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Methyltrioxorhenium (MTO) catalyzes the desulfurization of thiiranes by triphenylphosphine. Enormous enhancement in rate is observed when the catalyst is pretreated with hydrogen sulfide prior to the reaction. Using 2-mercaptomethylthiophenol as a ligand, the author synthesized several model complexes to study the mechanism of this reaction. With suitable model systems, they were able to show that the active catalyst is a Re(V) species. The reactions are highly stereospecific and very tolerant to functional groups. As part of the studies, he synthesized and crystallographically characterized the first examples of neutral terminal and bridging Re(V)sulfidocomplexes. Some of these complexes undergo fast oxygen atom transfer reactions with organic and inorganic oxidants. Studies on these model complexes led them to the discovery that MTO catalyzes the selective oxidation of thiols to disulfides. This report contains the Introduction; ``Chapter 6: Isomerization of Propargylic Alcohols to Enones and Enals Catalyzed by Methylrhenium Trioxide``; and Conclusions.

Measurements of electrical resistivity as a function of temperature from 25 to 1,500 C were conducted on polycrystalline samples in the Mo-Si-B system. Single phase, or nearly single phase, samples were prepared for the following phases: Mo{sub 3}Si, Mo{sub 5}SiB{sub 2}, Mo{sub 5}Si{sub 3}B{sub x}, MoB, MoSi{sub 2}, and Mo{sub 5}Si{sub 3}. Thesis materials all exhibit resistivity values within a narrow range(4--22 x 10{sup {minus}7}{Omega}-m), and the low magnitude suggests these materials are semi-metals or low density of states metals. With the exception of MoSi{sub 2}, all single phase materials in this study were also found to have low temperature coefficient of resistivity(TCR) values. These values ranged from 2.10 x 10{sup {minus}10} to 4.74 x 10{sup {minus}10}{Omega}-m/{degree} C, and MoSi{sub 2} had a TCR of 13.77 x 10{sup {minus}10}{Omega}-m/{degree} C. The results from the single phase sample measurements were employed in a natural log rule-of-mixtures model to relate the individual phase resistivity values to those of multiphase composites. Three Mo-Si-B phase regions were analyzed: the binary Mo{sub 5}Si{sub 3}-MoSi{sub 2} system, the ternary phase field Mo{sub 5}Si{sub 3}B{sub x}MoB-MoSi{sub 2}, and the Mo{sub 3}Si-Mo{sub 5}SiB{sub 2}-Mo{sub 5} Si{sub 3}B{sub x} ternary region. The experimental data for samples in each of …

The Retinal Prosthesis project is a three year project conducted in part at the Lawrence Livermore National Laboratory and funded by the Department of Energy to create an epiretinal microelectrode array for stimulating retinal cells. The implant must be flexible to conform to the retina, robust to sustain handling during fabrication and implantation, and biocompatible to withstand physiological conditions within the eye. Using poly(dimethyl siloxane) (PDMS), LLNL aims to use microfabrication techniques to increase the number of electrodes and integrate electronics. After the initial designs were fabricated and tested in acute implantation, it became obvious that there was a need to characterize and understand the mechanical and electrical properties of these new structures. This knowledge would be imperative in gaining credibility for polymer microfabrication and optimizing the designs. Thin composite microfabricated devices are challenging to characterize because they are difficult to handle, and exhibit non-linear, viscoelastic, and anisotropic properties. The objective of this research is to device experiments and protocols, develop an analytical model to represent the composite behavior, design and fabricate test structures, and conduct experimental testing to determine the mechanical and electrical properties of PDMS-metal composites. Previous uniaxial stretch tests show an average of 7% strain before failure …

Photosynthesis is a complex process which results in the conversion of solar radiation into chemical energy. This chemical energy is then used as the free energy source for all living organisms. In its basic form, photosynthesis can be described as the light-activated synthesis of carbohydrates from the simple molecules of water and carbon dioxide: 6H{sub 2}O + 6 CO{sub 2} light C{sub 6}H{sub 12}O{sub 6} + 6 O{sub 2} This basic mechanism actually requires numerous reaction steps. The two primary steps being: the capture of light by pigment molecules in light-harvesting antenna complexes and the transfer of this captured energy to the so-called photochemical reaction center. While the preferred pathway for energy absorbed by the chromophores in the antenna complexes is transfer to the reaction center, energy can be lost to competing processes such as internal conversion or radiative decay. Therefore, the energy transfer must be rapid, typically on the order of picoseconds, to successfully compete. The focus of the present work is on the construction of light-harvesting antenna complexes incorporating modular pigment-proteins.

Despite more than thirty years having elapsed since the discovery of CP violation, our understanding about the source and the nature of this phenomenon is still very limited. In the standard model of particle physics, CP violation is due to the presence of an non-irreducible weak phase in the Cabibbo-Kabayashi-Maskawa(CKM) matrix. Up to now, all the experimental results are in good agreement with the standard model. However, it is important for us to over-constrain the CKM quark-mixing matrix and explore the possibility of new physics beyond the standard model. The B meson provides an ideal place to measure CP violation due to its heavy mass and potentially large CP-violating effects. In particular, the angle {gamma} of the Unitary Triangle relating the elements of the CKM matrix is extremely crucial in terms of CP violation and constraints on the new physics models. Various methods using B{sup -} {yields} D{sup 0}K{sup -} decays have been proposed to measure based on the interference between the V{sub cb} and V{sub ub} amplitudes. Despite the simple concept, the measurement turns out to be experimentally challenging due to the small branching fraction and the small value of {tau}{sub B}, the amplitude ratio between the two contributing …

A sample of 2500 {Xi}{sup -} and 500 {Xi}{sup 0} hyperons, produced in {Xi}K, {Xi}K{pi}, and {Xi}K{pi}{pi} final states by K{sup -} (in H{sub 2}) at incident momenta of 1.7 to 2.7 BeV/c, has been analyzed. The data are from an exposure (K-63) of 26 events/{mu}b in the 72-inch bubble chamber; approximately 85% of the {Xi}{sup -} events and 60% of the {Xi}{sup 0} events have been analyzed. For the {Xi}, they determine the spin and decay parameters a{sub {Xi}} and {Phi}{sub {Xi}} = tan{sup -1} ({beta}{sub {Xi}}/{Gamma}{sub {Xi}}). Combining their data with 900 {Xi}{sup -} and 150 {Xi}{sup 0} events from an earlier experiment (K-72), they obtain the following results: (1) {Xi} spin - J = 1/2 favored over J = 3/2 by {approx} 2.5 standard deviations; (2) {Xi} decay parameters (assuming a{sub {Lambda}} = 0.647 {+-} 0.048) - a{sub {Xi}{sup -}} = -0.398 {+-} 0.041, {Phi}{sub {Xi}{sup -}} = 9.8{sup o} {+-} 9.0{sup o}; a{sub {Xi}{sup 0}} = -0.413 {+-} 0.104. They observe {Xi}*(1530) and {Xi}*(1817); their data are insufficient for analysis of suggested {Xi}* resonances at 1705 and 1933 MeV. They measure the {Xi}*(1530) electromagnetic mass difference {Delta}m = m({Xi}*{sup -}) = m({Xi}*{sup 0}) = 2.0 {+-} …

Helium, with its two electrons and one nucleus, is a three-body system. One of the models for investigating correlated electron motion in this system is autoionization, produced via double excitation of the electrons. Predictions about the autoionization spectrum of helium have differed from each other and from preliminary experimental data. However, previous experiments have not been able to distinguish among the theoretical predictions because their energy resolution is not high enough to resolve the narrow linewidths of quasi-forbidden peaks and the resonances that appear in the highest excited states. Consequently, a team of researchers at Lawrence Berkeley National Laboratory have embarked on a project for building a high-resolution Fourier-Transform Soft X-ray (or VUV) interferometer (FTSX) to provide definitive data to answer remaining questions about the autoionization spectrum of helium. The design and construction of this interferometer is described in detail below, including the use of a flexure stage to provide the large path length difference necessary for high resolution measurements, the manufacture of x-ray beamsplitters, a description of the software, and the solution to the problems of stick-slip, vibration, and alignment. Current progress of its development is also described, as well as future goals.

By definition a plasma is an electrically conducting gaseous mixture containing a significant concentration of cations and electrons. The Inductively Coupled Plasma (ICP) is an electrodeless discharge in a gas at atmospheric pressure. This discharge is an excellent one for vaporizing, atomizing, and ionizing elements. The early development of the ICP began in 1942 by Babat and then by Reed in the early 1960s. This was then followed by the pioneering work of Fassel and coworkers in the late 1960s. Commercial ICP spectrometers were introduced in the mid 1970s. A major breakthrough in the area of ICP took place in the early 1980s when the ICP was shown to be an excellent ion source for mass spectrometry.

With the ever increasing awareness of the toxicity of Pb, significant pressure has been put on the electronics industry to get the Pb out of solder. This work pertains to the development and characterization of an alloy which is Pb-free, yet retains the proven positive qualities of current Sn-Pb solders while enhancing the shortcomings of Sn-Pb solder. The solder studied is the Sn-4.7Ag-1.7Cu wt% alloy. By utilizing a variety of experimental techniques the alloy was characterized. The alloy has a melting temperature of 217{degrees}C and exhibits eutectic melting behavior. The solder was examined by subjecting to different annealing schedules and examining the microstructural stability. The effect of cooling rate on the microstructure of the solder was also examined. Overall, this solder alloy shows great promise as a viable alternative to Pb-bearing solders and, as such, an application for a patent has been filed.

This thesis consists of three main parts. The first one relates to boron neutron capture therapy. It summarizes the guidelines obtained by numerical simulations for the treatment of shallow and deep-seated brain tumors, as well as the results on the design of beam-shaping assemblies to moderate D-D and D-T neutrons to epithermal energies. The second part is about boron neutron capture synovectomy for the treatment of rheumatoid arthritis. Optimal neutron energy for treatment and beam-shaping assembly designs are summarized in this section. The last part is on the development of the sealed neutron generator, including experimental results on the prototype ion source and the prototype accelerator column.

Mechanisms and associated energetics for adatom diffusion on the (100) and (110) surfaces of Ni, Cu, Rh, Pd, and Ag are investigated. Self-diffusion was studied on (100) and (I 10) surfaces of Ni, Cu, Pd and Ag using corrected effective medium method (CEM) and approximation to CEM used for molecular dynamics and Monte Carlo studies (MD/MC-CEM). Self-diffusion on Pd(100), Ag(100), Ni(110), Cu(110), Pd(110), and Ag(110) is accomplished by classical diffusion: the adatom hops from its equilibrium adsorption site over an intervening bridge site to an adjacent equilibrium site. Self-diffusion on Ni(100) and Cu(100) proceeds by atomic-exchange diffusion: the adatom on the surface displaces an atom in the first surface layer. Aside from explicit inclusion of the kinetic-exchange-correlation energy, it is critical to include enough movable atoms in the calculation to insure correct energetics. Distortions induced by these diffusion mechanisms, especially atomic exchange, are long ranged in surface plane, owing to small distortions of many atoms being energetically favored over large distortions of few atoms. Energetics and rates of heterogeneous adatom diffusion on the (100) surfaces of Ni, Cu, Rh, Pd, and Ag show that the final state energies differ due to variation of metallic bonding with coordination for different types …

This dissertation presented several results which add to the general knowledge base regarding organothiolates monolayer spontaneously adsorbed at gold films. Common to the body of this work is the use of voltammetric reductive resorption and variants of scanning probe microscopy to gain insight into the nature of the monolayer formation process as well as the resulting interface. The most significant result from this work is the success of using friction force microscopy to discriminate the end group orientation of monolayer chemisorbed at smooth gold surfaces with micrometer resolution (Chapter 4). The ability to detect the differences in the orientational disposition is demonstrated by the use PDMS polymer stamp to microcontact print an adlayer of n-alkanethiolate of length n in a predefine pattern onto a gold surface, followed by the solution deposition of a n-alkanethiol of n {+-} 1 to fill in the areas on the gold surface intentionally not coated by the stamping process. These two-component monolayers can be discriminated by using friction force microscopy which detects differences in friction contributed by the differences in the orientation of the terminal groups at surfaces. This success has recently led to the detection of the orientation differences at nanometer scale. Although the …

Scene reconstruction from video sequences has become a prominent computer vision research area in recent years, due to its large number of applications in fields such as security, robotics and virtual reality. Despite recent progress in this field, there are still a number of issues that manifest as incomplete, incorrect or computationally-expensive reconstructions. The engine behind achieving reconstruction is the matching of features between images, where common conditions such as occlusions, lighting changes and texture-less regions can all affect matching accuracy. Subsequent processes that rely on matching accuracy, such as camera parameter estimation, structure computation and non-linear parameter optimization, are also vulnerable to additional sources of error, such as degeneracies and mathematical instability. Detection and correction of errors, along with robustness in parameter solvers, are a must in order to achieve a very accurate final scene reconstruction. However, error detection is in general difficult due to the lack of ground-truth information about the given scene, such as the absolute position of scene points or GPS/IMU coordinates for the camera(s) viewing the scene. In this dissertation, methods are presented for the detection, factorization and correction of error sources present in all stages of a scene reconstruction pipeline from video, in the …

The Sudbury Neutrino Observatory (SNO) is a large-volume heavy water Cerenkov detector designed to resolve the solar neutrino problem. SNO observes charged-current interactions with electron neutrinos, neutral-current interactions with all active neutrinos, and elastic-scattering interactions primarily with electron neutrinos with some sensitivity to other flavors. This dissertation presents an analysis of the solar neutrino flux observed in SNO in the second phase of operation, while {approx}2 tonnes of salt (NaCl) were dissolved in the heavy water. The dataset here represents 391 live days of data. Only the events above a visible energy threshold of 5.5 MeV and inside a fiducial volume within 550 cm of the center of the detector are studied. The neutrino flux observed via the charged-current interaction is [1.71 {+-} 0.065(stat.){+-}{sub 0.068}{sup 0.065}(sys.){+-}0.02(theor.)] x 10{sup 6}cm{sup -2}s{sup -1}, via the elastic-scattering interaction is [2.21{+-}0.22(stat.){+-}{sub 0.12}{sup 0.11}(sys.){+-}0.01(theor.)] x 10{sup 6}cm{sup -2}s{sup -1}, and via the neutral-current interaction is [5.05{+-}0.23(stat.){+-}{sub 0.37}{sup 0.31}(sys.){+-}0.06(theor.)] x 10{sup 6}cm{sup -2}s{sup -1}. The electron-only flux seen via the charged-current interaction is more than 7{sigma} below the total active flux seen via the neutral-current interaction, providing strong evidence that neutrinos are undergoing flavor transformation as they travel from the core of the Sun to the …

An exposure assessment was performed at the equipment and vehicle maintenance repair shops operating at the U. S. Department of Energy Hanford site, in Richland, Washington. The maintenance shops repair and maintain vehicles and equipment used in support of the Hanford cleanup mission. There are three general mechanic shops and one auto body repair shop. The mechanics work on heavy equipment used in construction, cranes, commercial motor vehicles, passenger-type vehicles in addition to air compressors, generators, and farm equipment. Services include part fabrication, installation of equipment, repair and maintenance work in the engine compartment, and tire and brake services. Work performed at the auto body shop includes painting and surface preparation which involves applying body filler and sanding. 8-hour time-weighted-average samples were collected for benzene and noise exposure and task-based samples were collected for lead dust work activities involving painted metal surfaces. Benzene samples were obtained using 3M™ 3520 sampling badges and were analyzed for additional volatile organic compounds. These compounds were selected based on material safety data sheet information for the aerosol products used by the mechanics for each day of sampling. The compounds included acetone, ethyl ether, toluene, xylene, VM&P naphtha, methyl ethyl ketone, and trichloroethylene. Laboratory data …

Fast methods for separation and detection of important neurotransmitters and the releases in central nervous system (CNS) were developed. Enzyme based immunoassay combined with capillary electrophoresis was used to analyze the contents of amino acid neurotransmitters from single neuron cells. The release of amino acid neurotransmitters from neuron cultures was monitored by laser induced fluorescence imaging method. The release and signal transduction of adenosine triphosphate (ATP) in CNS was studied with sensitive luminescence imaging method. A new dual-enzyme on-column reaction method combined with capillary electrophoresis has been developed for determining the glutamate content in single cells. Detection was based on monitoring the laser-induced fluorescence of the reaction product NADH, and the measured fluorescence intensity was related to the concentration of glutamate in each cell. The detection limit of glutamate is down to 10{sup {minus}8} M level, which is 1 order of magnitude lower than the previously reported detection limit based on similar detection methods. The mass detection limit of a few attomoles is far superior to that of any other reports. Selectivity for glutamate is excellent over most of amino acids. The glutamate content in single human erythrocyte and baby rat brain neurons were determined with this method and results …

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The fundamental and practical aspects are described for extracting ions from atmospheric pressure plasma sources into an analytical mass spectrometer. Methodologies and basic concepts of inductively coupled plasma mass spectrometry (ICP-MS) are emphasized in the discussion, including ion source, sampling interface, supersonic expansion, slumming process, ion optics and beam focusing, and vacuum considerations. Some new developments and innovative designs are introduced. The plasma extraction process in ICP-MS was investigated by Langmuir measurements in the region between the skimmer and first ion lens. Electron temperature (T{sub e}) is in the range 2000--11000 K and changes with probe position inside an aerosol gas flow. Electron density (n{sub e}) is in the range 10{sup 8}--10{sup 10} {sup {minus}cm }at the skimmer tip and drops abruptly to 10{sup 6}--10{sup 8} cm{sup {minus}3} near the skimmer tip and drops abruptly to 10{sup 6}--10{sup 8} cm{sup {minus}3} downstream further behind the skimmer. Electron density in the beam leaving the skimmer also depends on water loading and on the presence and mass of matrix elements. Axially resolved distributions of electron number-density and electron temperature were obtained to characterize the ion beam at a variety of plasma operating conditions. The electron density dropped by a factor of 101 …

A variety of scenarios are considered which shed light upon the uses and limitations of classical geometric and topological notions in string theory. The primary focus is on situations in which D-brane or string probes of a given classical space-time see the geometry quite differently than one might naively expect. In particular, situations in which extra dimensions, non-commutative geometries as well as other non-local structures emerge are explored in detail. Further, a preliminary exploration of such issues in Lorentzian space-times with non-trivial causal structures within string theory is initiated.

We have presented results in two different yet strongly linked aspects of Higgs boson physics. We have learned about the importance of the Higgs boson for the fate of the Standard Model, being either only a theory limited to explaining phenomena at the electroweak scale or, if the Higgs boson lies within a mass range of 130 < m_H < 160 GeV the SM would remain a self consistent theory up to highest energy scales O(m_Pl). This could have direct implications on theories of cosmological inflation using the Higgs boson as the particle giving rise to inflation in the very early Universe, if it couples non-minimally to gravity, an effect that would only become significant at very high energies. After understanding the immense meaning of proving whether the Higgs boson exists and if so, at which mass, we have presented a direct search for a Higgs boson in associated production with a W boson in a mass range 100 < m_H < 150 GeV. A light Higgs boson is favored regarding constraints from electroweak precision measurements. As a single analysis is not yet sensitive for an observation of the Higgs boson using 5.3 fb^-1 of Tevatron data, we set limits …

High temperature alloys are reviewed, focusing on current superalloys and their coatings. The synthesis, characerization, and oxidation performance of a NiAl–TiB{sub 2} composite are explained. A novel coating process for Mo–Ni–Al alloys for improved oxidation performance is examined. The cyclic oxidation performance of coated and uncoated Mo–Ni–Al alloys is discussed.

n-Butane selective oxidation over the VPO catalyst to maleic anhydride is the first and only commercialized process of light alkane selective oxidation. The mechanism of this reaction is still not well known despite over twenty years of extensive studies, which can partially be attributed to the extreme difficulties to characterize catalytic reactions real-time under typical reaction conditions. In situ spectroscopic characterization techniques such as Infrared spectroscopy and laser Raman spectroscopy were used in the current mechanistic investigations of n-butane oxidation over VPO catalysts. To identify the reaction intermediates, oxidation of n-butane, 1,3-butadiene and related oxygenates on the VPO catalyst were monitored using FTIR spectroscopy under transient conditions. n-Butane was found to adsorb on the VPO catalyst to form olefinic species, which were further oxidized to unsaturated, noncyclic carbonyl species. The open chain dicarbonyl species then experienced cycloaddition to form maleic anhydride. VPO catalyst phase transformations were investigated using in situ laser Raman spectroscopy. This report contains Chapter 1: General introduction; Chapter 2: Literature review; and Chapter 5: Conclusion and recommendations.

This dissertation focuses on the development of methods for stable isotope metabolic tracer studies in living systems using inductively coupled plasma single and dual quadrupole mass spectrometers. Sub-nanogram per gram levels of molybdenum (Mo) from human blood plasma are isolated by the use of anion exchange alumina microcolumns. Million-fold more concentrated spectral and matrix interferences such as sodium, chloride, sulfate, phosphate, etc. in the blood constituents are removed from the analyte. The recovery of Mo from the alumina column is 82 {+-} 5% (n = 5). Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is utilized for the quantitative ultra-trace concentration determination of Mo in bovine and human blood samples. The average Mo concentration in reference bovine serum determined by this method is 10.2 {+-} 0.4 ng/g, while the certified value is 11.5 {+-} 1.1 ng/g (95% confidence interval). The Mo concentration of one pool of human blood plasma from two healthy male donors is 0.5 {+-} 0.1 ng/g. The inductively coupled plasma twin quadrupole mass spectrometer (ICP-TQMS) is used to measure the carbon isotope ratio from non-volatile organic compounds and bio-organic molecules to assess the ability as an alternative analytical method to gas chromatography combustion isotope ratio mass spectrometry …