Iranian Journal of Materials Science and Engineering

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Green synthesis refers to the synthesis of nanoparticles using plants and microorganisms. It is preferred over conventional methods as its sustainable, eco-friendly, cost effective and rapid method. The phytochemicals and enzymes present in plants and microorganisms respectively acts as the reducing and capping agent for the synthesis of nanoparticles. Phytochemicals and enzymes have the ability to reduce precursor metal ions into nanoparticles. As the conventional methods involve the use of high energy and toxic chemicals which are harmful to both environment and organisms, these synthesis methods are discouraged. Of the nanoparticles, gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have gained lots of attention owing to their multiple applications and less toxicity. In addition, various in-vitro studies have reported the antimicrobial activity of AgNPs and AuNPs against various microbes. This particular review portrays the methods of nanoparticles synthesis, components of green synthesis, mechanism of green synthesis, antimicrobial activity, other applications and various factors affecting the green synthesis of AgNPs and AuNPs.

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Biocompatible ceramics, commonly known as “bioceramics”, are an extremely versatile class of materials with a wide range of applications in modern medicine. Given the inorganic nature and physico-mechanical properties of most bioceramics, which are relatively close to the mineral phase of bone, orthopedics and dentistry are the preferred areas of usage for such biomaterials. Another clinical field where bioceramics play an important role is oculo-orbital surgery, a highly cross- and interdisciplinary medical specialty addressing to the management of injured eye orbit, with particular focus on the repair of orbital bone fractures and/or the placement of orbital implants following removal of a diseased eye. In the latter case, orbital implants are not intended for bone repair but, being placed inside the ocular cavity, have to be biointegrated in soft ocular tissues. This article reviews the state of the art of currently-used bioceramics in orbital surgery, highlighting the current limitations and the promises for the future in this field.

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In recent years, Mg- based alloys have been considered as a biodegradable biomaterial for implant applications. However, the high corrosion rate and hydrogen gas evolution in an aqueous environment are the most important challenges for these alloys. This study has focused on optimizing the biocorrosion properties of  bioalloys in Mg-Zn-Ca system, using a combined approach of thermodynamic simulations, and response surface methodology (RSM). In, Mg₂Ca and Ca_xMg_yZn_z precipitates have a significant effect on corrosion mechanisms. It is believed that, in the Mg-Zn-Ca alloy system, the Mg₂Ca secondary phase usually enhances corrosion rate with microgalvanic coupling mechanisms. The ternary phases Ca_xMg_yZn_z have less detrimental effects on corrosion resistance. To minimize harmful phases, CompuTherm’s PANDAT software was utilized for phase evolution prediction, with outputs directly validated against experimental measurements. Potentiodynamic tafel polarization experiments and long-term immersion tests were conducted to evaluate the corrosion rate. In order to design an alloy with the least detrimental phase, a statistical model (RSM) was developed based on predicted results from thermodynamic model. The results showed that the ZX31 (Mg-2.6Zn-1Ca) exhibited the highest corrosion potential (-1.6336 V_Ag/AgCl) and the lowest corrosion current density (216 µA/cm²), showing higher biocorrosion resistance compared to ZX24 (Mg-2.3Zn-4.0Ca) and ZX15 (Mg-1.3Zn-4.8Ca).