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BACKGROUND: The establishment of coculture system combined with physical factors and scaffold materials and the induction of cytokines have become the focus of chondrogenic differentiation of bone marrow mesenchymal stem cells. OBJECTIVE: To observe the effect of bone morphogenetic protein 7 combined with porous tantalum on chondrogenic differentiation of bone marrow mesenchymal stem cells. METHODS: Bone marrow mesenchymal stem cells of Sprague-Dawley rats (provided by Beijing Huafukang Biology) were isolated and cultured. Group intervention: (1) in the experimental group, porous tantalum tablet was added, while in the control group, porous tantalum tablet was not added. At 5 days after culture, cell growth on the surface of porous tantalum tablet was observed by phalloidin staining. At 1,3, 5, and 7 days after culture, CCK-8 method was used to detect cell proliferation. (2) Group A was added with chondrocyte inducer; group B with chondrocyte inducer and bone morphogenetic protein 7; group C with domestic porous tantalum material and chondrocyte inducer; group D with domestic porous tantalum material and chondrocyte inducer and bone morphogenetic protein 7. At 7,14 and 21 days after culture, the levels of type II collagen, SRY type high mobility group protein and matrix metalloproteinase-13 secreted by cells in each group was detected by ELISA. Western blot assay was used to detect the expression of type II collagen, SRY type high mobility group protein and matrix metalloproteinase-13. This study was approved by the Animal Experimental Ethics Committee of North China University of Science and Technology. RESULTS AND CONCLUSION: (1) The phalloidin staining results showed that bone marrow mesenchymal stem cells grew well on and around the porous tantalum surface. (2) At 3 and 5 days after culture, the proliferation of bone marrow mesenchymal stem cells was slower in the experimental group than in the control group (P < 0.05). There was no statistical difference in cell proliferation between the two groups at 1 and 7 days (P > 0.05). (3) At 7,14 and 21 days, the expression of type II collagen and SRY high mobility group protein increased gradually among groups A, B, C and D (P < 0.05). At 7 days, the expression of matrix metalloproteinase-13 decreased gradually among groups A, B, C and D (P < 0.05). At 14 days, matrix metalloproteinase-13 secretion of matrix in group A was highest compared with that in group B, group C and group D [P < 0.05), but there was no significant difference between groups B, C and D (P > 0.05). At 21 days, there was no significant difference among groups A, B, C and D (P > 0.05). (4) Western blot assay showed that at 7,14 and 21 days after culture, the expression level of type II collagen and SRY high mobility group protein increased gradually in groups A, B, C and D (P < 0.05). At 7 days, the expression of matrix metalloproteinase-13 decreased gradually in groups A, B, C and D (P < 0.05). At 14 days, the expression of matrix metalloproteinase-13 was higher in group A than in groups C and D (P < 0.05), and higher in groups B and C than in group D (P < 0.05). At 21 days, the expression of matrix metalloproteinase-13 was higher in group A than in groups B, C and D (P < 0.05). No significant difference was found among groups B, C and D (P > 0.05). (5) The results showed that bone morphogenetic protein-7 combined with domestic porous tantalum could induce cartilage differentiation of bone marrow mesenchymal stem cells, facilitate the expression of type II collagen and SRY high mobility group protein, and inhibit the expression of matrix metalloproteinase-13. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a guided mode resonance filter with the improved structure for facile fabrication is designed; the properties of the designed filters are simulated by rigorous coupled wave analysis. It is found that the resonance wavelength and spectral linewidth are slightly increased with the increasing of the grating thickness, and seldom changed with the thickness of the grating filling factor, as the parameter error of the grating thickness and the grating filling factor are deviated from the designed value by ±10%, respectively, which are very favorable for simplifying preparation process of the GMR filter. [Copyright &y& Elsevier]

Abstract: We show that a one-dimensional grating can generally exhibit time-reversed lasing better than a uniform slab. As the effective refractive index of a grating can be controlled by adjusting the geometric parameters, the time-reversed lasing can be realized for any incident wavelength in it. Moreover, the operating frequency range of coherently perfect absorption for a grating structure is remarkably broad compared with a uniform structure. All these behaviors are demonstrated with GaAs/Air gratings illuminated around . The properties of the proposed grating imply the potential applications such as detectors, transducers, and broad band absorber. [Copyright &y& Elsevier]

The optical properties of amorphous PbZr0.52Ti0.48O3 thin films on vitreous silica and sapphire substrates by the RF magnetron sputtering method have been investigated by transmittance measurements. For a single-layer thin film on the transparent substrate, the inverse synthesis or fitting method with the six fitting parameters was given and used to calculate the optical constants such as the refractive index n, the extinction coefficient k, and the absorption coefficient α. The film thickness d, which was one of the fitting parameters, is simultaneously obtained. According to Tauc''s law, the optical transition in amorphous PbZr0.52Ti0.48O3 thin films is direct in nature. The direct band gaps of amorphous PbZr0.52Ti0.48O3 thin films on vitreous silica and sapphire substrates were found to be 3.36 and 3.25 eV, respectively. The dispersions of the refractive index in films were studied by considering a single-oscillator model. [Copyright &y& Elsevier]

In order to solve the problem of waste concrete caused by demolition of old buildings, calcined nano-attapulgite (CNAT) was added into recycled aggregate concrete (RAC) to form nano-attapulgite recycled concrete. In this paper, the experiment was divided into two stages. Stage 1: The influence of activity of nano-attapulgite (NAT) which is calcined at different temperatures was analyzed by thermo-gravimetric analysis (TGA), scanning electron microscope (SEM) and X-ray diffraction (XRD) to find out the optimal activation temperature. Stage 2: The influence of different CNAT content and replacement rate of recycled coarse aggregate (RA) on the compressive strength of RAC were investigated, and the microstructure was analyzed by SEM, XRD and Barret-Joyner-Halenda (BJH) method. The results showed that when the calcination temperature is 500 °C, NAT has the highest activity; the compressive strength of RAC decreases gradually with the increase of replacement rate of RA. When the replacement rate of RA were 30 wt% and 50 wt% and the content of CNAT was 6 wt%, the compressive strength of concrete were the largest and the compressive strength is 13.2% and 16.1% higher than that without CNAT, respectively. Because of its filling effect, surface effect and pozzolanic activity, CNAT can fill the pores and cracks in the old mortar, new mortars and the interfacial transition zone (ITZ) of RAC. The harmful pores of RAC is refined, and the concrete is more dense. Above all, CNAT can increase the macroscopic mechanical properties of RAC by improving its microstructure effectively, which provides a theoretical basis for the further study of RAC. [ABSTRACT FROM AUTHOR]