Thesis (doctoral)--Universität Erlangen.

As hidroxiapatitas (HA) são amplamente utilizadas como biomateriais osteocondutores, mas não possuem propriedades osteoindutoras e osteogênicas. O fluoreto, por sua vez, quando presente no meio em doses adequadas (da ordem de 10-5 M), é capaz de aumentar a proliferação de osteoblastos e a atividade da fosfatase alcalina. Assim, o objetivo do presente estudo foi modificar um biomaterial existente, constituído por HA bifásica (70% HA + 30% β-TCP) porosa, pela adsorção de fluoreto. A capacidade de liberação de fluoreto deste material para meio de cultura osteogênico foi também avaliada. Foi ainda feita caracterização físicoquímica do material com fluoreto adsorvido, em comparação ao material original (FTIR, DRX e MEV). Para os ensaios de adsorção de fluoreto, soluções com diferentes concentrações deste elemento, na forma de NaF, foram adicionadas à HÁ bifásica na proporção de 10 g de HA por 50 mL de solução contendo fluoreto. Os testes foram feitos em duas etapas. Na primeira etapa, as concentrações de fluoreto empregadas variaram entre 100 e 2000 ppm e foi feita incubação por 3, 6, 18 ou 24 h, em temperatura ambiente, sob agitação constante. Após estes intervalos de tempo, removeu-se o sobrenadante e colocou-se o restante na estufa a 40oC, até a completa secagem dos grânulos. Os mesmos foram armazenados para posterior quantificação de fluoreto adsorvido, que foi feita com o eletrodo, após difusão facilitada por exametildisiloxano. Na segunda etapa, as concentrações de fluoreto empregadas variaram entre 0,625 e 80 ppm, sendo feita incubação por 24 ou 48 h. Para a avaliação da liberação de fluoreto da HA adsorvida, as amostras de HA com fluoreto adsorvido foram incubadas à temperatura ambiente com meio de cultura α-MEM, na proporção de 10 g de HA por 50 mL de meio, sob agitação, por 3, 6, ou 24 h e o sobrenadante foi coletado para quantificação de fluoreto. Foi observada uma relação dose- resposta entre a concentração de fluoreto que se adsorveu à HA e concentração de fluoreto presente nas soluções em que a HA foi incubada. O tempo de incubação nas soluções fluoretadas não alterou a concentração de fluoreto adsorvido (exceto para uma diminuição da adsorção para o tempo de 48 h). A porcentagem de adsorção de fluoreto variou entre 15 e 35%. Houve uma redução na concentração de fluoreto liberada para o meio, em função da redução da concentração de fluoreto na solução de incubação da HA. Liberações da ordem de 10-5 M foram observadas para a HA incubada por 24 h em 80 ppm fluoreto. A avaliação físico-química da HA bifásica porosa com fluoreto adsorvido revelou características semelhantes ao material original, sem fluoreto adsorvido. Em conclusão, a incubação da HA bifásica porosa em solução contendo 80 ppm de fluoreto por 24 horas é capaz de levar a uma adsorção de fluoreto tal que permite a liberação deste elemento na ordem de 10-5 M em meio de cultura osteogênico. Esta adsorção de fluoreto não altera as propriedades físico-químicas do material. / Hydroxyapatites (HA) are broadly employed as osteoconductive biomaterials, but they do not possess osteoinductive or osteogenic properties. Fluoride, when present in the environment in appropriate doses (around 10-5 M) is able to increase the proliferation of osteoblastos and the activity of alcaline phosphatase. Thus, the aim of the present study was to modify an existing biomaterial (biphasic HA, containing 70% HA and 30% β-TCP), through the adsorption of fluoride. The ability of this material to release fluoride for osteogenic culture medium was also evaluated. The biomaterial containing adsorbed fluoride was characterized physic-chemically (FTIR, DRX and SEM), in comparison to its counterpart without adsorbed fluoride. For the fluoride adsorption experiments, solutions with different fluoride concentrations (as NaF) were added to biphasic HA (10 g HA : 50 mL fluoridecontaining solution). Tests were carried out in 2 stages. In the first stage, fluoride concentrations used ranged between 100 and 2000 ppm. Incubation was done for 3, 6, 18 or 24 h, at room temperature, under constant agitation. After incubation, supernatant was removed and the pellets were allowed to dry at 40oC. The resulting material was stored for subsequent fluoride analysis that was done with the electrode, after examethyldisiloxane-facilitated diffusion. In the second stage, the fluoride concentrations ranged between 0.625 and 80 ppm and incubation was carried out for 24 or 48 h. For the evaluation of the release of adsorbed fluoride, samples of HA containing adsorbed fluoride were incubated in α-MEM medium at room temperature (10 g HA : 50 mL medium), under agitation, for 3, 6 or 24 h. Supernatant was collected for fluoride quantification. A dose- response relationship was observed between the concentration of fluoride that adsorbed to HA and the fluoride concentration in the incubation solutions. The time of incubation did not change the concentration of adsorbed fluoride (except for a reduction in adsorption for 48 h). The percentage of fluoride adsorption ranged between 15 and 35%. It was observed a reduction in the concentration of fluoride that was released to the medium, as a function of the reduction of the fluoride concentration in the incubation solution. Fluoride releases around 10-5 M were observed for HA incubated with 80 ppm fluoride for 24 h. Physico-chemical evaluation of the porous biphasic HA containing adsorbed fluoride revealed a pattern similar to the one observed for the original material (without adsorbed fluoride). In conclusion, the incubation of porous biphasic HA in a solution containing 80 ppm fluoride for 24 h allows adsorption of F to HA to an extent that allows the release of 10-5 M fluoride concentrations to the medium. In addition, fluoride adsorption to HA does not change the physico-chemical properties of the material.

Doctor Scientiae - DSc / Semiconductor nanocrystals or quantum dots (QDs) are fluorescent nanometer-sized particles which have physical dimensions that are smaller than the excitonic Bohr radius, large surface area-to-volume ratios, broad absorption spectra and very large molar extinction coefficients. Biomedical applications of QDs are mainly based on II-VI QDs containing cadmium, such as CdSe/ZnS. These cadmium-based systems are associated with high toxicity due to cadmium. As a result, potential replacements of cadmium-based QDs in biological applications are needed. In this study, InP/ZnSe QDs were synthesized for the first time using a one-pot hot injection method. Furthermore, a growth-doping method was used for silver, cobalt and iron incorporation into the InP core. Water compatibility was achieved through ligand exchange with 3- mercaptopropionic acid. In vitro cytotoxicity and imaging/internalization of the as-prepared MP A-InP/ZnSe and MP A-capped CdTe/ZnS QDs were evaluated. InP/ZnSe QDs were successfully synthesized with ZnSe shell causing a 1.4 times reduction in trap-related emission.

The purpose of this study was to examine Mississippi?s Career and Technology School Administrators? attitudes and perceptions toward technology integration and to determine their knowledge and use of the NETS∙A. The study contributed to the literature on technology integration and the NETS∙A in the secondary classroom. The research design for this study was descriptive and correlational. A pilot study was conducted prior to the commencement of the research study in which no problems were identified. Out of a population of 144 Mississippi Career and Technology School Administrators, 102 participated in the study. A survey instrument consisting of three parts was used in this study. Part I of the instrument was designed to collect demographic data and to determine administrators? training and experience with technology. Part II was the "Survey of Administrative Attitudes and Perceptions toward Technology Integration", and Part III was the "Administrator Technology Self-Assessment Tool". The research questions posed in the study were developed to examine Mississippi Career and Technology School Administrators? attitudes and perceptions toward technology integration and to determine their knowledge and use of the NETS∙A. The study was further designed to determine whether relationships existed between the variable attitude and perceptions and the variables knowledge and use, demographic characteristics, and experience and training with technology integration. Pearson r, Spearman rs, and Point-biserial rpb were used to analyze the data of the returned surveys. After the data were collected and analyzed, the researcher determined that there was a statistically significant correlation between Mississippi Career and Technology School Administrators? attitudes and perceptions of technology integration and the variable knowledge and use of the NETS∙A and the variable experience and training with technology integration. There was no statistically significant correlation between Mississippi?s Career and Technology School Administrators? attitudes and perceptions of technology integration and the variables age, sex, and years experience as an administrator. Conclusions and recommendations based on the findings in this study indicated that Mississippi Career and Technology School Administrators should be required to increase their experience and training with technology integration. School administrators should also broaden their knowledge and increase their use of the NETS∙A.

No description available.

No description available.

Cette thèse aborde la thématique de la synthèse et de la dispersion de nanomatériaux luminescents (silice ou oxydes de terres rares) dédiés à la lutte anti-contrefaçon. La silice est synthétisée par un procédé sol-gel en microémulsion inverse. Des molécules fluorescentes organiques et organo-lanthanides sont incorporées dans les nanoparticules et il est montre que la nature du colorant influence son encapsulation. La fluorescence est obtenue sans lien covalent entre le colorant et la nanoparticule. Les nanoparticules sont ensuite fonctionnalisées dans le milieu de synthèse. Une nouvelle méthode de caractérisation de la fonctionnalisation est proposée et fait notamment apparaitre que la fonctionnalisation ainsi réalisée est homogène mais qu’a l’échelle de la nanoparticule, il y a apparition de nanodomaines. Les oxydes de terres rares sont obtenus par une collaboration. Deux traitements de surface sont particulièrement étudiés : une approche hybride consistant en l’encapsulation des nanoparticules dans une couche de polysiloxane suivie d’une fonctionnalisation adaptée ; et une approche basée sur l’adsorption d’agents tensioactifs. En particulier plusieurs agents tensioactifs représentatifs sont compares. Les nanoparticules ainsi traitées sont dispersées et stables en milieu liquide. Elles peuvent alors être incorporées dans différents polymères témoins (PMMA, PVA et PVC) et il est montre qu’une bonne dispersion en milieu liquide permet une incorporation homogène dans le polymère. Un essai industriel a été réalisé et a prouvé que certains de ces procédés développés pouvaient être transférés à l’échelle industrielle / This work deals with the synthesis and the dispersion of luminescent nanomaterials dedicated to the fight against counterfeiting. The nanomaterials (silica and rare earth oxides) own an optical code which is dispersed into the material to be tagged. The silica is synthesized by a reverse microemulsion sol-gel process. Organic fluorescent dyes and organo-lanthanides metal complexes are incorporated into the nanoparticles and it is shown that the nature of the dye influences its incorporation. The fluorescence is obtained without any covalent link between the dye and the silica matrix. After the synthesis, the nanoparticles are functionalized into the microemulsion. An original method is proposed to characterize the functionalization and it is shown that the functionalization is on the whole homogeneous but that at the nanoscale some nanodomains appear. The rare-earth oxides are obtained by collaboration. Two surface treatments are particularly studied : an hybrid approach based on the encapsulation of the nanoparticles into a polysiloxane shell followed by an adapted functionalization; and a second approach based on the use of surfactants. In particular, several well-known surfactants are compared. These modified nanoparticles are dispersed and stabilized into liquid media such as water or 2-Butanone. They are then incorporated into three polymers (PMMA, PVA and PVC) and it is shown that a good dispersion into a liquid allows obtaining an homogeneous incorporation into the polymers. An industrial test has been realized and has given the proof that some of these processes can be transferred directly at industrial scale

Malgré les efforts de la communauté scientifique, les cellules solaires multijonctions à base de matériaux amorphes, sont limitées par la dégradation sous lumière des matériaux actifs qu'elles emploient - notamment, le silicium amorphe hydrogéné (a-Si:H) ou le silicium-germanium amorphe (a-SiGe:H). Compte tenu de la facilité avec laquelle les dispositifs multijonctions peuvent être fabriqués dans cette filière couches minces, pour que cette filière reste compétitive sur le marché photovoltaïque, il est nécessaire de déposer des matériaux présentant les meilleures propriétés de transport possible, avec une énergie de gap variable comprise entre celle du silicium microcristallin hydrogéné (µc-Si:H, 1.1 eV) et celle du a-SiH (1.7 eV), et peu sensibles au vieillissement sous lumière. Le but de ces travaux de thèse était de développer une nouvelle classe de matériaux satisfaisant les critères précédemment cités, alliant carbone et silicium. En effet, les alliages silicium-carbone microcristallins hydrogénés (µc-Si1−xCx:H), sont des candidats prometteurs pour la réalisation de cellules photovoltaïques (PV): d'une part, la structure microcristalline devrait les rend moins sensible au vieillissement sous lumière, et d'autre part, il est possible de faire varier l'énergie de gap en modifiant le taux de carbone de l'alliage. Dans cette thèse, nous avons étudié les propriétés structurales et électriques de ces alliages à l'aide de nombreuses techniques de caractérisation complémentaires, et en faisant varier de nombreux paramètres de dépôt afin de déterminer celles permettant d'obtenir les meilleures propriétés possibles. Nous avons montré en particulier que ces alliages sont composés de cristallites de taille sous-micrométrique, enrobé dans une matrice de silicium-carbone amorphe (a-Si1−xCx:H). En plus, ces matériaux sont caractérisés par une croissance colonnaire, typique du µc-Si:H, avec la taille moyen des grains qui est contrôler en prévalence par la puissance RF utilisé pour le dépôt. L'incorporation de carbone, qui ne peut pas se passer dans la phase cristalline, cause la formation d'un tissue amorphe interstitielle qui enrobe les grain et en empêche la croissance. Ainsi, l'analyse de l'ensemble de nos résultats nous a permis de proposer un modèle cohérent de la croissance de ces alliages. Les propriétés électriques de nos matériaux ont été étudiées à l'aide des mesures de courant d'obscurité et de photocourant en régime stationnaire, de spectroscopie par interférométrie laser et de photocourant modulé. Nous avons pu établir une corrélation directe entre les propriétés électriques et les conditions de dépôt, mettant notamment en évidence que la présence des cristallites assure une conductivité plus élevée par rapport à du a-Si1−xCx:H, et que l'incorporation de carbone amène à des énergies de gap plus grandes que celle du µc-Si:H. Nous avons également montré que les meilleurs matériaux étaient obtenus pour des puissances RF faibles, de l'ordre de 113 mW/cm2. Des résultats de caractérisation de cellules photovoltaïques de type p-i-n ou n-i-p réalisées à partir de nos alliages, ont été aussi présentés. Les rendements obtenus restent encore modestes (de l'ordre de 3,5%) mais nous avons mis en évidence qu'il est possible de faire varier la tension de circuit ouvert (Voc) des cellules en changeant le taux de carbone incorporé dans les alliages. Ainsi, un paramètre autre que la dilution de silane lors du dépôt peut être utilisé pour contrôler Voc. Ces dispositifs sont les tout premiers déposés et nécessitent encore des étapes d'optimisation. Néanmoins, l'étude approfondie que nous avons réalisée sur ces alliages nous laisse penser qu'ils ont un potentiel intéressant pour les applications PV. / Despite continuous effort, thin-film silicon multi-junction solar cells are still limited by the light-induced degradation of amorphous materials that they employ − hydrogenated amorphous silicon layers (a-Si:H) or amorphous silicon-germanium (a-SiGe:H) layers. To survive, this technology must fully benefit from the ease with which it allows multi-band gap photovoltaic (PV) devices to be assembled. To this end, materials that are stable under light soaking and have an electronic band gap between that of hydrogenated microcrystalline silicon (µc-Si:H, 1.1 eV) and that of a-Si:H (1.7 eV) are needed. The goal of this PhD thesis was to develop a new class of materials satisfying all these requirements by alloying carbon and silicon. Indeed, hydrogenated microcrystalline silicon-carbon alloys (µc-Si1−xCx:H) are a promising candidate for expanding the toolbox of useful materials for thin-film photovoltaics. The interest in these alloys lies in the possibility of easily varying their effective band gap by changing the amount of carbon in their composition. In this thesis, the usefulness of such materials in thin-film PV devices was probed using a broad range of deposition and characterization techniques. Using thin-film growth techniques at low temperatures (175−300° C), the range in which such electronically useful materials can be grown has been explored. It was confirmed that even in the condition of small crystallites, no stable sub-stoichiometric Si-C crystalline phase exists (i.e. no parallel for silicon-rich c-SiGe has been observed). Under all deposition techniques utilized, these materials were composed of submicron-size silicon crystallites embedded in an amorphous silicon-carbon (a-Si1−xCx:H) matrix. However, while the presence of the crystallites assures a higher conductivity compared to a-Si1−xCx:H, the carbon incorporation leads to an effective energy gap larger than that of microcrystalline silicon, supporting our investigation of these materials as promising optoelectronic layers. In the first part of this work, different Plasma Enhanced Chemical Vapor Deposition strategies have been investigated to achieve the widest range of processing conditions and to learn the most about the growth conditions required to produce a high quality µc-Si1−xCx:H material. Material properties were extensively characterized both on the structural side and also from an electrical point of view, in order to establish a correlation between the deposition parameters and the microstructural, transport and defect-related properties. The extensive set of results has allowed the proposal of a coherent growth model for such µc-Si1−xCx:H thin films. Exploiting these results, PV devices using these alloys as active layers were made. Although the absolute levels of efficiency (around 3.5 %) are not as high as state-of-the-art microcrystalline silicon, this work showed that it is possible to obtain variations in the open circuit voltage by varying the amount of carbon incorporated in such µc-Si1−xCx:H alloys. This important result shows that a process parameter other than silane dilution can be used to control this aspect of device performance. PV performances are modest so far, which is expected as these are the first ever results concerning the application of such a new class of materials as the active layer in thin-film solar cells. However, with further advancements in such materials, their replacement of the less stable a-SiGe:H is not unforeseeable.

Thesis (Ph.D.)--Murdoch University, 2005. / Thesis submitted to the Division of Arts. Bibliography: leaves 387-428.

Si les liens entre l’alimentation et la religion se sont distendus dans un monde sécularisé, les pratiques alimentaires constituent encore aujourd’hui un marqueur d’identité et d’attachement à « Dieu ». C’est dans cette perspective que nous nous sommes intéressés à l’émergence d’une consommation de produits halal au sein de migrants Berbères Marocains et de leurs descendants vivant en Moselle. Notre projet s’inscrit dans une volonté de saisir cette consommation à travers un héritage à la fois familial, culturel et politique et une trajectoire propre à chaque acteur. Manger halal sera abordé ici sous l’angle d’un fait religieux comportant de multiples dimensions, à la fois collective, matérielle, symbolique et sensible. Si manger halal renvoie aux interdits alimentaires propres au système religieux de l’islam, cette pratique n’explique pas pour autant les raisons pour lesquelles un individu respecte une prescription, un interdit. En nous inspirant des approches de Michel de Certeau, de Jean-Noël Ferrié ou encore de Saba Mahmood, nous montrerons comment un individu, par le biais de l’incorporation, matérialise sa foi et construit ses appartenances. Loin d’apparaître comme une essentialisation des pratiques alimentaires, manger halal produit de nouveaux types de mangeur où le croire constitue une technique de soi destinée à créer chez l’acteur des capacités de réflexivité et d’agentivité. / If the links between food and religion have weakened in a secularized world, feeding practices are still a marker of identity and attachment to "God". With this in mind, we are interested in the emergence of a consumption of halal products by Berber Moroccan migrants and their descendants living in Moselle.Our project is a desire to use this consumption through a legacy of both family, cultural and political trajectory that is specific for each actor. Eating Halal is discussed here in terms of a religious fact with multiple dimensions, both collective, material, symbolic and significant. If eating halal refers to dietary laws specific to Islam religious system, this practice does not explain why an individual meets a requirement, a prohibition. Drawing on the approaches of Michel de Certeau, Jean-Noël Ferrié and Saba Mahmood, we show how an individual, through the incorporation, embodies faith and built its membership. Far from appearing as an essentialization of feeding practices, eating halal produces new types of eaters for whom the believe is a technique designed to create for the actor a capability of agency and reflexivity.