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151.
This work presents an analytical approach to investigate the mechanical and thermal buckling of functionally graded materials sandwich truncated conical shells resting on Pasternak elastic foundations, subjected to thermal load and axial compressive load. Shells are reinforced by closely spaced stringers and rings, in which the material properties of shells and stiffeners are graded in the thickness direction following a general sigmoid law distribution and a general power law distribution. Four models of coated shell-stiffener arrangements are investigated. The change of spacing between stringers in the meridional direction also is taken into account. Two cases on uniform temperature rise and linear temperature distribution through the thickness of shell are considered. Using the first-order shear deformation theory, Lekhnitskii smeared stiffener technique and the adjacent equilibrium criterion, the linearization stability equations have been established. Approximate solution satisfies simply supported boundary conditions and Galerkin method is applied to obtain closed-form expression for determining the critical compression buckling load and thermal buckling load in cases uniform temperature rise and linear temperature distribution across the shell thickness. The effects of temperature, foundation, core layer, coating layer, stiffeners, material properties, dimensional parameters and semi-vertex angle on buckling behaviors of shell are shown. 相似文献
152.
通过实例分析指出,由于运行不当会在密封瓦外建立起大循环油路进而使空一氢侧油箱间产生大量窜油,由此造成氢气纯度迅速下降,并给出了解决此类故障的具体建议及操作方案。 相似文献
153.
Navaneethan Muthuswamy Jose Luis Gomez de la Fuente Dung T. Tran John Walmsley Mikhail Tsypkin Steinar Raaen Svein Sunde Magnus Rønning De Chen 《International Journal of Hydrogen Energy》2013
The present work presents a method to encapsulate pre-synthesised Ru nanoparticles (NPs) by Pt using a polyol method without capping agents at various pH values (6, 7, 8 and 10). The structural and surface properties of the catalysts were characterised using X-ray diffraction, transmission electron microscopy, CO stripping, and energy-dispersive X-ray spectroscopy. The studies suggest that the pH during encapsulation of Ru by Pt plays an important role in controlling of shell composition. A core–shell catalyst with an alloy shell was obtained at a pH of 6, whereas a monometallic Pt shell was obtained at a pH of 10. The core–shell catalysts gave higher steady-state current for methanol oxidation: 10-fold higher for alloy shells and 5-fold higher for Pt-enriched shells compared to the pure Pt catalyst. It is suggested that the highest catalytic enhancement of the core–shell catalysts is obtained through the bi-functional character that dominates the alloy shells rather than the ligand-effect-promoted Pt-enriched shells. 相似文献
154.
Sung Ho Ha Sang Hyun Lee Dung Thanh Dang Min Sik Kwon Woo-Jin Chang Yong Jae Yu Il Suk Byun Yoon-Mo Koo 《Korean Journal of Chemical Engineering》2008,25(2):291-294
The activity and stability of lipase from Candida antarctica were investigated in the kinetic resolution of (R,S)-1-phenylethanol with vinyl acetate using ionic liquids (ILs) as reaction media. Among ILs tested, the highest activity of
lipase was observed in [Edmim][Tf2N]. In hydrophobic ILs such as [Edmim][Tf2N], [Emim][Tf2N] and [Pmim] [PF6], lipase could retain its activity after 5 times reuse, while the activity of lipase in hydrophilic ILs and organic solvents
was drastically decreased. The activities of lipase in [Edmim][Tf2N], [Emim][Tf2N] and [Pmim][PF6] were also well maintained after 1 day incubation at 80 °C. The lipase suspended in [Edmim][Tf2N] could be successfully reused 6 times without loss of activity. 相似文献
155.
Liu J Erassov A Halina P Canete M Nguyen DV Chung C Cagney G Ignatchenko A Fong V Emili A 《Analytical chemistry》2008,80(20):7846-7854
Tandem mass spectrometry is the prevailing approach for large-scale peptide sequencing in high-throughput proteomic profiling studies. Effective database search engines have been developed to identify peptide sequences from MS/MS fragmentation spectra. Since proteins are polymorphic and subject to post-translational modifications (PTM), however, computational methods for detecting unanticipated variants are also needed to achieve true proteome-wide coverage. Different from existing "unrestrictive" search tools, we present a novel algorithm, termed SIMS (for Sequential Motif Interval Search), that interprets pairs of product ion peaks, representing potential amino acid residues or "intervals", as a means of mapping PTMs or substitutions in a blind database search mode. An effective heuristic software program was likewise developed to evaluate, rank, and filter optimal combinations of relevant intervals to identify candidate sequences, and any associated PTM or polymorphism, from large collections of MS/MS spectra. The prediction performance of SIMS was benchmarked extensively against annotated reference spectral data sets and compared favorably with, and was complementary to, current state-of-the-art methods. An exhaustive discovery screen using SIMS also revealed thousands of previously overlooked putative PTMs in a compendium of yeast protein complexes and in a proteome-wide map of adult mouse cardiomyocytes. We demonstrate that SIMS, freely accessible for academic research use, addresses gaps in current proteomic data interpretation pipelines, improving overall detection coverage, and facilitating comprehensive investigations of the fundamental multiplicity of the expressed proteome. 相似文献
156.
In this study, we prepared magnetic iron oxide and gold/iron oxide nanoparticles (NPs) and characterized their morphologies and properties by XRD, TEM, EDX, VSM and UV-vis measurements. The magnetite iron oxide NPs of 10 nm were synthesized by coprecipitation of Fe2+ and Fe+3 in the solution of NH4OH and then they were used as seed particles for the subsequent growth to prepare the magnetite NPs of different particle sizes and also to prepare gold/iron oxide composite NPs. All those magnetite NPs are superparamagnetic and the gold/iron oxide composite NPs combine the optical and magnetic properties, which are contributed by gold and iron oxide components, respectively. 相似文献
157.
Dinh Xuan Loc Tran Thi Kim Chi Tran Thu Huong Nguyen Vu Tran Kim Anh Wieslaw Strek Le Quoc Minh 《中国稀土学报(英文版)》2011,(12):1147-1151
Core/shell structured CePO4:Tb(III) @LaPO4 and CePO4:Tb(III) were successfully synthesized in tris(2-ethylhexyl) phosphate(TEHP) and diethylene glycol(DEG) solvents for comparison of the two techniques in open air and closed reaction vessel.Morphology and crystal structure of the core/shell nanophosphors were determined by using X-ray diffraction(XRD) and transmission electron microscopy(TEM) ,which showed that nanophosphors had diameter of about 5-10 nm with the monoclinic monazite phase.The nanophosphors ... 相似文献
158.
Cr2AlC compounds were synthesized by a powder metallurgical route and corrosion tested at 900, 1000, 1100 and 1200 °C for up to 150 h under an Ar/1% SO2 gas atmosphere. The compounds were resistant to corrosion because a thin ??-Al2O3 barrier layer quickly formed on the surface which suppressed sulfidation. Virtually no sulfur was detected inside the scale except during the initial corrosion stage. The superior corrosion resistance of Cr2AlC originated from the high affinity of Al for oxygen to form the thermodynamically stable Al2O3. Unlike Al, Cr was not active because Cr was strongly bound to carbon as Cr2C layers in Cr2AlC. The small amount of Cr2O3 that had formed was dissolved in the Al2O3 layer. The corrosion of Cr2AlC resulted in the formation of an ??-Al2O3 layer and an underlying Cr7C3 layer. 相似文献
159.
A conventional and general route has been exploited to the high yield synthesis of many kinds of highly crystalline metal oxide and mixed oxide nanocrystals with different morphologies including belt, rod, truncated-octahedron, cubic, sphere, sheet via the hydrothermal reaction of inorganic precursors in aqueous solution in the presence of bifunctional 6-aminohexanoic acid (AHA) molecules as a capping agent. This method is a simple, reproducible and general route for the preparation of a variety of high-crystalline inorganic nanocrystals in scale-up. The shape of inorganic nanocrystals such as CoWO(4), La(2)(MoO(4))(3) can be controlled by simply adjusting the synthesis conditions including pH solution and reaction temperature. Further, by tuning precursor monomer concentration, the mesocrystal hierarchical aggregated microspheres (e.g., MnWO(4), La(2)(MoO(4))(3)) can be achieved, due to the spontaneous assembly of individual AHA-capped nanoparticles. These obtained AHA-capped nanocrystals are excellent supports for the synthesis of a variety of hybrid metal/oxide nanocrystals in which noble metal particles are uniformly deposited on the surface of each individual nanosupport. The photocatalytic activity of Ag/TiO(2) nanobelts as a typical hybrid photocatalyst sample for Methylene Blue degradation was also studied. 相似文献
160.
Hoang T. Dinh Chonho Lee Dusit Niyato Ping Wang 《Wireless Communications and Mobile Computing》2013,13(18):1587-1611
Together with an explosive growth of the mobile applications and emerging of cloud computing concept, mobile cloud computing (MCC) has been introduced to be a potential technology for mobile services. MCC integrates the cloud computing into the mobile environment and overcomes obstacles related to the performance (e.g., battery life, storage, and bandwidth), environment (e.g., heterogeneity, scalability, and availability), and security (e.g., reliability and privacy) discussed in mobile computing. This paper gives a survey of MCC, which helps general readers have an overview of the MCC including the definition, architecture, and applications. The issues, existing solutions, and approaches are presented. In addition, the future research directions of MCC are discussed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献