Literatur

Analytical and Bioanalytical Chemistry -     

Eine neues Prinzip zur Bestimmung mancher organischer Stoffe in w?ssriger L?sung

Ohne Zusammenfassung     

Connectivity and percolation behaviour of grain boundary networks in three dimensions

Grain boundary networks are subject to crystallographic constraints at both triple junctions (first-order constraints) and quadruple nodes (second-order constraints). First-order constraints are known to influence the connectivity and percolation behaviour in two-dimensional grain boundary networks, and here we extend these considerations to fully three-dimensional microstructures. Defining a quadruple node distribution (QND) to quantify both the composition and isomerism of quadruple nodes, we explore how the QNDs for crystallographically consistent networks differ from that expected in a randomly assembled network. Configurational entropy is used to quantify the relative strength of each type of constraint (i.e., first- and second-order), with first-order triple junction constraints accounting for at least 75% of the non-random correlations in the network. As the dominant effects of constraint are captured by considering the triple junctions alone, a new analytical model is presented which allows the 3-D network connectivity to be estimated from data on 2-D microstructural sections. Finally, we show that the percolation thresholds for 3-D crystallographically consistent networks differ by as much as ±0.07 from those of standard percolation theory.     

Elektroanalytische Bestimmungen und Trennungen

Ohne Zusammenfassung     

Synthesis of zirconium poly-O-amidoximes

Synthesis of zirconium poly-O-amidoximes was affected by using both interfacial and aqueous solution techniques. Reaction is rapid. The yield for the synthesis of analogous titanium product is Cp₂ZrCl₂ > Cp₂TiCl₂ which is consistent with that predicted by the hard-soft acid–base theory.     

Simulation of plasticity in nanocrystalline silicon

Molecular dynamics investigation of plasticity in a model nanocrystalline silicon system demonstrates that inelastic deformation localizes in intergranular regions. The carriers of plasticity in these regions are atomic environments, which can be described as high-density liquid-like amorphous silicon. During fully developed flow, plasticity is confined to system-spanning intergranular zones of easy flow. As an active flow zone rotates out of the plane of maximum resolved shear stress during deformation to large strain, new zones of easy flow are formed. Compatibility of the microstructure is accommodated by processes such as grain rotation and formation of new grains. Nano-scale voids or cracks may form if stress concentrations emerge which cannot be relaxed by a mechanism that simultaneously preserves microstructural compatibility.     

Elektroanalytische Bestimmungen und Trennungen

Ohne Zusammenfassung     

Changing surface hydro- and oleophobicity with resorcinarene multilayers-a simple water/oil proofing process

Resorcinarenes (resorcinol-aldehyde tetramers) of appropriate structures have been shown to change the hydro- and oleophilicities of a variety of surfaces. The phenomenon results from attachment of the rim of the bowl-like molecules to hydrophilic surfaces. Hydrophobic (alkyl) and oleophobic (perfluoro alkyl) "legs" attached to the bowls then determine the immediate surface property. Amounts required to modify surfaces are only between 2 and 10 mg m(-2) treated, and there is evidence of multilayer formation. Penetration of surfaces by a variety of liquids has been studied and cannot easily be understood as a function of density, viscosity, or surface tension.