Plant WRKY transcription factors are involved in various physiological processes, including biotic and abiotic stress responses, as well as developmental processes. In this study, the expression patterns of the WRKY68...Plant WRKY transcription factors are involved in various physiological processes, including biotic and abiotic stress responses, as well as developmental processes. In this study, the expression patterns of the WRKY68 protein during interactions between rice 4021 containing the bacterial blight resistance gene Xa21 and Xanthomonas oryzae pv. oryzae（Xoo） were investigated. A possible modified form of the WRKY68 protein appeared in the Xa21-mediated disease resistance response, and its expression levels were similar in compatible and incompatible responses, but differed significantly from that of the mock control treatment, suggesting that WRKY68 may be involved in the bacterial blight response in rice. To further understand WRKY68＇s roles in the resistance signaling pathway, WRKY68 recombinant protein was expressed in Escherichia coli and a microscale thermophoresis analysis was performed to investigate the interactions between WRKY68 and cis-elements in crucial pathogenesis-related（PR） genes. The results showed that the WRKY68 protein binds to W-boxes in the PR1 b promoter region, with an apparent dissociation constant of 25 nmol L–1, while the binding between WRKY68 and PR10 a was W-box independent. The results suggested that a possible modified form of the WRKY68 protein was induced during the interaction between rice and Xoo, which then regulated the activity of the downstream PR genes by binding with the W-boxes in the PR1 b gene＇s promoter region. Moreover, the constitutive transcription of the WRKY68 gene in dozens of rice tissues and the expression of the WRKY68 protein in leaves during all growth stages suggests that WRKY68 plays important roles in rice during normal growth processes.展开更多
This work is concerned with the analysis of blood flow through inclined catheterized arteries having a balloon(angioplasty) with time-variant overlapping stenosis. The nature of blood in small arteries is analyzed mat...This work is concerned with the analysis of blood flow through inclined catheterized arteries having a balloon(angioplasty) with time-variant overlapping stenosis. The nature of blood in small arteries is analyzed mathematically by considering it as a Carreau nanofluid. The highly nonlinear momentum equations of nanofluid model are simplified by considering the mild stenosis case. The formulated problem is solved by a homotopy perturbation expansion in terms of a variant of the Weissenberg number to obtain explicit forms for the axial velocity, the stream function, the pressure gradient, the resistance impedance and the wall shear stress distribution. These solutions depend on the Brownian motion number, thermophoresis number, local temperature Grashof number G_r and local nanoparticle Grash of number B_r. The results were also studied for various values of the physical parameters, such as the Weissenberg number W_i, the power law index n, the taper angle φ, the maximum height of stenosis δ~*, the angle of inclination α, the maximum height of balloon σ~*, the axial displacement of the balloon z_d~*,the flow rate F and the Froud number Fr. The obtained results show that the transmission of axial velocity curves through a Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) is substantially lower than that through a Carreau nanofluid near the wall of balloon while the inverse occurs in the region between the balloon and stenosis. The streamlines have a clearly distinguished shifting toward the stenotic region and this shifting appears near the wall of the balloon, while it has almost disappeared near the stenotic wall and the trapping bolus in the case of horizontal arteries and Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) does not appear but for the case of Carreau nanofluid bolus appears.展开更多
The problem of laminar fluid flow, which results from the stretching of a vertical surface with variable stream conditions in a nanofluid due to solar energy, is in- vestigated numerically. The model used for the nano...The problem of laminar fluid flow, which results from the stretching of a vertical surface with variable stream conditions in a nanofluid due to solar energy, is in- vestigated numerically. The model used for the nanofluid incorporates the effects of the Brownian motion and thermophoresis in the presence of thermal stratification. The sym- metry groups admitted by the corresponding boundary value problem are obtained by using a special form of Lie group transformations, namely, the scaling group of transfor- mations. An exact solution is obtained for the translation symmetrys, and the numerical solutions are obtained for the scaling symmetry. This solution depends on the Lewis number, the Brownian motion parameter, the thermal stratification parameter, and the thermophoretic parameter. The conclusion is drawn that the flow field, the temperature, and the nanoparticle volume fraction profiles are significantly influenced by these param- eters. Nanofluids have been shown to increase the thermal conductivity and convective heat transfer performance of base liquids. Nanoparticles in the base fluids also offer the potential in improving the radiative properties of the liquids, leading to an increase in the efficiency of direct absorption solar collectors.展开更多
Bisphenol A(BPA)is one of the environmental endocrine disruptors(EDCs),and BPA contamination in environment can cause high risks to human health.Rapid determination of BPA on sites is in high demand in environmental a...Bisphenol A(BPA)is one of the environmental endocrine disruptors(EDCs),and BPA contamination in environment can cause high risks to human health.Rapid determination of BPA on sites is in high demand in environmental analysis.Taking advantage of aptamers as affinity ligands and fluorescence anisotropy(FA)analysis,we developed a simple and rapid FA assay for BPA by employing a single tetramethylrhodamine(TMR)labeled short 35-mer DNA aptamer against BPA.The assay is based on the BPA-binding induced conformation change of TMR-labeled aptamer and alteration of interaction between TMR and guanine bases,resulting in change of FA signals.We screened the FA change of aptamer probes having TMR label on a specific site of the aptamer upon BPA addition.The aptamer with a TMR label on the 22nd T base showed large FA-decreasing response to BPA and maintained good binding affinity to BPA.By using this TMR-labeled aptamer,we achieved FA detection of BPA with a detection limit of 0.5μmol/L under the optimized conditions.This assay was selective towards BPA and enabled the detection of BPA spiked in tap water sample,showing the potential applications on water samples.展开更多
Optical tweezers that rely on laser irradiation to capture and manipulate nanoparticles have provided powerful tools for biological and biochemistry studies.However,the existence of optical diffraction-limit and the t...Optical tweezers that rely on laser irradiation to capture and manipulate nanoparticles have provided powerful tools for biological and biochemistry studies.However,the existence of optical diffraction-limit and the thermal damage caused by high laser power hinder the wider application of optical tweezers in the biological field.For the past decade,the emergence of optothermal tweezers has solved the above problems to a certain extent,while the auxiliary agents used in optothermal tweezers still limit their biocompatibility.Here,we report a kind of nanotweezers based on the sign transformation of the thermophoresis coefficient of colloidal particles in low-temperature environment.Using a self-made microfluidic refrigerator to reduce the ambient temperature to around 0℃in the microfluidic cell,we can control a single nanoparticle at lower laser power without adding additional agent solute in the solution.This novel optical tweezering scheme has provided a new path for the manipulation of inorganic nanoparticles as well as biological particles.展开更多
Microencapsulation phase change material slurry(MEPCMS) becomes a potential working fluid for cooling high energy density miniaturized components,thanks to the latent heat absorption of particles in the heat transfer ...Microencapsulation phase change material slurry(MEPCMS) becomes a potential working fluid for cooling high energy density miniaturized components,thanks to the latent heat absorption of particles in the heat transfer process.In this work,the Discrete Phase Model(DPM) based on the Euler-Lagrangian method is used to numerically investigate the convective heat transfer characteristics of MEPCMS flowing through a rectangular minichannel with constant heat flux.The results show that particles of MEPCMS are mainly subjected to drag force during the flow.Even so,they can migrate from the high-temperature region to the low-temperature region driven by the thermophoretic force,affecting the particle distribution and phase change process.Moreover,the Nux of the MEPCMS fluctuates due to particle phase change with varying specific heat capacities.Specifically,the value increases first,then decreases,and eventually increases again until it approaches the fully developed value of the pure base fluid as the particles gradually melt.Furthermore,the heat transfer performance of the MEPCMS is influenced by the combination of fluid inlet temperature fluid inlet velocity(v),and mass concentration(c_(m)) of MEPCM particles.The result shows that the maximum reduction of the maximum bottom wall temperature difference(ΔT_(w)) is 23.98% at T_(in)=293.15 K,v=0.15 m·s^(-1),c_(m)=10%.展开更多
The role of phoretic forces in providing in-cloud and below-cloud scavenging due to falling drop is reviewed by considering published papers dealing with theoretical models, laboratory and field measurements. Theoreti...The role of phoretic forces in providing in-cloud and below-cloud scavenging due to falling drop is reviewed by considering published papers dealing with theoretical models, laboratory and field measurements. Theoretical analyses agree that Brownian diffusion appears to dominate drop scavenging of aerosol with radius less than 0.1 μm, and inertial impaction dominates scavenging of aerosol with radius higher than 1 μm. Thus, there is a minimum collection efficiency for particles in the approximate range 0.1 μm - 1 μm, where phoretic forces are felt. Generally speaking, published papers report not uniform evaluations of the contribution of thermo- and diffusiophoretic forces. This disagreement is partially due to the different laboratory and field conditions, and different theoretical approaches.展开更多
A numerical model based on the Eulerian–Eulerian two-fluid approach is used to simulate the gasification of coal char inside an entrained flow gasifier. In this model, effects of thermophoresis of coal char particles...A numerical model based on the Eulerian–Eulerian two-fluid approach is used to simulate the gasification of coal char inside an entrained flow gasifier. In this model, effects of thermophoresis of coal char particles are thoroughly investigated. The thermophoresis is due to the gas temperature gradient caused by absorpted heat of coal char gasification. This work, firstly, calculates the gas temperature gradient and thermophoretic force at1100 °C,1200 °C,1300 °C and 1400 °C wall temperatures. Then, the changes of particle volume fraction and velocity in the gasifier are studied in the simulation with thermophoresis or not. The results indicate that considering the particle thermophoresis has some effects on the calculation of particle volume fraction in the gasifier, especially at wall temperature of 1400 °C, and the maximum particle volume fraction variance ratio reaches up to 1.38% on wall surface of the gasifier. These effects are mainly caused by large gas temperature gradient along the radial direction of the gasifier. For the particle velocity, the changes are small but can be observable along radial direction of the gasifier, which has good agreement with the distributions of radial gas temperature gradient and thermophoretic force. These changes above may have certain effects on gasification reaction rates in this Eulerian model. So the change of gasification reaction rates in the simulation with thermophoresis or not is studied finally.展开更多
The numerical analysis of heat transfer of laminar nanofluid flow over a fiat stretching sheet is presented. Two sets of boundary conditions （BCs） axe analyzed, i.e., a constant （Case 1） and a linear streamwise va...The numerical analysis of heat transfer of laminar nanofluid flow over a fiat stretching sheet is presented. Two sets of boundary conditions （BCs） axe analyzed, i.e., a constant （Case 1） and a linear streamwise variation of nanopaxticle volume fraction and wall temperature （Case 2）. The governing equations and BCs axe reduced to a set of nonlinear ordinary differential equations （ODEs） and the corresponding BCs, respectively. The dependencies of solutions on Prandtl number Pr, Lewis number Le, Brownian motion number Nb, and thermophoresis number Nt are studied in detail. The results show that the reduced Nusselt number and the reduced Sherwood number increase for the BCs of Case 2 compared with Case 1. The increases of Nb, Nt, and Le numbers cause a decrease of the reduced Nusselt number, while the reduced Sherwood number increases with the increase of Nb and Le numbers. For low Prandtl numbers, an increase of Nt number can cause to decrease in the reduced Sherwood number, while it increases for high Prandtl numbers.展开更多
The present article explores the entropy generation of radiating viscoelastic second grade nanofluid in a porous channel confined between two parallel plates. The boundaries of the plates are maintained at distinct te...The present article explores the entropy generation of radiating viscoelastic second grade nanofluid in a porous channel confined between two parallel plates. The boundaries of the plates are maintained at distinct temperatures and concentrations while the fluid is being sucked and injected periodically through upper and lower plates. The buoyancy forces, thermophoresis and Brownian motion are also considered due to the temperature and concentration differences across the channel. The system of governing partial differential equations has been transferred into a system of ordinary differential equations(ODEs) by appropriate similarity relations, and a shooting method with the fourth-order Runge-Kutta scheme is used for the solutions. The results are analyzed in detail for dimensionless velocity components. The temperature, concentration distributions, the entropy generation number, and the Bejan number corresponding to various fluid and geometric parameters are shown graphically. The skin friction, heat and mass transfer rates are presented in the form of tables. It is noticed that the temperature profile of the fluid is enhanced with the Brownian motion, whereas the concentration profile of the fluid is decreased with the thermophoresis parameter, and the entropy and Bejan numbers exhibit the opposite trend for the suction and injection ratio.展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China(20131302110006)
文摘Plant WRKY transcription factors are involved in various physiological processes, including biotic and abiotic stress responses, as well as developmental processes. In this study, the expression patterns of the WRKY68 protein during interactions between rice 4021 containing the bacterial blight resistance gene Xa21 and Xanthomonas oryzae pv. oryzae（Xoo） were investigated. A possible modified form of the WRKY68 protein appeared in the Xa21-mediated disease resistance response, and its expression levels were similar in compatible and incompatible responses, but differed significantly from that of the mock control treatment, suggesting that WRKY68 may be involved in the bacterial blight response in rice. To further understand WRKY68＇s roles in the resistance signaling pathway, WRKY68 recombinant protein was expressed in Escherichia coli and a microscale thermophoresis analysis was performed to investigate the interactions between WRKY68 and cis-elements in crucial pathogenesis-related（PR） genes. The results showed that the WRKY68 protein binds to W-boxes in the PR1 b promoter region, with an apparent dissociation constant of 25 nmol L–1, while the binding between WRKY68 and PR10 a was W-box independent. The results suggested that a possible modified form of the WRKY68 protein was induced during the interaction between rice and Xoo, which then regulated the activity of the downstream PR genes by binding with the W-boxes in the PR1 b gene＇s promoter region. Moreover, the constitutive transcription of the WRKY68 gene in dozens of rice tissues and the expression of the WRKY68 protein in leaves during all growth stages suggests that WRKY68 plays important roles in rice during normal growth processes.
文摘This work is concerned with the analysis of blood flow through inclined catheterized arteries having a balloon(angioplasty) with time-variant overlapping stenosis. The nature of blood in small arteries is analyzed mathematically by considering it as a Carreau nanofluid. The highly nonlinear momentum equations of nanofluid model are simplified by considering the mild stenosis case. The formulated problem is solved by a homotopy perturbation expansion in terms of a variant of the Weissenberg number to obtain explicit forms for the axial velocity, the stream function, the pressure gradient, the resistance impedance and the wall shear stress distribution. These solutions depend on the Brownian motion number, thermophoresis number, local temperature Grashof number G_r and local nanoparticle Grash of number B_r. The results were also studied for various values of the physical parameters, such as the Weissenberg number W_i, the power law index n, the taper angle φ, the maximum height of stenosis δ~*, the angle of inclination α, the maximum height of balloon σ~*, the axial displacement of the balloon z_d~*,the flow rate F and the Froud number Fr. The obtained results show that the transmission of axial velocity curves through a Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) is substantially lower than that through a Carreau nanofluid near the wall of balloon while the inverse occurs in the region between the balloon and stenosis. The streamlines have a clearly distinguished shifting toward the stenotic region and this shifting appears near the wall of the balloon, while it has almost disappeared near the stenotic wall and the trapping bolus in the case of horizontal arteries and Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) does not appear but for the case of Carreau nanofluid bolus appears.
文摘The problem of laminar fluid flow, which results from the stretching of a vertical surface with variable stream conditions in a nanofluid due to solar energy, is in- vestigated numerically. The model used for the nanofluid incorporates the effects of the Brownian motion and thermophoresis in the presence of thermal stratification. The sym- metry groups admitted by the corresponding boundary value problem are obtained by using a special form of Lie group transformations, namely, the scaling group of transfor- mations. An exact solution is obtained for the translation symmetrys, and the numerical solutions are obtained for the scaling symmetry. This solution depends on the Lewis number, the Brownian motion parameter, the thermal stratification parameter, and the thermophoretic parameter. The conclusion is drawn that the flow field, the temperature, and the nanoparticle volume fraction profiles are significantly influenced by these param- eters. Nanofluids have been shown to increase the thermal conductivity and convective heat transfer performance of base liquids. Nanoparticles in the base fluids also offer the potential in improving the radiative properties of the liquids, leading to an increase in the efficiency of direct absorption solar collectors.
基金supported by the National Natural Science Foundation of China(Nos.21874146,21575153,21435008)。
文摘Bisphenol A(BPA)is one of the environmental endocrine disruptors(EDCs),and BPA contamination in environment can cause high risks to human health.Rapid determination of BPA on sites is in high demand in environmental analysis.Taking advantage of aptamers as affinity ligands and fluorescence anisotropy(FA)analysis,we developed a simple and rapid FA assay for BPA by employing a single tetramethylrhodamine(TMR)labeled short 35-mer DNA aptamer against BPA.The assay is based on the BPA-binding induced conformation change of TMR-labeled aptamer and alteration of interaction between TMR and guanine bases,resulting in change of FA signals.We screened the FA change of aptamer probes having TMR label on a specific site of the aptamer upon BPA addition.The aptamer with a TMR label on the 22nd T base showed large FA-decreasing response to BPA and maintained good binding affinity to BPA.By using this TMR-labeled aptamer,we achieved FA detection of BPA with a detection limit of 0.5μmol/L under the optimized conditions.This assay was selective towards BPA and enabled the detection of BPA spiked in tap water sample,showing the potential applications on water samples.
基金the National Natural Science Foundation of China(Nos.62275164,61905145,and 62275168)National Key Research and Development Program of China(No.2022YFA1200116)+1 种基金Guangdong Natural Science Foundation and Province Project(No.2021A1515011916)Shenzhen Science and Technology Planning Project(No.ZDSYS20210623092006020).
文摘Optical tweezers that rely on laser irradiation to capture and manipulate nanoparticles have provided powerful tools for biological and biochemistry studies.However,the existence of optical diffraction-limit and the thermal damage caused by high laser power hinder the wider application of optical tweezers in the biological field.For the past decade,the emergence of optothermal tweezers has solved the above problems to a certain extent,while the auxiliary agents used in optothermal tweezers still limit their biocompatibility.Here,we report a kind of nanotweezers based on the sign transformation of the thermophoresis coefficient of colloidal particles in low-temperature environment.Using a self-made microfluidic refrigerator to reduce the ambient temperature to around 0℃in the microfluidic cell,we can control a single nanoparticle at lower laser power without adding additional agent solute in the solution.This novel optical tweezering scheme has provided a new path for the manipulation of inorganic nanoparticles as well as biological particles.
基金the financial support of the National Natural Science Foundation of China (No.U20A20299)the Natural Science Foundation of Guangdong Province (No.2019A1515012119)。
文摘Microencapsulation phase change material slurry(MEPCMS) becomes a potential working fluid for cooling high energy density miniaturized components,thanks to the latent heat absorption of particles in the heat transfer process.In this work,the Discrete Phase Model(DPM) based on the Euler-Lagrangian method is used to numerically investigate the convective heat transfer characteristics of MEPCMS flowing through a rectangular minichannel with constant heat flux.The results show that particles of MEPCMS are mainly subjected to drag force during the flow.Even so,they can migrate from the high-temperature region to the low-temperature region driven by the thermophoretic force,affecting the particle distribution and phase change process.Moreover,the Nux of the MEPCMS fluctuates due to particle phase change with varying specific heat capacities.Specifically,the value increases first,then decreases,and eventually increases again until it approaches the fully developed value of the pure base fluid as the particles gradually melt.Furthermore,the heat transfer performance of the MEPCMS is influenced by the combination of fluid inlet temperature fluid inlet velocity(v),and mass concentration(c_(m)) of MEPCM particles.The result shows that the maximum reduction of the maximum bottom wall temperature difference(ΔT_(w)) is 23.98% at T_(in)=293.15 K,v=0.15 m·s^(-1),c_(m)=10%.
文摘The role of phoretic forces in providing in-cloud and below-cloud scavenging due to falling drop is reviewed by considering published papers dealing with theoretical models, laboratory and field measurements. Theoretical analyses agree that Brownian diffusion appears to dominate drop scavenging of aerosol with radius less than 0.1 μm, and inertial impaction dominates scavenging of aerosol with radius higher than 1 μm. Thus, there is a minimum collection efficiency for particles in the approximate range 0.1 μm - 1 μm, where phoretic forces are felt. Generally speaking, published papers report not uniform evaluations of the contribution of thermo- and diffusiophoretic forces. This disagreement is partially due to the different laboratory and field conditions, and different theoretical approaches.
文摘A numerical model based on the Eulerian–Eulerian two-fluid approach is used to simulate the gasification of coal char inside an entrained flow gasifier. In this model, effects of thermophoresis of coal char particles are thoroughly investigated. The thermophoresis is due to the gas temperature gradient caused by absorpted heat of coal char gasification. This work, firstly, calculates the gas temperature gradient and thermophoretic force at1100 °C,1200 °C,1300 °C and 1400 °C wall temperatures. Then, the changes of particle volume fraction and velocity in the gasifier are studied in the simulation with thermophoresis or not. The results indicate that considering the particle thermophoresis has some effects on the calculation of particle volume fraction in the gasifier, especially at wall temperature of 1400 °C, and the maximum particle volume fraction variance ratio reaches up to 1.38% on wall surface of the gasifier. These effects are mainly caused by large gas temperature gradient along the radial direction of the gasifier. For the particle velocity, the changes are small but can be observable along radial direction of the gasifier, which has good agreement with the distributions of radial gas temperature gradient and thermophoretic force. These changes above may have certain effects on gasification reaction rates in this Eulerian model. So the change of gasification reaction rates in the simulation with thermophoresis or not is studied finally.
文摘The numerical analysis of heat transfer of laminar nanofluid flow over a fiat stretching sheet is presented. Two sets of boundary conditions （BCs） axe analyzed, i.e., a constant （Case 1） and a linear streamwise variation of nanopaxticle volume fraction and wall temperature （Case 2）. The governing equations and BCs axe reduced to a set of nonlinear ordinary differential equations （ODEs） and the corresponding BCs, respectively. The dependencies of solutions on Prandtl number Pr, Lewis number Le, Brownian motion number Nb, and thermophoresis number Nt are studied in detail. The results show that the reduced Nusselt number and the reduced Sherwood number increase for the BCs of Case 2 compared with Case 1. The increases of Nb, Nt, and Le numbers cause a decrease of the reduced Nusselt number, while the reduced Sherwood number increases with the increase of Nb and Le numbers. For low Prandtl numbers, an increase of Nt number can cause to decrease in the reduced Sherwood number, while it increases for high Prandtl numbers.
基金supported by the Senior Research Fellowship of the Defence Research and Development Organization(No.DIAT/F/Acad(Ph.D.)/1613/15-52-12)
文摘The present article explores the entropy generation of radiating viscoelastic second grade nanofluid in a porous channel confined between two parallel plates. The boundaries of the plates are maintained at distinct temperatures and concentrations while the fluid is being sucked and injected periodically through upper and lower plates. The buoyancy forces, thermophoresis and Brownian motion are also considered due to the temperature and concentration differences across the channel. The system of governing partial differential equations has been transferred into a system of ordinary differential equations(ODEs) by appropriate similarity relations, and a shooting method with the fourth-order Runge-Kutta scheme is used for the solutions. The results are analyzed in detail for dimensionless velocity components. The temperature, concentration distributions, the entropy generation number, and the Bejan number corresponding to various fluid and geometric parameters are shown graphically. The skin friction, heat and mass transfer rates are presented in the form of tables. It is noticed that the temperature profile of the fluid is enhanced with the Brownian motion, whereas the concentration profile of the fluid is decreased with the thermophoresis parameter, and the entropy and Bejan numbers exhibit the opposite trend for the suction and injection ratio.
