Effects of Limiting the Number of Different Cross-Sections Used in Statically Loaded Truss Sizing and Shape Optimization.

This research aims to show the effects of adding cardinality constraints to limit the number of different cross-sections used in simultaneous sizing and shape optimization of truss structures. The optimal solutions for sizing and shape optimized trusses result in a generally high, and impractical, number of different cross-sections being used. This paper presents the influence of constraining the number of different cross-sections used on the optimal results to bring the scientific results closer to the applicable results. The savings achieved using the cardinality constraint are expected to manifest in more than just the minimization of weight but in all the other aspects of truss construction, such as labor, assembly time, total weld length, surface area to be treated, transport, logistics, and so on. It is expected that the optimal weight of the structures would be greater than when not using this constraint; however, it would still be below conventionally sized structures and have the added benefits derived from the simplicity and elegance of the solution. The results of standard test examples for each different cardinality constraint value are shown and compared to the same examples using only a single cross-section on all bars and the overall optimal solution, which does not have the cardinality constraint. An additional comparison is made with results of just the sizing optimization from previously published research where authors first used the same cardinality constraint.

Electrospun and 3D printed polymeric materials for one-stage critical-size long bone defect regeneration inspired by the Masquelet technique: Recent Advances.

Critical-size long bone defects represent one of the major causes of fracture non-union and remain a significant challenge in orthopaedic surgery. Two-stage procedures such as a Masquelet technique demonstrate high level of success however their main disadvantage is the need for a second surgery, which is required to remove the non-resorbable cement spacer and to place the bone graft into the biological chamber formed by the 'induced membrane'. Recent research efforts have therefore been dedicated towards the design, fabrication and testing of resorbable implants that could mimic the biological functions of the cement spacer and the induced membrane. Amongst the various manufacturing techniques used to fabricate these implants, three-dimensional (3D) printing and electrospinning methods have gained a significant momentum due their high-level controllability, scalable processing and relatively low cost. This review aims to present recent advances in the evaluation of electrospun and 3D printed polymeric materials for critical-size, long bone defect reconstruction, emphasizing both their beneficial properties and current limitations. Furthermore, we present and discuss current state-of-the art techniques required for characterisation of the materials' physical, mechanical and biological characteristics. These represent the essential first steps towards the development of personalised implants for single-surgery, large defect reconstruction in weight-bearing bones.

Photovoltaic characterization of hybrid solar cells using surface modified TiO(2) nanoparticles and poly(3-hexyl)thiophene.

We report on the photovoltaic performance of bulk heterojunction solar cells using novel nanoparticles of 6-palmitate ascorbic acid surface modified TiO(2) as an electron acceptor embedded into the donor poly(3-hexyl)thiophene (P3HT) matrix. Devices were fabricated by using P3HT with varying amounts of red TiO(2) nanoparticles (1:1, 1:2, 1:3 w-w ratio). The devices were characterized by measuring current-voltage characteristics under simulated AM 1.5 conditions. Incident photon to current efficiency (IPCE) was spectrally resolved. The nanoscale morphology of such organic/inorganic hybrid blends was also investigated using atomic force microscopy (AFM).