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TAMPA, Fla. (June 18, 2019) -- Air pollution significantly increases the risk for premature deaths, particularly in people with underlying cardiovascular disease, clinical and epidemiological studies have determined.

In healthy people, inhaling ozone or particle pollution triggers a defensive lung-heart reflex (pulmonary-cardiac reflex) that automatically slows heart rate to accommodate oxygen deficiency and help slow distribution of pollutants throughout the body. Yet, when patients with cardiovascular diseases breathe pollutants that same protective mechanism does not kick in. Instead, their heart rates intermittently speed up, known as tachycardia, and can evoke a potentially deadly irregular heart rhythm, known as premature ventricular contractions.

What accounts for the difference? University of South Florida Health (USF Health) researchers who study the role of sensory airway nerves in protective behaviors wanted to know.

Their preclinical findings, reported May 11 in The Journal of Physiology, help explain the altered physiological response to air pollution in patients with preexisting cardiovascular disease.

Using a rat model for high blood pressure (hypertension), a common chronic cardiovascular condition, the USF Health team found that preexisting hypertension altered normal reflexes in the lungs to affect autonomic regulation of the heart when an irritant mimicking air pollution was inhaled. In particular, hypertension appeared to shift the reflex response from the parasympathetic nervous system to the sympathetic nervous system. The sympathetic nervous system mobilizes the body's defensive "fight-or-flight" response to a threat, including releasing adrenaline that increases heart rate. In contrast, the parasympathetic nervous system controls involuntary responses, including breathing and heart rate, while the body is at rest and maintains a state of calm.

"The speeding up of heart rate and abnormal heart beats (in the hypertensive rats) were due to the switching on of this 'flight-or-fight' nervous system not seen in the healthy animals exposed to noxious agents," said senior author Thomas Taylor-Clark, PhD, associate professor of molecular pharmacology and physiology in the USF Health Morsani College of Medicine. "The heart was responding to an aberrant nerve-generated reflex that may worsen preexisting cardiovascular disease."

To simulate effects of air pollution inhaled into the lungs -- difficult to recreate in a laboratory setting -- the USF researchers used allyl isothiocyanate, the pungent ingredient in wasabi and horseradish. When healthy rats with normal blood pressure inhaled this irritant, their heart rates slowed as expected. But, in the rats with chronic hypertension, inhaling the same irritant stimulated an increased heart rate accompanied by premature ventricular contractions.

Surprisingly, a rapid heart rate and abnormal heart rhythm did not occur when allyl isothiocyanate was intravenously injected into the hypertensive rats.

"It did not evoke the peculiar reflex; instead, we observed a slowing of the heart rate like that seen in the rats with normal blood pressure," Dr. Taylor-Clark said. "This suggests that the sensory airway nerves accessible by IV are different than those accessible by inhalation... so perhaps the pathways of airway sensory nerves (connecting organs like the heart and lungs with the brainstem,) are more complex than previously understood."

Chronic hypertension may remodel airway sensory nerves controlling the pulmonary-cardiac reflex that helps defend the body against physical damage from air pollution, the USF study suggests. This remodeling, which may happen in the developmental stages of hypertension, could turn on inappropriate sympathetic nervous system excitation of the heart, Dr. Thomas-Taylor said.

By better understanding how cardiovascular disease changes neuronal interactions between the heart and lungs, the researchers hope to help doctors with treatment choices - and eventually discover new treatments.

"Our goal is to add another piece of information that clinicians could consider when selecting a best treatment for hypertension. In addition to the patient's age, ethnicity and race, that might include whether the person lives in an area with high pollution levels," he said. "In the long-term, if we can identify the nervous system mechanisms involved in remodeling the pulmonary-cardiac reflex, we can target those to develop new blood pressure drugs."

WASHINGTON, D.C. (June 18, 2019) - Two years after their child "comes out" as lesbian, gay or bisexual (LGB), many parents still say that it is moderately or very hard for them to adjust to the news, according to a study published today. Those responses are the same, on average, as parents who have recently learned about their child's sexual orientation, a finding that suggests most parents struggle with such news for several years.

The results are important because previous studies suggest parents who have trouble adjusting are more likely to disapprove or adopt negative behaviors that can, in turn, put LGB youth at risk of serious health problems.

"Surprisingly, we found that parents who knew about a child's sexual orientation for two years struggled as much as parents who had recently learned the news," said David Huebner, PhD, MPH, associate professor of prevention and community health at the George Washington University Milken Institute School of Public Health (Milken Institute SPH). "Two years is a very long time in the life of a child who is faced with the stress of a disapproving or rejecting parent."

This study is one of the first and largest to survey parents themselves, Huebner said. In addition, the study includes data from parents rarely ever studied, Huebner said, noting that 26 percent of the parents surveyed had only learned their son or daughter identified as LGB in the past month.
Huebner and his colleagues studied more than 1,200 parents of LGB youth ages 10 to 25. The researchers asked parents who visited a website with LGB resources to fill out a questionnaire.

Huebner and his colleagues asked parents "How hard is it for you, knowing that your son or daughter is gay, lesbian or bisexual?" Parents responded using a five-point scale of magnitude that ranged from not at all hard to extremely hard.

The researchers found:

Parents who had learned about their child's sexual orientation two years ago reported struggling just as much as parents who had been told very recently;

African American and Latino parents reported greater trouble adjusting compared to white parents;

Parents of older youth said they had greater levels of difficulty compared to parents of younger children;

Fathers and mothers reported similar levels of difficulty as did parents of boys and girls.

Huebner says that the difficulty most parents experience runs a developmental course with most gradually adjusting over a long period. Parents in this study who had known for five years or longer reported having the least amount of trouble with the fact that their child is LGB.

Parents who have trouble accepting the news may worry that their child might face a more difficult life, one that includes bullying or harassment. Others need time to adjust because they have long imagined a traditional heterosexual future for their child, Huebner said.

Previous research by this team suggests that if parents reject their child or react negatively - even for a few years--it takes a toll on the parent-child relationship. Negative parenting behaviors run the gamut from mild disapproval to outright rejection. Huebner's research and other studies suggest such behavior puts the child at high risk of depression, suicide, substance abuse and other health risks.

Still, Huebner says most parents, even those in shock when first learning the news, care deeply about their children and eventually do adjust.

"Our results suggest interventions to speed up the adjustment process would help not only the parents but also their children," Huebner said. "LGB youth with accepting families are more likely to thrive as they enter adulthood."

Huebner and his team have created a website, Lead With Love, that contains evidence-based resources for families, including a documentary film, to help support parents who have just learned about a child's sexual orientation.

At the same time, the researchers say much more needs to be done. For example, this study looked at parents and their reaction at a snapshot in time. Additional research must be done that follows parents and children to see how the relationship changes over the months and years. Such studies could help researchers develop better supports for families - ones that would help keep the relationship between parents and children healthy and strong.

The study, "Effects of Family Demographics and the Passage of Time on Parents' Difficulty with Their Lesbian, Gay or Bisexual Youth's Sexual Orientation," was published in the journal Archives of Sexual Behavior. The National Institute of Mental Health funded the study.

CORVALLIS, Ore. - Researchers at Oregon State University and Oregon Health & Science University have found a possible counterpunch to the drug resistance of melanoma, the most dangerous form of skin cancer.

The findings, published today in the journal Molecular Carcinogenesis, are important because in the United States alone, almost 100,000 new melanoma cases will be diagnosed this year and more than 7,000 melanoma patients are expected to die.

Oregon ranks 15th in the U.S. in per-capita diagnoses, with melanoma afflicting 27 out of every 100,000 Oregonians. Men are more likely than women to develop melanoma; the death rate varies by race and ethnicity and is highest among white people.

Nationwide, melanoma is the fifth-most common cancer and its incidence is on the rise, noted Arup Indra, associate professor in the OSU College of Pharmacy, a member of OHSU's Knight Cancer Institute and an affiliate investigator at Oregon State's Linus Pauling Institute. One of the most aggressive cancers, it kills by metastasizing, or spreading, to other organs such as the liver, lungs and brain.

Indra's team and collaborators at Oregon State and in the Department of Dermatology at OHSU looked for ways to combat the drug resistance that metastatic melanoma cells often quickly develop.

"Breakthroughs in understanding the molecular basis for the disease have led to a couple of different drugs, vemurafenib and dabrafenib, that elicit dramatic clinical responses in patients with metastatic melanoma containing a mutation in a certain gene," he said. "But the drugs' effectiveness is limited by a high incidence of resistance, which inevitably leads to disease relapse in six or eight months. The current five-year survival rate of stage IV metastatic melanoma is less than 50%."

The researchers directed their efforts toward melanoma metabolism - the chemical processes the cells rely on to thrive. Cancer cells have a metabolism that's been altered from that of normal cells.

At the High Throughput Screen Lab at OSU, the scientists tested almost 9,000 compounds, some of them drugs already approved by the FDA, against a vemurafenib-resistant melanoma cell line to see if any of them would halt proliferation or induce cell death.

They found that two structurally similar compounds - deguelin and rotenone, naturally occurring pesticides produced by many plant species - interfered with the cancer cells' metabolism. Further testing with deguelin showed that it inhibited oxygen consumption in the cells' mitochondria, effectively starving the cells of energy.

"Having a metabolic regulator of metastatic melanoma will be a very attractive treatment option," Indra said. "This drug has been known as a treatment for other cancer types, but its utility as a metabolic regulator in drug-resistant metastatic melanoma has not been shown or demonstrated before."

RICHLAND, WASHINGTON, June 18, 2019 - An advanced manufacturing process to produce nano structured rods and tubes directly from high-performance aluminum alloy powder -- in a single step -- was recently demonstrated by researchers from the Pacific Northwest National Laboratory.

Using a novel Solid Phase Processing approach, the research team eliminated several steps that are required during conventional extrusion processing of aluminum alloy powders, while also achieving a significant increase in product ductility (how far a material can stretch before it breaks).

This is good news for sectors such as the automotive industry, where the high cost of manufacturing has historically limited the use of high-strength aluminum alloys made from powders.

The team's research is described in the paper "High Ductility Aluminum Alloy Made from Powder by Friction Extrusion," published in the June 2019 issue of Materialia.

Stepping Away from Conventional Extrusion

High-performance aluminum alloys made from powder have long been used in lightweight components for specialized aerospace applications, where cost is not a limiting factor. However, these alloys have typically been too expensive for the automotive industry.

A typical extrusion process for aluminum alloy powders is energy-and process-intensive, requiring multiple steps to mass produce the material. First, the loose powder must be loaded into a can and gases removed using a vacuum, which is called "degassing." The can is then sealed, hot pressed, pre-heated, and placed into the extrusion press. After extrusion, the can is removed, or "decanned," to reveal the extruded part made from consolidated powder.

In this study, the team eliminated many of these steps, extruding nanostructured aluminum rods directly from powder in a single step, using PNNL's Shear Assisted Processing and Extrusion technology, or ShAPE™.

Extrusion of aluminum alloys directly from powder elimates canning, de-gassing, hot isostatic pressing, de-canning, and billet pre-heating

In the ShAPE™ process, a powder -- in this case, an Al-12.4TM aluminum alloy powder provided by SCM Metal Products, Inc., a division of Kymera International -- is poured into an open container. A rotating extrusion die is then forced into the powder, which generates heat at the interface between the powder and die. The material softens and easily extrudes, eliminating the need for canning, degassing, hot pressing, pre-heating, and decanning.

"This is the first published instance of an aluminum alloy powder being consolidated into nano structured extrusions using a single-step process like ShAPE™," said PNNL materials scientist Scott Whalen, who led the study.

He added, "The elimination of both the processing steps and the need for pre-heating could dramatically reduce production time as well as lower the cost and overall embedded energy within the product, which could be beneficial for automotive manufacturers who want to make passenger vehicles more affordable, lighter, and fuel-efficient for the consumer."

Besides providing the Al-12.4TM powder, SCM Metals Products, Inc. performed mechanical testing to validate the resulting material's performance. PNNL and SCM Metal Products, Inc. are now collaborating on a project for DOE's Office of Technology Transitions to scale up the process for larger diameter extrusions.

Ductility--It's a Stretch

Elimination of processing steps and reduced heating weren't the only successful findings by the team.

While high-performance aluminum alloys have historically shown excellent strength, they have typically been hampered by poor ductility. However, the team found dramatic improvements in the ductility of the extrusion produced by ShAPE™, measuring ductility that is two to three times that found in conventional extrusion products, and with equivalent strength.

To understand the reason for the substantial increase in ductility, transmission electron microscopy was used to evaluate the microstructures of the powder and the extruded materials. The results indicated that the ShAPE™ method refined the second phases in the powder--tiny strengthening particles of non-aluminum materials. ShAPE™ reduces the particles to nanoscale sizes and evenly distributes them throughout the aluminum matrix, increasing ductility.

Inflammation in a sound-processing region of the brain mediates ringing in the ears in mice that have noise-induced hearing loss, according to a study publishing June 18 in the open-access journal PLOS Biology by Shaowen Bao of the University of Arizona, and colleagues.

Hearing loss is a widespread condition that affects approximately 500 million individuals, and is a major risk factor for tinnitus -- the perception of noise or ringing in the ears. Recent studies indicate that hearing loss causes inflammation -- the immune system's response to injury and infection -- in the auditory pathway. But its contribution to hearing loss-related conditions such as tinnitus is still poorly understood. To address this gap in knowledge, Bao and his colleagues examined neuroinflammation -- inflammation that affects the nervous system -- in the auditory cortex of the brain following noise-induced hearing loss, and its role in tinnitus, in rodent models.

The results indicate that noise-induced hearing loss is associated with elevated levels of molecules called proinflammatory cytokines and the activation of non-neuronal cells called microglia -- two defining features of neuroinflammatory responses--in the primary auditory cortex. Experiments in mice that incur noise-induced hearing loss showed that a cell-signaling molecule called tumor necrosis factor alpha (TNF-α) mediates neuroinflammation, tinnitus, and synaptic imbalance -- an altered pattern of signaling between neurons. Moreover, the researchers found that pharmacological blockade of TNF-α or depletion of microglia prevented tinnitus in mice with noise-induced hearing loss. According to the authors, the findings suggest that neuroinflammation may be a therapeutic target for treating tinnitus and other hearing loss-related disorders.

Self-reported rates of cigarette smoking increased in minority 11th and 12th graders after affirmative action bans were implemented in their state, according to a new study published this week in PLOS Medicine by Atheendar Venkataramani of the University of Pennsylvania, and colleagues.

Between 1996 and 2013, nine US states banned race-based affirmative action in college admissions. In the new study, researchers used data from the 1991-2015 US National Youth Risk Behavior Survey to investigate health behaviors, comparing changes in self-reported cigarette and alcohol use among students residing in states implementing such bans and those residing in states without bans. The dataset included information on more than 35,000 high school students.

Rates of cigarette smoking in the 30 days prior to the survey apparently increased by 3.8 percentage points in under-represented minority students after affirmative action bans were enacted (95% CI 2.0-5.7; p

"Our study suggests that ongoing efforts to ban affirmative action programs in college admissions may have unanticipated adverse effects on health risk behaviors and health status within under-represented minority populations," the authors say. "In doing so, they may exacerbate short- and long-run disparities in health outcomes." The authors also note that their results, more generally, illustrate the importance of policies that shift socioeconomic opportunities as a key determinant of health.

New research publishing June 18 in the open-access journal, PLOS Biology, led by Dr Lucy Taylor from the University of Oxford's Department of Zoology now reveals that homing pigeons fit in one extra wingbeat per second when flying in pairs compared to flying solo.

Birds that fly in 'V'-formations, such as geese, are able to conserve energy by flying in aerodynamically optimal positions. By contrast, in species that don't fly in formation, such as homing pigeons, the costs and benefits of flocking have been less well understood.

The research indicates that flying with another bird requires more energy compared to flying solo. 'The results of this study were completely unexpected. Energy is the currency of life so it's astonishing that the birds are prepared to pay a substantial energetic cost to fly together," said lead-author, Dr Lucy Taylor.

The team used high frequency GPS and accelerometer bio-loggers to measure how pigeons changed their wingbeat patterns when flying in pairs compared to flying solo. The accelerometers act much like fitness trackers but, instead of measuring steps, the researchers measure wingbeats. 'The increase in wingbeat frequency is equivalent to Usain Bolt running the 100m sprint at his usual speed, whilst fitting in nearly one extra step per second. The pigeons are flapping faster when flying in pairs but hardly going any faster," said Dr Taylor.

The increase in wingbeat frequency is likely to be related to the demands of coordinating flight. Dr Taylor said: 'Imagine trying to coordinate with and avoid hitting another small object travelling at around 44 miles per hour. This is nearly two times faster than an Olympic sprinter, and the birds can move up and down as well as left and right. For a pigeon, flapping your wings faster will both give you faster reactions and greater control over your movements, and will help keep your head stable making it easier to track where the other bird is.'

Despite the costs of fitting in one additional wingbeat per second, the birds consistently chose to fly together, suggesting that they were able to gain other benefits from flocking. Birds flying in a pair were simultaneously able to improve their homing accuracy, meaning that they could conserve energy by flying shorter routes home. Combined with increased predator protection from safety in numbers, this research suggests that the overall benefits of flocking outweigh the immediate energetic costs of changing wingbeat patterns.

PHILADELPHIA - Transitions are a hallmark of life. When dormant plants flower in the spring or when a young adult strikes out on their own, there is a shift in control. Similarly, there is a transition during early development when an embryo undergoes biochemical changes, switching from being controlled by maternal molecules to being governed by its own genome. For the first time, a team from the Perelman School of Medicine at the University of Pennsylvania found in an embryo that activation of its genome does not happen all at once, instead it follows a specific pattern controlled primarily by the various sizes of its cells. The researchers published their results this week as the cover story in Developmental Cell.

In an early embryo undergoing cell division, maternally loaded RNA and proteins regulate the cell cycle. The genomes of the zygote--a term for the fertilized egg--are initially in sleep mode. However, at a point in the early life of the embryo, these zygotic nuclei "wake up" and expression from their genomes takes biochemical control over subsequent embryo development. But how an embryo "recognizes" when to undergo this transition has remained unknown.

"How an embryo 'hands over' control of development from mother to zygote is a fundamental question in developmental biology," said senior author Matthew C. Good, PhD, an assistant professor of Cell and Developmental Biology and of Bioengineering. "Previously it was not appreciated that different regions of a vertebrate embryo can undergo genome activation at different times, or how directly cell size regulates the awakening of a zygote's genome."

Different hypotheses have been offered over the last 40 years to explain how an embryo discerns when to turn on the new genome of individual cells within the zygote, but it was the Penn team who nailed the mechanism and answered this key question.

Using single-cell imaging of embryos from the African clawed frog (Xenopus laevis), they found that cell size was the key parameter governing the start of genome activation in zygotes. Cells must achieve a threshold size to initiate large-scale transcription of their own proteins. By generating miniature embryos, the team demonstrated that changes in cell size control the timing of genome activation.

The results of this study have a number of important implications for the basic understanding of how an embryo develops in its earliest days and for the field of developmental biology in general. The Penn team believes this finding could impact how other investigators approach their own research on genome activation and screening for maternal factors that are necessary to control the fidelity of early embryo development.

"To gain new insights, zygotic transcription should be measured at a single-cell level," said first author Hui Chen, PhD, a postdoctoral fellow in Good's lab. "This approach helped us to not overlook the influence of the spatial organization of an embryo's cells on the maternal-zygotic transition."

The 'decision' to initiate the zygote's genome is made at the level of individual cells, not the entire embryo, which has changed the Penn team's view of the developmental process. "Evolution has co-opted cell size as a regulatory mechanism to control a critical transition in embryonic development, a paradigm that may extend to other areas of biology in which cell size varies," said Good. He and Chen plan to continue this work by measuring genome activation in zebrafish and mice to see if this new perspective holds true in other species.

WASHINGTON, D.C., June 18, 2019 -- Cancer touches nearly everyone in one way or another, and regrettably, it will claim another 600,000 lives in the U.S. in 2019, according to the American Cancer Society. Researchers from San Diego State University, TumorGen MDx Inc., and Sanford Burnham Prebys Medical Discovery Institute set out to explore a seemingly basic question: What is it about cancer that kills?

The answer is, about 90% of cancer deaths are due to metastases, when tumors spread to other vital organs. How does cancer metastasize? After an exhaustive search of the scientific literature, the researchers realized that it's not individual cells but rather distinct clusters of cancer cells that circulate and metastasize to other organs.

As the group reports in AIP Advances, from AIP Publishing, this caused them to question -- if these cell clusters are the "root causes of cancer," why isn't more research being devoted to gaining a better understanding of circulating cancer cell clusters?

"The reason for such little research activity is the overwhelming difficulty of capturing these extremely rare metastatic cancer cell clusters from a patient's blood sample," said Peter Teriete, one of the authors and a research assistant professor at Sanford Burnham Prebys Medical Discovery Institute. "But we realized that if we're ever going to understand the complex process of cancer metastasis, we'd need to develop a tool to easily find these clusters."

To do this, the researchers first identified the basic requirements essential to collecting useful information from isolated cancer cell clusters. It involves a sample size large enough to likely contain appreciable numbers of cancer cell clusters (about 10 milliliters of whole blood), as well as using whole blood to preserve rare circulating clusters. Whole blood, however, requires channel-coating procedures that reduce nonspecific binding properties to prevent biofouling. And the device channel dimensions must be of a suitable size to accommodate single cells and cancer cell clusters of varying diameters.

"Our device's channel design had to generate microfluidic flow characteristics suitable to facilitate cell capture via antibodies within the coated channels," Teriete explained. "So we introduced microfeatures -- herringbone recesses -- to produce the desired functionality. We also developed a unique alginate hydrogel coating that can be readily decorated with antibodies or other biomolecules. By connecting bioengineering with materials science and basic cancer biology, we were able to develop a device and prove that it performs as desired."

The group's microfluidic device brings a new therapeutic strategy to the fight against cancer metastasis. Capturing viable circulating cancer stem cell clusters directly from cancer patients is a novel approach for the development of new anti-metastatic drug therapies.

"Drug development that specifically targets distant metastases has been greatly restricted due to the lack of adequate tools that can readily access the metastatic cells responsible for cancer's dissemination," said Teriete. "Our microfluidic device will provide cancer researchers with actual human cancer cell clusters, so they can begin to understand the critical mechanisms involved with metastasis and develop highly effective drugs that ultimately can save more cancer patients' lives."

For a long time, ecologists have relied on their senses when it comes to recording animal populations and species diversity. However, modern programmable sound recording devices are now the better option for logging animal vocalisations. Scientists lead by the University of Göttingen have investigated this using studies of birds as an example. The results were published in the journal Ecological Applications.

"Data collection by people is less reliable, provides only approximate values, and is difficult to standardise and verify," says first author Dr Kevin Darras from the Department of Crop Sciences at the University of Göttingen. For comparison purposes, the international research team prepared a systematic overview based on data from previous bird studies. In addition to the collected sound recordings, they also compared the usefulness of both methods.

The result: sound recording devices can provide the same data as those obtained by people during bird "point counts" (the standard survey method where a person logs the birds they see or hear). Sound recordings can be used to measure population densities and map territories of individual species. They can also record entire soundscapes and better measure animal activity over long periods of time. "In a previous meta-analysis, we found that recording devices could detect and identify at least as many species as traditional ornithologists using standard techniques," says Darras. There are further advantages: enormous amounts of data can be checked, archived and automatically evaluated by computer programs to identify animal species.

"There are now very inexpensive, small devices that can record huge amounts of data over long periods of time and large spaces. In an increasingly data-driven time, they are the better choice." In addition to the systematic comparison, the study also provides a guide for scientists who sample the noises of animal populations acoustically. The authors give an overview of the currently available recording devices and discuss their modes of operation.

As a part of JST PRESTO program, Associate professor Masaharu Kobayashi, Institute of Industrial Science, the University of Tokyo, has developed a ferroelectric FET (FeFET) with ferroelectric-HfO2 and ultrathin IGZO channel. Nearly ideal subthreshold swing (SS) and mobility higher than poly-silicon channel have been demonstrated.

FeFET is a promising memory device because of its low-power, high-speed and high-capacity. After the discovery of CMOS-compatible ferroelectric-HfO2 material, FeFET has been attracting more attentions than ever before. For even higher memory capacity, 3D vertical stack structure has been proposed as shown in Fig. 1(a).

For 3D vertical stack structure, poly-silicon is typically used as a channel material. However, poly-silicon has very low mobility in nanometer thickness region due to grain boundaries and extrinsic defects. Moreover, poly-silicon forms a low-k interfacial layer with ferroelectric-HfO2 gate insulator. This results in voltage loss and charge trapping which prevents low voltage operation and degrades reliability, respectively as shown in Fig. 1(b).

To solve these problems, in this study, we proposed a ferroelectric-HfO2 based FeFET with ultrathin IGZO channel. IGZO is a metal-oxide semiconductor and can avoid low-k interfacial layer with ferroelectric HfO2 gate insulator. Moreover, since IGZO is N-type semiconductor and typically used in junctionless transistor operation, charge trapping, which seriously happens in inversion mode operation, can be avoided as shown in Fig. 1(b).

First, we systematically investigated optimum IGZO channel thickness. As IGZO thickness decreases, SS is reduced and threshold voltage (Vth) increases. To realize steep SS and normally-off operation, 8nm was chosen. Next, we fabricated TiN/HfZrO2/IGZO capacitor. HfZrO2 is the ferroelectric layer. Cross-sectional TEM image shows that each layer was uniformly formed as shown in Fig. 2(a). GIXRD spectrum was taken and ferroelectric phase was confirmed. By electrical characterization, we confirmed clear ferroelectric property with IGZO capping on HfZrO2 as shown in Fig. 2(b). It should be noted that, in the current device design, back-gate is needed with buried oxide to fix body potential. Without back-gate, body potential is floating and voltage cannot be sufficiently applied on ferroelectric-HfO2 gate insulator, which was confirmed by TCAD simulation. Based on these device design, we fabricated a FeFET with ferroelectric-HfO2 and ultrathin IGZO channel. Fig. 3(a) shows the measured drain-current versus gate-voltage after applying write and erase pulse voltages. 0.5V memory window and nearly ideal SS of 60mV/dec was obtained. In addition, field-effect mobility is about 10cm2/Vs as shown in Fig. 3(b), which can be higher than poly-silicon at the same thickness.

The achievements in this study will open a new path for realizing low-voltage and highly reliable FeFET with 3D vertical stack structure. This leads to enabling ultralow power IoT edge devices, deploying highly sophisticated network system, and thus providing more strategic social services utilizing big data.

HOUSTON -- (June 18, 2019) -- Rice University's solar-powered approach for purifying salt water with sunlight and nanoparticles is even more efficient than its creators first believed.

Researchers in Rice's Laboratory for Nanophotonics (LANP) this week showed they could boost the efficiency of their solar-powered desalination system by more than 50% simply by adding inexpensive plastic lenses to concentrate sunlight into "hot spots." The results are available online in the Proceedings of the National Academy of Sciences.

"The typical way to boost performance in solar-driven systems is to add solar concentrators and bring in more light," said Pratiksha Dongare, a graduate student in applied physics at Rice's Brown School of Engineering and co-lead author of the paper. "The big difference here is that we're using the same amount of light. We've shown it's possible to inexpensively redistribute that power and dramatically increase the rate of purified water production."

In conventional membrane distillation, hot, salty water is flowed across one side of a sheetlike membrane while cool, filtered water flows across the other. The temperature difference creates a difference in vapor pressure that drives water vapor from the heated side through the membrane toward the cooler, lower-pressure side. Scaling up the technology is difficult because the temperature difference across the membrane -- and the resulting output of clean water -- decreases as the size of the membrane increases. Rice's "nanophotonics-enabled solar membrane distillation" (NESMD) technology addresses this by using light-absorbing nanoparticles to turn the membrane itself into a solar-driven heating element.

Dongare and colleagues, including study co-lead author Alessandro Alabastri, coat the top layer of their membranes with low-cost, commercially available nanoparticles that are designed to convert more than 80% of sunlight energy into heat. The solar-driven nanoparticle heating reduces production costs, and Rice engineers are working to scale up the technology for applications in remote areas that have no access to electricity.

The concept and particles used in NESMD were first demonstrated in 2012 by LANP director Naomi Halas and research scientist Oara Neumann, who are both co-authors on the new study. In this week's study, Halas, Dongare, Alabastri, Neumann and LANP physicist Peter Nordlander found they could exploit an inherent and previously unrecognized nonlinear relationship between incident light intensity and vapor pressure.

Alabastri, a physicist and Texas Instruments Research Assistant Professor in Rice's Department of Electrical and Computer Engineering, used a simple mathematical example to describe the difference between a linear and nonlinear relationship. "If you take any two numbers that equal 10 -- seven and three, five and five, six and four -- you will always get 10 if you add them together. But if the process is nonlinear, you might square them or even cube them before adding. So if we have nine and one, that would be nine squared, or 81, plus one squared, which equals 82. That is far better than 10, which is the best you can do with a linear relationship."

In the case of NESMD, the nonlinear improvement comes from concentrating sunlight into tiny spots, much like a child might with a magnifying glass on a sunny day. Concentrating the light on a tiny spot on the membrane results in a linear increase in heat, but the heating, in turn, produces a nonlinear increase in vapor pressure. And the increased pressure forces more purified steam through the membrane in less time.

"We showed that it's always better to have more photons in a smaller area than to have a homogeneous distribution of photons across the entire membrane," Alabastri said.

Halas, a chemist and engineer who's spent more than 25 years pioneering the use of light-activated nanomaterials, said, "The efficiencies provided by this nonlinear optical process are important because water scarcity is a daily reality for about half of the world's people, and efficient solar distillation could change that.

"Beyond water purification, this nonlinear optical effect also could improve technologies that use solar heating to drive chemical processes like photocatalysis," Halas said.

For example, LANP is developing a copper-based nanoparticle for converting ammonia into hydrogen fuel at ambient pressure.

Halas is the Stanley C. Moore Professor of Electrical and Computer Engineering, director of Rice's Smalley-Curl Institute and a professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering.

NESMD is in development at the Rice-based Center for Nanotechnology Enabled Water Treatment (NEWT) and won research and development funding from the Department of Energy's Solar Desalination program in 2018.

Andriy Zakutayev knows the odds of a scientist stumbling across a new nitride mineral are about the same as a ship happening upon a previously undiscovered landmass.

"If you find any nitride in nature, it's probably in a meteorite," said Zakutayev, a scientist at the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL).

Formed when metallic elements combine with nitrogen, nitrides can possess unique properties with potential applications spanning from semiconductors to industrial coatings. One nitride semiconductor served as the cornerstone of a Nobel Prize-winning technology for light-emitting diodes (LEDs). But before nitrides can be put to use, they first must be discovered--and now, researchers have a map to guide them.

A groundbreaking research effort involving scientists at NREL; Lawrence Berkeley National Laboratory (LBNL); University of Colorado, Boulder (CU); and other partner institutions around the country recently published "A Map of the Inorganic Ternary Metal Nitrides," which appears in Nature Materials. The paper features a large stability map of the ternary nitrides, highlighting nitride compositions where experimental discovery is promising, and other compositions where nitride formation would be unlikely. For chemists attempting to create new nitrides in the laboratory, this map will be a significantly valuable tool.

Wenhao Sun, lead author of the paper and staff scientist at LBNL, likened materials discovery to the world exploration of bygone days. "Sailing into the unknown was a very risky endeavor," Sun explains, "and in the same way, exploration of new chemical spaces can also be risky. If you go into the lab and mix different elements together, you might make a new compound. Or you might not. If you don't find a new material where you are looking, it can be a big waste of time and effort. Maps help to guide explorers, allowing them to navigate better. Here, we built a chemical map to guide the exploratory synthesis of nitrides."

An interactive version of the map shows stable ternary nitrides highlighted in blue, indicating that they are good candidates for experimentation.

This research was supported by the Center for Next Generation of Materials Design: Incorporating Metastability (CNGMD), an Energy Frontier Research Center (EFRC) funded by DOE's Office of Science. As one of 46 EFRCs, CNGMD is tasked with discovering new materials for use in energy research. NREL Associate Laboratory Director for Materials and Chemical Science and Technology Bill Tumas, a co-author of the recent study, serves as director of CNGMD.

Other research funded by the center has discovered new ways to combine materials to form alloys, as well as to synthesize specific material polymorphs that could form the basis of next-generation semiconductors. The new nitrides research follows several years of investigating metastable materials and the potential to use them in various technologies, including semiconductors.

Graphic shows a series of different colored squares that chart where new nitrides can be found.

Exploring Metastable Materials

Metastable materials are those that, over time, will shift to become more stable. Diamonds, for example, are metastable as they would eventually turn into graphite, a more stable polymorph form of carbon. But the amount of time that takes is considerable--millions of years in this example--so researchers should not discount the use of metastable compounds.

"If you only do materials design with stable materials," Sun said, "your choices are limited. But if you start thinking about which metastable materials can be made, you increase your design space."

"Our EFRC team set out to include metastable compounds into materials design," added Tumas. "This work demonstrates the power of collaborations between theorists and experimentalists, combining computational, synthetic, and characterization skills in a team approach."

In addition to NREL, CU, and LBNL, scientists from Oregon State University and SLAC National Accelerator Laboratory lent their expertise in mapping, characterizing, and understanding the potential new nitrides. "This was very much a team effort," said Sun. "It definitely took everyone working together."

Before embarking on his ongoing collaboration with NREL, Sun had determined that metastable materials accounted for a significant fraction of nitride compounds, and published his findingsPDF near the end of 2016. "After that was written, it became clear this would be a good team effort to explore nitrides," Sun said. "NREL has been making metastable nitrides for many years now."

That, coupled with NREL's demonstrated ability to synthesize highly metastable nitride thin-films (described in Zakutayev's 2016 review article on this topic), inspired an article on binary nitrides that Sun, Zakutayev, and others published in 2017. The newly published research on ternary nitrides was the next logical step.

The world of ternary nitrides hasn't been thoroughly explored because the compounds--consisting of nitrogen and two metals--are difficult to synthesize. The prediction of the new ternary nitrides relied on computational materials science, using machine-learning algorithms to map previously uncharted spaces. This accelerated the process compared to the traditional trial-and-error method.

More Nitrides on the Horizon

One woman and two men stand outside on a balcony. The man on the right holds a ball-and-stick model of a molecule.

Although nitrogen is far more abundant in Earth's atmosphere than oxygen, it's considerably easier for oxides to form than nitrides. Leave a piece of iron outside, for example, and eventually it will rust, or oxidize. That's because the bond between oxygen atoms can easily dislodge. But nitrogen atoms hold tight.

"Oxides and nitrides often have a similar chemistry," said Zakutayev, who works on developing new materials for renewable energy technologies and has a proven track record in synthesizing nitrides. "But for each nitride documented, there are 14 oxides. If the chemistry is similar, there is no reason there should be many of one and few of the other. That's a very large discovery opportunity."

Before researchers could map the nitrides, however, they first needed to predict new nitride materials. Using high-throughput computational materials science, they first considered 6,000 potential nitride compounds by substituting known nitrides with new elements. After checking the stability of these possible nitrides, they predicted 203 new stable ternary nitride compounds. Until now, only 213 stable nitrides were known to exist.

The first two ternary nitrides were discovered in 1927, and the third eight years later. Since then, new nitrides have been discovered sporadically. This batch of 203 is by far the largest number of potential new nitrides identified in a single year.

"Historically, nitrides are discovered at the rate of three or four a year, experimentally speaking," said Zakutayev.

Guided by the map, Zakutayev and his team were initially able to synthesize seven new ternary nitrides in the laboratory. Several more nitrides have been synthesized since the paper was written.

Synthesis Proves Accuracy of Predictions

"So far, we're batting a thousand," said Holder, a research professor who holds a joint CU-NREL appointment and is a co-author of the new paper. "Every ternary nitride we predicted could make a stable compound."

The ability to synthesize the seven new nitrides, the authors noted in the paper, validates the predictions of the existence of the other nitrides "and highlights the valuable role of computational materials discovery in accelerating exploratory synthesis in novel chemical spaces."

The research also provides another dimension to the periodic table of elements by indicating a group of metals' propensity to form stable or metastable ternary nitrides. Calcium, for example, stood out for its ability to create a nitride. So did lithium. The scientists also were able to discount metals that won't be useful in nitride research. "Gold doesn't want to combine with nitrogen," Holder said, "and adding another metal is not going to stabilize it enough to make it happen."

Now possessed with a greater understanding of nitrides, researchers can move forward with determining their best uses. The Nobel Prize for physics in 2014 was awarded to a trio of researchers who combined several layers of gallium nitride to invent a blue LED. Coupling their blue light with efficient phosphors allowed the creation of long-lasting and energy-efficient white LED bulbs. The nitrides team sees even more applications on--and beyond--the horizon.

"Certainly, these materials have many possible new functional applications," Sun said. "Some of them are semiconductors and others might be superconductors. Many of them might have applications we haven't even dreamed of yet. There are a lot of directions for this to go."

Bottom Line: A detailed analysis of recent national data on suicide rates among young people ages 15 to 24 reports 6,241 suicides in 2017, and suicide rates at ages 15 to 19 and 20 to 24 that have increased to their highest point since 2000. This study used data from the Centers for Disease Control and Prevention to take a closer look at suicide rates in the United States among young people and to see if increases from 2000 to 2016 were continuing. Of the 6,241 suicides in 2017, 5,016 were male and 1,225 were female; the suicide rate for those 15 to 19 was 11.8 per 100,000 compared with 8 per 100,000 in 2000. For young adults 20 to 24, the suicide rate in 2017 was 17 per 100,000 compared with 12.5 per 100,000 in 2000. A limitation of the study is that causes of death in death certificates can sometimes be wrong, for example, if a suicide using opioids is mistaken for an accidental overdose. The observed increase in suicide also could reflect better reporting. Future studies should examine other possible contributing factors to the increasing suicide rate.

Plant root systems play a crucial role in ecosystems, radically impacting everything from nutrient cycling to species composition. Despite their importance, scientists are just beginning to develop the tools to understand how these complex systems are structured, how they function, and how structure and function are related. Much of the research into root systems today uses sophisticated new technologies to address basic questions and descriptions. A recent special issue of Applications in Plant Sciences contains six papers from the cutting edge of root science, exploring questions from the subcellular to the ecosystem level.

Because research into root systems is relatively new, much research is still in the realm of description. For example, Kengkanna et al. (2019) evaluate root structure in cassava, refining which variables might be agronomically important and could thus serve as a target for breeding programs. They do this using a tool called digital imaging of root traits (DIRT), a high-throughput method for scoring root phenotypes that is itself only five years old. "In areas where drought is or already has become more prominent, [DIRT] makes it feasible for breeding programs to target root traits that may be critical to achieving higher yield with limited water supply," said Dr. Gregory Pec, a postdoctoral research associate at the University of New Hampshire, and co-editor of this special issue.

Other current root system research takes aim at basic, fundamental questions, such as: are the microbes growing under a particular tree species better adapted to decompose that species' leaf litter? This idea, known as the home-field advantage hypothesis, was tested by Martini et al. (2019); the authors found that the answer might be a little more complicated, depending on fine-scale species composition, and which nutrient is under investigation.

Metzler et al. (2019) address the question: given a mixed sample of soil containing many roots, how can one figure out which roots belong to which species efficiently? The authors use fluorescent amplified fragment length polymorphisms---fluorescently marked small segments of DNA---to determine species identities of multiple roots in mixed samples simultaneously, dramatically cutting cost and time over previous Sanger sequencing methods. In the process, they provide root size profiles for 193 species, effectively doubling the existing database. Genetic tools have moved root system research forward on many fronts, aside from identifying which roots belongs to which species.

One area of particular promise for genetic research is in understanding and mapping soil microbial diversity. "The use of traditional, cultivation-based approaches to examine soil-microbial-root dynamics has proven challenging as these methods retrieve a small fraction of the total diversity. However, technological advances in the last decade have allowed for these complex and often context dependent interactions to be investigated," said Dr. Pec.

In this issue, a historical dimension is added to this genetic research into root-microbe associations, as Heberling and Burke (2019) present research to investigate and quantify arbuscular mycorrhizal fungal communities on historical herbarium specimens. This reconstruction of historical plant-microbe interactions can help us understand how climate change has impacted forest ecosystems.

Research into root systems was neglected for decades due to the difficulty of studying these delicate, complex, underground systems. Today, as improvements in technology have made this research much more feasible, interest in root systems is growing, and databases are starting to fill with important baseline data like root structure and size profiles, and microbial associations. "Our understanding of root structure-function relationships is often limited due to methodological challenges associated with roots' hidden nature in soils," said Dr. Pec. "In the 1990s, plant ecologists started looking at belowground competition and root biomass distributions, but this did not require new methodology. In the 2000s, mycorrhizae, plant-soil feedback and microbial interactions of root ecology really took off. However, prior to that, most research by mainstream plant scientists was just not focused on roots."

That is beginning to change.