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.     

2,9-dithia-1-thioxophosphabicyclo[4.3.0]nona-3,7-dienes. Precursors of new type heterodienes, 2-thioxo-1,2-thiaphospholes

The reaction of arylmethylenepinacolones, chalcones and 2-arylmethylene-1-tetralones with P₄S₁₀ in the presence of triethylamine gave the title compounds, from which 2-thioxo-1,2-thiaphospholes (phosphathiophenes) were generated by the thermolysis and reacted with acrylonitrile to give [4+2]cyclo-adducts.     

Synthesis in the diazasteroid group X. A synthesis of 8,12-diaza-D-homosteroid

The condensation of 1-aminoethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline 1 with 1,2-cyclohexanedione 2 gave the 8,12-diaza- D -homosteroid system 3 , which was reduced with Adams' catalyst followed by acetic anhydride acetylation to afford the 8,12-diaza- D -homosteroids 4a,b .     

Simultaneous microanalysis of N-linked oligosaccharides in a glycoprotein using microbore graphitized carbon column liquid chromatography-mass spectrometry

We previously reported that graphitized carbon column liquid chromatography-mass spectrometry (GCC-LC-MS) is very useful for the structural analysis of carbohydrates in a glycoprotein. In this study, GCC-LC-MS was adapted for the simultaneous microanalysis of oligosaccharides. A variety of oligosaccharide alditols prepared from fetuin, ribonuclease B, and recombinant human erythropoietin were used as model oligosaccharides. The use of microbore GCC-LC-MS was found to be successful for rapid, sensitive, and simultaneous analysis of high-mannose-type, desialylated fucosyl complex-type, sialylated complex-type, and sialylated fucosyl complex-type oligosaccharide alditols. Furthermore, we demonstrate that this method is applicable to the analysis of carbohydrate heterogeneity in a glycoprotein that possesses diverse oligosaccharides. Microbore GCC-LC-MS was able to characterize high-mannose-type, hybrid-type, and complex-type oligosaccharides in tissue plasminogen activator produced from human melanoma cells in a single analysis.     

Clathrate hydrate formation in (methane + water + methylcyclohexanone) systems: the first phase equilibrium data

The present study experimentally demonstrated clathrate hydrate formation in the systems of (methane + water + each of the three methylcyclohexanone isomers, i.e., 2-methylcyclohexanone, 3-methylcyclohexanone, and 4-methylcyclohexanone) and measured the first data of the quadruple (water rich liquid + hydrate + methylcyclohexanone rich liquid + methane rich vapor) equilibrium pressure and temperature conditions in these systems over the temperatures from T=273 K to T=281 K. In the three systems with methylcyclohexanone, the measured equilibrium pressure at each given temperature is ∼1.3 MPa lower than that in a structure-I hydrate forming (methane + water) system without any methylcyclohexanone, which suggests the formation of structure-H hydrates with methylcyclohexanones as large-molecule guest substances. Among the three systems, 3-methylcyclohexanone provides the highest equilibrium pressure, and 2-methylcyclohexanone, the lowest.     

Synthetic study of macquarimicins: highly stereoselective construction of the AB-ring system

The highly stereoselective synthesis of the AB-ring system of macquarimicins, a novel class of microbial metabolites with inhibitory activity for neutral sphingomyelinase, has been achieved. The present synthesis features the highly stereocontrolled construction of the cis-tetrahydroindan structure via the intramolecular Diels-Alder reaction of an (E,Z,E)-1,6,8-nonatriene derived from D-glyceraldehyde acetonide. Reaction: see text.     

Catalytic highly enantioselective 1,3-dipolar cycloaddition reaction of nitrones with 3-alkenoyl-2-oxazolidinones by use of a bidentate chiral bis(imine) ligand–Cu(II) triflate complex

A copper(II) triflate complex with bidentate, chiral C₂-symmetric cyclohexane-1,2-bis[(2,6-dichlorophenylmethylene)amine] catalyzed the 1,3-dipolar cycloaddition reactions of nitrones with electron-deficient dipolarophiles, 3-(2-alkenoyl)-1,3-oxazolidin-2-ones to give isoxazolidine cycloadducts with extremely high endo- and enantioselectivities.     

Particle isolation for analysis of uranium minor isotopes in individual particles by secondary ion mass spectrometry

A new technique to measure ²³⁴U/²³⁸U and ²³⁶U/²³⁸U isotope ratios for individual particles in environmental samples was developed, which was a combination of particle isolation under scanning electron microscope (SEM) and secondary ion mass spectrometry (SIMS). The technique was verified by measuring ²³⁴U/²³⁸U and ²³⁶U/²³⁸U isotope ratios in individual particles in a simulated environmental sample containing uranium standard (NBL CRM U010) and Pb metal particles. When the uranium particles were not isolated, the relative deviations of the measured isotope ratios from the reference values increased with increasing the signal intensity ratio of ²⁰⁸Pb to ²³⁸U, which was due to the molecular ion interferences by the Pb particles co-existing in the sputtered area. By the isolation of individual uranium particles, the interferences were eliminated and the measured isotope ratios were in good agreement with the reference values. The maximum relative deviations among 20 particles were 8.9% for ²³⁴U/²³⁸U and 13.1% for ²³⁶U/²³⁸U isotope ratios, respectively. The technique was also successfully applied to the analysis of a real swipe sample containing various kinds of elements.     

2-Pyridylaldehydebenzoylhydrazone derivatives as highly selective precolumn chelating reagents for nickel (II) ion in kinetic differentiation mode high-performance liquid chromatography

2-Pyridylaldehydearoylhydrazones have been examined as reagents for precolumn derivatization of metal ions in the HPLC-spectrophotometry system. With the simplest analog, 2-pyridylaldehydebenzoylhydrazone (PAB), among 11 metal ions only Ni(II) ion gives the peak while the other metal chelates seem to be dissociated on an HPLC column where no added PAB is present in the eluent solutions. All other PAB analogs exhibit the peak for Ni(II) ion as well as Co(III) ion. In one reagent system, V(V) and Fe(II) chelates also appear in the chromatograms. It has been stressed that the selectivity principle is the kinetic differentiation (KD) towards metal chelates associated with the HPLC processes. The specificity for Ni(II) ion is in close relation to a key structure of the ligand molecules which provides an N,N,O coplanar coordination environment to form two five-membered chelate rings. An extremely selective and sensitive KD-HPLC method for the quantitation of Ni(II) ion at the ultra-trace levels was assessed; the detection limit (3 _Blank) for Ni(II) ion was down to 5.34 × 10^–9 mol l^–1 (31.5 pg in a 100 l injection) and the excellent applicability was checked using coal fly ash samples.     

Facile assignment of sequence ions of a peptide labelled with 18O at the carboxyl terminus.

The combination of collision-induced dissociation (CID) and linked-scan analysis was used for analysing the sequence ions from the precursor ion of a peptide, which had been labelled with 18O at its carboxyl terminus (C-terminus) using 40 atom % H2 18O. The CID and linked-scan mass spectrum of the labelled peptide gave two series of sequence-ion signals: the one, originating from the C-terminus of the labelled peptide, showed a doublet signal due to the part-incorporation of 18O into the carboxyl group at the C-terminus, while the other, originating from the amino terminus (N-terminus), has the natural isotopic ion distribution. From the distribution of the isotopic ions in a single CID spectrum, the sequence ions containing the C-terminus could be readily differentiated from those containing the N-terminus, allowing the facile assignment of sequence ions to the amino-acid sequence of a peptide by CID and linked-scan analysis. This method was successfully applied to determination of the amino-acid sequence of the light-chain of mouse anti-porphyrin monoclonal antibody.