The evolution of wake structure in a flow around an impulsively stopped sphere in an incompressible viscous fluid is investigated under the influence of a streamwise magnetic field at moderate Reynolds numbers.The res...The evolution of wake structure in a flow around an impulsively stopped sphere in an incompressible viscous fluid is investigated under the influence of a streamwise magnetic field at moderate Reynolds numbers.The research parameter range is 600≤Re≤1400 and 0≤N≤10,where Re and N are the Reynolds number and the interaction parameter,respectively.A vortex ring system is developed,which contains the primary and secondary vortex rings after stopping the sphere.The flow will keep axisymmetric before stopping the sphere for the purpose to investigate the instability of shedding vortex rings.Without the magnetic field,an azimuthal instability will develop on the secondary vortex ring when the Reynolds number is large enough,e.g.,Re=1200.It is caused by the centrifugal movement of the secondary vortex ring and this instability can be suppressed by the streamwise magnetic field.Furthermore,an obvious oscillation caused by the motion of the primary vortex ring on the drag force is found after stopping the sphere.The amplitude of such oscillation increases with enlarging the Reynolds number but decreases with enlarging the magnetic field intensity.展开更多
Protein arginine methyltransferases(PRMTs)are crucial epigenetic regulators in eukaryotic organisms that serve as histone writers for chromatin remodeling.PRMTs also methylate a variety of non-histone protein substrat...Protein arginine methyltransferases(PRMTs)are crucial epigenetic regulators in eukaryotic organisms that serve as histone writers for chromatin remodeling.PRMTs also methylate a variety of non-histone protein substrates to modulate their function and activity.The development of potent PRMT inhibitors has become an emerging and imperative research area in the drug discovery field to provide novel therapeutic agents for treating diseases and as tools to investigate the biological functions of PRMTs.PRMT1 is the major type I enzyme that catalyzes the formation of asymmetric dimethyl arginine,and PRMT1 plays important regulatory roles in signal transduction,transcriptional activation,RNA splicing,and DNA repair.Aberrant expression of PRMT1 is found in many types of cancers,pulmonary diseases,cardiovascular disease,diabetes,and renal diseases.PRMT1 is a highly promising target for therapeutic development.We created a stopped flow fluorescence-based assay for PRMT1 inhibitor detection and characterization that has the advantages of being homogeneous,nonradioactive,and mix-and-measure in nature,allowing for continuous measurement of the methylation reaction and its inhibition.To our knowledge,this is the first continuous assay for PRMT1 reaction detection and inhibitor characterization.The approach is not only capable of quantitatively determining the potency(IC50)of PRMT1 inhibitors but can also distinguish cofactor-competitive inhibitors,substrate-competitive inhibitors,and mixed-type inhibitors.展开更多
Government crackdowns may put the dairy industry back on the right track,but more action will be necessary to ensure dairy safety Nearly half of China’s dairy enter-p rises will be forced to suspend operations or clo...Government crackdowns may put the dairy industry back on the right track,but more action will be necessary to ensure dairy safety Nearly half of China’s dairy enter-p rises will be forced to suspend operations or close their facilities following a watchdog ins pectiont hat found many dairy producers have been operating below quality safety standards.展开更多
Mr.Han Qide and his party meeting with Prof.Mehmet SAGLAM,Vice Speaker of the Grand National Assembly of Turkey.Mr.Han Qide meeting with Mr.Shimon Peres,the President of Israel.Mr.Han Qide and his party attending Chin...Mr.Han Qide and his party meeting with Prof.Mehmet SAGLAM,Vice Speaker of the Grand National Assembly of Turkey.Mr.Han Qide meeting with Mr.Shimon Peres,the President of Israel.Mr.Han Qide and his party attending China-Turkey NGO Roundtable Meeting.Mr.Han Qide and his party attending the China-Israel Friendly Associations and Think Tanks Workshop.展开更多
The computational fluid dynamics(CFD)approach can be used to obtain both internal and external characteristics of centrifugal pumps,and the variations of the hydrodynamic force,the pressure and the torque on the blade...The computational fluid dynamics(CFD)approach can be used to obtain both internal and external characteristics of centrifugal pumps,and the variations of the hydrodynamic force,the pressure and the torque on the blades acquired by the CFD are highly associated with the safety of the pumping system.Based on the CFD simulations,this paper investigates the stopping characteristics of multiple pumps with some pumps being stopped.The 3-D geometric model is built,including all 6 pumps,the valves,the pipes,the tanks and other components,and using the Realizable k-ε turbulence model.The CFD results for the operating points agree well with the results from the theoretical analysis.With some pumps being stopped,the key parameters of the operating pumps would not be stable,with a larger fluctuation;the direction of the hydrodynamic force might be opposite with more than 3 stopped pumps.For the stopped pumps,the maximum reverse values of the discharge and the rotational speed would be larger when fewer pumps are stopped,and could be more than 120%of the rated values,which is dangerous for the pumping system.The CFD results could help understanding the stopping process of multiple pump systems with some pumps being stopped.展开更多
When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling o...When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling of driving.Ifs fun!展开更多
We investigate the influence of gold doping on the transport range of a relativistic electron beam in high-density deuterium–tritium(DT)fuel,which could be encountered in the double-cone ignition laser fusion.We deve...We investigate the influence of gold doping on the transport range of a relativistic electron beam in high-density deuterium–tritium(DT)fuel,which could be encountered in the double-cone ignition laser fusion.We develop the stopping power model to include gold doping and then analyze the influence of Coulomb collision and bremsstrahlung on the electron transport range with different gold doping ratios,consistent with the Geant4 simulations.When the gold doping ratio increases from 0.5%to 30%,the transport range of a 10 Me V electron beam is decreased by 9.6%and 18.5%via the bremsstrahlung.For the 1 Me V beam,the decrease of the range becomes 0.7%and 1.0%.We also investigate the transverse broadening of the electron beam and radiated photon energy reabsorption in a spherical target.When the gold doping ratio is 2%and the beam energy is increased from 1 Me V to 5 Me V,the bremsstrahlung photons cover 2.6%to 10.3%of the total beam energy.Meanwhile,the reabsorbed photon energy is reduced from 31.6%to 8.9%.展开更多
This paper investigates the start-up and shutdown phases of a five-bladed closed-impeller centrifugal pump through experimental analysis,capturing the temporal evolution of its hydraulic performances.The study also pr...This paper investigates the start-up and shutdown phases of a five-bladed closed-impeller centrifugal pump through experimental analysis,capturing the temporal evolution of its hydraulic performances.The study also predicts the transient characteristics of the pump under non-rated operating conditions to assess the accuracy of various machine learning methods in forecasting its instantaneous performance.Results indicate that the pump’s transient behavior in power-frequency mode markedly differs from that in frequency-conversion mode.Specifically,the power-frequency mode achieves steady-state values faster and exhibits smaller fluctuations before stabilization compared to the other mode.During the start-up phase,as the steady-state flow rate increases,inlet and outlet pressures and head also rise,while torque and shaft power decrease,with rotational speed remaining largely unchanged.Conversely,during the shutdown phase,no significant changes were observed in torque,shaft power,or rotational speed.Six machine learning models,including Gaussian Process Regression(GPR),Decision Tree Regression(DTR),and Deep Learning Networks(DLN),demonstrated high accuracy in predicting the hydraulic performance of the centrifugal pump during the start-up and shutdown phases in both power-frequency and frequency-conversion conditions.The findings provide a theoretical foundation for improved prediction of pump hydraulic performance.For instance,when predicting head and flow rate during power-frequency start-up,GPR achieved absolute and relative errors of 0.54 m(7.84%)and 0.21 m3/h(13.57%),respectively,while the Feedforward Neural Network(FNN)reported errors of 0.98 m(8.24%)and 0.10 m3/h(16.71%).By contrast,the Support Vector Machine Regression(SVMR)and Generalized Additive Model(GAM)generally yielded less satisfactory prediction accuracy compared to the other methods.展开更多
We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The...We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The free-electron contribution is described by the Maynard–Deutsch–Zimmerman formula,and the bound-electron contribution relies on the Bethe formula with corrections,in particular taking into account density and shell effects.The results of the bound-state computation using three different parametric potentials are investigated within the Garbet formalism for the mean excitation energy.The first parametric potential is due to Green,Sellin,and Zachor,the second one was proposed by Yunta,and the third one was introduced by Klapisch in the framework of atomic-structure computations.The results are compared with those of self-consistent average-atom calculations.This approach correctly bridges the limits of neutral and fully ionized matter.展开更多
To address the sensitive and uncertain limitations of single-energy computed tomography(CT)calibration methods in computing proton stopping power ratio during treatment planning,different methods have been proposed us...To address the sensitive and uncertain limitations of single-energy computed tomography(CT)calibration methods in computing proton stopping power ratio during treatment planning,different methods have been proposed using a dual energy CT approach.This paper reviews the most recent dual-energy CT approaches for computing proton stopping power ratio.These include image domain and projection domain methods.The advantages and uncertainties of these methods are analyzed based on existing studies.This paper highlights recent advances in dual energy CT,discussing their implementation,advantages,limitations,and potential for clinical adoption.展开更多
Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-dope...Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-doped double perovskites are common,research on their thermoluminescence(TL)properties is less extensive.This study synthesized a series of Y_(2-x)Sm_(x)MgTiO_(6)(0≤x≤0.1)samples using a high-temperature solid-state method.X-ray diffraction(XRD)analysis confirmed a monoclinic crystal structure(space group P2_(1)∕n),with Sm^(3+)ions substituting for Y^(3+)ions in Y_(2)MgTiO_(6).The PL results indicated that the optimal doping concentration was Y_(1.95)Sm_(0.05)MgTiO_(6),exhibiting emission peaks at 568,605,652,and 715 nm under 409 nm blue light excitation.The TL measurements for different doping concentrations showed that the Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors exhibited the strongest TL signals.The TL peaks observed at 530 and 610 K correspond to defects in the matrix and Sm^(3+)dopants,respectively.The T_(m)-T_(stop)analysis revealed that the TL curve of Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors was a superposition of seven peaks.Computerized glow curve deconvolution(CGCD)was performed on the TL of the sample according to the results of three-dimensional thermoluminescence spectra(3D-TL)and T_(m)-T_(stop),and the trap depths in the sample were estimated to range from 0.69 to 1.49 eV.Additionally,the lifetimes of each overlapping peak were calculated using the fitting parameters.Furthermore,the dose-response test showed that the saturation dose of the sample was high(9956 Gy).Therefore,this material can serve as a thermoluminescent dosimeter for high-dose measurements.The saturation dose for the lowest-temperature overlapping peak was 102 Gy,which correlated with its specific energy-level lifetime,whereas the other overlapping peaks also exhibited favorable linear relationships.展开更多
基金the National Natural Science Foundation of China(Grant No.52006212)Basic Frontier Science Research Program of Chinese Academy of Sciences(Grant No.ZDBS-LY-JSC033)+1 种基金Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB22040201)China Postdoctoral Science Foundation(Grant No.2019M650815).
文摘The evolution of wake structure in a flow around an impulsively stopped sphere in an incompressible viscous fluid is investigated under the influence of a streamwise magnetic field at moderate Reynolds numbers.The research parameter range is 600≤Re≤1400 and 0≤N≤10,where Re and N are the Reynolds number and the interaction parameter,respectively.A vortex ring system is developed,which contains the primary and secondary vortex rings after stopping the sphere.The flow will keep axisymmetric before stopping the sphere for the purpose to investigate the instability of shedding vortex rings.Without the magnetic field,an azimuthal instability will develop on the secondary vortex ring when the Reynolds number is large enough,e.g.,Re=1200.It is caused by the centrifugal movement of the secondary vortex ring and this instability can be suppressed by the streamwise magnetic field.Furthermore,an obvious oscillation caused by the motion of the primary vortex ring on the drag force is found after stopping the sphere.The amplitude of such oscillation increases with enlarging the Reynolds number but decreases with enlarging the magnetic field intensity.
文摘Protein arginine methyltransferases(PRMTs)are crucial epigenetic regulators in eukaryotic organisms that serve as histone writers for chromatin remodeling.PRMTs also methylate a variety of non-histone protein substrates to modulate their function and activity.The development of potent PRMT inhibitors has become an emerging and imperative research area in the drug discovery field to provide novel therapeutic agents for treating diseases and as tools to investigate the biological functions of PRMTs.PRMT1 is the major type I enzyme that catalyzes the formation of asymmetric dimethyl arginine,and PRMT1 plays important regulatory roles in signal transduction,transcriptional activation,RNA splicing,and DNA repair.Aberrant expression of PRMT1 is found in many types of cancers,pulmonary diseases,cardiovascular disease,diabetes,and renal diseases.PRMT1 is a highly promising target for therapeutic development.We created a stopped flow fluorescence-based assay for PRMT1 inhibitor detection and characterization that has the advantages of being homogeneous,nonradioactive,and mix-and-measure in nature,allowing for continuous measurement of the methylation reaction and its inhibition.To our knowledge,this is the first continuous assay for PRMT1 reaction detection and inhibitor characterization.The approach is not only capable of quantitatively determining the potency(IC50)of PRMT1 inhibitors but can also distinguish cofactor-competitive inhibitors,substrate-competitive inhibitors,and mixed-type inhibitors.
文摘Government crackdowns may put the dairy industry back on the right track,but more action will be necessary to ensure dairy safety Nearly half of China’s dairy enter-p rises will be forced to suspend operations or close their facilities following a watchdog ins pectiont hat found many dairy producers have been operating below quality safety standards.
文摘Mr.Han Qide and his party meeting with Prof.Mehmet SAGLAM,Vice Speaker of the Grand National Assembly of Turkey.Mr.Han Qide meeting with Mr.Shimon Peres,the President of Israel.Mr.Han Qide and his party attending China-Turkey NGO Roundtable Meeting.Mr.Han Qide and his party attending the China-Israel Friendly Associations and Think Tanks Workshop.
基金Projects supported by the National Natural Science Foundation of China(Grant Nos.51879087,51839008 and 51709087).
文摘The computational fluid dynamics(CFD)approach can be used to obtain both internal and external characteristics of centrifugal pumps,and the variations of the hydrodynamic force,the pressure and the torque on the blades acquired by the CFD are highly associated with the safety of the pumping system.Based on the CFD simulations,this paper investigates the stopping characteristics of multiple pumps with some pumps being stopped.The 3-D geometric model is built,including all 6 pumps,the valves,the pipes,the tanks and other components,and using the Realizable k-ε turbulence model.The CFD results for the operating points agree well with the results from the theoretical analysis.With some pumps being stopped,the key parameters of the operating pumps would not be stable,with a larger fluctuation;the direction of the hydrodynamic force might be opposite with more than 3 stopped pumps.For the stopped pumps,the maximum reverse values of the discharge and the rotational speed would be larger when fewer pumps are stopped,and could be more than 120%of the rated values,which is dangerous for the pumping system.The CFD results could help understanding the stopping process of multiple pump systems with some pumps being stopped.
文摘When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling of driving.Ifs fun!
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA25050300 and XDA25010100)the National Key R&D Program of China(Grant No.2018YFA0404801)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.20XNLG01)。
文摘We investigate the influence of gold doping on the transport range of a relativistic electron beam in high-density deuterium–tritium(DT)fuel,which could be encountered in the double-cone ignition laser fusion.We develop the stopping power model to include gold doping and then analyze the influence of Coulomb collision and bremsstrahlung on the electron transport range with different gold doping ratios,consistent with the Geant4 simulations.When the gold doping ratio increases from 0.5%to 30%,the transport range of a 10 Me V electron beam is decreased by 9.6%and 18.5%via the bremsstrahlung.For the 1 Me V beam,the decrease of the range becomes 0.7%and 1.0%.We also investigate the transverse broadening of the electron beam and radiated photon energy reabsorption in a spherical target.When the gold doping ratio is 2%and the beam energy is increased from 1 Me V to 5 Me V,the bremsstrahlung photons cover 2.6%to 10.3%of the total beam energy.Meanwhile,the reabsorbed photon energy is reduced from 31.6%to 8.9%.
基金financially supported by Science and Technology Project of Quzhou(Grant Nos.2023K256,2023NC08)Research Grants Program of Department of Education of Zhejiang Province(No.Y202455709)+1 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LZY21E050001)University-Enterprise Cooperation Program for Visiting Engineers in Higher Education Institutions in Zhejiang Province(No.FG2020215).
文摘This paper investigates the start-up and shutdown phases of a five-bladed closed-impeller centrifugal pump through experimental analysis,capturing the temporal evolution of its hydraulic performances.The study also predicts the transient characteristics of the pump under non-rated operating conditions to assess the accuracy of various machine learning methods in forecasting its instantaneous performance.Results indicate that the pump’s transient behavior in power-frequency mode markedly differs from that in frequency-conversion mode.Specifically,the power-frequency mode achieves steady-state values faster and exhibits smaller fluctuations before stabilization compared to the other mode.During the start-up phase,as the steady-state flow rate increases,inlet and outlet pressures and head also rise,while torque and shaft power decrease,with rotational speed remaining largely unchanged.Conversely,during the shutdown phase,no significant changes were observed in torque,shaft power,or rotational speed.Six machine learning models,including Gaussian Process Regression(GPR),Decision Tree Regression(DTR),and Deep Learning Networks(DLN),demonstrated high accuracy in predicting the hydraulic performance of the centrifugal pump during the start-up and shutdown phases in both power-frequency and frequency-conversion conditions.The findings provide a theoretical foundation for improved prediction of pump hydraulic performance.For instance,when predicting head and flow rate during power-frequency start-up,GPR achieved absolute and relative errors of 0.54 m(7.84%)and 0.21 m3/h(13.57%),respectively,while the Feedforward Neural Network(FNN)reported errors of 0.98 m(8.24%)and 0.10 m3/h(16.71%).By contrast,the Support Vector Machine Regression(SVMR)and Generalized Additive Model(GAM)generally yielded less satisfactory prediction accuracy compared to the other methods.
文摘We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The free-electron contribution is described by the Maynard–Deutsch–Zimmerman formula,and the bound-electron contribution relies on the Bethe formula with corrections,in particular taking into account density and shell effects.The results of the bound-state computation using three different parametric potentials are investigated within the Garbet formalism for the mean excitation energy.The first parametric potential is due to Green,Sellin,and Zachor,the second one was proposed by Yunta,and the third one was introduced by Klapisch in the framework of atomic-structure computations.The results are compared with those of self-consistent average-atom calculations.This approach correctly bridges the limits of neutral and fully ionized matter.
文摘To address the sensitive and uncertain limitations of single-energy computed tomography(CT)calibration methods in computing proton stopping power ratio during treatment planning,different methods have been proposed using a dual energy CT approach.This paper reviews the most recent dual-energy CT approaches for computing proton stopping power ratio.These include image domain and projection domain methods.The advantages and uncertainties of these methods are analyzed based on existing studies.This paper highlights recent advances in dual energy CT,discussing their implementation,advantages,limitations,and potential for clinical adoption.
基金supported by the Zhanjiang Science and Technology Plan Project(No.2022A05022)Science and Technology Development Special Project of Zhanjiang(No.2023A21616)Research Project of Guangdong Ocean University(No.060302112102).
文摘Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-doped double perovskites are common,research on their thermoluminescence(TL)properties is less extensive.This study synthesized a series of Y_(2-x)Sm_(x)MgTiO_(6)(0≤x≤0.1)samples using a high-temperature solid-state method.X-ray diffraction(XRD)analysis confirmed a monoclinic crystal structure(space group P2_(1)∕n),with Sm^(3+)ions substituting for Y^(3+)ions in Y_(2)MgTiO_(6).The PL results indicated that the optimal doping concentration was Y_(1.95)Sm_(0.05)MgTiO_(6),exhibiting emission peaks at 568,605,652,and 715 nm under 409 nm blue light excitation.The TL measurements for different doping concentrations showed that the Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors exhibited the strongest TL signals.The TL peaks observed at 530 and 610 K correspond to defects in the matrix and Sm^(3+)dopants,respectively.The T_(m)-T_(stop)analysis revealed that the TL curve of Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors was a superposition of seven peaks.Computerized glow curve deconvolution(CGCD)was performed on the TL of the sample according to the results of three-dimensional thermoluminescence spectra(3D-TL)and T_(m)-T_(stop),and the trap depths in the sample were estimated to range from 0.69 to 1.49 eV.Additionally,the lifetimes of each overlapping peak were calculated using the fitting parameters.Furthermore,the dose-response test showed that the saturation dose of the sample was high(9956 Gy).Therefore,this material can serve as a thermoluminescent dosimeter for high-dose measurements.The saturation dose for the lowest-temperature overlapping peak was 102 Gy,which correlated with its specific energy-level lifetime,whereas the other overlapping peaks also exhibited favorable linear relationships.
