Preparation of mesoporous silicon dioxide with high specific surface area

The influence of the reactant ratio on the specific surface area, total pore volume, and mean pore diameter of mesoporous silicon dioxide prepared by the sol-gel method was examined. The optimal reactant ratio for preparing the material with a high specific surface area was determimed.     

Mercury passivation solutions of potassium chloride and sodium hydroxide and hypochlorite

Formation of anodic films on the surface of mercury in solutions of potassium chloride and sodium hydroxide and hypochlorite and the effect of these films on mercury passivation were studied by the potentiostatic method.     

New integer programming formulations and an exact algorithm for the ordered cutting stock problem

Apart from trim loss minimization, there are many other issues concerning cutting processes that arise in real production systems. One of these is related to the number of stacks that need to be opened near the cutting machines. Many researchers have worked in the last years on cutting stock problems with additional constraints on the number of open stacks. In this paper, we address a related problem: the Ordered Cutting Stock Problem (OCSP). In this case, a stack is opened for every new client's order, and it is closed only when all the items of that order are cut. The OSCP has been introduced recently in the literature. Our aim is to provide further insight into this problem. This paper describes three new integer programming formulations for solving it, and an exact algorithm based on column generation, branch-and-bound and cutting planes. We report on computational experiments on a set of random instances. The results show that good lower bounds can be computed quickly, and that optimal solutions can be found in a reasonable amount of time.     

Oscillator strengths and transition energies of diamond

The spectrum of the dielectric constant of three different samples of diamond in the 5–30-eV region is decomposed in thirteen elementary components. The main parameters of components are determined, and their nature is found on the basis of the band model.     

Effective interactions in the periodic Anderson model in the regime of mixed valency with strong correlations

For the periodic Anderson model in the strong correlation regime, we construct the effective Hamiltonian H _eff up to terms of the fourth order in the parameter V/U, where V is the hybridization interaction intensity and U is the intra-atom Coulomb repulsion strength. This Hamiltonian contains interactions inducing both magnetic ordering and Cooper instability under conditions of a mixed valency of rare-earth ions. Based on numerical calculations, we obtain information about the dependences of the effective interaction parameters on the distance between crystal lattice sites. We demonstrate that realizing exchange interactions corresponds to a strongly frustrated system of localized spin moments and facilitates the suppression of the antiferromagnetic order parameter with a possible transition to the state of a quantum spin liquid. It is essential that among the terms in H _eff inducing the transition to the superconductivity phase, there are terms resulting in the d-type symmetry of the superconductivity order parameter; such a symmetry is realized in many heavy-fermion compounds. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 157, No. 2, pp. 235–249, November, 2008.     

1D to 3D NMR study of microporous alumino‐phosphate AlPO4‐40

From one‐ to two‐ and three‐dimensional MAS NMR solid‐state experiments involving ³¹P and ²⁷Al, we show that the structure of microporous alumino‐phosphate AlPO₄‐40 contains at least four times more sites than expected, and we attribute two types of Al_IV sites. The newly described ²⁷Al‐³¹P MQ‐HMQC opens new possibilities of describing details of three‐dimensional bounded networks. Copyright © 2009 John Wiley & Sons, Ltd.     

Higher-Order Relations for Derivatives of Nonlinear Diffusion Semigroups

We show that a special choice of the Cameron–Martin direction in the characterization of the Wiener measure via the formula of integration by parts leads to a set of natural representations for derivatives of nonlinear diffusion semigroups. In particular, we obtain a final solution of the non-Lipschitz singularities in the Malliavin calculus.     

Dielectric Spectra and d-bands Structure of Germanium,Tin, and Lead Tellurides

Russian Physics Journal - The known experimental absorption spectra were used to calculate the dielectric spectra of GeTe, SnTe, and PbTe crystals in the region of electron transitions from the...     

Distribution of Mn2+ Manganese Ions in a Single Crystal of the Lithium–Gallium Li0.5Ga2.5O4 Spinel

Physics of the Solid State - A self-organization of eight structurally and magnetically nonequivalent positions of manganese Mn2+ ions in the unit cell of a single crystal of the...