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91.
Experiments have been performed in which fs-timescale laser pulses, focused to an intensity ~1016 W cm?2, are able to directly create and interact with solid density plasma (1). We have performed one-dimensional simulations of the experiments with a kinetic model which solves Maxwell's equations coupled to the Fokker–Planck equation enabling us to self-consistently model the non-local heat flow and absorption process. We find that the heat-flux is magnetized by the laser field and is inhibited relative to the Spitzer value. 相似文献
92.
Novel organometallic chalcones functionalized with a crown ether fragment as optical ion chemosensors
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Fernando Godoy Tamara Maldonado Erick Flores Nicolás Agurto Rodrigo González Guillermo Ferraudi Graham Lappin 《应用有机金属化学》2018,32(3)
We previously reported the synthesis and characterization of new organometallic chalcones derived from ferrocene, cyrhetrene and cymantrene functionalized with a benzo‐15‐crown‐5 fragment. The ferrocene and cyrhetrene chalcones have been investigated as chemosensors for metal ions with optical response in acetonitrile. Several metal ions were selected considering the diameter of the cavity and the charge‐to‐radius ratio of the cation. The stoichiometry of the complexes was determined using Job's method. It was found that Na+ and Ca2+ complexes have a 1:1 stoichiometry while a 2:1 (metaloligand‐to‐cation) stoichiometry was determined for Ba2+ and Pb2+ complexes. The association constants were calculated according to the stoichiometry of the complex and the results showed that they are directly affected by the electron‐withdrawing nature of the organometallic fragment. Moreover, complexes of ferrocenyl chalcone have larger association constants than those of the cyrhetrenyl analogue. This experimental observation is consistent with the electronic properties of the ferrocenyl fragment. 相似文献
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Hubert Schmidbaur Graham A. Bowmaker Ulrich Deschler Cornelia Dörzbach Rudolf Herr Beatrix Milewski-mahrla 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):167-170
Abstract Structural data of phosphorus ylides are summarized and discussed. Conformational preferences in solution and in the solid state, as followed by NMR spectroscopy and X-ray diffraction, indicate a strong gauche effect for the lone pairs of electrons at the ylidic carbon atom. One- and two-electron oxydation of ylide carbanions is accomplished with copper(II) as the oxidant, leading to oxidative coupling or to halogenation, respectively. 相似文献
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J. Graham Dawber R. Glynn Skerratt John C. Tebby Albert A. C. Waite 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1261-1268
Abstract Third order rate constants have been determined for the alkaline hydrolysis of four series of alkylphenylphosphonium salts and alkylphenylbenzylphosphonium salts at various temperatures in 50%–70% v/v aqueous tetrahydrofuran and 70% v/v aqueous methanol. Thermodynamic activation parameters have been calculated for the reactions of each substrate and the effects of varying the ratio of alkyl to phenyl groups have been compared, as well as the effects of changes in the nature of the alkyl group. Solvation, as revealed by trends in entropy of activation, plays a largely counter-balancing role with respect to enthalpy and energy of activation. The role of the isokinetic effect is discussed. In aqueous tetrahydrofuran, solvation effects on the hydrolyses of phosphonium salts change as the mole fraction of water changes, and for aqueous methanol the trends in the thermodynamic activation parameters actually reverse. 相似文献