92 resultados para Defect chemistry
Prosthetic rehabilitation of a bone defect with a teeth-implant supported, removable partial denture
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The use of teeth-implant, mucosa-supported removable dentures for rehabilitation of partially edentulous patients involves highly complex biomechanical aspects. This type of prosthesis associates 3 kinds of support that react differently to the functional and parafunctional forces developed in the oral cavity. Although the construction of removable partial dentures may seem paradoxical when osseointegrated implants are placed, in some cases, this option is an excellent alternative to solve difficulties related to the anatomic, biologic, psychomotor, and financial conditions of the patient. This article reports on a case in which a teeth-implant, mucosa-supported removable partial denture was the option of choice for a patient with financial and anatomic limitations, having a large structural loss of the residual alveolar ridge caused by trauma by a gunshot injury at the mandible. The 5-year follow-up did not reveal any type of biomechanical or functional problem. Copyright © 2006 by Lippincott Williams and Wilkins.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Eriocaulaceae is a pantropical family that comprises about 1100 species distributed in 11 genera. The infrafamilial relationships are still unsatisfactorily resolved, because of the tiny flowers and generalized morphology, which makes the taxonomy very difficult. Flavonoid and naphthopyranone profiles have proved to be important in order to contribute to the alignment of genera into the family. We here present a survey of the chemical data of Eriocaulaceae with a discussion about their contribution to the taxonomy of Eriocaulaceae. © 2008 Verlag der Zeitschrift für Naturforschung.
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Visible photoluminescence was generated in standard soda-lime-silica glass powder, mechanically milled in a high-energy attrition mill. The broad emission band maximum shows a linear dependence on the exciting wavelength, suggesting the possibility to tune the PL emission. The photoluminescence was attributed to defect generation related to unsatisfied chemical bonds due to the high surface area. Raman scattering and ultraviolet-visible optical reflectance measurements corroborate this assertion. Transmission electron microscopy measurements indicate that the powder is composed by nanocrystallites with about 10-20 nanometers immersed in an amorphous media.
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The purpose of our work is to extend the formulation of classical affine Toda Models in the presence of jump defects to pure fermionic Thirring model. As a first attempt we construct the Lagrangian of the Grassmanian Thirring model with jump defect (of Backlund type) and present its conserved modified momentum and energy expressions giving a first indication of its integra-bility. Copyright © owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
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The present study was designed to analyze the effects of the association between cinnamon extract and aerobic exercise on the glycemic control and serum lipid profile of diabetic rats. Fifty Wistar male rats divided into five groups: control (C), sedentary nondiabetic rats; diabetic (D), sedentary diabetic rats; diabetic cinnamon (DC), sedentary diabetic rats that received cinnamon extract; diabetic exercise (DE), sedentary diabetic rats subjected to physical training; and diabetic cinnamon exercise (DCE), diabetic rats that received cinnamon extract and were subjected to physical training. For the induction of diabetes, the rats received alloxan. The cinnamon was administered to once a day for four weeks. The groups performed swimming exercises for one hour each day with lead overloads (3% - 5% of b.w) for five days a week for four weeks. Body weight loss was lower in the DE group compared to the other diabetic groups. The basal serum glucose of all the diabetic groups was higher compared to the control group. Group D had higher serum cholesterol concentrations compared to the DE and DCE groups. The resting blood lactate in group D was higher than the resting blood lactate in the DC and DE groups. Aerobic exercise partially counteracted the diabetic effects on body weight, serum cholesterol and blood lactate concentrations. No additional beneficial effects of cinnamon extract and aerobic exercise were observed on the parameters studied.
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We report on the influence of a circular defect on the vortex configuration in a mesoscopic superconducting sample. Effects associated with the pinning force of the circular defect on the configuration and on the vortex entry fields are studied for a very thin disk. We calculate the magnetization loop, vorticity, free energy and superconducting electrons for the disk in presence of an external magnetic field applied perpendicular to the disk plane. The magnetization curves are hysteretic, with paramagnetic response in part of the downward branch, also, in this part we found a vortex-anti-vortex state. © 2013 World Scientific Publishing Company.
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The occurrence of a high incidence of sperm tail defects in a male domestic cat resembling the known 'Dag-like' defect is reported. Sperm analyses were performed in ejaculated samples collected by an artificial vagina and in testicular and epididymal sperm cells after castration. The following alterations were observed using transmission electron microscope: heavily coiled sperm tails containing several axonemal units enclosed in the same common cell membrane; aberrations in the axonemal main structure; and swollen and unevenly distributed mitochondria in the midpiece. Abnormal modifications in the mitochondrial sheath were also found in sperm cells retrieved from testes and epididymides. Considering these findings, we can conclude that this is the Dag-like defect, described previously in other domestic species and a testicular origin may be involved. © ISFM and AAFP 2012.
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Hydrogenated bulk Zn1-xCoxO samples were synthesized via standard solid-state reaction route with Co molar concentrations up to 15 at.%. Magnetic characterization demonstrates a room temperature ferromagnetic behavior associated to a paramagnetic Curie-Weiss component. Detailed microstructural analysis was carried out to exclude the presence of extrinsic sources of ferromagnetism. The magnetization increases linearly as a function of Co concentration. Hall measurements reveal an insulating character for the whole set of samples. In this context, the defect mediated magnetic coupling between the Co atoms under the scope of the bound magnetic polarons model is used to interpret the observed room temperature ferromagnetism. © 2012 Elsevier B.V. All rights reserved.
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A YSZ@Al2O3 nanocomposite was obtained by Al 2O3 coating on the surface of yttrium stabilized zirconia via a polymeric precursor method. The resulting core-shell structures were characterized by X-ray diffraction, scanning electron microscopy, transmission electronic microscopy and PL spectra. The TEM micrographs clearly show a homogeneous Al2O3 shell around the ZrO2 core. The observed PL is related to surface-interface defects. Such novel technologies can, in principle, explore materials which are not available in the bulk single crystal form but their figure-of-merit is dramatically dependent on the surface-interface defect states. © 2013 This journal isThe Royal Society of Chemistry.
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Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. Among the various materials for implants, calcium phosphates and hydroxyapatite are widely used clinically. In this work, titanium nanotubes were fabricated on the surface of Ti-7.5Mo alloy by anodization. The samples were anodized for 20 V in an electrolyte containing glycerol in combination with ammonium fluoride (NH4F, 0.25%), and the anodization time was 24 h. After being anodized, specimens were heat treated at 450 °C and 600°C for 1 h to crystallize the amorphous TiO2 nanotubes and then treated with NaOH solution to make them bioactive, to induce growth of calcium phosphate in a simulated body fluid. Surface morphology and coating chemistry were obtained respectively using, field-emission scanning electron microscopy (FEG-SEM), AFM and X-ray diffraction (XRD). It was shown that the presence of titanium nanotubes induces the growth of a sodium titanate nanolayer. During the subsequent invitro immersion in a simulated body fluid, the sodium titanate nanolayer induced the nucleation and growth of nano-dimensioned calcium phosphate. It was possible to observe the formation of TiO2 nanotubes on the surface of Ti-7.5Mo. Calcium phosphate coating was greater in the samples with larger nanotube diameter. These findings represent a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications. © (2013) Trans Tech Publications, Switzerland.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Avaliou-se a composição centesimal e análise físico-química do Lentinus strigosus, um cogumelo comestível de ocorrência na Amazônia brasileira, produzidos em substratos alternativos à base de resíduos madeireiros e agroindustriais. Com este objetivo, determinou-se C, N, pH, sólidos solúveis, atividade de água, proteína, lipídios, fibra total, cinzas, carboidratos e energia. Os substratos foram formulados a partir de serragem de Simarouba amara Aubl. (marupá), Ochroma piramidale Cav. ex. Lam. (pau-de-balsa) e Anacardium giganteum (cajuí); e do estipe de Bactris gasipaes Kunth (pupunheira) e de Saccharum officinarum (cana-de-açúcar). Os resultados demonstraram que: a composição nutricional do L. strigosus variou com o substrato de cultivo; os valores de proteína encontrados nos cogumelos cultivados nos diferentes substratos (18 - 21,5%) variaram de acordo com o substrato, sendo considerados elevados; os sólidos solúveis presentes nos cogumelos podem ter relação com vitaminas hidrossolúveis do complexo B; o L. strigosus pode ser considerado um importante alimento devido suas características nutricionais: alto teor de proteína, carboidratos metabolizáveis e fibras; baixos teores de lipídios e de calorias.
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Azide-alkyne Huisgen click chemistry provides new synthetic routes for making thermoplastic polytriazole polymers-without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young's modulus compared to C18C4 and C18C18. This was due to the odd-even effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries.