Análise fractográfica do modo de falha de compósitos carbono/epóxi

A utilização de compósitos poliméricos na fabricação de aeronaves vem sendo cada vez mais intensa. em função disso, a possibilidade de ocorrer falhas em serviço de um componente fabricado em compósito polimérico torna-se cada vez maior. A análise de falhas de materiais compósitos ainda é um tema pouco explorado, principalmente no Brasil, porém vem tornando-se cada vez mais importante em apoio à área de prevenção e investigação de acidentes aeronáuticos. Este trabalho teve como objetivo a caracterização de fraturas em laminados unidirecionais de fibra de carbono de módulo intermediário com sistema de resina epóxi modificada, tipo 8552, em resistência ao cisalhamento interlaminar nas condições ambiente e saturado de umidade em câmara higrotérmica. A análise fractográfica no plano de falha dos laminados foi realizada por microscopias óptica e eletrônica de varredura. A comparação dos resultados mostrou que o condicionamento higrotérmico afetou significativamente a região de interface da resina sem alterar a adesão interfacial fibra/resina. Os aspectos de fratura presentes na região de resina, como cristas de galo e escarpas, e do reforço foram detalhados, podendo-se assim estabelecer a direção de propagação da trinca e caracterizar o modo de falha, por ser do tipo misto (arrancamento e cisalhamento simultaneamente).

Evaluation on fatigue strength of AISI 4340 steel aluminum coated by electroplating and IVD processes

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

Effects of several TIG weld repairs on the axial fatigue strength of AISI 4130 aeronautical steel-welded joints

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

STUDY of THE TURNING NICKEL BASE ALLOY PYROMET (R) 31V (SAE HEV8)

Considering the constant technological developments in the aeronautical, space, automotive, shipbuilding, nuclear and petrochemical fields, among others, the use of materials with high strength mechanical capabilities at high temperatures has been increasingly used. Among the materials that meet the mechanical strength and corrosion properties at temperatures around 815 degrees C one can find the nickel base alloy Pyromet 31V (SAE HEV8). This alloy is commonly applied in the manufacturing of high power diesel engines exhaust valves where it is required high resistance to sulphide, corrosion and good resistance to creep. However, due to its high mechanical strength and low thermal conductivity its machinability is made difficult, creating major challenges in the analysis of the best combinations among machining parameters and cutting tools to be used. Its low thermal conductivity results in a concentration of heat at high temperatures in the interfaces of workpiece-tool and tool-chip, consequently accelerating the tools wearing and increasing production costs. This work aimed to study the machinability, using the carbide coated and uncoated tools, of the hot-rolled Pyromet 31V alloy with hardness between 41.5 and 42.5 HRC. The nickel base alloy used consists essentially of the following components: 56.5% Ni, 22.5% Cr, 2,2% Ti, 0,04% C, 1,2% Al, 0.85% Nb and the rest of iron. Through the turning of this alloy we able to analyze the working mechanisms of wear on tools and evaluate the roughness provided on the cutting parameters used. The tests were performed on a CNC lathe machine using the coated carbide tool TNMG 160408-23 Class 1005 (ISO S15) and uncoated tools TNMG 160408-23 Class H13A (ISO S15). Cutting fluid was used so abundantly and cutting speeds were fixed in 75 and 90 m/min. to feed rates that ranged from 0.12, 0.15, 0.18 and 0.21 mm/rev, and cutting depth of 0.8mm. The results of the comparison between uncoated tools and coated ones presented a machined length of just 30% to the first in relation to the performance of the second. The coated tools has obtained its best result for both 75 and 90 m/min. with feed rate of 0.15 mm/rev, unlike the uncoated tool which obtained its better results to 0.12 mm/rev.

Influence of voids on the flexural resistance of the NCF/RTM6 composites

A major difficulty to achieve maximum weight savings in the manufacture of composite structural components, is the tendency of these materials have the formation of voids and cracks in the interior and surface components. In aeronautical applications, controlling the volume fraction of fibers, resins and empty the components of composite is very hard. In this work, composites of epoxy matrix RTM6 reinforced with NCF (non crimp fabric carbon) processed by resin transfer molding (RTM) were characterized for porosity (P-ap) and density (rho(ad)). We used a method based on Archimedes' principle (ASTM C830) and the technique of helium pycnometer. The porosity values were compared with those determined by acid digestion (ASTM D3171). The mechanical properties of processed composites was evaluated by testing on the performing flexural and the results were correlated with the porosity value. All techniques tested to determine void content are satisfactory. The differents results can be justified for heterogeneous void distribution on laminate and differences among techniques characteristics. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of ICM11

Adaptive filter feature identification for structural health monitoring in an aeronautical panel

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Time-dependent alterations of soluble and cellular components in human milk

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

Brazilian natural dietary components (annatto, propolis and mushrooms) protecting against mutation and cancer

Considering the high number of new cancer cases in Brazil (approximately 470 000 cases in 2005) and the remarkable differences in the incidence of this disease around the world, the development of chemopreventive strategies using foods widely consumed would have a huge impact, both medically and economically. This review summarizes some of our studies conducted to verify the anti-mutagenic and anti-carcinogenic potential of some Brazilian natural dietary constituents (annatto, mushrooms, and propolis). Overall data have shown a clear role for these compounds in preventing mutation and specific preneoplastic lesions. Taken together, these agents indicate a favorable side-effect profile and may prove to be a promising alternative for cancer prevention strategies, although more investigation is needed to fully explore this issue.

Dietary components may prevent mutation-related diseases in humans

Since it is not always possible to reduce human exposure to mutagens, attempts have been directed to identify potential antimutagens and anticarcinogens for use in protecting the population against environmental disease. The purpose of this paper is to provide the reader with information about the antimutagenic and anticarcinogenic potentials of some dietary constituents and foods widely consumed in Brazil, and to reinforce diet as a key factor in determining genomic stability and preventing human diseases. In this report, we have summarized data that show interactive effects between some dietary components and specific chemical mutagens or carcinogens using in vitro and in vivo short- or medium-term assays. The summary indicates that certain dietary compounds may be useful agents for disease prevention. (C) 2003 Elsevier B.V. All rights reserved.

Expression of cell cycle regulatory proteins in epithelial components of dental follicles

Dental follicle is a component of tooth germs, which remain adjacent to the crown of unerupted or impacted teeth. Under the influence of pathologic changes, however, dental follicles that possess reduced epithelium can proliferate into stratified squamous epithelium as far as originate dental cysts. In order to clarify the role of apoptosis and cellular proliferation herein, expression of p53 and PCNA was examined in epithelial components of dental follicles associated with impacted third molars by means of immunohistochemistry. A total of 40 cases was included in this study being 22 cases with reduced epithelium and 18 cases with stratified epithelium. Expression of p53 expression was weak or not detected in dental follicles with reduced and stratified squamous epithelium. By contrast, PCNA positive cells were evidenced in basal and supra basal layers of the stratified squamous epithelium and in reduced epithelium of dental follicles, but without any significant statistically differences between them (P > 0.05). In conclusion, these data suggest that dental follicles possess proliferative activity as depicted by PCNA-positive nuclei in some epithelial cells. However, the biological behavior of dental follicles during the late stage of dental eruptive process may not be associated with deregulation of death and/or cell proliferation.

Metabolic syndrome and dietary components are associated with coronary artery disease risk score in free-living adults: a cross-sectional study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mapping quantitative trait loci in Gallus gallus using principal components

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

Vasectomy effect on canine seminal plasma biochemical components and their correlation with seminal parameters

Three semen samples were collected at 48 It intervals from 20 mature research dogs previously conditioned to manual semen collection. Vasectomy was performed in all dogs, and 15 days after surgery, another three ejaculates were similarly collected. The semen was evaluated, and centrifuged to obtain seminal plasma for measurement of pH, and concentrations of total proteins (TP), total chlorides (Cl), calcium (Ca), potassium (K), and sodium (Na). The seminal plasma protein profile was evaluated by SDS-PAGE; molecular weights and the integrated optical density (IOD) of each band were estimated. There was a negative correlation between K concentration and progressive motility (r = -0.49, P = 0.027), sperm vigor (r = -0.60, P = 0.0053), and plasma integrity, evaluated by both the hypo-osmotic swelling test (r = -0.50, P = 0.026) and a fluorescent stain (r = -0.45, P = 0.046). Positive correlations between Na and K pre- and post-vasectomy (r = 0.88, P < 0.001; r = 0.56, P < 0.01, respectively) were verified. There were a total of 37 bands pre-vasectomy and 35 post-vasectomy (range, 100.6-3.6 kDa). Bands B9 and B13 (42.6 and 29.2 kDa) were not present post-vasectomy. The IOD of band B3 (73.5 kDa) was higher (P 0.03) pre-vasectomy, compared to post-vasectomy; conversely, the IODs of bands B29 and B37 (7.8 and 3.6 kDa) increased (P 0.026 and 0.047). Pre-vasectomy, there was a positive correlation (r = 0.49, P = 0.029) between band B37 band (3.6 kDa) and the Na:K ratio. In conclusion, K appeared to be involved in sperm motility in dogs and could be a tool to evaluate sperm function. The prostate contributed several elements to canine seminal plasma. Vasectomy changed Ca concentrations and the protein profile of the seminal plasma. Further studies must be performed to clarify the function of these elements on the in vivo fertility of dogs. (c) 2006 Elsevier B.V. All rights reserved.

Characterization of S3Pvac Anti-Cysticercosis Vaccine Components: Implications for the Development of an Anti-Cestodiasis Vaccine

Background: Cysticercosis and hydatidosis seriously affect human health and are responsible for considerable economic loss in animal husbandry in non-developed and developed countries. S3Pvac and EG95 are the only field trial-tested vaccine candidates against cysticercosis and hydatidosis, respectively. S3Pvac is composed of three peptides (KETc1, GK1 and KETc12), originally identified in a Taenia crassiceps cDNA library. S3Pvac synthetically and recombinantly expressed is effective against experimentally and naturally acquired cysticercosis.Methodology/ Principal Findings: In this study, the homologous sequences of two of the S3Pvac peptides, GK1 and KETc1, were identified and further characterized in Taenia crassiceps WFU, Taenia solium, Taenia saginata, Echinococcus granulosus and Echinococcus multilocularis. Comparisons of the nucleotide and amino acid sequences coding for KETc1 and GK1 revealed significant homologies in these species. The predicted secondary structure of GK1 is almost identical between the species, while some differences were observed in the C terminal region of KETc1 according to 3D modeling. A KETc1 variant with a deletion of three C-terminal amino acids protected to the same extent against experimental murine cysticercosis as the entire peptide. on the contrary, immunization with the truncated GK1 failed to induce protection. Immunolocalization studies revealed the non stage-specificity of the two S3Pvac epitopes and their persistence in the larval tegument of all species and in Taenia adult tapeworms.Conclusions/ Significance: These results indicate that GK1 and KETc1 may be considered candidates to be included in the formulation of a multivalent and multistage vaccine against these cestodiases because of their enhancing effects on other available vaccine candidates.

Long-term nano-mechanical properties of biomodified dentin-resin interface components

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