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91.
D. Sajan G. D. Sockalingum M. Manfait I. Hubert Joe V. S. Jayakumar 《Journal of Raman spectroscopy : JRS》2008,39(12):1772-1783
Chloramphenicol (CLM), originally derived from the bacterium Streptomyces venezuelae, is an inhibitor of bacterial ribosomal peptidyl transferase activity. The near infrared Fourier transform (NIR‐FT) Raman, surface‐enhanced Raman spectroscopy (SERS) and Fourier transform infrared (FT‐IR) spectral analyses of CLM, a potential antibacterial drug for the treatment of typhoid fever, were carried out along with density functional computations. The vibrational spectral analysis reveals that the CH2 asymmetric and symmetric stretching modes are shifted to higher wavenumbers than the computed values, owing to the electronic effects resulting from induction of methylene group with the adjacent electronegative atom. The lowering of CO stretching wavenumber is due to the presence of the strong electronegative atom, nitrogen, attached to the carbonyl carbon, causing large degree of molecular π‐electron delocalization and redistribution of electrons, which weakens the CO bond. The absence of a C H stretching vibration and the observed C H out‐of‐plane bending modes suggest that the CLM molecule may be adsorbed in a flat orientation with respect to the silver surface. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
92.
R. Mittal S. L. Chaplot A. I. Kolesnikov C. -K. Loong O. D. Jayakumar S. K. Kulshreshtha 《Pramana》2004,63(2):405-408
We report here measurements of phonon spectrum and lattice dynamical calculations for GaPO4. The measurements in low-cristobalite phase of GaPO4 are carried out using high-resolution medium-energy chopper spectrometer at ANL, USA in the energy transfer range 0–160 meV.
Semiempirical interatomic potential in GaPO4, previously determined using ab-initio calculations have been widely used in studying the phase transitions among various
polymorphs. The calculated phonon spectrum using the available potential show fair agreement with the experimental data. However,
the agreement between the two is improved by including the polarisability of the oxygen atoms in the framework of the shell
model. The lattice dynamical models are also exploited for calculations of various thermodynamic properties of GaPO4. 相似文献
93.
Dr. Jayachandran Jayakumar Guganchandar Vedarethinam Huan-Chang Hsiao Shang-You Sun Prof. Dr. Shih-Ching Chuang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(2):699-704
Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C−H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2-azobiaryls with alkenes to give orange-red-fluorescent cinnolino[2,3-f]phenanthridin-9-ium salts and 15H-cinnolino[2,3-f]phenanthridin-9-ium-10-ide is proposed to involve ortho C−H olefination of the 2-azobiaryl compound with the alkene, intramolecular aza-Michael addition, concerted metalation–deprotonation (CMD), reductive elimination, and oxidation. 相似文献
94.
The dehydration of aldoximes and amides, and oxidation of benzoin are accomplished in one-pot using in situ–generated Burgess-type reagent.
Keywords: Amide, benzil, benzoin, Burgess reagent, Burgess-type reagent, dehydration, nitrile, oxidation, oxime
95.
Lakshmi R. Lakshman K. T. Shalumon Sreeja V. Nair R. Jayakumar S. V. Nair 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1012-1018
Polyurethane foam is currently used as an exudate absorptive wound dressing material. In this study silver (Ag) nanoparticles were incorporated into electrospun polyurethane (PU) nanofiber to enhance the antibacterial as well as wound healing properties. The electrospinning parameters were optimized for PU with and without silver nanoparticles. Silver nanoparticles were synthesized by aqueous and organic methods. The water absorption, antibacterial and cytocompatibility of the PU-Ag nanofibers were studied and compared to that of conventional PU foam. The results indicated that the PU-Ag nanofibers could be used for wound dressing applications. 相似文献
96.
Lakkavarapu Suresh Jayakumar Singh Bondili Pradeep Kumar Brahman 《Electroanalysis》2020,32(7):1439-1448
Present work demonstrates the fabrication of new and facile sandwich‐type electrochemical immunosensor based on palladium nanoparticles (PdNPs), polyaniline (PANI) and fullerene‐C60 nanocomposite film modified glassy carbon electrode (PdNP@PANI‐C60/GCE) for ultrasensitive detection of Prostate‐specific antigen (PSA) biomarker. PdNP@PANI‐C60 was electrochemically synthesized on GCE and used as an electroactive substrate. PdNP@PANI‐C60 was characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Primary antibody anti‐PSA (Ab1) was covalently immobilized on PdNP@PANI‐C60/GCE using NHS/EDC linkers. In the presence of PSA antigen, horseradish peroxidase secondary antibody (HRP‐Ab2) was brought into the surface of the electrode, developing stable amplified signals of H2O2 reduction. Under the optimal conditions, a linear curve for determination of PSA at the proposed immunosensor was 1.6×10?4 ng.mL?1 to 38 ng.mL?1 with a limit of detection (LOD) of 1.95×10?5 ng.mL?1. The proposed immunosensor was successfully validated in serum and urine samples towards PSA detection with satisfactory and acceptable results. 相似文献
97.
喹啉及其衍生物的多相不对称氢转移是制备杂环手性化合物的理想策略.多相手性催化体系具有催化剂可循环利用及产物分离提纯容易等优势.然而,喹啉及其衍生物的多相手性高效催化体系鲜有报道.这主要是由于多相手性氢转移为水-油-固三相反应,在反应的过程中,传质问题极大影响固体催化剂的催化性能.因此,发展具有相转移功能的手性催化材料,... 相似文献
98.
K. Jayakumar 《Mathematical and Computer Modelling》2003,37(12-13):1427-1434
First-order autoregressive Mittag-Leffler process is studied. Methods for generating dependent (first-order autoregressive Markovian) sequences of random variables with Mittag-Leffier marginal distributions are discussed. Comparison of the first-order autoregressive Mittag-Leffler process with the first-order autoregressive exponential process of Gaver and Lewis [1] is done. As an application, the first-order autoregressive Mittag-Leffier process is fitted to weakly stream flows of the Kallada River in Kerala, India. 相似文献
99.
Nguyen CT Hoang PH Perumal J Kim DP 《Chemical communications (Cambridge, England)》2011,47(12):3484-3486
A high resolution negative-tone-type of inorganic-organic diblock copolymer photoresist was synthesized as a novel precursor for simple and direct fabrication of SiCN ceramic mesoporous patterns with ordered nanoscale pores by using a "top-down" photolithographic technique and the subsequent sacrificial processes of a "bottom-up" self-assembled nanostructure. 相似文献
100.
S. Sutha K. Sakthipandi R. Palanivelu C. Uma Rani T. Jayakumar 《Phase Transitions》2013,86(7):565-576
Monodispersed, nano silica particles have been prepared by sol-gel hydrolysis and condensation of the metal alkoxide using pH buffer. The prepared particles are characterised by XRD, FTIR, BET, SEM, TEM measurements. The measurements reveal that the size and shape of silica particles depend on concentration of water. In addition, the ultrasonic longitudinal velocity and attenuation of the nano silica particles have been measured at a frequency of 5?MHz over a wide range of temperatures from 300?K to 1150?K in nano silica. The different structural transitions, such as monoclinic, orthorhombic, orthorhombic with a non-integral super lattice, stable orthorhombic and hexagonal, which exist in silica are explained based on on-line high-temperature ultrasonic velocity and attenuation measurements. 相似文献