Ultraviolet-Laser-Induced Crystallization of Sol-Gel Derived Indium Oxide Films

Modification of sol-gel derived indium oxide thin films using ultraviolet lasers was investigated. Irradiation by an ArF excimer (6.4 eV) and the fourth harmonic generation of a Nd : YAG laser (4.7 eV) was found to be effective in crystallization with a loss of hydroxyl groups and a decrease in the sheet resistance of the sol-gel films. Transparent crystalline indium oxide films were successfully obtained by 6.4 eV laser irradiation at fluences below 20 mJ/(cm2·shot), whereas degradation of the films was induced by a relatively high-fluence beam.     

Evaluation of the efficiency of the photocatalytic one-electron oxidation reaction of aromatic compounds adsorbed on a TiO2 surface

The TiO2 photocatalytic one-electron oxidation mechanism of aromatic sulfides with a methylene bridging group (-(CH2)n-, n=0-4) between the 4-(methylthio)phenyl chromophore and the carboxylate binding group on the surface of a TiO2 powder slurried in acetonitrile (MeCN) has been investigated by time-resolved diffuse reflectance (TDR) spectroscopy. The electronic coupling element (H(DA)) between the hole donor and acceptor, which was estimated from the spectroscopic characteristics of the charge transfer (CT) complexes of the substrates (S) and the TiO2 surface, exhibited an exponential decline with the increasing of the methylene number of S. The determined decay factor (beta) of 9 nm(-1) also supports the fact that the 4-(methylthio)phenyl chromophore is separated from the TiO2 surface. The efficiency of the one-electron oxidation of S adsorbed on the TiO2 surface, which was determined from the relationship between the amount of adsorbates and the concentration of the generated radical cations, significantly depended on the H(DA) value, but not on the oxidation potential of S determined in homogeneous solution.     

Study of the metastable region in the growth of GaN using the Na flux method

It was revealed that the metastable region, in which liquid phase epitaxy (LPE) of GaN single crystals proceeds without the generation of polycrystals, expands with growth temperature in the Na flux method. The metastable region appears when LPE growth proceeds at temperatures above 1073 K, although generation of polycrystals inevitably occurs on a crucible at temperatures less than 1073 K. The highest growth rate of 14 μm/h in a small experimental setup was achieved at a temperature of 1163 K with a nitrogen pressure of 5.5 MPa due to complete suppression of the growth of polycrystals on a crucible, even though the supersaturation at this condition reached a fairly high level.Also, an LPE crystal with a flat surface could easily be obtained under high-temperature conditions.     

Chemical and Structural Properties of Drug–protein Nanocomposites Prepared by Pulsed Laser Deposition from Conjugated Targets

Nanostructured indomethacin (IM) – bovine serum albumin (BSA) composite particulates below 50 nm were obtained by pulsed laser deposition (PLD) with 1064 nm IR beam. IM and BSA powders were coground for up to 210 min to prepare conjugated targets for PLD with varying structural states. The ablation threshold was determined to be around 1.8 J/cm², from in situ monitoring of the deposited amount by a QCM sensor. The crystallinity of IM was preserved after PLD at 5 J/cm² and decreased with increasing the laser fluence. The non-crystalline state of IM in the target after prolonged cogrinding with BSA, was also preserved in the deposited film. FT-IR absorption bands due to amide I of BSA became sharper while preserving the peak top position after cogrinding with IM. Conversely, we observed broadening of the amide I bands by PLD. Preservation and change in the chemical and structural states of the conjugates after PLD is discussed in terms of the secondary structure of BSA and crystallinity of IM.     

Greener Synthesis of Pristane by Flow Dehydrative Hydrogenation of Allylic Alcohol Using a Packed-Bed Reactor Charged by Pd/C as a Single Catalyst

Our previous work established a continuous-flow synthesis of pristane, which is a saturated branched alkane obtained from a Basking Shark. The dehydration of an allylic alcohol that is the key to a tetraene was carried out using a packed-bed reactor charged by an acid–silica catalyst (HO-SAS) and flow hydrogenation using molecular hydrogen via a Pd/C catalyst followed. The present work relies on the additional propensity of Pd/C to serve as an acid catalyst, which allows us to perform a flow synthesis of pristane from the aforementioned key allylic alcohol in the presence of molecular hydrogen using Pd/C as a single catalyst, which is applied to both dehydration and hydrogenation. The present one-column-two-reaction-flow system could eliminate the use of an acid catalyst such as HO-SAS and lead to a significant simplification of the production process.     

Reaction of N,N-dimethylselenocarbamoyl chloride with nucleophiles. Preparation of diselenocarbamates, selenothiocarbamates, and selenoureas

Reactions of N,N-dimethylselenocarbamoyl chloride prepared by using LiAlHSeH with nucleophiles such as lithium alkylselenolate, lithium alkylthiolate, and amines afford the corresponding diselenocarbamates, selenothiocarbamates, and selenoureas. The crystal structure of the Se-phenyl N,N-dimethyldiselenocarbamate was also determined by X-ray diffraction.     

Synthesis and characterization of macrocyclic ligands containing benzene and/or pyridine rings and their nickel(II), copper(II) and zinc(II) complexes

Macrocycles, 7,16-diethyl-5,6,7,8,9,14,15,16,17,18-decahydrodibenzo[b,i][1,4,8,11]tetraazacyclotetradecine ( 2B ), 7,16-diethyl-5,6,7,8,9,14,15,16,17,18-decahydro-(E)dipyrido[b,i][1,4,8,11]tetraazacyclotetradecine ( 2E ) and 7,16-diethyl-5,6,7,8,9,14,15,16,17,18-decahydro-(Z)-dipyrido[b,i][1,4,8,11]tetraazacyclotetradecine ( 2Z ), have been synthesized by hydrogenation of 7,16-diethyl-5,14-dihydrodibenzo[b,i][1,4,8,11]tetraazacyclotetradecine and 7,16-diethyl-5,14-dihydro-(E)- or -(Z)-dipyrido[b,i][1,4,8,11]tetraazacyclotetradecine. In each case, two isomers were produced with differing orientations of the ethyl groups relative to the macrocyclic plane. The isomers were separated by repeated recrystallization. Carbon-13 nmr spectra for the metal-free ligands were used to distinguish between the two isomers. The nickel(II), copper(II) and zinc(II) complexes of the two isomers of 2B were prepared and their spectroscopic data were determined. The ligand-field bands in the 15000–30000 cm^?1 region for the nickel(II) and copper(II) complexes are consistent with square-planar configurations. A strong band appearing at ca. 3200 cm^?1 in the infrared spectra was assigned to the N-H stretching mode which shifted to lower frequency upon metal coordination.     

Intermolecular electron transfer from excited benzophenone ketyl radical

The electron transfer from the benzophenone ketyl radical in the excited state (BPH(.-)(D(1))) to several quenchers (Qs) was investigated using nanosecond/picosecond two-color two-laser flash photolysis and nanosecond/nanosecond two-color two-laser flash photolysis. The electron transfer from BPH(.-)(D(1)) to Qs was confirmed by the transient absorption and fluorescence quenching measurements. The intermolecular electron-transfer rate constants were determined using the Stern-Volmer analysis. The driving force dependence of the electron-transfer rate was revealed.