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991.
992.
AbstractWe report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ~190 nm. Taking advantage of the ‘direct writing’ feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices. 相似文献
993.
994.
MQ silicone resins, which represent a broad range of hydrolytic condensation products of monofunctional silane (M) and tetrafunctional silane (Q), were synthesized by reaction of water glass with hexamethyldisiloxane. The optimum reaction time and the optimal reaction temperature is 30 min and 30–40°C, respectively. Concentrated hydrochloric acid is the best one among those catalysts tested. In large-scale experiments (420–1680 mL), the favorable feeding order is catalyst first, and then water glass, the mixture of hexamethyldisiloxane and ethanol last and most MQ silicone resin was observed. The structure of MQ silicone resin was characterized by FT-IR and GPC spectra. The MQ silicone resin shows narrow molecular weight distribution and the number average molecular weight of MQ silicone resin is 2917. The silicone pressure sensitive adhesive prepared from as-synthesized MQ resin has good tack (29#) and 180° peel adhesion (5.630N/20 mm). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
995.
《International Journal of Hydrogen Energy》2014,39(36):21470-21479
Proton exchange membrane fuel cell (PEMFC) has attracted considerable interest because of its superb performance, and many researches are focused on the development of high-performance, long-life bipolar plates. Stainless steel bipolar plates offer many advantages over the conventional graphite bipolar plates, such as low material and fabrication cost, excellent mechanical behaviour and ease of mass production. However, the insufficient corrosion resistance and relatively high interfacial contact resistance (ICR) become the major obstacles to the widespread use of stainless steel bipolar plates. In this work, active screen plasma nitriding (ASPN), a novel plasma nitriding technique, was used to modify the surface of 316 austenitic stainless steel. A variety of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), glow discharge optical emission spectrometer (GDOES), were employed to characterize the nitrided samples. The results reveal that a nitrogen supersaturated S-phase layer has been successfully produced on the surface of all nitrided 316 stainless steel samples. The interfacial contact resistance (ICR) value can be decreased dramatically after ASPN treatment and the corrosion resistance can also been improved. In addition, better corrosion resistance can be achieved by active screen plasma nitriding with a stainless steel screen than with a carbon steel screen. This technique could be used to improve the performance and lifespan of bipolar plates for fuel cells. 相似文献
996.
针对典型工业挥发性有机物(VOC)甲苯设计一套冷凝法回收系统。该系统制冷部分采用冰箱系统常用的分立多循环结构,将回收流程分为预冷级和冷却级。运用物性软件REFPROP及通用流程模拟软件Aspen Plus对甲苯负荷及制冷流程进行模拟。通过对系统的模拟运行,研究该冷凝法甲苯回收系统的工作性能以及能耗影响因素,为系统的进一步设计优化提供理论依据。 相似文献
997.
Antje Grünewald-LükeHermann Gies Ulrich MüllerBilge Yilmaz H. ImaiTakashi Tatsumi B. XieFeng-Shou Xiao Xinhe BaoWeiping Zhang Dirk De Vos 《Microporous and mesoporous materials》2012,147(1):102-109
Condensation of layered silicate precursors leads to new, all silica zeolite frameworks. In order to introduce catalytic functionality, boron has been substituted into the silicate layer of RUB-39 in a single step synthesis process. Condensation of the silicate layer to the zeolite framework of RUB-41, RRO framework structure type, preserved B as constituent of the material. Analysis of structural details obtained from Rietveld analysis of powder diffraction data, 11B and 29Si NMR experiments of the as synthesized precursor as well as of the zeolite condensation product, and crystal chemical reasoning indicates segregation of B on one specific T-site. This T-site is buried in the silicate anionic layer of the precursor shielding the additional negative charge introduced by the trivalent T-atom. 相似文献
998.
999.
1000.
采用双向循环恒刚度剪切试验对预制桩的侧阻退化效应进行试验研究。研究显示,剪切应力(摩阻力)随剪切循环数的增加呈指数型衰减,衰减主要发生在开始的部分循环内,约 25 个循环后基本达到稳定。剪切过程中剪切带发生明显的剪缩,导致法向应力释放,此为摩阻力退化的 原因之一 。随剪切循环数的增加界面摩擦角发生指数型退化直至达到残余值,此为摩阻力退化的另一原因。法向刚度的大小决定剪切应力、法向应力和界面摩擦角衰减的速度和幅度,法向刚度越大,衰减越快且残余值越小。恒刚度剪切试验说明桩土界面摩擦力的退化与桩周土的坚硬程度密切相关,土体越硬则侧阻退化现象越明显。 相似文献