The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

William Eugence Acree - One of the best experts on this subject based on the ideXlab platform.

Paul D. Beer - One of the best experts on this subject based on the ideXlab platform.

Abolghasem Jouyban - One of the best experts on this subject based on the ideXlab platform.

Zenko Yoshida - One of the best experts on this subject based on the ideXlab platform.

  • Luminescence study on preferential solvation of Europium(III) in water/non-Aqueous Solvent mixtures
    Journal of Alloys and Compounds, 2001
    Co-Authors: Takaumi Kimura, Ryuji Nagaishi, Yoshiharu Kato, Zenko Yoshida
    Abstract:

    Abstract The Solvent composition in the first coordination sphere of Eu(III) in water/non-Aqueous Solvent mixtures was investigated by measuring the luminescence lifetime. The inner-sphere hydration numbers of Eu(III) calculated from the lifetimes gave reasonable values in N , N -dimethylacetamide, N , N -dimethylformamide, dimethyl sulfoxide, formamide, hexamethyl phosphoramide, or N -methylformamide with water system. Eu(III) was preferentially solvated by the non-Aqueous Solvent in those systems, over the whole range of the non-Aqueous Solvent mole fraction in the bulk mixtures, X s . The degree of the preferential solvation K PS , defined as the Solvent/water mole ratio in the first coordination sphere to that in the bulk solution, varied considerably with the X s in all the systems. The order of the K PS for Eu(III) was hexamethyl phosphoramide>dimethyl sulfoxide> N -methylformamide> N , N -dimethylformamide>formamide> N , N -dimethylacetamide>water>pyridine>methanol>ethanol>acetone>tetrahydrofuran>acetonitrile at X s =0.5. The Gibbs free energy of transfer of Eu(III) from water to non-Aqueous Solvent was also estimated from the K PS .

Qiu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Temperature dependence of the internal dynamics of a protein in an Aqueous Solvent: Decoupling from the Solvent viscosity
    Chemical Physics, 2013
    Co-Authors: Eugene Mamontov, Hugh O'neill, Qiu Zhang, Suresh M. Chathoth
    Abstract:

    Abstract We have recently observed decoupling of the dynamics of a protein from its Aqueous Solvent [Chu et al., JPCL 3 (2012) 380]; here we report the more detailed studies. We analyzed quasielastic neutron scattering data from a 40 mg/ml solution of lysozyme in (D 2 O) 8 (LiCl) and (H 2 O) 8 (LiCl). The internal dynamics of lysozyme exhibited super-Arrhenius temperature dependence with no crossover to a different regime down to at least 200 K. The decoupling of the internal protein dynamics from the viscosity of its Aqueous Solvent is evident. The temperature dependence of the protein dynamics indicates an apparent dynamic arrest at a temperature above 190 K, whereas the glass transition temperature for the Solvent is around 135–140 K. The internal dynamics of the solvated protein is coupled to the dynamics of its hydration shell, not of the bulk Solvent, which is qualitatively altered by the salt to defer the dynamic arrest to 135–140 K.

  • Apparent Decoupling of the Dynamics of a Protein from the Dynamics of its Aqueous Solvent.
    The journal of physical chemistry letters, 2012
    Co-Authors: Xiang-qiang Chu, Eugene Mamontov, Hugh O'neill, Qiu Zhang
    Abstract:

    Studies of the low-temperature dynamics of proteins in Aqueous solutions are limited by the crystallization of water. In this work, we use a solution of LiCl in D2O as a Solvent for a protein to prevent crystallization and study the dynamics of both the protein and its Aqueous Solvent by quasielastic neutron scattering (QENS) in the temperature range of 210 to 290 K. Our results reveal that, while the dynamics of the Aqueous Solvent undergoes a crossover at about 220 K, the dynamics of the protein itself shows no transition at this temperature. The prevailing view is that the β-fluctuations of the protein are governed by the α-fluctuations of the Solvent; therefore, observation of the apparent decoupling between the dynamics of the protein and its Solvent below the crossover temperature is remarkable.