Preconditioning, structural optimization

T. Randen, L. Spimeland, A. Carrillat, T.S. Valen, T. Skov, S.I. Pedersen, B. Rafaelsen, and G. Elvebakk (2003) Preconditioning for optimal 3d strati-graphical and structural inversion. Extended Abstr., Eur. Assoc. Expl. Geophys. 

B. Rafaelsen, and G. ElvebaJsk (2003) Preconditioning for optimal 3D strati-graphical and structural inversion. Proc. 65th EAGE Conference Exhibition. 

A precondition for the optimization of a package having a specified minimum shelf life date for a food with a known oxygen and/or water sensitivity is the calculation of the permeability of laminate structures. The total permeability Qv of a laminate film made from n different plastic layers with thicknesses d, and having permeability coefficients of Pj can be calculated using the following formula ... 

The structure and yield of the propylene dimerization products have been studied as functions of the catalyst composition and solvent [603]. The highest yield is obtained in toluene with a relative molar composition of Nifacac) -AlEt3-PPh3-BF3-OEt2 at 2 1 4 3.5. This corresponds to a B/Ni molar ratio of 15. At a B/Ni molar ratio <5 the system is catalytically inactive. When BF3-OEt2 is preconditioned in anhydrous toluene for a few days, the optimal ratio decreases. At the optimum catalyst composition the yield is the highest in toluene, then in benzene, and much lower in chlorobenzene, yet the relative distribution of products in toluene and chlorobenzene is closer than that in benzene. The Bronsted acids activate the catalyst containing nickel(O). 

Electrochemical energy conversion for technical applications relies on a high catalytic reactivity. The electro catalytic reactivity is strongly influenced by the structure and composition of the surface of the catalysts. In PEMFC the catalysts consist of Pt or Pt alloys, which are of nanometer size and often supported on carbon in order to optimize the surface area and the costs of the noble metals. However, the important relation between the reactivity and the structure is obscured in technical electro catalysts by a variety of parameters, like, e.g. the properties of the carbon support, the preconditioning of the catalyst, and the structure of the interface between the electrolyte and the active layer (e.g. the Nafion content). An excellent review on the PEM fuel cell electrodes is given by Litster and McLean (2004)... 

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