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991.
The performance of Co catalysts supported on MgO at different Co loading (10%-75%) for the formation of carbon nanotubes through acetylene decomposition at 600 °C with H2/C2H2 mixture for 1 h is investigated. The yield of MWNTs increases with an increase in Co loading (up to 50%). Starting from 1 g of catalyst precursor, about 8 g of MWNTs was obtained. The XRD patterns of catalyst precursor indicate the presence of cobalt in oxidic phase that eventually transformed into the catalytically active Co nanoparticles (12-18 nm) under the influence of acetylene and was responsible for the growth of coiled-like multi-walled CNTs as revealed by SEM and HRTEM images. It is suggested that bending in coil shaped MWNTs has the potential for functionalization for its biomedical applications. 相似文献
992.
Nguyen Nhu Dat 《Czechoslovak Journal of Physics》1989,39(9):1048-1058
The nonlinear dielectric function of a direct band gap semiconductor is calculated using non-equilibrium Green's function technique. The interaction between the semiconductor and the intense radiation field is assumed to occur via excitons. As an example we calculate the polariton dispersion relation and the intensity-dependent changes of refraction index for GaAs.The author would like to thank Prof. Nguyen Van Hieu for projecting the problem and helpful discussions. 相似文献
993.
994.
Graphs with Prescribed Mean Curvature on Poincare Disk 总被引:1,自引:0,他引:1
We establish the existence and uniqueness of a solution of aquasilinear elliptic equation in the unit disk of R2. Usingthis result, we obtain the existence of graphs with prescribedcurvature on the Poincaré disk. 相似文献
995.
Nguyen Tien Zung 《Letters in Mathematical Physics》1995,33(3):187-193
The main perpose of this letter is to give a topological classification of stable nondegenerate singularities of smooth integrable Hamiltonian systems. Namely, we show that all such singularities can be decomposed diffeomorphically, after a finite covering, to the direct product of simplest (codimension 1 and codimension 2 focus-focus) singularities. 相似文献
996.
V. I. Belyavskiĭ Yu. V. Kopaev Nguyen Ngoc Tuan 《Journal of Experimental and Theoretical Physics》2007,105(4):726-737
In a weakly doped quasi-two-dimensional antiferromagnet with a Fermi contour in the form of small pockets, the Coulomb repulsion gives rise to a doubly ordered superconducting state of coexisting condensates with a large pair momentum and a zero one. The pairing with the large momentum determines the superconducting transition temperature, below which the order with zero momentum coexists as an induced order until the temperature corresponding to the initiation of the phonon pairing mechanism is reached. The superconductivity-induced orbital current density wave eliminates the pairing-repulsion-caused zero points from the two-gap quasiparticle spectrum and leads to a deviation of the relative phase of the superconducting order parameter components from π. 相似文献
997.
998.
Zhihua Sui Van N. Nguyen Jeff Fernandez John F. Barrett Kwasi A. Ohemeng 《Journal of heterocyclic chemistry》1997,34(1):153-156
A series of 4-quinazolone-5-carboxylic acids were designed as bacterial DNA gyrase inhibitors. The syntheses of the target compounds were accomplished by reacting 3-aminophthalimide with aroyl chlorides followed by rearrangement of the resulting 3-acylaminophthalimides under basic conditions. The designed compounds showed moderate DNA gyrase inhibitory activity. 相似文献
999.
K. Khazeni J. Hone Nasreen G. Chopra A. Zettl J. Nguyen R. Jeanloz 《Applied Physics A: Materials Science & Processing》1997,64(3):263-269
60 display transport properties vastly different from their unpolymerized counterparts. We here describe structural (X-ray
diffraction and transmission electron microscopy) and dc resistivity measurements of polymerized AC60 (A = K, Rb) at zero and high pressures. The structural and electronic properties are rich, and evidence is found for unusual
phase transitions in both materials.
Received: 28 October 1996/Accepted: 13 December 1996 相似文献
1000.
Nguyen Dai Hung Y. Segawa Pham Long Dinh V. Trung 《Applied physics. B, Lasers and optics》1997,65(1):19-23
Received: 18 April 1996/Revised version: 14 August 1996 相似文献