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- 저자 : Afra Hadjizadeh (검색결과 2 건)
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Yalda Chehrehsaz,Kaveh Hajizadeh,Afra Hadjizadeh,Lida Moradi,Sara Mahshid 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6
Despite many advantages of titanium, such as proper mechanical properties, biocompatibility and corrosion resistance, ithas two main weaknesses; low tensile strength compared to other metallic biomaterials, and inadequate osseointegrationowing to its bioinert spontaneous surface oxide layer. Grain refinement using Equal Channel Angular Pressing (ECAP) hasbeen preferred as a desirable method to enhance low tensile strength. In addition, osseointegration could be improved byelectrochemical oxidation (anodization), resulting in titania nanotubes formation on titanium surface. The latter has beenextensively studied on commercially pure titanium (CP-Ti), and the formed nanotubes have been well characterized. However,a thorough observation on anodic nanotubes of ECAP-processed coarse-grained pure titanium (CG-Ti) is missing. In thisresearch, we aimed to investigate the surface characteristics and cytotoxicity of anodic TiO2nanotubes on ECAP-processedCP-Ti substrate compared to that of CG-Ti. The results generally showed superior use of nanotubes anodized on ECAP-edCP-Ti substrates over that of coarse-grained ones. We acquired ultrafine-grained titanium (UFG-Ti) by ECAP, and synthesizedanodic nanotube arrays on both UFG-Ti and CG-Ti at different times and voltages. We compared the resulted nanotubes’morphologies, physicochemical and biological properties, in which cell culture on anodic TiO2nanotubes of ECAP-edCP-Ti has been performed for the first time by this research. FESEM results showed relatively lower diameter and longernanotubes for UFG-Ti samples rather than CG-Ti ones. Nanotubes of both substrates were amorphous, and CG-Ti nanotubeswere more hydrophilic than UFG-Ti nanotubes. Enhanced cell viability and proliferation were achieved on ECAP-ed CP-Tianodic TiO2nanotubes.
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Fatemeh Kashani‑Asadi‑Jafari,Ahmadreza Parhizgar,Afra Hadjizadeh 한국섬유공학회 2023 Fibers and polymers Vol.24 No.2
There are different methods for producing core–shell nanofibers, one of which is the emulsion electrospinning method. Thestability of the emulsion during electrospinning is one of the most critical factors in the quality of the fibers. In this study, amagnetic-field-assisted emulsion electrospinning system was designed, built, and tested to keep the emulsion stable withoutadditives or sonication. Polycaprolactone (PCL) 10 wt. % in dichloromethane (DCM) for the shell and gelatin 2.5 wt. % inwater for the core was used. Scanning electron microscope (SEM) image of samples with different weight ratios of componentsboth with and without using the magnetic-field-assisted emulsion electrospinning system at different rotational speedswas investigated. Transition electron microscope (TEM) images of the sample with a ratio of 1/10 (gel/PCL) at differentrotational speeds were studied. The fibers were finally analyzed by Fourier transform infrared (FTIR) and tensile strengthmachine. According to the results, there was no change in the bonds in the materials after electrospinning. The designedsystem improved the fiber texture and reduced its structural problems significantly. By increasing the rotation speed of themagnet from 700 to 900 rpm, an improvement in fiber morphology and uniformity in diameter was observed. The compositionof gelatin/PCL with a ratio of 1/10 was selected as the optimal condition. The spun nanofibers in these conditionshad a uniform structure without the bead, and the presence of both polymers uniformly in the fibers was shown. Finally,the magnetic-field-assisted emulsion electrospinning system successfully held the emulsion stable during electrospinningwithout additives.
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