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排序方式: 共有1209条查询结果,搜索用时 343 毫秒
1.
Rahul Sasidharan Pillai Matteo Frasnelli Vincenzo M. Sglavo 《Ceramics International》2018,44(2):1328-1333
The present work focuses on the fabrication of βTCP (β-tricalcium phosphate) and HA/βTCP (hydroxyapatite/β-tricalcium phosphate) composite coatings by plasma spraying. The starting powders were produced via solid-state method using 2 wt% MgO to stabilize βTCP phase. The synthesized powders were preliminarily granulated to be used by the plasma spray process. Coatings obtained on titanium substrates are uniform and well adherent but due to the high temperature and cooling rate typical for plasma spraying process, βTCP phase is almost totally transformed into the α allotrope. Thermal treatment at 800 °C allows the reconversion of the phase αTCP→ βTCP. It is therefore possible to produce coatings with tuneable dissolution properties by selecting the proper initial powder mixture and the specific thermal treatment. 相似文献
2.
Carin L. Felsen L.B. Kralj D.R. Oh H.S. Lee W.C. Unnikrishna Pillai S. 《Antennas and Propagation, IEEE Transactions on》1997,45(4):592-600
Phase-space data processing is receiving increased attention because or its potential for furnishing new discriminants relating to classification and identification of targets and other scattering environments. Primary emphasis has been on time-frequency processing because of its impact on transient, especially wideband, short-pulse excitations. Here, we investigate the windowed Fourier transform, the wavelet transform, and model based superresolution algorithms within the context of a fully quantified and calibrated test problem investigated by us previously: two-dimensional (2-D) short-pulse plane wave scattering by a finite periodic array of perfectly conducting coplanar flat strips. Because the forward problem has been fully calibrated and parametrized, some quantitative measures can be assigned with respect to the tradeoffs of these time-frequency algorithms, yielding tentative performance assessments of the tested processing algorithms 相似文献
3.
R. M. Pillai S. G. K. Pilhii A. D. Damodaran 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(10):12-16
Indian artisans and craftsmen have long been masters at extracting and shaping metals and alloys, as proven by archaeological
finds from the 2nd—3rd millennia B.C. For example, two well-known artifacts, castings of the dancing girl of Mohenjo Daro
and the Mother Goddess of Adichanallur, Tamilnadu, depict a high degree of metallurgical knowledge. Those castings were formed
by the lost wax process, which later was modified and became known as investment casting. In various parts of India, this
age-old casting process is still being practiced, without any major modifications. This paper discusses details of the process
used by the Indian artisans of Swamimalai, Tamilnadu, and Mannar, Kerala, South India in shaping copper-base alloys into icons
and utensils, bells, and lamps. 相似文献
4.
M. Ravi U. T. S. Pillai B. C. Pai A. D. Damodaran E. S. Dwarakadasa 《Metallurgical and Materials Transactions A》2002,33(2):391-400
The effect of Fe content (0.2 to 0.6 pct) on the microstructure and mechanical properties of a cast Al-7Si-0.3Mg (LM 25/356)
alloy has been investigated. Further, 1 pct mischmetal (MM) additions (a mixture of rare-earth (RE) elements) were made to
these alloys, and their mechanical properties at room and at elevated temperatures (up to 200 °C) were evaluated. A structure-property
correlation on this alloy was attempted using optical microstructure analysis, fractographs, X-ray diffraction, energy-dispersive
analysis of X-rays (EDX), and quantitative metallography by image analysis. An increase in Fe content increased the volume
percentage of Fe-bearing intermetallic compounds (β and π phases), contributing to the loweryield strength (YS), ultimate tensile strength (UTS), percentage elongation, and higher
hardness. An addition of 1 pct MM to the alloys containing 0.2 and 0.6 pct Fe was found to refine the microstructure; modify
the eutectic silicon and La, Ce, and Nd present in the MM; form different intermetallic compounds with Al, Si, Fe, and Mg;
and improve the mechanical properties of the alloys both at room and elevated temperatures. 相似文献
5.
VK Tzitzios V Georgakilas TN Angelidis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(6):699-704
A study of nitrous oxide (N2O) reduction with methane (CH4) and propene (C3H6) in the presence of oxygen (5%) over Ag/Al2O3, Rh/Al2O3 and Ag–Rh/Al2O3 catalysts, with Ag and Rh loadings of 5 wt% and 0.05 wt% respectively, has been performed. From the results, it was observed that the Ag–Rh bimetallic catalyst was the most active for both nitrous oxide removal (more than 95%) and hydrocarbon oxidation. This high activity seems to be connected with a synergistic effect between Ag and Rh. The findings from X‐ray diffraction and X‐ray photoelectron spectroscopy studies showed also, that there were no strong interactions (eg alloying) between Ag and Rh. Copyright © 2005 Society of Chemical Industry 相似文献
6.
Prostate enlargement in mice due to fetal exposure to low doses of estradiol or diethylstilbestrol and opposite effects at high doses 总被引:7,自引:0,他引:7
FS vom Saal BG Timms MM Montano P Palanza KA Thayer SC Nagel MD Dhar VK Ganjam S Parmigiani WV Welshons 《Canadian Metallurgical Quarterly》1997,94(5):2056-2061
On the basis of results of studies using high doses of estrogens, exposure to estrogen during fetal life is known to inhibit prostate development. However, it is recognized in endocrinology that low concentrations of a hormone can stimulate a tissue, while high concentrations can have the opposite effect. We report here that a 50% increase in free-serum estradiol in male mouse fetuses (released by a maternal Silastic estradiol implant) induced a 40% increase in the number of developing prostatic glands during fetal life; subsequently, in adulthood, the number of prostatic androgen receptors per cell was permanently increased by 2-fold, and the prostate was enlarged by 30% (due to hyperplasia) relative to untreated males. However, as the free serum estradiol concentration in male fetuses was increased from 2- to 8-fold, adult prostate weight decreased relative to males exposed to the 50% increase in estradiol. As a model for fetal exposure to man-made estrogens, pregnant mice were fed diethylstilbestrol (DES) from gestation days 11 to 17. Relative to controls, DES doses of 0.02, 0.2, and 2.0 ng per g of body weight per day increased adult prostate weight, whereas a 200-ng-per-g dose decreased adult prostate weight in male offspring. Our findings suggest that a small increase in estrogen may modulate the action of androgen in regulating prostate differentiation, resulting in a permanent increase in prostatic androgen receptors and prostate size. For both estradiol and DES, prostate weight first increased then decreased with dose, resulting in an inverted-U dose-response relationship. 相似文献
7.
8.
Papain was immobilized on polymer supports with spacer arms of varying nature and length. As the length of the spacer arm increased, there was a marked increase in the extent of enzyme immobilization and activity of immobilized enzymes. When a long, flexible and hydrophilic polyethylene glycol spacer was introduced between the polystyrene backbone and the functional group used for immobilization, the extent of coupling and enzyme activity increased. Dependence of enzyme activity on the nature and extent of crosslinking and on the nature of the polymeric backbone was investigated. Hydrophilic polyacrylamide-based supports were found to be more efficient supports for immobilization compared to hydrophobic polystyrene-based supports. 相似文献
9.
Narratives are gaining recognition as important ways occupational therapists and other clinicians can think about the life stories of clients. The purpose of this article is to examine a conceptualization of how changes from one chapter to another occur in life stories, using the metaphor of an adaptive repertoire, and to consider how this notion can be useful in helping clients maintain continuity and a coherent life story in times of change. Three premises based on the concept of adaptation address (a) configurations of occupational forms embedded in particular local worlds, (b) cumulative development of an adaptive repertoire that allows one to perform both competently and appropriately, and (c) adaptive transitions and application of one's repertoire to new circumstances. Implications for research and clinical practice in occupational therapy also are examined. 相似文献
10.