Centrifugal pumps are widely used in engineering for a variety of applications.A known drawback of these devices is the high-level noise generated during operations,which can affect their stability and adversely influ...Centrifugal pumps are widely used in engineering for a variety of applications.A known drawback of these devices is the high-level noise generated during operations,which can affect their stability and adversely influence the entire working environment.By combining the Powell vortex sound theory,numerical simulations and experimental measurements,this research explores the trends of variation and the corresponding underlying mechanisms for the flow-induced noise at various locations and under different operating conditions.It is shown that the total sound source intensity(TSSI)and total sound pressure level(TSPL)in the impeller,in the region between the inlet to the outlet and along the circumferential extension of the volute,are much higher than those at pump inlet and outlet.Additionally,under various rotational speeds with the design flow rate(Condition 1),the TSSI and TSPL at pump inlet and outlet are higher than those obtained with the opening of the valve kept unchanged(Condition 2);vice versa when these two parameters are evaluated at various locations in the impeller and the volute under the Condition 2,they exceed the equivalent values obtained for the other Condition 1.展开更多
Flow channels with a variable cross-section are important components of piping system and are widely used in variousfields of engineering.Using afinite element method and modal analysis theory,flow-induced noise,mode ...Flow channels with a variable cross-section are important components of piping system and are widely used in variousfields of engineering.Using afinite element method and modal analysis theory,flow-induced noise,mode shapes,and structure-borne noise in such systems are investigated in this study.The results demonstrate that the maximum displacement and equivalent stress are located in the part with variable cross-sectional area.The aver-age excitation force on theflow channel wall increases with theflow velocity.The maximum excitation force occurs in the range of 0–20 Hz,and then it decreases gradually in the range of 20–1000 Hz.Additionally,as theflow velocity rises from 1 to 3 m/s,the overall sound pressure level associated with theflow-induced noise grows from 49.37 to 66.37 dB.Similarly,the overall sound pressure level associated with the structure-borne noise rises from 40.27 to 72.20 dB.When theflow velocity is increased,the increment of the structure-borne noise is higher than that of theflow-induced noise.展开更多
The so-called T-shaped reducing tees are typically used to divide,change and control(to a certain extent)the flow direction in pipe networks.In this study,the Ffowcs Williams–Hawkings(FW-H)equation and the Large Eddy...The so-called T-shaped reducing tees are typically used to divide,change and control(to a certain extent)the flow direction in pipe networks.In this study,the Ffowcs Williams–Hawkings(FW-H)equation and the Large Eddy Simulation(LES)methods are used to simulate the flow-induced noise related to T-shaped reducing tees under different inlet flow velocities and for different pipe diameter ratios.The results show that the maximum flow velocity,average flow velocity,and vorticity in the branch pipe increase gradually as the related diameter decreases.Strong vorticity and secondary flows are also observed in the branch pipe,and the associated violent pressure fluctuations are found to be the main sources of flow-induced noise.In particular,as the pipe diameter ratio decreases from 1 to 0.45,the Total Sound Pressure Level(TSPL)increases by 6.8,6.26,and 7.43 dB for values of the inlet flow velocity of 1,2,and 3 m/s,respectively.The distribution characteristics of the flow-induced noise in the frequency domain follow similar trends for different pipe diameter ratios.展开更多
To obtain a better understanding the thermal stress of a rail,the thermal simulator was used to measure the expansion curves of different stresses loaded during the continuous cooling process of U75V rail.The transfor...To obtain a better understanding the thermal stress of a rail,the thermal simulator was used to measure the expansion curves of different stresses loaded during the continuous cooling process of U75V rail.The transformation plasticity model was established.The experimental results show that stress can accelerate the transformation process of pearlite.While the same cooling rate is accelerated with the increase of stress,the transformation process of pearlite is accelerated,and the proportion of plastic strain transformation in total strain increases.At the same stress,the process of transformation of pearlite decreases with the increase in cooling rate,and the proportion of transformation plastic strain in total strain decreases.When considering the transformation plasticity,the axial residual stress is more consistent with the actual working condition,the accuracy of the transformation plasticity model is higher;during the continuous cooling process,and the loading stress has a significant influence on the structure.When the stress increases,the orientation of the pearlite lamellae becomes disordered,the pearlite lamellae are bent,the lamellae spacing is no longer uniform,and the hardness is improved.展开更多
Vehicular Ad hoc Networks (VANETs) which is a special form of Mobile Ad hoc Networks (MANETs) has promising application prospects in the future. Due to the rapid changing of topology structure, how to find a route whi...Vehicular Ad hoc Networks (VANETs) which is a special form of Mobile Ad hoc Networks (MANETs) has promising application prospects in the future. Due to the rapid changing of topology structure, how to find a route which can guarantee Quality of Service (QoS) is an important issue in VANETs. This paper presents an improved Greedy Perimeter Stateless Routing (GPSR) protocol based on our proposed next-hop node selection mechanism. Firstly, we define the link reliability in two cases which take the movement direction angle between two vehicles into consideration. Then we propose a next-hop node selection mechanism based on a weighted function which consists of link reliability between the sender node and next-hop candidate node, distance between next-hop candidate node and the destination, movement direction angle of next-hop candidate node. At last, an improved GPSR protocol is proposed based on the next-hop node selection mechanism. Simulation results are presented to evaluate the performance of the improved GPSR protocol, which shows that the performance including packet delivery ratio and average end-to-end delay of the proposed protocol is better in some situations.展开更多
BACKGROUND It has been reported that vascular endothelial growth factor(VEGF)is a susceptibility gene for both type 2 diabetes mellitus(T2DM)and diabetic retinopathy(DR).In response to hypoxia,VEGF mRNA levels are inc...BACKGROUND It has been reported that vascular endothelial growth factor(VEGF)is a susceptibility gene for both type 2 diabetes mellitus(T2DM)and diabetic retinopathy(DR).In response to hypoxia,VEGF mRNA levels are increased,which is mainly mediated by the binding of hypoxia-inducible factor-1(HIF-1)and hypoxia response element upstream of the transcriptional start site of VEGF.Therefore,HIF-1a is supposed to be involved in pathology of DR.AIM To investigate whether the polymorphisms in HIF-1a gene are associated with DR.METHODS Two hundred and ninety-nine type 2 diabetic patients(128 males and 171 females)and 144 healthy volunteers were recruited.Mean age was 56.04±21.05 years.According to the results of fundus fluorescein angiography and examination of ophthalmoscopy,patients were divided into two groups,DNR group(diabetes without retinopathy)and DR group(diabetes with retinopathy).There are 150 cases in DNR group and 149 cases in DR group.Two single nucleotide polymorphisms(SNP)of the HIF-1a gene were tested using matrix-assisted laser desorption/Ionization time of flight mass spectrometry.The frequency of genotypes and alleles,and odds ratio were measured.RESULTS The mean age of the cases with diabetes was 55.84±3.66 years,the mean age of the cases with DR was 55.97±4.66 years and that of controls was 56.32±4.70 years.Two variations were found in 76 patients.Rs11549465 is the change of C-T base,rs11549467 is the change of G-A base.The rs11549467 G/A genotype was 5.33%in diabetes and 6.04%in DR patients,respectively.The rs11549465 C/T genotype was 10%and 12.75%in patients with diabetes and DR.The rs11549467 A allele frequencies and rs11549465 T frequencies was similar to that of controls.Paired SNP linkage disequilibrium analysis indicated that rs11549467 was in linkage disequilibrium with rs11549465.Haplotype association analysis denoted that the haplotype association exhibited similar distribution in the patients compared to the normal controls.CONCLUSION This study suggests that there is no relationship between the genetic variations of HIF1a and diabetes or DR.展开更多
Traditional machining methods, such as gear hobbing, gear shaping and gear milling, etc, are commonly used for cutting machining of gear tooth profile, which cannot meet huge machining demand of gears to a certain ext...Traditional machining methods, such as gear hobbing, gear shaping and gear milling, etc, are commonly used for cutting machining of gear tooth profile, which cannot meet huge machining demand of gears to a certain extent. This article proposes to utilize a face-milling machining method in involute gear machining, which can be used to reduce production cost effectively. Cutting vibration generated during cutting machining has a direct effect on the machining accuracy and machined surface quality of workpiece. Therefore, it is desiderated to perform in-depth research regarding this issue. ADAMS software was used to establish a rigid-flexible coupling virtual prototyping model of face-milling gear milling system and a cutting vibration system model. Cutting vibration analysis was performed for face-milling gear by adopting quick sine frequency sweep method, so that the frequency response characteristics of workpiece in three directions X, Y and Z and space were acquired. The research results will provide reference and theoretical foundation for actual application of face-milling gear machining technology.展开更多
A rapidly deployable dense seismic monitoring system which is capable of transmitting acquired data in real time and analyzing data automatically is crucial in seismic hazard mitigation after a major earthquake.Howeve...A rapidly deployable dense seismic monitoring system which is capable of transmitting acquired data in real time and analyzing data automatically is crucial in seismic hazard mitigation after a major earthquake.However,it is rather difficult for current seismic nodal stations to transmit data in real time for an extended period of time,and it usually takes a great amount of time to process the acquired data manually.To monitor earthquakes in real time flexibly,we develop a mobile integrated seismic monitoring system consisting of newly developed nodal units with 4G telemetry and a real-time AI-assisted automatic data processing workflow.The integrated system is convenient for deployment and has been successfully applied in monitoring the aftershocks of the Yangbi M_(S) 6.4 earthquake occurred on May 21,2021 in Yangbi County,Dali,Yunnan in southwest China.The acquired seismic data are transmitted almost in real time through the 4G cellular network,and then processed automat-ically for event detection,positioning,magnitude calculation and source mechanism inversion.From tens of seconds to a couple of minutes at most,the final seismic attributes can be presented remotely to the end users through the integrated system.From May 27 to June 17,the real-time system has detected and located 7905 aftershocks in the Yangbi area before the internal batteries exhausted,far more than the catalog provided by China Earthquake Networks Center using the regional permanent stations.The initial application of this inte-grated real-time monitoring system is promising,and we anticipate the advent of a new era for Real-time Intelligent Array Seismology(RIAS),for better monitoring and understanding the subsurface dynamic pro-cesses caused by Earth's internal forces as well as anthropogenic activities.展开更多
Electrosynthesis has gained widespread recognition for its extraordinary ability to precisely control the redox process.This outstanding capability enables the direct conversion of non-functionalized substrates into r...Electrosynthesis has gained widespread recognition for its extraordinary ability to precisely control the redox process.This outstanding capability enables the direct conversion of non-functionalized substrates into reactive intermediates by utilizing easily accessible starting materials, eliminating the need for preliminary functionalization procedures and allowing for unconventional bond activations.展开更多
Objective:To build the database of the absorbed fractions(AFs)and specific absorbed fractions(SAFs),in order to accurately assess the internal radiation dose in non-human biota.Methods:A voxel-based Portunus haanii ph...Objective:To build the database of the absorbed fractions(AFs)and specific absorbed fractions(SAFs),in order to accurately assess the internal radiation dose in non-human biota.Methods:A voxel-based Portunus haanii phantom was established based on the computed tomography(CT)images.A set of AFs and SAFs were calculated with Monte Carlo toolkit Geant4 for the emission of monoenergetic photons and electrons with energies ranging from 10 keV to 5 MeV.Results:The mass of the voxel-based Portunus haanii phantom(392.2 g)was in agreement with the actual mass(389.2 g),indicating the reliability of the phantom.The calculated AFs and SAFs,based on the voxel-based Portunus haanii phantom,provided precise and reliable data for conducting internal radiation dose calculations specifically tailored to the Chinese Red Swimming Crab(Portunus haanii).The results indicated that the self-AFs and self-SAFs were affected by both the radiation energy and the mass of the source/target organ.Moreover,the AFs and SAFs for cross irradiation,were not only dependent on the energy and the mass of the target organ,but also on the relative position of the source and target organs.Conclusion:These results serve as a valuable resource for accurately evaluating the internal radiation exposure of this species.展开更多
Hierarchical Pt-alloys enriched with active sites are highly desirable for efficient catalysis,but their syntheses generally need time-consuming and elaborate annealing treatment at high temperature.We herein report a...Hierarchical Pt-alloys enriched with active sites are highly desirable for efficient catalysis,but their syntheses generally need time-consuming and elaborate annealing treatment at high temperature.We herein report a surface active-site engineering strategy for constructing the hierarchical PtNi nanocatalysts with an atomic Pt-skin layer(PtNi@Pt-SL)towards efficient triiodide reduction reaction(TRR)via an acid-dealloying approach.The facile acid-dealloying process promotes the formation of surface Pt active sites on the hierarchical Pt-alloys,and thus results in good catalytic performance towards TRR.Theoretical calculation reveals that the enhanced catalytic property stems from the moderate energy barriers for iodide atoms on the surface Pt active-sites.The surface active-site engineering strategy paves a new way for the design of active and durable electrocatalysts.展开更多
Asymmetric electrochemical synthesis has emerged as an attractive and sustainable alternative for the distinctive activation of bond connections in the preparation of diverse enantiomerically enriched targets,includin...Asymmetric electrochemical synthesis has emerged as an attractive and sustainable alternative for the distinctive activation of bond connections in the preparation of diverse enantiomerically enriched targets,including natural products and pharmaceutical agents.Herein,we describe the chiral Lewis acid-catalyzed enantioselective electrochemical anodic coupling reaction as a key step in the presented formal synthesis of isopavine alkaloids.展开更多
基金the Key Research and Development Project of Shandong Province(2019GSF109084)Qilu University of Technology(Shandong Academy of Sciences)Young Doctors Cooperative Fund(2019BSHZ022).
文摘Centrifugal pumps are widely used in engineering for a variety of applications.A known drawback of these devices is the high-level noise generated during operations,which can affect their stability and adversely influence the entire working environment.By combining the Powell vortex sound theory,numerical simulations and experimental measurements,this research explores the trends of variation and the corresponding underlying mechanisms for the flow-induced noise at various locations and under different operating conditions.It is shown that the total sound source intensity(TSSI)and total sound pressure level(TSPL)in the impeller,in the region between the inlet to the outlet and along the circumferential extension of the volute,are much higher than those at pump inlet and outlet.Additionally,under various rotational speeds with the design flow rate(Condition 1),the TSSI and TSPL at pump inlet and outlet are higher than those obtained with the opening of the valve kept unchanged(Condition 2);vice versa when these two parameters are evaluated at various locations in the impeller and the volute under the Condition 2,they exceed the equivalent values obtained for the other Condition 1.
基金supported by the Key Research and Development Project of Shandong Province[2019GSF109084]the National Natural Science Foundation of China[51776111]Young Scholars Program of Shandong University[2018WLJH73].
文摘Flow channels with a variable cross-section are important components of piping system and are widely used in variousfields of engineering.Using afinite element method and modal analysis theory,flow-induced noise,mode shapes,and structure-borne noise in such systems are investigated in this study.The results demonstrate that the maximum displacement and equivalent stress are located in the part with variable cross-sectional area.The aver-age excitation force on theflow channel wall increases with theflow velocity.The maximum excitation force occurs in the range of 0–20 Hz,and then it decreases gradually in the range of 20–1000 Hz.Additionally,as theflow velocity rises from 1 to 3 m/s,the overall sound pressure level associated with theflow-induced noise grows from 49.37 to 66.37 dB.Similarly,the overall sound pressure level associated with the structure-borne noise rises from 40.27 to 72.20 dB.When theflow velocity is increased,the increment of the structure-borne noise is higher than that of theflow-induced noise.
基金supported by the Shandong Engineering Laboratory for High-Efficiency Energy Conservation and Energy Storage Technology&Equipment.
文摘The so-called T-shaped reducing tees are typically used to divide,change and control(to a certain extent)the flow direction in pipe networks.In this study,the Ffowcs Williams–Hawkings(FW-H)equation and the Large Eddy Simulation(LES)methods are used to simulate the flow-induced noise related to T-shaped reducing tees under different inlet flow velocities and for different pipe diameter ratios.The results show that the maximum flow velocity,average flow velocity,and vorticity in the branch pipe increase gradually as the related diameter decreases.Strong vorticity and secondary flows are also observed in the branch pipe,and the associated violent pressure fluctuations are found to be the main sources of flow-induced noise.In particular,as the pipe diameter ratio decreases from 1 to 0.45,the Total Sound Pressure Level(TSPL)increases by 6.8,6.26,and 7.43 dB for values of the inlet flow velocity of 1,2,and 3 m/s,respectively.The distribution characteristics of the flow-induced noise in the frequency domain follow similar trends for different pipe diameter ratios.
基金Funded by the Inner Mongolia Science and Technology Major Project(No.ZDZX2018024)the Natural Science Foundation of Inner Mongolia(No.2019LH05016)+1 种基金the Research Program of Science and Technology at Universities of Inner Mongolia Autonomous Region of China(No.NJZY20089)the Innovation Fund of Inner Mongolia University of Science and Technology(No.2019QDL-B06)。
文摘To obtain a better understanding the thermal stress of a rail,the thermal simulator was used to measure the expansion curves of different stresses loaded during the continuous cooling process of U75V rail.The transformation plasticity model was established.The experimental results show that stress can accelerate the transformation process of pearlite.While the same cooling rate is accelerated with the increase of stress,the transformation process of pearlite is accelerated,and the proportion of plastic strain transformation in total strain increases.At the same stress,the process of transformation of pearlite decreases with the increase in cooling rate,and the proportion of transformation plastic strain in total strain decreases.When considering the transformation plasticity,the axial residual stress is more consistent with the actual working condition,the accuracy of the transformation plasticity model is higher;during the continuous cooling process,and the loading stress has a significant influence on the structure.When the stress increases,the orientation of the pearlite lamellae becomes disordered,the pearlite lamellae are bent,the lamellae spacing is no longer uniform,and the hardness is improved.
文摘Vehicular Ad hoc Networks (VANETs) which is a special form of Mobile Ad hoc Networks (MANETs) has promising application prospects in the future. Due to the rapid changing of topology structure, how to find a route which can guarantee Quality of Service (QoS) is an important issue in VANETs. This paper presents an improved Greedy Perimeter Stateless Routing (GPSR) protocol based on our proposed next-hop node selection mechanism. Firstly, we define the link reliability in two cases which take the movement direction angle between two vehicles into consideration. Then we propose a next-hop node selection mechanism based on a weighted function which consists of link reliability between the sender node and next-hop candidate node, distance between next-hop candidate node and the destination, movement direction angle of next-hop candidate node. At last, an improved GPSR protocol is proposed based on the next-hop node selection mechanism. Simulation results are presented to evaluate the performance of the improved GPSR protocol, which shows that the performance including packet delivery ratio and average end-to-end delay of the proposed protocol is better in some situations.
文摘BACKGROUND It has been reported that vascular endothelial growth factor(VEGF)is a susceptibility gene for both type 2 diabetes mellitus(T2DM)and diabetic retinopathy(DR).In response to hypoxia,VEGF mRNA levels are increased,which is mainly mediated by the binding of hypoxia-inducible factor-1(HIF-1)and hypoxia response element upstream of the transcriptional start site of VEGF.Therefore,HIF-1a is supposed to be involved in pathology of DR.AIM To investigate whether the polymorphisms in HIF-1a gene are associated with DR.METHODS Two hundred and ninety-nine type 2 diabetic patients(128 males and 171 females)and 144 healthy volunteers were recruited.Mean age was 56.04±21.05 years.According to the results of fundus fluorescein angiography and examination of ophthalmoscopy,patients were divided into two groups,DNR group(diabetes without retinopathy)and DR group(diabetes with retinopathy).There are 150 cases in DNR group and 149 cases in DR group.Two single nucleotide polymorphisms(SNP)of the HIF-1a gene were tested using matrix-assisted laser desorption/Ionization time of flight mass spectrometry.The frequency of genotypes and alleles,and odds ratio were measured.RESULTS The mean age of the cases with diabetes was 55.84±3.66 years,the mean age of the cases with DR was 55.97±4.66 years and that of controls was 56.32±4.70 years.Two variations were found in 76 patients.Rs11549465 is the change of C-T base,rs11549467 is the change of G-A base.The rs11549467 G/A genotype was 5.33%in diabetes and 6.04%in DR patients,respectively.The rs11549465 C/T genotype was 10%and 12.75%in patients with diabetes and DR.The rs11549467 A allele frequencies and rs11549465 T frequencies was similar to that of controls.Paired SNP linkage disequilibrium analysis indicated that rs11549467 was in linkage disequilibrium with rs11549465.Haplotype association analysis denoted that the haplotype association exhibited similar distribution in the patients compared to the normal controls.CONCLUSION This study suggests that there is no relationship between the genetic variations of HIF1a and diabetes or DR.
基金financially supported by Natural Science Foundation of Liaoning Province(20170540778),People's Republic of China
文摘Traditional machining methods, such as gear hobbing, gear shaping and gear milling, etc, are commonly used for cutting machining of gear tooth profile, which cannot meet huge machining demand of gears to a certain extent. This article proposes to utilize a face-milling machining method in involute gear machining, which can be used to reduce production cost effectively. Cutting vibration generated during cutting machining has a direct effect on the machining accuracy and machined surface quality of workpiece. Therefore, it is desiderated to perform in-depth research regarding this issue. ADAMS software was used to establish a rigid-flexible coupling virtual prototyping model of face-milling gear milling system and a cutting vibration system model. Cutting vibration analysis was performed for face-milling gear by adopting quick sine frequency sweep method, so that the frequency response characteristics of workpiece in three directions X, Y and Z and space were acquired. The research results will provide reference and theoretical foundation for actual application of face-milling gear machining technology.
基金supported by the National Natural Science Foundation of China (under grants 41874048,41790464,41790462).
文摘A rapidly deployable dense seismic monitoring system which is capable of transmitting acquired data in real time and analyzing data automatically is crucial in seismic hazard mitigation after a major earthquake.However,it is rather difficult for current seismic nodal stations to transmit data in real time for an extended period of time,and it usually takes a great amount of time to process the acquired data manually.To monitor earthquakes in real time flexibly,we develop a mobile integrated seismic monitoring system consisting of newly developed nodal units with 4G telemetry and a real-time AI-assisted automatic data processing workflow.The integrated system is convenient for deployment and has been successfully applied in monitoring the aftershocks of the Yangbi M_(S) 6.4 earthquake occurred on May 21,2021 in Yangbi County,Dali,Yunnan in southwest China.The acquired seismic data are transmitted almost in real time through the 4G cellular network,and then processed automat-ically for event detection,positioning,magnitude calculation and source mechanism inversion.From tens of seconds to a couple of minutes at most,the final seismic attributes can be presented remotely to the end users through the integrated system.From May 27 to June 17,the real-time system has detected and located 7905 aftershocks in the Yangbi area before the internal batteries exhausted,far more than the catalog provided by China Earthquake Networks Center using the regional permanent stations.The initial application of this inte-grated real-time monitoring system is promising,and we anticipate the advent of a new era for Real-time Intelligent Array Seismology(RIAS),for better monitoring and understanding the subsurface dynamic pro-cesses caused by Earth's internal forces as well as anthropogenic activities.
基金supported by the National Natural Science Foundation of China(21971227,22222113)CAS Project for Young Scientists in Basic Research(YSBR-054)+1 种基金the Fundamental Research Funds for the Central Universities(WK9990000090,WK9990000111)the Chinese Postdoctoral Science Foundation(2022TQ0324,2023M733376)。
文摘Electrosynthesis has gained widespread recognition for its extraordinary ability to precisely control the redox process.This outstanding capability enables the direct conversion of non-functionalized substrates into reactive intermediates by utilizing easily accessible starting materials, eliminating the need for preliminary functionalization procedures and allowing for unconventional bond activations.
基金funded by National Natural Science Foundation of China(11905106)the Fundamental Research Funds for the Central Universities(30921013110)+1 种基金Provincial Ecological Environment Research Project of Jiangsu(2022017)the Graduate student scientific research innovation projects in Jiangsu province(SJCX22_0118),China.
文摘Objective:To build the database of the absorbed fractions(AFs)and specific absorbed fractions(SAFs),in order to accurately assess the internal radiation dose in non-human biota.Methods:A voxel-based Portunus haanii phantom was established based on the computed tomography(CT)images.A set of AFs and SAFs were calculated with Monte Carlo toolkit Geant4 for the emission of monoenergetic photons and electrons with energies ranging from 10 keV to 5 MeV.Results:The mass of the voxel-based Portunus haanii phantom(392.2 g)was in agreement with the actual mass(389.2 g),indicating the reliability of the phantom.The calculated AFs and SAFs,based on the voxel-based Portunus haanii phantom,provided precise and reliable data for conducting internal radiation dose calculations specifically tailored to the Chinese Red Swimming Crab(Portunus haanii).The results indicated that the self-AFs and self-SAFs were affected by both the radiation energy and the mass of the source/target organ.Moreover,the AFs and SAFs for cross irradiation,were not only dependent on the energy and the mass of the target organ,but also on the relative position of the source and target organs.Conclusion:These results serve as a valuable resource for accurately evaluating the internal radiation exposure of this species.
基金This research was supported Science Foundation of China 21675009）, and the Fundamenta n part by the National Natural （Grant Nos. 21475007 and Research Funds for the Central Universities （buctrc201608 and buctrc201720）.
基金The research was financially supported by the National Natural Science Foundation of China(No.21771019)the National Key Research and Development Program of China(No.2018YFA0702002)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.XK1901 and buctrc202023)P.Ma is funded by China Postdoctoral Science Foundation(No.2020M672772)。
文摘Hierarchical Pt-alloys enriched with active sites are highly desirable for efficient catalysis,but their syntheses generally need time-consuming and elaborate annealing treatment at high temperature.We herein report a surface active-site engineering strategy for constructing the hierarchical PtNi nanocatalysts with an atomic Pt-skin layer(PtNi@Pt-SL)towards efficient triiodide reduction reaction(TRR)via an acid-dealloying approach.The facile acid-dealloying process promotes the formation of surface Pt active sites on the hierarchical Pt-alloys,and thus results in good catalytic performance towards TRR.Theoretical calculation reveals that the enhanced catalytic property stems from the moderate energy barriers for iodide atoms on the surface Pt active-sites.The surface active-site engineering strategy paves a new way for the design of active and durable electrocatalysts.
基金The authors acknowledge financial support from the National Natural Science Foundation of China(grant nos.21702198 and 21971227)the Anhui Provincial Natural Science Foundation(grant no.1808085MB30)the Fundamental Research Funds for the Central Universities(no.WK2340000090).
文摘Asymmetric electrochemical synthesis has emerged as an attractive and sustainable alternative for the distinctive activation of bond connections in the preparation of diverse enantiomerically enriched targets,including natural products and pharmaceutical agents.Herein,we describe the chiral Lewis acid-catalyzed enantioselective electrochemical anodic coupling reaction as a key step in the presented formal synthesis of isopavine alkaloids.
