News From The American Chemical Society April 22, 2009

Main Category: Biology / Biochemistry
Also Included In: Water - Air Quality / Agriculture;  Infectious Diseases / Bacteria / Viruses;  Medical Devices / Diagnostics
Article Date: 28 Apr 2009 - 6:00 PDT

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Cousin of the "ice that burns" emerges as greener new way to fight fires

Researchers in Japan are reporting development of a new type of ice that may provide a more efficient, environmentally-friendly method for putting out fires, including out-of control blazes that destroy homes and forests. Their study appears in the current issue of ACS' Industrial & Engineering Chemistry Research, a bi-weekly journal.

Toshihisa Ueda and colleagues note in the new study that firefighters have used water and carbon dioxide as fire extinguishing agents for decades. That knowledge led the scientists on a quest to see if carbon dioxide hydrates, frozen crystals made of water and carbon dioxide bonded together, may serve as promising fire-suppressing materials. Such icy chunks occur naturally in some parts of the world, including hydrates containing methane. Methane hydrates are a potential new source of natural gas, and are renowned as the "ice that burns." They burst into flame when ignited.

To test their idea, the scientists used a special reactor to produce tiny pellets of carbon dioxide hydrates in the laboratory. They compared the fire-suppressing performance of these hydrates to similar-sized pellets made of normal ice (frozen water) and dry ice (frozen carbon dioxide) after sprinkling them onto several small, carefully controlled fires. The hydrates extinguished flames faster than the other two substances, they say. The hydrates also used less water than ordinary ice and released less carbon dioxide than dry ice, they note. Grinding the pellets into smaller pieces boosted their flame-fighting efficiency, the researchers say. - MTS

"Fire Extinction Using Carbon Dioxide Hydrate"
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ie8019533

CONTACT:
Toshihisa Ueda, Ph.D.
Department of Mechanical Engineering
Keio University
Yokohama, Japan 223-8522

New biosensor for most serious form of Listeria food poisoning bacteria

Scientists in Indiana are reporting development of a new biosensor for use in a faster, more sensitive test for detecting the deadliest strain of Listeria food poisoning bacteria. That microbe causes hundreds of deaths and thousands of hospitalizations each year in the United States, particularly among people with weakened immune systems. Their study appears in the current issue of ACS' Analytical Chemistry, a semi-monthly journal.

Arun Bhunia and colleagues note in the new study that fast, highly effective tests already are available for five of the six known species of Listeria. These tests use antibodies that signal the presence of the bacteria. However, no rapid, sensitive tests are available for detecting Listeria monocytogenes, the deadliest of the species, the researchers say.

The scientists describe development of the biosensor using so-called heat shock proteins - which the body produces in response to stress - instead of the antibodies used in other tests. They showed that their new sensor was faster and more sensitive at detecting the deadly bacterium than antibody-based tests. It had a microbe capture rate up to 83 percent higher than antibody-based tests. The new biosensor will reduce the likelihood of false-positive results for Listeria monocytogenes and may lead to improved tests for detecting other types of dangerous pathogens, the researchers say. - MTS

"Targeted Capture of Pathogenic Bacteria Using a Mammalian Cell Receptor Coupled with Dielectrophoresis on a Biochip"
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ac9000833

CONTACT:
Arun K. Bhunia, Ph.D.
Professor of Food Microbiology
Department of Food Science
Purdue University
West Lafayette, Ind.47907

Presto! Fast color-changing material may lead to improved sunglasses

Researchers in Japan are reporting development of a new so-called "photochromic" material that changes color thousands of times faster than conventional materials when exposed to light. The development could lead to a wide range of new products including improved sunglasses, more powerful computers, dynamic holograms, and better medicines, the researchers say. Their report appears in the Journal of the American Chemical Society, a weekly publication.

In the new study, Jiro Abe and colleagues note that photochromic materials are most familiar as the invisible layers found in the lenses of many high-end sunglasses, which change color when exposed to sunlight. For years, researchers have explored the possibility of using these unusual materials for optical data storage in computers and as "molecular switches" for more controlled drug delivery. Conventional photochromic materials, however, tend to be relatively slow-acting (tens of seconds to hours) and unstable, which prevents their use for many advanced applications, the scientists say.

The scientists describe development of a unique photochromic material that shows instantaneous coloration upon exposure to ultraviolet light and its disappearance within tens of milliseconds when the light is turned off. The decoloration speed is thousands of times faster than conventional materials. The material is also more stable and longer-lasting, they note. In laboratory studies, the scientists showed that the new material could instantly change from colorless to blue in both solid form and in solution when they exposed the molecules to ultraviolet light, and quickly back to colorless when the light is turned off. The development opens the door to futuristic technologies "with unprecedented switching speeds and remarkable stabilities," the article notes. - MTS

"A Fast Photochromic Molecule That Colors Only under UV Light"
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ja810032t

CONTACT:
Jiro Abe, Ph.D.
Aoyama Gakuin University
Department of Chemistry
School of Science and Engineering
Sagamihara, Kanagawa, Japan

Source:
Michael Woods
American Chemical Society