Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A Física das Radiações é um ramo da Física que está presente em diversas áreas de estudo e se relaciona ao conceito de espectrometria. Dentre as inúmeras técnicas espectrométricas existentes, destaca-se a espectrometria por fluorescência de raios X. Esta também possui uma gama de variações da qual pode-se dar ênfase a um determinado subconjunto de técnicas. A produção de fluorescência de raios X permite (em certos casos) a análise das propriedades físico-químicas de uma amostra específica, possibilitando a determinação de sua constituiçõa química e abrindo um leque de aplicações. Porém, o estudo experimental pode exigir uma grande carga de trabalho, tanto em termos do aparato físico quanto em relação conhecimento técnico. Assim, a técnica de simulação entra em cena como um caminho viável, entre a teoria e a experimentação. Através do método de Monte Carlo, que se utiliza da manipulação de números aleatórios, a simulação se mostra como uma espécie de alternativa ao trabalho experimental.Ela desenvolve este papel por meio de um processo de modelagem, dentro de um ambiente seguro e livre de riscos. E ainda pode contar com a computação de alto desempenho, de forma a otimizar todo o trabalho por meio da arquitetura distribuída. O objetivo central deste trabalho é a elaboração de um simulador computacional para análise e estudo de sistemas de fluorescência de raios X desenvolvido numa plataforma de computação distribuída de forma nativa com o intuito de gerar dados otimizados. Como resultados deste trabalho, mostra-se a viabilidade da construção do simulador através da linguagem CHARM++, uma linguagem baseada em C++ que incorpora rotinas para processamento distribuído, o valor da metodologia para a modelagem de sistemas e a aplicação desta na construção de um simulador para espectrometria por fluorescência de raios X. O simulador foi construído com a capacidade de reproduzir uma fonte de radiação eletromagnética, amostras complexas e um conjunto de detectores. A modelagem dos detectores incorpora a capacidade de geração de imagens baseadas nas contagens registradas. Para validação do simulador, comparou-se os resultados espectrométricos com os resultados gerados por outro simulador já validado: o MCNP. / Radiation Physics is a branch of Physics that is present in various studying areas and relates to the concept of spectrometry. Among the numerous existing spectrometry techniques, there is the X-ray fluorescence spectrometry. It also has a range of variations which can emphasize a particular subset of techniques. The production of X-ray fluorescence enables (in some cases) the analysis of physical and chemical properties of a given sample, allowing the determination of its chemical constitution and also a range of applications. However, the experimental analysis may require a large workload, both in terms of physical apparatus and in relation to technical knowledge. Thus, the simulation comes into play as a viable path between theory and experiment. Through the Monte Carlo method, which uses the manipulation of random numbers, the simulation is a kind of alternative to the experimental analysis. It develops this role by a modeling process, within a secure environment and risk free. And it can count on high performance computing in order to optimize all the work through the distributed architecture. The aim of this paper is the development of a computational simulator for analysis and studying of X-ray fluorescence systems developed on a communication platform distributed natively, in order to generate optimal data. As results, has been proved the viability of the simulator implementation through the CHARM++ language, a language based on C++ which incorporate procedures to distributed processing, the value of the methodology to system modelling e its application to build a simulator for X-ray fluorescence spectrometry. The simulator was built with the ability to reproduce a eletromagnetic radiation source, complex samples and a set of detectors. The modelling of the detectors embody the ability to yield images based on recorded counts. To validate the simulator, the results were compared with the results provided by other known simulator: MCNP.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A Física das Radiações é um ramo da Física que está presente em diversas áreas de estudo e se relaciona ao conceito de espectrometria. Dentre as inúmeras técnicas espectrométricas existentes, destaca-se a espectrometria por fluorescência de raios X. Esta também possui uma gama de variações da qual pode-se dar ênfase a um determinado subconjunto de técnicas. A produção de fluorescência de raios X permite (em certos casos) a análise das propriedades físico-químicas de uma amostra específica, possibilitando a determinação de sua constituiçõa química e abrindo um leque de aplicações. Porém, o estudo experimental pode exigir uma grande carga de trabalho, tanto em termos do aparato físico quanto em relação conhecimento técnico. Assim, a técnica de simulação entra em cena como um caminho viável, entre a teoria e a experimentação. Através do método de Monte Carlo, que se utiliza da manipulação de números aleatórios, a simulação se mostra como uma espécie de alternativa ao trabalho experimental.Ela desenvolve este papel por meio de um processo de modelagem, dentro de um ambiente seguro e livre de riscos. E ainda pode contar com a computação de alto desempenho, de forma a otimizar todo o trabalho por meio da arquitetura distribuída. O objetivo central deste trabalho é a elaboração de um simulador computacional para análise e estudo de sistemas de fluorescência de raios X desenvolvido numa plataforma de computação distribuída de forma nativa com o intuito de gerar dados otimizados. Como resultados deste trabalho, mostra-se a viabilidade da construção do simulador através da linguagem CHARM++, uma linguagem baseada em C++ que incorpora rotinas para processamento distribuído, o valor da metodologia para a modelagem de sistemas e a aplicação desta na construção de um simulador para espectrometria por fluorescência de raios X. O simulador foi construído com a capacidade de reproduzir uma fonte de radiação eletromagnética, amostras complexas e um conjunto de detectores. A modelagem dos detectores incorpora a capacidade de geração de imagens baseadas nas contagens registradas. Para validação do simulador, comparou-se os resultados espectrométricos com os resultados gerados por outro simulador já validado: o MCNP. / Radiation Physics is a branch of Physics that is present in various studying areas and relates to the concept of spectrometry. Among the numerous existing spectrometry techniques, there is the X-ray fluorescence spectrometry. It also has a range of variations which can emphasize a particular subset of techniques. The production of X-ray fluorescence enables (in some cases) the analysis of physical and chemical properties of a given sample, allowing the determination of its chemical constitution and also a range of applications. However, the experimental analysis may require a large workload, both in terms of physical apparatus and in relation to technical knowledge. Thus, the simulation comes into play as a viable path between theory and experiment. Through the Monte Carlo method, which uses the manipulation of random numbers, the simulation is a kind of alternative to the experimental analysis. It develops this role by a modeling process, within a secure environment and risk free. And it can count on high performance computing in order to optimize all the work through the distributed architecture. The aim of this paper is the development of a computational simulator for analysis and studying of X-ray fluorescence systems developed on a communication platform distributed natively, in order to generate optimal data. As results, has been proved the viability of the simulator implementation through the CHARM++ language, a language based on C++ which incorporate procedures to distributed processing, the value of the methodology to system modelling e its application to build a simulator for X-ray fluorescence spectrometry. The simulator was built with the ability to reproduce a eletromagnetic radiation source, complex samples and a set of detectors. The modelling of the detectors embody the ability to yield images based on recorded counts. To validate the simulator, the results were compared with the results provided by other known simulator: MCNP.

Há, em ciência do solo, muita informação sobre a estabilidade de hematita e goethita pedogênicas. Entretanto, observa-se uma escassez de informação a respeito da estabilidade da hematita presente em arenitos vermelhos (litogênica). Neste estudo, buscou-se investigar esses dois tipos de hematita quanto à estabilidade ante a dissolução por um agente redutor. Utilizaram-se amostras de rochas areníticas de quatro formações e quatro amostras de Latossolo com caráter férrico derivadas de basalto de diferentes regiões do Brasil. As amostras de rochas areníticas foram moídas separando-se as frações silte + argila para análises mineralógicas. Inicialmente, foi feita a concentração dos óxidos de ferro para o preparo das lâminas, tendo em vista as análises mineralógicas por difração de raios x. Em seguida, foram realizadas quatro extrações sucessivas do ferro mediante dissolução por ação do redutor ditionito citrato bicarbonato de sódio (DCB), realizada na terra fina seca ao ar (TFSA). Paralelamente, procedeu-se à determinação do ferro total (Fet) pelo método do ataque sulfúrico e pela espectrometria de fluorescência de raios x. Os resultados indicam que a melhor definição dos picos de raios x para a hematita litogênica é uma característica que revela melhor cristalinidade e consequente maior resistência à redução (solubilização pelo DCB80) do que aquelas observadas na hematita pedogênica. Nos difratogramas de raios x, observou-se muito pouca variação na posição de reflexões da hematita nos dois ambientes, indicando proximidade estrutural. Os resultados obtidos pela espectrometria de fluorescência de raios x revelaram ser essa uma técnica auxiliar importante no estudo mineralógico. / Much information is available in soil science on the stability of pedogenic hematite and goethite, but not on the stability of litogenic hematite present in red sandstones. This study investigates the stability of these two types of hematite in the face of dissolution by a reducing agent. The study included sandstone rocks from four formations and four samples of ferric, basalt-derived Latosol from different regions in Brazil. The sandstone samples were ground and had their silt + clay fractions separated for mineralogical analysis. Initially, iron oxides were concentrated for slide preparation by using X-ray diffraction for mineralogical analyses. Then, four successive iron extractions were carried out through dissolution by using reducing agent sodium dithionite-citrate- bicarbonate (DCB) on thin air-dried earth. In addition, total iron (Fet) was measured by using sulfuric attack and X-ray fluorescence spectrometry. The results indicate that the best definition of X-ray peaks for lithogenic hematite is a characteristic that reveals better crystallinity and consequently greater resistance to reduction (solubilization by DCB80) than those observed in pedogenic hematite. In the X-ray diffractograms, very little variation was observed in the position of hematite reflections in both environments, indicating structural proximity. The results obtained by X-ray fluorescence spectrometry proved to be an important auxiliary technique in the mineralogical study. / Dissertação (Mestrado)

Preliminary results of research focused on the applications of DC diaphragm discharge in water solutions containing humic substances are presented in this diploma thesis. Electrical discharges in water produce various reactive species such as radicals (•OH, •O, •H), ions and molecules (H2O2, O3). These species have high oxidation potential and thus they easily react with order species and molecules. Such reactions could lead, for example, to destruction of organic pollutants dissolved in water. This work studies this effect on humic matters that can be contained in water coming from floods. Diaphragm discharge investigated by this work was created in the reactor using konstant DC high voltage up to 2 kV that gave the total input power from 100 to 200 W. Breakdown and discharge ignition started in the pin-hole in the dielectric barrier separating two electrode spaces (anode and cathode space). Presented work investigates decomposition of humic substances by the electric discharge in the dependence of solution properties and discharge conditions. Parameters such as initial solution conductivity, electrolyte kind or input power have been investigated. Moreover, substantial effect of pH on humic acid decomposition has been observed. Refraktometry and absorption spectroscopy in UV-VIS region together with fluorescence spectroscopy has been used for the detection of changes in humic solutions.

The master thesis deals with comparison of atomic fluorescence spektrometry and high resolution continuum source atomic absorption spektrometry for three methods generation of volatile compounds Antimony. In both methods of atomic antimony detection, it compares the most common chemical generation of volatile compounds (hydrides) with two alternative methods - electrochemical and UV - photochemical. The values of performance parameters for the determination of Sb(III) and Sb(V) were determined for all the above combinations. In the case of chemical generation, a surprisingly almost four times higher limit of detection of Sb(III) was found in connection with AFS detection than AAS detection. The final part was devoted to UV - photochemical vapor generation, with AAS detection for Sb(III) reaching limit of detection 4,96 ppb, for Sb(V) 8,63 ppb. Although UV - photochemical generation of volatile antimony compounds did not reach such performance parameters as chemical or electrochemical generation, it was observed that the sensitivity of antimony determination increased greatly when introducing oxygen into the apparatus. The interference study also found a significant positive effect of Fe(II) on the generation efficiency, and this modification partially persisted without further introduction of these...

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18591号 / 工博第3952号 / 新制||工||1607(附属図書館) / 31491 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 河合 潤, 教授 酒井 明, 教授 伊藤 秋男 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Soil characterization provides the basic information necessary for understanding the physical, chemical, and biological properties of soils. Knowledge about soils can in turn be used to inform management practices, optimize agricultural operations, and ensure the continuation of ecosystem services provided by soils. However, current analytical standards for identifying each distinct property are costly and time-consuming. The optimization of laboratory grade technology for wide scale use is demonstrated by advances in a proximal soil sensing technique known as portable X-ray fluorescence spectrometry (pXRF). pXRF analyzers use high energy Xrays that interact with a sample to cause characteristic reflorescence that can be distinguished by the analyzer for its energy and intensity to determine the chemical composition of the sample. While pXRF only measures total elemental abundance, the concentrations of certain elements have been used as a proxy to develop models capable of predicting soil characteristics. This study aimed to evaluate existing models and model building techniques for predicting soil pH, texture, cation exchange capacity (CEC), soil organic carbon (SOC), total nitrogen (TN), and C:N ratio from pXRF spectra and assess their fittingness for California soils by comparing predictions to results from laboratory methods. Multiple linear regression (MLR) and random forest (RF) models were created for each property using a training subset of data and evaluated by R2 , RMSE, RPD and RPIQ on an unseen test set. The California soils sample set was comprised of 480 soil samples from across the state that were subject to laboratory and pXRF analysis in GeoChem mode. Results showed that existing data models applied to the CA soils dataset lacked predictive ability. In comparison, data models generated using MLR with 10-fold cross validation for variable selection improved predictions, while algorithmic modeling produced the best estimates for all properties besides pH. The best models produced for each property gave RMSE values of 0.489 for pH, 10.8 for sand %, 6.06 for clay % (together predicting the correct texture class 74% of the time), 6.79 for CEC (cmolc/kg soil), 1.01 for SOC %, 0.062 for TN %, and 7.02 for C:N ratio. Where R2 and RMSE were observed to fluctuate inconsistently with a change in the random train/test splits, RPD and RPIQ were more stable, which may indicate a more useful representation of out of sample applicability. RF modeling for TN content provided the best predictive model overall (R2 = 0.782, RMSE = 0.062, RPD = 2.041, and RPIQ = 2.96). RF models for CEC and TN % achieved RPD values >2, indicating stable predictive models (Cheng et al., 2021). Lower RPD values between 1.75 and 2 and RPIQ >2 were also found for MLR models of CEC, and TN %, as well as RF models for SOC. Better estimates for chemical properties (CEC, N, SOC) when compared to physical properties (texture), may be attributable to a correlation between elemental signatures and organic matter. All models were improved with the addition of categorical variables (land-use and sample set) but came at a great statistical cost (9 extra predictors). Separating models by land type and lab characterization method revealed some improvements within land types, but these effects could not be fully untangled from sample set. Thus, the consortia of characterizing bodies for ‘true’ lab data may have been a drawback in model performance, by confounding inter-lab errors with predictive errors. Future studies using pXRF analysis for soil property estimation should investigate how predictive v models are affected by characterizing method and lab body. While statewide models for California soils provided what may be an acceptable level of error for some applications, models calibrated for a specific site using consistent lab characterization methods likely provide a higher degree of accuracy for indirect measurements of some key soil properties.

In anthropology, elemental analysis of bone and teeth can provide significant details about an individual’s life history, such as diet, toxicity exposure, residency, and migration patterns. Intra-individual comparisons can help to gather information about a single individual’s life, while inter-individual comparisons can help illustrate a community’s life history during these periods. However, current methods of elemental analysis commonly involve the destruction of skeletal samples, which can damage a collection’s integrity and be perceived as disrespectful by descendant communities. Preliminary research has validated handheld x-ray fluorescence spectrometry (HHXRF) as an accurate and reliable method of analysis appropriate for determining the elemental composition of archaeological bone and teeth. In this study, teeth from 16 individuals (N=16) from the pre-conquest Classic Period (AD 625-1100) Maya site of Altun Ha, Belize, were analyzed using HHXRF to identify trace elements to gain a better understanding of the lives of the individuals and community. This study expands upon preliminary research by increasing the sample size and utilizes a filter to increase sensitivity to elements of interest. Diet and mobility were assessed using calcium (Ca), strontium (Sr), and bromine (Br) ratios. Net photon counts per element of interest were extracted and converted into ratios. An inter- and intra-individual comparison model was used. Results of calculated Sr/Ca ratios show a general increased reliance on marine subsistence sources within the sample. Shifts that do not align with this trend are present in several individuals, indicating social complexity of Altun Ha. Results of Br/Ca ratios are less clear in regard to diet and warrant further investigation.

Dans le but d’approfondir les connaissances fondamentales entre la structure des polymères associatifs intramoléculaires (polysavons) et leurs propriétés physico-chimiques en milieux aqueux, trois nouvelles familles de polymères amphiphiles cationiques ont été synthétisées par deux méthodes complémentaires permettant une grande variabilité de structure. Les polymères obtenus sont des poly(méth)acrylamides en peigne avec des groupes latéraux de type ammonium quaternaire portant une chaîne alkyle de taille variable. Une étude du comportement physico-chimique de ces polymères en solution, par viscosimétrie et spectroscopie de fluorescence avec deux sondes aux caractéristiques complémentaires, montre qu’ils présentent des propriétés de polysavons qui varient progressivement avec la structure des polymères amphiphiles étudiés, notamment la longueur de la chaîne alkyle latérale, la taille de l’espaceur entre les deux sites polaires amide et ammonium quaternaire et la masse molaire moyenne en nombre. En parallèle, la tensiométrie a montré que ces polyamphiphiles ont une très faible activité à l’interface eau/air confirmant la prédominance de l’effet hydrophobe, alors que les modèles moléculaires correspondants présentent d’excellentes propriétés tensio-actives. Des films de Langmuir ont ensuite été réalisés dans le cadre de la première étude de cette importance sur des polyamphiphiles cationiques. Dans ce domaine également, la grande variabilité de structure des polymères a permis des observations originales et de dégager de nouvelles relations entre la structure du polymère et les caractéristiques des isothermes de compression obtenues / In order to improve the fundamental knowledge of the relationships between the chemical structure of intramolecular associative polymers (polysoaps) and their physical chemical properties in aqueous media, three new families of cationic amphiphilic polymers were obtained by complementary methods offering great structure variability. The corresponding polymers were comb poly(meth)acrylamides with pendant ammonium groups with alkyl side chains of variable lengths. A first investigation of their physical chemical behaviour in aqueous solutions, by viscometry and fluorescence spectrometry with two complementary fluorescent probes, showed that they displayed polysoap properties which varied progressively with their chemical features, in particular the length of the alkyl side chain, the size of the spacer between the two polar amide and ammonium groups and the polymer molecular weight. Tensiometry confirmed the prevailing of the hydrophobic effect by showing that these polymers displayed a very weak activity at the water/air interface although the corresponding molecular models showed excellent tensio-active properties. Langmuir’s films were eventually obtained in the first study of this importance on cationic amphiphilic polymers. Here again, the great structural variability enabled original observations and new structure/properties relationships were obtained for the corresponding compression isotherms

Neste projeto foram abordados procedimentos analíticos para extração, separação e identificação de espécies de arsênio encontradas normalmente em quantidades de traços e ultra-traços em amostras biológicas e ambientais. Entre as amostras alvo deste estudo, teve-se alimentos de origem marinha como por exemplo camarão. Foi avaliada a estabilidade das espécies de arsênio nas soluções geradas pelos processos de extração. Para separação das espécies inorgânicas (arsenito e arsenato), metiladas (ácidos mono e dimetil arsênio) e orgânicas (arsenobetaina) empregaram-se as técnicas eletroforese capilar (CE) e cromatografia líquida (LC). Os sistemas de separação para a determinação das espécies de arsênio foram acoplados com os espectrômetros massas (ICP-MS), e de fluorescência atômica (AFS). Os sistemas acoplados apresentaram resolução e sensibilidade na determinação das espécies de arsênio nas amostras estudadas neste trabalho. A extração com água de espécies de As utilizando-se banho de ultra-som apresentou eficiência acima de 78%. A estabilidade das espécies nas soluções padrão e nos extratos das amostras foi mantida por um período de até uma semana quando armazenadas em geladeira (+4°C). Visando uma política de química limpa, foi desenvolvida uma metodologia para evitar desperdiço preparando micro-volumes de amostras e soluções padrão, para especiação de arsênio por eletroforese capilar. Para tal se empregou um injetor seqüencial, também foi desenvolvido um dispositivo de injeção hidrodinâmica para eletroforese capilar. Além disto, as soluções residuais geradas durante a pesquisa analítica foram tratadas para a recuperação de arsênio e boro. A extração no ponto nuvem foi empregada para recuperar As entanto que a precipitação por mineralização hidrotérmica foi aplicada para a recuperação de B . A aplicação deste procedimento resultou na extração de 80% de arsênio e 75% de boro. Isto, permitiu converter grandes volumes de resíduos líquidos perigosos em um pequeno volume de resíduos sólidos / Analytical procedures for extraction, separation and identification of arsenic species at ultra-trace levels in biological and environmental samples were investigated. Stability studies of arsenic species in sample extracts and standard solutions were carried out. Separation of arsenite, arsenate, monomethylarsonic and dimethylarsinic acids and also arsenobetaine were carried out by capillary electrophoresis or liquid chromatography. Determination of the separated arsenic species was accomplished by coupling the separation techniques to inductively coupled plasma mass spectrometry (ICP-MS) or atomic fluorescence spectrometry (AFS). Satisfactory resolution and sensibility were achieved by the coupled systems described. Extraction efficiency better than78% were achieved with water in an ultrasonic bath at the laboratory temperature (23-27°C). Whereas, stability of species in solutions stored in refrigerator at +4°C was efficient for aperiod up to one week. Micro-volumes of standards and sample solutions mixed in a sequential injector were prepared for arsenic speciation by capillary electrophoresis, aiming green chemistry. A time controlled micro-volume injector device for hydrodinamic injections was also developed. Finally, waste solutions from arsenic speciation analysis in a system with hydride generation were treated for arsenic and boron removal. Cloud point extraction for recovery of arsenic and hydrothermal mineralization of boron by calcium hydroxide were employed. Satisfactory removal of 80% of arsenic and 75% of boron from waste solution was achieved. These procedures allowed to reduce volumes of hazardous waste solutions