Microstructure and bonding properties of diffusion–bonded composite comprising an Fe–Al alloy and carbon steel

This study discusses microstructure evolution, diffusion behavior and bonding strength of a couple comprising of an iron aluminium alloy (Fe–Al) and high carbon-steel (FeCMn) during diffusion bonding. A columnar microstructure evolves from the joint interface toward FeCMn and disappears in couples bonded for a long period. Aluminium diffusion from Fe–Al to FeCMn and columnar microstructure evolution are retarded as compared to a couple consisting of an Fe–Al and ferrite steel. The carbide in the FeCMn impedes the aluminium diffusion and retards the columnar grain evolution. When the carbide is dissolved in the ferrite during the aluminium diffsuion from Fe–Al, coarse grains evolve due to the coalescence of the columnar grains and a high-bonding strength is obtained. The hardness variation is minimum in the FeCMn of a couple bonded for a short period, which is explained by the microstructural changes in the columnar grain evolution and carbide dissociation.     

Cathodic performance of some sulfide electrodes in liquid ammonia

The cathodic performance of some metal sulfide electrodes has been investigated in a liquid ammonia solution of NH₄SCN. In dry liquid ammonia, the     

Hydration of ethene over W–P mixed metal oxide catalysts

W–P mixed metal oxide catalysts are active and selective for the gas-phase hydration of ethene to ethanol. The activity and selectivity of this catalytic reaction depend on the W/P atomic ratio. However, ethene conversion slightly decreases at higher W/(W + P) atomic ratio. The selectivity for ethanol increases with the W/P atomic ratio and reaches the highest value (92%) at W_0.81P_0.19O_x. The W_0.81P_0.19O_x catalyst is less active than the conventional H₃PO₄/SiO₂ catalyst, but the activity is maintained for a long time without the supply of any catalyst components. The reaction temperature does not affect substantially the rate of ethene hydration over the W_0.81P_0.19O_x catalyst. The H₂O/ethene molar ratio of 0.4 is the most appropriate for both reaction rate and selectivity. The active species of W–P mixed metal oxide are amorphous. But there is Keggin structure of W–P oxide species (PW₁₂O₄₀ ³⁻) in the presence of steam. And the species are the active sites for the hydration of ethene, confirmed by in situ Raman spectroscopy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Magnetoresistance Properties of Planar-Type Tunnel Junctions With Ferromagnetic Nanogap System Fabricated by Electromigration Method

We report electromigration techniques for the fabrication of planar-type tunnel junctions with ferromagnetic nanogap system. In these techniques, by monitoring the current passing through the devices, we are easily able to obtain the planar-type Ni-Vacuum-Ni tunnel junctions. In this paper, magnetoresistance (MR) properties of the planar-type Ni-based tunnel junctions formed by stepwise feedback-controlled electromigration (SFCE) and field-emission-induced electromigration (activation) are studied. We performed the SFCE method for Ni nanoconstrictions connecting asymmetrical butterfly-shape electrodes. Furthermore, the activation technique was applied to Ni nanogaps with separations of 15-45 nm. MR ratio of the devices formed by the SFCE exhibited approximately 4% at 16 K . On the other hand, the devices fabricated by the activation showed MR ratio of above 300% at 16 K. These results suggest that it is possible to fabricate planar-type ferromagnetic tunnel junctions with vacuum barriers by electromigration techniques.     

A WEB-based integrated data processing system for the TRIAM-1M

In TRIAM-1M, plasma discharge can be sustained for over five hours [H. Zushi, et al., Steady-state tokamak operation, ITB transition and sustainment and ECCD experiments in TRIAM-1M, Nucl. Fusion 45 (2005) S142–S156]. In order to avoid sitting in front of one console for the purpose of monitoring the plasma discharge, it is recommended that the experimental information be accessible from any location at any time. In addition, simple services to access experimental information are required in order to promote the participation of multiple researchers in the TRIAM-1M experiment. Thus, A WEB-based integrated data processing system that provides management for experiment planning, an experimental log, numerical data, and plasma supervision has been installed in the TRIAM-1M. These services are composed primarily of an Apache WEB server, a Tomcat JSP/Servlet container, and a MySQL relational database. This system is constructed using the object-oriented Java language, which is easy to maintain and develop because of the intrinsic characteristics of the Java language. When participating in experiments, researchers are required only to prepare a WEB browser on any platform and are no longer required to memorize complex operations because all services are provided with a uniform user interface through a WEB browser. Furthermore, with the integration of these services, the required information and numerical data can be provided promptly by tracing HTML links that are created dynamically by server applications.     

Vacuum insulation of the high energy negative ion source for fusion application

Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of ～2 m(2). The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A, 500 keV D(-) ion beams for 100 s.     

Effects of Silica and Titanium Oxide Particles on a Human Neural Stem Cell Line: Morphology,Mitochondrial Activity,and Gene Expression of Differentiation Markers

Several in vivo studies suggest that nanoparticles (smaller than 100 nm) have the ability to reach the brain tissue. Moreover, some nanoparticles can penetrate into the brains of murine fetuses through the placenta by intravenous administration to pregnant mice. However, it is not clear whether the penetrated nanoparticles affect neurogenesis or brain function. To evaluate its effects on neural stem cells, we assayed a human neural stem cell (hNSCs) line exposed in vitro to three types of silica particles (30 nm, 70 nm, and <44 μm) and two types of titanium oxide particles (80 nm and < 44 μm). Our results show that hNSCs aggregated and exhibited abnormal morphology when exposed to the particles at concentrations ≥ 0.1 mg/mL for 7 days. Moreover, all the particles affected the gene expression of Nestin (stem cell marker) and neurofilament heavy polypeptide (NF-H, neuron marker) at 0.1 mg/mL. In contrast, only 30-nm silica particles at 1.0 mg/mL significantly reduced mitochondrial activity. Notably, 30-nm silica particles exhibited acute membrane permeability at concentrations ≥62.5 μg/mL in 24 h. Although these concentrations are higher than the expected concentrations of nanoparticles in the brain from in vivo experiments in a short period, these thresholds may indicate the potential toxicity of accumulated particles for long-term usage or continuous exposure.     

Hyperosmotic Stress Induces Phosphorylation of CERT and Enhances Its Tethering throughout the Endoplasmic Reticulum

The ceramide transport protein (CERT) delivers ceramide from the endoplasmic reticulum (ER) to the Golgi apparatus, where ceramide is converted to sphingomyelin (SM). The function of CERT is regulated in two distinct phosphorylation-dependent events: multiple phosphorylations in a serine-repeat motif (SRM) and phosphorylation of serine 315 residue (S315). Pharmacological inhibition of SM biosynthesis results in an increase in SRM-dephosphorylated CERT, which serves as an activated form, and an enhanced phosphorylation of S315, which augments the binding of CERT to ER-resident VAMP-associated protein (VAP), inducing the full activation of CERT to operate at the ER–Golgi membrane contact sites (MCSs). However, it remains unclear whether the two phosphorylation-dependent regulatory events always occur coordinately. Here, we describe that hyperosmotic stress induces S315 phosphorylation without affecting the SRM-phosphorylation state. Under hyperosmotic conditions, the binding of CERT with VAP-A is enhanced in an S315 phosphorylation-dependent manner, and this increased binding occurs throughout the ER rather than restrictedly at the ER–Golgi MCSs. Moreover, we found that de novo synthesis of SM with very-long acyl chains preferentially increases via a CERT-independent mechanism under hyperosmotic-stressed cells, providing an insight into a CERT-independent ceramide transport pathway for de novo synthesis of SM.     

Natural Ligand-Mimetic and Nonmimetic Inhibitors of the Ceramide Transport Protein CERT

Lipid transfer proteins (LTPs) are recognized as key players in the inter-organelle trafficking of lipids and are rapidly gaining attention as a novel molecular target for medicinal products. In mammalian cells, ceramide is newly synthesized in the endoplasmic reticulum (ER) and converted to sphingomyelin in the trans-Golgi regions. The ceramide transport protein CERT, a typical LTP, mediates the ER-to-Golgi transport of ceramide at an ER-distal Golgi membrane contact zone. About 20 years ago, a potent inhibitor of CERT, named (1R,3S)-HPA-12, was found by coincidence among ceramide analogs. Since then, various ceramide-resembling compounds have been found to act as CERT inhibitors. Nevertheless, the inevitable issue remains that natural ligand-mimetic compounds might directly bind both to the desired target and to various undesired targets that share the same natural ligand. To resolve this issue, a ceramide-unrelated compound named E16A, or (1S,2R)-HPCB-5, that potently inhibits the function of CERT has recently been developed, employing a series of in silico docking simulations, efficient chemical synthesis, quantitative affinity analysis, protein–ligand co-crystallography, and various in vivo assays. (1R,3S)-HPA-12 and E16A together provide a robust tool to discriminate on-target effects on CERT from off-target effects. This short review article will describe the history of the development of (1R,3S)-HPA-12 and E16A, summarize other CERT inhibitors, and discuss their possible applications.