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open access

1. Mono([8]annulene)Uranium(4) half-sandwich complexes, 2. Novel syntheses of symmetrically substituted cyclooctatetetraenes

Description: A reproducible, high-yield synthesis of mono([8]annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono([8]annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 … more
Date: October 1, 1991
Creator: Boussie, T. R.
open access

AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H₂ multilayers

Description: We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the … more
Date: November 1, 1991
Creator: Phelps, R. B.
open access

An amplitude analyses of the K K-bar system (M < 2 GeV/C{sup 2}) produced in J/{Psi} radiative decay

Description: Using the 5.8 {times} 10{sup 6} J/{psi} events collected by the MARK 3 experiment on the SPEAR e{sup +}e{sup {minus}} storage ring at SLAC, a mass independent amplitude analysis of the J/{psi} {yields} {gamma} K{sub s}K{sub s} and J/{psi} {yields} K{sup +}K{sup {minus}} decays is presented. For K{bar K} systems having mass less than 2 GeV/c{sup 2}, the efficiency-corrected spherical harmonic moments of the J/{psi} joint decay angular distribution are measured. Fits are then performed in each in… more
Date: November 1, 1991
Creator: Chen, Liang-Ping
open access

Application of a canine {sup 238}Pu dosimetry model to human bioassay data

Description: Associated with the use of 2{sup 238}Pu in thermoelectric power sources for space probes and power supplies for cardiac devices is the potential for human exposure to {sup 238}Pu, primarily by inhalation. In the event of human internal exposure, a means is needed for assessing the level of intake and calculating radiation doses. Several bioassay/dosimetry models have been developed for {sup 239}Pu. However, results from studies with laboratory animals have indicated that the biokinetics, and th… more
Date: August 1, 1991
Creator: Hickman, A. W. Jr.
open access

The application of psoralens to the study of DNA structure, function and dynamics

Description: A series of six nitroxide spin-labeled psoralens were designed, synthesized and tested as probes for DNA dynamics. The synthesis of these spin-labeled psoralen derivatives and their photoreactivity with double-stranded DNA fragments is described. The spin labels (nitroxides) were demonstrated to survive the uv irradiation required to bind the probe to the target DNA. EPR spectra of the photobound spin-labels indicate that they do not wobble with respect to the DNA on the time-scales investigate… more
Date: April 1, 1991
Creator: Spielmann, P. H.
open access

The application of the symmetry properties of optical second harmonic generation to studies of interfaces and gases

Description: Optical second harmonic generation has proven to be a powerful tool for studying interfaces. The symmetry properties of the process allow for surface sensitivity not available with other optical methods. In this thesis, we take advantage of these symmetry properties SHG to study a variety of interesting systems not previously studied with this technique. We show that optical second harmonic generation is an effective surface probe with a submonolayer sensitivity for media without inversion symm… more
Date: November 1, 1991
Creator: Feller, M. B.
open access

Automated insertion of sequences into a ribosomal RNA alignment: An application of computational linguistics in molecular biology

Description: This thesis involved the construction of (1) a grammar that incorporates knowledge on base invariancy and secondary structure in a molecule and (2) a parser engine that uses the grammar to position bases into the structural subunits of the molecule. These concepts were combined with a novel pinning technique to form a tool that semi-automates insertion of a new species into the alignment for the 16S rRNA molecule (a component of the ribosome) maintained by Dr. Carl Woese`s group at the Universi… more
Date: November 1, 1991
Creator: Taylor, R. C.
open access

Bis(pentamethylcyclopentadienyl) ytterbium: Electron-transfer reactions with organotransition metal complexes

Description: The divalent lanthanide complex, (Me{sub 5}C{sub 5}){sub 2}Yb, reacts with methylcopper to produce the base-free, ytterbium-methyl complex, (Me{sub 5}C{sub 5}){sub 2}YbMe. This product forms a asymmetric, methyl-bridged dimer in the solid state. The bulky alkyl complex, (Me{sub 5}C{sub 5}){sub 2}YbCH(SiMe{sub 3}){sub 2}, displays similar chemistry to (Me{sub 5}C{sub 5}){sub 2}YbMe, but at a reduced reaction rate due to the limited accessibility of the metal in (Me{sub 5}C{sub 5}){sub 2}YbCH(SiM… more
Date: November 1, 1991
Creator: Matsunaga, P. T.
open access

Budgets and behaviors of uranium and thorium series isotopes in the Santa Monica Basin off the California Coast

Description: Samples from three time-series sediment traps deployed in the Santa Monica Basin off the California coast were analyzed to study the flux and scavenging of uranium and thorium series isotopes. Variations of uranium and thorium series isotopes fluxes in the water column were obtained by integrating these time-series deployment results. Mass and radionuclide fluxes measured from bottom sediment traps compare favorably with fluxed determined from sediment core data. This agreement suggests that th… more
Date: December 16, 1991
Creator: Yu, Lei
open access

Calculations of Bottom Quark Production at Hadron Colliders

Description: This thesis studies Monte Carlo simulations of QCD heavy flavor production processes (p{bar p} {yields} Q({anti Q})X) at hadron colliders. ISAJET bottom quark cross-sections are compared to the O({alpha} {sub s}{sup 3}) perturbative calculation of Nason, Dawson, and Ellis. These Monte Carlo cross-sections are computed from data samples which use different parton distribution functions and physics parameters. Distributions are presented in the heavy quark`s transverse momentum and rapidity. Corr… more
Date: June 29, 1991
Creator: Kuebel, D.
open access

Capacitance of edge plane of pyrolytic graphite in acetonitrile solutions

Description: The capacitance of the edge plane of pyrolytic graphite electrodes, in acetonitrile solutions, is measured by recording the current response to an applied triangular voltage sweep; TVS, and then fitting the current response with an appropriate function, (via a set of adjustable parameters). The pretreatment of the electrodes, the supporting electrolyte concentration used, and the frequency of the input TVS, were all found to affect the measured capacitance. In these experiments, a background cu… more
Date: May 1, 1991
Creator: Minick, S. K. & Ishida, Takanobu
open access

Characterization of electrochemically modified polycrystalline platinum surfaces

Description: The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a singl… more
Date: December 1, 1991
Creator: Krebs, L. C. & Ishida, Takanobu
open access

A coarsening model for coherent precipitates

Description: The morphological evolution of coherent inclusions in elastic media is studied in two-dimensions. The inclusions are simple dilations with isotropic surface energy in a system with homogeneous elastic constants of negative anisotropy. The equilibrium sizes at which a circular inclusion transforms to a rectangle or square, and at which a square splits into a doublet or quartet of separated inclusions are computed analytically. A finite-element model is then constructed to simulate the evolution … more
Date: December 1, 1991
Creator: McCormack, M. T.
open access

Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

Description: The vibrational to translational (V{yields}T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibration… more
Date: October 1, 1991
Creator: Chu, P. M. Y.
open access

Continuous profiling of magnetotelluric fields

Description: The magnetotelluric (MT) method of mapping ground electrical conductivity is traditionally based on measurement of the surface impedance at widely spaced stations to infer models of the subsurface through a suitable pseudo 1-D inverse or with linearized least-squares inversion for 2- or 3-D geoelectric media. It is well known that small near-surface inhomogeneities can produce spatial discontinuities in the measured electric fields over a wide frequency range and may consequently bias the imped… more
Date: May 1, 1991
Creator: Verdin, C. T.
open access

Cracking behavior of cored structures

Description: The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a composition gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Data on stress corrosion cracking and fatigue crack growth in selected FCC alloys are used to illustrate the significance of … more
Date: September 1991
Creator: Wahid, A.; Olson, D.L.; Matlock, D.K. (Colorado School of Mines, Golden, CO (United States). Center for Welding and Joining Research) & Kelly, T.J. (General Electric Aircraft Engines, Evendale, OH (United States))
open access

Cross flow induced vibrations in staggered arrays of cylindrical structures

Description: Flow induced vibrations cause by instability is the subject of this investigation. The bulk of the work performed is theoretical in nature, the comparison with some of existing experimental data is given for each of four models described. First model encompasses the effects of prescribed motion on the cylinder. Such circumstances occur in the case of vortex shedding initiated instability. The reduced velocity within the cylinder array is low and there is no coupling between the adjacent cylinde… more
Date: December 31, 1991
Creator: Marn, J.
open access

D0 central tracking chamber performance studies

Description: The performance of the completed DO central tracking chamber was studied using cosmic rays at the State University of New York at Stony Brook. Also studied was a prototype tracking chamber identical in design to the completed DO tracking chamber. The prototype chamber was exposed to a collimated beam of 150 GeV pions at the Fermilab NWA test facility. Results indicate an R{Phi} tracking resolution compatible with the limitations imposed by physical considerations, excellent 2 track resolution, … more
Date: December 1991
Creator: Pizzuto, Domenico
open access

Design, development and evaluation of a precision air bearing rotary table with large diameter through-hole

Description: A large diameter precision air bearing rotary table with a 16.0 inch diameter through-hole was designed, fabricated and tested in the course of this research. The rotary table will be used in conjunction with a specialized, computer controlled precision inspection machine being designed for the Department of Energy`s (DOE) Nuclear Weapons Complex (NWC). The design process included a complete engineering analysis to predict the final performance of the rotary table, and to ensure that the rotary… more
Date: November 1, 1991
Creator: Accatino, M. R.
open access

Development of derived investigation levels for use in internal dosimetry at the West Valley Demonstration Project

Description: The objective was to determine if the routine intemal dosimetry program at the West Valley Demonstration Project is capable of meeting the performance objective of 1 mSv annual effective dose equivalent due to internal contamination. With the use of the computer code REMedy the annual effective dose equivalent is calculated. Some of the radionuclides of concern result in an annual effective dose equivalent that exceeds the performance objective. Although the results exceed the performance objec… more
Date: 1991
Creator: Johnson, Paul
open access

Electromagnetic dissociation of {sup 238}U in heavy-ion collisions at 120 MeV/A

Description: This thesis describes a measurement of the heavy-ion induced electromagnetic dissociation of a 120 MeV/A {sup 238}U beam incident on five targets: {sup 9}Be, {sup 27}Al, {sup nat}Cu, {sup nat}Ag, and {sup nat}U. Electromagnetic dissociation at this beam energy is essentially a two step process involving the excitation of a giant resonance followed by particle decay. At 120 MeV/A there is predicted to be a significant contribution of the giant quadrupole resonance to the EMD cross sections. The … more
Date: April 1, 1991
Creator: Justice, M. L.
open access

Electroweak phase transitions

Description: An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l_angle}{phi}{r_angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l_angle}{phi}{r_angle}{sub T}. In very minimal extensions of the standard mode… more
Date: September 16, 1991
Creator: Anderson, G. W.
open access

An evaluation of the Panasonic model UD513AC-1 Thermoluminescence Dosimetry system

Description: An evaluation of the Panasonic UD513AC-1 Thermoluminescence Dosimetry system was performed to determine the system`s capabilities as a general purpose thermoluminescence dosimeter measuring device. The tests that were performed included a critique of the user`s manual, delimitation of the operating parameters, the quality of construction, and an evaluation of the features that were unique to this system. The UD513AC-1 was found to be an adequate measuring device for most dosimetric applications… more
Date: December 1, 1991
Creator: Durrer, R. E., Jr.
open access

An experimental investigation of two-phase crossflow over rigidly and flexibly mounted tubes

Description: Two-phase crossflow over heat exchanger tubes induces vibrations which contribute greatly to the wear on the tubes. Of the three mechanisms leading to two-phase flow-induced vibrations which have been identified, fluid-elastic instability has been recognized as that which leads to the vibrations with the largest amplitude. The mass damping parameter is used to predict the onset of fluid-elastic instability, and the mean drag coefficient is used to calculate the mass damping parameter. In this t… more
Date: December 31, 1991
Creator: Gerhart, S.M.
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