Avec de nombreuses qualités exceptionnelles (biocompatible et ostéogénique), la nacre représente un biomatériau naturel comme substitut osseux. Mais les composés ostéogéniques dans la nacre ne sont pas encore connus. Nos travaux visent à l’identification des composés ostéogéniques de la nacre. L’ESM (éthanol soluble matrix) est un extrait de la nacre qui est démontré ostéogénique. A partir d’ESM, nous avons essayé plusieurs approches pour cibler et identifier ces composés. Grâce au couplage des cellules MC3T3-E1 et d’ostéoblastes humains arthrosiques, nous avons démontré que la partie cationique d’ESM est ostéogénique, sans interaction avec la partie anionique. Le calcium joue un rôle dans l’activité ostéogénique d’ESM. Ensuite, nous avons créé une lignée cellulaire exprimant de manière stable un plasmide contenant un gène rapporteur ostéogénique (ATDC5 pMetLuc2 ColX promoteur). Grâce à cette lignée, nous avons découvert que les lipides et les sucres présents dans l’ESM ont un effet ostéogénique. Les peptides précipités par TCA sont aussi démontrés ostéogéniques, et ont conduit à leur identification partielle par LC-MS. Ces résultats nous permettent d’avancer plus loin et plus rapidement vers l’identification des composés ostéogéniques de la nacre et vers les applications de la nacre en orthopédie clinique / With many exceptional qualities (biocompatible and osteogenic), nacre represents a natural biomaterial as a bone substitute. However, the osteogenic compounds in nacre are not yet known. Our work aims at the identification of the osteogenic compounds in nacre. The ESM (soluble ethanol matrix) is an extract of nacre that is shown to be osteogenic. From the ESM, we have tried several approaches to target and identify these compounds. Thanks to the coupling of MC3T3-E1 cells and the human osteoarthritis osteoblasts, we demonstrated that the cationic part of the ESM is osteogenic, without interaction with the anionic part. Calcium plays a role in the osteogenic activity of the ESM. Then, we created a cell line stably expressing a plasmid containing an osteogenic reporter gene (ATDC5 pMetLuc2 ColX promoter). Thanks to this cell line, we found out that the lipids and sugars in the ESM have an osteogenic effect. The peptides precipitated by TCA are also demonstrated to be osteogenic, which have led to their partial identification by LC-MS. These results allow us to move farther and faster towards the identification of osteogenic compounds in nacre and the applications of nacre in clinical orthopaedics

Atualmente a demanda mundial por cacau é superior à sua oferta, impulsionando a pesquisa e desenvolvimento de substitutos. Pesquisa conduzida recentemente evidenciou um potencial substituto ao submeter sementes de jaca dura a processos de fermentação, secagem e torração, resultando na produção de compostos voláteis similares aos do cacau. No entanto, o processo fermentativo foi realizado com a microbiota natural, o que impossibilita o direcionamento da produção de compostos de interesse. Desse modo, o objetivo do presente trabalho foi utilizar cultura starter de dois microrganismos isolados da fermentação da semente do cacau (Kluyveromyces marxianus e Saccharomyces cerevisiae) no processo fermentativo da semente de jaca dura, acompanhar as características da massa fermentativa, caracterizar microbiologicamente e avaliar os compostos voláteis produzidos. No primeiro capítulo são apresentados os dados referentes à primeira etapa do projeto, que envolveu a realização das fermentações em três lotes, contendo um tratamento sem inoculação de leveduras (controle) e dois tratamentos inoculados, sendo o KM, com K. marxianus, e o mix, com K. marxianus e S. cerevisiae. Neste capítulo também foram avaliadas as características da massa fermentativa ao longo do processo fermentativo (pH, exsudação, sólidos solúveis, acidez titulável e temperatura), o consumo de nutrientes (açúcares e proteínas), a produção de etanol e ácidos orgânicos (ácido acético e ácido lático) e a caracterização do conteúdo mineral. Observaram-se diferenças nos parâmetros para os tratamentos, principalmente devido à aceleração da fermentação no tratamento mix, que influenciaram na produção de compostos voláteis. Também foi evidenciada a presença de leveduras, bactérias láticas e bactérias acéticas ao longo do processo. No capítulo 2 estão apresentados os resultados obtidos na segunda etapa do projeto, que envolveu a análise dos compostos voláteis produzidos com perfil aromático semelhante ao do cacau, evidenciando a maximização da produção de alguns compostos voláteis que conferem aroma de chocolate, na presença de mix de culturas starters, indicando o potencial uso das mesmas na fermentação de jaca dura. / Currently the world demand of cocoa exceeds it\'s supply, leading the research and development of substitutes. Study recently conducted evidenced a potential substitute by subjecting hard jackfruit seeds to fermentation, drying and roasting processes, resulting in the production of volatile compounds to those of cocoa. However, the fermentative process was carried out with the natural microbiota, which makes it impossible to direct the production of interests compounds. Thus, the aim of the present work was the application of starter cultures of two microrganisms isolated from the cocoa beans fermentation (Kluyveromyces marxianus e Saccharomyces cerevisiae) in the fermentative process of hard jackfruit seeds, the monitoring of the fermentative mass characteristics, the microbiological characterization, and evaluation of volatile compounds produced. In the first chapter are presented the data refering to the first stage of the project, which involved the fermentation in three lots, containing a treatment without yeast inoculation (control) and two inoculated treatments, KM with K.marxianus, and MIX with K.marxianus and S. cerevisiae. In this chapter it was also evaluated the fermentative mass characteristics throughout the fermentation process (pH, exsudation, soluble solids, titratable acidity and temperature), the nutrients consumption (sugars and proteins), the production of ethanol and organic acids (acetic acid and lactic acid) and the characterization of mineral content. Differences were observed in the parameters for the treatments, mainly due to the acceleration of the fermentation in the MIX treatment, which influenced in the volatile compounds production. Also it was evidenced the presence of yeasts, lactic acid bacteria and acetic acid bacteria throughout the process. In chapter two are presented the results obtained in the second stage of the project, which involved the analysis of volatile compounds production and the aromatic profile similar to cocoa, evidencing the maximization of some volatile compounds production that confer chocolate aroma, in the presence of MIX of starters cultures, indicating their potential use in the hard jackfruit fermentation.

In the provided care for children placed in substitute residential facilities in the Czech Republic are in the context of European Union made demands to change some key aspects of its current structural frame. Aim of this master thesis is to provide in this context, through the analysis of mainly bibliographic sources, a complex overview of the system of substitute residential care in two EU countries, the Czech Republic and the Federal Republic of Germany. The thesis contains an insight into the activities of both systems, as well as comparatively processed answers to two initial research questions. The results of the research work on the answer to the question "What are the differences in the existing service network, regarding the work with the children placed in selected Czech and German children's homes?" show, that the established frame of the provided services is similar, but the qualitative and quantitative offer of the services is in practice reflected by different economic situations in both countries. The result of the second comparative research, answering the question "How are in the chosen countries determined the means of children rehabilitation in the selected children's homes?", shows, that the coordinated rehabilitation is in all its parts realized in both countries as consistent with the fulfilment of "the child's best interest" as possible. The most significant difference in reaching the optimal harmony of all segments of coordinated rehabilitation in these countries makes the application of support means to the work with the family, to the care for youth preparing for leaving the institution, to the realization of complex multidisciplinary care, or to fulfilment of an individual approach and planning. It is therefore desirable, that the Czech Republic, as well as the Federal Republic of Germany, orient themselves not only on the quality of provided help and care for the children placed in children's homes, but also on the future of young people, who are in the process of leaving the institution. This can be achieved by legislatively well-set structural system of substitute residential care, in which is through suitable service provided a valuable support in the context of coordinated rehabilitation. This master thesis can for the people interested in this topic expand the view on how the same mission regarding the children in substitute residential care is fulfilled by two advanced European countries, it can also be in this context an impulse to reflect on the form of a good practice in these institutions.

Submitted by Rosina Valeria Lanzellotti Mattiussi Teixeira (rosina.teixeira@unisantos.br) on 2015-04-22T14:51:02Z No. of bitstreams: 1 Priscila Larangeira Carvalho.pdf: 5761393 bytes, checksum: 8fed8a6dfcc8e65d04b881eed0e53508 (MD5) / Made available in DSpace on 2015-04-22T14:51:02Z (GMT). No. of bitstreams: 1 Priscila Larangeira Carvalho.pdf: 5761393 bytes, checksum: 8fed8a6dfcc8e65d04b881eed0e53508 (MD5) Previous issue date: 2013-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This dissertation discusses a research on the current role played by Psychologist in public health policies, particularly in the case of Substitute Network of Mental Health, Emerging closing (intervention) Hospital (Psychiatric) Nursing Home Anchieta. As a goal, try to understand where the "locus" in which professional psychology was inserted through the activities offered in Public Policy Health System (SUS), the city of Santos. Characterized as qualitative, exploratory development features, and the methodology used in the survey included: bibliographic (about SUS implementation in Santos, with an emphasis on mental health); consultation documents and files (the Municipal Health Santos, publicly available), information gathering (together with mental health professionals - through stories about his professional experience and operation services - during the period studied), and interviews (semi structured interviews with criteria: employment - public servant; academic - psychologist, and the service time - more than three years). Consisted of field research involving 12 subjects, divided into: 10 interviews and 02 reports, composing the content to be judged against the objectives. The analysis of the data collected in the interviews was carried out from the exhaustion of content and meaning of their narratives; thematic diversity of these narratives were structured three main data analysis, in obedience to the general objective and specific research: Attention Model - NAPS versus Anchieta; Blurred Role of the Psychologist in the interior of this model, and the Absence of Prevention in Mental Health. We conclude by proposing an alert to the class, aiming to offer support for reflection on new political contexts and health, in the field of Mental Health, which may go beyond the call of emergencies. / A presente dissertação aborda uma investigação sobre o atual papel ocupado pelo Psicólogo nas políticas públicas de saúde, em particular no caso da Rede Substitutiva de Saúde Mental, emergente do fechamento (intervenção) do Hospital (Psiquiátrico) Casa de Saúde Anchieta. Como objetivo, busca-se compreender qual o "locus" no qual o profissional de Psicologia foi inserido, mediante as atividades ofertadas nas Políticas Públicas de Saúde (SUS), no município de Santos. Caracterizada como qualitativa, seu desenvolvimento possui cunho exploratório, sendo que a metodologia utilizada pela pesquisa contou com: levantamento bibliográfico (sobre implantação do SUS em Santos, com ênfase na área da saúde mental); consulta de documentos e arquivos (da Secretaria Municipal de Saúde de Santos, disponíveis publicamente); coleta de informações (junto a profissionais da saúde mental - por meio de relatos a respeito de sua experiência profissional e do funcionamento de serviços - no decorrer no período estudado); e entrevistas (semi estruturadas, tendo como critério: vínculo empregatício ¿ servidor público; formação acadêmica ¿ psicólogo; e o tempo de serviço ¿ superior a três anos). Constou do campo de investigação a participação de 12 sujeitos, subdivididos em: 10 entrevistas e 02 relatos, que compôs o conteúdo a ser analisado à luz dos objetivos propostos. A análise dos dados coletados nas entrevistas foi realizada a partir do esgotamento de conteúdo e sentido de suas narrativas; da diversidade temática dessas narrativas foram estruturados três eixos principais de análise dos dados, em obediência ao objetivo geral e aos específicos da pesquisa: Modelo de Atenção - NAPS versus Anchieta; Indefinição do Papel do Psicólogo no interior desse modelo; e a Ausência da Prevenção em Saúde Mental. Conclui-se propondo um alerta à classe, visando ofertar subsídios para a reflexão sobre novos contextos políticos e de saúde, no campo da Saúde Mental, que possam ir além do atendimento das emergências.

A cicatrização de um alvéolo após a extração dental é uma resposta reparadora. Após a exodontia, a cicatrização espontânea irá levar à perda do volume e do formato do rebordo original. A preservação alveolar envolve qualquer procedimento que limite os efeitos da reabsorção pós-extração. O objetivo deste estudo foi avaliar o uso de um substituto ósseo xenogênico na preservação alveolar pós-extração dental comparado com a cicatrização espontânea em dentes anteriores da maxila com defeitos ósseos da parede vestibular maiores do que 50%. Foram tratados 13 pacientes com necessidade de exodontia de dente anterior da maxila com perda >50% da parede vestibular. Todas as exodontias foram realizadas sem retalho. Os pacientes foram alocados aleatoriamente em grupo teste: preservação alveolar com substituto ósseo (7 participantes) e grupo controle: cicatrização espontânea (6 participantes). O desfecho primário foi a alteração dimensional do rebordo alveolar calculada entre as imagens tomográficas de início (pós-exodontia) e depois de 4 meses da intervenção, na espessura 1mm abaixo da porção coronal da crista (HW-1). Os desfechos secundários foram as medidas vestibular e palatina, e os segmentos transversais HW-3 e HW-5. A medida HW-1 reduziu 51,21 % no grupo teste e 82,80% no grupo controle, com uma diferença intergrupos estatisticamente significante de 31,59%. Para as medidas transversais, houve redução estatisticamente significante tanto para HW-3 quanto para HW-5 entre os dois grupos. Em alvéolos com perda da parede vestibular maior que 50%, a utilização do substituto ósseo promoveu uma menor perda horizontal na ordem de 30%. / The healing process of post-extraction sockets is bone resorption. After tooth extraction, spontaneous healing will lead to loss of volume and shape of the original ridge. Alveolar ridge preservation involves any procedure that limits the effects of post-extraction resorption. The objective of this study was to evaluate the use of the xenogenic bone substitute in the post-extraction alveolar preservation compared to spontaneous healing in anterior maxilla teeth with vestibular wall defects greater than 50%. Thirteen patients with anterior maxillary tooth extraction with a > 50% buccal wall loss were treated. All the surgeries were made flapless. Patients were randomly assigned to a test group: alveolar preservation with bone substitute (7 participants); and control group: spontaneous healing (6 participants). The primary outcome was the dimensional alteration of the alveolar ridge calculated between the tomographic images at the beginning (post-extraction) and after 4 months of the intervention, at the thickness 1mm below the coronal portion of the crest (HW-1). Secondary outcomes were measures buccal and palatine, and HW-3 and HW-5 cross-sections. The HW-1 measure reduced 51.21% in the test group and 82.80% in the control group, with a statistically significant intergroup difference of 31.59%. For the other horizontal measurements, there was a statistically significant reduction for both HW-3 and HW-5 between the two groups. In sockets with buccal wall loss greater than 50%, the use of the bone substitute provided a 30% lower horizontal loss.

A cicatrização de um alvéolo após a extração dental é uma resposta reparadora. Após a exodontia, a cicatrização espontânea irá levar à perda do volume e do formato do rebordo original. A preservação alveolar envolve qualquer procedimento que limite os efeitos da reabsorção pós-extração. O objetivo deste estudo foi avaliar o uso de um substituto ósseo xenogênico na preservação alveolar pós-extração dental comparado com a cicatrização espontânea em dentes anteriores da maxila com defeitos ósseos da parede vestibular maiores do que 50%. Foram tratados 13 pacientes com necessidade de exodontia de dente anterior da maxila com perda >50% da parede vestibular. Todas as exodontias foram realizadas sem retalho. Os pacientes foram alocados aleatoriamente em grupo teste: preservação alveolar com substituto ósseo (7 participantes) e grupo controle: cicatrização espontânea (6 participantes). O desfecho primário foi a alteração dimensional do rebordo alveolar calculada entre as imagens tomográficas de início (pós-exodontia) e depois de 4 meses da intervenção, na espessura 1mm abaixo da porção coronal da crista (HW-1). Os desfechos secundários foram as medidas vestibular e palatina, e os segmentos transversais HW-3 e HW-5. A medida HW-1 reduziu 51,21 % no grupo teste e 82,80% no grupo controle, com uma diferença intergrupos estatisticamente significante de 31,59%. Para as medidas transversais, houve redução estatisticamente significante tanto para HW-3 quanto para HW-5 entre os dois grupos. Em alvéolos com perda da parede vestibular maior que 50%, a utilização do substituto ósseo promoveu uma menor perda horizontal na ordem de 30%. / The healing process of post-extraction sockets is bone resorption. After tooth extraction, spontaneous healing will lead to loss of volume and shape of the original ridge. Alveolar ridge preservation involves any procedure that limits the effects of post-extraction resorption. The objective of this study was to evaluate the use of the xenogenic bone substitute in the post-extraction alveolar preservation compared to spontaneous healing in anterior maxilla teeth with vestibular wall defects greater than 50%. Thirteen patients with anterior maxillary tooth extraction with a > 50% buccal wall loss were treated. All the surgeries were made flapless. Patients were randomly assigned to a test group: alveolar preservation with bone substitute (7 participants); and control group: spontaneous healing (6 participants). The primary outcome was the dimensional alteration of the alveolar ridge calculated between the tomographic images at the beginning (post-extraction) and after 4 months of the intervention, at the thickness 1mm below the coronal portion of the crest (HW-1). Secondary outcomes were measures buccal and palatine, and HW-3 and HW-5 cross-sections. The HW-1 measure reduced 51.21% in the test group and 82.80% in the control group, with a statistically significant intergroup difference of 31.59%. For the other horizontal measurements, there was a statistically significant reduction for both HW-3 and HW-5 between the two groups. In sockets with buccal wall loss greater than 50%, the use of the bone substitute provided a 30% lower horizontal loss.

Made available in DSpace on 2016-04-28T18:22:10Z (GMT). No. of bitstreams: 1 Cacilda Aparecida da Silva.pdf: 586246 bytes, checksum: fa79d8b0b9f2d7bc0e906b38b09ddd67 (MD5) Previous issue date: 2010-10-15 / Secretaria da Educação do Estado de São Paulo / This research aims at understanding critically the construction process of meanings shared by a group of teachers from a public school of São Paulo concerning the job/ role of the substitute teacher. More specifically, this paper describes and discusses the substitute teacher activity, having as focuses two activity systems: understanding this professional s job at the school and developing a reading proposal as a support to the substitute teacher s job. To do so, meetings among the voluntary participants were carried out among titular teachers (this researcher among them), temporary teachers (OFAs), and substitute teachers. During the meetings, each participant expressed their point of view about the job/ role of the substitute teacher. The organization of this paper is based on the collaborative critical methodology (MAGALHÃES, 2006), in order to set a locus of critical collaboration aimed at a critical reflection about the actions of the participants on negotiating understandings and proposals which could provide transformation to the substitute teacher s reality in the context of the school. The study of the continuous academic background of this teacher as a collaborative and critical professional in the relationship with their partners is supported in the discussions of Vygotsky, Leontiev, Freire (1996); Engestrom (2009) LIBERALI( 2004 and 2008) and MAGALHÃES, (2004 and 2006), among others. As a result of the initial discussions, a proposal based on reading was begun, based on the Proposta Curricular do Estado de São Paulo (2008) and on the Projeto de Leitura nas Diversas areas do Conhecimento (LACE- fase 1,2002). The focus on reading was decided by the group of participant teachers, since one of the main focuses of the school in which most students have difficulties in reading and writing. The results show that: a) the initial meanings of the participants about the substitute teacher underwent some transformations except for one of the titular teachers who attended this research; b) the relations among people in the group of teachers led to a recognition of the importance of the HTP sessions use to discuss the theories which involve the teacher s practice; c) the discussed proposals have features of traditional teaching; d) the material initially developed isn t complied with the curricular proposal (2008) of São Paulo / Este trabalho tem como objetivo compreender criticamente o processo de construção de significados compartilhados por um grupo de professores de uma escola da Rede Pública Estadual de São Paulo, quanto ao trabalho/papel do professor eventual . Mais especificamente, descreve e discute a atividade do professor eventual, com foco em dois sistemas de atividade: a compreensão do trabalho desse profissional na escola e a produção de uma proposta com leitura como apoio para o trabalho do professor eventual. Para tanto, foram realizados encontros com um grupo de participantes voluntários: professores titulares (entre os quais esta pesquisadora), OFAs e professores eventuais. Nessas ocasiões, cada participante pode expor a sua visão sobre o trabalho/papel do eventual. Esta pesquisa está organizada com base na Metodologia Crítica de Colaboração (MAGALHÃES, 2006), para criação de lócus de colaboração crítica, voltada à reflexão crítica sobre as ações dos participantes na negociação de compreensões e propostas que trouxessem transformação à realidade do professor eventual, no contexto da escola. O estudo sobre a formação contínua desse professor, como profissional colaborativo e crítico na relação com seus pares, está apoiado nas discussões de Vygotsky (1934), Leontiev (1978), de Freire (1970/2005); Engestrom (1999 ), LIBERALI ( 2004 e 2008) e MAGALHÃES (2004 e 2006), entre outros. Como resultado das discussões iniciais, foi principiada a produção de uma proposta de trabalho em leitura, com base nos pressupostos da Proposta Curricular do Estado de São Paulo (2008) e no Projeto de Leitura nas Diversas áreas do Conhecimento (LACE- fase 1,2002). O foco na leitura foi decidido pelo grupo de professores participantes, uma vez que esta é uma questão central da escola, em que a grande maioria dos alunos apresenta dificuldades em ler e escrever. Os resultados apontam que: a) os sentidos iniciais dos participantes sobre o professor eventual sofreram transformações, exceto para um dos professores efetivos participantes; b) as relações, entre o grupo de professores, levaram à constatação da relevância das sessões de HTPC direcionadas para discussão das teorias que envolvam as práticas do professor na escola, em lugar de discussões utilitárias; c) as propostas discutidas apresentam características de um ensino tradicional; d) o material inicial produzido não está voltado para a proposta curricular (2008) do Estado de São Paulo

Ce travail de thèse a eu comme objectif la mise en place et la validation d’une méthodologie expérimentale pour le suivi de l’évolution in-vitro de substituts osseux à base de phosphates de calcium. Du phosphate dicalcique dihydraté (DCPD, CaHPO4·2H2O) et du phosphate tricalcique bêta (β-TCP, β-Ca3(PO4)2) ont été choisis comme matériaux modèles de deux grandes classes de substituts osseux: les “biosolubles” (sujets à dissolution après implantation) et les “biorésorbables” (sujets à résorption cellulaire après implantation). Pour l’étude des phénomènes de dissolution et de reprécipitation observés lorsque les phosphates de calcium sont plongés en solution, ces matériaux ont été produits sous forme d’échantillons microporeux (60% de porosité pour le DCPD, 75% pour le β-TCP) et soumis à des tests de dissolution in-vitro en conditions statiques ou dynamiques (sans ou avec renouvellement du liquide) dans différentes solutions tamponnées à pH physiologique (TRIS et PBS) et pour des durées s’étalant entre 30 minutes et 2 mois. L’analyse des propriétés physico-chimiques, microstructurales et mécaniques des échantillons avant et après immersion a permis d’évaluer l’influence du type de milieu et des conditions de test choisies sur l’évolution des échantillons. Une attention particulière a été prêtée à la caractérisation mécanique: la technique de micro-indentation instrumentée sphérique a été préférée à autres essais plus conventionnels. Cette technique permet d’évaluer plusieurs paramètres tels que la dureté et le module de Young de façon quasi non-destructive et à une échelle locale. En conséquence, l’utilisation de la micro-indentation s’est avérée d’une grande aide pour le suivi des caractéristiques d’échantillons dégradés qui présentaient un gradient de propriétés entre la surface (où le processus de dégradation commence) et le cœur (sujet à des changements sur plus long terme). La dernière partie de cette étude a été dédiée à l’étude du deuxième phénomène qui entraine la résorption de substituts osseux in-vivo, à savoir la résorption cellulaire. Pour cela des essais cellulaires avec des cellules précurseurs d’ostéoclastes ont été réalisés sur des échantillons denses de β-TCP pur ou dopé avec 5% molaire de magnésium. L’addition de cet élément est censée modifier les propriétés du matériau (notamment sa solubilité) et, par conséquence, modifier le comportement cellulaire. Les résultats des tests ont confirmé la cytocompatibilité des deux types de β-TCP, mais ont également mis en avant une difficulté d’activation des ostéoclastes. Deux des causes possibles seraient liées à la topographie de surface des échantillons et au relargage des ions calcium suite à la dissolution du matériau. / The present Ph.D. thesis work was aimed to establish and assess an experimental methodology to monitor the in-vitro evolution of calcium phosphate (CaP) bone substitutes. Dicalcium phosphate dihydrate and beta-tricalcium phosphate were chosen as model of two main classes of bone substitutes: “biosoluble” ones (which undergo dissolution after implantation) and “bioresorbable” ones (which undergo cellular resorption after implantation). In order to study the dissolution and precipitation phenomena, which take place once CaPs are immersed in solution, these materials were produced in the form of micro-porous samples (60% of porosity for DCPD, 75% for β-TCP) and used for dissolution tests in-vitro in static and dynamic conditions (without or with liquid renewal) in different buffered solutions at physiologic pH (TRIS and PBS) and for periods of time ranging between 30 minutes and 2 months. The analysis of the physico-chemical, microstructural and mechanical properties of the samples before and after immersion allowed to evaluate the influence of the chosen medium and immersion conditions on the evolution of the specimens. Particular attention was paid to the mechanical characterisation: instrumented spherical micro-indentation was preferred to other more conventional tests. This technique enables the evaluation of several parameters such as the hardness and the Young’s modulus in a quasi-non-destructive way and on a local scale. As a consequence, the use of micro-indentation proved to be of great help for monitoring the characteristics of the degraded specimens, which presented a gradient of properties between the surface (where the degradation process starts) and the core (subject to changes on a longer period). The last part of this work was focused on the study of the second main phenomenon, which takes part in the in-vivo resorption of bone substitutes, that is to say the cellular resorption. For this purpose, cellular tests with osteoclast-precursor cells were carried out on dense samples made of pure and magnesium-doped β-TCP (5 mol.% of Mg). The addition of magnesium was aimed to modify the properties of the material and, as a consequence, the cellular behavior. The results confirmed the cytocompatibility of both types of β-TCP, but they also showed a difficult activation of osteoclasts. Two of the possible causes would be linked to the topography of the surface of the specimens and to the release of calcium ions due to the dissolution of the material.

Les substituts osseux synthétiques servent au remplacement temporaire des tissus osseux, favorisent la formation, la croissance et la survie de l’os et sont biorésorbables. Aucun matériau monophasé ne remplissant complètement ces exigences, un matériau composite bioinspiré est une alternative possible. L’objectif de cette thèse était par conséquent d’étudier la synthèse et les propriétés de deux composites biocéramiques/biopolymères : des hydrogels physiques de chitosane minéralisés avec de l’apatite, et une hardystonite architecturée imprégnée par des hydrogels physiques de chitosane. Afin d’obtenir le premier matériau, deux approches ont été développées. La première a consisté à fabriquer des hydrogels physiques de chitosane puis à les minéraliser avec de l’apatite ; la formation de microcapillaires se produit avec des conditions de synthèse spécifiques, et les précipités d’apatite ont été trouvés uniquement à la surface des hydrogels. La seconde approche consiste à convertir des suspensions homogènes contenant le phosphate de calcium et le chitosane en hydrogels de chitosane minéralisés par l’apatite. Les suspensions ont été préparées soit avec un mélange simultané, soit avec des mélanges successifs de suspensions phosphates de calcium avec les solutions de chitosane. Des agrégats minéraux plus petits avec une distribution plus uniforme ont été formés avec la méthode des mélanges successifs. Cela est attribué à une meilleure homogénéité, une viscosité plus faible et l’absence de chitosane. De manière générale, trois paramètres influencent les propriétés mécaniques d’hydrogels de chitosane minéralisés : la base utilisée pour la gélification (déterminant la vitesse de gélification : une grande vitesse conserve l’enchevêtrement des chaînes, résultant en une meilleure élasticité) ; la densité de la réticulation physique (cela induit un module de conservation plus important) et la force ionique (qui mène au désenchevêtrement des chaînes de chitosane, donc, à un faible module de conservation). Cette compréhension a permis l’utilisation de ces suspensions de phosphate de calcium-chitosane en tant qu’encre pour l’impression 3D. Les hydrogels de chitosane et les hydrogels minéralisés ne sont pas cytotoxiques. Pour fabriquer le second matériau, une encre pré-céramique a été imprimée en 3D puis frittée pour former une céramique d’hardystonite cristalline. Les scaffolds d’hardystonite ont été imprégnés par la solution de chitosane, converties ensuite en hydrogels physiques de chitosane. A plus forte concentration de chitosane, la viscosité de la solution était plus grande et l’imprégnation de la matrice plus lente. Avec une vitesse de gélification plus importante, qui dépend de la base utilisée pour la gélification, la perte de poids est plus faible pendant la gélification. L’hydrogel de chitosane a partiellement rempli les pores participant au support de charges externes et à la dissipation d’énergie par rupture. / Bone substitutes, an approach to attend social demand for bone healing and reparation, are temporary replacements of bone tissue, promote bone formation and growth and finally are bioresorbed. No single material meets these requirements; an alternative is a bioinspired composite material. The objective of this thesis was thus to study the synthesis and properties of two bioceramics/biopolymer composites: chitosan physical hydrogels mineralized with apatite and hardystonite scaffolds impregnated with chitosan physical hydrogels. To obtain the first material, two strategies were developed. The first one consisted in the fabrication of chitosan physical hydrogels and its subsequent mineralization with apatite; the formation of micro-capillaries occurred under particular synthesis conditions, and apatite precipitates were found only on the surface of hydrogels. The second strategy consisted in a simultaneous conversion of chitosan-calcium phosphate suspensions into chitosan-apatite hydrogels. The suspensions were prepared by sequential or simultaneous mixing of calcium and phosphate suspensions with chitosan solutions. Smaller and more uniformly distributed mineral aggregates were formed following sequential mixing, attributed to higher homogeneity, lower viscosity and no-presence of chitosan. This enabled the use of these chitosan-calcium phosphate suspensions as inks for 3-D printing. In general, three factors impacted the mechanical properties of mineralized chitosan hydrogels: the base used for gelation (determining the gelation rate: a higher rate preserved chain entanglement, resulting in higher elasticity); the density of physical crosslinks (hence a higher storage modulus) and the ionic strength (that led to chitosan chain disentanglements, thus, low storage modulus). Chitosan hydrogels and mineralized hydrogels were not cytotoxic, having no deleterious effects on osteoblasts proliferation. To fabricate the second material, pre-ceramic ink was 3-D printed and then sintered to form crystalline hardystonite ceramic. Hardystonite scaffolds were impregnated with chitosan solution that was, next, converted to chitosan physical hydrogel. At higher chitosan concentration, viscosity of solution was higher and scaffold impregnation was lower. At higher gelation rate, which depend on base used for gelation, lower weight loss during gelation. Chitosan hydrogel partially filled the pores contributing to bearing of external loads and to energy dissipated by fracture.

This thesis aims at systematically studying the possibilities of minimizing devastating consequences of high-speed rail vehicle derailments by appropriate measures and features in the train design including the running gear. Firstly, an empirical database is established containing as much relevant information as possible of past incidents and accidents that have occurred at substantial running speeds due to mechanical failure close to the interface between the running gear and the track. Other causes that ultimately brought the train in a derailed condition are also covered. Although various accidental circumstances make each derailment a unique event, certain patterns appear to emerge which lead to several critical vehicle parameters capable of influencing the outcome of a derailment or preventing a derailment to occur. Secondly, the possibility of preventing wheel climbing derailments after an axle journal failure is studied by implementing mechanical restrictions between wheelsets and bogie frame. In this respect, a multi body system (MBS) computer model is developed to account for such an axle failure condition, which is successfully validated on the basis of two authentic passenger car events. In order to study the overall post-derailment vehicle behaviour, in particular the wheelsets’ vertical motion and lateral deviation on sleepers, a comprehensive MBS post-derailment module is developed and implemented in the commercially available software GENSYS. The model detects wheel-sleeper impact conditions and applies valid force resultants calculated through linear interpolation based on a pre-defined look-up table. The table was constructed through exhaustive finite element (FE) wheel to concrete sleeper impact simulations utilising the commercially available software LS-DYNA. The MBS post-derailment module has been validated successfully in several stages, including a correct prediction of the derailing wheelset’s trajectory over ten consecutive sleepers in comparison with an authentic passenger vehicle derailment event. An extensive simulation analysis on the feasibility of utilizing alternative substitute guidance mechanisms attached to the running gear on rail vehicles is presented, as means of minimizing the lateral deviation. Three low-reaching guidance mechanisms attached onto the running gear (bogie frame, brake disc and axle journal box) are analysed in terms of geometrical parameters for a successful engagement with the rail in order to prevent large lateral deviations after twelve different derailment scenarios. Three conventional coupled passenger trailing cars are investigated in terms of lateral deviation and vehicle overturning tendency after derailments on tangent and curved track. This is performed as a function of various vehicle design features and parameters such as: maximum centre coupler yaw angle, carbody height of centre of gravity, coupler height and additional running gear features. In a similar manner, the articulated train concept is investigated in terms of the post-derailment vehicle behaviour as a function of different inter-carbody damper characteristics and running gear features. / QC 20100701