O objetivo deste estudo foi comparar a eficácia clínica, radiográfica e microscópica do formocresol (FC) de Buckley diluído a 1/5, hidróxido de cálcio PA (HC) e Agregado Trióxido Mineral (MTA) como agentes capeadores pulpares em dentes decíduos humanos acometidos por cárie extensa. Quarenta e cinco molares decíduos inferiores de 23 crianças com idades entre 5 e 9 anos foram tratados pela técnica convencional de pulpotomia. Os dentes foram aleatoriamente divididos entre os grupos experimentais (HC e MTA) e o grupo controle (FC). Após a remoção da polpa coronária e hemostasia, o tecido pulpar remanescente foi coberto com pasta de MTA ou pó de HC nos grupos experimentais. No grupo controle, uma bolinha de algodão umedecida na solução de FC diluído foi colocada por 5 minutos sobre o remanescente pulpar e então a câmara pulpar preenchida com óxido de zinco e eugenol. Todos os dentes foram restaurados com uma base de óxido de zinco e eugenol reforçado (IRM) e cimento de ionômero de vidro modificado por resina. As avaliações clínicas e radiográficas foram realizadas nos períodos de 3, 6, 12, 18, 24 e 30 meses do pós-operatório. Durante as avaliações, os dentes que se apresentavam no período normal de esfoliação, bem como, dentes considerados fracasso ao tratamento foram extraídos e processados para análise microscópica. Os cortes foram feitos seriadamente, no sentido vestíbulo-lingual e corados pela hematoxilina e eosina. A análise microscópica foi realizada de forma descritiva dos fenômenos mais marcantes ocorridos no tecido pulpar remanescente. Pelos resultados clínicos e radiográficos obtidos foi possível observar uma taxa de sucesso para os grupos FC, HC e MTA de 100%, 35,7% e 100%, respectivamente. Diferença estatisticamente significativa foi observada quanto à presença de reabsorção interna, lesão inter- radicular, mobilidade e fístula para o grupo HC (p < 0,05). A análise microscópica para o grupo FC revelou presença de intenso infiltrado inflamatório e deposição de tecido mineralizado, irregular por todo canal radicular. Para o grupo MTA, notou-se deposição de material mineralizado de aspecto dentinóide, obliterando todo o canal radicular, além de áreas centrais preenchidas por tecido conjuntivo frouxo com inúmeros vasos sanguíneos. O grupo HC apresentou, na maioria dos cortes, extensa área de necrose tanto na câmara pulpar quanto no canal radicular. Em outros poucos cortes, presença de barreira de dentina reacional, obliterando a abertura coronária do canal radicular, com discreto infiltrado inflamatório crônico. O MTA parece ser um possível substituto do FC, no entanto, o hidróxido de cálcio mostrou ser uma técnica muito sensível e, portanto, não indicada para pulpotomias de dentes decíduos. / The aim of this study was to compare the clinical, radiographic and microscopic effectiveness of formocresol (FC), calcium hydroxide (CH) and trioxide mineral aggregate (MTA) as pulp dressing agents in carious primary teeth. Forty-five primary mandibular molars of 23 children between 5 and 9 years old were treated by conventional pulpotomy technique. The teeth were randomly assigned to the experimental (CH and MTA) or control (FC) groups. After coronal pulp removal and hemostasis, remaining pulp tissue was covered with a MTA paste or CH powder in the experimental groups. In the control group, diluted FC was placed over the pulp tissue with a cotton pellet for 5 minutes and removed; the pulp tissue was covered then with zinc oxide-eugenol (ZOE) paste. All the teeth were restored with reinforced zinc oxide-eugenol base and resin modified glass ionomer cement. Clinical and radiographic evaluations were recorded at 3, 6, 12, 18, 24 and 30-month follow-up. During the assessments, the teeth in the regular exfoliation period, as well as those considered as treatment failures were extracted and further processed for microscopic analysis. Serial sections were performed in the bucco-lingual direction and stained with hematoxylin and eosin. Microscopic analysis was performed as a description of the most remarkable phenomena in the remaining pulp tissue. Through clinical and radiographic results, success rates of 100%, 35.7% and 100% for FC, CH and MTA were found, respectively. Statistically significant differences were observed regarding to the presence of internal resorption, inter-radicular bone destruction, mobility and fistula for CH group (p < 0.05). Microscopic analysis revealed the presence of intense inflammatory infiltrate and mineralized tissue deposition, which was irregular throughout the root canal, in the FC group. As far as MTA group, dentin-like mineralized material deposition obliterating the root canal, and central areas filled by loose conjunctive tissue with several blood vessels were noticed. CH group presented, in most of the sections, extensive necrotic areas both in pulp chamber and root canal. Other sections revealed the presence of extensive reactive dentin barrier, which obliterated the coronal opening of the root canal, and a discrete chronic inflammatory infiltrate. MTA may serve as an effective substitute of FC in primary molar pulpotomies. However, CH seems to be a technique sensitive-material and therefore not indicated for pulpotomies of primary teeth.

Orientador: Wilma De Grava Kempinas / Texto em português e inglês / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T16:12:27Z (GMT). No. of bitstreams: 1 Silva_RaquelFrenedoso_M.pdf: 3492189 bytes, checksum: 66cf94f64336b7c79f7b1cf8981d8d60 (MD5) Previous issue date: 2014 / Resumo: O trióxido de arsênio (As2O3) tem se mostrado altamente eficaz e muito utilizado no tratamento para diminuir ou eliminar a leucemia promielocítica aguda. Estudos mostram relação entre exposição a este composto e inibição da espermatogênese ou desenvolvimento do espermatozoide, uma vez que exerce efeito inibitório nos testículos. Diante da crescente utilização do As2O3 no tratamento da leucemia e da escassez de resultados sobre os seus efeitos adversos na reprodução masculina, justifica-se a realização do presente estudo, pelo qual se avaliou os efeitos imediatos e tardios do tratamento com As2O3 sobre fisiologia reprodutiva de camundongos Swiss adultos e se a co-administração de N-acetilcisteína (NAC), previne esses efeitos. Em um primeiro experimento, camundongos Swiss adultos foram tratados com veículo, 0,3 ou 3,0 mg/Kg/dia de As2O3, via subcutânea, em 25 aplicações. No final do tratamento, metade dos animais foram eutanasiados para avaliação dos efeitos pós-tratamento e a outra metade foi mantida sem a droga por período de 50 dias, até que se procedeu a eutanasia para avaliação da possível reversibilidade dos efeitos. Foram investigados: peso dos órgãos vitais, reprodutores e glândulas sexuais acessórias, quantidade e qualidade espermáticas, dosagem de testosterona e dosagem de arsênio no sangue. Os animais tratados com 3,0 mg/kg de As2O3 e eutanasiados logo após o fim do tratamento mostraram diminuição no peso da vesícula seminal, número de espermatozoides móveis e produção espermática diária. Após período de suspensão do tratamento, os animais tratados com a mesma dose continuaram apresentando redução nos mesmos parâmetros. Em um segundo experimento, foi avaliada a contratilidade do ducto epididimário isolado tanto frente ao tratamento in vivo dos animais (tratados com o veículo ou com a dose de 3,0 mg/kg/dia de As2O3) quanto ao tratamento in vitro do tecido. Essa análise revelou que a contração máxima do ducto epididimário estava significativamente aumentada nos animais tratados com As2O3 in vivo. E em uma terceira etapa os animais foram divididos em Controle, As2O3 (3,0 mg/Kg/dia), NAC na água de beber (40mM) e As2O3 + NAC, tratados por 5 semanas. Após o final do tratamento, os animais foram avaliados quanto aos parâmetros que se apresentaram prejudicados com o tratamento anterior, descrito na etapa um. Quando a NAC foi oferecida aos animais, houve uma melhora significativa nos parâmetros espermáticos antes prejudicados pela administração da droga, i.e., o peso de vesícula seminal, número de espermatozoides móveis e produção espermática diária do grupo As2O3 + NAC foram similares ao grupo controle. Podemos concluir que o As2O3 exerce efeitos tóxicos sobre o sistema genital de camundongos machos, e que esses efeitos podem ser persistentes mesmo após o término do tratamento. Os resultados mostraram, também, que a administração de um antioxidante pode prevenir os efeitos deletérios dessa droga sobre os parâmetros avaliados / Abstract: Arsenic trioxide (As2O3), a trivalent arsenic form has proven highly effective and widely used in the treatment to reduce or eliminate acute promyelocytic leukemia. Studies show a relationship between exposure to this compound and inhibition of spermatogenesis and sperm development since it exerts an inhibitory effect on the testis. Given the growing use of As2O3 on treatment of leukemia and the lack of results about the side effects on male reproduction, it is justified to carry out this study, which evaluated the immediate and late effects of treatment with As2O3 on the structure and reproductive physiology of adult Swiss mice and whether the co-administration of N-acetylcysteine (NAC) prevents these effects. In a first experiment, adult Swiss mice were treated with vehicle, 0.3 or 3.0 mg/Kg/day of As2O3, subcutaneously in 25 applications. At the end of treatment, half of the animals were euthanized for evaluation of the post- treatment effects and the other half was maintained without the drug for 50 days until the euthanasia to evaluate the potential reversibility of the effects. It was evaluated: the vital, reproductive and accessories organ weights, analyzes of sperm quantity and quality, testosterone and arsenic measurements in blood. Animals treated with 3.0 mg/Kg of As2O3 and euthanized immediately after the end of treatment showed a decrease of seminal vesicle weight, in number of motile spermatozoa and daily sperm production. After suspension of treatment, animals treated with this same dose continued to show reduction in these same parameters. In a second experiment, the contractility of the epididymal duct was evaluated both in vivo treatment of animals (treated with vehicle or a 3.0 mg/Kg/day of As2O3) and in vitro treatment of the tissues. This analysis revealed that the maximum contraction of the epididymal duct was significantly increased in in vivo treated animals. And in a third step animals were divided into Control, As2O3 (3.0 mg/Kg/day) NAC in tap water (40 mM) and As2O3 + NAC, treated for 5 weeks. After the end of treatment, animals were assessed for previously impaired parameters described in step one. When NAC was given to the animals, there was a significant improvement in sperm parameters before harmed by the drug administration, i.e. seminal vesicle weight, number of motile sperm and daily sperm production in As2O3 + NAC group were similar to the control group. We conclude that As2O3 exerts toxic effects on the male mice genital system, and that these effects may be persistent even after the end of treatment. Also, the results showed that administration of an antioxidant can prevent the deleterious effects of this drug on the parameters evaluated / Mestrado / Biologia Celular / Mestra em Biologia Celular e Estrutural

This study was directed at the pyrotechnic time delay compositions that are used in detonator assemblies. The objectives were to: --Investigate effective alternatives for the barium and lead-based oxidants currently used, maintaining the use of silicon as fuel --Develop easy to use, realistic measurement techniques for burn rates and shock tube ignitability --Determine the variables that affect burn rate, and --Evaluate alternative processing routes to facilitate intimate mixing of the component powders. Lead chromate and copper antimonite were found to be suitable oxidants for silicon in time delay compositions. They were ignitable by shock tubing, a relatively weak ignition source. The measured burn speeds for these systems showed a bimodal dependence on stoichiometry. Measured burn rates varied between 6-28 mm/s. Lead chromate is potentially a suitable alternative to the oxidant currently used in the medium burn rate commercial composition. It burns faster than copper antimonite. The latter is potentially a suitable replacement oxidant for the slow and medium compositions. Antimony trioxide-based compositions exhibited unreliable performance with respect to ignition with shock tubing. The addition of aluminium powder or fumed silica was found to reduce the burn rate. Increasing the silicon particle size (<3,5<font face="symbol">m</font>m) also decreased the burn speed for copper antimonite and lead chromate compositions. Addition of fumed silica improved the flow properties of the lead chromate, copper antimonite and antimony trioxide powders allowing for easier mixing. The silicon powder was found to react violently with water in alkaline solutions. This makes particle dispersion in a wet-mixing process problematic. / Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

This work deals with the optimization of the preparation process of WO3 photoanodes nad their characterization. For compositions were prepared, which were applied to a substrate via spin-coating process and subsequently annealed at 450 °C. The length of milling of precursor particles contained in the coating formulations determined properties of deposited layers. were examined for. The additivity of the individual compositions was also observed. The structure of the layers was observed by optical microscopy and scanning electron microscopy (SEM), their composition by the X-ray diffraction (XRD) and their thickness and surface roughness was defined by contact profilometry. Photoelectrochemical properties of the prepared layers were also investigated by linear voltametry and chronoamperometry.

The dielectric tensor of Ga2O3 in the monoclinic (β) phasewas determined by generalized spectroscopic ellipsometry in a wide spectral range from 0.5 eV to 8.5 eV as well as by density functional theory calculations combined with many-body perturbation theory including quasiparticle and excitonic effects. The dielectric tensors obtained by both methods are in excellent agreement with each other and the observed transitions in the dielectric function are assigned to the corresponding valence bands. It is shown that the off-diagonal element of the dielectric tensor reaches values up to |εxz| ≈ 0.30 and cannot be neglected. Even in the transparent spectral range where it is quite small (|εxz| < 0.02) it causes a rotation of the dielectric axes around the symmetry axis of up to 20◦.

In the last 150 years, the City of Yellowknife has transitioned from an area of traditional subsistence living to the largest city in the Northwest Territories (Canada) due to the economic influence of resource extraction. As resource extraction in the area boomed, large quantities of pollutants from mine tailings and emissions from roaster stacks adjacent to gold mines were deposited on the landscape, leaving a known legacy of elevated surface water, sediment, and soil metal(loid) concentrations. Most of the research to date has focused on arsenic in the region, and my thesis expands the body of knowledge to include other metal(loids) of interest, including antimony, lead, and mercury. My thesis's main objective was to determine the spatial and temporal extent of legacy mining emissions near Yellowknife and assess the associated biological risk from these historic emissions. I analyzed select intervals from 20 lake sediment cores for time constrained metal(loid) contaminants of concern. I used a combination of paleotoxicity and paleoecotoxicology methods to establish a spatial and temporal footprint of biological risk associated with historic gold mining activities in the Yellowknife region. I determined that lakes close to the mine exhibited a low-level hazard to aquatic communities before mining, while the onset of mining increased the hazard posed by sediments deposited to acute levels. I also discovered that lakes within 5 km of Giant Mine exceeded guideline values for sedimentary mercury during active mining. Further, I developed methods in paleoecotoxicology that indicated a concordance between time deposited, estimated risk, and observed mortality of native Daphnia sp exposed to time-constrained sediment archives. My thesis demonstrates that paleotoxicity and paleoecotoxicology are effective methods to separate historic and modern influences of industrial development on aquatic biota. Additionally, my research has application extensions for policymakers, remediation scientists, Indigenous Peoples, and those proposing new industrial ventures.

This diploma thesis deals with layers of tungsten oxide, which are prepared from a nanoparticle suspension and a binder. The coating composition consisted in the first case of ground tungsten oxide nanoparticles alone, then of acetylated peroxotungstic acid alone and finally of a mixture of ground tungsten oxide mixed with acetylated peroxotungstic acid. The compositions thus formed were applied to conductive FTO glass and thus act as photoanodes. A stainless steel needle is used as a counter electrode for volt-ampere measurements. The work focuses on the study of physicochemical properties of prepared photoanodes and their optimalization in order to obtain the highest possible values of generated photocurrents. The electrical properties of all cells were determined using voltammetric characteristics.

No description available.

No description available.

This thesis extends our fundamental knowledge in the area of high oxidation state chemistry of xenon trioxide, XeO3. Oxygen coordination to the Xe(VI) atom of XeO3 was observed in its adducts with triphenylphosphine oxide, [(C6H5)3PO]2XeO3, dimethylsulfoxide, [(CH3)2SO]3(XeO3)2, pyridine-N-oxide, (C5H5NO)3(XeO3)2, and acetone, [(CH3)2CO]3XeO3. The crystalline adducts were characterized by low-temperature single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO3, which detonates when mechanically or thermally shocked, the solid [(C6H5)3PO]2XeO3, [(CH3)2SO]3(XeO3)2, and (C5H5NO)3(XeO3)2 adducts are insensitive to mechanical shock, but undergo deflagration when exposed to a flame. Both [(C6H5)3PO]2XeO3 and (C5H5NO)3(XeO3)2 are air-stable at room temperature. The xenon coordination sphere in [(C6H5)3PO]2XeO3 is a distorted square pyramid and provides the first example of a five-coordinate Xe center in a XeO3 adduct. The xenon coordination sphere of the remaining adducts are distorted octahedral comprised of three equivalent Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO3. Hirshfeld surfaces of XeO3 and (C6H5)3PO in [(C6H5)3PO]2XeO3 show the adduct is well-isolated in its crystal structure and provide a visual representation of the secondary Xe---O bonding in this adduct. Crown ethers have been known for over 50 years, but no example of a complex between a noble-gas compound and a crown ether or another polydentate ligand had been reported. Xenon trioxide is shown to react with 15-crown-5 to form the kinetically stable (CH2CH2O)5XeO3 adduct which, in marked contrast with solid XeO3, does not detonate when mechanically shocked. The crystal structure shows that the five oxygen atoms of the crown ether are coordinated to the xenon atom of XeO3. The gas-phase Wiberg bond valences and indices and empirical bond valences indicate the Xe---Ocrown bonds are predominantly electrostatic, σ-hole, bonds. Mappings of the electrostatic potential (EP) onto the Hirshfeld surfaces of XeO3 and 15-crown-5 in (CH2CH2O)5XeO3 and a detailed examination of the molecular electrostatic potential surface (MEPS) of XeO3 and (CH2CH2O)5 reveal regions of negative EP on the oxygen atoms of (CH2CH2O)5 and regions of high positive EP on the xenon atom that are also consistent with σ-hole bonding. Reactions of crown ethers with HF acidified aqueous solutions of XeO3 at room-temperature yielded adducts of 12-crown-4, (CH2CH2O)4XeO3, and 18-crown-6, [(CH2CH2O)6XeO3∙2H2O]2∙HF, whereas slow cooling of a solution of XeO3 with 18-crown-6 in acetone yielded (CH2CH2O)6XeO3∙2H2O. The adducts (CH2CH2O)4XeO3 and (CH2CH2O)6XeO3∙2H2O are shock-insensitive whereas the former adduct is air-stable at room temperature. The low-temperature, single-crystal X-ray structures show the Xe atom of XeO3 coordinated to the oxygen atoms of the crown ether ring. Uncharacteristic xenon coordination numbers exceeding six (including the three primary bonds of XeO3) were observed for all crown ether adducts. Raman spectroscopy frequency shifts are consistent with complex formation and provided evidence for the 2,2,1-cryptand adduct of XeO3. Gas-phase Wiberg bond valences and indices and empirical solid-state bond valences confirmed the electrostatic nature of the Xe---O bonding interactions. Comparisons between the XeO3 and SbF3 18-crown-6, 15-crown-5, and 12-crown-4 complexes are made. Incorporation of xenon trioxide, XeO3, into inorganic polyatomic salts under ambient conditions has been observed in several mixed xenate salts; K[XeO3XO3] (X = Cl, Br), K2[XeO3SeO4]∙HF, K[(XeO3)nZO3] (Z = I, N), and M2[(XeO3)nCO3]∙xH2O (M = Na, K, Rb, Ba). Raman spectroscopy was used to identify the aforementioned compounds and K[XeO3ClO3], K[XeO3BrO3], K2[XeO3SeO4]∙HF, and Rb2[(XeO3)2CO3]∙2H2O were also characterized by low-temperature, single-crystal X-ray diffraction. The xenon atom of XeO3 is seven coordinate in K[XeO3ClO3] and six coordinate in all other compounds with Xe---O distances that are significantly less than the sum of the Xe and O van der Waals radii. These salts provide examples of XeO3 coordinated to inorganic compounds and may provide insights into the inclusion of xenon oxides in minerals. / Thesis / Master of Science (MSc)