Fabrication of densely packed titania nanosheet films on solid surface by use of Langmuir-Blodgett deposition method without amphiphilic additives

Densely packed exfoliated nanosheet films such as Ti0.91O2, Ti0.8M0.2O2 (M = Co, Ni), Ti0.6Fe0.4O2, and Ca2Nb3O10 on solid substrates were prepared by the LB transfer method without any amphiphilic additives at the air-water interface. Nanosheet crystallites covered nearly 95% on the solid surface with minimum overlapping of nanosheets. The LB transfer method of the Ti0.91O2 nanosheet monolayer film is applicable for not only hydrophilic substrates such as quartz, silicon, indium-tin oxide (ITO), and glass but also the hydrophobic Au surface. On the basis of these points, the LB transfer method has advantages compared to the alternating layer-by-layer method, which makes use of oppositely charged polyelectrolytes such as poly(ethylenimine) (PEI). Adsorption of hydrophobic Ti0.91O2 nanosheets at the air-water interface is responsible for this LB transfer deposition method. The addition of tetrabutylammonium bromide into the subphase assisted the adsorption, causing an increase in the adsorbed amount of Ti0.91O2 nanosheets at the air-water interface.     

Vacuum cosmological solution in a 6D universe

A simple vacuum cosmological solution that is a function ofct, Gm/c ² andeG ^1/2/C² is obtained in the 6D space-time-mass-charge universe which is proposed by Wesson [1] with the introduction of the sixth coordinate of charge in order to obtain a unified theory of gravity and electromagnetism along the line of his original 5D space-time-mass universe [2]. It reduces to a similar solution to that of the radiation era in the 4D FRW universe through the compactifications of the extra dimensions. The trajectory of a test particle in the 6D universe is also studied by using the solution.     

Preparation and characterization of aqueous colloids of Pt-Ru nanoparticles

A synthetic method for platinum-ruthenium (PtRu) nanoparticles in aqueous media is proposed. This method employs citric acid as a capping agent and NaBH(4) as a reducing agent with the aid of pH control. The number-averaged size of the PtRu nanoparticles was ca. 2 nm. The crystal phase and chemical composition of the nanoparticles was investigated by X-ray diffraction measurement and scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis, which indicated that the nanoparticles mainly consisted of an alloy of Pt and Ru. Electrochemical measurement showed that the PtRu nanoparticles had catalytic activity for methanol oxidation.     

Asymmetric transfer hydrogenation of alpha-aminoalkyl alpha'-chloromethyl ketones with chiral Rh complexes

Asymmetric transfer hydrogenation of N-substituted (3S)-3-amino-1-chloro-4-phenyl-2-butanones in the presence of CpRhCl[(R,R)-Tsdpen] (S/C = 1000) with a mixture of formic acid/triethylamine gave N-substituted (2R,3S)-3-amino-1-chloro-2-hydroxy-4-phenylbutanes with up to 93% de in a quantitative yield, and reduction with the enantiomeric catalyst CpRhCl[(S,S)-Tsdpen] gave (2S,3S)-diastereomeric alcohol with up to 96% de.     

Electrophilic and oxidative chemistry of pyrene and its non-alternant isomers: theoretical (DFT, GIAO-NMR, NICS) study of protonation carbocations and oxidation dications from pyrene, azupyrene (dicyclopenta[ef,kl]heptalene) and dicyclohepta[ed,gh]pentalene

Mono- and diprotonated carbocations and the two-electron oxidation dications derived from parent pyrene and its nonalternant isomers "azupyrene"(dicyclopenta[ef,kl]heptalene)(DCPH) and dicyclohepta[ed,gh]pentalene (DCHP) were studied by DFT at the B3LYP/6-31G(d) level. The most likely site(s) for mono- and diprotonation were determined based on relative arenium ion energies and the structures of the energetically most favored carbocations were determined by geometry optimization. The NMR chemical shifts for the protonated mono- and dications and the oxidation dications were computed by GIAO-NMR at the B3LYP/6-31G(d)//B3LYP/6-31G(d) level and their charge delocalization paths were deduced based on magnitude of the computed [capital Delta][small delta](13)C values and the NPA-derived changes in charges. Relative aromaticity/antiaromaticity in various rings in the energetically favored mono- and dications was estimated via NICS and [capital Delta]NICS. Calculated NMR chemical shift data for and were compared with the available experimental NMR values. The available data on chemical and physical properties of DCPH and DCHP are extremely limited and biological activity data are non-existent. The present study provides the first glance into their carbocations and oxidation dications, while augmenting and reinforcing the previous stable ion data on the pyrenium cations.     

Role of Water Activity on the Synthesis of Vinyl Thymidine Catalyzed by Protease from Bacillus Subtilis

The transesterification activity of Bioprase, a protease from Bacillus subtilis, in dimethylformamide (DMF) is found to depend strongly on water addition. For the transesterification between thymidine and divinyl adipate by Bioprase in DMF with water (5–40%), the conversion rate of thymidine to the ester is much higher than the rate in DMF without the addition of water. For example, the transesterification reaction of 0.25 M thymidine with 1 M divinyl adipate in DMF in the presence of 10% water was catalyzed by Bioprase (50 mg · ml^?1) at 30 °C for only 10–20 minutes to give 5′‐O‐vinyladipoyl thymidine (conversion ca. 90%), but the reaction did not proceed without the addition of water. Furthermore, the water effect is useful for the transesterification of thymidine with divinyl sebacate, which has a longer alkyl chain than divinyl adipate. This investigation showed that DMF adsorbs on the enzyme surface instead of essential water in the reaction of DMF without addition of water. On the other hand, in the reaction of DMF/water cosolvents, essential water bound to enzyme was not removed by DMF, and a higher transesterification activity occurs thereafter.

Effect of water on the transesterification of thymidine catalyzed by Bioprase in DMF.     

STM observation of alkyl-chain-assisted self-assembled monolayers of pyridine-coordinated porphyrin rhodium chlorides

Alkyl-chain-assisted self-assembled monolayers of pyridine-coordinated porphyrin rhodium chlorides were observed at the solid-liquid interface by scanning tunneling microscopy (STM). The resolved images at a molecular level were obtainable in the pure solution of pyridine-coordinated porphyrin rhodium chloride with four triacontyl groups [Rh(C300PP)(Cl)(Py)]. In the case of pyridine-coordinated porphyrin rhodium chloride with four octadecyl groups [Rh(C18OPP)(Cl)(Py)], the STM images were not obtainable in the pure solution of Rh(C18OPP)(Cl)(Py) but obtainable in the mixture containing Rh(C18OPP)(Cl)(Py) and free porphyrin C18OPP. On the basis of the mixed self-assembled monolayer analysis, the apparent difference in the adsorption free energy between Rh(CnOPP)(Cl)(Py) and CnOPP (deltaGapp) was calculated. The calculated deltaGapp values for C18OPP and C30OPP mixed systems were quite different. The disadvantage of the adsorption free energy of Rh(C18OPP)(Cl)(Py) makes it difficult to obtain molecularly resolved images of Rh(C18OPP)(Cl)(Py), and the large adsorption energy due to the long alkyl chains enabled us to obtain molecularly resolved images of Rh(C30OPP)(Cl)(Py).     

Removal of boron(III) by N-methylglucamine-type cellulose derivatives with higher adsorption rate

To obtain adsorbents for boron(III) derived from a natural polymer, two forms (powder and fiber) of N-methylglucamine-type cellulose derivatives were newly synthesized. After the graft polymerization of two forms of cellulose with vinyl monomer having epoxy groups, the N-methylglucamine-type cellulose derivatives were obtained by the reaction of the grafted cellulose with N-methylglucamine. The adsorption capacities of the cellulose derivatives for boron(III) were the same levels as that of a commercially available N-methylglucamine-type polystyrene resin. However, the cellulose derivatives adsorbed boron(III) more quickly than the polystyrene resin. The adsorption and desorption of boron(III) with a column method using the cellulose fiber were achieved at a higher flow rate than that using the polystyrene resin. In addition, the boron(III), adsorbed on the cellulose fiber column, was quantitatively recovered with dilute hydrochloric acid in 20- and 200-fold increased concentrations. Consequently, it was found that the cellulose derivatives were superior to the polystyrene resin as adsorbents for boron(III) for treatment of a large quantity of wastewater.     

Determination of molecular mass of acidic polysaccharides by capillary electrophoresis

We developed a method for the determination of molecular mass of acidic polysaccharides based on their high-resolution separation by capillary electrophoresis. Polymers of N-acetylneuraminic acid (NeuAc) and polysulfated hyaluronic acid were separated into their molecular species up to 100 mono- and 20 disaccharide units, respectively. The relationship between the molecular mass of NeuAc-polymer and their electrophoretic mobilities showed good linearity, and was applied to the determination of molecular masses of larger NeuAc species unresolved by capillary electrophoresis under the same conditions. In the first step, the standard curve for the determination of molecular mass was constructed from the relationship between electrophoretic mobility and molecular mass. Subsequently, the mobility was extrapolated to the standard curve, and the molecular mass was calculated. Five different preparations of NeuAc polymers having different molecular masses showed smaller values than those determined by conventional chromatographic techniques. Further, molecular mass determined by the present method correlated with number-average molecular mass. The methodology presented here was applied to the determination of molecular mass of polysulfated hyaluronic acid. The data indicated that native hyaluronic acid was extensively degraded during sulfonation reaction.