Thèses sur le sujet « Energy X-ray Dispersive Spectroscopy (EDX) »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Energy X-ray Dispersive Spectroscopy (EDX).
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 44 meilleures thèses pour votre recherche sur le sujet « Energy X-ray Dispersive Spectroscopy (EDX) ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
1
Canli, Sedat. « Thickness Analysis Of Thin Films By Energy Dispersive X-ray Spectroscopy ». Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612822/index.pdf.
Texte intégralRésumé :
EDS is a tool for quantitative and qualitative analysis of the materials. In electron microscopy, the energy of the electrons determines the depth of the region where the X-rays come from. By varying the energy of the electrons, the depth of the region where the X-rays come from can be changed. If a thin film is used as a specimen, different quantitative ratios of the elements for different electron energies can be obtained. Unique thickness of a specific film on a specific substrate gives unique energy-ratio diagram so the thickness of a thin film can be calculated by analyzing the fingerprints of the energy-ratio diagram of the EDS data obtained from the film.
2
Gharehbaghi, Ali. « Precipitation Study in a High Temperature Austenitic Stainless Steel using Low Voltage Energy Dispersive X-ray Spectroscopy ». Thesis, KTH, Materialens processteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103492.
Texte intégralRésumé :
Precipitation of second phase particles is a key factor dominating the mechanical properties of high temperature alloys. In order to control and optimize the precipitation effect it is of great importance to study the role of alloying elements in the formation and stability of precipitates. As a favored family of corrosion and creep resistant austenitic stainless steels the 20Cr-25Ni alloy was modified by addition of copper, molybdenum, nitrogen, niobium and vanadium. A set of alloys with similar matrix but varying contents of niobium, vanadium and nitrogen were prepared. Sample preparation process included melting, hot forging, solution annealing and finally aging for 500 h at 700, 800 and 850 ºC.Light optical and scanning electron microscopy revealed micron-scale precipitates on grain and twin boundaries as well as sub-micron intragranular precipitates in all samples. Characterization of precipitates was carried out by means of energy dispersive X-ray spectroscopy (EDS). Among micron-scale precipitates M23C6 carbide was the dominant phase at 700 ºC aging temperature; whereas silicon-rich eta phase (M5SiC) was the main precipitate in samples aged at 800 and 850 ºC. A few sigma phase particles were found in one of the niobium containing samples aged at 700 and 800 ºC. Sub-micron intragranular precipitates were analyzed using low voltage EDS. The spatial resolution of EDS microanalysis at 5 kV accelerating voltage was estimated as almost 100 nm which was at least eight times better than that using the ordinary 20 kV voltage. Also, low voltage EDS revealed the presence of light elements (carbon, nitrogen and boron) in the composition of sub-micron particles thanks to the less matrix effect in absorption of low energy X-rays of light elements. In samples aged at 700 ºC niobium-rich and vanadium-rich carbonitrides were found as the dominant precipitates; whereas they contained much less carbon in samples aged at 800 ºC and mostly became carbon-free nitrides with well-defined cuboidal shapes at 850 ºC aging temperature. This showed that niobium/vanadium-rich nitride phases are stable precipitates at aging temperatures above 700 ºC.The drawbacks of low voltage EDS were indicated as high detection limit (no detection of low- content elements), poor accuracy of quantitative analysis and high sensitivity to surface contamination. Some possible ways to improve the accuracy of low voltage EDS, e.g. longer acquisition time were examined and some other suggestions are proposed for future works.
3
Hubbard, Philip J. « Understanding biomineralization of polycaprolactone surfaces ». Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/119039/1/Philip_Hubbard_Thesis.pdf.
Texte intégralRésumé :
This thesis explored both a method to fabricate new model systems of the gut using 3D printing (Universiteit Utrecht, UU), and the fundamental mechanisms behind a coating process used to improve the qualities of 3D-printed scaffolds for bone regeneration applications (Queensland University of Technology, QUT). More specifically, the projects involved using stereolithography (SLA) technology to produce a "midi-gut" representative of intestinal architecture for cell seeding at UU, and investigating and optimising calcium phosphate coating on polycaprolactone surfaces at QUT. This thesis corresponds to the dual Master in Biofabrication programme, carried out between UU (Utrecht, Netherlands) and QUT (Brisbane, Australia).
4
Rueda-Fonseca, Pamela. « Magnetic quantum dots in II-VI semiconductor nanowires ». Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENY015/document.
Texte intégralRésumé :
Dans ce travail de thèse a été développé et étudié un nouveau type d'objet semiconducteur magnétique : des boîtes quantiques de CdMnTe insérées dans des nanofils de ZnTe/ZnMgTe constituant une structure de type cœur-coquille. L'objectif était d'étudier la croissance par épitaxie par jets moléculaires et les propriétés fondamentales de ces hétéro-structures complexes. Dans ce but deux aspects principaux ont été abordés : i) la qualité et le contrôle des propriétés structurales, électroniques et magnétiques de ces objets, grâce à une maîtrise de leur croissance et ii) l'obtention d'informations quantitatives locales sur la composition chimique de ces nanostructures inhomogènes. Pour atteindre ces objectifs, nous avons divisé notre étude en quatre étapes. La première étape de ce travail a été concentrée sur l'étude quantitative de la formation des particules d'or servant de catalyseurs à la croissance des nanofils. La seconde étape a porté sur l'analyse des mécanismes de croissance et des paramètres gouvernant la croissance des fils de ZnTe. En particulier deux types de fils ont été observés : des fils cylindriques de structure wurtzite et des fils coniques de structures zinc-blende. Un modèle de croissance guidée par la diffusion a été utilisé pour rendre compte de certains des résultats quantitatifs présentés dans cette partie. La troisième étape a concerné l'insertion de boîtes quantiques de CdMnTe dans des nanofils de structure cœur-coquille ZnTe/ZnMgTe. Une étude préalable des paramètres pertinents influençant les propriétés magnéto-optiques de ces objets, tels que le confinement de la boîte quantique, l'incorporation du Mn et l'anisotropie de contrainte créée par la structure, a été menée. La quatrième et dernière étape de ce travail a porté sur l'interprétation quantitative de mesures d'analyse dispersive en énergie effectuées sur des nanofils de structure cœur-multicoquille. Un modèle géométrique a été proposé, permettant de retrouver la forme, les dimensions et la composition chimique des boîtes quantiques et des coquilles. Cette étude a été couplée à des mesures de caractérisation telles que la cathodo-luminescence, la micro-photo-luminescence et la spectroscopie magnéto-optique effectuées sur le même nanofilIn this PhD work a novel type of magnetic semiconductor object has been developed: Cd(Mn)Te quantum dots embedded in ZnTe/ZnMgTe core-shell nanowires. The goal was to investigate the growth, by molecular beam epitaxy, and the fundamental properties of these complex heterostructures. For that purpose, two main issues were addressed: i) gaining control of the structural, electronic and magnetic properties of these quantum objects by mastering their growth; and ii) obtaining quantitative local knowledge on the chemical composition of those non-homogeneous nanostructures. To tackle these topics, our research was divided into four stages. The first stage was devoted to perform a quantitative study of the formation process of the Au particles that catalyze the growth of nanowires. The second stage involved the analysis of the mechanisms and parameters governing the growth of ZnTe nanowires. In particular, two different types of nanowires were found: cone-shaped nanowires with the zinc-blende crystal structure and cylinder-shaped nanowires with the hexagonal wurtzite structure. A diffusion-driven growth model is employed to fit some of the quantitative results presented in this part. The third stage focused on the insertion of pure CdTe quantum dots containing Mn ions in the core-shell nanowires. An initial study of the relevant parameters influencing the magneto-optical properties of these objects, such as the quantum dot confinement, the Mn incorporation, and the strain anisotropy, was performed. The four and last stage of this work concerned the quantitative interpretation of Energy-Dispersive X-ray spectroscopy measurements performed on single core-multishell nanowires. A geometrical model was proposed to retrieve the shape, the size and the local composition of the quantum dot insertions and of the multiple layers of the heterostructures. This study was coupled to other complementary characterization measurements on the same nanowire, such as cathodo-luminescence, micro-photo-luminescence and magneto-optical spectroscopy
5
Lepinay, Kevin. « Développement et applications de la tomographie chimique par spectroscopie EDX ». Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0124/document.
Texte intégralRésumé :
Cette thèse porte sur l’évaluation des techniques pour la tomographie chimique par STEM EDX : mise au point des procédures expérimentales, traitement des données, reconstruction des volumes, analyse de la qualité des résultats obtenus et évaluation de la complexité globale. Les performances très limitées de l’analyse STEM EDX font que peu d’études, jusqu’à aujourd’hui, se sont portées sur cette technique. Cependant, les avancées très notables procurées par les nouveaux détecteurs ‘SDD’ ainsi que les sources électroniques X-FEG haute brillance, rendant l’analyse STEM EDX 2D très rapide, ont relancé la possibilité de la tomographie chimique ; la technique demande toutefois à être mise au point et évaluée (performances et complexité). Nous avons travaillé sur un microscope Tecnai Osiris permettant d’acquérir des cartographies chimiques EDX de centaines de milliers de pixels avec une résolution de l’ordre du nanomètre en quelques minutes. Nous avons choisi de préparer par FIB des échantillons en forme de pointe et d’utiliser un porte-objet permettant une exploration angulaire de 180° sans ombrage. Puis, à l’aide d’échantillons modèles (billes de SiO2 dans une résine), nous avons évalué les déformations d’échantillon par l’irradiation du faisceau électronique. Ceci nous a permis de proposer une méthode pour limiter cet effet par déposition d’une couche de 20 nm de chrome. Des simulations d’images ont permis d’évaluer les logiciels et méthodes de reconstruction. La méthodologie de chaque étape d’une analyse de tomographie STEM EDX a ensuite été expliquée, et l’intérêt de la technique démontré grâce à la comparaison de l’analyse 2D et 3D d’un transistor FDSOI 28 nm. La qualité des reconstructions (rapport signal-sur-bruit, résolution spatiale) a été évaluée en fonction des paramètres expérimentaux à l’aide de simulations et d’expériences. Une résolution de 4 nm est démontrée grâce à l’analyse d’une mire et d’un transistor « gate all around ». Pour ce même transistor, la possibilité et l’intérêt d’analyse de défaillance à l’échelle nanométrique est prouvée. Une analyse d’un défaut de grille d’une SRAM ou de trous dans un pilier en cuivre permettent d’expliquer l’intérêt d’une combinaison d’un volume HAADF (morphologie et résolution < 4 nm) et du volume EDX (information chimique). La conclusion est que cette technique, qui reste encore à améliorer du point de vue de sa simplicité, montre déjà son utilité pour l’analyse et la mise au point des technologies avancées (nœud 20 nm et après)This thesis focuses on the evaluation of the STEM EDX chemical tomography technique: development of experimental procedures, data processing and volumes reconstruction, quality analysis of the results and evaluation of the overall complexity. Until now, STEM EDX analysis performances were very limited, so only few studies about this technique have been realized. However, very significant progress procured by the new SDD detectors as well as by the high brightness electronic sources (X-FEG), making the STEM EDX 2D analysis very fast, have revived the possibility of the chemical tomography, although the technique has to be developed and evaluated (performance and complexity). We have worked on a Tecnai Osiris which acquires EDX chemical mapping of hundreds of thousands of pixels with resolution of one nanometer and in a few minutes. We chose to prepare the rod-shaped samples by FIB and use a sample holder allowing an angle of exploration of 180° without shadowing effects. Then, using model samples (SiO2 balls in resin), we evaluated the sample deformation due to the electron beam irradiation. This allowed us to propose a method to reduce this effect by depositing a 20 nm chromium layer. Images simulations were used to evaluate the software and the reconstruction methods. The methodology of each step of the STEM EDX tomography analysis is then explained and the technique interest is demonstrated by comparing the 2D and the 3D analysis of a transistor 28 nm FDSOI. The quality of the reconstructions (signal-to-noise ratio, spatial resolution) was evaluated, in function of experimental parameters, using simulations and experiments. A resolution of 4 nm is demonstrated through the analysis of a test pattern and a "gate all around” transistor. For the same transistor, the possibility and the interest of a failure analysis at the nanoscale is proven. Analyses of a SRAM gate fail or of the holes in a copper pillar explain the benefits of a combination between a HAADF volume (morphology and resolution < 4 nm) and an EDX volume (chemical information). To conclude, this technique, which still needs to be improved in terms of simplicity, is already showing its usefulness for the analysis and the development of advanced technologies (20nm node and beyond)
6
Ozaslan, Mehtap, Wei Liu, Maarten Nachtegaal, Anatoly Frenkel, Bogdan Rutkowski, Matthias Werheid, Anne-Kristin Herrmann et al. « Homogeneity and Elemental Distribution in Self-Assembled Bimetallic Pd-Pt Aerogels prepared by a spontaneous one-step gelation process ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-210970.
Texte intégralRésumé :
Multi-metallic aerogels have recently emerged as a novel and promising class of unsupported electrocatalyst materials due to their high catalytic activity and improved durability for various electrochemical reactions. Aerogels can be prepared by a spontaneous one-step gelation process, where the chemical co-reduction of metal precursors and the prompt formation of the nanochain-consisting hydrogels, as a preliminary stage for the preparation of aerogels take place. However, detailed knowledge about the homogeneity and chemical distribution of these three-dimensional Pd-Pt aerogels at the nano-scale as well as at the macro-scale is still unclear to date.
Therefore, we used a combination of spectroscopic and microscopic techniques to obtain a better insight into the structure and elemental distribution of the various Pd-rich Pd-Pt aerogels prepared by the spontaneous one-step gelation process. Synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy and high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) in combination with energy-dispersive X-ray spectroscopy (EDX) were employed in this work to uncover the structural architecture and chemical composition of the various Pd-rich Pd-Pt aerogels over a broad length range. The Pd80Pt20, Pd60Pt40 and Pd50Pt50 aerogels showed heterogeneity in the chemical distribution of the Pt and Pd atoms inside the macroscopic nanochain-network. Features of monometallic clusters were not detected by EXAFS or STEM-EDX, indicating alloyed nanoparticles. However, the local chemical composition of the Pd-Pt alloys strongly varied along the nanochains and thus within a single aerogel. To determine the electrochemically active surface area (ECSA) of the Pd-Pt aerogels for applications in electrocatalysis, we used the electrochemical CO stripping method. Due to high porosity and extended network structure, the resulting values of the ECSA for the Pd-Pt aerogels were higher than that for a commercially available unsupported Pt black catalyst. We show that the Pd-Pt aerogels possess a high utilization of catalytically active centers for electrocatalytic applications based on the nanostructured bimetallic framework.
Knowledge about the homogeneity and chemical distribution of the bimetallic aerogels can help to further optimize their preparation by the spontaneous one-step gelation process and to tune their electrocatalytic reactivity.
7
Lu, Shifeier. « Analytical study of osteoporosis of maxilla in ovariectomized rats ». Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/88474/1/Shifeier_Lu_Thesis.pdf.
Texte intégralRésumé :
The project applied analytical facilities to characterize the composition and mechanical properties of osteoporosis in maxillary bone using an ovariectomized rat model. It was found that osteoporotic jaw bone contained different amount of trace elements in comparison with the normal bone, which plays a significant role in bone quality. The knowledge generated from the study will assist the treatment of jaw bone fracture and dental implant placement.
8
Fairbrother, P. J. « Thermal diffuse scattering in energy-dispersive x-ray spectroscopy ». Thesis, University of Exeter, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232967.
Texte intégral
9
Vídeňský, Ondřej. « Analýza bateriových hmot metodami EDS ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-399522.
Texte intégralRésumé :
This master thesis deals with analysis of battery mass using x-ray spectral microanalysis. For the measurement two scanning electron microscopes equipped with energy dispersive x-ray spectroscopes were used. Appropriate examples were prepaired by standard method. Then elemental analysis was performed with changing conditions of measurement. Two programs were used for spectrums evaluation and in the end the size of errors was observed for every conditions.
10
Kleinhans, Henrik. « Evaluation of the Carbonization of Thermo-Stabilized Lignin Fibers into Carbon Fibers ». Thesis, Linköpings universitet, Kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120519.
Texte intégralRésumé :
Thermo-stabilized lignin fibers from pH-fractionated softwood kraft lignin were carbonized to various temperatures during thermomechanical analysis (TMA) under static and increasing load and different rates of heating. The aim was to optimize the carbonization process to obtain suitable carbon fiber material with good mechanical strength potential (high tensile strength and high E-modulus). The carbon fibers were therefore mainly evaluated of mechanical strength in Dia-Stron uniaxial tensile testing. In addition, chemical composition, in terms of functional groups, and elemental (atomic) composition was studied in Fourier transform infrared spectroscopy (FTIR) and in energy-dispersive X-ray spectroscopy (EDS), respectively. The structure of carbon fibers was imaged in scanning electron microscope (SEM) and light microscopy. Thermogravimetrical analysis was performed on thermo-stabilized lignin fibers to evaluate the loss of mass and to calculate the stress-changes and diameter-changes that occur during carbonization. The TMA-analysis of the deformation showed, for thermo-stabilized lignin fibers, a characteristic behavior of contraction during carbonization. Carbonization temperatures above 1000°C seemed most efficient in terms of E-modulus and tensile strength whereas rate of heating did not matter considerably. The E-modulus for the fibers was improved significantly by slowly increasing the load during the carbonization. The tensile strength remained however unchanged. The FTIR-analysis indicated that many functional groups, mainly oxygen containing, dissociate from the lignin polymers during carbonization. The EDS supported this by showing that the oxygen content decreased. Accordingly, the relative carbon content increased passively to around 90% at 1000°C. Aromatic structures in the carbon fibers are thought to contribute to the mechanical strength and are likely formed during the carbonization. However, the FTIR result showed no evident signs that aromatic structures had been formed, possible due to some difficulties with the KBr-method. In the SEM and light microscopy imaging one could observe that porous formations on the surface of the fibers increased as the temperature increased in the carbonization. These formations may have affected the mechanical strength of the carbon fibers, mainly tensile strength. The carbonization process was optimized in the sense that any heating rate can be used. No restriction in production speed exists. The carbonization should be run to at least 1000°C to achieve maximum mechanical strength, both in E-modulus and tensile strength. To improve the E-modulus further, a slowly increasing load can be applied to the lignin fibers during carbonization. The earlier the force is applied, to counteract the lignin fiber contraction that occurs (namely around 300°C), the better. However, in terms of mechanical performance, the lignin carbon fibers are still far from practical use in the industry.
11
Slater, Thomas Jack Alfred. « Three dimensional chemical analysis of nanoparticles using energy dispersive X-ray spectroscopy ». Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/three-dimensional-chemical-analysis-of-nanoparticles-using-energy-dispersive-xray-spectroscopy(3eb607a2-eb03-4d45-b9eb-71b0ca45c2db).html.
Texte intégralRésumé :
The aim of this thesis is to investigate the methodology of three dimensional chemical imaging of nanoparticles through the use of scanning transmission electron microscope (STEM) – energy dispersive X-ray (EDX) spectroscopy. In this thesis, an absorption correction factor is derived for spherical nanoparticles that can correct X-ray absorption effects. Quantification of EDX spectra of nanoparticles usually neglects X-ray absorption within the nanoparticle but may lead to erroneous results, thus an absorption correction is important for accurate compositional quantification. The absorption correction presented is verified through comparison with experimental data of Au X-ray peaks in spherical Au nanoparticles and is found to agree excellently. This absorption correction allows accurate compositional quantification of large ( > 100 nm) particles with STEM-EDX.Three dimensional chemical mapping is achievable through the use of EDX spectroscopy with electron tomography. Here, the methodology of STEM-EDX tomography is fully explored, with a focus on how to avoid artefacts introduced through detector shadowing and low counts per pixel. A varied-time acquisition scheme is proposed to correct for detector shadowing that is shown to provide a more constant intensity over a series of projections, allowing a higher fidelity reconstruction. The STEM-EDX tomography methodology presented is applied to the study of AgAu nanoparticles synthesized by the galvanic replacement reaction. The elemental distribution as a function of the composition of the as-synthesized nanoparticles is characterised and a reversal in the element segregated to the surface of the nanoparticles is found. The composition at which the reversal takes place is shown to correlate with a peak in the catalytic yield of a three component coupling reaction. It is hypothesized that a continuous Au surface results in the optimum catalytic conditions for the reaction studied, which guides the use of galvanically prepared AgAu nanoparticles as catalysts.
12
Lee, Ester Mi Ryoung. « Análise in vitro da morfologia superficial de uma nova formulação de biovidro associado ao laser de Nd:YAG e laser de CO2 sobre dentina humana ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/23/23155/tde-24082017-140846/.
Texte intégralRésumé :
Dentre as opções de terapias dessensibilizantes, a proposta mais recente para o tratamento da Hipersensibilidade Dentinária é o uso do biovidro. Esse novo material apresenta a capacidade de promover a formação de hidroxiapatita na superfície da dentina, representando uma união química mais estável e duradoura sobre os túbulos dentinários. Este trabalho comparou o efeito de uma nova formulação de biovidro disperso em ácido fosfórico 30%, associado ao laser de Nd:YAG e ao laser de CO2 na obliteração de túbulos dentinários expostos. Foram obtidas 96 amostras de dentina humana que foram divididas em 6 grupos experimentais (n=16) e distribuídas como a seguir: G1 - controle negativo (nenhum tratamento adicional);? G2 - laser de Nd:YAG;? G3 - laser de CO2;? G4 - pasta de biovidro (biovidro + ácido fosfórico 30%);? G5 - pasta de biovidro + laser de Nd:YAG;? G6 - pasta de biovidro + laser de CO2. Os grupos G5 e G6 foram irradiados com laser de Nd:YAG e laser de CO2, respectivamente, após tratamento com a pasta de biovidro disperso em ácido fosfórico. Ao final do experimento, os grupos foram analisados qualitativamente por Espectroscopia de Infravermelho na Transformada de Fourier (FTIR), Difração de Raios X (DRX), Microscopia Eletrônica de Varredura (MEV) e Espectroscopia de Dispersão de Energia de Raios X (EDS). As análises evidenciaram que a dipersão do biovidro em ácido fosfórico 30% é capaz de formar cristais de hidrogenofosfato de cálcio e, quando a pasta formulada é aplicada sobre a dentina, ocorrem reações químicas com a estrutura dental, formando cristais de monetita. Ao irradiar os cristais formados com laser de Nd:YAG e CO2, ocorreu a desidratação desses cristais, levando à formação de hidroxiapatita. As imagens de MEV demonstram a formação de precipitados cristalinos e amorfos de dimensões variadas sobre a superfície de dentina e na entrada dos túbulos dentinários em todos os grupos que receberam o tratamento com a formulação de biovidro. O laser de CO2 foi capaz de promover alterações na morfologia do material formado de maneira ainda mais evidente especialmente nas dimensões e disposição dos cristais de hidroxiapatita formado sobre a superfície. A análise de EDS evidenciou presença de silício, composto que não está presente naturalmente na estrutura dentária, mas somente na composição do biovidro. Dessa forma, pode-se concluir que a associação do pó de biovidro com ácido fosfórico 30% permitiu a formação de uma camada de cristais na superfície e entrada dos túbulos dentinários, evidenciando que a pasta formulada viabiliza a aplicação e manutenção do biovidro sobre a superfície dentinária. Sua associação com o laser de Nd:YAG e CO2 parece melhorar a interação desses cristais com a dentina, formando cristais de hidroxiapatita. Nesse estudo, o laser de CO2 promoveu a melhor distribuição e conformação dos cristais sobre a dentina.Among desensitizing therapies options, the most recent proposal for Dentin Hypersensitivity treatment is the use of bioglass. This new material presents the ability to promote the formation of hydroxyapatite on dentin surface, representing a more stable and lasting chemical bond on dentin tubules. This work compared the effect of a new formulation of bioglass dispersed in 30% phosphoric acid, associated with Nd: YAG laser and CO2 laser in the obliteration of exposed dentin tubules. 96 human dentin samples were obtained, divided into 6 experimental groups (n = 16) and distributed as follows: G1 - negative control (no additional treatment);? G2- Nd: YAG laser;? G3 - CO2 laser;? G4 - bioglass paste (bioglass + 30% phosphoric acid);? G5 - bioglass paste + Nd: YAG laser;? G6 - bioglass paste + CO2 laser. Groups G5 and G6 were irradiated with Nd:YAG laser and CO2 laser, respectively, after treatment with the slurry dispersed in phosphoric acid. At the end of the experiment, all groups were qualitatively analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Energy Dispersion Spectroscopy (EDS). The analysis showed that the dispersion of bioglass in 30% phosphoric acid forms calcium hydrogen phosphate crystals and when the formulated paste is applied on dentin surface, chemical reactions occur with the dental structure, forming monetite crystals. When irradiating these crystals with Nd: YAG and CO2 laser, dehydration of these crystals occurred leading to the formation of hydroxyapatite. MEV images demonstrate the formation of crystalline and amorphous precipitates of varying dimensions on the dentin surface and at the entrance of dentinal tubules in all groups receiving treatment with the bioglass formulation. The CO2 laser was able to promote changes in the morphology of the formed material even more evident especially in the dimension and arrangement of hydroxyapatite crystals formed on the surface. The analysis of EDS showed the presence of silicon, a compound that is not naturally present in the tooth structure, but only in the bioglass composition. Thus, it can be concluded that the association of bioglass powder with 30% phosphoric acid allowed the formation of a layer of crystals on the surface and its entrance of the dentinal tubules, evidencing that the formulated paste enables the application and maintenance of bioglass on dentin surface. Its association with the Nd:YAG and CO2 laser seems to improve the interaction of these crystals with dentin, forming hydroxyapatite crystals. In this study. CO2 laser promoted better crystals distribution and conformation on dentin surface.
13
Alexandrina, Eduardo Carlos. « Caracterização e composição química do material particulado grosso (MP10) no centro da cidade de São Carlos (SP) ». Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7241.
Texte intégralRésumé :
Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-15T20:31:27Z
No. of bitstreams: 1
DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5)Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:58:59Z (GMT) No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5)
Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-16T19:59:07Z (GMT) No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5)
Made available in DSpace on 2016-09-16T19:59:13Z (GMT). No. of bitstreams: 1 DissECA.pdf: 4704364 bytes, checksum: 1909457a146bdb29a74ad65130ca2bd9 (MD5) Previous issue date: 2015-03-27
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coarse particulate matter with aerodynamic diameter smaller than 10μm (PM10) have long been considered as air pollutants associated with health issues. They penetrate into the upper respiratory tract, causing respiratory problems such as worsening of asthma. The aim of this study was to determine and quantify the distribution of chemical elements in the PM10 particulate matter present in the atmosphere of the city of Sao Carlos (Sao Paulo). Samples were collected daily for a period of 23h and 30 minutes, from April 16, 2014 to April 16, 2015. A high-volume sampler (AGV-PM10) with micro quartz and fiber glass filters were used. The filters were subjected to gravimetric analysis to obtain the mass of PM10 and were then analyzed by energy dispersive X-ray fluorescence and Laser Induced Breakdown Spectroscopy to identify and quantify the chemical composition of the samples. The highest average concentration during twelve-month period was 70.41μg/m³ (August, 2014) and the smallest was 22.59μg/m³ (January, 2015). The annual arithmetic average found for the twelve months period was 42.71μg/m³. If compared with annual arithmetic average limit of 40μg/m³, established by CETESB, the value is slightly above and below 50 μg/m³ (CONAMA). If we consider the limit established by the World Health Organization (WHO), which is 20μg/m³, this value is much higher than recommended. The chemicals elements found were characteristic of urban areas
O material particulado, cujo diâmetro aerodinâmico é menor do que 10μm vem sendo considerado como poluente atmosférico muito associado a questões de saúde, uma vez que são os que penetram em vias respiratórias, agravando problemas como o da asma, por exemplo. O objetivo deste trabalho foi avaliar os níveis de concentração de material particulado (MP10) e determinar a distribuição dos elementos químicos deste material particulado presente no ar atmosférico do centro da cidade de São Carlos (São Paulo). As amostras foram coletadas diariamente, por um período de 23h e 30 minutos, entre 16 de abril de 2014 a 16 de abril de 2015. Foi utilizado um amostrador de grandes volumes (AGV-MP10), submetendo os filtros, de fibra de vidro e de micro quartzo, à análise gravimétrica para obtenção de massa de MP10, Fluorescência de Raios-X de Energia Dispersiva de (EDX) e a Espectroscopia de ruptura induzida por laser (LIBS) para identificação e quantificação da composição química elementar das amostras. A maior concentração média do período de doze meses amostrado foi de 70,41μg/m³ em agosto/2014 e a menor de 22,59μg/m³ em janeiro/2015. A média aritmética anual encontrada para o período de doze meses foi de 42,71μg/m³. Se comparada com a média aritmética anual do limite estabelecido pela CETESB, de 40μg/m³, o valor está um pouco acima e um pouco abaixo de 50 μg/m³(CONAMA). Se for considerado o limite estabelecido pela Organização Mundial da Saúde (OMS), que é de 20 μg/m³, este valor encontra-se muito acima do recomendado. Os elementos químicos encontrados são característicos de áreas urbanas e apresentam resultados semelhantes a estudos anteriores na cidade.
14
Unuigbe, David Moweme. « Characterisation of silicon nanoparticles produced by mechanical attrition using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoemission spectroscopy ». Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12105.
Texte intégralRésumé :
Includes abstract.Includes bibliographical references.
The establishment of printing technologies, using nanoparticle based inks, promises inexpensive manufacture of electronic devices. However, to produce working devices, nanoparticles have to meet requirements on size, shape, and composition. In the application of silicon nanoparticles in electronics, it is important that a network of interconnecting particles is formed through which charge transport can take place. Of further importance is that there is an absence of surface oxide in order to maintain a direct silicon-silicon connection within the network. In this work, cheap and scalable production of silicon nanoparticles is achieved efficiently with a top-down process of mechanical attrition by high energy milling.
15
Bhattacharya, Arunodaya. « Ion irradiation effects on high purity bcc Fe and model FeCr alloys ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112398/document.
Texte intégralRésumé :
Les alliages binaires FeCr de structure FM (ferrito/martensitique) sont actuellement les candidats les plus prometteurs comme matériaux de structure pour les réacteurs rapides refroidis au sodium et les futurs systèmes de fusion. Cependant, l'impact de Cr sur l'évolution de la microstructure irradié dans ces matériaux n’est pas bien compris. De plus, particulièrement pour les applications de fusion, le scénario de dégâts d'irradiation devrait être compliquée en outre par la présence de grandes quantités d'hélium produit par transmutation nucléaire (~ 10 appm He / dpa). Dans ce contexte, une étude spécifique des effets de l'irradiation ionique (influence du Cr et de l’He sur l’évolution de la microstructure) a été menée à 500 ° C sur une grande variété d’alliages FeCr de haute pureté (à teneur en Cr allant de ~ 3 wt.% À 14 wt.%) ainsi que sur du Fe pur. Les irradiations ont été effectuées à l'aide ions Fe, en mode mono-faisceau et mode dual-beam (irradiation par des ions Fe et co-implantation d'He) afin de pouvoir séparer le dommage ballistique de l’implantation couplée avec de l’He. Trois différentes doses ont été étudiées: dose élevée (157 dpa, avec 17 appm He / dpa), dose intermédiaire (45 dpa, avec 57 appm He / dpa) et in situ à faible dose (0,33 dpa, avec 3030 appm He / dpa). Les expériences ont été effectuées en utilisant l'installation JANNuS triple faisceau du CEA-Saclay et la plateforme in-situ du CSNSM-Orsay. L’évolution microstructurale des échantillons est essentiellement faite par MET, SAT et par EDS en mode STEM. Les principaux résultats sont les suivants : 1) L’étude détaillée de la population des cavités dans du Fe irradié à forte dose a révélé une forte réduction du gonflement du fait de l'ajout d’He. Une réduction drastique de la taille des cavités en dépit d’une densité plus élevée a été observée. Ce comportement a été observé tout au long zone irradié, jusqu’au pic d’endommagement. 2) La microstructure de cavités a également été étudiée dans les alliages FeCr irradiés en double faisceau à forte dose, et les résultats ont été comparés à ceux obtenus dans le Fe pur. L'analyse a été effectuée à une profondeur intermédiaire de 300 à 400 nm sous la surface (pour éviter les effets des interstitiels injectés et les effets de surface), correspondant à 128 dpa, 13 appm He / dpa. L’étude par TEM a montré que l'addition de petites quantités de Cr, aussi basse que 3wt.%, est très efficace pour réduire fortement le gonflement. Une réduction drastique de la taille des cavités a été mise en évidence. Par exemple, la taille moyenne des cavités pour l’alliage Fe3% Cr est de l’ordre de 0,9 nm alors qu’elle est voisine de 6,8 nm pour le Fe pur. De plus, la variation du gonflement en fonction de la teneur en Cr n’est pas monotone et présente un maximum local à environ 9 -. 10wt% Cr. 3) Le couplage des différentes techniques d’analyse, MET classique, STEM/EDS et analyse SAT appliqué à l’étude des alliages FeCr irradiés à faible et moyenne dose révèle la présence de zones enrichies en Cr sur le plan d’habitat des boucles de dislocation. Ce phénomène est relié à un phénomène de ségrégation induite par irradiation (RIS) de Cr au voisinage du coeur des boucles de dislocation. Quand la boucle se développe sous irradiation, les zones de ségrégation ne peuvent probablement pas se redissoudre du fait de la présence d'impuretés telles que le C. Lorsque les boucles sont imagées par MET, ces zones enrichies produisent des franges de contraste au voisinage du plan de la boucle. Une estimation quantitative de cet enrichissement a été déduit par STEM / EDS et l'SAT. La teneur en Cr dans ces domaines se situe entre 23 -. 35% par EDS et 22 % par SAT, ce qui est bien en dessous de la teneur en Cr de la phase α’ riche en CrFeCr binary alloys are a simple representative of the reduced activation ferritic/martensitic (F-M) steels, which are currently the most promising candidates as structural materials for the sodium cooled fast reactors (SFR) and future fusion systems. However, the impact of Cr on the evolution of the irradiated microstructure in these materials is not well understood in these materials. Moreover, particularly for fusion applications, the radiation damage scenario is expected to be complicated further by the presence of large quantities of He produced by the nuclear transmutation (~ 10 appm He/dpa). Within this context, an elaborate ion irradiation study was performed at 500 °C on a wide variety of high purity FeCr alloys (with Cr content ranging from ~ 3 wt.% to 14 wt.%) and a bcc Fe, to probe in detail the influence of Cr and He on the evolution of microstructure. The irradiations were performed using Fe self-ions, in single beam mode and in dual beam mode (damage by Fe ions and co-implantation of He), to separate ballistic damage effect from the impact of simultaneous He injection. Three different dose ranges were studied: high dose (157 dpa, 17 appm He/dpa for the dual beam case), intermediate dose (45 dpa, 57 appm He/dpa for dual beam case) and in-situ low dose (0.33 dpa, 3030 appm He/dpa for the dual beam case). The experiments were performed at the JANNuS triple beam facility and dual beam in situ irradiation facility at CEA-Saclay and CSNSM, Orsay respectively. The microstructure was principally characterized by conventional TEM, APT and EDS in STEM mode. The main results are as follows: 1) A comparison of the cavity microstructure in high dose irradiated Fe revealed strong swelling reduction by the addition of He. It was achieved by a drastic reduction in cavity sizes and an increased number density. This behaviour was observed all along the damage depth, upto the damage peak. 2) Cavity microstrusture was also studied in the dual beam high dose irradiated FeCr alloys, and the results were compared to bcc Fe. The analysis was performed at an intermediate depth 300 – 400 nm below the surface (to avoid injected interstitial effect and surface effects), corresponding to 128 dpa, 13 appm He/dpa. TEM study revealed that the addition of small quantities of Cr, as low as 3wt.%, is highly efficient in strongly reducing void swelling. It was achieved by a drastic reduction of cavity sizes. For instance, average cavity size in Fe3%Cr was 0.9 nm as opposed to 6.8 nm in bcc Fe. Furthermore, the variation of void swelling as a function of Cr content is non-monotonic, with alocal maxima around 9 - 10wt.%Cr. 3) Coupling of conventional TEM, STEM/EDS and APT analysis on low and intermediate dose irradiated FeCr alloys revealed the presence of Cr enriched zones on the habit plane of the dislocation loops. This is expected to be due to radiation induced segregation (RIS) of Cr close to the core of the loops. As the loop grows under irradiation, the segregated areas are probably prevented from re-dissolution by impurity elements such as C. When imaged by TEM using classical diffraction contrast imaging techniques, these enriched zones produce displacement fringe contrast on the loop plane. A quantitative estimate of this enrichment was deduced by STEM/EDSand APT. The Cr content in these areas was between 23 - 35 at.% measured by EDS and 22 ± 2 at.% obtained by APT, whichis well below the Cr content of the Cr-rich α’ phase
16
Ouma, Linda Achiengꞌ. « Synthesis, optical and morphological characterization of pbse quantum dots for diagnostic studies : a model study ». Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/3975.
Texte intégralRésumé :
>Magister Scientiae - MScIn this study PbSe quantum dots (QDs) were successfully synthesized via the organometallic and aqueous routes. Optical characterization was carried out using photoluminescence (PL) spectroscopy, structural and morphological characterization were carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDS) was used to determine the composition of the QDs. All the synthesized QDs were found to have emissions within the near-infrared region of the spectrum (≥1000 nm) with most of them being less than 5 nm in size. The aqueous synthesized QDs had a perfect Gaussian emission spectrum with a FWHM of ~23 nm indicating pure band gap emission and narrow size distribution respectively. The QDs were determined to have a cubic rock-salt crystal structure consistent with bulk PbSe. The aqueous synthesized QDs were however not stable in solution with the QDs precipitating after approximately 48 h. The organometallic synthesized QDs were transferred into the aqueous phase by exchanging the surface oleic acid ligands with 11-mercaptoundecanoic acid ligands. The ligand exchanged QDs were however stable in solution for over two weeks. The effects of reaction parameters on the optical and structural properties of the organometallic synthesized QDs were investigated by varying the reaction time, temperature, ligand purity, lead and selenium sources. It was observed that larger QDs were formed with longer reaction times, with reactions proceeding faster at higher reaction temperatures than at lower temperatures. Varying the ligand purity was found to have minimal effects on the properties of the synthesized QDs. The lead and selenium sources contributed largely to the properties of the QDs with lead oxide producing spherical QDs which were smaller compared to the cubic QDs produced from lead acetate. TBPSe was seen to produce smaller QDs as compared to TOPSe. The cytotoxity of the synthesized QDs was determined following the WST-1 cell viability assay with the QDs being found to be non-toxic at all the tested concentrations
17
Sorel, Julien. « Tomographie électronique analytique : Automatisation du traitement de données et application aux nano-dispositifs 3D en micro-électronique ». Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI078.
Texte intégralRésumé :
Ce travail porte sur l’automatisation du traitement des données de tomographie électronique analytique appliquée aux nano-dispositifs électroniques. La technique utilisée est la spectroscopie de dispersion en énergie des rayons-X en mode balayage en microscopie électronique en transmission (STEM-EDX : Scanning Transmission Electron Microscopy, Energy Dispersive X-ray spectroscopy). Si la tomographie électronique STEM-EDX a bénéficié d’avancées technologiques récentes, comme de nouvelles sources électroniques ‘X’-FEG (Field Emission Gun) et des détecteurs X sensibles, les SDD (Silicon Drift Detectors), elle reste chronophage avec une statistique de comptage souvent faible pour éviter des durées prohibitives et une dégradation de l’échantillon par irradiation électronique. L’empilement des projections STEM-EDX, acquises sous différents angles d’inclinaison, est par ailleurs très volumineux et les logiciels commerciaux actuels ne peuvent pas le traiter automatiquement et de manière optimale. Pour améliorer cette situation, nous avons développé un programme utilisant la librairie Hyperspy en langage python, dédiée au traitement de données multi-dimensionnelles. L’analyse statistique multivariée permet d’optimiser et d’automatiser le débruitage des données, la calibration des spectres et la séparation des raies d’émission X superposées pour l’obtention de reconstructions tridimensionnelles quantitatives. Une technique de reconstruction avancée, l’acquisition comprimée, a aussi été mise en œuvre, diminuant le nombre de projections sans réduire l’information 3D finale. La méthode développée a été utilisée pour l’analyse chimique 3D de quatre nanostructures issues de la microélectronique : des transistors FET multi-grilles, HEMT et GAA, et un film mince GeTe. Les échantillons ont été taillés en pointe par FIB (Focused Ion Beam: Faisceau d’ions focalisés), et les données obtenues sur un microscope Titan Themis muni d’un système à 4 détecteurs SDD. L’évaluation du programme atteste qu’il permet d’obtenir des résultats précis et fiables sur les architectures 3D étudiées. Des pistes d’améliorations sont discutées en perspective d’un futur logiciel dédié au traitement de données en tomographie électronique analytiqueThe aim of this thesis is to automate the process of hyperspectral analysis for analytical electron tomography applied to nanodevices. The work presented here is focused on datasets obtained by energy-dispersive X-ray spectroscopy in a scanning transmission electron microscope (STEM-EDX). STEM-EDX tomography has benefited greatly from recent developments in electron sources such as the ‘X’-FEG (Field Emission Gun), and multiple X-ray detector systems such as the Super-X, incorporating four SSD (Silicon Drift Detectors) detectors. The technique remains however very time-consuming, and low X-ray count rates are necessary to minimize the total acquisition time and avoid beam damage during the experiment. In addition, tomographic stacks of STEM-EDX datacubes, acquired at different tilt angles, are too large to be analyzed by commercial software packages in an optimal way. In order to automate this process, we developed a code based on Hyperspy, a Python library for multidimensional data analysis. Multivariate statistical analysis techniques were employed to optimize and automate the denoising, the energy calibration and the separation of overlapping X-ray lines, with the aim to achieve quantitative, chemically sensitive volumes. Moreover, a compressed sensing based algorithm was employed to achieve high fidelity reconstructions with undersampled tomographic datasets. The code developed during this thesis was used for the 3D chemical analysis of four microelectronic nanostructures: FinFET, HEMT and GAA transistors, and a GeTe thin film for memory device applications. The samples were prepared in a needle shape using a focused ion beam, and the data acquisitions were performed using a Titan Themis microscope equipped with a super-X EDX detector system. It is shown that the code yields 3D morphological and chemical information with high accuracy and fidelity. Ways to improve the current methodology are discussed, with future efforts aiming at developing a package dedicated to analytical electron tomography
18
Gullayanon, Rutchanee. « A calibration methodology for energy dispersive X-ray fluorescence measurements based upon synthetically generated reference spectra ». Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42771.
Texte intégralRésumé :
This research developed an on-line measurement systemfor determining the amount of fluorochemicals on carpet fibers using energy-dispersive X-ray fluorescence (EDXRF).This system is designed as a complementary tool to an existingchemical burn test certified by the American Association ofTextile Chemists and Colorists (AATCC), which is performed off-line on randomly selected carpet samples and time consuming.This research reviewed XRF principles and determined parameters that affect XRF spectra such as measurement time, measurement number, X-ray tube voltage, X-ray tube current, primary beam filter, and carpet characteristics. For this application, XRF calibrations must be performed for carpets of all styles and types. However, preparing actual carpet calibration samples is expensive. This research introduced a methodology to synthetically generate reference spectra using XRF spectra from standard fluorochemical stock solution samples and from base carpet samples for each carpet type to be tested. Thus, actual, physical standards are not required for each carpet type or style. This study showed that the synthetically generated XRF spectra alone were not always sufficient to guarantee the confidence interval required by the certified AATCC test. Thus, it is recommended that for on-line implementation, burn test results should be used to create a historical data base for each carpet type to reduce margin of error for calibrations generated from the synthetic spectra.
19
Jabeen, Fauzia. « III-V semiconducting nanowires by molecular beam epitaxy ». Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3097.
Texte intégralRésumé :
2007/2008This thesis is devoted to the study of the growth of III-V nanowires (NWs) by catalyst assisted and catalyst free molecular beam epitaxy (MBE). The nanostructures have been routinely characterized by scanning electron microscopy (SEM) and, to a minor extent by transmission electron microscopy (TEM). X-ray photoemission spectroscopy (XPS), scanning photoemission microscopy (SPEM), extended X-ray absrorption fi ne structure analysis (EXAFS), photoluminescence (PL) and trans- port measurements have given an important contribution on specifi c topics. The first section of this thesis reports on GaAs, InAs, and InGaAs NWs growth by Au assisted MBE. A substrate treatment is proposed that improves uniformity in the NWS morphology. Thanks to a careful statistical analysis of the NWs shape and dimensions as a function of growth temperature and duration, evidence is found of radial growth of the NWs taking place together with the axial growth at the tip. This eff ect is interpreted in term of temperature dependent diff usion length of the cations on the NWs lateral surface. The control of the NWs radial growth allowed to grow core shell InGaAs/GaAs NWs, displaying superior optical quality. A new procedure is proposed to protect NWs surface from air exposure. This procedure allowed to perform ex-situ SPEM studies of electronic properties of the NWs. The second part of this thesis is devoted to Au-free NWs growth. GaAs and InAs NWs were successfully grown for the first time using Mn as catalyst. Incorporation of Mn in the NW is studied using EXAFS technique. It is shown that Mn atoms are incorporated in the body of GaAs NWs. Use of low growth temperature is suggested in order to improve the Mn incorporation inside GaAs NWs and obtain NWs with magnetic properties. Finally, growth of GaAs and InAs NWs on cleaved Si subtrate is demonstrated without the use of any outside metal catalyst. Two kinds of nanowires have been obtained. The experimental findings suggest that the two types of nanowires grow after di fferent growth processes.
Questa tesi e' dedicata allo studio della crescita di nanofili di semiconduttori III- V tramite epitassia da fasci molecolari (MBE) assistita da catalizzatore e senza l'uso di catalizzatori. Le nanostrutture sono state caratterizzate sistematicamente tramite microscopia elettronica a scansione (SEM), e in maniera minore microscopia elettronica in trasmissione (TEM). Altre tecniche come la spettroscopia di fotoemissione da raggi x (XPS), la microscopia da fotoemissione in scansione (SPEM), la spettroscopia di assorbimento x (in particolare la extended X-ray absorpition fine structure analysis (EXAFS)) la fotoluminescenza (PL), e il trasporto elettrico hanno dato importanti contributi su problematiche specifiche. La prima parte di questa tesi riguarda la crescita di nanofili di GaAs, InAs e InGaAs tramite MBE assistita da oro. Viene proposto un trattamento del substrato che migliora nettamente l'omogeneita' morfologica dei nanofili. Grazie ad un'attenta analisi statistica della forma e delle dimensioni dei nanofili in funzione della temperatura e del tempo di crescita e' stata dimostrata la crescita radiale dei nanofili, che avviene insieme alla crescita assiale che ha luogo alla punta del nanofilo. Le osservazioni sperimentali sono state interpretate in termini di dipendenza dalla temperatura della lunghezza di diffusione dei cationi sulle super ci laterali dei nanofili. Il controllo della crescita radiale ha permesso di crescere nanofili di InGaAs/GaAs core shell, costituiti cioe' da una anima centrale di InGaAs (core) e uno strato esterno di GaAs (shell) , che hanno dimostrato eccellente qualita' ottica. Viene quindi proposta una nuova procedura per proteggere la super ficie dei nanofili durante l'esposizione all'aria. Grazie a questa e' stato possibile realizzare ex-situ uno studio SPEM delle proprieta' elettroniche dei nanofili. La seconda parte della tesi riguarda la crescita di nanofili senza l'uso di oro. Viene per la prima volta dimostrata la possibilita' di crescere nanofili di GaAs e InAs usando il manganese come catalizzatore. L'incorporazione del Mn come impurezza nei nanofili e' stata studiata tramite EXAFS. Le misure hanno dimostrato che atomi di Mn sono effettivamente incorporate nel corpo dei nano fili. La crescita delle nanostrutture a temperatura piu' bassa potrebbe migliorare qualitativamente l'incorporazione del Mn e permettere la crescita di nanofili con proprieta' magnetiche. Viene in fine dimostrata la crescita di nanofili di GaAs e di InAs senza l'utilizzo di materiali diversi da quelli costituenti il semiconduttore. Tale risultato e' ottenuto su superfici sfaldate di silicio. Sono state osservate nanostrutture di due tipi, che sulla base dei dati sperimentali sembrano essere dovuti a due diversi meccanismi di crescita.
XXI Ciclo
1977
20
Aquilanti, Giuliana. « Challenges for energy dispersive X-ray absorption spectroscopy at the ESRF : microsecond time resolution and Megabar pressures ». Université Joseph Fourier (Grenoble), 2002. http://www.theses.fr/2002GRE10195.
Texte intégralRésumé :
La Thèse s'articule en deux parties distinctes, autour de l'exploitation des caractéristiques exceptionnelles d'une ligne de lumière d'absorption X en géométrie dispersive dans un synchrotron de troisième génération. La première partie décrit la possibilité d'effectuer des études de spectroscopie d'absorption X résolues en temps avec une résolution temporelle de l'ordre de la microseconde. L'étude de la structure de l'état excité du composé Pt2(P20sH2)44- a été choisi pour mettre au point cette technique. Dans la deuxième partie, l'adéquation entre les possibilités offertes par une ligne d'absorption X en dispersion d'énergie et les expériences à très hautes pressions obtenues dans les cellules à enclumes de diamants est mise en évidence. Outre les développements instrumentaux, cette dernière technique est illustrée par une étude combinée par diffraction et par absorption des rayon X du composé InAs sous pressionThis Thesis concerns the development of two different applications of energy-dispersive Xray absorption spectroscopy at the ESRF: time-resolved (TR) studies pu shed to the microsecond time resolution and high-pressure (HP) studies at the limit of the Megabar pressures. The work has been developed in two distinct parts, and the underlying theme has been the exploitation of the capabilities of an X-ray absorption spectrometer in dispersive geometry on a third generation synchrotron source. For TR studies, the study of the triplet excited state following a laser excitation of Ph(P20sH2)44- has been chosen to push the technique to the us time resolution. In the HP part, the suitability of the energy dispersive Xray absorption spectrometer for HP studies using diamond anvils cell is stressed. Sorne technical developments carried out on beamline ID24 are discussed. Finally, the most extensive scientific part concerns a combined X-ray absorption and diffraction study of InAs under pressure
21
Green, Heather F. « Casting no shadow : overlapping soilscapes of European-Indigenous interaction in northern Sweden ». Thesis, University of Stirling, 2012. http://hdl.handle.net/1893/13133.
Texte intégralRésumé :
The Sámi’s past activities have been documented historically from a European perspective, and more recently from an anthropological viewpoint, giving a generalised observation of the Sámi, during the study period of AD200-AD1800, as semi-nomadic hunter gatherers, with several theories suggesting that interaction with Europeans, through trade, led to the adoption of European activities by certain groups of the Sámi (Eiermann, 1923; Paine, 1957; Manker and Vorren, 1962; Bratrein, 1981; Mathiesen et al, 1981; Meriot, 1984). However, there is almost no information on the impact the Sámi had on the landscape, either before or after any adoption of European activities, and none investigating what cultural footprint or indicators would remain from Sámi or European occupation and/or activity within the typically podzolic soils of Northern Sweden. Consequently the thesis aims to contribute to the gap in knowledge through the formation of a podzol model identifying the links between anthropogenic activity and the alteration of podzol soils, and through the creation of soils based models which identify the cultural indicators associated with both Sámi and European activity; formed from the identification of cultural indicators retained within known Sámi and European sites. The methods used to obtain the information needed to achieve this were the pH and magnetic susceptibility from bulk soil samples and micromorphological and chemical analysis of thin section slides through the use of standard microscopy and X-ray fluorescence from a scanning electron microscope. The analysis revealed that the Sámi had an extremely low impact on the landscape, leaving hard to detect cultural indicators related to reindeer herding in the form of reindeer faecal material with corresponding phosphorous peaks in the thin section slides. The European footprint however, was markedly different and very visible even within the acidic soil environment. The European indicators were cultivation based and included phosphorous and aluminium peaks as well as a deepened, highly homogenised plaggen style anthropogenic topsoil rich in ‘added’ materials. An abandoned European site which visibly and chemically shows the formation of a secondary albic horizon within the anthropogenic topsoil also provides an insight into the delicate balance of cultivated soil in northern Sweden, whilst reinforcing the outputs identified in the podzol model. Due to the almost invisible Sámi footprint on the landscape, areas of overlap were impossible to identify however, there was no evidence of the adoption of European cultivation activities at any of the Sámi sites investigated. The only known area of interaction between the two cultures was an official market place which had been a Sámi winter settlement prior to its use as a market site. This site showed none of the reindeer based Sámi indicators or the cultivation based European indicators, but did contain pottery fragments which could be linked to trade or occupation. Overall, the thesis reinforces the low impact expected of the semi-nomadic Sámi and sheds light on the underlying podzolic processes influencing the anthropogenically modified soils of Northern Sweden. The podzol model is reinforced by several findings throughout the thesis and the soils based cultural indicator models for both Sámi and European activity have been successfully tested against independent entomological and palynological data and therefore provide reliable reference material for future studies.
22
Fagerland, Steffen Knut. « Investigation of Focused Ion Beam/Scanning Electron Microscope parameters for Slice and View and Energy Dispersive X-ray Spectroscopy of Embedded Brain Tissue ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25765.
Texte intégralRésumé :
This Thesis investigates the optimization of a Focused Ion Beam/Scanning Electron Microscope (FIB/SEM) Slice and View protocol of brain tissue. Using a Slice and View protocol in a Dualbeam instrument, the ion and electron beams are used in sequence to alternately mill and image the newly exposed surface of a predefined volume. This creates serial section images that may be used for 3D reconstruction. Research questions addressed include finding FIB parameters most beneficial for accurate milling of the tissue, use of different software strategies and image processing for 3D reconstruction of selected subsets enclosed within the volume sectioned, and the use of Energy Dispersive X-ray Spectroscopy for revealing the volume contents \emph{a priori} of the Slice and View. The reults showed that FIB parameters of $30kV$ and $0.9nA$ provided sufficient accuracy and consistency; that the DAB labeling protocol provided characteristics easily identifiable of the morphology of selected interneurons which were reconstructed, but was difficult to use in a generalized semi-automatic reconstruction protocol; and a model created to test EDX tracing did show potential for its use to increase protocol efficiency by narrowing down the regions of interest of the FIB block.
23
Kuei, Chun-Fu. « Transmission electron microscopy study on the formation of SiNX interlayer during InAlN growth on Si (111) substrate ». Thesis, Linköpings universitet, Tunnfilmsfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-125472.
Texte intégralRésumé :
Ternary indium aluminum nitride (InXAl1-XN) semiconductor is an attractive material with a wide-range bandgap energy varied from ultraviolet (Eg(AlN): 6.2 eV) to near infrared (Eg(InN): 0.7 eV). With tuning composition, it can be widely used to many optoelectronic device applications. In this thesis, I have studied InXAl1-XN film deposited on Si (111) substrate using natural and isotopically enriched nitrogen as reactive gas by reactive magnetron sputter epitaxy (MSE). Four series of experiments were performed, which are I. InAlN presputtering, II. InAlN sputter deposition, III. InAlN direct deposition, and IV. InAlN direct deposition using isotopically enriched nitrogen. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The θ-2θ XRD scan confirms that the designed composition x = 0.17 of InXAl1-XN film was obtained. TEM images shows that an amorphous interlayer with a thickness ranging from 1.2 nm to 1.5 nm was formed between Si substrate and InXAl1-XN film. However, high-resolution TEM shows that the interlayer actually contains partial crystalline structures. EDX line profile indicates that the chemical composition of the amorphous interlayer is silicon nitride (SiNX). By comparing d-spacing measurement of partial crystalline structures with EDX line profile, it reveals that partial SiNX crystal is formed in the interlayer. Nonetheless, the samples (IAD01, IAD02, IAD03, IAD04), grown without presputtering procedure, contain both crystalline SiNX and InXAl1-XN embedded in the amorphous interlayer. It means that SiNX and InXAl1-XN film can be directly grown on the substrate in the beginning of deposition. Moreover, the samples (IAD01, IAD03), quenched directly after deposition, have less crystalline structures in the interlayer then the samples (IAD02, IAD04), maintained at 800℃ for 20 min.
24
Gul, Sheraz. « Synthesis, Optical and Structural Characterization, and Exciton Dynamics of Doped ZnSe Nanocrystals, and, Simultaneous X-ray Emission Spectroscopy of Two Elements Using Energy Dispersive Spectrometer ». Thesis, University of California, Santa Cruz, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3630692.
Texte intégralRésumé :
Doped semiconductor quantum dots (QDs) comprise an important subclass of nanomaterials in which a small quantity of impurity is added intentionally, adding another degree of freedom to alter their size-dependent physical and electronic properties. Intense, tunable, long lived and stable photoluminescence make them quintessential candidates for many opto-electronic applications including solid-state lighting, display devices and biomedical imaging. ZnSe QDs, which are blue-emitting fluorophores, were doped with Cu+1 to redshift their photoluminescence (PL) to green region of the visible spectrum. These Cu-doped ZnSe QDs were then codoped with Al3+, Ga 3+ and In3+ to improve the PL quantum yield (QY) by eliminating the defect states originating from charge imbalance created by aliovalent doping. Codoping also resulted in further redshifting of the PL, covering most of the visible spectrum, making them potential candidates for use in solid-state lighting and as optical down converters in next generation light emitting diodes (LEDs). To better understand the optical properties of these materials, local structure around the luminescent centers was investigated by extended X-ray absorption fine structure (EXAFS). Cu was found to occupy a distorted tetrahedral site with the codopant residing in a substitutional Zn site. Based on the structural information obtained by EXAFS, density functional theory calculations (DFT) were performed to get a clear picture of the energy levels associated with the electronic transitions. Furthermore, the dynamics studies of the exciton and charge carriers were carried out to get deeper insight of the various photophysical processes involved. The fluorescence lifetime was increased approximately 10 times after doping.
The multielectron catalytic reactions often involve multimetallic clusters, where the reaction is controlled by the electronic and spin coupling between metals and ligands to facilitate charge transfer, bond formation/breaking, substrate binding, and release of products. A method was developed to detect X-ray emission signal from multiple elements simultaneously to probe the electronic structure and sequential chemistry that occurs between the elements. A wavelength dispersive spectrometer based on the von-Hamos geometry was used, that disperses Kβ emission signals of multiple elements onto an area detector, and enables an XES spectrum to be measured in a single-shot mode. This overcomes the scanning needs of the Rowland circle spectrometers, and the data is free from temporal and normalization errors, and therefore ideal to follow sequential chemistry at multiple sites. This method was applied to MnOx based electrocatalysts, and the effect of Ni addition was investigated. Electro-deposited Mn oxide catalyses oxygen-evolution reaction (OER) and oxygen-reduction reaction (ORR) at different electrochemical potentials under alkaline condition. Incorporation of Ni reduced the low valent Mn component resulting in higher average oxidation state of Mn in MnNiOx under ORR and OER conditions, when compared to MnO x under similar conditions. The reversibility of the electrocatalyst was also found to improve by the inclusion of Ni.
25
Yamane, H., T. Kawano, K. Tatsumi, Y. Fujimichi et S. Muto. « Site occupancy determination of Eu/Y doped in Ca2SnO4 phosphor by electron channeling microanalysis ». Elsevier, 2011. http://hdl.handle.net/2237/20827.
Texte intégral
26
SILVA, NETO Oscar Gomes da. « Extração e avaliação das propriedades físicas, quimicas e biológicas do gel de aloe vera para aplicação em ecografia ». Universidade Federal de Campina Grande, 2018. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1028.
Texte intégralRésumé :
Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-21T23:28:14Z
No. of bitstreams: 1
OSCAR GOMES DA SILVA NETO – DISSERTAÇÃO (UAEMa) 2015.pdf: 1645990 bytes, checksum: e448fc8b851a203983ccd784d8234090 (MD5)Made available in DSpace on 2018-06-21T23:28:14Z (GMT). No. of bitstreams: 1 OSCAR GOMES DA SILVA NETO – DISSERTAÇÃO (UAEMa) 2015.pdf: 1645990 bytes, checksum: e448fc8b851a203983ccd784d8234090 (MD5) Previous issue date: 2018-06-21
A ecografia é um dos métodos de diagnóstico por imagem mais versátil e difundido na atualidade, de aplicação relativamente simples, basear-se no fenômeno de interação de uma onda mecânica com os tecidos corporais, ou seja, observa as propriedades mecânicas dos tecidos ao longo da propagação da onda pelos mesmos, necessitando de um gel de acoplamento acústico para aumentar o contato entre a pele e o aparelho. A Aloe vera (Aloe barbadensis Miller) é uma planta suculenta perene, que desenvolve um tecido de armazenamento de água no interior das folhas, o gel, para sobreviver em zonas áridas de pluviosidade baixa ou irregular. Desta forma, este trabalho objetivou a extração do gel de Aloe vera, com subsequente análise de suas propriedades físicas, químicas e biológicas. Foram realizados testes de avaliação da sua funcionalidade para aquisição de imagens por ecografia e, por fim, realizado estudo comparativo com imagens ecográficas adquiridas com o gel de Aloe vera e com o gel comercial atualmente utilizado. O gel de Aloe Vera a 100% foi extraído da própria planta, processado e caracterizado por espectroscopia na Região do Infravermelho com Transformada de Fourier (FTIR), espectroscopia por Energia Dispersiva de raios X (EDS), Ensaio de Citotoxicidade e Ecografia. As análises foram realizadas no Laboratório de Desenvolvimento e Avaliação de Biomateriais (CERTBIO). O gel de Aloe vera quando utilizado para fins de obtenção de imagem, apresentou resultado igual ou superior às imagens obtidas com o gel comercial, podendo ter ocorrido devido a menor resistência oferecida pelo mesmo e consequentemente maior condutividade, provavelmente pela maior quantidade de íons livres, permitindo a diminuição da impedância do transdutor em relação à pele, promovendo a propagação do ultrassom desde o transdutor até os órgãos avaliados. Com base nos resultados obtidos nos ensaios de Espectroscopia na Região do Infravermelho com Transformada de Fourier, Espectroscopia por Energia Dispersiva de raios X, Citotoxicidade e Exames Ecográficos, pode-se concluir que os materiais apresentam características semelhantes, indicando que o gel de Aloe vera possa ser utilizado em exames de ultrassonografia.
Ultrasound is a diagnostic methods for more versatile and widespread image today, relatively simple application, be based on the interaction phenomenon of a mechanical wave with body tissues, ie observe the mechanical properties of tissues along the Wave propagation through the same, necessitating an acoustic coupling gel to increase the contact between the skin and the device. Aloe vera (Aloe barbadensis Miller) is a succulent perennial plant which develops a water storage tissue sheets within the gel, to survive in arid zones of low rainfall or irregular. Thus, this study aimed to extract the gel of Aloe vera, with subsequent analysis of their physical, chemical and biological properties, as well as evaluation tests were carried out of its functionality for image acquisition by ultrasound and finally performed study comparison with ultrasound images acquired with the gel of Aloe vera and commercial gel currently used. The gel of Aloe Vera 100% was extracted from the plant itself, processed and characterized by Spectroscopy in Infrared Region Fourier Transform (FTIR) Spectroscopy Energy Dispersive X-ray (EDS), Cytotoxicity and ultrasound test. The analyzes were performed at the Development Laboratory and Biomaterials Assessment (CERTBIO). The Aloe vera gel when used for the purpose of obtaining image presented results equal to or better than the images obtained with the commercial gel and this may be due to lower resistance of the same and therefore higher conductivity and this can probably allow the reduction of the impedance of the transducer relative to the skin, promoting the propagation of ultrasound from the transducer to the evaluated organs. Since based on the results obtained in tests spectroscopy in the infrared Fourier transform spectroscopy, by Energy Dispersive X-ray, ultrasound examinations and cytotoxicity, it can be concluded that the materials have similar characteristics indicative that the aloe vera gel may be used on ultrasound examination.
27
Zhang, Shuo. « The Performance and Service Life Prediction of High Performance Concrete in Sulfate and Acidic Environments ». FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2260.
Texte intégralRésumé :
Concrete substructures are often subjected to environmental deterioration, such as sulfate and acid attack, which leads to severe damage and causes structure degradation or even failure. In order to improve the durability of concrete, the High Performance Concrete (HPC) has become widely used by partially replacing cement with pozzolanic materials. However, HPC degradation mechanisms in sulfate and acidic environments are not completely understood. It is therefore important to evaluate the performance of the HPC in such conditions and predict concrete service life by establishing degradation models.
This study began with a review of available environmental data in the State of Florida. A total of seven bridges have been inspected. Concrete cores were taken from these bridge piles and were subjected for microstructural analysis using Scanning Electron Microscope (SEM). Ettringite is found to be the products of sulfate attack in sulfate and acidic condition.
In order to quantitatively analyze concrete deterioration level, an image processing program is designed using Matlab to obtain quantitative data. Crack percentage (Acrack/Asurface) is used to evaluate concrete deterioration. Thereafter, correlation analysis was performed to find the correlation between five related variables and concrete deterioration. Environmental sulfate concentration and bridge age were found to be positively correlated, while environmental pH level was found to be negatively correlated.
Besides environmental conditions, concrete property factor was also included in the equation. It was derived from laboratory testing data. Experimental tests were carried out implementing accelerated expansion test under controlled environment. Specimens of eight different mix designs were prepared. The effect of pozzolanic replacement rate was taken into consideration in the empirical equation. And the empirical equation was validated with existing bridges.
Results show that the proposed equations compared well with field test results with a maximum deviation of ± 20%. Two examples showing how to use the proposed equations are provided to guide the practical implementation. In conclusion, the proposed approach of relating microcracks to deterioration is a better method than existing diffusion and sorption models since sulfate attack cause cracking in concrete. Imaging technique provided in this study can also be used to quantitatively analyze concrete samples.
28
Gonçalves, Ligia Maria Napolitano. « Efeito da radioterapia sobre as propriedades mecânicas, químicas e morfológicas do esmalte e da dentina de dentes permanentes - Estudo in vitro ». Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/58/58135/tde-23052012-163912/.
Texte intégralRésumé :
O presente estudo teve como objetivo avaliar, in vitro, os efeitos da radiação com cobalto-60 nas propriedades mecânicas, morfológicas e químicas do esmalte e da dentina de dentes permanentes através da: 1- microdureza longitudinal; 2- microscopia eletrônica de varredura (MEV); e 3- espectroscopia de energia dispersiva de raios X (EDX). A microdureza do esmalte e da dentina (n=12 hemissecções vestibulares) foi avaliada em três profundidades (superficial, média e profunda), antes e a cada 10 Gy de irradiação, até uma dose cumulativa de 60 Gy. A morfologia do esmalte e da dentina foi avaliada por meio de MEV (n=8 hemissecções), em 2 hemissecções vestibulares irradiadas com dose cumulativa de 30 Gy, 2 hemissecções vestibulares irradiadas com dose cumulativa de 60 Gy e 4 hemissecções palatinas não irradiadas. A composição química do esmalte e da dentina foi avaliada por meio de EDX (n=4 hemissecções), utilizando-se as mesmas hemissecções previamente submetidas à MEV (com dose cumulativa de 60 Gy de irradiação, e nas hemissecções não irradiadas). Os dados foram analisados quanto à sua distribuição e submetidos à Análise de Variância a dois critérios. Para a diferenciação das médias, empregou-se o teste de Fisher. O nível de significância adotado foi de 5%. Com relação à microdureza no esmalte, pôde-se observar que houve diferença estatisticamente significante entre os grupos (p < 0,05). A microdureza no esmalte não irradiado não apresentou diferença estatisticamente significante em comparação com a do esmalte após irradiação com doses de 40, 50 e 60 Gy (p > 0,05), e apresentou-se maior que os valores de microdureza nas doses de 10, 20 e 30 Gy (p < 0,05). Com relação à microdureza nas diferentes profundidades pôde-se observar diferença significante (p < 0,05) entre elas, observando-se no esmalte superficial seus maiores valores. Na análise morfológica do esmalte observou-se que os espécimes irradiados apresentaram alterações crescentes, em função do aumento da dose de radiação, em comparação ao esmalte não irradiado. A porção interprismática tornou-se mais evidente após as doses de 30 e 60 Gy. Em relação à microdureza da dentina, pôde-se observar que houve diferença significante entre os grupos (p < 0,05). A microdureza na dentina não irradiada não apresentou diferença estatisticamente significante em comparação com a microdureza na dose de 40 Gy (p > 0,05) e apresentou valores superiores aos observados nas doses de 10, 20, 30, 50 e 60 Gy (p < 0,05). Em relação à microdureza nas diferentes profundidades avaliadas pôde-se observar diferença significante (p < 0,05) entre elas, sendo que a dentina média apresentou seus maiores valores. Na análise morfológica da dentina observou-se a presença de fendas na estrutura dentinária, túbulos dentinários colabados/destruídos e fragmentação das fibras colágenas nas doses de 30 e 60 Gy, sendo as alterações mais intensas com aumento da dose de irradiação, para todas as regiões analisadas, em comparação à dentina não irradiada. Na análise química do esmalte e da dentina irradiados observou-se discreto aumento de oxigênio (O) e diminuição de fósforo (P) e cálcio (Ca), em comparação aos espécimes não irradiados. Os resultados permitiram concluir que a radioterapia não influenciou a microdureza do esmalte, como um todo, entretanto, quando analisou-se nas diferentes profundidades do esmalte, verificou-se um aumento da microdureza na região superficial. Na dentina, a radioterapia ocasionou diminuição da microdureza após praticamente todas as doses de radiação, em comparação à dentina não irradiada, sendo que na região da dentina média observaram-se seus menores dos valores. As alterações morfológicas das estruturas do esmalte e da dentina foram crescentes com o aumento das doses de irradiação observando-se a porção interprismática mais evidente, presença de fendas e túbulos dentinários colabados/destruídos e fragmentação progressiva das fibras colágenas. Quimicamente, após a irradiação, tanto no esmalte como na dentina, observouse um discreto aumento na porcentagem de oxigênio e redução nas porcentagens de fósforo e cálcio.The present study had as objective to evaluate, in vitro, the effect of the radiation of 60 Cobalt (Co 60) in the mechanical, morphological and chemical properties of the enamel and of the dentine of permanent teeth by means of: 1- longitudinal microhardness; 2- scanning electron microscopy (SEM); and 3; energy dispersive X-ray spectroscopy (EDX). The microhardness of the enamel and of the dentine (n = 12 vestibular hemisections) was evaluated in three depths (superficial, medium and deep), before and at each 10 Gy of irradiation, until a total cumulative dose of 60 Gy. The morphology of the enamel and of the dentine was evaluated by means of a SEM (n = 8 hemisections), in 2 irradiated vestibular hemisections with total cumulative dose of 30 Gy, 2 irradiated vestibular hemisections with total cumulative dose of 60 Gy and 4 not irradiated palatine hemisections (control). The chemical composition of the enamel and of the dentine was evaluated by means of EDX (n = 4 hemisections), using the same hemisections previously submitted to SEM (with cumulative dose of 60 Gy of irradiation, and in the not irradiated hemisections). The data were analyzed about their distribution and submitted to the Analysis of Variance at two criteria. For the differentiation of the averages, the test of Fisher was used. The level of significance adopted was of 5%. About the longitudinal microhardness in the enamel, it was possible to be observed that there was no statistically significant difference between the groups (p < 0,05). The microhardness in the not irradiated enamel was similar to the enamel after the irradiation with doses of 40, 50 and 60 Gy (p > 0,05) and higher than the microhardness values in the doses of 10, 20, e 30 Gy (p < 0,05). About the microhardness in the different depths it was observed significant difference (p < 0,05) between them, being observed in the superficial enamel the greatest values of microhardness. In the morphological analysis of the enamel it was observed that the irradiated specimens presented growing alterations, due to the increase of the radiation dose, comparing to the not irradiated enamel. There was no difficulty in observing the prisms and the crystals after the irradiation, however the interprismatic portion became more evident after the radiation doses of 30 and 60 Gy. About the longitudinal microhardness of the dentine, it could be observed that there was significant difference between the groups (p < 0,05). The microhardness of the not irradiated dentine was not statistically significant compared to the microhardness in the dose of 40 Gy (p > 0,05) and it presented higher values to the observed ones in the doses of 10, 20, 30, 50 and 60 Gy (p < 0,05). About the relation to the microhardness in the different evaluated depths it was possible to observe significant difference (p < 0,05) among them, being that the medium dentine presented the highest values of microhardness. In the morphological analysis of the dentine it was observed the presence of cracks in the dentine structure, collapsed/destroyed dentine tubules and fragmentation of the collagen fibers in the doses of 30 and 60 Gy, being the alterations more intense with the increase of the dose of irradiation, for all the analyzed regions, comparing to the not irradiated dentine. In the chemical analysis of the irradiated enamel and the dentine it was observed the slight increase of oxygen (O) and decrease of phosphorus (P) and Calcium (Ca), comparing to the not irradiated specimens. The result allowed to be concluded that the radiotherapy occasioned the decrease of the microhardness of the enamel after the doses from 10 to 30 Gy, but in the following doses there was an increase of the microhardness, which became similar to the not irradiated enamel, being that in the superficial region it was observed the biggest increase of the microhardness. In the dentin, the radiotherapy caused decrease of the microhardness after practically all doses of radiation, comparing to the not irradiated dentine, being that in the region of the medium dentine the lowest values of microhardness were observed. The morphological alterations of the enamel and of the dentine structure were growing with the increase of the radiation doses observing the more evident interprismatic portion, presence of cracks and collapsed/destroyed dentine tubules and progressive fragmentation of collagen fibers. Chemically, after the irradiation, not only in the enamel but also in the dentin, it was observed a slight increase of percentage of the oxygen and decrease in the percentages of phosphorus and calcium.
29
Lejonklo, Caroline. « Friction and wear study of lean powder metallurgy steel in a lubricated sliding contact ». Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-390557.
Texte intégralRésumé :
A fairly new technology used to produce metallic components is powder metallurgy (PM). Among the advantages with this technique are decreased cost of production for complex-shaped parts, new alloys are made possible, reduced end processing, less material loss, and vibrational damping effects. The downside is the number of pores created which can alter the tribological properties of the material. The focus of this report is to investigate how lean PM steel behaves under tribological contacts. Friction and wear will be investigated using a pin-on-disc setup to mimic the sliding part of a gear tooth mesh. Previous studies show that the amount of wear, and if the wear increases or decreases with increased density is dependent on the degree of porosity and the pore size. This means that the wear might be minimized by optimizing the number of pores in the material and their shape and size. The result of this study shows that the friction coefficient decreases with increasing density. The wear coefficient show signs of the same correlations but further tests are needed. The main wear comes from adhesive wear, with signs of abrasive wear. The amount of abrasive wear seems to increase with an increase in density, supporting previous studies claiming that pores can trap wear debris and decrease the number of abrasive particles in the contact.
30
Luong, Minh Anh. « Etude de la diffusion thermique de l'Aluminium dans des nanofils de Germanium et en alliages de SixGe1-x en utilisant la microscopie électronique en transmission in situ ». Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY050.
Texte intégralRésumé :
Les nanofils semi-conducteurs suscitent un intérêt croissant en raison de leur potentiel pour de nouvelles applications dans les transistors à effet de champ, les photodétecteurs et les biocapteurs. En particulier, la géométrie des nanofils offre la possibilité de fabriquer des hétérostructures axiales auxquelles il est facile d’accéder électriquement par des contacts pris aux extrémités. Selon les dimensions et la composition des hétérostructures, les porteurs peuvent subir des effets de confinement quantique, permettant de fabriquer des boites ou des disques quantiques connectés électriquement. Ainsi, la formation de contacts en silicide ou en germanide, via une réaction à l'état solide activée thermiquement entre un métal et un nanofil de Si ou de Ge, a suscité beaucoup d'intérêt en raison de son avantage pour la fabrication de dispositifs à canal court à partir de nanofils fait par croissance ‘bottom up’, qui parait plus aisé et moins couteux qu’une approche par lithographie et gravure du style ‘top down’. L'avantage de cette approche est que lors du chauffage, le métal pénètre dans le nanofil semi-conducteur aux deux extrémités, créant une région (inter) métallique. Si le processus est bien contrôlé et arrêté au bon moment, il ne reste qu'une mince section de semi-conducteur entre les contacts métalliques, ce qui permet de fabriquer des boites ou des disques quantiques mis en contact électriquement dans des structures filaires en une seule étape de fabrication. La diffusion à l'état solide induite thermiquement de l’Al dans un nanofil de Ge est un système prometteur car, contrairement à d'autres combinaisons métal-semi-conducteur ou une phase intermétallique est formée, une phase monocristalline d’Al pur est créée dont l’interface avec le nanofil de Ge est nette. De plus, la combinaison du couplage spin-orbite intrinsèquement fort du Ge et les propriétés supraconductrices de l'Al font de ce système une plate-forme prometteuse pour l'étude de dispositifs semi-conducteurs hybrides supraconducteurs qui pourraient être un des éléments constitutifs potentiels des dispositifs d'interférence quantique supraconducteurs (SQUID). Le défi abordé dans cette thèse est d'étudier la réaction d'échange de l'aluminium induit thermiquement à la fois dans les nanofils pur de Ge et d'alliage SixGe1-x en utilisant les techniques de microscopie électronique à transmission (TEM) in situ, afin de permettre une meilleure compréhension et un meilleur contrôle des mécanismes impliqués dans la réactionSemiconductor nanowires are receiving widespread interests for their novel applications in field-effect transistors, photodetectors and biosensors. The nanowire geometry provides an interesting possibility to fabricate axial heterostructures that can be easily accessed electrically by contacting the NW edges. Depending on the size, material and composition of the heterostructure, carriers can experience quantum confinement effects, allowing to fabricate quantum dots or quantum disks inside the NW. Recently, the formation of Silicide or Germanide contacts via a thermally activated solid state reaction between the metal and Si or Ge NW has drawn significant attention because of its great advantages for fabricating short channel devices from bottom up grown NWs rather than complex and high-cost photolithography top-down approaches. The advantage of this approach is that upon heating a metal enters a semiconducting NW at both ends, creating an (inter)metallic region in the NW. If the process is well controlled and stopped at the right moment, only a thin section of semiconductor is left between metallic contacts, allowing to fabricate electrically contacted quantum-dot in a wire structures in a single fabrication step. Al/Ge NW thermal induced solid-state diffusion is a promising system since, in contrast to other metal-semiconductor combinations, no intermetallic phase is formed and a pure monocrystalline Al NW is created with a very sharp interface with the remaining Ge NW. Moreover, the combination of the intrinsically strong spin−orbit coupling in Ge and the superconducting properties of Al, make this system a promising platform to study hybrid superconductor-semiconductor devices that could be potential building blocks for superconducting quantum interference devices (SQUIDs). The challenge addressed in this PhD is to study the thermally induced exchange reaction of Al in both pure Ge as well as SixGe1-x alloy NWs using in-situ observations in a transmission electron microscope (TEM), to allow better understanding and control of the mechanisms involved in the reaction
31
Trueman, Anthony Roger. « Characterization and corrosion studies of high carbon tool steel/tungsten carbide metal matrix composites ». Thesis, Queensland University of Technology, 1999.
Trouver le texte intégral
32
Schilling, Sibylle. « Liquid in situ analytical TEM : technique development and applications to austenitic stainless steel ». Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/liquid-in-situ-analytical-tem-technique-development-and-applications-to-austenitic-stainless-steel(fd490551-7d7a-4b2e-9b1f-917b5f8165b3).html.
Texte intégralRésumé :
Environmentally-assisted cracking (EAC) phenomena affect the in-service behaviour of austenitic stainless steels in nuclear power plants. EAC includes such degradation phenomena as Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Factors affecting EAC include the material type, microstructure, environment, and stress. This is an important degradation issue for both current and Gen III+ light water reactors, particularly as nuclear power plant lifetimes are extended ( > 60 years). Thus, it is important to understand the behaviour of the alloys used in light water reactors, and phenomena such as SCC to avoid failures. Although there is no agreement on the mechanism(s) of SCC, the importance of localized electrochemical reactions at the material surface is widely recognised. Considerable research has been performed on SCC and CF crack growth, but the initiation phenomena are not fully understood. In this project, novel in situ analytical TEM techniques have been developed and applied to explore localised reactions in Type 304 austenitic stainless steel. In situ transmission electron microscopy has become an increasingly important and dynamic research area in materials science with the advent of unique microscope platforms and a range of specialized in situ specimen holders. In metals research, the ability to image and perform X-ray energy dispersive spectroscopy (XED) analyses of metals in liquids are particularly important for detailed study of the metal-environment interactions with specific microstructural features. To further facilitate such studies a special hybrid specimen preparation technique involving electropolishing and FIB extraction has been developed in this thesis to enable metal specimens to be examined in the liquid cell TEM specimen holder using both distilled H2O and H2SO4 solutions. Furthermore, a novel electrode configuration has been designed to permit the localized electrochemical measurement of electron-transparent specimens in the TEM. These novel approaches have been benchmarked by extensive ex situ experiments, including both conventional electrochemical measurements and microcell measurements. The results are discussed in terms of validation of in situ test data as well as the role of the electron beam in the experiments. In situ liquid cell TEM experiments have also explored the localized dissolution of MnS inclusions in H2O, and correlated the behaviour with ex situ experiments. Based on the research performed in this thesis, in situ liquid cell and in situ electrochemical cell experiments can be used to study nanoscale reactions pertaining to corrosion and localized dissolution leading to "precursor" events for subsequent EAC phenomena.
33
Seidel, Falko. « Dünne Siliziumschichten für photovoltaische Anwendungen hergestellt durch ein Ultraschall-Sprühverfahren ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-159507.
Texte intégralRésumé :
Der hauptsächliche Bestandteil dieser Arbeit ist die Entwicklung einer kostengünstigen Methode zur Produktion von auf Silizium basierenden Dünnschicht-Solarzellen durch Sprühbeschichtung. Hier wird untersucht inwiefern sich diese Methode für die Herstellung großflächiger photovoltaische Anlagen eignet. Als Grundsubstanz für entsprechende Lacke werden Mischungen aus Organosilizium und nanokristallines Silizium verwendet. Eine Idee ist das Verwenden von Silizium-Kohlenstoff-Verbindungen als Si-Precursor (Cyclo-, Poly-, Oligo- und Monosilane). In jedem Fall, Organosilizium und Silizium- Nanopartikel, ist eine Umwandlung durch äußere Energiezufuhr nötig, um die Precursor-Substanz in photovoltaisch nutzbares Silizium umzuwandeln. Die Versuchsreihen werden mithilfe photothermischer Umwandlung (FLA-„flash lamp annealing“, einige 1 J/cm² bei Pulslängen von einigen 100 μs) unter N2-Atmosphäre durchgeführt. Zur Bereitstellung eines auf Laborgröße skalierten Produktionsprozesses wurden ein Spraycoater, eine Heizplatte, ein Blitzlampensystem und ein In-Line Ellipsometer in einem Aufbau innerhalb einer Glovebox unter N2-Atmosphäre kombiniert. Die Gewinnung von Proben und deren Charakterisierung fand in enger Zusammenarbeit mit den beiden Arbeitsgruppen der anorganischen Chemie und der Koordinationschemie an der TU-Chemnitz statt.
Die eingesetzten Charakterisierungsmethoden sind Raman-Spektroskopie, Infrarotspektroskopie, Rasterelektronenmikroskopie, Transmissionselektronenmikroskopie, Elektronenbeugung, Röntgenbeugung, energiedispersive Röntgenspektroskopie, Rasterkraftmikroskopie und elektrische Charakterisierung wie die Aufnahme von Strom- Spannungs-Kennlinien und Widerstandsmessung per Vierpunktkontaktierung.
34
Guettler, Barbara Elisabeth. « Effect of Thermal and Chemical Treatment of Soy Flour on Soy-Polypropylene Composite Properties ». Thesis, 2012. http://hdl.handle.net/10012/6702.
Texte intégralRésumé :
Soy flour (SF), a by-product of the soybean oil extraction processing, was investigated for its application in soy-polypropylene composites for interior automotive applications. The emphasis of this work was the understanding of this new type of filler material and the contribution of its major constituents to its thermal stability and impact properties. For this reason, reference materials were selected to represent the protein (soy protein isolate (SPI)) and carbohydrate (soy hulls (SH)) constituents of the soy flour. Additional materials were also investigated: the residue obtained after the protein removal from the soy flour which was called insoluble soy (IS), and the remaining liquid solution after acid precipitation of the proteins, containing mostly sugars and minerals, which was called soluble sugar extract (SSE).
Two treatments, potassium permanganate and autoclave, were analyzed for their potential to modify the properties of the soy composite materials. An acid treatment with sulfuric acid conducted on soy flour was also considered.
The soy materials were studied by thermogravimetric analysis (TGA) under isothermal (in air) and dynamic (in nitrogen) conditions. SPI had the highest thermal stability and SSE the lowest thermal stability for the early stage of the heating process. Those two materials had the highest amount of residual mass at the end of the dynamic TGA in nitrogen. The two treatments showed minimal effect on the isothermal thermal stability of the soy materials at 200 ??C. A minor improvement was observed for the autoclave treated soy materials.
Fourier transformed infrared (FTIR) spectroscopy indicated that the chemical surface composition differed according to type of the soy materials but no difference could be observed for the treatments within one type of soy material.
Contact angle analysis and surface energy estimation indicated differences of the surface hydrophobicity of the soy materials according to type of material and treatment. The initial water contact angle ranged from 57 ?? for SF to 85 ?? for SH. The rate of water absorption increased dramatically after the autoclave treatment for IS and SPI. Both materials showed the highest increase in the polar surface energy fraction. In general, the major change of the surface energy was associated with change of the polar fraction. After KMnO4 treatment, the polar surface energy of SF, IS and SPI decreased while SH showed a slight increase after KMnO4 treatment. A relationship between protein content and polar surface energy was observed and seen to be more pronounced when high protein containing soy materials were treated with KMnO4 and autoclave. Based on the polar surface energy results, the most suitable soy materials for polypropylene compounding are SPI (KMnO4), SH, and IS (KMnO4) because their polar surface energy are the lowest which should make them more compatible with non-polar polymers such as polypropylene.
The soy materials were compounded as 30 wt-% material loading with an injection moulding grade polypropylene blend for different combinations of soy material treatment and coupling agents. Notched Izod impact and flexural strength as well as flexural modulus estimates indicated that the mechanical properties of the autoclaved SF decreased when compared to untreated soy flour while the potassium permanganate treated SF improved in impact and flexural properties. Combinations of the two treatments and two selected (maleic anhydride grafted polypropylene) coupling agents showed improved impact and flexural properties for the autoclaved soy flour but decreased properties for the potassium permanganate treated soy flour. Scanning electron microscopy of the fractured section, obtained after impact testing of the composite material, revealed different crack propagation mechanisms for the treated SF. Autoclaved SF had a poor interface with large gaps between the material and the polypropylene matrix. After the addition of a maleic anhydride coupling agent to the autoclaved SF and polypropylene formulation, the SF was fully embedded in the polymer matrix. Potassium permanganate treated SF showed partial bonding between the material and the polymer matrix but some of the material showed poor bonding to the matrix. The acid treated SF showed cracks through the dispersed phase and completely broken components that did not bind to the polypropylene matrix.
In conclusion, the two most promising soy materials in terms of impact and flexural properties improvement of soy polypropylene composites were potassium permanganate treated SF and the autoclaved SF combined with maleic anhydride coupling agent formulation.
35
Liu, Chen-Yen, et 劉俊延. « Evaluation of Scanning Electron Microscopy-Energy Dispersive X-Ray Spectrometer (SEM-EDX) for Detection of Heavy Metals in Himematsutake ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/55795130915924905524.
Texte intégralRésumé :
碩士國立中興大學
植物病理學系所
100
Himematsutake (Agaricus blazei Murill) is a popular edible mushroom in the world. Recently, the over accumulation of heavy metals in the himematsutake had been paid attention in Taiwan. Several methods can be used to detect the accumulation of heavy metals in biological materials; however, these methods are time consuming. For detecting the heavy metals and its distribution in fruit body of himematsutake rapidly, the scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDX) was used to analyze eight heavy metals of Cr, Ni, Cu, Zn, As, Cd, Hg and Pb in pileus and stipe of fruiting body by pieced and powdery types. Moreover, the atomic percentage of these heavy metals in pileus and stipe were be confirmed by ICP-MS. In this study, the specimens of himematsutake were collected from Taichung (USA and Japanese strain), Changhua (Japanese and Taiwanese strain), Nantou and China. The results of pieced analysis showed that the accumulation of Ni (0.040%) and As (0.009%) in pileus of fruiting body of USA strain from Taichung were significantly higher than in stipe; however, the accumulation of Hg (0.044%) and Pb (0.043%) in stipe of fruiting body of USA strain were significantly higher than pileus. The other side, the accumulation of As (0.008%) in pileus of fruiting body of Japanese strain from Taichung was significantly higher than in stipe; meanwhile, the accumulation of Ni (0.015%), Cu (0.054%), Zn (0.017%), Hg (0.034%)and Pb (0.030%) in stipe of fruiting body of Japanese strain were significantly higher than pileus. The pieced analysis of Japanese strain from Changhua indicated that Cu (0.044%), Hg (0.092%) and Pb (0.069%) in pileus were significantly higher than in stipe, and As (0.013%) and Cd (0.015%) in stipe were significantly higher than in pileus. However, the pieced analysis of Taiwanese strain from Changhua revealed that Ni (0.023%), Cu (0.041%), Zn (0.024%), As (0.013%) and Hg (0.114%) in pileus were significantly higher than in stipe. The pieced analysis of himematsutake from Natou showed that accumulation of Hg (0.088%) in pileus was significantly higher than in stipe, and the accumulation of Ni (0.029%), Cu (0.060%), Zn (0.030%) and Cd (0.025%) in stipe were significantly higher than in pileus. The pieced analysis of himematsutake from China indicated that accumulation of As (0.015%) and Hg (0.067%) in pilues were significantly higher than in stipe, and Cr (0.017%), Ni (0.023%), Cu (0.048%), Cd (0.015%) and Pb (0.052%) in stipe were significantly higher than in pileus. The results of powdery analysis showed that the accumulation of Cu (0.149%), Zn (0.059%), Hg (0.127%) and Pb (0.076%) in pileus of fruiting body of USA strain from Taichung were significantly higher than in stipe; however, the accumulation of As (0.016%), Hg (0.102%) and Pb (0.065%) in pileus of fruiting body of Japanese strain was significantly higher than in stipe. The powdery analysis of Japanese strain from Changhua indicated that Hg (0.087%) in pileus was significantly higher than in stipe, and As (0.050%) in stipe was significantly higher than in pileus. However, the powdery analysis of Taiwanese strain from Changhua revealed that Ni (0.040%), Hg (0.148%) and Pb (0.095%) in pileus were significantly higher than in stipe, and the accumulations of Cr (0.023%) and Cd (0.037%) in stipe were significantly higher than in pileus. The powdery analysis of himematsutake from Natou showed that accumulation of Pb (0.061%) in pileus wa significantly higher than in stipe. The powdery analysis of himematsutake from China indicated that accumulation of As (0.021%), Hg (0.101%) and Pb (0.076%) in pilues were significantly higher than in stipe. For ICP-MS analysis, 0.25 g of pileus and stipe of fruiting body were used for analysis. The results showed that the concentration of Cu (52.263 mg/kg), Zn (164.820 mg/kg), As (1.440 mg/kg), Cd (6.158 mg/kg) and Hg (0.178 mg/kg) in pileus of fruiting body of USA strain from Taichung were significantly higher than in stipe; however, the concentration of Cu (71.975 mg/kg), As (0.450 mg/kg) and Pb (0.260 mg/kg) in pileus of fruiting body of Japanese strain were significantly higher than in stipe. The Japanese strain from Changhua indicated that the concentration of Cu (647.847 mg/kg), Zn (121.450 mg/kg), As (2.270 mg/kg) and Hg (0.130 mg/kg) in pileus were significantly higher than in stipe; meanwhile, the is of Taiwanese strain showed that the concentration of Cu (78.553 mg/kg), Zn (214.230 mg/kg), As (1.418 mg/kg), Cd (19.530 mg/kg) and Hg (0.125 mg/kg) in pileus were significantly higher than in stipe. The analysis of himematsutake from Natou did not show significantly different between pileus and stipe of fruiting bodies. The analysis of himematsutake from China indicated that concentration of Cu (53.460 mg/kg) and Zn (124.310 mg/kg) in pilues were significantly higher than in stipe. For comparing the accumulation and distribution of heavy metals in basidiospore, pilues and stipe, the powdery analysis and ICP-MS analysis were be done. The powdery analysis showed that the heavy metals could be accumulated in basidiospores with lower atomic percentage than in pilues or stipe. Specially, Zn, Hg, and Pb were significantly different among basidiospores, pilues and stipe. Moreover, the sawdust analysis showed that the accumulations of certain heavy metals in fruiting bodies were higher than in sadust. The atomic percentage and concentration of Cu were higher in fruiting bodies than in sawdust. In this study, the analyses results from EDX were compared with the results from ICP-MS. According to correlation analysis, the atomic percentage of As, Cd and Hg based on pieced analysis have positive relationship with the ICP-MS analysis, and the coefficient of As, Cd and Hg were 0.841, 0.672 and 0.497, respectively. The other sides, the atomic percentage of Zn, As, Cd and Pb based on powdery analysis have positive relationship with the ICP-MS analysis, and the coefficient of Zn, As, Cd and Pb were 0.039, 0.277, 0.037 and 0.080. Based on the results, the EDX has potential to detect the eight heavy metals in himematsutake rapidly, and the powdery analysis might better than pieced analysis.
36
« Determination of Fe, Cu and Zn in human plasma by energy dispersive X-ray fluorescence spectrometry ». Chinese University of Hong Kong, 1993. http://library.cuhk.edu.hk/record=b5887819.
Texte intégralRésumé :
by Chan Wing-yee.Thesis (M.Phil.)--Chinese University of Hong Kong, 1993.
Includes bibliographical references (leaves 93-95).
ACKNOWLEDGEMENT --- p.i
ABSTRACT --- p.ii
Chapter CHAPTER 1 --- INTRODUCTION --- p.1
Chapter 1.1 --- General Introduction --- p.1
Chapter 1.2 --- "Clinical Significance of Fe, Cu and Zn" --- p.2
Chapter 1.3 --- Alternative Methods of Analysis --- p.5
Chapter 1.4 --- Principles of Energy Dispersive X-ray Fluorescence Spectrometry --- p.11
Chapter 1.5 --- Research Plan --- p.20
Chapter CHAPTER 2 --- EXPERIMENTAL --- p.22
Chapter 2.1 --- Energy Dispersive X-ray Fluorescence Analysis --- p.22
Chapter 2.1.1 --- Apparatus --- p.22
Chapter 2.1.2 --- Reagents --- p.25
Chapter 2.1.3 --- Procedure --- p.28
Chapter 2.2 --- Atomic Absorption Spectrometric Analysis --- p.32
Chapter 2.2.1 --- Apparatus --- p.32
Chapter 2.2.2 --- Reagents --- p.32
Chapter 2.2.3 --- Procedure --- p.34
Chapter CHAPTER 3 --- RESULTS AND DISCUSSION --- p.38
Chapter 3.1 --- Optimisation of Excitation Conditions --- p.38
Chapter 3.1.1 --- Effect of Filter --- p.38
Chapter 3.1.2 --- Effect of Tube Voltage --- p.43
Chapter 3.1.3 --- Effect of Tube Current --- p.44
Chapter 3.2 --- Optimisation of Preconcentration Procedure --- p.46
Chapter 3.2.1 --- Effect of Sample Area and Collimator Size --- p.46
Chapter 3.2.2 --- Effect of pH --- p.51
Chapter 3.2.3 --- Effect of Ligand Concentration --- p.54
Chapter 3.2.4 --- Effect of Mixing Time --- p.57
Chapter 3.2.5 --- Effect of Standing Time --- p.59
Chapter 3.2.6 --- Study of Sample Homogeneity --- p.61
Chapter 3.3 --- Optimisation for Deproteination --- p.63
Chapter 3.3.1 --- Effect of Different Protein Precipitants --- p.63
Chapter 3.3.2 --- Effect of Trichloroacetic Acid Concentration --- p.65
Chapter 3.3.3 --- Effect of Hydrochloric Acid Concentration --- p.67
Chapter 3.3.4 --- Effect of Temperature --- p.69
Chapter 3.3.5 --- Effect of Incubation Time --- p.71
Chapter 3.4 --- Study of Blanks --- p.74
Chapter 3.5 --- Construction of Calibration Curves --- p.77
Chapter 3.6 --- Determination of Detection Limit and Sensitivity --- p.84
Chapter 3.7 --- Accuracy and Reproducibility Tests --- p.86
Chapter 3.8 --- Parallel Check --- p.89
Chapter CHAPTER 4 --- CONCLUSION --- p.92
REFERENCES --- p.93
37
汪毓人. « Identification of Automotive Paint Chips by Pyrolysis/ Gas Chromatography (Py/GC) and Scanning Electron Microscopy/ Energy Dispersive X-Ray Analysis (SEM/EDX) ». Thesis, 1994. http://ndltd.ncl.edu.tw/handle/08134902094273720299.
Texte intégral
38
汪毓人. « Identification of Automitive Paint Chips by Pyrolysis/ Gas Chromatography (Py/GC) and Scanning Electron Microscopy/ Energy Dispersive X-Ray Analysis (SEM/EDX) ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/jjepa9.
Texte intégral
39
Lumka, Mandisile. « Chemical characterisation of atmospheric aerosols in Soweto, Bethlehem and Thohoyandou using energy dispersive x-ray fluorescence spectroscopy and ion chromatography ». Thesis, 2012. http://hdl.handle.net/10210/4491.
Texte intégralRésumé :
M.Sc.Aerosol samples were collected at stations using simple filter unit, loaded with a 4 7 mm diameter pore size Nuclepore membrane filter. The sampling duration was 24 hours for each sample, with the total of 11 samples: seven for Thohoyandou and four for Bethlehem. The samples were analyzed with energy dispersive X-ray fluorescence spectrometry for up to 20 elements. Comparison for elemental concentrations of the data showed that the samples fall into three clusters on average (major: Ca, Cl, Si. S, Fe and AI; intermediate: K, Ti, Pb, Brand Zn; minor: Mn, Cr, As, Sr, Ni and Cu), with the samples collected from Bethlehem having high concentrations in all clusters. High concentrations in the samples collected on Bethlehem were attributed to entrainement of dust particles during the dry winter period. The results also show that the elements are associated with anthropogenic emissions. Therefore, the sampling station at Thohoyandou is considered as a background station due to the low aerosol concentration. The aerosol concentration levels at Thohoyandou can be attributed to biogenic sources because of the large presence of large forest areas in the region and in the vicinity of the sampling location. The samples collected in both regions reveal highly enriched sulphur, chlorine, zinc and lead. It is clearly proved that these elements come from local soil. Chromium and copper were both slightly enriched in Thohoyandou, but the concentration data for these two elements are not available. However it is supposed that these elements come from local soil as well. In another aerosol analysis, passive (diffusive) samplers were used to measure concentration levels for sulphur dioxide and nitrogen dioxide. The measurement campaign was carried out from Soweto in Johannesburg and Bohlokong in Bethlehem with the campaign lasting for two months during the w~nter season. A very clear result derived for sulphur dioxide was the dominating source contribution from use of coal for heating and cooking in both areas. For nitrogen dioxide, it was found that contribution from traffic in highly populated areas and from industrial activities in the neighbourhood of the two areas was the source. The role played by wood burning, is also another additional source used for domestic heating and even cooking.
40
Smoker, Meghan Grace. « Glass population study and discrimination of glass samples using Glass Refractive Index Measurement III and scanning electron microscopy/energy dispersive X-ray spectroscopy ». Thesis, 2019. https://hdl.handle.net/2144/36607.
Texte intégralRésumé :
Glass is a hard, amorphous, and transparent or translucent substance, and it is examined in forensic science to place a person or object at a scene or with a victim when a crime is committed. Due to its brittle nature when combined with some force, glass is often broken, and is then submitted as a type of trace evidence to a crime laboratory in cases such as hit and runs, breaking and enterings, and homicides. Broken glass is most often obtained from bottles, windows, doors, and automobiles, and can easily be found on the street. Previous published research has examined known samples of glass and compared these samples with their known categories or types of glass. In this current research, a population study was conducted based on the collection and analysis of broken glass with unknown origins in Boston, MA. Glass samples (n=100) were collected from the streets and sidewalks around Boston neighborhoods, and an analytical scheme, constructed by the Boston Police Department Crime Laboratory (Boston, MA, USA), was utilized for every sample. This analytical scheme included physical characteristics, such as color, transparency, thickness, curvature and the observance of UV fluorescence. Further instrumental analysis was performed using the Glass Refractive Index Measurement system (GRIM3®) for the measurement of refractive index and the Scanning Electron Microscope and Energy Dispersive Spectroscopy (SEM/EDS) for elemental composition of each sample. Refractive index varies with glass depending on the manufacturing process and its added components and is defined as the ratio of the speed of light in a vacuum to the speed of light in the substance. Using an SEM/EDS it was possible to qualitatively determine the elemental components in each unknown glass sample. Using this analytical scheme, it may be possible to distinguish every unknown sample of glass from each other using differences in physical, optical, and elemental characteristics. This study showed the differences observed in a population of glass within the city of Boston, which ultimately could help with better statistics for testimony when asked about the significance of determining an inclusion or exclusion with casework samples.
41
Riego, Daniela Alejandra. « Análisis de contenido de fósforo en cáncer mamario por microfluorescencia de rayos X ». Bachelor's thesis, 2022. http://hdl.handle.net/11086/23640.
Texte intégralRésumé :
Tesis (Lic. en Física)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2022.En el presente trabajo, se ha implementado el Microanálisis por Fluorescencia de Rayos X para el estudio de tejidos neoplásicos. Esta técnica permite un análisis multielemental simultáneo no destructivo, simplificando la tarea laboriosa que implica el análisis elemental tradicional por histoquímica. En particular la micro-XRF permite el monitoreo de fósforo cuya presencia está asociada a microcalcificaciones y al metabolismo tumoral. El fósforo, muestra un incremento significativo en tumores malignos por lo que recientemente se lo ha empezado a emplear como posible biomarcador en modelos de prognosis del cáncer de mama. Estudios preliminares llevados a cabo por el grupo de investigación del presente trabajo han mostrado la viabilidad de la metodología propuesta particularmente aplicada en la determinación de fósforo.
In the present work, the X-Ray Fluorescence Microanalysis (micro-XRF) was implemented for the study of neoplastic tissues. Through this non-destructive technique, precise quantification of phosphorus and calcium in neoplasms of a murine model of breast cancer was achieved with the purpose of being able to distinguish malignant and benign lesions according to the variety of calcified crystals and also using phosphorus content as an indicator of tumor activity and progression. The experimental tasks and data processing processes were further supported by the simulation of radiation transport by Monte Carlo techniques using the open-source program XMI-MSIM.
Fil: Riego, Daniela Alejandra. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.
42
Silva, Sara Margarida Jorge da. « Caracterização Material e Temporal dos Túmulos da Rainha Santa Isabel e de sua Neta, Infanta D. Isabel ». Master's thesis, 2019. http://hdl.handle.net/10316/88038.
Texte intégralRésumé :
Dissertação de Mestrado em Química Forense apresentada à Faculdade de Ciências e TecnologiaCom esta dissertação, pretendeu-se analisar o historial/material dos túmulos daRainha Santa Isabel e de sua neta, tendo em conta a cronologia bibliográfica.Este estudo incidiu, em particular, na análise da estratigrafia de amostras recolhidas,nomeadamente da tampa do túmulo da Rainha Santa (TRS) e túmulo da neta da RainhaSanta (TNRS). Posteriormente, foram também analisadas amostras de outras peças paraservir como meio de comparação com as faces laterais respetivas.Os resultados obtidos permitem formular hipóteses sobre janelas temporais para aexecução das várias decorações dos dois túmulos, tendo por base a identificação dospigmentos encontrados (azuis, vermelhos, brancos, castanhos) e composição das ligas deouro (Au) e prata (Ag).Como complemento a este estudo comparativo, procedeu-se também à análise de umterceiro túmulo, possivelmente pertencente à filha da duquesa de Coimbra - D. Isabel deUrgel, D. Catarina de Urgel (TCU), e uma peça escultórica, ambas provenientes do mesmolocal, Mosteiro de Santa Clara-a-Velha. Adicionalmente, foram também incluídoselementos existentes na atual capela mor da igreja do Mosteiro de Santa Clara-a-Nova porforma para complementar o estudo, incidindo este sobre a última camada de pintura doTNRS.Na análise de pigmentação e materiais de suporte foram utilizadas as técnicas deMicroscopia Ótica (MO), Espetroscopia de Fluorescência de Raios-X tanto portátil (p-XRF)como de bancada (b-XRF), Espetroscopia micro-Raman e Microscopia Eletrónica deVarrimento com Espetroscopia de Energia Dispersa de Raios-X (SEM-EDS), e para as ligasmetálicas apenas b-XRF e SEM-EDS.
The aim of this study was to analyze the history/material of the tombs of Rainha SantaIsabel and her granddaughter, in order to achieve it, it was considered the availablebibliographic chronology.This thesis focused, particularly, on the stratigraphy of samples collected, morespecifically in the ones from the Queen Isabel's tomb cover (TRS) and the tomb of theQueen's granddaughter (TNRS), as well as some other samples that allowed to comparewhat was found on the top with the lateral sides.The results obtained lead to a formulation of a hypothesis regarding the temporalwindows for the execution of the different decorations of the two tombs, based on theidentification of the pigments found (blue, red, white, brown), and also the gold and silvercomposition.In order to reinforce this comparative study, a third tomb was also analyzed, which itis thought to belong to the daughter of the Duchess of Coimbra - D. Isabel de Urgel, D.Catarina de Urgel (TCU), and a sculptural piece, both found in the same place, Santa Claraa-Velha Monastery. Additionally, it was further included some elements that can be foundin the current main chapel of the church of Santa Clara-a-Nova Monastery, in order tocomplement the study. In these pieces, the focus was the last coat of paint, to compare tothe one from Queen's granddaughter tomb.For the analysis of pigmentation and support materials it were used the techniques ofOptical Microscopy (MO), X-ray Fluorescence Spectroscopy, both portable (p-XRF) andbench assemble (b-XRF), Micro-Raman Spectroscopy and Scanning Electron Microscopywith Energy Dispersive Spectroscopy X-ray (SEM-EDS), and for the metal alloys it wasonly used bench-top XRF and SEM-EDS.
43
Guettler, Barbara Elisabeth. « Soy-Polypropylene Biocomposites for Automotive Applications ». Thesis, 2009. http://hdl.handle.net/10012/4427.
Texte intégralRésumé :
For the automotive sector, plastics play the most important role when designing interior and exterior parts for cars. Currently, most parts are made from petroleum-based plastics but alternatives are needed to replace environmentally harmful materials while providing the appropriate mechanical performance and preferably reduce the cost for the final product.
The objective of this work was to explore the use of soy flakes as natural filler in a composite with polypropylene and to investigate the mechanical properties, water absorption and thermal behaviour. For a better understanding of the filler, the soy flakes were characterized extensively with analytical and microscopic methods.
Two types of soy fillers were investigated, soy flakes, provided by Bunge Inc., with a 48 wt-% protein content and an industrial soy based filler with 44 wt-% protein content and provided by Ford.
The size of the soy flakes after milling was mainly between 50 and 200 µm and below 50 µm for the industrial filler. The aspect ratio for all filler was below 5. The soy flakes were used after milling and subjected to two pre-treatment methods: (1) one hour in a 50 °C pH 9 water solution in a 1 : 9 solid-liquid ratio; (2) one hour in a 50 °C pH 9 1M NaCl solution in a 1 : 9 solid-liquid ratio. A control filler, without pre-treatment was considered. The soy flakes were also compared to an industrial soy based filler provided by Ford (soy flour (Ford)). The thermogravimetric analysis showed an onset of degradation at 170 °C for the treated filler (ISH2O and ISNaCl) and 160 °C for the untreated filler.
The biocomposites formulation consisted of 30 wt-% filler, and polypropylene with/without 0.35 wt-% anti-oxidant Irganox 1010 and with/without the addition of MA-PP as coupling agent. All biocomposites were compounded in a mini-extruder, pressed into bars by injection moulding and tested subsequently.
The mechanical properties of the biocomposites are promising. An increase of the E-modulus was observed when compared to pure polypropylene. The addition of MA-PP as coupling agent increased the yield strength of the biocomposites. When pure polypropylene and the biocomposites were compared no difference could be seen for their yield strength.
The thermal behaviour deduced from differential scanning calorimetry, revealed a similar behaviour for the biocomposites and the pure polypropylene. Only the samples treated in the presence of NaCl and without a coupling agent, appear to have a slightly higher degree of crystallinity. The melt flow index was slightly increased for the biocomposites containing soy flakes pre-treated with NaCl and decreased for biocomposites containing the soy flour.
The water absorption behaviour of the biocomposites was quite similar at the beginning with a slightly lower absorption for the materials with coupling agent. After three months, all samples except the ones treated with water showed a weight loss that can be due to the leaching of the water soluble components in the untreated filler and the NaCl treated filler.
In conclusion, soy flakes represent an attractive filler when used in a polypropylene matrix if an aqueous alkaline pre-treatment is performed. The aqueous alkaline extraction also leads to the recovery of the proteins that can be used in food products while the remaining insoluble material is used for the biocomposites, avoiding the competition with the use of soy for food products...
44
Seidel, Falko. « Dünne Siliziumschichten für photovoltaische Anwendungen hergestellt durch ein Ultraschall-Sprühverfahren ». Doctoral thesis, 2013. https://monarch.qucosa.de/id/qucosa%3A20180.
Texte intégralRésumé :
Der hauptsächliche Bestandteil dieser Arbeit ist die Entwicklung einer kostengünstigen Methode zur Produktion von auf Silizium basierenden Dünnschicht-Solarzellen durch Sprühbeschichtung. Hier wird untersucht inwiefern sich diese Methode für die Herstellung großflächiger photovoltaische Anlagen eignet. Als Grundsubstanz für entsprechende Lacke werden Mischungen aus Organosilizium und nanokristallines Silizium verwendet. Eine Idee ist das Verwenden von Silizium-Kohlenstoff-Verbindungen als Si-Precursor (Cyclo-, Poly-, Oligo- und Monosilane). In jedem Fall, Organosilizium und Silizium- Nanopartikel, ist eine Umwandlung durch äußere Energiezufuhr nötig, um die Precursor-Substanz in photovoltaisch nutzbares Silizium umzuwandeln. Die Versuchsreihen werden mithilfe photothermischer Umwandlung (FLA-„flash lamp annealing“, einige 1 J/cm² bei Pulslängen von einigen 100 μs) unter N2-Atmosphäre durchgeführt. Zur Bereitstellung eines auf Laborgröße skalierten Produktionsprozesses wurden ein Spraycoater, eine Heizplatte, ein Blitzlampensystem und ein In-Line Ellipsometer in einem Aufbau innerhalb einer Glovebox unter N2-Atmosphäre kombiniert. Die Gewinnung von Proben und deren Charakterisierung fand in enger Zusammenarbeit mit den beiden Arbeitsgruppen der anorganischen Chemie und der Koordinationschemie an der TU-Chemnitz statt.
Die eingesetzten Charakterisierungsmethoden sind Raman-Spektroskopie, Infrarotspektroskopie, Rasterelektronenmikroskopie, Transmissionselektronenmikroskopie, Elektronenbeugung, Röntgenbeugung, energiedispersive Röntgenspektroskopie, Rasterkraftmikroskopie und elektrische Charakterisierung wie die Aufnahme von Strom- Spannungs-Kennlinien und Widerstandsmessung per Vierpunktkontaktierung.:I Bibliographische Beschreibung
II Abkürzungsverzeichnis
III Abbildungsverzeichnis
IV Tabellenverzeichnis
1 Einleitung 1
2 Grundlagen 3
2.1 Dioden und Photodioden 3
2.1.1 Schottky-Dioden 3
2.1.1.1 Schottky-Kontakt oder Ohmscher Kontakt 3
2.1.1.2 Schottky-Barriere 3
2.1.1.3 Arbeitsweise der Schottky-Diode 5
2.1.1.4 Ladungstransport durch eine Schottky-Diode 6
2.1.2 Schottky-Photodioden 8
2.2 Solarzellen 9
2.2.1 Aufbau einer Solarzelle 10
2.2.2 Charakterisierung einer Solarzelle 10
2.3 Moderne Photovoltaik 12
2.4 Transparente leitfähige Oxide (TCO) 13
2.5 Ultraschalldüse und Sprühnebel 14
2.6 Blitzlampenbehandlung (FLA) 17
3 Methoden zur Charakterisierung 18
3.1 Fourier-Transformations-Infrarotspektroskopie (FTIRS) 18
3.2 Lichtstreuung an Materie 20
3.2.1 Raman-Spektroskopie 20
3.2.1.1 Klassische Deutung des Raman-Effektes 21
3.2.1.2 Quantenmechanische Deutung des Raman-Effektes 22
3.2.1.3 Räumlich eingeschränkte Phononen 23
3.3 Änderung der Lichtpolarisation an Materie 26
3.3.1 Fresnel-Formeln 26
3.3.2 Jones-Formalismus 27
3.3.3 Spektroskopische Ellipsometrie (SE) 27
3.4 Röntgenbeugung (XRD) 29
3.4.1 Kalibrierung des Einfallswinkels 31
3.4.2 Kristallitgröße 31
3.5 Elektronenmikroskopie (EM) 31
3.5.1 Transmissionselektronmikroskopie (TEM) 32
3.5.2 Rasterelektronenmikroskopie (SEM und EDX) 33
3.6 Rasterkraftmikroskopie (AFM) 34
4 Experimentelles 37
4.1 Prozessaufbauten 37
4.2 Messgeräte 39
4.3 Probenherstellung 40
4.3.1 Lösungen und Dispersionen 41
4.3.2 Sprühlack 41
4.3.3 Substratreinigung 42
4.3.4 Drop- und Spraycoating 42
4.3.4.1 Dropcoating und Rohrofenprozess 43
4.3.4.2 Sprühen und Blitzlampenbehandlung 43
4.4 Infrarotspektroskopie 46
4.4.1 DRIFT-Spektroskopie an Silizium-Nanopartikeln im MIR 47
4.4.2 DRIFT-Spektroskopie an Silizium-Precursoren im MIR 48
4.4.3 Transmissions- und Reflexionsspektroskopie an Si-Schichten im FIR 49
4.5 Lichtstreuung 49
4.5.1 Mie-Streuung an Silizium-Nanopartikeln 49
4.5.2 Raman-Streuung an Silizium-Precursoren und –Schichten 50
4.6 AFM an Silizium-Schichten 51
4.7 Elektronenmikroskopie 51
4.7.1 SEM und EDX an Silizium-Schichten und –Folien 52
4.7.2 TEM an Silizium-Nanopartikeln und –Folien 53
4.8 XRD an Silizium-Folien 54
4.9 Elektrische Messungen an Silizium-Schichten und –Folien 55
5 Ergebnisse und Diskussion 56
5.1 Silizium-Nanopartikel als Pulver 56
5.1.1 Dispersionen von Silizium-Nanopartikeln 56
5.1.2 Oxidationsgrad von Silizium-Nanopartikeln 58
5.1.3 Verteilung von Silizium-Nanopartikeln in getrocknetem Ethanol 61
5.2 Gesprühte Silizium-Nanopartikel 64
5.2.1 Ellipsmetrie als In-Line Prozessmethode im Spraycoating 64
5.2.2 Oberflächenrauheit von Schichten von Silizium-Nanopartikeln 66
5.2.3 Effekt des FLA auf Schichten von Silizium-Nanopartikeln 69
5.2.4 Simulationen zum Phonon-Confinement 74
5.3 Organosilizium als Silizium-Precursoren 80
5.3.1 Vorversuche: Zersetzung von Phenylsilanen im Rohrofen 80
5.3.2 Photothermische Zersetzung von Monosilanen durch FLA 82
5.4 Monosilane als Haftmittel zwischen Silizium-Nanopartikeln 89
5.4.1 Bestandteile des verwendeten Lacks 90
5.4.2 Filme hergestellt von Si-Nanopartikeln gemischt mit Si-Precursor 92
5.4.3 Folien hergestellt von Si-Nanopartikeln gemischt mit Si-Precursor 106
5.5 Realisierung von Diodenstrukturen 120
6 Zusammenfassung 124
Literaturverzeichnis
Anhang