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Many aspects relating to equipment configuration affect users’ actions in a manual wheelchair, determining the overall mobility performance. Since the equipment components and configuration determine both stability and mobility efficiency, configuring the wheelchair with the most appropriate set-up for individual users’ needs is a difficult task. Several studies have shown the importance of seat/backrest assembly and the relative position of the rear wheels to the user in terms of the kinetics and kinematics of manual propulsion. More recently, new studies have brought to light evidence on the inertial properties of different wheelchair configurations. Further new studies have highlighted the handrim as a key component of wheelchair assembly, since it is the interface through which the user drives the chair. In light of the new evidence on wheelchair mechanics and propulsion kinetics and kinematics, this article presents a review of the most important aspects of wheelchair configuration that affect the users’ actions and mobility.

Biomaterial-based bone grafts have an important role in the field of bone tissue engineering. One of the most promising classes of biomaterials is collagen, including the ones from marine biodiversity (in general, called spongin (SPG)). Also, hydroxyapatite (HA) has an important role in stimulating bone metabolism. Therefore, this work investigated the association of HA and SPG composites in order to evaluate their physico-chemical and morphological characteristics and their in vitro biological performance. For this, pre-set composite disks were evaluated by means of mass loss after incubation, pH, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and "in vitro" cell viability. pH measurements showed no statistical difference between groups. Moreover, a higher mass loss was observed for HA/SPG70/30 compared to the other groups for all experimental periods. Moreover, SEM representative micrographs showed the degradation of the samples with and without immersion. FTIR analysis demonstrated the absorption peaks for poly(methyl methacrylate) (PMMA), HA, and SPG. A higher L292 cell viability for control and PMMA was observed compared to HA and HA/SPG 90/10. Also, HA/SPG 70/30 showed higher cell viability compared to HA and HA/SPG 90/10 on days 3 and 7 days of culture. Furthermore, HA showed a significant lower MC3T3 cell viability compared to control and HA/SPG 70/30 on day 3 and no significant difference was observed between the composites in the last experimental period. Based on our investigations, it can be concluded that the mentioned composites were successfully obtained, presenting improved biological properties, especially the one mimicking the composition of bone (with 70% of HA and 30% of SPG). Consequently, these data highlight the potential of the introduction of SPG into HA to improve the performance of the graft for bone regeneration applications. Further long-term studies should be carried out to provide additional information concerning the late stages of material degradation and bone healing in the presence of HA/SPG.

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Duplex stainless steels have a large number of industrial applications and may replace high cost materials, especially in chloride-containing environments like seawater in off-shore platforms due to their high mechanical properties and good corrosion resistance. The influence of the ferrite content on the performance of duplex stainless steels in these corrosive environments is not well known. For the present paper, new superduplex stainless steels with ferrite between 30 and 60% were developed and their microstructure and corrosion resistance were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in NaCl 3.5% (wt %) at 26°C and 78°C. The results obtained at 26°C showed that the pitting potential (E pitt ) is little affected by the ferrite content, but for the materials with higher ferrite it was possible to observe an increase in the repassivation potential with a decrease in the corrosion potential and passive currents due to the presence of more resistive passive films. Tests performed at 78°C indicated a high decrease in the E pitt for all the samples, independently of the ferrite percentage, although maintaining superiority in higher ferrite content. Alloys with a 55% ferrite phase content, i.e. less dependent of Ni element, present a superior performance of corrosion resistance.

Background Implants or implantable devices should integrate into the host tissue faster than fibrous capsule formation, in which the design of the interface is one of the biggest challenges. Generally, bioactive materials are not viable for load-bearing applications, so inert biomaterials are proposed. However, the surface must be modified through techniques such as coating with bioactive materials, roughness and sized pores. The aim of this research was to validate an approach for the evaluation of the tissue growth on implants of porous alumina coated with bioactive materials. Methods Porous alumina implants were coated with 45S5 Bioglass® (BG) and hydroxyapatite (HA) and implanted in rat tibiae for a period of 28 days. Ex vivo resections were performed to analyze osseointegration, along with histological analysis, Scanning Electron Microscopy with Energy Dispersive X-Ray spectroscopy (SEM-EDX) line scanning, radiography and biomechanical testing. Results Given that the process of implant integration needs with the bone tissue to be accelerated, it was then seen that BG acted to start the rapid integration, and HA acted to sustaining the process. Conclusions Inert materials coated with bioglass and HA present a potential for application as bone substitutes, preferably with pores of diameters between 100 μm and 400 μm and, restrict for smaller than 100 μm, because it prevents pores without organized tissue formation or vacant. Designed as functional gradient material, stand out for applications in bone tissue under load, where, being the porous surface responsible for the osseointegration and the inner material to bear and to transmit the loads.