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81.
Single‐Face/All‐cis Arene Hydrogenation by a Supported Single‐Site d0 Organozirconium Catalyst 下载免费PDF全文
Madelyn Marie Stalzer Dr. Christopher P. Nicholas Dr. Alak Bhattacharyya Dr. Alessandro Motta Dr. Massimiliano Delferro Prof. Tobin J. Marks 《Angewandte Chemie (International ed. in English)》2016,55(17):5263-5267
The single‐site supported organozirconium catalyst Cp*ZrBz2/ZrS (Cp*=Me5C5, Bz=benzyl, ZrS=sulfated zirconia) catalyzes the single‐face/all‐cis hydrogenation of a large series of alkylated and fused arene derivatives to the corresponding all‐cis‐cyclohexanes. Kinetic/mechanistic and DFT analysis argue that stereoselection involves rapid, sequential H2 delivery to a single catalyst‐bound arene face, versus any competing intramolecular arene π‐face interchange. 相似文献
82.
The electrophoresis of a charged soft particle with charged rigid core is considered under a weak imposed field condition. The rigid core of the soft particle is considered to have a finite dielectric permittivity and a fixed volume charge density. The electric potential distribution is determined by solving the Poisson-Boltzman equation out side the rigid core and a Poisson equation within the core along with continuity conditions on the core-shell interface. We have extended the analytic expression of Ohshima (Electrophoresis 27:526–533, 2006) for the electrophoretic mobility of a soft particle with a charged shell to include the effect of the volume charge density of the rigid core. Mobility based on the present expression matches exactly with the existing analytical solutions for a soft particle with an uncharged core. We have also made a comparison of our solution for mobility with an uncharged rigid core with the existing experimental results. The impact of the core charge density on the soft particle mobility is analyzed. 相似文献
83.
S. Pramanik S. S. Bhattacharyya P. Chattopadhyay 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):237-243
A new stable chelating resin was synthesized by incorporating 2-aminothiophenol into Merrifield polymer through C-N covalent
bond and characterized by elemental analysis, IR and thermal study. The sorption capacity of the newly formed resin for Hg2+ as a function of pH has been studied using 203Hg radioisotope. The resin exhibits no affinity to alkali or alkaline earth metal ions and common anions. The separation of
mercury(II) in presence of different alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+), common anions (ClO4
−, SO4
2−) and other diverse ions (Ag+, Cu2+, Pb2+, Fe3+, Ni2+ and Zn2+) has been checked. In column operation it has been observed that Hg2+ content of the waste water can be removed at usual pH of natural water. Mercury was determined by isotope dilution method
and the concentration of Hg2+ in the waste water spiked with 203Hg was found to be 0.05 to 0.09 μg/ml. 相似文献
84.
Bhattacharyya S Salvetat JP Roy D Heresanu V Launois P Saboungi ML 《Chemical communications (Cambridge, England)》2007,(41):4248-4250
Highly ordered self-assembled multi-layer structures with denatured collagen wrapped single wall carbon nanotubes and surfactant systems were obtained through bioinspired methodology. 相似文献
85.
Sahu K Mondal SK Ghosh S Roy D Sen P Bhattacharyya K 《The journal of physical chemistry. B》2006,110(2):1056-1062
Using femtosecond time-resolved fluorescence spectroscopy, it is shown that the solvation dynamics in the two partially folded states (IS' and IS' ') of a protein, cytochrome C, are very different. In the case of IS' (formed by the addition of 2 mM sodium dodecyl sulfate, SDS) almost the entire dynamic solvent shift of coumarin 153 (C153) is captured in a picosecond setup and the contribution of the ultrafast component (0.5 ps) is very small (5%). Solvation dynamics of IS' ' (formed by 2 mM SDS and 5 M urea) displays a major component (47%) of 1.3 ps. This indicates that the structure of IS' ' is much more open and exposed compared to that of IS'. The difference in the dynamics of IS' and IS' ' is attributed to differences in their structure, particularly near the heme region, and the presence of urea in IS' '. 相似文献
86.
Examined in this study is the kinetics of a net 2e− transfer between [Fe2(μ‐O)(phen)4(H2O)2]4+ ( 1 ) and its hydrolytic derivatives [Fe2(μ‐O)(phen)4(H2O)(OH)]3+ ( 2 ) and [Fe2(μ‐O)(phen)4(OH)2]2+ ( 3 ) with in aqueous media and in presence of excess 1,10‐phenanthroline (phen). The reaction is quantitative with a 1 : 1 stoichiometry between the oxidant and reductant to produce ferroin ([Fe(phen)3]2+) and . The order of reactivity of the oxidant species is 1 > 2 > 3 , in agreement with the progressive cationic charge reduction. The reactions appear to be inner‐sphere where the initial one‐electron proton‐coupled redox (1e−, 1H+; electroprotic) seems to be rate‐determining. 相似文献
87.
88.
This paper presents a new value at risk (VaR) estimation model for equity returns time series and tests it extensively on Stock Indices of 14 countries. Two most important stylized facts of such series are volatility clustering, and non-normality as a result of fat tails of the return distribution. While volatility clustering has been extensively studied using the GARCH model and its various extensions, the phenomenon of non-normality has not been comprehensively explored, at least in the context of VaR estimation. A combination of extreme value theory (EVT) and GARCH has been explored to analyze financial data showing non-normal behavior. This paper proposes a combination of the Pearson’s Type IV distribution and the GARCH (1, 1) approach to furnish a new method with superior predictive abilities. The approach is back tested for the entire sample as well as for a holdout sample using rolling windows. 相似文献
89.
The problem of electromagnetic scattering from a plate with a rim loading for transverse electric (TE) and transverse magnetic (TM) polarizations is investigated. The analysis is based on the work of R. Tiberio et al. (ibid., vol.AP-33, no.8, p.867-73, 1985) on the uniform geometrical theory of diffraction analysis of a wedge with two face impedances. The two-dimensional field is converted into three-dimensional field using Siegel's 2-D to 3-D conversion formula. The corner effects are neglected. The width of the coating around the edges which gives the same result as a uniformly coated plate of the same size is estimated. Hence, the percentage of saving of radar-absorbing material (RAM) can also be estimated for practical application in radar cross-section (RCS) reduction problems 相似文献
90.
A discrete reliability-growth model (appropriate for success-failure data) whose derivation parallels that of a popular nonhomogeneous Poisson process model (appropriate for continuous failure time data) is considered.,Following J. M. Finkelstein (ibid. vol.R-32, p.508-11, Dec. 1983) continuous analog estimators are defined for use with the discrete model when there is a constant prespecified number of test trials between system configuration changes. The large-sample properties of these estimators, including consistency and normality, are established. Large-sample standard-error formulas and confidence interval procedures are developed 相似文献