ACS News Service Weekly PressPac: March 21, 2007

• Chemistry Glossary
• Science Elements: ACS Audio Clips
• Earth Day, April 22
• ACS Chemical Biology

• ACS National Meeting, March 25-29, Chicago
• Special Event: Chicago News Media Tour/Briefing/Reception
• On the Horizon: ACS Regional Meeting, May 16-19, Philadelphia

Sustainability of energy, food and water is the featured theme of the 233rd national meeting. In a program organized by ACS President Catherine T. (“Katie”) Hunt, representatives from academia, government and industry will discuss a wide range of topics within this theme, including alternative energy sources, genetically-engineered crops and new water purification processes. To view abstracts and nontechnical summaries of the papers listed, please visit the Summaries: Sustainability page. For a Tip Sheet showcasing key sustainability topics and embargo times, visit Sustainability Summary on EurekAlert!. To see ACS President Katie Hunt’s unembargoed comments on sustainability and details of the program, visit the ACS President page.

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Researchers in Japan have developed molecular-scale “scissors” that open and close in response to light. The tiny scissors are the first example of a molecular machine capable of mechanically manipulating molecules by using light, according to Takuzo Aida and colleagues.

Just three nanometers long, the scissors are small enough (83 million, lined up end to end, would make one inch) to deliver drugs into cells or manipulate genes and other biological molecules. Chemists and biochemists may also use the scissors to precisely control the activity of proteins. Scientists have long sought ways to develop molecular-scale tools that operate in response to specific stimuli, such as sound or light. Biologists are enthusiastic about such techniques as a simple way to manipulate genes.

The new scissors-like molecular machine uses a photo-responsive chemical group that extends or folds in response to light of different wavelengths. Just like real scissors, the molecular tool consists of a pivot, blades and handles.

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Ladybugs may look cute and seem like totally beneficial insects, but they also have a dark side. These polka-dotted insects have become a nuisance by invading homes and crops, including some vineyards. To make matters worse, the bugs produce a foul-smelling liquid that, besides irritating homeowners, can be inadvertently processed along with grapes and taint the aroma and flavor of wine.

Jacek Koziel and colleagues in Iowa now report identification of several compounds involved in ladybug’s noxious odor, a finding that could lead to new strategies to detect and eliminate the offensive compounds, potentially leading to better tasting wine.

A growing number of winemakers say that their wines have an abnormal aroma and flavor, known as “ladybug taint,” that resembles the bug’s characteristic odor. Winemakers report that there are more ladybugs in vineyards and on the grapes during harvest. Experts believe that the bugs accidentally become mixed into the juice during processing and fermentation, resulting in inferior wine.

The researchers used instrumentation and a panel of human “sniffers” to characterize and identify the odors emitted by live ladybugs. They detected 28 different odors, including four compounds that were most responsible for the characteristic ladybug odor.

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A pioneering “biofuel cell” that produces electricity from ordinary air spiked with small amounts of hydrogen offers significant potential as an inexpensive and renewable alternative to the costly platinum-based fuel cells that have dominated discussion about the “hydrogen economy” of the future, British scientists are reporting.

Fraser Armstrong and colleagues cite the new device’s advantages over conventional fuel cells, which convert chemical energy in a fuel into electricity without combustion. Platinum is the most commonly used catalyst in conventional (proton exchange membrane) fuel cells, for instance, making the devices an expensive alternative energy source with sharply limited uses. Platinum catalysts also are easily poisoned or inactivated.

The new cell consists of enzyme-coated electrodes placed inside a container of ordinary air with 3 percent added hydrogen. That is just below the 4 percent danger level at which hydrogen becomes an explosion hazard. The research established for the first time that it is possible to generate electricity from such low levels of hydrogen in air, Armstrong said. Prototype versions of the cell produced enough electricity to power a wristwatch. Armstrong foresees advanced versions of the device energizing other low-power electronic devices.

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High concentrations of nitrogen dioxide gas — inhaled for even very brief periods following fires, explosions of military munitions or detonations of terrorist devices — could cause serious lung damage, scientists are reporting.

Dr. Zengfa Gu and colleagues reached that conclusion based on experiments with laboratory rats that were exposed to the toxic gas. Gu explained that previous research showed that chronic exposure to low and moderate levels of nitrogen dioxide could damage the lungs. However, there was no clear information on the health risks of brief, high-level exposures lasting only a few minutes.

Gu said that the research represents the first real-time measurements of breathing changes due to the inhalation of nitrogen dioxide gas. No other laboratories have conducted the same research due to technical challenges, which involved designing a special exposure chamber and computer software to make accurate measurements on living animals.

Nitrogen dioxide is a brownish gas with a sharp, biting odor most familiar as an air pollutant. It also forms in fires and explosions. In their experiments, scientists exposed laboratory rats to varying concentrations of nitrogen dioxide for 5 minutes. They monitored effects of nitrogen dioxide during the exposure and examined the lungs afterward for signs of damage.

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New discoveries offer promise for developing drugs that improve on the therapeutic profile of niacin, the inexpensive, time-tested B-vitamin that boosts levels of HDL cholesterol — the “good” cholesterol with the potential to protect people against heart attacks and stroke, scientists reported today.

Graeme Semple and colleagues described new insights into developing drugs that raise HDL via the same mechanism as niacin. In the high doses prescribed by a physician, niacin can increase HDL and reduce levels of artery-clogging triglycerides.

Doctors have long recognized niacin’s ability to reduce the risk of heart attacks and strokes. However, they have not prescribed niacin as widely as newer and more costly medications because of side effects such as skin flushing and itching. “Since currently marketed cholesterol drugs have a more modest HDL-raising activity than niacin, better tolerated HDL-targeted therapies with improved efficacy could provide additional clinical benefits to patients and potentially reduce the risk of heart attack and stroke,” Semple explained.

Semple described research toward that goal, including Arena’s discovery of a niacin receptor termed GPR109a. Semple said data from the joint Arena-Merck research program reinforces the possibility of identifying a compound that activates the niacin receptor without causing flushing, thereby separating the beneficial effects on fatty acids from the flushing side effect.

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Chemists in Seattle are developing ‘smart’ sunglasses that will allow the wearer to instantly change the color of their lenses to virtually any hue by tuning a tiny electronic knob in the frame, report Chunye Xu and colleagues.

“Through polymer chemistry, we’ve developed lenses that aren’t like anything else on the market. This could be the fashion statement of the future,” they said. The lenses of the ‘smart’ sunglasses feature a unique type of electrochromic polymer that has the ability to change levels of darkness and color in the presence of an electric current. Researchers have been developing electrochromic polymers for decades, but Xu’s lab is one of just a few using the technology to develop improved eyewear.

Xu developed a prototype of the eyewear that demonstrates the feasibility of these color-changing sunglasses. Powered by a tiny battery, the prototype shades resemble a pair of laboratory goggles with a button attached to the frame. Turning the button activates the battery and dials up the desired color, the researcher says. Ultimately, the sunglasses can be manufactured to resemble the size and shape of regular sunglasses and should cost about the same, Xu said.

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A new bright spot in heart disease research may soon allow physicians to peer directly into patients' blood vessels and find dangerous cholesterol-filled plaques before they rupture and cause a heart attack.

Scientists in New York under the direction of Edward A. Fisher and Zahi A. Fayad report development of a synthetic molecule that delivers an imaging enhancer to cholesterol-filled cells embedded in the arterial walls. In animal tests, the enhancer improved cholesterol detection by 79 percent. The new technique would allow physicians to diagnose unstable plaques before they rupture, and save lives by identifying the highest risk patients, says Fayad.

When used with magnetic resonance imaging (MRI), the plaques appear bright, allowing physicians to measure inflammation in artery walls and assess overall cholesterol buildup. The technique also could be used to follow a patient’s response to therapy.

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