FOR IMMEDIATE RELEASE
ACS News Service Weekly PressPac: October 29, 2008
- Record high performance with new solar cells
- Tale of two snails reveals secrets about the biochemistry of evolution
- Tiny DNA tweezers can catch and release objects on-demand
- DNA fingerprinting method may thwart false labeling of shark meat
- Toward a safer, more effective method for preserving museum specimens
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Here is the latest American Chemical Society (ACS) News Service Weekly PressPac with news from ACS’ 36 peer-reviewed journals and Chemical & Engineering News.
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News Items in this Edition
Researchers in China and Switzerland are reporting the highest efficiency ever for a promising new genre of solar cells, which many scientists think offer the best hope for making the sun a mainstay source of energy in the future. The photovoltaic cells, called dye-sensitized solar cells or Grätzel cells, could expand the use of solar energy for homes, businesses, and other practical applications, the scientists say. Their study is scheduled for the November 13 issue of ACS’ The Journal of Physical Chemistry C, a weekly publication.
The research, conducted by Peng Wang and colleagues — who include Michael Grätzel, inventor of the first dye-sensitized solar cell — involves photovoltaic cells composed of titanium dioxide and powerful light-harvesting dyes. Grätzel cells are less expensive than standard silicon-based solar cells and can be made into flexible sheets or coatings. Although promising, Grätzel cells until now have had serious drawbacks. They have not been efficient enough at converting light into electricity. And their performance dropped after relatively short exposures to sunlight.
In the new study, researchers describe lab tests of solar cells made with a new type of ruthenium-based dye that helps boost the light-harvesting ability. The new cells showed efficiencies as high as 10 percent, a record for this type of solar cell. The new cells also showed greater stability at high temperatures than previous formulas, retaining more than 90 percent of their initial output after 1,000 hours in full sunlight. — MTS
Researchers in Spain are reporting deep new insights into how evolution changes the biochemistry of living things, helping them to adapt to new environments. Their study, based on an analysis of proteins produced by two populations of marine snails, reveals chemical differences that give one population a survival-of-the fittest edge for life in its cold, wave-exposed environment. Their report is scheduled for the November 7 issue of ACS’ Journal of Proteome Research, a monthly publication.
In the new study, Emilio RolÁn-Alvarez and colleagues note that scientists long have known that animals of the same species can have different physical characteristics enabling them to survive in different habitats. One famous example is the different beak sizes and shapes that evolved in Darwin’s finches, enabling the birds to live on different foods in different habitats on the Galapagos Islands. Until now, however, scientists knew little about the invisible biochemical changes behind such adaptations.
To help fill those gaps, the scientists studied two populations of marine snails that live only a few feet apart on the Spanish coast. One group lives on the lower shore, typically submerged in water and protected from large changes in temperature. The other group lives on the upper shore exposed to daily changes in temperature, humidity and other environmental conditions. Tests with mass spectrometry showed major differences in about 12 percent of the proteins in the snail, a subset of proteins that apparently enables the snails to survive in different environmental conditions. — MTS
Researchers in China are reporting development of a new DNA “tweezers” that are the first of their kind capable of grasping and releasing objects on-demand. The microscopic tweezers could have several potential uses, the researchers note. Those include microsurgery, drug and gene delivery for gene therapy, and in the manufacturing of nano-sized circuits for futuristic electronics. Their study is scheduled for the November 12 issue of the weekly Journal of the American Chemical Society.
Zhaoxiang Deng and colleagues note that other scientists have developed tweezers made of DNA, the double helix molecule and chemical blueprint of life. Those tweezers can open and close by responding to complementary chemical components found in DNA’s backbone. However, getting the tweezers to grasp and release objects like real tweezers has remained a bioengineering challenge until now.
The scientists describe development of a pair of DNA tweezers composed of four DNA strands — three which act as the “arms.” In laboratory studies, the scientists showed that they could grab a piece of target DNA in the arms of the tweezers and release it on-demand using a controlled series of hydrogen bonding and pH changes. The scientists used fluorescent gel imaging to confirm the effectiveness of the tweezers’ operation. — MTS
Researchers in Spain are reporting that a new DNA identification method could thwart false labeling of shark species used in various seafood products, including the expensive Chinese delicacy known as shark fin soup. Their study is scheduled for the November 26 issue of ACS’ Journal of Agricultural and Food Chemistry, a bi-weekly publication.
Maria Blanco, Ricardo Perez-Martin, and Carmen G. Sotelo note that consumption of shark meat appears to be on the rise worldwide, with some seafood companies reportedly having substituted cheaper shark species for more expensive species and incorrectly labeling their products. European Union regulations now require listing the species name on shark products to avoid fraud and to help conserve certain shark species. However, a fast, reliable method for distinguishing between different species of shark remains elusive.
The scientists describe the use of a relatively new technique called forensically informative nucleotide sequencing (FINS), in which DNA isolated from unknown biologic samples is compared to a database of DNA markers from known species. In the new study, the scientists collected DNA markers from nine different commercial seafood samples containing shark meat and compared them to known DNA markers from 23 different shark species. The scientists found that two of the nine shark products analyzed had been labeled with incorrect species names, demonstrating the effectiveness for the FINS method. — MTS
Some of the most fascinating creatures ever to inhabit the Earth can be seen today only in the form of preserved museum specimens. Researchers now are reporting progress toward a safer, more effective method of preserving these precious biological specimens in order to prolong their study and enjoyment for future generations, according to an article scheduled for the Nov. 3 issue of Chemical & Engineering News, ACS’ weekly newsmagazine.
In the article, C&EN Assistant Editor Carmen Drahl notes that the most widely-used substances for long-term museum conservation are solutions of alcohols, such as ethanol, and formalin, a dilute solution of formaldehyde. Although used for centuries as effective preservatives, these solutions have several disadvantages. For example, alcohol is highly flammable and discolors specimens, while formalin has been linked to cancer in animals and also causes discoloration.
Scientists at the Smithsonian’s National Museum of Natural History in Washington, D.C. are now experimenting with a promising new solution to help preserve its prized 24-foot long giant squid specimen. Called “Novec,” the transparent solution is a nontoxic, non-flammable hydrofluoroether originally developed by 3M Corporation for electronics industry applications. Novec works by forming a chemical envelope around already preserved specimens, much like repelling water from a car’s surface by applying a fresh coat of wax. Novec does not get cloudy over time, and unlike traditional preservatives, it protects specimens from color changes. Thus, the Smithsonian’s giant squid has become an ongoing experiment in modern preservation methods. “We’re very interested in seeing how it will all turn out,” says one researcher.
It's never too late to explore a treasure trove of news sources, background material and story ideas available from the ACS' latest National Meeting, which was held in Philadelphia from August 17-21, 2008. Reporters can view press releases, search an archive with abstracts of more than 9,000 scientific presentations and hundreds of non-technical summaries of those presentations, and access other resources at: www.eurekalert.org/acsmeet.php.
The ACS Office of Public Affairs also offers recorded video versions of its national meeting "chat room" briefings and accompanying chat transcripts by going to http://www.ustream.tv/channel/acslive. To use this site, you must first register with Ustream.tv by going to http://ustream.tv/sign-up-step-1. It's free and only takes a minute or two to sign up. To view the archived chat room sessions, proceed by clicking the "Login" button at the top right of the Ustream window and then selecting "Past Clips." Please note that Ustream requires the latest version of Adobe Flash, which can be downloaded without charge at http://www.adobe.com/products/flashplayer.
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