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51.
S. G. Dani Meera G. Mainkar 《Transactions of the American Mathematical Society》2005,357(6):2235-2251
We associate with each graph a -step simply connected nilpotent Lie group and a lattice in . We determine the group of Lie automorphisms of and apply the result to describe a necessary and sufficient condition, in terms of the graph, for the compact nilmanifold to admit an Anosov automorphism. Using the criterion we obtain new examples of compact nilmanifolds admitting Anosov automorphisms, and conclude that for every there exist a -dimensional -step simply connected nilpotent Lie group which is indecomposable (not a direct product of lower dimensional nilpotent Lie groups), and a lattice in such that admits an Anosov automorphism; we give also a lower bound on the number of mutually nonisomorphic Lie groups of a given dimension, satisfying the condition. Necessary and sufficient conditions are also described for a compact nilmanifold as above to admit ergodic automorphisms.
52.
The C-cyanoethylation of the methyl and ethyl ethers of dimethylphenols has been carried out with acrylonitrile in the presence of anhydrous AlCl3 to furnish propionitrile derivatives. The latter on hydrolysis to the corresponding propionic acids followed by cyclization with PPA afforded the appropriate indanones, whose structures have been established on the basis of spectral data and by the formation of 2, 4-DNP derivatives. 相似文献
53.
S. Karamat R. S. Rawat T. L. Tan P. Lee R. Chen H. D. Sun W. Zhou 《Applied Physics A: Materials Science & Processing》2010,99(4):717-722
Multilayer structures A–B–A⋅⋅⋅ consisting of alternating layers of a metal A and a semiconductor B can show large anisotropy
in their transport properties. In tilted multilayer structures, where layer planes and sample surface include a nonzero tilt
angle, nonvanishing off-diagonal elements in the sample’s transport tensors lead to transverse Seebeck and Peltier effects.
Achievable temperature differences and figures of merit for transverse Peltier cooling are discussed and compared with experiments,
coefficients of performance for transverse power generation are calculated. 相似文献
54.
Material ablation and plasma plume expansion study from Fe and graphite targets in Ar gas atmosphere
S. Mahmood R. S. Rawat S. V. Springham T. L. Tan P. Lee 《Applied Physics A: Materials Science & Processing》2010,101(4):695-699
Study of expansion dynamics of pulsed-laser ablation plasmas from Fe and graphite targets is presented. A 532 nm Q-switched
Nd:YAG laser with fluence of 30 J cm−2 is used to ablate the Fe and graphite targets in various Ar ambient gas pressures. Plasma ablation parameters for the two
target materials are estimated using snow-plow and shock-wave models, which show that the laser beam energy deposited to ablated
species remains at 70% for both targets at all ambient pressures. The plume splitting was observed, more prominently, for
Fe plasma as it moves faster compared to graphite plasma. The difference in plasma plume fronts’ speeds for different targets
was attributed to the significant difference in mass of the ablated plasma for two targets, as estimated from simulation results. 相似文献
55.
56.
Ijaz Ahmad Khan Syed Anwaar Hussain Amjad Farid Ali Hussnain Zeshan Adeel Umar Rajdeep Singh Rawat 《辐射效应与固体损伤》2013,168(11-12):929-943
ABSTRACTCrystalline silicon oxy-nitride (SiON) composite films are deposited on Si substrate for multiple (5, 15, 25 and 50) focus shots (FS) by plasma focus device. The X-rays diffraction patterns reveal the development of various diffraction peaks related to Si, Si3N4, and SiO2 phases which confirms the formation of SiON composite film. The intensity of Si3N4 (1 0 2) plane is linearly increased with the increase of FS. The Si3N4 (1 0 2) phase does not nucleate for 5 FS. Raman analysis confirms the formation of β–Si–N phase. Raman and Fourier transform infrared spectroscopy analysis reveals that the strength of chemical bonds like Si–N, Si–O formed during the deposition process of SiON composite films is associated with the bonds intensity which in turn depends on the number of FS. The field emission scanning electron microscopic analysis reveals that the surface morphology like size, shape and distribution of micro/nano-dimensional particles, film compactness and the formation of micro-rods, micro-teethes and micro-tubes of SiON composite films is entirely associated with the rise in substrate surface transient temperature which in turn depends on the increasing number of FS. The EDX spectrum confirms the presence of Si (22.5?±?4.7 at. %), N (13.4?±?4.5 at. %) and O (54.7?±?11.3 at. %) in the SiON composite film. The thickness of SiON composite film deposited for 50 FS is found to ~15.47?µm. 相似文献
57.
Hamid Latif M. Shahid Rafique R.S. Rawat Shahzad Naseem 《Applied Surface Science》2008,254(22):7505-7511
In the paper an attempt has been made to use the laser-induced plasma as an X-ray source for the growth of nanostructures on the surface of gold. For this purpose, an Nd:YAG laser operated at second harmonics (λ = 532 nm, E = 400 mJ) is used to produce plasma from analytical grade 5N pure Al, Cu and W targets. An analytical grade (5N pure) gold substrate was irradiated by X-rays generated from Al, Cu and W plasma under the vacuum ∼10−4 Torr. The surface was analyzed by two techniques, XRD and AFM. The aberrations in the XRD peaks show that there are significant structural changes in the exposed gold, in terms of decreased reflection intensities, increased dislocation line density, changes in the d-spacing and disturbance in the periodicity of the planes. AFM used to explore the topography of the irradiated gold reveals that regardless of the source, nm sized hillocks have been produced on the gold surface. The roughness of the surface has increased due to the growth of these hillocks. 相似文献
58.
Firdose R. Kolar Chaya L. Gogi Mairunisabegum M. Khudavand Meera S. Choudhari Sindhu B. Patil 《Natural product research》2018,32(11):1324-1328
In this study, the antioxidant activity of aqueous and ethanol extracts of four plants from the genus Cassia were evaluated by various antioxidant assays, including ferric reducing antioxidant power (FRAP), DPPH free radical scavenging, metal chelating activity, phosphomolybdenum reducing power, hydrogen peroxide radical scavenging, hydroxyl radical scavenging, deoxyribose degradation and β-carotene bleaching assay. The various antioxidant activities were compared to standard antioxidant such as ascorbic acid. All the extracts showed antioxidant activity in the tested methods. Among the four species, Cassia auriculata has been found to possess highest activity in most of the tested models. In addition to the antioxidant activity, the total phenolics and flavonoids were measured in the extracts. The ethanolic extract exhibited highest phenolics and flavonoid contents and had also shown potent antioxidant activity in comparison to the aqueous extracts. The possible antioxidant mechanism of the ethanol extract can be due to its hydrogen or electron donating and direct free radical scavenging properties. Hence, the ethanol extract represents a source of potential antioxidants that could be used in pharmaceutical industries. 相似文献
59.
Gupta Abhishek Verma Shikhar Dwivedi Harinath Rawat Ajay Kumar Singh 《平面色谱法杂志一现代薄层色谱法》2016,29(6):423-428
JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatography (HPTLC) method for the simultaneous quantitative determination of lupeol and ursolic... 相似文献
60.