by King Lai Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 86-93). / Title Page --- p.i / Table of Contents --- p.ii / List of Tables --- p.iv / List of Figures --- p.v / Abbreviations --- p.viii / Acknowledgements --- p.ix / Abstract --- p.x / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1. --- Mass Spectrometry for Macromolecular Analysis --- p.1 / Chapter 1.2. --- Laser Desorption --- p.3 / Chapter 1.3. --- Development of Matrix-assisted Laser Desorption/Ionization (MALDI) --- p.4 / Chapter 1.4. --- Matrix-assisted Laser Desorption/Ionization --- p.5 / Chapter 1.4.1. --- Laser --- p.6 / Chapter 1.4.2. --- Matrix Selection --- p.6 / Chapter 1.4.3. --- Sample Preparation Methodology --- p.7 / Chapter 1.4.4. --- Ion Formation Process(es) --- p.7 / Chapter 1.4.4.1. --- Desorption --- p.8 / Chapter 1.4.4.2. --- Ionization --- p.9 / Chapter 1.5. --- Time-of-Flight Mass Spectrometry --- p.12 / Chapter 1.6. --- Outline of the Present Work --- p.16 / Chapter CHAPTER TWO --- INSTRUMENTATION AND EXPERIMENTAL / Chapter 2.1. --- Instrumentation --- p.17 / Chapter 2.1.1. --- Laser System --- p.17 / Chapter 2.1.2. --- Ion Source --- p.19 / Chapter 2.1.3. --- Reflector --- p.20 / Chapter 2.1.4. --- Detector --- p.20 / Chapter 2.2. --- Experimental --- p.21 / Chapter 2.2.1. --- Synthesis of nitroanthracene-d9 --- p.21 / Chapter 2.2.2. --- Sample Preparation --- p.22 / Chapter CHAPTER THREE --- STUDIES OF THE EFFECTS OF SOLUTION pH / Chapter 3.1. --- Introduction --- p.25 / Chapter 3.2. --- Sample Preparation --- p.26 / Chapter 3.3. --- Results and Discussion --- p.28 / Chapter 3.3.1. --- Effect of Bronsted Base (NaOH) --- p.28 / Chapter 3.3.2. --- Effect of Lewis Base (Imidazole) --- p.33 / Chapter 3.3.3. --- Effect of Salt Concentration --- p.40 / Chapter 3.4. --- Conclusions --- p.44 / Chapter CHAPTER FOUR --- PROTON SOURCES FOR ION GENERATION IN MALDI-MS / Chapter 4.1. --- Introduction --- p.46 / Chapter 4.2. --- Sample Preparation --- p.47 / Chapter 4.3. --- Results and Discussion --- p.49 / Chapter 4.4. --- Conclusions --- p.55 / Chapter CHAPTER FIVE --- CATIONIZATION PROCESSES IN MALDI-MS : ATTACHMENT OF DIVALENT AND TRIVALENT METAL IONS / Chapter 5.1. --- Introduction --- p.57 / Chapter 5.2. --- Sample Preparation --- p.58 / Chapter 5.3. --- Results and Discussion --- p.60 / Chapter 5.3.1. --- Protonation versus Cationization --- p.60 / Chapter 5.3.2. --- Attachment of Divalent and Trivalent Metal Ions --- p.63 / Chapter 5.4. --- Conclusions --- p.80 / Chapter CHAPTER SIX --- CONCLUDING REMARKS --- p.82 / REFERENCES --- p.86

An experimental study was performed in which an ammonia-water solution was desorbed within a branching fractal-like microchannel array. The solution entered in the center of a disk, and flowed out radially until discharging in to a gravity-driven separation chamber. Heat was added to the ammonia-water through a thin wall, above which flowed heat transfer oil in a separate branching fractal-like microchannel array. Such arrays have been shown to utilize the increased heat transfer coefficients seen in parallel channel arrays; however, they do so with a lower pressure drop. An experimental flow loop consisting of ammonia-water and heat transfer oil sub-loops was instrumented along with a test manifold for global measurements to be taken. Temperature, pressure, density and mass flow rate measurements permitted calculation of desorption and heat transfer characteristics. Parameters included oil mass flow rate, oil inlet temperature, and strong solution flow rate, while strong solution concentration, temperature, and weak solution pressure were kept constant. The desorber was assumed to achieve equilibrium conditions between the vapor and weak solution in the separation chamber. The exit plenum was large and acted as a flash chamber, making the assumption reasonable. The vapor mass fraction was determined from knowledge of the weak solution saturation temperature. Heat exchanger analyses (LMTD and ε-NTU) were done to determine the heat transfer characteristics of the desorber. Calculated values of UA are shown to be as high as 5.0 W/K, and desorber heat duties were measured as high as 334 W. Strong solution, at 0.30 mass fraction, was desorbed into weak solution and vapor with concentrations ranging from 0.734 to 0.964. Circulation ratios, defined as strong solution mass flow rate per unit desorbed vapor mass flow rate, varied in this study from 3.4 to 20. A method for specifying desorber operating conditions is described, in which a minimum desorber heat input per unit vapor flow rate is determined at an optimum circulation ratio. A description of how the circulation ratio behaves as a function of strong solution mass flow rate, oil flow rate, and the maximum temperature difference between oil and ammonia-water solution is shown. / Graduation date: 2006

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

The transport of health-related organic micropollutans has been a major water quality and environmental issue in the past few decades. Because of their high toxicity, long environmental half-life and high bioaccumulation factors, many of the hydrophobic organic pollutants (HOPs) are listed as priority pollutants in many countries. Although not all of the chemical and physical factors should be considered in the fate of transportation of all chemicals, a simple one-dimensional mathematical model used to simulate all of the factors was conceptually developed (Bobba et al., 1996). In that study, most important parameters needed in the model were empirically fitted. For numerical simulation of the behaviors of pollutants in the environment, it is important to provide a feasible chemical and physical transport mechanism to describe the geo-chemical and geophysical interactions involved in the system. In this study a general two-dimensional hydrodynamic numerical simulation model is developed .This model can readily extend to a three-dimensional one. The model includes all possible physical and chemical factors that might affect the transport of the pollutants. For validation and demonstration purpose, only sorption-desorption between specified dissolved organic material and phase are studied in the present study. The hydrodynamic model is verified by comparing with the reported numerical results. The numerical model then incorporates the sorption-desorption terms and the sediment effects. From the results of the simulation, the sorption-desorption mechanism and sediment scavenge effect are founded to significantly affects the pollutants fate and transport of an outfall discharge.

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The carbonaceous material possesses many kinds of structures and extensive applicability. For example, they are used for lithium battery and fuel cell electrode, printer¡¦s carbon powder, and for the reinforcement of tire. The carbon nanotube and carbon nanocapsule are the novel carbonaceous materials. Their unique property and applicability have attracted a lot of investigation. In this research, we attempt to understand the relationship between the structures and chemical properties of the carbonaceous material. Graphite is an ideal model for this study, and the temperature-programmed desorption method is applied in this investigation. XRD and TEM are also used to support the results of TPD method. Four kinds of exploration molecules are chosen. They are benzene-like molecules, cyclohexane-like molecules, long chain molecules and alcohol-like molecules, respectively. We attempt to find out the differences of the interaction between graphite and various kinds of molecules. The benzene-like molecules with alkyl branch are strongly adsorbed on graphite. The adsorption of long chain molecules on graphite is the next. There are more than one kind of adsorption site on graphite available for 1,3-hexadiene and alcohol-like molecules adsorption. The adsorption behavior of 1,3-hexadiene and alcohol molecules are more complicated. Although the desorption activation energy for different molecules on graphite with different coverages are different. The difference in the desorption activation energy are negligible. The tendency of change is similar for the same kind of molecules. The adsorbed molecules can also diffuse into graphite¡¦s interlayer structure. The interlayer distance of graphite can be changed by the diffusion process of the adsorbed molecules. The desorption activation energies may change when graphite¡¦s pore size changes or functional groups exist on graphite surface. The changes of the activation energy caused by the change of graphite¡¦s pore size or by the surface functional groups are more prominent than the changes induced by the coverage difference of adsorbed molecules on graphite.

With the decrease in feature size in semiconductor manufacturing, molecular contamination problems are increased significantly. In order to optimize the yields in wafer fabrication units there is a need for process modeling that addresses the details of wafer contamination. Wafer contamination and cleaning is a complex process that covers various length and time scale events and phenomena. At the largest scales, there is the availability and transport of specific species within the fabrication unit and subsequent contamination of the wafer surface either through processing steps or through simple ambient transport processes. To limit wafer contaminant levels and/or to decontaminate them, wafers in the semiconductor fabrication unit are often cleaned and transported in a closed enclosure called Front Opening Unified Pod (FOUP) and purged with an inert gas like nitrogen. For the FOUP geometry, I analyze the large scale process modeling approaches to cleaning wafers. At smaller scales, the specific molecular configuration of the contaminant species impacts the kinetic chemical-physical cleaning mechanisms. To determine, from a fundamental perspective, the mechanisms contributing to wafer cleaning requires different scale tools from transport tools aimed at characterizing equipment scale (e.g., FOUP) contamination issues. I use molecular dynamics models and optimization techniques to infer physicochemical rates for molecular desorption on wafer surfaces. This dissertation considers these problems from a common perspective. The objective of this study has been to characterize the multi-scale problem of wafer cleaning with the objective of developing appropriate tools and models at different scales to best predict the dynamics of contaminant removal from wafer surfaces. A standardized method has been presented to extract kinetic rate parameters using molecular dynamics simulation (smaller-scale) and optimization for use in a larger-scale model of wafer decontamination using computational fluid dynamics (CFD). Also, by using available experimental data and CFD analysis an optimized FOUP purging recipe for better decontamination is presented and the relative magnitude of the time scales associated with surface kinetics and FOUP purging have been estimated. / text

There are 1,305 Superfund Sites on the United States Environmental Protection Agencies National Priorities List that may require remediation due to the environmental or human health risks associated with subsurface contamination. The contaminants present at these sites and others vary with respect to their physical and chemical properties which dictate the selection of appropriate remediation technologies. In-Situ Thermal Desorption (ISTD) has been studied as a remediation technique for removing many recalcitrant contaminants from soil. ISTD involves passing electrical current through heating elements in wells and removing contaminants through heater/vacuum wells. Heating occurs by heat conduction through the soil. At high temperatures, even relatively low volatility contaminants can be vaporized, removed by vacuum and treated with an on-site recovery system. The main objective of this research was to design and test a laboratory apparatus scaled to a typical ISTD field site and to use it to conduct experiments that could be used to aid in the validation of the STARS numerical simulator. A dimensional analysis was done on the governing energy balance equation to determine the most important scaling groups for the ISTD process so the laboratory experiments could be scaled up to the field. The laboratory apparatus was modeled after a symmetry element of the hexagonal field pattern and a triangular glass prism was constructed for heated sandpack experiments. Temperature data was measured in dry sand, sand partially saturated with water, and sand with both water and PCE added to it. The apparatus was made of glass so that the behavior of the PCE contaminant could be observed when the sand was heated. / text

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Thesis (M.Sc.)(Soil Science)--University of Pretoria, 2008. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.