ChemWeb Newsletter

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This week: How to overcome capillary forces in microfluidic systems, Kyoto comes of age, and an explanation for the flipping health effects of estrogen. Also in this issue of The Alchemist, the spurious signature of Martian methane hints at life on the Red Planet and how quantum chemists can test nano-catalysts in silico.




If microfluidic and nanofluidic systems are to come to the fore and allow the concept of the lab-on-a-chip to mature, then their designers must address certain technical issues first. One such issue is developing effective and reproducible ways to make the tiny compartments for holding small amounts of liquids and reagents. Now, researchers at the Max Planck Institute of Colloids and Interfaces, the Max Planck Institute of Dynamics and Self-organization and the University of California in Santa Barbara have demonstrated that "open systems" fabricated using available photolithographic techniques should be possible in general but only if the geometry of the surface channels is carefully matched with their wettability. This constraint is due directly to the strong capillary forces at this scale but the study reveals how this issue might be overcome.





After years of delays, the Kyoto Protocol aimed at combating global warming due to anthropogenic greenhouse gases finally came into effect on February 16, eight years after it was first signed in 1997. However, it may be too little too late according to some scientists. Researchers at the Scripps Institution of Oceanography in La Jolla, California produced new evidence this week that ocean warming is strongly linked to human activity over the past four decades years. This, they say, puts paid to the doubters. However, eight years of wrangling between nations over the ratification of the Kyoto Protocol resulted in US opting out in 2001 and the big developing nations, Brazil, China and India, being left out of the equation.





The changing chemistry of estrogen could explain why its role apparently switches from protecting women from heart disease to increasing their risk later in life. Researchers Richard White and Scott Barman of the Medical College of Georgia found that estrogen targets nitric oxide synthase 1, one of three enzymes that produce the vasodilator, nitric oxide. However, normal aging leads to lowering of the enzyme's cofactors L-arginine and tetrahydrobiopterin so that in older women, increased estrogen does not boost enzyme activity but instead simply releases the vasoconstricting and damaging oxygen-free radical, superoxide. The research could lead to a new approach to hormone replacement therapy for menopausal women the researchers say.





NASA scientist Carol Stoker and Larry Lemke told officials that they have the strongest evidence yet of life on Mars. The presence of telltale methane signatures strongly suggest that microbial life could still exist on the red planet tucked away in watery niches among rocks and caves. Fluctuations in the methane signatures observed from the ground and by the European Space Agency's Mars Express hint at an active underground biosphere not unlike that found in Spain's Rio Tinto region where acidic hot springs harbor life despite the extreme conditions. The researchers hope to publish their results in a forthcoming issue of the journal Nature.





Jens Nørskov of the Technical University of Denmark (DTU) and specialist firm Haldor Topsøe used quantum theory to calculate the performance of a wide range of catalysts for use in everything from vehicle exhaust clean-up to the future production of hydrogen. They found they could test the properties of virtual nano-particulate catalysts in a host of physical and chemical experiments without having to resort to making the materials or carrying out physical experiments. The in silico approach to testing could cut the cost of developing new catalysts for many applications not only by allowing the chemistry to be fine-tuned before the catalyst is synthesized but also by pointing out technological dead-ends.