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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
381

Estudo da cinética de ligação de cálcio e fluoreto à superfície de estreptococos e sua importância como reservatórios de íons no biofilme dental / Kinetics of calcium and fluoride binding to the surface of streptococci and the importance of these ions as mineral reservoirs in dental biofilm

Leitão, Tarcísio Jorge, 1986- 20 August 2018 (has links)
Orientador: Livia Maria Andaló Tenuta / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-20T14:29:42Z (GMT). No. of bitstreams: 1 Leitao_TarcisioJorge_D.pdf: 1707027 bytes, checksum: 3a9ae05a28621a678e53355a8ac4c250 (MD5) Previous issue date: 2012 / Resumo: O estudo das formas de retenção de íons no biofilme dental e dos mecanismos de disponibilização destes para o fluido do biofilme é importante para o entendimento do papel destes reservatórios em interferir na dinâmica do processo de formação da cárie dental. Sabe-se que o fluoreto (F) está ligado ao biofilme por interação com íons cálcio (Ca). Um dos reservatórios que estes dois íons podem formar é o F ligado ao Ca na superfície de bactérias e proteínas da matriz extracelular. Quando o pH do biofilme diminui após a exposição à carboidratos fermentáveis, a liberação destes íons poderia diminuir o potencial de perda mineral, mas isto não está claro na literatura. Além disso, há evidências de que um pré-bochecho com Ca aumente a retenção de F no biofilme e entender a cinética de ligação e liberação destes íons pode ser uma estratégia importante para o desenvolvimento de métodos que os mantenham por mais tempo no biofilme dental. Assim, o objetivo deste trabalho de tese foi estudar a cinética de ligação de Ca e F na superfície bacteriana e sua liberação em função do tempo e do pH do meio. A bactéria Streptococcus mutans cepa IB 1600 foi utilizada em todos os experimentos. Foram realizados experimentos sequenciais in vitro para avaliar a cinética de ligação e liberação de Ca à superfície de S. mutans utilizando soluções contendo 0 (controle), 1 ou 10 mM de Ca. A capacidade de liberação deste reservatório também foi avaliada em situação que simula a queda do pH. Além disso, foi avaliada a capacidade e cinética de ligação de F, na concentração de 52,6 ?M F (1 ppm F), mediada por Ca, às bactérias. A quantidade de Ca e F ligada às bactérias foi estimada após extração desses íons da superfície bacteriana com ácido forte, utilizando dosagem colorimétrica e eletrodo íon-específico, respectivamente. Curvas e parâmetros de cinética de ligação e liberação foram calculados e avaliados como fenômenos bioquímicos. Os resultados mostraram que a ligação de Ca à S. mutans é função da concentração do meio e mostrou ser um fenômeno rápido, onde a máxima saturação é alcançada nos primeiros minutos. Por outro lado, a cinética de liberação mostrou ser um fenômeno mais lento, onde significativa quantidade de íons é encontrada ligada às bactérias mesmo após 60 min de tratamento com solução livre de Ca. Ademais, a liberação parece ser função direta do pH do meio e não influenciada pela quantidade de Ca previamente ligada. A ligação de F às bactérias também mostrou ser um fenômeno rápido, mas não dependente da concentração de Ca ligado às bactérias. A ligação deste último também não foi afetada pela presença de F no meio. De forma geral, os resultados sugerem que a ligação de Ca na superfície bacteriana pode funcionar como um importante reservatório capaz de perdurar por um significativo período de tempo e ser prontamente liberado para o fluido do biofilme durante uma queda de pH. Além disso, a ligação de F às bactérias parece não ser influenciada pela presença de Ca / Abstract: The study of the retention of mineral ions in dental biofilm and their release to the biofilm fluid is important to understand the role of these reservoirs to interfere with the dental caries process. It is known that fluoride (F) is bound to the biofilm by interaction with calcium (Ca) ions. One type of reservoir formed is Ca-F bridging in bacteria surface and in proteins of the extracellular matrix. When pH drops in dental biofilm after a sugar exposure and a subsaturation state is established, favoring dental demineralization, the ions released from these reservoirs could reduce the potential for mineral loss, but this is unclear in the literature. Furthermore, there is evidence that a Ca pre-rinse increases F retention in biofilm and to evaluate the kinetics of binding and release these ions could be an important strategy to the development of methods that keep them for longer periods in the dental biofilm. Thus, this study aimed to evaluate the kinetics of Ca and F binding and release from bacteria surface as a function of time and pH. Streptococcus mutans IB 1600 was used in all experiments. In vitro studies were conducted to evaluated the kinetics of Ca binding and release using treatments solutions containing 0, 1 or 10 mM Ca. The release capacity also was evaluate after a pH drop. Furthermore, the binding capacity and kinetics of fluoride at 52.6 ?M F (1 ppm F) to bacteria was evaluated. The amount of Ca and F bound to bacteria after equilibrium with treatment solutions was determined in the bacterial pellet after treatment with strong acid, using a colorimetric method and F electrode, respectively. Curves and parameters of binding and release were calculated and treated as biochemical phenomena. Results showed that Ca binding to S. mutans is concentration-dependent and rapid, with maximum saturation achieved in the first minutes. On the other hand, Ca release was shown to be a slower phenomenon, since a significant amount of ions was still bound after 60 min of treatment with Ca-free solution. Moreover, the Ca release seems to be a direct function of media pH and not influenced by the amount of Ca previously bound. F binding to bacteria also shown to be a rapid phenomenon, but independent of Ca concentration in bacteria. Also, Ca binding was not affected by F presence in the treatment solution. In summary, the results suggest that ions bound to bacterial surface could be an important reservoir able to persist for a significant period of time and be released into the biofilm fluid during a pH drop. Furthermore, F binding to bacteria seems not to be influenced by Ca previously bound / Doutorado / Cariologia / Doutor em Odontologia
382

Inter-relação do iodo e do flúor no metabolismo de ovinos jovens / Iodine and fluoride in young ovine metabolism

Prestes, Danívia Santos 20 July 2007 (has links)
Mineral supplementation of is a well-known factor contributing to productivity in sheep or cattle herds. However, little is known about mineral interactions in these species. The objective of the present work was to evaluate the inter-relation of iodine (I) and fluoride (F) in young ovine metabolism and the thyroid gland. Two experiments were conducted; first it was analyzed the dynamics of urinary I excretion in sheep. Five lambs were used in a repeated measurement protocol. After a 15-day adaptation period urine samples were collected (control group), then animals received 3 different 15-day treatments (0,05; 0,42; and 0,8 mg of I/kg DM) consecutively. Punctual (8 hour interval) and 24 hour total urine samples were collected. No differences in I excretion among treatments or collection time. Also, there were no differences in urinary creatinine levels among treatments or collection time, except between 16:00 and 24:00 hours in the medium dose. No significant correlation was found between urinary I and creatinine. In a second experiment, it was evaluated the effect of chronic fluoride administration in thyroid function and histology in sheep. Twelve ram lambs were allocated into 2 groups: Control which received 5g NaCl + 0,2 mg of I/Kg DM and treated group which received the same treatment plus sodium fluoride (4,7 mg F/ Kg BW) daily for 150 days. Blood samples were collected at 60, 90, 120, and 150 days for determination of F, I T3 and T4. At the same time points, total 24-hour urine production was collected for measurement of F and I. After euthanasia, at 150 days of treatment, thyroid gland was removed for histopathological and morphometrical analyses. No differences were found between or within groups for urinary I. Also no differences were found for T3 and T4 nor serum I between groups or among time points. No histological alterations were found in the thyroid. In conclusion, urinary I excretion is not a reliable parameter to access I status in animals with supplementation within the recommended levels. Additionally, data related to Iodine-fluoride interactions cannot be used across species, since the effect of fluoride on the thyroid appears to have specie dependant intensity / A suplementação mineral dos rebanhos é um fator que influi de forma relevante no índice de produtividade, porém, há carência de novos estudos relacionados à situação e interação dos elementos minerais nos rebanhos e nisso está alicerçado o objetivo do presente trabalho: avaliar a inter-relação do iodo (I) e do flúor (F) no metabolismo de ovinos jovens, através da avaliação do efeito do F sobre a glândula tireóide. Para tanto, foram realizados dois experimentos. O primeiro teve o objetivo de analisar a dinâmica da excreção urinária de I em ovinos. Assim, utilizaram-se cinco animais. Antes de iniciar o tratamento com I, coletou-se amostras de urina (grupo controle), posteriormente, os animais passaram a receber três diferentes tratamentos (0,05; 0,42 e 0,8 mg de iodo/kg de matéria seca), consecutivamente. Cada tratamento teve duração de 15 dias. Foram coletadas amostras de urina equivalente às 24 horas e amostras pontuais (intervalo de oito horas). Não houve diferença na excreção urinária de I entre tratamentos e entre horários de coleta. Os valores urinários de creatinina não diferiram entre os horários de coleta dentro de cada tratamento, exceto entre as 16:00 e às 24:00 horas, na dose média. A relação iodo/creatinina não demonstrou correlação. No segundo experimento, o objetivo foi avaliar o efeito da administração crônica de fluoreto de sódio na função e histologia da glândula tireóide de ovinos. Foram utilizados doze ovinos, os quais foram divididos em dois grupos: Controle, o qual recebeu somente sal iodado (5g NaCl/animal+0,2mg de iodo/kg MS) e o grupo Tratado, que recebeu sal iodado (5g NaCl/animal+0,2mg de iodo/kg MS) adicionado de fluoreto de sódio (4,7mg F/kg de peso corporal), durante um período de 150 dias. Amostras de sangue foram coletadas aos 60, 90, 120 e 150 dias de tratamento para análise sérica de I e F, Triiodotironina (T3) e Tetraiodotironina (T4). Ainda, nesse mesmo intervalo de tempo, coletou-se a urina, correspondente às 24 horas, para análise da excreção urinária de I e F. Após o sacrifício dos animais, a glândula tireóide foi removida para posterior exame histopatológico e morfométrico. Quanto ao I urinário, não foi observada diferença estatística entre os grupos controle e tratado e dentro de cada grupo, entre os períodos. As concentrações de T3 e T4 não diferiram estatisticamente entre ambos os grupos e dentro de cada grupo, nos diferentes tempos de tratamento. Assim como, também não houve diferença estatística nos teores de I sérico. Quanto à avaliação histopatológica da glândula tireóide, não foram observadas alterações. De um modo geral, é possível concluir que a excreção urinária de iodo, quando utilizada como estimativa do status nutricional deste elemento, deve ser considerada com parcimônia, principalmente se forem utilizadas doses dentro do intervalo de recomendação requerido para a espécie. Outrossim, conclui-se que dados referentes a inter-relação do iodo e flúor não podem ser aplicados de uma espécie para outra, pois o efeito do flúor sobre a glândula tireóide não ocorre na mesma forma e intensidade
383

Administração crônica de flúor: efeitos no metabolismo e na reprodução de ovinos / Chronic fluoride administration in sheep: effects on metabolism and reproduction

Filappi, Andreane Rosa 12 June 2008 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Mineral nutrition has a major effect upon animal productivity. Recently, the use different sources of phosphorus in supplements have been discussed, these have higher fluoride (F) content than traditional sources. Although F is considered an essential element, most biological interest is turned to its toxic effects. Therefore, the objective of the present study was to evaluate F metabolism, its effects upon liver function, seminal quality, including oxidative profile, and, histomorphometric variables of the reproductive system of ram lambs chronically exposed to sodium fluoride (NaF). Twelve 5 month old ram lambs, maintained on alfalfa hay (3% BW) and nonfluorinated water ad libitum were divided in 2 groups: Control, which received 5g NaCl/animal + 0.2 mg I/Kg DM daily; and treated that received the same as control plus NaF (4.7 mg F/Kg BW). Treatments were given by gavage, daily, for 150 days. Blood, urine, fecal and ejaculate samples were collected. After 150 days of treatment animals were euthanized and the pineal gland, testicle, tail of the epididymus, vas deferens, and samples of bone and liver were collected. Serum, urine, and bone values of F were higher in treated animals. No differences were observed in whole pineal F content. Serum protein, albumin, and cholesterol concentrations were not different between groups, also, no differences were detected in the plasma AST and GGT activity. No histological changes observed in the liver, testicle, tail of the epididymus, and vas deferens. In seminal samples, no differences were observed in motility, viability, and spermatic morphology, concentration of reduced glutathione, and zinc. The concentration of thiobarbituric acid reactive substances (TBARS) and copper were lower in F treated animals than in controls. In conclusion, chronic F treatment leads to F deposition in bones. The capacity of lambs to deal with F excess is different than what is reported in other species. Chronic fluorine intake in lambs does not lead to structural alterations of the reproductive system, nor affects seminal quality. However, sub clinical alterations in the seminal oxidative profile can occur and lead to impairment of fertility. / A suplementação mineral é um fator que contribui de forma relevante sobre o índice de produtividade dos animais. Nos últimos anos, tem-se discutido a utilização de fontes alternativas de fósforo na alimentação animal, as quais contêm um teor maior de flúor (F) comparado a outras fontes convencionalmente utilizadas. O F é considerado um elemento essencial, mas o interesse biológico está voltado aos seus efeitos tóxicos. Assim, o objetivo do presente estudo foi avaliar o metabolismo do F, investigar o efeito sobre o metabolismo hepático e avaliar as características seminais, indicadores do metabolismo oxidativo do sêmen e os parâmetros histomorfométricos do sistema reprodutivo de ovinos tratados cronicamente com fluoreto de sódio (NaF). Para tanto, foram utilizados 12 machos, com idade aproximada de cinco meses. Os animais foram divididos em grupo Controle, que recebeu apenas sal iodado (5g de NaCl/animal + 0,2mg I/kg matéria seca) e, grupo Tratado, que recebeu sal iodado adicionado de NaF (4,7mg F/kg de peso corporal). Esses sais foram administrados diariamente, via sonda oro-esofágica, por um período de 150 dias. Coletaramse amostras de sangue, urina, fezes e sêmen. Ao fim do período experimental, após a eutanásia, coletaram-se a glândula pineal e amostras de osso, fígado, testículo, cauda do epidídimo e canal deferente. Os teores séricos, urinários e ósseos de F foram superiores nos animais Tratados. Quanto ao teor de F na glândula pineal, não houve diferença entre os grupos. Em relação às concentrações séricas de proteína total, albumina e colesterol total, não houve diferença entre os grupos, assim como não houve na atividade das enzimas gama glutamiltransferase e aspartato aminotransferase. No exame histológico do fígado, não foram observadas alterações. No sistema reprodutivo, na comparação entre os grupos, não foram observadas diferenças no percentual de motilidade, viabilidade e morfologia espermática; na concentração da glutationa reduzida seminal; no teor de zinco seminal e ainda, no peso testicular, morfometria e histologia do testículo, cauda do epidídimo e canal deferente. A concentração de substâncias reativas ao ácido tiobarbitúrico e o teor de cobre no sêmen foram menores no grupo Tratado. De um modo geral, é possível concluir que a administração crônica de F induz ao acúmulo desse elemento nos ossos. A capacidade orgânica de acúmulo ósseo e excreção urinária do F nos ovinos jovens é diferente de outras espécies animais, não podendo ser aplicados resultados entre espécies. A administração crônica de F para ovinos jovens não afeta a estrutura tecidual do sistema reprodutivo, bem como a qualidade seminal. Entretanto, alterações inaparentes relacionadas ao perfil oxidativo seminal podem ocorrer, interferindo na fertilidade dos animais.
384

Synthèse de pinces à fluorures dérivées d'aminoacides pour l'imagerie TEP / Synthesis of fluoride pincers derived from amino acids for PET imaging

Bernard, Julie 28 November 2014 (has links)
Ce travail de thèse réalisé à l’Institut de Chimie Moléculaire de l’Université de Bourgogne et en collaboration avec le PET Research Centre, porte sur la synthèse d’une nouvelle classe de pinces à fluorures dérivés d’aminoacides dans le but de piéger les ions [18F]-fluorures par formation d’une liaison B-F et d’évaluer leur potentiel en tant qu’agent d’imagerie TEP. Les travaux ont tout d’abord concerné la conception, la synthèse et la caractérisation des nouveaux sels de phosphoniums boronatés et trifluoroborates dérivés d’aminoacides. Ainsi, par quaternisation de l’o-boronate phényl phosphine avec des β-iodo amino esters ou des γ-iodo amino esters, les sels correspondants sont obtenus sans racémisation et avec des rendements atteignant 88%. La saponification des phosphoniums boronatés aminoesters donne les dérivés avec la fonction acide libre, tandis que l’acidolyse par HCl mène à l’amine correspondante offrant ainsi, l’opportunité d’un couplage ultérieur à une biomolécule. Ensuite, les dérivés trifluoroboratés sont facilement préparés par réaction de KHF2 en solution dans un mélange hydroalcoolique. Les études de stabilités en milieux aqueux des phosphoniums o-trifluoroborates aminoacides ont permis d’établir que ces dérivés sont extrêmement stables à l’hydrolyse. Enfin, la [18F]-radiosynthèse des sels de phosphonium boronatés a été étudiée selon deux méthodes: par échange isotopique 18F-19F direct à partir d’un trifluoroborate et par marquage direct d’un sel de phosphonium boronaté en présence d’un mélange de fluorures [18F] et KHF2. Intéressement, après une synthèse totale de 50 minutes comprenant le séchage azéotropique, la synthèse et la purification, [18F]-203c a été obtenu avec un rendement radiochimique de 10% corrigé de la décroissance, une pureté radiochimique ≥97% et une activité spécifique de 0.13 GBq/µmol. / This thesis project, which is part of a collaboration between the Institut de Chimie Moléculaire de l’Université de Bourgogne and the Positron Emission Tomography Research Centre, is about the synthesis of fluoride pincers derived from amino acids based on 18F-B bond construction to get a new class of PET imaging agents. First, this project concerned the design, synthesis and characterisation of new boronato and trifluoroborato phosphonium amino acid salts. Quaternisation of o-boronate phenyl phosphine with β-iodo amino esters or γ-iodo amino ester leads to the corresponding salts without racemisation and in yields up to 88%. Saponification of boronato phosphonium amino esters afford the free carboxylic acid derivatives, whereas HCl acidolysis leads to the corresponding amino compounds which offers the opportunity of further biomolecule coupling. Then, o-trifluoroborate phosphonium salts are efficiently prepared by reaction with KHF2 in solution on hydroalcoholic mixture. The kinetic stabilities of these o-trifluoroborate phosphoniums have shown extremely stable compounds to hydrolysis. Finally, [18F]-radiosyntheses of phosphonium salts was studied according to two methods : by 18F-19F isotopic exchange from trifluoroborate or by carrier added preparation of [18F]-fluoride ions from boronate phosphonium salts. Satisfactingly, after a total synthesis of 50 minutes (including azeotropic drying, synthesis and purification), [18F]-203c was obtained with a RCY on 10% decay corrected, a RCP ≥ 97% and a specific activity of 0.13 GBq/µmol.
385

Identifying dental restorative treatment need in healthy young adults at individual and population level

Kämppi, A. (Antti) 22 September 2015 (has links)
Abstract Dental caries is one of the most widespread diseases in the world. In the industrialized world the situation improved until the 1990s, after which the good development is claimed to have almost stagnated. One of the aims of this cross-sectional study was to investigate caries prevalence in a young male population. Another aim was to investigate ways to find individuals needing restorative treatment. The hypothesis in this study was that caries prevalence among Finnish young males born in the 1990s was similar or even poorer compared to those born in earlier decades. Polarization of dental caries was still expected to exist. It was also hypothesized that caries prevalence is geographically unevenly distributed in Finland. The Finnish Defence Forces screening protocol was hypothesized to be valid for detecting individuals with restorative treatment need. Finally, it was hypothesized that restorative treatment need at the individual level associates well with a well-chosen set of questions concerning dental symptoms, dental attendance, treatment history and health behaviour. Study material consisted of 255 female and 13,564 male (total n=13,819) conscripts. Anamnestic data, along with information about the socioeconomic status, educational level and place of residence just before military service, were collected with computer-based questionnaire in connection with the oral screening (50 questions and 108 sub-questions). Validity of the screening protocol was evaluated in a sub-population (74 conscripts) examined using both the screening and the ICDAS classification. The screening protocol was validated using the ICDAS criteria and it proved to be well in accord with it considering restorative treatment need at the individual level. The study revealed that on average the conscripts had 1.4 decayed teeth (DT), third molars excluded. The number of decayed, earlier restored or extracted teeth due to caries (DMFT) was 4.1. Ten per cent had about half of the caries lesions and 30% had 90%, suggesting that polarization still exists. It was also found that living in areas with high fluoride content in drinking water, living in urban areas and a Swedish-speaking home municipality were protective factors against dental caries. A positive response to eight questions of a statistically selected set of ten questions reliably predicted restorative treatment need (OR 69.27). / Tiivistelmä Karies on yksi maailman laajimmalle levinneistä sairauksista. Menneinä vuosikymmeninä karies väheni merkittävästi aina 1990-luvulle saakka, jonka jälkeen myönteinen kehitys on hidastunut. Tämän tutkimuksen tavoitteena oli tutkia korjaavan hoidon tarpeen määrää nuorten miesten keskuudessa. Tutkimuksen toinen tavoite oli tutkia tapoja erottaa terveistä korjaavan hoidon tarpeessa olevat henkilöt. Tutkimuksen oletuksena oli, että karieksen esiintyvyys 1990-luvun alussa syntyneiden suomalaismiesten joukossa on vastaavalla tai huonommalla tasolla kuin 1970-luvun alussa. Lisäksi oletettiin, että kyseisessä ikäluokassa karies on polarisoitunut. Oletuksena oli myös, että karieksen esiintyvyys on maantieteellisesti epätasaisesti jakaantunut. Tutkimuksessa oletettiin myös, että Suomen Puolustusvoimien käyttämällä suunterveyden seulontamenetelmällä voidaan tunnistaa luotettavasti yksilötasolla korjaavan hoidon tarpeessa olevat yksilöt. Viimeisenä oletuksena oli, että korjaavan hoidon tarve yksilötasolla olisi arvioitavissa seulonnan ja hyvin valitun kysymyspaketin perusteella tutkituissa ikäluokissa. Tämän poikittaistutkimuksen satunnaistettu tutkimusaineisto koostui 13819 varusmiehestä (255 naista ja 13564 miestä) sekä esitietoihin perustuvasta aineistosta joka kerättiin seulonnan yhteydessä tietokonepohjaisella kyselylomakkeella (50 kysymystä ja 108 alakysymystä). Seulonnan tulokset vastasivat hyvin tarkastusta, jossa vauriot diagnosoitiin ICDAS kriteereitä käyttäen. Tutkimus osoitti myös että, keskimäärin yksilöllä oli 1,4 korjaavan hoidon tarpeessa olevaa hammasta viisaudenhampaat pois lukien. Aiemmin korjattujen, karieksen takia poistettujen ja karieksen vaurioittamien hampaiden lukumäärä oli 4,1. Kymmenellä prosentilla tutkimusjoukosta oli puolet kaikista vaurioista ja vastaavasti kolmanneksella tutkituista oli 90 prosenttia kaikista vaurioista. Juomaveden fluoripitoisuus ja asuminen kaupungissa tai ruotsinkielisessä kunnassa olivat suojaavia tekijöitä korjaavan hoidon tarpeen suhteen. Kymmenen esitietokysymystä valittiin tilastollisesti 108 kysymyksen joukosta. Positiivinen, korjaavalle hoidolle altistava, vastaus vähintään kahdeksaan näistä kymmenestä kysymyksestä ennusti luotettavasti (OR 69,27) korjaavan hoidon tarvetta yksilötasolla.
386

Piezoelektriska filament : från garn till textil applikation / Piezoelectric filaments - from yarn to textile application

Backe, Carin, Skelte, Gabrielle January 2015 (has links)
Piezoelektriska material används flitigt i olika sensorer då de kan generera en mätbar elektrisk signal vid tryck eller töjning. Arbetet utreder hur ett piezoelektriskt garn innehållandes Polyvinyldiflourid (PVDF) påverkas av faktorer som långvarig mekanisk deformation, fukt och värme. Fokus har legat på det piezoelektriska garnets egenskaper men projektet undersöker också hur integrering i tyg samt applicering i en textil produkt fungerar. Det piezoelektriska garnet har utsatts för ett stort antal tester. I de flesta tester har proverna utvärderats genom cyklisk deformation i en extensometer. Det piezoelektriska garnet har undersökts genom experiment i laboratoriemiljö, praktiska tester i textila applikationer samt vid statistisk analys. Det kan konstateras att yttre faktorer så som fukt och temperatur har inverkan på garnets piezoelektriska effekt. Långvariga tester avslöjar hur garnet uppvisar en längdförändring vid deformation som bidrar till garnets minskade signalstyrka. Garnet kan framgångsrikt integreras i tyg genom sömnad vid rätt inställning för stygnlängd, där högre stygnlängd ger bättre resultat. Samma metod kan användas för att konstruera en piezoelektrisk sensor som appliceras i en träningsstrumpa. Slutsatsen av detta arbete är att parametrar som fukt, krypningsbeteende samt strukturell variation i de individuella PVDF-filamenten har en betydande effekt på det piezoelektriska garnets elektriska signal. Potential i garnets förmåga att fungera som sensor kan ses genom att garnet integrerats med tyg på ett framgångsrikt sätt i en träningsstrumpa för mätning av fotnedsättning. Det kvarstår mycket gällande forskning kring piezoelektriska filament och garn. Vidare forskning i ämnet kommer kunna leda till nya innovativa applikationsmöjligheter som kan komma till nytta inom olika delar av samhället, inte minst inom medicinska användningsområden. / Piezoelectric materials are frequently used in different sensors as they can generate a measurable electrical signal during applied pressure or when subjected to extension. This project examines how a piezoelectric yarn containing Polyvinylidene fluoride (PVDF) is affected when exposed to moisture, heat and long-term mechanical deformation. Focus has been directed towards investigating the properties of the piezoelectric yarn as well as how it can be applied in textile fabrics and textile applications. The piezoelectric yarn has been subjected to a series of tests. Most of the samples have undergone cyclic deformation in an extensometer during tests. The piezoelectric yarn has been examined by experiments in laboratory environment, practical tests in textile applications as well as by statistical analysis. It can be stated that factors such as moisture and temperature have influence on the piezoelectric effect of the yarn. Long-term tests reveal how the yarn displays a change in length while undergoing deformation, which contributes to the diminished signal strength of the yarn. The piezoelectric yarn can successfully be integrated in a piece of fabric by the means of sewing when using correct stitch- length, where higher stitch-length gives a higher signal output. The same method can be applied to construct a piezoelectric sensor used in a training sock. This project can conclude that parameters such as moisture, creep-behaviour and structural variation within the PVDF-filaments have a significant effect on the signal created by the piezoelectric yarn. The potential of the yarn as a sensor can be seen by successfully applying it to a textile structure as well as in a training sock that can monitor the fore and rear foot while running. It can be stated that much remains to be studied in this particular research area regarding piezoelectric filaments and yarns. Further research in the subject will lead to new innovative applications that can be of use in different parts of society, not to say the least in the area of medicine.
387

Efeito de dentifrício fluoretado e aplicação profissional de fluoreto no controle de cárie de esmalte e de dentina radicular = Effect of fluoridated toothpaste and professional fluoride application on caries control in enamel and root dentine / Effect of fluoridated toothpaste and professional fluoride application on caries control in enamel and root dentine

Fernandez, Constanza Estefany, 1985- 02 October 2015 (has links)
Orientador: Jaime Aparecido Cury / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-26T12:48:18Z (GMT). No. of bitstreams: 1 Fernandez_ConstanzaEstefany_D.pdf: 2276340 bytes, checksum: 1735521ece2fdcfcf30384ce9aabe6df (MD5) Previous issue date: 2015 / Resumo: Dentifrício fluoretado (DF) de concentração convencional (1000-1500-ppm) é eficiente no controle da cárie de esmalte, entretanto seu efeito na cárie radicular pode não ser o mesmo devido à maior susceptibilidade da dentina à cárie. Essa diferença poderia ser compensada pelo uso diário de DF de maior concentração (DF-5000-ppm) ou da combinação da aplicação profissional de fluoreto (APF) com uso diário de DF-1100-ppm. Entretanto, além dessa comparação nunca ter sido pesquisada, a diferença do efeito entre esmalte e dentina tem sido pouco estudada num único experimento. Em acréscimo, o efeito de DF-5000-ppm na dentina radicular se limita a estudos do efeito da remineralização. O Capítulo 1 dessa tese descreve a validação do modelo de biofilme de Streptococcus mutans (SM) para estudar o efeito dose resposta de DF na redução da desmineralização (des-) do esmalte e dentina radicular. No Capítulo 2, foi avaliado in situ o efeito dose-resposta de DF e o efeito de DF-5000-ppm ou a combinação de APF com DF-1100-ppm na redução da des- e ativação da remineralização do esmalte e dentina radicular. No capítulo 1, biofilmes de SM foram crescidos sobre blocos de esmalte e dentina radicular, os quais foram expostos à sacarose 8x/dia e 2x/dia às soluções fluoretadas contendo 0, 150, 450 e 1350-ppm. Ao final do experimento, a concentração de F foi determinada nos biofilmes e nos blocos a dureza de superfície (DS) e F-solúvel em ácido (FAp). No capítulo 2, num desenho cruzado, duplo-cego de 4 fases de 14 dias cada, 18 sujeitos utilizaram dispositivo palatino contendo blocos hígidos e cariados de esmalte e de dentina radicular. Biofilme foi permitido ser acumulado sobre os blocos, os quais foram expostos à sacarose 8x/dia ou 3x/dia, nos blocos hígidos ou cariados, respectivamente. Os tratamentos foram: 1) Dentifrício-placebo (DP); 2) DF-1100; 3) DF-5000; 4) único pré-tratamento dos blocos com APF (gel acidulado, 12300-ppm) combinado com DF-1100 (APF+DF-1100). Dentifrícios foram usados 2x/dia. No fluido e porção sólida do biofilme foram determinadas as concentrações de F. Nos blocos a porcentagem de perda (%PDS) ou recuperação da DS (%RDS), nos substratos hígidos e cariados respectivamente, como também as áreas de lesão de cárie (?S). F-solúvel em álcali e ácido também foram determinadas nos blocos. Os resultados in vitro mostraram que o modelo apresentou efeito dose-resposta, havendo em função da concentração de F um aumento de F no biofilme e um aumento da concentração de FAp e decréscimo da %PDS nos blocos de esmalte-dentina. O efeito do F na redução da desmineralização no estudo in vitro foi menor na dentina do que o observado no esmalte. Os dados in situ mostraram efeito dose-resposta para a concentração de F nos dentifrícios (0;1100;5000) para a maioria das variáveis analisadas, à exceção do ?S para dentina-cariada. Na comparação dos tratamentos, APF+DF-1100 foi estatisticamente mais eficaz que DF-5000 reduzindo desmineralização e ativando a remineralização da dentina radicular. Os resultados dessa tese sugerem que o efeito de DF no controle de cárie de esmalte ou dentina é concentração dependente, sendo a combinação com APF mais relevante para dentina-radicular que para esmalte / Abstract: Fluoride dentifrice (FD) of conventional concentration (1,000-5,000 ppm) is efficient for enamel caries control; however, it is possible that their effect might not be the same for root-caries because dentine is more caries susceptible. This difference could be compensated by the daily use of high concentration FD (5,000 ppm-FD) or by the combination of professional fluoride application with daily use of 1,100 ppm-FD. Besides, this comparison has never been researched; the difference of effect between enamel and dentine has been scarcely evaluated in the same experiment. In addition, the effect of 5,000-FD has been focused essentially on root-caries remineralization. Chapter 1 of this thesis describes the validation of a Streptococcus mutans (SM) biofilm model to study the dose-response effect of FD in the reduction of demineralization (de-) on enamel and root-dentine. In Chapter 2, it was evaluated in situ the FD dose-response effect and the effect of FD-5000 ppm or the combination of acidulated phosphate fluoride (APF) application with DF-1100 ppm in the reduction of de- and activation of remineralization on enamel and root-dentine. In chapter 1, SM biofilms were grown on enamel and root-dentine slabs, and exposed 8x/day to sucrose and 2x/day to fluoridated solutions containing 0, 150, 450 and 13,50-ppm. At the end of the experiment, F-concentration in the biofilms was determined and surface hardness (SH) and acid-soluble-F (FAp) were assessed in the slabs. In chapter 2, in a cross-over and blind design of 4 phases of 14 days each, 18 subjects wore a palatine appliance containing sound and carious slabs of enamel and root-dentine. Biofilm was allowed to accumulate on the slabs and while the sound slabs were exposed to sucrose 8x/day the carious were exposed 3x/day. The treatment groups were: 1) F-placebo dentifrice (PD); 2)1,100-FD; 3) 5,000-FD; 4) slabs pre-treated with APF (F-gel, 12,300 ppm-F) combined with daily use of 1100-FD (APF+1,100-FD). Dentifrices were used 2x/day. The F concentration was determined in fluid and solid portions of the biofilm. In slabs, the percentage of SH loss (%SHL) or recovery (%RSH) was estimated in sound and carious slabs, respectively, as well as the caries lesion area (?S). Acid-soluble-F and alkali-soluble-F concentrations were also determined in the slabs. The in vitro results showed that the model presented a dose-response effect, with an increment of F concentration in the biofilm and an increment of FAp in function of F concentration of the treatments. Also, %SHL showed a reduction in enamel and dentine slabs according to the treatments. F effect on the reduction of demineralization was lower on dentine than that observed on enamel. The in situ data showed a dose-response effect to F concentration in the dentifrices (0;1,100;5,000) for most response variables, with the exception of ?S for carious-dentine. In the treatments comparison, APF+1100-FD was statistically more effective than 5000-FD at reducing demineralization and activating remineralization in root-dentine. The results from this thesis suggest that the FD effect in enamel and dentine caries control is concentration-dependent, and the combination with APF was more relevant to root-dentine that to enamel / Doutorado / Cariologia / Doutora em Odontologia
388

Fluorosis in the early permanent dentition: evaluating gene-environment interactions

Bhagavatula Naga, V R N Pradeep 01 July 2009 (has links)
No description available.
389

Inhibition of different strains of Streptococcus mutans at different concentrations of Fluoride and Chlorhexidine

Tutumlu, Christian, Lund, André January 2021 (has links)
ABSTRACT Background: The most common species associated with dental caries is Streptococcus mutans. Different Streptococcus mutans adhesion biotypes, SpaP A/B/C and Cnm/Cbm, with ability to predict individual caries development have recently been identified. Aim: The aim of the study was to investigate if there was a difference in growth ability of the Streptococcus mutans adhesion biotypes and their relative sensitivity to biocides such as fluoride and chlorhexidine in vitro. We also aim to compare the potency of biocides in vitro to those concentrations used in the clinic. Methods: Culturing of the Streptococcus mutans biotypes in a planktonic solution with and without fluoride and chlorhexidine. Used concentrations: 3.5-4500 parts per million fluoride and 15-500 parts per million chlorhexidine. Optical density was used to measure growth under the different conditions. Results: The tests with fluoride showed a similar dose dependent inhibition of growth for all 6 biotypes of Streptococcus mutans. The tests with chlorhexidine showed a major inhibition of growth for the concentration 62 parts per million which inhibited growth more than 500 parts per million. All biotypes had a similar proliferation pattern without any biocide present. Conclusion: All tested biotypes of Streptococcus mutans had a similar pattern of sensitivity to the different concentrations of biocides and cultivation conditions used.
390

Controlling Coherency Phase Boundary for High Performance Batteries / 蓄電池の高性能化に資する相境界面制御

Yoshinari, Takahiro 25 March 2019 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第21877号 / 人博第906号 / 新制||人||216(附属図書館) / 2018||人博||906(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 内本 喜晴, 教授 吉田 寿雄, 准教授 藤原 直樹 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

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