SEM and TEM characterization of magnesium hydride catalyzed with Ni nano-particle or Nb2O5

The microstructures of MgH₂ catalyzed with Ni nano-particle or Nb₂O₅ mesoporous powders are examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. For MgH₂ catalyzed with Ni, the Ni particles with the diameter smaller than 1 μm were detected on the MgH₂ particles with the diameter smaller than 5 μm by the back scattering electron (BSE) microscopy. In details, the TEM micrograph indicates that the Ni particles distribute 20 nm in diameter on MgH₂ uniformly, which was the same size as the additive doped in MgH₂ before milling. On the other hand, for MgH₂ catalyzed with Nb₂O₅, the additive particles could not be found anywhere in the BSE image. Even in the TEM micrograph by much larger magnification than the SEM micrograph, the particles corresponding to the additive cannot be observed at all. Furthermore, an energy dispersive X-ray (EDX) analysis in spots with a diameter of 20 nm indicated that the existing ratio of Mg to Nb was evaluated to 98:2, being the same as the starting ratio before milling. Therefore, the metal oxide Nb₂O₅ becomes extremely small particle that could not be observed by the present work after milling compared to metal Ni^nano.     

Tensile Fracture Behavior and Strength of Surface-Modified SiTiCO Fiber SiC-Matrix Minicomposites Fabricated by the PIP Process

The effect of surface-modified SiTiCO (Tyranno®) fiber on the tensile behavior of SiC-matrix minicomposites has been examined. Standard SiTiCO fiber and two kinds of surface-modified fibers were used and the composites were fabricated by a polymer infiltration pyrolysis process. The strengths of the surface-modified-fiber-reinforced minicomposites were significantly improved compared to that of the standard fiber minicomposite. The scattering of tensile strength also decreased with the use of surface-modified fibers. The results demonstrate the achievement of SiTiCO-fiber-reinforced SiC-matrix composite by modifying the surface chemistry of the fiber.     

Nb/Nb5Si3原位复合材料的开发研究

Nb/Nb5Si3原位复合材料极具替代现有镍基超合金作为未来飞行器发动机超高温部件材料的潜力。本研究采用反应热压烧结、反应放电等离子烧结等粉末冶金技术及氩弧熔炼技术制备了多种成分的Nb/Nb5Si3原位复合材料 ,并对其组织形态、高温强度及室温塑性进行了考察。结果表明 :两种粉末法制得的复合材料具有类似的显微组织 ,即Nb固溶体与硅化物两相均呈现等轴状晶粒分布。合金元素Mo、W对烧结组织形貌无明显影响 ,但可改变凝固过程Nb5Si3的析出机制 ,从而优化氩弧熔炼合金的组织形态。粉末合金保持较高高温强度 ,并具有较高室温塑性。熔炼材料的高温强度远高于粉末合金 ,其中Nb 16Si 10Mo 15W合金 16 0 0℃时的压缩屈服强度高达50 0MPa。     

Microbial participation in iodine volatilization from soils

The roles of microorganisms in iodine volatilization from soils were studied. Soils were incubated with iodide ion (I-), and volatile organic iodine species were determined with a gas chromatograph. Iodine was emitted mainly as methyl iodide (CH3I), and CH3I emission was sometimes enhanced by the addition of glucose. Soils were then incubated with a radioactive iodine tracer (125I), and radioiodine emitted from soils was determined. The emission of iodine was enhanced in the presence of yeast extract but was inhibited by autoclaving of soils. The addition of streptomycin and tetracycline, antibiotics that inhibit bacterial growth, strongly inhibited iodine emission, while a fungal inhibitor cycloheximide caused little effect. Forty bacterial strains were randomly isolated from soils, and their capacities for volatilizing iodine were determined. Among these, 14 strains volatilized significant amounts of iodine when they were cultivated with iodide ion. Phylogenetic analysis based on 16S ribosomal DNA sequences showed thatthese bacteria are widely distributed through the bacterial domain. Our results suggest that iodine in soils is methylated and volatilized as CH3I by the action of soil bacteria and that iodine-volatilizing bacteria are ubiquitous in soil environments. The pathway of iodine volatilization by soil bacteria should be important for understanding the biogeochemical cycling of iodine as well as for the assessment of long-lived radioactive iodine (129I) in the environment.     

Progress in development and design of the neutral beam injector for JT-60SA

Neutral beam (NB) injectors for JT-60 Super Advanced (JT-60SA) have been designed and developed. Twelve positive-ion-based and one negative-ion-based NB injectors are allocated to inject 30 MW D⁰ beams in total for 100 s. Each of the positive-ion-based NB injector is designed to inject 1.7 MW for 100 s at 85 keV. A part of the power supplies and magnetic shield utilized on JT-60U are upgraded and reused on JT-60SA. To realize the negative-ion-based NB injector for JT-60SA where the injection of 500 keV, 10 MW D⁰ beams for 100 s is required, R&Ds of the negative ion source have been carried out. High-energy negative ion beams of 490–500 keV have been successfully produced at a beam current of 1–2.8 A through 20% of the total ion extraction area, by improving voltage holding capability of the ion source. This is the first demonstration of a high-current negative ion acceleration of >1 A to 500 keV. The design of the power supplies and the beamline is also in progress. The procurement of the acceleration power supply starts in 2010.     

Integration of single-electron transistors using field-emission-induced electromigration

A novel technique for the integration of planar-type single-electron transistors (SETs) composed of nanogaps is presented. This technique is based on the electromigration procedure, which is caused by a field emission current. The technique is called "activation." By applying the activation to the nanogaps, SETs can be easily obtained. Furthermore, the charging energy of the SETs can be controlled by adjusting the magnitude of the applied current during the activation process. The integration of two SETs was achieved by passing a field emission current through two series-connected initial nanogaps. The current-voltage (I(D)-V(D)) curves of the simultaneously activated devices exhibited clear electrical-current suppression at a low-bias voltage at 16 K, which is known as the Coulomb blockade. The Coulomb blockade voltage of each device was also obviously modulated by the gate voltage. In addition, the two SETs, which were integrated by the activation procedure, exhibited similar electrical properties, and their charging energy decreased uniformly with increasing the preset current during the activation. These results indicate that the activation procedure allows the simple and easy integration of planar-type SETs.     

Simultaneous determination of N-methylcarbamate and urea pesticides in agricultural products by LC/MS

A simultaneous determination method of 7 N-methylcarbamate and 7 urea pesticides in agricultural products by liquid chromatography/mass spectrometry (LC/MS) has been developed. Under reversed-phase liquid chromatographic conditions, 14 pesticides were analyzed using electrospray ionization (ESI) with simultaneous acquisition of positive ions and negative ions. Fourteen pesticides were extracted with acetone, 10% NaCl solution was added, and the pesticides were re-extracted with dichloromethane. The extract was concentrated under reduced pressure, and dissolved in methanol. The detection limits of 14 pesticides ranged from 0.0012 to 0.0056 microgram/g. The recoveries of pesticides were from 36.5 to 112.5% [RSD (n = 3) ranged from 0.5 to 48.1%] for 4 agricultural products.     

Evaluation of Potential Anti-Hepatitis A Virus 3C Protease Inhibitors Using Molecular Docking

Hepatitis A virus (HAV) infection is a major cause of acute hepatitis worldwide and occasionally causes acute liver failure and can lead to death in the absence of liver transplantation. Although HAV vaccination is available, the prevalence of HAV vaccination is not adequate in some countries. Additionally, the improvements in public health reduced our immunity to HAV infection. These situations motivated us to develop potentially new anti-HAV therapeutic options. We carried out the in silico screening of anti-HAV compounds targeting the 3C protease enzyme using the Schrodinger Modeling software from the antiviral library of 25,000 compounds to evaluate anti-HAV 3C protease inhibitors. Additionally, in vitro studies were introduced to examine the inhibitory effects of HAV subgenomic replicon replication and HAV HA11-1299 genotype IIIA replication in hepatoma cell lines using luciferase assays and real-time RT-PCR. In silico studies enabled us to identify five lead candidates with optimal binding interactions in the active site of the target HAV 3C protease using the Schrodinger Glide program. In vitro studies substantiated our hypothesis from in silico findings. One of our lead compounds, Z10325150, showed 47% inhibitory effects on HAV genotype IB subgenomic replicon replication and 36% inhibitory effects on HAV genotype IIIA HA11-1299 replication in human hepatoma cell lines, with no cytotoxic effects at concentrations of 100 μg/mL. The effects of the combination therapy of Z10325150 and RNA-dependent RNA polymerase inhibitor, favipiravir on HAV genotype IB HM175 subgenomic replicon replication and HAV genotype IIIA HA11-1299 replication showed 64% and 48% inhibitory effects of HAV subgenomic replicon and HAV replication, respectively. We identified the HAV 3C protease inhibitor Z10325150 through in silico screening and confirmed the HAV replication inhibitory activity in human hepatocytes. Z10325150 may offer the potential for a useful HAV inhibitor in severe hepatitis A.     

Improvement of Interface in SiC Particle-Reinforced Al-Li Composite by Sol-Gel Coating Technique

This paper describes a study to investigate an improvement of the interface in SiC particle-reinforced Al-Li composite by coating the SiC particle with metallic oxide film. A coating method utilizing a sol-gel technique produced fine SiC powders covered with SiO₂, TiO₂, or ZrO₂ metallic oxide film. The film thickness was not affected by the hydrolysis time of the sol solution under a dry argon atmosphere. The average thickness of the SiO₂, TiO₂ and ZrO₂ films was about 10 nm, 8 nm and 27 nm, respectively. In metallic oxide coated SiC particle-reinforced Al-Li composite, TEM observation showed that the coating film was not damaged by fabrication processing, and that the formation of Al⁴C³ at the interface between the matrix and reinforcement was controlled by the coating film. The tensile strength and elongation of the extruded TiO₂, coated sample increased by 12% and 24%, respectively, compared with the non-coated sample.     

Alloy design for Al addition on microstructure and mechanical properties of Ni3(Si,Ti) alloy

The effect of Al addition on the microstructure and tensile properties of Ni₃(Si,Ti) alloys with an L1₂ ordered structure, which were fabricated through thermomechanical processing from arc-melted ingots, was investigated. Al was added to a Ni₃(Si,Ti) alloy by using two methods such that Al substituted for (1) only Ti and (2) both Ni and Ti along a Ni₃(Si,Ti)-Ni₃Al pseudo-binary line. In the case of the alloys prepared by the former method, the addition of more than 4 at.% Al resulted in a two-phase microstructure consisting of disordered fcc Ni solid solution dispersions in the L1₂ matrix, while in the case of the alloys prepared by the latter method, the addition of 4 at.% Al retained the L1₂ single-phase microstructure. In the case of the 4 at.% Al-added alloys, the room-temperature tensile properties were similar and independent of the alloying methods, whereas the high-temperature yield stress was higher in the alloys prepared by the latter method than in the case of the alloys prepared by the former method. These results suggest that a single-phase microstructure consisting of an entire L1₂ structure is favorable for obtaining high-temperature tensile properties.