The use of GRID in the 3-D QSAR analysis of a series of calcium-channel agonists is described. Partial least-squares analysis of GRID maps showing the interaction energy between an alkyl hydroxyl probe and a series of agonists in 3-D space generated a predictive quantitative model of the variation of biological activity. The macroscopic descriptors CLOGP and CMR were included in the analysis, and the importance of appropriate block scaling is highlighted. The discussion highlights the interpretation of the resulting regression maps, and the steric, electrostatic, lipophilic, and hydrogen-bonding preferences of the calcium-channel receptor are identified.

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Resonant x-ray diffraction revealing chemical disorder in sputtered L10 FeNi on Si(0 0 1). Physics: Condensed Matter, 28(40) Abstract. In the search for new rare earth free permanent magnetic materials, FeNi with the L1 0 structure is a possible candidate. We have synthesized the phase in thin film form by sputtering onto HF-etched Si(001) substrates. Monatomic layers of Fe and Ni were alternately deposited on a Cu buffer layer, all of which grew epitaxially on the Si substrates. A good crystal structure and epitaxial relationship was confirmed by in-house X-ray diffraction (XRD). The chemical order, which to some part is the origin of an uniaxial magnetic anisotropy, was measured by resonant XRD. The 001 superlattice reflection was split in two symmetrically spaced peaks due to a composition modulation of the Fe and Ni layers. Furthermore the influence of roughness induced chemical anti-phase domains on the RXRD pattern is exemplified. A smaller than expected magnetic uniaxial anisotropy energy was obtained, which is partly due to the composition modulations, but the major reason is concluded to be the Cu buffer surface roughness. Journal of

Thermodynamic stability as well as structural, electronic, and elastic properties of boron-deficient AlB$_{2}$-type tantalum diborides, which is designated as $\alpha$$-$TaB$_{2-x}$, due to the presence of vacancies at its boron sublattice are studied $via$ first-principles calculations. The results reveal that $\alpha$$-$TaB$_{2-x}$, where 0.167 $\lesssim$ $x$ $\lesssim$ 0.25, is thermodynamically stable even at absolute zero. On the other hand, the shear and Young's moduli as well as the hardness of stable $\alpha$$-$TaB$_{2-x}$ are predicted to be superior as compared to those of $\alpha$$-$TaB$_{2}$. The changes in the relative stability and also the elastic properties of $\alpha$$-$TaB$_{2-x}$ with respect to those of $\alpha$$-$TaB$_{2}$ can be explained by the competitive effect between the decrease in the number of electrons filling in the antibonding states of $\alpha$$-$TaB$_{2}$ and the increase in the number of broken bonds around the vacancies, both induced by the increase in the concentration of boron vacancies. A good agreement between our calculated lattice parameters, elastic moduli and hardness of $\alpha$$-$TaB$_{2-x}$ and the experimentally measured data of as-synthesized AlB$_{2}$-type tantalum diborides with the claimed composition of TaB$_{\thicksim2}$, available in the literature, suggests that, instead of being a line compound with a stoichiometric composition of TaB$_{2}$, AlB$_{2}$-type tantalum diboride is readily boron-deficient, and its stable composition in equilibrium may be ranging at least from TaB$_{\thicksim1.833}$ to TaB$_{\thicksim1.75}$. Furthermore, the substitution of vacancies for boron atoms in $\alpha$$-$TaB$_{2}$ is responsible for destabilization of WB$_{2}$-type tantalum diboride and orthorhombic Ta$_{2}$B$_{3}$, predicted in the previous theoretical studies to be thermodynamically stable in the Ta$-$B system, and it thus enables the interpretation of why the two compounds have never been realized in actual experiments.

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