567 resultados para Discos abrasivos


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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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Pós-graduação em Engenharia Mecânica - FEG

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O sucesso das restaurações metálicas indiretas depende, dentre outros fatores, de uma união eficaz entre a estrutura metálica e o cimento dentário empregados. Sabe-se que os primers para metal atuam com comprovada eficácia na resistência adesiva dos cimentos resinosos às ligas nobres. Entretanto, pouco foi estudado sobre o efeito de tais materiais em ligas não nobres. O propósito deste estudo foi avaliar a eficácia de primers para metal na resistência ao cisalhamento da união entre cimentos resinosos e metais não nobres. Discos (9 mm de diâmetro e 3 mm de altura) foram fundidos em liga de NiCr (n=80) e em titânio comercialmente puro (Ti c.p.) (n=80) e foram incluídos em anel de PVC com resina acrílica quimicamente ativada. As superfícies dos discos foram regularizadas com lixas de carbeto de silício de granulação 320, 400 e 600 e jateadas com partículas de óxido de alumínio de 50 µm. Espécimes de cada metal foram divididos em quatro grupos (n=20). Uma matriz metálica bi-partida (5 mm de diâmetro interno e 2 mm de altura) foi posicionada na superfície do espécime. As áreas adesivas receberam um dos seguintes tratamentos: 1) Panavia F; 2) Alloy Primer e Panavia F; 3) Bistite DC e 4) Metaltite e Bistite DC. Para evitar a exposição dos cimentos à luz, estes foram espatulados e inseridos na matriz dentro de uma câmara de revelação radiográfica. Quarenta minutos após a confecção, os espécimes foram armazenados em água destilada a 37ºC por 24 horas e então termociclados (1.000 ciclos, 5ºC e 55ºC, 30 segundos cada banho). Após a termociclagem, os espécimes foram armazenados novamente nas mesmas condições descritas anteriormente por um período de 24 horas (n=10) ou de 6 meses (n=10) antes do ensaio de cisalhamento em uma máquina de ensaios mecânicos (Material Test System 810).

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The aim of this work was to evaluate the types of resistance of soybean genotypes to the attack of Spodoptera cosmioides (Walker, 1858), under laboratory conditions. Plants of the soybean genotypes, IAC 100, Dowling, PI 227687, PI 274454, BR 16, IGRA RA 626 RR, PI 227682, BRSGO 8360, IGRA RA 516 RR e P 98Y11 RR, were cultivated in vases and placed in a greenhouse in order to have their leaves used afterwards in free-choice and no-choice no-preference for feeding tests and evaluation of the biological parameters of S. cosmioides fed on the genotypes. For free-choice no preference for feeding test, 10 leaf discs were prepared and placed in Petri dishes equidistantly among themselves, and then two recently-hatched caterpillar per genotype were release in the center of the plate. The same test was performed for third instar larvae, so that one caterpillar per genotype was used. In non-choice test, only one genotype was used in each Petri dish, where two recently-hatched or one third instar caterpillars were released, respectively. For both tests, the attractiveness was assessed at 1, 3, 5, 10, 15, 30, 60, 120, 360, 720 and 1440 minutes after the release of the insects. In addition, the leaf area consumed was evaluated. Randomized blocks design and completely randomized design were used for free-choice and non-choice tests, respectively, with 10 replications. In biology test, recently-hatched larvae were transferred to Petri dishes with leaves of the genotypes, evaluating the period of larvae, pupae and overall (larvae + pupae), viability of larvae, pupae and overall, weight of 12 days-old larvae and 24 hours-old pupae and longevity of the adults. Completely randomized design was used for this test, with 30 replications. Genotypes IGRA RA 516 RR and IGRA RA 626 RR were the least and the most consumed by recently-hatched larvae of S. cosmioides, respectively, in non-choice non-preference for feeding test. Genotypes PI 274454 and PI 227687 were...

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The catalytic function of extended-spectrum β-lactamases can result in high degrees of bacterial resistance to β-lactamic antimicrobials and in the emergence of ESBL among the members of Enterobacteriaceae family, especially Klebsiella pneumoniae and Escherichia coli. This occurs due to the dissemination and emergence of new variants of these enzymes caused by the high utilization of antibiotics like broad-spectrum cephalosporins. The ESBL are β-lactamases capable of conferring bacterial resistance to the penicillins, 1st, 2nd and 3rd generation cephalosporins, and aztreonam (but not cephamycins and carbapenems) through the hydrolysis of these antibiotics. In view of this phenomenon, the exact screening and detection of the producers of ESBL are essential for the appropriate selection of the antimicrobial therapy. The purposes of this study were to evaluate the best antimicrobial for the selection of ESBL producers and to determine the best method for the detection of such microorganisms. We evaluated 200 sequential bacterial samples including the species Klebsiella pneumoniae (56.5%), Escherichia coli (34%), Proteus mirabilis (8.5%) and Klebsiella oxytoca (1%), previously characterized as ESBL producers between February and September 2008 in the Laboratory of Microbiology, Botucatu Medical School - UNESP, Botucatu, São Paulo State, Brazil. To select the ESBL-producer bacteria, we used the disks recommended by CLSI 2008, aztreonam (ATM), cefpodoxime (CPD), ceftriaxone (CRO), cefotaxime (CTX) and ceftazidime (CAZ), besides cefepime (FEP). ESBL production was confirmed by three methods: double disk screening, ESBL Etest®, and Vitek® automated system. The disks employed in the double disk screening were: penicillin associated with β-lactamase inhibitor, amoxicillin-clavulanic acid, and two β-lactamic antibiotics, ceftazidime and cefotaxime...(Complete abstract click electronic access below)

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This research The Vilelas: illustration of the modern quest redneck identity of the peasant represented by two layers of compact disc (CD) of Ivan Vilela, Paisagens (1998) and Dez Cordas (2007). The first brings new songs and the second, copyright music with readings. Both illustrated by an artist named Fernando Vilela. The covers, in a symbiosis with culture and their traditional behavior hillbilly show relevance to constitute a parallel with today's society and the day by day

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This study evaluated the effect of physical and chemical activation on the speed of penetration of hydrogen peroxide bleaching agents present in different concentrations through the enamel and dentin. One hundred and twenty bovine incisors were used, which were obtained enamel/dentin discs of the buccal surface, with 6 mm in diameter. The samples were divided into six groups: G1 - Hydrogen Peroxide Gel 20%, G2 - Hydrogen Peroxide Gel 20% with light activation, G3 - Hydrogen Peroxide Gel 20% with Manganese Gluconate; G4 - Hydrogen Peroxide Gel 35%; G5 - Hydrogen Peroxide Gel 35% with the light activation and G6 - Hydrogen Peroxide Gel 35% with Manganese Gluconate. The specimens were placed in a transparent support on which there was a substance sensitive to hydrogen peroxide immediately below and in contact with the specimen. After the procedures for applying the gel for each group, one video camera was positioned and operated to monitor the time of penetration of peroxide in each specimen. The recording ended after changing the color of the fluid revealed in all specimens and times were noted for comparison. ANOVA analysis showed that concentration and type of activation of bleaching gel significantly influenced the diffusion time of hydrogen peroxide (P 0.05). 35% hydrogen peroxide showed the lowest diffusion times compared to the groups with 20% hydrogen peroxide gel. The light activation of hydrogen peroxide decrease significantly the diffusion time compared to chemical activation. The highest diffusion time was obtained with 20% hydrogen peroxide chemically activated. The diffusion time of hydrogen peroxide was dependent on activation and concentration of hydrogen peroxide. The higher concentration of hydrogen peroxide diffused through dental tissues more quickly

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Charcoal is obtained from carbonization, much used in the steel industry for ore reduction, using as raw material the Eucalyptus. The present study aims to verify whether the main Eucalyptus saligna genetically modified produce quality charcoal with only 3.5 years old. The study was done with material collected from three trees, divided into five discs removed at 0, 25 , 50 , 75 and 100 % of the commercial height of the tree. The procedures adopted were based on standards published by ABNT. The results were satisfactory for the parameters: basic wood density with an average of 0.39 ± 0.0082 g / cm ³; volatile materials from coal with an average of 19.35 ± 3.27 %, fixed carbon content of the coal with an average of 75.62 ± 3.40 % and gross calorific value of coal with an average of 4694.43 cal / g, and unsatisfactory results for ash content averaging 5.03 ± 0.23 when compared to the values found in the literature. It was concluded that the studied wood is able to produce charcoal, but the factors of production should be better observed, such as heating time which exerted direct influence on the determination of ash content

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The objective of the present work was to evaluate surface of experimental alloy Ti-7.5Mo after hydrothermal treatment. Ingots were obtained in arc melting furnace under an argon atmosphere and then homogenized under vacuum at 1100ºC for 86.4 ks to eliminate chemical segregation and after cold worked discs were cutting and grinding. For surface treatment, samples were immersed in a container with NaOH aqueous solution 5M, autoclaved, washed with distilled water. Followed, samples were heat treated and they were soaking in 5xSBF to form an apatite layer on the surface. Surfaces were investigated by, scanning electron microscopy, X-Rays powder diffraction, atomic force microscopy and contact angle, in order to evaluate the wettability of the alloy surface. The results were compared with our previous studies using the group of chemical surface treatments and results shows better condition is 120 minutes in the autoclave

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

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Patients that are mechanically ventilated in ICUs are constantly exposed to different pathogens, which present multiantibiotic resistance. Among these microorganisms, is MRSA (Meticillin-Resistant Staphylococcus aureus) considered to be a therapeutic challenge due to its resistance to β-lactam antibiotics. Therefore, this study proposed to identify species of Staphylococcus spp. isolated from mechanically ventilated patients in ICU, the gene mecA detection and the genes of the enterotoxins A (sea), B (seb), C (sec-1) and D (sed) in samples of S. aureus, as well as the phenotypic resistance determination to oxacillin using the disc-diffusion method with discs of oxacillin and cefoxitin. The samples collection occurred during in a period of 19 months, obtaining samples from 232 patients. A percentage of 39% (70) of Gram-positive cocci were found; which 82,8% (58) were identified as Staphylococcus spp,. among these, 75,8% (44) corresponded to S. aureus species and 47,7% were identified as MRSA. It was found resistance to both drugs in 31,8% of the S. aureus samples, 16 (36,3%) had the gene sea and 11 (25%) had the sec-1 gene. Among the coagulase-negative staphylococci obtained, the species most found was S. epidermidis, corresponding to 43% (6). The results revealed that one of the most important etiologic agents of VAP amid the Gram-positive cocci is the species S. aureus, with special attention to MRSA. The presence of enterotoxins genes in S. aureus did not showed determinant role in VAP, but the presence of these superantigens can contribute worsening the patient’s prognosis, since they are associated with intense inflammatory response

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Titanium and its alloys has been widely used as materials for metallic biomaterials implants are usually employed to restore the hard tissue function, being used for artificial joints and bones, synthetic plates, crowns, dental implants and screws . Objective of this work was the surface modification of Ti-alloy 25Ta from biomimetic surface treatment of employment and deposition of polymer by electrospinning. The league was obtained from the fusion of the pure elements in the arc furnace with controlled atmosphere. The ingots were subjected to heat treatment, cold forged and sectioned discs with 13 mm diameter and 3 mm thick. Two surface treatments was evaluated, biomimetic and electrospinning with PCL fiber. The biomimetic treatment was performed involving alkaline treatment for three molarities 1.5M, 3M and 5M with immersion in SBF. The electrospinning was performed using PCL polymer alloy surface after the alkali treatment Ti25Ta 1M. For this group the polymer coated surfaces were immersed in calcium phosphate containing solution for immobilization of apatite. The results were compared with previous studies using surface treatment group to verify hydroxyapatite formation on the sample surface and it is concluded that the best condition is biomimetic treatment with 5M alkali treatment and heat treatment at 80 ° C for 72 hours