InP/Al2O3n-channel inversion-mode m.i.s.f.e.t.s using sulphur-diffused source and drain

InP metal-insulator-semiconductor field-effect transistors (m.i.s.f.e.t.s) have been fabricated using c.v.d. Al2O3 as the gate insulator and the sulphur-diffusion process for source and drain. The n-channel inversion-mode device exhibits normally off behaviour. A maximum d.c. transconductance gm of 10 mS (87 mS/mm of gate width) has been obtained.     

n-channel formation on semi-insulating InP surface by m.i.s.f.e.t.

InP m.i.s.f.e.t.s using Fe-doped semi-insulating material surface have been fabricated. The devices, composed of sulphur-diffused n-type source and drain and c.v.d. Al2O3 gate insulator, exhibited n-channel normally-off behaviour and a source drain capacitance two orders of magnitude smaller than that of p-InP m.i.s.f.e.t.s with the same dimensions.     

Selectively ion implanted Gunn-f.e.t. integrated circuits for pulse regenerator

A planar GaAs integrated Gunn-effect device and f.e.t. connected in cascade have been fabricated using selective sulphur-ion implantation. High-speed pulse regeneration and pulse amplification have been realised under d.c. bias condition. Output voltage and voltage gain of the regenerated pulse of 1 ns width were 1.7 V and 18.6 dB, respectively.     

Production of anti-CD2 chimeric antibody by recombinant animal cells

Expression vectors for chimeric anti-CD2 antibody were constructed in order to clarify the importance of the expression ratio of heavy (H-) and light (L-) chains of antibody to antibody production in animal cells. The antibody genes were introduced into cells using plasmid DNA vectors or replication-defective retroviral vectors. Productivity was maximal when the expression ratio of H-and L-chains was 1:1, and decreased when the ratio was not equal. We also examined the expression of antibody using one-packed vectors in which the bicistronic expression of H- and L-chain genes was mediated by an internal ribosomal entry site (IRES) sequence derived from encephalomyocarditis virus (EMCV). The translation efficiency was unbalanced between 5'Cap- and IRES-dependent genes. Using the retroviral vectors, it was estimated that the IRES-dependent translation efficiency was 5-fold lower than the 5'Cap-dependent translation efficiency. The cells exhibiting an unbalanced expression of H- and L-chains tended to accumulate H-chain protein.     

Electrical conductivity increase of Al-doped ZnO films induced by high-energy-heavy ions

We have investigated the effects on electrical properties of Al-doped ZnO (AZO) semiconductor films induced by 90 MeV Ni, 100 MeV Xe and 200 MeV Xe ions. The AZO films with c-axis orientation on SiO₂-glass substrate were prepared by using a RF-sputter-deposition method at 400 °C. We find that the conductivity increases by two order of magnitude under high-energy-heavy ion irradiation, as has already been observed for 100 keV Ne ion irradiation. We also find that the efficiency of the conductivity enhancement, which is defined as the conductivity increment per a unit of ion fluence, scales super-linearly with the electronic stopping power (S_e). The carrier density and mobility for unirradiated and irradiated AZO films are presented.     

Hydrogen storage and thermal conductivity properties of Mg-based materials with different structures

Mg-based hydrogen storage materials can be very promising candidates for stationary energy storage application due to the high energy density and low cost of Mg. Hydrogen storage kinetics and thermal conductivity are two important factors for the material development for this kind of application. Here we studied several types of Mg-based materials with different structure-micrometer scale Mg powders, Mg nanoparticles, single crystal Mg, nanocrystalline Mg₅₀Co₅₀ BCC alloy and Mg thin film samples. It seems the Mg materials with good kinetics usually are the ones with nanostructure and tend to show poor thermal conductivity due to electron/phonon scattering resulting from more interfaces and boundaries in nanomaterials. Based on this work, good crystallinity Mg phase incorporated in carbon nano framework could be one promising option for energy storage.     

Development of multi‐analyte DNA microchip using 3D nanoprototyping fabrication method

The importance of microfluidics systems for high‐throughput postgenome analysis has been steadily increasing. We conceived and fabricated an integrated six‐microchip capillary electrophoresis unit on a small area of 30 × 30 mm for high‐throughput DNA analysis. The design of the structure was performed using a fluid dynamics simulation of electrophoresis to improve the DNA separation resolution. A narrow width of the micro channel at the corners was adopted. For simple fabrication of the microchip, we developed the PMMA structure of the micro fluid channel using lithography, molding, and fusion bonding techniques. It was demonstrated that the proposed integrated structure of micro channels results in good performance of on‐chip DNA separation in a small one‐unit area of 9 × 9 mm. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 32–36, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21156     

Hydrogenolysis of sugar beet fiber by supported metal catalyst

Sugar beet fiber is an agricultural by-product in the sugar manufacturing and an available biomass source with a rich hemicellulose component. So far, there has been no report on the catalytic conversion of the beet fiber for the synthesis of chemicals. In this work, the hydrogenolysis of the beet fiber was studied by using supported metal catalysts under pressurized hydrogen conditions. Activated carbon supported Ru was found to show the highest catalytic activity to give arabitol as a major product in the hydrogenolysis of hemicellulose part of this material. The reuse ability of the catalyst was also investigated.     

Isolation of Pseudozyma churashimaensis sp. nov., a novel ustilaginomycetous yeast species as a producer of glycolipid biosurfactants, mannosylerythritol lipids

An ustilaginomycetous anamorphic yeast species isolated from the leaves of Saccharum officinarum (sugarcane) in Okinawa, Japan, was identified as a novel Pseudozyma species based on morphological and physiological aspects and molecular taxonomic analysis using the D1/D2 domains of the large subunit (26S) rRNA gene and the internal transcribed spacer 1 (ITS1)-5.8S-ITS2 regions. The name Pseudozyma churashimaensis sp. nov. was proposed for the novel species, with JCM 16988(T) as the type strain. Interestingly, P. churashimaensis was found to produce glycolipid biosurfactants, a mixture of mannosylerythritol lipids (MELs), including a novel tri-acetylated derivative (MEL-A2), from glucose. The observed critical micelle concentration (CMC) and the surface tension at CMC of MEL-A2 were 1.7 × 10?? M and 29.2 mN/m, respectively. Moreover, on a water-penetration scan, MEL-A2 efficiently formed different lyotropic liquid crystalline phases, including the lamella phase at a wide range of concentrations, indicating its excellent surface-active and self-assembling properties. The novel strain of the genus Pseudozyma should thus facilitate the application of glycolipid biosurfactants in combination with other MEL producers.