Identification of a bisegmented double-stranded RNA virus (picobirnavirus) in calf faeces

To determine the incidence of rotavirus infection among dairy herds in the State of Sdo Paulo, Brazil, 576 faecal samples obtained from calves aged 1-45 days with and without diarrhoea, reared on 63 dairy cattle farms, were analyzed. Polyacrylamide gel electrophoresis (PAGE) identified 28 samples positive for group A rotavirus, while four samples, two diarrhoeic and two non-diarrhoeic, showed a bisegmented genome with a typical picobirnavirus pattern. Electron microscopy revealed spherical virus particles with a diameter of 37 nm and without a defined surface structure. The present study is the first report of a bisegmented virus identified in cattle in Brazil. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Structural features of silicas prepared in n-heptane/water/ethanol/sodium dodecylsulfate microemulsions

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

Barium strontium titanate powders prepared by spray pyrolysis

Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders were submicronic, consisting of spherical, polycrystalline particles, with internal nanocrystalline structure. Crystallite size of 10 nut, calculated using Rietveld refinement, is in a good agreement with results of HRTEM. (c) 2005 Elsevier B.V. All rights reserved.

Effect of the temperature on the TMOS sono-hydrolysis and a study of the structure of the resulting aged sonogels

The effect of temperature on the oxalic acid catalyzed sono-hydrolysis of tetramethoxysilane (TMOS) was studied by means of a heat flux calorimetric method. The activation energy of the process was measured as (24.5 +/- 0.8) kJ/mol in the temperature range between 10 and 50 degreesC. The structural characteristics of the resulting sonogels, after long period of aging in saturated conditions, were studied by means of small angle X-ray scattering. The structure can be described as formed by similar to2.7 nm mean size mass fractal-like aggregates (clusters) of primary silica particles of similar to0.3 nm mean size, all imbibed in a liquid phase. The average mass fractal dimension of the clusters was found to be 2.58. The primary particle density was estimated as 2.23 g/cm(3), in good agreement with the value frequently quoted for fused silica. The volume fraction of the clusters, in the saturated sonogels was estimated as about 28%. The moment in which the meniscus of the liquid phase penetrates into the clusters under rapid evaporation process has been detected by an inflection in the first derivative of the curve of weight loss in a simple thermogravimetric test. (C) 2003 Elsevier B.V. All rights reserved.

The influence of internal surface treatments on tensile bond strength for two ceramic systems

Statement of the Problem: the ceramic composition and surface microstructure of all-ceramic restorations are important components of an effective bonding substrate. Hydrofluoric acid and sandblasting are well-known procedures for surface treatment; however, surface treatment for high alumina-containing and lithium disilicate ceramics have not been fully investigated.Purpose: This in vitro study evaluated the tensile bond strength of resin cement to two types of ceramic systems with different surface treatments.Methods and Materials: Thirty specimens of each ceramic system were made according to the manufacturer's instructions and embedded in polyester resin. Specimens of In-Ceram Alumina [1] and IPS Empress 2 [E] were distributed to three groups with differing surface treatments (n=10): sandblasting with 50 jam aluminum oxide (APA); sandblasting with 110 pm aluminum oxide modified with silica particles (ROCATEC System-RS); a combination of sandblasting with APA and 10% hydrofluoric acid etching (HA) for two minutes on In-Ceram and for 20 seconds for IPS Empress 2. After the respective surface treatments, all the specimens were silanated, and Rely-X resin cement was injected onto the ceramic surface and light polymerized. The specimens were stored in distilled water at 37 degrees C for 24 hours and thermally cycled 1,100 times (5 degrees C/55 degrees C). The tensile bond strength test was performed in a universal testing machine at a 0.5 mm/minute crosshead speed.Results: the mean bond strength values (AWa) for IPS Empress 2 were 12.01 +/- 5.93 (EAPA), 10.34 +/- 1.77 (ERS) and 14.49 +/- 3.04 (EHA). The mean bond strength values for In-Ceram Alumina were 9.87 +/- 2.40 JAPA) and 20.40 +/- 6.27 (IRS). All In-Ceram specimens treated with 10% hydrofluoric acid failed during thermal cycling.Conclusion: the Rocatec system was the most effective surface treatment for In-Ceram Alumina ceramics; whereas, the combination of aluminum oxide sandblasting and hydrofluoric acid etching for 20 seconds worked more effectively for Empress 2 ceramics.

Pesquisa e desenvolvimento de microesferas de poli(vinil álcool) com alta cristalinidade para utilização em embolização e quimioembolização

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades nanoestruturais de géis de sílica preparados com adiçoes de surfactante anionico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nanopartículas de sílica e ácido p-amino benzóico: um estudo de associação para protetores solares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades ópticas em filmes de opalas sintéticas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Partículas magnéticas: ferrita de ítrio 'Y IND. 3''FE IND. 5''O IND. 12' (YIG) recoberta com sílica ('SIO IND. 2')

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

Síntese e caracterização de novos materiais compósitos orgânicos/inorgânicos, fotopolimerizáveis, para uso em restaurações odontológicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Hidroxicarbonato de gadolínio ativado com európio ou térbio trivalentes como precursor de óxidos, oxissulfetos e silicatos luminescentes

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

The potential of novel primers and universal adhesives to bond to zirconia

Objectives: To investigate the adhesive potential of novel zirconia primers and universal adhesives to surface-treated zirconia substrates.Methods: Zirconia bars were manufactured (3.0 mm x 3.0 mm x 9.0 mm) and treated as follows: no treatment (C); air abrasion with 35 mu m alumina particles (S); air abrasion with 30 mu m silica particles using one of two systems (Rocatec or SilJet) and; glazing (G). Groups C and S were subsequentially treated with one of the following primers or adhesives: ZP (Z-Prime Plus), AZ (AZ Primer); MP (Monobond Plus); SU (ScotchBond Universal) and; EA (an Experimental Adhesive). Groups Rocatec and SilJet were silanized prior to cementation. Samples form group G were further etched and silanized. Bars were cemented (Multilink) onto bars of a silicate-based ceramic (3.0 mm x 3.0 mm x 9.0 mm) at 90 degrees angle, thermocycled (2.500 cycles, 5-55 degrees C, 30 s dwell time), and tested in tensile strength test. Failure analysis was performed on fractured specimens to measure the bonding area and crack origin.Results: Specimens from group C did not survive thermocycling, while CMP, CSU and CEA groups survived thermocycling but rendered low values of bond strength. All primers presented a better bond performance after air abrasion with Al2O3 particles. SilJet was similar to Rocatec, both presenting the best bond strength results, along with SMP, SSU and CEA. G promoted intermediate bond strength values. Failure mode was predominately adhesive on zirconia surface combined to cohesive of the luting agent.Conclusions: Universal adhesives (MP, SU, EA) may be a considerable alternative for bonding to zirconia, but air abrasion is still previously required. Air abrasion with silica particles followed by silane application also presented high bond strength values. (C) 2013 Elsevier Ltd. All rights reserved.

Efeitos da exposição à sílica sobre a responsividade vascular e de vias aéreas de ratos

Silicosis, a common type of pneumoconiosis, is an occupational lung disease caused by inhalation of silica dust often with mining activity and thus reaches the miners. The fine and ultrafine silica particles deposited in the alveolar epithelium may lead to the development of progressive massive fibrosis. An increased reactive oxygen species (ROS) production has been proposed to explain the mechanism for induction of pulmonary fibrosis in silicosis. In this situation, alveolar macrophages are activated to phagocytes silica particles deposited in the alveoli. The activated macrophages secrete large amounts of ROS that in turn induce synthesis of fibrotic factors. In addition, the activity of antioxidant enzymes is impaired, which results in increased lipid peroxidation, as well as generating a local inflammatory process. Diffuse pulmonary fibrosis progresses with interstitial collagen deposition. Interstitial collagen overlies small pulmonary arteries and arterioles and thus it is associated with pulmonary hypertension in pulmonary fibrotic diseases. In addition, cytokines and silica particles passing through the respiratory membrane can reach the bloodstream. In this context, the increase in the generation of ROS in the circulation may lead to a reduction in the bioavailability of nitric oxide, an important endothelium-derived relaxing factor. A deficiency in the nitric oxide bioavailability can result in vascular endothelial dysfunction. Moreover, pro-inflammatory cytokines could contribute to the impairment of endothelial function. In the airways, pro-inflammatory cytokines can reduce the smooth muscle responsiveness to β- adrenergic agonists as isoproterenol. Thus, the aim of this study was to evaluate the effect of silica dust instillation in the function of the pulmonary artery, aorta and trachea of rats with acute silicosis. For this purpose, male Wistar rats were anesthetized... (Complete abstract click electronic access below)

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

Pós-graduação em Odontologia Restauradora - ICT