PRESS-NEWS.org - Press Release Distribution
FREE PRESS RELEASES DISTRIBUTION

UCI scientists measure local vibrational modes at individual crystalline faults

Breakthrough research made possible by advanced microscopic techniques

2021-01-13
(Press-News.org) Irvine, Calif., Jan. 11, 2021 - Often admired for their flawless appearance to the naked eye, crystals can have defects at the nanometer scale, and these imperfections may affect the thermal and heat transport properties of crystalline materials used in a variety of high-technology devices.

Employing newly developed electron microscopy techniques, researchers at the University of California, Irvine and other institutions have, for the first time, measured the spectra of phonons - quantum mechanical vibrations in a lattice - at individual crystalline faults, and they discovered the propagation of phonons near the flaws. The team's findings are the subject of a study published recently in Nature.

"Point defects, dislocations, stacking faults and grain boundaries are often found in crystalline materials, and these defects can have a significant impact on a substance's thermal conductivity and thermoelectric performance," said senior co-author Xiaoqing Pan, UCI's Henry Samueli Endowed Chair in Engineering, as well as a professor of materials science and engineering and physics & astronomy.

He said that there are ample theories to explain the interactions between crystal imperfections and phonons but little experimental validation due to the inability of earlier methods to view the phenomena at high enough space and momentum resolution. Pan and his collaborators approached the problem through the novel development of space- and momentum-resolved vibrational spectroscopy in a transmission electron microscope at UCI's Irvine Materials Research Institute.

With this technique, they were able to observe individual defects in cubic silicon carbide, a material with a wide range of applications in electronic devices. Pan and his colleagues were familiar with how imperfections in silicon carbide are manifested as stacking faults, and theoretical work has described the thermoelectric impacts, but now the team has produced direct experimental data to characterize phonon interactions with the individual defects.

"Our method opens up the possibility of studying the local vibrational modes at intrinsic and non-intrinsic defects in materials," said Pan, who is also director of IMRI and UCI's Center for Complex and Active Materials, funded by the National Science Foundation. "We expect it to find important applications in many different areas, ranging from the study of thermal resistance-inducing interfacial phonons to defect structures engineered to optimize a material's thermal properties."

INFORMATION:

This project, which was supported by the U.S. Department of Energy's Office of Basic Energy Sciences and the NSF, included researchers from Nion R&D in Kirkland, Washington; China's Henan University; and Cornell University.

About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 36,000 students and offers 222 degree programs. It's located in one of the world's safest and most economically vibrant communities and is Orange County's second-largest employer, contributing $5 billion annually to the local economy. For more on UCI, visit http://www.uci.edu.

Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.



ELSE PRESS RELEASES FROM THIS DATE:

UCI researchers use deep learning to identify gene regulation at single-cell level

2021-01-13
Irvine, Calif., Jan. 5, 2021 -- Scientists at the University of California, Irvine have developed a new deep-learning framework that predicts gene regulation at the single-cell level. Deep learning, a family of machine-learning methods based on artificial neural networks, has revolutionized applications such as image interpretation, natural language processing and autonomous driving. In a study published recently in Science Advances, UCI researchers describe how the technique can also be successfully used to observe gene regulation at the cellular level. Until now, that process had ...

Research reveals how teeth functioned and evolved in giant mega-sharks

Research reveals how teeth functioned and evolved in giant mega-sharks
2021-01-13
A pioneering study by University of Bristol researchers finds that the evolution of teeth in the giant prehistoric shark Megalodon and its relatives was a by-product of becoming huge, rather than an adaptation to new feeding habits. The iconic extinct Megalodon was the largest shark to ever roam the seas. Its name translates to 'big tooth', making reference to its massive teeth, which represent the most abundant fossil remains of the species. They are broad and triangular, nothing like the curved, blade-like teeth of the closest relatives of Megalodon. The ...

Recurrent GBM brain tumors with few mutations respond best to immunotherapy

2021-01-13
DURHAM, N.C. - Glioblastoma brain tumors are especially perplexing. Inevitably lethal, the tumors occasionally respond to new immunotherapies after they've grown back, enabling up to 20% of patients to live well beyond predicted survival times. What causes this effect has long been the pursuit of researchers hoping to harness immunotherapies to extend more lives. New insights from a team led by Duke's Preston Robert Tisch Brain Tumor Center provide potential answers. The team found that recurring glioblastoma tumors with very few mutations are far more vulnerable ...

Upper ocean temperatures hit record high in 2020

Upper ocean temperatures hit record high in 2020
2021-01-13
Even with the COVID-19-related small dip in global carbon emissions due to limited travel and other activities, the ocean temperatures continued a trend of breaking records in 2020. A new study, authored by 20 scientists from 13 institutes around the world, reported the highest ocean temperatures since 1955 from surface level to a depth of 2,000 meters. The report was published on January 13 in Advances in Atmospheric Sciences and concluded with a plea to the policymakers and others to consider the lasting damage warmer oceans can cause as they attempt to mitigate the ...

Ukraine genome survey adds missing pieces to human diversity puzzle

Ukraine genome survey adds missing pieces to human diversity puzzle
2021-01-13
Today, the largest study of genetic diversity in Ukraine was published in the open science journal GigaScience. The project was an international effort, bringing together researchers in Ukraine, the US and China and is the first fruits of this collaboration to set up a new Central Europe Center for Genomic Research in Ukraine. Led by researchers at Uzhhorod National University and Oakland University in the US, the work provides genetic understanding of the historic and pre-historic migration settlements in one of the key intersections of human trade and migration between the Eurasian peoples as well as the identification of genetic variants of medical interest in the Ukrainian population that differ ...

New study suggests that college campuses are COVID-19 superspreaders

New study suggests that college campuses are COVID-19 superspreaders
2021-01-13
College campuses are at risk of becoming COVID-19 superspreaders for their entire county, according to a new vast study which shows the striking danger of the first two weeks of school in particular. Looking at 30 campuses across the nation with the highest amount of reported cases, experts saw that over half of the institutions had spikes - at their peak - which were well above 1,000 coronavirus cases per 100,000 people per week within the first two weeks of class. In some colleges, one in five students had been infected with the virus by the end of the fall term. Four institutions had over 5,000 ...

Ovarian cancer cells adapt to their surroundings to aid tumor growth

2021-01-13
A detailed description of how ovarian cancer cells adapt to survive and proliferate in the peritoneal cavity has been published in Frontiers in Oncology. Researchers show that structures inside the cells change as the disease progresses from benign to malignant, helping the cells to grow in an otherwise hostile environment of low nutrients and oxygen. Understanding how these cellular adaptations are regulated could herald new targeted treatment options against the fifth-leading cause of cancer-related deaths in women. "Our study compared the structures inside cells representing different stages of ovarian cancer, including after aggregation, which enhances their survival," says Eva Schmelz, a Professor and Scientific Director at Virginia Tech University, USA, who led this research. "We found ...

Families' remote learning experience during lockdown more positive than widely believed

2021-01-13
The remote learning experience of parents who had their children at home in Spring 2020, as schools across the US closed during the United States' COVID-19 lockdown, was more positive than widely believed. That is the suggestion from a new study published in the Journal of School Choice, which looked at the experience of a nationally representative sample of 1,700 parents stretching right across America. On average only 44% of parents reported the online learning program required too much of parents, while 38% of parents said it was difficult for them to manage the online provisions. However, worryingly, most parents (63%) believed remote learning caused their child to fall behind. While the study focused ...

Disagreeing takes up a lot of brain real estate

2021-01-13
Yale researchers have devised a way to peer into the brains of two people simultaneously while are engaged in discussion. What they found will not surprise anyone who has found themselves arguing about politics or social issues. When two people agree, their brains exhibit a calm synchronicity of activity focused on sensory areas of the brain. When they disagree, however, many other regions of the brain involved in higher cognitive functions become mobilized as each individual combats the other's argument, a Yale-led research team reports Jan. 13 in the journal Frontiers of Human Neuroscience. "Our entire brain ...

Expert prognosis for the planet - we're on track for a ghastly future

2021-01-13
A loss of biodiversity and accelerating climate change in the coming decades coupled with ignorance and inaction is threatening the survival of all species, including our very own, according to the experts from institutions including Stanford University, UCLA, and Flinders University. The researchers state that world leaders need a 'cold shower' regarding the state of our environment, both to plan and act to avoid a ghastly future. Lead author Professor Corey Bradshaw of Flinders University in Australia says he and his colleagues have summarised the state of the natural world in stark form to help clarify the gravity of the human predicament. "Humanity is causing a ...

LAST 30 PRESS RELEASES:

Study provides first real-world evidence of Covid-19 contact tracing app effectiveness

Myeloid immune cells in the blood tied to severe COVID-19

Scientists developed energy saving ceramic phosphors for high power LED systems

Roadblocks to success for PhD grads could mean missed opportunities for Canada

Corona vaccination: Approach receives approval

Researchers use nanomaterials to make 2D diamond clusters at room temperature

Reef fish futures foretold

When looking at species declines, nuances and long-term data are important

Solar hydrogen: Photoanodes made of alpha-SnWO4 promise high efficiencies

Intercontinental study sheds light on the microbial life of sourdough

Biodegradable displays for sustainable electronics

Autistic kids may have a harder time recognizing healthy vs. toxic arguments

A benchmark for single-electron circuits

UOC researchers have analysed 13 apps developed for the treatment and control of neglected tropical diseases, identifying the main weaknesses and evaluating possible improvements

At three days old, newborn mice remember their moms

Fighting racial inequity by funding Black scientists

Microwaves used to deactivate coronavirus, flu, other aerosolized viruses

Prevalence, risk factors associated with self-reported psychological distress among children, adolescents during COVID-19 pandemic in China

Neonatal antibiotic use associated with reduced growth in boys

Air purifiers may do more harm than good in confined spaces with airborne viruses

Nixing bone cancer fuel supply offers new treatment approach, mouse study suggests

Iron-carrying extracellular vesicles are key to respiratory viral-bacterial co-infection

A research team from Denmark discovers new control mechanism in the innate immune system

Soil health is as environmentally important as air and water quality, say microbiologists

The longevity gene mammalian Indy (mINDY) is involved in blood pressure regulation

Children cannot ignore what they hear when detecting emotions

Nuclear physicist's voyage towards a mythical island

Holocaust Remembrance Day: COVID-19 changed how we remember

Cancer deaths attributable to cigarette smoking in 152 US metropolitan and micropolitan areas

To combat false news, correct after reading

[Press-News.org] UCI scientists measure local vibrational modes at individual crystalline faults
Breakthrough research made possible by advanced microscopic techniques