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Valence proton-neutron interaction strengths from double binding energy differences

Description: Empirical p-n interaction strengths have been extracted from experimental mass data using double-difference binding energy equations. The especially strong interactions for self-conjugate nuclei will be discussed as well as microstructure found for deformed and in doubly magic regions. Valence correlation Schemes provide a basis to comment on the stability of medium mass near-drip-line nuclei and superheavy elements.
Date: 1996-10~
Creator: Brenner, D. S.; Foy, B. D.; Warner, D. D.; Zamfir, N. V. & Casten, R. F.
Partner: UNT Libraries Government Documents Department

Effective interactions, elementary excitations, and transport in the helium liquids

Description: Polarization potentials, the self-consistent fields which describe the primary consequences of the strong atom-atom interaction in the helium liquids, are developed for liquid /sup 4/He and /sup 3/He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero point motion, and the Pauli principle) which determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon-maxon-roton spectra of /sup 4/He and /sup 3/He-/sup 4/He mixtures, the phonon-maxon spectrum of normal and spin-polarized /sup 3/He, and the transport properties of superfluid /sup 4/He and of normal and spin-polarized /sup 3/He.
Date: January 1, 1986
Creator: Pines, D.
Partner: UNT Libraries Government Documents Department

FY99 Status Report on the HSV

Description: 'The HSV in storage in MTF has been monitored during FY99, and its overpressure has been sampled and analyzed. The HSV''s internal pressure continues to rise slowly, and the overpressure still analyzes as 100 percent 3He. The titanium tritide sample that was to be monitored annually and which had developed a leak last year has been repaired and isotherms measured. Unfortunately the sample was showing significant unexpected 3He release, so the isotherm data is corrupted by unknown levels of 3He. This release has disqualified this sample for future use, as it is now seriously divergent from the HSV material. A different sample must be selected for subsequent studies.The unexpected 3He releases of the Ti-3 sample and the possible release in other Ti samples have raised a serious issue. It should be determined why this release is occurring, so that an unexpected release of 3He during HSV unloading can be assessed as unlikely.'
Date: October 15, 1999
Creator: Shanahan, K. L.
Partner: UNT Libraries Government Documents Department

FY99 Status Report on the HSV

Description: 'The HSV in storage in MTF has been monitored during FY99, and its overpressure has been sampled and analyzed. The HSV''s internal pressure continues to rise slowly, and the overpressure still analyzes as 100 percent 3He. The titanium tritide sample that was to be monitored annually and which had developed a leak last year has been repaired and isotherms measured. Unfortunately the sample was showing significant unexpected 3He release, so the isotherm data is corrupted by unknown levels of 3He. This release has disqualified this sample for future use, as it is now seriously divergent from the HSV material. A different sample must be selected for subsequent studies.The unexpected 3He releases of the Ti-3 sample and the possible release in other Ti samples have raised a serious issue. It should be determined why this release is occurring, so that an unexpected release of 3He during HSV unloading can be assessed as unlikely.'
Date: October 15, 1999
Creator: Shanahan, K.L.
Partner: UNT Libraries Government Documents Department

Vibrational soliton: an experimental overview

Description: To date the most convincing evidence of vibrational solitons in biopolymers has been found in two very disparate systems: Davydov-like excitations in hydrogen-bonded linear chains (acetanilide and N-methylacetamide) which are not biopolymers but plausible structural paradigms for biopolymers, and longitudinal accoustic modes of possibly nonlinear character in biologically viable DNA. 17 refs., 4 figs.
Date: March 8, 1986
Creator: Bigio, I.J.
Partner: UNT Libraries Government Documents Department

Sound propagation in normal and superfluid /sup 3/He

Description: Liquid /sup 3/He, despite the rather simple nature of its interatomic force, displays striking properties at ultralow temperatures. Below about 2 x 10/sup -3/ K it behaves as a superfluid whose properties are related to, but are much more varied and complex than, those of superconducting electrons in metals. Ultrasonic waves prove to be a powerful probe of this system; here the acoustic properties of both the normal and superfluid phases of this liquid are briefly reviewed.
Date: January 1, 1977
Creator: Ketterson, J.B. & Roach, P.R.
Partner: UNT Libraries Government Documents Department

Theory of Moessbauer line broadening due to diffusion

Description: We have calculated the line broadening of the Moessbauer line due to diffusion of Moessbauer atoms via single vacanices. We take into account the perturbation of vacancy jumps in the neighbourhood of an impurity Moessbauer atom (e.g. Fe in Al) using the 5-frequency model. The anisotropy of the line width is given by the Fourier transform of the final distribution of a Moessbauer atom after an encounter with a vacancy. This distribution is calculated by Monte Carlo computer simulation. 3 figures, 1 tables.
Date: December 1, 1981
Creator: Schroeder, K.; Wolf, D. & Dederichs, P.H.
Partner: UNT Libraries Government Documents Department

New data on the heat capacity of liquid /sup 3/He

Description: Recent heat capacity measurements on liquid /sup 3/He by Haavasoja have shown much smaller values than previous measurements by Wheatley. We have measured P/sub v/(T) from which we can derive values for par. deltaC/sub v/par. delta v. A comparison with values of par. deltaC/sub v//par. delta v obtained from the actual heat capacity measurements shows agreement between our data and those from the heat capacities of Wheatley but disagreement with those from the heat capacities of Haavasoja. This suggests that the large discrepancy between the two sets of heat capacities originates with a problem in the data of Haavasoja.
Date: January 1, 1981
Creator: Roach, P.R.; Eckstein, Y. & Meisel, M.W.
Partner: UNT Libraries Government Documents Department

Hyperfine structure of stored ions. result for 2s /sup 3/He/sup +/

Description: The measurement, by radio-frequency spectroscopy, of the hyperfine structure (hfs) of the metastable 2s state of the /sup 3/He/sup +/ ion is presented. A brief discussion of the advantages and drawbacks of the ion-storage technique as applied to the hfs of ions, as well as a summary of previous ion-storage hfs measurements is given. The method used is described, and results for /sup 3/He/sup +/ are shown. 7 figures, 2 tables, 24 references. (GHT)
Date: August 1, 1976
Creator: Prior, M. H. & Wang, E. C.
Partner: UNT Libraries Government Documents Department

The superfluid Stirling refrigerator, a new method for cooling below 0. 5 K

Description: A new subkelvin refrigerator, the superfluid Stirling cycle refrigerator, uses a working fluid of [sup 3]He-[sup 4]He mixture in a Stirling cycle. The thermodynamically active components of the mixture are the [sup 3]He, which behaves like a Boltzman gas, and the phonon-roton gas in the [sup 4]He. The superfluid component of the liquid is inert. Two refrigerators have been built and temperatures of 340 mK have been achieved.
Date: April 9, 1993
Creator: Brisson, J.G.; Kotsubo, V. & Swift, G.W.
Partner: UNT Libraries Government Documents Department

Two dimensional NMR and NMR relaxation studies of coal structure

Description: This report covers the progress made on the title project for the project period. Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins are particularly promising. Methods combining proton-proton spin diffusion with [sup 13]C CPMAS readout are being developed to determine the connectivity of functional groups in coals in a high sensitivity relay type of experiment. Additional work is aimed at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.
Date: November 25, 1992
Creator: Zilm, K.W.
Partner: UNT Libraries Government Documents Department

Energy related studies utilizing K-feldspar thermochronology

Description: Two distinct sources of information are available from a [sup 40]Ar/[sup 39]Ar step-heating experiment: the age spectrum and Arrhenius plot. Model ages are calculated from the flux of radiogenic argon ([sup 40]Ar*) (assuming trapped argon of atmospheric composition) relative to the reactor produced [sup 39]Ar evolved during discrete laboratory heating steps. With the additional assumption that the [sup 39]Ar is uniformly distributed within the sample, we can infer the spatial distribution of the daughter product. ne associated Arrhenius plot, derived by plotting the diffusion coefficient (obtained from the inversion of the 39[sup Ar] release function assuming a single domain) against the inverse temperature of laboratory heating, are a convolution of the parameters which characterize the individual diffusion domains (whether these be dictated by varying length scale, energetics, etc.). However, many and perhaps Most [sup 40]Ar/[sup 39]Ar age spectra for slowly cooled alkali feldspars are significantly different from model age spectra calculated assuming a single diffusion-domain size. In addition, Arrhenius plots calculated from the measured loss of [sup 39]Ar during the step heating experiment show departures from linearity that are inconsistent with diffusion from domains of equal size. By extending the single diffusion-domain closure model (Dodsontype) to apply to minerals with a discrete distribution of domain sizes, we obtained an internally consistent explanation for the commonly observed features of alkali feldspar age spectra and their associated Arrhenius plots.
Date: January 1, 1993
Partner: UNT Libraries Government Documents Department

Energy flow in an arctic aquatic ecosystem

Description: This project has been using natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. We are processing samples collected at the R4D intensive site over the past three years and are comparing these data with similar samples collected from the coastal plain. Our approach is to determine if carbon is accumulating in upland and coastal tundra; to determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers.
Date: January 1, 1993
Creator: Schell, D.M.
Partner: UNT Libraries Government Documents Department

Energy transfer and isotopic enrichment in vibrationally pumped diatomic molecules

Description: The preliminary results from two experiments on vibration-vibration pumped CO are reported. The first experiment is a demonstration of isotopic enrichment by vibration-vibration pumping. An approx.300/sup 0/K translational temperature flowing mixture of CO, Ar and He is excited by a CO laser and the resulting non-equilibrium vibrational distribution is probed by laser induced fluorescence. In CO plus Ar mixtures, /sup 13/CO enrichments of a factor of three times the natural /sup 13/CO abundance are observed for high, v = 30, vibrational states. In CO plus Ar and He mixtures the /sup 13/CO enrichment is reduced to approximately its natural abundance. Calculations indicate that larger He mole fractions could result in relative enrichment of the /sup 12/CO isotope. The second experiment is a time and state resolved kinetics study of vibration-vibration pumped CO. A pulsed CO laser is used to produce a highly excited vibrational distribution. The vibrationally resolved overtone emission from the ground electronic state is monitored as a function of time for states v = 2 to 40. Electronic emission from the A-X band is also observed. In order to derive the kinetic rates for the various vibrational exchange processes, the data are compared with a kinetic model including all of the energy exchange terms. Preliminary calculations show reasonable agreement with the observed ground electronic state emission. 10 refs., 4 figs.
Date: January 1, 1984
Creator: DeLeon, R.L.; Rich, J.W.; Bergman, R.C. & Homicz, G.F.
Partner: UNT Libraries Government Documents Department

NMR analysis of coal macerals. Progress report

Description: A second set of six vitrinite samples were hand picked from the lower Kittanning Seam and obtained from Penn State University. The rank of the samples ranged from low volatile to high volatile B bituminous. The ultimate and proximate analyses are given in Table 1. This set of samples was selected in order to assess the nature of structural changes observed when carefully selected coal samples from a given seam are examined using CP/MAS techniques. In each case, the samples contained greater than 95% vitrinite. For purposes of clarity, the CP/MAS spectrum of PSMC-67 is given in Figure 1 as a composite of /sup 13/C chemical shifts of structural units containing H, C, and O. The vitrinite spectra thus displays the range of chemical structural types that give rise to resonance lines in different spectral regions. The banded structure observed provides enough detail to discuss major structural types present. A casual observation demonstrates that a significant amount of aliphatic oxygen is present (50 to 95 ppM region). Further interpretative details are given and also the changes in the spectra with rank progression are discussed.
Date: unknown
Creator: Pugmire, R.J.
Partner: UNT Libraries Government Documents Department

Geochemistry, petrology, and basin analysis. Quarterly report

Description: Progress was made in all three areas this quarter--geochemistry, petrology, and basin analysis. In geochemistry the isotope work is well-established as is elemental analysis. Both are useful in application of data from other sources to the shales sequence, as shown. The V/Ni is proceeding well, and should be complete by July. The phenolic aldehyde work is not yet started because of equipment supply problems. In petrology some important progress was made in internal surface area studies of the shale in the Cumberland Thrust. Thin section petrography of outcrop samples from the Virginia side of the thrust is nearly complete. In basin analysis, the basic stratigraphic work of the project is nearly complete, with perhaps some problems remaining in the lower part of the section. All contractors are encouraged to produce the isopach maps, etc. of each unit as soon as possible. Representatives from Cincinnati have attended several meetings this quarter helping to coordinate these activities. The paleocurrent study of the basin is very nearly complete, needing some final work along the western side.
Date: April 25, 1978
Creator: Maynard, J.B.; Potter, P.E. & Pryor, W.A.
Partner: UNT Libraries Government Documents Department

Muon-catalyzed fusion experiments at LAMPF

Description: Our collaboration has conducted a series of muon-catalysis experiments over broad temperature and density ranges at the LAMPF accelerator in Los Alamos. We have discovered surprising effects on the normalized muon-catalysis cycling rate, lambda/sub c/, and the apparent alpha-particle sticking coefficient, ..omega../sub s/, that depend on the d-t mixture density. This paper reviews our experimental approach, analysis methods, and results for tests with targets varying in density from 0.12 to 1.30, normalized to liquid hydrogen density, and in temperature from 15K to 800K. In particular, results will be presented on the cycling rate, sticking coefficient, and /sup 3/He scavenging rate, as functions of temperature, mixture density, or tritium concentration.
Date: January 1, 1986
Creator: Caffrey, A.J.; Anderson, A.N.; Van Siclen, C.D.W.; Watts, K.D.; Bradbury, J.N.; Gram, P.A.M. et al.
Partner: UNT Libraries Government Documents Department

/sup 13/C NMR studies of bacterial dihydrofolate reductase containing (methyl-/sup 13/C)methionine and (guanido-/sup 13/C)arginine. [Streptococcus]

Description: (Methyl-/sup 13/C)methionine and (guanido-/sup 13/C)arginine have been incorporated with high efficiency by Streptococcus faecium var. Durans strain A into dihydrofolate reductase isoenzyme 2 and /sup 13/C NMR spectra have been obtained for the labeled enzymes and their complexes with substrates, co-factors, and inhibitors. The /sup 13/C NMR spectra exhibit a high degree of discrimination--up to six guanido-/sup 13/C resonances spanning a 1.2 ppM range have been resolved for the eight arginine residues and, under certain conditions, seven methyl-/sup 13/C resonances spanning a 3 ppM chemical shift range have been resolved for the seven methionine residues of the enzyme. The /sup 13/C chemical shifts and spin lattice relaxation times of these distinct, relatively narrow resonances can be interpreted in terms of the conformational states of the enzyme and the interactions of the /sup 13/C-labeled residues with bound ligands. In a larger context, the results reported here provide experimental data which bear on a central question in the use of /sup 13/C NMR spectroscopy to probe the structure of labeled macromolecules, vis.: Where should the /sup 13/C label be incorporated to ensure a relatively narrow resonance whose chemical shift is nonetheless sensitive to perturbations of the macromolecule. Contrary to one accepted view, this study demonstrates that a significant degree of internal motion for a class of amino acid residues is not necessarily incompatible with a large chemical shift dispersion within the class.
Date: January 1, 1978
Creator: Matwiyoff, N.A.; London, R.E.; Walker, T.E.; Blakley, R.L. & Cocco, L.
Partner: UNT Libraries Government Documents Department