AIP Physics News Highlights; September 26, 2011

Newswise — Physics News Highlights of the American Institute of Physics (AIP) contains summaries of interesting research from the AIP journals, notices of upcoming meetings, and other information from the AIP Member Societies. Copies of papers are available to journalists upon request.

TOPICS IN THIS ISSUE:

1. Sneaking up on the glassy transition of water: Researchers claim to have settled a long-standing debate over the exact temperature at which water transforms into an exotic glass-like substance believed to be present in comets and other icy objects in the outer solar system, as well as in the coldest regions of the Earth’s atmosphere.

2. E-textiles get fashion upgrade with memory-storing fiber: In the future when you upgrade your computer you may also be upgrading your wardrobe as researchers create novel new textiles that pull double-duty as fabrics and electronics.

3. Scientists model the pathways of pain-blocking meds: Although local anesthetics are commonly used, in many cases scientists still don’t understand the finer points of how the drugs act on cell membranes. A new computer model may help by showing how readily cell membranes made up of different compounds absorb anesthetics. _______________________________________________________

1. Sneaking up on the glassy transition of water

Rapid cooling of ordinary water or compression of ordinary ice: either of these can transform normal H2O into an exotic substance that resembles glass in its transparency, brittleness, hardness, and luster. Unlike everyday ice, which has a highly organized crystalline structure, this glass-like material’s molecules are arranged in a random, disorganized way. Scientists have studied glassy water for decades, but the exact temperature at which water acquires glass-like properties has been the subject of heated debate for years, due to the difficulty of manipulating pure glassy water in laboratories. Now, in a paper published in the AIP’s Journal of Chemical Physics, physicists from the University of Pisa and the Consiglio Nazionale delle Ricerche at the Institute for Chemical-Physical Processes (CNR-IPCF) in Pisa, Italy, claim to have put an end to the controversy. Unlike previous attempts in which scientists tried to measure the transition temperature directly, the CNR team “snuck up” on the answer by inferring the temperature from a thorough study of the dynamics of water. They examined water’s behavior in bulk and at the nano-scale, at high temperatures and low, combining their own experimental results with 15 decades’ worth of research by colleagues. They also measured the glass transition temperature and the molecular behavior of water that had been doped with other materials, and used this information to set lower and upper boundaries on the transition temperature for pure water. Taken together, their evidence points to a magic number of approximately 136 Kelvin (-137 Celsius). The authors say their work supports traditional views of this phenomenon and refutes recent claims that the transition is above 160 Kelvin (-113 Celsius). The research could find uses in technology associated with food science and the cryopreservation of biological materials, as well as in the study of water in comets and on the surface of planets.

Article: “Resolving the controversy on the glass transition temperature of water?” is published in the Journal of Chemical Physics.

Authors: Simone Capaccioli (1, 2) and K. L. Ngai (1, 3).(1) CNR-IPCF, Dipartimento di Fisica, Pisa, Italy(2) Dipartimento di Fisica, Università di Pisa, Pisa, Italy(3) State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, China

2. E-textiles get fashion upgrade with memory-storing fiber

The integration of electronics into textiles is a burgeoning field of research that may soon enable smart fabrics and wearable electronics. Bringing this technology one step closer to fruition, Jin-Woo Han and Meyya Meyyappan at the Center for Nanotechnology at NASA Ames Research Center in Moffett Field, Calif., have developed a new flexible memory fabric woven together from interlocking strands of copper and copper-oxide wires. At each juncture, or stitch along the fabric, a nanoscale dab of platinum is placed between the fibers. This “sandwich structure” at each crossing forms a resistive memory circuit. Resistive memory has received much attention due to the simplicity of its design. As described in the AIP’s journal AIP Advances, the copper-oxide fibers serve as the storage medium because they are able to change from an insulator to a conductor simply by applying a voltage. The copper wires and the platinum layers serve as the bottom and top electrodes, respectively. This design easily lends itself to textiles because it naturally forms a crossbar memory structure where the fibers intersect. The researchers developed a reversible, rewritable memory system that was able to retain information for more than 100 days. In this proof-of-concept design, the copper wires were one millimeter thick, though smaller diameter wire would allow for an increase in memory density and a reduction in weight. In practical applications, e-textiles would need to integrate a battery or power generator, sensors, and a computational element, as well as a memory structure. Taken together, an e-textile could potentially detect biomarkers for various diseases, monitor vital signs of the elderly or individuals in hostile environments, and then transmit that information to doctors. Article: “Copper oxide resistive switching memory for e-textile” is published in AIP Advances. Authors: Jin-Woo Han (1) and Meyya Meyyappan (1). (1) NASA Ames Research Center, Moffett Field, Calif.

3. Scientists model the pathways of pain-blocking meds

Benzocaine, a commonly used local anesthetic, may more easily wiggle into a cell’s membrane when the membrane is made up of compounds that carry a negative charge, a new study shows. The finding could help scientists piece together a more complete understanding of the molecular-level mechanisms behind pain-blocking medicines, possibly leading to their safer and more effective use. Most scientists believe that local anesthetics prevent pain signals from propagating to the central nervous system by blocking nerve cells’ sodium channels, but exactly how the medicines accomplish this feat remains vague. Since the solubility of anesthetics in the cell membrane can affect the medicine’s potency, some scientists have hypothesized that certain anesthetics may block the action of sodium channels indirectly, by entering the cell membrane and jostling the channels into a new shape that prevents ion flow. With the aim of further investigating such complex processes, scientists from the Universidad Politecnica de Cartagena in Spain and the Universidad Nacional de San Luis in Argentina have created a computer model that calculates the probability of molecules of benzocaine entering a cell’s membrane, based on the composition of the membrane. As reported in the AIP’s Journal of Chemical Physics, the model predicts that membranes made of a large percentage of DPPS, a negatively charged phospholipid component of cells, present less of a barrier to benzocaine molecules than membranes made mostly of DPPC, a neutral phospholipid. DPPS is normally found as one of the main components of cell membranes in the central nervous system, as well as a component of the inner side of membranes in other humans cells.

Article: “Thermodynamic study of benzocaine insertion into different lipid bilayers” is accepted for publication in the Journal of Chemical Physics.

Authors: J.J. Lopez Cascales (1), S.D. Oliveira Costa (1), and R.D. Porasso (2).(1) Grupo de Bioinformatica y Macromoleculas (BIOMAC), Universidad Politecnica de Cartagena, Spain(2) Instituto de Matematica Aplicada San Luis (IMASL), Departamento de Fisica, Universidad Nacional de San Luis, Argentina_________________________________________________________Upcoming Conferences of Interest

OSA Annual Meeting and Exhibit: The Frontiers in Optics meeting will be held October 16 - 20, 2011, in San Jose, Calif.http://www.frontiersinoptics.com/

AVS Symposium: The AVS 58th International Symposium and Exhibition will be held October 30 - November 4, 2011, at the Nashville Convention Center, in Nashville, Tenn.http://www2.avs.org/symposium/AVS58/pages/greetings.html

ASA Meeting: The 162nd meeting of the Acoustical Society of America will be held October 31 - November 4, 2011, in San Diego, Calif.http://www.acousticalsociety.org

APS/DFD Meeting: The American Physical Society/Division of Fluid Dynamics meeting will be held November 20 - 22, 2011, in Baltimore, Md.http://www.aps.org/units/dfd/meetings/meeting.cfm?name=DFD11

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