none

The work presented in this thesis aims at investigating the attachment of lightning flashes to wind turbines. Modern wind turbines are highly exposed to lightning strikes, due to the increase of their height and the rotation of the blades. Upward lightning is the dominant mechanism of lightning strikes to them. Therefore, this study evaluates the initiation of the initial upward leader discharge and the process of lightning attachment of dart leaders taking place prior to the first return stroke in upward flashes. This work extends the self-consistent leader inception and propagation model (SLIM) to evaluate the lightning attachment of dart and dart-stepped leaders to grounded objects. SLIM was originally proposed to evaluate the lightning attachment of stepped leaders. Unlike the well-studied lightning attachment of stepped leaders, upward connecting leaders initiated in response to dart and dart-stepped leaders develop under a significantly faster change of the ambient electric field. Additionally, these connecting leaders could develop in warm air pre-conditioned by the previous strokes in the same flash. An analytical expression to evaluate the charge required to thermalize the connecting leader per unit length is also developed in the extended model. This model is validated through the analysis of three attachment events recorded in rocket-triggered lightning experiments. Good agreement between the predicted properties of the upward leaders and the measurements has been found. The model is utilized to evaluate the different conditions where connecting leaders can develop prior to the return strokes in upward lightning. The extended model of SLIM is also applied to study the interception of lightning dart leaders by upward connecting leaders initiated from wind turbines. The evaluation considers the influence of the return stroke peak current, the blade rotation and wind on the attachment of lightning dart leaders to wind turbines. The probability of lightning strikes to the receptors along the blade and on the nacelle is calculated for upward lightning flashes. It is shown that the lightning attachment of dart leaders is a mechanism that can explain the lightning damages to the inboard region of the blades (more than 10 meters from the tip) and the nacelle of wind turbines. Furthermore, the critical stabilization electric field required to initiate upward lightning from wind turbines is evaluated for both ‘self-initiated’ and ‘other-triggered’ upward flashes. The calculation shows that the stabilization electric field of an operating wind turbine periodically changes due to the rotation of its blades.  The initiation of upward lightning is greatly facilitated by the electric field change produced by nearby lightning events. However, the rate of rise of the electric field only has a weak impact on the stabilization electric field. The evaluation of the stabilization electric field provides essential information needed for the estimation of the incidence of upward lightning to wind turbines. / <p>QC 20161201</p>

Human breast milk is a biofluid produced by a woman’s body during pregnancy. Breast milk contains necessary nutrition to a growing infant as well as xenobiotics--including drugs of abuse-- consumed by the woman which diffuse into the breast milk from the bloodstream. Since breast milk is recommended to be part of all infants’ diets, being able to detect any toxic components--such as drugs--in the matrix is critical. However, despite the ease and noninvasive nature of collection, human breast milk is a difficult matrix to analyze due to its high fat and protein content. Thus far, no literature has been published on the analysis of breast milk through direct analysis in real time mass spectrometry (DART-MS). Adapting DART-MS to detect drugs of abuse in human breast milk will allow for quick and timely identification of drugs present in an individual’s breast milk, as well as aid in research regarding the potential harmful effects of drugs--both licit and illicit--on an infant who is breastfeeding. Forensically, this method could potentially allow toxicologists to use breast milk as a matrix to determine if drugs played a role in a woman’s or breastfed child’s death. Using both C18 biocompatible solid-phase microextraction (BIO-SPME) fibers and QuickStrip™ cards, a DART-MS method was developed to be able to detect drugs of abuse in human breast milk. Four drugs of abuse (cocaine, codeine, morphine, and delta-9-tetrahydrocannabinol (Δ9-THC))--all of which are either commonly abused during the postpartum period or are of particular danger to breastfeeding women--were chosen to be studied. The drugs of abuse were extracted from either whole or pre-filtered human breast milk using either liquid-liquid extraction or C18 BIO-SPME fibers and detected with DART-MS using parameters suggested by IonSense, Incorporation (Inc.). Mass spectral results indicated that macromolecules in whole breast milk did not hinder extraction or detection and that a larger amount of the analytes were ionized/desorbed when using the BIO-SPME fibers. Thus, a BIO-SPME method adopted from IonSense, Inc. utilizing C18 fibers and SPME DART-MS parameters (with temperature and rail time adjustments) can be used to quickly detect cocaine, codeine, morphine, and Δ9-THC in human breast milk, indicating that this method may be used for the detection of other drugs of abuse in breast milk. In addition, BIO-SPME fibers can be used to quantify the concentration of cocaine in breast milk between a range of 50 and 200 nanograms per milliliter as demonstrated by a matrix-matched calibration curve created using various concentrations of cocaine. Despite its benefits, the BIO-SPME and DART method cannot be used on samples containing more than one drug of abuse (based upon the drug concentrations utilized in this study) due to competitive adsorption and competitive ionization, respectively, as not all drugs could be detected when this method was applied to breast milk samples containing numerous drugs.

Since 2011, toxicology labs across the United States have faced an ever-increasing caseload, with backlogs and analytical turn-around times that continue to grow despite efforts to increase sample throughput. Sample preparation is often the more time-consuming, labor-intensive, and error-prone portion of the analytical process. Biocompatible Solid Phase Microextraction (Bio-SPME) is a single-step sample preparation technique that is rapid, simple, and amenable to automation. Direct Analysis in Real Time (DART) is an ambient ionization technique that can be paired with mass spectrometry (MS) to rapidly detect, identify, and quantitate drugs of abuse in urine samples. When these methods are combined, the entire analytical process, from start to finish, can be completed manually in just over 2 minutes per sample. By increasing sample throughput and decreasing human labor, toxicology labs would benefit greatly by adopting such a rapid analytical technique. This project focused on optimization of the Bio-SPME sample preparation process to maximize signal intensity and minimize preparation time per sample. 11-nor-9-carboxy-9-tetrahydrocannabinol (THC-COOH), benzoylecgonine, norfentanyl, and methamphetamine were selected as target analytes for detection and quantitation in specialty matrix urine (SMx urine). To prepare samples, octadecyl (C18) Bio-SPME fibers were subjected to a conditioning and extracting process prior to analysis via DART-MS. It was determined that a 15 minute conditioning period was sufficient to prepare the fibers for extraction. The extraction period was analyte-dependent with ideal analytes adsorbing to the fibers in as little as 15 minutes. Under ideal conditions, the entire sample preparation process was found to take as little as 30 minutes. Multiple Reaction Monitoring (MRM) methods were built for each target analyte and their deuterated analog. For qualitative purposes, two to three transitions were included for each analyte, whereas the quantitative methods included only one transition per analyte. The limit of detection (LOD) for benzoylecgonine and methamphetamine was found to be 50ng/mL in urine. The LOD for norfentanyl was 75ng/mL in urine, and the LOD for THC-COOH was 250ng/mL in urine. Three of the four analytes were successfully quantitated using DART-MS when only a single analyte is present in the sample: benzoylecgonine and methamphetamine can be reliably quantitated between 50ng/mL and 1000ng/mL, while norfentanyl can be quantitated between 75ng/mL and 1000ng/mL. Data collected from the optimized sample preparation and targeted analytical process demonstrates that rapid detection, identification, and quantitation of metabolites from various drug classes are possible via DART-MS.

Wheat (Triticum aestivum L.) is one of the most important food crops, comprising the largest source of daily calorie and protein intake of human beings worldwide. Among the several diseases of wheat, Yellow Rust (YR; caused by Puccinia striiformis Westend. f. sp. tritici) and Leaf Rust (LR; caused by Puccinia triticina Erikss. & Henn.) have always been major production constraints since the domestication of wheat. For the last few decades, scientists have invested large efforts to identify, characterize and utilize Adult Plant Resistance (APR), a.k.a. slow rusting resistance, in wheat germplasm to promote durability of resistance against rust. The objectives of this study were to 1) understand the genetics of APR to YR and/or LR present in two potential wheat lines 'Quaiu 3' and 'TAM 111', and 2) map the putative Quantitative Trait Loci (QTL) associated with YR and LR resistance using DNA-based molecular markers. Two Recombinant Inbred Line (RIL) populations were subjected to YR and LR disease evaluation experiments in multiple years and locations. Visual evaluation of Disease severity (DS) and Infection Type (IT) score in both RIL populations showed that APR to YR and LR were highly heritable quantitative traits with significant correlation among experiments. In spring wheat population, composite interval mapping consistently detected four and three large effect QTL for YR and LR resistance, respectively. Among those QTLs, 1B, 3B and 1D QTL were found to be associated with previously characterized genes Lr46/Yr29, Sr2/Yr30 and Lr42, respectively. However, QTLs QYr.tam-3D and QYr.tam-2D were potentially novel. The largest YR QTL QYr.tam-2D was located on long arm of chromosome 2D explaining about 48 to 61% of the total phenotypic variation. Similarly, in winter wheat population, apart from three environment-specific QTL on chromosomes 1A, 2A and 7D, the QTL on chromosome 2B (QYr.tam-2B) was found to express consistently in multiple environments explaining about 23 to 63% of total phenotypic variation. This study has further elucidated the inheritance mechanism of APR to YR and LR present in two different wheat lines, Quaiu 3 and TAM 111, and resulted in the successful mapping and characterization of the genetic loci associated with corresponding disease resistance traits. These findings should be very useful to isolate the novel APR genes and/or directly use in wheat breeding programs to enhance durable rust resistance in diverse wheat germplasm and cultivars in the future.

Many plant species around the world are known to contain various psychoactive compounds. Due to their effects when consumed, many of these plants are used as a part of religious and ritualistic practices in many different cultures. As with any psychoactive compounds, these plants have the potential to be used in a recreational manner. In the United States, plant based drugs of abuse, such as marijuana, have become commonly abused substances. Although marijuana is currently regulated by the federal government, many of the plant materials containing potential drugs of abuse are not, and can be purchased legally from various online sources. The goals of this research were to develop methods for the analysis of a wide variety of plant based drugs of abuse by Direct Analysis in Real Time-Mass Spectrometry (DART-MS) and to apply the methods in an effort to differentiate between multiple strains of a single seed species. DART is an ambient ionization technique that allows for rapid analysis of samples while eliminating the need for sample preparation considerations for many applications. Analytes of interest can be detected within the complex plant matrix of ground up seeds, with no need for further extraction or isolation of the analytes. For this study, fourteen different seed samples, including twelve different species, reported to have psychoactive effects on the user were obtained and analyzed. Physical examination was performed, in which average measurements were obtained to describe the length, width, thickness, and mass of each seed species, followed by analytical analysis by DART-MS. The seeds were prepared for analysis by DART-MS by grinding to expose the middle of the seed containing the analytes of interest, and embedding the powder onto QuickStrip(TM) cards (IonSense, Inc.). To optimize the method for analysis, three different DART carrier gas temperatures (250°C, 300°C, and 350°C) were investigated for each seed sample by considering the signal to noise ratio, ion abundance, and presence of the analyte of interest at each source temperature using a single quadrupole mass spectrometer. The analytes detected were then subjected to MS(n) fragmentation in a quadrupole ion trap to confirm the identity of the analytes being detected. Fragmentation patterns were then compared to fragmentation patterns reported in the literature through methods such as chemical ionization, atmospheric pressure chemical ionization, and electrospray ionization. Thirteen of the fourteen seed samples were known to contain compounds with psychoactive properties. One of the species contained no known hallucinogenic compounds, however it was reported to have psychoactive effects when ingested or smoked. Protocols were developed for each sample and the identification of the analytes of interest was successful in twelve of the fourteen samples. DART-MS is a powerful technique for the detection and identification of a variety of plant based drugs of abuse, including tetrahydrocannabinol, lysergic acid amide, and numerous others. The ability to rapidly analyze a large number of samples makes DART-MS a technique with great potential in forensic laboratory settings, such as forensic drug analysis, where case backlog is often an area of concern. The majority of the samples explored in this study are not considered common substances of abuse. However, as their abuse is becoming more common, the high throughput nature of the analytical methods and techniques discussed will become increasingly important.

Comprendre le vieillissement des caoutchoucs afin de le ralentir est un challenge industriel. Pour répondre à cette problématique, la caractérisation du matériau à chaque étape de sa préparation est primordiale. En effet la vulcanisation au soufre est largement utilisée dans l’industrie alors que les mécanismes réactionnels et la structure des matériaux formés restent encore hypothétiques et controversés. La connaissance de ces mécanismes permettrait une amélioration de leur durée de vie. Pour cela nous avons utilisé des techniques innovantes comme l’Analyse Directe en Temps Réel couplée à la spectrométrie de masse (DART-MS) et la Résonance Paramagnétique Electronique (RPE). Une analyse par spectroscopie RPE et DART-MS est effectuée sur chaque additif et mélange (gomme et additifs) à différentes étapes de leur préparation (brut, cru et vulcanisé) pour constituer une base de données. Le cœur de la thèse est l’étude menée par RPE sur la réaction de vulcanisation et sur le vieillissement accéléré des matériaux afin d’apporter des éléments de réponse sur les mécanismes radicalaires proposés dans la littérature. La vulcanisation est étudiée en comparant l’étude ex-situ consistant à analyser le matériau ayant subi la vulcanisation au sein du rhéomètre et l’étude in situ qui consiste à mimer cette réaction au sein du spectromètre RPE pour une étude en temps réelle. Les analyses par RPE montrent la présence d’espèces paramagnétiques de différentes natures (organique et métallique) évoluant au cours de la réaction de vulcanisation et de vieillissement. La spectroscopie RPE montre clairement son intérêt dans l’étude de la réaction de vulcanisation et le suivi du vieillissement. / Understanding the rubber materials’ aging is a challenge in the world of industry. To respond at this problematic, the characterization of the material at each stage of its preparation is essential. Actually, sulfur vulcanization is often used in industry while the reaction’s mechanisms and the structure of the materials formed are still hypothetical and controversial. Knowledge of these mechanisms would improve the life of rubbers. For this we have used innovative techniques such as Direct Analysis at Real-Time coupled with Mass Spectrometry (DART-MS) and Electronic Paramagnetic Resonance (EPR). Spectroscopic analysis by EPR and DART-MS is performed on each additive and mixture (rubber and additives) at different stages of their preparation (raw, uncured and vulcanized) to make a database. The center of the thesis is the study conducted by EPR on the vulcanization reaction and the accelerated aging of materials to provide response’s elements on the radical mechanisms proposed in the literature. Vulcanization is studied by comparing the ex-situ study which the material is vulcanized in the rheometer and the in-situ study which mimicking the vulcanization reaction in the EPR spectrometer for a real-time study. EPR analyzes show the presence of different paramagnetic species (organic and metallic) evolving during the vulcanization and aging reaction. EPR spectroscopy shows clearly its interest in the study of the vulcanization reaction and in the aging.

År 2010 lanserades applikationen Instagram och har öppnat upp dörrarna till en ny personligare kommunikationsstrategi för företag. Den mycket visuella och snabba modebranschen är en av de industrier som dominerar med sin närvaro på Instagram. Denna studie ämnar skapa förståelse kring hur företag inom modebranschen använder Instagram som en kommunikationskanal, samt vilken påverkan användningen av Instagram har på företaget. Det teoretiska ramverk som ligger till grund för studien är samvärdeskapande som sker genom interaktion av fyra centrala byggstenar – dialog, tillgång, riskbedömning, och transparens. Författaren har utfört tre kvalitativa telefonintervjuer med företag inom olika delar av modebranschen. Författaren kom fram till att Instagram är en användbar kommunikationskanal som möjliggör att företag kan sprida sitt varumärke, skapa hållbara relationer med kunderna, och öppnar upp för en dialog mellan företag och konsument. Instagram hjälper företaget med produktion, service och marknadsföring. De aktiviteter de använder sig av är tävlingar, hashtags citat, igenkänningsfaktorer, inspirationsbilder, miljöbilder och samarbeten med bloggare.

Organic contamination on spaceflight hardware is an ongoing concern for spaceflight safety. In addition, for the goal of analyzing for possible evidence of extra-terrestrial life, it is necessary to consider the presence of terrestrial contamination. This paper will introduce and evaluate a new method using a direct analysis real time (DART) ionization source paired with a high resolution time of flight mass spectrometer (TOFMS) for the determination of organic contamination involved in spaceflight hardware and ground support materials. This novel analytical technique has significant advantages over current methodologies. Materials analyzed in this study were historically considered as probable contaminants in spaceflight related substrates. A user determined library was generated due to the non-traditional mass spectra generated by the DART. Continual improvement of analytical methods for the detection of trace levels of contaminants in potential drinking water sources is of extreme importance to both regulatory communities and concerned citizens. This paper will evaluate a novel analytical method using stir bar sorbtive (SBSE) extraction techniques combined with analysis with a DART TOFMS. Compounds of interest will include several representative pharmaceutical contaminants of emerging concern listed in EPA method 1694. Optimal SBSE and DART experimental parameters will be investigated along with accuracy, precision, limits of detection and calibration linearity.

Radiative transfer models (RTM) have been successfully used to simulate the effect of forest structural and biochemical characteristics, such as tree sizes and shapes, leaf area index (LAI), leaf angle distribution (LAD), on the canopy radiative budget. One particular use of RTM is the analysis of the reflected light by the canopy, which can be measured by remote sensing techniques. RTM allows a physically based interpretation of the reflectance quantity measured by satellite and can help disentangling the multiple source of variation of the reflectance signal. The DART model - Discrete Anisotropic Radiative Transfer - is one of the most complex three-dimensional RTM, since it uses an accurate mathematical approach of physical processes and a great realism of the landscapes under simulation. Its main simulation outputs are the reflectance of the scene (e.g. a forest stand) at particular spectral wavelength from bottom and top of the atmosphere, the simulation of satellite images, and the simulation of localized radiative budget. Despite the DART potential in analyzing biophysical parameters from remote sensing data, few studies report its application in forest plantations in Brazil, which can have a large number of important field measurements to parameterize the model. The main objective of this project is to evaluate if the DART RTM can help understand the satellite-measured canopy reflectance of Eucalyptus plantations and in particular if DART RTM can improve LAI estimation rather than use only empirical models, as spectral vegetation indices. DART model was parameterized using extensive in situ data obtained from a clonal test, part of the EucFlux project. The specific objectives were: i) parameterize the DART model at different growth stages and for different clonal materials of Eucalyptus plantations and compare simulated reflectance with high resolution satellite images acquired on the same site; ii) analyze the relationship between the Leaf Area Index (LAI) and Spectral Vegetation Indices (SVI) based on empirical relationships, and then use the DART model; iii) analyze the advantage and drawbacks of using a generic relationship or a clone-specific relationship between LAI and SVI, and find other criteria for grouping the genotypes in the same. In Chapter 2, we demonstrated the good performance of DART to simulate canopy reflectance of Eucalyptus forest plantations. The simulated reflectance was similar to those measured by very high resolution images from satellite, despite some discrepancies found in the near infrared region. Then, in Chapter 3, we showed that empirical relationships between LAI and SVI were able to give a reasonable precision for generic relationships; however, genotype-scale relationships gave even better results. The same methodology applied on a DART simulated dataset lead to the same conclusions. An intermediate possibility of grouping the genotypes regarding their litter or leaf optical properties gave intermediate performance. We finally concluded about the superiority of NDVI to estimate LAI using a genotype-specific calibration. Overall, DART simulated datasets created in this work enable to calibrate different LAI -SVI relationships in terms of genotypes, sensors and acquisition characteristics. / Modelos de transferência de radiação (MTR) têm sido utilizados com sucesso para simular o efeito das características estruturais e bioquímicas florestais, como tamanhos de árvores e formas, índice de área foliar (IAF), distribuição angular das folhas (DAF) e sobre o balanço de radiação. Um uso particular do MTR é a análise da radiação refletida pela copa, o que pode ser medido através de técnicas de sensoriamento remoto. O MTR pode permitir a interpretação física da quantidade de reflectância medido por satélite, e pode ajudar a diferenciar as múltiplas fontes de variação do sinal de reflectância. O modelo DART - Discrete Anisotropic Radiative Transfer - é um dos modelos tridimensionais de transferência de radiação mais complexos, uma vez que utiliza uma abordagem matemática precisa e um grande realismo na simulação das paisagens. Seus principais resultados de simulação são a reflectância da cena (por exemplo, um povoamento florestal) em determinado comprimento de onda espectral em relação ao topo e à base da atmosfera, a simulação de imagens de satélite e a simulação do balanço de radiação. Apesar do potencial do DART na análise de parâmetros biofísicos de paisagens florestais a partir de dados de sensoriamento remoto, existem poucos estudos sobre sua aplicação em povoamentos florestais no Brasil; que podem dispor de um elevado número de medições de campo importantes para a parametrização do modelo. O principal objetivo deste estudo foi avaliar se o DART pode ajudar a compreender o comportamento da reflectância do dossel das plantações de eucalipto oriunda de dados de imagens de satélite e, em particular, se DART pode melhorar a estimativa do IAF ao invés do uso somente de modelos empíricos como índices espectrais da vegetação. O DART foi parametrizado com extensos dados de campo adquiridos em um experimento com testes clonais do Projeto Eucflux. Os objetivos específicos foram: i) parametrizar o modelo DART em diferentes idades e com diferentes materiais genéticos de plantações de eucalipto e comparar a refletância simulada com imagens de satélite de alta resolução adquiridas no mesmo local; ii) analisar a relação entre o Índice de Área Foliar (IAF) e Índices Espectrais de Vegetação (IEV\'s) com base em relações empíricas, e, em seguida, usando o modelo DART; iii) analisar as vantagens e as limitações do uso de uma relação genérica ou uma relação específica do genótipo entre IAF e IV e encontrar outros critérios para agrupar os genótipos. No Capítulo 2 foi demonstrado bom desempenho do DART para simular a reflectância do dossel das florestas plantadas de eucalipto. As refletâncias simuladas foram semelhantes com as obtidas pelas imagens de satélite de alta resolução, apesar de algumas discrepâncias encontradas na região do infravermelho próximo. No Capítulo 3, foi mostrado que as relações empíricas entre os IEV\'s e os IAF\'s foram capazes de estimar com razoável precisão para as relações genéricas dos plantios. Contudo, as estimativas por genótipo deram resultados superiores. A mesma metodologia foi aplicada em um conjunto de dados simulados pelo DART com as mesmas conclusões. Uma possibilidade intermediária de agrupar os genótipos foi em função das propriedades ópticas da serapilheira ou das folhas, com desempenhos intermediários. Nós concluímos sobre a superioridade do NDVI para estimar o LAI usando uma calibração específica para cada genótipo. Em termos mais gerais, os dados simulados com o modelo DART utilizados neste trabalho permitiram calibrar diferentes relações IAF-IEV em função dos genótipos, sensores e características de aquisição.