Total hemispherical emissivity of oxidized Inconel 718 in the temperature range 300–1000°C

Total hemispherical emissivities were measured for Inconel 718 as a function of sample temperature. Measurements were made for both unoxidized and oxidized samples. The oxidation temperatures were 1000°C, 1100°C and 1142°C and the oxidation times were 15, 30 and 60 min, respectively. The oxidized samples showed a significant increase in emissivity over the unoxidized one which was in an as-received condition. No apparent pattern was observed in the change of emissivity as a function of oxidation time at a given oxidation temperature. In some cases, emissivity measurements made with increasing temperature were greater than those made with descending temperature. One possible explanation for this is the spalling of the oxide layer as the sample area contracted with descending sample temperature.     

Deuterium hyperfine structure in interstellar C3HD

The deuterium nuclear quadrupole hyperfine structure of the transition 1(10)-1(01) of the ring molecule cyclopropenylidene-d1 (C3HD) has been observed in emission from interstellar molecular clouds. The narrowest linewidths (approximately 7 kHz) so far observed are in the cloud L1498. The derived D coupling constants Xzz = 186.9(1.4) kHz, eta=0.063(18) agree well with correlations based on other molecules.     

A study of liquid 3He in the Brueckner-Goldstone formalism

The two- and three-body correlation energies in liquid ³He are calculated within the framework of Brueckner-Goldstone theory. Various approximations taken from nuclear matter calculations and used in previous liquid helium studies are examined and improved upon.The dependence of the g-matrix elements on the center of mass momentum of the interacting particles and the question of the self-consistency of the hole spectrum are treated more systematically and extensively than before.The contribution to the three-body energy of relative partial wave interactions with nonzero relative angular momentum is studied in some detail for the first time.     

The alpha - cluster ground state of O

It is shown that there is an α-cluster configuration which is more bound than the optimum regular tetrahedron which is usually assumed to correspond to the ground state of ¹⁸O. There is no sharp minimum in the energy of the ground state of ¹⁶O in the α-cluster model suggesting that the ground state must be a mixture of α-clusters, or that it is important to treat the cluster co-ordinates as dynamical variables.     

Dielectric relaxation in styrene-related polymers at low temperatures

The complex dielectric constants ?^* = ?′ ? j?″ of each of several members of a system of copolymers of 4-chlorostyrene and 4-methylstyrene have been measured from 1.6°K to 300°K and from 0.1 kHz to 20 kHz. The principal experimental findings are: the strength of the relaxation process which occurs near 50°K at 1 kHz varies linearly with changing copolymer composition; both the apparent activation energy (H = 2.7 ± 0.7 kcal/mole) and the shape of the relaxation curve are independent of the composition variable and of the temperature (or frequency) within the ranges studied; and the ratio of the relaxation strength of poly-4-methylstyrene to that of poly-4-chlorostyrene in the 50°K process is about 25 times the corresponding ratio for the primary relaxation process that occurs in the neighborhood of the glass-transition temperature. These findings suggest that in the 50°K process the phenyl groups relax independently of one another; that the apparent activation energy and the shape of the relaxation spectrum are determined primarily by the nature of the intrachain forces; and that the strength of the relaxation process depends primarily on effects of intermolecular forces that are governed by the molar “free volume” of the copolymers.