Thermodynamics of solid solutions with ordering tendencies

This paper describes a new procedure for the calculation of phase diagrams for quasibinary systems that show ordering phenomena near special stoichiometric compositions. The diagrams are calculated from excess Gibbs energy functions that are modulated in the solid state at the specified stoichiometric compositions by distribution functions of the Gauss type. These ‘Gaussian’ terms consider the contribution of the composition and temperature depending ordering energy to the excess Gibbs energy of the solid solution.

As the solid state is described in this way by a single continuous Gibbs function, the thermodynamic factor for interdiffusion in such quasibinary systems can also be derived as a single continuous function yielding negative values inside the miscibility gaps of the phase diagram.     

New gold and silver-gold catalysts in the shape of sponges and sieves

Gold with a nanoporous sponge-like morphology, generated by leaching of AuAg alloys is presented as a new unsupported material system for catalytic applications. The role of residual silver for catalytic activity towards CO oxidation in the temperature range from −20 to 50°C has been investigated by comparison with Au and Au/Ag zeolite catalysts. As revealed by a systematic variation of the silver content in the zeolite catalysts, bimetallic systems exhibit a significantly higher activity than pure gold, probably due to activation/dissociation of molecular oxygen by silver. By STEM tomography we can unambiguously prove that at least some of the particles form inside the zeolite lattice.     

Correlation between Thermal Expansion and Magnetic Characteristics of Fe-Ni Alloys in Fe_(1-x)Ni_x/Cu Superlattices

Thermal expansion behaviors of FeNi alloys were investigated by means of X-ray diffraction technique within a Fe1 -xNix/Cu superiattice structure. It was found that with a Ni concentration of x = 0.35, FeNi alloy layers showed the well-known Invar behavior, but for alloy layers with either lower or higher Ni concentrations, thermal expansion coefficients were larger. Based on results of magnetic measurements it is concluded that FeNi alloy layers with Ni concentrations lower than the Invar composition are in a superparamagnetic state which leads not only to low spontaneous magnetizations but also to large thermal expansions of the alloy layers.     

Bridging Artifacts and Actors: Expertise Sharing in Organizational Ecosystems

We synthesize findings from longitudinal case studies examining work practices in three different organizations and propose analytical and methodological frameworks to guide the design and implementation of technologies for expertise and knowledge management. We appropriate the concept of ecosystem to argue that we can create active and useful solutions for knowledge management through a focus on interaction between two mutually intertwined elements of an ecosystem—artifacts and actors. We show that in expertise and knowledge sharing systems domain knowledge and technological knowledge are complementary and we present evidence that small solutions can have far reaching effects. Finally, we make a case for full integration of IT developers as an element of expertise sharing ecosystem.     

Design and incorporation of reactive diluents for air-drying high solids alkyd paints

The development of air-drying solvent borne trade paints with solvent content below that of current solids levels will necessitate reformulation using reactive diluents. The current lack of suitable reactive diluents for air-drying systems has prompted this investigation. This paper highlights some emerging aspects of the design of reactive diluents, in particular the importance of inclusion of the correct balance of sites for both initiation and coupling reaction stages into an alkyd system together with the concept of functionality as a tool to predict performance. Also reported is a new class of reactive diluents based on fumarates and succinates of octadienol (referred to as the OFS class of reactive diluents). A detailed study on the cure and performance of this class of compounds is reported. A combination of conventional and refined analytical techniques have given new insights into the mechanism of cure of these reactive diluents as well as a measurement of incorporation into the drying paint film. The findings of this performance study have confirmed the suitability of the reactive diluent design and allowed its further refinement. OFS reactive diluents have thus been found to achieve full chemical incorporation whilst maintaining high performance of the paint.     

Kinetics and regioselectivity of the Autoxidation of o-Substituted Isopropyl Aromatics

The relative chain propagation constants and the regioselectivities of the oxidations of o-cymene and 2-isopropyl-1,4-dimethylbenzene were determined by competitive oxidations of the hydrocarbons with cumene. As expected, the reactivity of the tertiary C H bond of the isopropyl group is considerably decreased by o-methyl groups. Also in α-isopropylnaphthalene a considerable decrease in the reactivity of the tertiary C H bond takes place. The decrease of the chain propagation constants effects a decrease of the oxidabilities of o-substituted isopropyl aromatics. In the case of the methyl isopropyl benzenes the increase of the chain termination constants by primary peroxy radicals must also be taken into consideration. This results in a decrease of the oxidabilities which can be observed even in p-cymene (in comparison with cumene).