The construction of a liquid nitrogen-cooled ion mobility spectrometer coupled with time-of-flight mass spectrometry was implemented to demonstrate the ability to discriminate between electronic isomers. Ion mobility allows for the separation of ions based on differing cross-sections-to-charge ratio. This allows for the possible discrimination of species with same mass if the ions differ by cross-section. Time-offlight mass spectrometry was added to mass identify the separated peak for proper identification. A liquid nitrogen-cooled mobility cell was employed for a two-fold purpose. First, the low temperatures increase the peak resolution to aid in resolving the separated ions. This is necessary when isomers may have similar cross-sections. Second, low temperature shortens the mean free path and decreases the neutral buffer gas speeds allowing for more interactions between the ions and the drift gas. Kr2+ study was performed to verify instrument performance. The variable-temperature ion mobility spectrometer was utilized to separate the distonic and conventional ion forms of CH3OH, CH3F, and CH3NH2 and to discriminate between the keto and enol forms of the acetone radical cation. Density functional theory and ab initio calculations were employed to aid in proper identification of separating isomers. Monte Carlo integration tools were also developed to predict ion cross-section and resolution within a buffer gas.

Although advances in microfluidic technology have enabled increasingly sophisticated biosensing and bioassay operations to be performed at the microscale, many of these applications employ such small amounts of charged biomolecules (DNA, proteins, peptides) that they must first be pre-concentrated to a detectable level. Efficient strategies for precisely handling minute quantities of biomolecules in microchannel geometries are critically needed, however it has proven challenging to achieve simultaneous concentration, focusing, and metering capabilities with currentgeneration sample injection technology. Using microfluidic chips incorporating arrays of individually addressable microfabricated electrodes, we demonstrate that DNA can be sequentially concentrated, focused into a narrow zone, metered, and injected into an analysis channel. The technique used in this research transports charged biomolecules between active electrodes upon application of a small potential difference (1 V), and is capable of achieving orders of magnitude concentration increases within a small device footprint. The collected samples are highly focused, with sample zone size and shape defined solely by electrode geometry. In addition to achieving the objectives of the research project, this setup was found to provide added functionality as a label-free biomolecule detection technique due to the formation of light scattering phases of charged biomolecules on top of the capture electrode.

No description available.

This thesis outlines a novel approach to make ill-posed inverse source problem well-posed exploiting inhomogeneous media. More precisely, we use Maxwell fish-eye lens to make scattered field emanating from distinct regions of an object of interest more directive and concentrated onto distinct regions of observation. The object of interest in this thesis is a thin slab placed conformally to the Maxwell fish-eye lens. Focused Green’s function of the background medium results in diagonal dominance of the matrix to be inverted for inverse problem solution. Hence, the problem becomes well-posed. We have studied one-dimensional variation of a very thin dielectric slab of interest having conformal shape to the lens. This method has been tested solving the forward problem using both Mie series and using COMSOL. Most common techniques for solving inverse problem are full non-linear inversion techniques, such as: distorted Born iterative method (DBIM) and contrast source inversion (CSI). DBIM needs to be regularized at every iteration. In some cases, it converges to a solution, and, in some cases, it does not. Diffraction tomography does not utilize regularization. It is a technique under Born approximation. It eliminates ill-posedness, but it works only for small contrast. Our proposed method works for high contrast and also provides well-posedness. In this thesis, our objective is to demonstrate inverse source problem and inverse scattering problem are not inherently ill-posed. They are ill-posed because conventional techniques usually use homogeneous or non-focusing background medium. These mediums do not support separation of scattered field. Utilization of background medium for scattered field separation casts the inverse problem in well-posed form.

This thesis examines a series of near-field antenna arrays used to perform subwavelength focusing and subwavelength imaging outside the extreme near field. For this purpose, slot and dipole arrays have been designed to produce a subwavelength focal spot at a distance of a quarter wavelength from the array. The dipole arrays are then used as scanning probes to produce images with subwavelength resolution based on perturbations in the scattered field. Unlike negative-refractive-index metamaterial superlenses, the imaging resolution is not affected by losses in the array. Furthermore, the arrays are simple to fabricate and are frequency scalable up to Terahertz frequencies and beyond. A near-field analogue to classic antenna-array theory called ``shifted beam theory'' is presented as a design tool. Based on the linear independence of element field patterns in the near field, this theory is very intuitive and provides a simplified way to calculate the element current weights necessary to generate a given target near-field pattern. Two-dimensional near-field subwavelength focusing is demonstrated using a slotted transmission-screen, or ``meta-screen'', under plane-wave incidence. At a distance of a quarter wavelength, the transverse electric field was measured in experiment to have a full-width half-maximum beamwidth of 0.40 by 0.27 wavelengths. This is compared to a single slot transmission-screen which had a beamwidth of 0.60 by 0.58 wavelengths. Broadside and end-fire dipole arrays are used to perform subwavelength imaging in one and two dimensions, respectively. The experimental minimum resolvable separation between two objects at a quarter-wavelength distance was 0.26 wavelengths using the end-fire array probe, as compared to 0.43 wavelengths for a single monopole probe. For an experiment using eight objects scattered over a one-square-wavelength area, however, the array probe imaging resolution remained around 0.25 wavelengths while the baseline monopole probe was no longer able to resolve any of the objects. Experiments were also conducted using objects buried behind a dielectric barrier as well as objects immersed within a dielectric. These results were consistent with the resolution improvements observed in the free-space resolution experiments.

This thesis examines a series of near-field antenna arrays used to perform subwavelength focusing and subwavelength imaging outside the extreme near field. For this purpose, slot and dipole arrays have been designed to produce a subwavelength focal spot at a distance of a quarter wavelength from the array. The dipole arrays are then used as scanning probes to produce images with subwavelength resolution based on perturbations in the scattered field. Unlike negative-refractive-index metamaterial superlenses, the imaging resolution is not affected by losses in the array. Furthermore, the arrays are simple to fabricate and are frequency scalable up to Terahertz frequencies and beyond. A near-field analogue to classic antenna-array theory called ``shifted beam theory'' is presented as a design tool. Based on the linear independence of element field patterns in the near field, this theory is very intuitive and provides a simplified way to calculate the element current weights necessary to generate a given target near-field pattern. Two-dimensional near-field subwavelength focusing is demonstrated using a slotted transmission-screen, or ``meta-screen'', under plane-wave incidence. At a distance of a quarter wavelength, the transverse electric field was measured in experiment to have a full-width half-maximum beamwidth of 0.40 by 0.27 wavelengths. This is compared to a single slot transmission-screen which had a beamwidth of 0.60 by 0.58 wavelengths. Broadside and end-fire dipole arrays are used to perform subwavelength imaging in one and two dimensions, respectively. The experimental minimum resolvable separation between two objects at a quarter-wavelength distance was 0.26 wavelengths using the end-fire array probe, as compared to 0.43 wavelengths for a single monopole probe. For an experiment using eight objects scattered over a one-square-wavelength area, however, the array probe imaging resolution remained around 0.25 wavelengths while the baseline monopole probe was no longer able to resolve any of the objects. Experiments were also conducted using objects buried behind a dielectric barrier as well as objects immersed within a dielectric. These results were consistent with the resolution improvements observed in the free-space resolution experiments.

Proteomics is an increasingly important area of biological research and has gathered much attention over recent years. Major challenges that make a proteomic analysis difficult are sample complexity, diversity and dynamic range. Progress in the area of proteomics relies heavily on new analytical tools for the sensitive, selective, and high-throughput studies of target analytes. It is estimated that there are several hundred thousand proteins in a human cell. In order to be able to analyze such a complex sample, an analytical method must be capable of separating and detecting many different sample peaks. The complexity of such samples indicates that a single separation method will not be able to provide the needed resolution. If two methods that are orthogonal are combined, then the peak capacity of the combined system is the product of the two individual peak capacities. Development of such systems would cater to the current demands of proteomics studies. Matrix assisted laser desorption/ionization (MALDI) mass spectrometry has evolved into a primary analytical tool for proteomics research. MALDI is fast and efficient and has a high tolerance to non-volatile buffers and impurities. The samples for MALDI are typically applied to solid supports after having been subjected to off-line liquid or gel separations. Several methods have been reported involving various chromatographic or electrophoretic separation methods. However, the current methods often require highly sophisticated sample handling systems, which are often expensive and in need of skilled human resources. The current demands of proteomic analyses require fast, efficient and inexpensive methods for separation to fully harness the capability of MALDI mass spectrometry. In this work a microfluidic device has been designed to perform dynamic isoelectric focusing (DIEF) based protein separation with digital sample deposition directly on a MALDI target for offline analysis. DIEF is related to capillary isoelectric focusing which and can facilitate the interface without the loss of the separation resolution. Compared to traditional capillary isoelectric focusing (cIEF) DIEF uses additional high-voltage power supplies to control the pH gradient by manipulating the electric field. The proteins can be focused at a desired sampling position according to their isoelectric point, to be collected for further analysis by MALDI mass spectrometry. DIEF has a peak capacity of over a thousand and offers an ease of interfacing to other techniques making it a preferred separation method for the interface with mass spectrometric techniques such as MALDI. The design of the microfluidic device is based on a digital droplet fractionation. Multiple fractions of the sample solution from DIEF are generated to retain the resolution and to act as an additional separation mode. The microfluidic device is controlled by actuating pneumatic valves built into the device. The DIEF operational parameters were optimized according to the surface functionality and the design of the microfluidic device. A suitable MALDI sample preparation method was found by studying different existing methods. The methods were studied using test proteins prepared in solutions having the additives used in the experiment. A simple mixture of three proteins was used to demonstrate the application of the developed method. The separation between the proteins insulin, hemoglobin and the myoglobin was demonstrated by varying the separation resolution in three experiments.

Made available in DSpace on 2014-10-09T12:29:26Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:38Z (GMT). No. of bitstreams: 1 01140.pdf: 1334428 bytes, checksum: 1fff9b6a35d24191c6e7e1d24917d345 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

Submitted by Murilo Eduardo dos Reis (muriloreis86@gmail.com) on 2018-05-22T18:59:51Z No. of bitstreams: 1 Dissertação.pdf: 887470 bytes, checksum: 62c272ce95724a2dc2d2dd10ab4f0489 (MD5) / Approved for entry into archive by Milena Maria Rodrigues null (milena@fclar.unesp.br) on 2018-05-23T19:26:12Z (GMT) No. of bitstreams: 1 reis_me_me_arafcl.pdf: 887470 bytes, checksum: 62c272ce95724a2dc2d2dd10ab4f0489 (MD5) / Made available in DSpace on 2018-05-23T19:26:12Z (GMT). No. of bitstreams: 1 reis_me_me_arafcl.pdf: 887470 bytes, checksum: 62c272ce95724a2dc2d2dd10ab4f0489 (MD5) Previous issue date: 2018-04-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O tema do trabalho é a caracterização do romance policial de Rubem Fonseca, tendo em vista a importância desse gênero em sua obra. O objetivo é verificar, em três livros do autor, o modo como ele se apropria de recursos clássicos desse tipo de composição, trazendo ou não contribuição para o gênero em pauta. O corpus é composto pelos romances O caso Morel, de 1973, A grande arte, de 1983, e Agosto, de 1990. Para a concretização da proposta, realizamos análise detida de cada livro em particular. A história, as personagens, a narração, a focalização, bem como o espaço e o tempo, serão objeto de exame com o intuito de se estabelecer a maneira como, atuando organicamente ou não, tais elementos constituem romances que são classificados como policiais. Entre tais componentes, no que se refere à história, levantamos e analisamos a menção a um homicídio já realizado, cujo autor deve ser descoberto na sequência da narrativa, e o leitor acompanha as investigações. No que diz respeito às personagens, é examinada a presença de detetives, delegados, policiais, advogados, etc., como também a sua caracterização superficial ou mais profunda. Para que os objetivos sejam atingidos, é fundamental a investigação das figuras do narrador (quem fala) e do focalizador (quem vê). O espaço social e a ambientação construída na obra também serão levados em conta, bem como a representação ou não de determinado período histórico do país. Além dos livros pertencentes ao corpus, há inserções relativas a obras anteriores e posteriores de Rubem Fonseca, pois existem elementos dessas obras mencionados nos objetos de nossa pesquisa, como também de autores que o influenciaram. Para isso, tomamos como apoio teórico textos críticos e analíticos de estudiosos que tratam do romance policial, da obra de Rubem Fonseca e de aspectos da narrativa, tais como Ernest Mandel, Boileau e Narcejac, Sandra Lúcia Reimão, Vera Lúcia de Follain Figueiredo, Alfredo Bosi, Tânia Pellegrini e Gérard Genette. / The theme of the work is the characterization of Rubem Fonseca's detective novel, considering the importance of this genre in his work. The objective is to verify, in three books by the author, the way in which he appropriates classical resources of this type of composition, whether or not making a contribution to the genre in question. The corpus is composed by the novels O caso Morel (1995), A grande arte (1990) and Agosto (1990). For the purpose of the proposal, we carry out a detailed analysis of each book in particular. History, characters, narration, focus, as well as space and time, will be examined in order to establish how, acting organically or not, such elements constitute novels that are classified as criminal. Among such components, as far as history is concerned, we raise and analyze the mention of a homicide already made, whose author must be discovered following the narrative, and the reader accompanies the investigations. With regard to the characters, the presence of detectives, delegates, police officers, lawyers, etc., is examined, as well as their superficial or deeper characterization. In order for the objectives to be achieved, it is fundamental to investigate the figures of the narrator (who speaks) and the focus (who sees). The social space and the atmosphere built in the work will also be taken into account, as well as the representation or not of a certain historical period of the country. In addition to the books belonging to the corpus, there are insertions concerning Rubem Fonseca's previous and later works, because there are elements of these works mentioned in the objects of our research, as well as of authors that influenced him. For this, we take as theoretical support critical and analytical texts of researchers dealing with the police novel, the work of Rubem Fonseca and aspects of the narrative, such as Ernest Mandel, Boileau and Narcejac, Sandra Lúcia Reimão, Vera Lúcia de Follain Figueiredo, Alfredo Bosi, Tânia Pellegrini and Gérard Genette.

Made available in DSpace on 2014-10-09T12:29:26Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:38Z (GMT). No. of bitstreams: 1 01140.pdf: 1334428 bytes, checksum: 1fff9b6a35d24191c6e7e1d24917d345 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP