Scanning Electron Microscopy of High-Modulus Polyethylene Fibres

Scanning electron microscopy (SEM) examination of high modulus polyethylene (HMPE) fibres gives rise to a number of artifacts which are here recognized. Antistatic agents may be successfully used for the observation of the woven fibres, but only in conjunction with an intermediate metallic coating. For isolated threads superior results are obtained with the metallic coating alone. New SEM evidence suggests that the high density of surface cracks produced by plasma treatment of HMPE fibres is associated with an aging process. This can also be activated by mechanical energy or storage at room conditions

Pinealectomy affects bone mineral density and structure - an experimental study in sheep

<p>Abstract</p> <p>Background</p> <p>Osteoporosis and associated fractures are a major public health burden and there is great need for a large animal model. Melatonin, the hormone of the pineal gland, has been shown to influence bone metabolism. This study aims to evaluate whether absence of melatonin due to pinealectomy affects the bone mass, structure and remodeling in an ovine animal model.</p> <p>Methods</p> <p>Female sheep were arranged into four groups: Control, surgically ovariectomized (Ovx), surgically pinealectomized (Px) and Ovx+Px. Before and 6 months after surgery, iliac crest biopsies were harvested and structural parameters were measured using μCT. Markers of bone formation and resorption were determined. To evaluate long term changes after pinealectomy, bone mineral density (BMD) was analyzed at the distal radius at 0, 3, 9, 18 and 30 months.</p> <p>Results</p> <p>Cancellous bone volume (BV/TV) declined after 6 months by -13.3% Px and -21.5% OvxPx. The bone loss was due to increased trabecular separation as well as decreased thickness. The histomorphometric quantification and determination of collagen degradation products showed increased bone resorption following pinealectomy. Ovariectomy alone results in a transient bone loss at the distal radius followed by continuous increase to baseline levels. The bone resorption activity after pinealectomy causes a bone loss which was not transient, since a continuous decrease in BMD was observed until 30 months.</p> <p>Conclusions</p> <p>The changes after pinealectomy in sheep are indicative of bone loss. Overall, these findings suggest that the pineal gland may influence bone metabolism and that pinealectomy can be used to induce bone loss in sheep.</p

Optimization of atmospheric plasma treatment of LDPE films: Influence on adhesive properties and ageing behavior

One of the major disadvantages of low density polyethylene (LDPE) films is their poor adhesive properties. Therefore, LDPE films have been treated with atmospheric pressure air plasma in order to improve their surface properties. So as to simulate the possible conditions in an industrial process, the samples have been treated with two different sample distances (6 and 10 mm), and treatment rates between 100 and 1000 mm s-1. The different sample distances are the distance of the sample from the plasma source. The variation of the surface properties and adhesion characteristics of the films were investigated for different aging times after plasma exposure (up to 21 days) using contact angle measurement, atomic force microscopy, weight loss measurements and shear test. Results show that the treatment increases the polar component () and these changes improve adhesive properties of the material. 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M., Kim, M. S., … Khang, G. (2007). Correlation of proliferation, morphology and biological responses of fibroblasts on LDPE with different surface wettability. Journal of Biomaterials Science, Polymer Edition, 18(5), 609-622. doi:10.1163/156856207780852514Borcia, G., Anderson, C. A., & Brown, N. M. D. (2004). The surface oxidation of selected polymers using an atmospheric pressure air dielectric barrier discharge. Part I. Applied Surface Science, 221(1-4), 203-214. doi:10.1016/s0169-4332(03)00879-1Pascual, M., Calvo, O., Sanchez-Nácher, L., Bonet, M. A., Garcia-Sanoguera, D., & Balart, R. (2009). Optimization of adhesive joints of low density polyethylene (LDPE) composite laminates with polyolefin foam using corona discharge plasma. Journal of Applied Polymer Science, 114(5), 2971-2977. doi:10.1002/app.30906Encinas, N., Díaz-Benito, B., Abenojar, J., & Martínez, M. A. (2010). Extreme durability of wettability changes on polyolefin surfaces by atmospheric pressure plasma torch. 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Libraries and open society; Popper, Soros and digital information

This paper examines the role of libraries and information services, in promoting the ‘open society’ espoused by Karl Popper and George Soros. After a brief discussion of the nature of an ‘open society’, the paper covers the role played by provision of knowledge and information, of new technology, particularly the Internet, and of critical thinking and digital literacy in the development of this form of society. Conclusions are drawn for the role of libraries and librarians, with seven general principles suggested: • provision of access to a wide variety of sources without ‘negative’ restriction or censorship • provision of ‘positive’ guidance on sources, based on open and objective criteria • a recognition that a ‘free flow of information’ though essential, is not sufficient • a recognition that provision of factual information, while valuable, is not enough • a need for a specific concern for the effect of new ICTs, and the Internet in particular • promotion of critical thinking and digital literacy • a need for explicit consideration of the ethical values of librarie

Hydrostatically extruded HAPEXTM

Hydroxyapatite reinforced high density polyethylene composite (HAPEXTM) has been developed for bone substitution. To improve its mechanical properties, HAPEXTM was hydrostatically extruded at different extrusion ratios after compression moulding. Substantial increases in the tensile and flexural properties of both unfilled polyethylene and HAPEXTM were achieved. It was evident that the higher the extrusion ratio, the stiffer and the stronger the extruded rods. The ductility of HAPEXTM was also significantly enhanced by hydrostatic extrusion. Hydrostatically extruded HAPEXTM possesses mechanical properties that are within the bounds for human cortical bone, which indicates its potential for load-bearing skeletal implant applications.link_to_subscribed_fulltex

Hydrostatic extrusion of hydroxyapatite polyethylene composite

A 40 vol % hydroxyapatite high density polyethylene composite (HAPEX) was prepared by a Betol twin screw compounding extruder. Tensile tests revealed a small decrease in tensile strength due to hydroxyapatite reinforcement. Hydrostatic extrusion countered this effect, however, and enhanced mechanical properties to within the bounds for human cortical bone but with a significantly increased ductility and toughness.link_to_subscribed_fulltex