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The Alchemist this week learns of a golden opportunity to make a fundamental industrial feedstock, ethylene, from natural gas, rather than oil. In microfluidics, a droplet of acid finds its way out of a maze, while an accidental mineral could become the material of choice for magnetic tunnel junctions. In the zone between chemistry and physics, German researchers have discovered a new way to produce free electrons, which might help explain biological radiation damage, and in health PFOA emerges as a risk factor for thyroid problems. Finally, more than half a million small molecules have found a home in Cambridge, UK thanks to a grant from the Wellcome Trust.

Bartosz Grzybowski and colleagues at Northwestern University have shown that an acidic droplet can successfully navigate a complex maze. The droplet of 2-hexyldecanoic acid in either dichloromethane or mineral oil travels through a maze with a pH gradient. The pH is high at the maze entrance and low at its exit and the droplet moves from high to low pH along the shortest path through the maze. The discovery might be used as a pumping method for microelectromechanical systems (MEMS) or for powering lab-on-a-chip and other devices.

The mineral kotoite, a magnesium boron oxide, could be the ideal insulator for memory storage devices known as magnetic tunnel junctions, according Derek Stewart, a computational research associate at Cornell University's NanoScale Science and Technology Facility and colleagues. Magnetic tunnel junctions comprise a sandwich of two magnets, typically iron-based, with an oxide layer in between just nanometers thick. They are used in non-volatile memory for computers, cell phones and magnetic field sensors. The team was studying magnesium oxide insulators for these devices when they discovered that boron "contamination" led to better spin filtering and so more effective devices.

Chemists have puzzled over the origin of slow-moving free electrons that may underpin radiation damage to biological systems, for many years. Now, researchers at the Max Planck Institute of Plasma Physics (IPP) in Garching and Greifswald and Fritz Haber Institute in Berlin, Germany, have at last discovered a new way in which high-energy radiation in water can release slow electrons. When ionizing radiation impinges on matter, large quantities of slow electrons are released. It was previously assumed that these electrons are ejected by the high-energy radiation from the electron sheath of the particle hit, a water molecule, for instance. X-ray studies have now shown that two adjacent water molecules can also work together to boost the yield of slow electrons.

A new study has, for the first time, linked human exposure to perfluorooctanoic acid (PFOA) with thyroid disease. PFOA is used in industrial and consumer goods, including non-stick cookware and stain- and water-resistant coatings for carpets and fabrics. Writing in the journal Environmental Health Perspectives, Tamara Galloway, of the University of Exeter, U.K., and colleagues report that people with higher concentrations of PFOA in their blood were more likely to report a history of thyroid disease. The study was based on data from the U.S. Centers for Disease Control and Prevention's nationally representative National Health and Nutrition Examination Survey (NHANES).

A new database of information on the properties and activities of drugs and drug-like small molecules and their targets, launched in January 2010 with data on more than 520,000 compounds. The database is now hosted by the European Molecular Biology Laboratory's European Bioinformatics Institute (EMBL-EBI) having been transferred from biotech firm Galapagos NV in July 2008 through a GBP4.7 million (about $7.6m) Strategic Award from the Wellcome Trust. ChEMBLdb is unique in focusing on drug discovery and because of its size; 520,000 small molecules and 2.4 million records of their effects on biological systems.

Ethene (ethylene) is usually produced as a chemical feedstock for the industry by catalytic cracking of fossil fuel fractions. Now, Thorsten Bernhardt at the University of Ulm, Germany and Uzi Landman at the Georgia Institute of Technology, Atlanta, USA, have found a way to convert methane (natural gas) into ethylene at low pressures and temperatures using free gold dimers to catalyze the reaction. Both the activation of the carbon-hydrogen bonds in methane and the subsequent splitting off of the ethylene molecule require the cooperative actions of several atoms bound to the gold dimer, the team explains. "Our insights are not only of fundamental interest, but may also be of practical use," they add.