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In this study, improvement of near-dry machining (NDM) and its effect on tool wear in turning of AISI 4142 by carbide tool (DNMG 150608-PM) is investigated. First, the preparation of experimental setup was carried out, and then, some experiments to study the process were performed. Surface roughness was used as the criterion of finding the optimal conditions of fluid flow rate and frequency, and position and angle of nozzle. After optimization of the process, some experiments were performed to study tool life. Machining force, roughness, and tool wear were chosen as the criteria to determine the tool life. Obtained results show that the tool life in NDM is longer than that in dry machining.

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Highly flexible biocompatible materials that are both thermally conductive and electrically insulating are important for implantable and wearable bioelectronics applications. The ability to thermally process these materials into useful structures using additive manufacturing approaches opens up new opportunities for its use in bespoke structures. Here we investigate the three-dimensional (3D) printing of a medical-grade thermoplastic polyurethane (PU) elastomer, which is thermally insulating and enhance its thermal and mechanical properties through the incorporation of boron nitride (BN) as a filler. Via a simple solution compounding approach, a highly flexible and thermally conductive BN nanoparticle/ PU composite has been developed and subsequently processed into simple bio-scaffolds structures via a 3D pneumatic melt extrusion printing process. The addition of up to 20% w/w of BN to the PU significantly enhances the tensile modulus by 659%, from 1.74 to 13.2 MPa, while supporting high mechanical flexibility. The thermal conductivity of 20% w/w BN/PU composite increases by 74% with respect to the unmodified PU. The 3D printed BN/PU composite scaffolds exhibit good biocompatibility and cell attachment enhancement with L929 fibroblast cells.

The PEO-CaP coating produced on magnesium metal using an unconventional electrolyte enhanced the degradation resistance and provided excellent cytocompatibility.

et al., 2016) metal that has potential implant applications such as bone fracture fixation devices. Being an essential nutrient for human body, zinc is required for many different biological functions such as wound healing (Andrews & Gallagher-Allred, 1999), cell proliferation and DNA stabilization (MacDonald, 2000; Wu & Wu, 1987). Furthermore, zinc possesses anti-inflammatory effects and is haemocompatible and used by the human body as a hormone mediator (Beyersmann & Haase, 2001; Tapiero & Tew, 2003). Although the daily recommended dietary allowance (RDA) for zinc is limited to 8-11 mg/day, zinc overdose (10 times the RDA) has shown no adverse effects in humans (Samman & Roberts, 1987). In fact, a study has shown that high concentrations of zinc prevent conditions like osteoporosis (Luo et al., 2014). The physical and mechanical properties of metallic zinc (density = 7.14 g/cm 3 ; young's modulus = 70 GPa, and ultimate tensile strength (UTS) = 126-246 MPa; Porter, 1991) are similar to those of other metallic implant materials. For orthopaedic temporary implants for bone fracture fixation (e.g. bone plates), the implant material should possess excellent load-bearing capacity during service.