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81.
M. Nilofar Nissa P. G. Aravindan V. Kasinath G. Gopalakrishnan H. Merazig D. Velmurugan 《Crystal Research and Technology》2004,39(7):643-649
The title compounds (I) and (II) crystallize in the monoclinic space group P21/c and orthorhombic space group Pbca respectively. The inter‐planar angle between the two phenyl rings are 55° in I and 24.5(1)° in II. The molecular packing of the compounds I and II are stabilized by C‐H…O and C‐H…π, and N‐H…O, C‐H…O and C‐H…π interactions, respectively. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
82.
M. Nilofar Nissa D. Velmurugan S. Shanmuga Sundara Raj H.‐K. Fun V. Kasinath G. Gopalakrishnan 《Crystal Research and Technology》2002,37(1):125-133
The crystal structures of two cinnamanilide derivatives 2‐methyl cinnamanilide (C16 H15 N O – compound I) and 2‐methoxy cinnamanilide (C16 H15 N O2 – compound II) are reported. In both crystal structures, the cinnamamide group is almost planar. The inter‐planar angle between the two phenyl rings are 71.6(1)° for compound I and 7.5(1)° for compound II. The N‐H…O and C‐H…O type of hydrogen bond interactions between the amide group and the carbonyl group stabilizes the molecular packing as chains in the crystal lattice. 相似文献
83.
J. Gopalakrishnan 《Journal of Chemical Sciences》1984,93(3):421-432
A survey of recent developments in preparative solid state chemistry shows that, with a knowledge of structural chemistry
and reactivity patterns of solids, it is possible to synthesize a variety of new solids possessing novel structures. A distinction
is made between synthesis ofnew solids and synthesis of solids bynew methods. Three new routes to solid state synthesis are recognized: the precursor method, and topochemical methods involving redox
and ion-exchange reactions. The low-temperature topochemical methods enable synthesis of metastable phases that are inaccessible
by the high temperature route. Several illustrative examples of solid state synthesis from the recent literature are presented. 相似文献
84.
S Mohan M Gopalakrishnan H Balasubramanian A Chandrashekar 《The Journal of the Operational Research Society》2007,58(6):827-831
The success behind effective project management lies in estimating the time for individual activities. In many cases, these activity times are non-deterministic. In such situations, the conventional method (project evaluation and review technique (PERT)) obtains three time estimates, which are then used to calculate the expected time. In practice, it is often difficult to get three accurate time estimates. A recent paper suggests using just two time estimates and an approximation of the normal distribution to obtain the expected time and variance for that activity. In this paper, we propose an alternate method that uses only two bits of information: the most-likely and either the optimistic or the pessimistic time. We use a lognormal approximation and experimental results to show that our method is not only better than the normal approximation, but also better than the conventional method when the underlying activity distributions are moderately or heavily right skewed. 相似文献
85.
Y. J. Uemura L. P. Le G. M. Luke B. J. Sternlieb J. H. Brewer J. Carolan W. Hardy R. Kadono R. F. Kiefl S. R. Kreitzman T. M. Riseman C. L. Seaman J. J. Neumeier M. B. Maple G. Saito H. Yamochi H. Takagi S. Uchida J. Gopalakrishnan M. A. Subramanian A. W. Sleight Gang Xiao 《Hyperfine Interactions》1991,63(1-4):131-137
We update our muon spin relaxation studies of the magnetic field penetration depth which show the correlations betweenT
c and the relaxation rate σ αn
s/m
* (carrier density/effective mass) of hole-doped high-T
c cuprate superconductors (La2, Sr3)CuO4, YBa2Cu3O7 (Y1−xPrx)Ba2Cu3O7, and other double and triple layer systems. These studies are extended to the organic superconductor (BEDT-TTF)2Cu(NCS)2. 相似文献
86.
Nagarajan NS Rao RP Manoj CN Sethuraman MG 《Magnetic resonance in chemistry : MRC》2005,43(3):264-265
An alcoholic extract of Dalbergia sympathetica, on column chromatography, yielded a compound which analyzed for C(6)H(11)NO(3) (M(+) 145). The IR spectrum of the compound showed the presence of carbonyl and hydroxyl groups. PMR, (13)C and DEPT NMR spectral studies of the compound showed the presence of one N-methyl, two methine and two methylene groups. A quaternary carbon signal at delta 172.88 ppm was assigned to C-2 carbonyl of the compound. From all the above observations and also from the HMQC 2D NMR spectrum, the compound was identified as 3, 6-dihydroxy-N-methyl-2-piperidone. This is the first report of the natural occurrence of this compound from plant sources. 相似文献
87.
An equivalent single layer model of Lamb wave generation by thickness-graded piezoelectric IDT on host structure is developed. Various additional complexities, such as the coupling between the Lamb wave modes, complicated nature of the electro-mechanical excitation are considered. The model of infinite IDT is extended to deal with the finite IDT with edge discontinuities. The effects of electromechanical coupling and thickness gradation on the wavelength shifts are investigated. The problem of electrically driven instability within the IDT is analyzed. Numerical results are reported by considering Al2O3/PZT IDT as integral part of the host structure, which show that there are significant changes and improvements in the Lamb wave characteristics due to the graded configuration. Most important among these is the reduced dispersiveness of the Lamb wave modes, which is useful in launching a SAW that propagates with narrower pulse width and less attenuation. 相似文献
88.
Time harmonic Maxwell equations in lossless media lead to a second order differential equation for the electric field involving a differential operator that is neither elliptic nor definite. A Galerkin method using Nedelec spaces can be employed to get approximate solutions numerically. The problem of preconditioning the indefinite matrix arising from this method is discussed here. Specifically, two overlapping Schwarz methods will be shown to yield uniform preconditioners.
89.
B. Viswanathan R. Gopalakrishnan R. Vetrivel 《Reaction Kinetics and Catalysis Letters》1982,18(1-2):209-212
Three different binding states of CO on cobalt surfaces have been identified by TPD studies. The energetics of these adsorption states and their relevance in Fischer-Tropsch synthesis are considered.
CO - . -.相似文献
90.
AVO3 (A = Ba2+, Sr2+, La3+, Gd3+) oxides have been prepared by hydrogen reduction of suitable vanadium(V) ternary oxides. The oxidation state of vanadium in the reduction products seems to be controlled by the nature of other cations. In the presence of strongly basic alkaline-earth metal ions, Ba2+ and Sr2+ as in Ba2V2O7 and Sr2V2O7, vanadium is reduced to +4 state. But when A is a trivalent lanthanide ion as in LnVO4 (Ln = La or Gd), the reduction of vanadium proceeds to +3 state to yield LnVO3 phases. The products have been characterized by X-ray diffraction. BaVO3 crystallizes in a hexagonal structure related to Ba3V2O8 while SrVO3, LaVO3 and GdVO3 crystallize in GdFeO3 type structure. Electrical transport measurements indicate that BaVO3, LaVO3 and GdVO3 are p-type semiconductors while SrVO3 is metallic. 相似文献