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661.
A series of Ce1MgxZr1-xO2 mixed metal oxides with different molar ratios were prepared by simple co-precipitation and were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, temperature-pro- grammed desorption of CO2, and N2 adsorption techniques. The prepared materials were tested for catalytic activity by the synthesis of tet-rahydrobenzo[b]pyran derivatives using a three component reaction (aromatic aldehydes, malononitrile, and dimedone) in an ethanol me-dium. The best catalytic activity was obtained with Ce1Mg0.6Zr0.4O2. The particle size or crystallite size was estimated using the De-bye-Scherrer equation. The addition of magnesium oxide into the ceria-zirconia lattice resulted in the formation of nanosized particles rang-ing from 5.41 to 9.78 nm. This work describes the catalytic behavior of magnesium oxide in mixed metal oxide systems. 相似文献
662.
Raghunath B. Toche Balasaheb P. Pagar Ravindra R. Zoman Goraksha B. Shinde Madhukar N. Jachak 《Tetrahedron》2010,66(27-28):5204-5211
This paper describes the synthesis of 2,8-dichloroquinolin-4-amine 4 and 4,5,7-trichloro-3-(2-chloroethyl)-2-methylbenzo[h][1,6]naphthyridine 8 as novel class of building blocks. Also describes the regioselective SNAr reactions of 2,4,8-trichloroquinoline 2 on C2 and C4 positions with azide, similarly SNAr reactions of benzo[h][1,6]naphthyridine 8 at C4, C5 positions, and SN2 reactions on C3-(2-chloroethyl) side chain with nucleophiles such as primary aromatic amines, methoxide/ethoxide, and azide at different temperatures. 相似文献
663.
Intramolecular Diels-Alder approach to construct the fused AB ring of trinervitane has been demonstrated efficiently. The key intermediate for the Diels-Alder cyclization has been achieved following highly stereoselective Julia-Kocienski olefination, Sharpless epoxidation and Evan’s asymmetric alkylation as the key reactions. 相似文献
664.
In the present work a numerical study was carried out to investigate the inclusion behaviour in a four strand asymmetric billet caster tundish. A parameter called separation efficiency was used to compare inclusion behaviour quantitatively. An open source CFD code called OpenFOAM was used to model the inclusions through Lagrangian Particle Tracking approach. First, the Lagrangian particle class was defined in the existing simpleFoam solver of the OpenFOAM and the same customized solver was used to track particles in the already obtained velocity field. Inclusions were modelled as spheres and various forces acting were also considered. Present numerical results were validated using available experimental results and found to be in good agreement. Further, such inclusion behaviour was also extended for a real industrial case tundish. Inclusion flotation characteristics in thermally induced flow was analyzed in detail. This is, perhaps, for the first time such an exhaustive study on inclusion analysis being reported considering the forces acting on the inclusions particles and with OpenFOAM. 相似文献
665.
666.
Haji-saeed B Sengupta SK Goodhue W Khoury J Woods CL Kierstead J 《Optics letters》2006,31(13):1969-1971
We introduce a dynamic range image compression technique for nonlinear deconvolution; the impulse response of the distortion function and the noisy distorted image are jointly transformed to pump a clean reference beam in a two-beam coupling arrangement. The Fourier transform of the pumped reference beam contains the deconvolved image and its conjugate. In contrast to standard deconvolution approaches, for which noise can be a limiting factor in the performance, this approach allows the retrieval of distorted signals embedded in a very high-noise environment. 相似文献
667.
Synthesis and reactivity of a 9-membered azaenediyne: importance of proximity effect in N-alkylation
Synthesis of a 9-membered azaenediyne has been achieved for the first time via intramolecular N-alkylation; the importance of proximity of the reacting centres via cobalt carbonyl complexation of the acetylenic moiety and not the activation of propargylic carbon has been demonstrated. 相似文献
668.
First VLF detections of ionospheric disturbances due to Soft Gamma Ray Repeater SGR J1550-5418 and Gamma Ray Burst GRB 090424 总被引:1,自引:0,他引:1
Sandip K. Chakrabarti Sushanta K. Mandal Sudipta Sasmal Debashis Bhowmick Asit K. Choudhury Narendra N. Patra 《Indian Journal of Physics》2010,84(11):1461-1466
We present the first report of the detection of sudden ionospheric disturbances (SIDs) due to a Soft Gamma Ray Repeater (SGR)
SGR J1550-5418 and a Gamma Ray Burst (GRB) GRB 090424. These detections were made with receiving stations of Indian Centre
for Space Physics which were monitoring Very Low Frequency signals (VLFs) from the VTX transmitter located at the southern
tip of Indian sub-continent. These positive detections add to the list of a handful of similar detections of other GRBs and
SGRs throughout the world. 相似文献
669.
The reaction of a tridentate Schiff base ligand HL (2-[(3-dimethylaminopropylimino)-methyl]-phenol) with Ni(II) acetate or perchlorate salts in the presence of azide as coligand has led to two new Ni(II) complexes of formulas [Ni(3)L(2)(OAc)(2)(μ(1,1)-N(3))(2)(H(2)O)(2)]·2H(2)O (1) and [Ni(2)L(2)(μ(1,1)-N(3))(μ(1,3)-N(3))](n)(2). Single crystal X-ray structures show that complex 1 is a linear trinuclear Ni(II) compound containing a μ(2)-phenoxido, an end-on (EO) azido and a syn-syn acetato bridge between the terminal and the central Ni(II) ions. Complex 2 can be viewed as a one-dimensional (1D) chain in which the triply bridged (di-μ(2)-phenoxido and EO azido) dimeric Ni(2) units are linked to each other in a zigzag pattern by a single end-to-end (EE) azido bridge. Variable-temperature magnetic susceptibility studies indicate the presence of moderate ferromagnetic exchange coupling in complex 1 with J value of 16.51(6) cm(-1). The magnetic behavior of 2 can be fitted in an alternating ferro- and antiferromagnetic model [J(FM) = +34.2(2.8) cm(-1) and J(AF) = -21.6(1.1) cm(-1)] corresponding to the triple bridged dinuclear core and EE azido bridge respectively. Density functional theory (DFT) calculations were performed to corroborate the magnetic results of 1 and 2. The contributions of the different bridges toward magnetic interactions in both compounds have also been calculated. 相似文献
670.
Two new one-dimensional heterometallic complexes, [Mn(3)Na(L)(4)(CH(3)CO(2))(MeOH)(2)](ClO(4))(2)·3H(2)O (1), [Mn(3)Na(L)(4)(CH(3)CH(2)CO(2))(MeOH)(2)](ClO(4))(2)·2MeOH·H(2)O (2) [LH(2) = 2-methyl-2-(2-pyridyl)propane-1,3-diol], have been synthesized and characterized by X-ray crystallography. Both complexes feature Mn(II) and Na(I) ions in trigonal-prismatic geometries that are linked to octahedral Mn(IV) ions by alkoxy bridges. Variable-temperature direct- and alternating-current magnetic susceptibility data indicated a spin ground state of S = 11/2 for both complexes. Density functional theory calculations performed on 1 supported this conclusion. 相似文献