The purpose of this study was to evaluate the effects of sodium hypochlorite on the organic and inorganic composition of enamel. Background: With the advent of enamel bonding for orthodontic appliances in the late 1970s, it has been shown that traditional phosphoric acid etching affects the inorganic portion of the enamel.1, 2 In an attempt to enhance the acid etching pattern and, furthermore, the bond strength, additional pretreatment techniques that target the organic components of the enamel biofilm have been proposed. One such method is the non-invasive enamel pretreatment with 5.25% sodium hypochlorite (NaOCl) prior to phosphoric acid etching.3, 4 It has been suggested that the mechanism by which sodium hypochlorite enhances the etching pattern is enamel deproteinization, in which organic elements, including the acquired film, are removed from the enamel surface.3, 5 This presumption is based on the multitude of endodontic literature supporting the use of NaOCl as an effective irrigant in root canal therapy6-13. In contrast to dentin and pulpal tissue, enamel is comprised of minimal organic matter.14, 15 As a result of this fact and the limited amount of experimentation of the effect of NaOCl on the enamel surface, the true mechanism by which sodium hypochlorite enhances the etching pattern of enamel is questionable.5, 16 The objective of this study was to determine the compositional effects of sodium hypochlorite on human enamel. Methods: Following IRB approval, 120 enamel sections from 22 extracted human premolar teeth were randomly divided into three experimental groups and one control group.17 The control group (E = enamel) received no treatment. The first experimental group (A = phosphoric acid) received a 15-second treatment with 37% phosphoric acid, rinsed with distilled water and air sprayed for 20 seconds, then dried with oil free compressed air. The second experimental group (H = sodium hypochlorite) received a treatment of 5.25% sodium hypochlorite for 60 seconds, washed with distilled water for 10 seconds, and dried. The third experimental group (HA = sodium hypochlorite + phosphoric acid) received a treatment of 5.25% sodium hypochlorite for 60 seconds, washed with distilled water for 10 seconds, dried, then receive the 15-second treatment with 37% phosphoric acid as in Group A.3 Following treatment preparations of the four groups, scanning electron microscopy (SEM)/energy-dispersive X-ray spectrometer (EDX) analysis was performed for all groups.18 For elemental concentration, a one-way ANOVA and Tukey’s post hoc statistical tests were applied.17, 19, 20 ANOVA and Tukey tests were performed at a significance level of p ≤ 0.05. Results: There were no significant effects of treatment on the enamel elements carbon (C), calcium (Ca) sodium (Na), oxygen (O), and phosphorous (P). There was a significant effect of treatment on the amount of chlorine (Cl) in enamel between groups acid (A) and hypochlorite + acid (HA) as well as between groups hypochlorite (H) and hypochlorite + acid (HA) (p = 0.004). The amount of variation of iodine (I) in the enamel composition between untreated enamel (E) and enamel treated with sodium hypochlorite + phosphoric acid (HA) was significant (p = 0.004). Additionally, there was a significant decrease in the quantity of antimony (Sb) found in the control group (E) versus the hypochlorite + acid (HA) experimental group (p = 0.002). Lastly, tin (Sn) was significantly reduced from the enamel surface (E) when treated with hypochlorite + acid (HA) (p = 0.008). Conclusions: The various treatments minimally affected the elemental concentrations of C, Ca, Na, O, and P. The amount of chlorine present in enamel significantly increased following treatment with sodium hypochlorite (H) alone and even more so following treatment with phosphoric acid and sodium hypochlorite (AH). In contrast, elements I, Sb, and Sn demonstrated a congruent reduction in concentration after treatment with hypochlorite and acid (HA). Although it has been hypothesized that sodium hypochlorite targets the organic pellicle present on the surface of enamel via a process known as deproteinization, the findings presented here suggest that pre-treatment with NaOCl impacts the inorganic components of enamel more so than the organic constituents. These quantitative findings corroborate the enhanced etching pattern that can be visualized under scanning electron microscopy in this as well as previous studies.

Identification of osseous materials is generally established on gross anatomical factors; however, highly fragmented or taphonomically altered materials are often problematic and alternative methods, such as biological, histological, or chemical analysis, must be utilized. Recently, chemical methods have been proposed to sort unknown materials according to their Ca/P ratios. Ubelaker and colleagues (2002) proposed using SEM/EDX to achieve this distinction and Christensen and colleagues (2012) have validated X-ray Fluorescence Spectrometry (XRF) for this application. An alternative method of analysis involves performing principal component analysis (PCA) on element spectra to classify unknown materials based on their trace element composition. Zimmerman (2013) proposed the validity of this method with data obtained using hand held XRF. Subsequently, performing PCA on elemental data obtained using SEM/EDX demonstrates potential for material differentiation. Elemental weight percent data were collected using SEM/EDX then processed in R, version 3.0.1, by the R Foundation for Statistical Computing using PCA and Fisher Linear Discriminant Analysis. A two-tiered analysis was undertaken to improve discrimination between sample groups. The first tier involved distinguishing between osseous and non-osseous materials. After outliers were removed overall correct classification was 98.02% with one of 1504 osseous and 39 of 520 non-osseous spectra misclassifying. Since forty spectra were collected for each sample, the single misclassifying spectra would not affect the overall classification of the sample, resulting in 100% correct classification with a 0% error rate for the osseous samples. The second tier assessed differentiation of human and non-human osseous materials but demonstrated a poor correct classification rate of 72.41%. Finally, a blind study was conducted using 20 samples to assess the applicability for using this method to classify unknown materials as osseous or non-osseous. All of the samples were correctly classified resulting in 100% correct classification, further demonstrating the efficiency of SEM/EDX and statistical analysis for differentiation of osseous and non-osseous materials. Due to its high specificity, small sample requirements, and relative non-destructive testing protocol, as well as its presence in most modern crime laboratories, SEM/EDX has been proposed as a laboratory method for chemical differentiation of osseous and non-osseous materials. Additionally, the proposed method does not require advanced training or knowledge of analytical chemistry as the SEM/EDX provides clear results that can be processed using publically available statistical analysis software. By assessing and improving chemical analysis methodologies used for material differentiation, forensic anthropologists might be able to identify osseous and non-osseous samples as a preemptive step in forensic investigations involving fragmentary and taphonomically modified materials, reducing time and cost investments spent on forensically insignificant samples.

The purpose of this thesis is to examine the potential for a more comprehensive method of analysis of coal mine dust. Respirable dust is specifically of interest due to its ability to cause occupational lung disease when miners are overexposed to airborne concentrations. A detailed standard methodology to characterize respirable mine dust is carefully investigated with the use of scanning electron microscopy with energy dispersive x-ray (SEM-EDX). In addition to a thorough description of the developed particle level characterization approach, the method is demonstrated with underground respirable dust samples collected from an underground coal mine in Central Appalachia. Results of this thesis indicate that a comprehensive dust characterization method is possible and can be efficient and effective, when standardized. This analytical approach uses measured compositions, dimensions, and shapes to produce an abundance of data in even a single sample of dust. Verification results show the method is suitable for analysis of respirable particles of common coal mine mineralogy and analysis of many samples in a timely manner. The results obtained from the underground samples in Central Appalachia reveal the quantity of information which can be generated using the developed method. The amount of data which is acquired using the more comprehensive dust characterization method may aid in understanding the health effects of various dust characteristics. / Master of Science

Grâce à ses propriétés d’antioxydant, d’anti-usure et éventuellement d’extrême pression le dithiophosphate de zinc (ZDDP) fait partie des additifs les plus utilisés dans les lubrifiants pour moteurs thermiques. De nos jours, dans un souci de respect de l’environnement, de nouveaux lubrifiants possédant de bonnes performances en lubrification (frottement faible et usure limitée) sont développés en prenant compte des limitations d’utilisations actuelles du ZDDP. L’idée étant de réduire dans ceux-ci les teneurs en phosphore et soufre (Normes euros VI), éléments essentiels du ZDDP qui endommagent les pots catalytiques. L’objectif de cette thèse est l’étude du comportement tribologique du phosphate de zinc di alkyl (ZP) en comparaison avec le ZDDP. La méthodologie expérimentale étudiée pour comprendre le mécanisme d’action de ces additifs, associe des essais de frottement à descaractérisations physico-chimiques des surfaces frottantes après essais.Cette comparaison a été effectuée en fonction de la température (25°C et 100°C), la vitesse de glissement (25, 50 et 100 mm/s) et la concentration en additif (200 et 600 ppm dephosphore). Les meilleures actions anti-usure sont obtenues avec le ZDDP pour une température de 100°C et une vitesse de glissement de 100 mm/s et le ZP pour une température de 25°C et une vitesse de glissement de 25 mm/s. Les analyses de surface XPS, AES, XANES et MET-EDX ont permis de mettre en évidence la présence d’un film protecteur constitué principalement de phosphate de zinc, ceci pour les deux additifs.Une synergie de comportement tribologique a été mise en évidence avec un lubrifiantconstitué de ZP (usure faible) et d’oléate d’urée (frottement faible). Des essais complémentaires sur un tribomètre dynamique ont permis d’étudier le niveau de frottement du tribofilm formé à partir du ZDDP. Le caractère visqueux du tribofilm de ZDDP a été mis en évidence. / Thanks to its antioxidant, anti-wear and extreme pressure properties, zinc dialkyldithiophosphate (ZDDP) is nowadays the most used anti-wear additives in engine oil. Due to environmental protection concerns, new lubricants with good tribological performances (low friction and low wear) are developed. This research aims to evaluate the current limitations of ZDDP and to find alternative environmentally friendly solutions. Thus, the target is to reduce the quantity of phosphorus and sulphur in lubricants, two essential elements of ZDDP molecule that damage catalytic. The objective of this thesis is to study tribological behavior of zinc phosphate di alkyl (ZP) in comparison to ZDDP. The experimental method performed is the coupling of friction test with surface physico-chemical characterisation of rubbing surface after tests.This comparison carried out according to the temperature (25°C and 100°C), the sliding speed (25, 50, 100 mm/s) and additives concentrations (200 and 600 ppm). The best anti-wear efficiency is obtained with the ZDDP additive at 100°C - 100 mm/s and with the ZP at 25°C - 25 mm/s. For both additives and under these conditions, tribofilms are mainly made of zinc phosphate.A tribological synergy are obtained with a lubricant contained ZP (low wear) and oleyl urea (low friction). Complementary tests were made on a original dynamic tribometer for a better understanding of ZDDP tribofilm friction behavior. The viscous character of ZDDP tribofilm was obtained.

As metaloproteinases da matriz (MMPs) foram identificadas na saliva, na placa dental, na dentina e no cemento. Este trabalho teve como objetivos: Estudo I (I) - avaliar a expressão de MMP-2 e MMP-9 presentes na saliva total e parotidiana e no fluido gengival crevicular (FGC) de pacientes portadores e não portadores de lesões cervicais não cariosas (LCNC); Estudo II (II) - investigar se a presença de MMP-8 e -9/TIMPs poderia influenciar a remineralização de lesões artificialmente criadas na superfície radicular, com ou sem desgaste por abrasão. Os métodos utilizados foram: (I) Coleta de amostras de saliva e do FGC de 32 pacientes, com (n=16) e sem LCNC (n=16). A atividade gelatinolítica das MMPs foi avaliada através de análise zimográfica e Western Blot. (II): Espécimes de dentina humana radicular foram obtidos. O grupo controle G1(10) não sofreu nenhum tratamento. Os demais segmentos radiculares foram desmineralizados G2(60). O Grupo A não foi submetido à escovação e o Grupo B foi submetido à abrasão por escovação em uma máquina de escovação simulada. G2(10) foi apenas desmineralizado, G3(10) desmineralizado e remineralizado, e os Grupos G4(10), G5(10), G6(10), G7(10) foram desmineralizados e remineralizados em presença de tampão neutro, TIMP, MMP-8 e -9, MMP-8,-9 e TIMP, respectivamente. Para a análise elemental, as concentrações de Ca+2, P, Mg+2 assim como a relação molar Ca/P e Mg/Ca foram determinadas através de uma sonda eletrônica para microanálise (EPMA). A análise qualitativa por retrodispersão (BSE) foi realizada para demonstrar a distribuição global da densidade mineral. Os resultados (I) mostraram que a principal gelatinase presente, tanto na saliva total quanto no FGC, é a proMMP-9. Na saliva secretada pela glândula parótida, não foram detectadas bandas indicando a presença de gelatinases. Os resultados do estudo (II) indicaram que os espécimes escovados apresentaram maior conteúdo de Ca+2 a 20µm e maior conteúdo de Mg+2 a 30 e 50µm. Em presença de TIMPs, ocorreu uma redução do conteúdo de Ca+2 a 20µm. Para os espécimes não escovados, em todas as profundidades, as amostras incubadas com MMPs apresentaram maiores valores de Ca+2. Portanto, pode-se concluir que (I) a comparação entre pacientes com e sem LCNC mostrou não haver diferença estatisticamente significante quanto à atividade gelatinolítica; (II) quando não inibidas pelos TIMPs, as MMPs degradaram o colágeno completamente desmineralizado na superfície radicular, permitindo melhor recalcificação na superfície subjacente. Esse fenômeno foi também facilitado pela abrasão por escovação. / Matrix metalloproteinases (MMPs) have been identified in saliva, plaque, gingival crevicular fluid (GCF), dentin and cementum. Study (I) aimed at evaluating the presence and quantity of gelatinases MMP-2 and MMP-9 in total and parotid saliva and in GCF (GCF) of subjects with and without NCCL. Study (II) aimed at investigating whether the presence of matrix metalloproteinase (MMP)-8 and - 9/TIMPs would influence the remineralization of artificial root lesions with and without mechanical wear. (I) Total stimulated saliva, parotid saliva, and GCF from patients with (n=16) and without NCCL (n=16) were collected and assessed for gelatin zymography and for western immunoblot analysis. (II) Human root segments from Group A (n=35) were not brushed and from Group B (n=35) were subjected to machine-controlled brushing, simulating mechanical wear. Specimens from Group 1 (control, n=10) were left untreated. Group 2 (n=10), was just demineralized; Group 3 (n=10) was demineralized and remineralized. The other samples G4 (n=10), G5 (n=10), G6 (n=10), G7 (n=10) were subjected to remineralization with HEPES buffer, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2), activated MMP-8 and MMP-9 and activated MMP-8, MMP-9 and TIMP-2, respectively. Ca+2, P, Mg+2 concentrations as well as Ca/P and Mg/Ca molar ratios were determined through an Electron Probe Microanalyser (EPMA). (I) Densitometric analysis revealed that the main gelatinase was proMMP-9. No statistically significant difference was observed for MMP-2 and MMP-9 levels, separately. In parotid saliva, gelatinolytic activity was very low or absent. Western immunoblots revealed that, while little immunoreactivity was detected for MMP-2, there was positive immunoreaction for MMP-9, both in total saliva and in GCF. Gelatinases do not seem to originate from parotid gland. (II) The results indicated that the brushed specimens presented higher Ca+2 levels at 20 µm and higher Mg+2 content at 30 and 50 µm. Ca+2 content at 20 µm decreased in the presence of TIMPs. For the non-brushed specimens, in all depths, samples incubated with MMPs showed highest Ca+2 values. It can be concluded that (I) the main gelatinase present in the oral cavity is MMP-9. No significant differences were found in total gelatinolytic activity among NCCL+ and NCCL- patients. (II) When not inhibited by TIMPs, MMPs degraded the completely demineralized collagen in the root surface, allowing for better recalcification in the deeper areas. This phenomenon was also facilitated by the brushing procedure.

Ein Spezialgebiet der modernen Mikroelektronik ist die Miniaturisierung und Entwicklung von neuen nanostrukturierten und Komposit-Materialen aus 3d-Metallen. Durch geeignete Zusammensetzungen können diese sowohl mit einer hohen Sättigungsmagnetisierung und Koerzitivfeldstärke als mit besserer Oxidationsbeständigkeit im Vergleich zu den reinen Elementen erzielt werden.<br /> <br /> In der vorliegenden Arbeit werden neue Methoden für die Herstellung von bimetallischen kolloidalen Nanopartikeln vor allem mit einer Kern-Hülle-Struktur (Kern@Hülle) präsentiert. Bei der überwiegenden Zahl der vorgestellten Reaktionen handelt es sich um die thermische Zersetzung von metallorganischen Verbindungen wie Kobaltcarbonyl, Palladium- und Platinacetylacetonate oder die chemische Reduktion von Metallsalze mit langkettigem Alkohol in organischem Lösungsmittel. Daneben sind auch Kombinationen aus diesen beiden Verfahren beschrieben. Es wurden Kolloide aus einem reinen Edelmetall (Pt, Pd, Ag) in einem organischen Lösungsmittel synthetisiert und daraus neue, bisher in dieser Form nicht bekannte Ag@Co-, Pt@Co-, Pd@Co- und Pt@Pd@Co-Nanopartikel gewonnen.<br /> <br /> Der Kobaltgehalt der Ag@Co-, Teilchen konnte im Bereich von 5 bis 73 At. % beliebig eingestellt werden. Der mittlere Durchmesser der Ag@Co-Partikel wurde von 5 nm bis 15 nm variiert. Bei der Herstellung von Pt@Co-Teilchen wurde eine unterschiedlich dicke Kobalt-Hülle von ca. 1,0 bis 2,5 nm erzielt. Im Fall des Palladiums wurden sowohl monodispere als auch polydisperse Pd-Nanopartikel mit einer maximal 1,7-2,0nm dicken Kobalthülle synthetisiert.<br /> <br /> Ein großer Teil dieser Arbeit befasst sich mit den magnetischen Eigenschaften der kolloidalen Teilchen, wobei die SQUID-Magnetometrie und Röntgenzirkulardichroismus (XMCD) dafür eingesetzt wurden. Weil magnetische Messungen alleine nur indirekte Schlüsse über die untersuchten Systeme erlauben, wurde dabei besonderer Wert auf die möglichst genaue strukturelle Charakterisierung der Proben mittels moderner Untersuchungsmethoden gelegt. Röntgendiffraktometrie (XRD), Röntgenabsorptionsfeinstruktur- (EXAFS) und UV-Vis-Spektroskopie sowie Transmissionselektronenmikroskopie (TEM) in Kombination mit Elektronen Energieverlustspektroskopie (EELS) und energiedispersive Röntgenfluoreszensanalyse (EDX) wurden verwendet. / Magnetic colloidal particles are attractive because of their possible application to ultra-high-density magnetic data storage media, sensors, electronic devices and medical diagnostics. The properties of small particles depend on their composition, shape, and method of preparation. The combination of 3d-metals (Fe, Co, Ni) with noble metals improves the stability of the colloids and leads to new properties of the magnetic systems, often distinct from those of the corresponding monometallic particles. Core-shell particles, where dia- or paramagnetic noble metal-cores are surrounded by a ferromagnetic Co-shell, are an interesting system to study surface and interfacial magnetism such as an induced polarization or a giant magnetoresistance effect. <br /> <br /> In this work, new synthetic routes for the preparation of monometallic (Pt, Pd, Ag) and bimetallic magnetic nanocrystals (Ag@Co, Pt@Co, Pd@Co) with core-shell structure are presented. Stable colloids with a narrow particle size distribution were obtained in organic solvents using methods of wet chemistry. The method of preparation of Ag@Co is based on the thermal decomposition of dicobalt octycarbonyl in combination with a transmetalation reaction with water free AgClO4. The cobalt amount in the Ag@Co system could be tuned from 5 to 73 at. %. The average diameter of the particles was varied from 5 to 15 nm. <br /> <br /> The reduction of platinum and palladium salts in organic solution using long chained alcohol as the reductant leads to stable metal nanostructures. Monodisperse Pd and Pt particles with average sizes of 1.7 to 7.0 nm were synthesized via thermal decomposition of metal-surfactant complexes too. Alkylamines and alkylphosphines were used in this procedure. The thickness of the Co-shell was controlled by a simple high-temperature thermolysis of dicobalt octacarbonyl at the presence of Pd and Pt seeds and was tunable from 0.5 to 2.5 nm. <br /> <br /> The crystalline structure of the samples was characterized by transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), UV-VIS and electron-energy loss spectroscopy (EELS). SQUID magnetometry, x-ray magnetic circular dichroism (XMCD) and extended x-ray absorption fine structure (EXAFS) measurements gave information about the magnetic properties of the bimetallic systems and revealed their dependency on the particle size and the chemical composition. A high spin to orbital moments ratio µL/µS of 0.26±0.06 for Ag@Co and 0.22±0.05 for Pt@Co nanocrystals was observed at XMCD measurements due to the lowered dimensionality the investigated systems.

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 nanofil. / In 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.

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 nanofil. / In 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.

As metaloproteinases da matriz (MMPs) foram identificadas na saliva, na placa dental, na dentina e no cemento. Este trabalho teve como objetivos: Estudo I (I) - avaliar a expressão de MMP-2 e MMP-9 presentes na saliva total e parotidiana e no fluido gengival crevicular (FGC) de pacientes portadores e não portadores de lesões cervicais não cariosas (LCNC); Estudo II (II) - investigar se a presença de MMP-8 e -9/TIMPs poderia influenciar a remineralização de lesões artificialmente criadas na superfície radicular, com ou sem desgaste por abrasão. Os métodos utilizados foram: (I) Coleta de amostras de saliva e do FGC de 32 pacientes, com (n=16) e sem LCNC (n=16). A atividade gelatinolítica das MMPs foi avaliada através de análise zimográfica e Western Blot. (II): Espécimes de dentina humana radicular foram obtidos. O grupo controle G1(10) não sofreu nenhum tratamento. Os demais segmentos radiculares foram desmineralizados G2(60). O Grupo A não foi submetido à escovação e o Grupo B foi submetido à abrasão por escovação em uma máquina de escovação simulada. G2(10) foi apenas desmineralizado, G3(10) desmineralizado e remineralizado, e os Grupos G4(10), G5(10), G6(10), G7(10) foram desmineralizados e remineralizados em presença de tampão neutro, TIMP, MMP-8 e -9, MMP-8,-9 e TIMP, respectivamente. Para a análise elemental, as concentrações de Ca+2, P, Mg+2 assim como a relação molar Ca/P e Mg/Ca foram determinadas através de uma sonda eletrônica para microanálise (EPMA). A análise qualitativa por retrodispersão (BSE) foi realizada para demonstrar a distribuição global da densidade mineral. Os resultados (I) mostraram que a principal gelatinase presente, tanto na saliva total quanto no FGC, é a proMMP-9. Na saliva secretada pela glândula parótida, não foram detectadas bandas indicando a presença de gelatinases. Os resultados do estudo (II) indicaram que os espécimes escovados apresentaram maior conteúdo de Ca+2 a 20µm e maior conteúdo de Mg+2 a 30 e 50µm. Em presença de TIMPs, ocorreu uma redução do conteúdo de Ca+2 a 20µm. Para os espécimes não escovados, em todas as profundidades, as amostras incubadas com MMPs apresentaram maiores valores de Ca+2. Portanto, pode-se concluir que (I) a comparação entre pacientes com e sem LCNC mostrou não haver diferença estatisticamente significante quanto à atividade gelatinolítica; (II) quando não inibidas pelos TIMPs, as MMPs degradaram o colágeno completamente desmineralizado na superfície radicular, permitindo melhor recalcificação na superfície subjacente. Esse fenômeno foi também facilitado pela abrasão por escovação. / Matrix metalloproteinases (MMPs) have been identified in saliva, plaque, gingival crevicular fluid (GCF), dentin and cementum. Study (I) aimed at evaluating the presence and quantity of gelatinases MMP-2 and MMP-9 in total and parotid saliva and in GCF (GCF) of subjects with and without NCCL. Study (II) aimed at investigating whether the presence of matrix metalloproteinase (MMP)-8 and - 9/TIMPs would influence the remineralization of artificial root lesions with and without mechanical wear. (I) Total stimulated saliva, parotid saliva, and GCF from patients with (n=16) and without NCCL (n=16) were collected and assessed for gelatin zymography and for western immunoblot analysis. (II) Human root segments from Group A (n=35) were not brushed and from Group B (n=35) were subjected to machine-controlled brushing, simulating mechanical wear. Specimens from Group 1 (control, n=10) were left untreated. Group 2 (n=10), was just demineralized; Group 3 (n=10) was demineralized and remineralized. The other samples G4 (n=10), G5 (n=10), G6 (n=10), G7 (n=10) were subjected to remineralization with HEPES buffer, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2), activated MMP-8 and MMP-9 and activated MMP-8, MMP-9 and TIMP-2, respectively. Ca+2, P, Mg+2 concentrations as well as Ca/P and Mg/Ca molar ratios were determined through an Electron Probe Microanalyser (EPMA). (I) Densitometric analysis revealed that the main gelatinase was proMMP-9. No statistically significant difference was observed for MMP-2 and MMP-9 levels, separately. In parotid saliva, gelatinolytic activity was very low or absent. Western immunoblots revealed that, while little immunoreactivity was detected for MMP-2, there was positive immunoreaction for MMP-9, both in total saliva and in GCF. Gelatinases do not seem to originate from parotid gland. (II) The results indicated that the brushed specimens presented higher Ca+2 levels at 20 µm and higher Mg+2 content at 30 and 50 µm. Ca+2 content at 20 µm decreased in the presence of TIMPs. For the non-brushed specimens, in all depths, samples incubated with MMPs showed highest Ca+2 values. It can be concluded that (I) the main gelatinase present in the oral cavity is MMP-9. No significant differences were found in total gelatinolytic activity among NCCL+ and NCCL- patients. (II) When not inhibited by TIMPs, MMPs degraded the completely demineralized collagen in the root surface, allowing for better recalcification in the deeper areas. This phenomenon was also facilitated by the brushing procedure.

La pollution atmosphérique urbaine pose des problèmes au niveau de l'environnement et de la santé publique pour plus de la moitié de la population mondiale. Afin de réduire la pollution de fond dans les villes, un matériau cimentaire innovant a été développé et permet de dégrader les polluants atmosphériques grâce à ses propriétés photocatalytiques induites par l'ajout de TiO2. Ce travail a porté sur la corrélation entre les propriétés physico-chimiques et l'efficacité photocatalytique d'un mortier enrichi en TiO2 lors de la dégradation de 2 composés organiques volatils (COV), le formaldéhyde et le toluène ainsi que sur un mélange d'oxydes d'azote (NOx). Le taux de présence de la surface en dioxyde de titane, le pourcentage relatif de titane et l'absorbance des photons UV par TiO2 ont été respectivement déterminés par spectroscopie Raman, microscopie électronique à balayage couplé à une analyse X et spectroscopie UV-visible par réflexion diffuse. La proportionnalité entre ces 3 grandeurs a été démontrée. L'efficacité photocatalytique des matériaux cimentaires enrichis en TiO2 a été mise en évidence pour la dégradation des 2 COV et des NOx. L'efficacité photocatalytique est reliée à la présence de TiO2 en surface ainsi qu'à la capacité de TiO2 à absorber des photons UV. La matrice cimentaire permet également, à l'obscurité, de réduire significativement la concentration en formaldéhyde. L'étude de l'influence des paramètres matériaux et environnementaux a montré l'importance de la teneur en TiO2, du flux lumineux et de l'humidité relative sur les propriétés photocatalytiques du mortier et permis de contribuer à une meilleure compréhension des réactions intervenant lors de la dégradation des polluants par un matériau cimentaire photocatalytique / More than half of the world population is exposed to urban air pollution which poses problems for the environment and human health. To reduce the background of the pollution in cities, an innovative cementitious material has been developed and used to degrade pollutants thanks to its photocatalytic properties induced by the addition of TiO2. This work was focused on the correlation between physicochemical properties and the photocatalytic efficiency of a mortar enriched with TiO2 during the degradation of two volatile organic compounds (VOCs), formaldehyde and toluene as well as a mixture of nitrogen oxides (NOx). The occurence rate of of titanium dioxide on the surface, the relative percentage of titanium and the absorptance of UV photons by TiO2, respectively, were determined by Raman spectroscopy, scanning electron microscopy coupled with X-ray analysis and UV-visible diffuse refectance spectroscopy. Proportionality between these three variables has been demonstrated. The photocatalytic efficiency of TiO2-rich cementitious materials has been demonstrated for the degradation of the 2 VOCs and also for NOx. The photocatalytic efficiency is related to the presence of TiO2 on the surface and the ability of TiO2 to absorb UV photons. The cement matrix can also, in the dark, reduced significantly the concentration of formaldehyde. The study of the influence of materials and environmental parameters showed the importance of the TiO2 content, the luminous flux and relative humidity on the photocatalytic properties of the mortar and allowed to contribute to a better understanding of the reactions occurring during the degradation of pollutants by a photocatalytic cementitious material