116 resultados para Cleaning procedures


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

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Purpose: To evaluate the influence of heat treatment (HT) procedures of a pre-hydrolyzed silane on bond strength of resin cement to a feldspathic ceramic.Materials and Methods: Ceramic and composite blocks (N = 30) were divided into six groups (n = 5) and subjected to the following conditioning procedures: G1: 9.6% hydrofluoric acid (HF) for 20 s + silane (RelyX Ceramic Primer, 3M ESPE) + resin cement (Panavia F2.0, Kuraray) (control); G2: HF (20 s) + silane + heat treatment in furnace (HTF) (100 degrees C, 2 min) + resin cement; G3: silane + HTF + resin cement; G4-HF (20 s) + silane + heat treatment with hot air (HTA) (50 +/- 5 degrees C for 1 min) + resin cement; G5: silane + HTA + resin cement; G6: silane + resin cement. The microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using a stereomicroscope and SEM to categorize the failure types. The data were statistically evaluated using one-way ANOVA and Tukey's test (5%).Results: The control group (G1) showed no pre-test failures and presented significantly higher mean MTBS (16.01 +/- 1.12 MPa) than did other groups (2.63 +/- 1.05 to 12.55 +/- 1.52 MPa) (p = 0.0001). In the groups where HF was not used, HTF (G3: 12.55 +/- 1.52 MPa) showed significantly higher MTBS than did HTA (G5: 2.63 +/- 1.05 MPa) (p < 0.05). All failure types were mixed, ie, adhesive between the resin cement and ceramic accompanied by cohesive failure in the cement.Conclusion: Heat treatment procedures for the pre-hydrolyzed silane either in a furnace or with the application of hot air cannot replace the use of HF gel for the adhesion of resin cement to feldspathic ceramic. Yet when mean bond strengths and incidence of pre-test failures are considered, furnace heat treatment delivered the second best results after the control group, being considerably better than hot air application.

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This study assessed the effect of different etching durations of feldspathic ceramic with hydrofluoric acid (HF) and ultrasonic cleaning of the etched ceramic surface on the microtensile bond strength stability of resin to a feldspathic ceramic. The research hypotheses investigated were: (1) different etching times would not affect the adhesion resistance and (2) ultrasonic cleaning would improve the adhesion. Ceramic blocks (6 x 6 x 5 mm) (N = 48) were obtained. The cementations surfaces were duplicated in resin composite. The six study groups (n = 8) were: G1Etching with 10% aqueous HF (30 s) + silane; G 210% HF (1 min) + silane; G3-10% HF (2 min) + silane; G4-10% HF (30 s) + ultrasonic cleaning (4 min) in distilled water + silane; G5-10% HF (1 min) + ultrasonic cleaning + silane; G6-10% HF (2 min) ultrasonic cleaning + silane. The cemented blocks were sectioned into microbars for the microtensile test. The etching duration did not create significant difference among the groups (p = .156) but significant influence of ultrasonic cleaning was observed (p = .001) (Two-way ANOVA and Tukey's test, p > 0.05). All the groups after ultrasonic cleaning presented higher bond strength (19.38-20.08 MPa) when compared with the groups without ultrasonic cleaning (16.2117.75 MPa). The bond strength between feldspathic ceramic and resin cement was not affected by different etching durations using HF. Ultrasonic cleaning increased the bond strength between ceramic surface and resin cement, regardless of the etching duration.

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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 Enfermagem (mestrado profissional) - FMB

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This work assessed the performance of membranes made of natural latex extracted from Hevea brasiliensis prepared with three different methods: polymerized immediately after collection without the use of ammonia (L1); polymerized after preservation in ammonia solution (L2); and polymerized after storage in ammonia, followed by Soxhlet technique for the extraction of substances (L3). Polytetrafluoroethylene (PTFE) membrane was used as control. Two 10-mm diameter bone defects were surgically made in the calvaria of thirty adult male New Zealand rabbits. Defects (total n = 60) were treated with guided bone regeneration (GBR) using L1, L2, L3 or PTFE membranes (n = 15 for each membrane). Ten animals were euthanized after 7, 20 and 60 days postoperatively so that five samples (n = 5) of each treatment were collected at each time, and bone regeneration was assessed microscopically. The microscopic analysis revealed defects filled with blood clot and new bone formation at the margins of the defect in all 7-day samples, while 20-day defects were mainly filled with fibrous connective tissue. After 60 days defects covered with L1 membranes showed a significantly larger bone formation area in comparison to the other groups (P < 0.05, ANOVA, Tukey). Additionally, bone tissue hypersensitization for L1 and PTFE membranes was also investigated in six additional rabbits. The animals were subjected to the same surgical procedure for the confection of one 10-mm diameter bone defect that was treated with L1 (n = 3) or PTFE (n = 3). Fifty-three days later, a second surgery was performed to make a second defect, which was treated with the same type of membrane used in the first surgery. Seven days later, the animals were euthanized and samples analyzed. No differences among L1 and PTFE samples collected from sensitized and non-sensitized animals were found (P > 0.05, Kruskal-Wallis). Therefore, the results demonstrated that latex membranes presented performance comparable to PTFE membranes, and that L1 membranes induced higher bone formation. L1 and PTFE membranes produced no hypersensitization in the bone tissue.

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Objective. To determine the effects of different aging methods on the degradation and flexural strength of yttria-stabilized tetragonal zirconia (Y-TZP)Methods. Sixty disc-shaped specimens (0, 12 mm; thickness, 1.6 mm) of zirconia (Vita InCeram 2000 YZ Cubes, VITA Zahnfabrik) were prepared (ISO 6872) and randomly divided into five groups, according to the aging procedures (n=10): (C) control; (M) mechanical cycling (15,000,000 cycles/3.8 Hz/200N); (T) thermal cycling (6,000 cycles/5-55 degrees C/30 s); (TM) thermomechanical cycling (1,200,000 cycles/3.8 Hz/200N with temperature range from 5 C to 55 C for 60s each); (AUT) 12h in autoclave at 134 degrees C/2 bars; and (STO) storage in distilled water (37 degrees C/400 days). After the aging procedures, the monoclinic phase percentages were evaluated by X-ray diffraction (XRD), and topographic surface analysis was performed by 3D profilometry. The specimens were then subjected to biaxial flexure testing (1 mm/min, load 100 kgf, in water). The biaxial flexural strength data (MPa) were analyzed by 1-way ANOVA and Tukey's test (alpha = 0.05). The data for monoclinic phase percentage and profilometry (Ra) were analyzed by Kruskal-Wallis and Dunn's tests.Results. ANOVA revealed that flexural strength was affected by the aging procedures (p = 0.002). The M (781.6 MPa) and TM (771.3 MPa) groups presented lower values of flexural strength than did C (955 MPa), AUT (955.8 MPa), T (960.8 MPa) and STO (910.4 MPa). The monoclinic phase percentage was significantly higher only for STO (12.22%) and AUT (29.97%) when compared with that of the control group (Kruskal-Wallis test, p = 0.004). In addition, the surface roughnesses were similar among the groups (p = 0.165).Signcance. Water storage for 400 days and autoclave aging procedures induced higher phase transformation from tetragonal to monoclinic; however, they did not affect the flexural strength of Y-TZP ceramic, which decreased only after mechanical and thermomechanical cycling. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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

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

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The performance analysis based on indicators is an important tool when you want to check the economic and financial situation of a company. From the information provided by the ratios and their analysis, we have a better base for a decision making In this context , this study aims to analyse the financial and economic performance of a service providing company in the cleaning area, in the period between 2011 and 2012 , based on selected financial indicators, and basically calculated from the financial statements (Balance Sheet and Income Statement) , beyond effectuated the vertical and horizontal analysis of them. For the methodological procedures it was used a descriptive case of study and combined (quantitative and qualitative). The results revealed that the economic and financial situation of the company is healthy , once the results are considered satisfactory

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Thin films of Ga1-xMnxN have great interest in its potential for control of electron spin (spintronics), in most cases this material is synthesized by techniques that have a high degree of control the deposition parameters, such as molecular beam epitaxy (MBE) and deposition of metalorganic chemical vapor deposition (MOCVD). The sputtering technique is an alternative route to produce such materials. Here we study the film deposition Ga1-xMnxN by reactive sputtering technique and apply enhancements such as a glove box, a residual gas analyzer and temperature control system, in order to growth films epitaxially using an analysis of the preconditions of films analyzed by spectroscopic techniques and microscopic. These procedures helped to improve the technique of deposition by cleaning substrates in an inert environment, and by the analysis of trace gases and heating the substrate holder as explained in the literature. Through the applications and comparisons it can be pointed out that the technique has the advantage of its simplicity and relatively low cost compared to MBE and MOCVD, but produces polycrystalline material

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Pós-graduação em Saúde Coletiva - FMB