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21.
Rauth Goutam Kumar Dinda Joydev Jasimuddin Sk. Sinha Chittaranjan 《Transition Metal Chemistry》2003,28(1):88-95
1-Alkyl-2-(naphthyl--azo)imidazoles [-NaiR; R = Me (a), Et (b), CH2Ph (c)] react with Pd(MeCN)2Cl2 to yield Pd(-NaiR)Cl2
(2), the i.r. spectra of which support the presence of a cis-PdCl2 configuration. The complexes react with catechols in the presence of Et3N to yield ternary complexes [Pd(-NaiR)(O,O)] [O,O = pyrocatecholato (cat) (3), 4-t-butylcatecholato (tbcat) (4), 3,5-di-t-butylcatecholato (dtbcat) (5), and tetrachlorocatecholato (tccat) (6)], which were characterized by elemental analysis, i.r. and 1H-n.m.r. spectral data. Redox studies by cyclic voltammetry suggest the existence of four successive redox couples wherein two responses, positive to s.c.e. are due to catechol to semiquinone and semiquinone to quinone oxidation, respectively; the couples at negative to s.c.e. are referred to azo reductions. The complexes exhibit ligand-ligand charge-transfer transitions in the near-i.r. region. The band position is largely dependent upon the substitutent on the catechol frame and exhibits negative solvatochromic effects. The transition is qualitatively assigned as the HOMO (cat) LUMO (-NaiR) transition. This fact is also supported by theoretical calculations using the PM3 method. 相似文献
22.
Sk.F. Ahmed P.K. Ghosh S. Khan M.K. Mitra K.K. Chattopadhyay 《Applied Physics A: Materials Science & Processing》2007,86(1):139-143
We have observed low-macroscopic field electron emission from wide bandgap nanocrystalline Al doped SnO2 thin films deposited on glass substrates. The emission properties have been studied for different anode-sample spacings and for different Al concentrations in the films. The turn-on field and approximate work function were calculated and we have tried to explain the emission mechanism from this. The turn-on field was found to vary in the range 5.6–7.5 V/μm for a variation of anode sample spacing from 80–120 μm. The turn-on field was also found to vary from 4.6–5.68 V/μm for a fixed anode-sample separation of 80 μm with a variation of Al concentration in the films 8.16–2.31%. The Al concentrations in the films have been measured by energy dispersive X-ray analysis. Optical transmittance measurement of the films showed a high transparency with a direct bandgap ∼3.98 eV. Due to the wide bandgap, the electron affinity of the film decreased. This, along with the nanocrystalline nature of the films, enhanced the field emission properties. PACS 81.20.Fw; 61.10.-i; 79.70.+q 相似文献
23.
A pulsed master oscillator fiber power amplifier working in nanosecond range has been developed. An ytterbium-doped double-clad
(large mode area) optical fiber was used as an amplifying medium. Actively Q-switched Nd:YVO laser was used as a seed of light
pulses. The system worked at the repetition rate from 10 kHz to 40 kHz. At the amplifier output, pulses of 10.9 kW peak-power
were achieved. The laser system worked at the slope efficiency of 30%. 相似文献
24.
25.
We derive simple expressions for the asymptotic variance of the kernel-density estimator of a stationary continuous-time process in one and d dimensions and relate convergence rates to sample path smoothness. Important applications include methods for selecting optimal smoothing parameters and construction of confidence bands for testing hypotheses about the density. In a simulation study the results are applied to bandwidth selection for discrete-time processes that can be modelled as continuous-time processes sampled at a high rate. 相似文献
26.
Małgorzata Skórka Monika Asztemborska 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,332(1):1-8
Sodium cholate and sodium deoxycholate dissolved in formamide were applied as stationary phases in gas chromatography. The critical micelle concentration of sodium cholate and deoxycholate in formamide was determined by surface tension measurements. The relation of retention times vs. concentration of bile salts was investigated for isomers of monoterpenes and xylenes. The enthalpy of binding of selected compounds with sodium cholate and sodium deoxycholate monomers and micelles was determined. 相似文献
27.
Nirvik Sen K. Saswani K. K. Singh S. Barkade S. Mukhopadhyay S. M. Chavan Sk. M. Ali K. T. Shenoy 《Journal of Radioanalytical and Nuclear Chemistry》2017,312(2):255-262
Batch extraction of uranium(VI) from uranyl nitrate solutions using TiAP in ionic liquids ([BMIM]PF6 and [HMIM]PF6) is studied. Effects of acidity, TiAP concentration in ionic liquid and temperature on distribution coefficient are studied. Results show that distribution coefficient increases with an increase in acidity and reduces with an increase in the alkyl chain length of the cation of the ionic liquid. Extraction of uranium(VI) by TiAP-[HMIM]PF6 system is found to involve two molecules of the extractant per metal ion and extraction is found to change from being exothermic to endothermic as the percentage of the extractant is increased. 相似文献
28.
29.
Ane Funderud Heidi H Henanger Tilahun T Hafte Paul S Amieux Sigurd ?rstavik Bj?rn S Sk?lhegg 《BMC biochemistry》2006,7(1):20
Background
Two main genes encoding the catalytic subunits Cα and Cβ of cyclic AMP dependent protein kinase (PKA) have been identified in all vertebrates examined. The murine, bovine and human Cβ genes encode several splice variants, including the splice variant Cβ2. In mouse Cβ2 has a relative molecular mass of 38 kDa and is only expressed in the brain. In human and bovine Cβ2 has a relative molecular mass of 47 kDa and is mainly expressed in lymphoid tissues. 相似文献30.
M. Chvojka B. Králiková J. Krása L. Láska K. Mašek K. Rohlena J. Skála W. Mróz P. Parys J. Wolowski E. Woryna 《Czechoslovak Journal of Physics》1994,44(9):851-864
Particle diagnostics of Al-laser-produced plasma based on ion collectors identified three groups of emitted ions. Their velocity distributions were analyzed to obtain the mean ion energy, energy and charge carried by ions, including the angular distributions of these quantities. The electron temperature evaluated from these measurements was compared with X-ray results. A satisfactory agreement between the two sets of data was found. In both the cases the electron temperature grows only very slowly with the incident laser power. Origin of different ion groups is discussed. Iodine photodissociation laser system PERUN was used as a driver. 相似文献