The U.S Environmental Protection Agency (USEPA) Airborne Spectral Photometric Environmental Collection Technology (ASPECT) program is designed in part to provide first responders with radiological mapping of potentially hazardous locations. This program utilizes an aircraft fitted with a gamma-ray spectrometer capable of remote detection of radioisotopes. The challenges present in detecting a radioisotope signal remotely are strongly tied to the signal-to-noise ratio of the collected gamma-ray spectra and the specific signal processing and pattern recognition methods used in the data analysis. Depending on the distance from the detector to the radioisotope source, Compton scattering can significantly reduce the analyte signal, and weakened signals pose a significant challenge when attempting to design an effective classifier for detecting radioisotopes of interest. In this research, a basic methodology has been developed for the detection of cesium-137 (¹³⁷Cs) and cobalt-60(⁶⁰Co) utilizing only laboratory collected spectra and backgrounds from the field collected only once. The presented classifier methodology has been proven to provide a fundamental structure for which more advanced algorithms can be developed. Furthermore, this methodology has demonstrated the ability to strongly associate a level of confidence in a detection which allows for intelligent decision making. From this basic methodology, more sensitive and selective algorithms can be designed. The Compton effect has previously been problematic in the development of gamma-ray pattern recognition systems. In this research, a background suppression methodology utilizing linear regression has been implemented to enhance the basic pattern recognition methodology. This background correction strategy has led to significant improvements in the remote detection of radioisotopes and enables the classification of more complex radioisotopes such as europium-152 (¹⁵²Eu). This research demonstrates not only the capabilities of the pattern recognition methodology, but also the flexibility of the procedure. In the remote detection of radioisotopes, false detections and low sensitivity are the key challenges when developing a classifier. While the background corrected methodology was shown to greatly enhance the classifier performance, further advances can be made into the methodology through the use of committee classifiers. Since every classifier utilizes a different dataspace, a standardization procedure has been developed from which the classifier result can be averaged and generate a committee classifier result. This classifier methodology has been demonstrated to further improve the radioisotope classifier performance without sacrificing either sensitivity or selectivity. While the development of targeted radioisotope classifiers is invaluable to the first responder, developing a general gamma-ray anomaly classifier can handle those radioisotopes that have no dedicated classifier. From this objective, a unique anomaly classifier based on the Compton region of the gamma-ray spectrum has been developed and demonstrated to operate in the field. Utilizing all of the strategies and techniques developed for single radioisotope classifiers, the anomaly classifier has been proven to detect background and natural radioactive sources as well as controlled and man-made radioisotope targets. From the developed remote detection classifiers via pattern recognition techniques, robust radiation detection classifiers have been developed. This pattern recognition methodology eschews the need for extensive field data collection for training the algorithms, while also removing the need for on-site calibrations. When used in conjunction with one another, the dedicated radioisotope and anomaly classifiers provide a thorough and rugged remote detection capability to the first responder. The presented methodology also demonstrates that any radioisotope classifier can be generated, implying that this method can be used for the detection of any radioisotope in the field.

abstract: A new challenge on the horizon is to utilize the large amounts of protein found in the atmosphere to identify different organisms from which the protein originated. Included here is work investigating the presence of identifiable patterns of different proteins collected from the air and biological samples for the purposes of remote identification. Protein patterns were generated using high performance liquid chromatography (HPLC). Patterns created could identify high-traffic and low-traffic indoor spaces. Samples were collected from the air using air pumps to draw air through a filter paper trapping particulates, including large amounts of shed protein matter. In complimentary research aerosolized biological samples were collected from various ecosystems throughout Ecuador to explore the relationship between environmental setting and aerosolized protein concentrations. In order to further enhance protein separation and produce more detailed patterns for the identification of individual organisms of interest; a novel separation device was constructed and characterized. The separation device incorporates a longitudinal gradient as well as insulating dielectrophoretic features within a single channel. This design allows for the production of stronger local field gradients along a global gradient allowing particles to enter, initially transported through the channel by electrophoresis and electroosmosis, and to be isolated according to their characteristic physical properties, including charge, polarizability, deformability, surface charge mobility, dielectric features, and local capacitance. Thus, different types of particles are simultaneously separated at different points along the channel distance given small variations of properties. The device has shown the ability to separate analytes over a large dynamic range of size, from 20 nm to 1 μm, roughly the size of proteins to the size of cells. In the study of different sized sulfate capped polystyrene particles were shown to be selectively captured as well as concentrating particles from 103 to 106 times. Qualitative capture and manipulation of β-amyloid fibrils were also shown. The results demonstrate the selective focusing ability of the technique; and it may form the foundation for a versatile tool for separating complex mixtures. Combined this work shows promise for future identification of individual organisms from aerosolized protein as well as for applications in biomedical research. / Dissertation/Thesis / Ph.D. Chemistry 2011

Abstract The subject of this thesis is flow imaging by methods based on the nuclear magnetic resonance (NMR) phenomenon. The thesis consists of three related topics: In the first one the feasibility of measuring velocity maps and distributions inside a microfluidic device by pulsed field gradient (PFG) NMR has been demonstrated. The second topic was to investigate microfluidic gas flow using a combination of a special detection technique and a powerful signal enhancement method. The third topic is related to the unambiguous determination of velocities under challenging experimental conditions and introduces a new, improved velocity imaging sequence. In the first part, well established imaging methods have been used to study water flow inside a micromixer. A surface coil matching the region of interest of the mixer was home built and used in the measurements in order to gain a better signal-to-noise ratio. Velocities inside the mixer have been measured by phase-encoding velocity, with unprecedented spatial resolution. Two dimensional NMR imaging and velocity maps revealed clogging and different manufacturing qualities of the mixers. In addition to the velocity maps, which display an average velocity for spins within one pixel, complete velocity distributions (so called average propagators) were measured. It was found that in the absence of spatial resolution in the third dimension, the propagator data can provide valuable insight to the flow system by revealing overlapping flow passages. The next topic was gas flow inside a microfluidic device. It was investigated by time-of-flight flow imaging. The measurement of the weak gas signal was enabled by the use of two signal enhancement techniques: remote detection NMR and parahydrogen induced polarization (PHIP). The results demonstrate that a very significant signal enhancement can be achieved by this technique. In the future it may enable the investigation of interesting chemical reactions inside microreactors. The third and last topic of the thesis deals with measuring flow by the so called multiecho sequences. When multiecho sequences are used in combination with phase encoding velocity, an error may be introduced: the multiecho sequence may produce a cumulative error to the phase of the magnetization, if it is sensitive to RF pulse imperfections. The problem has been elaborately explained and various solutions discussed, among the newly proposed one. Experimental results demonstrate the performance of the new velocity imaging sequence and show that the new sequence enables the unambiguous determination of velocities even in challenging experimental conditions resulting from inhomogeneous radio frequency fields of the measurement coils.

Abstract Xenon atoms and sulfur hexafluoride (SF6) molecules can be dissolved in liquids and liquid crystals or adsorbed in porous materials. Nuclear magnetic resonance (NMR) spectra of 129Xe or 19F nuclei reveal information about their surroundings. This means that xenon atoms and SF6 molecules can be used as probes to indirectly study materials by NMR spectroscopy. The change in the spectra arises from a NMR interaction called shielding. Especially in the case of xenon, shielding reveals even the slightest changes, for example, in the density of a liquid it is dissolved in. Because a change in temperature leads to a change in the density of the liquid as well, temperature change is observed as a shift of the resonance line in the 129Xe NMR spectrum. This property can be utilized in the accurate determination of the sample temperature. Self-diffusion measurements of the gases provide additional information on a larger scale rather than just the immediate surroundings of atoms or molecules. Various liquid crystals were studied using xenon and SF6 as probes proving their applicability. It is often considered that the signal observed in NMR experiments is very weak and limits the full potential of the method. This is true especially with the samples in gaseous form. The Spin-Exchange Optical Pumping (SEOP) hyperpolarization method solves this problem in the case of xenon. A 129Xe NMR signal can be enhanced by a factor of 104–105 by SEOP and this opens access to techniques that are not otherwise possible. The remote detection technique, which separates the encoding and detection steps of the typical NMR experiment both temporally and spatially, is one of these techniques. The potential of the combination of SEOP and remote detection techniques was shown in studies of thermally modified Pinus Sylvestris.

Using techniques of remote detection, this work aimed to obtain the energy balance in the Basin of Low Jaguaribe, Perimeter irrigated Tabuleiro de Russas and dam Santo Antônio de Russas. Two images of sensor TM of the satellite Landsat 5 obtained together DGI (Department of Generation of Images) of INPE, composed by six bands, (1,2,3,4,5,7) of the spectrum of the visible and a thermal band, (6) dated of 13/08/2007 and 28/09/2008, were used for this. After, I linked the variations of the obtained results, with the indexes of rain observed in four pluviometers, belonging to FUNCEME, entered in the study area. There was not rain registration during the five previous days the image of 2007, already in 2008, three pluviometers registered 14 mm, 15 mm and 3,2 mm.The processing of the images, the Software ERDAS 8.7 was used, being used for the estimate of the energy balance, the method proposed by the algorithm SEBAL (Surface Energy Balancy Algorithm Land). This algorithm calculated: reflectance, vegetation indexes, temperature of the surface, radiation balance, flow of sensitive heat, flow of latent heat among others. For the obtaining of some of those parameters was used surface data obtained in the automatic station of the municipal district of Russas. The medium reflectance, in 2008, was of 0,249. and in 2007, it was of 0,236, being verified a small increase in 2008. The Index of Vegetation of the normalized difference presented average of 0,376 in 2008, and 0,162 in 2007, being verified a strong influence of the rains in that parameter. The radiation balance in 2007, 570 W/m², was higher than 2008, 522 W/m². I concluded that this increase is related with smaller reflectance index and larger incidence of the radiation of short waves in 2007. The flow of sensitive heat in 2007 was of 303 W/m² and, in 2008, it was of 185 W/m², observed that the rains, in 2008, will reduce the flow of sensitive heat. The flow of latent heat presented opposite values to the flow of sensitive heat as expected. In 2007 the obtained average was 162 W/m², and in 2008, it increased due ace rains, for 272 W/m². / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Utilizando técnicas de sensoriamento remoto, o presente trabalho teve como objetivo a obtenção do balanço de energia à superfície na Bacia do Baixo Jaguaribe, no perímetro irrigado Tabuleiro de Russas e no açude Santo Antônio de Russas. Foram utilizadas para isso, duas imagens do sensor TM do satélite Landsat 5 obtidas junto ao DGI (Departamento de Geração de Imagens) do INPE compostas por seis bandas, (1,2,3,4,5,7) do espectro do visível e de uma banda do termal, (6), datadas de 28/09/2007 e 13/08/2008. Após, relacionou-se as variações dos resultados obtidos, com os índices de chuva observados em quatro pluviômetros, pertencentes à FUNCEME, inseridos na área de estudo. Não houve registro de chuva durante os cinco dias anteriores à imagem de 2007. Já em 2008, três pluviômetros registraram chuvas de 14 mm, 15 mm e 3,2 mm. Para o processamento das imagens, usou-se o Software ERDAS 8.7, utilizando-se para a estimativa do balanço de energia, o método proposto pelo algoritmo SEBAL (Surface Energy Balancy Algorithm Land). Através desse algoritmo estimou-se: albedo, índices de vegetação, temperatura da superfície, saldo de radiação, fluxo de calor sensível, fluxo de calor latente, entre outros. Para a obtenção de alguns desses parâmetros utilizou-se dados meteorológicos de superfície, obtidos na estação automática do município de Russas. O albedo médio, em 2008, foi de 0,249, e em 2007, de 0,236, constatandose um pequeno aumento em 2008. O Índice de Vegetação da Diferença Normalizada apresentou média de 0,376 em 2008 e 0,162 em 2007, verificando-se uma forte influência das chuvas nesse parâmetro. O saldo de radiação em 2007, 570 W/m², foi superior ao de 2008, 522 W/m². Concluí-se que, esse aumento está relacionado com menor índice de albedo e maior incidência da radiação de ondas curtas em 2007. O fluxo de calor sensível em 2007 foi de 303 W/m² e, em 2008, de 185 W/m², observando-se, dessa forma, que as chuvas, em 2008, diminuíram significativamente o fluxo de calor sensível. O fluxo de calor latente apresentou valores opostos ao fluxo de calor sensível, como se esperava. Em 2007, a média obtida foi de 162 W/m², e em 2008, aumentou, devido às chuvas, para 272 W/m².

Abstract The subject of this thesis is the characterization of chemical reactions and adsorption by means of remote detection (RD) method of nuclear magnetic resonance (NMR). The thesis consists of three related topics: In the first one, novel RD NMR based methods for characterizing chemical reactions were presented. In the second topic RD NMR methods were used to study the performance of new kind of microfluidic reactors. The third project concentrated on the development of a novel way to quantify the adsorption of flowing gas mixtures in porous materials. Even though all the topics cover quite different areas of research, they have few common nominators: remote detection NMR, microfluidics and method development. Microfluidic devices are of interest for many areas of science (such as molecular biology, disease diagnosis, chemistry) as they offer great promises for future technologies. Small dimensions enable, among many other things, the benefits of small sample volumes, large surface to volume ratio, efficient heat exchange and precise control of flow features and chemical reactions. The efficient evolution of microfluidic processes requires also the development of new innovative ways to characterize the performance of microfluidic devices. In this work, remote detection NMR is utilized for the purpose. RD is a method where the encoding and detection of information are separated physically. In many cases, the encoding and detection are performed with two separate RF coils while a fluid is passing through the studied system. In the first part of the thesis work, we introduced the concept of remote detection exchange (RD-EXSY) NMR spectroscopy. We demonstrated that the RD-EXSY method can provide unique chemical information. Furthermore, the time-of-flight (TOF) information, which is a natural side product of the experimental setup used, can be converted into indirect spatial information, showing the active reaction regions in a microfluidic device. Additionally, we demonstrated that by applying the principles of Hadamard spectroscopy in the encoding of the indirect spectral dimension we were able to produce with high efficiency RD-EXSY TOF images with direct spatial information. This allows even more accurate characterization of the active regions. The second topic concentrates on the development of microfluidc hydrogenation reactors. In the project atomic layer depositon (ALD) method was used for the first time to deposit both catalyst nanoparticles and support material on the surface of wall-coated microreactors. As a model reaction continuous flow propene hydrogenation into propane was studied by means of remote detection NMR. Reaction yield, mass transport phenomena and the activity of the catalyst surface were determined from the RD NMR data. Thirdly we presented a novel method for gas adsorption measurements in porous materials using RD TOF NMR. Traditional adsorption measurements are carried out at static conditions for a single gas component, as multi-component adsorption measurements are challenging and time-consuming. We investigated adsorption of continuously flowing propane and propene gases as well as their mixture in packed beds of mesoporous materials. The unique time-of-flight information obtained using the RD NMR method was utilized in the determination of flow velocity, which was then converted into amount of adsorbed gas.