In this work, we use lasers to enhance possibilities of laser desorption methods and to optimize coating procedure for capillary electrophoresis (CE). We use several different instrumental arrangements to characterize matrix-assisted laser desorption (MALD) at atmospheric pressure and in vacuum. In imaging mode, 488-nm argon-ion laser beam is deflected by two acousto-optic deflectors to scan plumes desorbed at atmospheric pressure via absorption. All absorbing species, including neutral molecules, are monitored. Interesting features, e.g. differences between the initial plume and subsequent plumes desorbed from the same spot, or the formation of two plumes from one laser shot are observed. Total plume absorbance can be correlated with the acoustic signal generated by the desorption event. A model equation for the plume velocity as a function of time is proposed. Alternatively, the use of a static laser beam for observation enables reliable determination of plume velocities even when they are very high. Static scattering detection reveals negative influence of particle spallation on MS signal. Ion formation during MALD was monitored using 193-nm light to photodissociate a portion of insulin ion plume. These results define the optimal conditions for desorbing analytes from matrices, as opposed to achieving a compromise between efficient desorption and efficient …

The variation in the oft-observed, thermally-forced, nocturnal katabatic winds along the east side of the Rocky Mountains can be explained by either internal variability or interactions with various other forcings. Though generally katabatic flows have been studied as an entity protected from external forcing by strong thermal stratification, this work investigates how drainage winds along the Colorado Front Range interact with, in particular, topographically forced mountain waves. Previous work has shown, based on measurements taken during the Atmospheric Studies in Complex Terrain 1993 field program, that the actual dispersion in katabatic flows is often greater than reflected in models of dispersion. The interaction of these phenomena is complicated and non-linear since the amplitude, wavelength and vertical structure of mountain waves developed by flow over the Rocky Mountain barrier are themselves partly determined by the evolving atmospheric stability in which the drainage flows develop. Perturbations to katabatic flow by mountain waves, relative to their more steady form in quiescent conditions, are found to be caused by both turbulence and dynamic pressure effects. The effect of turbulent interaction is to create changes to katabatic now depth, katabatic flow speed, katabatic jet height and, vertical thermal stratification. The pressure effect is found to …

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.

Inductively coupled plasma mass spectrometry (ICP-MS) is the technique of choice for rapid, high precision, semiquantitative elemental and isotopic analysis for over 70 elements. Less than 20 years after the first mass spectrum was obtained by ICP-MS, this technique has applications in clinical chemistry, geochemistry, the semiconductor industry, the nuclear industry, environmental chemistry, and forensic chemistry. The determination of many elements, though, by ICP-MS is complicated by spectral interferences from background species, interelement spectral overlaps, and polyatomic ions of matrix elements. The emphasis of this thesis is the unique applications of solvent removal using cryogenic and membrane desolvation. Chapter 1 is a general introduction providing background information concerning the need for these methods and some information about the methods themselves. Chapter 5 discusses general conclusions and general observations pertaining to this work. Chapters 2, 3, and 4 have been processed separately for inclusion on the database. Chapter 2 describes a method to screen urine samples for vanadium using cryogenic desolvation. Chapter 3 compares solvent removal by cryogenic and membrane desolvation. Chapter 4 describes the use of cool plasma conditions for the determination of potassium in the presence of excess sodium by ICP-MS.

Scanning probe microscopy (SPM) offers access to the structural and material properties of interfaces, and when combined with macroscopic characterization techniques results in a powerful interfacial development tool. However, the relative infancy of SPM techniques has dictated that initial investigations concentrate on model interfacial systems as benchmarks for testing the control and characterization capabilities of SPM. One such family of model interfacial systems results from the spontaneous adsorption of alkyl thiols to gold. This dissertation examines the application of SPM to the investigation of the interfacial properties of these alkyl thiolate monolayers. Structural investigations result in a proposed explanation for counterintuitive correlations between substrate roughness and heterogeneous electron transfer barrier properties. Frictional measurements are used for characterization of the surface free energy of a series of end-group functionalized monolayers, as well as for the material properties of monolayers composed of varying chain length alkyl thiols. Additional investigations used these characterization techniques to monitor the real-time evolution of chemical and electrochemical surface reactions. The results of these investigations demonstrates the value of SPM technology to the compositional mapping of surfaces, elucidation of interfacial defects, creation of molecularly sized chemically heterogeneous architectures, as well as to the monitoring of surface reactions. However, …

Three-dimensional creeping flow around single, axisymmetric protrusions is studied numerically using the boundary-integral technique. Emphasis is placed upon cylindrical protrusions on plane walls for various height-to-radius (h-to-a) aspect ratios, but cones and sections of spheres protruding from plane walls are also briefly examined. The presented items include shear-stress distributions, shear-stress contours, extents of the fluid-flow disturbance, total forces and torques on the cylinders, streamlines, and skin-friction lines. Also included is a discussion of flow topology around axisymmetric geometries. No flow reversal is observed for cylindrical protrusions with aspect ratios greater than 2.4 to 2.6. At higher aspect ratios, the fluid tends to be swept around cylindrical protrusions with little vertical motion. At lower aspect ratios, the strength of the recirculation increases, and the recirculation region becomes wider in the transverse direction and narrower in the flow direction. Also, the recirculation pattern begins to resemble the closed streamline patterns in two-dimensional flow over square ridges. However, unlike two-dimensional flow, closed streamline patterns are not observed. For arbitrary axisymmetric geometries, the extent of the fluid-flow disturbance can be estimated with the total force that is exerted on the protrusion. When the same force is exerted on protrusions with different aspect ratios, the …

The Full Potential Linear Augmented Plane Wave (FPLAPW or FLAPW) method is used for a spin-polarized band calculation for ordered Fe{sub 3}Pt. As major purpose, the momentum distributions of the spin-polarized electrons are calculated and compared with results from a magnetic Compton scattering measurement. To get related information, the electronic behavior is also analyzed by examining the partial densities of states and the spatial electron distributions; the role of alloying effects is then explored by studying the electrons in some related alloys: Fe{sub 3}Ni, Fe{sub 3}Pd, Ni{sub 3}Pt and Co{sub 3}Pt.

The single crystals of TiNiSn and polycrystalline PtMnSb were grown by the flux and melt cooling method. Their lattice parameters and structures were determined by x-ray diffraction. The effect of impurities on the growth of TiNiSn single crystals was investigated. It was found that the concentration of chlorine plays a key role in determining the chemical composition of the phases that are formed. The heat capacity and magnetic susceptibility of TiNiSn was measured in a temperature range from 4.7 K to room temperature. Magnetic measurements show that the TiNiSn is paramagnetic, and that it does not order magnetically.

This thesis reports on the measurement of the W and Z boson inclusive production cross sections ({sigma}{sub W} and {sigma}{sub Z}) times electronic branching ratios (Br(W {r_arrow} e{nu}) and Br(Z {r_arrow} ee)) in p{anti p} collisions at {radical}s = 1.8 TeV. The analysis is based on 12.8 pb{sup {minus}1} of data taken in the 1992--1993 run by the D0 detector at the Fermilab Tevatron collider; the cross sections were measured to be: {sigma}{sub W} {center_dot} Br(W {r_arrow} e{nu}) = 2.36 {+-} 0.02 {+-} 0.07 {+-} 0.13 nb and {sigma}{sub Z} {center_dot} Br(Z {r_arrow} ee) = 0.218 {+-} 0.008 {+-} 0.008 {+-} 0.012 nb. The first error is statistical, the second error represents the non-luminosity systematic error, and the third error shows the uncertainty in the luminosity determination. Future prospects for similar measurements based on larger samples of data are discussed.

Effective on March 15, 1990, the Environmental Protection Agency established regulations controlling the emission of radionuclides to the air from Department of Energy facilities to limit the dose to the public to 10 mrem/yr. These regulations are detailed in 40 CFR 61, Subpart H, {open_quotes}National Emission Standards for Emissions of Radionuclides Other Than Radon from Department of Energy Facilities{close_quotes}. Part of these regulations require the operation of sampling systems on stacks meeting certain requirements. Although Los Alamos National Laboratory has a long history of stack sampling, the systems in place at the time the regulation became effective did not meet the specific design requirements of the new regulation. In addition, certain specific program elements did not exist or were not adequately documented. The Los Alamos National Laboratory has undertaken a major effort to upgrade its compliance program to meet the requirements of USEPA. This effort involved: developing new and technically superior sampling methods and obtaining approval from the Environmental Protection Agency for their use; negotiating specific methodologies with the Environmental Protection Agency to implement certain requirements of the regulation: implementing a complete, quality assured, compliance program; and upgrading sampling systems. After several years of effort, Los Alamos National Laboratory now …