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151.
Ce doped ZnO nanoparticles (Zn1−xCexO, x = 0.0, 0.05 and 0.1) have been synthesized by sol–gel method at annealing temperature of 500 °C for 1 h under Ar atmosphere.
The synthesized samples have been characterized by powder X-ray diffraction (XRD), energy dispersive X-ray studies, UV–Visible
spectrophotometer and fourier transform infrared (FTIR) spectroscopy. The XRD measurements indicate that the prepared nanoparticles
have a hexagonal wurtzite structure and CeO2 crystallites. The calculated average crystalline varied from 21.97 to 15.62 nm with increase in Ce concentrations. The increase
in lattice parameters reveals the substitution of Ce into ZnO lattice. The presence of functional groups and the chemical
bonding is confirmed by FTIR spectra. PL spectra of the Zn1−xCexO system show that the shift in near band edge emission from 386 to 363 nm and a shift in blue band emission from 517 to 485 nm
which confirms the substitution of Ce into the ZnO lattice. 相似文献
152.
SENTHILKUMAR Annamalai THARINI Kumaravel SETHURAMAN Mathur Gopalakrishnan 《物理化学学报》2012,28(2):399-406
Three synthesized piperidin-4-one oximes,3-ethyl-2,6-diphenyl-piperidin-4-one oxime(A),1-methyl-3-isopropyl-2,6-diphenyl-piperidin-4-one oxime(B),and 3-isopropyl-2,6-diphenyl-piperidin-4-one oxime(C),were tested at different concentrations to determine their ability to inhibit corrosion of mild steel in 1 mol.L-1 H2SO4 and measured by a mass loss method(at various temperatures),polarization and impedance measurements,X-ray diffraction(XRD),scanning electron microscopy(SEM) with energy-dispersive X-ray spectroscopy(EDS),and a quantum chemical method.The synergistic influence of compounds A,B and C with iodides has also been evaluated.All three compounds show good inhibition efficiency in the following order:A>B>C.Compounds A,B and C were found to physically adsorb on the surface of mild steel while obeying the Temkin isotherm.Polarization measurements indicated that these compounds behave as a mixed mode inhibitor.XRD and SEM with EDS studies revealed the formation of a protective barrier on the mild steel surface by these oximes.The electron donating ability of the studied molecules was tested using semi empirical methods.The studies revealed that the oxime nitrogen,the piperidine moiety,and the phenyl ring assist largely in corrosion control.The studies also showed that the steric crowding by the alkyl group in the piperidine ring affects the inhibitor efficiency.Further,it is interesting to note that all of the studied compounds exhibit synergism with iodide ions. 相似文献
153.
Sheo B. Singh Hiranthi Jayasuriya Kithsiri B. Herath Chaowei Zhang John G. Ondeyka Deborah L. Zink Sookhee Ha Gopalakrishnan Parthasarathy Joseph W. Becker Jun Wang Stephen M. Soisson 《Tetrahedron letters》2009,50(37):5182-5185
Inhibition of fatty acid synthesis is emerging as a valuable target for antibacterial agents. Platensimycin and platencin are novel natural products that were reported recently to inhibit the FabF and FabF/FabH condensing enzymes, respectively, present in the fatty acid biosynthetic pathway. Selective inhibition of these enzymes by platensimycin and platencin accounts for their potent antibiotic activity. We have continued our quest to find additional members of this class of compounds leading to discovery of platensimycin A1, a hydroxylated congener. We report herein the isolation, structure, antibacterial and enzymatic activities, and co-crystal structure bound to Escherichia coli FabF. The lower activity of platensimycin A1 suggests that substitution at C-14 is detrimental for the activity. 相似文献
154.
J. Thanusu V. Kanagarajan M. Gopalakrishnan 《Research on Chemical Intermediates》2010,36(9):1073-1084
Abstract
A series of bis heterocycles comprising both piperidine and thiohydantoin nuclei namely 3-(3-alkyl-2,6-diarylpiperin-4-ylidene)-2-thioxoimidazolidin-4-ones is synthesized and characterized by melting point, elemental analysis, MS, FT–IR, one-dimensional NMR (1H, D2O exchanged 1H and 13C), two-dimensional HOMOCOSY, and NOESY spectroscopic data. 相似文献155.
The present article reports the growth of single crystals of a complex Orthonitroaniline with picric acid (2[C6H6N2O2]·C6H2(NO2)3OH) (ONAP) by solution growth (slow evaporation) method at room temperature. Single crystal XRD, UV–vis spectral analysis and TGA/DTA studies were carried out. FT-IR and Raman spectra were recorded to explore information of the functional groups. The high-resolution X-ray diffraction curve reveals the internal structural low angle boundaries. The PL spectrum of the title compound shows green emission. Dielectric behaviour was investigated at 33 and 70 °C. The dipole moment and first-order hyperpolarizability (β) values were evaluated by using Gaussian 98 W software package with the help of B3LYP the density functional theory (DFT) method. The possible modes of vibrations are theoretically predicted by factor group analysis. The mechanical stability of the grown crystal was tested with Vicker’s microhardness tester and the work hardening coefficient of the grown material was estimated. 相似文献
156.
Mezler M Hermann D Swensen AM Draguhn A Terstappen GC Gross G Schoemaker H Freiberg G Pratt S Gopalakrishnan SM Nimmrich V 《Combinatorial chemistry & high throughput screening》2012,15(5):372-385
Dysfunction of P/Q-type calcium channels is thought to underlie a variety of neurological diseases. There is evidence that migraine, Alzheimer's disease, and epilepsy involve a gain-of-function of the channel, leading to abnormal presynaptic vesicle release. P/Q-channel blockers may normalize current flow and consequently lead to an alleviation of disease symptoms. Although the medical need is high, there are no such compounds on the market. Here we describe a high throughput screen (HTS) for P/Q-type calcium channel blockers and the confirmation of hits by automated electrophysiology. We generated a HEK293 cell line stably expressing the α1A subunit of the P/Q-type calcium channel under control of a tetracycline (Tet) promoter. The accessory β1.1 and α2δ1 subunits were co-expressed constitutively. The cell line was pharmacologically characterized by ion channel specific modulators, and revealed functional P/Q-type calcium currents. Using a fluorescence imaging plate reader (FLIPR), an assay for P/Q-type calcium channels was established based on a calcium sensitive dye. HTS of a 150,000 compound-containing sub-library led to the identification of 3262 hits that inhibited the fluorescence signal with potencies below 10 μM. Hit-to-lead (HTL) efforts identified 12,400 analogues. Compounds were clustered into 37 series, and 8 series of interest were prioritized. An electrophysiological secondary screen, providing a more direct measure of channel function, was implemented into the HTL process. 27 selected exemplars of different chemotypes were validated by automated whole-cell patch clamp analysis at inactivated channel state. The discovery of P/Q-channel blockers may foster the development of new therapeutics for a variety of neurological diseases. 相似文献
157.
Spin locking of the nuclear magnetization of a spin with S=1 such as deuterium in the presence of a radio-frequency field under magic angle spinning (MAS) is described in terms of adiabatic modulations of the energy levels. In a brief initial period, part of the initial density operator nutates about the Hamiltonian and is dephased. The remaining spin-locked state undergoes persistent oscillatory transfer processes between various coherences with a periodicity given by the rotation of the sample. While all crystallites in the powder undergo such periodic transfer processes, the phases of the oscillations depend on the angle gamma of the crystallites. The angle gamma is the azimuthal angle defining the orientation of the unique axis of the quadrupolar interaction tensor in a rotor-fixed frame. The theory is extended to describe cross-polarization between spins S=1 and I=12 under MAS. There are four distinct Hartmann-Hahn matching conditions that correspond to four zero-quantum matching conditions, all of which are shifted and broadened compared to their spin S=12 counterparts. These matching conditions are further split into a family of sideband conditions separated by the spinning frequency. The theory allows the calculation of both shifts and broadening factors of the matching conditions, as verified by simulations and experiments. 相似文献
158.
Effect of SDS on the self-assembly behavior of the PEO-PPO-PEO triblock copolymer (EO)20(PO)70(EO)20
Ganguly R Aswal VK Hassan PA Gopalakrishnan IK Kulshreshtha SK 《The journal of physical chemistry. B》2006,110(20):9843-9849
The mixed micellar system comprising the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-based triblock copolymer (EO)(20)(PO)(70)(EO)(20) (P123) and the anionic surfactant sodium dodecyl sulfate (SDS) has been investigated in aqueous media by small-angle neutron scattering (SANS) and viscosity measurements. The aggregation number of the copolymer in the micelles decreases upon addition of SDS, but a simultaneous enhancement in the degree of micellar hydration leads to a significant increase in the micellar volume fraction at a fixed copolymer concentration. This enhancement in the micellar hydration leads to a marked increase in the stability of the micellar gel phase until it is destroyed at very high SDS concentration. Mixed micellar systems with low and intermediate SDS concentrations form the micellar gel phase in much wider temperature and copolymer concentration ranges than the pure copolymer micellar solution. A comparison of the observed results with those for the copolymers (EO)(26)(PO)(40)(EO)(26) (P85) and (EO)(99)(PO)(70)(EO)(99) (F127) suggests that the composition of the copolymers plays a significant role in determining the influence of SDS on the gelation characteristics of the aqueous copolymer solutions. Copolymers with high PO/EO ratios show an enhancement in the stability of the gel phase, whereas copolymers with low PO/EO ratios show a deterioration of the same in the presence of SDS. 相似文献
159.
A room temperature sphere-to-rod transition of the polyethylene oxide-polypropylene oxide-polyethylene oxide-based triblock
copolymer, (PEO)20(PPO)70 (PEO)20 micelles have been observed in aqueous medium under the influence of ethanol and sodium chloride. Addition of 5–10% ethanol
induces a high temperature sphere-to-rod transition of the micelles, which is brought to room temperature upon addition of
NaCl. The inference about the change in the shape of the micelles has been drawn from small-angle neutron scattering (SANS)
and viscosity studies. 相似文献
160.
Janarthanan Gopalakrishnan M. N. Sudheendra Rao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):754-764
Though aminophosphines have been known for a century, and a large variety of such compounds has been synthesized for different aspects of their chemistry, until now, no examples are available on phosphines containing three different amino substituents. In this study, the first examples of such chiral tris(amino)phosphines and o-phenylenedioxo(amino)phosphines were successfully synthesized using condensation reactions, and they were converted to their respective selenides using a simple oxidative addition reaction. The compounds are characterized by IR, 1H, and 13C NMR spectral techniques, and the spectral aspects are presented. The spectral studies (i) indicated that they are indeed powerful tools for structural elucidation of compounds; (ii) showed the effect of heavier selenium atom on the P–N bond rotation process; and (iii) further supported the fact that dipolar structure predominates over the π-bond structure for the aminophosphine selenides. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献