Ti-Mo alloys employed as biomaterials: Effects of composition and aging heat treatment on microstructure and mechanical behavior

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

Evaluation of diffusive gradients in thin films technique (DGT) for measuring Al, Cd, Co, Cu, Mn, Ni, and Zn in Amazonian rivers

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

Heat Treatment and Yb-Fiber Laser Welding of a Maraging Steel

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Obtention and characterization of collagen and chitosan based cements for bone regerneration. Part 1: extraction and characterization of collagen

Several cements are used as biomaterials. Biopolymers such as chitosan and collagen exhibit excellent biocompatibility and can be used in the remodeling of bone tissue. The cement must have high mechanical strength and compatibility with original tissue. In this context, the objective of this study was to extract, characterize and cross-link collagen from bovine tendon, forlater associate it with chitosan and calcium phosphate to obtain cements for bone regeneration. Glutaraldehyde was used as cross-linker in 0.1, 0.5, 1.0 and 10% concentration. Infrared analysis confirmed the presence of functional groups characteristic of collagen, whereas the capacity of water absorption decreased with the increasing of cross-linking degree. Denaturation temperatures of collagen samples were obtained by Differential Scanning Calorimetry and Scanning Electron Microscopy showed the fiber structure characteristics of collagen, which were more organized for high degree of cross-linking samples.

Concreto com adição de cinza de bagaço de cana-de-açúcar

Pós-graduação em Engenharia Civil - FEIS

Monitoring the process of densification of 3D and 4D (tridirectional and tetradirectional) carbon/carbon composites

Carbon fiber reinforced carbon composites can be made by iterative liquid impregnation or gas phase carbon deposition routes. In both cases, at the final processing stage the carbon fiber is embedded in carbon matrix which results in unique properties such as low density, high thermal conductivity and thermal shock resistance, low thermal expansion and high modulus, in relation to other refractory materials. In the present study assembled three-directional and four-directional preforms, having 50% volume of pores, were densified by iterative cycles of thermoset resin impregnation followed by pyrolysis under inert atmosphere, until appropriate densities were achieved. The thermoset resin is converted in a carbon matrix during pyrolysis. The iterative manufacturing process of the carbon fiber reinforced carbon composites is evaluated by means of nondestructive techniques based on X-ray computed tomography and electrical resistivity. X-ray computed tomography gives a general mapping view of the filling pores of the preforms which impacts results of the electrical resistivity. After six processing cycles and heat treatments up to 2000?, the final densities of the three-directional and four-directional carbon fiber reinforced carbon composites were 1.16g/cm(3) and an electrical resistivity of approximate to 0.07m. The configuration of preforms, three-directional or four-directional, did not alter the densification profile, in terms of increasing density and reducing porosity during the processing cycles.

Effects of late defoliations on chemical and sensory characteristics of cv. Uva Longanesi wines

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

Relationship between aerobic and anaerobic parameters from 3-minute all-out tethered swimming and 400-m maximal front crawl effort

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

Handgrip strength as a predictor of bone mineral density in cirrhotic outpatients

Osteoporosis is well recognized as a cirrhosis complication; however, most studies assessing this condition included only patients on liver transplantation lists with an elevated rate of bone diseases. While general population studies show that handgrip strength is clearly associated with bone mineral density, until now this tool has not been applied to cirrhotic patients in relation to their bone condition. This study aimed to evaluate whether handgrip strength, bone and liver tests may be useful as predictors of bone disease in cirrhotic outpatients. 129 subjects were included (77 men and 52 women). Dual energy X-ray absorptiometry was applied to evaluate lumbar-spine and femoral-neck T scores. Osteoporosis/osteopenia rates were 26.3%/35.6% in the lumbar spine and 6.9%/41.8% in the femoral neck, respectively. Model selections were based on backward procedures to find the best predictors of low T scores. For lumbar spine, only low handgrip strength and high parathyroid hormone levels were clearly related to low T scores. For femoral neck, only age was associated with low T scores. Handgrip strength may serve as an effective predictor of low lumbar spine T score among cirrhotic outpatients. As cirrhosis affects the lumbar spine more than the femoral neck, these results suggest that handgrip strength should be tested in all cirrhotic patients as a first indicator of bone health. This article is protected by copyright. All rights reserved.

Efeito da vinhaça na membrana impermeabilizante usada nos tanques de armazenamento

This work evaluated the effect of vinasse (residue from sugar cane) in high density polyethylene (HDPE) geomembranes having in mind that it is deposited at temperatures of 80-90˚C on the geomembrane in storage tanks. The objective was to evaluate the resistance of the geomembrane in contact with residue in a total period of 4 months. Physical and mechanical tests, and thermogravimetric analysis (TGA) were used to determine degradation of polymer membranes after chemical immersion. In general, the results obtained show that the vinasse affected the geomembranes significantly in some aspects, for instance, the thickness of the material presented a variation of 7.8%. The average values in both directions at yielding showed a significant loss of tensile strength (34.13%) and strain (23.48%) and an increase in the modulus of elasticity (9.63%). At the rupture the behavior presented the same trend: a loss of 32% for tensile strength and 24.4% for the deformation were observed. Tear strength presented small decrease (4.72%) and puncture resistance a increase of 7.9% after immersion of geomembranes. The TGA tests were not efficient to detect evidence of degradation in samples of geomembranes after exposures, but identified problems in the quality of the supplied material.

Structure, microstructure, and selected mechanical properties of Ti-Zr-Mo alloys for biomedical applications

New titanium alloys for biomedical applications have been developed primarily with the addition of Nb, Ta, Mo, and Zr, because those elements stabilize the β phase and they don’t cause cytotoxicity in the organism. The objective of this paper is to analyze the effect of molybdenum on the structure, microstructure, and selected mechanical properties of Ti-15Zr-xMo (x = 5, 10, 15, and 20 wt%) alloys. The samples were produced in an arc-melting furnace with inert argon atmosphere, and they were hot-rolled and homogenized. The samples were characterized using chemical, structural, and microstructural analysis. The mechanical analysis was made using Vickers microhardness and Young’s modulus measurements. The compositions of the alloys were sensitive to the molybdenum concentration, indicating the presence of α’+α”+β phases in the Ti-15Zr-5Mo alloy, α”+β in the Ti-15Zr-10Mo alloy, and β phase in the Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys. The mechanical properties showed favorable values for biomedical application in the alloys presenting high hardness and low Young’s modulus compared with CP-Ti.

Diffusion of oxygen in some binary Ti-Based alloys used as biomaterials

Ti and its alloys are widely used as biomaterials. Their main properties are excellent corrosion resistance, relatively low elastic modulus, high specific strength, and good biocompatibility. The development of new Ti alloys with properties favorable for use in the human body is desired. To this end, Ti alloys with Mo, Nb, Zr, and Ta are being developed, because these elements do not cause cytotoxicity. The presence of interstitial elements (such as oxygen and nitrogen) induces strong changes in the elastic properties of the material, which leads to hardening or softening of the alloy. By means of anelastic spectroscopy, we are able to obtain information on the diffusion of these interstitial elements present in the crystalline lattice. In this paper, the effect of oxygen on the anelastic properties of some binary Ti-based alloys was analyzed with anelastic spectroscopy. The diffusion coefficients, pre-exponential factors, and activation energies were calculated for oxygen and nitrogen in these alloys.

Propriedades físico-mecânicas de painéis de mdp (medium density particleboard) constituído de bambu e fibra de coco

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A comparative study between crack analysis and a mechanical test for assessing the polymerization stress of restorative composites

Objectives. To verify the hypothesis that crack analysis and a mechanical test would rank a series of composites in a similar order with respect to polymerization stress. Also, both tests would show similar relationships between stress and composite elastic modulus and/or shrinkage. Methods. Soda-lime glass discs (2-mm thick) with a central perforation (3.5-mm diameter) received four Vickers indentations 500 mu m from the cavity margin. The indent cracks were measured (500x) prior and 10 min after the cavity was restored with one of six materials (Kalore/KL, Gradia/GR, Ice/IC, Wave/WV, Majesty Flow/MF, and Majesty Posterior/MP). Stresses at the indent site were calculated based on glass fracture toughness and increase in crack length. Stress at the bonded interface was calculated using the equation for an internally pressurized cylinder. The mechanical test used a universal testing machine and glass rods (5-mm diameter) as substrate. An extensometer monitored specimen height (2 mm). Nominal stress was calculated dividing the maximum shrinkage force by the specimen cross-sectional area. Composite elastic modulus was determined by nanoindentation and post-gel shrinkage was measured using strain gages. Data were subjected to one-way ANOVA/Tukey or Kruskal-Wallis/Mann-Whitney tests (alpha: 5%). Results. Both tests grouped the composites in three statistical subsets, with small differences in overlapping between the intermediate subset (MF, WV) and the highest (MP, IC) or the lowest stress materials (KL, GR). Higher stresses were developed by composites with high modulus and/or high shrinkage. Significance. Crack analysis demonstrated to be as effective as the mechanical test to rank composites regarding polymerization stress. (c) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

SALIVARY CORTISOL AND IMMUNOGLOBULIN A RESPONSES TO SIMULATED AND OFFICIAL JIU-JITSU MATCHES

Moreira, A, Franchini, E, Freitas, CG, Arruda, AFS, Moura, NR, Costa, EC, and Aoki, MS. Salivary cortisol and immunoglobulin A responses to simulated and official Jiu-Jitsu matches. J Strength Cond Res 26(8): 2185-2191, 2012-The aim of this study was to compare the salivary cortisol (sC) and the salivary immunoglobulin A (sIgA) responses to simulated and official Brazilian Jiu-Jitsu (BJJ) matches. Saliva samples were collected from 9 male BJJ athletes before (pre) and after (post) 2 simulated matches (SMs) and 2 official matches (OMs) performed during 2 different competitions. Salivary cortisol and sIgA concentrations (absolute concentration of sIgA [sIgA(abs)] and the secretion rate of sIgA [sIgA(rate)]) were measured by an enzyme-linked immunosorbent assay. For sC, there was an effect of condition (SM vs. OM) (p < 0.05) and a time effect (pre and post) (p < 0.05). The sC was lower during SMs as compared with that during OMs and lower at premeasurement when compared with postmeasurement. No changes were observed for sIgA measurements. In summary, both SMs and official BJJ matches can increase sC levels. Moreover, the higher sC resting levels, observed before OMs, suggest that psychological factors associated with high physical-physiological demands from official BJJ competitions maximize stress hormone responses. In addition, the present findings suggest that the acute effect of BJJ matches on mucosal immunity is minimal, and it seems unlikely that changes in cortisol play a major role in the alterations in sIgA levels in response to BJJ matches. The findings of this study suggest that the use of sC can provide valuable information for coaches regarding athletes' responses to competition. In addition, psychological strategies should be implemented before events, to improve the manner in which BJJ athletes cope with the stress inherent to official matches.