Thermodynamic investigation of CuSn alloys with solid state galvanic cells

An experimental apparatus for the measurement of the EMF of galvanic cells with solid state electrolytes and with separate gas chambers around the electrolytes is described. This provides the possibility of a more precise determination of the thermodynamic values for solid alloys. Measurements on alloys from the copper-rich solid solution region of the CuSn system resulted in a linear temperature dependence of the measured EMF values with very little scatter. The partial free energies of mixing and the integral mixing enthalpies obtained using the published value of Petot-Ervas [10] for the formation enthalpy difference of the oxides NiO and SnO₂ agree well with the literature data, which were determined by other methods.     

Optical properties and delocalization of excess negative charges on oligo(phenylenevinylene)s: a quantum chemical study

A quantum chemical study of the electronic structure of negatively charged phenylenevinylene (PV) oligomers and methoxy-substituted derivatives is presented. The geometries of the PV oligomers were optimized using density functional theory. The geometry deformations are found to be delocalized along the entire oligomer chain without indication of polaron formation. The optical absorption spectra of the negatively charged PVs were calculated using both time-dependent density functional theory (TDDFT) and the singly excited configuration interaction method with an intermediate neglect of differential overlap reference wave function (INDO/s-CIS). The available experimental optical absorption energies are reproduced by the calculations. Introduction of methoxy substituents reduces the transition energies, while this does not have a strong effect on the charge distribution along the chain. DFT calculations yield a more delocalized excess negative charge than that of INDO/s-CIS calculations.     

D-lattices

Difference lattices (D-lattices), which generalize Boolean algebras, orthomodular lattices as well as MV algebras, are studied.     

Hydrolytically stable linkers for silicone carbohydrates derived from hydrodiisopropylsilanes

Two strategies were developed for the attachment of sugars to siloxanes using bifunctional silicon linkers: the substrate could be functionalized with a silyl hydride before coupling to a vinyl-terminated siloxane through platinum catalyzed hydrosilylation; alternatively, unprotected glucose could be directly silylated by a silicone terminated with a chlorosilyl group. Optimal steric bulk was found with difunctional diisopropylsilanes, which exhibit excellent reactivity for preparation of sugarsilane derivatives, and also permit efficient grafting to silicones via hydrosilylation. The resulting product alkoxysilane-silicone exhibits greater stability to hydrolysis than the silicone itself.