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多孔硅结构电镜图像的数字处理 被引量:1
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作者 李格 《江苏石油化工学院学报》 2002年第4期39-41,共3页
多孔硅在光电子和传感器领域是一种具有重要应用价值的材料,多孔硅网络结构的形状纹理直接影响其光学和热学性能。运用数字图像处理分析方法对多孔硅结构电子显微镜图像(SEM)进行特征提取,为多孔化率的测定提供了重要依据。
关键词 多孔硅结构 电镜图像 数字处理 图像处理 纹理分析 多孔化率
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Fabrication and flexural strength of porous Si3N4 ceramics with Li2CO3 and Y2O3 as sintering additives 被引量:6
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作者 HU Hai-long LUO Shi-bin 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第9期2548-2556,共9页
By employing sintering additives of Li2CO3 and Y2O3,porous Si3N4 ceramics are prepared after experiencing the processes of sintering and post-vacuum heat treatment at 1680 and 1550°C,respectively.The experimental... By employing sintering additives of Li2CO3 and Y2O3,porous Si3N4 ceramics are prepared after experiencing the processes of sintering and post-vacuum heat treatment at 1680 and 1550°C,respectively.The experimental results demonstrate the completed phase transformation fromαtoβ-Si3N4 in Si3N4 ceramic samples with a amount of 1.60 wt%Li2CO3(0.65 wt%Li2O)and 0.33 wt%Y2O3 additives.The as-synthesized porous Si3N4 ceramics exhibit high flexural strength((126.7±2.7)MPa)and high open porosity of 50.4%at elevated temperature(1200°C).These results are attributed to the significant role of added Li2CO3 as sintering additive,where the volatilization of intergranular glassy phase occurs during sintering process.Therefore,porous Si3N4 ceramics with desired mechanical property prepared by altering the addition of sintering additives demonstrate their great potential as a promising candidate for high temperature applications. 展开更多
关键词 sintering additive flexural strength POROSITY glassy phase Si3N4 porous ceramics
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Gas Diffusion in Bi-disperse Porous Catalyst Pellets
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作者 刘秀凤 张宝泉 LIN Y.S 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2005年第4期471-476,共6页
A flux equation of diffusion for bi-disperse porous catalyst pellets was proposed by modifying the previously developed model equation over fractal trajectories. The proposed fractal model equation considered the same... A flux equation of diffusion for bi-disperse porous catalyst pellets was proposed by modifying the previously developed model equation over fractal trajectories. The proposed fractal model equation considered the same tortuous degree for both micro-and macro-pores. The experimental data of diffusion over a bi-disperse Ni/gamma-alumina pellet were obtained with a standard Wicke-Kallenbach diffusion cell for both carbon monoxide- ethylene and carbon dioxide-ethylene binary mixtures. The fitting between experimental results and the fractal model equation leads to a fractal dimension of 1.11. The prediction of diffusion flux over the bi-disperse Ni/gamma- alumina pellet by the proposed fractal model equation is much better than the traditional tortuosity-based model equation by comparison with the measured flux through the pellet. 展开更多
关键词 FRACTAL diffusion porous media CATALYST
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High hydrosilylation efficiency of porous silicon SiHx species produced by Pt-assisted chemical etching for biochip fabrication 被引量:1
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作者 XIAO MinYu HAN HuanMei XIAO ShouJun 《Science China Chemistry》 SCIE EI CAS 2013年第8期1152-1163,共12页
Porous silicon (PSi) prepared from Pt metal-assisted chemical etching (MACE) was demonstrated to possess higher hydrosi- lylation efficiency (-57%) than anodized PSi (-11%) by surface reaction with co-undeceny... Porous silicon (PSi) prepared from Pt metal-assisted chemical etching (MACE) was demonstrated to possess higher hydrosi- lylation efficiency (-57%) than anodized PSi (-11%) by surface reaction with co-undecenyl alcohol (UO). Deconvolution of the SiHx (x = 1-3) stretching bands revealed the abundance of SiH2 species on MaCE PSi was 53%, -10% higher than on ano- dized samples, while both of Sill1 and Sill3 were -5% lower correspondently on MaCE PSi than on anodized samples. The surface SiHx abundances were suggested to account for the higher hydrosilylation efficiency on MaCE PSi. Optimization of Pt-assisted chemical etching parameters suggested a 7-15 nm thick Pt-coating and an etching time of 3-10 min for biochip ap- plications. Scanning electron microscopy images revealed that an isotropic top meso-porous layer was beneficial for hydrosi- lylation and long-term durability under ambient conditions. To end, an example of histidine-tagged protein immobilization and microarray was illustrated. Combining the materials' property, surface chemistry, and micro-fabrication technology together, we envision that silicon based biochip applications have a prosperous future. 展开更多
关键词 metal-assisted chemical etching porous silicon surface chemistry HYDROSILYLATION BIOCHIP
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Pd embedded in porous carbon (Pd@CMK-3) as an active catalyst for Suzuki reactions: Accelerating mass transfer to enhance the reaction rate 被引量:7
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作者 Zhencai Wang Wei Chen +6 位作者 Zhenliang Han Jie Zhu Na Lu Yun Yang Dekun Ma Ying Chen Shaoming Huang 《Nano Research》 SCIE EI CAS CSCD 2014年第9期1254-1262,共9页
Heterogeneous catalysts are promising candidates for use in organic reactions due to their advantages in separation, recovery, and environment compatibility. In this work, an active porous catalyst denoted as Pd embed... Heterogeneous catalysts are promising candidates for use in organic reactions due to their advantages in separation, recovery, and environment compatibility. In this work, an active porous catalyst denoted as Pd embedded in porous carbon (Pd@CMK-3) has been prepared by a strategy involving immersion, ammonia- hydrolysis, and heating procedures. Detailed characterization of the catalyst revealed that Pd(0) and Pd(I1) species co-exist and were embedded in the matrix of the porous carbon (CMK-3). The as-prepared catalyst has shown high activity toward Suzuki reactions. Importantly, if the reaction mixture was homogenized by two minutes of ultrasonication rather than magnetic stirring before heating, the resistance to mass transfer in the pore channels was significantly reduced. As a result, the reactions proceeded more rapidly and a four-fold increase in the turnover frequency (TOF) could be obtained. When the ultrasonication was employed throughout the entire reaction process, the conversion could also exceed 90% even without the protection of inert gas, and although the reaction temperature was lowered to 30 ℃. This work provides a method for fabricating highly active porous carbon encapsulated Pd catalysts for Suzuki reactions and proves that the problem of mass transfer in porous catalysts can be conveniently resolved by ultrasonication without any chemical modification being necessary. 展开更多
关键词 PD CMK-3 porous catalyst Suzuki reactions mass transfer
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Improved conversion efficiency of dye-sensitized solar cells by using novel complex nanostructured TiO_2 electrodes
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作者 ZHANG TianShu LIU LiFeng +2 位作者 YANG Fei WANG Yi KANG JinFeng 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第1期115-119,共5页
A novel complex nanostructured TiO2 electrode and fabrication process were proposed and demonstrated to improve the performance of dye-sensitized solar cells(DSSCs).In the proposed process,a nanoporous TiO2 layer was ... A novel complex nanostructured TiO2 electrode and fabrication process were proposed and demonstrated to improve the performance of dye-sensitized solar cells(DSSCs).In the proposed process,a nanoporous TiO2 layer was firstly fabricated on the FTO(fluorine-doped tin oxide) conducting substrate by an anodization process,then a nanoparticulate TiO2 film was deposited on the nanoporous TiO2 layer by the screen printed method to form the complex nanostructured TiO2 electrode.The experiments demonstrated that the nanoporous TiO layer can enhance the light scattering,decrease the contact resistance between TiO2 electrode and FTO,and suppress the recombination of I3-ion with the injected electrons of FTO.The process variables are crucial to obtain the optimized performance of DSSCs.By adopting the optimized process,improved conversion efficiency of DSSCs was achieved at AM 1.5 sunlight. 展开更多
关键词 dye-sensitized solar cells conversion efficiency nanoporous TiO2 electrode anodization
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