Gas transport properties in thermally cured aromatic polyimide membranes

Aromatic polyimide derived from 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 3,3′-diaminodiphenylsulfone (m-DDS) has been synthesized to facilitate the study of relationships between the polymer structure and the gas transport properties (permeability and selectivity). The gas permeability and selectivity of CO₂, O₂, N₂, and CH₄ for the 6FDA-m-DDS membranes cured at 150, 200, and 250°C have been determined at 35°C and at pressures up to 760 cmHg. The packing density and the fluorescence intensity of the 6FDA-m-DDS polyimide increased sharply with the increasing curing temperature. We propose that this behavior is associated with an increase in intermolecular and/or intramolecular interactions by a charge transfer complex formed in 6FDA-m-DDS containing an alternating sequence of electron donor and electron aceptor molecules. The effect of the microstructure of the thermally cured 6FDA-m-DDS membranes on their gas transport properties is discussed.     

Effect of Pt loading on the photocatalytic reactivity of titanium oxide thin films prepared by ion engineering techniques

Platinum-loaded titanium oxide thin-film photocatalysts were prepared by using an ionized cluster beam (ICB) deposition method and a RF magnetron sputtering (RF-MS) deposition method as dry processes. From the results of the photocatalytic oxidation of acetaldehyde with O₂ under UV light irradiation, small amounts of Pt loading (less than 10 nm film thickness) were found to dramatically enhance the photocatalytic reactivity. However, when TiO₂ thin films were loaded with relatively larger amounts of Pt (more than 30 nm as the film thickness), the photocatalytic reactivity became lower than for the pure TiO₂ thin films. Moreover, investigations of the ratio of Pt loaded onto the surface of the thin film catalysts by XPS measurements revealed that the small amounts of Pt loaded exist as very small clusters working to efficiently enhance the charge separation, whereas, large amounts of Pt covers the entire surface of the TiO₂ thin films, resulting in a decrease of the photocatalytic reactivity.     

Synthesis of nanosized TiO2 particles in reverse micelle systems and their photocatalytic activity for degradation of toluene in gas phase

Nanosized pure TiO₂ particles with high crystallinity and large surface area were prepared by hydrolysis of tetrabutyl titanate in water/Triton X-100/isooctane reverse micelle solutions as reaction media followed by hydrothermal treatment to improve crystallinity. The prepared TiO₂ nanoparticles were characterized by XRD, BET, TGA, FT-IR and TEM. The size of ultrafine particles was controlled by changing the water content of the reverse micelle solution. The TiO₂ particles showed monodispersity, large surface area and high degrees of crystallinity and thermostability. The photocatalytic activity of the TiO₂ particles was evaluated by decomposition of toluene in the gas phase. The activity of the TiO₂ nanoparticles was higher than that of commercially available anatase fine particles, such as ST-01, which is one of the most active photocatalysts for degradation of organic compounds in the gas phase.     

CpRu(PN) complex-catalyzed isomerization of allylic alcohols and its application to the asymmetric synthesis of muscone

Highly efficient isomerization of allylic alcohols into saturated carbonyls is accomplished using the catalyst system of Cp*RuCl[Ph2P(CH2)2NH2-kappa2-P,N]-KOt-Bu (Cp* = eta5-C5(CH3)5) under mild conditions. Mechanistic consideration based on isotope-labeling experiments indicated the present reaction is applicable to the asymmetric isomerization of racemic sec-allylic alcohols with a prochiral olefin via dynamic kinetic resolution. A concise asymmetric synthesis of muscone has been achieved, where the asymmetric isomerization using an optically active ligand is a key reaction.     

13C-NMR spectra of 6-aminohexyl glycosides of O-β-D-galactopyranosyl-2-acetamido-2-deoxy-β-D-glucopyranose

¹³C-NMR spectral data on 6-aminohexyl glycosides of $\text{O}$-β-$\text{D}$-galactopyranosyl-2-acetamido-2-deoxy-β-$\text{D}$-glucopyranose are pr     

Palladium-catalyzed cyclization reactions of 3-propargylthio 1,2,4-triazin-5(2h)-ones to thiazolo-1,2,4-triazinones

Selective transformation of 3-propargylthio-1,2,4-triazin-5(2H)-ones ($\text{1}$) to 6-methylene-6,7-dihydro-4H-thiazolo[2,3-c][1,2,4]-triazin-4-ones ($\text{2}$) and 3-methylene-2,3-dihydro-7H-thiazolo[3,2-b]-[1,2,4]triazin-7-ones ($\text{3}$) is performed under the conditions of Pd(II) salt or sodium hydroxide catalysis, respectively.     

Subcellular localization of docosahexaenoic acid and arachidonic acid ω-hydroxylation activity in the brain, liver and colonic adenocarcinoma

A homogenate of rat brain, rat liver or human colonic well differentiated adenocarcinoma was prepared in 250 mM sucrose isoosmolaric buffer (pH 7.6) and fractionated by differential centrifugation at 10³, 10⁴ and 10⁵ g. Each precipitate or supernatant was incubated with NADPH and docosahexaenoic acid or arachidonic acid as a substrate for 30 min at 37°C under aerobic conditions. ω-Hydroxydocosahexaenoic acid or ω-hydroxyeicosatetraenoic acid from an incubation mixture was detected by reversed-phase high-performance liquid chromatography-thermospray mass spectrometry with selected-ion monitoring. ω-Hydroxy polyunsaturated fatty acids were characterized by high intensity of the molecular ion (MH⁺) although common hydroxy polyunsaturated fatty acids were characterized by high intensity of the MH⁺ - H₂O ion. For the rat brain, ω-hydroxylation activity (the amount of ω-hydroxy product produced in 30 min) was concentrated to a 103 g precipitate although the specific activity (the activity per 1 mg of protein) in the 10³ g precipitate did not indicate superiority over other fractions. However, the specific activity of the rat brain increased on addition of a 10⁴ or 10⁵ g precipitate. For the rat liver, although ω-hydroxylation activity was concentrated to a 10³ g precipitate, the specific activity was concentrated to a 10⁵ g precipitate and the Subcellular localization differed from that of rat brain. In the human colonic well differentiated adenocarcinoma, although ω-hydroxylation activity was relatively high in the 10³ g supernatant, the specific activity was relatively high in the 10³ and 10⁵ g precipitates. These results suggest that there is a difference regarding subcellular localization of the ω-hydroxylation activity depending on the species of the organs.     

Photoreactions between [60]fullerene and various aromatic tertiary amines

The photoreactions of [60]fullerene with aromatic tertiary amines such as N,N-dimethylaniline and N,N-dimethyl-1-naphthylamine gave two or three types of [60]fullerene adducts. The reaction efficiency in the series of p-substituted N,N-dimethylanilines remarkably increased with increasing electron-donating properties of aromatic tertiary amines employed.     

Structure of sclerosporin,a sporogenic substance of sclerotiniafructicola

Sclerosporin, the major sporogenic substance of $\text{S. fructicola}$, and its related metabolite, sclerosporal, were shown to have the plain structures, $\text{1}$, and $\text{2}$, respectively. by using a micro-amount of the samples, and co-occurring sclerosporene probably to have the structure $\text{3}$.