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1.
A. Sadananda Chary S. Narender Reddy T. Chiranjivi 《Journal of Materials Science》1989,24(6):2199-2202
Dielectric properties, dielectric constant (k), dielectric loss (tan δ) and a.c. conductivity (σ) in the solution-grown single crystals of RbNO3 are presented from room temperature to about 200°C covering the frequency range 102 to 105 Hz. A broad peak observed in tan δ-frequency data between 103 and 105Hz is thought to be due to impurity-vacancy dipoles. The sudden rise of three parameters near 160°C is attributed to the known
phase transition from trigonal to CsCl structure. 相似文献
2.
The aim of the present paper is to review the recent progress in the synthesis of in situ particle reinforced aluminum composites
using thermal, mechanical and combined mechanical-thermal activation of aluminothermic reduction reactions. The combination
of combustion synthesis (CS) and mechanosynthesis (MS) is the most recent development in the processing of advanced materials
like micro and nano aluminum based composites. The combined mechanical thermal synthesis (MTS) has widened the possibilities
for both CS and MS. MTS holds great potential for commercial viability and offers exciting processing route for the synthesis
of advanced materials. Enhanced reaction kinetics and extended concentration limits in MTS are demonstrated by illustrating
the synthesis of aluminum based nanocomposite involving Al–CeO2. 相似文献
3.
K Madhusudan Reddy Sunkara V Manorama R.D.K Misra 《Materials Research Bulletin》2004,39(10):1491-1498
A comparative study of gas sensing behavior of nanocrystalline nickel ferrite synthesized by micro-emulsion and hydrothermal method to liquefied petroleum gas (LPG) is presented. Nanocrystalline nickel ferrite synthesized by hydrothermal method indicated higher electrical conductivity and gas sensitivity at low operating temperature compared to nanocrystalline nickel ferrite synthesized by reverse micelle technique. This difference in the gas sensing behavior can be attributed to the presence of more oxygen vacancies (i.e. non-stoichiometry) in the hydrothermally synthesized nickel ferrite. Incorporation of palladium had a catalytic effect and the operating temperature was significantly reduced in both the samples. The higher operating temperature of the reverse micelle nickel ferrite material makes the sensor response speed faster (∼10 s) compared to the hydrothermally synthesized material (∼1 min). 相似文献
4.
5.
EG Mdurvwa JI Alak GE Pimentel-Smith HS Gakou S Kolavala H Abdelrahman PG Reddy 《Canadian Metallurgical Quarterly》1997,43(7):1039-1044
The LP-BM5 murine leukemia virus causes acquired immunodeficiency syndrome in C57BL/6J mice (MAIDS), similar to that of AIDS in humans. The objective of this study was to determine the effect of LP-BM5 viral infection on cellular activation and membrane integrity of splenocytes. Oxidative burst in splenocytes in response to exposure to PMA (20 microg/ml) was significantly higher (p<.02) in infected than in control mice at two weeks post-infection using luminol-enhanced chemiluminescence. By 13 weeks post-infection superoxide anion production in infected mice was significantly lower when compared to controls coinciding with decreased proliferative response to mitogens. The extent of cell membrane damage as indicated by lactic dehydrogenase (LDH) activity in serum was significantly higher in infected than in control mice (p<.001). The results from this study suggests that LP-BM5 virus causes an initial stimulation of cellular activity followed by a decreased cell activation characterized by decreased proliferation of splenocytes and decreased oxygen radical production. Decreased cell membrane integrity indicated by increased LDH activity may partly be responsible for these changes. 相似文献
6.
K. T. Ramakrishna Reddy R. W. Miles 《Journal of Materials Science: Materials in Electronics》2003,14(9):529-532
Small-area polycrystalline CuGa
x
In1–x
Se2-based solar cells produced in the laboratory have been reported with efficiencies up to 18.8%. This success at achieving high-efficiency devices has stimulated a parallel research effort to produce large-area modules based on the use of CuGa
x
In1–x
Se2 with reduced cost of production. One method that has potential to achieve these objectives is chemical spray pyrolysis. Preliminary studies have resulted in devices with efficiencies of 4–5%. Further improvements toward implementing higher-efficiency devices are expected to result from a better understanding of the physical and chemical properties of the chalcopyrite layers produced. In this work we have investigated, for the first time, the properties of these layers using X-ray photoelectron spectroscopy (XPS) to identify the secondary phases and residual impurities present. The layers studied were for In/Ga mole ratios of x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 in CuGa
x
In1–x
Se2. The layers were also profiled by sputter etching away the surface of the layers and repeating the XPS measurements. The effects of annealing the layers in air, vacuum, and selenium vapor were also investigated. 相似文献
7.
A modal expansion method is used with the reciprocity and Poynting theorems to derive the admittance of inclined slots cut in the metal wall of a nonradiating dielectric (NRD) waveguide. Theoretical values of normalised conductance and susceptance are compared with previously reported experimental results and are found to be in good agreement.<> 相似文献
8.
Adherent and pin-hole free amorphous Sb2Te3 thin films have been obtained by vacuum evaporation at substrate temperatures ≤25 °C. The films have been crystallized by thermal and laser annealing, and the crystallization processes monitored as a function of annealing temperature and laser scan speed. A comparative study of topography reveals disk-shaped crystallized areas in thermal crystallization and dendrite growth in the laser induced process. The crystallized films in both cases contain a single Sb2Te3 phase. Activation energy of 2 eV for crystallization, determined using differential scanning calorimetery indicates good room temperature stability of the amorphous states. 相似文献
9.
A. S. S. R. Reddy 《Canadian Metallurgical Quarterly》1992,5(1):70-78
The dynamic analysis and control system design of large space structures involve the solution of the large‐dimensional generalized matrix eigenvalue problem. The computational effort involved is proportional to the third power of the dimension of the matrices involved. To minimize the computational time a graph‐theory approach to reduce a matrix to lower‐ordered submatrices is proposed. The matrix‐reduction algorithm uses the Boolean matrices corresponding to the original numerical matrices and, thus, the computational effort to reduce the original matrix is nominal. The computational savings directly depend upon the number of submatrices into which the original matrix is reduced. A free‐free square plate is considered as an example to illustrate the technique. In this example a matrix of 16th order is reduced to three scalars corresponding to three rigid‐body modes, and three matrices of order three and one matrix of order four. 相似文献
10.
A. A. Arafa Rama Subba Reddy Gorla 《International Journal of Engineering Science》1992,30(12):1745-1751
An analysis is presented to investigate the effects of buoyancy and curvature on convection along vertical cylinders and needles placed in a micropolar fluid. The governing equations for momentum, angular momentum and energy are solved numerically by finite difference scheme. The heat transfer results are presented for a range of values of the buoyancy parameters, the curvature parameter and the material parameters of the fluid. The effect of the microrotation boundary conditions on heat transfer is discussed. 相似文献