Characterization of Catalase from Psychrotolerant Psychrobacter piscatorii T-3 Exhibiting High Catalase Activity

A psychrotolerant bacterium, strain T-3 (identified as Psychrobacter piscatorii), that exhibited an extraordinarily high catalase activity was isolated from the drain pool of a plant that uses H(2)O(2) as a bleaching agent. Its cell extract exhibited a catalase activity (19,700 U·mg protein(-1)) that was higher than that of Micrococcus luteus used for industrial catalase production. Catalase was approximately 10% of the total proteins in the cell extract of the strain. The catalase (PktA) was purified homogeneously by only two purification steps, anion exchange and hydrophobic chromatographies. The purified catalase exhibited higher catalytic efficiency and higher sensitivity of activity at high temperatures than M. luteus catalase. The deduced amino acid sequence showed the highest homology with catalase of Psycrobacter cryohalolentis, a psychrotolelant bacterium obtained from Siberian permafrost. These findings suggest that the characteristics of the PktA molecule reflected the taxonomic relationship of the isolate as well as the environmental conditions (low temperatures and high concentrations of H(2)O(2)) under which the bacterium survives. Strain T-3 efficiently produces a catalase (PktA) at a higher rate than Exiguobacterium oxidotolerans, which produces a very strong activity of catalase (EktA) at a moderate rate, in order to adapt to high concentration of H(2)O(2).     

Suppression of hydrogen-induced blisters in SK4 carbon steel alloy by friction stir processing

The feasibility of using friction stir-processing technique as a microstructural refining method for preventing hydrogen-induced blisters of SK4 carbon steel alloy containing microstructure of hard cementite particles in a ductile ferrite matrix was examined. Amount and size of hydrogen-induced blisters decreased in the stirred layers with increasing rotation speed and completely disappeared when rotation speed attained 400 rpm because of the formation of a hard and fine microstructure consisting of pearlite, martensite, and retained austenite instead of that containing hard spheroidized cementite particles in a soft ferrite matrix. Interfaces between ferrite matrix and cementite particles were the preferential sites for the hydrogen blisters initiation.     

Wetting of MgO and α-Al2O3 by molten Mg: a model of droplet with high vapor pressure

The wetting of MgO and α-Al₂O₃ polycrystalline plates by molten Mg in purified argon was studied between 973 and 1273?K using an improved sessile drop method. The MgO/Mg system is basically non-reactive while Al₂O₃/Mg is reactive. The common features in the non-reactive and reactive systems are the high tendency for oxidation and the high evaporation rate of Mg. It is shown that wetting kinetics in both systems is governed by the evaporation and pinning phenomenon leading to contact angle versus time curves passing through a minimum: the apparent contact angle first decreases and then increases. The intrinsic contact angle should be estimated using the initial value (advancing contact angle) and the maximum value just before the disappearance of the droplet caused by Mg evaporation (receding contact angle).     

Deformation Mechanism in the Crack-Tip Region of Fine-Grained Magnesium Alloy

The deformation mechanism in the crack-tip region of a fine-grained Mg-2.4 at. pct Zn binary alloy was investigated by focused ion beam (FIB) and transmission electron microscopy (TEM) observation and finite element analysis (FEA) at the beginning of the fracture toughness test. The deformed microstructure observations showed the formation of subgrains instead of deformation twins in the fracture toughness tested sample, which was performed at a conventional crosshead speed of 1 mm/min. By preventing the formation of deformation twins at the beginning of the test, the crack tip of the fine-grained magnesium alloys became blunted, and thus, the alloys obtained high fracture toughness. Finite element results showed that the temperature increased 50 to 110 K, and the strain rate became two orders of magnitude higher; however, this temperature increment was not sufficient to form high-angle grain boundaries, i.e., a complete occurrence of dynamic recrystallization. On the other hand, the deformed microstructure observations in the sample, which was tested at a crosshead speed of 50 mm/min, showed the formation of nano-order {10-12} deformation twins and subgrains. The formation of deformation twins was caused, in part, by the severe strain from the operation of a high strain rate in the crack-tip region.     

The use of intravenous immunoglobulin in Miller Fisher syndrome

We report a patient with Miller Fisher syndrome who was treated with an intravenous high-dose of immunoglobulin. This syndrome is considered to be a benign variety of acute inflammatory demyelinating polyneuropathy (Guillain-Barré syndrome). However, there have been several reports of the need for ventilatory support and a few cases have had a fatal outcome. We observed a case of progressive Miller Fisher syndrome in a 3-year-old boy. Following 2 episodes of apnea lasting about 50 s each, he was treated with intravenous immunoglobulin (400 mg/kg/day) for 5 consecutive days. His respiratory state, general muscle strength, truncal ataxia and emotional state improved remarkably after this therapy.     

Noninvasive subsurface analysis using multiple miniaturized Raman probes, part I: basic study of thin-layered transparent models of biomedical tissues

This study describes a basic theory for reconstructing pure Raman signals of materials composing a multilayer sample from Raman spectra obtained using two types of miniaturized Raman probes. An illustrative example is demonstrated using a multilayer system of samples composed of the transparent plastics polymethylmethacrylate (PMMA) and polyethylene (PE) as a model of thin-layered biomedical tissues. When the same region of an object is measured using Raman probes with different focal properties, the Raman spectra provide different depth profile information depending on the level of light penetration. Thus, a detailed comparison of the spectra can provide an interesting opportunity to probe the differences between the layers. A simple analytic form is presented for reconstructing the pure Raman spectra of the embedded layer. The method applies an understanding of the Raman sampling volume in layered transparent materials to the interpretation of Raman spectra experimentally measured by multiple probes. The basic theory described here is necessary for the expansion of the technique to turbid media, such as biological samples, where light-scattering effects must be considered. The potential applications of the proposed method include material and catalyst subsurface probing through different embedded materials, such as assessment of silicon wafers, effective noninvasive screening for catalyst synthesis, and biomedical tissue research.     

Communication Interface with Eye-Gaze and Head Gesture Using Successive DP Matching and Fuzzy Inference

This paper proposes a communication interface with eye-gaze and head gesture. Visual sensorimotor integration with eye-head cooperation is considered, especially head gesture accompanied with vestibulo-ocular reflex is used for selecting object in the screen. Eye-mark recorder and motion tracking system were used to tracking eye movement and head movement, respectively. Nonverbal response animation with eye contact was introduced in the interaction system. In identifying the head gesture, we adopted a modified dynamic programming matching method and fuzzy inference.     

Orbital Magnetism in Confined Two-Dimensional Systems

The way how the Landau diamagnetism emerges in finite two-dimensional systems, disc and ring, has been clarified by examining both the field dependences of the magnetization and the spatial distribution of the persistent currents induced by the magnetic field.     

High temperature water–gas shift reaction over hollow Ni–Fe–Al oxide nano-composite catalysts prepared by the solution-spray plasma technique

The effect of Fe content in Ni–Fe–Al oxide nano-composites prepared by the solution-spray plasma technique on their catalytic activity for the high temperature water–gas shift reaction was investigated. The composites showed a hollow sphere structure, with highly dispersed Fe–Ni particles supported on the outer surface of the spheres. When the water–gas shift reaction was performed over an Ni–Al oxide composite catalyst without Fe, undesired CO methanation took place predominantly compared to the water–gas shift reaction, and significant amounts of hydrogen were consumed. When appropriate amounts of Fe were added to the Ni–Al oxide composite catalyst during the plasma process, methanation was suppressed remarkably, without serious loss of activity for the water–gas shift reaction. The catalyst was characterized by STEM, XRD and H₂ chemisorption measurements.     

H2O-tolerant monolithic catalysts for preferential oxidation of carbon monoxide in the presence of hydrogen

Pt–Fe/mordenite (4 wt% Pt–0.5 wt% Fe) powder catalysts were wash-coated onto ceramic straight-channel monoliths by using silica- and/or alumina-sol as a binder, and were evaluated for the preferential oxidation of carbon monoxide (PROX) in a hydrogen-rich gas. In a synthetic reformate gas (1% CO, 1% O₂, 5% H₂O, 20% CO₂, and balance H₂), the CO concentration was reduced to less than 20 ppm at temperatures ranging from 100 to 130 °C. After a certain period of the PROX reaction, condensation of H₂O in the pores of the mordenite-support occurred over the monolithic catalyst, which was wash-coated with alumina-sol, in the lower temperature range (100–120 °C), resulting in a rapid increase in CO concentration. The monolithic catalyst wash-coated with silica-sol, however, showed an excellent tolerance against H₂O condensation and offered a stable catalytic performance, maintaining a CO concentration of ca. 20 ppm for 200 h. The H₂O-tolerant characteristic was attributed to the relatively small adsorption amount of H₂O over the silica-modified monolithic catalyst.