Earth

There's no doubt that climate change is affecting ecosystems as well as the lifestyles of plants and animals around the globe. As temperatures rise, so do the complexity of the issues. Scientists, both in the United States and around the world, are actively pursuing mitigation solutions while providing governments with the understanding of natural hazards to help stem the effects of climate change.

At The University of New Mexico, Matthew Hurteau, associate professor in the Department of Biology, has conducted research to determine how disturbances influence tree mortality risk and how that information can be used in carbon management policies to mitigate climate change. Hurteau and several colleagues argue in an opinion piece, "Managing for disturbance stabilizes forest carbon," released today in Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed multidisciplinary scientific journal, that policymakers would do well to use disturbance ecology in an effort to stabilize forest carbon.

Central to their piece, Hurteau and colleagues say that "forest systems sequester approximately 12 percent of anthropogenic carbon emissions, and that efforts to increase forest carbon uptake are central to climate mitigation policy.

Understanding the role of carbon is important. As plants photosynthesize, they're taking in carbon dioxide from the atmosphere and then, in the case of trees, turning that carbon into wood. Basically, you can look at a tree and that's carbon that could be in the atmosphere, but it's been taken up by that tree and locked up in wood.

Managing forests to store carbon has focused on increasing forested area, decreasing area lost to logging and clearing, and increasing forest carbon density. Warming, drought, and wildfires challenge the stability of carbon stored in forests.

"By contrast, natural cycles of low intensity fires in dry forests can, over the long term, promote forest carbon storage by protecting carbon in soil and in large, old trees. The conundrum is how to balance immediate, disturbance-driven carbon loss with long-term, stable carbon storage and account for these risks in policies for forest carbon management."

The understanding of disturbance ecology has come long way. Generally, disturbance is a temporary change in environmental conditions that causes a definitive or pronounced change in an ecosystem. They act quickly, such as in the case of wildfire, and create significant effect in the physical structure and arrangement of living and nonliving elements.

"When you have a climate change mitigation project, like a forest carbon offset project, it has to meet several criteria," said Hurteau. "One of those criteria is that the carbon must be stored in the forest for some long period of time, which is called permanence. This is a tall order when it comes to a natural system, especially when it's disturbance prone."

Along those lines, one of the new areas policymakers should consider the researchers say, "is the explicit use of disturbance ecology to factor in tree mortality risk." Scientists understanding of wildfire and other impactful disturbances have grown to a level where it's time to incorporate these risks into policy mechanisms that enhance forest carbon storage. Governments and policymakers already use similar types of knowledge to make informed decisions for natural disasters including earthquakes, wildfires and floods.

"In the California compliance market for their cap and trade system, if you develop a forest carbon project, that carbon you quantify and sell as offsets has to be stored for a hundred years," Hurteau explained. "Things like wildfire, insect outbreaks, and drought pose what is called a 'reversal risk' in the carbon accounting world, where that carbon sequestration and storage gets undone by the disturbance.

"This creates a situation where you've got offsets that had been sold to help reduce emissions that we put in the atmosphere that are causing the climate to change," said Hurteau. "When a disturbance happens, that carbon is no longer sequestered in the forest and so the idea is that we have the ability and the data to actually quantify what the chance of these disturbances occurring is, and then what effect on any sort of management action could have on reducing that reversal risk."

As an example, the thinking behind these carbon offsets is that if a large power producer is burning coal and they need to meet an emissions reduction target and you own a forest, they can pay you to do some activity to store more carbon than you would have under business as usual conditions.

"If you've got a working forest and, and you usually harvest every so often, you develop carbon offsets by foregoing harvest and I buy them," said Hurteau. "And then you keep that carbon locked up in the forest."

In the opinion column, Hurteau and his colleagues encourage policymakers to use stability and risk accounting strategies based on the understanding of disturbance probability and severity. California's cap and trade program, which is one of the largest carbon markets, is currently being monitored by several U.S. states and other countries as a potential model to develop their own markets. The program allows California companies to buy forest carbon offsets that may be available anywhere in the U.S. Out-of-state offsets are valued by bid price and standing carbon stores.

An important piece of this idea is how researchers can help quantify and price risk, which is pretty common in other areas. Auto or homeowners insurance is a good example. The price of your policy all depends on how much exposure to loss you have.

Hurteau says scientists can actually quantify the risks to forest carbon offsets and then the benefit of management to reduce that risk can be priced by the market. Another key point in the dialogue is that the U.S. already has the legal framework in place to implement the initiative on federal lands in the U.S.

"One of the things that stands in the way of getting this done is that the U.S. Federal government has not recognized, the significant risks that we face from climate change and therefore is undervaluing the portfolio of options we have available to reduce that risk," said Hurteau. "The data and research on wildfire and forest management goes back to the 70s and 80s and we've known that the humans have been changing the climate for decades. We could have done something a lot sooner. As humans, we're real good at dealing with acute problems and not real good with the chronic."

Coral reef experts from around the world are calling for an urgent re-evaluation of our climate goals in the light of increasing evidence of unprecedented speed of change to these fragile ecosystems.
Coral reefs, which have functioned relatively unchanged for some 24 million years, are now going through profound changes in their make-up.

Writing in a special feature of Functional Ecology, some of the world's leading coral reef experts are asking searching questions about the priorities for reef conservation and reef ecology in the face of these recent and rapid changes, which have far exceeded predictions.

The scientists address issues such as how we should actually define what comprises a functioning coral reef in the Anthropocene, an era where humans are the dominant force of planetary change.

As the world's climate changes, tropical temperatures shift towards the poles, enabling corals to grow in new places. As corals are lost to warming oceans in some places and growing in previously inhospitable cooler waters, how are environmental scientists to react?

This shifting picture requires fresh responses from the scientific community if we are to preserve coral ecosystems along with the services and benefits they provide from food to tourism, coastal protection and ecosystem support.

Professor Nick Graham of Lancaster University said: "Coral reefs have been with us in some form since the dinosaurs and today they are at the frontline in terms of responses to climate change and a range of other human pressures. Our special feature captures an emerging realisation within the coral reef science community that the rules of how coral reefs function, their species configurations, geographic distributions, and the benefits derived by people, are all changing. The scientific community, managers, and resource users are having to rapidly understand and adapt to this changing ecosystem and learn how to sustain it. This will only be possible if carbon emissions are rapidly reduced".

Bangor University's Dr Gareth Williams said: "This special feature on the functional ecology of coral reefs is necessary and timely. Within one generation we are already observing changes which were not foreseen. This pace of change is so fast that it requires us to revisit and question whether our understanding of how these ecosystems function, built up over the many decades of research, is still relevant. The works call for the scientific community to revisit many classic questions and theories surrounding the ecology, management and conservation of coral reefs, asking provocative questions such as: what makes for a functioning coral reef in this new climate scenario and human-dominated world? Answering these questions has important implications for how we study, describe and manage these ecosystems moving forward."

PITTSBURGH, June 7, 2019 - The faster fluid is removed using continuous dialysis from patients with failing kidneys, the higher the likelihood they will die in the next several months, according to a study published today in JAMA Network Open by University of Pittsburgh School of Medicine researchers.

Nearly two-thirds of critically ill patients with acute kidney injury have extra fluid accumulating in their bodies, which can put pressure on their lungs and cause injury to other organs. To relieve that pressure, clinicians routinely remove the excess fluid from the blood while performing dialysis in the intensive care unit. But there is no guidance on how fast that fluid should be removed.

"We want to get this excess fluid out of our patients before it causes damage but, in removing it, we're actually causing a controlled loss of fluid that can sometimes cause stress on the heart and lead to dangerously low blood pressure," said lead author Raghavan Murugan, M.D., M.S., associate professor in Pitt's Department of Critical Care Medicine and UPMC physician. "So the question--how rapidly to remove fluid?--has been asked in the critical care community for many years, but there's been no good answer."

Previous studies in outpatients who are not critically ill found that routine dialysis--a procedure to remove waste, toxins, salt and extra water from the blood of people whose kidneys have failed--when performed too quickly, is associated with increased risk of death.

Murugan partnered with senior author Rinaldo Bellomo, M.D., Ph.D., a professor of intensive care medicine at the University of Melbourne in Australia to find out if that finding extends to critically ill patients. Their team examined data from 1,434 patients that Bellomo had previously collected for the Randomized Evaluation of Normal vs. Augmented Level of Renal Replacement Therapy trial, which was conducted between December 30, 2005 and November 28, 2008 in 35 intensive care units in Australia and New Zealand.

The research team found that for every 0.5 milliliter increase in fluid removed per kilogram of the patient's weight per hour (0.5 mL/kg/hr), their risk of death increases. That translates to a 51% to 66% higher risk of death in the next three months for critically ill patients for whom excess fluid is removed at a rate greater than 1.75 mL/kg/hr, compared to patients for whom excess fluid is removed at a rate less than 1.01 mL/kg/hr.

For the average older American male, that's a difference of removing a gallon of fluid in about one day versus a little under two days.

Murugan is quick to point out that his analysis shows association, not causation; until a clinical trial is performed to specifically test the effects of removing fluid faster versus slower, he cannot say for sure that removing fluid slowly is better for the patient. And, in some cases, such as imminent heart failure, Murugan says a more rapid removal of fluid might be warranted to prevent sudden death.

"You have to balance the pros and the cons, and decide how fast to remove fluid based on your patient's clinical condition," said Murugan, who also is a member of Pitt's Clinical Research, Investigation, and Systems Modeling of Acute Illness Center and the Center for Critical Care Nephrology. "But in a patient where I can't find an immediate need to get fluid out quickly, I'll be removing fluid at a slower rate until we get definitive results and guidance from a clinical trial."

Extreme erosion of Arctic coastlines in a changing climate - up to a metre a day - has been revealed with drone surveys.

Storms in the Canadian Arctic are washing away increasing amounts of coastal permafrost - frozen ground - which is exposed when sea ice melts during the summer.

The results highlight the ongoing change in the region, as a warming climate leads to longer summer seasons. Sea ice melts earlier and reforms later in the year than before, exposing the coastline and presenting more opportunities for storms to cause damage.

An international team of researchers led by the University of Edinburgh flew drone-mounted cameras over a section of permafrost coastline on Herschel Island, also known as Qikiqtaruk, off the Yukon coast in the Canadian Arctic.

The team mapped the area seven times over 40 days in the summer of 2017. Their results, from image-based computer models, showed that the coast had retreated by 14.5 metres during the period, sometimes more than a metre a day.

Comparison with surveys dating from 1952 until 2011 showed that the rate of erosion in 2017 was more than six times the long-term average for the area.

Around the Arctic, rapidly changing permafrost landscapes threaten infrastructure essential to local communities such as on Qikiqtaruk - Herschel Island, as well as significant cultural and historic sites.

The study, published in The Cryosphere, was carried out in collaboration with the University of Exeter, Alfred Wegener Institute, Germany, the GFZ German Research Centre for Geosciences, the Vrije Universiteit Amsterdam and Dartmouth College. It was supported by the UK Natural Environment Research Council, the National Geographic Society, and Horizon 2020.

Dr Andrew Cunliffe, currently of the University of Exeter's Geography department, who led the study, said: "As the Arctic continues to warm faster than the rest of our planet, we need to learn more about how these landscapes are changing. Using drones could help researchers and local communities improve monitoring and prediction of future changes in the region."

Dr Isla Myers-Smith, of the University of Edinburgh's School of GeoSciences, who took part in the study, said: "Big chunks of soil and ground break off the coastline every day, then fall into the waves and get eaten away."

In spintronics, the use of organic materials as a "spin transport material" has recently garnered significant attention as they exhibit long spin-relaxation times and long spin-diffusion lengths owing to the weak spin-orbit interaction (SOI) of light elements. Meanwhile, the weak SOI of organic materials become a drawback when they are used as a "spin filter". A spin-polarized current is, therefore, typically generated by inorganic materials with ferromagnetism or strong SOIs. However, the recent finding of spin-selective electron transport through chiral molecules, i.e., the so-called chirality-induced spin selectivity (CISS) effect, suggests an alternative method of using organic materials as spin filters for spintronics applications. Through this effect, right-handed and left-handed molecules generate down- and up-spin, respectively. However, chiral molecules used in the experiments reported so far are static molecules. Hence, the manipulation of spin-polarization direction by external stimuli has not been realized yet.

Now, researchers at Institute for Molecular Science, RIKEN, Nara Institute of Science and Technology, Suranaree University and Vidyasirimedhi Institute of Science and Technology fabricated a novel solid-state spin filtering device that sandwiches a thin layer of artificial molecular motors (Figure 1). Because the artificial molecular motors demonstrate 4 times chirality inversion by light irradiation and thermal treatments during the 360-degree molecular rotation, the spin-polarization direction of electrons that pass through the molecular motors should be switched by light irradiation or thermal treatments.

Figure 2 shows (left) the magnetoresistance (MR) curves recorded after various visible light-irradiation time for a device fabricated with a left-handed isomer. In the initial state, a clear antisymmetric MR curve with a negative slope was observed, which means a clear up-spin selectivity. The MR signal decreased as light irradiation proceeded, and finally the slope of the MR signal was inverted to positive, indicating a light-induced spin switching in the spin-polarized current from up-spin selective to down-spin through the left-handed-to-right-handed chirality inversion. A subsequent thermal activation process for the left-handed isomer inverted the slope of the MR curve from positive to negative again, as shown in Figure 2 (right), implying a thermal-activation-induced spin switching from down-spin selective to up-spin selective through the right-handed-to-left-handed chirality inversion. Similar phenomena were observed in subsequent measurements after photo-irradiation and thermal treatments. This series of experiments clearly demonstrated that 4 times spin switching were induced during the 360-degree rotation of the molecular motors.

In this new type of novel organic spintronics device, the right-handed/left-handed chirality, which is the origin of spin-polarization generation through the CISS effect, is reconfigurable by external stimuli and precise control of the spin-polarization direction in the spin-polarized currents by utilizing an artificial molecular motor was realized, for the first time. The present results are beneficial for the development of next-generation organic photo/thermospintronic devices combined with molecular machines.

As sessile organisms, plants rely on their ability to adapt the development and growth of their roots in response to changing nutrient conditions. One such response, known to be displayed by plants grown in low nitrogen conditions, is the elongation of primary and lateral roots to explore the surrounding soil. This adaption to the lack of the essential element nitrogen is of particular interest, as it reflects a "foraging strategy", by which the root system can exploit nutrients from a larger soil volume. Until recently, this was the least understood nitrogen-dependent root response. Scientists from the IPK in Gatersleben have now identified the hormone pathway regulating root foraging under low nitrogen conditions and a signalling component that modulates the intensity of this response. These findings open up the possibility of breeding crops with root systems enabling more efficient nitrogen uptake.

The amount and form of plant-available nutrients fluctuates in soils, for example in dependence of soil moisture or microbial transformation processes of nutrients. Plants sense changes in their nutritional status and respond to these by tailoring the growth and development of their roots. These responses express in an altered degree of branching, extension, placement, and growth direction of individual parts of the root system. Nitrogen is an essential mineral element and nutrient for plants. When nitrogen availability is low, plant roots preferentially grow into nitrogen-enriched soil patches by locally expanding their lateral roots. As soon as plants run into nitrogen deficiency, they immediately induce a foraging response, in which roots elongate to explore a larger soil volume. The regulatory mechanisms underlying this nitrogen-dependent root response were previously unknown. Researchers from the IPK in Gatersleben have now discovered that a class of steroid hormones modulate root foraging under low nitrogen conditions and thereby determine the extent of this response. The findings were published in Nature Communications.

In this study, scientists from the research group "Molecular Plant Nutrition", led by Prof. N. von Wirén, assessed the natural variation in root growth under mild nitrogen deficiency in 200 accessions of the model plant Arabidopsis thaliana. Employing genome-wide association mapping with support of the "Heterosis" group led by Prof. T. Altmann, the researchers were able to show that BSK3, a brassinosteroid signaling kinase, is modulating the extent of root elongation under low nitrogen. Further, they demonstrated that mild nitrogen deficiency activates brassinosteroid signaling by upregulating the transcript levels of the brassinosteroid co-receptor BAK1 that enhances the sensitivity of root cells to brassinosteroids.

The results reveal a previously unknown role of brassinosteroid-type plant hormones in shaping root systems in response to nutrient deficiencies. This novel insight allows a deeper understanding of the regulation behind adaptive responses of plants to changes in nitrogen availability, but also provides a perspective for practical application in agriculture.

As a "major driver of plant growth", nitrogen is an indispensable element in agricultural plant production. However, nitrogen fertilizers must be used with care, as a surplus of nitrogen in the soil can have a detrimental impact on the environment, for example by leading to soil acidification or to eutrophication of waterbodies. Therefore, the breeding of crops, which better exploit the soil for nutrients, is highly desirable as they may require less fertilizer. The researchers of this study see their discovery of the regulatory role of BSK3 as novel opportunity to approach this matter. By exploiting naturally occurring allelic versions of BSK3 or by the generation of de-novo variants by precise genome editing, plant breeders could develop new crop cultivars with larger root systems, giving crop species the sought-after mechanisms to perform better at low nitrogen fertilizer inputs.

An international team of researchers recently synthesized polyarylether-based covalent organic frameworks, the most stable crystalline porous material on record. The team, which includes the University of Delaware's Yushan Yan and Jilin University's Qianrong (Frank) Fang, a former postdoctoral researcher with Yan at UD, described their results in the international scientific journal Nature Chemistry.

Some materials act like sieves and let molecules pass through their pores. These materials, known as molecular sieves, are useful in many industrial processes, especially in the chemical and energy sectors. They could be used to remove contaminants from water. They have also received attention for potential applications in aerospace, rail transportation, automobile manufacturing and more, but so far, their applications have been limited by their instability under extreme conditions.

Yan, the Distinguished Engineering Professor in the Department of Chemical and Biomolecular Engineering, has investigated crystalline porous materials such as zeolite since his doctoral research in the earlier 1990s. He won the Donald Breck Award, the highest award from the International Zeolite Association in 2010 for his zeolite thin film work. When Fang joined his group in 2009, the pair began to explore an emerging class of crystalline porous materials called covalent organic frameworks, which are linked by covalent bonds, show great promise, but at times are limited by available chemistries and their instability in harsh conditions, such as strong acids and bases.

Yan and Fang were the first to make covalent organic frameworks using stable carbon-nitrogen bond (imide) and they have since, first at UD and then at Jilin University after Fang left UD to take a prestigious faculty position back in China, been working to develop covalent organic frameworks based on carbon-oxygen bonds. They anticipated these materials would be stable -- if only they could make them.

To do so, they made frameworks out of polyarylether, a highly stable engineered plastic. By carefully designing the skeletons based on new stable bonds, they made a material that was more stable than any other of its kind.

"Once you have the carbon-oxygen bond, this porous material is stable in strong acid, strong bases, and strong oxidants," said Yan. The frameworks are also stable up to 400 degrees Celsius. "Among porous crystalline materials, organic or inorganic, this is the most stable one."

For the next step, the research team made polyarylether-based covalent organic frameworks that could sift antibiotic residue out of water in a pH ranging from 1 to 13.

In the paper, the research group concluded: "These stable COFs [covalent-organic frameworks] are a perfect platform for the preparation of functional materials that can be used under extreme chemical environments."

Large parts of Asian Russia could become habitable by the late 21st century due to climate change, new research has found.

A study team from the Krasnoyarsk Federal Research Center, Russia, and the National Institute of Aerospace, USA, used current and predicted climate scenarios to examine the climate comfort of Asian Russia and work out the potential for human settlement throughout the 21st century.

They published their results today in Environmental Research Letters.

At 13 million square kilometres Asian Russia - east of the Urals towards the Pacific - accounts for 77 per cent of Russia's land area. Its population, however, accounts for just 27 per cent of the country's people and is concentrated along the forest-steppe in the south, with its comfortable climate and fertile soil.

"Previous human migrations have been associated with climate change. As civilisations developed technology that enabled them to adapt, humans became less reliant on the environment, particularly in terms of climate," said the study's lead author Dr Elena Parfenova, from the Krasnoyarsk Federal Research Center.

"We wanted to learn if future changes in climate may lead to the less-hospitable parts of Asian Russia becoming more habitable for humans."

For their analysis, the team used a combination of 20 general circulation models (Coupled Model Intercomparison Project Phase 5) and two CO2 Representative Concentration Pathway scenarios - RCP 2.6 representing mild climate change and RCP 8.5 representing more extreme changes.

They applied the collective means of January and July temperatures and annual precipitation of the two scenarios to Asian Russia to find their respective effects on three climate indices that are important for human livelihood and well-being: Ecological Landscape Potential (ELP), winter severity, and permafrost coverage.

Dr Parfenova said: "We found increases in temperature of 3.4°C (RCP 2.6) to 9.1°C (RCP 8.5) in mid-winter; increases of 1.9°C (RCP 2.6) to 5.7°C (RCP 8.5) in mid-summer; and increases in precipitation of 60 mm (RCP 2.6) to 140 mm (RCP 8.5).

"Our simulations showed that under RCP8.5, by the 2080s Asian Russia would have a milder climate, with less permafrost coverage, decreasing from the contemporary 65 per cent to 40 per cent of the area by the 2080s."

The researchers also found that even under the RCP 2.6 scenario, the ELP for human sustainability would improve in more than 15 per cent of the area, which could allow for a five-fold increase in the in the capacity of the territory to sustain and become attractive to human populations.

Dr Parfenova concluded: "Asian Russia is currently extremely cold. In a future warmer climate, food security in terms of crop distribution and production capability is likely to become more favourable for people to support settlements.

"However, suitable land development depends on the authorities' social, political and economic policies. Lands with developed infrastructure and high agricultural potential would obviously be populated first.

"Vast tracts of Siberia and the Far East have poorly developed infrastructure. The speed these developments happen depends on investments in infrastructure and agriculture, which in turn depends on the decisions that should be made soon."

ALBUQUERQUE, N.M. -- Steel pipes rust and eventually fail. To preempt disasters, oil companies and others have created computer models to predict when replacement is needed. But if the models themselves go wrong, they can be modified only through experience, a costly problem if detection comes too late.

Now, researchers at Sandia National Laboratories, the Department of Energy's Center for Integrated Nanotechnologies and the Aramco Research Center in Boston, have found that a particular form of nanoscale corrosion is responsible for unpredictably decreasing the working life of steel pipes, according to a paper recently published in Nature's Materials Degradation journal.

Using transmission electron microscopes, which shoot electrons through targets to take pictures, the researchers were able to pin the root of the problem on a triple junction formed by a grain of cementite -- a compound of carbon and iron -- and two grains of ferrite, a type of iron. This junction forms frequently during most methods of fashioning steel pipe.

Iron atoms slip-sliding away

The researchers found that disorder in the atomic structure of those triple junctions made it easier for the corrosive solution to remove iron atoms along that interface.

In the experiment, the corrosive process stopped when the triple junction had been consumed by corrosion, but the crevice left behind allowed the corrosive solution to attack the interior of the steel.

"We thought of a possible solution for forming new pipe, based on changing the microstructure of the steel surface during forging, but it still needs to be tested and have a patent filed if it works," said Sandia's principle investigator Katherine Jungjohann, a paper author and lead microscopist. "But now we think we know where the major problem is."

Aramco senior research scientist Steven Hayden added, "This was the world's first real-time observation of nanoscale corrosion in a real-world material -- carbon steel -- which is the most prevalent type of steel used in infrastructure worldwide. Through it, we identified the types of interfaces and mechanisms that play a role in the initiation and progression of localized steel corrosion. The work is already being translated into models used to prevent corrosion-related catastrophes like infrastructure collapse and pipeline breaks."

To mimic the chemical exposure of pipe in the field, where the expensive, delicate microscopes could not be moved, very thin pipe samples were exposed at Sandia to a variety of chemicals known to pass through oil pipelines.

Sandia researcher and paper author Khalid Hattar put a dry sample in a vacuum and used a transmission electron microscope to create maps of the steel grain types and their orientation, much as a pilot in a plane might use a camera to create area maps of farmland and roads, except that Hattar's maps had approximately 6 nanometers resolution. (A nanometer is one-billionth of a meter.)

"By comparing these maps before and after the liquid corrosion experiments, a direct identification of the first phase that fell out of the samples could be identified, essentially identifying the weakest link in the internal microstructure," Hattar said.

Sandia researcher and paper author Paul Kotula said, "The sample we analyzed was considered a low-carbon steel, but it has relatively high-carbon inclusions of cementite which are the sites of localized corrosion attacks.

"Our transmission electron microscopes were a key piece of this work, allowing us to image the sample, observe the corrosion process, and do microanalysis before and after the corrosion occurred to identify the part played by the ferrite and cementite grains and the corrosion product."

When Hayden first started working in corrosion research, he said, "I was daunted at how complex and poorly understood corrosion is. This is largely because realistic experiments would involve observing complex materials like steel in liquid environments and with nanoscale resolution, and the technology to accomplish such a feat had only recently been developed and yet to be applied to corrosion. Now we are optimistic that further work at Sandia and the Center for Integrated Nanotechnologies will allow us to rethink manufacturing processes to minimize the expression of the susceptible nanostructures that render the steel vulnerable to accelerated decay mechanisms."

Invisible path of localized corrosion

Localized corrosion is different from uniform corrosion. The latter occurs in bulk form and is highly predictable. The former is invisible, creating a pathway observable only at its endpoint and increasing bulk corrosion rates by making it easier for corrosion to spread.

"A better understanding of the mechanisms by which corrosion initiates and progresses at these types of interfaces in steel will be key to mitigating corrosion-related losses," according to the paper.

WASHINGTON, D.C., JUNE 6 -- Sustainability-driven new research could one day help tuna fisheries cast their nets more selectively, mitigating unintentional "bycatch" of undersized fish and off-limits species.

The key development is an innovative application of electronic fish-finders like those commonly used by commercial tuna fleets. A multinational research team conducted the investigation under the sponsorship of the International Seafood Sustainability Foundation (ISSF).

In a research article titled Acoustic Discrimination of Tropical Tuna, published today in PLOS ONE, the peer-reviewed open-access journal of the Public Library of Science, the ISSF team's findings address a chronic challenge for commercial fishing fleets: How is it possible to identify and harvest mature, sustainable tuna without disturbing young fish or other species in the same vicinity?

As corresponding author Gala Moreno, Ph. D., explains, "If you're working with land animals, you can walk right up to the herd and count them by size and species. But, typically, fish are out of your reach, hard to see, and constantly moving in three dimensions."

Tuna support some of the world's largest and most valued fisheries. The prevailing technique in many tuna fisheries worldwide employs large "purse seine" nets to collect everything that swims inside a circle of up to 500 meters (about a third of a mile) across and as much as 180 meters deep. Typically, purse-seine fishing is conducted near fish-aggregating devices (FADs), passive structures built to exploit marine life's tendency to gather beneath floating objects.

In an ideal scenario, a purse-seine vessel would head for a given FAD where shipboard or FAD-based electronics have detected a promising mass of fish. Then (again, ideally) the crew would set its net and haul in a uniform catch of mature skipjack tuna, a favored species that's considered plentiful enough to be caught sustainably.

In practice, however, FADs attract mixed populations that include unacceptably small skipjack, as well as yellowfin and bigeye tuna of all sizes, which can be proscribed in certain waters. But sorting them out before the net closes in is practically impossible. A technology capable of analyzing the proportions of various tuna species swimming together, at a distance, would:

Help fishing-vessel skippers selectively target sustainable species

Save fuel and reduce marine-engine emissions by guiding vessels more directly to the right fishing grounds

Reduce wasteful bycatch and the mortality of vulnerable species

Current acoustic technology can detect schools of tuna around FADs remotely, but so far no conventional onboard or FAD-mounted device can distinguish fine detail such as fish sizes or species. Based on innovative field work, performed at sea on commercial fishing vessels, the new paper explores a technique for repurposing standard echolocation devices to predict not only the quantities but also the mix of sizes and species in an aggregation of fish.

A key factor is the gas-filled swim bladder that regulates buoyancy in most bony fishes. The interface between the trapped gas and the bladder envelope is an effective sound reflector. Marine echolocation devices work primarily by emitting powerful sonic pulses, then reading the sound that bounces back from that interface or other tissue. Each species reflects certain frequencies more strongly than others, so each presents a distinctive acoustic signature.

Bigeye and yellowfin are equipped with similar swim bladders, but skipjack make do with no swim bladders at all. The resulting difference in acoustic signatures could eventually help skippers distinguish skipjack from bigeye and yellowfin remotely.

Although acoustic properties have long been used to assess the abundance and species of fish other than tuna, the ISSF team's work has produced the first sonic-discrimination data that could lead to practical, selective tuna fishing techniques around FADs in the tropics.

Instruments on board the team's host vessel supplied an unprecedented level of calibrated acoustic data describing the frequency responses of tropical tuna. Measurements stemming from the vessel's capture of entire tuna aggregations were vastly more reliable than comparable data gathered in earlier surveys involving smaller-scale fishing operations.

According to Dr. Moreno, "Our research opens the door to several positive developments: faster growth of knowledge about the acoustic properties of tropical tunas; the advantages of close collaboration with commercial operations in support of science; definition of the conditions necessary for applying this technology for selective fishing; and projections of other uses of direct acoustic observations, as direct indices of tropical tuna abundance, to support tuna conservation."

Tohoku University researchers have developed a technique using a hollow
sphere to measure the electronic and optical properties of large semiconducting crystals. The approach, published in the journal Applied Physics Express, improves on current photoluminescence spectroscopy techniques and could lead to energy savings for mass producers, and thus consumers, of power devices.

Semiconducting crystals are used to make electronic devices like microprocessor chips and transistors. Manufacturers need to be able to detect crystal defects and test their energy conversion efficiency. One way to do this is to measure their 'internal quantum efficiency', or their ability to generate photons from electrons excited by an electric current or an excitation laser. Currently available methods limit the sample size that can be tested at a time.

Advanced materials scientist Kazunobu Kojima of Tohoku University and colleagues devised a modified approach to photoluminescence spectroscopy that can test larger samples.

Standard photoluminescence spectroscopy detects the relative amount of light emitted by a semiconductor crystal when an excitation laser is shone on it. Light energy is lost through these excitation and emission processes, so scientists have been experimenting with photoluminescence spectroscopy that uses an 'integrating sphere' to minimize the loss of photons, the elementary particles of light.

Integrating spheres collect both the excitation light and the light emitted from a sample lying inside it, where the light is diffusively reflected inside until it becomes uniformly dispersed. The uniform distribution of light improves the accuracy and repeatability of internal quantum efficiency testing. But this means that the size of the crystal being tested is ultimately limited by the size of the sphere.

Kojima and colleagues found they could still test the internal quantum efficiency of a crystal when it was placed directly outside the sphere, allowing larger samples to be used.

They conducted their tests on a semiconducting crystal called gallium nitride, which
is commonly used in LEDs and is expected to be used in electronic devices because of its superior properties.

"This 'omnidirectional photoluminescence' spectroscopy can be used to evaluate the quality of large-sized crystals or semiconductor wafers, which are essential for the mass production of power devices," says Kojima, adding that this could lead to energy saving and reduce production costs.

Irvine, Calif., June 6, 2019 - In a paper published this week in Nature, materials science researchers at the University of California, Irvine and other institutions unveil a new process for producing oxide perovskite crystals in exquisitely flexible, free-standing layers.

A two-dimensional rendition of this substance is intriguing to scientists and engineers, because 2D materials have been shown to possess remarkable electronic properties, including high-temperature superconductivity. Such compounds are prized as potential building blocks in multifunctional high-tech devices for energy and quantum computing, among other applications.

"Through our successful fabrication of ultrathin perovskite oxides down to the monolayer limit, we've created a new class of two-dimensional materials," said co-author Xiaoqing Pan, professor of materials science & engineering and Henry Samueli Endowed Chair in Engineering at UCI. "Since these crystals have strongly correlated effects, we anticipate they will exhibit qualities similar to graphene that will be foundational to next-generation energy and information technologies."

For all of their promising physical and chemical properties, oxide perovskites are difficult to render in flat layers due to the clunky, strongly bonded structure of their crystals. Earlier efforts at making free-standing, monolayer films of the material through the pulsed laser deposition method failed.

Pan's cross-disciplinary group of researchers applied a technique called molecular beam epitaxy to grow the thin oxide films layer by layer on a template with a water-dissolvable buffer, followed by etching and transfer.

"Most of the known two-dimensional materials can be synthesized by exfoliation or by chemical deposition, as their bulk crystals consist of unique layered structures in which many strong covalently bonded planes are held together by weak van der Waals interactions," he said. "But oxide perovskite is different; like most oxide materials, it has strong chemical bonds in three dimensions, making it especially challenging to fabricate into two dimensions."

Pan, who holds a dual appointment as a professor of physics & astronomy and directs the Irvine Materials Research Institute, said that molecular beam epitaxy is a more precise method for growing oxide perovskite thin films with almost no defects. He knows this because his research team was able to review its work at atomic resolution using aberration-corrected transmission electron microscopy.

"TEM played a crucial role in this project, because it provided important feedback for the optimization of film growth conditions and allowed us to directly observe novel phenomena, including the crystal symmetry breaking and unexpected polarization enhancement under the reduced dimension," Pan said.

"Given the outstanding physical and chemical properties of oxide perovskites and novel phenomena emergent at the monolayer limit, this work opens new possibilities in the exploration of quantum behaviors in strongly correlated two-dimensional materials," he added.

Pan and his team at UCI were joined by collaborators at China's Nanjing University and the University of Nebraska. They used TEM facilities at UCI's Irvine Materials Research Institute. The project was supported by the U.S. Department of Energy Office of Basic Energy Sciences' materials sciences and engineering division, under grant DE-SC0014430.

ANU and Uni of Melbourne Archaeologists have discovered 15 new sites in Laos containing more than one hundred 1000-year-old massive stone jars possibly used for the dead.

The jars of Laos are one of archaeology's enduring mysteries. Experts believe they were related to disposal of the dead, but nothing is known about the jars' original purpose and the people who brought them there.

The new finds show the distribution of the jars was more widespread than previously thought and could unlock the secrets surrounding their origin.

The sites, deep in remote and mountainous forest and containing 137 jars, were identified by ANU PhD student Nicholas Skopal with officials from the Lao government.

"These new sites have really only been visited by the occasional tiger hunter. Now we've rediscovered them, we're hoping to build a clear picture about this culture and how it disposed of its dead," said Mr Skopal.

ANU archaeologist Dr Dougald O'Reilly and Dr Louise Shewan from the University of Melbourne co-led the team that made the discovery. Dr O'Reilly said the new sites show the ancient burial practices involving the jars was "more widespread than previously thought".

"It's apparent the jars, some weighing several tonnes, were carved in quarries, and somehow transported, often several kilometres to their present locations," Dr O'Reilly.

"But why these sites were chosen as the final resting place for the jars is still a mystery. On top of that we've got no evidence of occupation in this region."

This year's excavations revealed beautifully carved discs which are most likely burial markers placed around the jars. Curiously, the decorated side of each disc has been buried face down.

Dr O'Reilly said the imagery on the discs found so far included concentric circles, pommels, human figures and creatures.

"Decorative carving is relatively rare at the jar sites and we don't know why some discs have animal imagery and others have geometric designs," Dr O'Reilly said.

Among typical iron-age artefacts found with the burials - decorative ceramics, glass beads, iron tools, discs worn in the ears and spindle whorls for cloth making - one particular find piqued the researchers' interest.

"Curiously we also found many miniature jars, which look just like the giant jars themselves but made of clay, so we'd love to know why these people represented the same jars in which they placed their dead, in miniature to be buried with their dead," Dr O'Reilly said.

"We've seen similar megalithic jars in Assam in India and in Sulawesi in Indonesia so we'd like to investigate possible connections in prehistory between these disparate regions."

Dr O'Reilly and his co-research Director on the project, Dr Louise Shewan, from the University of Melbourne would like to acknowledge Dr Thonglith Luangkoth of the Ministry of Information, Culture and Tourism without whose kind hospitality none of our research would be possible.

A new study by University of Alberta scientists shows that banded iron formations originated from oxidized iron, confirming the relevance and accuracy of existing models--a finding of great importance to the geological community.

Banded iron formations are a distinct type of sedimentary rock with layers of iron deposited as horizontal bands. The majority of these formations formed over the last 2.5 billion years and are a major source of iron today. "We've been using banded iron formations with great success to track the evolution of seawater chemistry and evolution of the biosphere," explained Kurt Konhauser, professor in the Department of Earth and Atmospheric Sciences and co-author on the paper. "But these experiments are based on the assumption that we understand the primary minerals that compose these rocks."

In the last decade, a new model was proposed, suggesting that the formations began as ferrous iron that was later oxidized by oxygen in the environment--a model that, if correct, would require a major paradigm shift in this area of study.

To examine this possibility, a group of researchers led by Konhauser's PhD student Leslie Robbins tested the theory using a hydrogeological model, designed to determine how long it would take oxygen to oxidize such a formation. The research team included Professor Ben Roston, Assistant Professor Daniel Alessi, and Professor Larry Heaman.

"Essentially, we found that this would be possible in only one per cent of cases in the suggested time frame of 250 million years," said Konhauser. "Moreover, we had to create unrealistic conditions in order to make the new proposed model work--for instance, an extremely steep slope, or rock that was actually sand, or a great deal of oxygen."

These results confirmed that the newly proposed model is inaccurate, indicating that existing models and our current understanding remains the most effective method of studying banded iron formations.

"This is a powerful result that stems from the simple question about whether recently proposed models for banded iron formations are plausible when extrapolated to the size of a depositional basin," said Robbins, now a postdoctoral fellow at Yale University in New Haven, United States. "This result has fundamental implications for the formation of these deposits, and this work benefited greatly from strong collaborations both within Earth and Atmospheric Sciences and with our external collaborators."

Researchers in Punta Tombo, Argentina conducted a study to see whether Magellanic penguins (Spheniscus magellanicus) showed lateralization (handedness) in their behaviors or morphology.

They found no lateralization or mixed results in the population of Magellanic penguins in three individual behaviors: stepping up, swimming, and thermoregulation.

They did find lateralization when penguins fought for dominance with the more aggressive penguin using its left eye and attacking the other penguin's right side in most fights.