High-density poly-ethylene (HDPE) is a nonbiodegradable recyclable plastic which is widely utilized in single use packaging applications. Consequently, it constitutes a significant amount of plastic waste found in lan...High-density poly-ethylene (HDPE) is a nonbiodegradable recyclable plastic which is widely utilized in single use packaging applications. Consequently, it constitutes a significant amount of plastic waste found in landfills. From literature, it has been shown that parts produced using composites of HDPE with carbohydrate-based polymers, such as thermoplastic starch (TPS), experience mechanical degradation through hydrolytic degradation process. The possible utilization of recycled-HDPE (rHDPE) and TPS composite in nonconventional manufacturing processes such as Fused filament fabrication (FFF) has however not been explored. This study explores the potential application of rHDPE and TPS composites in FFF and optimizes the extrusion process parameters used in rHDPE-TPS filament production process. Taguchi method was utilized to analyze the extrusion process. The extrusion process parameters studied were the spooling speed, extrusion speed and the extrusion temperatures. The response variable studied was the filament diameter. In this research, the maximum TPS content achieved during filament production was 40 wt%. This filament was however challenging to use in FFF printers due to frequent nozzle clogging. Printing was therefore done with filaments that contained 0 - 30 wt% TPS. The experimental results showed that the most significant parameter in extrusion process was the spooling speed, followed by extrusion speed. Extrusion temperature had the least significant influence on the filament diameter. It was observed that increase in TPS content resulted in reduced warping and increased rate of hydrolytic degradation. Mechanical properties of printed parts were investigated and the results showed that increasing TPS content resulted in reduction in tensile strength, reduction in compression strength and increase in stiffness. The findings of this research provide valuable insights to plastic recycling industries and researchers regarding the utilization of recycled HDPE and TPS composites as substitute materials in FFF.展开更多
Objectives: The present study evaluated the effects of a combined nutritional supplement, containing omega-3 fatty acids (ω-3 FA) and different antioxidative micronutrients on nutrient status and disease activity in ...Objectives: The present study evaluated the effects of a combined nutritional supplement, containing omega-3 fatty acids (ω-3 FA) and different antioxidative micronutrients on nutrient status and disease activity in patients with rheumatoid arthritis (RA). Methods: The study was conducted as a double-blind, randomised placebo-controlled trial. A hundred patients with defined RA were allocated to the verum or placebo group. During a period of twelve weeks they were given three capsules of their specific study supplementation every day. The daily dosage of ω-3 FA was 1.35 g (thereof 900 mg eicosapentaenoic acid, EPA), 90 mg vitamin E, 600 μg vitamin A, 3 mg copper, and 75 μg selenium, or soy oil (placebo), respectively. Outcome variables were the changes in DAS 28, the number of tender and swollen joints, morning stiffness, and supply with different nutrients (e.g. serum concentration of EPA, AA and vitamin E), as well as blood lipid levels. Results: Sixty-four participants were included in this analysis: 30 receiving verum and 34 placebo. After twelve weeks of intervention, little but not significant improvements were observed in the DAS 28 and other clinical factors. Subgroup analysis revealed that the effect was much more pronounced in patients who were at least at a moderate activity of illness. Regarding the nutritional status, the serum concentration of EPA (P < 0.001), vitamin E (P < 0.01), SOD (P < 0.05), and GPx (P < 0.001) increased significantly, while AA (P < 0.001) decreased after supplementation. The concentration of triglycerides decreased significantly in the verum group (P < 0.05) but not in the placebo group. Conclusions: A twelve week add-on supplementation of a combined food supplement (ω-3 FA + antioxidants) effected modest but not significant changes in the clinical parameters in RA. Though vitamin E, SOD and GPx improved significantly, equivalent to an increased antioxidant defence. This supplementation was dedicated to enhance the nutritional status of critical nutrients in RA, especially with regard to an increased risk of cardiovascular disease in these patients.展开更多
文摘High-density poly-ethylene (HDPE) is a nonbiodegradable recyclable plastic which is widely utilized in single use packaging applications. Consequently, it constitutes a significant amount of plastic waste found in landfills. From literature, it has been shown that parts produced using composites of HDPE with carbohydrate-based polymers, such as thermoplastic starch (TPS), experience mechanical degradation through hydrolytic degradation process. The possible utilization of recycled-HDPE (rHDPE) and TPS composite in nonconventional manufacturing processes such as Fused filament fabrication (FFF) has however not been explored. This study explores the potential application of rHDPE and TPS composites in FFF and optimizes the extrusion process parameters used in rHDPE-TPS filament production process. Taguchi method was utilized to analyze the extrusion process. The extrusion process parameters studied were the spooling speed, extrusion speed and the extrusion temperatures. The response variable studied was the filament diameter. In this research, the maximum TPS content achieved during filament production was 40 wt%. This filament was however challenging to use in FFF printers due to frequent nozzle clogging. Printing was therefore done with filaments that contained 0 - 30 wt% TPS. The experimental results showed that the most significant parameter in extrusion process was the spooling speed, followed by extrusion speed. Extrusion temperature had the least significant influence on the filament diameter. It was observed that increase in TPS content resulted in reduced warping and increased rate of hydrolytic degradation. Mechanical properties of printed parts were investigated and the results showed that increasing TPS content resulted in reduction in tensile strength, reduction in compression strength and increase in stiffness. The findings of this research provide valuable insights to plastic recycling industries and researchers regarding the utilization of recycled HDPE and TPS composites as substitute materials in FFF.
文摘Objectives: The present study evaluated the effects of a combined nutritional supplement, containing omega-3 fatty acids (ω-3 FA) and different antioxidative micronutrients on nutrient status and disease activity in patients with rheumatoid arthritis (RA). Methods: The study was conducted as a double-blind, randomised placebo-controlled trial. A hundred patients with defined RA were allocated to the verum or placebo group. During a period of twelve weeks they were given three capsules of their specific study supplementation every day. The daily dosage of ω-3 FA was 1.35 g (thereof 900 mg eicosapentaenoic acid, EPA), 90 mg vitamin E, 600 μg vitamin A, 3 mg copper, and 75 μg selenium, or soy oil (placebo), respectively. Outcome variables were the changes in DAS 28, the number of tender and swollen joints, morning stiffness, and supply with different nutrients (e.g. serum concentration of EPA, AA and vitamin E), as well as blood lipid levels. Results: Sixty-four participants were included in this analysis: 30 receiving verum and 34 placebo. After twelve weeks of intervention, little but not significant improvements were observed in the DAS 28 and other clinical factors. Subgroup analysis revealed that the effect was much more pronounced in patients who were at least at a moderate activity of illness. Regarding the nutritional status, the serum concentration of EPA (P < 0.001), vitamin E (P < 0.01), SOD (P < 0.05), and GPx (P < 0.001) increased significantly, while AA (P < 0.001) decreased after supplementation. The concentration of triglycerides decreased significantly in the verum group (P < 0.05) but not in the placebo group. Conclusions: A twelve week add-on supplementation of a combined food supplement (ω-3 FA + antioxidants) effected modest but not significant changes in the clinical parameters in RA. Though vitamin E, SOD and GPx improved significantly, equivalent to an increased antioxidant defence. This supplementation was dedicated to enhance the nutritional status of critical nutrients in RA, especially with regard to an increased risk of cardiovascular disease in these patients.
