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111.
A complete mass spectral fragmentation pattern of naturally abundant ethyldigermane is presented. The base peak occurs at m/e 148 in the Ge2H×=0←5 + region and not in the parent region. Three metastable peaks are observed at m/e 52.70, m/e 59.36, and m/e 125.63 respectively. 相似文献
112.
Structural Chemistry - Certain DNA minor groove binders, especially bis-benzimdazole containing compounds, such as Hoechst 33258 and its derivatives, act as potent topoisomerase I inhibitors. The... 相似文献
113.
MgO nanoparticles (NPs) and Gr/MgO nanocomposite (NC) have been synthesized by hydrothermal route. X-ray diffraction (XRD) analysis confirmed the crystalline cubic phase of MgO and Gr/MgO NC. Raman spectroscopy was used to study the defects in the NCs. Electron microscopy study display spherical NPs of MgO on graphene sheets. UV-visible spectroscopy shows a red shift in the absorption band and a significant reduction in the bandgap for Gr/MgO NC. The improvements in dielectric properties of NC can be ascribed to interfacial polarization between rGO and MgO. The rGO in the NCs supports the electron transfer and improves the electrical conductivity. 相似文献
114.
Effects of deposition temperature on the structural and morphological properties of thin ZnO films fabricated by pulsed laser deposition 总被引:3,自引:0,他引:3
Rakhi Khandelwal Amit Pratap Singh Avinashi Kapoor Sorin Grigorescu Paola Miglietta Nadya Evgenieva Stankova Alessio Perrone 《Optics & Laser Technology》2008,40(2):247-251
ZnO thin films were grown on Si(1 0 0) substrates using pulsed laser deposition in O2 gas ambient (10 Pa) and at different substrate temperatures (25, 150, 300 and 400 °C). The influence of the substrate temperature on the structural and morphological properties of the films was investigated using XRD, AFM and SEM. At substrate temperature of T=150 °C, a good quality ZnO film was fabricated that exhibits an average grain size of 15.1 nm with an average RMS roughness of 3.4 nm. The refractive index and the thickness of the thin films determined by the ellipsometry data are also presented and discussed. 相似文献
115.
116.
Bell AF Stratton CF Zhang X Novichenok P Jaye AA Nair PA Parikh S Rawat R Tonge PJ 《Journal of the American Chemical Society》2007,129(20):6425-6431
InhA, the enoyl reductase from Mycobacterium tuberculosis, catalyzes the NADH-dependent reduction of trans-2-enoyl-ACPs. In the present work, Raman spectroscopy has been used to identify catalytically relevant changes in the conformation of the nicotinamide ring that occur when NADH binds to InhA. For 4(S)-NADD, there is an 11 cm-1 decrease in the wavenumber of the C4-D stretching band (nuC-D) and a 50% decrease in the width of this band upon binding to InhA. While a similar reduction in line width is observed for the corresponding band arising from 4(R)-NADD, nuC-D for this isomer increases 34 cm-1 upon binding to InhA. These changes in nuC-D indicate that the nicotinamide ring adopts a bound conformation in which the 4(S)C-D bond is in a pseudoaxial orientation. Mutagenesis of F149, a conserved active site residue close to the cofactor, demonstrates that this enzyme-induced modulation in cofactor structure is directly linked to catalysis. In contrast to the wild-type enzyme, Raman spectra of NADD bound to F149A InhA resemble those of NADD in solution. Consequently, F149A is no longer able to optimally position the cofactor for hydride transfer, which correlates with the 30-fold decrease in kcat and 2-fold increase in D(V/KNADH) caused by this mutation. These studies thus substantiate the proposal that hydride transfer is promoted by pseudoaxial positioning of the NADH pro-4S bond, and indicate that catalysis of substrate reduction by InhA results, in part, from correct orientation of the cofactor in the ground state. 相似文献
117.
Richa Vinayak Dhritiman Dey Dipanjan Ghosh Dhrubajyoti Chattopadhyay Abhrajyoti Ghosh Hari Pada Nayek 《应用有机金属化学》2018,32(3)
Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C6H5)2Sn(L)] ( 1 ), [(t‐Bu)2Sn(L)] ( 2 ) and [(t‐Bu)2Sn(L')] ( 3 ) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H 2 L or H 2 L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (1H, 13C and 119Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1 – 3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed. 相似文献
118.
Accurate determination of concentration of immunoglobulin (IgG) to tetanus toxoid is important in order to evaluate the immunogenicity of tetanus toxoid vaccines, immune competence in individual patients and to measure the prevalence of immunity in populations. Surface modified polyacrylonitrile (PAN) fibers were evaluated as a matrix to develop highly sensitive method for the detection of anti-tetanus antibody in a sandwich ELISA format. In the proposed method tetanus toxoid immobilized on modified PAN fibers was used to detect anti-tetanus antibody (raised in horse hence represented as horse anti-tetanus toxoid or HAT-Ab) with horse raddish peroxidase enzyme conjugated with Rabbit anti-Horse IgG (RAH-HRP) as the label within 2.5 h. A sigmoidal pattern for the detection of different concentration of antibody ranging from 1.0 to 0.0001 IU mL−1 was validated. The immunoassay recorded a very high sensitivity as concentration as low as 0.0005 IU mL−1 of HAT-Ab was detected. The intra- and inter-assay precision for 3 parallel measurements of 0.01 and for 0.001 IU mL−1 of antibody varied from 5.4% to 11% and 5.7% to 20% respectively. PAN fibers were also used to qualitatively access the presence of different level of anti-tetanus antibody spiked in human blood. Seroepidemiological studies to measure the immunity against tetanus were conducted with twenty-five human beings belonging to various age groups using modified PAN-ELISA. The sensitivity, specificity and the reproducibility of the developed immunoassay indicate the potential application of modified PAN fibers in the field of immunodiagnostics. 相似文献
119.
Hwang IC Chandran RP Singh NJ Khandelwal M Thangadurai TD Lee JW Chang JA Kim KS 《Inorganic chemistry》2006,45(20):8062-8069
The imidazole-based ligands, bis(imidazol-1-yl)methane (Bizm, 1a) and (pyrenyl)bis(imidazol-1-yl) methane (Pbizm,2a) were prepared. With LiClO4, these two compounds formed two novel organic-inorganic hybrid materials: a 3D network polymer Li(Bizm).ClO4 (1b) and a 1D chain polymer Li(Pbizm)2.ClO4 (2b). The intriguing topological and physiochemical characteristics of 1b and 2b are reported on the basis of the X-ray single-crystal structure analysis and Li ion binding studies. 相似文献
120.
The kinetics of ligand substitution between aquapentacyanoruthenate(II) ion, [Ru(CN)5H2O]3− and 4-cyanopyridine (4-CNpy) has been investigated spectrophotometrically in the presence of anionic surfactant micelle,
namely sodium dodecylsulphate (SDS) at 400 nm (λmax of the intense yellow product [Ru(CN)54-CNpy]3−) under pseudo-first-order conditions using at least 10% excess of 4-CNpy over [Ru(CN)5H2O]3−. The reaction was studied as a function of [Ru(CN)5H2O3−], [4-CNpy], [SDS], pH, ionic strength and temperature, by varying each of these variables one at a time. The reaction exhibited
overall second-order kinetics, being first order each in [4-CNpy] and [Ru(CN)5H2O3−] over a wide concentration range. Variation of ionic strength of the medium had a significant negative effect on the rate.
The SDS micelle, being negatively charged, does not reveal any regular effect except at or near its critical micelle concentration
(c.m.c). The rate of reaction was measured at different temperatures, and the activation parameters were computed using Arrhenius
and Eyring plots. A plausible mechanism consistent with the experimental results has been proposed. 相似文献