryland is one of the first states to have linked records across databases in an attempt to identify those at risk for opioid overdose.

The findings, published online June 24 in JAMA Psychiatry, suggest that risk of an overdose can be accurately predicted by leveraging information found across databases.

Using these linked databases, the researchers found that individuals who were recently released from prison were more than four times likely to experience a fatal overdose. Being on probation and parole were also associated with double the odds of an overdose.

Among demographic predictors of opioid overdose, men had 2.4 higher odds of fatal overdose and 1.4 times higher odds of nonfatal overdose compared to women.

"A lot of the individuals with the highest risk for an overdose come in contact with the hospital or prison system," says lead author Brendan Saloner, PhD, associate professor in the Department of Health Policy and Management at the Bloomberg School. "There's a high opportunity in those places to help those individuals and we can save a lot of lives if we focus efforts there."

Between 1999 and 2017, drug overdose deaths in the U.S. quadrupled and two out of three overdose deaths are linked to opioids. Initial reports suggest that during the COVID-19 lockdown period overdoses have dramatically increased in some locales.

Maryland and other states have applied several strategies to curb the opioid epidemic, including expanded treatment for people with opioid use disorder, safer prescribing policies, and harm reduction programs like naloxone distribution that can be administered to reverse an overdose.

The study findings suggest that predictive data analytics could be used to more effectively target these strategies towards those with the greatest risk by identifying groups that could most benefit from intensive support services such as peer counselors.

Maryland is among a handful of states that have built single comprehensive individual-level databases that include major risk factors that affect critical health outcomes, such as opioid overdoses. The merged database paints a far more complete picture than any one of the component parts, with a "lens" that combines medical, public health, and human service perspectives.

In collaboration with the Maryland Department of Health and the state's Health Information exchange, the researchers matched deidentified individual records across five Maryland databases including all-payer hospital discharge data, which includes private insurance as well as Medicare and Medicaid; Maryland's prescription drug-monitoring program, a registry of controlled prescriptions; behavioral treatment programs that participate in Medicaid; as well as criminal justice records for property or drug-related offenses.

The study sample of more than 2.29 million linked records, included Maryland residents ages 18-80 with one or more records in any of the four databases in 2015. Using statistical modeling, the researchers predicted opioid-related overdoses in 2016 from variables derived from 2015. The researchers tracked fatal opioid overdoses using medical examiner records and nonfatal opioid overdoses from emergency department or inpatient hospital-settings data.

Of the study sample, approximately 43 percent were male and 53 percent were aged 50 or younger. In 2016, 0.05 percent of the sample, or approximately 1,204 individuals, experienced a fatal opioid overdose and 0.37 percent, or approximately 8,430 individuals, had a nonfatal overdose. In 2015, 63.9 percent of the study sample had hospital records, 32 percent had one to two emergency department visits, and 1.2 percent were diagnosed with an opioid use disorder in the hospital.

Approximately two-thirds of the sample (66.8 percent) had records in the prescription drug-monitoring program, but a very small number, only 1.1 percent, had involvement in the criminal justice system. The study drew on a limited criminal justice sample of only individuals with drug or property offenses. About 7.4 percent of the study sample had used behavioral health services.

"The COVID-19 experience has taught us the importance of using linked medical and public health data to identify and respond to health risks on a real-time basis," says the study's senior author Jonathan Weiner, DrPH, co-director of the Center for Population Health Information Technology and professor in the Department of Health Policy and Management. "This study offers evidence that data already in every state's possession can be used to redouble our efforts to help individuals and communities still being decimated by the opioid overdose epidemic."

CORVALLIS, Ore. - Suspended, rotating devices known as "flappers" may be the key to fewer birds flying into power lines, a study by Oregon State University suggests.

The findings by researchers in OSU's College of Agricultural Sciences are important because around the globe both the number of power lines and concern over bird fatalities are on the rise.

Research has documented more than 300 species of birds dying from hitting power lines, with one study estimating that more than 170 million perish annually in the United States and another estimating the global death toll to be 1 billion per year. There's also the problem of power outages that bird strikes can cause.

Conservation managers and utilities many years ago developed flight diverters, basically regularly spaced devices that make the lines more visible, as a step toward reducing the number of birds flying into the lines.

The most common type are the PVC spirals, which are durable and easy to install, but how well they actually work isn't well understood. Though they've been in use for nearly four decades, strike rates remain high for a number of species.

OSU researchers Virginia Morandini and Ryan Baumbusch were part of an international collaboration that compared the effectiveness of three types of flight diverters: yellow PVC spiral; orange PVC spiral; and a flapper model with three orange and red polypropylene blades with reflective stickers.

The flapper hangs from a power line and its blades, 21 centimeters by 6.2 centimeters, rotate around a vertical axis.

The three-year study took place in southern Spain, and almost 54 kilometers of power lines were used in the research. Ten kilometers were marked with yellow spirals, 13 kilometers were marked with orange spirals, another 13 had flappers, and 16 kilometers had no markers, thus serving as a control. All three flight diverter types were spaced every 10 meters.

Field workers combed the area under the lines every 40 days for evidence of birds killed by power lines and found a total of 131 such birds representing 32 species.

The research suggested the flappers were responsible for a 70% lower average death rate compared to the control. The findings also showed the spirals were better than no diverters, but significantly less effective than the flappers.

"Colored PVC spiral is the most commonly used flight diverter by far, but the flapper diverter was the one showing the largest reduction in mortality with the lowest variation across different power lines, habitats and bird communities," Morandini said. "We suggest to consider the flapper as the first choice when installing bird flight diverters, recommending to increase future research in testing its material durability and resistance against vibrations and color loss."

The flappers and PVC spirals have comparable materials and production costs, researchers say, with flappers being easier and faster to install.

That's important because power companies must keep a line discharged during the diverter installation process - losing money because electricity is not flowing through the line - so the time required to install diverters is the most important factor when considering costs.

EL PASO, Texas - A research team from The University of Texas at El Paso has made strides in understanding how memories are formed through the brain mechanisms of fruit flies, findings that could enhance our understanding of brain disorders such as post-traumatic stress disorder and substance addiction, according to an article published in the highly renowned Journal of Neuroscience.

The article, titled "Concerted Actions of Octopamine and Dopamine Receptors Drive Olfactory Learning," focuses on flexible behavioral choices that are shaped by experiences and cognitive memory processes of fruit flies in a laboratory setting. The study was led by Kyung-An Han, Ph.D., professor of biological sciences and director of the Master of Arts in Teaching Science (MATS) program at UTEP; brothers John Martin Sabandal, a UTEP graduate who is currently a doctoral student at Scripps Research Institute in Jupiter, Florida, and Paul Rafael Sabandal, Ph.D., a postdoctoral researcher in Han's laboratory. Martin Sabandal was an undergraduate student in Han's research lab when he performed research that contributed to the study. A former postdoctoral associate, Youngcho Kim, Ph.D., who is currently a faculty member at the University of Iowa Carver College of Medicine, is also a co-author of the study.

The research team identified the actions of the neurotransmitters octopamine and dopamine as a key neural mechanism for associative learning in fruit flies. This is vital for animals to appropriately respond to the cues predicting benefit or harm. If animals cannot promptly learn and remember the cues, they would not be able to survive or have a decent quality of life.

"I am beyond thrilled about this work getting published," John Martin Sabandal said. "We expanded our knowledge about the importance of aminergic signaling for olfactory learning in fruit flies. This represents a significant finding in the invertebrate field since octopamine was previously shown to be only important for positively-reinforced learning. This publication was a culmination of the hard work spent during my undergraduate years at UTEP."

Paul Sabandal said olfactory conditioning in fruit flies has greatly contributed to overall understanding about the mechanisms underlying associative learning and memory. Historically, in fruit flies, dopamine is implicated in both punishment- and reward-based learning while octopamine is widely considered to be essential only for reward.

"This pioneering work serves as an essential framework for future studies to delineate the signals and circuits that shape appropriate behavioral choices important for fitness and survival," he said. "We strongly believe that our study advanced not only the learning and memory field, but may have implications on related disciplines including dementia and addiction."

Han said the study may help enhance our understanding of the brain disorders with anomalous memories such as PTSD (augmented memory on traumatic events), addiction (intensified memory on drug-associated cues) or learning disabilities (impaired memory).

"Many aspects of our behaviors are the representations of our memories that are formed by associating information or stimuli that we experience," Han said. "For example, celebrities are often featured in commercial advertisements, which is because we tend to associate their social status or star power with product values. This is a typical case of classical conditioning for associative learning and memory. Our study tackles the key question of how the association is occurring in the brain using the genetic model Drosophila melanogaster, or fruit flies."

Kim added that fruit flies provided an excellent primer for the research team to uncover their findings.

"Associative learning is a fundamental form of behavioral plasticity," Kim said. "Drosophila provides a powerful system to uncover the mechanisms for learning and memory."

Long-tailed tits actively avoid harmful inbreeding by discriminating between the calls of close family members and non-family members, according to new research from the University of Sheffield.

Inbred animals typically suffer from reduced survival and reproductive success, so incest is usually avoided. But, in species where young stay close to where they were born, relatives are often encountered as potential mates, increasing the risk of harmful inbreeding.

Long-tailed tits often breed close to home, allowing kin to help raise each other's chicks, but also incurring a risk of incest that reduces the reproductive success of offspring.
The research, led by Dr Amy Leedale from the University of Sheffield's Department of Animal and Plant Science, found that despite this risk, close relatives are actively avoided when pairs form each spring.

Long-tailed tits use distinctive calls to recognise close relatives so that they can help raise their offspring. The authors suggest that these calls also explain how the birds avoid inbreeding.

Dr Amy Leedale, who led the research as a PhD student at the University of Sheffield, said: "We recorded the calls of males and females in many pairs of long-tailed tits and found that the calls of breeding pairs were less similar than the calls of close relatives that they could have bred with.
Call similarity within breeding pairs was, instead, similar to that observed among distant relatives or unrelated birds."

Long-tailed tit calls are learned in the nest, when parents, offspring and siblings are closely associated. Call similarity can therefore act as a reliable indicator of close relatedness in adulthood. This study reveals a potential mechanism by which long-tailed tits can avoid harmful inbreeding as well as gaining benefits from cooperating with kin.

Professor Ben Hatchwell, who has led the long-tailed tit project at the University of Sheffield for more than 25 years, said: "This study demonstrates the value of long-term studies of wild animals, allowing us to build pedigrees of known individuals over many generations, and to measure the consequences of behavioural decisions for their reproductive success."

The University of Sheffield's Department of Animal and Plant Sciences is home to one of the biggest communities of whole-organism biologists in the UK. Research covers animals, plants, humans, microbes, evolution and ecosystems, in habitats ranging from the polar regions to the tropics. This work aims to shed new light on the fundamental processes that drive biological systems and help solve pressing environmental problems.

Ultrasound imaging is one of the workhorses in a modern hospital. It hits the trifecta of being relatively cheap, portable, and non-invasive. The ability to cause future parents to get a bit emotional over fetus images is also an appreciated perk. But ultrasound imaging does have its limitations. Its resolution is often limited by the acoustic wavelength, which is rather long, compared to optical wavelengths. This is compounded by the limitations of acoustic transducers: they are typically optimized for a small range of acoustic frequencies, which limits the resolution of time-of-flight type measurements. Then there is the issue of getting sound waves into and out of the body. The large mismatch between the acoustic properties of the human body and air (or a solid microphone) can make for large losses. To overcome this issue, scientists and engineers have come up with some rather creative solutions, like partially immersing the patient in a bath to improve acoustic matching. Being able to place acoustic sources anywhere on the body with good acoustic matching would avoid these problems. But current technology doesn't allow that because the transducers require a bulky power source. Lan and colleagues, reporting in the peer-reviewed open access journal Advanced Photonics, have developed a wireless ultrasound transducer that is efficiently excited by microwaves. The result is a simple oil-filled patch that can be placed anywhere on the body. No batteries, no wires, and no bath. Wire loop induces good vibrationsThe basic principle is based on using microwave absorption to generate sound waves. Microwaves are an excellent compromise between photoacoustic imaging, which has high-resolution but low imaging depth, and traditional ultrasound imaging. Microwaves result in lower resolution compared to optical systems, but the scattering is also much lower, so excitation depth is no longer a problem. But, the body's absorption of microwaves is also very low, so the generated sound waves are very weak.

The absorbed power is proportional to amplitude of the microwaves. A high amplitude microwave will induce a stronger acoustic wave. The unfortunate side effect is that you may inadvertently cook the person you are imaging. To avoid inadvertent cooking, the microwaves should be concentrated just where they are needed. This is what the device that Lan and colleagues have developed does.

The technique relies on the properties of the split ring resonator. A split ring resonator is a wire loop that is broken. When exposed to microwaves, a current flows in the ring. But, because the ring isn't complete, the charge "piles up" at the gap, creating a large voltage between the ends of the wire. This large oscillating voltage means that, just in the gap, the absorbed power is high, and thermo-elastically induced acoustic waves are produced efficiently.

Now, a resonator implies that it is most efficient at a particular frequency of radiation. Split ring resonators are no exception: the resonant frequency is controlled by the diameter of the wire ring and the medium in which it is placed. Lan and colleagues chose a diameter of about 13 mm, which resonates at about 2.3 GHz in air, and 2.5 GHz in oil. But, the more important feature is the bandwidth of the resonator. Here, the researchers face a choice. To increase the amount of absorbed power, it is beneficial to have a resonator that has a very narrow bandwidth. However, to produce very short pulses of sound, the bandwidth needs to be very broad. The researchers ended up with a split ring resonator with a bandwidth of about 200 MHz, about 10-20 times that of a traditional piezoelectric transducer.Conformal wireless resonatorThe flexibility of the split ring resonator was demonstrated by a series of experiments showing that it could be used to generate mixtures of ultrasound frequencies by pulsing the microwave excitation. Acoustic frequencies up to about 2.5 MHz were produced, but, based on the resonance width of the split ring resonator, higher frequencies can likely be produced.

Probably the biggest benefit is that the resonator is just a copper ring. By placing the ring in a plastic envelope with some oil (the oil absorbs the microwaves and matches the acoustic properties of the body), the ring can be placed anywhere on the body and excited remotely. The researchers demonstrate this using a breast phantom. The ring was placed under the breast, and the detection equipment on top. The wirelessly excited ultrasound signals were strong, and the researchers show that as little as 10mW of average power is required to obtain an ultrasound signal.

Now that the proof of principle has been shown, the next step must be to build an imaging system.

NEW YORK, NY (June 23, 2020) -- During the height of the COVID-19 pandemic in New York City, health care workers on the front lines had high levels of acute stress, anxiety, and depression, a study by researchers at Columbia University Irving Medical Center and NewYork-Presbyterian has found.

Levels of stress, anxiety and depression were particularly high among those with the greatest amount of patient contact and interaction.

Among the findings:

More than half had high levels of acute stress.

Nearly half screened positive for depressive symptoms.

One-third had anxiety.

Most had insomnia symptoms and experienced loneliness.

The findings were published online in the journal General Hospital Psychiatry.

"This is the largest study in the United States to document the psychological impact among clinicians working on the front lines at the height of the NYC COVID-19 pandemic," says Marwah Abdalla, MD, assistant professor of medicine in the Center for Behavioral Cardiovascular Health at Columbia University, cardiac intensivist at NewYork-Presbyterian/Columbia University Irving Medical Center, and study leader.

"Our findings confirm what we suspected: Clinicians working in this environment experienced significant levels of acute stress and other psychological effects."

Nurses had highest stress levels

The researchers analyzed data from 657 clinicians at NewYork-Presbyterian/Columbia University Irving Medical Center who were screened for stress, anxiety, and depression symptoms between April 9 and April 24 during the peak of the pandemic in New York City. More than half (375) of respondents were nurses and advanced practice providers.

Overall, 57% of participants -- and 64% of nurses and advanced practice providers -- said they had experienced symptoms of acute stress, such as nightmares, an inability to stop thinking about COVID-19, a feeling of being constantly on guard, and numbness or detachment from people or their surroundings. Acute stress symptoms that persist for more than a month can lead to post-traumatic stress syndrome (PTSD).

Although the environment took a psychological toll on all healthcare workers, nurses were particularly affected. The different responsibilities of nurses may partly explain the higher rates of positive acute stress screens and other impacts, as nurses spend more time delivering direct patient care.

Nearly half (48%) of all participants screened positive for depressive symptoms and one-third (33%) for anxiety.

Loneliness was pervasive

Insomnia and loneliness were also pervasive in this group (71% and 65%, respectively). "These were essential workers who were still going to work and interacting with patients and colleagues throughout the day," Abdalla says, "so the high prevalence of loneliness is striking."

Three out of four participants were highly distressed about the possibility of transmitting COVID-19 to loved ones. Most were highly distressed about the need to maintain social distance from family and friends and a lack of control and uncertainty during the pandemic.

"The health care workers had the double burden of caring for patients with COVID-19 and worrying about the possibility of getting loved ones sick," says Abdalla. "The high prevalence of insomnia and loneliness among clinicians suggests that the acute stress of working in this environment was physically and emotionally exhausting and isolating, but we don't know yet if this stress will have long-term consequences, and if so, whether the feeling that they were doing something meaningful and purposeful helps insulate them from this stress."

Most engaged in stress-reducing behaviors

Most respondents reported the use of stress-reducing behaviors, most commonly physical exercise but also talk therapy, virtual support groups, and religious/spiritual practices. Most expressed interest in having access to an individual therapist.

"Our findings highlight the need to study the effectiveness of the wellness resources that were available to the health care workers during the study period and determine if additional resources may be needed to better protect them during the next health crisis that may arise in New York City," Abdalla says.

Abdalla and her colleagues are currently doing a follow-up survey to see if these clinicians' psychological symptoms, coping strategies, and sense of optimism change over time.

A team of scientists working at Lawrence Berkeley National Laboratory (Berkeley Lab) has discovered a new form of the human-made element mendelevium. The newly created isotope, mendelevium-244, is the 17th and lightest form of mendelevium, which is element 101 on the periodic table.

Mendelevium was first created by Berkeley Lab scientists in 1955 (see a related video), and is among a list of 16 other elements that Berkeley Lab scientists discovered or helped to discover. An isotope is a form of an element with more or fewer neutrons (uncharged particles) in its atomic nucleus than other forms of an element.

In the latest discovery, the team used Berkeley Lab's 88-Inch Cyclotron, which accelerates powerful beams of charged particles at targets to create atoms of heavier elements, to make mendelevium-244. A cyclotron is a type of particle accelerator that was invented by the Lab's namesake, Ernest O. Lawrence, in 1930.

Berkeley Lab-led teams have now discovered 12 of the 17 mendelevium isotopes, and have discovered a total of 640 isotopes - about one-fifth of all known isotopes and by far the highest count for a single institution. At the close of 2019 there were 3,308 known isotopes. The new isotope discovery is the first by a Berkeley Lab-led team since 2010.

"It was challenging to discover this new isotope of mendelevium because all of the neighboring mendelevium isotopes have very similar decay properties," said Jennifer Pore, a Berkeley Lab project scientist who led the study detailing the isotope's discovery. Alpha decay describes the process by which a radioactive element like mendelevium breaks down into lighter elements over time.

In total, the team measured the properties of 10 atoms of mendelevium-244 for the study, which appeared today in the journal Physical Review Letters.

"Each isotope represents a unique combination of protons and neutrons," Pore said. "When a new isotope is discovered, that particular combination of protons (positively charged particles) and neutrons has never been observed. Studies of these extreme combinations are critical toward our understanding of all nuclear matter."

In addition to discovering the new isotope, the research team's work also provided the first direct evidence for a decay process involving an isotope of the element berkelium. The team included scientists from UC Berkeley, Lawrence Livermore National Laboratory, San Jose State University, and Sweden's Lund University.

Researchers found evidence that mendelevium-244 has two separate chains of decay, each leading to a different half-life: 0.4 second and 6 seconds, based on different energy configurations of particles in its nucleus. A half-life is the time it takes for a radioactive element's number of atoms to be reduced by half as their nuclei decay into other, lighter nuclei.

In a separate measurement stemming from the same study, the researchers found the first evidence for the alpha decay process of berkelium-236, an isotope of the element berkelium, as it transforms into americium-232, a slightly lighter isotope. Berkelium was discovered in 1949 by a Berkeley Lab-led team.

Central to the isotope's discovery was an instrument at the 88-Inch Cyclotron called FIONA, or For the Identification Of Nuclide A. The "A" in FIONA represents an element's mass number, which is the total number of protons (positively charged particles) and neutrons (uncharged particles) in an atom's nucleus. The new isotope's mass number is 244.

"The most important tool that we had in this discovery was FIONA," said Pore, who was also part of the team that assisted in FIONA's testing and startup. FIONA precisely measured the mass number of the new isotope.

Barbara Jacak, Nuclear Science Division director at Berkeley Lab, said, "We built FIONA to enable discoveries like this one, and it is exciting to see this instrument hitting its stride."

Michael Thoennessen, a University Distinguished Professor at Michigan State University who is on leave to serve as editor in chief of the American Physical Society, maintains a list of isotope discoveries and notes that the list of new isotopes has been thinner than usual over the past several years.

"Isotope discoveries are cyclical and depend on new accelerators and major advances in experimental equipment development," he said. Berkeley Lab's FIONA and the Facility for Rare Isotope Beams (FRIB), a U.S. Department of Energy user facility in development at Michigan State University, are unique capabilities "with large discovery potential" for different types of new isotopes in the U.S., he noted.

To ensure that FIONA's measurements were accurate, the research team first measured the decay properties and mass numbers of known mendelevium isotopes, including mendelevium-247, mendelevium-246, and mendelevium-245.

"Once we were confident that we were well-versed in the properties of these light mendelevium isotopes, we attempted the experiment to discover the previously unobserved isotope mendelevium-244," Pore said. "Without the direct confirmation that we had produced an isotope with a mass number of 244, it would have been very difficult to disentangle the results and prove the discovery."

To create such exotic isotopes - even the lightest known form of mendelevium is still heavier than naturally occurring uranium - scientists produced a particle beam at the 88-Inch Cyclotron containing charged particles of argon-40, an isotope of argon, and directed the beam at a thin foil target composed of bismuth-209, an isotope of bismuth.

Occasionally in these experiments, a nucleus in the high-energy particle beam directly strikes and fuses with a nucleus in the target foil, producing a single atom of a heavier element. And for an isotope with a very short half-life, it's a race to take measurements of an atom before it decays away into something else.

Berkeley's 88-Inch Cyclotron has another tool upstream of FIONA that is called the Berkeley Gas-Filled Separator. The separator helps pull out the relevant atoms that can be quickly and individually measured in detail with FIONA.

Researchers may pursue other studies of mendelevium-244 with other instrumentation to try to learn more about its structure, Pore said.

And now that FIONA has demonstrated its value in isotope discovery, Berkeley Lab researchers are setting their sights on other new isotopes. "We are already planning similar studies along other isotopic chains to discover new isotopes," Pore said.

Sea ice across the Southern Ocean played a crucial role in controlling atmospheric carbon dioxide levels during times of past climate change - and it could provide a critical resource to improve Earth system models, a new study shows.

The paper by scientists from UNSW and Keele University was published today in Nature Geoscience.

Led by Professor Chris Fogwill, an Honorary Professor at UNSW and Professor at Keele University, the international team of researchers demonstrated that seasonal growth and destruction of sea ice in a warming world enhances the amount of marine life present in the sea around Antarctica, sequestering carbon from the atmosphere, which ultimately becomes stored in the deep ocean.

"The Southern Ocean occupies 14% of the Earth's surface and plays a fundamental role in the global carbon cycle and climate," says Prof. Fogwill.

"It has captured around half of all human-related carbon that has entered the ocean to date, and is therefore crucial for regulating carbon dioxide levels resulting from human activity - and understanding the processes that determine its effectiveness as a carbon sink through time are essential to reducing uncertainty in future projections."

To understand this process further, Professor Fogwill and colleagues studied data relating to a period where atmospheric carbon dioxide levels changed rapidly - after the Last Ice Age, around 18,000 years ago, when the world transitioned naturally into the warm interglacial world we live in today.

During this period, carbon dioxide rose rapidly from around 190 parts per million (ppm) to 280 ppm over around 7,000 years, but one period in particular stands out; a 1,900 year period where carbon dioxide levels plateaued at a nearly constant level of 240 ppm.

The cause of this plateau, which occurred around 14,600 years ago, is unknown, but understanding what happened during this period could be crucial for improving climate change projections.

Walking back in time across ice

To resolve this question, the researchers travelled to the Patriot Hills Blue Ice Area of Antarctica to develop new records of evidence of marine life that are captured in ice cores.

"Blue ice areas are the perfect laboratory for Antarctic scientists due to their unique topography. Created by fierce, high-density winds, the top layer of snow is effectively eroded, exposing the ice below. As a result, ice flows up to the surface, providing access to ancient ice below", says co-author and UNSW Sydney Professor Chris Turney.

"Instead of drilling kilometres into the ice, we can simply walk across a blue ice area and travel back through time."

This type of blue ice lets scientists sample large amounts of ice for studying past environmental changes in detail.

"Organic biomarkers and DNA from the Southern Ocean are blown onto Antarctica and preserved in the ice, providing a unique record in a region where we have few scientific observations," Prof. Turney says.

Co-author Professor Andy Baker from UNSW Science says to pursue the idea of using organic matter trapped in ice, he helped to set up a methodology which allowed the team to look at the natural fluorescence of some organic molecules that they found in the ice.

"We knew this technique had amazingly good detection limits, and we thought we would need this given the small amounts of organic material we expected to find in the ice. We found the organic matter fluorescence signal that is normally associated with microbes.

"But where did this fluorescent organic matter come from? Because the team could walk across the ice, rather than core it, they could collect larger samples for organic techniques that needed that larger amount for analysis. These showed that the fluorescent organic matter could be identified as coming from the oceans. Transported from the oceans in the air, it was ultimately deposited as snow and preserved in the ice."

Increased marine life activity

Using this approach, the team discovered that there was a marked increase in the number and diversity of marine organisms present across the 1,900 year period when carbon dioxide plateaued, an observation which had never been recorded before.

"This is the first recorded evidence of increased biological productivity in the Antarctic zone during that period, and suggests that Southern Ocean processes may have caused the carbon dioxide plateau," co-author Dr Laurie Menviel from UNSW Science says.

However, the driver of this increase in marine organisms wasn't immediately clear to the scientists, so they used climate modelling to better understand the potential cause.

"The modelling revealed that the plateau period coincided with the greatest seasonal changes in sea ice, which occurred during a pronounced cold phase across the Southern Ocean known as the Antarctic Cold Reversal," Dr Menviel says.

"During this period, sea ice grew extensively across the Southern Ocean, but as the world was warming rapidly, each year the sea ice would be rapidly destroyed during the summer.

"Our results imply that during periods of Southern Ocean sea ice expansion, high variability in winter and summer sea ice extent may result in increased marine life activity and therefore enhanced carbon capture."

The cause of this long plateau in global carbon dioxide levels may be fundamental to understanding the potential of the Southern Ocean to moderate atmospheric carbon dioxide levels in the future.

"We need to understand the ways in which carbon dioxide levels have been stabilised by natural processes in the past. Under future warming, less sea ice will likely mean a weakening of this part of the carbon sink, making it increasingly difficult to meet Australia's commitment to the Paris Agreement," Prof. Turney says.

Toolkit for future research

UNSW co-author Dr Zoë Thomas says the paper is an exciting example of multidisciplinary collaboration.

"A lot of science can just focus on one specific process such as a physical, biological, or chemical aspect, but this work is a true interdisciplinary collaboration. It's only when you look at the combination of all these different roles that you get the main story - while it can be tempting to just go down one route, we got together a big team with a range of different expertise which allowed us to get a broader understanding of the system."

"This paper will also be known for developing a 'toolkit' of analyses on the trace amounts of organic material in ice," Prof. Baker says.

"This opens a new door for the global research community who can now think of using organic analyses to understand past climate changes."

The researchers will now use these findings to underpin the development of future Earth system models. The coupling of Southern Ocean and ecosystem dynamics in a new generation of models will be crucial for reducing uncertainties around climate projections, and will help society adapt to future warming.

Replacing the expensive metals that break down exhaust gases in catalytic converters with cheaper, more effective materials is a top priority for scientists, for both economic and environmental reasons. Catalysts are required to perform chemical reactions that would otherwise not happen, such as converting polluting gases from automotive exhaust into clean compounds that can be released into the environment. To improve them, researchers need a deeper understanding of exactly how they catalysts work.

Now a team at Stanford University and the Department of Energy's SLAC National Accelerator Laboratory has identified exactly which pairs of atoms in a nanoparticle of palladium and platinum - a combination commonly used in converters ¬- are the most active in breaking those gases down.

They also answered a question that has puzzled catalyst researchers: Why do larger catalyst particles sometimes work better than smaller ones, when you'd expect the opposite? The answer has to do with the way the particles change shape during the course of reactions, creating more of those highly active sites.

The results are an important step toward engineering catalysts for better performance in both industrial processes and emissions controls, said Matteo Cargnello, an assistant professor of chemical engineering at Stanford who led the research team. Their report was published June 17 in Proceedings of the National Academy of Sciences.

"The most exciting result of this work was identifying where the catalytic reaction occurs - on which atomic sites you can perform this chemistry that takes a polluting gas and turns it into harmless water and carbon dioxide, which is incredibly important and incredibly difficult to do," Cargnello said. "Now that we know where the active sites are, we can engineer catalysts that work better and use less expensive ingredients."

In a car's catalytic converter, nanoparticles of precious metals like palladium and platinum are attached to a ceramic surface. As emission gases flow by, atoms on the surface of the nanoparticles latch onto passing gas molecules and encourage them to react with oxygen to form water, carbon dioxide and other less harmful chemicals. A single particle catalyzes billions of reactions before becoming exhausted.

Today's catalytic converters are designed to work best at high temperatures, Cargnello said, which is why most harmful exhaust emissions come from vehicles that are just starting to warm up. With more engines being designed to work at lower temperatures, there's a pressing need to identify new catalysts that perform better at those temperatures, as well as in ships and trucks that are unlikely to switch to electric operation any time soon.

But what makes one catalyst more active than another? The answer has been elusive.

In this study, the research team looked at catalyst nanoparticles made of platinum and palladium from two perspectives - theory and experiment - to see if they could identify specific atomic structures on their surface that contribute to higher activity.

Rounder particles with jagged edges

On the theory side, SLAC staff scientist Frank Abild-Pedersen and his research group at the SUNCAT Center for Interface Science and Catalysis created a new approach for modeling how exposure to gases and steam during chemical reactions affects a catalytic nanoparticle's shape and atomic structure. This is computationally very difficult, Abild-Pedersen said, and previous studies had assumed particles existed in a vacuum and never changed.

His group created new and simpler ways to model particles in a more complex, realistic environment. Computations by postdoctoral researchers Tej Choksi and Verena Streibel suggested that as reactions proceed, the eight-sided nanoparticles become rounder, and their flat, facet-like surfaces become a series of jagged little steps.

By creating and testing nanoparticles of different sizes, each with a different ratio of jagged edges to flat surfaces, the team hoped to home in on exactly which structural configuration, and even which atoms, contributed the most to the particles' catalytic activity.

A little help from water

Angel Yang, a PhD student in Cargnello's group, made nanoparticles of precisely controlled sizes that each contained an evenly distributed mixture of palladium and platinum atoms. To do this, she had to develop a new method for making the larger particles by seeding them around smaller ones. Yang used X-ray beams from SLAC's Stanford Synchrotron Radiation Lightsource to confirm the composition of the nanoparticles she made with help from SLAC's Simon Bare and his team.

Then Yang ran experiments where nanoparticles of different sizes were used to catalyze a reaction that turns propene, one of the most common hydrocarbons present in exhaust, into carbon dioxide and water.

"Water here played a particularly interesting and beneficial role," she said. "Normally it poisons, or deactivates, catalysts. But here the exposure to water made the particles rounder and opened up more active sites."

The results confirmed that larger particles were more active and that they became rounder and more jagged during reactions, as the computational studies predicted. The most active particles contained the biggest proportion of one particular atomic configuration - one where two atoms, each surrounded by seven neighboring atoms, form pairs to carry out the reaction steps. It was these "7-7 pairs" that allowed big particles to perform better than smaller ones.

Going forward, Yang said, she hopes to figure out how to seed nanoparticles with much cheaper materials to bring their cost down and reduce the use of rare precious metals.

Interest from industry

The research was funded by BASF Corporation, a leading manufacturer of emissions control technology, through the California Research Alliance, which coordinates research between BASF scientists and seven West Coast universities, including Stanford.

"This paper is addressing fundamental questions about active sites, with theory and experimental perspectives coming together in a really nice way to explain the experimental phenomena. This has never been done before, and that's why it's quite significant," said Yuejin Li, a senior principal scientist with BASF who participated in the study.

"In the end," he said, "we want to have a theoretical model that can predict what metal or combination of metals will have even better activity than our current state of the art."