In order to investigate the formation mechanisms of the layered growth phenomena in diffusion couples with spinodal decomposition,a phase field model combined with elastic strain field was employed.Microstructure evol...In order to investigate the formation mechanisms of the layered growth phenomena in diffusion couples with spinodal decomposition,a phase field model combined with elastic strain field was employed.Microstructure evolutions of diffusion couple with spinodal decomposition in binary alloys were numerically simulated by considering concentration fluctuation and elastic anisotropy.The simulation results indicate that the number of the periodical layers decreases with the increase of initial concentration fluctuation,even with large elastic anisotropy.The growth of layered microstructures can be attributed to the directional diffusion enhanced by initially discontinuous chemical potential at the interface.展开更多
A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performanc...A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions （in complete darkness and presence of light）, and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30 h. Changes in chemical oxygen demand, and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness （D-MFC） with a stable open circuit voltage of 700 mV, presence of light led to growth of other species, and consecutively low and unsteady open circuit voltage. Although the performance of the MFC subjected to light （L-MFC） was quite low and unsteady in dynamic state （internal resistance = 100 Ω, power density = 5.15 W.m-3）. it reached power density of 9.2 W.m-3 which was close to performance of D-MFC （internal resistance = 50 d, power density = 10.3 W.m-3）. Evaluated only for D-MFC, the coulombic efficiency observed in batch mode （30%） was quite higher than the maximum acquired in continuous mode （9.6%） even at the highest hydraulic retention time. In this study, changes in phosphate and different types of nitrogen existing in dairy wastewater were investigated for the first time. At hydraulic retention time of 8 h, the orthophosphate concentration in effluent was 84% higher compared to influent. Total nitrogen and total Kjeldahl nitrogen were reduced 70% and 99% respectively at hydraulic retention time of 30 h, while nitrate and nitrite concentrations increased. The microbial electrolysis cell （MEC）, revamped from D-MEC, showed the maximum gas production of 0.2 m3 H2·m-3·d-1 at 700 mV applied voltage.展开更多
We present a scheme of preparing the tripartite W state among three cavitymodes of radiation field inside high-Q superconducting cavities. Our scheme is based on theinteraction of a four-level atom with the cavity Gel...We present a scheme of preparing the tripartite W state among three cavitymodes of radiation field inside high-Q superconducting cavities. Our scheme is based on theinteraction of a four-level atom with the cavity Geld for precalculated interaction times with everymode.展开更多
When two-dimensional graphene is exfoliated from three-dimensional highly oriented pyrolytic graphite （HOPG）, ripples or corrugations always exist due to the intrinsic thermal fluctuations. Surface-grown graphenes a...When two-dimensional graphene is exfoliated from three-dimensional highly oriented pyrolytic graphite （HOPG）, ripples or corrugations always exist due to the intrinsic thermal fluctuations. Surface-grown graphenes also exhibit wrinkles, which are larger in dimension and are thought to be caused by the difference in thermal expansion coefficients between graphene and the underlying substrate in the cooling process after high temperature growth. For further characterization and applications, it is necessary to transfer the surface-grown graphenes onto dielectric substrates, and other wrinkles are generated during this process. Here, we focus on the wrinkles of transferred graphene and demonstrate that the surface morphology of the growth substrate is the origin of the new wrinkles which arise in the surface-to-surface transfer process; we call these morphology- induced wrinkles. Based on a careful statistical analysis of thousands of atomic force microscopy （AFM） topographic data, we have concluded that these wrinkles on transferred few-layer graphene （typically 1-3 layers） are determined by both the growth substrate morphology and the transfer process. Depending on the transfer medium and conditions, most of the wrinkles can be either released or preserved. Our work suggests a new route for graphene engineering involving structuring the growth substrate and tailoring the transfer process.展开更多
基金Project(2017YFB0702401) supported by the National Key R&D Program of ChinaProject(51301146) supported by the National Natural Science Foundation of ChinaProjects(20720170038,20720170048) supported by the Fundamental Research Funds for the Central Universities,China
文摘In order to investigate the formation mechanisms of the layered growth phenomena in diffusion couples with spinodal decomposition,a phase field model combined with elastic strain field was employed.Microstructure evolutions of diffusion couple with spinodal decomposition in binary alloys were numerically simulated by considering concentration fluctuation and elastic anisotropy.The simulation results indicate that the number of the periodical layers decreases with the increase of initial concentration fluctuation,even with large elastic anisotropy.The growth of layered microstructures can be attributed to the directional diffusion enhanced by initially discontinuous chemical potential at the interface.
基金supported by Sharif University of Technology,Vice President for Research Grant G930111
文摘A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell （MFC）, was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions （in complete darkness and presence of light）, and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30 h. Changes in chemical oxygen demand, and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness （D-MFC） with a stable open circuit voltage of 700 mV, presence of light led to growth of other species, and consecutively low and unsteady open circuit voltage. Although the performance of the MFC subjected to light （L-MFC） was quite low and unsteady in dynamic state （internal resistance = 100 Ω, power density = 5.15 W.m-3）. it reached power density of 9.2 W.m-3 which was close to performance of D-MFC （internal resistance = 50 d, power density = 10.3 W.m-3）. Evaluated only for D-MFC, the coulombic efficiency observed in batch mode （30%） was quite higher than the maximum acquired in continuous mode （9.6%） even at the highest hydraulic retention time. In this study, changes in phosphate and different types of nitrogen existing in dairy wastewater were investigated for the first time. At hydraulic retention time of 8 h, the orthophosphate concentration in effluent was 84% higher compared to influent. Total nitrogen and total Kjeldahl nitrogen were reduced 70% and 99% respectively at hydraulic retention time of 30 h, while nitrate and nitrite concentrations increased. The microbial electrolysis cell （MEC）, revamped from D-MEC, showed the maximum gas production of 0.2 m3 H2·m-3·d-1 at 700 mV applied voltage.
文摘We present a scheme of preparing the tripartite W state among three cavitymodes of radiation field inside high-Q superconducting cavities. Our scheme is based on theinteraction of a four-level atom with the cavity Geld for precalculated interaction times with everymode.
基金the on-going national project (No: 10BYY006) on Contrastive Study of Minimum Discourse Patterns in English and Chinesethe MOE project (No: 08JA740013) on Contrastive Study of Clause Relations and Discourse Patterns in English and Chinese
基金The research was supported by the Natural Science Foundation of China （Grants Nos. 51072004, 50802003, 20973013, and 50821061） and the Ministry of Science and Technology of China （Grants Nos. 2007CB936203, 2009CB29403, 2011CB933003, and 2011CB921903）.
文摘When two-dimensional graphene is exfoliated from three-dimensional highly oriented pyrolytic graphite （HOPG）, ripples or corrugations always exist due to the intrinsic thermal fluctuations. Surface-grown graphenes also exhibit wrinkles, which are larger in dimension and are thought to be caused by the difference in thermal expansion coefficients between graphene and the underlying substrate in the cooling process after high temperature growth. For further characterization and applications, it is necessary to transfer the surface-grown graphenes onto dielectric substrates, and other wrinkles are generated during this process. Here, we focus on the wrinkles of transferred graphene and demonstrate that the surface morphology of the growth substrate is the origin of the new wrinkles which arise in the surface-to-surface transfer process; we call these morphology- induced wrinkles. Based on a careful statistical analysis of thousands of atomic force microscopy （AFM） topographic data, we have concluded that these wrinkles on transferred few-layer graphene （typically 1-3 layers） are determined by both the growth substrate morphology and the transfer process. Depending on the transfer medium and conditions, most of the wrinkles can be either released or preserved. Our work suggests a new route for graphene engineering involving structuring the growth substrate and tailoring the transfer process.
