Shear Viscosity from the Effective Coupling of Gravitons

We review the progress in the holographic calculation of shear viscosity for strongly coupled field theories. We focus on the calculation of shear viscosity from the effective coupling of transverse gravitons and present some explicit examples.Comment: 10 pages, invited presentation for the 9th Asia-Pacific International Conference On Gravitation And Astrophysics (ICGA 9), June 28-July 2, 2009, Wuhan, China; for the proceedings to be published by World Scientifi

A second ortho­rhom­bic polymorph of 3,5-diphenyl-4H-1,2,4-triazol-4-amine

The present crystal structure is the second ortho­rhom­bic polymorph of the title compound, C14H12N4. Whereas the structure in Pnma with Z′ = 0.5 is already known [Ikemi et al. (2002 ▶). Heterocycl. Commun. 8, 439–442], the present structure crystallizes in the space group Pbca with Z′ = 1. The dihedral angle between the two phenyl rings is 23.5 (4)° and the dihedral angles between central ring and the phenyl rings are 41.0 (3) and 26.3 (5)°. In the 4-amino-1,2,4-trizole fragment, the C=N distances are 1.321 (3) and 1.315 (3) Å, which are much shorter than the C—N distances of 1.367 (3) and 1.357 (3) Å. In the crystal, adjacent mol­ecules are linked by N—H⋯N hydrogen bonds

Shape control of bimetallic nanocatalysts through well-designed colloidal chemistry approaches

This is the published version. ©Copyright 2012 Royal Society of ChemistrySynthesis of bimetallic nanomaterials with well controlled shape is an important topic in heterogeneous catalysis, low-temperature fuel cell technology, and many other fields. Compared with monometallic counterparts, bimetallic nanocatalysts endow scientists with more opportunities to optimize the catalytic performance by modulating the charge transfer between different metals, local coordination environment, lattice strain and surface element distribution. Considering the current challenges in shape controlled synthesis of bimetallic nanocatalysts, this tutorial review highlights some significant achievements in preparing bimetallic alloy, core–shell and heterostructure nanocrystals with well-defined morphologies, summarizes four general routes and some key factors of the bimetallic shape control scenarios, and provides some general ideas on how to design synthetic strategies to control the shape and exposing facets of bimetallic nanocrystals. The composition and shape dependent catalytic behaviours of bimetallic nanocrystals are reviewed as well

catena-Poly[[triaqua­zinc(II)]-μ-1H-1,2,4-triazole-3,5-dicarboxyl­ato]

In the title compound, [Zn(C4HN3O4)(H2O)3]n, each ZnII atom adopts a distorted octa­hedral coordination geometry, being surrounded by one chelating and one monodentate 1H-1,2,4-triazole-3,5-dicarboxyl­ate ligand and three water mol­ecules. Adjacent ZnII cations are linked by a 1H-1,2,4-triazole-3,5-dicarboxyl­ate ligand in a μ2,κ3 fashion to form a chain running along the c axis. The crystal packing is stabilized by N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds