Photosensitive Membrane Fabricated by Molecular Imprinting
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edge. The presence of such states results in a trapped electron potential of -0.39 V, which exceeds the reduction potential of the O2 /O2 - at pH 7 (-0.16 V), and enables the formation of OH radicals by visiblelight irradiation. The researchers, therefore, analyzed the photocatalytic activity of new materials by observing the degradation of typical pollutants in water and air by artificial and natural light. They observed complete photomineralization of the ubiquitous water pollutant 4-chlorophenol in the presence of the catalyst after 180 min of irradiation with visible light (λ = 455 nm). The researchers also confirmed high photocatalytic activity of the substances by photodegradation of 4-chlorophenol and the azo dye remazol red by illumination experiments in diffused indoor daylight. Furthermore, they found that the catalyst supported on filter paper catalyzes the oxidation of gaseous acetaldehyde, benzene, and carbon monoxide. ANDREI A. ELISEEV
Micromirrors Fabricated by the Micro-Origami Technique Characterized by Optical Actuation The development of semiconductors goes hand in hand with research into microelectromechanical systems (MEMS) devices because the latter, in a lot of cases, are built on semiconductors and consequently the progress of semiconductor research depends on the study of micro technologies. J.M. Zanardi Ocampo from ATR Laboratories in Kyoto, T. Ohnishi from Konan University in Kobe, R. Izumoto from Osaka City University in Osaka, and their colleagues addressed the formation of reliable hinges for movable parts of MEMS equipment, by means of micromirrors, and the actuation of the resulting micromirrors. As reported in the November 3, 2003, issue of Applied Physics Letters, the researchers have fabricated standing micromirrors by the microorigami technique they developed in which the hinges bend as the result of strain in a pair of lattice-mismatched epi-
Chiral Surface Produced through Electrodeposition J.A. Switzer and colleagues at the University of Missouri—Rolla have developed a process for separating or detecting chiral molecules using electrodeposited chiral surfaces, in contrast to the current process that requires a homogeneous catalyst or an enzyme solution. The electrodeposited chiral surface can then be used as this type of catalyst. As reported in the October 2, 2003 issue of Nature, the researchers immersed a thin layer of gold in a liquid containing copper and the enantiospecific chemical tartrate while applying an electric current to the system. The electricity caused copper oxide to bond to the achiral Au(001) surface. The chirality of the film was determined by the chirality of the tartrate ion in solution. The researchers used x-ray diffraction to determine the orientation of the entire film, and x-ray pole figure analysis to determine the film’s absolute configuration (see figure). Initial tests revealed that the material differentiates the enantiomeric forms of the chiral tartrate without breaking down or being permanently altered. Switzer said, “We’ve made a material
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