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The forming process of ceramic green tape has heavy influence on the performance of ceramic substrate. Aimed on the application for electric package, a new technology of casting-calendering process for preparing pure Al2O3 substrate was proposed in this paper. Micro and nano multi-scale mixed ceramic powders were used as raw material. The ceramic green tape with micro-nano hierarchical structure was prepared by casting-calendering process. Finally, the pure Al2O3 ceramic substrates were sintered under 1300 to 1600, and the microstructure of the ceramic substrates prepared by casting-calendering process and casting process was compared. Experimental results showed that the pure Al2O3 ceramic substrate sintered at 1500 with no additives exhibits good densification degree of 92.5%. The thermal conductivity of the pure Al2O3 ceramic substrate prepared by casting-calendering process and sintered at 1500°C was 17.5W/(mK), which was much higher than that by tape casting process under the same sintering condition. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Suitable seed cells and selection of bioactive scaffold materials are the main research contents of bone tissue engineering. It was showed that autologous oxygen release nano bionic scaffold could promote the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The role of microRNA- 106a (miR-106a) in regulating BMSCs differentiation has not been reported. We intend to investigate the role of autologous oxygen release nano bionic scaffold composite miR-106a in inducing BMSCs constructing tissue engineering bone. MATERIALS AND METHODS: Rat BMSCs were isolated and transfected by using miR-106a scramble or miR-106a inhibitor. Healthy male Sprague-Dawly (SD) rats were randomly divided into three groups, including bone fracture group established as rat tibial fracture model, negative control group implanted by autologous oxygen release nano bionic scaffold composite miR-106a scramble BMSCs, and miR-106a inhibitor group implanted by autologous oxygen release nano bionic scaffold composite miR-106a inhibitor BMSCs. Callus growth was observed. Alkaline phosphatase (ALP) activity was detected. Bone morphogenetic protein 2 (BMP-2) expression was tested by Real-time PCR (RT-PCR) and Western blot assay. Collagen II production was determined by RT-PCR. RESULTS: Autologous oxygen release nano bionic scaffold composite BMSCs significantly increased local bone mineral density, promoted callus healing, facilitated ALP secretion, elevated collagen II expression, and up-regulated BMP-2 mRNA and protein levels compared with fracture group (p<0.05). Autologous oxygen release nano bionic scaffold composite miR-106a induced BMSCs exhibited more significant effect on bone repair (p<0.05). CONCLUSIONS: Autologous oxygen release nano bionic scaffold composite miR-106a induced BMSCs enhanced osteoblast conversion and promoted bone repair through regulating BMP-2. [ABSTRACT FROM AUTHOR]

Reducing the resistivity of low temperature grown p-Al0.09Ga0.91N layers is crucial to improving the performance of GaN-based laser diodes. In this study, growth conditions of low temperature grown p-Al0.09Ga0.91N layers are monitored and the role of C impurity is investigated systematically. On the basis of the dependence of resistivity on C concentration and the photoluminescence analysis, it is found that C impurities act as donors in p-Al0.09Ga0.91N layer, and reducing the C concentration can reduce its compensation effect on Mg acceptor. Finally, a low resistivity of 4.2 Ω·cm is achieved for the low temperature grown p-Al0.09Ga0.91N. [ABSTRACT FROM AUTHOR]

OBJECTIVE: MiR-155 has been shown to be up-regulated in hepatocellular carcinoma (HCC) patients. B-cell lymphoma-2 (Bcl-2) interacting mediator of cell death (BIM) regulates cell proliferation and apoptosis, as its down-regulation is involved in HCC onset. Transcriptional factor FoxO3a mediates BIM expression and is related to HCC pathogenesis. Bioinformatics analysis showed targeted regulation of FoxO3a by miR-155. This study aims to investigate whether miR-155 plays a role in mediating FoxO3a/BIM signal pathway and HCC occurrence. PATIENTS AND METHODS: HCC patients were collected for tumor and adjacent tissues, in which microRNA-155 (miR-155) and FoxO3a expressions were examined. In vitro cultured HCCLM3, HepG2 and L-02 cells were tested for basal apoptotic rate by flow cytometry and were compared for miR-155 and FoxO3a expression. Dual-luciferase reporter gene assay demonstrated the targeted relationship between miR-155 and FoxO3a. HCCLM3 cells were treated with miR-155 inhibitor and/or FoxO3a-pMD18-T. Cell apoptosis and proliferation were examined by using flow cytometry and MTT assays, respectively. Western blot and spectrometry assay were employed to quantify the FoxO3a, BIM expressions, and caspase activity. RESULTS: Compared to adjacent tissues, HCC tissues had significantly higher miR-155 and significantly lower FoxO3a expression (p<0.05). HCCLM3 and HepG2 cells had significantly lower FoxO3a expression and basal apoptotic rate compared to L02 cells, whilst miR-155 level was significantly higher (p<0.05). MiR-155 targeted and inhibited 3'-UTR of FoxO3a, increasing BIM expression, caspase-3, and caspase-9 activities, and enhancing cell apoptosis and weakening proliferation. CONCLUSIONS: HCC tissues elevated the miR-155 and suppressed the FoxO3a expressions. MiR-155 targeted and inhibited FoxO3a expression to suppress the BIM, depress caspase-3 and caspase-9 activities, therefore inhibiting the HCC cell apoptosis and facilitating proliferation. [ABSTRACT FROM AUTHOR]

Effect of 35BaO-35ZnO-30BO (BZB) addition on the sintering behaviors, phase evolution and microwave dielectric properties of Ti-modified BaTiNbO (BaTiNbO, BTNO) ceramics had been investigated. BZB addition effectively reduced the sintering temperature of BTNO from 1250 °C to about 900 °C. With increasing BZB addition, the crystal phase of the present ceramics changed from single phase BaTiNbO to mixing phases of BaTiNbO and BaTiNbO. And the major phase gradually became from BaTiNbO to BaTiNbO. Dielectric constant and temperature coefficient increased with the rising of BZB addition. But the Qf value gradually declined from 28000 to about 6000 GHz. The BTNO ceramics with 15% BZB addition exhibited excellent microwave dielectric properties as following: ε = 46.3, Qf = 5887 GHz and τ = 35.5 ppm/°C, which was potential of candidate materials for LTCC application. And the variation of microwave dielectric properties had been also discussed with the phase and microstructure evolution. [ABSTRACT FROM AUTHOR]