Chlorine Fixing Ability of Electric Arc Furnace Dust During the Thermal Degradation of Polyvinyl Chloride under Oxidative Conditions

Electric arc furnace dust (EAFD) and polyvinyl chloride (PVC) are two hazardous wastes that are accumulated world-wide at an alarming rate. Utilising these two wastes simultaneously towards a sustainable recycling loop can greatly mitigate their environmental impact. Herein, EAFD was studied as a potential emission fixator of evolved gaseous HCl generated from the thermal decomposition of PVC under different operational conditions: EAFD-PVC mass ratio, solid reactants geometry, O2 partial pressure, holding temperature, holding time and heating rate. The highest chlorine fixation percentage was calculated to be 78.9% and was obtained at an EAFD-PVC mass ratio of 1:1 (thin disks geometry), while the rest escaped in the form of HCl/Cl2. No significant variation was observed on the percentage of fixed chlorine when the thermal treatment was performed using different geometries: long cylinder, thin disks, and powder forms with a maximum difference in fixation of only 5.6% between extremities. Increasing O2 partial pressure positively affected the chlorine fixation percentage increasing it from 39.9 to 48.4% at 0 and 21 kPa partial pressures, respectively. Increasing both the holding temperature and holding time under oxidative conditions negatively affected the percentage of fixed chlorine due to oxidation of formed FeCl2 back to Fe2O3. The heating rate did not show any significant effect on the amount of fixed HCl, suggesting that the speed of chlorination reactions can be identical to or faster than the decomposition rate of PVC. Overall, EAFD is believed to be an excellent candidate for capturing HCl contained in PVC upon thermal degradation

Thermodynamic, pyrolytic, and kinetic investigation on the thermal decomposition of polyvinyl chloride in the presence of franklinite

Thermal co-treatment of Electric Arc Furnace Dust (EAFD) and polyvinyl chloride (PVC) may provide a viable route for reprocessing these hazardous materials within the circular economy. To develop and optimise a commercial treatment process, the complex mechanistic pathway resulting from the reaction of these two wastes must be understood. Franklinite (ZnFe2O4) is a major zinc containing phase in EAFD and to date, little work has been undertaken on the decomposition of PVC in its presence. Herein, we present a thermodynamic, pyrolytic, and kinetic study of PVC degradation in the presence of ZnFe2O4. It was found that, ZnFe2O4 decomposed to its associated halides. Additionally, the kinetics data confirmed the catalytic activity of ZnFe2O4, dropping the de-hydrochlorination onset temperature of PVC from 272 to 235 °C. The distribution of the activation energy with conversion suggests the presence of several competitive reactions each with a different energy barrier. In such a case, reaction channelling can take place leading to selective zinc chlorination.Moreover, since the reduction of Fe2O3 is slow at low temperatures, it is recommended to operate at a temperature as low as 235 °C which can promote the chlorination selectivity towards zinc leaving iron bearing compounds in their stable form (Fe2O3)

A thermo-kinetic investigation on the thermal degradation of polyvinyl chloride in the presence of magnetite and hematite

Electric arc furnace dust (EAFD) which is accumulated in large amounts world-wide contains hematite (Fe2O3) and significant quantities of magnetite (Fe3O4). Waste polyvinyl chloride (PVC) also poses a great environmental threat aside to accumulated EAFD. Both of these wastes have shown a great potential for their co-thermal treatment for metal extraction, thus minimising their environmental footprint. Herein, an investigation on the thermal degradation behaviour, reaction products, thermodynamics and the decomposition kinetics of PVC and its stoichiometric mixtures with Fe3O4 and Fe2O3 was conducted using non-isothermal thermogravimetric scans. The kinetic data suggests a significant increase in the average activation energy of PVC de-hydrochlorination from 122.6 ± 24.2 kJ/mol (pure PVC) to 177.0 ± 28.0 and 199.0 ± 77.0 kJ/mol when stoichiometric quantities of Fe3O4 and Fe2O3 were mixed with PVC. The inhibiting effect of both Fe3O4 and Fe2O3 on the degradation of PVC might be assigned to the capturing of emitted gaseous HCl which is known for its catalytic effect. This result suggests that EAFDs containing both Fe3O4 (in large amounts) and Fe2O3 can have an inhibiting effect on the de-hydrochlorination of PVC resulting in longer processing times or the requirement of higher processing temperatures for achieving reasonable reaction rates

Segond's fracture: a biomechanical cadaveric study using navigation

Background Segond’s fracture is a well-recognised radiological sign of an anterior cruciate ligament (ACL) tear. While previous studies evaluated the role of the anterolateral ligament (ALL) and complex injuries on rotational stability of the knee, there are no studies on the biomechanical effect of Segond’s fracture in an ACL deficient knee. The aim of this study was to evaluate the effect of a Segond’s fracture on knee rotation stability as evaluated by a navigation system in an ACL deficient knee. Materials and methods Three different conditions were tested on seven knee specimens: intact knee, ACL deficient knee and ACL deficient knee with Segond’s fracture. Static and dynamic measurements of anterior tibial translation (ATT) and axial tibial rotation (ATR) were recorded by the navigation system (2.2 OrthoPilot ACL navigation system B. Braun Aesculap, Tuttlingen, Germany). Results Static measurements at 30 showed that the mean ATT at 30 of knee flexion was 5.1 ± 2.7 mm in the ACL intact condition, 14.3 ± 3.1 mm after ACL cut (P = 0.005), and 15.2 ± 3.6 mm after Segond’s fracture (P = 0.08). The mean ATR at 30 of knee flexion was 20.7 ± 4.8 in the ACL intact condition, 26.9 ± 4.1 in the ACL deficient knee (P[0.05) and 30.9 ± 3.8 after Segond’s fracture (P = 0.005). Dynamic measurements during the pivot-shift showed that the mean ATT was 7.2 ± 2.7 mm in the intact knee, 9.1 ± 3.3 mm in the ACL deficient knee(P = 0.04) and 9.7 ± 4.3 mm in the ACL deficient knee with Segond’s fracture (P = 0.07). The mean ATR was 9.6 ± 1.8 in the intact knee, 12.3 ± 2.3 in the ACL deficient knee (P[0.05) and 19.1 ± 3.1 in the ACL deficient knee with Segond’s lesion (P = 0.016). Conclusion An isolated lesion of the ACL only affects ATT during static and dynamic measurements, while the addition of Segond’s fracture has a significant effect on ATR in both static and dynamic execution of the pivot-shift test, as evaluated with the aid of navigation

Effect of simple, targeted diet in pregnant women with metabolic risk factors on maternal and fetal outcomes (ESTEEM): study protocol for a pragmatic multicentre randomised trial

This work was supported by Bart’s Charity. The California Walnut Commission and Blue Diamond Growers donated with thanks the mixed nuts provided to the ESTEEM participants. The trial sponsor is Queen Mary University of London

Predicting global habitat suitability for stony corals on seamounts

Aim Globally, species distribution patterns in the deep sea are poorly resolved, with spatial coverage being sparse for most taxa and true absence data missing. Increasing human impacts on deep-sea ecosystems mean that reaching a better understanding of such patterns is becoming more urgent. Cold-water stony corals (Order Scleractinia) form structurally complex habitats (dense thickets or reefs) that can support a diversity of other associated fauna. Despite their widely accepted ecological importance, records of scleractinian corals on seamounts are patchy and simply not available for most of the global ocean. The objective of this paper is to model the global distribution of suitable habitat for stony corals on seamounts. Location Seamounts worldwide. Methods We compiled a database containing all accessible records of scleractinian corals on seamounts. Two modelling approaches developed for presence-only data were used to predict global habitat suitability for seamount scleractinians: maximum entropy modelling (Maxent) and environmental niche factor analysis (ENFA). We generated habitat-suitability maps and used a cross-validation process with a threshold-independent metric to evaluate the performance of the models. Results Both models performed well in cross-validation, although the Maxent method consistently outperformed ENFA. Highly suitable habitat for seamount stony corals was predicted to occur at most modelled depths in the North Atlantic, and in a circumglobal strip in the Southern Hemisphere between 20° and 50° S and shallower than around 1500 m. Seamount summits in most other regions appeared much less likely to provide suitable habitat, except for small near-surface patches. The patterns of habitat suitability largely reflect current biogeographical knowledge. Environmental variables positively associated with high predicted habitat suitability included the aragonite saturation state, and oxygen saturation and concentration. By contrast, low levels of dissolved inorganic carbon, nitrate, phosphate and silicate were associated with high predicted suitability. High correlation among variables made assessing individual drivers difficult. Main conclusions Our models predict environmental conditions likely to play a role in determining large-scale scleractinian coral distributions on seamounts, and provide a baseline scenario on a global scale. These results present a first-order hypothesis that can be tested by further sampling. Given the high vulnerability of cold-water corals to human impacts, such predictions are crucial tools in developing worldwide conservation and management strategies for seamount ecosystems. © 2009 Blackwell Publishing Ltd

Written information about individual medicines for consumers.

Medicines are the most common intervention in most health services. As with all treatments, those taking medicines need sufficient information: to enable them to take and use the medicines effectively, to understand the potential harms and benefits, and to allow them to make an informed decision about taking them. Written medicines information, such as a leaflet or provided via the Internet, is an intervention that may meet these purposes

The Role of Maternal Smoking in Effect of Fetal Growth Restriction on Poor Scholastic Achievement in Elementary School

Fetal growth restriction and maternal smoking during pregnancy are independently implicated in lowering intellectual attainment in children. We hypothesized that only reduction of fetal growth that is attributable to extrinsic causes (e.g., maternal smoking) affects intellectual development of a child. Cross-sectional survey of 3,739 students in Nova Scotia (Canada) in 2003 was linked with the perinatal database, parental interviews on socio-demographic factors and the performance on standardized tests when primarily 11–12 years of age, thereby forming a retrospective cohort. Data was analyzed using hierarchical logistic regression with correction for clustering of children within schools. The risk of poor test result among children born small-for-gestational-age (SGA) to mothers who smoked was 29.4%, higher than in any other strata of maternal smoking and fetal growth. The adjusted odds ratio among SGA children born to mothers who smoked was the only one elevated compared to children who were not growth restricted and born to mothers who did not smoke (17.0%, OR = 1.46, 95% CI 1.02, 2.09). Other perinatal, maternal and socio-demographic factors did not alter this pattern of effect modification. Heterogeneity of etiology of fetal growth restriction should be consider in studies that address examine its impact on health over life course

Relative judgement is relatively difficult: evidence against the role of relative judgement in absolute identification

A variety of processes have been put forward to explain absolute identification performance. One difference between current models of absolute identification is the extent to which the task involves accessing stored representations in long-term memory (e.g. exemplars in memory, Kent & Lamberts, Journal of Experimental Psychology: Learning Memory and Cognition, 31, 289–305, 2005) or relative judgement (comparison of the current stimulus to the stimulus on the previous trial, Stewart, Brown & Chater, Psychological Review, 112, 881–911, 2005). In two experiments we explored this by tapping into these processes. In Experiment 1 participants completed an absolute identification task using eight line lengths whereby a single stimulus was presented on each trial for identification. They also completed a matching task aimed at mirroring exemplar comparison in which eight line lengths were presented in a circular array and the task was to report which of these matched a target presented centrally. Experiment 2 was a relative judgement task and was similar to Experiment 1 except that the task was to report the difference (jump-size) between the current stimulus and that on the previous trial. The absolute identification and matching data showed clear similarities (faster and more accurate responding for stimuli near the edges of the range and similar stimulus-response confusions). In contrast, relative judgment performance was poor suggesting relative judgement is not straightforward. Moreover, performance as a function of jump-size differed considerably between the relative judgement and absolute identification tasks. Similarly, in the relative judgement task, predicting correct stimulus identification based on successful relative judgement yielded the reverse pattern of performance observed in the absolute identification task. Overall, the data suggest that relative judgement does not underlie absolute identification and that the task is more likely reliant on an exemplar comparison process