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81.
The structure of the (0–1) band of the d3Πi-b3Πr system of SiO has been photographed under high resolution with a chemiluminescent flame source, and a rotational analysis has been carried out. All theoretically predicted 27 branches of the d3Πi-b3Πr transition have been identified. The upper-state level is shown to be perturbed by the v = 23 level of the A1Π state. Due to mixing of the A1Π with the d3Π, the (23-1) band of the A1Π-b3Πr transition has also been observed. The deperturbed molecular constants of the d3Πi and A1Π levels have been evaluated. 相似文献
82.
R. Shanker 《Physics letters. A》1983,96(4):188-190
A statistical treatment has been applied to interpret the experimental data on the Xe M-shell vacancy production in slow 1.05 MeV XeXe collisions and is shown to give better agreement with experiment than that of the molecular-orbital models. 相似文献
83.
S.C. Agrawal V.K. Jain Jai Shanker 《Journal of Physics and Chemistry of Solids》1982,43(11):1033-1035
Electronic polarizabilities and sizes of ions in NH4Cl, NH4Br and NH4I crystals are calculated using Ruffa's theory and an empirical relation between polarizability and radius. Using the electronic polarizabilities we have estimated the van der Waals dipole-dipole and dipole-quadrupole potentials following the Slater-Kirkwood varitional method. These potentials and ionic radii are then used to calculate the cohesive energies of ammonium halides. The results are discussed and compared with those of other investigators. 相似文献
84.
Darbha GK Rai US Singh AK Ray PC 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(13):3896-3903
Infectious diseases caused by the human immunodeficiency virus (HIV) remain the leading killers of human beings worldwide, and function to destabilize societies in Africa, Asia, and the Middle East. Driven by the need to detect the presence of HIV viral sequence, here we demonstrate that the second-order nonlinear optical (NLO) properties of gold nanorods can be used for screening HIV-1 viral DNA sequence without any modification, with good sensitivity (100 pico-molar) and selectivity (single base-pair mismatch). The hyper-Rayleigh scattering (HRS) intensity increases 45 times when a label-free 145-mer, ss-gag gene DNA, was hybridized with 100 pM target DNA. The mechanism of HRS intensity change has been discussed with experimental evidence for higher multipolar contribution to the NLO response of gold nanorods. 相似文献
85.
Reddy PM Shanker K Rohini R Sarangapani M Ravinder V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(5):1231-1237
Some new organometallics of ruthenium(II) of the type [RuCl(2)(COD)(CO)L] (1a-f) and [RuCl(2)(COD)L(2)] (2a-f) (where L is substituted tertiary phosphines), have been synthesized by using precursors [RuCl(2)(COD)(CO)(CH(3)CN)] (1) and [RuCl(2)(COD)(CH(3)CN)(2)] (2) with the substituted tertiary phosphine ligands in 1:1 and 1:2 molar ratio. The organometallics (2a-f) have been further reacted with carbonmonoxide to produce compounds of the type [RuCl(2)(CO)L(2)] (3a-f). These compounds were characterized by elemental analysis, IR, NMR ((1)H, (13)C and (31)P), mass and electronic spectral data. The catalytic activity of all these organometallics were studied and found that they are efficient catalysts for hydrolysis of etofibrate. The hydrolyzed product was separated by column chromatography and the percent yields are found in the range of 98.6-99.1%. 相似文献
86.
Tombari E Ferrari C Johari GP Shanker RM 《The journal of physical chemistry. B》2008,112(35):10806-10814
Glassy states of three pharmaceuticals, acetaminophen, griseofulvin, and nifedipine, and an acetaminophen-aspirin (1:1 mol) alloy were made by slow cooling of the melt and studied by calorimetry. Measurements were performed by cooling and heating at significantly slow rates of 20 K/h, which were comparable to the rate used in adiabatic calorimetry. The results were modeled in terms of a nonexponential, nonlinear structural relaxation. The calorimetric relaxation of all four pharmaceutical samples were less nonexponential than those of polymeric or inorganic glasses, and this finding was attributed to additional contributions to energy change that would arise from temperature and time dependent variation in the hydrogen bond population, the extent of isomerization, and/or the ionic equilibria that exist in these materials. Four calculated and relevant parameters for the pharmaceutical samples were, ln A = -183, beta = 0.75, x = 0.4, and Delta h* = 457 kJ/mol for acetaminophen, ln A = -170, beta = 0.75, x = 0.45, and Delta h* = 516 kJ/mol for griseofulvin, ln A = -189, beta = 0.69, x = 0.39, and Delta h* = 503 kJ/mol for nifedipine, and ln A = -160, beta = 0.70, x = 0.50, and Delta h* = 363 kJ/mol for the acetaminophen-aspirin alloy. The significance of these parameters and, in particular, their values are discussed in the context of the stability of the pharmaceuticals against crystallization and compared against the significance of the localized motions of the JG relaxation in the same context. Acetaminophen was found to be significantly more prone to crystallization on heating than the other two pharmaceuticals as well as the acetaminophen-aspirin alloy. 相似文献
87.
The linear stability of convection due to compositional and thermal buoyancy in Earth's outer core has been investigated. We have obtained the values of Takens-Bogdanov bifurcation points by plotting graphs of neutral curves corresponding to stationary and oscillatory convection for different values of physical parameters. We have derived a non-linear two-dimensional Landau-Ginzburg equation with real coefficients near the onset of stationary convection at a supercritical pitchfork bifurcation and two non-linear one-dimensional coupled Landau-Ginzburg type equations with complex coefficients near the onset of oscillatory convection at a supercritical Hopf bifurcation. We have studied Nusselt number contribution from a Landau-Ginzburg equation at the onset of stationary convection. We have discussed the stability regions of standing and travelling waves. We have also discussed the occurrence of secondary instabilities such as Eckhaus, zigzag and Benjamin-Feir instabilities. We have also derived the non-linear amplitude equation near the Takens-Bogdanov bifurcation point. 相似文献
88.
Wine and propolis are among the richest sources of polyphenolics. Flavonoids and phenolic acids are main pharmacological components whose benefits have been shown in numerous reports. This paper presents a review of the latest applications of HPLC for determination of polyphenolics in propolis and wine. Special attention is focused on sample preparation, chromatographic conditions, and detection of polyphenolics. HPLC will undoubtedly be the most used method that is readily available for analysis, as well as for isolation of polyphenolics in complex mixtures. 相似文献
89.
This paper presents an integrated production-inventory model where a vendor produces an item in a batch production environment and supplies it to a set of buyers. The buyer level demand is assumed to be independent normally distributed and lead time of every buyer can be reduced at an added crash cost. The buyers review their inventory using continuous review policy, and the unsatisfied demand at the buyers is completely backordered. A model is formulated to minimize the joint total expected cost of the vendor–buyers system to determine the optimal production-inventory policy. Since it is often difficult to estimate the stock-out cost in inventory systems, and so instead of having stock-out cost component in the objective function, a service level constraint (SLC) corresponding to each buyer is included in the model. A Lagrangian multiplier technique based algorithmic approach is proposed, which evaluates a very limited number of combinations of lead time of the buyers to find simultaneously the optimal lead time, order quantity and safety factor of the buyers and the number of shipments between the vendor and the buyers in a production cycle. Finally, a numerical example and effects of the key parameters are included to illustrate the results of the proposed model. 相似文献
90.
Debasis De Shanker Ram Alok BanerjeeSanat K. Roy 《Journal of magnetism and magnetic materials》2012,324(6):1133-1140
(La0.6Eu0.4)0.67Ca0.33MnO3 has been prepared in the shape of nanoplates of single crystallites (an orthorhombic structure) through polymer templates. HRTEM images reveal 18, 25, and 30 nm thicknesses of plates after heating a precursor powder at 873, 1073, and 1273 K in air for 2 h. These values present average crystallite size determined from broadening of the X-ray diffraction peaks. A spin-glass-like surface (GS) overlayer (3-5 nm thickness) in such plates facilitates a ferromagnetic→ferrimagnetic reordering with markedly suppressed Curie point TC, i.e., as small as 90 K in a 873 K heated sample, from the parent value 268 K. The TC point increases to 103 K (or 120 K) when heating at higher temperature 1073 (or 1273 K), during which the core grows at the expense of the overlayer. The GS tailors as high coercivity Hc as 617 Oe in the zero field cooled (ZFC) sample that is decreased to 500 Oe in the field cooled (FC) sample in the surface spin-freezing along the field direction. The Hc-value (ZFC) that steps down successively to 252 Oe on the overlayer is thinned down by heating at 1273 K. Samples heated at 873, 1073, or 1273 K have regularly increased saturation magnetization 35.3, 63.9, or 69.6 emu/g in ZFC, while 43.7, 70.2, or 75.5 emu/g in FC measured at 10 K. The ferrimagnetic reordering are described based on the scenario of an antiferromagnetic exchange coupling between the Eu3+ and Mn3+ (or Mn4+) sublattices. 相似文献