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991.
992.
A new gram-positive, nonmotile coccus is described. Strains IFO 12422T (T = type strain) and IFO 15385 in the Institute for Fermentation, Osaka, culture collection, which were isolated from soil and water, respectively, have the following chemotaxonomic characteristics: menaquinone MK-9(H4); G + C content of DNA of 67 mol%; and LL-diaminopimelic acid, alanine, glycine, and glutamic acid in a molar ratio of ca. 1:2:1:1 (type A3 gamma). Mycolic acids are not present. The taxonomic characteristics of these organisms are different from those of previously described gram-positive, high-G + C-content cocci. The partial 16S rRNA sequence indicated that IFO 12422T represents a distinct line of descent among gram-positive bacteria with a high G + C content. The name Luteococcus japonicus gen. nov., sp. nov. is proposed. The type strain is strain IFO 12422. 相似文献
993.
994.
995.
In fatigue of materials, it is often observed that a number of cracks initiate from preexisting defects and propagate to form major cracks causing the final failure. In this paper, we consider a doubly-periodic array and a zig-zag array of cracks in a two-dimensional solid subjected to tension, as simplified models of randomly distributed cracks in materials. The analysis is based on the eigenfunction expansions of the complex stress potentials for properly chosen unit regions. Numerical results for the stress intensity factors, crack opening displacements and effects of cracks on the tensile stiffnesses of these solids are given for various combinations of the parameters. The results are then fitted to reliable polynomial formulae for convenience of engineering applications. 相似文献
996.
I. Kashif H. Farouk S. A. Aly A. M. Sanad M. H. El-Kottamy E. E. Assem 《Journal of Materials Science: Materials in Electronics》1992,3(3):144-146
The effect of the addition of Fe2O3 and heat treatment duration on the magnetic susceptibility of vanadium borophosphate glass were studied. The magnetic susceptibility of glass samples was found to increase with increasing Fe2O3 content, which may be explained by the formation of the FeO6 group and the change of Fe2+ to Fe3+ which has higher paramagnetic properties. No detectable changes in the magnetic susceptibility with heat treatment for the samples containing 0.0, 0.5 and 1.0 mol% Fe2O3 was observed. The magnetic susceptibility for the heat treated samples containing 2.5, 5.0 and 7.5 mol% Fe2O3 decreases sharply with increasing duration of heat treatment up to 6 h and then remains almost constant. The sharp decrease in magnetic susceptibility of 2.5 mol% Fe2O3 is attributed to the increase in the number of ferrous ions. The sharp decrease for samples containing 5.0 and 7.5 mol% Fe2O3 is attributed to the increase in the number of Fe3+ in tetrahedral co-ordination. The rate of crystallization owing to the heat treatment was calculated and was found to increase with increasing iron oxide content. The geometry of crystallization was found to be in three-, two-and one-dimension(s) for samples containing 2.5, 5.0 and 7.5 mol% Fe2O3, respectively. 相似文献
997.
High-temperature oxide scale growth at the ceramic-metal interface is a major contributor to the thermomechanical resistance
of thermal barrier coatings for hot stages of gas turbines. In order to better understand this phenomenon, microstructural
observations of the alumina scales formed at 1100 and 1200 °C under air, between low-pressure plasma-sprayed NiCrAlY and air
plasma-sprayed ZrO2-8.5 wt % Y2O3, have been performed by classical and analytical transmission electron microscopy on transverse thin foil specimens. The
evolution of the oxide grain morphology from the metal-oxide to the oxide-oxide interface suggests that the scale growth principally
takes place at the metal-oxide interface. Segregation of yttrium at oxide grain boundaries has been detected as well as significant
quantities of zirconium inside the alumina grains. The oxide growth seems to be dominated by a classical grain-boundary oxygen
diffusion mechanism. The presence of zirconium inside the alumina grains also suggests that Al2O3 partially forms by chemical reduction of ZrO2 by AI. The comparison between the microstructures observed and that of alumina scales grown under similar conditions on bare
MCrAlY alloys gives some insight into how the ceramic top-coat modifies NiCrAlY high-temperature oxidation mechanisms. 相似文献
998.
999.
Li Z.-M. Landheer D. Veilleux M. Conn D.R. Surridge R. Xu J.M. McDonald R.I. 《Photonics Technology Letters, IEEE》1992,4(5):473-476
The authors have developed a 2-D device simulator for heterostructure metal-semiconductor-metal (MSM) photodetectors. They have incorporated a model of multilayer optics into the simulator and used it to analyze the temporal response of a resonant-cavity enhanced heterostructure with a confining buffer layer and a distributed Bragg reflector (DBR). The authors show that through fine tuning the layer thicknesses, optical resonance enhancement of the light absorption can be obtained 相似文献
1000.
Journal of Materials Science Letters - 相似文献