Propriedades ópticas e elétricas de materiais híbridos de sílica/orgânico à base de GPTS:TEOS preparados pelo método sol-gel

Fabrication of optoelectronic devices requires the employment of at least one transparent electrode. Usually, commercially transparent electrodes have been made by deposition of indium tin oxide (ITO) films by RF-Sputtering technique. These commercial electrodes have sheet resistance of about 100 Ω/sq and optical transmittance of 77% at the wavelength of 550 nm. The poly(3,4-ethylenedioxythiophene):polystyrene-sulfonate (PEDOT:PSS) is an alternative material to fabricate transparent electrodes due to its high conductivity (about 600 S/cm) and solubility in water. Soluble conductive materials exhibits advantages for processing of electrode layers, however there is a disadvantage during devices fabrication once materials with the same solvent of the electrode material cannot be coated one over the other. Alternatively, organic/Silica hybrid materials prepared by sol-gel process allow producing bulks and films with high chemical durability. In order to obtain transparent electrodes with high chemical durability, we introduced a blended material comprising the high UV-VIS transparency of organic/Silica sol-gel material and a high conductivity polymer PEDOT:PSS. The organic/Silica sol was obtained using two different molar concentrations (1:1 and 4:1), of tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTS). Amounts of PEDOT:PSS solutions were added to the sol material, resulting in different weight fractions of sol and polymer. G:T/P:P were deposit onto glass substrates by spray-coating. In order to perform electrical characterization of the blended material, gold electrodes were thermally evaporated onto the films. The electrical characterization was performed using a Keithley 2410 source/meter unity and the optical characterization, using a Cary50 UV-Vis spectrophotometer. The absorption coefficient and electric conductivity of the different compositions blends, as function of the PEDOT:PSS concentration, were...

Comportamento do esmalte de dentes decíduos após desafio desmineralizante em função de materiais restauradores: estudo ao microscópio de luz polarizada

Pós-graduação em Biopatologia Bucal - ICT

Jato de plasma frio em pressão atmosférica para tratamento de materiais e esterilização

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resistência de união entre um cimento resinoso e uma cerâmica aluminizada submetida a diferentes tratamentos de superfície

Pós-graduação em Odontologia Restauradora - ICT

Avaliação do selamento de ápices radiculares retrobturados ou recobertos com diferentes materiais mediante infiltração marginal por corante e análise da interface em microscopia eletrônica de varredura

The purpose of this study was to evaluate the apical sealing ability and the marginal adaptation of five dental materials used in retrofillings or applied to the bevelled root surface. One hundred and forty extracted single rooted human teeth were used, divided into seven groups of twenty each. ln the first, second, third and fourth groups, the teeth were apicoectomized, submitted to cavity preparations and retrofilled with one of the following materiais: zinc free silver amalgam, a dentin bonding system plus composite resin, a glass ionomer cement ora compomer. In the fifth, sixth and seventh groups, the teeth were apicoectomized and capped on the bevelled root surface with one of the following materiais: a dentin bonding system plus composite resin, a glass ionomer cement or a compomer. Two specimens of each experimental group were evaluated for the marginal adaptation using scanning electron microscopy. The remaining 126 specimens were immersed in 2% methylene blue dye, stored for one week at 37ºC and the infiltration was evaluated with a stereomicroscope. The results showed that the glass ionomer cement presented the lowest values of marginal infiltration when used as retrofilling material, with a significant statistical difference when compared with the others tested materials. When used as apical capping, the glass ionomer cement and the compomer were equivalent and significantly better than the dentin bonding system plus composite resin. Using scanning electron microscopy, all the materials showed some slight adjustment problem. ln the retrofilling, the smallest marginal gaps were observed with the compomer and the dentin bonding system plus composite resin, while the largest were observed with the glass ionomer cement and zinc free silver amalgam. ln the apical capping, the smallest marginal gaps were observed with the compomer and the dentin bonding system plus composite resin and ...

Filmes híbridos PMMA-siloxano modificados com nanotubos de carbono para proteção de materiais metálicos contra corrosão

Using the sol-gel process, organic-inorganic hybrid coatings were synthesized by incorporation of different concentrations of functionalized carbon nanotubes, to improve their mechanical strength and thermal resistance without changing its passivation character. The siloxane-PMMA hybrids were prepared by radical polymerization of methyl methacrylate (MMA) with 3-methacryloxipropiltrimethoxisilane (MPTS) using the thermal initiator benzoyl peroxide (BPO), followed by acid catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS). The analysis of pristine and functionalized carbon nanotubes was carried out using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Raman Spectroscopy. Structural analysis of hybrids was performed by Nuclear Magnetic Resonance, Atomic Force Microscopy and Raman Spectroscopy. For analysis of mechanical strength and thermal stability were performed mechanical compression tests and thermogravimetric analysis, respectively. Electrochemical Impedance Spectroscopy was used to evaluate the corrosion resistance in saline environment. The results showed an effective functionalization of carbon nanotubes with carboxyl groups and conservation of its structure. The hybrids showed high siloxane network connectivity and roughness of approximately 0.3 nm. The incorporation of carbon nanotubes in the hybrid matrix did not change significantly their thermal stability. Samples containing carbon nanotubes exhibit good corrosion resistance (on the order of MΩ in saline environment), but the lack of complete dispersion of carbon nanotubes in the hybrid, resulted in a loss of mechanical and corrosion resistance compared to hybrid matrix.

Análise de materiais para sistemas de fechamento ósseo através da caracterização superficial e comportamento mecânico

Pós-graduação em Engenharia Mecânica - FEB

Características químico-mineralógicas e cerâmicas da matéria-prima utilizada pelo polo cerâmico de Rio Verde de Mato Grosso, MG

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo de materiais supercondutores em forma de SQUID com uma constrição usando métodos de paralelização computacional

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Materiais derivados de hidróxidos duplos lamelares: síntese, caracterização e aplicação em adsorção e processos avançados de oxidação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Laminados cerâmicos em dentes tratados endodonticamente: considerações restauradoras e endodônticas com finalidade protética

A harmonia e beleza de um sorriso podem ser comprometidos pela presença de apenas um dente da região anterior que se apresente escurecido, mesmo que os demais elementos estejam alinhados e com forma adequada. A alteração de coloração, mesmo que mínima, sendo na região frontal é capaz de gerar um ponto de tensão e de desequilíbrio no sorriso, concentrando o olhar do observador no local1,2,3. Logo, a demanda dos pacientes por um sorriso estético, belo e harmonioso aumenta o desafio do profissional que visa integrar as características ópticas de um dente anterior despolpado e escurecido com os demais dentes polpados e sem manchamentos significativos. O clareamento é a alternativa mais conservadora para resolver o escurecimento em dentes despolpados. Apesar de resultados satisfatórios, alguns clínicos e autores relutam em assumir, como rotina, os procedimentos de clareamento para dentes despolpados, pelo alto índice de recidiva de escurecimento4,5. Mas, é importante lembrar que as recidivas descritas, normalmente, não contemplam um retorno aos valores inicias de manchamento. Deve ser feito um bom planejamento, levando em considerações fatores como a idade do paciente, o grau de escurecimento, o tempo em que o dente se encontra escurecido e a dificuldade em se alcançar o clareamento do dente, que são determinantes para o sucesso do tratamento clareador e para estabelecer a longevidade do clareamento obtido. Por isso, não são todos os dentes despolpados que apresentam alteração de cor que podem ser clareados, devendo ser avaliados com precisão os critérios estabelecidos3. Os dentes tratados endodonticamente e escurecidos, muitas vezes, necessitam da reintegração estética, associando as técnicas de clareamento com procedimentos restauradores ou, dependendo da condição do dente, a escolha imediata por procedimentos restauradores diretos ou indiretos.

Plástica gengival associada à laminados cerâmicos para resolução estética

Sometimes we face clinical situations in which the lack of harmony in the smile is caused by a major exhibition of the gingival tissue. In these cases the professional should be able to perform a detailed analysis of the static and dynamic components of the smile, in search of a satisfactory planning and treatment which may include different dental specialties. For these situations, the association of periodontics/prosthesis is a viable alternative that has been used positively in search of an aesthetic and functional condition that benefits the patient, without leaving aside the preservation of periodontal tissues and of the remaining structure of the tooth. Thus, the aim of this study was to describe a case in which the association between these two areas was proposed to correct gummy smile and dental vestibularization. Clinical results and the satisfaction of the patient indicate that this multidisciplinary treatment combining periodontal and prosthetic techniques is favorable to positive results in cases of compromised smile aesthetics due to excessive gum tissue.

Reabilitação estética com enfoque nas diferentes cores de substratos e na escolha da cor do cimento adesivo

The evolution of techniques and materials applied to adhesive ceramic restorations resulted in the intensification of its use, proving to be an excellent method of aesthetic restoration. Some important features of this technique are its conservative preparation, which avoids an excessive loss of tooth structure and its high aesthetic value provided by the ceramic even when utilized under different color of dental substrates. The aim of this paper was to report a clinical case with full crowns, porcelain veneers and non-prep veneers, enhancing peculiarities related to the material used, tooth preparation techniques, cementing, indications and contraindications.

Osseointegração de implantes instalados sem estabilidade primária: o papel dos materiais à base de fibrina e fosfato de cálcio

When implants are installed immediately after tooth extraction may occur anchoring primary decreased, delay or failure of osseointegration process. This occurs because of the large interface between the surrounding walls of the socket and the surface of the implant. For reconstruction, replacement or filling of bone defects the solution can be obtained with the use of autogenous, heterogenous or allogeneic bone grafts. However, these grafts suffer certain drawbacks, particularly a high rate of donor site morbidity, limited amounts of available bone, and the additional operative time required for harvest. For these reasons, intensive efforts have been directed toward developing alternative substances for to either augment or substitute. In this paper, we will examine some of the commonly used materials : fibrin and calcium phosphate.

Emprego de técnica cirúrgica e materiais adesivos diretos no fechamento de diastema

The following is a clinical case report of a patient whose main complaint was the presence of a generalized spacing in the anterior maxillary segment. After meticulous clinical analysis and discussions of the clinical procedures to be adopted, a labial frenectomy was our first choice, so that we could reduce the diastemas directly using composite resin. It was observed that the association of clinical and restorative procedures was capable of giving back shape, function and dental aesthetics, allowing to the young patient the satisfaction of smiling without any fear.