Some wave-propagation experiments in plasteline-clay rods

Compressional stress pulses have been propagated in plasteline-clay rods by detonating small charges of lead azide at one end. A capacitance gage at the other end was used to measure particle displacement associated with the pulses and the particle velocity was obtained by differentiation. The shapes and amplitudes of the pulses were determined in separate experiments using composite clay-steel rods where the steel acted, in effect, as a pressure transducer. The techniques employed permitted comparatively accurate determination of some aspects of the dynamic behavior of clay. On the basis of preliminary results, the behavior of clay has been compared to that of a linear viscoelastic solid with the tentative goal of studying the validity of a viscoelastic constitutive model.     

Analysis of the possibility of the spin-orbit origin of surface state splitting in thin Mg(0001) layers on W(110) and Mo(110)

A set of magnesium films ranging in thickness from submonolayer to a few tens of atomic layers grown on single-crystal W(110) has revealed film-thickness dependent splitting of states localized energywise close to the magnesium surface state. Literature refers to several models describing the origin of this splitting; in one case, it is treated as substrate-induced spin-orbit splitting, and in another, as due to formation of nondegenerate pairs of even and odd surface states penetrating deep into the film bulk. The proposed models draw upon studies of films more than five monolayers thick. A comparative investigation of the Mg/W(110) and Mg/Mo(110) systems has been carried out for magnesium films of different, starting from submonolayer, thicknesses, which did not substantiate the spin-orbit origin of this splitting and suggests instead formation on the substrate-film interface of hybridized states, with their variation with thickness being assigned to variation in the contribution due to the magnesium surface states. Original Russian Text ? A.M. Shikin, D.E. Marchenko, N.A. Vinogradov, G.V. Prudnikova, A.G. Rybkin, V.K. Adamchuk, O. Rader, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 3, pp. 572–583.     

Optimal cell flipping to minimize channel density in VLSI design and pseudo-Boolean optimization

Cell flipping in VLSI design is an operation in which some of the cells are replaced with their “mirror images” with respect to a vertical axis, while keeping them in the same slot. After the placement of all the cells, one can apply cell flipping in order to further decrease the total area, approximating this objective by minimizing total wire length, channel width, etc. However, finding an optimal set of cells to be flipped is usually a difficult problem. In this paper we show that cell flipping can be efficiently applied to minimize channel density in the standard cell technology. We show that an optimal flipping pattern can be found in O(p(n/c)^c) time, where n, p and c denote the number of nets, pins and channels, respectively. Moreover, in the one channel case (i.e. when c = 1) the cell flipping problem can be solved in O(p log n) time. For the multi-channel case we present both an exact enumeration scheme and a mixed-integer program that generates an approximate solution very quickly. We present computational results on examples up to 139 channels and 65000 cells.     

Extension of AOAC official method 999.14 (choline in infant formula and milk) to the determination of choline in dietary supplements

AOAC Official Method 999.14 is applicable for the determination of choline in milk and infant formulas. To date, its use has not been extended beyond these matrixes. We modified Official Method 999.14 and applied it to the determination of choline in a range of choline-containing dietary supplements. Dietary supplement tablets, capsules, wafers, softgels, liquid products, and drink powders were included. We found that the standard curve could be extended to cover a wider range of choline concentrations and defined a procedure for the use of Norit for samples in which the vitamin C content was high enough to interfere with the analysis. Recoveries of choline added to infant formula powders and to representative dietary supplement tablets, capsules, powdered drink mix, and wafer products were 85-114%. The use of Norit during the procedure did not affect the recovery of choline added to infant formula powders or to dietary supplements. An alkaline digestion was included for use with a product containing lecithin as the sole source of choline. Ten of 11 dietary supplement products analyzed by the modified method contained amounts of choline at or above declarations found on the product labels. The remaining product contained about 40% of the label-declared amount of choline.