Alkyl ketoximes as analytical reagents. IX

Summary A method is outlined for the determination of trace amounts of palladium in a standard nickel-copper reference matte using the 4-heptanone oxime extraction procedure. The average result of 0.259 oz/ton agrees favourably with the recommended value of 0.24 oz/ton.

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Zusammenfassung Ein Verfahren zur Bestimmung von Palladiumspuren in einer standardisierten Nickel-Kupfer-Bezugsprobe mit Hilfe der Extraktion mit 4-Heptanonoxim wurde angegeben. Das durchschnittliche Ergebnis von 0,259 Unzen/Tonne stimmt mit dem statistisch ermittelten Wert von 0,24 Unzen/Tonne sehr gut überein.

     

Linear polyethylene in a glassy phase: The value of the glass-transition temperature

Raman spectroscopy, x-ray diffraction, and thermal analysis are used to investigate the structure of linear high-density polyethylene rapidly quenched from the melt to cryogenic temperatures. All the results point to the production of a glassy phase which crystallizes when heated above 170 K.     

Studies in peroxidase action—XXII : Peroxidase as a transalkylating agent

The oxidations of 2,3,4-trimethylaniline, 4-isopropyl-2,6-dimethylaniline, 4-t-butyl-2,6- dimethylaniline and 4-cyclohexyl-2,6-dimethylaniline by peroxidase have been studied in detail. In three instances alkyl group migrations are involved and a mechanism is proposed.     

The Dirac equation in the de Broglie-Bohm theory of motion

We discuss the application of the de Broglie-Bohm theory of relativistic spin-1/2 particles to the Klein paradox andzitterbewegung.     

Characterisation of sol-gel prepared (HfO2)x(SiO2)1-x (x=0.1, 0.2 and 0.4) by 1H, 13C, 17 O and 29Si MAS NMR, FTIR and TGA

The HfO2-SiO2 system is attracting interest as a possible new dielectric material in semiconductor devices. Knowledge of the location of hafnium within the silica network and the effect hafnium has on the structure will be central to the successful use of this material system in this application. Here, sol-gel techniques have been used to manufacture (HfO2)x(SiO2)1-x samples (x=0.1, 0.2 and 0.4, each heat treated at 250, 500 and 750 degrees C) and these have been characterised by magic angle spinning (MAS) NMR (1H, 13C, 17 O, 29Si), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis. 29Si MAS NMR showed that increasing the hafnia content decreases the connectivity of the silicate network, i.e. increases the range of differently connected SiO4 (Qn) units with more having increased numbers of non-bridging oxygens (i.e. lower n). FTIR and 17 O MAS NMR showed unequivocally that the x=0.4 sample phase-separated at higher temperatures, while in the x=0.1 sample the hafnium was homogeneously mixed into the SiO2 phase without any phase separation.     

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