ChemWeb Newsletter

Not a subscriber? Join now.November 11, 2004

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A microbial fuel cell that can generate electricity from raw sewage could solve two problems - how to sanitize waste water and how to generate electricity, in this week's Alchemist, while a new type of solar cell that can both generate and store electricity even on cloudy days. Also in this issue, how spinning on molecular rotors reveal another incremental step towards sub-microscopic machines, the negative impact of a particular class of PCBs on health, and finally, the 2000-year old cosmetic gets a face lift.




A pot of 2000-year old white cream unearthed during an archeological dig in London had scientists turning pale as to what it might be. But, now chemists have analyzed the cream and replicated it in the laboratory. They showed that the cream dating from around 150 AD was simply a high-class cosmetic used by the Roman aristocracy as the equivalent of a modern foundation cream to change the tone of the skin. It is rare to find preserved organic material in a closed container, explains team leader Richard Evershed of Bristol University. He adds that his team could characterize and quantify the diverse chemical components allowing them to reproduce the cream.





US researchers have developed a new technology that can turn raw sewage and other organic waste into raw power. Bruce Logan and colleagues at Pennsylvania State University built a microbial fuel cell that generates electricity by cleaning up wastewater. The device could offer developing countries a way to bring sanitation to remote areas and provide much-needed cheap energy. Logan's microbial fuel cell could treat waste from animal farms and food processing plants and might even find use on manned space missions. "The application to wastewater treatment is an excellent example of looking at wastes as a resource while they are being treated," David Bagley of the University of Toronto told us.





Japanese researchers have developed a novel solar cell that produces electricity from sunlight as normal but can also store this energy without the need for a battery. The new "photocapacitor" was designed by Tsutomu Miyasaka and Takurou Murakami at Toin University in Yokohama. It could revolutionize portable electronic devices, such as mobile phones and other hand-held devices, allowing users to charge up the device even on cloudy days. The photocapacitor uses a unique combination of materials. A light-absorbing photoelectrode made of titanium dioxide is kept separate from a platinum-coated glass counterelectrode by a resin film. Additionally, both electrodes include a porous carbon layer filled with electrolyte. The titanium dioxide generates the charge which is then stored by the electrolyte on the large surface area of the porous carbon.





Molecules that can act as rotors could be the key to making sub-microscopic machines, according to nanotechnologists. Now, John Gladysz and colleagues at the Friedrich Alexander University of Erlangen-Nurenberg have developed a new type of molecular rotor that resembles a toy gyroscope. The researchers used a relatively simple synthetic technique to build their rotor constructing a fixed fastening unit and a rotating component. The rotating axis spins within a fixed housing consisting of three circular spokes. The rotor could be set spinning by an electric field mimicking the almost frictionless spin of a gyroscope.





Researchers have linked exposure to organochlorine compounds to an increased risk of developing colorectal cancer. A French-Spanish study analysed data on 132 cases and 76 controls that higher plasma concentrations of mono-ortho polychlorinated biphenyls (PCBs) correlated with an elevated risk of colorectal cancer. The research team suggests that the toxic action of these particular PCBs is linked specifically to the genetic mutations seen in the study and conclude that this implies a causal link between this type of PCB and the disease.