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Gao G.,National Key Laboratory of Nano Micro Fabrication Technology | Gao G.,Tsinghua University | Xiang L.,Tsinghua University
Journal of Alloys and Compounds | Year: 2010

Herein we report a simple emulsion-phase route for the synthesis of honeycomb-like basic magnesium carbonate (BMC, Mg5(OH)2(CO3)4·4H 2O) micro-spheres at 80 °C. Magnesium(II) salts in water are precipitated by sodium carbonate in the presence of cetyltrimethylammonium bromide (CTAB). Scanning electron microscopy shows the obtained BMC samples are composed of a lot of micro-spheres (diameter ranging from 8 to 10 μm) which are interweaved by a lot of nano-sized thin sheets (thickness of 20-30 nm and length >1 μm). The BMC micro-spheres prepared by this approach are porous and appear to be hollow structures. The size and shape of BMC are related to the CTAB concentration and temperature. The lower concentration of CTAB resulted in the decrease of the micro-spheres sizes. When the temperature was elevated to 110 °C, hexagonal tablets (thickness of 20 nm, length of each side varies from 400 to 600 nm) can be prepared. After the calcinations for BMC at 600 °C for 2 h, BMC are almost completely converted to MgO. Transmission electron microscopy indicates that the obtained MgO samples have a poly-crystalline feature. The possible formation mechanism of BMC micro-spheres has been discussed. © 2010 Elsevier B.V. All rights reserved. Source

Dong X.,National Key Laboratory of Nano Micro Fabrication Technology | Dong X.,Peking University | Yu M.,National Key Laboratory of Nano Micro Fabrication Technology | Yu M.,Peking University | And 7 more authors.
ECS Transactions | Year: 2012

A novel process for fabricating thin silicon PIN detectors based on wafer bonding technology is proposed. Two silicon wafers, device wafer and supporting wafer, with different orientation and resistivity are bonded at high temperature. The bonded device wafer is grinded and polished. Processing this wafer, we successfully produced 100um thick PIN detectors with detecting area ranging from 1 to 113 mm2. The full depletion voltage of all the detectors is about 9V and electrical testing shows a low leakage current of around 100nA/cm3 at 11V. The energy resolution of the fabricated detectors for 5.486Mev alpha particles from Am is 0.34%-0.46%. © The Electrochemical Society. Source

Rui Y.,National Key Laboratory of Nano Micro Fabrication Technology | Rui Y.,Key Laboratory for Thin Film and Microfabrication of Minstry of Education | Rui Y.,Shanghai JiaoTong University | Liu J.,National Key Laboratory of Nano Micro Fabrication Technology | And 8 more authors.
Microsystem Technologies | Year: 2011

In implantable medical systems, low-impedance electrode-tissue interface is important for maintaining signal quality for recording and effective charge transfer for stimulation. In this paper, we propose a novel hemispherical biocompatible and flexible microelectrode arrays (MEAs) which were fabricated by the process of micro electrical mechanical system (MEMS). Compared with conventional planar microelectrodes, the interface impedance of hemispherical microelectrodes decreased due to their increased surface area. Parylene C thin film with good biocompatibility and flexibility was chemical vapor deposited as packaging material for decreasing nerve tissue damage. Pt-black coatings were electroplated by applying current pulses in H 2PtCl 6 solution on electrode sites for the further decrease of interface impedance. Moreover, the geometrical and electrical properties of these MEAs were demonstrated by using a scanning electron microscope (SEM) and an electrochemical workstation. Experimental results showed that the interface impedance decreased by about 34% compared with conventional planar microelectrodes, and significantly decreased by 84% with Pt-black coatings on electrode sites compared with those uncoated microelectrodes. © Springer-Verlag 2011. Source

Gao G.,National Key Laboratory of Nano Micro Fabrication Technology | Wu H.,National Key Laboratory of Nano Micro Fabrication Technology | He R.,National Key Laboratory of Nano Micro Fabrication Technology | Cui D.,National Key Laboratory of Nano Micro Fabrication Technology
Corrosion Science | Year: 2010

Corrosion inhibition for Cu2O nanoparticles in solution using the regulators of 1,3-dimorpholinpropylene and 1,3-diethylaminopropylene was studied by experimental and theoretical calculation methods. The inhibition mechanism of regulators was related to the arrangement of cetyltrimethylammonium (CTAB) molecules on the surface of Cu2O nanoparticles. Control of the type and amount of regulators has been demonstrated to produce well-dispersed and active Cu2O nanoparticles (∼100 nm). The oxidation temperature of Cu2O nanoparticles decreased from 297.9-404.4 °C (blank) to 232.3-334.3 °C (containing regulator). For 1,3-dimorpholinpropylene, its arc structure and active sites (C_4{double bond, long}C_5, N_2 and O_2) facilitate the formation of stable protective film over Cu2O surface. © 2010. Source

Zhang X.,National Key Laboratory of Nano Micro Fabrication Technology | Zhang X.,Shanghai JiaoTong University | Fu H.,National Key Laboratory of Nano Micro Fabrication Technology | Fu H.,Shanghai JiaoTong University | And 6 more authors.
Chinese Journal of Cancer Biotherapy | Year: 2013

Objective: To investigate the association between the expression of the ten-eleven translocation 2 (TET2) protein and the cytotoxin associated gene A (CagA) of Helicobacter pylori (Hp), and to explore the possible mechanisms of CagA in the process of gastric carcinogenesis. Methods: Real-time PCR was used to detect TET2 mRNA level in human gastric epithelial GES-1 cells and gastric cancer MGC-803 cells. Immuncytochemistry was used to detect the TET2 protein localization and expression in GES-1 and MGC-803 cells. GES-1 cells were transfected with pEGFP-CagA and a cell oxidative stress model was constructed with 200 μmol/L H202. Flow cytometry was used to analyze cell cycle and ROS in GES-1 cells. Results: The mean expression level of TET2 mRNA in GES-1 cells was lower than that in MGC-803 cells (1.00 ± 0.08 vs 1.68 ± 0.07, P < 0.05). TET2 protein expression in GES-1 cells was lower than that in MGC-803 cells (8.09 ± 3.57 vs 14.60 ±2.31,P < 0.05). Compared with the negative control pEGFP-N1 group, the mean expression level of TET2 mRNA in pEGFP-CagA-transfected GES-1 cells was increased (1.00 ± 0.04 vs 0.06 ± 0.00, P <0.05), and TET2 protein expression in pEGFP-agA-transfected GES-1 cells was also increased (10.82 ± 3.39 to 16.45 ±4.40,P <0.05), and a higher level of ROS production was observed in pEGFP-CagA-transfected GES-1 cells (69 ± 9.0 to 91 ± 16.8, P < 0.05), which significantly displayed the cell apoptosis in cycle analysis. In the cell oxidative stress model, TET2 mRNA level in H202 treated cells was higher than that in normal GES-1 cells (1.44 ± 0.02 vs 1.00 ± 0.04, P < 0.05) and TET2 protein expression level was higher than that in normal GES-1 cells (11.74 ± 4.34 to 15.72 ± 4.52, P <0.05). Conclusion: CagA factor can induce ROS accumulation and cell cycle disruption of GES-1, indicating that TET2 can be upregulated by oxidative stress and may be involved in the progress of CagA-induced carcinogenesis. Source

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