Nanocomposite membranes based on nano-sized SiO 2 particles with chemical coupling to the polymer matrix are described with special emphasis on gas permeation properties. In this paper, poly(ether imide) with reactive imide rings in the backbone was used as the matrix to which the SiO 2 particles were chemically bonded via an amine-containing silane coupling agent. Four types of nanocomposite membranes were prepared by solution casting and melt processing and characterized in terms of morphology and void volume formed due to adding SiO 2 particles. The relative gas permeability of the nanocomposite with chemical coupling to matrix was decreased by the presence of SiO 2 particles. Diffusion coefficients computed from time lag data also decreased with SiO 2 content. However, solubility coefficients computed by dividing the experimental permeability by the diffusivity obtained from the observed time lag increased with SiO 2 content contrary to simple composite theory. These permeation properties are discussed in terms of the void volume fraction estimated by density observations. In addition, TEM and SEM were used to explore the morphology of these nanocomposite membranes.
Introduction
To investigate the efficacy of the transplantation of autologous bone marrow-derived mesenchymal stem cells (BMSCs) under arthroscopy with microfracture (MFX) compared with microfracture alone.
Methods
Eleven patients with a symptomatic articular cartilage defect of the knee were included in the study. They were randomized to receive BMSCs with MFX (cell-T group, n=7) or MFX alone (control group, n=4). Clinical results were evaluated using International Knee Documentation committee (IKDC) knee evaluation questionnaires and the Knee Injury and Osteoarthritis Outcome Score (KOOS) before and 48 weeks after surgery. Quantitative and qualitative assessments of repair tissue were carried out at 48 weeks by T2 mapping of magnetic resonance images (MRIs) and the magnetic resonance observation of cartilage repair tissue (MOCART) scoring system with follow-up MRI.
Results
No significant differences between preoperative and postoperative IKDC and KOOS were observed in the cell-T or control group. However, forty-eight weeks after surgery, the cell-T group showed a trend for a greater KOOS QOL score compared with the control group (79.4 vs. 39.1, respectively; P=0.07). The T2 value did not differ significantly between the two groups, but the mean MOCART score was significantly higher in the cell-T group than in the control group (P=0.02).
Conclusions
Compared with MFX alone, BMSC transplantation with MFX resulted in better postoperative healing of the cartilage and subchondral bone as determined by the MOCART score. Clinically, BMSC transplantation with MFX gave a higher KOOS QOL score after 48 weeks.
Smaller meniscal width and greater severity of meniscal extrusion correlated with knee joint degeneration. An anterocentral shift on preoperative MRI was a risk factor for degenerative changes and smaller residual meniscal width.
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