Highly Diastereoselective Reduction of Bicyclic and Steroidal Conjugated Enones with Dibal in THF-DME

Reduction of four bicyclic and two steroidal conjugated enones employing diisobutylaluminum hydride (DIBAL) in tetrahydrofuran (THF)/1,2-dimethoxyethane (DME) led to allylic alcohols with high levels of diastereo-selectivity.     

RING-TRANSFORMATION FROM ISOTHIAZOLE TO 1,2,4-THIADIAZOLE - POSSIBLE INTERMEDIACY OF π-SULFURANE

Abstract

5-Amino-3-methyl- and 5-amino-3-phenylisothiazoles (3a and 3b) afforded 1 : 1 adducts with aromatic nitriles and imidates. On the basis of their spectral data and the structure of hydrolysis products, the adducts were identified as 3-substituted 5-(2-aminovinyl)-1,2,4-thiadiazole derivatives (2a-g), where ring transformation took place from isothiazole to 1,2,4-thiadiazole.     

Precision measurement of laser RF double resonance spectra with an effective compensation of residual magnetic field

Ultra Fast Timing has been applied at the IGISOL facility since more than a decade ago with the aim to systematically study nano- and subnanosecond lifetimes in the neutron-rich nuclei from the A~110 region. Over this period two generations of crystals and photomultipliers have been introduced, which allowed to study more complex level schemes populated in β decay. The IGISOL facility provides unique capabilities to study the A~110 region not matched elsewhere in the world.     

Normal shock wave oscillations in supersonic diffusers

The present paper describes experimental investigations for shock oscillations caused by normal shock wave/turbulent boundary layer interaction in a supersonic diffuser. An array of wall-mounted transducers and especially a line image sensor for the nonintrusive detection of shock displacements were employed to investigate the interactions at low supersonic speeds. The line image sensor was collimated with a conventional schlieren optical system and was a good indicative of capturing the shock oscillating motions in the present configuration. This study shows that the amplitude of the shock motions increases with approaching flow Mach number, and the cause of oscillation of the shock wave can, however, be independent of the Mach number. In addition, the present system employed to determine the shock wave positions and displacements can be effectively applied to a variety of practical problems.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Experimental analysis of vertical soil reaction and soil stress distribution under off-road tires

In this study, the vertical soil reaction acting on a driven wheel was measured by strain gages bonded to the left rear axle of a 2WD tractor driven under steady-state condition on different soil surfaces, tractor operations, and combinations of static wheel load and tire inflation pressure. In addition, the measurements of radial and tangential stresses on the soil–tire interface were made simultaneously at lug’s face and leading side near the centerline of the left rear tire using spot pressure sensors. The experimental results indicate that the proposed method of vertical soil reaction measurement is capable of monitoring the real-time vertical wheel load of a moving vehicle and provides a tool for further studies on vehicle dynamics and dynamic wheel–soil interaction. Furthermore, the measured distributions of soil stresses under tractor tire could provide more real insight into the soil–wheel interactions.     

Development of New Strain Gage for High-Pressure Hydrogen Gas Use

The output changes of two conventional strain gages (Cu–Ni and Ni–Cr) and a newly-selected strain gage for high-pressure hydrogen gas use (Fe–Cr–Al) in 90 MPa hydrogen and nitrogen gases were measured under unloading conditions to find a high-performance strain gage for high-pressure hydrogen gas use. The changes in the outputs of the Cu–Ni and Ni–Cr gages in hydrogen gas were much larger than those in nitrogen gas, and the Fe–Cr–Al gage showed almost the same output changes in both gases. These results imply that the Fe–Cr–Al gage is superior to the others as a strain gage for high-pressure hydrogen gas use. A large amount of hydrogen entered the Cu–Ni and Ni–Cr foils, and the electrical resistances of these foils were significantly changed by hydrogen exposure, whereas almost no hydrogen entered the Fe–Cr–Al foil, and its electrical resistance was not changed. These resistance changes of the foils as a result of hydrogen entry were consistent with the gage output changes in hydrogen gas.     

Pre-edge features of Ti K-edge X-ray absorption near-edge structure for the local structure of sol-gel titanium oxides.

Titanium K-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to examine the local Ti environments in the sol, gel, and xerogels of titanium oxide prepared by a sol-gel method. The xerogels were prepared by heat treatment at 200, 300, 400, 500, and 600 degrees C (denoted xero-200, xero-300, xero-400, xero-500, and xero-600), and the xerogels were doped with Fe(II), Ni(II), and Cu(II) ions (xero-Fe, xero-Ni, and xero-Cu). The local structures of the samples are compared using the pre- and post-edge features of the XANES spectra. Further analysis of the pre-edge features using Gaussian functions provides the energy and height of each peak, and the intensity ratios between peaks. Based on the resulting data, the samples can be classified into three groups: a weak Ti-Ti interaction group, an anatase-like structure group, and an anatase group. The sol, gel, xerogel, and xero-Ni are in the weak Ti-Ti interaction group, and the xero-200, xero-Fe, and xero-Cu are in the anatase-like structure group. The remaining samples are in the anatase group.     

Adsorption behavior of cytochrome c, myoglobin and hemoglobin in a quartz surface probed using slab optical waveguide (SOWG) spectroscopy.

Slab optical waveguide (SOWG) spectroscopy was used to observe the adsorption behavior of three important heme proteins, namely cytochrome c, myoglobin and hemoglobin, in a quartz surface. Using prism-coupled polychromatic visible light propagated into a quartz waveguide by internal total reflection, the real-time monitoring of evanescent wave absorption revealed a strong dependence of the protein-surface interaction on the protein concentration, the solution pH and the ionic strength. For the three proteins studied, the absorbance-bulk concentration ratio was higher at low bulk concentrations, and decreased at higher concentrations. For cytochrome c and myoglobin, the absorbance approached a limiting value, but buffered hemoglobin surprisingly did not show any indication of forming a signal plateau. Moreover, the slow introduction of protein into the solution lessened the total adsorbed amount per unit area. These observations suggested a possible conformational transition of the protein molecules at the quartz surface after adsorption. For a bulkier protein, hemoglobin, adsorption onto the quartz surface was enhanced in the presence of a phosphate buffer, while the opposite effect was observed for the smaller cytochrome c and myoglobin molecules. The results of pH studies concurred with the electrostatic interactions predicted from the isoelectric data of proteins and the quartz surface.