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排序方式: 共有3582条查询结果,搜索用时 531 毫秒
981.
V. Siva Reddy N. L. Panwar S. C. Kaushik 《Clean Technologies and Environmental Policy》2012,14(1):47-53
This communication deals with the exergetic analysis of a vapour compression refrigeration system with selected refrigerants.
The various parameters computed are COP and exergetic efficiency in the system. Effects of degree of condenser temperature,
evaporator temperature and sub-cooling of condenser outlet, supper-heating of evaporator out let and effectiveness of vapour
liquid heat exchanger are also computed and discussed. In this study, it was found that R134a has the better performance in
all respect, whereas R407C refrigerant has poor performance. 相似文献
982.
In the present study, highly dispersed copper promoted bimetallic nanocomposite oxides with superior catalytic performance for vapor phase chemoselective hydrogenation of ortho-chloro-nitrobenzene were successfully prepared by deposition–precipitation and impregnation methods and characterized using different techniques. XRD and TPR results revealed the presence of small and extremely well dispersed metal oxide particles over the high surface area ceria–silica support. TEM analysis confirmed existence of nanocrystals with an average particle size of 7 nm. Among different catalysts employed, CuO–NiO/CS exhibited high conversion (96.6%), high product selectivity (98%), and excellent stability. 相似文献
983.
Chihliang Chang Ssu‐Hsien Li Raju Jannapu Reddy Kwunmin Chen 《Advanced Synthesis \u0026amp; Catalysis》2009,351(9):1273-1278
984.
K. Raju S. Manjunathrao P. Venugopal Reddy 《Journal of Low Temperature Physics》2012,168(5-6):334-349
To understand the structural, electrical, magnetic, elastic and anelastic properties of La0.67?x Eu x Sr0.33MnO3 (0.30≤x≤0.39) manganites, a series of samples was prepared by citrate gel route. X-ray diffraction studies along with Rietveld analysis indicate the samples crystallize in single phase with Pnma space group. Studies on the variations of magnetization with temperature indicate that the Curie transition temperature (T C) decreases with increasing Eu content. Furthermore, Eu substitution is found to increase the electrical resistivity and significantly enhances the colossal magnetoresistance effect, while it is found to decrease the characteristic metal–insulator transition temperature (T P). On analyzing the electrical resistivity data, it has been concluded that the resistivity below T P can be explained based on electron–electron, electron–phonon and two magnon scattering processes, while that above T P, the adiabatic small polaron model is found to explain the observed behavior. Finally, the longitudinal modulus (L) and internal friction (Q ?1) have been measured and a dramatic change in L (T) is observed at T C, accompanied by a sharp peak in Q ?1 (T). Simultaneous occurrence of magnetic, transport and lattice anomalous behavior at T C indicate the presence of strong electron–phonon and spin–phonon interactions in these manganites. 相似文献
985.
K. Bhargavi M. Srinivasa Reddy P. Raghava Rao N. Narasimha Rao M. Sundara Rao V. Ravi Kumar N. Veeraiah 《Materials Research Bulletin》2012,47(2):267-273
Optical absorption and photoluminescence characteristics of Sm3+ ions in lead silicate glasses mixed with different concentrations of Al2O3 (5–10 mol%) have been investigated. From these studies, the radiative properties viz., spontaneous emission probability A, the total emission probability, the radiative lifetime τR, the fluorescent branching ratio β of emission transition of 4G5/2 → 6H7/2 along with other transitions for Sm3+ have been evaluated and found to be the highest for the glass mixed with 8.0 mol% of Al2O3.The IR spectral studies have indicated that Al3+ ions do participate in the glass network with AlO4 and AlO6 structural units and further revealed that the concentration of octahedral aluminium ions induce bonding defects in the glass network. Such bonding defects are assumed to be responsible for low phonon losses in these glasses and lead to higher values of radiative parameters for the glass mixed with 8.0 mol% of Al2O3. 相似文献
986.
Reddy MC Hossner KL Belk KE Scanga JA Yemm RS Sofos JN Smith GC 《Journal of food protection》2006,69(8):1966-1970
This study was conducted to determine optimal buffer pH, extraction procedure, and temperature for detecting central nervous system (CNS) tissue on meat surfaces and on carcass-splitting band saw blades using swab sampling. Glial fibrillary acidic protein (GFAP) is restricted to CNS tissue and has been used as a marker for CNS tissue presence in meat products. Sample preparation, extraction procedure, and extraction temperature of glial fibrillary acidic protein fluorescent enzyme-linked immunosorbent assay (GFAP F-ELISA) were modified to detect CNS tissue on meat surfaces and on carcass-splitting band saw blades. Maximum GFAP recovery was observed with an extraction buffer pH of 7.4. Extracting samples at room temperature by vortexing for 30 s in 1 ml of extraction buffer (phosphate-buffered saline [pH 7.4] plus 0.05% sodium dodecyl sulfate) consistently provided detection of GFAP on meat surfaces contaminated with 500 microg of spinal cord suspension per 50 cm2 and on carcass-splitting band saw blades contaminated with 20 microg of spinal cord suspension per 50 cm2. Recovery of GFAP was not affected by storing samples overnight at 4 degrees C. The current studies demonstrate the effectiveness of modified sampling procedures and preparations, sample extraction buffer pH, and extraction temperatures. These modifications introduced to the original F-ELISA sampling protocol result in asensitive and repeatable assay for detection of CNS tissue on meat surfaces and on carcass-splitting band saw blades. 相似文献
987.
988.
K.T. Ramakrishna Reddy N. Koteswara Reddy R.W. Miles 《Solar Energy Materials & Solar Cells》2006,90(18-19):3041-3046
Polycrystalline thin films of tin sulphide have been synthesised using spray pyrolysis. The layers grown at a temperature of 350 °C had the orthorhombic crystal structure with a strong (1 1 1) preferred orientation. The films had resistivities 30 Ω cm with an optical energy band gap (Eg) of 1.32 eV. Heterojunction solar cells were fabricated using sprayed SnS as the absorber layer and indium doped cadmium sulphide as the window layer and the devices were characterised to evaluate the junction properties as well as the solar cell performance. The current transport across the junction has been modelled as a combination of tunnelling and recombination. The best devices had solar conversion efficiencies of 1.3% with a quantum efficiency of 70%. 相似文献
989.
990.
Narendra Reddy 《Polymer》2005,46(15):5494-5500
We have developed a fiber extraction method that produces fibers from cornstalks with mechanical properties similar to that of the common textile fibers. The fiber extraction method developed results in partial delignification and produces fibers from cornstalks that are suitable for textile and other industrial applications. The structure of the fibers obtained was investigated using X-ray diffraction and scanning electron microscope. The structure and composition of the natural cellulose fibers obtained from cornstalks are different than that of the common bast fibers such as flax and kenaf. Tensile properties of the fibers were studied using an Instron tensile tester. This study found that cornstalk fibers have relatively lower percent crystallinity but similar microfibrillar angle as that of the common bast fibers. The structure and properties of cornstalk fibers indicate that the fibers are suitable for producing various textile products. 相似文献