Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 115-117). Also available in print.

Thesis (M.S.)--University of Delaware, 2005. / Principal faculty advisor: Katharina Billups, Dept. of Marine and Earth Studies . Includes bibliographical references.

Multi-isotopic approaches have been used effectively to help provide estimated geographic origins for unidentified skeletal remains in cold case homicides and archaeological contexts, when DNA testing was not practical. Stable oxygen and strontium isotopes were used in the present study in order to determine their effectiveness of proveniencing human remains from Colombia and New England. Enamel hydroxyapatite was extracted from individual teeth (n=151) from individuals with known birthplaces for different regions of Colombia as well as the region of New England in the United States. All oxygen data is presented as a ratio of δ18O /δ16O (‰PDB). The results show significant geographical differences (p ≤ 0.001), between the Colombian and New England populations. The mean δ18O value for Colombia is -11.06 ± 1.28. The mean 87Sr/86Sr value for Colombia is 0.707391 ± 0.0016. The mean δ18O value of the samples from the United States is -7.42 ± 1.39. The mean 87Sr/86Sr value for the samples from the United States is 0.7099747 ± 0.0011. The oxygen and strontium ratios of the sample set have no significant differences within each geographic region. Additionally, a small subset of the immigrant community in Boston, MA is represented within the sample. There is a significant difference (p ≤ 0.002) in the population’s mean δ18O values. The establishment of this oxygen and strontium isoscape has the potential to provenience unidentified human remains recovered as a result of Colombia’s long-term internal conflict.

abstract: This research focuses upon the intersection of social complexity and leadership among commoners in complex societies as expressed through mortuary ritual. I study how ideology, materialized through treatment of the deceased body, was a potential source of power among commoners in ancient Maya society and how this materialization changed through time. Mortuary data are drawn from mid-level settlements of the Belize River Valley, located in western Belize within the eastern Maya lowlands. The primary research question addresses whether mid-level leaders in the Belize River Valley targeted certain human bodies for ancestral veneration through tomb re-entry and ritual interaction with skeletal remains. The ritual-political strategy of mid-level leaders is measured using archaeothanatology, an analysis of grave taphonomy based on forensic data, to reconstruct cultural beliefs about death based on treatment of deceased bodies, radiogenic strontium isotope analysis to reconstruct residential history, and analysis of dental metrics to assess biological kinship. While preservation of osseous material was poor, results indicate that the frequency of disarticulated and secondary burials was higher in eastern structures than in other locales, although eastern structures were not the only loci of these types of deposits. Overall, it does not seem like secondary burials were regularly and purposefully created for use as ritual objects or display. Radiogenic strontium isotope data enrich this analysis by showing that eastern structures were not a burial locale exclusive to individuals who spent their childhood in the Belize Valley. Data from upper-level eastern structures also suggests that within that part of society local birth did not guarantee interment in a local manner; perhaps the social network created during one's life shaped treatment in death more than residential origin. Biological distance analyses were inconclusive due to missing data. Comparison of mortuary practices to nearby regions shows distinct mortuary patterning across space and time. This is consistent with reconstructions of ancient Maya sociopolitical organization as regionally diverse and moderately integrated. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2015

Orientador: Rosemary Adriana Chiérici Marcantonio / Banca: Ricardo Andres Landázuri Del Barrio / Banca: Roberto Henrique Barbeiro / Resumo: Objetivo: Avaliar o efeito do revestimento com estrôncio em duas concentrações sobre o potencial de reparo ósseo do osso bovino desproteinizado (DBB) em defeitos críticos de calvárias (DCC) de ratos. Material e métodos: Foram utilizadas 42 ratas que foram randomicamente divididas em 3 grupos(n=14) de acordo com o tipo de biomaterial utilizado para preencher os DCC: Grupo DBB-Osso bovino desproteinizado; Grupo DBB/Sr 1(140µM por g de DBB); Grupo DBB/Sr 2(700µM por g de DBB). Foram confeccionados dois defeitos ósseos circulares (Ø5mm) nos ossos parietais dos animais, sendo que um defeito foi preenchido com biomaterial e o outro foi mantido apenas com coágulo (controle negativo). Os animais foram submetidos a eutanásia após 15 e 60 dias do procedimento cirúrgico (n=7 animais/período). Os animais foram avaliados com relação ao volume do preenchimento do DCC com tecido reparado e o tamanho remanescente do DCC por meio de análise microtomográfica. A composição do tecido reparado e as características da cicatrização foram determinadas por meio de análise histométrica/descrição histológica, enquanto que a expressão das proteínas TGFβ1 e Osteocalcina (OCN) foi realizada por análise imuno-histoquímica. Resultados: O DBB/Sr2 induziu o maior fechamento e preenchimento do DCC que os outros grupos. O DBB/Sr1 e DBB/Sr2 apresentaram maior componente de tecido ósseo dentro do tecido reparado do que os DCC preenchidos com DBB no período de 60 dias. Adicionalmente, também foi verificado que o D... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Objective: Evaluate the healing potential of deproteinized bovine bone (DBB) coated with strontium at two concentrations in critical defects of calvarial rats (DCC). Methods: We used 42 rats that were divided randomly into 3 groups (n = 14) according to the type of biomaterial used to fill the DCC: Group DBB - Deproteinized bovine Bone; Group DBB / Sr 1 (140μM per g DBB); Group DBB / Sr 2 (700μM per g DBB). Two circular bone defects (Ø5mm) were prepared in the parietal bones of the animals and one defect was filled with biomaterial and the other was maintained empty (negative control). The animals were sacrificed after 15 and 60 days after surgery (n = 7 animals / period). The animals were evaluated according the filing volume of the DCC with the repair tissue and the residual size of the DCC by microtomográfica analysis. The composition of the repaired tissue and healing characteristics were determined by Histometrical / histological description analysis, while the expression of TGFβ1 and osteocalcin (OCN) were determined by immunohistochemical analysis. Results: The DBB / Sr2 induced the highest closing and filling of the DCC than the other groups. The DBB / Sr1 and DBB / Sr2 showed greater bone tissue section within the repaired tissue than DCC filled with DBB within 60 days. Additionally, it was also found that the DBB / Sr1 and DBB / Sr2 induced a higher expression of OCN. Conclusion: The addition of Sr (700 mM) improved the quality of bone healing induced by DBB. / Mestre

Dentoflex / LaboratÃrio Servier do Brasil / A integraÃÃo dos implantes dentÃrios no osso tem sido amplamente relatada nas Ãltimas dÃcadas desde os trabalhos originais de Branemark e co-autores. O uso de implantes dentÃrios de titÃnio no tratamento de pacientes edÃntulos ou parcialmente edÃntulos tem se tornado uma alternativa para restauraÃÃo funcional e estÃtica, entretanto esses resultados dependem da quantidade e da qualidade do osso maxilar ou mandibular. Osteoporose à uma doenÃa que influencia a qualidade do tecido Ãsseo, tornando-o susceptÃvel à fratura. RelaÃÃo importante tem sido descrita entre massa Ãssea oral e esquelÃtica em mulheres pÃs-menopausa. A osteoporose tem sido considerada um fator de risco para a osseointegraÃÃo de implantes dentÃrios, embora o assunto ainda seja bastante controverso. O ranelato de estrÃncio à uma nova terapia para o tratamento e prevenÃÃo da osteoporose, que dissocia a formaÃÃo Ãssea da reabsorÃÃo Ãssea permitindo continuada produÃÃo de osso enquanto diminui a sua reabsorÃÃo. O objetivo do presente trabalho foi determinar, em coelhos, o efeito da terapia sistÃmica com ranelato de estrÃncio sobre o tempo de osseointegraÃÃo de implantes dentÃrios baseado nos valores do torque para a sua remoÃÃo. Sessenta e quatro implantes dentÃrios de titÃnio idÃnticos foram, entÃo, instalados, seguindo protocolo cirÃrgico padronizado, na distal do fÃmur e proximal da tÃbia, bilateralmente, de 16 coelhos brancos da raÃa Nova ZelÃndia (64 implantes no total). Uma semana antes da instalaÃÃo dos implantes, foi iniciada a administraÃÃo de doses de ranelato de estrÃncio (625mg/kg/dia) a 8 coelhos prorrogada atà o sacrifÃcio desses animais. Os outros 8 coelhos pertenciam ao grupo controle, sem medicaÃÃo. Um coelho de cada grupo foi sacrificado com 15, 30, 45, 60, 75, 90, 105 e 120 dias e os valores do torque para a remoÃÃo dos implantes foi determinado por um torquÃmetro digital. A anÃlise dos dados desses torques mostrou que nÃo houve nenhuma diferenÃa estatÃstica entre o grupo experimental e o grupo controle. Com base nos achados do presente trabalho, concluiu-se que o tempo de 15 atà 120 dias de uso de ranelato de estrÃncio nÃo interferiu no tempo de osseointegraÃÃo. / The integration of titanium dental implants in bone has been reported extensively over the last few decades beginning with the original work of Branemark and co-workers. The use of titanium endosseous dental implants in the treatment of edentulous or partially edentulous patients has become an alternative to restore function and esthetics, however, this results depend on the quantity and quality of the maxillary or mandibular bone. Osteoporosis is a disease that influences the quality of bone tissue such that it may become susceptible to fracture. Significant relationship have been reported between oral bone and skeletal bone mass in postmenopausal women. Osteoporosis could, therefore be considered a risk factor for osseointegration of dental implants, but this is still controversial. Strontium ranelate is a new therapy for the treatment and prevention of osteoporosis that may dissociate bone formation and bone resorption by allowing continued production of bone while decreasing bone resorption. The purpose of this study was to determine the effect of systemic strontium ranelate therapy on early dental implant osseointegration based on torque-removal values in rabbits. Sixty-four identical titanium dental implants were placed using a standardized surgical protocol in the bilateral distal femur and proximal tibia of 16 New Zealand white rabbits (64 implants total). One week before implant placement, 8 rabbits were given doses of strontium ranelate (625mg/kg/day) until euthanized. The other 8 rabbits were untreated controls. One rabbit of each group were sacrificed in time of 15, 30, 45, 60, 75, 90, 105, 120 days, and torque-removal values were determined using a digital torque wrench for all implants. Analyses of torque data showed no statistical differences between the strontium ranelate and control groups. Based on the findings of this study, we can conclude that the time of 15 to 120 days of strontium ranelate administration does not interfere with the timing of early dental implant osseointegration in an animal model.

O objetivo deste trabalho foi o de otimizar a adição de estrôncio em liga A356 visando obter as melhores propriedades mecânicas de ductilidade. Foram estudados diferentes níveis de adição de estrôncio em ligas A356 com dois níveis de fósforo residual. Além disto, foi estudado o efeito de adições crescentes de magnésio na morfologia do silício em liga Al-7%Si modificada. Para a realização deste estudo, foram produzidos corpos de prova de tração segundo ASTM B108 com velocidade de resfriamento de 8°C/s. Os corpos de prova foram endurecidos por precipitação via tratamento térmico e tracionados. Além de uma avaliação quantitativa das propriedades mecânicas, amostras de todas as condições passaram por uma avaliação metalográfica qualitativa. Foi feito também ataque profundo para observação das morfologias das partículas de silício em microscópio eletrônico. O efeito da adição crescente de estrôncio na liga A356 em um intervalo de 0 a 256 ppm de estrôncio foi o de aumento do alongamento até teores de 50 a 60 ppm, seguido de uma diminuição do mesmo até 256 ppm. O teste de adição crescente de estrôncio foi repetido para uma liga A356 com teor residual de fósforo de aproximadamente 10 ppm. A curva de alongamento segue o mesmo formato da curva levantada para amostras que não continham fósforo, embora tenha sido encontrada uma sensível queda nos valores de alongamento na presença de fósforo. A presença de magnésio em ligas Al-Si modificadas por estrôncio foi responsável por uma mudança na morfologia de crescimento das partículas de silício nas regiões de contornos de células eutéticas, além do aparecimento de partículas intermetálicas nesta mesma região. Deste trabalho, concluiu-se que as melhores propriedades mecânicas de ductilidade foram obtidas para a adição de estrôncio de 50 a 60 ppm. / This work has, as its main objective, the optimization of the strontium addition in A356 alloy, in order to obtain the best ductility results. The addition of several different strontium amounts in alloys containing two phosphorous amounts was studied. Besides, the effect of increasing magnesium content on the morphology of the silicon particles of Al-7%Si modified alloy was also studied. Test bars were produced from ASTM B108 cooled at a rate of 8°C/s. The samples were heat treated and then tested. The mechanical properties were evaluated and the microstructures were analyzed. The silicon morphology was observed in deep etched samples at SEM. Strontium additions of 0 to 256 ppm increased the elongation up to 50-60 ppm. Above 75 ppm, the addition of strontium caused the elongation to decrease up to 256 ppm. The same test was reproduced for an alloy containing approximately 10 ppm P and, although the best results were achieved at strontium additions of 50-60 ppm, the elongation results were clearly lower. The presence of magnesium in Al-7%Si modified alloys was responsible for a change in the growth morphology of the silicon particles, especially near grain boundaries, and also for the formation of intermetallic particles in those areas. From this work, it was possible to conclude that the best ductility properties are achieved for strontium additions of 50-60 ppm.

Doctor of Philosophy / Department of Chemistry / Kenneth J. Klabunde / A new approach to synthesize nanosized strontium titanate (SrTiO3) and barium titanate (BaTiO3) has been developed. Nanocrystals of mixed metal oxide were synthesized by a modified aerogel procedure from alkoxides. The textural and surface characteristic properties were studied by nitrogen BET analysis, transmission electron microscopy, and powder XRD. The crystallite sizes of aerogel prepared powders can vary from 6 to 25 nm by the use of different solvents. A mixture of ethanol and toluene was found to be the best binary solvent for supercritical drying, which produced a SrTiO3 sample with a surface area of 159 m2/g and an average crystallite size of 8 nm, and a BaTiO3 sample with a surface area of 175 m2/g and an average crystallite size of 6 nm. These titanates have been studied for photocatalytic oxidation of volatile organic compounds and acetaldehyde (CH3CHO) in particular. The big band gaps of the bulk (3.2 eV for SrTiO3 and 3.1 eV for BaTiO3) limit their application to a UV light region only. The modification of titanates by doping with transition metal ions (partial substitution of Ti ions with metal ions) creates a valence band or electron donor level inside of the band gap, narrows it, and increases the visible light absorption. The enhanced adsorption of visible light was achieved by the synthesis of nanosized SrTiO3 and BaTiO3 by incorporating Cr ions during the modified aerogel procedure. Gaseous acetaldehyde photooxidation has been studied on pure SrTiO3 and BaTiO3, and on chromium doped Cr-SrTiO3 and Cr-BaTiO3 under UV and visible light irradiation, and compared with the photoactivity of P25 TiO2. SrTiO3 doped with antimony/chromium shows absorption in visible light and show photocatalytic activity for CH3CHO oxidation. The reason for the codoping of SrTiO3 with Sb/Cr was to maintain the charge balance and to suppress oxygen defects in the lattice. This photocatalyst shows high photoactivity under visible light irradiation even after several continuous runs. The photoactivity under visible and UV light irradiation was almost identical for the Sb/Cr-SrTiO3 photocatalyst. Dielectric properties of aerogel prepared barium titanate samples have being studied and the bulk resistance values of AP-BaTiO3 were significantly lower than that of commercial BaTiO3, by several orders of magnitude.

No description available.

Low temperature sintering has become a very important research area in ceramics processing and sintering as a promising process to obtain grain size below 100nm. For electronic ceramics, low temperature sintering is particularly difficult, because not only the required microstructure but also the desired electronic properties should be obtained. In this dissertation, the effect of liquid sintering aids and particle size (micrometer and nanometer) on sintering temperature and Positive Temperature Coefficient Resistivity (PTCR) property are investigated for Ba1-xSrxTiO3 (BST) doped with 0.2-0.3mol% Sb3+ (x = 0.1,0.2,0.3,0.4 and 0.5). Different sintering aids with low melting point are used as sintering aids to decrease the sintering temperature for micrometer size BST particles. Micrometer size and nanometer size Ba1-xSrxTiO3 (BST) particles are used to demonstrate the particle size effect on the sintering temperature for semiconducting BST. To reduce the sintering temperature, three processes are developed, i.e. 1 using sol-gel nanometer size Sb3+ doped powders with a sintering aid; 2 using micrometer size powders plus a sintering aid; and 3 using nanometer size Sb3+ doped powders with sintering aids. Grain size effect on PTCR characteristics is investigated through comparison between micrometer size powder sintered pellets and nanometer size powder sintered pellets. The former has lower resistivity at temperatures below the Curie temperature (Tc) and high resistivity at temperatures above the Curie temperature (Tc) along with higher ñmax/ñmin ratio (ñmax is the highest resistivity at temperatures above Tc, ñmin is the lowest resistivity at temperatures below Tc), whereas the latter has both higher ñmax and ñmin. Also, ñmax/ñmin is smaller than that of pellets with larger grain size. The reason is that the solid with small grain size has more grain boundaries than the solid with large grain size. The contribution z at room temperature and high temperature and a lower ñmax/ñmin ratio value.