Short-Term Mixing Structures

AU the heteropolysalts described in the literature have been prepared starting from the heteropolycompound in the acid form, successively exchanged by addition of the suitable alkali metal carbonate. The final materials are therefore characterized by the presence of some fraction of heteropolycompound still in the add form, not salified this constitutes a factor of structural instability. In addition, the add form is known to be detrimental for the selectivity in MAA formation, being responsible for the formation of the by-product propylene. Aim of the present work is to study the short-term catalytic performance in IBA oxydehydrogenation of mixed salts with composition Kx(NH4)3-xPMoi2O40, prepared with a method that allows to directly obtain salified compounds, without intermediate formation of the add. The effect of c ildnation temperature and of composition on the catalytic behavior will be examined. 

Nematic polyurethanes derived from 4,4 -dihydroxybiphenyl and 4,4 -bipiperidine, ethylene-4,4 -bipiperidine, or trimethylene-4,4 -bipiperidine have been reported [254]. 4,4 -Bipiperidine, l,2-bis(4-piperidinyl)ethane, and l,3-bis(4-piperidinyl)pro-pane were condensed with the dichloroformates of p-phenylene, 2-methyl-l,4-phenylene, or 2,5-biphenylylene. Furthermore, two copolyurethanes were prepared either by mixing 4,4 -bipiperidine and l,2-bis(4-piperidinyl)ethane or by mixing the dichloroformates of p-phenylene and 2,5-biphenylene. The polyurethanes derived from hydroquinone or methylhydroquinone were semicrystalline polymers with a short-term thermostability up to 310 °C. The polyurethanes derived from phenyl-hydroquinone were amorphous with a thermostability up to 360 °C. The homo-and co-polyurethanes containing 4,4 -biphenylylene units formed a smectic layer structure in the solid state and a nematic melt above the melting point [254]. 

In general terms, the initial fixed capital investment and the minimum net working capital are covered by a mix of equity and long-term loans and additional net working capital from short- and medium-term loans or from positive net cash flow (equity). Within this structure, various combinations and permutations need to be considered related to cost of finance, financial flexibility, debt service, and taxation. Consideration should also be given to leasing, supplier credits, and other sources of finance. In all cases, a balance has to be struck between equity and debt finance. 

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