Desgaste e rugosidade superficial de um cimento de ionômero de vidro nanoparticulado

To compare the abrasion wear resistance and superficial roughness of different glass ionomer cements used as restorative materials, focusing on a new nanoparticulate material. Material and Method: Three glass ionomer cements were evaluated: Ketac Molar, Ketac N100 and Vitremer (3M ESPE, St. Paul, MN, USA), as well as the Filtek Z350 (3M ESPE, St. Paul, MN, USA). For each material were fabricated circular specimens (n=12), respecting the handling mode specified by the manufacturer, which were polished with sandpaper disks of decreasing grit. The wear was determined by the amount of mass (M) lost after brushing (10,000 cycles) and the roughness (Ra) using a surface roughness tester. The difference between the Minitial and Mfinal (ΔM) as well as beroughness of aesthetic restorative materials: an in vitro comparison. SADJ. 2001; 56(7): 316-20. 11. Yip HK, Peng D, Smales RJ. Effects of APF gel on the physical structure of compomers and glass ionomer cements. Oper. Dent. 2001; 26(3): 231-8. 12. Ma T, Johnson GH, Gordon GE. Effects of chemical disinfectants on the surface characteristics and color of denture resins. J Prosthet Dent 1997; 77(2): 197-204. 13. International organization for standardization. Technical specification 14569-1. Dental Materials – guidance on testing of wear resistance – PART I: wear by tooth brushing. Switzerland: ISO; 1999. 14. Bollen CML, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dent Mater.1997; 13(4): 258-9. 15. Kielbassa AM, Gillmann C, Zantner H, Meyer-Lueckel H, Hellwig E, Schulte-Mönting J. Profilometric and microradiographic studies on the effects of toothpaste and acidic gel abrasivity on sound and demineralized bovine dental enamel. Caries Res. 2005; 39(5): 380-6. 16. Tanoue N, Matsumara H, Atsuta M. Wear and surface roughness of current prosthetic composites after toothbrush/dentifrice abrasion. J Prosthet Dent. 2000; 84(1): 93-7. 17. Heath JR, Wilson HJ. Abrasion of restorative materials by toothpaste. J Oral Rehabil. 1976; 3(2): 121-38. 18. Frazier KB, Rueggeberg FA, Mettenburg DJ. Comparasion of wearresistance of class V restorative materials. J Esthet Dent. 1998; 10(6): 309-14. 19. Momoi Y, Hirosakil K, Kohmol A, McCabe JF. In vitro toothebrushdentifrrice abrasion of resin-modified glass ionomers. Dent Mater. 1997; 13(2): 82-8. 20. Turssi CP, Magalhães CS, Serra MC, Rodrigues Jr.AL. Surface roughness assessment of resin-based materials during brushing preceded by pHcycling simulations. Oper Dent. 2001; 26(6): 576-84. 21. Wang L, Cefaly DF, Dos Santos JL, Dos Santos JR, Lauris JR, Mondelli RF, et al. In vitro interactions between lactic acid solution and art glassionomer cements. J Appl Oral Sci. 2009; 17(4): 274-9. 22. Carvalho FG, Fucio SB, Paula AB, Correr GM, Sinhoreti MA, PuppinRontani RM. Child toothbrush abrasion effect on ionomeric materials. J Dent Child (Chic). 2008; 75(2): 112-6. 23. Coutinho E, Cardoso MV, De Munck J, Neves AA, Van Landuyt KL, Poitevin A, et al. Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer. Dent Mater. 2009; 25(11): 1347-57. tween Rainitial and Rafinal (ΔRa) were also used for statistical analysis (α=0.05). Results: Except for the composite, significant loss of mass was observed for all glass ionomer cements and the ΔM was comparable for all of them. Significant increase in roughness was observed only for Vitremer and Ketac N100. At the end of the brushing cycle, just Vitremer presented surface roughness greater than the composite resin. Conclusion: All glass ionomer cements showed significant weight loss after 10,000 cycles of brushing. However, only Vitremer showed an increase of roughness greater than the Z350 resin, while the nanoparticulate cement Ketac N100 showed a smooth surface comparable to the composite.

Estimativa da divergência entre ecótipos de braquiária baseada em descritores quantitativos e qualitativos

This study aimed to estimate the genetic divergence between Urochloa brizantha ecotypes based on quantitative, qualitative descriptors and their joint analysis to select the promising to release as cultivars of this species. Eight ecotypes (B1, B2, B3, B4, B5, B6, B8) and cultivar 'Marandu' of U. brizantha were implanted into pickets with 1000m2 each, with two repetitions. Five quantitative descriptors were evaluated [leaf area (ALF), length and width of leaf blades (CLF and LLF, respectively), dry mass (MS), mass of dry matter (MMS) and proportion of leaf blade in MS (PLF)] in two forage samples, being a representative of rainfall, in February 2000, and another in the dry period, in August 2000. It was measured the qualitative descriptors: shear strength (RC), volume of accumulated gas in fast and slow fraction (A and B, respectively), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF ), cellulose (CEL), lignin in sulfuric acid (LIG), silica (SIL) and in vitro digestibility of organic matter (IVOMD). There was considerable genetic divergence in U. brizantha ecotypes, especially regarding to quantitative descriptors. Based on the groupings of quantitative, qualitative descriptors and their joint analysis, the grouping containing of B1, B3 and B5 with 'Marandu' can result in promising U. brizantha ecotypes

Vinhaça da indústria sucroalcooleira como matéria-prima a carbonização hidrotérmica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Corrosão do aço-carbono: uma abordagem do cotidiano no ensino de química

In this paper, two simple ways of evaluating carbon steel sheet corrosion in a hydrochloric acid solution were presented as an experimental proposal for corrosion teaching. The first method is based on direct measurements of mass before and after corrosion tests. The second approach follows the principle of visual colorimetry by which soluble corrosion products are transformed into red complexes allowing monitoring of the products'concentration according to increases in solution color intensity. Both methods proved able to determine the corrosion rate.

Anodization mechanism on SiC nanoparticle reinforced al matrix composites produced by power metallurgy

Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050) anodized under the same conditions. The processing method of the aluminum alloys influences the efficiency of the anodizing process, leading to a lower thicknesses for the unreinforced Al-PM alloy regarding the AA1050. The current density versus time response is strongly dependent on the amount of SiCnp. The current peaks and the steady-state current density recorded at each voltage step increases with the SiCnp volume fraction due to the oxidation of the SiCnp. The formation mechanism of the anodic film on Al/SiCnp composites is different from that occurring in AA1050, partly due the heterogeneous distribution of the reinforcement particles in the metallic matrix, but also to the entrapment of SiCnp in the anodic film.

Preparação e caracterização de materiais híbridos celulose/NbOPO4.nH2O a partir de celulose branqueada de bagaço de cana-de-açúcar

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

Fabricação e caracterização de diodo Schottky orgânico com arquitetura planar

Usually organic polymeric diodes are made with a semiconductor layer placed between two electrodes in a sandwich-like architecture, where the electrodes are deposited on the surfaces of a polymeric semiconductor film. This methodology leads to two main problems: i) the polymeric film top surface is rough and irregular, resulting in non-uniform electric field into the device; ii) during the deposition of metallic electrode in the top surface polymeric film, by thermal evaporation, occurs the diffusion of metal atoms into the polymeric film, changing the material electronic structure. Thus, the metal-semiconductor junction is not well defined, which is essential for the production of good quality Schottky diode, which exhibits ideality factor close to the unity and low turn-on voltage. In order to avoid these two problems, in the present research was proposed to manufacture an organic diode with the semiconductor polymeric layer deposited over bimetallic (gold and aluminum) interdigitated electrodes. The doping of the active layer was performed by immersing the device in hydrochloric acid solution with pH 2 during different times in order to promote different doping levels of the semiconductor polymer. Was verified that the proposed diode, which exhibits well-defined metal-semiconductor junction, operates as a Schottky diode, with good ideality factor, 10 ± 3, and low turn-on voltage, 1,2 ± 0,2 V, in comparison with conventional organic polymeric diodes. Contrasting with the ideality factor and turn-on voltage, the diode rectification ratio was obtained as 7, a value lower than the expected for a good organic diode. Was also showed that the diode characteristics were dependent on the semiconductor polymer doping level, and that the diode characteristics were optimized with doping promoted by immersion in the acid solution for times longer than 50 s. Furthermore, as was showed that the diodes properties are dependent on the semiconductor...

Osseointegration of anodized implant: effect of fibrin adhesive/TEA on primary stability

Processo FAPESP: 2012/24545-3

Desenvolvimento de técnicas e avaliações de antimicrobianos visando a produção de etanol carburante

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biocompatibility of experimental Ti-30Ta implants with compromised primary stability: effect of TEA

Purpose: Ti-Ta alloys have high potential for dental application due to a good balance between high strength and low modulus. Absence of primary anchoring may occur when dental implants are installed immediately after tooth extraction. Tranexamic acid (TEA) is used to reduce fibrin degradation and can prevent early blood clot breakdown. The aim of this study was to evaluate the biocompatibility of Ti-30Ta implants associated or not with tranexamic acid and installed with compromised primary stability. Methods and materials: Fabricated were 20 implants of titanium ASTM F67 (Grade 4) and 20 implants of Ti-30Ta alloy with dimensions of 2.1 mm × 2.8 mm Ø. They were divided (n = 10) into Group I (Ti machined), Group II (Ti machined/tranexamic acid), Group III (Ti-30Ta alloy) and Group IV (Ti-30Ta/tranexamic acid) and were implanted in tibia (defects with 2.5 mm × 3.2 mm Ø) of 40 male rats (250 g). The surgical sites were rinsed with 5% tranexamic acid solution in Groups II and IV. The animals were euthanized at 45 days postoperative. The pieces were processed in methyl methacrylate (Stevenel's blue/Alizarin red). The percentage of peri-implant tissue repair was analyzed via images obtained by an optical microscope coupled to a digital camera using Leica software and Adobe Photoshop QWin. Data were analyzed statistically with a significance level of 5%. Results: Histomorphometric results showed 97.16% of bone-implant contact for group IV, 89.78% of bone contact for group III, 70.89% for group II and 61.59% of bone contact for group I. The statistical analyses demonstrated significant differences (P < 0.05) among group I and other groups. Conclusion: The results suggest that (a) Ti-30Ta promoted an increase of bone healing and apposition around implant; (b) tranexamic acid favored the stabilization of blood clot and bone formation.

Metabolismo nutricional em Atta sexdens rubropilosa Forel, 1908: voo nupcial, fundação e desenvolvimento da colônia

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Mineralogia da fração argila dos solos do Planalto Ocidental Paulista

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produção de etanol utilizando cascas de banana e de laranja por co-fermentação de Zymomonas mobilis e Pichia stipitis

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

Pré-hidrólise ácida de bagaço de cana-de-açúcar e sua caracterização físico-química

The biomass resulting from processing sugarcane bagasse has been considered a source of cellulose with the potential production of bio-fuels. This lignocellulose can be processed into ethanol since is hydrolyzed by chemical processes (acids) or biotechnology (enzymes) which generate sugars suit for fermentation. This study had the objective to utilize physical and chemical pre-treatment processes for prehydrolysis of sugarcane bagasse. The experimental treatment was adjusted at a factor of 4 X 2, by the combination of pre-hydrolysis timing (15, 30, 45 and 60 minutes) and sulfuric acid concentrations (7.0% and 9.0%) which was incubated at a temperature of 121° C in an autoclave. The treatment data was subjected to analysis of the variance and averages which were compared using the Tukey test with a probability of 5%. The results obtained showed that through pretreatment acid applied on the lignocellulose material, there was a significant break from the substrate fibers like cellulose, hemicellulose and lignin.

Superação de dormência em sementes de messlina (Melissa officinalis L.)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)