Ohkuma Structures

The construction and characterization by T. Ohkuma of a chain whose automorphism group acts uniquely transitively is extended in this article to analogues for circularly ordered sets and betweenness chains.     

Polysiloxane Interpenetrating Network Materials as Electronic Device Encapsulants: Synthesis and Properties

Thermally curable interpenetrating networks employing short and long chain components were successfully prepared via the sol-gel route. Their mechanical properties were assessed and correlated to their composition and structure. The role of the organic cross-links was found to be a larger determinant of the mechanical properties than the inorganic network. Their low frequency dielectric properties were investigated and found to be comparable to those of conventional encapsulation materials. Observed mass losses at 523 K ranged between 3–5% after 1000 minutes, the suspected mechanism being the development of organic cross-links.     

Predicting transport properties without adjustable parameters: A test application of the Hulburt-Hirschfelder potential to argon

Accurate estimates of the transport properties of gaseous systems under conditions where experimental transport data are sparse of unavailable are important in a number of applications. The Hulburt-Hirschfelder (HH) potential for monatomic gas interactions, which is determined entirely by spectroscopic constants of diatomic molecules, provides a basis for calculating transport properties without adjustable parameters. In this paper we report test calculations of the viscosity, thermal conductivity and self-diffusion coefficients for argon. Comparison with the comprehensive correlation of thermophysical properties for argon by Kestin and co-workers shows very reasonable agreement for the transport properties at moderate and high temperatures. Deviations at lower temperatures may be attributed to inaccuracies in the long-range part of the HH potential, whereas the core and well of the potential appear to be adequately represented. These results strongly support the use of the HH potential for estimating the transport properties of monatomic gases at high t     

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.     

Local ionic motion in the superionic conductor Li3N

Anisotropic dielectric behavior of the superionic conductor lithium nitride (Li₃N) is reported for low temperature where the dc ionic conductivity can be neglected (T<17oK). For E ⊥ c the static dielectric constant followed a Langevin-Debye (ε ∝ 1/T) type law from 170 to 80K which changed to a temperature independent value below 40K. Debye relaxations were measured between 10 and 50K in the frequency range 10Hz to 1MHz. The observed properties are discussed in terms of a locally restricted ionic motion in shallow potentials. Different types of potentials are considered and an overdamped oscillator model is proposed.