Hydrothermal Wave Instability in a High-Aspect-Ratio Liquid Bridge of Pr > 200

The long-duration fluid physics experiments on a thermocapillary-driven flow have been carried out on the Japanese Experiment Module ‘Kibo’ aboard the International Space Station (ISS) since 2008. In these experiments, various aspects of thermocapillary convection in a half-zone (HZ) liquid bridge of high Prandtl number fluid have been examined under the advantages of the long-duration high-quality microgravity environment. In 2010, the authors succeeded to realize nonlinear convective fields in the HZ liquid bridge of rather high aspect ratio. Special attention was paid on to the complex convective fields, especially on the behaviors of the hydrothermal wave (HTW) over the free surface visualized by an infrared camera. In order to evaluate the characteristics of the nonlinear convective behaviors and their transition processes, the authors indicate the images taken by the infrared camera describing the time evolution of HTW, the spatio-temporal diagram, the Fourier analysis, and the pseudo-phase space, reconstructed from the time series of the scalar information of the liquid bridge, that is, surface temperature variation. In this paper, the authors introduce the signature of complex HTW behaviors observed at the long-duration on-orbit experiments, and make comparisons with some previous terrestrial and microgravity experiments.     

Optical Heterodyne Polarimeter for Studying Space-and Time-dependent State of Polarization of Light

Abstract

This paper describes an optical heterodyne polarimeter with a photodetector array by which the space- and time-dependent state of polarization (SOP) of light can be determined. Since no optical components for polarization control are used, the time response of the polarimeter is free from such components, but is basically limited to the frequency bandwidth of the photodetector array used. The signal and local oscillator beams are coherently photomixed to generate a beat photocurrent at every pixel of the photodetector array. The orthogonal linearly polarized two-frequency components of the local oscillator beam are superimposed with their respective counterpart orthogonally decomposed components of the elliptically polarized signal beam. The generated beat-photocurrent offers the significant physical parameters required for the determination of the space- and time-dependent SOP. The performance principle of the polarimeter is explained and confirmed experimentally.     

Catalytic azide reduction in biological environments

In the quest for the identification of catalytic transformations to be used in chemical biology and medicinal chemistry, we identified iron(III) meso-tetraarylporphines as efficient catalysts for the reduction of aromatic azides to their amines. The reaction uses thiols as reducing agents and tolerates water, air, and other biological components. A caged fluorophore was employed to demonstrate that the reduction can be performed even in living mammalian cells. However, in vivo experiments in nematodes (Caenorhabditis elegans) and zebrafish (Danio rerio) revealed a limitation to this method: the metabolic reduction of aromatic azides.     

Improvement of 2-mercaptoimidazoline analysis in rubber products containing chlorine

An improved analysis method for 2-mercaptoimidazoline in rubber products containing chlorine was developed. 2-Mercaptoimidazoline (20 μg/mL) is detected by means of TLC with two developing solvents in the official method. But, this method is not quantitative. Instead, we employed HPLC using water-methanol (9 : 1) as the mobile phase. This procedure decreased interfering peaks, and the quantitation limit was 2 μg/mL of standard solution. 2-Mercaptoimidazoline was confirmed by GC-MS (5 μg/mL) and LC/MS (1 μg/mL) in the scan mode. For preparation of test solution, a soaking extraction method, in which 20 mL of methanol was added to the sample and allowed to stand overnight at about 40°C, was used. This gave similar values to the Soxhlet extraction method (official method) and was more convenient. The results indicate that our procedure is suitable for analysis of 2-mercaptoimidazoline. When 2-mercaptoimidazoline is detected, it is confirmed by either GC/MS or LC/MS.     

Selective preparation of zero- and one-dimensional gold nanostructures in a TiO<Subscript>2</Subscript> nanocrystal-containing photoactive mesoporous template

Nanocrystallized SiO₂-TiO₂ with tubular mesopores was prepared via the sol-gel technique. Gold was deposited in the tubular mesopores of the nanocrystallized SiO₂-TiO₂. The shape of the gold was varied from one-dimensional [1-D] to zero-dimensional [0-D] nanostructures by an increase in TiO₂ content and ultraviolet [UV] irradiation during gold deposition. 1-D gold nanostructures [GNSs] were mainly obtained in the mesopores when a small amount of TiO₂-containing mesoporous SiO₂-TiO₂ was used as a template, whereas the use of a template containing a large amount of TiO₂ led to the formation of shorter 1-D or 0-D GNSs. UV irradiation also resulted in the formation of 0-D GNSs.     

Superplasticity in a bulk amorphous Pd-40Ni-20P alloy:a compression study

Compressive deformation behavior of a cast Pd₄₀Ni₄₀P₂₀ bulk metallic glass in the supercooled liquid region (589–670 K) was investigated at strain rates ranging from 10⁻⁴ to 10⁻² s⁻¹. The material exhibited excellent mechanical formability in the supercooled liquid region. However, in contrast to a Newtonian behavior generally observed in oxide glasses, the present alloy also showed a non-Newtonian behavior, depending upon the temperature and applied strain rate. Specifically, the alloy is like a Newtonian fluid at high temperatures, but becomes non-Newtonian at low temperatures and high strain rates. Structures of the amorphous material, both before and after deformation, were examined using X-ray diffraction and high-resolution transmission electron microscopy. The non-Newtonian behavior is proposed to be associated with the glass instability during deformation.     

Aerial flashover caused by surface flashover generated from microscopic pores of insulating solid

This paper studies the possibility of an aerial flashover between a coil conductor and the casing in a rotating machine at voltages below Paschen's voltage even when sufficient insulation distance has been provided. It might be considered that partial surface flashover generated from microscopic pores of a solid insulator generates the aerial flashover. In this study, the flashover voltage was measured using a cable which had simulated microscopic pores to confirm the above reasoning. When a potential gradient existed on the surface of the insulating solid, the flashover voltage decreased from that in the absence of a potential gradient. It also became clear that the aerial flashover probability depends mainly on the energy of the surface flashover rather than the energy of the main aerial flashover. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 16–23, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21221     

Model-based reconstruction integrated with fluence compensation for photoacoustic tomography

Photoacoustic (PA) tomography (PAT) is a rapidly developing imaging modality that can provide high contrast and spatial-resolution images of light-absorption distribution in tissue. However, reconstruction of the absorption distribution is affected by nonuniform light fluence. This paper introduces a reconstruction method for reducing amplification of noise and artifacts in low-fluence regions. In this method, fluence compensation is integrated into model-based reconstruction, and the absorption distribution is iteratively updated. At each iteration, we calculate the residual between detected PA signals and the signals computed by a forward model using the initial pressure, which is the product of estimated voxel value and light fluence. By minimizing the residual, the reconstructed values converge to the true absorption distribution. In addition, we developed a matrix compression method for reducing memory requirements and accelerating reconstruction speed. The results of simulation and phantom experiments indicate that the proposed method provides a better contrast-to-noise ratio (CNR) in low-fluence regions. We expect that the capability of increasing imaging depth will broaden the clinical applications of PAT.     

A Remarkable Titanium‐Catalyzed Asymmetric Strecker Reaction using Hydrogen Cyanide at Room Temperature

Close to perfect enantioselectivity (up to 98% ee) is obtained for the formation of amino nitriles using hydrogen cyanide (HCN) as the cyanide source at room temperature for the first time. In an operationally simple process, the catalyst generated from a partially hydrolyzed titanium alkoxide (PHTA) and (S)‐N‐salicyl‐β‐amino alcohol ligand, catalyzes the cyanation of imines in a short reaction time.     

Examination of original plant of mulberry bark extract, a natural food additive, based on composition of the constituents

Mulberry bark extract, a natural food additive, is described as a "root bark extract from Morus bombycis" (Japanese name: Yamaguwa) in the Notice (1996) relating to existing food additives used in Japan. The results of analyses by LC/UV and LC/MS suggested that the Mulberry bark extract products that were tested were actually made from the root bark of Morus alba (Japanese name: Maguwa) or its hybrid species, because the compositions of the constituents in the products are more similar to those in the extracts of the dried root bark of M. alba and hybrid species that are cultivated in Japan than to those of M. bombycis. In addition, the constituents of the food additive products were different from those of the natural medicine Mori Cortex products ('Souhakuhi' in Japanese) made from the root bark of mulberry grown in China, and which is described as being derived from M. alba in the Japanese pharmacopoeia. These results were also corroborated by Principal Component Analysis using the peak areas of LC/MS analysis as explanatory variables. After this study, it was decided that Mulberry bark extract is one of the existing food additives that should be excluded from the list this year in Japan.