Noble metal/titania hollow nanomaterials usually exhibit excellent photocatalytic activity because of their high specific surface area,low density,good surface permeability,strong light-harvesting capacity,and rapid i...Noble metal/titania hollow nanomaterials usually exhibit excellent photocatalytic activity because of their high specific surface area,low density,good surface permeability,strong light-harvesting capacity,and rapid interfacial charge transfer. However,the present preparation methods usually include complicated and multistep procedures,which can cause damage to the hollow nanostructures. In this paper,a facile template-induced synthesis,based on a template-directed deposition and in situ template-sacrificial dissolution,was employed to prepare Ag-modified TiO 2(Ag/TiO 2) hollow octahedra using Ag2 O octahedra as templates and TiF 4 as the precursor. In the synthetic strategy,the shells of TiO 2 hollow octahedra were formed by coating TiO 2 nanoparticles on the surface of Ag2 O templates based on the template-directed deposition. Simultaneously,the Ag2 O templates can be in situ removed by dissolving the Ag2 O octahedral template in HF solution produced via the hydrolysis reaction of TiF 4 in the reaction system. In addition,Ag nanoparticles were deposited on the inside and outside surfaces of TiO 2 shells by effectively using the photosensitive properties of Ag2 O and Ag+ ions under light irradiation,along with the formation of TiO 2 hollow octahedra. The Ag/TiO 2 hollow octahedra exhibited high photocatalytic activity because of their(1) short diffusion distances between photogenerated electrons and holes because of the thin shells of Ag/TiO 2 hollow octahedral,(2) deposition of Ag nanoparticles on the inside and outside surfaces of TiO 2 shells,and(3) rapid interfacial charge transfer between TiO 2 shells and Ag nanoparticles. This work may also provide new insights into preparing other Ag-modified and hollow nanostructured photocatalysts.展开更多
A modified Rushton impeller with two circular covering-plates mounted on the upper and lower sides of the blades was designed.There are gaps between the plates and the blades.The turbulent hydrodynamics was analyzed b...A modified Rushton impeller with two circular covering-plates mounted on the upper and lower sides of the blades was designed.There are gaps between the plates and the blades.The turbulent hydrodynamics was analyzed by the computational fluid dynamics(CFD) method.Firstly,the reliability of the numerical model and simulation method was verified by comparing with the experimental results from literature.Subsequently,the power consumption,flow pattern,mean velocity and mixing time of the covering-plate Rushton impeller(RT-C) were studied and compared with the standard Rushton impeller(RT) operated under the same conditions.Results show that the power consumption can be decreased about 18%.Compared with the almost unchanged flow field in the lower stirred tank,the mean velocity was increased at the upper half of the stirred tank.And in the impeller region,the mean axial and radial velocities were increased,the mean tangential velocity was decreased.In addition,the average mixing time of RT-C was shortened about 4.14% than the counterpart of RT.The conclusions obtained here indicated that RT-C has a more effective mixing performance and it can be used as an alternative of RT in the process industries.展开更多
A novel full color SOP(system on panel) AMOLED display based on the MIUC polycrystalline silicon TFT technique, and a new control circuit for the panel, which can deal with both VGA and DVI input signals have been d...A novel full color SOP(system on panel) AMOLED display based on the MIUC polycrystalline silicon TFT technique, and a new control circuit for the panel, which can deal with both VGA and DVI input signals have been developed. To realize gray-scale a sub-frame technique has been designed and im- plemented by FPGA device, in which an 120 module has been inserted. Through actual circuit, the whole design has been proven and the advantages of the SOP AMOLED display panel have been confirmed.展开更多
A356 alloy melt solidifies partially when it flows down on an oblique plate cooled from bottom by counter flowing water. Columnar dendrites are continuously formed on the plate wall. Because of the forced convection, ...A356 alloy melt solidifies partially when it flows down on an oblique plate cooled from bottom by counter flowing water. Columnar dendrites are continuously formed on the plate wall. Because of the forced convection, these dendrites are sheared off into equiaxed/fragmented grains and then washed away continuously by producing semisolid slurry at plate exit. Plate cooling rate provides required extent/amount of solidification whereas plate length enables necessary shear for producing semisolid slurry of desired quality. Slurry obtained is solidified in metal mould to produce semisolid-cast billets of desired microstructure. Furthermore, semisolid-cast billets are also heat-treated to improve surface quality. Microstructures of both semisolid-cast and heat-treated billets are compared. The effects of plate length and plate cooling rate on solidification and microstructure of billets produced by using oblique plate are illustrated. Three different plate lengths(200 mm, 250 mm, 300 mm) associated with three different heat transfer coefficients(1000, 2000 and 2500 W/(m2·K)) are involved. Plate length of 250 mm with heat transfer coefficient of 2000 W/(m2·K) gives fine and globular microstructures and is the optimum as there is absolutely no possibility of sticking of slurry to plate wall.展开更多
A numerical model was established for simulating wave impact on a horizontal deck by an improved incompressible smoothed particle hydrodynamics (ISPH). As a grid-less particle method, the ISPH method has been widely u...A numerical model was established for simulating wave impact on a horizontal deck by an improved incompressible smoothed particle hydrodynamics (ISPH). As a grid-less particle method, the ISPH method has been widely used in the free-surface hydrodynamic flows with good accuracy. The improvement includes the employment of a corrective function for enhancement of angular momentum conservation in a particle-based calculation and a new estimation method to predict the pressure on the horizontal deck. The simulation results show a good agreement with the experiment. The present numerical model can be used to study wave impact load on the horizontal deck.展开更多
Triangular silver nanoplates in aqueous solvent and on the surface of quartz substrate have been synthesized by seed-mediated growth approach in the presence of tannin.It was found that both the amount of tannin and t...Triangular silver nanoplates in aqueous solvent and on the surface of quartz substrate have been synthesized by seed-mediated growth approach in the presence of tannin.It was found that both the amount of tannin and the small triangular silver nanoplate seeds added to the growth solution are the key factors to modulation absorption band of triangular silver nanoplates.The optical in-plane dipole surface plasmon resonance (SPR) bands of these Ag nanoplates can be tuned from 608 nm to 980 nm via tannin deoxidization method.The formation mechanism of triangular silver nanoplates was proposed.The tannin deoxidization method realizes a convenient modulation of the absorption band of Ag nanostructures within the visible near-infrared (IR) region both in aqueous solvent and on substrates under mild conditions.展开更多
In this study,a suitable CFD(computational fluid dynamics)model has been developed to investigate the influence of liquid height on the discharge coefficient of the orifice-type liquid distributors.The orifice flow in...In this study,a suitable CFD(computational fluid dynamics)model has been developed to investigate the influence of liquid height on the discharge coefficient of the orifice-type liquid distributors.The orifice flow in different diameters and liquid heights has been realized using the shear stress transport(SST)turbulence model and the Gamma Theta transition(GTT)model.In the ANSYS CFX software,two models are used in conjunction with an automatic wall treatment which allows for a smooth shift from a wall function(WF)to a low turbulent-Re near wall formulation(LTRW).The results of the models coupled with LTRW are closer to the experimental results compared with the models with WF,indicating that LTRW is more appropriate for the prediction of boundary layer characteristics of orifice flow.Simulation results show that the flow conditions of orifices change with the variation of liquid height.With respect to the turbulence in orifice,the SST model coupled with LTRW is recommended.However,with respect to the transition to turbulence in orifice with an increase in liquid height,the predictions of GTT model coupled with LTRW are superior to those obtained using other models.展开更多
The stability control of longwall coalface is the key technology of large-cutting-height mining method.Therefore,a systematic study of the factors that affect coalface stability and its control technology is required ...The stability control of longwall coalface is the key technology of large-cutting-height mining method.Therefore,a systematic study of the factors that affect coalface stability and its control technology is required in the development of large-cutting-height mining method in China. After the practical field observation and years of study,it was found that the more than 95% of failures in coalface are shear failure. The shear failure analysis model of coalface has been established,that can perform systematic study among factors such as mining height,coal mass strength,roof load,support resistance,and face flipper protecting plate horizontal force. Meanwhile,sensitivity analysis of factors influencing coalface stability showed that improving support capacity,cohesion of coal mass and decreasing roof load of coalface are the key to improve coalface stability. Numerical simulation of the factors affecting coalface stability has been performed using UDEC software and the results are consistent with the theoretical analysis. The coalface reinforcement technology of large-cutting-height mining method using the grouting combined with coir rope is presented. Laboratory tests have been carried out to verify its reinforcement effect and practical application has been implemented in several coal mines with good results.It has now become the main technology to reduce longwall coalface failure of large-cutting-height mining method.展开更多
For a ship in service,seawater corrosion is unavoidable. In order to ensure navigation safety and master the steel plate thickness in service ship,thickness of the ship steel plate must be tested periodically by a sci...For a ship in service,seawater corrosion is unavoidable. In order to ensure navigation safety and master the steel plate thickness in service ship,thickness of the ship steel plate must be tested periodically by a scientific method. After consideration of an actual situation of thickness measurement,the bearing mechanism of ultrasonic thickness meter probe has been designed on the basis of wall-climbing robot,and preliminary experiments have been carried out. The device is mainly used for thickness measurement of a large area of ship hull plate when the docking ship has been sandblasted. Efficiency and safety can be improved to finish thickness measurement by using the device.展开更多
TheCo3O4 nanosheet-built hollow dodecahedrons(Co3 O4 NSHDs) were fabricated via a controllable twostep self-templated method. The ZIF-67 dodecahedrons were prepared as first self-template to synthesize the Co-LDH holl...TheCo3O4 nanosheet-built hollow dodecahedrons(Co3 O4 NSHDs) were fabricated via a controllable twostep self-templated method. The ZIF-67 dodecahedrons were prepared as first self-template to synthesize the Co-LDH hollow dodecahedrons, which were further used as self-template to fabricateCo3O4 NSHDs by a controlled calcination.The proposed two-step self-templated method not only brings hollow structures without auxiliary template, ultrathin nanosheet, ultrafine grains, and large surface areas, but also allows the easy and uniform surface modification, as demonstrated of PdO modification. TheCo3O4 NSHDs with above features could show multifunctional applications, such as sensing and catalysis. Experiments suggest that theCo3O4 NSHDs show good gas sensing performances to trimethylamine at a low operating temperature(100 oC). They can be further enhanced by PdO surface modification, which have a low detection limit(250 ppb) and a short response time(4.5 s).In addition, theCo3O4 NSHDs exhibited excellent oxygen evolution reaction performances with a low overpotential of359 mV, low Tafel slope of 80.7 mV dec-1 and low electrochemical impedance, which was superior to those for theCo3O4 NCs obtained by directly calcinating the ZIF-67 templates,Ni foam and most common metal oxides catalysts.展开更多
The surface tensions and contact angles of Fe_(78)Si_9B_(13) and Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 alloy melts were studied as a function of temperature in various atmospheres(vacuum, Ar and N_2 gas) and on different subs...The surface tensions and contact angles of Fe_(78)Si_9B_(13) and Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 alloy melts were studied as a function of temperature in various atmospheres(vacuum, Ar and N_2 gas) and on different substrates(Si C, Al_2O_3 and BN). It is indicated that Si_3N_4, NbN, Fe_2 Al B and B_(13)C_2 are generated as new phases at the interface between the melt and substrate, and reactive wetting behaviour exists during the heating process. The surface tensions of two alloy melts on BN substrate both firstly decrease and then increase along with increasing temperature, leading to V-shaped surface tension versus temperature, which results from atomic diffusion effects in the surface layer during the oxidation of BN and formation of C-rich layer. Comparably, the surface tensions on Al_2O_3 and Si C substrates decrease with increasing temperature throughout the entire temperature range. Among three substrates, BN exhibits the mildest wetting behaviour. The vacuum environment has the strongest protective effect on melt stability among the tested atmospheres. These findings enrich our knowledge about the effects of the substrate and atmosphere on Fe-based alloy melts at a high temperature, and provide theoretical reference for designing jet nozzles in melt-spinning techniques.展开更多
When two contacting solid surfaces are tightly closed and invisible to the naked eye, the discontinuity is said to be microscopic regardless of whether its length is short or long. By this definition, it is not suffic...When two contacting solid surfaces are tightly closed and invisible to the naked eye, the discontinuity is said to be microscopic regardless of whether its length is short or long. By this definition, it is not sufficient to distinguish the difference between a micro- and macro-crack by using the length parameter. Microcracks in high strength metal alloys have been known to be sev- eral centimeters or longer. Considered in this work is a dual scale fatigue crack growth model where the main crack can be mi- cro or macro but there prevails an inherent microscopic tip region that is damaged depending on the irregularities of the micro- structure. This region is referred to as the "micro-tip" and can be simulated by a sharp wedge with different angles in addition to mixed boundary conditions. The combination is sufficient to model microscopic entities in the form of voids, inclusions, precipitations, interfaces, in addition to subgrain imperfections, or cluster of dislocations. This is accomplished by using the method of "singularity representation" such that closed form asymptotic solutions can be obtained for the development of fa- tigue crack growth rate relations with three parameters. They include: (1) the crack surface tightness o-* represented by Cro/Cr~ = 0.3-0.5 for short cracks in region I, and 0.1-0.2 for long cracks in region II, (2) the micro/macro material properties reflected by the shear modulus ratio/1" (=,L/micro/]-/macro varying between 2 and 5) and (3) the most sensitive parameter d* being the micro-tip characteristic length d* (=d/do) whose magnitude decreases in the direction of region I ---~II. The existing fatigue crack growth data for 2024-T3 and 7075-T6 aluminum sheets are used to reinterpret the two-parameter da/dN=C(AK)n relation where AK has now been re-derived for a microcrack with surfaces tightly in contact. The contact force will depend on the mean stress ~m or mean stress ratio R as the primary parameter and on the stress amplitude era as the secondary parameter.展开更多
Protein microarrays based on fluorescence detection have been widely utilized for high-throughput functional proteomic analysis. However, a drawback of such assays has been low sensitivity and narrow dynamic range, li...Protein microarrays based on fluorescence detection have been widely utilized for high-throughput functional proteomic analysis. However, a drawback of such assays has been low sensitivity and narrow dynamic range, limiting their capabilities, especially for detecting low abundance biological molecules such as cytokines in human samples. Here, we present fluorescence-enhancing microarrays on plasmonic gold films for multiplexed cytokine detection with up to three orders of magnitude higher sensitivity than on conventional nitrocellulose and glass substrates. Cytokine detection on the gold plasmonic substrate is about one to two orders of magnitude more sensitive than enzyme-linked immunosorbent assay (ELISA) and can be multiplexed. A panel of six cytokines (Vascular endothelial growth factor (VEGF), Interleukin 1β (IL-1β), Interleukin 4 (IL-4), Interleukin 6 (IL-6), Interferon γ (IFN-γ), and Tumor necrosis factor (TNF)) were detected in the culture media of cancer cells. This work establishes a new method of high throughput multiplexed cytokine detection with higher sensitivity and dynamic range than ELISA.展开更多
基金supported by the National Natural Science Foundation of China(5120839621277107+5 种基金21477094and 51472192)the Program for New Century Excellent Talents in University(NCET-13-0944)the Fundamental Research Funds for the Central Universities(WUT 2014-1a-0032014-VII-037and 2015IB002)~~
文摘Noble metal/titania hollow nanomaterials usually exhibit excellent photocatalytic activity because of their high specific surface area,low density,good surface permeability,strong light-harvesting capacity,and rapid interfacial charge transfer. However,the present preparation methods usually include complicated and multistep procedures,which can cause damage to the hollow nanostructures. In this paper,a facile template-induced synthesis,based on a template-directed deposition and in situ template-sacrificial dissolution,was employed to prepare Ag-modified TiO 2(Ag/TiO 2) hollow octahedra using Ag2 O octahedra as templates and TiF 4 as the precursor. In the synthetic strategy,the shells of TiO 2 hollow octahedra were formed by coating TiO 2 nanoparticles on the surface of Ag2 O templates based on the template-directed deposition. Simultaneously,the Ag2 O templates can be in situ removed by dissolving the Ag2 O octahedral template in HF solution produced via the hydrolysis reaction of TiF 4 in the reaction system. In addition,Ag nanoparticles were deposited on the inside and outside surfaces of TiO 2 shells by effectively using the photosensitive properties of Ag2 O and Ag+ ions under light irradiation,along with the formation of TiO 2 hollow octahedra. The Ag/TiO 2 hollow octahedra exhibited high photocatalytic activity because of their(1) short diffusion distances between photogenerated electrons and holes because of the thin shells of Ag/TiO 2 hollow octahedral,(2) deposition of Ag nanoparticles on the inside and outside surfaces of TiO 2 shells,and(3) rapid interfacial charge transfer between TiO 2 shells and Ag nanoparticles. This work may also provide new insights into preparing other Ag-modified and hollow nanostructured photocatalysts.
基金Supported by the Key Development Foundation of Shandong province(2016GGX103035)
文摘A modified Rushton impeller with two circular covering-plates mounted on the upper and lower sides of the blades was designed.There are gaps between the plates and the blades.The turbulent hydrodynamics was analyzed by the computational fluid dynamics(CFD) method.Firstly,the reliability of the numerical model and simulation method was verified by comparing with the experimental results from literature.Subsequently,the power consumption,flow pattern,mean velocity and mixing time of the covering-plate Rushton impeller(RT-C) were studied and compared with the standard Rushton impeller(RT) operated under the same conditions.Results show that the power consumption can be decreased about 18%.Compared with the almost unchanged flow field in the lower stirred tank,the mean velocity was increased at the upper half of the stirred tank.And in the impeller region,the mean axial and radial velocities were increased,the mean tangential velocity was decreased.In addition,the average mixing time of RT-C was shortened about 4.14% than the counterpart of RT.The conclusions obtained here indicated that RT-C has a more effective mixing performance and it can be used as an alternative of RT in the process industries.
文摘A novel full color SOP(system on panel) AMOLED display based on the MIUC polycrystalline silicon TFT technique, and a new control circuit for the panel, which can deal with both VGA and DVI input signals have been developed. To realize gray-scale a sub-frame technique has been designed and im- plemented by FPGA device, in which an 120 module has been inserted. Through actual circuit, the whole design has been proven and the advantages of the SOP AMOLED display panel have been confirmed.
基金financial support received from Ministry of Mines, TIFAC, and Department of Science and Technology
文摘A356 alloy melt solidifies partially when it flows down on an oblique plate cooled from bottom by counter flowing water. Columnar dendrites are continuously formed on the plate wall. Because of the forced convection, these dendrites are sheared off into equiaxed/fragmented grains and then washed away continuously by producing semisolid slurry at plate exit. Plate cooling rate provides required extent/amount of solidification whereas plate length enables necessary shear for producing semisolid slurry of desired quality. Slurry obtained is solidified in metal mould to produce semisolid-cast billets of desired microstructure. Furthermore, semisolid-cast billets are also heat-treated to improve surface quality. Microstructures of both semisolid-cast and heat-treated billets are compared. The effects of plate length and plate cooling rate on solidification and microstructure of billets produced by using oblique plate are illustrated. Three different plate lengths(200 mm, 250 mm, 300 mm) associated with three different heat transfer coefficients(1000, 2000 and 2500 W/(m2·K)) are involved. Plate length of 250 mm with heat transfer coefficient of 2000 W/(m2·K) gives fine and globular microstructures and is the optimum as there is absolutely no possibility of sticking of slurry to plate wall.
基金the National High Technology Research and Development Program of China (863 Program,Grant No.2007AA11Z130)
文摘A numerical model was established for simulating wave impact on a horizontal deck by an improved incompressible smoothed particle hydrodynamics (ISPH). As a grid-less particle method, the ISPH method has been widely used in the free-surface hydrodynamic flows with good accuracy. The improvement includes the employment of a corrective function for enhancement of angular momentum conservation in a particle-based calculation and a new estimation method to predict the pressure on the horizontal deck. The simulation results show a good agreement with the experiment. The present numerical model can be used to study wave impact load on the horizontal deck.
基金Project(10804101) supported by the National Natural Science Foundation of ChinaProject(2007CB815102) supported by the National Basic Research Program of ChinaProject(2007B08007) supported by the Science and Technology Development Foundation of Chinese Academy of Engineering Physics
文摘Triangular silver nanoplates in aqueous solvent and on the surface of quartz substrate have been synthesized by seed-mediated growth approach in the presence of tannin.It was found that both the amount of tannin and the small triangular silver nanoplate seeds added to the growth solution are the key factors to modulation absorption band of triangular silver nanoplates.The optical in-plane dipole surface plasmon resonance (SPR) bands of these Ag nanoplates can be tuned from 608 nm to 980 nm via tannin deoxidization method.The formation mechanism of triangular silver nanoplates was proposed.The tannin deoxidization method realizes a convenient modulation of the absorption band of Ag nanostructures within the visible near-infrared (IR) region both in aqueous solvent and on substrates under mild conditions.
基金the financial support from the National Basic Research Program of China(No.2009CB219905)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0936)the National Natural Science Foundation of China(No.21176172)
文摘In this study,a suitable CFD(computational fluid dynamics)model has been developed to investigate the influence of liquid height on the discharge coefficient of the orifice-type liquid distributors.The orifice flow in different diameters and liquid heights has been realized using the shear stress transport(SST)turbulence model and the Gamma Theta transition(GTT)model.In the ANSYS CFX software,two models are used in conjunction with an automatic wall treatment which allows for a smooth shift from a wall function(WF)to a low turbulent-Re near wall formulation(LTRW).The results of the models coupled with LTRW are closer to the experimental results compared with the models with WF,indicating that LTRW is more appropriate for the prediction of boundary layer characteristics of orifice flow.Simulation results show that the flow conditions of orifices change with the variation of liquid height.With respect to the turbulence in orifice,the SST model coupled with LTRW is recommended.However,with respect to the transition to turbulence in orifice with an increase in liquid height,the predictions of GTT model coupled with LTRW are superior to those obtained using other models.
基金financial support from National Basic Research Program of China (No.2013CB227903)the National Natural Science Foundation of General Program of China (No.51574244)the Joint Funds of the National Natural Science Foundation of China (No.U1361209) are greatly appreciated
文摘The stability control of longwall coalface is the key technology of large-cutting-height mining method.Therefore,a systematic study of the factors that affect coalface stability and its control technology is required in the development of large-cutting-height mining method in China. After the practical field observation and years of study,it was found that the more than 95% of failures in coalface are shear failure. The shear failure analysis model of coalface has been established,that can perform systematic study among factors such as mining height,coal mass strength,roof load,support resistance,and face flipper protecting plate horizontal force. Meanwhile,sensitivity analysis of factors influencing coalface stability showed that improving support capacity,cohesion of coal mass and decreasing roof load of coalface are the key to improve coalface stability. Numerical simulation of the factors affecting coalface stability has been performed using UDEC software and the results are consistent with the theoretical analysis. The coalface reinforcement technology of large-cutting-height mining method using the grouting combined with coir rope is presented. Laboratory tests have been carried out to verify its reinforcement effect and practical application has been implemented in several coal mines with good results.It has now become the main technology to reduce longwall coalface failure of large-cutting-height mining method.
基金Supported by the National Natural Science Foundation of China(No.51309116)
文摘For a ship in service,seawater corrosion is unavoidable. In order to ensure navigation safety and master the steel plate thickness in service ship,thickness of the ship steel plate must be tested periodically by a scientific method. After consideration of an actual situation of thickness measurement,the bearing mechanism of ultrasonic thickness meter probe has been designed on the basis of wall-climbing robot,and preliminary experiments have been carried out. The device is mainly used for thickness measurement of a large area of ship hull plate when the docking ship has been sandblasted. Efficiency and safety can be improved to finish thickness measurement by using the device.
基金financial support from the National Key R&D Program of China(2016YFC0201103)the Natural Science Foundation of China(51471161 and 11674320)Youth Innovation Promotion Association CAS and Key Research Projects of the Frontier Science CAS(QYZDB-SSW-JSC017)
文摘TheCo3O4 nanosheet-built hollow dodecahedrons(Co3 O4 NSHDs) were fabricated via a controllable twostep self-templated method. The ZIF-67 dodecahedrons were prepared as first self-template to synthesize the Co-LDH hollow dodecahedrons, which were further used as self-template to fabricateCo3O4 NSHDs by a controlled calcination.The proposed two-step self-templated method not only brings hollow structures without auxiliary template, ultrathin nanosheet, ultrafine grains, and large surface areas, but also allows the easy and uniform surface modification, as demonstrated of PdO modification. TheCo3O4 NSHDs with above features could show multifunctional applications, such as sensing and catalysis. Experiments suggest that theCo3O4 NSHDs show good gas sensing performances to trimethylamine at a low operating temperature(100 oC). They can be further enhanced by PdO surface modification, which have a low detection limit(250 ppb) and a short response time(4.5 s).In addition, theCo3O4 NSHDs exhibited excellent oxygen evolution reaction performances with a low overpotential of359 mV, low Tafel slope of 80.7 mV dec-1 and low electrochemical impedance, which was superior to those for theCo3O4 NCs obtained by directly calcinating the ZIF-67 templates,Ni foam and most common metal oxides catalysts.
基金supported by the National Natural Science Foundation of China(Grant No.51501043)National Scientific and Technological Support Projects(Grant No.2013BAE08B00)+1 种基金National Key Scientific Instrument and Equiment Development Project(Grant No.2014YQ120351)Science and Technology Program of Beijing(Grant No.Z141100003814007)
文摘The surface tensions and contact angles of Fe_(78)Si_9B_(13) and Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 alloy melts were studied as a function of temperature in various atmospheres(vacuum, Ar and N_2 gas) and on different substrates(Si C, Al_2O_3 and BN). It is indicated that Si_3N_4, NbN, Fe_2 Al B and B_(13)C_2 are generated as new phases at the interface between the melt and substrate, and reactive wetting behaviour exists during the heating process. The surface tensions of two alloy melts on BN substrate both firstly decrease and then increase along with increasing temperature, leading to V-shaped surface tension versus temperature, which results from atomic diffusion effects in the surface layer during the oxidation of BN and formation of C-rich layer. Comparably, the surface tensions on Al_2O_3 and Si C substrates decrease with increasing temperature throughout the entire temperature range. Among three substrates, BN exhibits the mildest wetting behaviour. The vacuum environment has the strongest protective effect on melt stability among the tested atmospheres. These findings enrich our knowledge about the effects of the substrate and atmosphere on Fe-based alloy melts at a high temperature, and provide theoretical reference for designing jet nozzles in melt-spinning techniques.
文摘When two contacting solid surfaces are tightly closed and invisible to the naked eye, the discontinuity is said to be microscopic regardless of whether its length is short or long. By this definition, it is not sufficient to distinguish the difference between a micro- and macro-crack by using the length parameter. Microcracks in high strength metal alloys have been known to be sev- eral centimeters or longer. Considered in this work is a dual scale fatigue crack growth model where the main crack can be mi- cro or macro but there prevails an inherent microscopic tip region that is damaged depending on the irregularities of the micro- structure. This region is referred to as the "micro-tip" and can be simulated by a sharp wedge with different angles in addition to mixed boundary conditions. The combination is sufficient to model microscopic entities in the form of voids, inclusions, precipitations, interfaces, in addition to subgrain imperfections, or cluster of dislocations. This is accomplished by using the method of "singularity representation" such that closed form asymptotic solutions can be obtained for the development of fa- tigue crack growth rate relations with three parameters. They include: (1) the crack surface tightness o-* represented by Cro/Cr~ = 0.3-0.5 for short cracks in region I, and 0.1-0.2 for long cracks in region II, (2) the micro/macro material properties reflected by the shear modulus ratio/1" (=,L/micro/]-/macro varying between 2 and 5) and (3) the most sensitive parameter d* being the micro-tip characteristic length d* (=d/do) whose magnitude decreases in the direction of region I ---~II. The existing fatigue crack growth data for 2024-T3 and 7075-T6 aluminum sheets are used to reinterpret the two-parameter da/dN=C(AK)n relation where AK has now been re-derived for a microcrack with surfaces tightly in contact. The contact force will depend on the mean stress ~m or mean stress ratio R as the primary parameter and on the stress amplitude era as the secondary parameter.
文摘Protein microarrays based on fluorescence detection have been widely utilized for high-throughput functional proteomic analysis. However, a drawback of such assays has been low sensitivity and narrow dynamic range, limiting their capabilities, especially for detecting low abundance biological molecules such as cytokines in human samples. Here, we present fluorescence-enhancing microarrays on plasmonic gold films for multiplexed cytokine detection with up to three orders of magnitude higher sensitivity than on conventional nitrocellulose and glass substrates. Cytokine detection on the gold plasmonic substrate is about one to two orders of magnitude more sensitive than enzyme-linked immunosorbent assay (ELISA) and can be multiplexed. A panel of six cytokines (Vascular endothelial growth factor (VEGF), Interleukin 1β (IL-1β), Interleukin 4 (IL-4), Interleukin 6 (IL-6), Interferon γ (IFN-γ), and Tumor necrosis factor (TNF)) were detected in the culture media of cancer cells. This work establishes a new method of high throughput multiplexed cytokine detection with higher sensitivity and dynamic range than ELISA.