Conformation of the methyl group and tetrahydropyridine ring in N-acyltetrahydroquinaldine derivatives

NMR spectra of N-acyletrahydro quinaldines 12–19 and of pyridodibenzoxazepines 21–24 show the Me group to be axially oriented with the tetrahydropyridine ring in a half-boat conformation. The aroyl phenyl in both is twisted out of the CO plane. While the Me group again occupies the axial position in pyridophenanthridones 5 and 7 and pyridooxazinones 8 and 9, the tetrahydropyridine ring exists as a half-chair.     

Shrinkages of the internuclear distances in some hexafluorides of octahedral symmetry

A brief analysis of the shrinkages or shortening of the internuclear distances in many molecular systems has been made. Analytical expressions for the linear shrinkage and nonlinear shrinkage have been derived in terms of the meansquare perpendicular amplitudes. Analytical expressions for the generalized mean-square amplitudes (mean-square parallel amplitudes, mean-square perpendicular amplitudes, and mean cross products) for an octahedralXY ₆ molecule have been given in terms of the mean-square amplitude matrices. The linear and nonlinear shrinkages for the hexafluorides of sulfur, selenium, tellurium, molybdenum, technetium, ruthenium, rhodium, tungsten, rhenium, osmium, iridium, platinum, uranium, neptunium, and plutonium have been computed at 298°K and 500°K, and the results have been briefly discussed.This paper is based on a thesis to be submitted byThomas S. Adams to the Graduate School of the Valdosta State College in partial fulfillment of the requirements for the degree of Master of Science.     

A study of the PE–PTFE system. II. ESCA measurements

Samples of polyethylene and polytetrafluorethylene were sintered at 200°C. The samples were cleaved and cut, and the two types of surfaces were studied by ESCA. The possibility of chemical interaction between the two polymers and the formation of a transitional layer is postulated on the basis of the results. A morphological model of the structure of these samples is given.     

A finite element approach to the design and dynamic analysis of platform type robot manipulators

The design of a closed-loop platform-type robot manipulator using the finite element method is presented. The present approach aims at the optimization of the manipulator geometry and prediction ot the actuator parameters. Beam elements and triangular plate elements are used for the finite element model. Manipulators having six spherical-prismatic-spherical (6 SPS) pairs and of tetrahedron construction have been compared for their dynamic performance.     

Mittlere Schwingungsamplituden,thermodynamische Funktionen und molekulare Polarisierbarkeiten von gemischten Phosphorhalogeniden des Typs PX2Y

Zusammenfassung Es werden verschiedene molekulare Konstanten der Phosphorverbindungen PF₂Cl, PCl₂F, PF₂Br, PBr₂F, PCl₂Br und PBr₂Cl berechnet. Mit Hilfe der Methode vonCyvin werden mittlere Schwingungsamplituden für Zimmertemperatur ermittelt. Die mittleren Amplituden des P–F-, P–Cl- und P–Br-Abstandes nehmen mit zunehmender Gruppenelektronegativität der Halogenatome 1/3X _i ab. Weiterhin werden thermodynamische Funktionen sowie molekulare Polarisierbarkeiten nach der Methode vonLippincott undStutman berechnet.     

Hydroxamic acids and their derivatives—III Preparation of esters of pivalohydroxamic acid and their use in peptide synthesis

Reaction of N-protected amino acids with pivalonitrile oxide affords “active esters” which are useful in peptide syntheses.     

Thermodtnamics of surfactant-polymer interactions in dilute aqueous solutions

A thermodynamic model for suffactant binding to polymers in dilute aqueous solution is present. It assumes that the inter- molecular contacts between the polar and the non-polar polymer segment resemble the macroscopic hydrocarbon-water interface ,where preferential accumulation of surfactant accurs. The model also considers the competitive surfactant micelization.