Indiana University-Purdue University Indianapolis (IUPUI) / This thesis describes separations performed by Pressurized Planar Electrochromatography (PPEC), which is a chromatographic method developed at IUPUI. In PPEC the mobile phase is driven by electroosmotic flow, while the system is pressurized to allow temperature control. This results in a highly efficient chromatographic system that has several attractive attributes including the ability to separate multiple samples simultaneously. The first three chapters of the thesis describe the relationship of PPEC to other forms of chromatography, the theoretical background of PPEC, the PPEC apparatus, including the plate holders used, and the different manipulations involved in preparing a plate for a PPEC run. The fourth chapter describes two short studies. The first demonstrates that a very fast separation of steroids on a high efficiency sorbent layer can be effected by PPEC. This is illustrated by the separation of six steroids in three minutes on a Superspher layer, with an efficiency of over 100,000 plates per meter. The second study attempted to improve the efficiency of separation by imposing a temperature gradient. The study was not successful, possibly due to Joule heating within the layer overriding the temperature gradient. The final chapter of the thesis describes two different studies on separating peptides by PPEC. The first study was performed on a bonded C18 sorbent layer that was treated with Brij-35, which is a non-ionic surfactant that prevents irreversible adsorption of the peptides to the sorbent surface while allowing electroosmotic flow. The variables involved in preparing the plates by soaking in a Brij-35 solution were investigated as well as the variables for PPEC (temperature, pressure, electrical potential, and mobile phase composition and pH). It was possible to separate six peptides in eight minutes using this approach. The second study used monolithic sorbent layers prepared by Dr. Frantisek Svec of Lawrence Berkeley National Laboratory. Separations were by conventional PPEC on charged monoliths and by electrophoresis on neutral monoliths. The same variables for PPEC, listed in the above paragraph, were investigated for the monolith study. It was possible to separate six peptides in two minutes on neutral monoliths and in one minute on negatively charged monoliths.

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Advances in thin layer chromatography (TLC), including smaller more uniform particles, use of a scanning spectrophotometer (densitometer), and sample application devices, led to the development of the High Performance Thin Layer Chromatography (HPTLC) technique. HPTLC allows quantitative as well as qualitative results of much smaller amounts. in some cases down to the picogram level. With these advancements, the limiting factor in detection of smaller concentrations has become the plate itself, and more specifically the preparation of the absorbent and binder and the layering process. This research evaluated HPTLC plates from several manufacturers for significant differences between manufacturers and between plates of each manufacturer. Several concentrations of three drugs of abuse were applied, developed, and quantitated. Both Rf and peak area were statistically evaluated to look for any effect of manufacturer, specific plate for that manufacturer, specific drug, concentration, and/or cross nested effects. Significant differences were found between manufacturers for both Rf and peak area with E. Merck and Baker plates having the best overall results. All manufacturers were found to have some plates with obvious visual surface defects that were not suitable for use. The major source of variation for all manufacturers was the plate to plate variation rather than track to track deviations on any given plate. / Master of Science

A series of plate load tests were conducted at the experimental farm of the University of Pretoria. The test areas were levelled by means of three surface preparation methods namely, i) a thin layer of plaster of Paris; ii) a thin layer of well-graded sand and iii) by using only hand tools. In addition, a modified plate load test was designed to eliminate the effect of bedding errors that occur during these tests. Telescopic probes were used to measure the relative displacement at two points below the centre of the plate. The main objective of this research project was to first quantify the bedding errors that occur during plate load tests. Secondly, to evaluate the three different surface preparation methods used in plate load tests to achieve a levelled and smooth test surface, and lastly to evaluate the effectiveness of using telescopic probes in routine plate load tests to eliminate the effects of bedding errors. The stiffness values, determined from the vertical displacement of the plate, were compared with the internal stiffness values determined by means of the telescopic probes. All stiffness values were compared with continuous surface wave (CSW) measurements performed on the same material. The test apparatus, methods and results are discussed in this dissertation. To my / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Civil Engineering / unrestricted

A aflatoxina M1 (AFM1) é um metabólito tóxico resultante da biotransformação da aflatoxina B1 e pode ser secretada no leite de animais que ingerem alimentos contaminados com esta última. Considerando os efeitos adversos que podem ocorrer devido à ingestão do produto contaminado e visto que as crianças, maiores consumidoras deste alimento, são potencialmente mais sensíveis que os adultos aos efeitos desta micotoxina, a avaliação da presença de AFM1 no leite se faz necessária. Durante o período de março a novembro de 2006 foram analisadas 48 amostras de leite cru provenientes de 8 propriedades fornecedoras de leite para uma Cooperativa de Leite da Serra Gaúcha e 80 amostras de leite UHT, provenientes de 7 marcas distintas, comercializadas em Porto Alegre (RS). A metodologia empregada na análise de aflatoxina M1 envolveu partição líquido-líquido na etapa de extração, uso de coluna de sílica gel na etapa de purificação e Cromatografia em Camada Delgada para a detecção. O limite de detecção foi de 10 ng e a avaliação da eficiência do método apresentou valor de 86% no teste de recuperação. Nas condições de trabalho e pelo método utilizado nenhuma das amostras analisadas foi positiva para a presença de AFM1, sugerindo que as mesmas encontram-se dentro das conformidades legais. / Aflatoxin M1 (AFM1) is a toxic metabolite resulting of the biotransformation of aflatoxin B1, and may be sectreted in milk of animals that consume foods contaminated with aflatoxin B1. Considering the adverse effects that can occur when foods contaminated are consumed, and since children, the greatest milk consumer are potentially more susceptible than adults to the effects of this mycotoxin, the evaluation of the presence of AFM1 in milk is necessary. From March to November of 2006 48 samples of raw milk from 8 dairy farms that integrate a Milk Cooperative of mountain region of Rio Grande do Sul and 80 samples of UHT milk from 7 different brands commercialized in Porto Alegre were analized. The mehodology employed for the analysis of aflatoxin M1 involved liquid-liquid partition on the extraction step, use of silic gel column for the purification step and Thin Layer Chromatography for the detection. The evaluation of the method efficiency present a value of 86% in the recovery test and the detection level was 10ng. Following analysis conditions and the method employed none of the samples analyzed were positive for the presence of aflatoxin M1, suggesting that samples analysed attend the legal conformities.

This research contributes to worldwide efforts to miniaturize one of the most powerful and versatile analytical tools, gas chromatography (GC). If a rapid, sensitive and selective hand-held GC system is realized, it would have a wide range of applications in many industries and research areas. As a part of developing a hand-held GC system, this research focuses on the separation column, which is the most important component of a GC system. This thesis describes the development of a miniature separation column that has low thermal mass and an embedded heating element for rapid thermal cycling. The worlds first thin polymer film (parylene) GC column has been successfully developed. This thesis includes: first, a study of theoretical column performance of rectangular GC column; second, the design optimization of parylene column and embedded heating element; third, the development of new processes such as parylene micromolding and stationary phase coating technique for parylene column; fourth, the fabrication of parylene GC column with an embedded heating element; and lastly, the testing and evaluation of parylene GC column through GC analysis.

The protic acid-catalyzed polymerization of 1,6-anhydro-6-D-glucopyranose (I) was first reported one-half century ago; however, the mechanism of this reaction has not been resolved and is the topic under investigation in this thesis. In an attempt to resolve this mechanism, a number of 1,6-anhydrides structurally related to 1,6-anhydro-B-D-glucopyranose (I) were prepared and polymerized. The C-2, C-3, or C-4 hydroxyl group was either specifically blocked, replaced by a hydrogen atom or positioned different sterically. The relative rates of disappearance of monomer in the polymerization reaction were measured and this information used to propose a reaction mechanism.

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The ultrasonic nondestructive technique is mainly used to evaluate interior defect, material properties and outside dimensions by measuring the transmitting and reflecting sound waves. Generally, the evaluation of the ultrasonic testing depends on the amplitudes and delay time of the received signals; however, this research is focused on the analysis of the phase differences of the received signals. The leakage phenomenon of surface waves propagating at the liquid-solid interface has been studied for more than fifty years. The main characteristic of this phenomenon is the 180-degree phase difference between the reflected and leaky ultrasound when a bounded ultrasonic beam is incidented. And the null zone caused by the interference of these two waves is appearing in the reflected field. The phase difference is changed as the surface condition altered, including surface roughness and layered structures. The normal-mode theory is used at this research to analyze the analytical model of the leaky surface wave in thin layered structures. In experiments, the measurements of the reflected field are proceeded by the scanning system, so as to analyze the phase difference between the reflected and leaky ultrasound and calculate the layer thickness by the phase difference. As a result of the surface roughness of the thin layers, the leakage is more serious when the ultrasound propagates with lower frequency. For the consideration of locating the null-zone in the reflected field, this research prefers using lower frequency as an initial frequency at the beginning of the testing, then increasing the frequency to achieve a better sensitive of the thickness.

In this work, Schr&ouml / dinger and Dirac equations will be examined in geometries that confine the particles to hypersurfaces. For this purpose, two methods will be considered. The first method is the thin layer method which relies on explicit use of geometrical relations and the squeezing of a certain coordinate of space (or spacetime). The second is Dirac&rsquo / s quantization procedure involving the modification of canonical quantization making use of the geometrical constraints. For the Dirac equation, only the first method will be considered. Lastly, the results of the two methods will be compared and some notes on the differences between the results will be included.