Development of High-Pressure ESR System Using Micro-coil

We have developed the high-pressure electron spin resonance (ESR) system using a micro-coil in the frequency region up to around 2 GHz and potentially 10 GHz. The hybrid-type piston-cylinder pressure cell whose maximum pressure reaches 4 GPa was used. In this study, we obtained ESR spectra at 2.3 GPa successfully, which can never be obtained by the single-layer piston-cylinder pressure cell. The minimum detectable spin number was estimated to be the order of 10¹² spins/G. Moreover, it is shown that the sensitivity can be improved by two orders of magnitude using the field modulation technique. This high-pressure ESR technique is a promising one to achieve the sensitivity and the high pressure simultaneously.     

Evaluation of electron-hole recombination properties of titanium (IV) oxide particles with high photocatalytic activity

Electron-hole recombination in nano-sized titanium(IV) oxide (TiO₂) particles with various physical properties, which have been shown to be highly active photocatalysts, was evaluated by quantitative analysis of reduced titanium species (Ti³⁺), which might be formed at crystalline defective sites in TiO₂ particles through photo-irradiation in the presence of a hole scavenger under deaerated conditions. These highly active photocatalyst samples were synthesized by hydrothermal crystallization in organic media (HyCOM method) and post-calcination. The Ti³⁺ density decreased with increasing calcination temperature (T _c), and a linear correlation was observed between the Ti³⁺ density and rate constant for electron-hole recombination evaluated by femtosecond pump-probe diffuse reflection spectroscopy. Reaction rate (R _Ag) and the amount of silver ions (Ag⁺) adsorbed on TiO₂ particles ([Ag⁺]_ads) were measured for photocatalytic silver metal deposition along with oxygen formation from an aqueous Ag⁺ solution under deaerated conditions, and the slope of the R _Ag versus [Ag⁺]_ads plot was determined. Kinetic investigation of this reaction showed that the reciprocal of the slope was approximately related to the ratio of the rates for electron-hole recombination and electron trapping (k _r/k _e ratio). The k _r/k _e ratio decreased as T _c increased, and the logarithm of the k _r/k _e ratio was linearly related with Ti³⁺ density. These two parameters were used as a measure for the recombination properties of TiO₂ photocatalysts with various physical properties.     

Emulsion type new vehicle for soft gelatin capsule available for preclinical and clinical trials: effects of PEG 6000 and PVP K30 on physicochemical stability of new vehicle.

To prevent temperature-dependent gel-sol transformation of an o/w emulsion type new vehicle system for a soft gelatin capsule, which may be available for both preclinical and clinical trials, the basic new vehicle formulation (PEG 400:purified water:medium chain triglyceride:polyoxyethylene (20) cetylether = 77:10:10:3) was modified by partially (1, 2 or 3%) replacing PEG 400 with PEG 6000 or PVP K30. When 2 or 3% of PEG 400 was replaced with PEG 6000, temperature-dependent gel-sol transformation was prevented at temperatures below 40 degrees C, and the vehicle appeared to be stable during 8 weeks of storage at 4 to 40 degrees C; the particle size distribution remained unchanged. When 1% of PEG 400 was replaced with PEG 6000, gel-sol transformation was not prevented, though phase separation was not observed at sol state, and the particle size distribution was shifted to be in a larger particle size range after 2 weeks of storage. When PEG 400 was partially (1, 2 or 3%) replaced with PVP K30, temperature-dependent gel-sol transformation was not prevented and, after 2 weeks of storage at 40 degrees C, the particle size distributions of the vehicles were shifted to be in a larger particle size range and the vehicles were separated into two layers. These results suggested that a small amount of PEG 6000 plays an important role in preventing temperature-dependent gel-sol transformation of our developed vehicle system.     

Studies on iron(III) complex with 5,6-diamino-1,3-dimethyluracil

Reaction of 5,6-diamino-1,3-dimethyluracil (DDU) with iron(III) ion gave a fine blue colouration due to the formation of Fe[(DDU—H)₃]·2HClO₄. An oxidation product (7), C₁₂H₁₂N₆O₄, was also isolated from the reaction mixture.     

Photo‐Cross‐Linked Small‐Molecule Microarrays as Chemical Genomic Tools for Dissecting Protein–Ligand Interactions

We have developed a unique photo‐cross‐linking approach for immobilizing a variety of small molecules in a functional‐group‐independent manner. Our approach depends on the reactivity of the carbene species generated from trifluoromethylaryldiazirine upon UV irradiation. It was demonstrated in model experiments that the photogenerated carbenes were able to react with every small molecule tested, and they produced multiple conjugates in most cases. It was also found in on‐array immobilization experiments that various small molecules were immobilized, and the immobilized small molecules retained their ability to interact with their binding proteins. With this approach, photo‐cross‐linked microarrays of about 2000 natural products and drugs were constructed. This photo‐cross‐linked microarray format was found to be useful not merely for ligand screening but also to study the structure–activity relationship, that is, the relationship between the structural motif (or pharmacophore) found in small molecules and its binding affinity toward a protein, by taking advantage of the nonselective nature of the photo‐cross‐linking process.     

Determination of vanadium in high grade carbons by radioanalytical methods

The present work deals with the determination of vanadium in high grade carbons by three radioanalytical methods, viz. thermal neutron activation analysis with an accelerator, thermal neutron activation analysis with a reactor and proton induced X-ray emission analysis with an accelerator. It is cleared from this study that thermal neutron activation with an accelerator is more convenient for the rapid and non-destructive analysis of ppm-level vanadium in bulk carbons than thermal neutron activation analysis with a reactor. Proton induced X-ray emission is less useful for the analysis of bulk samples.     

Determination of cyclosporin A in whole blood by high-performance liquid chromatography using automated column switching

A fully automated high-performance liquid chromatographic column-switching system is presented for the determination of cyclosporin A in whole blood. After blood proteins were precipitated with acetonitrile, the supernatant was automatically loaded on to a cyanopropyl column for initial separation, and then the fraction containing cyclosporin A was loaded on to a trimethylsilica column for final separation and quantitation. Cyclosporin A was detected by ultraviolet absorption at 205 nm. The minimum detectable concentration of cyclosporin A was 5 ng/ml in 100 microliter of blood. The coefficient of variation of the method was 1.755, 1.748 and 0.655% in whole blood when spiked at the 170, 425 and 850 ng/ml levels, respectively. One assay was completed in 15 min.     

Assignment of photoelectro bands for naphthalene and anthracene by penning ionization electron spectroscopy

The Ne¹(³P₂) Penning electron spectra and the Ne I photoelectron spectra were measured in the gas phase. The observed systematic differences in their relative intensities were interpreted in terms of the electron distributions of the relevant molecular orbitals and used for assignment of the deep π bands, π₁ (12.4 eV) for naphthalene, and π₂ (11.9 eV) and π₁ (12.8 eV) for anthracene.