Microstructures and hydrogen absorption–desorption behavior of an A2B7-based La-Mg-Ni alloy

The microstructural changes during hydrogen absorption–desorption cycles of an A₂B₇-based La-Mg-Ni alloy with a nominal composition of La_1.5Mg_0.5Ni_7.0 were systematically investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The ternary La-Mg-Ni alloy was mostly composed of 2H-A₂B₇ phase with minor inclusions of 3R-A₅B₁₉, 2H-A₅B₁₉ and 3R-AB₃ phases existing as parts of intergrowth structures with the major A₂B₇ phase. Most parts of the major 2H-A₂B₇ phase containing Mg exhibited an excellent crystal structure retention after the hydrogen absorption–desorption cycles at 80 °C. Two types of defected bands were found to develop after the first hydrogen absorption–desorption cycle. The first ones are amorphous bands developed inside the minor 3R-AB₃ phase, while the second ones develop as heterogeneously strained regions inside the major 2H-A₂B₇ phase. Both the defected bands are considered to be responsible for the irreversible hydrogen capacity of the A₂B₇-based La_1.5Mg_0.5Ni_7.0 alloy during the hydrogen absorption–desorption cycles at 80 °C.     

Stabilization analysis of commercial‐scale subsonic diagonal‐type MHD generator considering loading conditions

In previous research on subsonic diagonal‐type MHD generators, the authors have proposed a conceptual design with relatively low Mach number in order to stabilize the MHD generator of commercial scale and have shown that the MHD generator works stably under constant‐current loading condition. In the present paper, effects of loading conditions on stability of the MHD generator are examined. A channel‐length scale linear stability analysis and time‐dependent calculations are carried out, where both gasdynamical boundary conditions and loading condition are taken into account. These analyses show that the MHD generator behaves stably under various loading conditions such as constant‐voltage loading condition and ohmic loading condition. Then the stability of the MHD generator connected with an ac power system is also analyzed by time‐dependent calculations. The analysis shows that the MHD generator stably provides the rated power to the ac power line. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 16–24, 1999     

Directional Solidification of TiAl‐based Alloys and Properties of Directionally Solidified Ingots

The mechanical properties of TiAl‐based alloys with lamellar microstructure are extremely anisotropic. However, if the lamellar microstructure can be aligned parallel to the growth direction, the resulting material should possess a good combination of mechanical properties. Unfortunately, simple casting operations often lead to a solidification texture with the lamellar boundaries perpendicular to the heat flow direction. This difficulty can be overcome by directionally solidifying TiAl‐based alloys. We have been performing directional solidification experiments with and without using a seeding technique. The current status of directional solidification of TiAl‐based alloys is reviewed.     

Crystallization of amorphous poly(lactic acid) induced by organic solvents

Crystallization of amorphous poly(lactic acid) (PLA) was investigated in various organic solvents, such as acetone, ethylacetate, diethylether, tetrahydrofurane, methanol, hexane, toluene, xylene, and o‐dichlorobenene. Most of the solvents, except hexane, induced crystallization of amorphous PLA. Acetone was the most effective solvent to accelerate the crystallization among the solvents used. The crystallization was induced by permeation of acetone into the amorphous phase of PLA, and the permeation obeyed Fick type diffusion. The crystallization rate increased with increasing of conducting temperature. Crystallized PLA formed α crystalline structure. The permeated acetone in the crystallized PLA gradually evaporated as time passes, and the elimination of acetone affected thermal and mechanical properties of the crystallized PLA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Numerical simulation of intermediate‐temperature disk type seal‐less SOFC fed with partially reformed methane

Since natural gas containing methane as major component is the most promising fuel for the solid oxide fuel cell (SOFC), development of a numerical simulation code of the intermediate‐temperature disk‐type seal‐less SOFC for methane fuel case is considered to be very useful. In this study, therefore, we develop a new simulation code for the single cell unit of this type of SOFC fed with partially reformed methane as the fuel gas, based on the existing simulation code for pure hydrogen. We calculate the current density versus single cell voltage (i–V ) curves of the single cell unit for various cases with a wide range of the cell temperature and prereformer temperature conditions and compare them with the corresponding experimental results. From the results, we confirm that the numerically obtained i–V curves coincide very well with the corresponding experimental ones in all cases. The variations of the i–V curves, which depend not only on the cell temperature but also on the prereformer temperature, are successfully simulated with a sufficiently high accuracy, indicating the validity of the newly developed simulation code. We also investigate the detailed influence of the cell temperature and prereformer temperature on the cell performance on the basis of the numerically obtained gaseous partial pressure profiles in the fuel channel and Nernst potential profiles in the cell, and clarify the reason why the prereformer temperature has obvious influence on the cell performance when the cell temperature is low, though the cell performance is almost independent of the prereformer temperature when the cell temperature is high. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Clear cell odontogenic carcinoma: A case report and literature review of odontogenic tumors with clear cells

For a period of 10 months, the perceptive-motor skills of golden hamsters were tested as part of an experiment to investigate vestibular controlled behaviour. We found that four out of 40 hamsters had more difficulties with swimming and equilibrium maintenance than the rest of the group. These disturbances either were apparent during the first months of testing or developed at a later period. In three hamsters the disturbances persisted over time while in one hamster performance in perceptive-motor skills increased. Histological examination with scanning electron microscopy revealed otoconial abnormalities in the saccule and/or the utricle. The otoconia were either malformed or replaced by spherulites. We conclude that the observed behavioural disturbances were caused by a defective peripheral vestibular organ. The results show similarities with data from pathology in other animals as well as in the human inner ear.     

Performance of a protonated Co-contained silicate catalyst for NO reduction in equivalent conditions to diesel engine exhaust

Effects of co-existence of H₂O, CO₂, and SO₂ in the reaction gas on the catalytic performance of cobalt containing silicate having ZSM-5 (MFI) structure (Co-silicate) were studied. Water vapor retarded only the hydrocarbon conversion to CO₂ but no effect was observed on NO conversion. Addition of CO₂ or SO₂ did not affect the reaction. The stability of H-Co-silicate against H₂O, CO₂, and SO₂ was ascribed to the state of metallic active species which were stabilized by incorporation into the high siliceous MFI structure.     

Reactions of rare earth acetates with aluminum isopropoxide in ethylene glycol: Synthesis of the garnet and monoclinic phases of rare earth aluminates

The reactions of mixtures of rare earth (RE) acetates and aluminum isopropoxide (Al/RE = 3/5) in ethylene glycol at 300°C afforded amorphous products. The IR spectra of these products were essentially identical with each other and indicated the presence of an acetate group and ethylene glycol moiety. When the content of RE (La–Gd) acetate in the starting mixture was increased, a crystalline glycol complex of RE oxide acetate was also formed together with the amorphous phase, but the reactions of acetates of the smaller RE ions (Tb–Lu) yielded amorphous products with wider compositions (Al/RE = 5/3–1/6). Phase-pure RE3Al5O12 (garnet) and RE4Al2O9 (monoclinic) were obtained by calcination of the amorphous products with the corresponding stoichiometric compositions at low temperatures.     

Sustaining the development of primary care in academic medicine. Working Group on Sustaining the Development of Academic Primary Care. Association of American Medical Colleges

Dietary supplementation of very long-chain n-3 fatty acids to rats reduces postprandial plasma concentrations of triacylglycerol, unesterified fatty acids and glycerol after long-term feeding by unknown mechanisms [Rustan et al., J. Lipid Res. 34 (1993) 1299-1309]. In the present study we examine the role of adipose tissues in metabolism of fatty acids. Postprandial plasma concentrations of triacylglycerol, unesterified fatty acids and glycerol were reduced by 75%, 50% and 30%, respectively, during 49 days of feeding high-fat diets containing n-3 fatty acids (6.5% n-3 fatty acid concentrate, 13% lard) as compared to lard (19.5% lard). These differences were observed already after two days of feeding. Plasma concentration of unesterified very long-chain n-3 fatty acids increased to 50 microM in n-3 fatty acid-supplemented rats, whereas these fatty acids were undetectable in lard-fed animals. The n-3 fatty acid-enriched diet limited cell volumes of perirenal and epididymal adipocytes by 40% and 30%, respectively, after 49 days, as compared to lard feeding. This reduction in cell volume was not due to reduced synthesis of glycerolipids in epididymal adipocytes. Acute incubation of perirenal and epididymal adipocytes with oleic acid or eicosapentaenoic acid, caused similar increase in synthesis of triacylglycerol. Dietary supplementation with n-3 fatty acids decreased basal and total lipolysis (isoprenalin-stimulated) in perirenal adipocytes. Basal lipolysis in epididymal adipocytes was reduced by n-3 fatty acids only after 49 days. n-3 fatty acids increased total lipolysis in mesenteric and subcutaneous fat cells compared to adipocytes derived from lard-fed animals, whereas basal lipolysis was unchanged. These results suggest that the reduced postprandial plasma concentration of unesterified fatty acids after n-3 fatty acid-supplementation is not caused by accumulation of fatty acids in adipose tissue. The reduced trophic growth of adipocytes might be due to decreased supply of unesterified fatty acids for triacylglycerol storage. (c) 1998 Elsevier Science B.V.