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991.
992.
This paper presents an optical method based on the interference of light beams of equal path difference for the measurement of the Young's modulus of a micro-beam. An optical wedge which consists of an optical plate and a micro-beam which forms part of a micro-accelerometer is illuminated by a collimated monochromatic sodium light beam. Loading on the micro-beam is accomplished by a loading-pin mounted on a three-axis translation stage and the resulting interference fringe pattern is observed using a CCD camera connected to a computer. Loadings are recorded using a high-sensitive load cell which measures loads of up to 200 g with a resolution of 0.01 g. Test results conducted on micro-beams of different sizes show good repeatability and comparison of the experimental results with theory shows good agreement. 相似文献
993.
Xiqiang Huang Jiang Liu Zhe Lu Wei Liu Li Pei Tianmin He Zhiguo Liu Wenhui Su 《Solid State Ionics》2000,130(3-4):195-201
A series of samples Pr0.6−xSr0.4MnO3 (x=0, 0.01, 0.05, 0.1, 0.15, 0.2) were synthesized by a solid state reaction method. Pr deficiency at the A site has a great effect on the properties of Pr0.6−xSr0.4MnO3 as the cathode of SOFCs (solid oxide fuel cells). Compared to the commonly used La0.6Sr0.4MnO3 and La0.55Sr0.4MnO3 cathode, Pr0.6−xSr0.4MnO3 is better in the properties of conductivity, overpotential and impedance. In all the samples, the one with x=0.05, Pr0.55Sr0.4MnO3, revealed the best performance in the measured temperature range. 相似文献
994.
This paper first describes the basic principles of digital time-integrated shearography in which speckle patterns of laser-illuminated object surfaces subjected to single excitation frequency are recorded over a finite time period. With image subtraction, the resulting phase-change manifests as a visible fringe pattern similar to that in conventional time-average shearography, except that dark areas denote nodal points. When this method is used for evaluating the soundness of joining, the test structure must be excited at or near resonant frequency; this requirement inhibits practical usage for field tests. To alleviate this concern, a new technique that uses a multiple-frequency sweep in digital shearography is proposed. Depending on whether or not phase-shifting by π radians is used during testing, improperly joined surfaces manifest as either a white patch (when phase-shifting is not used) or a dark patch (when phase-shifting is used) on the synthesized intensity map. This map also serves as a diagnostic map for rapid flaw detection. Thus, the user not only can conduct tests with little training provided, but also can very quickly interpret the test results from this map and report on defective areas in the joints. When need arises, the information recorded during testing also enables quantitative analysis of vibration displacements at any point on the test structure. 相似文献
995.
Gregory Morin Maoyu Shang Bradley D. Smith 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):544-545
The title compound, [Ca(C16H12O4)(H2O)6]·H2O, adopts a conformation about the central C—C bond that places the two carboxylate groups in an anti orientation. The crystal consists of layers of two‐dimensional arrays of 2,3‐diphenylsuccinate dianions which are linked by bridging Ca2+ cations. The unit cell contains two Ca2+ cations in an unusual four‐membered Ca—O—Ca—O ring in which the bridging O atoms belong to water molecules rather than carboxylates, i.e. poly[[[di‐μ‐aqua‐bis[pentaaquacalcium(II)]]‐μ‐(meso‐2,3‐diphenylsuccinato‐O:O′)] succinate dihydrate]. 相似文献
996.
A highly stable, versatile, and stimuli-responsive layer-by-layer coating is constructed for mesoporous silica nanoparticles (MSNs) using kinetically trapped host–guest complexation. The ultraslow dissociation kinetics of host–guest complexation ascertains the stability of supramolecular polymeric coating under the complex physiological condition of blood serum. The coating serves as the gatekeeper for nanovalve with zero premature release and the substrate for surface modification with polyethylene glycol or fluorescent dye via host–guest interaction. Under redox stimuli (glutathione), the nanovalve is opened to release the cargo (doxorubicin). The release rate is tunable depending on coating thickness. Polymer coated MSNs are used for the encapsulation and controlled release of doxorubicin in vitro. 相似文献
997.
998.
999.
Ran Zhao Liping Zhu Fangping Cai Zhiguo Yang Xiuquan Gu Jun Huang Ling Cao 《Applied Physics A: Materials Science & Processing》2013,113(1):67-73
We present a new method of synthesizing ZnO/TiO2 core–shell nanowire (NW) arrays for the fabrication of dye-sensitized solar cells (DSSCs). Vertically aligned ZnO NW arrays were obtained on Si substrates, and modified by a TiO2 shell in order to solve the recombination problems via a cost-effective spin-coating method. The structure of the ZnO/TiO2 composite NW arrays was characterized. The experimental results indicate that the TiO2 shell enhances the performance of the DSSCs, through improving the stability of the ZnO NWs and decreasing the recombination of photogenerated electrons on the NW surface. The highest overall conversion efficiency of the cell reaches about 3.0 %. 相似文献
1000.
无铅弛豫铁电体具有较好的介电可调性,在顺电相有较大的介电常数和极小的损耗,因较大的优值而被广泛地用于微波器件.根据现有的介电可调性理论,通过参量的适当修正,对介电可调性的表达式做了合理的探讨,结论适用于处理实验结果.比较发现,在电场作用下顺电相保持不变的近似得出的结论与实验结果差距较大,而转化为铁电相与实验结果完全吻合.考虑外加电场和自发极化对弹性吉布斯自由能的修正,导出了高电场对介电常数的修正关系,与实验结果相符.提出了介电可调度的概念与计算公式,能够定量表示掺杂对介电可调性的影响. 相似文献