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Chen D.,Gannan Normal University | Savidge T.,Baylor College of Medicine
Science | Year: 2015

Fried et al. (Reports, 19 December 2014, p. 1510) demonstrate electric field-dependent acceleration of biological catalysis using ketosteroid isomerase as a prototypic example. These findings were not extended to aqueous solution because water by itself has field fluctuations that are too large and fast to provide a catalytic effect. Given physiological context, when water electrostatic interactions are considered, electric fields play a less important role in the catalysis.

Tang S.,Gannan Normal University | Cao Z.,Xiamen University
Physical Chemistry Chemical Physics | Year: 2012

Graphene oxides (GOs) may offer extraordinary potential in the design of novel catalytic systems due to the presence of various oxygen functional groups and their unique electronic and structural properties. Using first-principles calculations, we explore the plausible mechanisms for the oxidative dehydrogenation (ODH) of propane to propene by GOs and the diffusion of the surface oxygen-containing groups under an external electric field. The present results show that GOs with modified oxygen-containing groups may afford high catalytic activity for the ODH of propane to propene. The presence of hydroxyl groups around the active sites provided by epoxides can remarkably enhance the C-H bond activation of propane and the activity enhancement exhibits strong site dependence. The sites of oxygen functional groups on the GO surface can be easily tuned by the diffusion of these groups under an external electric field, which increases the reactivity of GOs towards ODH of propane. The chemically modified GOs are thus quite promising in the design of metal-free catalysis. © 2012 the Owner Societies.

Zhang Z.,Gannan Normal University
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2015

In this paper, we would like to improve the recent results of Yamazaki on the regularity criteria for the threedimensional magentohydrodynamic equations © 2014 Springer Basel.

Tang S.,Gannan Normal University | Cao Z.,Xiamen University
Journal of Physical Chemistry C | Year: 2012

The interactions of ammonia with graphene oxides (GO) were studied by density functional theory calculations. Our results indicate that the adsorption of NH 3 on GO is generally stronger than that on graphene because of the presence of diverse active defect sites, such as the hydroxyl and epoxy functional groups and their neighboring carbon atoms. These surface oxygen sites can form OH···N and O···HN hydrogen bonds with NH 3 and enhance charge transfers from NH 3 to the graphene oxide. The dissociation of the adsorbed NH 3 into the chemisorbed NH 2 or NH species through the H atom abstractions leads to hydroxyl group hydrogenation and ring-opening of epoxy group. The reactions of NH 3 with the hydroxyl and epoxy groups are predicted to be exothermic with different energy barriers, depending on the oxidation species and the atomic arrangement of these groups. The hydroxyl group exhibits relatively higher reactivity toward hydrogen abstraction from the adsorbed NH 3 than the epoxy group in GO with a single oxygen group. The presence of a neighboring OH group may activate the oxygen groups to facilitate the surface reaction of NH 3. Followed by the ring-opening of the epoxy group, the newly formed hydroxyl group can be removed by the second H atom abstraction from NH 2. The calculated density of states of the adsorbed systems also reveals strong interactions between GO and NH 3. The calculated results show good agreement with available experimental observations. © 2012 American Chemical Society.

Zhang Z.,Gannan Normal University
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2015

This paper concerns about the Cauchy problem for the three-dimensional Navier–Stokes equations and provides a regularity criterion in terms of the gradient of one velocity component. This improves previous results. © 2015, Springer Basel.

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