This paper presents a study on the influence of different thermo-mechanical processing (TMP) parameters on some required properties such as micro-hardness and Young`s modulus of a novel near beta alloy Ti-20.6Nb-13.6Zr-0.5V (TNZV). The TMP scheme comprises of hot working above and below beta phase, solutionizing treatment above and below beta phase coupled with different cooling rates. Factorial design of experiment is used to systematically collect data for micro-hardness and Young`s modulus. Validity of assumptions related to the collected data is checked through several diagnostic tests. The analysis of variance (ANOVA) is used to determine the significance of the main and interaction effects. Finally, optimization of the TMP process parameters is also done to achieve optimum values of the micro-hardness and Young`s modulus.
titanium alloys; biomedical applications; micro-hardness; Young\'s modulus; ANOVA
Mohsin Talib Mohammed: Department of mechanical engineering, Faculty of engineering, Kufa University, Najaf, Iraq
Zahid A. Khan and Arshad N. Siddiquee: Department of mechanical engineering, Jamia Millia Islamia (A central university), New Delhi-110025, India
Geetha M.: Centre for biomaterials science and technology, SMBS, VIT University, Vellore-632 014, India
Vascular stenting has a great attention as a treatment for coronary arteries diseases as compared with percutaneous balloon angioplasty. In-stent restenosis and thrombosis are side effects resulting from using bare metal stent (BMS). Employing platelet therapy allowed to reduce the rate of thrombosis, however, the rate of restenosis remains a major problem. In 2002, drug-eluting stents (DESs) were introduced as an effort to reduce the restenosis. The commercially available DESs continue to suffer from coating defects that might lead to a series of adverse effects. Most importantly, multiple concerns remain regarding the polymer coating integrity on metal surfaces or the relation of polymer irregularities to long-term adverse events.
drug-eluting stent; thrombosis; restenosis; coating defects; durability
Tarek M. Bedair, Youngjin Cho, Yoon Ki Joung and Dong Keun Han: Center for Biomaterials, Biomedical Research Institute, Korea
Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
Tarek M. Bedair, Yoon Ki Joung and Dong Keun Han: Department of Biomedical Engineering, Korea University of Science and Technology,113 Gwahangno,Yuseong-gu, Daejeon 305-333, Republic of Korea
Tarek M. Bedair: Chemistry Department, Faculty of Science, Minia University, El-Minia 61519, Egypt
Bang Ju Park: Department of Electronic Engineering & Institute of Gachon Fusion Technology, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi 146-701, Republic of Korea
Genetically-modified mesenchymal stem cells (GM-MSCs) have emerged as promising therapeutic tools for orthopedic degenerative diseases. GM-MSCs have been widely reported that they are able to increase bone and cartilage tissue regeneration not only by secreting transgene products such as growth factors in a long-term manner, also by inducing MSCs into tissue-specific cells. For example, MSCs modified with BMP-2 gene increased secretion of BMP-2 protein resulting in enhancement of bone regeneration, while MSCs with TGF-b gene did cartilage regeneration. In this review, we introduce several growth factors for gene delivery to MSCs and strategies for bone and cartilage tissue regeneration using GM-MSCs. Furthermore, we describe strategies for strengthening GM-MSCs to more intensively induce tissue regeneration by co-delivery system of multiple genes.
The objective of this study is to prepare an artificial extracellular matrix (ECM) for cell culture by using polymer hydrogels. The polymer used is a cytocompatible water-soluble phospholipid polymer: poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-n-butyl methacrylate-p-nitrophenyloxycarbonyl poly(ethylene oxide) methacrylate (MEONP)] (PMBN). The hydrogels are prepared using a cross-linking reaction between PMBN and diamine compounds, which can easily react to the MEONP moiety under mild conditions. The most favorable diamine is the bis(3-aminopropyl) poly(ethylene oxide) (APEO). The effects of cross-linking density and the chemical structure of cross-linking molecules on the mechanical properties of the hydrogel are evaluated. The storage modulus of the hydrogel is tailored by tuning the PMBN concentration and the MEONP/amino group ratio. The porous structure of the hydrogel networks depends not only on these parameters but also on the reaction temperature. We prepare a hydrogel with 40–50