Tech

Buildings - Cool smart walls

Oak Ridge National Laboratory researchers used additive manufacturing to build a first-of-its kind smart wall called EMPOWER. The wall, designed for a building's interior, also functions as a cooling system to optimize energy use and lower overall cost.

The prototype wall was manufactured with a cable-driven, field deployable concrete additive manufacturing system and embedded with a thermal storage and active insulation system. A chiller connected to the wall pumps cool water through pipes. That coolness is stored in the interior and then transferred throughout the room as needed.

"With the ability to function not just as a support wall but also as the room's cooling system, the wall can lower utility bills and maintain occupant comfort while reducing energy use," said ORNL's Melissa Lapsa, who led the project sponsored by the Federal Energy Management Program.

Researchers will build two additional walls for installation in office buildings and monitor their performance and functionality for a year.

Media Contact: Jennifer Burke, 865.414.6835, burkejj@ornl.gov

Video: https://youtu.be/ANPn7c_KEBA

Caption: ORNL researchers 3D printed a concrete wall embedded with a thermal storage and active insulation system that allows the wall to function as a cooling system. Credit: ORNL, U.S. Dept. of Energy

Materials - Magnetism does the twist

Scientists discovered a strategy for layering dissimilar crystals with atomic precision to control the size of resulting magnetic quasi-particles called skyrmions. This approach could advance high-density data storage and quantum magnets for quantum information science.

In typical ferromagnets, magnetic spins align up or down. Yet in skyrmions, they twist and swirl, forming unique shapes like petite porcupines or tiny tornadoes.

The tiny intertwined magnetic structures could innovate high-density data storage, for which size does matter and must be small. The Oak Ridge National Laboratory-led project produced skyrmions as small as 10 nanometers - 10,000 times thinner than a human hair.

"The way we design and synthesize the superlattice creates the atomic-scale magnetic interactions responsible for twisting the spins," said physicist Elizabeth Skoropata, who co-led the study with John Nichols, both formerly of ORNL.

ORNL's Ho Nyung Lee added, "Our finding demonstrates how to precisely engineer interfaces in oxide quantum heterostructures to create nanometer-sized skyrmions."

Media Contact: Dawn Levy, 865.202.9465, levyd@ornl.gov

Image: https://www.ornl.gov/sites/default/files/2020-08/Skyrmion%20-%20v12%20%28NEW%20image%20from%20HNL%29.jpg

Caption: The layering of crystals into a superlattice yields a nanoscale magnetic structure of twisting, swirling spin orientations, shown from red to blue, that deflect electrons, shown as white dots. Credit: Adam Malin/ORNL, U.S. Dept. of Energy

Nuclear - Fuel cost savings

A developing method to gauge the occurrence of a nuclear reactor anomaly has the potential to save millions of dollars.

Oak Ridge National Laboratory is looking to answer a longtime question: What's the risk associated with fuel fragmentation, relocation and dispersal? That happens when fuel pellets in a reactor core degrade under accident conditions and extensive operation. If the cladding protecting the fuel bursts, fuel could be dispersed into the reactor core, potentially increasing the accident consequences.

Nathan Capps and colleagues are using the BISON fuel performance code and ORNL's hot cell-based severe accident test station - one of two worldwide - to identify and mitigate risk. That could pave the way for reactors to safely operate on longer cycles with less waste. The environmental impact and cost savings would be significant, he said - millions annually.

"This approach completely revolutionizes the nuclear industry, making nuclear energy safe and economically viable carbon-free energy sources," Capps said.

Media Contact: Kristi Nelson Bumpus, 865.253.1381, bumpuskl@ornl.gov

Image: https://www.ornl.gov/sites/default/files/2020-08/X2001338_FuelFragmentation_GraphicUpdate_Bumpus_jnj-01.jpg

Caption: This graphic shows the evolution of a rodlet during a high burnup loss-of-coolant accident test at the ORNL severe accident test station facility. As the rod's cladding balloons and bursts, fuel fragments can be dispersed. Credit: Jaimee Janiga/ORNL, U.S. Dept. of Energy

Image: https://www.ornl.gov/sites/default/files/2020-08/X2001338_FuelFragmentation_GraphicUpdate_Bumpus_jnj-02.jpg

Caption: Fuel pellets sometimes degrade to a sandlike consistency and can disperse into the reactor core if a rod's cladding bursts. ORNL researchers are studying how often this happens and what impact it has, in order to let reactors operate as long as possible without increasing risk. Credit: Jaimee Janiga/ORNL, U.S. Dept. of Energy

Nanomaterials - Short polymers, big impact

Oak Ridge National Laboratory scientists have discovered a cost-effective way to significantly improve the mechanical performance of common polymer nanocomposite materials. The discovery could lead to stronger, more durable materials for applications ranging from biomedical devices to automobile tires.

Glassy polymer nanocomposites, or PNCs, are sought-after materials with hard filler nanoparticles dispersed throughout their soft polymer matrices. While studying why PNCs demonstrate certain advantageous properties, researchers tried mixing in short and long chains of the same polymer.

"We found that by adding a small amount of the short polymer chains, the resulting mechanical properties were improved by 20%," ORNL's Vera Bocharova said. "This is good for practical applications."

Experimental data and computer simulations revealed that changes to polymer-nanoparticle interactions, polymer stretching, and density at nanoparticles' interfaces were responsible for the enhanced properties. The study results can be universally applied to PNCs and may help researchers design future materials with desired qualities.

Media Contact: Abby Bower, 865.323.9943, bowerae@ornl.gov

Image: https://www.ornl.gov/sites/default/files/2020-08/Screen%20Shot%202020-07-27%20at%202.45.28%20PM.png

Caption: Researchers used computer simulations to produce images of polymer nanocomposite materials. Nanoparticles are shown in pink and long polymer chains in cyan. Credit: Jan-Michael Y. Carrillo/ORNL, U.S. Dept. of Energy

Image: https://www.ornl.gov/sites/default/files/2020-08/Screen%20Shot%202020-07-27%20at%202.45.44%20PM.png

Caption: Simulations depict polymer nanocomposite, or PNC, materials. Mixing optimal amounts of short and long polymer chains, purple and cyan, improved PNC mechanical properties. Credit: Jan-Michael Y. Carrillo/ORNL, U.S. Dept. of Energy

There' s a loud bang, and then it starts: A battery module of an electric car is on fire in the Hagerbach test tunnel. A video of the test impressively shows the energy stored in such batteries: Meter-long flames hiss through the room and produce enormous amounts of thick, black soot. The visibility in the previously brightly lit tunnel section quickly approaches zero. After a few minutes, the battery module is completely burnt out. Ash and soot have spread throughout the room.

Crucial information for multi-storey and underground car parks

The trial, which was funded by the Swiss Federal Roads Office (FEDRO) and in which several Empa researchers participated, took place in December 2019. The results have just been published. "In our experiment we were considering in particular private and public operators of small and large underground or multi-story car parks," says project leader Lars Derek Mellert of Amstein + Walthert Progress AG. "All these existing underground structures are being used to an increasing extent by electric cars. And the operators ask themselves: What to do if such a car catches fire? What are the health risks for my employees? What effects does such a fire have on the operation of my plant?" But until now there has been hardly any meaningful technical literature, let alone practical experience for such a case.

With the support of battery researcher Marcel Held and corrosion specialist Martin Tuchschmid from Empa, Mellert developed three test scenarios. Experts from the Hagerbach AG test tunnel and the French Centre d'études des tunnels (CETU) in Bron were also involved. "We installed test surfaces in the fire tunnel on which the soot settled," explains Martin Tuchschmid, corrosion and fire damage specialist at Empa. "After the test, the surfaces were chemically analyzed and also stored in special rooms for several months to detect possible corrosion damage."

Scenario 1: Fire in an enclosed space

The first scenario involves a fire in a closed car park without mechanical ventilation. A parking space of 28 x 28 meters area and 2.5 meters floor height was assumed. Such a floor would have an air volume of 2000 cubic meters. The fire of a small car with a fully charged battery of 32 kWh is assumed. For reasons of test economy everything was scaled down to 1/8. Thus, a fully charged battery module with 4 kWh capacity was set on fire in a room with 250 cubic meters of air volume. The tests investigated how the soot settles on tunnel walls, surfaces and on protective suits worn by firefighters on site, how toxic the residues are and by what means the fire site can be cleaned after the event.

Scenario 2: Fire in a room with sprinkler system

Scenario 2 deals with chemical residues in the extinguishing water. The test set-up was the same as in scenario 1. But this time, the smoke from the battery was channeled with the aid of a metal plate beneath a water shower that resembled a sprinkler system. The sooty water that rained down was collected in a basin. The battery was not extinguished, but burned out completely.

Scenario 3: Fire in a tunnel with ventilation

In this scenario, the focus of the study lay on the effect of such a fire on a ventilation system. How far is the soot distributed in the exhaust ducts? Do substances that would cause corrosion settle there? In the experiment, a 4 kWh battery module was again set on fire, but this time a fan blew the smoke at a constant speed into a 160-meter-long ventilation tunnel. At a distance of 50, 100 and 150 meters from the site of the fire, the researchers had installed metal sheets in the tunnel where the soot would settle. The chemical composition of the soot and possible corrosion effects were analyzed in the Empa laboratories.

The results of the test were published in a final report in August 2020. Project leader Mellert reassures: In terms of heat development a burning electric car is not more hazardous than a burning car with a conventional drive. "The pollutants emitted by a burning vehicle have always been dangerous and possibly fatal," says the final report. Regardless of the type of drive or energy storage system, the primary objective has to be to get everyone out of the danger zone as quickly as possible. The highly corrosive, toxic hydrofluoric acid has often been discussed as a particular danger in burning batteries. In the three tests in the Hagerbach tunnel, however, the concentrations remained below critical levels.

Conclusion: A tunnel ventilation system that is state-of-the-art can cope not only with burning gasoline/diesel cars, but also with electric cars. Increased corrosion damage to the ventilation system or the tunnel equipment is also unlikely based on the results now available.

Even the fire brigades do not have to learn anything new on the basis of the tests. Firefighters know that the battery of an electric car is impossible to extinguish and that it can only be cooled with large amounts of water. So the fire can possibly be limited to a few battery cells, and part of the battery will not burn out. Of course, such a partially burnt wreck must be stored in a water basin or a special container so that it cannot reignite. But this is already known to the specialists and is being practiced.

The extinguishing water is poisonous

A problem, however, is the extinguishing and cooling water that is produced when fighting such a fire and storing a burnt-out battery in a water basin. The analyses showed that the chemical contamination of the extinguishing water exceeds the Swiss threshold values for industrial wastewater by a factor of 70; the cooling water is even up to 100-times above threshold values. It is important that this highly contaminated water does not enter the sewage system without proper treatment.

Professional decontamination mandatory

After the trials, the tunnel was decontaminated by a professional fire clean-up team. Samples taken subsequently confirmed that the methods and time required were sufficient for the clean-up after an electric car fire. But Mellert warns especially private owners of underground garages: "Do not try to clean up the soot and dirt yourself. The soot contains large amounts of cobalt oxide, nickel oxide and manganese oxide. These heavy metals cause severe allergic reactions on unprotected skin." So clean-up after an electric car fire is definitely a job for professionals in protective suits.

With the addition of just a small number of autonomous vehicles (AVs) on the road, traffic flow can become faster, greener, and safer in the near future, a new study suggests.

The study, published in Journal of Physics A: Mathematical and Theoretical, focused on the anticipated hybrid traffic flow of the future, which will combine traditional, human-operated vehicles with a small fraction of AVs. This scenario raises several questions as to whether traffic flow would actually improve and, if so, how many AVs would be required to produce significant change.

It may seem that a large number of AVs is required for a significant impact on traffic flow, especially on multilane freeways, as human drivers can simply ignore and bypass AVs. But this isn't necessarily so. In their research, Dr. Amir Goldental and Prof. Ido Kanter, from the Department of Physics at Bar-Ilan University, present a simple set of guidelines and regulations for achieving the self-organization of AVs into constellations that dynamically control the entire traffic flow.

The researchers suggest guidelines for efficient regulations, such that AVs can cooperate and significantly enhance traffic flow even when fewer than 5% of the vehicles on the road are autonomous, as seen in the accompanying video and image. In their article, the researchers describe how AVs should behave on a freeway in order to self-organize into groups that split the traffic flow into controllable clusters. It was observed that it takes less than two minutes to achieve self-organized high-speed, greener and safer traffic flow when starting from congested traffic.

"Without regulations on AVs, we face a classic example of game theory paradox, such as the prisoner's dilemma, where each vehicle tries to optimize its driving speed but the overall traffic flow is not optimal. In our research we examine how, with proper regulations, a very small number of AVs can improve the overall traffic flow significantly, through cooperation," says Dr. Goldental.

Quantitatively, the authors report a substantial increase of up to 40% in traffic flow speed with up to a 28% decrease in fuel consumption. Also, traffic safety is enhanced as traffic becomes more ordered and fewer lane transitions occur. The study shows that these improvements can be achieved without a central agent that governs AVs and without communication between AVs using current infrastructure.

Researchers from North Carolina State University have developed a suite of algorithms to improve the performance of cyber-physical systems - from autonomous vehicles to smart power grids - by balancing each component's need for data with how fast that data can be sent and received.

"Cyber-physical systems integrate sensors, devices, and communications tools, allowing all of the elements of a system to share information and coordinate their activities in order to accomplish goals," says Aranya Chakrabortty, co-author of a paper on the new algorithms and a professor of electrical and computer engineering at NC State. "These systems have tremendous potential - the National Science Foundation refers to them as 'enabling a smart and connected world' - but these systems also pose challenges.

"Specifically, the physical agents in a system - the devices - need a lot of communication links in order to function effectively. This leads to large volumes of data flowing through the communication network, which causes routing and queuing delays. These delays can cause long waiting times for the agents to take action, thereby degrading the quality of the system. In other words, there's so much data, being passed through so many links, that a system may not be able to accomplish its established goals - the lag time is just too long."

This creates a dilemma. Reducing communication can hurt the quality of the system's performance, because each element of the system will be operating with less information. On the other hand, reducing communication means that each element of the system would be able to get that information more quickly.

"So, it's all a trade-off," Chakrabortty says. "The right balance needs to be struck between all three variables - namely, the right amount of communication sparsity, the optimal delay, and the best achievable performance of the agents. Striking this fine balance to carry out the mission in the best possible way while also ensuring safe and stable operation of every agent is not easy. This is where our algorithms come in."

Chakrabortty and graduate student Nandini Negi developed three algorithms that, taken together, reduce the overall number of data requests from each node in a system, but ensure that each node receives enough information, quickly enough, to achieve system goals.

"There is no one-size-fits-all solution that will apply to every cyber-physical system," Negi says. "But our algorithms allow users to identify the optimal communications solution for any system."

The increasing use of AI (artificial intelligence) in the development of new medical technologies demands greater attention to ethical aspects. An interdisciplinary team at the Technical University of Munich (TUM) advocates the integration of ethics from the very beginning of the development process of new technologies. Alena Buyx, Professor of Ethics in Medicine and Health Technologies, explains the embedded ethics approach.

Professor Buyx, the discussions surrounding a greater emphasis on ethics in AI research have greatly intensified in recent years, to the point where one might speak of "ethics hype" ...

Prof. Buyx: ... and many committees in Germany and around the world such as the German Ethics Council or the EU Commission High-Level Expert Group on Artificial Intelligence have responded. They are all in agreement: We need more ethics in the development of AI-based health technologies. But how do things look in practice for engineers and designers? Concrete solutions are still few and far between. In a joint pilot project with two Integrative Research Centers at TUM, the Munich School of Robotics and Machine Intelligence (MSRM) with its director, Prof. Sami Haddadin, and the Munich Center for Technology in Society (MCTS), with Prof. Ruth Müller, we want to try out the embedded ethics approach. We published the proposal in Nature Machine Intelligence at the end of July.

What exactly is meant by the "embedded ethics approach"?

Prof.Buyx: The idea is to make ethics an integral part of the research process by integrating ethicists into the AI development team from day one. For example, they attend team meetings on a regular basis and create a sort of "ethical awareness" for certain issues. They also raise and analyze specific ethical and social issues.

Is there an example of this concept in practice?

Prof. Buyx: The Geriatronics Research Center, a flagship project of the MSRM in Garmisch-Partenkirchen, is developing robot assistants to enable people to live independently in old age. The center's initiatives will include the construction of model apartments designed to try out residential concepts where seniors share their living space with robots. At a joint meeting with the participating engineers, it was noted that the idea of using an open concept layout everywhere in the units - with few doors or individual rooms - would give the robots considerable range of motion. With the seniors, however, this living concept could prove upsetting because they are used to having private spaces. At the outset, the engineers had not given explicit consideration to this aspect.

Prof.Buyx: The approach sounds promising. But how can we avoid "embedded ethics" from turning into an "ethics washing" exercise, offering companies a comforting sense of "being on the safe side" when developing new AI technologies?

That's not something we can be certain of avoiding. The key is mutual openness and a willingness to listen, with the goal of finding a common language - and subsequently being prepared to effectively implement the ethical aspects. At TUM we are ideally positioned to achieve this. Prof. Sami Haddadin, the director of the MSRM, is also a member of the EU High-Level Group of Artificial Intelligence. In his research, he is guided by the concept of human centered engineering. Consequently, he has supported the idea of embedded ethics from the very beginning. But one thing is certain: Embedded ethics alone will not suddenly make AI "turn ethical". Ultimately, that will require laws, codes of conduct and possibly state incentives.

Abu Dhabi, UAE, September 1, 2020: A group of synthetic biologists at NYU Abu Dhabi (NYUAD) have identified new genetic targets that could lead to safe, biologically-based approaches to combat marine biofouling - the process of sea-based microorganisms, plants, or algae binding to underwater surfaces. Biofouling continues to present significant challenges for aquaculture and sea-based commercial activities, with one of the most common examples being found on the bottom of cargo ships, where the presence of attached marine organisms can change the hydrodynamics of ships, causing damage, and increasing fuel consumption.

In addition to its financial and operational impacts, biofouling has ecological consequences as it can introduce invasive species to new environments when the ships change locations. The current method for preventing biofouling is a chemical-based substance that is toxic to marine ecosystems.

A new study, led by NYUAD Research Scientist Weiqi Fu and Associate Professor of Biology Kourosh Salehi-Ashtiani, has identified 61 key signaling genes, some encoding protein receptors, that are turned on during surface colonization of a dominant group of phytoplankton (microscopic marine algae). The NYUAD researchers show that by increasing the level of the discovered genes and protein receptors, the biofouling activities of these marine-based planktonic cells can be manipulated. This study paves the way for the creation of new environmentally-friendly antifouling methods.

In the paper, titled GPCR Genes as Activators of Surface Colonization Pathways in a Model Marine Diatom, published in the interdisciplinary journal iScience, Salehi-Ashtiani and his team studied the process of morphology shifts of Phaeodactylum tricornutum, a model species of Diatoms. Diatoms are one of the most diverse and ecologically important groups of phytoplankton and are also recognized to be a leading contributor to biofouling globally. During the process of biofouling, the phytoplankton changes into an oval or round shape to aggregate as a biofilm on an underwater surface. This study presents the underlying molecular wiring that allows the cells of P. tricornutum to morph and induce biofouling.

"As marine biofouling on immersed artificial structures such as ship hulls, aquaculture cage facilities, and seawater handling pipes has had serious economic implications, there is a great need to discover a safe antifouling method," said Salehi-Ashtiani. "The receptors and signaling pathways described in this study pave the way for the targeted development of new antifouling techniques that are less harmful to global marine ecosystems," adds Fu, the lead author of the paper.

At the beginning of the 21st century, the International Maritime Organization banned the use of many widely used antifouling methods that were chemically-based due to their high toxicity towards marine organisms. Since then, there has been a surge in research to discover an environmentally-friendly antifouling technique. As the mechanics of biofouling on both the cellular and molecular levels were previously unknown, the signaling genes and protein receptors identified by this study provide key insight into targets for future ecologically safe antifouling methods.

The estimated time to clear surgeries postponed in Ontario because of the coronavirus disease 2019 (COVID-19) pandemic is 84 weeks, with a target of 717 surgeries per week, according to a new modelling study in CMAJ (Canadian Medical Association Journal).

"The magnitude of the surgical backlog from COVID-19 raises important implications for planning for the recovery phase and for possible second waves of the pandemic in Ontario," says Dr. Jonathan Irish, a surgeon at Princess Margaret Cancer Centre/University Health Network and the University of Toronto, Toronto, Ontario, with coauthors.

In mid-March, the Ontario Ministry of Health directed Ontario hospitals to cancel elective surgeries and other non-emergency-related activities to help prepare for an anticipated surge in patients with COVID-19. On May 26, the directive was lifted, allowing hospitals to begin ramping up elective and time-sensitive surgeries.

In April 2020, there were 38% fewer cancer surgeries, 42% fewer cardiac surgeries, 94% fewer pediatric surgeries and 96% fewer miscellaneous adult surgeries compared with the previous April. Between March 15 and June 13, there was a backlog of 148 364 surgeries. It will take 84 weeks - more than 1 ½ years - to complete these surgeries, with an estimated 14 weeks for time-sensitive surgeries (mainly cardiac, vascular and cancer surgeries) if resources are focused specifically on these procedures.

"This work shows the unprecedented magnitude of the secondary impact of COVID-19 on surgical care in Ontario," the authors write.

The modelling approach may be used in other provinces and territories to help with recovery planning.

"To effectively manage this impact on more than 140 000 patients, health systems and surgical leaders cannot get back to business as usual, but rather must employ innovative system-based solutions to provide patients with timely surgical care and prepare for future COVID-19 waves," the authors conclude.

An estimated 7600 pediatric surgeries were postponed between mid-March and June, and an additional 4000 children's surgeries could not be scheduled because of reduced access for surgical consultations, according to a related commentary.

"As Canada moves into a pandemic recovery phase, there is a danger than adult patients will be favoured by efforts to address the impact of disrupted access to surgery and to reduce the backlog of surgery," cautions Dr. Erik Skarsgard, a surgeon at the British Columbia Children's Hospital, Vancouver, BC, and member of the Pediatric Surgical Chiefs of Canada group. "Children are not small adults and they are not less deserving. Children have unique surgical needs that require prioritization within our health systems."

Almost 100 years ago, there was a strange, slow-motion takeover of the Great Plains. During the Dust Bowl of the 1930s, as a historic heatwave and drought swept the middle of the United States, there was a dramatic shift in the types of plants occupying the region.

Grasses more common in the cooler north began taking over the unusually hot and dry southern plains states that were usually occupied by other native grasses.

At the time, of course, this shift in plant cover was not the top concern during a disaster that displaced some 2.5 million people and caused at least $1.9 billion in agricultural losses alone. And, in fact, it didn't seem all that strange - until scientists started learning more about these types of plants.

"What happened only became a mystery much later, based on our subsequent understanding of the traits of the species that replaced each other," said Alan Knapp, a University Distinguished Professor in Colorado State University's Department of Biology in the College of Natural Sciences and the senior ecologist for CSU's Graduate Degree Program in Ecology.

During the 1960s, researchers found that there was a distinct ecological difference between these two types of what were thought of as warmer- and cooler-climate grasses (one group, known as "C4" use photosynthesis to produce a compound with four carbon atoms, compared to the other, known as "C3," whose first photosynthesis compound is composed of just three carbon atoms). The C4 grasses grow best in warm temperatures and are more efficient at using water. The C3 grasses tend to be most abundant in cooler and wetter climates.

Which raised the question: Why, during an infamous drought and heatwave, would C3 grasses suddenly invade some 135,000 square miles of the south-central U.S. Thus was born the "Dust Bowl paradox."

This is not just a matter of historical curiosity. As climate change accelerates, grasslands, which cover some 30% to 40% of the globe's land surface, are already seeing rising temperatures and extreme variations in rainfall and are expected to experience even more extreme droughts. And, noted Knapp, "they are a vital part of the local economies wherever they occur." So, understanding what precipitated the Dust Bowl's sudden shift in grass species - and their knock-on effects - is an increasingly pressing question.

"Because such extreme droughts are predicted to be more common in the future with climate change, it's important to understand why these grasslands responded the way they did, which was exactly the opposite that one would predict based on their traits," Knapp said.

Now, Knapp and his colleagues have found an answer to this question. In a new paper, published this week in Proceedings of the National Academy of Sciences, they describe a four-year artificial drought experiment carried out in Kansas and Wyoming grasslands that offers a solution to the mystery of the Dust Bowl paradox.

"This study unlocks a puzzle about why C3 grasses can outcompete C4 grasses in hot, dry conditions," said coauthor Yiqi Luo of the Center for Ecosystem Science and Society at Northern Arizona University. "As the global climate shifts and precipitation patterns change, this new lens is an important tool to predict future vegetation dynamics and carbon storage."

This gets us back to the mystery. Why would these cool-loving, less-water-efficient C3 grasses have come to dominate the central U.S. during a historic heatwave and drought? Knapp and his colleagues discovered that it had less to do with the amount of precipitation and much more to do with when that precipitation falls.

During a normal growing year in the southern U.S. plains, the bulk of the moisture falls in the summer, during the growing season. But in the northern grasslands, precipitation patterns are more even throughout the year. It turns out that this is also what happens during extreme drought - precipitation is much less tied to the warm months, occurring more evenly through the year.

So, with precipitation falling in patterns more like the northern plains during a drought in the south, C3 grasses found the bounds of their preferred rainfall dynamics extending southward. And they proliferated.

The researchers also found that the encroachment of C3 plants has a sort of self-fueling power. Because they start growing earlier in the year, "they can preemptively use soil water before C4 plants become active, further reducing the growth of C4 species," Knapp said.

These results are not simply a question of counting and tracking species. The different types of grasses also have different characteristics that can lead to changes in the overall ecosystem, climate, and land use.

For example, C3 grasses tend to green up an average of a full month before C4 grasses but die back sooner, shifting the region's soil-air carbon exchange. Being less efficient with water, C3 grasses suck up more moisture from the soil, which has a compounding effect, particularly during years when water is already scarce.

The time of year they grow matters too.

"All plants, when actively growing and green, evaporate substantial amounts of water from their leaves," Knapp explained. "This has a local cooling effect. Because C3 grasses grow when it is cool (in the spring) but not in the middle of the summer, the cooling effect is lost when it is needed most - during the hot summer months. This means that the shift from C4 to C3 growth patterns could result in hotter summers."

The team plans to continue studying the impacts of these seasonal changes - and recovery from them.

"After the decade-long Dust Bowl drought, remnants of the drought's impact on the plant communities were evident for 20 years," Knapp said. So the group is now monitoring how long it will take their experimental plots to recover after their four-year experiment.

"As such a globally extensive system, grasslands play a large role in the global carbon cycle and vegetation-atmospheric interactions," Knapp said, which is why understanding such large-scale historical events will be critical in preparing for climate changes of the future.

Johns Hopkins Medicine researchers have added to evidence that a gene responsible for turning off a cell's natural "suicide" signals may also be the culprit in making breast cancer and melanoma cells resistant to therapies that use the immune system to fight cancer. A summary of the research, conducted with mice and human cells, appeared Aug. 25 in Cell Reports.

When the gene, called BIRC2, is sent into overdrive, it makes too much, or an "overexpression," of protein levels. This occurs in about 40% of breast cancers, particularly the more lethal type called triple negative, and it is not known how often the gene is overexpressed in melanomas.

If further studies affirm and refine the new findings, the researchers say, BIRC2 overexpression could be a key marker for immunotherapy resistance, further advancing precision medicine efforts in this area of cancer treatment. A marker of this kind could alert clinicians to the potential need for using drugs that block the gene's activity in combination with immunotherapy drugs to form a potent cocktail to kill cancer in some treatment-resistant patients."Cancer cells use many pathways to evade the immune system, so our goal is to find additional drugs in our toolbox to complement the immunotherapy drugs currently in use," says Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Genetic Medicine, Pediatrics, Oncology, Medicine, Radiation Oncology and Biological Chemistry at the Johns Hopkins University School of Medicine, and director of the Vascular Program at the Johns Hopkins Institute for Cell Engineering.

Semenza shared the 2019 Nobel Prize in Physiology or Medicine for the discovery of the gene that guides how cells adapt to low oxygen levels, a condition called hypoxia.

In 2018, Semenza's team showed that hypoxia essentially molds cancer cells into survival machines. Hypoxia prompts cancer cells to turn on three genes to help them evade the immune system by inactivating either the identification system or the "eat me" signal on immune cells. A cell surface protein called CD47 is the only "don't eat me" signal that blocks killing of cancer cells by immune cells called macrophages. Other cell surface proteins, PDL1 and CD73, block killing of cancer cells by immune cells called T lymphocytes.

These super-survivor cancer cells could explain, in part, Semenza says, why only 20% to 30% of cancer patients respond to drugs that boost the immune system's ability to target cancer cells.

For the current study, building on his basic science discoveries, Semenza and his team sorted through 325 human genes identified by researchers at the Dana Farber Cancer Institute in Boston whose protein products were overexpressed in melanoma cells and linked to processes that help cancer cells evade the immune system.

Semenza's team found that 38 of the genes are influenced by the transcription factor HIF-1, which regulates how cells adapt to hypoxia; among the 38 was BIRC2 (baculoviral IAP repeat-containing 2), already known to prevent cell "suicide," or apoptosis, in essence a form of programmed cell death that is a brake on the kind of unchecked cell growth characteristic of cancer.

BIRC2 also blocks cells from secreting proteins that attract immune cells, such as T-cells and natural killer cells.

First, by studying the BIRC2 genome in human breast cancer cells, Semenza's team found that hypoxia proteins HIF1 and HIF2 bind directly to a portion of the BIRC2 gene under low oxygen conditions, identifying a direct mechanism for boosting the BIRC2 gene's protein production.

Then, the research team examined how tumors developed in mice when they were injected with human breast cancer or melanoma cells genetically engineered to contain little or no BIRC2 gene expression. In mice injected with cancer cells lacking BIRC2 expression, tumors took longer to form, about three to four weeks, compared with the typical two weeks it takes to form tumors in mice.

The tumors formed by BIRC2-free cancer cells also had up to five times the level of a protein called CXCL9, the substance that attracts immune system T-cells and natural killer cells to the tumor location. The longer the tumor took to form, the more T-cells and natural killer cells were found inside the tumor.

Semenza notes that finding a plentiful number of immune cells within a tumor is a key indicator of immunotherapy success.

Next, to determine whether the immune system was critical to the stalled tumor growth they saw, Semenza's team injected the BIRC2-free melanoma and breast cancer cells into mice bred to have no functioning immune system. They found that tumors grew at the same rate, in about two weeks, as typical tumors. "This suggests that the decreased tumor growth rate associated with loss of BIRC2 is dependent on recruiting T-cells and natural killer cells into the tumor," says Semenza.

Finally, Semenza and his team analyzed mice implanted with human breast cancer or melanoma tumors that either produced BIRC2 or were engineered to lack BIRC2. They gave the mice with melanoma tumors two types of immunotherapy FDA-approved for human use, and treated mice with breast tumors with one of the immunotherapy drugs. In both tumor types, the immunotherapy drugs were effective only against the tumors that lacked BIRC2.

Experimental drugs called SMAC mimetics that inactivate BIRC2 and other anti-cell suicide proteins are currently in clinical trials for certain types of cancers, but Semenza says that the drugs have not been very effective when used on their own.

"These drugs might be very useful to improve the response to immunotherapy drugs in people with tumors that have high BIRC2 levels," says Semenza.

DALLAS - Sept. 1, 2020 - Expanded telehealth services at UT Southwestern have proved effective at safely delivering patient care during the pandemic, leading to an increase in patients even in specialties such as plastic surgery, according to a new study.

The study, published in the Aesthetic Surgery Journal, illuminates the unexpected benefits that telehealth has had during the pandemic and provides insight into what this may mean for the future of medicine in the United States.

"Prior to COVID-19, it was not clear if telehealth would meet the standard of care in highly specialized clinical practices. Out of necessity, we were forced to innovate quickly. What we found is that it is actually a really good fit," says Alan Kramer, M.P.H., assistant vice president of health system emerging strategies at UTSW and co-author of the study.

UT Southwestern was already equipped with telehealth technology when COVID-19 hit - but only as a small pilot program. Through incredible team efforts, telehealth was expanded across the institution within days, bringing with it several unanticipated benefits for both the medical center and patients.

"The conversion rate to telehealth is higher than in person," says Bardia Amirlak, M.D., FACS, associate professor of plastic surgery and the study's senior corresponding author. The study found 25,197 of 34,706 telehealth appointments across the institution were completed in April 2020 - a 72.6 percent completion rate - compared with a 65.8 percent completion rate of in-person visits from April 2019.

The study notes the significant increases in the volume of new patients seen by telehealth beginning in March 2020. This resulted from a combination of relaxed regulations and an increasing comfort level with telehealth visits among physicians and patients. UTSW saw the percentage of new patients seen through telehealth visits increase from 0.77 percent in February to 14.2 percent and 16.7 percent in March and April, respectively.

Even within a niche field like plastic surgery, the implementation of telehealth has been incredibly successful, demonstrating the tractability of telehealth to a wide range of practices. From April to mid-May, plastic surgery completed 340 telehealth visits in areas such as breast cancer reconstruction, hand surgery, and wound care, with completion rates similar to the whole of UTSW. Likewise, plastic surgery also saw a large number of new patients, who comprised 41 percent of the telehealth visits.

"The fear was that the platform wouldn't be able to handle it: the privacy issues, insurance issues, malpractice issues ... but it came together well and we were able to ramp up into the thousands, and were able to not only decrease patient anxiety, but also increase many beneficial factors, such as patient access," says Amirlak.

The study reported several boons for telehealth patients, including reductions in stress, missed work, the number of hospital visits, travel time, and exposure to pathogens, in addition to improving access to care with the option for out-of-state consultations. Indeed, patients from 43 states and Puerto Rico have participated in telehealth visits at UTSW facilities since March.

Even as COVID-19 restrictions have eased in Texas, telehealth is still proving to be a major part of UT Southwestern's clinical practice. "The feedback from patients has been very positive," says Kramer. "We're now sustaining 25 percent of our practice being done virtually, a major win for our patients. It's changed the way we think about care."

Whether this trend continues into the post-COVID-19 world remains to be seen, he says. But either way, Kramer says, it is clear that telehealth will be a useful tool.

The numerous benefits that telehealth has to offer are accompanied by several challenges, however, such as the practicality and risks of remote diagnostic medicine. Though technology is starting to address some issues with the development of tools such as electronic stethoscopes and consumer-facing apps that can measure blood oxygen levels and perform electrocardiograms, for example, some argue the value of the in-person physical exam cannot be replaced. Moving forward, Amirlak says, "it will be our responsibility as physicians and scientists to recognize the potential dangers of taking telehealth to the extreme right now and missing a clinical diagnosis."

Aside from patient-facing issues, other challenges need to be included in discussions of the future of telehealth, including federal, state, and local laws; privacy concerns; and Health Insurance Portability and Accountability Act (HIPAA) regulations. Many statutes and restrictions have been loosened during the pandemic, allowing institutions like UTSW to implement telehealth rapidly and effectively. But the future of telehealth will necessitate the development of long-term regulations.

"Based on the trends, it seems that telehealth is here to stay. So it's important to think about the concerns, and based on this information, the issues that we have and how we can resolve them going forward," says Christine Wamsley, a UTSW research fellow and first author of the study. With the ramp-up of telehealth and related restrictions amid the COVID-19 pandemic, now may be the best opportunity for health care providers and governmental agencies to address these challenges and set out guidelines for the practice of telehealth.

Scientists have uncovered the earliest known evidence of an insect mimicking a lichen as a survival strategy, according to new findings published today in eLife.

The study suggests that the Jurassic moth lacewing Lichenipolystoechotes mimicked the fossil lichen Daohugouthallus to help conceal itself from predators. This interaction predates modern lichen-insect associations by 165 million years, indicating that the lichen-insect mimicry (or 'mimesis') system was well established during the mid-Mesozoic period and provided lacewings with highly-honed survival strategies.

Animals sometimes mimic other organisms or use camouflage to deceive predators. Lichens, which consist of a fungus and alga living in close proximity, sometimes have a plant-like appearance and are occasionally mimicked by modern animals and insects. One of the most well-known cases of a lichen-insect association is when the peppered moth acquired a mutation that turned it black during the Industrial Revolution in Britain, allowing the moth to blend in with tree trunks and lichen darkened by soot.

"As lichen models are almost absent in the fossil record of mimesis, it is still unclear as to when and how the mimicry association between lichen and insect first arose," explains lead author Hui Fang, a PhD student at the College of Life Sciences and Academy for Multidisciplinary Studies, Capital Normal University, Beijing, China. "The key to answer this question is to find early examples of a lichen-like insect and a co-occuring lichen fossil."

Fang and her team discovered deposits at the Daohugou 1 locality of Inner Mongolia in northeastern China that showed the 165-million-year-old lichen mimesis. The samples involved two lacewing species resembling a co-existing lichen from the latest Middle Jurassic.

After confirming the occurrence of the Jurassic lichen, the team then documented this mimetic relationship by describing structural similarities and detailed measurements of the lacewing and lichen. Their results suggest that when the lacewings rested in a lichen-rich habitat, a near-perfect match of their appearances would assist the insects' concealment from predators.

"Our findings indicate that a micro-ecosystem consisting of lichens and insects existed 165 million years ago in Northeastern China," concludes senior author Yongjie Wang, Associated Professor at the College of Life Sciences and Academy for Multidisciplinary Studies, Capital Normal University, Beijing. "This adds to our current understanding of the interactions between insects and their surroundings in the Mesozoic Era, and implies that there are many more interesting insect relationships awaiting discovery."

Human societies developed food preferences based on a blend of what was available and what the group decided it liked most. Those predilections were then passed along as part of the set of socially learned behaviors, values, knowledge, and customs that make up culture. Besides humans, many other social animals are believed to exhibit forms of culture in various ways, too.

In fact, according to a new study led by Harvard primatologists Liran Samuni and Martin Surbeck, bonobos, one of our closest living relatives, could be the latest addition to the list.

The research, published today in eLife, is the result of a five-year examination of the hunting and feeding habits of two neighboring groups of bonobos at the Kokolopori Bonobo Reserve in the Democratic Republic of Congo. They looked at whether ecological and social factors influence those habits. Four of those years were spent tracking the neighboring groups of great apes using GPS and some old-fashioned leg work to record each time they hunted.

Analyzing the data, the scientists saw many similarities in the lives of the two bonobo groups, given the names the Ekalakala and the Kokoalongo. Both roam the same territory, roughly 22 square miles of forest. Both wake up and fall asleep in the bird-like nests they build after traveling all day. And, most importantly, both have the access and opportunity to hunt the same kind of prey. This, however, is precisely where researchers noticed a striking difference.

The groups consistently preferred to hunt and feast on two different types of prey. The Ekalakala group almost always went after a type of squirrel-like rodent called an anomalure that is capable of gliding through the air from tree to tree. The Kokoalongo group, on the other hand, favored a small to medium-sized antelope called a duiker that lives on the forest floor.

"The idea is that if our closest living relatives, chimpanzees and bonobos, both have some cultural traits, then [it's likely] our ancestors already had some capacity for culture."
-- Liran Samuni

Out of 59 hunts between August 2016 and January 2020, the Ekalakala captured and ate 31 anomalure, going after duikers only once. Kokoalongo ate 11 duikers in that time and only three gliding rodents.

"It's basically like two cultures exploiting a common resource in different ways," said Samuni, a postdoctoral fellow in Harvard's Pan Lab and the paper's lead author. "Think about two human cultures living very close to each other but having different preferences: one preferring chicken more while the other culture is more of a beef-eating culture. ... That's kind of what we see."

Using statistical modeling, the scientists found this behavior happens independent of factors like the location of the hunts, their timing, or the season. They also found the preference wasn't influenced by hunting party size or group cohesion. In fact, the researchers' model found that the only variable that could reliably predict prey preference was whether the hunters were team Ekalakala or team Kokoalongo.

The researchers make clear in the paper that they didn't investigate how the bonobo groups learned this hunting preference, but through their analysis they were able to rule out ecological factors or genetic differences between the two groups. Basically, it means all evidence points toward this being a learned social behavior.

"It's the same population, and it's neighboring communities," said Surbeck, an assistant professor in the Department of Human Evolutionary Biology and the paper's senior author. He founded and directs the Kokolopori Bonobo Research Project. "These two communities basically live in the same exact forest. They use the exact same places, but, nevertheless, they show these differences."

The paper amounts to what's believed to be the strongest evidence of cultural behavior in this primate species.

The researchers believe this paper is only the tip of the iceberg and are already planning the next part of the work: looking at how the bonobo groups learned these behaviors.

One of the main goals driving this work is helping characterize the cultural capabilities of the last common ancestor between humans and our two closely related great ape cousins.

"The idea is that if our closest living relatives, chimpanzees and bonobos, both have some cultural traits, then [it's likely] our ancestors already had some capacity for culture," Samuni said.

Bonobos can play a special role in this mystery. Like chimpanzees, which they are often mistaken for, bonobos share 99 percent of their DNA with humans. Bonobos are often seen as less aggressive and territorial, however, favoring sex in various partner combinations over fighting. Chimp groups, on the other hand, sometimes battle when they meet in the wild, occasionally to the death.

Different Bonobo population groups are known to interact and even share meals, which along with their socio-sexual behavior has earn them the moniker "hippie apes." It's those free love and peace traits that make them prime for this type of study since scientists can observe two neighboring bonobo groups to distinguish whether a behavior that differs between two groups that interact regularly comes about because of some sort of a learning mechanism (or social preference) or because the environment dictates it, the researchers said.

The authors of the paper were not much surprised by their findings.

They had noticed this hunting preference anecdotally, and it's already believed that bonobos have subtle cultural traits. After all, a number of social animals display cultural behavior, especially when it comes to feeding habits. Chimps teach their young to use sticks to fish for termites. Dolphin mothers teach offspring to fit marine sponges to their noses to protect them as they forage on the seafloor.

What excites the researchers about this discovery, however, is that it shows the value of studying this often-overlooked endangered species and diving into its culture.

"They're like the missing puzzle piece," Surbeck said.

First-ever study of electronic waste shredding trucks shows the need for better safety guidelines.

A new Boston University School of Public Health study published in Annals of Work Exposure and Health is the first to evaluate the exposures faced by workers in mobile e-shredding, a new service to securely destroy hard drives, laptops, and other electronics containing confidential information on site.

Even proper electronic waste disposal still exposes workers to toxic metals such as lead and cadmium, as well as toxic chemicals--all of it usually ground into a fine powder that's easy to melt down for new gadgets, but also easy to inhale or even absorb through skin.

Dr. Diana Ceballos, assistant professor of environmental health at the Boston University School of Public Health (BUSPH), saw the growing use of mobile e-shredding trucks to destroy e-waste on site, including on university campuses, and was worried.

"I became particularly concerned with the almost non-existent safety measures, and potentially dangerous working conditions," Ceballos says.

She noticed workers not wearing masks or eye protection as they ground electronics to dust inside trucks that had no ventilation other than an open back door.

Ceballos and colleagues from the Harvard T.H. Chan School of Public Health evaluated the exposures during and after a 65-minute shredding job by one worker in a truck in the Greater Boston area.

Ceballos collected air samples (at the level of the worker's head) and surface wipes in different parts of the truck. The researchers found the concentrations of metal in the air near the shredder peaked at 2,500 ultrafine particles per cubic meter, including 2.9 micrograms of lead per cubic meter. "These exposures are similar to those experienced during a fire, or when using a diesel generator at a campsite," Ceballos says, "but the biggest challenge for the worker is that these levels are inside a truck and could accumulate to dangerous levels."

There were 171 micrograms of particulate matter 2.5 millimeters or less in diameter (known as PM2.5) per cubic meter. For comparison, the air in downtown Boston generally has 10-30 micrograms of PM2.5 per cubic meter, with notable and sometimes fatal effects.

After the job, the shredder and surfaces near it were coated with 1,190 micrograms of lead per square centimeter, and Ceballos found lead and other metals on surfaces as far away and separated from the shredder as the truck's cabin. Ceballos didn't take samples from the worker's clothes or skin, but notes that such contaminants can also come home with a worker and harm family members.

At least the generator powering the shredder in this truck was a new hybrid; with an older diesel generator and a differently configured truck, Ceballos says, a worker could be exposed to potentially fatal levels of carbon monoxide as well.

The verdict: Ceballos and colleagues found that the levels of metals and other contaminants in the truck were comparable to what they and other researchers have found in regulation-abiding, non-mobile e-recycling facilities. But workers in those facilities are supposed to wear protective equipment, and the facilities have exhaust ventilation (not just an open door) and regular cleaning.

(Ceballos says the trucks don't pose a risk to passersby out in the open air.)

"These trucks have become very popular and are a great service," Ceballos says. "My goal with this publication is to work with industry certifications to improve on their guidelines to strengthen the health and safety in these trucks."

But she says it isn't enough to just bring the trucks up to the same safety levels as non-mobile facilities.

E-recycling standards still aren't strict enough to fully protect the health of workers, in large part because the industry is so new, growing so quickly, and handling ever-changing technology, leaving government regulations in the dust.

The workers are also disproportionately "vulnerable," according to a new commentary in the American Journal of Industrial Medicine by Ceballos and colleagues at academic and government institutions including the Harvard Chan School, the University of Montreal, the National Institute for Occupational Safety and Health (NIOSH), and the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) in Quebec.

E-recycling workers, much like workers in many other high-risk and low-paying jobs, are much more likely to be members of racial/ethnic minorities, immigrants, under 25 years old, not fluent in English, and/or have physical or mental disabilities, the commentary authors write. Many are also currently or formerly incarcerated, including workers at nearly a dozen prison e-recycling sites in the US.

Ceballos says the e-recycling industry is one more example of how new hazards most affect groups who already face other health inequities. "Perhaps the public can understand this more clearly now during the pandemic," she says, "where the most vulnerable populations are those that have had the hardest time tackling the new virus."

By examining how fruit flies use eye movements to enhance flight control with a staggeringly fast reaction speed -- about 30 times faster than the blink of an eye -- Penn State researchers have detailed a framework to mimic this ability in robotics.

The researchers described the motions of fruit flies tethered in a virtual reality flight simulator constructed with LED lights and recorded using high speed cameras, in a paper published today (Aug. 31) in the Proceedings of the National Academy of Sciences.

"If you are able to study flies doing what they do best -- flying -- you can find some incredible engineering solutions that already exist in biology," said Benjamin Cellini, a doctoral student studying mechanical engineering and the first author of the paper.

Cellini and his adviser, Jean-Michel Mongeau, assistant professor of mechanical engineering and the director of the Bio-Motion Systems Lab, were able to determine how fruit flies use eye movements to quickly coordinate their wings in response to what they were seeing. Since fly eyes are fixed to the head, the researchers tracked head movements to infer where the flies were looking.

Stabilizing gaze is an ordinary phenomenon that most living things can do. For instance, we seamlessly move our eyes, head and/or body to scan a room.

"But that is a challenging, complex problem to understand, how are we and other animals able to do that so well?" Mongeau said. "My lab is interested in active sensing, which is a branch of engineering and biology that studies how sensor movement, like eyes scanning a room, can enhance sensing itself."

While much of the previous research in this area has focused on wing movements, understanding how animals like flies use active eye movements to control flight could greatly enhance robotics. Currently, most robots have stationary sensors, keeping sensing and movement decoupled. However, by better emulating the eyes and brain through the coordination of visual sensors capable of moving on the body, the flight control of robots could be vastly improved.

In support of this theory, the researchers determined the eyes of the fruit fly were able to react four times faster than the body or wings of the animal. These reactions were also tightly coupled, demonstrating that flies rely heavily upon eye movements to coordinate their wing movements.

"We've shown that their eyes can control and stabilize their vision better than we originally thought, by reducing motion blur," Cellini said. "Like in sports, they teach baseball players to follow the ball with their eyes to reduce blur and increase batting performance."

In addition, they found that when the flies had glue carefully applied to their heads and then recorded in the virtual reality flight simulator, the restriction of their head movements had a dramatic impact on flight performance.

"An important principle we discovered here was that fly eyes slow down visual motion that go into the brain and this process enhances their flying behavior," Mongeau said.

Demonstrated in this work, the researchers believe unlocking the secrets of the biological world could have broad implications for technology.

"In engineering, you are taught to apply principles from mathematics and physics to solve problems," Cellini said. "If you want to build a robot to fly on Mars, you can use engineering concepts to provide potential solutions. But we don't always have to develop ideas from scratch; we can also seek inspiration from nature."

The key to efficiently harvesting energy from sunlight could be to find the right combinations of light-capturing materials. Researchers at KAUST have discovered that a form of iron oxide makes an excellent co-catalyst for a promising photocatalytic material called gallium nitride.

Finding photocatalysts that can efficiently use sunlight to produce clean hydrogen fuel from water is one of the most sought-after applications of solar energy. "Nitrides can absorb most of the energy in the solar spectrum, but gallium nitride is a flawed water splitting photocatalyst," says Martin Velazquez-Rizo, a Ph.D. student in the labs of Kazuhiro Ohkawa, who led the current research.

"When GaN is used as a photocatalyst, the material is quickly damaged by photocorrosion, which impedes its implementation in industrial applications," Velazquez-Rizo says. Photocorrosion damage was visible after just two hours of photoelectrochemical hydrogen production, the team showed.

To test the possibility of extending the gallium nitride photocatalyst's working lifetime, the researchers tried combining it with an iron oxide. "Fe2O3 is a well-known material in the catalysis area because of its optical and electronic properties and for its capacity to operate in harsh environments," says Velazquez-Rizo. "We anticipated that, under the right conditions, Fe2O3 could suppress the photocorrosion of GaN photocatalysts without diminishing their photoabsorption capabilities."

The strategy has proven to be effective. When the team decorated the GaN surface with a 1.3 percent covering of Fe2O3 particles, the first signs of photocorrosion were more than 20 times slower to appear. In addition, the hydrogen production rate of the Fe2O3/GaN photocatalyst was five times higher than GaN alone. The results, says Velazquez-Rizo, "take GaN photocatalysts one step closer to being implemented in real-life applications."

Part of the reason Fe2O3 and GaN perform well together is likely because of the unusual way in which the Fe2O3 particles are arranged on the GaN surface. The atoms in the iron oxide particles align neatly with the atoms in the GaN lattice below, an effect known as epitaxial growth. This effect is rarely observed when combining materials with different crystallographic properties, such as Fe2O3 and GaN.

"Martin's work has shown that these different material systems can have a coherent crystal alignment, without crystal defects," Ohkawa says. "Today's photoelectrode devices are made of nitride semiconductors or of oxides, but his result indicates that by combining the two, it is possible to fabricate novel devices." The team is continuing to develop new GaN-based composite materials to improve the energy converstion efficiency of photocatalysts.