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1.
2.
Prapti Saxena Sankar P. Sanyal 《Physica E: Low-dimensional Systems and Nanostructures》2004,24(3-4):244-248
We report a detailed study of the phonon properties of hexagonal boron nitride (BN) monolayers as well as nanotubes by using De Launay type of angular force model. The force constants used for calculation of phonon dispersion relations of the nanotube are derived from those for the monolayers of hexagonal by employing force constant method. These force constants have been modified to include the effect of curvature of the tubule. The results are then used to derive the phonon dispersion relations for (10,10) BN nanotubes using ‘zone-folding’ method. Calculated phonon modes are in good agreement with the experimental values obtained so far, for (10,10) armchair BN nanotubes. 相似文献
3.
Cyclic voltammetric studies of certain industrially potential iron chelate catalysts 总被引:1,自引:0,他引:1
For the analysis of infrared spectroscopic bands and complex patterns partial cross correlation functions of a sample spectrum
with reference spectra are calculated. The chosen ranges of the spectra are based on empirical knowledge of infrared spectrum
structure correlations. The normalised maxima of the partial cross correlation functions are interpreted as fuzzy truth values
and are combined by fuzzy logical operators. By application of that procedure larger common substructures will be derived
from the reference spectra than by a maximum common substructure search based on the complete spectra.
Received: 30 October 1996/Revised: 24 February 1997/Accepted: 26 February 1997 相似文献
4.
Anubhav Saxena Roopali Rai Sun-Young Kim Michiya Fujiki Masanobu Naito Kento Okoshi Giseop Kwak 《Journal of polymer science. Part A, Polymer chemistry》2006,44(17):5060-5075
Noncovalent interactions, such as hydrogen bonding, metal coordination, and π-π stacking, are increasingly being utilized to develop well-ordered and self-organized supramolecular materials. Recently, new types of nonclassical weak interactions, such as C H···π, C H···F C, and C H···O, have been exploited in stabilizing the specific conformations of molecules and molecular assemblies in the solid state. These noncovalent interactions play an important role in materials comprised of polymer chains, because cooperative effects from a large number of weak interactions can lead to drastic changes in its conformation, several properties, and functionalities. The programmed design of synthetic helical polymer with well-defined molecular conformation has been the main subject in modern polymer science and engineering. Silicon-catenated polysilane is an ideal helical silicon quantum wire and polymers with unique photophysical properties. The present review highlights the spectroscopic evidences for through-space weak Si···F C interaction in poly(methyl-3,3,3-trifluoropropylsilane) ( 1 ) in noncoordinating and coordinating solvents by means of NMR (29Si and 19F) and IR spectroscopies, and viscometric measurement. It was found that 1 is applicable for chemosensors with an extremely high sensitivity and selectivity toward fluoride ions in tetrahydrofuran (THF) and with high sensitivity for nitroaromatic compounds, detected by a decrease in the photoluminescence intensity in THF and in thin solid film. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5060–5075, 2006 相似文献
5.
6.
The syntheses of some 2-mercaptobenzimidazole (I) derivatives have been described. While preparing such compounds it has been observed that I reacts predominantly as the thione under anhydrous reaction conditions, and as the thiol in the presence of an alkali. Strutures of all of the nine compounds have been established with the help of spectral methods including 13C nmr spectroscopy of the two compounds (II and III). 相似文献
7.
William J. Evans Ira Bloom Robert J. Doedens 《Journal of organometallic chemistry》1984,265(3):249-255
(C5H5)2VCl reacts with LiCCC(CH3)3 to form (C5H5)2VCCC(CH3)3 which was characterized by spectroscopic, analytical, and crystallographic methods. The complex crystallizes from pentane at 0°C as a monomer in the orthorhombic space group Pnma with four molecules in a unit cell of dimensions a 9.075(3), b 9.807(3), c 16.444(5) Å. Full-matrix least-squares refinement based upon 1300 nonzero intensity data converged to a final conventional R factor of 0.060. The molecule has a mean VC5H5-ring centroid distance of 1.941 Å with 146.6° ring centroid-V-ring centroid angle. The vanadium alkynide carbon distance is 2.075(5) Å. 相似文献
8.
Akhilesh K. Verma Rupesh Kumar Amit Saxena Subho Mozumdar 《Tetrahedron letters》2005,46(31):5229-5232
A novel method for effecting the aza-Michael reactions of N-alkyl- and N-arylpiperazines with acrylonitrile using Cu-nanoparticles is described. The method features the use of 10 mol % Cu (14-17 nm) nanoparticles under mild reaction conditions to afford the addition products in good to excellent yields. The Cu-nanoparticles selectively catalysed the aza-Michael reaction of N-alkyl- and N-arylpiperazines in the presence of aromatic amino or aliphatic hydroxy groups. 相似文献
9.
M. Aneesuddin P. N. Char M. Raza Hussain E. R. Saxena 《Journal of Thermal Analysis and Calorimetry》1983,26(2):205-215
When chalcopyrite is heated in air, up to 350? there is no marked change. Between 350 and 440?, surface material is oxidised to iron sulphate, CuSO4 and Fe2O3, while in regions not accessible to oxygen the formation of Cu5FeS4, FeS and S takes place. From 440 to 500? oxidation and sulphation phenomena occur. Stable compounds between 500 and 650? are iron sulphate, CuSO4 and Fe4O3, with a minor amount of 6CuO.Cu2O indicated at 650?. After the decomposition of iron sulphate, CuSO4 decomposes, first to CuO.CuSO4 and then to CuO. By 750? the sulphur has been totally lost from all compounds, while the oxides of copper and iron partly react to form CuFe2O4. Final products of oxidation between 800 and 850? are CuO, CuFe2O4 and Fe3O4. 相似文献
10.
Berkowitz SA Zhong H Berardino M Sosic Z Siemiatkoski J Krull IS Mhatre R 《Journal of chromatography. A》2005,1079(1-2):254-265
A simple high-resolution capillary zone electrophoresis (CZE) method capable of rapidly assessing the micro-heterogeneity of a 24 kDa molecular weight glycoprotein, has been developed. Separation is carried out using a bare silica capillary at a pH of 2.5 in a commercially available electrophoresis buffer system composed of triethanolamine and phosphoric acid. Over 30 peaks were detected within a run time of 15 min using a 27 cm capillary and approximately 60 peaks were detected using a 77 cm capillary. Although most of the peaks arise from differences in the oligosaccharide structures present on the one glycosylation site on this molecule, other forms of micro-heterogeneity due to the presence of the nonglycosylated form of this glycoprotein and various types of chemical degradation, e.g., deamidation, are also responsible for the multitude of peaks observed. Although the exact chemical identity of each peak in the resulting electropherogram of this glycoprotein is not known, useful information can be obtained for assessing comparability, stability, and batch consistency. Factors impacting the resolution, precision, accuracy, and robustness of the assay are also discussed along with inherent advantages and limitations associated with measuring the micro-heterogeneity of intact glycoproteins. 相似文献