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101.
Metal-catalyzed coupling methodologies have been employed in the synthesis of the key building block 3'-formyl-2,2':5',2"-terthiophene. Wittig olefinations with this aldehyde have produced five novel beta-styryl-substituted terthiophene monomers. These materials have been fully characterized by NMR spectroscopy, microanalysis, mass spectrometry, and X-ray crystal structure analysis. The results from the UV/visible spectroscopy and cyclic voltammetric investigations are reported. 相似文献
102.
A collisional-radiative model of helium has been developed that incorporates the effect of optical pumping with light that is resonant with an atomic transition. A steady-state solution of the collisional- radiative model with no pumping is used as an initial condition. The pumping radiation is switched on, and the population densities of the atomic levels are calculated as a function of time. Results are given for a wide range of plasma parameters and various pumping conditions. 相似文献
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Yan Z McKee GR Groebner RJ Snyder PB Osborne TH Burrell KH 《Physical review letters》2011,107(5):055004
A set of high frequency coherent (HFC) modes (f=80-250 kHz) is observed with beam emission spectroscopy measurements of density fluctuations in the pedestal of a strongly shaped quiescent H-mode plasma on DIII-D, with characteristics predicted for kinetic ballooning modes (KBM): propagation in the ion-diamagnetic drift direction; a frequency near 0.2-0.3 times the ion-diamagnetic frequency; inferred toroidal mode numbers of n~10-25; poloidal wave numbers of k(θ)~0.17-0.4 cm(-1); and high measured decorrelation rates (τ(c)(-1)~ω(s)~0.5×10(6) s(-1)). Their appearance correlates with saturation of the pedestal pressure. 相似文献
107.
Electrochemistry of room temperature protic ionic liquids 总被引:2,自引:0,他引:2
Zhao C Burrell G Torriero AA Separovic F Dunlop NF MacFarlane DR Bond AM 《The journal of physical chemistry. B》2008,112(23):6923-6936
Eighteen protic ionic liquids containing different combinations of cations and anions, hydrophobicity, viscosity, and conductivity have been synthesized and their physicochemical properties determined. In one series, the diethanolammonium cations were combined with acetate, formate, hydrogen sulfate, chloride, sulfamate, and mesylate anions. In the second series, acetate and formate anions were combined with amine bases, triethylamine, diethylamine, triethanolamine, di-n-propylamine, and di-n-butylamine. The electrochemical characteristics of the eight protic ionic liquids that are liquid at room temperature (RTPILs) have been determined using cyclic, microelectrode, and rotating disk electrode voltammetries. Potential windows of the RTPILs have been compared at glassy carbon, platinum, gold, and boron-doped diamond electrodes and generally found to be the largest in the case of glassy carbon. The voltammetry of IUPAC recommended potential scale reference systems, ferrocene/ferrocenium and cobaltocenium/cobaltocene, have been evaluated and found to be ideal in the case of the less viscous RTPILs but involve adsorption in the highly viscous ones. Other properties such as diffusion coefficients, ionic conductivity, and double layer capacitance also have been measured. The influence of water on the potential windows, viscosity, and diffusion has been studied systematically by deliberate addition of water to the dried ionic liquids. The survey highlights the problems with voltammetric studies in highly viscous room temperature protic ionic liquids and also suggests the way forward with respect to their possible industrial use. 相似文献
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Hornillo-Araujo AR Burrell AJ Aiertza MK Shibata T Hammond DM Edmont D Adams H Margison GP Williams DM 《Organic & biomolecular chemistry》2006,4(9):1723-1729
The syntheses of novel tricyclic pyrrolo[2,3-d]pyrimidine analogues of S6-methylthioguanine are described. The crystal structures and pKa values of these and related O6-methylguanine analogues are reported. All compounds display higher pKa values than O6-methylguanine with the sulfur-containing analogues being the more basic and exhibiting higher stability in aqueous solution. In a standard substrate assay with the human repair protein O6-methylguanine-DNA methyltransferase (MGMT) only the oxygen-containing analogue displayed activity. 相似文献