n-Hexane dehydrocyclization over Pt?Ni supported on alumina catalysts

Pt–Ni/-Al₂O₃ catalysts have been prepared and studied in n-hexane dehydrocyclization. The selectivity for benzene and toluene, a chain lengthening product formation was improved by Ni and correlated with its content.

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Pt–Ni/-Al₂O₃ -. Ni . Ni , .

     

Reactivity of aromatic nitrons with alkyl and alkylperoxyl radicals

The catalytic properties of Mn(II)-histidine complexes for the oxidation of indigo carmine by H₂O₂ have been studied. It has been shown that the complex Mn(II) (Histidine)₂ existing in as a dimer is the true catalyst but at high concentration of the reactant the reaction is inhibited because of complex formation between the reactant and the catalyst.

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Mn(II)- . , Mn(II)·()₂ . , .

     

Enhancement of conductivity by diameter control of polyimide-based electrospun carbon nanofibers

Oxydianiline-pyromellitic dianhydride poly(amic acid) (ODA-PMDA PAA) was polymerized with a catalyst support of triethyl amine for controlling molecular weight. This polymer was used for electrospinning in the preparation of PAA nanofibers, a precursor of carbon nanofibers. Here the amount of catalyst and concentration of PAA solution were optimized to produce polyimide-based carbon nanofibers approximately 80 nm in diameter. The effects of molecular weight of PAA, bias voltage, and spinning rate on the morphology of electrospun PAA and polyimide nanofibers have been evaluated. We showed that the conductivity of the carbon nanofiber mat decreased with increasing nanofiber diameter, where the conductivity of polyimide-based carbon nanofiber mat was much higher than those of other types of carbon nanofiber mat. The key ingredient to increase conductivity in a carbon nanofiber mat was found to be the number of cross junctions between nanofibers.     

On equivalence of the Gauss-Newton technique,the parameter influence coefficient technique,and the quasilinearization technique in dynamic system identification by least squares

The literature presents, among others, three general techniques for system identification by least squares. These techniques are the Gauss-Newton technique, the parameter influence technique and the quasilinearization technique. The purpose of this paper is to show the equivalence of all three techniques for the general case.