Processamento e caraterização de uma peça automóvel processado com tecnologia Mucell Vs Injeção convencional

Dissertação de mestrado integrado em Engenharia de PolímerosA indústria automóvel é marcada pela elevada competitividade e exigência na qualidade dos produtos. Estas empresas procuram métodos que lhes permitam reduzir custos, melhorar a qualidade dos produtos e a satisfação do cliente. As peças processadas por injeção com recurso a tecnologia MuCell possuem aplicações importantes para as diferentes áreas industriais. O uso da tecnologia MuCell permite utilizar diferentes materiais plásticos na produção de peças e apresenta várias vantagens como: redução do peso da peça e diminuição do tempo de ciclo, o que resulta na economia de custos e obtenção de peças mais complexas com design inovador. Este estudo decorreu em ambiente industrial na empresa MicroPlásticos. No presente estudo foram utilizados dois materiais, o Polipropileno (PP) e o poli (tereftalato de butileno) (PBT) com o objetivo de comparar a nível físico e mecânico peças processadas com injeção convencional e peças processadas com á recurso á tecnologia MuCell injetando diferente percentagens de Azoto. Ao longo do estudo verificou-se a influência da injeção de gás (Azoto), quer no tempo de ciclo de injeção, na contração e peso da peça, na resistência mecânica, bem como na observação do gás no núcleo das peças. Observou-se uma diminuição natural do peso das peças, bem como nas das propriedades mecânicas que é influenciada pelo aumento das diferentes percentagens de gás.The automotive industry is marked by high competitiveness and demand in the product quality. These companies search for methods that allow the reduction of costs, product quality improvement and client satisfaction. The parts processed by injection using MuCell technology have important applications for different industry areas. MuCell tecnology allows the use of different plastic materials in manufacture and has several advantages such as weight reduction and decreased cycle time, this results in cost savings and the ability of acquire more complex parts with innovative design. This study used Polypropylene (PP) and Polybutylene Terephthalate (PBT) to compare, at a physical and mechanical level, a part processed by injection using MuCell technology and conventional injection (without MuCell). Using MuCell technology, the material is processed with different percentages to assess the influence of the gas injection. Throughout the study it was evaluated the influence of gas injection (Nitrogen) whether on injection cycle time, mechanical resistance, shrinkage, and weight of the parts, and it was also observed the gas in the core of the parts. There was a natural decrease in the parts weight as well as in the mechanical properties due to the addition of different percentages of gas

Adição de redutores de pH e doses de glyphosate na dessecação de plantas daninhas

Two experiments were conducted to evaluate the influence from the addition of pH reducers and rates of glyphosate in the spray mix to Euphorbia heterophylla and Glycine max control. The treatments were arranged in a factorial scheme (4 x 2) + 1, randomized blocks design and four replications. Each experiment used a pH reducer (pH Fós ou Redumax), four rates of reducer (0, 50, 75 and 100% of the rate recommended), two rates of glyphosate (450 and 900 g ha-1) and an untreated check. The weed control was evaluated at 4, 6, 8, 10, 12 and 14 days after application (DAA) of treatments, in visual scale from 0 to 100% of control. In both experiments, 450 g ha-1 glyphosate, the addition of reducers in the spray mix provided greater weed control in relation to only glyphosate. There was no difference in 50, 75 and 100% of the rate recommended of reducers. With the use of adjuvant has a satisfactory control with half the recommended rate of glyphosate at 14 DAA. These results demonstrate the possibility of reduced rates of glyphosate when used these adjuvants in the spray mix.Foram conduzidos dois experimentos visando avaliar a influência de redutores de pH e doses de glyphosate associados à calda de pulverização sobre a dessecação de Euphorbia heterophylla (Amendoim–bravo) e Glycine max (Soja tiguera). Adotou-se o esquema fatorial (4 x 2) + 1, em blocos casualizados com quatro repetições. Foi utilizado um redutor comercial em cada experimento (pH Fós ou Redumax), sendo quatro doses do redutor (0, 50, 75 e 100% da dose recomendada pelo fabricante) e duas doses de glyphosate (450 e 900 g ha-1), além de uma testemunha sem aplicação. O controle das plantas daninhas foi avaliado aos 4, 6, 8, 10, 12 e 14 dias após a aplicação (DAA) dos tratamentos, em escala visual de 0 a 100% de controle. Em ambos os experimentos, na dose de 450 g ha-1 de glyphosate, a adição de redutores à calda de pulverização proporcionou maior controle das plantas daninhas, em relação ao uso de glyphosate isolado. Não houve diferenças no desempenho proporcionado pelas quantidades de 50, 75 e 100% da dose recomendada dos redutores, em todas as avaliações. Constatou-se ainda que aos 14 DAA, o uso de adjuvante permitiu um controle satisfatório com metade da dose de glyphosate recomendada. Tais resultados evidenciam a possibilidade de redução na dose de glyphosate quando forem utilizados esses adjuvantes

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.13Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved