Voltammetric studies of antimony ions in soda-lime-silica glass melts up to 1873 K.

The half wave potential of reduction of Sb5+ in 16Na2O x 10CaO x 74SiO2 glass melts was examined by differential pulse voltammetry up to 1873 K. The half wave potential shifted to the positive direction with an increase in temperature. The results indicate that the equilibrium of Sb5+/Sb3+ shifted to negative direction with an increase in temperature. The half wave potential shifted to positive direction (48 mV at 1473 K) when the atmosphere over the melts changed from pure oxygen gas to air, in agreement with the theoretical prediction. The reversibility of Pt:O2 reference electrode is confirmed.     

Optimization of operating conditions in a high-shear mixer using dem model: determination of optimal fill level

For the purpose of evaluating optimal fill level of starting materials in a high-shear mixer, discrete element method (DEM) simulation was conducted to visualize kinetic status between particles. The simulation results obtained by changing fill levels were used to determine solid fraction of particles, particle velocity, particle velocity vector, and kinetic energy and discuss the flow pattern. Optimal fill level was obtained from the information on these matters. It was pointed out that understanding the kinetic energy between particles in an agitating vessel was effective in determining the optimal fill level. Granulation experiment was conducted to validate the optimal fill level obtained by the simulation, confirming the good agreement between these two results. It was pointed out that determination of kinetic energy between particles through the simulation was effective in obtaining an index of the kinetic status of particles. Further, it was confirmed that the simulation could provide more information than conventional granulation experiments could provide and also helpful in optimizing the operating conditions.     

Detection of multiple anions by thin-layer chromatography

A novel detection method for 21 different anions by thin-layer chromatography is presented. Anions on the target plate form salts with amine in a developing solvent and are visualized after staining with citric acid-acetic anhydride reagent as white spots contrasting against a pale red-pink background. This method has particularly high sensitivity for anions of chlorate, sulfate, phosphate, chromate and dichromate (0.02-0.05 microg). The method is demonstrated to efficiently detect toxic arsenite in curry sauce as an example application. The proposed method offers highly efficient indirect detection for a wide range of anions, and serves as a purification procedure for the preparation of anionic sample solutions for other analytical methods.     

High-energy collision-induced dissociation of small polycyclic aromatic hydrocarbons

High-energy collision-induced dissociation (CID) experiments on polycyclic aromatic hydrocarbons (PAHs) having 2-6 rings, naphthalene, anthracene, phenanthrene, fluoranthene, pyrene and coronene, were performed, and the relative abundances of their fragment ions were investigated as a function of collision energy. The results revealed that the PAHs except naphthalene showed a bimodal-type distribution of positive fragmentation ions, which is closely similar to the fragment-ion distribution reported for the CID of three-dimensional fullerene, C(60)(+) and C(70)(+). The three-ring isomers of anthracene and phenanthrene and the four-ring isomers of fluoranthene and pyrene can be distinguishable in their spectra under an electron ionization energy of 70 eV, but the high-energy CID spectra of the three- and four-ring isomers were almost identical. The fragmentation corresponding to fragment ions in the low-mass region of the bimodal CID spectra could be interpreted by the simple statistical model that fragment ions are formed by random evaporation from the molecular ions after a considerable structural rearrangement, 'phase transition', occurring at some high-energy state.     

Synthesis of 6-acetamido-5-amino- and -5-guanidino-3, 4-dehydro-N-(2-ethylbutyryl)- 3-piperidinecarboxylic acids related to zanamivir and oseltamivir, inhibitors of influenza virus neuraminidases

[reaction: see text] 6-Acetamido-5-amino- and -5-guanidino-3, 4-dehydro-N-(2-ethylbutyryl)-3-piperidinecarboxylic acids (8 and 9) have been synthesized starting from natural siastatin B, a bacterial neuraminidase inhibitor isolated from Streptomyces culture in a stereospecific fashion. These compounds are related to zanamivir and oseltamivir, inhibitors of influenza virus neuraminidases.     

Finite difference simulation of nonlinear waves generated by ships of arbitrary three-dimensional configuration

A modified marker-and-cell method is developed in order to simulate nonlinear wave making in the near-field of ships of arbitrary three-dimensional (3D) configuration advancing steadily in deep water. The 3D Navier-Stokes equations are solved by a finite difference scheme under proper boundary conditions. Efforts are particularly focused on the treatment of the boundary conditions on the body surface and free surface which have complicated 3D configurations. An orthogonal cell system with more than 70,000 cells is used for the computation of the waves and flow field of ships. The agreement of computational results with experiment is good, and it promises effectiveness for engineering purposes.     

Layer-by-layer electrodeposition of copper in the presence of o-phenanthroline, caused by a new type of hidden NDR oscillation with the effective electrode surface area as the key variable

Electrochemical deposition of copper (Cu) from aqueous acidic Cu2+ solutions with o-phenanthroline (o-phen) shows both potential and current oscillations, together with a (partially hidden) N-shaped negative differential resistance (N-NDR), indicating that the oscillations are classified into hidden N-NDR (or HN-NDR) oscillations. The color and the surface morphology of Cu deposits oscillate in synchronization with the potential and current oscillations. Microscopic inspection has shown that dense round Cu leaflets, which look gray, grow in the positive side of the potential oscillation or in the high-current state of the current oscillation, whereas thin Cu leaflets, which look black, grow in the opposite-side stages of the potential and current oscillations, thus finally resulting in a layered Cu deposit with the layer thickness of about 5 microm. The appearance of the NDR is explained to be due to adsorption of the reduced form of a [Cu(II)(o-phen)2]2+ complex, which suppresses the Cu electrodeposition. The increase in the effective electrode surface area by growth of thin Cu leaflets, on the other hand, causes a current increase that can hide the NDR. This NDR-hiding mechanism is of a new type and the present oscillation is regarded as a new-type of HN-NDR oscillator.     

Synthesis and fluorescence spectra of oxa[3.n]phenanthrenophanes

[reaction: see text]. Novel photostable oxa[3.n](3,9)- and [3.3](3,10)phenanthrenophanes (n = 3, 4) bearing trimethylene-type linkage(s) were successfully synthesized by the intramolecular acid-catalyzed etherification of the corresponding precursor diols. syn-Oxa[3.3](3,10)phenanthrenophane afforded the most red-shifted excimer fluorescence (lambda(max) = 432 nm) among the phenanthrenophanes so far prepared.     

Control of bacteria adhesion by cell-wall engineering

UDP-MurNAc-pentapeptide derivative bacterial cell-wall precursors were synthesized as effective tools for surface display on living bacteria. Lactobacilli were incubated in the ketone-modified precursor-containing medium, and the ketone moiety was displayed on the bacterial surface through cell-wall biosynthesis. Oligomannose was coupled with the ketone moiety on the bacterial surface via a aminooxyl linker, thereby displaying this oligosaccharide on the surface of the bacteria. The increase in the adhesion of the sugar-displaying bacteria onto a concanavalin A-attached film compared to that of native bacteria was confirmed by microscopic observation and surface plasmon resonance measurement. The incorporation of the artificial cell-wall precursors was enhanced when incubated with fosfomycin, an inhibitor of cell-wall precursor biosynthesis.