The Effect Of Poly(methyl Methacrylate) Surface Treatments On The Adhesion Of Silicone-based Resilient Denture Liners.

Different surface treatment protocols of poly(methyl methacrylate) have been proposed to improve the adhesion of silicone-based resilient denture liners to poly(methyl methacrylate) surfaces. The purpose of this study was to evaluate the effect of different poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners. Poly(methyl methacrylate) specimens were prepared and divided into 4 treatment groups: no treatment (control), methyl methacrylate for 180 seconds, acetone for 30 seconds, and ethyl acetate for 60 seconds. Poly(methyl methacrylate) disks (30.0 × 5.0 mm; n = 10) were evaluated regarding surface roughness and surface free energy. To evaluate tensile bond strength, the resilient material was applied between 2 treated poly(methyl methacrylate) bars (60.0 × 5.0 × 5.0 mm; n = 20 for each group) to form a 2-mm-thick layer. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α = .05). A Pearson correlation test verified the influence of surface properties on tensile bond strength. Failure type was assessed, and the poly(methyl methacrylate) surface treatment modifications were visualized with scanning electron microscopy. The surface roughness was increased (P < .05) by methyl methacrylate treatment. For the acetone and ethyl acetate groups, the surface free energy decreased (P < .05). The tensile bond strength was higher for the methyl methacrylate and ethyl acetate groups (P < .05). No correlation was found regarding surface properties and tensile bond strength. Specimens treated with acetone and methyl methacrylate presented a cleaner surface, whereas the ethyl acetate treatment produced a porous topography. The methyl methacrylate and ethyl acetate surface treatment protocols improved the adhesion of a silicone-based resilient denture liner to poly(methyl methacrylate).

Bipolar Tribocharging Signal During Friction Force Fluctuations At Metal-insulator Interfaces.

Friction and triboelectrification of materials show a strong correlation during sliding contacts. Friction force fluctuations are always accompanied by two tribocharging events at metal-insulator [e.g., polytetrafluoroethylene (PTFE)] interfaces: injection of charged species from the metal into PTFE followed by the flow of charges from PTFE to the metal surface. Adhesion maps that were obtained by atomic force microscopy (AFM) show that the region of contact increases the pull-off force from 10 to 150 nN, reflecting on a resilient electrostatic adhesion between PTFE and the metallic surface. The reported results suggest that friction and triboelectrification have a common origin that must be associated with the occurrence of strong electrostatic interactions at the interface.

Administração limpa e enxuta em sistemas hidráulicos de colhedoras de cana-de-açúcar

Among the important changes in the production processes, it is necessary to guarantee the sustainability of the human enterprises, what makes us to foresee changes in the managerial administration to adapt to a new model, with the insert of the concepts of Clean Production, Cleaner, Lean and Total Productive Maintenance (TPM). The main focus of this work was to elaborate a methodology that made it possible to guarantee the reliability in the waterworks of the sugarcane harvester, identifying and analyzing the manners of flaws, in order to result in the improvement of the environmental and socioeconomic quality in the atmosphere of an industry of sugarcane through the significant decrease of hydraulic oil spill. Through the existent report in ERP (Enterprise Resource Planning), used in a Sugarcane Industry Plant, it was possible to accompany of the operational acting of the sugarcane harvester used during 03 crops, regarding the manners of flaws in the waterworks of the same ones, and, in one of the crops it was elaborated the total control of the waterworks of 5 harvesters. Based on the obtained data and the developed methodology it was possible to develop a software that specifies the electric outlet of decisions.

Democracia Corinthiana : sentidos e significados da participação dos jogadores = Corinthians democracy : meanings and significance of the players' participation

Universidade Estadual de Campinas . Faculdade de Educação Física