Rozprawy doktorskie na temat „Analytical techniques”

Novel applications of optical analytical techniques have been demonstrated in three general areas, namely application of broadband cavity enhanced absorption spectroscopy (BBCEAS) to the detection of liquid phase analytes, the use of total luminescence spectroscopy to discriminate between different type of teas and the development of an optical sensor to detect ammonia gas, based on the fluorescence quenching of a dye immobilised in a sol gel matrix. A simple BBCEAS setup has been developed with a view to perform sensitive visible wavelength measurements on liquid phase solutions. In the present work a simple low-cost experimental setup has been demonstrated for the measurement of the visible spectra of representative liquid-phase analytes in a 2 mm quartz cuvette placed at normal incidence to the cavity mirrors. Measurements on Ho3+ and sudan black with a white LED and the R ≥ 0.99 mirrors covered a broad wavelength range (~250 nm) and represents the largest wavelength range covered to date in a single BBCEAS experiment. The sensitivity of the technique as determined by the best αmin value was 5.1 x 10-5 cm-1 and was obtained using the R ≥ 0.99 mirrors. The best limit of detection (LOD) for the strong absorber brilliant blue-R, was approximately 620 pM. The optical setup was then optimised for the application of BBCEAS detection to an HPLC system. A 1 cm pathlength HPLC cell with a nominal volume of 70 ml was used in this study. The cavity was formed by two R ≥ 0.99 plano-concave mirrors with a bandwidth of ~ 420 – 670 nm. Two analytes rhodamine 6G and rhodamine B were chosen for separation by HPLC, as they were chemically similar species with distinctive visible spectra and would co-elute in an isocratic separation. The lowest value of amin obtained was 1.9 x 10-5 cm-1. The most significant advantage of the HPLC-BBCEAS study over previous studies arose from the recording of the absorption spectrum over a range of wavelengths. It was demonstrated that the spectral data collected could be represented as a contour plot which was useful in visualising analytes which nearly co-eluted. The LOD values for the two analytes studied indicated that the developed HPLC-BBCEAS setup was between 54 and 77 times more sensitive than a commercial HPLC system. For improved sensitivity and lower detection limits the low cost BBCEAS setup was used with a significantly longer 20 cm pathlength cell where the mirrors were in direct contact with the liquid phase analyte. This also reduced interface losses. The experiments were carried out using both R ³ 0.99 and R ³ 0.999 mirrors. The lowest αmin value obtained in this study was 2.8 x 10-7 cm-1 which is the lowest reported value to date for a liquid phase measurement, making this study the most sensitive liquid phase absorption measurement reported. The lowest LOD recorded was 4.6 pM, and was obtained for methylene blue with the R ³ 0.999 mirrors. A novel application of total luminescence spectroscopy to discriminate between different types of teas objectively was also investigated. A pattern recognition technique based on principal component analysis (PCA) was applied to the data collected and resulted in discrimination between both geographically similar and dissimilar teas. This work has shown the potential of fluorescence spectroscopy to distinguish between seven types of teas from Africa, India, Sri Lanka and Japan. Geographically similar black teas from 15 different plantation estates in Sri Lanka were also studied. The visualisation technique allowed the separation of all 11 types of teas when the first two principal components were utilised. The final part of the thesis describes the development of an optical sensor for the detection of ammonia gas. The operation of the sensor depended on the fluorescence quenching of the dye 9 amino acridine hydrochloride (9 AAH) immobilised in a sol gel matrix. It was also shown that the sensor response was not affected by the presence of acidic gases such as HCl and SO2. The final version of the sensor made use of dual channel monitoring to improve the sensitivity of the sensor. Measurements using diluted mixtures of ammonia gas in the range 5 -70 ppm showed that the response of the sensor was nonlinear, with the sensitivity increasing at lower concentrations. The measurement of the baseline noise allowed the LOD to be estimated at ~400 ppb.

Since the invention of FPGAs in 1984, their capabilities have increased dramatically making them more speed, area, and power efficient than older reconfigurable devices. These advances were made possible by better computer aided design tools and the continuous development of algorithms used to both design the chips, and to map circuits onto them. However, current methodologies for FPGA chip design suffer from their dependence on empirical approaches which sample the design space based on intuition and heuristic techniques. As a result these empirical tools might result in good architectures but their optimality cannot be measured. This thesis argues the case for the use of analytical models in heterogeneous FPGA architecture exploration. It shows that the problem, when simplified, is amenable to formal optimisation techniques such as Integer Linear Programming (ILP). However, the simplification process may lead to inaccurate models causing uncertainty about the quality of the results. Consequently, existing accurate models such as that used in the versatile place and route (VPR) tool are used to quantify the performance of the analytical framework in comparison with traditional design methodologies. The results obtained in this thesis show that the architectures found by the ILP model are better than those found using traditional parameter sweep techniques with an average improvement of up to 15% in speed. In addition, these architectures are further improved by combining the accuracy of VPR with the efficiency of analytical techniques. This was achieved using a closed loop framework which iteratively refines the analytical model using place and route information from VPR. The results show a further average improvement of 10% and a total improvement of 25% in comparison with a parameter sweep methodology. In summary, the work carried out in this thesis shows that the ILP architecture exploration framework may not model heterogeneous architectures as accurately as current place and route tools, however, it improves on parameter sweep techniques by exploring a wider range of designs.

This thesis describes the development and application of hydrodynamic modulation voltammetric (HMV) techniques coupled to ultramicroelectrodes (UMEs) that possess intrinsically high mass transport rates in quiescent solutions. This study demonstrates that the well defined convective-diffusive conditions of the microjet electrode (MJE) arrangement allows mass transport to be enhanced by almost two orders of magnitude compared to a 25 mm diameter disc-shaped UME. The MJE comprises a nozzle which is used to deliver solution to a UME surface at high velocity. Scanning electrochemical microscopy (SECM) with small UMEs has been used to image the hydrodynamics of the jet system with high precision. Variations in local mass transport for both IrCl63- and Fe(CN)64- oxidation at a range of flow rates has been observed at various positions within the impinging jet and the stagnation zone has been thoroughly characterised under a variety of experimental conditions. Agreement has been found between experiment and theory for voltammetric data recorded with the nozzle and UME aligned in the stagnation zone, for a range of viscous solutions examined. By modulating the mass transport rate to the surface of an UME, in the MJE arrangement, by the introduction of a rotating blade between the end of the nozzle and the UME, it was possible to enhance the current sensitivity of the system. Trace level detection, to 2 x 10-7 mol dm-3 IrCl63- solution, was readily facilitated. This type of HMV experiment has utilised two methods to provide the reference signal for phase-sensitive detection of the current signal, involving either a dual-disc electrode or a single UME coupled to an LED detection system. Both HMV methods have been shown to work well.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.
Includes bibliographical references (p. 63-65).
User level debugging of pervasive environments is important as it provides the ability to observe changes that occur in a pervasive environment and fix problems that result from these changes, especially since pervasive environments may from time to time exhibit unexpected behavior. Simple keepalive messages can not always uncover the source of this behavior because systems can be in an incorrect state while continuing to output information or respond to basic queries. The traditional approach to debugging distributed systems is to instrument the entire environment. This does not work when the environments are cobbled together from systems built around different operating systems, programming languages or platforms. With systems from such disparate backgrounds, it is hard to create a stable pervasive environment. We propose to solve this problem by requiring each system and component to provide a health metric that gives an indication of its current status. Our work has shown that, when monitored at a reasonable rate, simple and cheap metrics can reveal the cause of many problems within pervasive environments. The two metrics that will be focused on in this thesis are transmission rate and transmission data analysis. Algorithms for implementing these metrics, within the stated assumptions of pervasive environments, will be explored along with an analysis of these implementations and the results they provided. Furthermore, a system design will be described in which the tools used to analyze the metrics compose an out of bound monitoring system that retains a level of autonomy from the pervasive environment. The described system provides many advantages and additionally operates under the given assumptions regarding the resources available
(cont.) within a pervasive environment.
by Atish Nigam.
M.Eng.

This thesis is focused on a study on the dispersion formulation of the recently appeared ''laminated waveguide". In this framework a new method for the analysis of a wide variety of microwave components like posts, circular junctions or corners in rectangular waveguides is developed. This method can be used to model the posts in the laminated waveguide geometry and this was the main motivation of the present work. The method gives the impedance or admittance matrix of the microwave component by applying discrimination between the localised and accessible modes on the indirect mode matching (IMM) formulation. In all cases the method proved to be fast, very accurate and easy to implement. The application of the IMM technique to the dispersion formulation of the laminated waveguide is undertaken by implementing the Transverse Resonance Method. It is the first time that effort is paid, so that every possible polarisation of both bounded and unbounded modes is considered. In the process a new analytic solution is given for the modelling of the transverse bifurcation. Its significance relies on the the fact that the method of moments is not to be used in the analysis and thus its overall speed is increased. The total procedure is expected to be straightforward and flexible.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Nowadays, despite the technological development experienced by science in general, a fact especially evident by the available powerful computer machines, the analytical and semi-analytical methods to study different space problems are still of great importance in the fields of astrodynamics and celestial mechanics. From the physical understanding of the motion of celestial bodies to the planing and designing of space missions, the use of mathematical models to deal with a very large number of contemporary problems plays a fundamental role in the progress of human knowledge. In this context, the present thesis presents the use of different mathematical techniques to deal with different various and current problems in astrodynamics and celestial mechanics. The studies developed throughout this work are applicable to both areas. The topics studied are the following ones: (1) The development of disturbing potentials using the double-averaging process, in order to be included in the Lagrange planetary which are numerically integrated to study features of orbits around Mercury and the Galilean moon Callisto; (2) The use of different perturbation integrals, techniques to identify and map different perturbations present in a planetary system, with focus on the analysis of systems of Giant planets with their massive moons; (3) The use of the concept of intermediary Hamiltonian and the use of a canonical transformation called elimination of the parallax, both to deal with binary systems in the context of the roto-orbital dynamics, this one as an approach of the fulltwo body problem; (4) An updated analysis of Gauss variational equations to study quasisatellite orbits around the Martian moon Phobos and with analytical predictions made after obtaining linear and averaged equations of motions. Therefore, this thesis intend not only to provide important analysis and results for each specific problem which it deals with along its pages, but also seeks to highlighting the merit and current relevance of different analytical and semi-analytical methods to be used in the fields of astrodynamics and celestial mechanics. Additionally, the author also hopes to offer an outcome of diverse interesting ideas and methods to be explored in future investigations in these research fields
Na atualidade, a despeito do desenvolvimento tecnológico experimentado pela ciência em geral, algo especialmente evidenciado por poderosas máquinas computacionais disponíveis, os métodos analíticos e semianalíticos para o estudo de diferentes problemas espaciais ainda são de grande importância nos campos de astrodinâmica e mecânica celeste. Desde a compreensão física do movimento de corpos celestes até ao planejamento e projeto de missões espaciais, o uso de modelos matemáticos para lidar com um grande número de problemas contemporâneos desempenha um papel fundamental no progresso do conhecimento humano. Neste contexto, a presente tese apresenta o uso de diferentes técnicas matemáticas para lidar com diversos e atuais problemas em astrodinâmica e mecânica celeste. Os estudos desenvolvidos ao longo deste trabalho são aplicáveis à ambas as áreas. Os tópicos estudados são os seguintes: (1) O desenvolvimento de potenciais perturbadores usando o processo de dupla média, de forma a serem incluídos nas equações planetárias de Lagrange que são integradas numericamente para estudar características de órbitas ao redor de Mercúrio e da lua galileana Calisto; (2) A utilização de diferentes integrais de perturbação, técnicas para identificar e mapear diferentes perturbações presentes em um sistema planetário, com foco na análise de sistemas de planetas gigantes com suas luas massivas; (3) A utilização do conceito de hamiltoniana intermediária e o uso de uma transformação canônica chamada eliminação da paralaxe, ambos para lidar com sistemas binários no contexto da dinâmica roto-orbital, essa sendo uma aproximação do problema completo de dois corpos; (3) Uma análise atualizada de equações variacionais de Gauss para o estudo de órbitas quasi-satélite ao redor da lua marciana Fobos e com predições analíticas realizadas após serem obtidas equações de movimento linearizadas e com média. Portanto, esta tese pretende não somente prover importantes análises e resultados para cada problema específico com os quais a mesma lida ao longo de suas páginas, mas também procura destacar o mérito e relevância atual de diferentes métodos analíticos e semianalíticos a serem utilizados nos campos de astrodinâmica e mecânica celeste. Adicionalmente, o autor também espera oferecer um produto de variadas ideias e métodos a serem explorados em futuras investigações nesses campos de pesquisa
2013/26652-4
2015/18881-9

Aquesta tesi ofereix nous coneixements sobre el camp de les tècniques d'especiació basats en mesures de concentracions d'ions lliures. Les dues contribucions principals són: (i) la detecció de nous elements i (ii) la millora de les tècniques. La primera part es centra en la determinació electroquímica de dos elements trivalents com són l'In i el Sb. Darrerament, aquest dos elements han rebut molta atenció, a causa de les seves aplicacions creixents i dels possibles efectes en el medi ambient. Per tant, és necessari tenir tècniques analítiques adequades i fiables, per a tots dos elements. Per a l'anàlisi d'In, es van mesurar concentracions en In total i lliures en solució mitjançant dues tècniques electroanalítiques complementàries, SCP (Stripping chronopotentiometry) i AGNES (Absence of gradients and Nernstian equilibrium stripping), totes dues implementades amb el TMF/RDE (Thin mercury film/rotating disk electrode). Amb ambdues tècniques es van assolir límits de detecció nanomolars. AGNES va ser emprada per a l'estudi de la dissolució de nanopartícules In2O3, donat el seu ampli ús tecnológic. El pH i l'efecte dels lligands làbils en solució afectaven significativament la seva quantificació. També es van estudiar els avantatges d'utilitzar el TMF/RDE davant de l'HMDE (Hanging mercury drop electrode), aconseguint temps experimentals més curts fins i tot quan es determinen concentracions lliures petites. Les mesures presentades d'Sb representen la primera aplicació d'AGNES per detectar una espècie particular d'Sb(III) en una solució aquosa. L'Sb com a ió lliure és pràcticament inexistent, a causa de la seva extensa hidròlisi. Així doncs, la seva detecció es va basar en seguir les concentracions de Sb(OH)3(aq). Dues variants diferents d'AGNES es van emprar per a l'anàlisi d'Sb i van ser comparades. Mitjançant la variant AGNES-Q es van obtenir resultats acceptables, però els temps d'stripping que necessitava eren llargs. D'altra banda, AGNES-SCP resulta ser la tècnica més avantatjosa ja que va demostrar ser més ràpida i reproduïble. Aquesta prometedora metodologia obre camí per fer front a l'especiació d'Sb amb AGNES en altres sistemes i medis. La segona part d'aquesta tesi se centra en millorar l'aplicabilitat i l'eficiència de la tècnica DMT (Donnan membrane technique). Això es va dur a terme estudiant diversos canvis en la metodologia emprada, agrupades de la següent manera: variables experimentals, modificacions instrumentals i composició de l'acceptor. El primer conjunt va millorar l'eficàcia i la robustesa de la tècnica, descartant qualsevol efecte potencial de l'agitació de la mostra (donor), la temperatura del sistema i el mostreig de l'acceptor. Per la seva banda, la modificació instrumental es va basar en l'optimització de la relació superfície-volum, variacions en les dimensions de la cel·la de camp i utilitzar hollow fibres. Aquestes modificacions representen una manera simple i eficaç d'escurçar els temps experimentals. L'últim conjunt d'experiments es va basar en l'ajust de la composició de l'acceptor i es van aportar noves estratègies per superar els principals inconvenients de la tècnica DMT. Emprar concentracions d'electròlit suport més petites a l'acceptor que en la solució donor, van resultar en una reducció significativa dels temps experimentals. També es va veure pel cas contrati, on hi ha una major concentració d'electròlit de suport a l'acceptor que en el donor, és possible mesurar mostres més diluïdes.
Esta tesis ofrece nuevos conocimientos sobre el campo de las técnicas de especiación basados en medidas de concentraciones de iones libres. Las dos contribuciones principales son: (i) la detección de nuevos elementos y (ii) la mejora de las técnicas. La primera parte se centra en la determinación electroquímica de dos elementos trivalentes como son el In y el Sb. Últimamente, estos dos elementos han recibido mucha atención, debido a sus aplicaciones crecientes y los posibles efectos en el medio ambiente. Por lo tanto, es necesario tener técnicas analíticas adecuadas y fiables, para ambos elementos. Para el análisis de In, se midieron concentraciones de In total y libre en solución mediante dos técnicas electroanalíticas complementarias, SCP (Stripping chronopotentiometry) y AGNES (Absence of gradients and Nernstian equilibrium stripping), ambas implementadas con el TMF/RDE (Thin mercury film/rotating disk electrodes). Con ambas técnicas se alcanzaron límites de detección nanomolares. AGNES fue empleada para el estudio de la disolución de nanopartículas In2O3, dado su amplio uso tecnológico. El pH y el efecto de los ligandos lábiles en solución afectaban signicativamente su cuantificación. También se estudiaron las ventajas de utilizar el TMF/RDE ante el HMDE (Hanging mercury drop electrode), consiguiendo tiempos experimentales más cortos incluso cuando se determinan concentraciones libres pequeñas. Las medidas presentadas de Sb representan la primera aplicación de AGNES para detectar una especie particular de Sb(III) en una solución acuosa. El Sb como ion libre es prácticamente inexistente, debido a su extensa hidrólisis. Así pues, su detección se basó en seguir las concentraciones de Sb(OH)3(aq). Dos variantes diferentes de AGNES se emplearon para el análisis de Sb y fueron comparadas. Mediante la variante AGNES-Q se obtuvieron resultados aceptables, pero los tiempos de stripping que necesitaba eran largos. Por otra parte, AGNES-SCP resulta ser la técnica mas ventajosa, ya que demostró ser mas rápida y reproducible. Esta prometedora metodología abre camino para hacer frente a la especiación de Sb con AGNES en otros sistemas y medios. La segunda parte de esta tesis se centra en mejorar la aplicabilidad y la eficiencia de la técnica DMT (Donnan membrane technique). Esto se llevó a cabo estudiando varios cambios en la metodología empleada, agrupadas de la siguiente manera: variables experimentales, modificaciones instrumentales y composición del acceptor. El primer conjunto mejoró la eficacia y la robustez de la técnica, descartando cualquier efecto potencial de la agitación de la muestra (donor), la temperatura del sistema y el muestreo del acceptor. Por su parte, la modificación instrumental se basó en la optimización de la relación superficie-volumen, variaciones en las dimensiones de la celda de campo y la utilización de hollow fibres. Estas modificaciones representan una manera simple y eficaz de acortar los tiempos experimentales. El último conjunto de experimentos se basó en el ajuste de la composición del acceptor y se aportaron nuevas estrategias para superar los principales inconvenientes de la técnica DMT. Utilizar concentraciones de electrolito soporte más pequeñnas en el acceptor que en la solución donor, resultó en una reducción significativa de los tiempos experimentales. También se vio, por el contrario, que cuando hay una mayor concentración de electrolito de soporte en el acceptor que en el donor, es posible medir muestras más diluidas.
This thesis offers new insights for the speciation techniques field, based on the measurement of free ions concentrations. Two main contributions are: (i) the detection of novel different elements for the discipline and (ii) the improvement of the techniques. The first part focuses on the electrochemical determination of two trivalent elements such as In and Sb. Lately, both elements have received attention, because of their increasing applications and possible effects on the environment. So, appropriate and reliable analytical techniques, for both elements, are necessary. For the analysis of In, we measured total and free In concentrations in a solution using two complementary electroanalytical techniques, SCP (Stripping chronopotentiometry) and AGNES (Absence of gradients and Nernstian equilibrium stripping), both implemented with the TMF/RDE (Thin mercury film/rotating disk electrode). We achieved nanomolar limits of detection for both techniques. Also, AGNES was employed to study the dissolution of In2O3 nanoparticles, given its wide technological use. pH and the effect of the labile ligands in solution affected significantly free In quantification. We also studied the advantages of using the TMF/RDE in front of the HMDE (Hanging mercury drop electrode), achieving shorter experimental times even when determining extremely low free In concentrations. Sb measurements represent the first application of AGNES to detect one particular specie of Sb(III) in an aqueous solution. Since Sb as a free ion is practically non-existent, because of the extensive hydrolysis of the element, the detection methodology was based on following Sb(OH)3(aq) concentrations. Two different AGNES variants were studied for Sb analysis and were compared. The variant AGNES-Q yielded acceptable results but needed very long stripping times. On the other hand, a clear advantage was presented by AGNES-SCP, which demonstrated to be faster and more reproducible. This promising methodology opens the way to tackle Sb speciation with AGNES in other systems and media. The second part of this thesis focuses on improving DMT's (Donnan membrane technique) applicability and efficiency. It was performed studying a variety of modifications, based on the following sets of concepts: experimental variables, instrumental modifications, and acceptor composition. The first set improved the efficiency and robustness of the technique, ruling out any potential effect from the sample (donor) stirring, the temperature of the system, and the sampling of the acceptor. Conversely, the instrumental modification is based on optimizing the surface-to-volume ratio, modifying the dimensions of the field cell as well as employing hollow fibres. Such modifications represented to be an effective and simple way to shorten the experimental time. The last set of experiments is based on the tuning of acceptor's composition and it revealed new strategies to overcome significantly major drawbacks of the DMT technique. Lower supporting electrolyte concentrations in the acceptor than in the donor solution presented a significant reduction of the experimental times. On the other hand, higher supporting electrolyte concentrations in the acceptor than in the donor, allows to measure more diluted samples.

Sample preparation is often a bottleneck in systems for chemical analysis. The aim of this work was to investigate and develop new techniques to address some of the shortcomings of current sample preparation methods. The goal has been to provide full automation, on-line coupling to detection systems, short sample preparation times and high-throughput.

A new technique for sample preparation that can be connected on-line to liquid chromatography (LC) and gas chromatography (GC) has been developed. Microextraction in packed syringe (MEPS) is a new solid-phase extraction (SPE) technique that is miniaturized and can be fully automated. In MEPS approximately 1 mg of sorbent material is inserted into a gas tight syringe (100-250 μL) as a plug. Sample preparation takes place on the packed bed. Evaluation of the technique was done by the determination of local anaesthetics in human plasma samples using MEPS on-line with LC and tandem mass spectrometry (MS-MS). MEPS connected to an autosampler was fully automated and clean-up of the samples took one minute. In addition, in the case of plasma samples the same plug of sorbent could be used for about 100 extractions before it was discarded.

A further aim of this work was to increase sample preparation throughput. To do that disposable pipette tips were packed with a plug of porous polymer monoliths as sample adsorbent and were then used in connection with 96-well plates and LC-MS-MS. When roscovitine in human plasma and water samples was used as model substance, a 96-plate was handled in two minutes.

Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007.
Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5919. Adviser: Milos V. Novotny. Title from dissertation home page (viewed May 9, 2008).

Les radicaux peroxyles (HO2 et RO2) sont des espèces clés en chimie atmosphérique. Avec le radical hydroxyl (OH), ils sont impliqués dans les mécanismes d’oxydation conduisant à la formation de polluants secondaires tels que l’ozone et les aérosols organiques. Comparer les mesures ambiantes de ces espèces à très courte durée de vie aux concentrations issues de modèles de boîte permet d’évaluer la robustesse des mécanismes chimiques implémentés dans les modèles atmosphériques. Cependant, ces mesures ambiantes sont très difficiles à réaliser et quelques techniques seulement sont disponibles pour les mesures de terrain.L’objectif principal de ce travail est d’améliorer nos connaissances sur deux de ces techniques : l’Amplification Chimique (CA) et la Fluorescence Induite par Laser des ROx (ROxLIF). La technique CA, simple et bon marché, permet la mesure de la somme HO2+RO2 et constitue une bonne solution pour le terrain. La technique ROxLIF, plus complexe, permet de mesurer distinctement HO2 et la somme des RO2. Dans une première partie, un amplificateur à deux voies d’échantillonnage a été construit à l’IMT Lille Douai (France) et caractérisé pour deux chimies d’amplification :1) au monoxyde de carbone (PERCA, PEroxy Radical Chemical Amplifer) et 2) à l’éthane (ECHAMP, Ethane CHemical AMPlifier). Dans une seconde partie, la technique ROxLIF a été implémentée sur un instrument FAGE (Fluorescent Assay by Gas Expansion) à l’Université d’Indiana (USA). Les deux outils ont ensuite été testés lors de mesures ambiantes. Dans une dernière partie, PERCA et RoxLIF ainsi qu’une troisième technique basée sur la spectrométrie de masse à ionisation chimique ont été comparés lors d’une campagne intensive à la chambre de simulation atmosphérique HELIOS à Orléans (France). Plusieurs expériences ont été menées afin d’évaluer la robustesse des mesures de radicaux peroxyles
Peroxy radicals (HO2 and RO2) are key species in atmospheric chemistry, which together with the hydroxyl radical (OH), are involved in oxidation processes leading to the formation of secondary pollutants such as ozone and organic aerosols. Monitoring these short-lived species during intensive field campaigns and comparing the measured concentrations to box model simulations allow assessing the reliability of chemical mechanisms implemented in atmospheric models. However, ambient measurements of peroxy radicals are still considered challenging and only a few techniques have been used for field measurements.The main objective of this work was to improve our knowledge on two measurement techniques: CA (Chemical Amplification) and ROxLIF (Rox Laser Induced Fluorescence). CA is a chemical technique for measuring the sum of peroxy radicals (HO2+RO2) whose simplicity and low cost makes it attactive for field measurements. ROxLIF is a laser-based technique allowing to speciate HO2 and the sum of RO2. In the first part of this thesis, a two-channel chemical amplifier was built at IMT Lille Douai (France) and characterized using 2 different amplification chemistries (PERCA, PEroxy Radical Chemical Amplifer, and ECHAMP, Ethane CHemical AMPlifier). In a second part, the ROxLIF technique was implemented on an existing FAGE (Fluorescent Assay by Gas Expansion) instrument at Indiana University (United States). Both the CA and ROxLIF were tested for ambient measurements. In a last part, the CA using the PERCA approach, ROxLIF and an additional technique based on chemical ionization mass spectrometry were intercompared at the HELIOS atmospeheric chamber in Orleans (France). Several experiments were conducted to investigate the reliability of peroxy radical measurments

Abstract Information about interactions among metals, hydrogen peroxide and chelating agents is needed to develop environmental technology and the operating efficiency of modern elemental chlorine free and total chlorine free bleaching processes. The work presented here focused on the properties of metal chelates and corrosion of titanium in an alkaline hydrogen peroxide solution. A comparative study between three rapid analysis methods, ICP-AES, XRF and ISE, was performed in pulp matrix and error sources of ISE were investigated in detail. Sensitive and selective GC methods for chelating agents ADA and NTA in water matrices were developed. Decomposition of ADA (percentage of residual 71) was observed already at the hydrogen peroxide anion level of 400 mg/l in which DTPA was more persistent (percentage of residual 94). EDTA was stable even in the hydrogen peroxide anion level of 1200 mg/l, in which its percentage of residual was 94. DTPA, EDTA and ADA were more soluble in the presence of iron and manganese than in the absence of these metals. The chelation of iron appeared to be thermodynamically limited in hydrogen peroxide bleaching conditions. Unalloyed (Grade 2) and alloyed (Grade 5) titanium corroded at the hydrogen peroxide anion level of 200 mg/l. The presence of calcium and silica inhibitors and further iron and manganese enhanced the critical hydrogen peroxide anion levels. Grade 5 was inferior to Grade 2. During rapid uniform corrosion, the potential of unalloyed titanium was under 200 mV (SHE) and lower than that of platinum. Over 90% of manganese and many other metals could be leached into aqueous phase for ICP-AES analysis using chelation or acid hydrolysis. An XRF method for manganese, iron and copper in pulp including little or no sample treatment was developed. Measuring temperature differences and atmospheric carbon dioxide were observed to be notable error sources of the ISE technique.

The problem of two-dimensional acoustic scattering of an incident plane wave by a semi-infinite lattice is solved. The problem is first considered for sound-soft cylinders whose size is small compared to the wavelength of the incident field. In this case the formulation leads to a scalar Wiener--Hopf equation, and this in turn is solved via the discrete Wiener--Hopf technique. We then deal with a more complex case which arises either by imposing Neumann boundary condition on the cylinders' surface or by increasing their radii. This gives rise to a matrix Wiener--Hopf equation, and we present a method of solution that does not require the explicit factorisation of the kernel. In both situations, a complete description of the far field is given and a conservation of energy condition is obtained. For certain sets of parameters (`pass bands'), a portion of the incident energy propagates through the lattice in the form of a Bloch wave. For other parameters (`stop bands' or `band gaps'), no such transmission is possible, and all of the incident field energy is reflected away from the lattice.

Several traditional methods have been used to characterise bacteria, such as biochemical, morphological and molecular tests; however, these methods are time-consuming and not always reliable. Recently, modern analytical techniques have emerged as powerful tools offering high-throughput, reliable and rapid analysis in applications, such as clinical and microbiology studies. A variety of modern analytical techniques have been employed for bacterial characterisation, including matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS), liquid chromatography-mass spectrometry (LC-MS), Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy. This thesis focused on developing a robust MALDI-TOF-MS methodology to generate mass spectra profiles for the discrimination of clinically-significant bacteria. The data generated from MALDI-TOF-MS analysis are significantly influenced by a number of experimental factors, namely instrument settings, sample preparation, the choice of matrix, matrix additives and matrix preparation as well as sample-matrix deposition methods. The need to optimise experimental variables for bacterial analysis using MALDI-TOF-MS was evident despite the increased application of this analytical tool for clinical microbiology. Experimental optimisation revealed that the choice of matrix is the most important element in MALDI-TOF-MS analysis. Based on this study, a number of different matrices were used to obtain more reproducible mass spectra to classify bacterial samples using a rapid and effective approach. Studies in this thesis indicated that sinapinic acid (SA) is the best matrix for the analysis of proteins from intact bacteria, while 6-aza-2-thiothymine (ATT) and 2,5-dihydroxybenzoic acid (DHB) produced promising results for the analysis of lipid extracts from bacteria. Analytical techniques in combination with multivariate analysis, such as principal components analysis (PCA) and principal component-discriminant function analysis (PC-DFA), were used for bacterial discrimination. Classification was initially undertaken using MALDI-TOF-MS analysis, and subsequently FT-IR spectroscopy, Raman spectroscopy and LC-MS were performed to confirm the classification results. Two main types of bacteria were used for this analysis: 34 strains from seven Bacillus and Brevibacillus species and 35 isolates from 12 Enterococcus faecium strains. The findings showed that the four analytical techniques provide clear discrimination between bacteria at these different levels. Classification of different Bacillus and Brevibacillus bacteria using MALDI-TOF-MS analysis of extracted lipids was confirmed by LC-MS data. In addition, MALDI-TOF-MS data based on extracted lipids and intact bacterial cell proteins were very similar. MALD-TOF-MS analysis of intact enterococci cells produced successful classification with 78% correct classification rate (CCR) at the strain level. FT-IR and Raman spectroscopic data produced very similar bacterial classification with CCR of 89% and 69% at the strain level, respectively. However, classification based on MALDI-TOF-MS data and that based on spectroscopic data were slightly different (Procrustes distance of 0.81, p < 0.001, at the species level). Overall, the findings in this thesis indicate the potential of MALDI-TOF-MS as a rapid, robust and reliable method for the classification of bacteria based on different bacterial preparations.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Complex polymers are defined by their distributive properties with respect to molecular weight, chemical composition, functionality and molecular topology. As a result, polymer properties are very frequently determined not only by one of these entities but by the correlation of two or more distributions. Aliphatic polyesters are industrially implemented in high performance coatings, paints and varnishes. However, it is typically difficult to correlate the resulting properties with the synthesis parameters as these polymers vary in reactivity and application properties. Copolyester synthesis by direct polyesterification is often assumed to produce randomized products due to the mechanisms involved in stepwise polymerization. The formation of cyclic products by intramolecular reactions of hydroxyl (OH) and carboxylic (COOH) functional groups, sidereactions such as transesterification, alcoholysis, and ester-ester interchange allow even further randomization, enabling a highly complex system. Therefore, in addition to molecular weight distribution, polyesters exhibit chemical composition, functionality type as well as branching distributions, classifying them as complex polymeric systems. The different methods of polymer chromatography in combination with sophisticated spectrometry techniques are useful tools for enabling the full description of the molecular heterogeneity of these complex polyesters. The present study entails method development of different modes of chromatography and mass spectrometry along with their combination, to facilitate the analysis of the various distributions of two model polyester systems, phthalic and maleic anhydride, respectively, in combination with propylene glycol. Gradient HPLC analysis enabled an oligomeric separation based on chemical composition of the respective anhydride/propylene glycol samples. Its off-line coupling to MALDITOF MS and ESI-QTOF MS revealed the presence of several distributions of varying endgroup functionality type and molecular weight distributions at different intervals throughout the polymerization. In addition, online gradient HPLC x size exclusion chromatography (2D-LC) was conducted to obtain the dual chemical composition-molecular weight (CCD-MWD) distribution. The combination of the different coupling techniques provided the opportunity to a more in-depth analysis of the structure-property relationships.
AFRIKAANSE OPSOMMING: Komplekse polimere word gedefinieer deur hul verdelings eienskappe ten opsigte van molekulêre massa, chemiese samestelling, funksionaliteit en molekulêre topologie. Gevolglik, word hul eienskappe dikwels bepaal deur nie net een van hierdie entiteite nie, maar ‘n korrelasie van twee of meer verdelings. Alifatiese poliësters word industrieel geϊmplimenteer in hoë werkverrigting bestrykings, verwe en politoere, dog is dit tipies moeilik om die uiteinde eienskappe met die verwante sintese parameters te korrelleer, aangesien die polimere varieer in reaktiviteit en toepassingseienskappe. Ko-poliëster sintese vanaf direkte poliësterivering word dikwels aanvaar om willekeurige produkte op te lewer as gevolg van die meganismes wat betrokke is tydens trapgroei polimerisasie. Die produsering van sikliese produkte weens intra-molekulêre reaksies van hidroksiel(OH) en karboksiel (COOH) verwante funksionele groepe, newereaksies soos transverestering, alkoholise en ester-ester verwisseling, het verdere ewekansigmaking tot gevolg wat ‘n hoog gekomplekseerde sisteem tot gevolg het. Benewens die molekulere massa verdeling, vertoon poliësters dus chemiese samestelling, funksionaliteit tipe so wel as vertakkings verdeling wat hul as komplekse polimeer sisteme klassifiseer. Die verskillende metodes van polimeer chromatografie in kombinasie met gesofistikeerde spektrometriese tegnieke dien as nuttige bronne vir die volledige beskrywing wat betref die molekulêre heterogeniteit van komplekse poliesters. Die huidige studie stel metode ontwikkeling van verskillende modus van chromatografie, massa spektrometrie sowel as hul aaneenvoeging bekend, om die die verskillende verdelings van twee model poliester sisteme, ftaal- en maleϊensuuranhidried onderskeidelik in kombinasie met propileenglikol, suksesvol te analiseer. Gradiënt hoë-druk vloeistof chromatografie (HPLC) analise het ‘n oligomeriese skeiding, gebaseer op die chemiese samestelling van die verskeie anhidried /propileenglikol monsters, opgelewer. Die nie-gekoppelde skakeling met matriks-assisteerdelaser/ desorpsie-ionisasie tyd-van-vlug (MALDI-TOF) en elektron-sproei-ionisasie kwadrupool-tyd-van-vlug (ESI-QTOF) massa spektrometrie het die teenwoordigheid van verskeie verdelings van varieërende endgroep funksionaliteit tipe en molekulêre verdelings by verskillende intervalle tydens die polimerisasie aan die lig gebring. Gekoppelde skakeling van gradient HPLC en grootte uitsluitings chromatografie is ook uitgevoer om die tweedelige chemiese samestelling-molekulere massa verdeling te bepaal. Aaneenvoeging van die verskeie skakelings tegnieke het die geleentheid gebied om ‘n deeglike studie van die struktuureienskappe verhoudinge suksesvol uit te voer.

Internal diesel injector deposits (IDIDs) have become a prolific issue in the last decade, increased number of incidences have occurred since the introduction of ultra-low sulfur diesel and biodiesel. The IDIDs have caused concerns for customers such as injector systems misfiring or blocking, increased emissions and fuel consumption. Interest into the origins of the deposits has steadily grown, with identified possible causes including contaminants, degraded additives, or thermal and pressure stresses of the engine. Most examples in previous studies only provide surface analysis of IDIDs, however, the surface only provides a relatively small part of the story. In order to understand how an IDID has formed the history needs to be explained, to do this the lower layers of the IDID need to be analysed. Outcomes of this research include the first example of focused ion beam and secondary ion mass spectrometry being used in combination to analyse IDIDs and clearly shows different chemical layers, demonstrating that these deposits are made up of multiple complex chemistries. Raman spectroscopy can provide graphitic content information for IDIDs giving evidence of formation however, a method to remove fluorescence from carbonaceous structures was first devised and validated in order to allow this to be performed. The jet fuel thermal oxidation test (JFTOT) has been proven to be an effective method of replicating deposits on comparison with IDIDs from failed field engines, and key chemistries have been identified for B20 biodiesel and ultra-low sulfur diesel (ULSD). This work has used existing analytical methods to understand IDIDs and found novel insights that have not been previously observed in the literature.

Some results from applying nuclear and related analytical techniques in medical, environmental and industrial biotechnologies are presented. In the biomedical experiments biomass from the blue-green alga Spirulina platensis (S. platensis) has been used as a matrix for the development of pharmaceutical substances containing such essential trace elements as selenium, chromium and iodine. The feasibility of target-oriented introduction of these elements into S. platensis biocomplexes retaining its protein composition and natural beneficial properties was shown. The negative influence of mercury on growth dynamics of S. platensis was observed. Detoxification of Cr and Hg by Arthrobacter globiformis 151B was demonstrated. Microbial synthesis of technologically important silver nanoparticles by the novel actinomycete strain Streptomyces glaucus 71 MD and S. platensis was characterized by a combined use of scanning electron microscopy (SEM) and epithermal neutron activation analysis (ENAA). When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20683

The dominant theme in Regain is that of death leading to rebirth. This dissertation attempts to explore Giono's narrative techniques within this context. No single chapter will be devoted to a specific technique; instead, the various devices used by the author are discussed as they emerge from the structure of the chapters. Justifying the field of study as defined in the "Introduction", the following three chapters outline the passage of life from death to eventual rebirth. With acknowledgement to Frank Kermode, who writes: "A concord of past, present and future three dreams which, as Augustine said, cross in our minds, as in the present of things past, the present of things present, and the present of things future" ¹, the first three chapters bear his terminology for their headings. Chapter One, "The Present of Things Past", deals with Mameche's loss of her husband and son. Chapter Two, "The Present of Things Present", focuses upon Mameche' s realization of Gaubert's departure, and the decision that she must do something to save the dying village of Aubignane. Chapter Three, "The Present of Things Future", sees Mameche setting out in search of a wife for Panturle, and succeeding. This brings to an end Part One of the novel. Interwoven throughout the chapters are paradigms from Greek mythology, rich in universal symbolism, and the author's belief in man's ability to fuse himself with his surroundings. The conclusion summarizes the findings of this study, attempting to show how an analysis of Giono's narrative technique provides an insight into such a novel as Regain. ¹The Sense of an Ending (London: Oxford University Press, 1966), rpt., 1970, p. 50.

Thesis (Ph. D.)--Ohio State University, 2003.
Document formatted into pages; contains x, 108 p. Includes bibliographical references (p. 102-108). Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Sep. 22.

An advanced Electron Energy Loss Spectrometer has been used to study the formation of 3,3,3-trifluoropropylidyne on Pt (111). This has been compared to the results from the same system using the complementary vibrational spectroscopic technique of Reflection Absorption Infrared Spectroscopy (RAIRS). This study demonstrates the improved resolution of the new spectrometer. The thermal decomposition products, CF3 and CF2 have been detected in the Electron Energy Loss (EEL) spectra. The RAIR spectra of carbon monoxide on Cu (111) have been recorded using synchrotron radiation. An optical accessory has been used to record the RAIR spectra at an incident angle of 20°. The results have been compared to an incident angle of 87°. At 20° no conventional absorption band at 339 cm-l was observed and an anti absorption band at 274 em-l of similar magnitude to that at 87° was seen. This has confirmed the involvement of the parallel electric field in the observation of antiabsorption bands. The EEL spectra of hydrogen and deuterium adsorbed on Pt (111) at 160 K have been recorded. The data has been interpreted using the Nearest Neighbour Central Force Constant (NNCFC) model in terms of 3- fold and 2-fold bridging sites. It is the 2-fold site which offers the more complete assignment of the vibrational bands observed.

A linear aerosol time-of-flight mass spectrometer has been built to analyse carbon nanotubes. An aerodynamic lens system allows an aerosol-particle beam of controlled dimension and divergence to be formed.

Soft contact lens wear has become a common phenomenon in recent times. The contact lens when placed in the eye rapidly undergoes change. A film of biological material builds up on and in the lens matrix. The long term wear characteristics of the lens ultimately depend on this process. With time distinct structures made up of biological material have been found to build up on the lens. A fuller understanding of this process and how it relates to the lens chemistry could lead to contact lenses that are better tolerated by the eye. The tear film is a complex biological fluid, it is this fluid that bathes the lens during wear. It is reasonable to suppose that it is material derived from this source that accumulates on the lens. To understand this phenomenon it was decided to investigate the make up and conformation of the protein species that are found on and in the lens. As inter individual variations in tear fluid composition have been found it is important to be able to study the proteins on a single lens. Many of the analytical techniques used in bio research are not suitable for this study because of the lack of sensitivity. Work with poly acrylamide electrophoresis showed the possibility of analyzing the proteins extracted from a single lens. The development of a biotin avidin electro-blot and an enzyme linked aniibody electro-blot, lead to the high sensitivity detection and identification of the proteins present. The extraction of proteins from a lens is always incomplete. A method that analyses the proteins in situ would be a great advancement. Fourier transform infra red microscopy was developed to a point where a thin section of a contact lens could yield information about the proteins present and their conformation. The three dimensional structure of the gross macroscopic structures termed white spots was investigated using confocal laser microscopy.

Whilst the capabilities of analytical techniques are ever-increasing, individual methods can provide only a limited quantity of information about the composition of a complex mixture. Interrogation of samples by multiple techniques may permit for complementary information to be acquired, and suitable data fusion strategies are required in order to optimally exploit such complementary information. A novel mid-level data fusion strategy has been implemented which uses two-stage genetic programming for feature selection and canonical correlation analysis such that highly discriminatory variables can be related together in a multivariate fashion. The approach offers an intuitive way to visualise variable interaction and their contributions to experimental trends.

In an industrial society it is critical that techniques be developed for the measurement of chemical species in the environment, in humans and as both intended and unintended products of manufacturing. Initially, these techniques were developed around sophisticated instruments and often involved complex procedures. It is obviously advantageous if the cost of analyses can be reduced and the experimental procedures simplified, while still maintaining the quality of the data collected. Furthermore, it is often desirable to have measurements performed rapidly, with on-site measurement sometimes deemed useful or even essential. All of these desirable outcomes may, in some cases, be obtained by miniaturisation. The interest in miniaturisation has led to rapid growth of the field of microfluidics, an area of study which involves using small volumes of liquids, often with detection systems specifically tailored to these reduced volumes. Microfluidic systems must have some way of moving liquids through various stages of chemical or physical processes. One particularly interesting pumping method involves the use of centrifugal force, which eliminates the need for pumps and minimises connections to the platform on which the analysis is done. Up to this point, centrifugal systems have generally been constrained to a limited number of sequential analytical steps as liquid could only flow in the direction demanded by the applied centrifugal force.In this thesis, a variety of liquid manipulation techniques on centrifugal microfluidic platforms were developed and characterised. These techniques were used to miniaturise standard classical analytical methods and implement them on centrifugal microfluidic platforms with the goal of monitoring environmentally important compounds such as aqueous sulfide. A two-phase liquid displacement pumping technique and a pneumatic-centrifugal pumping technique are demonstrated and presented. The developed pneumatic-centrifugal system was used to significantly increase the toolbox of capabilities for centrifugal microfluidic platforms, simultaneously enabling critical microfluidic operations such as valveless liquid transfer, metering, liquid flow switching, agitative micromixing, and liquid recirculation. This technique is based on contactless implementation of pneumatic pressure using compressed air on a continually rotating centrifugal microfluidic platform, thereby enabling complete liquid flow control by combining the effects of pneumatic pressure and centrifugal force.This new type of pneumatically enhanced centrifugal microfluidic platform greatly simplifies the fabrication process by minimising valving requirements, as well as improving efficiency by performing analyses in a highly automated manner. The pneumatic approach was applied to an on-disk calibration and spectrophotometric measurement using the method of standard additions. Similarly, another pneumatically enhanced platform was developed for performing liquid-liquid extractions between an aqueous phase and an organic phase, demonstrating that these centrifugal platforms are not only capable of performing complex multi-step reactions, but also multi-cycle reactions and processes. Finally, an application-specific pneumatically enhanced centrifugal platform was developed for the spectrophotometric determination of aqueous hydrogen sulfide.All of the developed analytical methods only required small sample and reagent volumes, are highly automated and convenient, and have the potential to be performed in a field environment without the need for highly trained personnel.
Dans notre société industrielle, la conception de techniques pour la quantification d'espèces chimiques dans l'environnement, les humains et les dérivés de la production manufacturière est primordiale. Au départ, ces techniques avaient été élaborées à partir d'instruments sophistiqués et se basaient sur des procédures complexes. Il serait donc avantageux de pouvoir réduire les coûts d'analyse et simplifier les procédures expérimentales, tout en maintenant un niveau élevé de la qualité des données recueillies. De plus, il est souvent souhaitable de pouvoir effectuer ces mesures rapidement, et si possible sur le site où l'échantillon à analyser est recueilli. Toutes ces caractéristiques bénéfiques des méthodes analytiques peuvent être obtenues, dans certains cas, à travers la miniaturisation. L'intérêt pour la miniaturisation a mené à une croissance rapide des systèmes microfluidiques, un domaine d'études qui se concentre sur l'utilisation de petits volumes de liquide et des systèmes de détection spécialement adaptés à ces volumes réduits. Tout système microfluidique doit intégrer une méthode de transfert des liquides à travers différentes étapes de traitements chimiques ou physiques. Une méthode de pompage particulièrement intéressante utilise la force centrifuge, ce qui permet d'éliminer l'utilisation de pompes ou connections externes au système où s'effectue l'analyse chimique. Jusqu'à présent, les systèmes employant la force centrifuge ont été limités par le nombre d'étapes analytiques consécutives, le liquide ne pouvant se déplacer que dans une seule direction définie par la force centrifuge appliquée.Pour cette thèse, plusieurs techniques de manipulation des liquides sur un système microfluidique à base de force centrifuge ont été dévelopées et caractérisées. Ces techniques ont été utilisées pour miniaturiser les méthodes analytiques classiques pour ensuite les intégrer à des plateformes microfluidiques à base de force centrifuge, l'objectif final étant la surveillance d'espèces chimiques dans l'environnement. Une technique de pompage par déplacement de deux phases liquides et une technique de pompage pneumatique à base de force centrifuge sont démontrées. La technique pneumatique à base de force centrifuge qui a été développée augmente de façon significative les capacités de la boîte à outils des systèmes microfluidiques à base de force centrifuge. Ce nouveau système permet d'effectuer simultanément des opérations essentielles dans les systèmes microfluidiques telles que le transfert de liquides sans valves, les dosages, la commutation du débit des liquides, les micromélanges par agitation ainsi que la recirculation des liquides. Cette technique se base sur l'application sans contact d'une pression pneumatique en utilisant de l'air comprimé sur un système microfluidique à base de force centrifuge en rotation constante. Ceci permet un contrôle complet du débit des liquides en combinant les effets de la pression pneumatique et de la force centrifuge. Le processus de fabrication de ce nouveau système est grandement simplifié par l'ajout du système pneumatique car cela diminue le nombre de valves à intégrer dans le système. De plus, son efficacité est accrue grâce à la possibilité d'effectuer des analyses de façon automatisée. Cette approche pneumatique a été appliquée à des mesures spectrophotométriques par la méthode des additions connues effectuées directement sur le disque. Dans le même ordre d'idées, un autre système employant la fonction pneumatique a été développé pour effectuer des extractions liquide-liquide entre une phase liquide et une phase organique. Ceci a démontré que la plateforme centrifuge est capable non seulement d'effectuer des réactions chimiques complexes en plusieurs étapes, mais aussi de répéter les cycles de réactions et autres processus.

Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C₆₀/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (V_oc) by 160% and short circuit current (J_sc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

Thesis (Ph. D.)--University of Exeter, 1988.
Appendix A (v. I, leaves 367-388) "presents information relating to William Finschear the elder, a burgess of Edinburgh and possibly scribe of the Dunkeld Partbooks." Vol. II contains editions with commentary of the following works: Robert Fayrfax, Ave Dei Patris filia; Philip van Wilder, Vidi civitatem; van Wilder, Aspice Domine; Robert Carvor [sic], Mass Dum sacrum mysterium; Carvor, Mass Sine nomine a 5; Johannes Lupi, Ad nutum Domini nostrum; Pierre Certon, Regina caeli; Claudin de Sermisy, O Maria stans sub cruce; Robert Johnson, Domine in virtute tua; Patrick Douglas, In convertendo Domini. Publisher's no.: DX 82363. Includes bibliographical references (v. I, leaves 448-456).

Testing VLSI circuits is a complex task that requires enormous amounts of resources. To decrease testing costs, testing issues are considered earlier in the design process. This is known as "design for testability" (DFT). Built-in Self Test (BIST) is one proposed DFT approach. BIST generally consists of incorporating additional circuitry on the chip to generate test patterns and compact the response of the circuit under test (CUT) into a reference signature. Compaction implies an information loss, introducing the possibility that a faulty circuit declares itself as good. Such errors are known as aliasing errors. Several BIST schemes have been proposed, and each have a particular performance in regard to aliasing. However, the schemes are often evaluated and compared with ill-defined measures for which the underlying assumptions are either not stated or understood clearly. Here, a novel classification for the measures of aliasing is proposed. By providing clear definitions of different possible measures, the proposed classification augments the understanding of the aliasing problem.
This dissertation focuses on the popular BIST scheme that consists of applying pseudorandom test patterns to a CUT and compacting the latter's response by a signature analysis register (LFSR). Assessing the quality of such a scheme in regard to fault coverage is crucial. Fault coverage can be established by full fault simulation. However, high costs may preclude this approach. Other techniques, probabilistic in nature, have been proposed, but a lack of computationally feasible techniques for analyzing the aliasing problem under a reasonable model has left them elusive. Here, new and computationally feasible techniques are developed. More specifically, closed-form expressions for the probability of aliasing are derived for a certain type of LFSRs. Upper bounds are derived for LFSRs characterized by primitive polynomials. An iterative technique is developed for computing the exact probability of aliasing for LFSRs characterized by any feedback polynomial, and for any test sequence length. These new techniques enable better assessments of the quality of BIST schemes that use signature analysis for response compaction. In turn, they are useful for making important design decisions, e.g., determining the number of test patterns that should be applied to a CUT to achieve a certain test confidence; alternatively, deciding how long the signature analyzer should be, and what type of feedback it should possess to achieve a certain desired test confidence.
The techniques developed for computing the probability of aliasing in BIST are also useful in the context of coding theory. The iterative technique developed for computing the probability of aliasing may be used as an efficient technique for computing the probability of an undetected error for shortened versions of cyclic codes.

Milk and dairy products are important source of bioactive compounds useful to satisfy the nutritional and physiological needs of any newborns of mammalian species and useful to guarantee adequate growth and development of infants as well as provide a complete nourishment of adults. Physico-chemical, nutritional and organoleptic properties of the main constituents and the “minor” components have a crucial role in the quality of milk and milk products. Although in the past decades dietary milk fat was often regarded as harmful for the human health, recent researches suggest that milk contains specific fatty acids with nutritional and physiological health benefits. For these reasons, a major attention is given to the quantity and quality of total fat intake. In the recent years, as a result of the new concept of multifunctional agriculture and the changing behaviours about diet, consumer demands in favor of high-quality, security and safety dairy products are increased. Moreover, milk proteins and milk-derived bioactive peptides are recognized to have a high nutritive value, several health-promoting functional activities and excellent technological properties. Accordingly, growing interest in the development of functional dairy products and preparation of infant formulae for babies who cannot be breast-fed, has been give in order to meet the specific consumer’s requests. This manuscript presents the main results obtained during my PhD research aimed to evaluate the main bioactive lipids and proteins in milk and dairy products using innovative analytical techniques. The experimental section of this manuscript is divided in two sections where are reported the main results obtained during my research activities on dairy products and human milks in order to characterize their bioactive compounds for functional food applications.

In pharmaceutical R & D, drug stereochemistry, and consequently the rotation of enantiomers, is very important. Because they act as chiral selectors in vivo, biomacromolecules have been extensively used as chiral selectors for the liquid chromatographic (LC) resolution of enantiomers and more latterly have also been employed in the newer separative technique, capillary electrophoresis (CE). However, at the outset of this research programme, this had generally been restricted to common easily accessible biomacromolecules such as plasma-binding proteins. It was clear that it be would be useful therefore to adapt LC and CE in such a way as would allow the use of a much wider range of biomacromolecules. Accordingly the general aim of this study was to develop LC and CE protocols involving biomacromolecules that would give rise to minimum consumption of the biomacromolecule. To study biomacromolecules in free solution CE, a number of experimental variables had to be established for both optimum chiral discrimination and for investigating biomacromolecule-ligand interactions. The typical and widely used biomacromolecule for chiral discrimination, bovine serum albumin (BSA) was used to study the variables of pH from pH 5.4 to 8.4, concentration of BSA form 0 to 60 mM and concentration of organic modifiers in the range 0 – 20 % v/v for chiral selectivity. This involved an investigation into some unusual artefacts such as ghost peaks and stepped baselines, but ultimately the outcome was a successful free solution CE protocol suitable for the rapid evaluation of chiral discrimination of other biomacromolecules. The conditions were: run buffer (30 mM protein, 67 mM phosphate (pH 7.4) – methanol (97.5 : 2.5, v/v)), capillary CElect p150, 40 cm (35 cm to detector) x 50 mm i.d., temperature of ambient or 25 °C and an applied voltage of 10 kV. The ability of other biomacromolecules, such as human serum albumin (HSA), lactoferrin and protamine, to resolve enantiomers was studied using this protocol including looking at the effect of the addition of modifiers to the buffer such as metal ions like manganese and zinc, competing ligands, e.g. warfarin and ibuprofen, and b-cyclodextrin. As well as using CE, miniaturisation of LC was also studied in view of the success of biomacromolecule-affinity chiral LC. Two different, but similar, microbore LC protocols were employed, i.e. using the protein in free solution or as a pseudo stationary phase. For the former, a Lichrosorb DIOL stationary phase, based on hydroxyl groups immobilised on silica, was chosen in order to minimise the adsorption of protein to the stationary phase. Using this protocol it was demonstrated that free solution microbore LC could be easily be carried out, therefore used to evaluate chiral discrimination and that the use of the system to study in vivo interactions was feasible. The creation of a biomacromolecule pseudo stationary phase, as opposed to conventional chiral stationary phases where the protein is permanently bonded to the stationary phases, involves the biomacromolecule being adsorbed within the pores of the stationary phase. In this way the overall biomacromolecule structure should not be grossly distorted. Three stationary phases were evaluated, viz wide-pore Nucleosil silica, Nucleosil C8 and Lichrosorb DIOL, for optimum biomacromolecule loading and minimal biomacromolecule leakage when mobile phase was pumped through the column. The Nucleosil silica with adsorbed BSA proved the most successful, e.g. a of 3.6 and 4.0 for tryptophan and kynurenine respectively, and robust of the stationary phases with respect to demonstrating the chiral discrimination potential for this system. All the miniaturised systems evaluated were successful, to a greater or lesser degree, for the demonstration of chiral selectivity of biomacromolecules. While CE was better for minimisation of the consumption of the biomacromolecule, it was also important that the biomacromolecule LC systems could be operated in reduced dimensions since these systems have perhaps greater potential for exhibiting enantioselectivity and are more appropriate for the ever increasing need for the study of the interaction of ligands with the biomacromolecule in its ‘natural’ form. With the knowledge gained from this research programme it will now be possible to more easily carry out such studies with much smaller amounts of biomacromolecule, and, accordingly be able to work with biomacromolecules which hitherto it has not been possible to study because of limited availability. While some of the protocols have now been superseded by recent developments the system developed still has potential. The use of such small scale systems offers the potential to study chiral selectivity and drug-biomacromolecule binding of rare or expensive biomacromolecules.

The aim of this study was to investigate new methods of analysis which might be applied to forensic toxicology problems including those resulting from pesticides, particularly the quaternary ammonium herbicide group, and from drugs, particularly the benzodiazepine group. In the first part of this study, an efficient method for the determination of quaternary ammonium (QA) compounds (pesticides and drugs) in human whole blood was developed. The second part of this study concerned the development of a novel sorbents for solid phase extraction using molecularly imprinted polymers (MIPs). The approach adopted was initially to synthesise a known MIP using diazepam as template then to prepare novel MIPs using other benzodiazepines and analogues of QA compounds as templates. In the first of these stages, an anti-diazepam MIP was synthesized using methacrylate acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-liner and was then ground and prepared for use as an SPE sorbent by packing it into SPE cartridges. These cartridges were used to clean up extracts of diazepam and other benzodiazepine drugs made from hair samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. The MISPE method was also found to be applicable to the analysis of diazepam metabolites and other benzodiazepine drugs in addition to diazepam itself. The application of the extraction method to post-mortem hair samples yielded results that were in good agreement with ELISA data (from blood samples) and data arising from the analysis of the same blood samples using a validated in-house SPE-LC-MS-MS method. The MISPE procedure was also compared with a conventional SPE method for analysis of benzodiazepines in hair samples. The results from MISPE protocol showed better selectivity, specificity and accuracy toward diazepam (template molecule) and other benzodiazepines that display a similar resemblance to diazepam in terms of molecular structure. The MISPE procedure was found to be simpler and to offer cleaner extracts compared to a conventional SPE method.