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RISS 인기검색어
- 검색키워드
- 저자 : Mehdi Razavi (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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DEVELOPMENT AND CHARACTERIZATION OF SiC-Al2O3-Al CERAMIC MATRIX NANOCOMPOSITE POWDER
MARYAM KARBASI,MEHDI RAZAVI,MINA AZADI,LOBAT TAYEBI 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.6
In this study, SiC–Al2O3–Al ceramic matrix nanocomposite powder was successfully synthesized employing mechanical alloying technique, through mechanochemical reaction among Silicon dioxide (SiO2), Carbon (C) and Aluminum (Al). For the commercial purposes, the materials (SiO2, C and Al powders) and also the method of synthesis (mechanical alloying) is considered to be cost effective for the production of SiC–Al2O3–Al nanocomposite. Addition of alumina (Al2O3) and aluminum to silicon carbide (SiC) in a nancomposite form can improve the fracture toughness, strength and fatigue crack resistance of SiC and make it a leading material for many commercial applications specially by considering the cost-effective method of production. The structural evaluation of powder particles after different milling times was conducted by X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The results showed that during ball milling the SiO2, C and Al reacted with a combustion mode producing SiC–Al2O3–Al nanocomposite after 24 h ball milling and annealing at the temperature of 920°C. The crystallite sizes of phases remained in nanometric scale after annealing at 920°C for 1 h. Based on our investigation, it was revealed that ball milling and annealing process decreases the temperature of reaction between SiO2 and C from 1500°C to 920°C.
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Reduced graphene oxide coated alginate scaffolds: potential for cardiac patch application
Nafseh Baheiraei,Mehdi Razavi,Ramin Ghahremanzadeh 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
Background Cardiovascular diseases, particularly myocardial infarction (MI), are the leading cause of death worldwide and a major contributor to disability. Cardiac tissue engineering is a promising approach for preventing functional damage or improving cardiac function after MI. We aimed to introduce a novel electroactive cardiac patch based on reduced graphene oxide-coated alginate scaffolds due to the promising functional behavior of electroactive biomaterials to regulate cell proliferation, biocompatibility, and signal transition. Methods The fabrication of novel electroactive cardiac patches based on alginate (ALG) coated with different concentrations of reduced graphene oxide (rGO) using sodium hydrosulfite is described here. The prepared scaffolds were thoroughly tested for their physicochemical properties and cytocompatibility. ALG-rGO scaffolds were also tested for their antimicrobial and antioxidant properties. Subcutaneous implantation in mice was used to evaluate the scaffolds’ ability to induce angiogenesis. Results The Young modulus of the scaffolds was increased by increasing the rGO concentration from 92 ± 4.51 kPa for ALG to 431 ± 4.89 kPa for ALG-rGO-4 (ALG coated with 0.3% w/v rGO). The scaffolds’ tensile strength trended similarly. The electrical conductivity of coated scaffolds was calculated in the semi-conductive range (~ 10− 4 S/m). Furthermore, when compared to ALG scaffolds, human umbilical vein endothelial cells (HUVECs) cultured on ALG-rGO scaffolds demonstrated improved cell viability and adhesion. Upregulation of VEGFR2 expression at both the mRNA and protein levels confirmed that rGO coating significantly boosted the angiogenic capability of ALG against HUVECs. OD620 assay and FE-SEM observation demonstrated the antibacterial properties of electroactive scaffolds against Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes. We also showed that the prepared samples possessed antioxidant activity using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay and UV–vis spectroscopy. Histological evaluations confirmed the enhanced vascularization properties of coated samples after subcutaneous implantation. Conclusion Our findings suggest that ALG-rGO is a promising scaffold for accelerating the repair of damaged heart tissue.
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