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The winner this issue is the RSC's Project Prospect team, which received the 2007 ALPSP/Charlesworth Award for Publishing Innovation. In chemistry news, two smelly discoveries caught the nose of The Alchemist. The first points the way to a clearer understanding of how we smell, while the second explains the biochemistry of geosmin, the earthy smell of freshly turned soil and the particular bouquet after rain showers. We learn from GATech scientists how a sensor array can weigh up atmospheric or aqueous pollutants and why stirring a dendrimer solution could explain the origins of life. Finally, this week, researchers in California have taken the first steps towards building a gamma-ray laser using a quasi-molecule based on positronium.




Knowing the molecular structure of a substance can help predict whether we will find its smell heavenly or malodorous, according to new research from scientists at the Weizmann Institute of Science and the University of California at Berkeley. Neurobiologist Noam Sobel of the Weizmann and colleagues suggest that their findings represent a first step in understanding the physical laws that underlie our perception of smell. The team analyzed a database of 160 different odors ranked by perfume and smell experts according to a set of 146 characteristics, including sweet, smoky, musty, etc. The team obtained a chart of pleasantness rating of the odors, ranging from sweet and floral to rancid and sickening. They could then correlate odor rank with molecular structure and predict with some flexibility whether a particular molecule will smell good or bad.





Geosmin is the smell of freshly turned earth. It is a bicyclic alcohol but until David Cane and his colleagues at Brown University figured it out, no one knew how nature makes this earthy molecule. "One nice thing about geosmin is that essentially everyone has smelled it, even if they did not know what it was or where it comes from," says Cane. He and graduate students Jiaoyang Jiang and Xiaofei have now used gas chromatography-mass spectrometry to track the biosynthesis of geosmin by a bifunctional enzyme from the soil microbe Streptomyces coelicolor. Until now, such a two-part enzymatic process was not known in the biosynthesis of this type of terpene.





A tiny silicon disk can measure pollutants present in aqueous or gaseous environments, according to Oliver Brand and colleagues at Georgia Institute of Technology. One the disk is a cantilever microbalance that measures the mass of pollutant molecules. "When pollutant chemicals get adsorbed to the surface of the sensor, a frequency change of the vibrating microbalance provides a measure of the associated mass change," explains Brand. Such cantilever microbalances are not new. But, the team has now overcome the issue of how to dampen the cantilever's vibrations without loss of sensitivity, by designing a sensor array on to a silicon disk rather than using the conventional approach.





Nanofibers of a zinc porphyrin dendrimer become aligned in a stirred liquid. Switching the direction of stirring reverses the optical activity of the solution. Takuzo Aida and colleagues at the University of Tokyo, Japan, suggest that this phenomenon may have a factor in the breaking of nature's symmetry in probiotic systems. The highly branched zinc-containing molecules aggregate in solution to form long nanofibers, the researchers explain. Left unstirred, the solution optically inactive, stirred clockwise induces optical activity in one direction and stirred counterclockwise switches the direction of the rotation of polarized light shining through the liquid. This phenomenon does not stem, as first thought, from the twisting of individual nanofibers. It is evidently caused by a special macroscopic spatial arrangement of the fibers within the sample cuvette.





Molecular positronium was a theoretical quasi-compound, imagined as forming when a pair of electrons and a pair of their antimatter counterparts hook up. Now, David Cassidy and Allen Mills of the University of California Riverside have synthesized this unique material, fleetingly, in the laboratory. The research points the way to ways to generate coherent gamma radiation - a gamma laser. The discovery might one day allow us to harness nuclear fusion for power generation. The researchers made the positronium molecules by firing intense bursts of positrons into a thin film of porous silica. Cassidy and Mills plan to work next on using a more intense positron source to generate a "Bose-Einstein condensate" of positronium -- a collection of positronium atoms that are in the same quantum state





The UK's Royal Society of Chemistry has won the 2007 ALPSP/Charlesworth Award for Publishing Innovation for its semantic chemical web endeavor Project Prospect. The judges described Prospect as a "clear winner" for its efforts to incorporate useful chemical meta data into online chemistry journal articles in a "delightfully simple" manner. The benefits of Project Prospect to authors and readers are immediately obvious, the judges said. Prospect was created by RSC staff together with academic partners. The judging panel considered the originality and innovative qualities of each of the fifteen entries, together with their utility and benefit to their community and long term development prospects.