Photoreaction of Benzenecarbothioamide with Aldehydes. Facile Synthesis of Tetracyclic Imidazoles.1)

Photoreaction of benzenecarbothioamide with various aldehydes in benzene solution gave 2-substituted phenanthroimidazoles.     

On the Curvature of the Free Boundary for the Obstacle Problem in Two Dimensions

We give a new proof of the fact that the free boundary for the obstacle problem in two dimensions satisfies a natural and sharp inner ball condition.     

Continuous fabrication of Co-Cr perpendicular magnetic recording tape

To achieve high-throughput fabrication of Co-Cr/Ni-Fe double-layer perpendicular media, the optimum conditions for continuous preparation and construction of a new dc magnetron sputtering target have been investigated with respect to the aperture shield mask position and the magnetic circuit. The perpendicular magnetic tape media fabricated in a roll-coater equipped with the improved target showed high reproduced voltage at high densities.     

Critical current density of rolled silver-sheathed Bi(2223) tapes

Silver-sheathed (Bi,Pb)₂Sr₂Ca₂Cu₃O_x (Bi(2223)) tapes were fabricated by the “oxide-powder-in-tube” technique. After the tapes were shaped and sintered, an additional cold rolling and a re-sintering were applied in order to enhance the critical current density J_c. The influence of the additional rolling conditions (roll diameter, number of passes, lubrication) on the J_c (77 K, 0 T) was made clear. The influence of the sintering conditions (temperature, heating rate) on J_c was also investigated. As for the rolling conditions, a small redundant shear deformation or a small contact angle leads to a good grain alignment, texturing, and a higher J_c value. As for the temperature of the first sintering, 1113 K is superior to 1118 K because of the volume fraction of the Bi(2223) phase.     

Drag prediction,decomposition and visualization in unstructured mesh CFD solver of TAS‐code

The accuracy of drag prediction in unstructured mesh CFD solver of TAS (Tohoku University Aerodynamic Simulation) code is discussed using a drag decomposition method. The drag decomposition method decomposes total drag into wave, profile, induced and spurious drag components, the latter resulting from numerical diffusion and errors. The mesh resolution analysis is conducted by the drag decomposition method. The effect of an advanced unstructured mesh scheme of U‐MUSCL reconstruction is also investigated by the drag decomposition method. The computational results show that the drag decomposition method reliably predicts drag and is capable of meaningful drag decomposition. The accuracy of drag prediction is increased by eliminating the spurious drag component from the total drag. It is also confirmed that the physical drag components are almost independent of the mesh resolution and scheme modification. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of an in vitro Batch-type Closed Gas Exposure Device with an Alveolar Epithelial Cell Line, A549, for Toxicity Evaluations of Gaseous Compounds

To simply evaluate toxicity for various types of exhaust-gas samples collected in various locations, we developed a small-scale (150 mL) batch-type completely closed gas exposure device incorporated with an air-liquid interface culture of a human alveolar epithelial cell line, A549. On the basis of cell viability tests using an acid phosphatase assay after 48 h of gas exposure, the developed device was able to measure clear dose-response relationships for volatile organic and inorganic compounds, such as benzene, trichloroethylene (TCE), acetone, SO(2) and NO(2) gases, but not CO gas. Although the 50% effective concentration values in the device were much higher than 50% lethal concentration values reported in animal experiments, the tendency of the toxic intensity observed in the former was roughly consistent with that of the acute toxicity in the latter. We further applied the device to evaluate the toxicity of cigarette smoke as an example of actual environmental gases, and successfully measured acute cell death from the gas after 48 h of exposure. The present small device is expected to be one of good tools not only in simultaneously assessing various gaseous chemicals or samples, but also in studying acute toxicity expression mechanisms in human lung epithelia.     

Flow injection analysis for oxidation state speciation of vanadium(IV) and vanadium(V) in natural water.

A sensitive and simultaneous spectrophotometric flow injection method for the determination of vanadium(IV) and vanadium(V) is proposed. The method is based on the effect of ligands such as 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) and diphosphate on the conditional redox potential of iron(III)/iron(II) system. A four-channel flow system is assembled. In this flow system, diluted hydrochloric acid (1.0 x 10(-2) mol dm(-3)) as a carrier for standard/sample, acetate buffer (pH 5.5) as a carrier for diphosphate solution, an equimolar mixed solution of iron(III) and iron(II) and a TPTZ solution are delivered, so that the baseline absorbance can be established by forming a constant amount of iron(II)-TPTZ complex (lambda(max) = 593 nm). Vanadium(IV) and/or vanadium(V) (400 microL) and diphosphate (200 microL) solutions are simultaneously introduced into the flow system; in this system the diphosphate solution passes through a delay coil. The potential of the iron(III)/iron(II) system increases in the presence of TPTZ, and therefore vanadium(IV) is easily oxidized by iron(III) to vanadium(V) to produce an iron(II)-TPTZ complex (a positive peak for vanadium(IV) appears). On the other hand, the potential of the redox system decreases in the presence of diphosphate, so that vanadium(V) can be easily reduced by iron(II) to vanadium(IV). In this case, the amount of iron(II) decreases according to the amount of vanadium(V). As a result, the produced iron(II)-TPTZ complex decreases (a negative peak for vanadium(V) appears). In this manner, two peaks for vanadium(IV) and vanadium(V) can be alternately obtained. The limits of detection (S/N = 3) are 1.98 x 10(-7) and 2.97 x 10(-7) mol dm(-3) for vanadium(IV) and vanadium(V), respectively. The method is applied to the simultaneous determination of vanadium(IV) and vanadium(V) in commercial bottled mineral water samples.     

Affine R-Matrix and the Generalized Elliptic Ruijsenaars Models

Commutative elliptic difference operators associated with the affine root systems are constructed in terms of affine R-matrices. These operators describe the Ruijsenaars models with elliptic potentials and reduce to the Macdonald operators in the trigonometric limit.