Hexanes/acetonitrile: a binary solvent system for the efficient monosilylation of symmetric primary and secondary diols

Symmetric diols are useful compounds in the synthesis of natural products, their value often dependent on their successful monoprotection. A general and simple method for the monosilylation of symmetrical primary and secondary diols is reported. The method exploits the solubility differential of diols and their monosilylated counterparts in a binary hexanes/acetonitrile solvent system.     

A General Approach to the Synthesis of Gold–Metal Sulfide Core–Shell and Heterostructures

Cores and effect : Water‐dispersible core–shell structures and heterostructures incorporating gold nanocrystals of different shapes (polyhedra, cubes, and rods) and a variety of transition metal sulfide semiconductors (ZnS, CdS, NiS, Ag₂S, and CuS) are synthesized using cetyltrimethylammonium bromide‐encapsulated gold nanocrystals and metal thiobenzoates as starting materials.

     

Manipulating charge‐transfer character and tuning emission color with electron‐withdrawing main‐group moieties in iridium‐based electrophosphors: a theoretical investigation

A new way has been investigated for tuning the optical and electronic performance of cyclometalated iridium(III) phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2‐phenylpyridine) with various main group moieties in [Ir(ppy‐X)₂(acac)] (X = POPh₂, SO₂Ph, GePh₃, OPh, OPh(CF₃)₃, SOPh). The geometric and electronic structures of the complexes in the ground state are studied with time‐dependent density functional theory (TD‐DFT) and Hartree–Fock method, whereas the lowest singlet and triplet excited states are optimized by the configuration interaction singles method. At the TD‐DFT level, absorptions and phosphorescence properties of the studied molecules were calculated on the basis of the optimized ground‐ and excited‐state geometries, respectively. The various main group moieties produce a remarkable influence on their optoelectronic properties. The calculated data reveal that the studied molecules have improved charge transfer rate and balance and can be used as hole and electron transport materials in organic light‐emitting devices. In particular, the work can provide valuable insight toward future design of new and relatively rare luminescent materials with enhanced electron‐injection and electron‐transporting features. Copyright © 2012 John Wiley & Sons, Ltd.     

Dynamically consistent collaborative environmental management with production technique choices

Adoption of environment-preserving production technique plays a key role to effectively solving the continual worsening global industrial pollution problem. Due to the global nature of environmental effects and trade, unilateral response on the part of one nation is often ineffective. Cooperation in environmental management holds out the best promise of effective action. For cooperation over time to be credible, a dynamic consistency condition which requires the agreed-upon optimality principle to remain in effect throughout the collaboration duration has to hold. In this paper, we present a cooperative dynamic game of collaborative environmental management with production technique choices. A dynamically consistent cooperative scheme is derived. It is the first time that dynamically consistent solution is obtained for dynamic games in collaborative environmental management with production technique choices. The analysis widens the scope of study in global environmental management.     

Diliberto–Straus algorithm for the uniform approximation by a sum of two algebras

In 1951, Diliberto and Straus [5] proposed a levelling algorithm for the uniform approximation of a bivariate function, defined on a rectangle with sides parallel to the coordinate axes, by sums of univariate functions. In the current paper, we consider the problem of approximation of a continuous function defined on a compact Hausdorff space by a sum of two closed algebras containing constants. Under reasonable assumptions, we show the convergence of the Diliberto–Straus algorithm. For the approximation by sums of univariate functions, it follows that Diliberto–Straus’s original result holds for a large class of compact convex sets.     

Optimization for pattern classification using biased random search techniques

We demonstrate how optimization problems arise in the field of pattern classification, in particular in using piecewise-linear classification and classification based on an optimal linear separator. We motivate the need in this area for a general purpose optimization approach. We discuss ALOPEX, a biased random search approach, from the point of view of this need. While ALOPEX itself failed to fulfil our need, a newly-introduced generalization of it (iterated ALOPEX) was found to be appropriate for the optimization problems of our particular concern. We conclude the paper with a brief critical evaluation of this approach as compared to our original aims.     

Kaluza-Klein black hole in a six-dimensional Poincaré gauge theory of gravitation

We found a solution to the six-dimensional Poincaré gauge theory which can be interpreted as the exterior gravitational field of an uncharged black hole in the four-dimensional spacetime. The extra dimensions are curled up into a compact space of the size characterized by the Planck length.     

Kaluza-Klein unification in the poincaré gauge theory of gravitation

We show that we can unify the gravitational and internal gauge interactions in a high dimensional Riemann-Cartan spacetime in the spirit of Kaluza-Klein, if we identify some of the connection coefficients as Yang-Mills potentials and if the dynamics of the spacetime is governed by the Poincaré gauge theory of gravitation whose lagrangian contains curvature and torsion squared.