Completion of the Ablowitz-Kaup-Newell-Segur integrable coupling

Integrable couplings are associated with non-semisimple Lie algebras. In this paper, we propose a new method to generate new integrable systems through making perturbation in matrix spectral problems for integrable couplings, which is called the `completion process of integrable couplings'. As an example, the idea of construction is applied to the Ablowitz-Kaup-Newell-Segur integrable coupling. Each equation in the resulting hierarchy has a bi-Hamiltonian structure furnished by the component-trace identity

A novel bioactive PEEK/HA composite with controlled 3D interconnected HA network

Polyetheretherketone (PEEK) is a high-performance thermoplastic biomaterial which is currently used in a variety of biomedical orthopaedic applications. It has comparable tensile and compressive strength to cortical bone with favourable biocompatibility. However, natural grade PEEK-OPTIMA has shown insufficient bioactivity and limited bone integration. Bioactive PEEK composites (e.g., PEEK/calcium phosphates or Bioglass) and porous PEEK have been used to improve bone-implant interface of PEEK-based devices, but the bioactive phase distribution or porosity control is poor. In this paper, a novel method is developed to fabricate a bioactive PEEK/hydroxyapatite (PEEK/HA) composite with a unique configuration in which the HA (bioactive phase) distribution is computer-controlled within a PEEK matrix. This novel process results in complete interconnectivity of the HA network within a composite material, representing a superior advantage over alternative forms of product. The technique combines extrusion freeforming, a type of additive manufacturing (AM), and compression moulding. Compression moulding parameters, including pressure, temperature, dwelling time, and loading method together with HA microstructure were optimized by experimentation for successful biocomposite production. PEEK/HA composites with a range of HA were produced using static pressure loading to minimise air entrapment within PEEK matrix. In addition, the technique can also be employed to produce porous PEEK structures with controlled pore size and distribution

The initiation, propagation, and effect of matrix microcracks in cross-ply and related laminates

Recently, a variational mechanics approach was used to determine the thermoelastic stress state in cracked laminates. Described here is a generalization of the variational mechanics techniques to handle other cross-ply laminates, related laminates, and to account for delaminations emanating from microcrack tips. Microcracking experiments on Hercules 3501-6/AS4 carbon fiber/epoxy laminates show a staggered cracking pattern. These results can be explained by the variational mechanics analysis. The analysis of delaminations emanating from microcrack tips has resulted in predictions about the structural and material variables controlling competition between microcracking and delamination failure modes

Computer Generation of Metal Components by Simultaneous Deposition of Mould, Cores and Part

A new solid freeforming method based on co-delivery of mould powder materials and part powder materials using vibration-controlled, dry powder valves is presented in this paper. Thin layers of stainless steel powder are delivered to the forming area according to the cross-section of the CAD file to produce the component. Mould powder which has low sinterability is delivered to the non-forming areas of the same layer. All powders are delivered by computer-controlled, acoustic powder valves. The flow rate and switching of the valves provides the composition and shape control during fabrication. The stacked layers of loose powder are then sintered in a conventional furnace. The mould materials are removed after sintering. This method avoids the high thermal stress problem in selective laser sintering, avoids high capitalisation, makes use of conventional furnaces and allows for the incorporation of three dimensional function gradients. Test pieces including step wedge and Spierpinski’s cube were fabricated. Advantages, limitations and problems are discussed.Mechanical Engineerin

Generic protease detection technology for monitoring periodontal disease

Periodontal diseases are inflammatory conditions that affect the supporting tissues of teeth and can lead to destruction of the bone support and ultimately tooth loss if untreated. Progression of periodontitis is usually site specific but not uniform, and currently there are no accurate clinical methods for distinguishing sites where there is active disease progression from sites that are quiescent. Consequently, unnecessary and costly treatment of periodontal sites that are not progressing may occur. Three proteases have been identified as suitable markers for distinguishing sites with active disease progression and quiescent sites: human neutrophil elastase, cathepsin G and MMP8. Generic sensor materials for the detection of these three proteases have been developed based on thin dextran hydrogel films cross-linked with peptides. Degradation of the hydrogel films was monitored using impedance measurements. The target proteases were detected in the clinically relevant range within a time frame of 3 min. Good specificity for different proteases was achieved by choosing appropriate peptide cross-linkers.<br/