Dissertations / Theses on the topic 'Fluorapatit'

Die vorliegende Dissertation beschäftigt sich mit Wachstum und Aufbau von Fluorapatit-Gelatine-Nanokompositaggregaten. Diese Aggregate werden im sogenannten Doppeldiffusionsversuch biomimetisch erzeugt und ihre äußere Form bzw. Formentwicklung lässt sich anhand eines fraktalen Modells bis ins Detail nachvollziehen. Sie zeigen einen komplexen inneren Aufbau, in dem die Makromoleküle der organischen Komponente einerseits im Zentrum jeder Nanoeinheit und andererseits zu Strängen, den sogenannten Fibrillen, zusammengelagert am Aufbau der Kompositaggregate beteiligt sind. Im Fall des Kompositkeims ist die innere Architektur in hoher Detailstufe verstanden, auch wenn -- insbesondere bezüglich der späteren Wachstumsphasen -- eine Reihe ungeklärter Fragestellungen verbleibt. Ein zentrales Ergebnis der vorliegenden Arbeit bildet die Entdeckung eines weiteren Wachstumstypen, der im Vergleich zu den bekannten, fraktalen Kompositaggregaten grundsätzliche Unterschiede bezüglich des inneren und äußeren Aufbaus zeigt. Der Grund für die andersartige Formentwicklung liegt in der Versteifung der organischen Komponente durch eine vorangegangene Einlagerung von Calciumionen, wie sowohl experimentell als auch mit atomistischen Computersimulationen gezeigt werden konnte. Aufgrund der hohen Komplexität des Systems ist es bislang allerdings nicht möglich, lokale Ionen-Konzentrationen und pH-Werte vor bzw. während Nukleation und Wachstum der Kompositaggregate im Doppeldiffusionsversuch zu bestimmen. Deshalb wurde ein Ersatzversuch -- der sehr ähnlich strukturierte Aggregate erzeugt, sich aber mit rechnerischen Methoden analysieren lässt -- entworfen und untersucht. Anhand dieser Ergebnisse konnte erstmals die "Geschichte" von Fluorapatit-Gelatine-Nanokompositaggregaten detailliert nachvollzogen werden. Da über die Rolle der Gelatine beim Wachstum der Kompositaggregate nur wenig bekannt ist, wurde eine Reihe von Versuchen durchgeführt, in denen Gelatinen mit verschiedenen Molekülmassenverteilungen eingesetzt wurden. Es stellte sich heraus, dass für selbstorganisiertes und insbesondere fraktales Wachstum der Kompositaggregate lange, möglichst wenig gestörte Makromoleküle von zentraler Wichtigkeit sind. Um die Funktion der organischen Komponente für das Kompositwachstum näher zu untersuchen, wurden Oberflächen von Kompositkeimen mit rasterkraftmikroskopischen Methoden studiert. Durch Säuberung der Oberflächen konnten Austrittsstellen der organischen Komponente durch die Oberfläche der Kompositkeime identifiziert werden. Damit konnte gezeigt werden, dass die organische Komponente aus dem Inneren des Festkörpers teilweise durch die Oberfläche dringt und somit während des Wachstums weit in das Gel hineinreichen sollte. Für die mesoskopische Strukturbildung der Kompositaggregate spielen intrinsische elektrische Felder eine essenzielle Rolle. Deshalb wurde bislang eine Wirkung externer elektrischer Felder auf das Wachstum der Kompositaggregate vermutet. Im Rahmen der vorliegenden Arbeit wurde herausgearbeitet, dass es zwar zu keiner direkten Beeinflussung kommen kann, jedoch in den elektrodennahen Bereichen des Gels eine Ordnung der organischen Moleküle durch externe elektrische Felder zu erwarten ist. Dies könnte eine Wirkung auf wachsende Kompositaggregate zeigen. Da diese Effekte auch aufgrund der elektrischen Felder um die dipolaren Kompositaggregate zu erwarten sind, könnte eine ähnliche Strukturierung der Gelatine in der Nähe der wachsenden Kompositaggregate stattfinden. Insgesamt wurden in dieser Arbeit eine Reihe grundlegender Beiträge zur Erforschung der biomimetisch erzeugten Fluorapatit-Gelatine-Nanokompositaggregate geleistet. Es konnten neue Erkenntnisse zur inneren und äußeren Architektur der Kompositaggregate, zu Mechanismen der Morphogenese und deren wichtigsten Einflussgrößen sowie zum Verständnis der chemisch-physikalischen Vorgänge auf atomarer Größenskala gewonnen werden. Als besonders fruchtbar erwies sich die Verbindung von Experimenten mit theoretischen Untersuchungen, so dass dieser Weg auch in Zukunft grundlegende Erkenntnisse bei der Erforschung der Biomineralisation verspricht und weiterhin verfolgt werden sollte.

Die vorliegende Dissertation beschäftigt sich mit Wachstum und Aufbau von Fluorapatit-Gelatine-Nanokompositaggregaten. Diese Aggregate werden im sogenannten Doppeldiffusionsversuch biomimetisch erzeugt und ihre äußere Form bzw. Formentwicklung lässt sich anhand eines fraktalen Modells bis ins Detail nachvollziehen. Sie zeigen einen komplexen inneren Aufbau, in dem die Makromoleküle der organischen Komponente einerseits im Zentrum jeder Nanoeinheit und andererseits zu Strängen, den sogenannten Fibrillen, zusammengelagert am Aufbau der Kompositaggregate beteiligt sind. Im Fall des Kompositkeims ist die innere Architektur in hoher Detailstufe verstanden, auch wenn -- insbesondere bezüglich der späteren Wachstumsphasen -- eine Reihe ungeklärter Fragestellungen verbleibt. Ein zentrales Ergebnis der vorliegenden Arbeit bildet die Entdeckung eines weiteren Wachstumstypen, der im Vergleich zu den bekannten, fraktalen Kompositaggregaten grundsätzliche Unterschiede bezüglich des inneren und äußeren Aufbaus zeigt. Der Grund für die andersartige Formentwicklung liegt in der Versteifung der organischen Komponente durch eine vorangegangene Einlagerung von Calciumionen, wie sowohl experimentell als auch mit atomistischen Computersimulationen gezeigt werden konnte. Aufgrund der hohen Komplexität des Systems ist es bislang allerdings nicht möglich, lokale Ionen-Konzentrationen und pH-Werte vor bzw. während Nukleation und Wachstum der Kompositaggregate im Doppeldiffusionsversuch zu bestimmen. Deshalb wurde ein Ersatzversuch -- der sehr ähnlich strukturierte Aggregate erzeugt, sich aber mit rechnerischen Methoden analysieren lässt -- entworfen und untersucht. Anhand dieser Ergebnisse konnte erstmals die "Geschichte" von Fluorapatit-Gelatine-Nanokompositaggregaten detailliert nachvollzogen werden. Da über die Rolle der Gelatine beim Wachstum der Kompositaggregate nur wenig bekannt ist, wurde eine Reihe von Versuchen durchgeführt, in denen Gelatinen mit verschiedenen Molekülmassenverteilungen eingesetzt wurden. Es stellte sich heraus, dass für selbstorganisiertes und insbesondere fraktales Wachstum der Kompositaggregate lange, möglichst wenig gestörte Makromoleküle von zentraler Wichtigkeit sind. Um die Funktion der organischen Komponente für das Kompositwachstum näher zu untersuchen, wurden Oberflächen von Kompositkeimen mit rasterkraftmikroskopischen Methoden studiert. Durch Säuberung der Oberflächen konnten Austrittsstellen der organischen Komponente durch die Oberfläche der Kompositkeime identifiziert werden. Damit konnte gezeigt werden, dass die organische Komponente aus dem Inneren des Festkörpers teilweise durch die Oberfläche dringt und somit während des Wachstums weit in das Gel hineinreichen sollte. Für die mesoskopische Strukturbildung der Kompositaggregate spielen intrinsische elektrische Felder eine essenzielle Rolle. Deshalb wurde bislang eine Wirkung externer elektrischer Felder auf das Wachstum der Kompositaggregate vermutet. Im Rahmen der vorliegenden Arbeit wurde herausgearbeitet, dass es zwar zu keiner direkten Beeinflussung kommen kann, jedoch in den elektrodennahen Bereichen des Gels eine Ordnung der organischen Moleküle durch externe elektrische Felder zu erwarten ist. Dies könnte eine Wirkung auf wachsende Kompositaggregate zeigen. Da diese Effekte auch aufgrund der elektrischen Felder um die dipolaren Kompositaggregate zu erwarten sind, könnte eine ähnliche Strukturierung der Gelatine in der Nähe der wachsenden Kompositaggregate stattfinden. Insgesamt wurden in dieser Arbeit eine Reihe grundlegender Beiträge zur Erforschung der biomimetisch erzeugten Fluorapatit-Gelatine-Nanokompositaggregate geleistet. Es konnten neue Erkenntnisse zur inneren und äußeren Architektur der Kompositaggregate, zu Mechanismen der Morphogenese und deren wichtigsten Einflussgrößen sowie zum Verständnis der chemisch-physikalischen Vorgänge auf atomarer Größenskala gewonnen werden. Als besonders fruchtbar erwies sich die Verbindung von Experimenten mit theoretischen Untersuchungen, so dass dieser Weg auch in Zukunft grundlegende Erkenntnisse bei der Erforschung der Biomineralisation verspricht und weiterhin verfolgt werden sollte.

Apatite based glass-ceramics are some of the most bioactive materials found to date. They do not require fibrous encapsulation and bond to bone directly through an apatite layer. Apatite based glass-ceramics exhibit relatively poor biaxial flexural strength, hence limiting their applications to non-load bearing implants. The addition of mica results in a material that is highly machinable, and provided that a suitable interlocking microstructure can be produced, the strength will be increased. The aim of this work is to investigate how altering the heat treatment affects the crystallisation and the final mechanical properties of three different compositions of glass-ceramic. The glass system studied is the ternary glass system; barium fluorphlogopite (Bao.sMgafSiaAlOiojFz), fluorapatite (CaiofPO^eFz) and cordierite (MgzAUSisOis). The three compositions differ by the mol% of fluorapatite forming feedstock in the precursor glass. Glass-ceramics formed by heat-treating a glassy precursor are investigated using differential scanning calorimetry, kinetic neutron diffraction and scanning electron microscopy. The mechanical properties of the samples are characterised by their biaxial flexural strength and Vickers hardness. The phases formed and the microstructures of the samples are linked to the mechanical properties and an assessment of the final material's implant suitability is made.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão
Bioactive borate glass has presented superior results then bioactive silicate glasses, when compared its conversion rates in apatite and its potential of bioactivity. In this work, new Borate glasses with the basic 60B2O3 - 4P2O5 - 18Na2O – xCaF2 – (18-xCaO), com x = 0, 5 e 10 % wt were synthesized, and investigated the influence of CaF2 addition on bioactivity of samples in vitro, in a period of 28 days in a simulator of the body fluid (SBF). This bioactivity was investigated by means of X-ray diffraction (DRX), Raman Spectroscopy, FTIR and by the measure of pH. DRX measures, prior to immersion, presented wide bands, evidencing the amorphous structure of glasses. The results of density, thermal analysis, XRD, Raman and FTIR show that the addition of CaF2, until 10 % wt, did not cause significant changes in samples network structure. The thermal stability for all samples was calculated from DSC data and all presented values up to 120°C. The results of pH of SBF solution show increase from for 24 hours, which contributes to the dissolution of the outermost layer of the glass and the precipitation of apatite. In XRD data for 60B sample soaked in SBF for 7 days, there was formation of crystalline peaks, at 26° and 32° (2ϴ), in all measures. These peaks correspond to patterns of hydroxyapatite (HA). The XRD spectra in 60B5CaF and 60B10CaF, soaked in SBF for 7 days, presented peaks in 28°(2ϴ) corresponding to fluorapatite (FA), due to the presence of CaF2 in these glasses. Raman and FTIR measurements confirmed what was measured by XRD, showing characteristic peaks of HA and FA for all the samples. Results show that the prepared samples present potential for being used as biomaterials in biomedical applications, such as orthopedics, dentistry and tissue engineering.
Vidros boratos bioativos têm apresentado resultados superiores aos vidros silicatos bioativos, quando comparamos suas taxas de conversão em apatita e seu potencial de bioatividade. Neste trabalho sintetizamos novos vidros boratos com a composição básica 60B2O3 - 4P2O5 - 18Na2O – xCaF2 – (18-xCaO), com x = 0, 5 e 10 % em massa, e investigamos a influência da adição de CaF2 na bioatividade das amostras in vitro, em um período de 28 dias, em um simulador do fluído corporal (SBF). As medidas de DRX, antes da imersão, apresentaram bandas largas, comprovando a estrutura amorfa dos vidros. E verificou-se por meio das análises de Densidade, análise térmica, DRX, Raman e FTIR, que a adição de CaF2 até 10%, em massa, não provocou grandes mudanças estruturais na amostras. Por meio da calorimetria exploratória diferencial, determinamos a estabilidade térmica dos vidros que apresentaram valores acima de 120°C. A bioatividade foi investigada por meio das técnicas de difração de raios-X (DRX), espectroscopia Raman e FTIR, e pela medida do pH da solução SBF. Os resultados obtidos mostraram que, em 24h, houve um aumento no pH da solução SBF, o que contribui para a dissolução da camada mais externa do vidro e sua conversão em apatita. Nos difratogramas (DRX) para as amostras imersas por 7 dias, houve a formação de picos cristalinos, em 26° e 32° (2ϴ), em todas as amostras medidas. Esses picos correspondem aos padrões de hidroxiapatita. A presença de CaF2 na composição das amostras imersas por 7 dias apresentou picos em 28° (2ϴ) correspondendo a fluorapatita. A intensidade destes picos apresentou um aumento em função do tempo de imersão, durante todo período estudado. As medidas de Raman confirmaram os resultados do DRX, apresentando para todas as amostras espectros característicos da hidroxiapatita em 960 cm-1 . As amostras preparadas com CaF2 apresentaram picos em 965 cm-1 , que corresponde a fluorapatita. O FTIR confirmou os resultados apresentados no DRX e Raman, em que todas as amostras apresentaram um pico centrado em 1041 cm-1 para a hidroxiapatita e 1042 cm-1 característico para a fluorapatita. Os resultados demonstram que as amostras preparadas apresentam potencial para serem usados como biomateriais em aplicações biomédicas, como ortopedia, odontologia e engenharia de tecidos.

    Luminescentni nanokristali (nanofosfori) na bazi fluorapatita (FAP-a) dopirani elementima retkih zemalja idealni su kontrastni agenti za bio-medicinske primene, kao što su detekcije, snimanja, praćenja i terapije ćelija kancera. Kancer je jedna od najčešćih bolesti modernog doba čiji uspeh lečenja zavisi od rane dijagnostike i neinvazivnog tretmana. Luminescentne nanočestice mogu uneti inovativnu paradigmu u lečenje kancera kombinovanjem biosnimanja, dijagnostike i tretmana. Za studije fluorescentnih biosnimanja nanokristali fluorapatita dopirani retkim zemljama kao kontrastni agenti pružaju značajne prednosti u vidu velikih kontrasta i dugotrajnosti luminescencije, i što je još važnije visoke biokompatibilnosti, netoksičnosti i bioaktivnosti. Glavni ciljevi ove doktorske disertacije su sinteza novih luminescentnih multifotonskih bionanomaterijala na bazi fluorapatita dopiranih jonima prazeodimijuma (Pr³⁺), njihova karakterizacija i evaluacija  primene za fluorescentna biosnimanja kancera. Sintezom nanoprahova u umerenim uslovima metodom ko-precipitacije, a potom sušenjem na 110 ^oC i kalcinacijom na temperaturama od 700 i 1000 ^oC očekuje se pronalaženje najboljih uslova za dobijanje novih nanofosfora koji bi našli i različite bio-medicinske primene u oblasti fluorescentnih biosnimanja. Proučavane su tri vrste PrFAP nanokristala, sa 0,1%, 0,5% i 1% atomskih procenta Pr³⁺, zajedno sa nedopiranim FAP kontrolnim uzorkom. Nivoi energije aktivator jona Pr³⁺ sadrže metastabilna multipletna stanja koja nude mogućnosti efikasnih emisionih linija u više boja u FAP nanokristalima, kao i u infracrvenoj i ultravioletnoj oblasti spektra. Metodom ko-precipitacije na sobnoj temperaturi (25 ^oC), a potom sušenjem na 110 ^oC, sintetisani su monofazni heksagonalni nanokristali PrFAPs nepravilnog sfernog oblika. Termičkom analizom sintetisanih uzoraka, na osnovu detektovanih temperaturnih opsega procesa dekarbonacije i dehidroksilacije, utvrđene su temperature kalcinacije od 700 i 1000 oC. Termička analiza i karakterizacija uzoraka su pokazale da Pr³⁺ joni dovode do stabilizacije FAP strukture na višim temperaturama, što je pripisano unosu lantanoidnih jona sa specifičnim magnetnim osobinama u sistem i stvaranju jačih privlačnih sila sa O^2- anjonima. Nanokristali sušeni na 100 ^oC i kalcinisani na 1000 ^oC, zbog prisustva defekata kristalne rešetke koji zadržavaju emisiju Pr³⁺ jona, nisu pokazali luminescentne karakteristike od značaja za primene u medicinskim fluorescentnim biosnimanjima. Kalcinacijom uzoraka na 700 ^oC izrađen je novi tip aktiviranih fluorapatitnih nanokristala dopiranih prazeodimijumom (PrFAPa) sa ekscitaciono-emisionim profilima u vidljivom delu spektra. Fizičko-hemijska karakterizacija potvrdila je sferne kristale heksagonalne strukture do nanometrske veličine od oko 20 nm. Kvantno-hemijske kalkulacije predvidele su da se joni Pr³⁺ ugrađuju u kristalnu rešetku FAP nanokristala na položaju Ca2 (6h), što je praćeno deformacijama pozicije F^- jona. Pretpostavljeni mehanizam supstitucije je jedan jon Pr³⁺ za jedan Ca²⁺, s delimičnom supstitucijom anjona F^– sa O^2– i OH^– i stvaranjem vakansi usled postizanja neutralnosti sistema. Rezultati in vitro biokompatibilnosti i hemokompatibilnosti pokazali su da nanokristali PrFAPa nisu toksični za žive ćelije. Pored toga, internalizacija PrFAPa nanokristala od strane ćelija kancera kože (A431) i pluća (A549) je proučavana korišćenjem konfokalne mikroskopije i mikroskopije širokog polja zasnovane na fluorescenciji. Nanokristali pokazuju karakterističnu zelenu emisiju na 545 nm (³P₀→³H₅ tranzicija Pr³⁺ jona) i narandžastu emisiju na 600 nm (¹D₂→³H₄), koje su korišćene za razlikovanje od pozadinske autofluorescencije ćelije. Studije dobijenih slika konfokalnom mikroskopijom u plavom, zelenom i crvenom kanalu su otkrile da nanokristali mogu da prepoznaju ćelijsku površinu i da se lepe za nju, ali nisu potvrdile ulazak nanokristala u ćelije. Mikroskopija širokog polja je detektovala emisione prelaze u zelenoj i narandžastoj boji i potvrdila da luminescentni signal dolazi iz unutrašnjosti ćelija. Korišćenjem rezonantne ekscitacije od 488 nm i emisije od 600 nm PrFAPa nanokristala, konfokalnom mikroskopijom ekstrahovan je signal fluorescencije iz unutrašnjosti ćelija kancera. Ortogonalne projekcije u 3D konfokalnim ravnima pokazuju da su nanokristali u stanju da uđu u ćelije kancera i da se raspoređuju po citoplazmi. Sveukupno, ovako dobijeni nanokristali PrFAPa su biokompatibilni i od testiranih uzoraka, aktivirani nanokristali dopirani sa 0,5% Pr³⁺ pokazuju najviše potencijala za primenu u medicinskim fluorescentnim biosnimanjima kao kontrastni agenti.  
Luminescent nanocrystals (nanophosphorus) based on fluorapatite (FAP) doped with rare earth elements are ideal contrast agents for biomedical applications such as cancer cell detection, imaging, tracking and therapy. Cancer is one of the most common diseases of the modern times whose success of the cure depends on early diagnosis and non-invasive treatment. Luminescent nanoparticles can bring an innovative paradigm into the treatment of cancer by combining bioimaging, diagnostics and treatment. Rare earth doped fluorapatite nanocrystals as contrast agents for studies of fluorescence bioimaging, offer significant advantages in terms of high contrasts and long-term luminescence, and more importantly high biocompatibility, non-toxicity and bioactivity. The main objectives of this doctoral dissertation are the synthesis of novel luminescent multiphoton bionanomaterials based on fluorapatites doped with praseodymium ions (Pr³⁺), their characterization and evaluation of their application for cancer fluorescence bioimaging. Synthesis of nanopowders under moderate conditions by the co-precipitation method, followed by dried at 110 °C and calcination at 700 and 1000 °C, is expected to find the best conditions for obtaining new nanophosphors that would find different bio-medical applications in the field of fluorescence bioimaging. Three types of PrFAP nanocrystals were studied, with 0,1%, 0,5%, and 1% atomic percentages of Pr³⁺, together with an undoped FAP control sample. Energy levels of the Pr³⁺ ion activator contain metastable multiplet states that offer the possibility of efficient multi-color emission lines in FAP nanocrystals as well as in the infrared and ultraviolet regions of the spectrum. Single-phase hexagonal nanocrystals PrFAPs of irregular spherical shape were synthesized by the method of co-precipitation at room temperature (25 ^oC) and then drying at 110 ^oC. Thermal analysis of the synthesized samples, based on the detected temperature ranges of the decarbonation and dehydroxylation processes, determined calcination temperatures of 700 and 1000 ^oC. Thermal analysis with characterization showed that Pr³⁺ ions lead to stabilization of the FAP structure at higher temperatures, which was attributed to the entry of lanthanoid ions with specific magnetic properties into the system and the creation of stronger attractive forces with O^2- anions. Nanocrystals dried at 100 ^oC and calcined at 1000 ^oC, due to the presence of crystal lattice defects that quench the emission of Pr³⁺ ions, did not show luminescent characteristics of significance for applications in medical fluorescence imaging. Calcination of the samples at 700 ^oC produced a new type of activated praseodymium doped fluorapatite nanocrystals (PrFAPa) with excitation-emission profiles in the visible part of the spectrum. Physicochemical characterization confirmed spherical crystals of hexagonal structure up to a nanometer size of about 20 nm. Quantum-chemical calculations predicted that Pr³⁺ ions would be embedded in the crystal lattice of FAP nanocrystals at the Ca2 position (6h), which was followed by deformations of the F^- ion position. The assumed substitution mechanism is one Pr3+ ion for one Ca²⁺, with partial substitution of F^– anions with O^2– and OH^– and creation of vacancies due to achieving system neutrality. The results of in vitro biocompatibility and hemocompatibility showed that PrFAP nanocrystals were not toxic to living cells. In addition, the internalization of PrFAPa nanocrystals by skin (A431) and lung (A549) cancer cells was studied using fluorescence-based confocal microscopy and wide-field microscopy. The nanocrystals show characteristic green emission at 545 nm (³P₀→³H₅ transition of Pr³⁺ ion) and orange emission at 600 nm (¹D₂→³H₄), which we use to discriminate from cell autofluorescence. Studies of the images obtained by confocal microscopy in the blue, green, and red channels revealed that nanocrystals could recognize the cell surface and adhere to it, but they did not confirm the entry of nanocrystals into the cells. The wide-field microscopy detected emission transitions in green and orange color, and confirmed that the luminescent signal was coming from inside the cells. Using resonant excitation of PrFAP nanocrystals at 488 nm and emission of 600 nm, confocal microscopy extracted the fluorescence signal from inside the cancer cells. Orthogonal projections across 3D confocal stacks show that the nanocrystals are able to enter the cells positioning themselves within the cytoplasm. Overall, the obtained PrFAPa nanocrystals are biocompatible and of the tested types, the 0,5% Pr³⁺ doped nanocrystals show the highest promise as a tracking nanoparticle probe for bioimaging applications.

Doutoramento em Ciência e Engenharia dos Materiais
Bioactive glasses and glass–ceramics are a class of biomaterials which elicit special response on their surface when in contact with biological fluids, leading to strong bonding to living tissue. This particular trait along with good sintering ability and high mechanical strength make them ideal materials for scaffold fabrication. The work presented in this thesis is directed towards understanding the composition-structure-property relationships in potentially bioactive glasses designed in CaOMgOP2O5SiO2F system, in some cases with added Na2O. The main emphasis has been on unearthing the influence of glass composition on molecular structure, sintering ability and bioactivity of phosphosilicate glasses. The parent glass compositions have been designed in the primary crystallization field of the pseudo-ternary system of diopside (CaO•MgO•2SiO2) – fluorapatite (9CaO•3P2O5•CaF2) – wollastonite (CaO•SiO2), followed by studying the impact of compositional variations on the structure-property relationships and sintering ability of these glasses. All the glasses investigated in this work have been synthesized via melt-quenching route and have been characterized for their molecular structure, sintering ability, chemical degradation and bioactivity using wide array of experimental tools and techniques. It has been shown that in all investigated glass compositions the silicate network was mainly dominated by Q2 units while phosphate in all the glasses was found to be coordinated in orthophosphate environment. The glass compositions designed in alkali-free region of diopside – fluorapatite system demonstrated excellent sintering ability and good bioactivity in order to qualify them as potential materials for scaffold fabrication while alkali-rich bioactive glasses not only hinder the densification during sintering but also induce cytotoxicity in vitro, thus, are not ideal candidates for in vitro tissue engineering. One of our bioglass compositions with low sodium content has been tested successfully both in vivo and in preliminary clinical trials. But this work needs to be continued and deepened. The dispersing of fine glass particles in aqueous media or in other suitable solvents, and the study of the most important factors that affect the rheology of the suspensions are essential steps to enable the manufacture of porous structures with tailor-made hierarchical pores by advanced processing techniques such as Robocasting.
Os vidros e vitrocerâmicos bioactivos são uma classe de biomateriais que induzem uma resposta especial à sua superfície quando em contacto com fluidos biológicos que conduz a uma forte ligação ao tecido vivo. Esta característica particular conjugada com uma boa aptidão para a sinterização e elevada resistência mecânica torna estes materiais ideais para a fabricação de estruturas de suporte à regeneração óssea. O trabalho apresentado nesta tese pretende dar um contributo para uma melhor compreensão das relações entre composição-estrutura-propriedades em vidros potencialmente bioactivos com composições no sistema CaOMgOP2O5SiO2F, em alguns casos com a adição de Na2O. O estudo da influência exercida pela composição do vidro na estrutura molecular, capacidade de sinterização e nível de bioactividade dos vidros fosfosilicatados foi objecto de especial atenção. As composições vítreas foram concebidas no campo da cristalização primária do pseudo sistema ternário do diópsido (CaO•MgO•2SiO2) – fluorapatite (9CaO•3P2O5•CaF2) – wollastonite, e estudou-se o impacto das variações composicionais na estrutura, nas propriedades e na capacidade de sinterização destes vidros. Todos os vidros investigados neste trabalho foram preparados por fusão e fritagem e caracterizados quanto à sua estrutura molecular, capacidade de sinterização, degradação química e bioactividade, usando uma grande variedade de técnicas experimentais. Ficou demonstrado que em todas as composições de vidro investigadas a rede de silicato era dominada principalmente por unidades Q2 enquanto o fosfato se encontrava coordenado em ambiente de ortofosfato. As composições de biovidros isentas de alcalinos do sistema diópsido–fluorapatite demonstram possuir excelente capacidade de sinterização e elevados níveis de bioactividade, atributos que os qualificam como materiais promissores para a fabricação de estruturas de suporte à regeneração de tecidos ósseos, enquanto os vidros bioactivos contendo alcalinos foram mais difíceis de densificar durante a sinterização e induziram citotoxicidade in vitro, não sendo candidatos ideais para a engenharia de tecidos. Uma das nossas composições de biovidro com um baixo teor de sódio foi testada com sucesso tanto in vivo como em ensaios clínicos preliminares. Mas este trabalho precisa de ser continuado e aprofundado. A dispersão de fritas moídas em meio aquoso ou outros solventes adequados, e o estudo dos factores mais relevantes que condicionam a reologia das suspensões são etapas essenciais para viabilizar o processo de fabrico de suportes porosos com estruturas hierárquicas de poros feitas por medida através de técnicas de processamento avançadas tais como o Robocasting.

Objectives: The objectives of this study were to develop model dental composites incorporating fluorapatite (FA) as secondary filler and to characterise their physical and mechanical properties and fluoride ion release. Methods: Experimental composites were formulated containing BisGMA/TEGDMA/BisEMA and barium aluminium silicate glass as the primary filler. FA rod-like crystals and bundles were synthesised using a hydrothermal method and incorporated at 0 (0FA), 10 (10FA), 20 (20FA), 30 (30FA) and 40% (40FA) by mass into the previously identified optimum experimental composite, maintaining an overall filler content of 80%wt. 0FA and TetricEvoCeram (TC) were used for comparison as the experimental and the commercial controls, respectively. Two-body wear, Vickers Hardness (HV), Degree of Conversion (DC), Flexural strength (FS), Flexural modulus (FM), Fracture Toughness (K1C) and fluoride ion release were measured for each composition. Quantitative analysis of wear volume was carried out using a noncontact profilometer. Qualitative imaging of wear and fracture surfaces was undertaken using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). Statistical analysis was conducted using SPSS version 21. Results: All experimental composites showed similar wear resistance (p > 0.05) and enhanced microhardness compared to TC (p < 0.05). DC for all composites ranged between 56-60% at 20s polymerisation (p > 0.05). FA composites showed higher FM (p < 0.05) and similar FS (p > 0.05) to TC but lower FM and FS when compared to 0FA. 30FA and 40FA showed similar K1C to TC and 0FA (p > 0.05), whereas 10FA and 20FA showed lower K1C when compared to the other groups (p < 0.05). Under neutral pH, no fluoride release was detected from FA containing composites. However, under acidic conditions (pH 4), FA containing composites released fluoride when compared to the controls (p < 0.05), the amount of which was proportional to the amount of FA incorporated within the samples, i.e. 40FA> 30FA > 20FA > 10FA (p < 0.05). Conclusions: Experimental dental composites were successfully produced incorporating FA as secondary filler. The addition of FA did not affect the key physical and mechanical properties when compared to the commercial control. FA composites showed short and long term fluoride release under acidic conditions showing a promising step towards a potential “smart” fluoride releasing dental composite.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The use P solubilizing microorganisms are an alternative for a sustainable use of P against a backdrop of depletion of high-grade ores. Nevertheless, the chemical characteristics of rock phosphates (RP), particularly the level of toxic elements, can affect the efficiency of microbial solubilization. Fluoride (F-) released from fluorapatites has been shown to significantly inhibit P solubilization by Aspergillus niger, stimulating the search for alternatives to overcome F- toxicity. Thus, the aim of this study was to select A. niger mutants efficient at P solubilization in the presence of F-. Three selected mutants were also characterized as to their P solubilization mechanisms and the solubilization potential of different P sources. Twenty-nine mutants were obtained that presented changes in their phosphate solubilization activity in comparison to the wild type (WT). The mutant FS1-331 showed higher solubilization of Araxá RP, while FS1-555 promoted higher soluble P when grown in media with calcium phosphate supplemented with F- and in those with pure P sources. These mutants also showed higher tolerance to F- than the WT and displayed changes in the production of organic acids. The higher production of oxalic acid by FS1-331 and FS1-555 correlated with their improved capacity of Araxá RP solubilization. A mutant with decreased P solubilization capacity showed lower production of organic acids, corroborating the importance of these compounds for RP solubilization. FS1-331 was more efficient at solubilizing Araxá, Catalão, and Patos de Minas RPs than the WT and FS1-555. The variation in P solubilization capacity of the mutants obtained in this work may help clarify the RP solubilization mechanisms by A. niger. Moreover, the mutants with better performance selected in this work show potential for use in microbial RP solubilization systems with P sources rich in fluoride.
O uso dos micro-organismos solubilizadores de fosfato (P) é uma alternativa para o uso sustentável do P tendo em vista a diminuição das reservas fosfáticas de alta qualidade. As características químicas dos fosfatos de rocha (FR), em especial o nível de elementos tóxicos, podem influenciar a eficiência de solubilização microbiana. O fluoreto (F-) liberado de fluorapatitas inibi significativamente o processo de solubilização por Aspergillus niger FS1. Assim, o objetivo deste estudo foi selecionar mutantes de A. niger eficientes na solubilização de fosfato na presença de F-. Três mutantes selecionados foram também caracterizados quanto aos mecanismos de solubilização de fosfato e ao potencial de solubilização de diferentes fontes de P. Vinte e nove mutantes com alterações na solubilização de fosfato foram obtidos. O mutante FS1-331 demonstrou maior potencial de solubilização de fosfato de Araxá, enquanto que o mutante FS1-555 aumentou o P solubilizado em meio de cultura com fosfato de cálcio suplementado com F- e naqueles com fontes sintéticas de P. Os mutantes avaliados mostraram maior tolerância ao F- do que o tipo selavagem e tiveram a produção de ácidos orgânicos alterada. A maior produção de ácido oxálico pelos mutantes FS1-331 e FS1-555 relacionou-se com o melhor desempenho dessas estiprpes na solubilização de fosfato de Araxá. Um mutante com solubilização de P diminuída (FS1-375) apresentou menor produção de ácidos orgânicos quando comparado ao tipo selvagem, corroborando a importância desses compostos para o processo de solubilização de FRs. O mutante FS1-331 foi o mais eficiente na solubilização dos FRs de Araxá, Catalão e Patos de Minas. A variação na solubilização de P das estirpes fúngicas estudadas pode contribuir para a melhor compreensão do processo de solubilização de fosfatos por A. niger. Além disso, os mutantes mais eficientes obtidos apresentam alto potencial de aplicação em sistemas microbianos de solubilização de fosfatos com fontes de P ricas em fluoreto.

Currently, most titanium implant coatings are made using hydroxyapatite and a plasma-spraying technique. There are however limitations associated with the plasma-spraying process including; poor adherence, high porosity and cost. An alternative - the sol-gel technique offers many potential advantages but is currently lacking research data for this application. Hydroxyapatite (HA), fluorhydroxyapatite (FHA) and fluorapatite (FA) have been synthesised by a sol-gel method. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the FHA and FA sol-gels. Optimisation and characterisation of the sol-gels was carried out using, X-ray Diffraction (XRD), High Temperature X-Ray Diffraction (HTXRD), Fourier Transform Infrared Analysis (FTIR) and Differential Thermal Analysis (DTA). Rheology and hydrophilicity of the sol-gels showed that increasing fluoride ion substitution caused an increase in viscosity and contact angle. The dissolution (Ca2+ and PO4 3-rates) rates of the fluoride-substituted powders from the sol-gels were considerably lower than that of HA and all rates could be decreased by increasing the sintering temperature. This suggests the possibility of tailoring the solubility of any coatings made from the sol-gels through fluoride ion substitution and increased sintering temperature. A spin coating protocol has been established for coating the sol-gels onto titanium. Increasing the coating speed decreased the porosity and thickness of the coatings. Bond strengths to titanium were investigated. Fluoride substitution and sintering temperature were shown to be important factors. Cellular proliferation studies revealed that increasing the level of fluoride substitution in the apatite structure significantly increased the biocompatibility of the material. The sol-gel technique may be an alternative to plasma spraying for coating titanium implants. Furthermore it may also be suitable for producing HA, FHA and FA as bone grafting materials.

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As apatitas da região de Sumé, cidade localizada no Cariri paraibano, estão inseridas nos skarnitos da Província Borborema, mais precisamente no Complexo Sumé do terreno geotectônico Alto Moxotó, correlacionado à orogênese Brasiliana. As apatitas da região já foram alvo de pesquisas para exploração do minério fosfato e atualmente é estudada para fins gemológicos. Após tratamento térmico, a apatita apresenta cor azul neon, que tem grande aceitação no mercado e, consequentemente, valor agregado. O objetivo deste trabalho é caracterizar a apatita verde bruta e a apatita azul tratada, através de análises laboratoriais físicas e/ou químicas. As análises físicas apresentaram índice de refração e densidade compatível com a literatura que são 1,635 a 1,641 e 3,16 e 3,23g/cm3 respectivamente. Para o tratamento térmico da apatita verde natural, a faixa de temperatura de 700ºC é a que resulta na cor azul artificial mais intensa. Os resultados das análises químicas de fluorescência e microfluorescência mostraram que se trata de uma fluorapatita, apresentando concentrações de Neodímio e Praseodímio e alta anomalia de Tório. As análises de UV-Visível constataram as bandas dos terras raras Neodímio e Praseodímio. Os espectros de Infravermelho evidenciaram nas amostras tratadas a perda de agua e os carbonatos de substituição. A mudança de cor após tratamento térmico das apatitas verdes naturais para as apatitas azuis artificiais é creditada à substituição do íon (PO4)3, pelo íon Mn5+. As apatitas azuis tratadas apresentam coloração violeta quando estão submetidas à radiação UV, enquanto as apatitas verdes naturais não alteram sua cor.
Apatite crystals of the Sumé region, occur in the Cariri region, inserted in skarns of the Sumé Complex, of the Alto Moxotó Terrane, Borborema Province, which is correlated to the Brasiliano orogeny. Such minerals, has already been focus of exploitation research, being currently studied for gemological purposes. After the heat treatment, the apatite show blue neon color, which has great acceptance in the market and, consequently, economic value. The objective of this work is to characterize the crude green apatite and the treated blue apatite, through physical and / or chemical laboratory analyzes. The physical analyses presented refractive index and density compatible with the literature data that are 1,635 to 1,641 and 3,16, besides 3,23 g/cm³, respectively. For the heat treatment of natural green apatite, the temperature range of 700ºC resulted in the most intense artificial blue color. The results of the chemical analyses of fluorescence and microfluorescence showed that it corresponds to a fluorapatite, presenting considerable concentrations of Neodymium and Praseodymium and high thorium anomaly. UV-Visible analyses showed the rare earth bands neodymium and praseodymium. Infrared spectra revealed in loss of water and carbonate replacement in the treated samples. Color changing after heat treatment of the natural green apatites to the artificial blue ones is credited to the substitution of the ion (PO4)3 by the ion Mn5+. Treated blue apatites showed violet coloration when subjected to UV radiation, while natural green apatites do not alter their color.

Foram realizados seis experimentos in vitro com o objetivo de avaliar a eficiência de diversos microrganismos em solubilizar uma fluorapatita proveniente de Catalão, Goiás. Também foram avaliados os efeitos de doses de fluorapatita, do tempo de cultivo e da solubilização parcial da fluorapatita com ácido sulfúrico sobre a solubilização biológica do fosfato de rocha. O estudo foi realizado à temperatura ambiente utilizando-se uma solução de glicose com nutrientes minerais ou vinhaça esterilizada e não-esterilizada como meios de cultura. Seis culturas de fungos filamentosos foram selecionadas por terem apresentado elevado poder de solubilização em meio contendo glicose e nutrientes. Destas, duas culturas de Aspergillus niger foram mais eficientes em solubilizar a fluorapatita em todas as condições de cultivo estudadas. Nos cultivos com prazos superiores há 21 dias ocorreram os maiores teores de fósforo solúvel. Aspergillus niger apresentou maior solubilização em baixas doses, e Penicillium sp em doses elevadas. Correlações entre pH e fósforo solubilizado dependeram dos meios de cultivo empregados. Não houve mudança na composição mineralógica da fluorapatita devido ao ataque fúngico, embora Aspergillus niger tenha solubilizado uma quantidade de fósforo equivalente à encontrada em fluorapatita 25% solubilizada por H2SO4
Six experiments were carried out in vitro in order to evaliuate the effectiveness of several microrganisms in solubilizing a fluorapatite proceeding from Catalão, State of Goiás, Brazil. It was also evaluated the effects of rates of applied fluorapatita, time of cultivation, and previous partial solubilization on the biological solubilization of the rock phosphate. The study was conducted at ambient temperature using a glucose plus nutrients solution, as well as a sterilized and non-sterilized sugar cane vinasse as culture medium. Six filamentous fungi were selected as the most effective phosphate solubilizers when the culture medium was glucose plus nutrients solution. Among these, two cultures of Aspergillus niger were the most effective under any of the studied culture conditions. The highest levels of soluble phosphate were observed when the cultivation period was longer than 21 days. Aspergillus niger showed the highest solubilization rates at low levels of fluorapatite, whereas Penicillium sp was most effective at the higher levels. The composition of the culture media influenced the phosphorus solubilization by fungi, so that the correlation between pH and soluble phosphate varied depending on the medium used. No changes in the mineral composition of the fluorapatite due to fungal activity was observed, although Aspergillus niger had solubilization an amount of phosphate equivalent to that found in the fluorapatite 25% solubilized by sulfuric acid

Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2016.
Metallic materials play an essential role in assisting with the repair or replacement of bone tissue that has become diseased or damaged. Metals are more suitable for load bearing applications compared to ceramics or polymeric materials due to high mechanical strength and fracture toughness that are exhibited by metallic materials. However, the main limitation in the application of these metallic materials is the release of the toxic metallic ions. The release of these ions is caused by the interaction of metallic materials with human body fluids. These ions react with body tissue, which might lead to various adverse tissue reactions and/or hypersensitivity reactions. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys are one of the most useful alloys for biomedical applications such as dental and orthopedic implants because of acceptable mechanical properties and biocompatibility. However, the use of these alloys in biomedical applications has of late come under scrutiny recently due to unacceptable revision rates of applications such as hip resurfacing and total hip arthroplasty designs. Failure analysis has demonstrated that solid and soluble wear debris and corrosion products resulted. This release of ions from the joints has resulted in adverse local tissue reactions. Laser-aided deposition is a material additive based manufacturing process via metallurgically bonding the deposited material to the substrate. Due to its capability to bond various materials together, it became an attractive technology. The principal aims of this study were to 1a) fabricate nanocomposite materials by depositing fluorapatite nanopowder onto the Co-Cr-Mo dental alloy using pulsed laser deposition and 1b) evaluate which laser beam energy and layer thickness, based on the exposure time period, would be applicable, and 2) evaluate bioactivity properties on biological material.

Ce travail est consacre a la synthese et a l'etude des proprietes optiques des apatites au strontium et au calcium dopees a l'ion eu#3#+. Apres un rappel bibliographique sur les proprietes cristallographiques et optiques des materiaux apatitiques nous presentons dans un premier temps les techniques de synthese et la caracterisation de ces composes. Les echantillons au calcium sont obtenus par voie seche alors que ceux au strontium sont a la fois synthetises par voie seche et par coprecipitation. Differentes techniques d'analyse (analyse chimique, drx, ir et atg) sont utilisees pour caracteriser nos echantillons et pour comprendre leur comportement avec le traitement thermique. A la suite de cette etude, les echantillons obtenus par voie humide se sont averes riches en ions o#2# et oh#, ils serviront comme echantillons temoins pour l'etude optique. Une source de lumiere pulsee (laser a azote ou laser accordable a colorant) permet de porter les ions dans leurs etats excites et d'enregistrer les spectres d'emission et d'excitation ainsi que les declins de fluorescence. L'etude de la luminescence montre que l'ion eu#3#+ peut occuper jusqu'a sept sites contrairement aux previsions cristallographiques. A l'aide des echantillons temoins et de la propriete de sonde ponctuelle de l'ion eu#3#+, ces differents sites sont identifies et attribues a des environnements du type: (euo#6f)f, (euo#6f)oh, (euo#6f)o, (euo#6oh)oh, (euo#6oh)o et eu-f#n (symetrie c#s) et (euo#9) (symetrie c#3). Apres une diffusion rapide, des transferts d'energie entre ces differents sites sont observes. Le site c#3 n'est pas implique dans ces transferts d'energie. L'etude comparative entre les echantillons au strontium et au calcium montre que dans le dernier cas, on obtient une occupation simultanee des deux sites c#3 et c#s; le site c#3 n'est occupe qu'a forte concentration dans le cas des echantillons au strontium

Dental enamel is an excellent example of a highly mineralised tissue, composed of hierarchically organised apatite mineral. This unique organisation gives enamel superior mechanical properties. However, when mature, enamel becomes acellular and unable to repair itself during traumatic or carious damage. The lack of self-repair requires dental intervention, where the common treatment of decayed enamel is to remove the affected and healthy tissue, and replace with restorative materials. The restorative materials, currently used, can cause further complications in the form of secondary caries or failure due to thermal and mechanical property mismatch with enamel. Problems associated with current restorative materials have driven researchers to explore biomimetic enamel treatment routes. To mimic the natural enamel formation, we can explore how proteins can guide mineral growth, in order to form enamel-like ordered mineral structures. In this thesis, the use of a synthetic, recombinant protein called an elastin-like protein (ELP) containing the analogue of the N-terminal of statherin (STNA15) was under investigation. Statherin is a protein present in saliva that is said to aid in the remineralisation of enamel. ELP with STNA15 (STNA15-ELP) has already shown promise in biomimetic mineralisation. This thesis investigated how conformation and structure of STNA15-ELP can be affected and manipulated by different chemical environments, surface constraint and crosslinking. The STNA15-ELP characteristics were related to formation of fluorapatite. STNA15-ELP conformation changed due to presence if salts in solution and whether or not it was constrained. We linked the conformational changes within STNA15-ELP, in solution versus on the surface, to two different routes of mineral formation. FAp formed in an uncontrolled manner with free STNA15-ELP. Ordered FAp formed via a precursor when STNA15-ELP was constrained on a surface. This work leads to an understanding of biomimetic mineralisation using STNA15-ELP. This information can aid in the design of novel biomimetic, enamel-like therapeutics.

Zinkgruvan is a stratiform Zn-Pb-Ag and Cu sulphide deposit hosted by Paleoproterozoic strata in southern Bergslagen, Sweden. The deposit underwent medium-high grade regional metamorphism during the Svecokarelian orogeny, including partial melting of the host succession. Subordinate zones of semi-massive to massive magnetite and Fe-rich skarns occur in marble stratigraphically below the stratiform Zn-Pb-Ag ore but have so far not been described in detail in the scientific literature. This thesis presents results from detailed geological drill core logging, light optical microscopy (LOM) and scanning electron microscopy (SEM), which have been integrated with results from electron microprobe analysis (FE-EMPA) and whole-rock lithogeochemical analysis to provide a comprehensive description of the magnetite mineralization. Samples from the formerly mined magnetite deposits Västerby, Garpa and Åmme - distal to Zinkgruvan - have also been studied to allow for a comparison. The combined dataset has been used to 1) discuss the genesis of the magnetite mineralizations, including their relationship to base metal sulphide mineralization, and 2) evaluate potential vectors to Zn-Pb-Ag and Cu mineralization based on variations in the magnetite deposits. The semi-massive to massive magnetite, adjacent and associated Fe-rich skarn at Zinkgruvan are located in the stratigraphic upper part of the marble host. Three different varieties of magnetite mineralization can be defined: 1) semi-massive to massive magnetite mineralization in marble, 2) magnetite-bearing veins and 3) retrograde magnetite after olivine. Detailed optical microscopy has revealed a positive spatial correlation between aluminium spinel, apatite, magnetite and graphite. Semi-massive to massive magnetite mineralization at Zinkgruvan is enriched in P2O5, ΣREELa-Lu and Mn relative to a carbonate precursor. A positive correlation exists between P2O5 and ∑REELa-Lu, suggesting apatite and monazite are the primary REE-bearing minerals. The fact that the samples with highest P2O5 and ∑REELa-Lu are all Fe-rich rocks suggest the enrichment of the latter is related to the event which formed the Fe mineralization. Magnetite mineralization from the historic iron mines NW of Zinkgruvan share several key attributes with magnetite mineralization at Zinkgruvan. These include: 1) magnetite is the only iron oxide, 2) lithological and mineralogical similarities, including spatial association with marble, 3) equally high whole-rock Fe content, 4) equally high Mn (1-4 wt.% MnO), 5) equally high Eu anomalies (Eu/Eu* = 1.1- 2.8, avg. 1.75), and 6) local presence of sphalerite mineralization. Bending of the tectonic foliation from c. E-W to NW in the western part of Zinkgruvan suggest these magnetite mineralizations may be located along the same trend as those at Zinkgruvan. The normal calc-silicate mineralogy in Zinkgruvan marble (e.g. diopside, forsterite, phlogopite) can be explained by prograde regional metamorphic reactions between silicates and dolomite or calcite in impure carbonate rocks with a variable content of detrital siliciclastic and volcaniclastic material. However, the stratabound magnetite mineralization and associated Fe-rich skarns cannot be fully accounted for by this model. It is plausible that the Fe-rich skarns can be explained by similar reactions but involving more Fe-rich carbonates (ferrodolomite, ankerite, siderite). In the absence of quartz, siderite is known to thermally decompose into magnetite and graphite at temperatures above 465° C, whereby siderite-rich rocks may have been precursor to the semi-massive to massive magnetite mineralization. A recent genetic model suggests that the ore-forming fluids which formed Zinkgruvan where similar to those which formed McArthur-type SEDEX deposits. The presented results are consistent with this model, since e.g. siderite is a common alteration mineral in alteration envelopes to such deposits. Hence, magnetite mineralization, Zn-Pb-Ag and Cu-ore may all be related to the same pre-metamorphic hydrothermal system. The current genetic model places the magnetite mineralization at Zinkgruvan proximal to a fossil hydrothermal vent zone (the Burkland discontinuity). It is plausible that the magnetite mineralization mined at surface lay along the northern continuation of the Burkland discontinuity. Based on the assumption that the Burkland Cu-mineralization is most proximal and the old iron mines at Åmme are most distal along this structure, variations in whole-rock lithogeochemistry, mineral chemistry and mineralogy have been used to define nine vectors to economic Zn-Pb-Ag and Cu ore as is mined at Zinkgruvan.

A l'heure actuelle les recherches de nouvelles apatites thermiquement plus stables se développent. Ainsi desdépôts à base de fluoroapatite (Ca10(PO4)6F2) ou de fluorhydroxyapatite fournissent des dépôts plus stables etplus adhérents que l'hydroxyaptite tout en étant biocompatibles. La fluoroapatite (Fap) présente non seulement despropriétés physicochimiques semblables à celles de l'os naturel mais également une bonne résistance à lacorrosion dans le milieu physiologique. La Fap et l'hydroxyapatite (Hap) sont utilisées soit sous forme de dépôt surles parties métalliques de prothèses soit toutefois comme matériaux de comblement osseux. L'utilisation de cesbiocéramiques pose quelques problèmes en raison de leur faible tenue mécanique. L'alumine a été proposée ainsipour ses bonnes propriétés mécaniques et pour sa forte affinité pour le fluor avec lequel elle donne des composéstrès stables. Des dépôts composites Al2O3-Fap et Hap-Fap ont été réalisés par projection thermique. Nous avonsfait varier dans ces composites le pourcentage de fluor. Les résultats obtenus montrent que l'ajout de Fap améliorela résistance mécanique et les propriétés tribologiques de l'Hap et contribue à l'adhésion et à la prolifération descellules osseuses pour les dépôts d'alumine
A considerable amount of research already focused on ceramic biomaterials given their chemical stabilityand high mechanical strength. On the one hand, Fluorapatite (Fa) has recently attracted some attention as analternative to pure hydroxyapatite (Hap) as coating on metallic implants, given its chemical composition which issimilar to the bone mineral and therefore its excellent biocompatibility. On the other hand, alumina is known for itsexcellent bioinertia and is also one of the most widely investigated bioceramics. In this frame, the aim of our workwas to investigate Al2O3-Fap and Hap-Fap composite coatings deposited on stainless steel substrates usingSpraying processes (APS and SHVOF). The mechanical, micro-structural, tribological and biological (in Vitro and inVivo tests) properties of these composite coatings are determined and analysed in order to determine their possibleuse as surigical implant materials

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Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências- Geoquímica Ambiental. Niterói, RJ
A redistribuição dos radioisótopos presentes em alguns rejeitos industriais, ao provocar aumento na radioatividade natural, representa grave problema para a saúde e para o ambiente. Na produção de ácido fosfórico, o radioisótopo 226Ra é depositado preferencialmente no fosfogesso, resíduo gerado no processo por via úmida. Atualmente, com a produção anual de cerca de 12 milhões de toneladas, há um estoque estimado de mais de 80 milhões de toneladas de fosfogesso no Brasil. O presente trabalho buscou determinar as concentrações do 226Ra presente em uma amostra de fosfogesso, determinar um método de extração eficiente, desenvolver uma metodologia para pré-concentração do 226Ra por sorção em colunas trocadoras de íons e comparar a eficiência da hidroxiapatita e da flúorapatita no seu acondicionamento, de forma a possibilitar a remediação do passivo ambiental da indústria de fertilizantes por remoção do 226Ra, principal contribuinte de radiação de meia vida longa no fosfogesso. A média das concentrações de atividade radioativa encontrada para o 226Ra, na amostra de fosfogesso estudada, foi de 168±11 Bq.kg-1, com eficiência de extração de (82±31)%. O carvão ativado apresentou desempenho (32±3)% superior ao da resina chelex-100 na pré-concentração do 226Ra. Para seu acondicionamento, tanto a hidróxiapatita quanto a flúorapatita, apresentaram resultados satisfatórios, com eficiências globais similares, de (49±24)% e de (52±28)%, respectivamente, a nível laboratorial. Se os valores encontrados fossem extrapolados para a pilha de origem, com atividade estimada em (8,4±0,6)x1010 Bq o acondicionamento, tanto na flúorapatita quanto na hidróxiapatita, poderia promover a remoção de cerca de (4,5±2,6)x1010 Bq.
The redistribution of radioisotopes found in some industrial by-products, by the increasing of the natural radioactivity, represents a serious problem for the health and for the atmosphere. The production of phosphoric acid from natural phosphate rock by the wet process gives rise an industrial by-product called phosphogypsum where the radioisotope 226Ra is preferentially deposited. There are an annual production about 12 million tons and a stock of more than 80 million tons of phosphogypsum in Brazil. The present work aims to determinate the 226Ra radioactive activity present in a phosphogypsum sample, an efficient extraction method, development of a methodology for pré-concentration of the 226Ra by sorption in exchange ions columns and compare the global efficiency of the hydroxyapatite and the fluorapatite in its packaging, in order to turn possible the removal of the 226Ra from the phosphogypsum, by-product of the fertilizers industry. As results, the average of the concentrations of radioactive activity found for the 226Ra in the phosphogypsum samples was of 168±11 Bq.kg-1, with extraction efficiency of (82±31)%. Activated charcoal presented sorption (32±3)% higher than the chelex-100 resin in the pré-concentration of the 226Ra. For its packaging, hydroxyapatite and fluorapatite, presented satisfactory results, with similar global efficiencies around (49±24)% and (52±28)%, respectively, at laboratory level. If the found values were extrapolated to the original stack, with estimated activity of (8,4±0,6)x1010 Bq the packaging, in any of both materials, could remove about (4,5±2,6)x1010 Bq.

Les différentes lithologies sédimentaires du Groupe Belqa présentent un enrichissement en P et en toute une série d'éléments sensibles aux conditions redox. Il est montré que l'enrichissement en U, Cu, Co, Mo, V résulte d'un dépôt syn-sédimentaire sous conditions suboxiques. Par contre, les éléments Cr, Ni, Cd, Zn sont beaucoup plus enrichis et requierent un flux exogénique de métal probablement relié à l'altération de roches ultrabasiques obductées à la même période au nord de cette région, lors de la collision de la plaque arabo-africaine avec la plaque eurasienne. Les phosphates représentent le principal hôte de l'uranium et des terres rares. L'analyse des apatites par ablation laser ICP-MS a permis de montrer leur évolution, depuis le stade sédimentaire-diagénétique, puis pyrométamorphique, jusqu'à l'altération supergène. La libération de l'uranium de la structure de l'apatite lors du pyrométamorphisme et de l'altération supergène permet sa mise à disposition pour la formation de minéralisations. Le pyrométamorphisme, dû à une combustion des niveaux riches en matière organique, est responsable de la déstabilisation des apatites, et de la formation de roches de compositions semblables à des ciments clinker/Portland. L'uranium a également été libéré de la structure de l'apatite par altération supergène. L'altération météorique et les fluides évaporitiques ont permis le lessivage et le transport des éléments (U, V) des roches carbonatées métamorphiques, et des carbonates puis a conduit au dépôt des vanadates d'uranyles dans les carbonates pulvérulents ayant subi une dissolution importante
The different lithologies of the Belqa Group present an enrichment in P and various redox sensitive elements. The U, Cu, Co, Mo, V enrichment results from synsedimentary deposition in suboxic conditions. However, the higher Cr, Ni, Cd, Zn enrichment requires an exogenic metal flux probably related to the terrestrial leaching of ultrabasic rocks obducted during the collision between African-Arabian and Eurasian plates to the north of the study region, at the same time. Phosphates are the main host lithology for uranium and rare earth elements. The analysis of the apatites by laser ablation ICP-MS shows their evolution along the sedimentary-diagenetic and pyrometamorphic stages, up to the supergene weathering. The uranium liberation from the apatite structure during the pyrometamorphism and surficial weathering led to its availability as supergene ore mineralization. Pyrometamorphism resulted from the combustion of organic-rich layers and caused the destabilization of the apatites, and the formation of rocks which have compositions similar to clinker/Portland cements. Uranium has been also released from the structure of the apatite by supergene alteration. Meteoric weathering and the evaporitic groundwater resulted in the leaching and the transport of the elements (U, V) from the metamorphic carbonated hills, and from the surrounding permeable limestone which has undergone dissolution in the near surface zone

Yes
Peri-implantitis remains the major impediment to the long-term use of dental implants. With increasing concern over the growth in antibiotic resistance, there is considerable interest in the preparation of antimicrobial dental implant coatings that also induce osseointegration. One such potential coating material is fluorapatite (FA). The aim of this study was to relate the antibacterial effectiveness of FA coatings against pathogens implicated in peri-implantitis to the physicochemical properties of the coating. Ordered and disordered FA coatings were produced on the under and upper surfaces of stainless steel (SS) discs, respectively, using a hydrothermal method. Surface charge, surface roughness, wettability, and fluoride release were measured for each coating. Surface chemistry was assessed using X-ray photoelectron spectroscopy and FA crystallinity using X-ray diffraction. Antibacterial activity against periodontopathogens was assessed in vitro using viable counts, confocal microscopy, and scanning electron microscopy (SEM). SEM showed that the hydrothermal method produced FA coatings that were predominately aligned perpendicular to the SS substrate or disordered FA coatings consisting of randomly aligned rodlike crystals. Both FA coatings significantly reduced the growth of all examined bacterial strains in comparison to the control. The FA coatings, especially the disordered ones, presented significantly lower charge, greater roughness, and higher area when compared to the control, enhancing bacteria−material interactions and therefore bacterial deactivation by fluoride ions. The ordered FA layer reduced not only bacterial viability but adhesion too. The ordered FA crystals produced as a potential novel implant coating showed significant antibacterial activity against bacteria implicated in peri-implantitis, which could be explained by a detailed understanding of their physicochemical properties.
This work was partially funded through WELMEC, a Centre of Excellence in Medical Engineering funded by the Wellcome Trust and EPSRC, under grant number WT 088908/Z/09/Z.

碩士
國立成功大學
口腔醫學研究所
95
Bioceramics, especially in calcium phosphate, have been used as a surface-coating material on metallic implants. Due to their bioactive characteristics, bioceramics enable rapid fixation and stronger bonding between the host bone and the implant. Hydroxyapatite (HA) and Fluorapatite (FA) have been widely used in dentistry and orthopedics. HA is similar to inorganic component in human hard tissue. It has the innate ability to promote bone formation and growth, However HA easily dissolve in human body. On the other way, the pervious studies indicated that FA is a biocompatible material, and it is more stable than HA and ensures the functionally strong bone formation. The aim of this study is to evaluate the characteristics of FA coating using plasma spray in different parameters. By comparing with HA, the FA coatings were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), F Ion Selective Electrode and Differential Thermal Analyzer (DTA). To study the behaviors of the samples in human body, the specimens would be soaked in simulated body fluid (SBF) at 37℃. Then the soaked specimens were measured by SEM and XRD. In the assay of cellular biocompatibility, human osteosarcoma cells were cultured on those specimens and the cell morphology were evaluated. Moreover, both of HA and FA (coatings) had the same phase composition. To increase the current and the hydrogen flows may enhance the thickness and roughness of the HA & FA coatings, but decrease their crystallization.

碩士
南台科技大學
機械工程系
98
Biomedical implants are generally coated with a thin layer of hydroxyapatite (HA) using a plasma spraying or pulsed laser deposition method. However, the bonding strength between the coating layer and the substrate is relatively low. Moreover, the high temperature of the deposition process causes a structural instability of the HA, and therefore degrades its bioactivity and reduces the service life of the coating layer following implantation. Accordingly, the present study replaces HA with fluorapatite (FA) as the coating material, and examines the effects of two different binders, namely polyvinyl alcohol (PVA) and water glass (WG), on the properties of FA coatings deposited on Ti-6Al-4V substrates using an Nd-YAG laser cladding process. Scanning electron microscopy (SEM) observations reveal that the FA coating has a coral- and dendrite-like structure when mixed with the PVA binder, but a pure dendrite structure when mixed with the WG binder. In addition, the Ca/P value of the WG-based FA coating is significantly higher than that of the PVA-based coating. Fluorapatite, Al2O3, CaTiO3 and Ca3(PO4)2 phases are observed in both coating layers. However, the XRD analysis results indicate that the microstructure of the WG sample is dominated by Ca3(PO4)2 phase while that of the PVA sample is dominated by FA.The simulation body fluid （SBF） soaking test, results reveal, after soak 21 days, The PVA binder has a large amount of apatite is deposited in coating layers, the best with 740W among them.Ca/P value 1.59 to 1.8 .The XRD analysis results ,Ca2P2O7, Ca3 (PO4)2, HA ; The WG binder in soaking test of 21 days, the surface grows and only becomes scattered apatite, while making final Ca/P value 5.05 to 7.55, and XRD analysis, Ca2P2O7, Ca3(PO4)2 , but these phase of the looks not to be high, reveal also a small amount of apatite in that surface.

Fluorine is abundant in the oceans, and carbonate fluorapatite precipitation in marine sediment is a significant removal mechanism. A paucity of data has led to several misconceptions of fluorine geochemistry and carbonate fluorapatite (CFA) diagenesis, a fluorine and carbonate substituted apatite (Ca10 (PO4)5.74(CO3)0.26F 2.26). This thesis will revise and expand our understanding of fluorine and CFA in deep sediment by proving fluorine's availability, documenting CFA precipitation, and demonstrating alkalinity controls on fluorine and CFA. Because CFA is the main mineral phase of economic phosphorite deposits, its development has warranted much study. However, previous research focused on PO43- and F concentrations in pore waters of shallow sediment (<10 meters) and is incomplete. Here, previous work is improved by directly measuring fluorine concentrations in sediments and pore waters from deep cores (>100 meters) near the upwelling zone of the Peru margin. These results are then related to CFA diagenesis.

碩士
南臺科技大學
機械工程系
105
In this study, the fluorapatite (FA), which has higher thermal stability than hydroxyapatite (HA) was mixed as a coating material, and the Ti-6Al-4V substrate was pre-coated with a pure Ti by vacuum plasma spraying (VPS )on the Ti-6Al-4V substrate as bond coat first, and then investgate the mechanical properties and the biological properties of the graded coatings. The results show that In the case of monolayer composite coating, the thickness and porosity of all specimens are decreased with increasing power, and the decreasing proportion of FA / Ti , the coating thickness and porosity increased with the increase of FA / Ti ratio. XRD analysis showed that the thermal decomposition of FA in the coating resulted in CaF2 as the spray power and FA content increased. It was found that on the surface of all samples except that the 2FA /8Ti samples with the lowest spray capacity of 2FA / 8Ti samples were found for 14 days after soaking, three different proportions of the composite coating had been exposed to apatite on the surface of all samples. Increased power and FA / Ti ratio In order to promote the early nucleation of apatite, the apatite size increases with the immersion time gradient. In the coating, the microstructure of the coating shows that the pores of the coating increase with the increase of FA / Ti ratio. The hardness of the sample is the lowest in the pure Ti bond layer, and the FA content decreases with the increase of the FA content. Young's modulus analysis showed that Young's modulus of the sample began to decrease from the matrix to the 8FA / 2Ti coating. The results show that the average bond strength of the coating is 42 ± 3.7MPa, the main failure mode is the cohesion failure of the coating, and the bond between the coating and the substrate is not bonded. In vitro cell test results show that the composite gradient coating has a faster cell adhesion. The results show that the single layer composite coating with FA / Ti composite powder can make the coating have biological and mechanical properties, and the control parameters can keep Young's modulus difference between the coating and the substrate.

No
The latest advances in mesocrystal formation and non-classical crystallization of pre-synthesised nanoparticles have been reviewed with the focus on providing a fuller description of a number of complex systems and their properties and applications through examination of the crystallisation mechanisms at work. Two main crystallization principles have been identified; classical crystallization and particle based aggregation modes of non-classical pathways. To understand the non-classical pathways classical crystallization and its basics are introduced before non-classical pathways, such as oriented attachment and mesocrystal formation, are examined. In particular, the various destabilization mechanisms as applied to the pre-synthesized building blocks in order to form mesocrystalline materials as well as the interparticular influences providing the driving forces are analyzed and compared to the mechanisms at work within classical crystallization. Furthermore, the new properties of the mesocrystalline materials that derive from the collective properties of the nanoparticular building units, and their applications potential are presented. It is shown that this new class of materials has the potential to impact in a number of important areas such as sensor applications, energy conversion, photonic crystals as well as for energy storage, optoelectronics and heterogeneous catalysis or photocatalysis.