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71.
By selecting carefully controlled conditions for the thermal treatment of sodium borate glasses coated with PbO films, it is possible to prevent Pb2+ ions from penetrating deeply into the glass. For low alkali glasses, an interdiffusion layer can be formed, which sub-surface cation profiling (by ion beam induced radiation) shows is a solid solution of Na2O and B2O3 in PbO which acts as solvent. Experiments with 18.0 mol-% Na2O glass show that it is possible to transform such an interdiffusion layer into a second type in which Na2O and B2O3 together act as solvent and the concentration of PbO solute varies through the layer. For both types of layer the Na2O : B2O3 ratio is different from that of the glass substrate, and for the production of the second type of layer it is shown that an important factor connected with penetration of PbO into the glass surface is a “sweating” process in which thermal treatment of the glass, even in the absence of PbO, results in migration of Na+ ions so that the glass surface has a Na2O content higher than that of the bulk glass. Changes in the UV spectra of the Pb2+ ion are correlated with the formation of the interdiffusion layers, and results show that types of layer have optical basicities significantly greater than that of the glass substrate, through either the high PbO or high Na2O content. 相似文献
72.
This paper presents experimental results from an analysis of two similar games, the repeated ultimatum game and the repeated
best-shot game. The experiment examines whether the amount and content of information given to players affects the evolution
of play in the two games. In one experimental treatment, subjects in both games observe not only their own actions and payoffs,
but also those of one randomly chosen pair of players in the just-completed round of play. In the other treatment, subjects
in both games observe only their own actions and payoffs. We present evidence suggesting that observation of other players'
actions and payoffs may affect the evolution of play relative to the case of no observation.
Received February 1996/Final version April 1998 相似文献
73.
We report a study of the magnetization density in the mixed state of the unconventional superconductor Sr2RuO4. On entering the superconducting state we find no change in the magnitude or distribution of the induced moment for a magnetic field of 1 T applied within the Ru O2 planes. Our results are consistent with a spin-triplet Cooper pairing with spins lying in the basal plane. This is in contrast with similar experiments performed on conventional and high- T(c) superconductors. 相似文献
74.
Insulating GaN is obtained by doping with Be or Li during crystal growth. These impurities form deep acceptors and are responsible for photoluminescence at 2.16 eV for Be, and at 2.23 eV for Li. A 3.15 eV peak is obtained in insulating GaN when Dy-doping is attempted. Weak electroluminescence was obtained in the Be-doped material. 相似文献
75.
76.
Single crystals of LiF and Al are deformed in shear at a number of constant strain-rates in the range 10–4 to 1600 s–1. These constant rate tests are supplemented by a series of jump tests in which a sharp increment in strain rate is imposed during the quasi-static straining. Dislocation arrangements are observed by etch-pits technique for LiF crystals and by TEM for Al crystals. It is shown that cell sizes vary inversely with flow stress and strain-rate sensitivity. 相似文献
77.
78.
J. Duffy 《Experimental Mechanics》1961,1(3):74-82
It is known that birefringent coatings are a powerful experimental technique for the determination of surface strains of metals or other opaque bodies. In this paper the complete state of strain in such a coating is determined for an arbitrary one-dimensional variation of the displacement at the metal surface. It is shown that strain gradients or curvature of the surface have a pronounced effect on the observed birefringence, and must be taken into consideration. This can be done by means of two correction factors derived in the paper which take into account the elastic properties of the coating and its thickness. An experimental procedure is outlined for determining an unknown distribution of strain at the metal surface on the basis of the observed photoelastic pattern. 相似文献
79.
Ilias S. Zouboulis Fuming Jiang Jue WangThomas S. Duffy 《Journal of Physics and Chemistry of Solids》2014
The six independent elastic constants (C11, C12, C13, C33, C44, and C66) of single-crystal MgF2 in the rutile structure have been measured by Brillouin spectroscopy at room temperature from ambient conditions to 7.4 GPa. Measurements were performed on two monocrystals with perpendicular faces, (001) and (100). A quasi-linear fit from finite strain theory was applied to the experimental data revealing the pressure dependence of the six elastic constants of MgF2. The shear modulus CS=1/2(C11−C12), and the aggregate shear (Voigt–Reuss–Hill) modulus G show a softening with increasing pressure, indicating the approach of the rutile-to-CaCl2-type structural phase transition at P~9 GPa. The adiabatic bulk modulus (Reuss average) and its pressure derivative have been determined: K0S=105.1±0.3 GPa, (∂K0S/∂P)T=4.14±0.05. The pressure–volume equation of state of MgF2 was computed self-consistently from the Brillouin data. Our results are in good agreement with X-ray diffraction data. As the phase transition is approached, MgF2 becomes strongly anisotropic and develops partially auxetic behavior (a negative Poisson's ratio in certain directions). 相似文献
80.
Fluorogel Elastomers with Tunable Transparency,Elasticity, Shape‐Memory,and Antifouling Properties
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Dr. Xi Yao Dr. Stuart S. Dunn Dr. Philseok Kim Meredith Duffy Jack Alvarenga Prof. Joanna Aizenberg 《Angewandte Chemie (International ed. in English)》2014,53(17):4418-4422
Omniphobic fluorogel elastomers were prepared by photocuring perfluorinated acrylates and a perfluoropolyether crosslinker. By tuning either the chemical composition or the temperature that control the crystallinity of the resulting polymer chains, a broad range of optical and mechanical properties of the fluorogel can be achieved. After infusing with fluorinated lubricants, the fluorogels showed excellent resistance to wetting by various liquids and anti‐biofouling behavior, while maintaining cytocompatiblity. 相似文献