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排序方式: 共有546条查询结果,搜索用时 15 毫秒
51.
A series of soluble aromatic polyesters (polyarylates) containing arylene sulfone ether linkages and having inherent viscosities of 0.36–1.10 dl/g were prepared by the two-phase low temperature polycondensation of 4,4′-[sulfonyl-bis(p-phenyleneoxy)]dibenzoyl chloride and 3,3′-[sulfonylbis(p-phenyleneoxy)]-dibenzoyl chloride with various bisphenols in an organic solvent-aqueous alkaline solution system in the presence of a phase transfer catalyst. Bisphenols 4,4′-[sulfonylbis(p-phenyleneoxy)]diphenol and 3,3′-[sulfonylbis(p-phenyleneoxy)]-diphenol were synthesized in quantitative yields by an improved procedure. The aromatic polyesters prepared were characterized by infrared spectroscopy, elemental analysis, solution viscosity, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction. The polyesters prepared had glass transition temperatures in the range 150–230°C and initial decomposition temperatures of 397–491°C. They gave transparent, tough and flexible films by the solution casting technique. 相似文献
52.
Ahmad Zuhairi Abdullah Mohamad Zailani Abu Bakar Subhash Bhatia 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(9):1016-1025
The performance of H‐ZSM‐5‐supported bimetallic catalysts with chromium as the base metal in the combustion of ethyl acetate and benzene is reported. A reactor operated from 100 to 500 °C at a gas hourly space velocity (GHSV) of 32 000 h?1 was used for study of the activity. A combination of 1.0 wt% chromium and 0.5 wt% copper yielded a catalyst (Cr1.0Cu0.5/Z) with improved conversion and carbon dioxide yield. Cr2O3 (Cr3+) and CuO (Cu2+) were the predominant metal species in the catalyst. In agreement with the Mars–van Krevelen model, improved reducibility of Cr3+ in the presence of Cu2+ led to an improvement in activity. The copper content in Cr1.0Cu0.5/Z also favored the formation of deep combustion products. Condensation and subsequent growth of coke precursors in the catalyst pores led to the formation of a softer and less aromatic coke fraction while dehydrogenation activity on acid sites formed a harder and more aromatic coke fraction. The use of Cr1.0Cu0.5/Z favored the formation of lower molecular weight intermediates, leading to reduction in formation of softer coke. Copyright © 2005 Society of Chemical Industry 相似文献
53.
A Fortran IV computer program was developed to calculate the composition at equilibrium of products from a single-stage coal gasification process involving coal, H2 and steam. This program was used to develop equilibrium concentration profiles for various components and heating values of dry product gas as a function of temperature, pressure and percentage steam in a hydrogen-steam mixture feed gas. Based on the results, a useful range for the variables, from the thermodynamic point of view, has been established. 相似文献
54.
Subhash Chandra 《Nuclear Engineering and Design》1983,74(2):293-297
The present paper discusses some numerical simulations of two phase dispersed droplet flows obtained with an accident analysis code ANEXDI which employs an algorithm based on the implicit multi-field (IMF) method. The numerical solutions have been found to remain stable up to a moderate volume fraction of the incompressible droplets. The results so obtained compare well with the ones obtained with the computer code SIMMER-II and with an analytical formula for shock speed. The viscosity and drag terms which are often retained only for numerical considerations have been observed to affect flow variables profiles. Often neglected transient force flow terms have been observed to stabilize sometimes numerical results, which are otherwise unstable. 相似文献
55.
Temperature on the machined surface is critical for surface integrity and the performance of a precision component. However,
the temperature of a machined surface is challenging for in-situ measurement. Furthermore, the individual contribution of
tool/work friction and plastic deformation of work materials to surface temperature is very difficult to quantify because
the measured temperature is always the resultant temperature. This lack of understanding on the temperature distribution blocks
the design of effective cutting tool geometries and materials to minimize surface temperature. This study provides a finite
element method based on a predictive model to decouple the contributions of tool/work friction and material plastic deformation
to surface temperature in a dry cutting process. The study shows that the plastic deformation of work material contributes
to the majority of surface temperature, whereas the tool/work friction contribution is secondary. High temperatures are produced
when more materials are plowed under the cutting edge. A large tool/work friction leads to higher surface temperatures, and
the use of a cutting tool with physical properties in process simulation significantly improves the accuracy of predicted
surface temperatures. Residual stress reversal from subsurface maximum residual to surface maximum residual stress may occur
when tool/work friction increases. 相似文献
56.
Subhash Chandra Ghosh Senthilkumar Muthaiah Yao Zhang Xiangya Xu Soon Hyeok Hong 《Advanced Synthesis \u0026amp; Catalysis》2009,351(16):2643-2649
Amides are synthesized directly from alcohols and amines in high yields using an in situ generated catalyst from easily available ruthenium complexes such as the (p‐cymene)ruthenium dichloride dimer, [Ru(p‐cymeme)Cl2]2, or the (benzene)ruthenium dichloride dimer, [Ru(benzene)Cl2]2, an N‐heterocyclic carbene (NHC) ligand, and a nitrogen containing L‐type ligand such as acetonitrile. The phosphine‐free catalyst systems showed improved or comparable activity compared to previous phosphine‐based catalytic systems. The in situ generated catalyst from [Ru(benzene)Cl2]2, an NHC ligand, and acetonitrile showed excellent activity toward reactions with cyclic secondary amines such as piperidine and morpholine. 相似文献
57.
Banerjee Sanchari Padhan Subhash Thangavel R. 《Journal of Materials Science: Materials in Electronics》2022,33(12):9277-9288
Journal of Materials Science: Materials in Electronics - Limited light absorption and acute charge recombination on the surface of ZnO nanostructure-based photoelectrodes are the basic challenges... 相似文献
58.
In this article, we have studied the effect of carbonaceous nanofillers viz. fullerenol (0D), carboxylated multi-wall carbon nanotube (MWCNT, 1D), hydroxylated graphene (2D) and combination of carboxylated CNT and hydroxylated graphene as 3D in thermoplastic polyurethane on the tensile properties of the fabricated cellular structures. The concentration of nano-fillers was varied as 0.1, 1, and 5 wt%. Tensile properties of the nanocomposite cellular structures were measured as per ASTM D882 at 20°C (below glass transition temperature, Tg) and 40°C (above Tg). The results have shown that the tensile strength was found to increase by 200%–300% and the tensile modulus was found to increase by 150%–300% for 2D and 3D nano-fillers while significantly poor results were observed for 0D. However, the test data tensile strength and modulus showed marginal increase at 20°C and marginally low at 40°C for 1D filler. The interfacial adhesion was calculated by using experimental tensile data and the predictive models. The interfacial adhesion parameter (Bσ) calculated using Pukanszky equation was found significantly higher value for 2D (Bσ20 = 195.8) and 3D (Bσ20 = 192.0) fillers while poor adhesion was observed for 0D (Bσ20 = −81.6) fillers. The developed cellular structured materials were also evaluated by attenuated total reflection Fourier transform IR spectra, differential scanning calorimetry, X-ray diffraction, scanning electron microscope, and transmission electron microscope. 相似文献
59.
60.
Nan Huang Beibei Han Yudong Wang Yuanyuan Li Yu Su Wanbing Guan Xiaodong Zhou Maorong Chai Subhash C. Singhal 《International Journal of Hydrogen Energy》2021,46(38):20078-20086
The dependence of interfacial contact resistance (ICR) on contact materials between cathode and interconnect is systematically studied under both isothermal oxidation and thermal cycling conditions. Three kinds of cathode current-collecting layer (CCCL) are used, (La,Sr) (Co,Fe)O3 (LSCF), LSCF+10%Ag, and Ag, and tested in a SUS430/CCCL/SUS430 sandwich structure to simulate the actual operation of the solid oxide fuel cells (SOFCs). Experimental results show that the ICR of LSCF+10%Ag exhibits the smallest value, in comparison with the specimens with LSCF and Ag paste, as well as the sample without a CCCL. For LSCF+10%Ag contact, the ICR increases from 0.0069 mΩ cm2 to 3.74 mΩ cm2 under an isothermal condition for 150 h, then increases from 3.74 mΩ cm2 to 10.79 mΩ cm2 after 15 thermal cycles. This work provides information for the understanding of possible mechanisms of performance degradation of SOFCs. 相似文献