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111.
Sameer M. Ikhdair 《Applied mathematics and computation》2010,216(3):911-6652
We solve the Dirac equation approximately for the attractive scalar S(r) and repulsive vector V(r) Hulthén potentials including a Coulomb-like tensor potential with arbitrary spin-orbit coupling quantum number κ. In the framework of the spin and pseudospin symmetric concept, we obtain the analytic energy spectrum and the corresponding two-component upper- and lower-spinors of the two Dirac particles by means of the Nikiforov-Uvarov method in closed form. The limit of zero tensor coupling and the non-relativistic solution are obtained. The energy spectrum for various levels is presented for several κ values under the condition of exact spin symmetry in the presence or absence of tensor coupling. 相似文献
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113.
Digambar D. Gaikwad Sameer V. Renukdas Babasaheb V. Kendre Suresh U. Shisodia Ravikumar M. Borade Praveen S. Shinde 《合成通讯》2013,43(2):257-259
Nitriles have been prepared from different aromatic aldehydes by a one‐pot process using hydroxylamine hydrocloride and molecular iodine in the presence of dimethylsulphoxide. 相似文献
114.
Sengupta S Uemura S Patwardhan S Huber V Grozema FC Siebbeles LD Baumeister U Würthner F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(19):5300-5310
A chlorophyll derivative with a central zinc ion, a methoxy functionality at its 3(1)-position, and functionalized with a second-generation dendron (3,4-3,4,5)12G2-CH(2)OH at its 17(2)-position was synthesized starting from natural chlorophyll a (Chl a). This compound exhibits liquid crystalline (LC) behavior and its mesomorphic properties have been characterized by differential scanning calorimetry (DSC), polarisation optical microscopy (POM), powder X-ray diffraction (XRD), and scanning probe microscopy (SPM). A combination of powder XRD, high resolution scanning tunneling microscopy (STM), and atomic force microscopy (AFM) experiments revealed the formation of nano-segregated well-ordered columnar tubular superstructures consisting of about five molecules in the column stratum. These self-assembled columns are further self-organized into a two-dimensional oblique unit cell lattice. Semiconducting behavior of this compound has been studied by pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) method and charge carrier mobility values of ~10(-2) cm(2) V(-1) s(-1) are observed. Such organized columnar superstructures constructed from semisynthetic zinc chlorins are reminiscent of the tubular organization of the bacteriochlorophyll dyes in the light-harvesting chlorosomal antennae of green sulphur bacteria. 相似文献
115.
Dr. Brismar Pinto-Pacheco Dr. William P. Carbery Sameer Khan Prof. Dr. Daniel B. Turner Prof. Dr. Daniela Buccella 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22324-22333
Inverse electron demand Diels–Alder reactions between s-tetrazines and strained dienophiles have numerous applications in fluorescent labeling of biomolecules. Herein, we investigate the effect of the dienophile on the fluorescence enhancement obtained upon reaction with a tetrazine-quenched fluorophore and study the possible mechanisms of fluorescence quenching by both the tetrazine and its reaction products. The dihydropyridazine obtained from reaction with a strained cyclooctene shows a residual fluorescence quenching effect, greater than that exerted by the pyridazine arising from reaction with the analogous alkyne. Linear and ultrabroadband two-dimensional electronic spectroscopy experiments reveal that resonance energy transfer is the mechanism responsible for the fluorescence quenching effect of tetrazines, whereas a mechanism involving more intimate electronic coupling, likely photoinduced electron transfer, is responsible for the quenching effect of the dihydropyridazine. These studies uncover parameters that can be tuned to maximize fluorogenic efficiency in bioconjugation reactions and reveal that strained alkynes are better reaction partners for achieving maximum contrast ratio. 相似文献
116.
Chiguru Vishnuvardhan P. Radhakrishnanand Sameer G. Navalgund Krishnam Raju Atcha N. Satheeshkumar 《Chromatographia》2014,77(3-4):265-275
The present study describes a convenient method for the separation and simultaneous determination of eight drugs used in cardiovascular diseases, viz., atenolol (ATN), lisinopril (LISI), hydrochlorothiazide (HCTZ), enalapril maleate (ENA), amlodipine besylate (AMLO), losartan potassium (LOSA), valsartan (VAL) and atorvastatin calcium (ATOR) in pharmaceutical formulations. A ZORBAX Rx-C8 column (250 × 4.6 mm, 5 μm particle size) was used with mobile phase consisting of acetonitrile, 10 mM dipotassium hydrogen phosphate buffer (pH 2.2 adjusted with orthophosphoric acid) using a gradient program and quantitative evaluation was performed at 210 nm with a flow rate of 1.0 mL min?1. Suitability of this method for the quantitative determination of the drugs was proved by validation in accordance with International Conference on Harmonization guidelines. The method is selective, precise, robust, accurate and can be used for routine analysis of 15 combination pharmaceutical formulations in quality control. 相似文献
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119.
S Kawatkar D Moustakas M Miller D Joseph-McCarthy 《Journal of computer-aided molecular design》2012,26(8):921-934
An NMR fragment screening dataset with known binders and decoys was used to evaluate the ability of docking and re-scoring methods to identify fragment binders. Re-scoring docked poses using the Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) implicit solvent model identifies additional active fragments relative to either docking or random fragment screening alone. Early enrichment, which is clearly most important in practice for selecting relatively small sets of compounds for experimental testing, is improved by MM-PBSA re-scoring. In addition, the value in MM-PBSA re-scoring of docked poses for virtual screening may be in lessening the effect of the variation in the protein complex structure used. 相似文献
120.
In the presence of spin and pseudospin (p-spin) symmetries, the approximate analytical bound states of the Dirac equation for Hulthén-like potential including a Coulomb-like tensor interaction are obtained with any arbitrary spin–orbit coupling number κ using the Pekeris approximation. The generalized parametric Nikiforov–Uvarov (NU) method is used to obtain the energy eigenvalues and the corresponding wave functions in their closed forms. We show that tensor interaction removes degeneracies between spin and p-spin doublets. Some numerical results are also given. 相似文献