The negative ion mass spectra of mixtures of sulphur and organic compounds. II—the formation of [C5H5 + Sn]− from the mixture of sulphur and ferrocene

The negative ion mass spectra of ferrocene and of a mixture of ferrocene with sulphur were studied. In the spectrum of the mixture, characteristic peaks of [C₅H₅ + S_n]^? (n = 1, 2, 3 etc.) were observed. The structures of these ions are discussed.     

The 13C NMR titration shifts of sulphonic acids

Carbon-13 chemical shifts of a number of alkyl and aromatic sulphonic acids in sulphuric acids in sulphuric acid and strongly basic deuterium oxide have been compared. The titration shifts are relatively small for carbons near the sulphonyl group, but are comparable with those of other organic acids or bases for carbons remote from the deprotonation sites.     

Radiation-induced cis–trans isomerization of polyisoprenes and temperature dependence of the equilibria

The cis-trans interconversion of polyisoprenes in solutions induced by γ-radiation in the presence of a sensitizer, which is any one of organic bromides or n-butyl mercaptan, was studied by using hevea and gutta percha as starting substances. The percentage cis remaining or converted after irradiation were determined by the infrared absorption. The equilibrium constants for the interconversion at 22, 60, and 100°C. were found to be 3.00, 5.25, and 7.33, respectively. The first-order rate constants for cis → trans and trans → cis isomerizations at 22°C. were calculated to be 9.05 and 2.91, respectively. The results were interpreted by the mechanism proposed by Golub, according to which the double bonds from π complexes with radiolytic fragments from sensitizers give a radical transition state capable of interconversion. However, our results showing that heating shifts the equilibrium toward trans isomer are not in accord with the mechanisms of the radiation-induced isomerization of polybutadiene of Golub and those for photoisomerization of aromatic azo compounds.     

Spectroscopic studies of microwave-excited plasma

Manganese solution was sprayed into a microwave-excited plasma torch (2450 MHz and ca. 200 W), whose profile was examined; the electron temperature, the degree or ionization and the total number of atoms and ions were estimated. Effects of alkali and alkaline earth metals were found to depend on the ionisation potentials of both manganese and the added metal.     

Nb and N co-doped TiO2 for a high-performance deNO x photocatalyst under visible LED light irradiation

By a facile and rapid microwave-assisted hydrothermal reaction at 190 °C for 30 min, niobium and nitrogen co-doping TiO₂ nanoparticles were prepared. The obtained samples were characterized by XRD, UV–Vis spectroscopy, EDX analysis, and BET measurements. To evaluate the photocatalytic activity, destruction of NO _x gas under the irradiation of several LED lamps with various wavelengths were carried out. Although co-doping of Nb with N into TiO₂ resulted in the decrement of the specific surface area, it was useful to improve the photocatalytic activity for the oxidative destruction of NO, probably due to the effective reduction of the anion vacancy in the lattice which acts as the recombination center of the photo-induced electrons and holes.     

Pyrolysis—gas chromatographic determination of run numbers in methyl methacrylate--styrene copolymers using the boundary effect

By considering the effect of neighbouring monomer units in depropagating polymer chain radicals on the formation of degradation products, a new boundary effect theory was developed in order to elucidate the sequence distributions in vinyl-type copolymers using the corresponding monomer yields. This theory was applied succesfully to the calculation of the sequence distributions in methyl methacrylate—styrene copolymers in terms of the run numbers. The significance of newly introduced parameters (monomer formation probability constants) is also discussed.     

Morphology-controlled synthesis of W18O49 nanostructures and their near-infrared absorption properties

The morphology-controlled synthesis and near-infrared (NIR) absorption properties of W(18)O(49) were systematically investigated for the application of innovative energy-saving windows. Various morphologies of W(18)O(49), such as nanorods, nanofibers, nanograins, nanoassembles, nanoplates, and nanoparticles, with various sizes were successfully synthesized by solvothermal reactions using organic alcohols as reaction media and WCl(6), W(EtO)(6), and WO(3) solids as the tungsten source. W(18)O(49) nanorods of less than 50 nm in length showed the best optical performance as an effective solar filter, which realized high transmittance in the visible region as well as excellent shielding properties of NIR light. Meanwhile, the W(18)O(49) nanorods also exhibited strong absorption of NIR light and instantaneous conversion of the absorbed photoenergy to the local heat.     

Synthesis of photocatalytic active fibrous titania by the solvothermal reactions

Abstract

Fibrous titania was synthesized by the solvothermal reactions of H₁Ti₄O₉ nH₂in different media. H₂Ti₄O₉·nH₂O transformed in steps to H₂Ti₈O₁₇, monoclinic TiO_z, anatase and rutile. The phase transformation temperature and microstructure of the products changed significantly depending on the heating environment. The critical temperature at which anatase appeared in liquid media was much lower than that in air. The titania fibers consisted of nanocrystals of TiO₂. The crystallite size and crystallinity of titania decreased with decreasing the dielectric constant of the reaction medium. Consequently, the photocatalytic activity of titania changed with heat treatment media in the following sequence: ethanol, methanol > water > air, i.e., fibrous titania possessing excellent photocatalytic activity could be obtained by the solvothermal reactions using alcohol such as methanol and ethanol. Titania powders crystallized by the solvothermal reaction in methanol also possessed excellent thermal stability.     

The application of a new sampling technique using an atomizer for chemical ionization mass spectrometry to free amino acids,drug components,higher phthalates and oligomers of styrene and ethyleneglycol

A new vacuum atomizing sample introduction device was developed and applied to take stable and reproducible chemical ionization mass spectra of various involatile compounds. As examples, chemical ionization spectra of some free amino acids, drug components in a cold medicine, higher phthalates, oligomers of styrene and ethyleneglycol, etc., are presented.