Development of a specimen heating holder with an evaporator and gas injector and its application for catalyst

A specimen heating holder equipped with a gas injector and an evaporator has been developed for use with conventional transmission electron microscopes (TEMs). The developed specimen holder allows both synthesis of metal oxide support and deposition of catalyst nano-particles in situ. Since the holder is designed to be used in small gapped high-resolution objective lens pole-piece, all the procedure from the synthesis of support material to the deposition of catalyst as well as the behavior of the catalyst nano-particles on the support can be observed at near atomic resolution. The developed specimen holder was applied to the study of AuPd catalyst. First, air was injected onto heated aluminum particles via a gas injector to synthesize Al(2)O(3) support. Then, nano-particles of AuPd were deposited on the Al(2)O(3) support. After the deposition, the synthesized Al(2)O(3) support was heated and air was injected again to observe behaviors of the deposited AuPd nano-particles at elevated temperatures in the aerial environment. Behaviors of the AuPd nano-particles such as coalescence, segmentation and diffusion to the Al(2)O(3) support were dynamically observed at atomic level high resolution.     

Development of a high temperature-atmospheric pressure environmental cell for high-resolution TEM

An environmental cell for high-temperature, high-resolution transmission electron microscopy of nanomaterials in near atmospheric pressures is developed. The developed environmental cell is a side-entry type with built-in specimen-heating element and micropressure gauge. The relationship between the cell condition and the quality of the transmission electron microscopic (TEM) image and the diffraction pattern was examined experimentally and theoretically. By using the cell consisting of two electron-transparent silicon nitride thin films as the window material, the gas pressure inside the environmental cell is continuously controlled from 10(-5)?Pa to the atmospheric pressure in a high-vacuum TEM specimen chamber. TEM image resolutions of 0.23 and 0.31?nm were obtained using 15-nm-thick silicon nitride film windows with the pressure inside the cell being around 5?×?10(-5) and 1?×?10(4)?Pa, respectively.     

Study on waste heat recovery from exhaust smoke in cogeneration system using woody biomass fuels

In recent years, fossil fuels such as petroleum, coal, and natural gas have become limited resources. In addition, bad effects caused by excessive carbon dioxide (CO₂) emissions have now begun destroying our global environment seriously. Since current living and economical standards depend strongly on the fossil fuels, it is necessary to realize a new society that utilizes biomass as one of major sources of energy. In this background, we manufactured a practical Stirling engine using woody biomass fuels for the first time in Japan in 2005. Further we proposed a unique cogeneration system with the Stirling engine that uses woody biomass fuels such as sawdust, firewood, and wood pellets. In this cogeneration system, 43% of the input energy is wasted as heat loss from the exhaust smoke into the atmosphere. Therefore we tried to recover the waste heat by using a thermoelectric conversion module in this study. In this report, the results of basic performance test and demonstration experiment as a cogeneration system combined the waste heat recovery with a power generating system are reported. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20390     

Physical and electrochemical characteristics of nickel hydroxide as a positive material for rechargeable alkaline batteries

Nickel hydroxide is widely used as an active material in pasted-type nickel electrodes. Physical properties of several nickel hydroxide powders have been examined by laser diffraction, BET, X-ray diffraction, thermal analysis and SEM. Nickel hydroxide powder with a smaller crystalline size shows better charge-discharge cyclic characteristics. The chemical diffusion coefficients of the proton in the nickel hydroxide sample are measured by a current pulse relaxation method. Nickel hydroxide with a smaller crystalline size shows a higher proton diffusion coefficient, giving excellent cycling behaviour.     

A new optoelectronic device based on modulation-dopedheterostructure: demonstration of functions as both lateral currentinjection laser and junction field effect transistor

A new type of optoelectronic semiconductor device which utilizes the modulation-doped (MOD) heterostructure is demonstrated. The device operates not only as a lateral current injection (LCI) laser but also as a junction field-effect transistor (JFET) based on the MOD heterostructure. This first demonstration of the structural compatibility of the LCI laser with the MODFET is one step toward optoelectronic integration utilizing a common two-dimensional electron gas     

High-performance dual-gate CMOS utilizing a novel self-alignedpocket implantation (SPI) technology

A self-aligned pocket implantation (SPI) technology is discussed. This technology features a localized pocket implantation using the gate and drain electrodes (TiSi₂ film) as well as self-aligned masks. The gate polysilicon is patterned by KrF excimer laser lithography. The measured minimum gate length L_g (the physical gate length) is 0.21 μm for both N- and P-MOSFETs. A newly developed photoresist was used to achieve less than quarter-micrometer patterns. This process provides high punchthrough resistance and high current driving capability even in such a short channel length. The subthreshold slope of the 0.21-μm gate length is 76 mV/dec for N-MOSFETs and 83 mV/dec for P-MOSFETs. The SPI technology maintains a low impurity concentration in the well (less than 5×10 ¹⁶ cm^-3). The drain junction capacitance is decreased by 36% for N-MOSFETs and by 41% for P-MOSFETs, compared to conventional LDD devices, which results in high-speed circuit operation. The delay time per stage of a 51-stage dual-gate CMOS ring oscillator is 50 ps with a supply voltage of 3.3 V and a gate length of 0.36 μm, and 40 ps with a supply voltage of 2.5 V and a gate length of 0.21 μm     

Phylogenetic affinity of mitochondria of Euglena gracilis and kinetoplastids using cytochrome oxidase I and hsp60

To elucidate the role of ras gene mutations during the early stage of colorectal tumour progression, K-ras gene mutations were analysed in 32 benign adenomas and 36 adenomas with focal carcinoma in the colorectum by microscraping of histologically pure regions from tissue sections, polymerase chain reaction-restriction fragment length polymorphism and in part by direct sequencing. Several regions were scraped out and analysed when an adenoma contained areas with different grades of dysplasia. The frequencies of K-ras gene mutation in mild dysplasia, moderate dysplasia and focal carcinoma were 19% (7/36), 51% (25/49) and 39% (14/36) respectively. The K-ras gene status was heterogeneous in 4 of the 11 benign adenomas from which multiple samples were obtained, and mutations were always found in the regions with more advanced dysplasia in these adenomas. Thirteen of the 36 adenomas with focal carcinoma showed heterogeneity of mutations between the adenoma region and the focal carcinoma. Seven of which had mutations only in the adenoma region. These findings indicated that the K-ras gene mutations occur during the late stage of adenoma progression and may confer a more advanced morphological phenotype of adenoma, but these mutations are not mainly involved in malignant transformation from adenoma to carcinoma.     

Blade Fabrication Process for Titanium Matrix Composites

Continuous fiber reinforced titanium matrix composites (TMC) are attractive as one of the potential structural materials for aerospace applications, because of their high specific strength and stiffness. However, TMC parts are not yet put into practical use due to their limited damage tolerance and an enormous production cost resulting from process limitation requiring preliminary forming and elaborate tooling for consolidation. In order to reduce the production cost, superplastic TMC sheets (SiC/Ti-4.5Al-3V-2Mo-2Fe) were developed, and deformation properties, and cavitation behavior were investigated. The blade-shaped model was formed successfully out of the newly developed TMC sheet by means of Argon-gas-pressure forming technique. However, in order to reduce the defects that were observed in fiber/matrix interface of the deformed TMC, the tensile flow stresses in TMC sheet during deformation should be minimized. In this study a diaphragm forming method, whereby a TMC sheet is forced against the form tool surface by pressure acting on a driving sheet, was adopted to reduce the tensile stress generated in TMC sheet during superplastic forming of blade-shaped models. As a result, no defects were observed by an optical microscope in the TMC deformed by diaphragm forming method. Diffusion bonding techniques to attach the root blocks to the deformed TMC sheet and the reduction of the blade-fabrication cost are also discussed.     

A new class of DNA photolyases present in various organisms including aplacental mammals

DNA photolyase specifically repairs UV light-induced cyclobutane-type pyrimidine dimers in DNA through a light-dependent reaction mechanism. We have obtained photolyase genes from Drosophila melanogaster (fruit fly), Oryzias latipes (killifish) and the marsupial Potorous tridactylis (rat kangaroo), the first photolyase gene cloned from a mammalian species. The deduced amino acid sequences of these higher eukaryote genes show only limited homology with microbial photolyase genes. Together with the previously cloned Carassius auratus (goldfish) gene they form a separate group of photolyase genes. A new classification for photolyases comprising two distantly related groups is proposed. For functional analysis P.tridactylis photolyase was expressed and purified as glutathione S-transferase fusion protein from Escherichia coli cells. The biologically active protein contained FAD as light-absorbing cofactor, a property in common with the microbial class photolyases. Furthermore, we found in the archaebacterium Methanobacterium thermoautotrophicum a gene similar to the higher eukaryote photolyase genes, but we could not obtain evidence for the presence of a homologous gene in the human genome. Our results suggest a divergence of photolyase genes in early evolution.