Master of Science / Department of Physics / Carlos Trallero / This report presents the details of an electron time-of-flight (ETOF) spectrometer to be used for characterizing ultrafast electric field pulses. The pulses will range in pulse-duration from femtosecond to attoseconds and in wavelength from the far infrared (FIR) to the extreme ultra violet (XUV). By measuring the photoelectrons in the presence of two electric fields and their quantum interference we will be able to extract the amplitude and phase of the electric field. For XUV pulses this is the well-known streaking and Reconstruction of Attosecond Beating by Interference of Two-Photon Transition (RABITT) method. The ETOF is based on a set of tunable electrostatic lenses capable of detecting 0-150 eV electrons. In addition, we can selectively increase the photoelectron yield of the spectrum. The precise tuning of the electrostatic lens system is done with a Genetic Algorithm (GA) with an intensity fluctuation discriminator in the fitness.

Thin-layer chromatography (TLC) is of great importance for the pharmaceutical industry as a simple, quick, and low cost analytical method. Considerable effort has been made over the past decades to combine the simplicity of TLC with the selectivity and sensitivity of mass spectrometry (MS) detection. In the pharmaceutical industry sensitivity is an especially important factor, since the allowed impurity level of most drugs is under 0.1%.The aim of the present thesis was to develop methods for the direct examination of pharmaceutical compounds from TLC plates by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI TOF MS). The study was started by comparing several approaches for the application of the matrix for direct TLC-MALDI including a newly developed electrospray matrix deposition method. This new method was found to be superior to the other techniques studied. It produced a stable signal, minimised analyte spreading, and hence allowed the scanning of a TLC plate to obtain chromatographic as well as mass spectral data. The plotted mass chromatograms assisted in spot location, and allowed the calculation of Rf-values. These showed good agreement with the Rf -values determined by UV detection. The decrease in mass resolution and mass accuracy commonly observed in TLC-MALDI TOF MS due to the uneven nature of the silica gel layer was corrected by internal recalibration on selected matrix ions during the scanning of the TLC plate. To enhance the signals recorded directly from a TLC plate the use of an extraction solvent prior the matrix application was explored. Further improvements in sensitivity were obtained by modifying a robotic x-y-z axis motion system to act as an electrospray deposition device and by use of special Si 60 F[254] HPTLC-MALDI targets. Using both approaches sensitivities in the high fmol range were obtained. To minimise matrix interference, which can suppress analyte signals, the application of suspensions of particles of different materials and sizes (Co-UFP, TiN, TiO[2], graphite and silicon) onto eluted TLC plates were investigated. The structural analysis of pharmaceutical compounds was achieved by post-source decay - matrix-assisted laser desorption/ionisation (PSD-MALDI) mass spectrometry performed directly on the separated spots. TLC-MALDI MS is not only applicable to the qualitative analysis of pharmaceutical compounds. The generation of quantitative data by using a structural analogue as an internal standard is also described. Different approaches to the incorporation of the internal standard into the TLC plate were tested. The most successful approach was to develop the TLC plate in the mobile phase to which the internal standard was added. Good accuracy, precision, linearity and sensitivity was obtained using this approach.

Simultaneous localization and mapping (SLAM) is the problem of mapping your surroundings while simultaneously localizing yourself in the map. It is an important and active area of research for robotics. In this master thesis two approaches are attempted to reduce the drift which appears over time in SLAM algorithms. The first approach tries 3 different motion models for the camera. Two of the models exploit the a priori knowledge that the camera is mounted on a trolley. These two methods are shown to improve the results. The second approach attempts to reduce the drift by reducing noise in the point cloud data used for mapping. This is done by finding planar surfaces in the point clouds. Median filtering is used as an alternative to compare the result for noise reduction. The planes estimation approach is also shown to reduce the drift, while the median estimation makes it worse. / Simultaneous localization and mapping (SLAM) är problemet att kartlägga sin omgivning samtidigt som man lokaliserar sig själv i kartan. Det är ett viktigt och aktivt forskningsområde inom robotik. I det här exjobbet testas två tillvägagångssätt för att minska felet i kameraposition och orientering som uppstår över tiden i SLAM-lösningar. Det första tillvägagångssättet testar 3 olika rörelsemodeller för kameran. Två av modellerna utnyttjar vetskapen om att kameran sitter monterad på en vagn. Dessa två metoder förbättrar resultatet för SLAM-algoritmen. Det andra tillväggagångssättet försöker minska felet genom att reducera bruset i punktmolnsdatan som används i kartläggningen. Det görs genom att hitta plana ytor i punktmolnen. Medianfiltrering används som en alternativ lösning för att jämföra hur bra planestimeringen står sig. Planestimeringen visar sig också minska felet i lösningen, medan medianfiltreringen endast försämrar resultatet.

This thesis describes work on a novel 3D imaging system that successfully implements optical feedback and noise rejection mechanisms. The system is a combination of three relatively new technologies, namely, holographic projection, Time of Flight (ToF) ranging and Single Photon Avalanche Diode (SPAD) sensors. Holographic projection is used to provide structured illumination with optical feedback instead of more commonly used uniform illumination in similar imaging systems. It is obtained using a Ferro-electric Liquid Crystal on Silicon Spatial Light Modulator (FLCoS SLM). The structured illumination with optical feedback can be operated at up to 60 Hz with the current device, and has been shown to provide an average gain of about 1.56 in useful light levels. Alternatively, a gain over a limited area of up to a factor of 9 is possible with the current system. Time of Flight ranging is a method of choice for the system when depth estimation is concerned. It works even at very low light levels and allows for sub-centimetre depth resolution. ToF method was implemented using 20 MHz laser diode with 50 ps pulse duration and 200 mW peak power, as well as a SPAD sensor. The SPAD sensor consisted of a 32 32 array of 50 μm pixels, each with 10 bit Time to Digital Converter (TDC) with 50 ps timing resolution. Sensor pixels feature 100 Hz mean Dark Count Rate (DCR). The use of SPAD sensors with an adaptive sensing algorithm presented in this work has been demonstrated to reduce effective noise levels as seen by the sensor by a factor of 16. As a result, a significant gain in depth resolution can be achieved. The quantification of this gain is explained in more detail within this work. Furthermore, the work describes in detail system design, methodology of experimental procedure as well as different algorithms essential to the correct operation of the system. Significant amount of time is dedicated to diffraction pattern generation for the use in holographic projection, as well as modelling of photon detection in SPAD sensors and associated peak detection necessary to extract depth information from histograms of timed of photons. Moreover, the thesis discusses potential applications for the system based on the results of system characterisation presented in this work. The current state of the system suggests best suitability for gaming and machine vision applications. Finally, the work offers potential solutions to the practical issues that remain unresolved in the current system, alternatives for components used and paths for potential future development of the system proposed.

In spite of their importance in many systems, liquid surfaces have been explored at the microscopic level to a much lesser extent than solids. Most surface analysis must take place in vacuum, a major drawback for liquids. The technique of time-of-flight scattering and recoil spectrometry (TOF-SARS) has been applied to molecular liquid surfaces for the first time. The apparatus borrows key elements from previous TOF-SARS experiments on solids and from molecular beam scattering (MBS) and features excellent surface specificity and the ability to detect all elements. A high-vacuum time-of-flight spectrometer was developed for the purpose of measuring the surface atomic concentration of atoms in low-vapor pressure liquid samples, and hence to infer preferred surface orientations. The TOF-SARS experiment involves surface bombardment with inert gas ions in the 1-3 keV energy range. During the interaction surface atoms may either (a) induce scattering of primary ions or (b) recoil from the surface. A binary collision model describes the kinematics and dynamics of the interactions well, allowing prediction of velocities and probabilities of particles leaving the surface. Particles that reach a detector along a ~1.1 m flight path are separated by velocity, and signals are collected as a histogram, revealing relative measured intensities that are converted to ratios of accessible surface atoms. Comparing the measured atomic ratios with computer-simulated accessible atomic ratios for various possible orientations gives insight into preferred surface orientation. A number of systems were explored m this work: liquids including a complementary pair of molecules having distinct 'head-tails' structures; glycerol as a highly H-bonded system, and a room-temperature molten salt. Preliminary results reveal that surface molecules appear in most cases to adopt some preferred orientation at the interface. The TOF-SARS technique was able to distinguish 'head' from 'tail' in molecules exhibiting that structure, suggesting only part of the head was accessible. In glycerol, all but two possible orientations were ruled out but the symmetrical nature of the molecule prohibits definitive assignment. The ionic liquid was found to have the cation and anion sharing the surface population roughly equally, and a preferred orientation for the substituted aromatic anion was discovered. / Graduation date: 2000

This thesis reports studies of methane dehydro-aromatization (MDA) over Zn-based/HZSM-5 catalysts and the catalytic conversion of acetylene gas (C2H2) on grain surface reactions using time-of-flight mass spectrometry (TOF-MS). Both catalytic reactions generate polycyclic aromatic hydrocarbons (PAHs) as their final products. For the MDA reaction, the performance of Zn-based/HZSM-5 catalysts prepared by wet impregnation method was investigated under the conditions of atmospheric pressure and supersonic jet expansion (SJE). The experimental results revealed that, under the SJE condition, the Zn/HZSM-5 catalysts exhibited high catalytic activity. It was also found that because of the rapid migration of H+ ions on the catalyst, the activation of CH4 at active sites of nano-ZnO is facile. A new reaction mechanism involving an active “ZnO-CH3+...-H-ZnO” intermediate formed as a result of synergetic action between ZnO and HZSM-5 has been proposed for the dissociation of methane and dehydrogenation. However, under atmospheric pressure, the catalytic activity of the Zn/HZSM-5 catalysts was low. The physical properties of the catalyst were characterized by Brunauer-Emmett-Teller (BET), Fourier transform infrared (FT-IR), temperature-programmed reduction of H2 (H2-TPR), temperature -programmed desorption of NH3 (NH3-TPD), X-ray photoelectron spectroscopy (XPS), thermogravimetric and differential thermogravimetric (TG/ DTG), and high-resolution transmission electron microscopy (HRTEM) techniques. For the catalytic conversion reaction of acetylene gas to form PAHs, the grains used were olivine and pyroxene-type silicates as well as alumina. Gas-phase PAHs were produced by the catalytic reaction of acetylene over crystalline silicates and alumina in a pulsed jet expansion condition and the gaseous products detected using time-of-flight mass-spectrometry (TOF-MS). In a separate experiment, further confirmation of the catalytic conversion of PAHs was obtained with the acetylene gas at atmospheric pressure flowing continuously through a fixed-bed reactor. The gas effluent and carbonaceous compounds deposited on the catalysts were dissolved separately in dichloromethane and analyzed using gas-chromatography-mass spectrometry (GC-MS). Amongst the samples studied, alumina showed higher activity than the olivine and pyroxene-type silicates grains. A mechanism for PAH formation is proposed in which the Mg2+ in silicates and Al3+ ions in Al2O3 act as Lewis acid sites for the acetylene reactions. Experimental investigation indicated that these silicates and Al2O3 particles are capable of providing catalytic centers for adsorption and activation of acetylene molecules that are present in the circumstellar environments of mass-losing carbon stars. The structure and physical properties of the particles were characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and high-resolution transmission electron microscopy (HRTEM) techniques. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

The current streamline formulation is limited to single-porosity systems and is then not suitable for application to naturally fractured reservoirs. Describing the fluid transport in naturally fractured reservoirs has been recognized as a main challenge for simulation engineers due to the complicated physics involved. In this work, we generalized the streamline-based simulation to describe the fluid transport in naturally fractured reservoirs. We implemented three types of transfer function: the conventional transfer function (CTF), the diffusion transfer function (DTF), and the empirical transfer function (ETF). We showed that these transfer functions can be implemented easily in the current single-porosity streamline codes. These transfer functions have been added as a source term to the transport equation that describes the saturation evolution along the streamlines. We solved this equation numerically for all types of transfer functions. The numerical solution of the continuity equation with DTF and ETF requires discretizing a convolution term. We derived an analytical solution to the saturation equation with ETF in terms of streamline TOF to validate the numerical solution. We obtain an excellent match between the numerical and the analytical solution. The final stage of our study was to validate our work by comparing our dual-porosity streamline simulator (DPSS) to the commercial dual-porosity simulator, ECLIPSE. The dual-porosity ECLIPSE uses the CTF to describe the interaction between the matrix-blocks and the fracture system. The dual-porosity streamline simulator with CTF showed an excellent match with the dual-porosity ECLIPSE. On the other hand, dual-porosity streamline simulation with DTF and ETF showed a lower recovery than the recovery obtained from the dual-porosity ECLIPSE and the DPSS with CTF. This difference in oil recovery is not due to our formulation, but is related to the theoretical basis on which CTF, DTF, and ETF were derived in the literature. It was beyond the scope of this study to investigate the relative accuracy of each transfer function. We demonstrate that the DPSS is computationally efficient and ideal for large-scale field application. Also, we showed that the DPSS minimizes numerical smearing and grid orientation effects compared to the dual-porosity ECLIPSE.

Thesis (M.S.)--Rutgers University, 2007. / "Graduate Program in Biomedical Engineering." Includes bibliographical references (p. 23-24).

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 186-201).