The co-pyrolysis and kinetic behaviour of extrudates produced from discard coal fines and recycled plastic binders

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Mechanical and thermal properties of extrudates produced from discarded coal fines and recycled plastics as binders

This study focuses on the extrusion of discarded coal fines from the Highveld coalfield together with recycled low-density polyethylene (LDPE) and polypropylene (PP) which are used as binders to produce agglomerates with better handling properties than the coal fines for industrial use. The bindercontentvariedbetween5 and 100 wt %. The barrels of the twins crew extruder were kept at a temperature of 220°C to melt the binders while forcing the mixture through a 10 mm die. Theextrudatescontaining10%or more binder were strong and homogeneous, while a 5% binder addition proved to be too low to producehomogeneousextrudates.Theextrudatescontaining10%LDPEand 10%PP showed compressive strengths of 17.5and 7.9 MPa before breaking, respectively. The rest of the extrudates(>10%plasticaddition)did not break but merelyflattenedas the plasticloadincreased.The compressivestrengthof all the extrudatesshowedno significantdifferenceafterbeingexposedto water.Furthermore,the extrudatesabsorbedless than5% waterafterbeingsubmergedfor 24 h. Thermogravimetricanalysisof the extrudateswas conductedundera nitrogenatmosphereup to 900°C. Threeiso-conversionalmethods,Kissinger−Akahira−Sunose,Starink,and Flynn−Wall−Ozawa, were used to determine the activation energy of the extrudates and raw materials. The lower activation energy and conversion temperatures found for the extrudates indicate a synergy between plastic and coal fines when the extrudates are pyrolyzed. Results from this study suggest that the co-extrusion of recycled plastic with coal fines will produce solid carbonaceous fuels with high hydrophobicity, heating value, and high mechanical strength compared to coal fines.-National Research Foundation (NRF) -[Coal Research Chair grant no. 86880

La galerie des oiseaux

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Topics, Skills, and Cases for an Undergraduate Musculoskeletal Curriculum in Southern Africa

Background: Most patients with orthopaedic pathology in low to middle-income countries are treated by nonspecialists. A curriculum to prepare undergraduate medical students for this duty should reflect the local pathology and skills that are required to manage patients in a resource-restricted environment. The aim of this study was to establish and prioritize a list of core orthopaedic-related knowledge topics, clinical cases, and skills that are relevant to medical students in southern Africa and areas with a similar clinical context. Methods: A modified Delphi consensus study was conducted with 3 interactive iterative rounds of communication and prioritization of items by experts from Africa, Europe, and North America. Preferred priorities were selected but were limited to 50% of all of the possible items. Percent agreement of ≥75% was defined as consensus on each of these items. Results: Most of the 43 experts who participated were orthopaedic surgeons from 7 different countries in southern Africa, but 28% were general practitioners or doctors working in primary or secondary-level facilities. Experts prioritized cases such as patients with multiple injuries, a limping child, and orthopaedic emergencies. Prioritized skills were manipulation and immobilization of dislocations and fractures. The most important knowledge topics included orthopaedic infections, the treatment of common fractures and dislocations, any red flags alerting to specialist referral, and back pain. Surgical skills for the treatment of urgent care conditions were included by some experts who saw a specific need in their clinical practice, but these were ranked lower. Conclusions: A wide geographic, academic, and expertise-specific footprint of experts informed this international consensus through their various clinical and academic circumstances. Knowledge topics, skills, and cases concerning orthopaedic trauma and infection were prioritized by the highest percent agreement. Acute primary care for fractures and dislocations ranked high. Furthermore, the diagnosis and the treatment of conditions not requiring specialist referral were prioritized. This study can inform national curricula in southern Africa and assist in the allocation of student clinical rotations

Hiv treatment as prevention: Models, data, and questions-towards evidence-based decision-making

textabstractAntiretroviral therapy (ART) for those infected with HIV can prevent onward transmission of infection, but biological efficacy alone is not enough to guide policy decisions about the role of ART in reducing HIV incidence. Epidemiology, economics, demography, statistics, biology, and mathematical modelling will be central in framing key decisions in the optimal use of ART. PLoS Medicine, with the HIV Modelling Consortium, has commissioned a set of articles that examine different aspects of HIV treatment as prevention with a forward-looking research agenda. Interlocking themes across these articles are discussed in this introduction. We hope that this article, and others in the collection, will provide a foundation upon which greater collaborations between disciplines will be formed, and will afford deeper insights into the key factors involved, to help strengthen the support for evidence-based decision-making in HIV prevention