Investigating the Feasibility of Processing Activated Carbon/UHMWPE Polymer Composite Using Laser Powder Bed Fusion.

Activated Carbon (AC) is widely available at a relatively low cost, has a high porosity and is commonly used as a filter material for a range of applications. However, it is a brittle and friable material. Ultra-High Molecular Weight Polyethylene (UHMWPE) polymer is a tough engineering plastic that has been used as a binder. The traditional method used in manufacturing AC/UHMWPE filters involves compressing AC/UHMWPE composite powder during heating in a mould. This process compresses the particles together and the materials undergo sintering. This process results in a low pore interconnectivity, which has a considerable impact on the filter's efficiency. Selective Laser Sintering is a laser powder bed fusion additive manufacturing technique for polymers. This has a number of advantages compared to the conventional technique and produces a porous structure with improved filtration efficiency. We propose that this is due to the greater pore interconnectivity. In this work, AC/UHMWPE powdered composites were prepared with different AC and UHMWPE ratios. The structure and properties of the AC/UHMWPE composite were investigated and characterised to assess their suitability for selective laser sintering. Particle size and morphology analysis were conducted, as well as density measurements, powder flow, thermal analysis, and crystallinity measurements. The results reveal that the addition of AC improves the UHMWPE flow. The thermal analysis results show that the intrinsic thermal properties of UHMWPE powder are not significantly affected by the introduction of activated carbon. However, thermal gravimetric analysis revealed that the onset of mass loss is considerably shifted (20 °C) to higher temperatures for the AC/UHMWPE composites, which is favourable for laser sintering. Additionally, the change in the composition ratio of untreated composite does not have a significant effect on the degree of crystallinity. Laser-sintered AC/UHMWPE parts were successfully manufactured using a commercial laser-sintering machine.

Characterisation of UHMWPE Polymer Powder for Laser Sintering.

Ultra-high molecular weight polyethylene (UHMWPE) is a thermoplastic semicrystalline polymer that has outstanding mechanical properties, low friction coefficient, excellent wear resistance, and is highly resistant to corrosive chemicals. UHMWPE is found in many applications including artificial joints and filtration. However, UHMWPE parts cannot be produced easily by traditional techniques, such as injection moulding and extrusion because of its very high melt viscosity owing to the extremely long polymer chains. Few attempts were made to process UHMWPE by additive manufacturing, particularly laser sintering. This is due to the lack of understanding of the powder properties of UHMWPE. Therefore, the aim of the powder characterisation process in this study is to gain a better understanding of the material requirements and provide a detailed insight on whether UHMWPE is a suitable material for laser sintering. The characterisation process includes powder morphological and flow characteristics, thermal behaviour and stability, and crystallinity of UHMWPE. The study reveals that the sintering behaviour of polymers is controlled by the morphology of the particles in addition to the viscous flow of UHMWPE. There are still difficulties of processing UHMWPE due to highly agglomerated structure of smaller particles with the presence of fibrils in the UHMWPE particles.

Adult-onset Still's disease with prominent polyserositis.

Adult-onset Still's disease is a systemic autoinflammatory disease the presentation of which can often mimic infection. As a consequence, there is often a delay in diagnosis. Serositis is a recognised but less common clinical feature that can result in complications including cardiac tamponade and constrictive pericarditis. We describe a case of adult-onset Still's disease without the hallmark rash or significant arthritis, presenting with polyserositis that showed a good response to initial steroid treatment and sustained remission with anakinra. An elevated procalcitonin level was due to active adult-onset Still's disease, not bacterial infection.

Clinical features of septic discitis in the UK: a retrospective case ascertainment study and review of management recommendations.

Septic discitis is a rare but important cause of spinal pain caused by intervertebral disc infection. This retrospective observational case series analysis will examine the clinical features and management of septic discitis in 23 patients and compare with a similar 2001 study. We will also review the evidence behind management recommendations to identify areas for future research. The incidence of septic discitis was 2 per 100,000 per year. Patients presented with spinal pain (96 %), fever (70 %) and raised inflammatory markers. All patients had blood cultures and 52 % had targeted microbiological analysis. Staphylococcus aureus was the most common causative organism (39 %). Treatment was most often with intravenous flucloxacillin or ceftriaxone. CT-guided sampling for culture before commencing antibiotics increased organism detection from 33 to 67 %, and organism identification reduced the antibiotic course from an average of 142 days to 77 days. An increased number of significant co-morbid conditions were associated with worse outcomes. Results broadly resembled the 2001 study. Key differences were increased use and yield of magnetic resonance imaging and computerised tomography (CT) scanning and more frequent use of intravenous antibiotics. Comparisons between the studies suggest that improvements in the consistency of management have been slow. We suggest this due to the large spectrum of disease and the lack of guidelines in the UK. It is widely recommended to perform blood cultures and CT-guided biopsies before starting antibiotics, but it is unclear how long to withhold antibiotics if cultures remain negative. Six weeks of intravenous followed by 6 weeks of oral therapy is often suggested as treatment, whereas some recommend using inflammatory markers to guide antibiotic duration. Larger studies addressing these specific questions are required to provide more definitive guidance for these clinical decisions.

An Investigation into the Scale and Impact of Self-Reported Foot Problems Associated with Systemic Lupus Erythematosus: A Study Protocol and Survey Questionnaire Development.

BACKGROUND: Systemic lupus erythematosus (SLE) can manifest with arthralgia and myalgia, and, in severe cases, disorganization of the joints and tendon rupture. Further, Raynaud's phenomenon and other circulatory problems such as vasculitis have been reported, and may be associated with loss of sensation and ulcers. Associated with impaired peripheral neurovascular function there is the potential for changes in tissue viability leading to thinning of the skin or callus formation. In addition, resistance to infections may be reduced, such as fungal infection of the skin and nails, bacterial infection associated with wounds and viral infections such as verruca. There is a dearth of evidence for the effects of SLE in the foot, the prevalence of foot problems in SLE and the impact of these on the individual. In addition, it is not known if people with SLE and foot problems have access to specialist care through foot health services. Hence, there is a need to investigate the scale of foot problems associated with SLE. In order to achieve this, a questionnaire needs to be developed in order to carry out a national survey in England. METHODS: The items required for the questionnaire were generated using a focus group, which comprised patient advisers with SLE, consultants who specialized in SLE, specialist rheumatology podiatrists and specialist rheumatology nurses. From this consensus approach to the item generation, the draft questionnaire was developed with agreement on themes, question format and overall structure. Additionally, the Manchester Pain and Disability Questionnaire was included in order to capture levels of pain and associated disability. An iterative process followed, with feedback from the focus group reducing the number of other items from 53, until the penultimate version of questionnaire was produced with 50 items. Following on from this, a process of cognitive debriefing was used with two people with SLE who were naïve to the questionnaire. Minor changes to two questions and the layout was required before a final version of the questionnaire was produced. DISCUSSION: The questionnaire will be used for a study which aims to identify the frequency of patients' self-reported foot problems, the impact of foot problems on their lives and the status of foot care provision. This will be achieved through a survey of people with SLE across six clinical sites and interviews with some people in order to explore their experience of foot problems. The results from the present study will provide the information required to inform further research. In addition, it could potentially inform the design and delivery of foot health information and services to this patient group. Copyright © 2015 John Wiley & Sons, Ltd.