Ultraviolet-Cured Polymer Micro-Optical Elements

A new fabrication method for polymer micro-optical elements is described which uses the contracting effect of photopolymers during the process of polymerization. Convex and concave microlens arrays and phase gratings were formed by irradiating a ultraviolet (UV)-curable monomer with incoherent UV light through an appropriate metallic mask. The morphological and optical characterization of the fabricated elements reveals that the surface profile of the elements depends on the pattern and aperture size of the mask employed.     

Organotin antifouling paints and their alternatives

Tributyltin and triphenyltin compounds have excellent biocidal properties and almost all vessels in the world have used these paints since early in the 1960s. Contrary to expectation, as shown by experimental data at the beginning of organotin chemistry, triorganotins are exceptionally stable in the sediment or in dark places in the deep sea. Since triorganotins do not decompose rapidly in seawater, many incidences of deformities in some shellfish have been linked to their presence, even when present at extremely low concentrations. Alternative tin‐free antifoulants containing other biocides, such as copper compounds and organic compounds, have been developed and used since the late 1980s. Some nations have already banned the use of organotin antifouling compounds for small vessels, and in 2001 the International Maritime Organization decided to ban completely the use of the organotin compounds from the year 2003. Therefore, it is necessary to find economically and environmentally better biocidal substances as soon as possible. Moreover, the development of antifoulants containing environmentally safe natural products, fouling release coatings, electroconductive coatings, etc. have long been anticipated from the new point of conservation of the world marine environment. Copyright © 2003 John Wiley & Sons, Ltd.     

Application of a pentafluorobenzyl bromide derivatization method in gas chromatography/mass spectrometry of trace levels of halogenated phenols in air, water and sediment samples.

An analytical method using pentafluorobenzyl bromide (PFBB) derivatization and gas chromatography/mass spectrometry (GC/MS) has been applied to identify and quantify chloro-, bromo- and dichlorophenols in air, water and sediment samples. Phenols in air sample were collected with a PS-2 Sep-PAK cartridge, and eluted with 2-propanol. For water and sediment samples, liquid-liquid extraction with dichloromethane was carried out, and the solvent was exchanged to 2-propanol. The phenols in the solution reacted with PFBB to form the corresponding pentafluorobenzyl esters. After extracting the derivatives into hexane, the determination was carried out by GC/MS with selected-ion monitoring. The detection limits of phenols in air, water and sediment were 0.0033 - 0.0073 microg/m3, 0.0066 - 0.0147 microg/L and 0.33 - 0.73 microg/kg, respectively. More than 90% recoveries of the halogenated phenols were obtained from real environmental samples spiked by the halogenated phenols. The three isomers of mono-chlorophenols were detected in sediment samples in the range of 5.2 - 9.2 microg/kg in wet weight basis.     

Dynamic stability of silacarbonyl ylide

The structure of silacarbonyl ylide in the singlet gound state is obtained by ab initio quantum chemical calculations. This proves the recent experimental observation of silacarbonyl ylide by the photolysis of oxasilitane [W. Ando, K. Hagiwara, and A. Sekiguchi, Organometallics 6, 2270 (1987)]. The dynamic stability of the silacarbonyl ylide is studied by the TCSCF /3-21G ^(*) method. The second-order Jahn-Teller effect is examined in connection with the active role of frontier orbitals. Configuration analysis is used to clarify characteristic electronic structure of the silylene-carbonyl interaction.     

Annealing behavior of spin density in UHV evaporated amorphous silicon

The ESR of amorphous silicon films evaporated in UHV has been measured at room temperature. Up to 900°C the annealing behavior of the spin density in the amorphous silicon films is quite different from that of films deposited in conventional HV.