Aim:The purpose of this study was to evaluate the in vitro effect of Light Coke™, phosphoric acid, and citric o acid on the force decline pattern of two types of elastomeric chains. Methods and Materials:One hundred sixty gray colored elastomeric chain modules, 80 Chainette (GAC) and 80 Sunburst™ (GAC) chains, were divided into four groups for immersion into Light Coke, phosphoric acid, citric acid, and artificial saliva. The initial stretched force of the elastomeric chains ranged from 220gf to 250gf. During the experiment, all elastomeric chains were kept immersed in artificial saliva at 37ºC (pH≈6.24) to simulate the oral environment. To simulate daily consumption of Light Coke, the elastomeric chains were immersed in the solutions twice a day for 15 minutes. The control group was kept immersed in artificial saliva continuously with no further treatment. Force (gf) was measured with a Dial-Type dynamometer (Dentaurum ® ), initially (baseline), 24 hours, 7, 14, and 21 days. Data were analyzed using the Tukey test at a 5% level of probability. Results:A statistically significant reduction on the force produced by the elastomeric chains was seen at different time points. The greatest reduction in force occurred in the first 24 hours (p=0.01). Conclusion:Force decay of the Chainette elastomeric chains were lower than the Sunburst™ chain (p<0.05). The immersion treatments caused no statistically significant difference in force for either chain module (p>0.05). Abstract © Seer PublishingClinical Significance: Good elastomeric chain properties are necessary for effective tooth movement, and knowledge of force-decay rates is an important factor in achieving the best orthodontic outcome.

This study investigated the influence of the surface treatment of curaua fibres (Ananas erectifolius) on the morphological, thermal and mechanical properties of polyester composites when the treated fibres (10 wt-%) were added. The following treatment agents were assessed: 10% Ba(OH) 2 , 14% Ca(OH) 2 , 5% NaOH, 10% KOH and 5% silane. The treatments removed amorphous components, thereby increasing the crystallinity of the fibres. Among the alkali treatments, KOH gave the highest crystallinity index (67.09%), Ca (OH) 2 had the best tensile strength (19 MPa) and Ca(OH) 2 treatment resulted in the highest composite thermal stability (315°C). Fibres treated with Ba(OH) 2 resulted in the composite with the greatest resistance to impact (55 vs 10 J m −1 for the neat matrix). Finally, the silane-treated fibres resulted in composites with a better performance than the other treatments. There was a prominent pattern of improved performance for the silane-treated fibre composites in all the analyses performed in this study.

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Quality control to obtain composite laminates is frequently applied to synthetic fibers/epoxy prepregs. The gel time test, resin, volatiles and fiber content, drape measurement and tack tests together with water absorption capacity are methods currently employed. However, for natural fibers prepregs there is a gap in the literature, which makes their application difficult. Thus this work will investigate sisal fibers, which have low cost, high biodegradability and low specific weight, following the common methods to manufacture composites from natural fibers/epoxy prepregs. First, the prepregs were prepared by hand lay-up, aligning the fibers with epoxy, keeping 15% by weight content of fiber. After the quality control characterization, 3 mm thickness composite was prepared by using a press, and tensile tests and scanning electron microscopy (SEM) were applied. As a result, the resin fraction values and the solid content of the matrix showed little variation between the different samples. The natural fibers prepregs absorbed water quickly in the initial stage until reaching the saturation level. The NaOH-treated sisal/epoxy prepreg had a tension of 71.06 ± 8.28 kPa for the tack test and tensile strength of 69.24 ± 11.69 MPa. Finally, the NaOH-treated sisal 15 wt%/epoxy resulted in composites with a better performance than the neat epoxy resin. There was good adhesion between the fibers and matrix, as confirmed by SEM and mechanical tests.

A gestão de resíduos agrícolas e industriais é necessária para mitigar a poluição ambiental resultante de manejo de animais. Uma alternativa é utilizar resíduos para geração de energia, tornando um substrato com alto potencial poluidor ao meio ambiente em produto com maior valor agregado, como o biogás. O uso da Avaliação do Ciclo de Vida (ACV) para quantificar os impactos ambientais desses processos é uma ferramenta ideal e já consolidada mundialmente. Dentro das fases da ACV, a coleta de dados de inventário, definição das fronteiras e unidade funcional são pontos que devem ser explorados de maneira detalhada antes da construção do modelo. Quanto mais detalhado é o inventário, maior será a precisão de tomadas de decisão acerca dos processos analisados. Portanto, este estudo tem como objetivo elaborar um Inventário do Ciclo de Vida (ICV) da produção de biogás para geração de energia elétrica, utilizando o esterco do gado leiteiro como matéria-prima. A elaboração do ICV se deu por meio da coleta de dados locais em uma fazenda com atividades voltadas para a bovinocultura leiteira e com produção própria de biogás. Os resultados do ICV mostraram dados locais da produção diária de