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

Force is the key to granular state-shifting

2013-02-15
(Press-News.org) Ever wonder why sand can both run through an hourglass like a liquid and be solid enough to support buildings? It's because granular materials – like sand or dirt – can change their behavior, or state. Researchers from North Carolina State University have found that the forces individual grains exert on one another are what most affect that transition.

Physicists have explored the changing behavior of granular materials by comparing it to what happens in thermodynamic systems. In a thermodynamic system, you can change the state of a material – like water – from a liquid to a gas by adding energy (heat) to the system. One of the most fundamental and important observations about temperature, however, is that it has the ability to equilibrate: a hot cup of tea eventually cools to match the temperature of the room.

Physicists thought they could use thermodynamics' underlying ideas to explain the changes in granular materials, but didn't know whether granular materials had properties which might equilibrate in a similar way. In other words, instead of temperature being the change agent in a granular system, it might be a property related to the amount of free space, or the forces on the particles. But no one had really tested which of the two might exhibit this property of equilibration.

NC State physicist Karen Daniels and former graduate student James Puckett devised a way to do just that. Puckett used two different types of plastic "granules" with different properties that floated atop a layer of air on a small table. Puckett and Daniels wanted to see what would bring the two types of particles into equilibrium with one another. In order to make their measurements, they used a plastic material that indicated a change in force by a change in brightness.

First, they measured compactivity, which describes the number of ways particles can arrange themselves inside a given space, or volume, by reducing the physical space around the granules, but the two types of particles failed to achieve equilibrium. When they measured the ways that the forces between the particles could rearrange, they saw the equilibrium they were looking for.

Their findings appear in Physical Review Letters.

"Physicists often have ideas that are theoretically elegant, such as the idea that there might be new temperature-like variables to be discovered, and then it's exciting to go into the lab and see how well these ideas work in practice," says Daniels. "In this case, we found it is possible to take the temperature of a granular system and find out more about what makes it change its state. The 'thermometer' for this temperature is actually the particles themselves."

### Note to editors: "Equilibrating temperaturelike variables in jammed granular subsystems"

Authors: James Puckett, Karen Daniels, North Carolina State University Published: Physical Review Letters


ELSE PRESS RELEASES FROM THIS DATE:

Chemists develop single molecule sieves to separate complex molecular mixtures

2013-02-15
Chemists at the University of Liverpool have created a new technique that could be used in industry to separate complex organic chemical mixtures. Chemical feedstocks containing benzene are used extensively in industry to create modern materials and polymers. Their use relies heavily on distillation techniques which separate complex mixtures into more simple molecules used as building blocks to develop drugs, plastics and new materials. These distillation techniques can be expensive and involve large amounts of energy for hard-to-separate mixtures. A team of researchers ...

Rutgers physicists test highly flexible organic semiconductors

2013-02-15
Organic semiconductors hold promise for making low-cost flexible electronics – conceivably video displays that bend like book pages or roll and unroll like posters, or wearable circuitry sewn into uniforms or athletic wear. Researchers have demonstrated the ability to "print" transistors made of organic crystals on flexible plastic sheets, using technology that resembles inkjet or gravure printing. However, for the technology's potential to be realized, scientists have to show that these organic semiconductors will withstand the rugged handling they invite – they will ...

Extreme winters impact fish negatively

Extreme winters impact fish negatively
2013-02-15
Wcologists from Umeå University and the Norwegian University of Science and Technology in Trondheim have studied fish communities and fish habitat and reviewed the importance of winter conditions for fish in streams and rivers in cold regions. The findings are now being published in the journal BioScience. It is well known that winter can be a stressful season for plants and animals in streams and rivers. It is reasonable to assume that more extreme weather conditions are the most taxing, but the ecological significance of this is poorly understood. The research team, ...

UC research takes a new approach to identifying 'food deserts'

2013-02-15
University of Cincinnati-led research takes a new direction in examining the availability of healthy foods for urban populations by examining the commuting patterns of its residents. This new approach to identifying so-called food deserts, now published online, will appear in the May journal of Health and Place. Neighborhoods without access to stores that provide healthy food options – such as fresh fruits and vegetables – are often labeled as food deserts. However, current methods for determining which neighborhoods have access to nutritious foods focus only on where ...

Nano-machines for 'bionic proteins'

Nano-machines for bionic proteins
2013-02-15
This press release is available in German. Physicists of the University of Vienna together with researchers from the University of Natural Resources and Life Sciences Vienna developed nano-machines which recreate principal activities of proteins. They present the first versatile and modular example of a fully artificial protein-mimetic model system, thanks to the Vienna Scientific Cluster (VSC), a high performance computing infrastructure. These "bionic proteins" could play an important role in innovating pharmaceutical research. The results have now been published in ...

Study finds possible link between diabetes and increased risk of heart attack death

2013-02-15
Having diabetes doubles a person's risk of dying after a heart attack, but the reason for the increased risk is not clear. A new University of Iowa study suggests the link may lie in the over-activation of an important heart enzyme, which leads to death of pacemaker cells in the heart, abnormal heart rhythm, and increased risk of sudden death in diabetic mice following a heart attack. "Many studies have shown that patients with diabetes are at especially high risk for dying from a myocardial infarction (heart attack). Our study provides new evidence that this excess ...

Wild plants are infected with many viruses and still thrive

2013-02-15
UNIVERSITY PARK, PA. -- Researchers have studied viruses as agents of disease in humans, domestic animals and plants, but a study of plant viruses in the wild may point to a more cooperative, benevolent role of the microbe, according to a Penn State virologist. "Most of these wild plants have viruses," said Marilyn Roossinck, professor of plant pathology and environmental microbiology and biology, who has examined more than 7,000 individual plants for viruses. "But they don't have any of the symptoms that we usually see in crop plants with viruses." Most of the viruses ...

Technique that removes additional toxins prolongs dialysis patients' lives

2013-02-15
Highlights A technique that removes additional toxins during dialysis decreased kidney failure patients' risk of dying from any cause by 30% over three years. The technique also reduced patients' risk of dying from heart-related causes or infections. 15% to 25% of dialysis patients die annually. Washington, DC (February 14, 2013) — A technique that removes additional toxins during dialysis may prolong kidney failure patients' lives, according to a clinical trial appearing in an upcoming issue of the Journal of the American Society Nephrology (JASN). In light of ...

Accelerated protons confirm origin of cosmic rays

2013-02-15
We are constantly being bombarded by speedy, energetic, and yet unassuming, particles called cosmic rays. These charged particles (mostly protons), continuously assail the Earth from outer space. There is general consensus among scientists that supernova remnants (the leftovers of a supernova explosion) are the sources of cosmic rays, but the final proof has been elusive since cosmic rays are deflected on their way from the source to Earth. A new study offers conclusive evidence that cosmic ray protons within our galaxy are accelerated in the shock waves produced by ...

Fish become bolder and more gluttonous from drug residue

Fish become bolder and more gluttonous from drug residue
2013-02-15
Anxiety-moderating drugs that reach waterways via wastewater create fearless and asocial fish that eat more quickly than normal. These behavioral changes can have serious ecological consequences. This is shown by Umeå University researchers in the prestigious journal Science. Many drugs leave our bodies unaffected, and residues from them are therefore found in wastewater. Low concentrations of drugs are often found downstream from sewage treatment plants. Today we test how dangerous drugs are to humans, but our knowledge of the environmental impacts of drugs is limited. ...

LAST 30 PRESS RELEASES:

Thirty-year mystery of dissonance in the “ringing” of black holes explained

Less intensive works best for agricultural soil

Arctic rivers project receives “national champion” designation from frontiers foundation

Computational biology paves the way for new ALS tests

Study offers new hope for babies born with opioid withdrawal syndrome

UT, Volkswagen Group of America celebrate research partnership

New Medicare program could dramatically improve affordability for cancer drugs – if patients enroll

Are ‘zombie’ skin cells harmful or helpful? The answer may be in their shapes

University of Cincinnati Cancer Center presents research at AACR 2025

Head and neck, breast, lung and survivorship studies headline Dana-Farber research at AACR Annual Meeting 2025

AACR: Researchers share promising results from MD Anderson clinical trials

New research explains why our waistlines expand in middle age

Advancements in muon detection: Taishan Antineutrino Observatory's innovative top veto tracker

Chips off the old block

Microvascular decompression combined with nerve combing for atypical trigeminal neuralgia

Cutting the complexity from digital carpentry

Lung immune cell type “quietly” controls inflammation in COVID-19

Fiscal impact of expanded Medicare coverage for GLP-1 receptor agonists to treat obesity

State and sociodemographic trends in US cigarette smoking with future projections

Young adults drive historic decline in smoking

NFCR congratulates Dr. Robert C. Bast, Jr. on receiving the AACR-Daniel D. Von Hoff Award for Outstanding Contributions to Education and Training in Cancer Research

Chimpanzee stem cells offer new insights into early embryonic development

This injected protein-like polymer helps tissues heal after a heart attack

FlexTech inaugural issue launches, pioneering interdisciplinary innovation in flexible technology

In Down syndrome mice, 40Hz light and sound improve cognition, neurogenesis, connectivity

Methyl eugenol: potential to inhibit oxidative stress, address related diseases, and its toxicological effects

A vascularized multilayer chip reveals shear stress-induced angiogenesis in diverse fluid conditions

AI helps unravel a cause of Alzheimer's disease and identify a therapeutic candidate

Coalition of Autism Scientists critiques US Department of Health and Human Services Autism Research Initiative

Structure dictates effectiveness, safety in nanomedicine

[Press-News.org] Force is the key to granular state-shifting