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141.
J. M. Florence F. W. Glaze C. H. Hahner Ralph Stair 《Journal of the American Ceramic Society》1948,31(12):328-331
A study has been made of the transmittance of near-infrared energy by a number of binary glasses. Of the systems studied, the lithia-silica and lead oxide-silica glasses were found to have the highest transmittance of energy in the range of wave lengths from 3.0 to 5.0 microns. The transmittance of lithia-silica glass is compared with that of the other alkali-silica glasses. Values of transmittance are given for lead silicate glasses of higher lead content than previously reported in the literature. 相似文献
142.
This paper investigates the problem of unsteady magnetohydrodynamic heat plus mass transfer convective flow over a moveable vertical plate with the influence of thermophoresis and thermal radiation. The physical problem is governed by a set of partial differential equations. These sets of equations are coupled and are nonlinear. They were transformed into a dimensionless form of equations by introducing appropriate nondimensional quantities. An iterative method called the spectral relaxation method was used to linearize and decouple the set of dimensionless equations. Results were presented both in graphs and tables. It was found out that thermophoresis parameter has a significant effect on velocity and concentration fields. The thermal radiation is seen to have a significant effect on velocity and temperature fields. The skin friction is seen to increase the moment thermal Grashof number is increased. The model of Newtonian fluid flow over a moveable vertical plate is considered. The plate was considered moving toward the ‐direction and the radiative heat flux is only with respect to . This study considered effects of viscous dissipation, thermophoresis, and radiation on heat plus mass transfer. This, to the best of our knowledge, has not been considered in the literature. 相似文献
143.
144.
Karim Hentour Viviane Turq Alicia Weibel Florence Ansart Jean-Michel Sobrino Julien Garcia Pierre-François Cardey Christophe Laurent 《Journal of the European Ceramic Society》2019,39(4):1304-1315
Carbon-alumina coatings on stainless steel were prepared by a sol-gel route. The dispersion of the commercial graphite flakes by an ultrasonic bath, an ultrasonic probe and a high-shear mixer, produce thinner flakes, few-layered-graphene and bi-layer-graphene (BLG), respectively. The coatings were examined by optical and electron microscopy, interferential rugosimetry, optical profilometry and Raman spectroscopy. The friction coefficient against a steel ball is decreased by a factor of 5–7 and the wear volume is reduced by a factor of 6–38 compared to a pure alumina coating. The best results correspond to the sample prepared using the high-shear mixer. Delamination of the graphite flakes into BLG during the friction test provides the system with debris suitable for tribofilm building up and lubrication but it is better to already have carbon dispersed as BLG in the coating before the test, notably because the carbon surface area available is much higher. 相似文献
145.
To characterize the postnatal development of geniculocortical axon arbor morphology in owl monkeys at a series of ages from birth to adulthood, individual arbors were bulk-filled with HRP in brain slice preparations and were reconstructed from serial sections. At all ages, cortical layers and sublayers were obvious. Presumed M or magnocellular arbors were largely confined to layer IV alpha, but they also extended into layer IIIc (IVB of Brodmann, 1909); presumed P or parvocellular arbors were almost exclusively confined to layer IV beta. Other axons that may reflect feedback projections from MT terminated in layer IIIc. Overall, M axon arbors increased in size and complexity from birth to adulthood with mean surface-view arbor areas ranging from 0.08 +/- 0.01 mm2 in newborns to 0.24 +/- 0.02 mm2 in adults. The developing P arbor areas were, on average, as large or larger than adult (newborn = 0.07 +/- 0.01 mm2, adult = 0.047 +/- 0.01 mm2; n.s.) but the arbors were somewhat less complex. Since the brain and area 17 increase in size postnatally, the proportion of area 17 subserved by each P arbor would decrease in postnatal development. Terminal boutons with immature features were evident in both M and P populations at all developmental ages. The results indicate that, while both LGN axon types in monkeys undergo morphological changes postnatally, M arbors appear to mature by increasing arbor size and terminal branching complexity, whereas P arbors increase in complexity but not in size. These distinct programs of axon arbor development suggest that the periods of susceptibility of geniculocortical axon arbors to postnatal influences of the environment, and the types of plastic responses they potentially exhibit, are class-specific. 相似文献
146.
On the edge: Intelligent CALL in the 1990s 总被引:1,自引:0,他引:1
Florence Reeder 《Computers and the Humanities》1989,23(1):71-84
On the edge: Intelligent CALL in the 1990s 相似文献
147.
The radiosterilization of plastic packaging theoretically induces two types of chemical modifications, namely reticulation and cleavage, that depend not only on the chemical structure of the polymer, but also on the kind and dose of radiation. This article proposes a methodology for studying plasticized polyvinylchloride (PVC) behavior submitted to β radiation. Analytical techniques such as thermogravimetric analysis (TGA) and size exclusion chromatography (SEC) coupled with a light scattering detector were used in this study. SEC has informed us directly on the modifications (reticulation, scission) that intervened after a radiotreatment; TGA allowed us to highlight polymer structural changes. In addition, FTIR was employed to demonstrate an intermolecular dehydrochlorination following the radiotreatment. The results of these investigations permitted us to demonstrate both a reticulation and a scission phenomena within the PVC polymer. © 1994 John Wiley & Sons, Inc. 相似文献
148.
149.
Richard M. Laine†‡§ Florence Babonneau¶ Kay Y. Blowhowiak§ Richard A. Kennish§ Jeffrey A. Rahn‡†† Gregory J. Exarhos‡‡ Kurt Waldner‡ 《Journal of the American Ceramic Society》1995,78(1):137-145
The pyrolytic evolution of poly(N-methylsilazane), –[H2 SiN-Me] x –, from preceramic polymer to ceramic product is followed by heating samples of the partially cross-linked polymer, in 200°C increments, from ambient temperature to 1400°C. The intermediate products are characterized by chemical analysis, diffuse reflectance Fourier transform IR spectroscopy (DRIFTS), Raman spectroscopy, and 29 Si and 13 C magic-angle spinning (MAS) solid-state NMR. Spectro-scopic characterization indicates that the 1400°C pyrolysis products are amorphous silicon nitride mixed with amorphous and graphitic carbon (as determined by Raman spectroscopy), rather than silicon carbide nitride, as expected based on the presence of up to 20 mol% retained carbon. Efforts to crystallize the silicon nitride through heat treatments up to 1400°C do not lead to any crystalline phases, as established by transmission electron microscopy (TEM) and small-area electron diffraction (SAD). It appears that the presence of free carbon, along with the absence of oxygen, strongly inhibits crystallization of amorphous silicon nitride. These results contrast with the isostructural poly-(Si-methylsilazane), –[MeHSiNH] x –, which is reported to form silicon carbide nitride on pyrolysis. 相似文献
150.
1. Arterial blood from 63 male (315-500 g) and 60 female (210-290 g) healthy Sprague-Dawley rats was analyzed for 16 hematological and 22 clinical chemistry parameters. 2. Nine of these parameters were associated with growth and developmental changes in males between 38-78 days and females 49 - 89 days of age. 3. Weight gain in both sexes followed patterns consistent with other studies using this strain, but interexperimental variation was as much as +/-22%. 4. Rectal temperatures of females averaged 37.28 degrees C, being statistically greater (P < 0.05) than the average male at 36.99 degrees C. 5. The data provide reference values for use in toxicological and other investigations. 相似文献