排序方式: 共有59条查询结果,搜索用时 31 毫秒
1.
P. Prathap N. Revathi Y.P.V. Subbaiah K.T. Ramakrishna Reddy R.W. Miles 《Solid State Sciences》2009,11(1):224-232
Al-doped ZnS films were deposited using close-spaced evaporation of the powders synthesized by chemical precipitation method. The films were prepared for different Al concentrations in the range 0–10 at.% on glass substrates kept at 300 °C. The effect of Al-doping on ZnS composition, microstructure and optoelectronic properties of as-grown ZnS layers was determined using appropriate techniques. The films were polycrystalline and showed (111) preferred orientation for all the doping concentrations in spite of an additional phase of Al2S3 observed at higher dopant levels. The surface morphological studies indicated that the Al incorporation had a considerable effect on the surface roughness of the films. The optical measurements indicated that the optical energy band gap decreased slightly with the increase of dopant concentration without affecting the optical transmittance characteristics significantly. The electrical analysis indicated that the resistivity of the layers changed significantly with the doping concentration in the layers. The change of photoluminescence behaviour of the as-grown ZnS:Al films with dopant concentration was also studied. 相似文献
2.
M.?S.?MalashettyEmail author J.?C.?Umavathi J.?Prathap Kumar 《Heat and Mass Transfer》2004,40(11):871-876
Convective flow and heat transfer in an inclined channel bounded by two rigid plates held at constant different temperatures with one region filled with porous matrix saturated with a viscous fluid and another region with a clear viscous fluid different from the fluid in first region is studied analytically. The coupled nonlinear governing equations are solved using regular perturbation method. It is found that the presence of porous matrix in one of the region reduces the velocity and temperature. Results have been presented for a wide range of governing parameters such as Grashof number, porous parameter, angle of inclination, ratio of heights of the two layers and also the ratio of viscosities. 相似文献
3.
Prathap Chandran S Mondiot F Mondain-Monval O Loudet JC 《Langmuir : the ACS journal of surfaces and colloids》2011,27(24):15185-15198
The anchoring of liquid-crystal (LC) mesogens to the surfaces of colloids is an important factor in determining intercolloidal interactions and the symmetry of the ensuing colloidal assembly in nematic colloids. The dynamic control of surface anchoring could therefore provide a handle to tune the colloidal organization and resulting properties in these systems. In this article, we report our results on the study of thermotropic nematic LC (E7) dispersions of silica and glass microcolloids bearing photosensitive surface azobenzene groups. By the photoinduced modulation of the colloidal-LC interfacial properties, due to the trans-cis isomerization of azobenzene units, we tune the anchoring on silica colloids from homeotropic (trans-azobenzene) to homogeneous planar (cis-azobenzene) reversibly. In tune with the change in surface anchoring, the interparticle interactions were also dictated by dipolar and quadrupolar symmetries for homeotropic and homogeneous planar anchoring, respectively. In our experiments, we find that, in addition to the isomerization state of the surface-bound azobenzene units, the nature of the colloid plays a crucial role in determining the anchoring state obtained on applying photostimuli. We also study the LC anchoring on colloids as a function of the azobenzene surface density and find that beyond a threshold value the anchoring properties remain invariant. 相似文献
4.
5.
General conclusions regarding the non-linear vibration of structural components like curved beams, rings and thin shells are derived from the study of two specific examples, the circular ring and shallow spherical shell. It is shown that whereas the non-linear behaviour of flat plates and straight bars is generally of a hardening type, the behaviour of thin structural elements that have a finite curvature of the undeformed median surface in one or both principal axis directions may be of the hardening or softening type, depending on the structural parameters as well as on whether the shell is open or closed. It is seen that with careful judgment in the use of mode shapes of one or more terms, the resulting modal equations help one to appreciate much better the physics of the problem, whereas sophisticated mathematical models tend to obscure this. 相似文献
6.
Some novel compounds of bis/mono 1-aryl-1H-tetrazole-5-carboxylic acid are synthesized by the hydrolysis of two different synthesized esters, they are ethyl-1-aryl-1H-tetrazole-5-carboxylate and ethyloxo(1-aryl-1H-tetrazol-5-yl)acetate. The ethyl-1-aryl-1H-tetrazole-5-carboxylate is resistant to get hydrolyzed, whereas the ethyloxo(1-aryl-1H-tetrazol-5-yl) acetate undergoes hydrolysis process and converts the ester to title compound. All the synthesized compounds are characterized by IR, 1H and 13C NMR, mass and elemental analysis.The ethyl-1-aryl-1H-tetrazole-5-carboxylateis optimized by DFT B3LYP method and the HOMO and LUMO energy is 5.14?eV and also there is a formation of a weak bond between O18 and C8 as observed from the AIM analysis result. 相似文献
7.
Venkata Rao Madduluri Peddinti Nagaiah Challa Prathap Paleti Gidyonu Burri David Raju Kamaraju Seetha Rama Rao 《Journal of Saudi Chemical Society》2019,23(6):678-690
Co3O4/γ-Al2O3 catalysts with variable Co3O4 loadings (5–20 wt%) and deposition of 15% Co3O4 on La2O3/γ-Al2O3 were prepared by wet impregnation method. La2O3-γ-Al2O3 support with variable composition of La2O3 (2–6 wt%) were prepared by co-precipitation method. All the catalysts were tested for oxidative dehydrogenation of ethylbenzene with CO2 as soft oxidant. Among the Co3O4/γ-Al2O3 catalysts, 15% Co3O4/γ-Al2O3 has shown good performance and hence this catalyst has been chosen to investigate the effect of La2O3 species. CO2 pulse chemisorption data indicate more amount of CO2 uptake over 15% Co3O4/4%La2O3/γ-Al2O3 catalyst which clearly indicates that this catalyst exhibits good performance in ethylbenzene dehydrogenation with CO2 as soft oxidant because of reverse water gas shift reaction. Temperature programmed reduction studies indicate that the Co3O4 catalysts follow two step reduction mechanism from Co3O4 to CoO and then to Co and La2O3 promotional effect is visible through facile reduction of Co3O4 species. La2O3 doping has a vital influence in getting enhanced ethylbenzene conversion, styrene yield and alleviates catalyst deactivation compared to that of unpromoted Co3O4/γ-Al2O3 catalyst. TGA studies indicate the presence low amount coke deposition during time-on-stream over 15% Co3O4/4%La2O3/γ-Al2O3 catalyst compared to 15% Co3O4/γ-Al2O3 catalyst. 相似文献
8.
Nagu A. Vasikerappa K. Gidyonu P. Prathap Ch. Venkata Rao M. Rama Rao K. S. David Raju B. 《Research on Chemical Intermediates》2020,46(5):2669-2681
Research on Chemical Intermediates - MgO-supported Ni catalysts were selectively catalysed by the hydrogenation of benzonitrile to benzylamine in continuous flow at atmospheric pressure without any... 相似文献
9.
10.
A comparative study has been carried on the role of balanced magnetron (BM) and unbalanced magnetron (UBM) sputtering processes on the properties of SnO2 thin films. The oxygen partial pressure, substrate temperature and deposition pressure were kept 20%, 700 °C and 30 mTorr, respectively and the applied RF power varied in the range of 150–250 W. It is observed that the UBM deposition causes significant effect on the structural, electrical and optical properties of SnO2 thin films than BM as evidenced by X-ray diffraction, C-V, Spectroscopic Ellipsometer and Photoluminescence measurements. The value of band gap (Eg) of the films deposited at 150 W in UBM is found as Eg = 3.83 eV which is much higher than the value of Eg = 3.69 eV as observed in BM sputtering indicating that UBM sputtering results in good crystalline quality. Further, the C-V measurements of SnO2 thin films deposited using UBM at high power 250 W show hysteresis with large flat band shift indicating that these thin films can be used for the fabrication of memory device. The observed results have been attributed to different mechanisms which exist simultaneously under unbalanced magnetron sputtering due to ion bombardment of growing SnO2 thin film by energetic Ar+ ions. 相似文献