214 research outputs found

    Biodegradability standards for carrier bags and plastic films in aquatic environments: a critical review

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    Plastic litter is encountered in aquatic ecosystems across the globe, including polar environments and the deep sea. To mitigate the adverse societal and ecological impacts of this waste, there has been debate on whether ‘biodegradable’ materials should be granted exemptions from plastic bag bans and levies. However, great care must be exercised when attempting to define this term, due to the broad and complex range of physical and chemical conditions encountered within natural ecosystems. Here, we review existing international industry standards and regional test methods for evaluating the biodegradability of plastics within aquatic environments (wastewater, unmanaged freshwater and marine habitats). We argue that current standards and test methods are insufficient in their ability to realistically predict the biodegradability of carrier bags in these environments, due to several shortcomings in experimental procedures and a paucity of information in the scientific literature. Moreover, existing biodegradability standards and test methods for aquatic environments do not involve toxicity testing or account for the potentially adverse ecological impacts of carrier bags, plastic additives, polymer degradation products or small (microscopic) plastic particles that can arise via fragmentation. Successfully addressing these knowledge gaps is a key requirement for developing new biodegradability standard(s) for lightweight carrier bags

    Fatigue and microgap behaviour of a three-unit implant-fixed dental prosthesis combining conventional and dynamic abutments

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    This is an in vitro study composed by a fatigue test followed by an optical microscopy analysis. Dynamic abutments concept, recently introduced on screw-retained implant dental prosthesis, consists on the screw channel customisation according to the individual needs of each rehabilitation. Geometry and tightening torque differences advise the assessment of their mechanical performance. Clarify whether the combination of dynamic and conventional abutments in a three-unit implant-fixed prosthesis has detrimental effects either on the mechanical performance under cyclic loading or on the implant-abutment microgap dimensions. The fatigue test was performed in agreement with the ISO standard 14801. Then on the samples that resisted 5 million cycles, the implant-abutment microgap was measured on dynamic and conventional abutments using optical microscopy. Two unloaded samples were used as control group. The samples supported a load of 1050 N. The implant-abutment microgap measurement did not show statistically significant differences (p=.086) between loaded and unloaded groups, but the loaded conventional abutments showed a significant lower implant-abutment microgap (p=.05) than the loaded dynamic abutments. The combination of conventional and dynamic abutments do not seem to produce a decrease in fatigue resistance to a level below the mastication forces or an increase in the joint dimensions.The study was supported in part by SciTech - Science and Technology for Competitive and Sustainable Industries, and the R&D project was cofinanced by the North Portugal Regional Operational Program ("NORTE2020") and the European Regional Development Fund (FEDER)

    Development of DFSI using Fuzzy Logic to Analyze Risk Levels of Driving Activity

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    The objective of this study is to develop a Driving Fatigue Strain Index using fuzzy logic to analyze the risk levels of driving activity among road users. Driving fatigue is always related to the driving activity and has been identified as one of the vital contributors to the road accidents and fatalities in Malaysia. Therefore, the present paper introduces the use of fuzzy logic for the development of strain index to provide the systematic analysis and propose an appropriate solution in minimizing the number of road accidents and fatalities. The development of strain index is based on the six risk factors associated with driving fatigue; muscle activity, heart rate, hand grip pressure force, seat pressure distribution, whole-body vibration, and driving duration. The data is collected for all the risk factors and consequently, the three conditions or risk levels are defined as “safe”, “slightly unsafe”, and “unsafe”. A membership function is defined for each fuzzy conditions. IF-THEN rules were used to define the input and output variables which correspond to physical measures. This index is a reliable advisory tool for providing analysis and solutions to driving fatigue problem, which constitutes the first effort toward the minimization of road accidents and fatalities

    Different Behavior of Enteric Bacteria and Viruses in Clay and Sandy Soils after Biofertilization with Swine Digestate

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    Enteric pathogens from biofertilizer can accumulate in the soil, subsequently contaminating water and crops. We evaluated the survival, percolation and leaching of model enteric pathogens in clay and sandy soils after biofertilization with swine digestate: PhiX-174, mengovirus (vMC0), Salmonella enterica Typhimurium and Escherichia coli O157:H7 were used as biomarkers. The survival of vMC0 and PhiX-174 in clay soil was significantly lower than in sandy soil (ıPT90 values of 10.520 0.600 vs. 21.270 1.100 and 12.040 0.010 vs. 43.470 1.300, respectively) and PhiX- 174 showed faster percolation and leaching in sandy soil than clay soil (ıPT90 values of 0.46 and 2.43, respectively). S. enterica Typhimurium was percolated and inactivated more slowly than E. coli O157:H7 (ıPT90 values of 9.340 0.200 vs. 6.620 0.500 and 11.900 0.900 vs. 10.750 0.900 in clay and sandy soils, respectively), such that E. coli O157:H7 was transferred more quickly to the deeper layers of both soils evaluated (percolation). Our findings suggest that E. coli O157:H7 may serve as a useful microbial biomarker of depth contamination and leaching in clay and sandy soil and that bacteriophage could be used as an indicator of enteric pathogen persistence. Our study contributes to development of predictive models for enteric pathogen behavior in soils, and for potential water and food contamination associated with biofertilization, useful for risk management and mitigation in swine digestate recycling.RTA2014-00024-C04-01 from the Spanish Ministry of Economy and Innovation and the Brazilian CNPq Project number 472804/2013-8, an dby CAPES/PNPD and CAPES/PDSE

    Evaluation of the effectiveness and cost-effectiveness of lightweight fibreglass heel casts in the management of ulcers of the heel in diabetes: a randomised controlled trial

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    Background Ulcers of the foot in people with diabetes mellitus are slow to heal and result in considerable cost and patient suffering. The prognosis is worst for ulcers of the heel. Objective To assess both the clinical effectiveness and the cost-effectiveness of lightweight fibreglass casts in the management of heel ulcers. Design A pragmatic, multicentre, parallel, observer-blinded randomised controlled trial. A central randomisation centre used a computer-generated random number sequence to allocate participants to groups. Setting Thirty-five specialist diabetic foot secondary care centres in the UK. Those recruited were aged ≥ 18 years and had diabetes mellitus complicated by ulcers of the heel of grades 2–4 on the National Pressure Ulcer Advisory Panel and European Pressure Ulcer Advisory Panel scale. Participants In total, 509 participants [68% male, 15% with type 1 diabetes mellitus, mean age 67.5 years (standard deviation 12.4 years)] were randomised 1 : 1 to the intervention (n = 256) or the control (n = 253) arm. The primary outcome data were available for 425 participants (212 from the intervention arm and 213 from the control arm) and exceeded the total required; attrition was 16.5%. The median ulcer area at baseline was 275 mm2 [interquartile range (IQR) 104–683 mm2] in the intervention group and 206 mm2 (IQR 77–649 mm2) in the control group. There were no differences between the two groups at baseline in any parameter, neither in relation to the participant nor in relation to their ulcer. Interventions The intervention group received usual care supplemented by the addition of an individually moulded, lightweight, fibreglass heel cast. The control group received usual care alone. The intervention phase continued either until the participant’s ulcer had healed (maintained for 28 days) or for 24 weeks, whichever occurred first. During this intervention phase, the participants were reviewed every 2 weeks, and the fibreglass casts were replaced when they were no longer usable. Main outcome measures The primary outcome measure was ulcer healing (confirmed by a blinded observer and maintained for 4 weeks) within 24 weeks. Other outcome measures included the time taken for the ulcer to heal, the percentage reduction in the cross-sectional area, the reduction in local pain, amputation, survival and health economic analysis. The study was powered to define a difference in healing of 15% (55% intervention vs. 40% control). Results Forty-four per cent (n = 94) of the intervention group healed within 24 weeks, compared with 37% (n = 80) of the control participants (odds ratio 1.42, 95% confidence interval 0.95 to 2.14; p = 0.088), using an intention-to-treat analysis. No differences were observed between the two groups for any secondary outcome. Limitations Although the component items of care were standardised, because this was a pragmatic trial, usual care was not uniform. There was some evidence of a small excess of adverse events in the intervention group; however, non-blinded observers documented these events. There was no excess of adverse device effects. Conclusions There may be a small increase in healing with the use of a heel cast, but the estimate was not sufficiently precise to provide strong evidence of an effect. There was no evidence of any subgroup in which the intervention appeared to be particularly effective. A health economic analysis suggested that it is unlikely that the intervention represents good value for money. The provision of a lightweight heel cast may be of benefit to some individuals, but we have found no evidence to justify the routine adoption of this in clinical practice. Future work It is unlikely that further study of this intervention will have an impact on usual clinical care, and so future efforts should be directed towards other interventions designed to improve the healing of ulcers in this population

    Comparison of the environmental assessment of an identical office building with national methods

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    The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The ?be2226? office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts.IEA -International Association for the Evaluation of Educational Achievement(Slovenia
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