Plasma electrolytic oxidation of magnesium and its alloys:Mechanism,properties and applications

Plasma Electrolyte Oxidation(PEO)process has increasingly been employed to improve magnesium surface properties by fabrication of an MgO-based coating.Originating from conventional anodizing procedures,this high-voltage process produces an adhesive ceramic film on the surface.The present article provides a comprehensive review around mechanisms of PEO coatings fabrication and their different properties.Due to complexity of PEO coatings formation,a complete explanation regarding fabrication mechanisms of PEO coatings has not yet been proposed;however,the most important advancements in the field of fabrication mechanisms of PEO coatings were gathered in this work.Mechanisms of PEO coatings fabrication on magnesium were reviewed considering voltage–time plots,optical spectrometry,acoustic emission spectrometry and electronic properties of the ceramic film.Afterwards,the coatings properties,affecting parameters and improvement strategies were discussed.In addition,corrosion resistance of coatings,important factors in corrosion resistance and methods for corrosion resistance improvement were considered.Tribological properties(important factors and improvement methods)of coatings were also studied.Since magnesium and its alloys are broadly used in biological applications,the biological properties of PEO coatings,important factors in their biological performance and existing methods for improvement of coatings were explained.Addition of ceramic based nanoparticles and formation of nanocomposite coatings may considerably influence properties of plasma electrolyte oxidation coatings.Nanocomposite coatings properties and nanoparticles adsorption mechanisms were included in a separate sector.Another method to improve coatings properties is formation of hybrid coatings on PEO coatings which was discussed in the end.

High plastic Zr–Cu–Fe–Al–Nb bulk metallic glasses for biomedical applications

Four Zr–Cu–Fe–Al-based bulk metallic glasses（BMGs） with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties, and corrosion resistance properties of the prepared BMGs were investigated. These BMGs exhibit moderate glass forming abilities along with superior fracture and yield strengths compared to previously reported Zr–Cu–Fe–Al BMGs. Specifically, the addition of Nb into this quaternary system remarkably increases the plastic strain to 27.5%, which is related to the high Poisson＇s ratio and low Young＇s and shear moduli. The Nb-bearing BMGs also exhibit a lower corrosion current density by about one order of magnitude and a wider passive region than 316 L steel in phosphate buffer solution（PBS, pH 7.4）. The combination of the optimized composition with high deformation ability, low Young＇s modulus, and excellent corrosion resistance properties indicates that this kind of BMG is promising for biomedical applications.

Emerging low-dimensional black phosphorus:from physical-optical properties to biomedical applications

Low-dimensional black phosphorus(BP)is a class of nanomaterial derived from layered semiconductor BP which has gained tremendous attention in a variety of fields,owing to its uncommon structural features and appealing physical properties.More surprisingly,it has addressed current biomedical obstacles due to its orthorhombic puckered honeycomb crystal structure and unique properties such as tunable direct-bandgap,high carrier mobility,and exceptional photo-responsiveness.However,few reviews have focused on the interactions of low-dimensional BP’s physical properties with its biomedical performances.Herein,we discuss the physical properties of low-dimensional BP and potential biomedical applications associated with these physical properties.Moreover,different preparation methods,surface modification techniques,and future challenges,as well as future outlooks,are presented.This comprehensive review will provide a clear understanding of the relationship between lowdimensional BP’s physical properties and biomedical performances,with the ultimate goal of better knowledge of utilizing BP.

Comparative Studies on Hydrophilic and Hydrophobic Segments Grafted Poly(vinyl chloride)

Poly（vinyl chloride）（PVC） is one of the mostly produced plastics in the world and is widely used in single-use medical devices. However, the additives that are often necessary for PVC arouse concerns of its safety, thus quests the modifications of PVC itself. In this study, poly（ethylene glycol）（PEG） and polydimethylsiloxane（PDMS） segments were grafted onto PVC backbone in similar ways, and the chemical structures of the modified PVCs were characterized by Fourier transform infrared spectra, X-ray photoelectron spectra, thermogravimetric analysis and differential scanning calorimetry. Moreover, the water contact angle, protein adsorption, platelet adhesion, cell attachment and proliferation on different material surfaces were studied and compared. It was found that both PEG and PDMS grafting yielded improvement on biocompatibility compared with bare PVC, while hydrophobic PDMS grafted PVC showed more effective on cell attachment and proliferation than that of hydrophilic PEG grafted PVC.