The Bohai Sea(BS)is the unique semi-closed inland sea of China,characterized by degraded water quality due to significant terrestrial pollution input.In order to improve its water quality,a dedicated action named“Uph...The Bohai Sea(BS)is the unique semi-closed inland sea of China,characterized by degraded water quality due to significant terrestrial pollution input.In order to improve its water quality,a dedicated action named“Uphill Battles for Integrated Bohai Sea Management”(UBIBSM,2018–2020)was implemented by the Chinese government.To evaluate the action effectiveness toward water quality improvement,variability of the satelliteobserved water transparency(Secchi disk depth,Z_(SD))was explored,with special emphasis on the nearshore waters(within 20 km from the coastline)prone to terrestrial influence.(1)Compared to the status before the action began(2011–2017),majority(87.3%)of the nearshore waters turned clear during the action implementation period(2018–2020),characterized by the elevated Z_(SD)by 11.6%±12.1%.(2)Nevertheless,the improvement was not spatially uniform,with higher Z_(SD)improvement in provinces of Hebei,Liaoning,and Shandong(13.2%±16.5%,13.2%±11.6%,10.8%±10.2%,respectively)followed by Tianjin(6.2%±4.7%).(3)Bayesian trend analysis found the abrupt Z_(SD)improvement in April 2018,which coincided with the initiation of UBIBSM,implying the water quality response to pollution control.More importantly,the independent statistics of land-based pollutant discharge also indicated that the significant reduction of terrestrial pollutant input during the UBIBSM action was the main driver of observed Z_(SD)improvement.(4)Compared with previous pollution control actions in the BS,UBIBSM was found to be the most successful one during the past 20 years,in terms of transparency improvement over nearshore waters.The presented results proved the UBIBSM-achieved remarkable water quality improvement,taking the advantage of long-term consistent and objective data record from satellite ocean color observation.展开更多
Magnesium(Mg)alloys have been widely used in automobile,aviation,computer,and other fields due to their lightweight,high specific strength and stiffness,low pollution,and good electromagnetic shielding performance.How...Magnesium(Mg)alloys have been widely used in automobile,aviation,computer,and other fields due to their lightweight,high specific strength and stiffness,low pollution,and good electromagnetic shielding performance.However,the chemical stability of Mg alloys is poor,especially in the corrosive medium environment with high stress corrosion sensitivity,which causes sudden damage to structural components and restricts their application field.In recent years,owing to the increasing failure rate of engineering structures caused by stress corrosion of Mg alloys,it has become necessary to understand and pay more attention to the stress corrosion cracking(SCC)behavior of Mg alloys.In this paper,the SCC mechanisms and test methods of Mg alloys have been summarized.The recent research progress on SCC of Mg alloys has been reviewed from the aspects of alloying,preparation process,surface modification,corrosive medium,and strain rate.More importantly,future research trends in the field of SCC of Mg alloys have also been proposed.展开更多
Grain filling influences grain size and quality in cereal crops. The molecular mechanisms that regulate grain endosperm development remain elusive. In this study, we characterized a filling-defective and grain width m...Grain filling influences grain size and quality in cereal crops. The molecular mechanisms that regulate grain endosperm development remain elusive. In this study, we characterized a filling-defective and grain width mutant, fgw1, whose mutation increased rice seed width mainly via cell division and expansion in grains. Sucrose contents were higher but starch contents lower in the fgw1 mutant during the grainfilling stage, resulting in inferior endosperm of opaque, white appearance with loosely packed starch granules. Map-based cloning revealed that FGW1 encoded a protein containing DUF630/DUF632domains, localized in the plasma membrane with preferential expression in the panicle. RNA interference in FGW1 resulted in increased grain width and weight, whereas overexpression of FGW1 led to slightly narrower kernels and better grain filling. In a yeast two-hybrid assay, FGW1 interacted directly with the 14–3–3 protein GF14f, bimolecular fluorescence complementation verified that the site of interaction was the membrane, and the mutated FGW1 protein failed to interact with GF14f. The expression of GF14f was down-regulated in fgw1, and the activities of AGPase, StSase, and SuSase in the endosperm of fgw1increased similarly to those of a reported GF14f-RNAi. Transcriptome analysis indicated that FGW1 also regulates cellular processes and carbohydrate metabolism. Thus, FGW1 regulated grain formation via the GF14f pathway.展开更多
The high-frequency(HF) communication is one of essential communication methods for military and emergency application. However, the selection of communication frequency channel is always a difficult problem as the cro...The high-frequency(HF) communication is one of essential communication methods for military and emergency application. However, the selection of communication frequency channel is always a difficult problem as the crowded spectrum, the time-varying channels, and the malicious intelligent jamming. The existing frequency hopping, automatic link establishment and some new anti-jamming technologies can not completely solve the above problems. In this article, we adopt deep reinforcement learning to solve this intractable challenge. First, the combination of the spectrum state and the channel gain state is defined as the complex environmental state, and the Markov characteristic of defined state is analyzed and proved. Then, considering that the spectrum state and channel gain state are heterogeneous information, a new deep Q network(DQN) framework is designed, which contains multiple sub-networks to process different kinds of information. Finally, aiming to improve the learning speed and efficiency, the optimization targets of corresponding sub-networks are reasonably designed, and a heterogeneous information fusion deep reinforcement learning(HIF-DRL) algorithm is designed for the specific frequency selection. Simulation results show that the proposed algorithm performs well in channel prediction, jamming avoidance and frequency channel selection.展开更多
To develop biodegradable magnesium alloy with desirable corrosion properties,a low Gd-containing Mg-3Gd-1Zn-0.4Zr(wt%,GZ31K)alloy was prepared.The as-cast ingot was solution treated and then hot extruded.Microstructur...To develop biodegradable magnesium alloy with desirable corrosion properties,a low Gd-containing Mg-3Gd-1Zn-0.4Zr(wt%,GZ31K)alloy was prepared.The as-cast ingot was solution treated and then hot extruded.Microstructures were characterized by scanning electron microscopy(SEM).Corrosion behavior of the alloy under each condition was studied by hydrogen evolution and quasi in-situ corrosion methods.It has been found that the as-cast alloy is composed ofα-Mg,stacking faults(SFs)at the outer edge of the matrix grains,and eutectic phase along the grain boundaries.After solution treatment,the SFs disappear and precipitates rich in Zn and Zr elements form in the grain interior and boundaries.The microstructure is significantly refined after extrusion.Hydrogen evolution tests show that the as-cast alloy exhibits the best corrosion resistance,and the solution-treated alloy has the worst corrosion resistance.Corrosion rate of the alloy under each condition decreases first and then increases with prolonging immersion time.Corrosion experiments demonstrate thatα-Mg was corroded preferentially,the eutectic phase and precipitates exhibit better corrosion resistance.The as-extruded alloy demonstrates uniform corrosion due to fine and homogeneous microstructure.展开更多
Corrosion is one of the most drawbacks which restricts the wide applications of Mg alloys.In the last decade,the corrosion behaviors of Mg alloys with stacking fault(SF)and/or long period stacking ordered(LPSO)structu...Corrosion is one of the most drawbacks which restricts the wide applications of Mg alloys.In the last decade,the corrosion behaviors of Mg alloys with stacking fault(SF)and/or long period stacking ordered(LPSO)structures have obtained increasing attention.However,the corrosion mechanism of the SF–or LPSO–containing Mg alloys has not been well illustrated and even reverse results have been reported.In this paper,we have reviewed recent reports on corrosion behaviors of SF–or LPSO–containing Mg alloys to better clarify and understand the significance and mechanism.Moreover,some deficiencies are presented and advises are proposed for the development of corrosion resistant Mg alloys with SF or LPSO structures.展开更多
Hydrogeochemistry and factor analysis were conducted together to assess the distribution and the major geochemical processes in fluoride-contaminated shallow groundwater in the Yuncheng Basin.Spatially,fluoride concen...Hydrogeochemistry and factor analysis were conducted together to assess the distribution and the major geochemical processes in fluoride-contaminated shallow groundwater in the Yuncheng Basin.Spatially,fluoride concentration was low(<1.5 mg/L)in the southern piedmont plain,medium(<4 mg/L)in the central basin,and high(up to 14.1 mg/L)in Kaolao lowland areas in shallow aquifers.A three-factor principal component analysis model explained over 75.1%of the total variance.Sediment weathering leaching and evapotranspiration were recognized as the first primary hydrochemical processes response for the groundwater chemistry and explained the largest portion(42.1%)of the total variance.Factor two reflects the negative influence of human activities,with a positive loading of NO3^-and HCO3^-,and negative loading of well depth.Fluoride-bearing mineral dissolution and alkaline condition was ranked as the third factors responding for groundwater chemistry and explained 11.2%of the total variance.展开更多
We optimized the extraction process of Lysurus mokusin(L.)Fr.insecticidal compound(LMIC)using response surface methodology with ultrasonic extraction(UE).The surface morphologies of maceration extract(ME)and UE residu...We optimized the extraction process of Lysurus mokusin(L.)Fr.insecticidal compound(LMIC)using response surface methodology with ultrasonic extraction(UE).The surface morphologies of maceration extract(ME)and UE residues were compared by scanning electron microscopy,and then the activity of LMIC on Lymantria dispar(Asian gypsy moths)larvae was determined.Results showed that the optimal condition of UE was followed by 80 min of extraction time,60%of ethanol concentration and 80 mL g^-1 of liquid–solid ratio.The surface morphologies of UE residue were looser and rougher than ME residue.The corrected mortalities of LMIC on L.dispar larvae was 59.77%.This result indicated that L.mokusin was a good candidate as pesticide for pest management.展开更多
Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy,and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance.Scanning e...Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy,and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance.Scanning electron microscope(SEM)and X-ray diffraction(XRD)measurements were carried out to analyze the surface morphology and phase composition.The corrosion resistance of Mg-Al hydrotalcite film after sealing treatment was evaluated by the polarization curve and electrochemical impedance spectroscopy(EIS)tests.The results showed that lower concentration of Ce-containing solution was beneficial to seal the micro-cracks on Mg-Al hydrotalcite film,and improve the surface integrity and corrosion resistance;higher concentration of Ce-containing solution could seal fewer micro-cracks,and the corrosion resistance was decreased owing to the disintegration of Mg-Al hydrotalcite film.展开更多
The friction and wear behaviors of biodegradable Mg-6Gd-0.5Zn-0.4Zr(wt%,GZ60K)alloy were evaluated under simulated body fluid(SBF)condition using ball-on-disk configuration and compared with those under dry sliding co...The friction and wear behaviors of biodegradable Mg-6Gd-0.5Zn-0.4Zr(wt%,GZ60K)alloy were evaluated under simulated body fluid(SBF)condition using ball-on-disk configuration and compared with those under dry sliding condition.The results show that under dry sliding and SBF conditions,the friction coefficient declines with increasing applied load and keeps stable with prolonging sliding time.The friction coefficient of the alloy effectively decreases in SBF as compared to dry sliding due to lubrication caused by SBF.The real wear rates under SBF condition are lower than those under dry sliding condition for each parameter.Nevertheless,the nominal wear rates are higher in SBF which are attributed to the more mass loss caused by corrosion but not wear.Both the nominal wear rate in SBF and the dry sliding wear rate increase with increasing applied load,and they decline firstly and then keep stable with prolonging sliding time.It is concluded that the wear of the alloy is restricted by the SBF,but the corrosion of the alloy is aggravated by the wear.展开更多
In order to study the effects of Nd addition on microstructure and mechanical properties of Mg-Gd-Zn-Zr alloys,the microstruc-ture and mechanical properties of the as-cast Mg-12Gd-2Zn-xNd-0.4Zr(x=0,0.5wt%,and 1wt%)all...In order to study the effects of Nd addition on microstructure and mechanical properties of Mg-Gd-Zn-Zr alloys,the microstruc-ture and mechanical properties of the as-cast Mg-12Gd-2Zn-xNd-0.4Zr(x=0,0.5wt%,and 1wt%)alloys were investigated by using optical microscope,scanning electron microscope,X-ray diffractometer,nano indentation tester,microhardness tester,and tensile testing machine.The results show that the microstructures mainly consist ofα-Mg matrix,eutectic phase,and stacking faults.The addition of Nd plays a significant role in grain refinement and uniform microstructure.The tensile yield strength and microhardness increase but the compression yield strength decreases with increasing Nd addition,leading to weakening tension-compression yield asymmetry in reverse of the Mg-12Gd-2Zn-xNd-0.4Zr alloys.The highest ultimate tensile strength(194 MPa)and ultimate compression strength(397 MPa)are obtained with 1wt%Nd addition of the alloy.展开更多
This paper mainly investigates the coordinated anti-jamming channel access problems in multiuser scenarios where there exists a tracking jammer who senses the spectrum and traces the channel with maximal receiving pow...This paper mainly investigates the coordinated anti-jamming channel access problems in multiuser scenarios where there exists a tracking jammer who senses the spectrum and traces the channel with maximal receiving power.To cope with the challenges brought by the tracking jammer,a multi-leader onefollower anti-jamming Stackelberg(MOAS)game is formulated,which is able to model the complex interactions between users and the tracking jammer.In the proposed game,users act as leaders,chose their channel access strategies and transmit firstly.The tracking jammer acts as the follower,whose objective is to find the optimal jamming strategy at each time slot.Besides,the existence of Stackelberg equilibriums(SEs)is proved,which means users reach Nash Equilibriums(NEs)for each jamming strategy while the jammer finds its best response jamming strategy for the current network access case.An active attraction based anti-jamming channel access(3ACA)algorithm is designed to reach SEs,where jammed users keep their channel access strategies unchanged to create access chances for other users.To enhance the fairness of the system,users will adjust their strategies and relearn after certain time slots to provide access chances for those users who sacrifice themselves to attract the tracking jammer.展开更多
Reservoir temperature estimation is vitally important for assessing the exploitation potential of a geothermal field.In this study,the concentrations of major chemical constituents in geothermal water sampled from boi...Reservoir temperature estimation is vitally important for assessing the exploitation potential of a geothermal field.In this study,the concentrations of major chemical constituents in geothermal water sampled from boiling and hot springs in the Tengchong hydrothermal area were measured,and quartz and cationic solutes geothermometers were used to calculate subsurface temperatures.Log(Q/K) diagrams and Na-K-Mg triangular diagrams were applied to evaluating the equilibrium status of geothermal water samples with regard to reservoir minerals,and results were used to select suitable geothermometers.The results show that samples RH01,RH03,RH04,RH05,and LL16 were in or very close to full equilibrium with the selected minerals,and therefore a NaK geothermometer is appropriate.A K/Mg geothermometer,however,is applicable to LP08 and PZH18 whose chemical compositions adjusted to the shallow reservoir temperatures during their re-equilibrium processes.In contrast,cationic solute geothermometers are unsuitable for SQ20 and RH07,which are categorized as immature water in the Na-K-Mg diagram;a quartz geothermometer was adopted to evaluate the corresponding subsurface temperatures of these samples.According to the reservoir temperature estimation made in this study,there is at least one high-temperature reservoir below Rehai with a possible temperature range of 210-270 ℃.展开更多
DNA polymerase δ(Polδ)plays a crucial and versatile role in DNA replication and DNA repair processes.Vent shrimp Rimicaris exoculata is the primary megafaunal community living in hydrothermal vents.In this study,the...DNA polymerase δ(Polδ)plays a crucial and versatile role in DNA replication and DNA repair processes.Vent shrimp Rimicaris exoculata is the primary megafaunal community living in hydrothermal vents.In this study,the Polδfrom shrimp Rimicaris exoculata was cloned,expressed and characterized.The results showed that the Polδcatalytic subunit(POLD1),852 amino acids in length,shared high homology with crayfish Procambarus clarkii and shrimp Oratosquilla oratoria.The recombinant POLD1 expressed in Escherichia coli showed that the enzyme was active in a range of 20℃ to 40℃ with an optimum temperature at 25℃ and in a wide range of p H with an optimum at pH 6.0.The activities of POLD1 were significantly enhanced in the presence of Triton-X 100,Tween 20 and Mn^(2+).The K_(m)(dNTP)value of POLD1 was 4.7μmol/L.The present study would be helpful to reveal the characterization of Polδof deep-sea vent animals.展开更多
In J-TEXT tokamak,fast electron bremsstrahlung diagnostic with 9 chords equipped with multichannel analyzer enables detailed studies of the generation and transport of fast electrons.The spatial profiles and energy sp...In J-TEXT tokamak,fast electron bremsstrahlung diagnostic with 9 chords equipped with multichannel analyzer enables detailed studies of the generation and transport of fast electrons.The spatial profiles and energy spectrum of the fast electrons have been measured in two ECCD cases with either on-axis or off-axis injection,and the profiles processed by Abel-inversion are consistent with the calculated power deposition locations.Moreover,it is observed that the energy of fast electrons increases rapidly after turning off the ECCD,which may be attributed to the acceleration by the recovered loop voltage at low electron density.展开更多
The avoidance of runaway electrons(REs) generated during plasma disruption is of great concern for the safe operation of tokamak devices.Experimental study on the suppression of runaway current by electrode biasing(EB...The avoidance of runaway electrons(REs) generated during plasma disruption is of great concern for the safe operation of tokamak devices.Experimental study on the suppression of runaway current by electrode biasing(EB) and limiter biasing(LB) has been performed on the J-TEXT tokamak,which could be an alternative way to suppress the runaway current.The experimental results show that the higher the voltage value,the smaller the runaway current in both EB and LB experiments.The runaway current can be completely suppressed at an electrode biased voltage of +450 V and a limiter biased voltage of +300 V.The comparison of the energy spectra during the runaway plateau phase shows that the maximum energy max(E_(RE)) and radiation temperature T_(HXR)hard x-rays(HXRs)are significantly reduced after the application of +200 V limiter biased voltage.The electric field generated by the biased voltage may be the key factor to suppress the runaway current,and the measured radial electric field increases obviously after the voltage is applied.This may result in an increase in the loss of REs to realize the suppression of runaway current.展开更多
Electron cyclotron current drive(ECCD) efficiency research is of great importance for the neoclassical tearing mode(NTM) stabilization.Improving ECCD efficiency is beneficial for the NTM stabilization and the ECCD pow...Electron cyclotron current drive(ECCD) efficiency research is of great importance for the neoclassical tearing mode(NTM) stabilization.Improving ECCD efficiency is beneficial for the NTM stabilization and the ECCD power threshold reduction.ECCD efficiency has been investigated on the J-TEXT tokamak.The electron cyclotron wave(ECW) power scan was performed to obtain the current drive efficiency.The current drive efficiency is derived to be approximately η_(0)=(0.06-0.16)×10^(19)A m^(-2)W^(-1)on the J-TEXT tokamak.The effect of the residual toroidal electric field has been included in the determination of the current drive efficiency,which will enhance the ECCD efficiency.At the plasma current of I_(p)=100 kA and electron density of n_(e)=1.5×10^(19)m^(-3),the ratio of Spitzer conductivity between omhic(OH)and ECCD phases is considered and the experimental data have been corrected.The correction results show that the current drive efficiency η_(1)caused by the fast electron hot conductivity decreases by approximately 79%.It can be estimated that the driven current is approximately 24 kA at 300 kW ECW power.展开更多
The spatially modulated electron distribution of plasma is the basis for obtaining programmable electron density patterns.It has an important influence on plasma technology applications.We propose an efficient scheme ...The spatially modulated electron distribution of plasma is the basis for obtaining programmable electron density patterns.It has an important influence on plasma technology applications.We propose an efficient scheme to realize controllable electron density patterns in underdense plasma based on the array laser-plasma interaction.Theoretical evidence for the realization of programmable electron density patterns and the corresponding electrostatic field is provided analytically,which is confirmed by particle-in-cell simulations.Results show that the spatial distribution of electron density in the propagation and transverse directions of the laser can be highly modulated to obtain rich programmable electron density patterns by adjusting the array pattern code and pulse width of the array laser beam.展开更多
Dry eye disease is the most prevalent ocular surface disease in eye clinics.The deficiency of tears is regarded as one of the main pathogenic factors for this disease.Due to the fact that the components of tears are s...Dry eye disease is the most prevalent ocular surface disease in eye clinics.The deficiency of tears is regarded as one of the main pathogenic factors for this disease.Due to the fact that the components of tears are still far beyond our knowledge,the restoration of physiological tears remains the optimum choice for dry eye patients.However,the traditional way to stimulate tear production by systemic administration of muscarinic agonists usually encounters severe side effects.Recently,Nakamachi and colleagues reported that PACAP,a native neurotransmitter present in tear fluid,could stimulate main lacrimal gland secretion and relieve dry eye-like symptoms in PACAP knockout mice.The finding of PACAP and its underlying mechanisms suggest a new modality for dry eye treatment via targeted topical tear stimulations.展开更多
基金The fund supported by Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) under contract No. SML2021SP313the fundamental research funds for the Central Universities of Sun Yat-Sen University under contract No.23xkjc019the fund supported by China-Korea Joint Ocean Research Center of China under contract No. PI-2022-1-01
文摘The Bohai Sea(BS)is the unique semi-closed inland sea of China,characterized by degraded water quality due to significant terrestrial pollution input.In order to improve its water quality,a dedicated action named“Uphill Battles for Integrated Bohai Sea Management”(UBIBSM,2018–2020)was implemented by the Chinese government.To evaluate the action effectiveness toward water quality improvement,variability of the satelliteobserved water transparency(Secchi disk depth,Z_(SD))was explored,with special emphasis on the nearshore waters(within 20 km from the coastline)prone to terrestrial influence.(1)Compared to the status before the action began(2011–2017),majority(87.3%)of the nearshore waters turned clear during the action implementation period(2018–2020),characterized by the elevated Z_(SD)by 11.6%±12.1%.(2)Nevertheless,the improvement was not spatially uniform,with higher Z_(SD)improvement in provinces of Hebei,Liaoning,and Shandong(13.2%±16.5%,13.2%±11.6%,10.8%±10.2%,respectively)followed by Tianjin(6.2%±4.7%).(3)Bayesian trend analysis found the abrupt Z_(SD)improvement in April 2018,which coincided with the initiation of UBIBSM,implying the water quality response to pollution control.More importantly,the independent statistics of land-based pollutant discharge also indicated that the significant reduction of terrestrial pollutant input during the UBIBSM action was the main driver of observed Z_(SD)improvement.(4)Compared with previous pollution control actions in the BS,UBIBSM was found to be the most successful one during the past 20 years,in terms of transparency improvement over nearshore waters.The presented results proved the UBIBSM-achieved remarkable water quality improvement,taking the advantage of long-term consistent and objective data record from satellite ocean color observation.
基金supported by the National Natural Science Foundation of China(52071175)the Key Research&Development Plan(Social Development)of Jiangsu Province(BE2020702)。
文摘Magnesium(Mg)alloys have been widely used in automobile,aviation,computer,and other fields due to their lightweight,high specific strength and stiffness,low pollution,and good electromagnetic shielding performance.However,the chemical stability of Mg alloys is poor,especially in the corrosive medium environment with high stress corrosion sensitivity,which causes sudden damage to structural components and restricts their application field.In recent years,owing to the increasing failure rate of engineering structures caused by stress corrosion of Mg alloys,it has become necessary to understand and pay more attention to the stress corrosion cracking(SCC)behavior of Mg alloys.In this paper,the SCC mechanisms and test methods of Mg alloys have been summarized.The recent research progress on SCC of Mg alloys has been reviewed from the aspects of alloying,preparation process,surface modification,corrosive medium,and strain rate.More importantly,future research trends in the field of SCC of Mg alloys have also been proposed.
基金sponsored by the National Key Research and Development Program of China(2022YFD1201600, 2016YFD0100501)Natural Science Foundation of Chongqing of China (cstc2020jcyj-msxm0539)+1 种基金the National Natural Science Foundation of China (32171964)Chongqing Natural Science Foundation Innovation Group (cstc2021jcyjcxttX0004)。
文摘Grain filling influences grain size and quality in cereal crops. The molecular mechanisms that regulate grain endosperm development remain elusive. In this study, we characterized a filling-defective and grain width mutant, fgw1, whose mutation increased rice seed width mainly via cell division and expansion in grains. Sucrose contents were higher but starch contents lower in the fgw1 mutant during the grainfilling stage, resulting in inferior endosperm of opaque, white appearance with loosely packed starch granules. Map-based cloning revealed that FGW1 encoded a protein containing DUF630/DUF632domains, localized in the plasma membrane with preferential expression in the panicle. RNA interference in FGW1 resulted in increased grain width and weight, whereas overexpression of FGW1 led to slightly narrower kernels and better grain filling. In a yeast two-hybrid assay, FGW1 interacted directly with the 14–3–3 protein GF14f, bimolecular fluorescence complementation verified that the site of interaction was the membrane, and the mutated FGW1 protein failed to interact with GF14f. The expression of GF14f was down-regulated in fgw1, and the activities of AGPase, StSase, and SuSase in the endosperm of fgw1increased similarly to those of a reported GF14f-RNAi. Transcriptome analysis indicated that FGW1 also regulates cellular processes and carbohydrate metabolism. Thus, FGW1 regulated grain formation via the GF14f pathway.
基金supported by Guangxi key Laboratory Fund of Embedded Technology and Intelligent System under Grant No. 2018B-1the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province under Grant No. BK20160034+1 种基金the National Natural Science Foundation of China under Grant No. 61771488, No. 61671473 and No. 61631020in part by the Open Research Foundation of Science and Technology on Communication Networks Laboratory
文摘The high-frequency(HF) communication is one of essential communication methods for military and emergency application. However, the selection of communication frequency channel is always a difficult problem as the crowded spectrum, the time-varying channels, and the malicious intelligent jamming. The existing frequency hopping, automatic link establishment and some new anti-jamming technologies can not completely solve the above problems. In this article, we adopt deep reinforcement learning to solve this intractable challenge. First, the combination of the spectrum state and the channel gain state is defined as the complex environmental state, and the Markov characteristic of defined state is analyzed and proved. Then, considering that the spectrum state and channel gain state are heterogeneous information, a new deep Q network(DQN) framework is designed, which contains multiple sub-networks to process different kinds of information. Finally, aiming to improve the learning speed and efficiency, the optimization targets of corresponding sub-networks are reasonably designed, and a heterogeneous information fusion deep reinforcement learning(HIF-DRL) algorithm is designed for the specific frequency selection. Simulation results show that the proposed algorithm performs well in channel prediction, jamming avoidance and frequency channel selection.
基金This project was supported by the Natural Science Foundation of Jiangsu Province for Outstanding Youth(BK20160081)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province-Key Project(18KJA430008)+2 种基金the Jiangsu Government Scholarship for Overseas Studies,the“333 Project”of Jiangsu Province(BRA2018338)the National Natural Science Foundation of China(51701093)the Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu Province.
文摘To develop biodegradable magnesium alloy with desirable corrosion properties,a low Gd-containing Mg-3Gd-1Zn-0.4Zr(wt%,GZ31K)alloy was prepared.The as-cast ingot was solution treated and then hot extruded.Microstructures were characterized by scanning electron microscopy(SEM).Corrosion behavior of the alloy under each condition was studied by hydrogen evolution and quasi in-situ corrosion methods.It has been found that the as-cast alloy is composed ofα-Mg,stacking faults(SFs)at the outer edge of the matrix grains,and eutectic phase along the grain boundaries.After solution treatment,the SFs disappear and precipitates rich in Zn and Zr elements form in the grain interior and boundaries.The microstructure is significantly refined after extrusion.Hydrogen evolution tests show that the as-cast alloy exhibits the best corrosion resistance,and the solution-treated alloy has the worst corrosion resistance.Corrosion rate of the alloy under each condition decreases first and then increases with prolonging immersion time.Corrosion experiments demonstrate thatα-Mg was corroded preferentially,the eutectic phase and precipitates exhibit better corrosion resistance.The as-extruded alloy demonstrates uniform corrosion due to fine and homogeneous microstructure.
基金This project was supported by the Natural Science Foundation of Jiangsu Province for Outstanding Youth(BK20160081)the Natural Science Foundation of Jiangsu Province(BK20181020)+2 种基金the Natural Science Foundation of Higher Education Institutions of Jiangsu Province–Key Project(18KJA430008)the“333 Project”of Jiangsu Province(BRA2018338)the Practical Innovative Project for Postgraduates of Jiangsu Province(SJCX19_0493).
文摘Corrosion is one of the most drawbacks which restricts the wide applications of Mg alloys.In the last decade,the corrosion behaviors of Mg alloys with stacking fault(SF)and/or long period stacking ordered(LPSO)structures have obtained increasing attention.However,the corrosion mechanism of the SF–or LPSO–containing Mg alloys has not been well illustrated and even reverse results have been reported.In this paper,we have reviewed recent reports on corrosion behaviors of SF–or LPSO–containing Mg alloys to better clarify and understand the significance and mechanism.Moreover,some deficiencies are presented and advises are proposed for the development of corrosion resistant Mg alloys with SF or LPSO structures.
基金financially supported by the National Natural Science Foundation of China(41877204)Foundation for Innovative Research Groups of the National Natural Science Foundation of China(41521001)the China Postdoctoral Science Foundation(2018M642944)。
文摘Hydrogeochemistry and factor analysis were conducted together to assess the distribution and the major geochemical processes in fluoride-contaminated shallow groundwater in the Yuncheng Basin.Spatially,fluoride concentration was low(<1.5 mg/L)in the southern piedmont plain,medium(<4 mg/L)in the central basin,and high(up to 14.1 mg/L)in Kaolao lowland areas in shallow aquifers.A three-factor principal component analysis model explained over 75.1%of the total variance.Sediment weathering leaching and evapotranspiration were recognized as the first primary hydrochemical processes response for the groundwater chemistry and explained the largest portion(42.1%)of the total variance.Factor two reflects the negative influence of human activities,with a positive loading of NO3^-and HCO3^-,and negative loading of well depth.Fluoride-bearing mineral dissolution and alkaline condition was ranked as the third factors responding for groundwater chemistry and explained 11.2%of the total variance.
基金The work was supported by the Central University Fundamental Research Funds Special Fund Project[2572016AA03,25720171118]Harbin Applied Technology Research and Development Project[2016RAXXJ035]the Central Financial Forest Science and Technology Promotion Demonstration Fund Project[JLT[2016]13].
文摘We optimized the extraction process of Lysurus mokusin(L.)Fr.insecticidal compound(LMIC)using response surface methodology with ultrasonic extraction(UE).The surface morphologies of maceration extract(ME)and UE residues were compared by scanning electron microscopy,and then the activity of LMIC on Lymantria dispar(Asian gypsy moths)larvae was determined.Results showed that the optimal condition of UE was followed by 80 min of extraction time,60%of ethanol concentration and 80 mL g^-1 of liquid–solid ratio.The surface morphologies of UE residue were looser and rougher than ME residue.The corrected mortalities of LMIC on L.dispar larvae was 59.77%.This result indicated that L.mokusin was a good candidate as pesticide for pest management.
基金supported by the National Natural Science Foundation of China(No.51701093)the Natural Science Foundation of Jiangsu Province(No.BK20170764)+2 种基金the Six Talent Peaks(No.2015-XCL-025)the Qing Lan Project of Jiangsu Province,the Practice Innovation Program for graduate students of Jiangsu Province(No.SJZZ16_0292)the Research Fund of Nanjing Institute of Technology(No.JCYJ201603).
文摘Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy,and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance.Scanning electron microscope(SEM)and X-ray diffraction(XRD)measurements were carried out to analyze the surface morphology and phase composition.The corrosion resistance of Mg-Al hydrotalcite film after sealing treatment was evaluated by the polarization curve and electrochemical impedance spectroscopy(EIS)tests.The results showed that lower concentration of Ce-containing solution was beneficial to seal the micro-cracks on Mg-Al hydrotalcite film,and improve the surface integrity and corrosion resistance;higher concentration of Ce-containing solution could seal fewer micro-cracks,and the corrosion resistance was decreased owing to the disintegration of Mg-Al hydrotalcite film.
基金supported by the Natural Science Foundation of Jiangsu Province for Outstanding Youth(BK20160081)the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(ASMA201503)+1 种基金the Innovative Foundation Project for Students of Nanjing Institute of Technology(TP20170011)the Six Talent Peaks(2015-XCL-025)of Jiangsu Province,and the Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu Province.
文摘The friction and wear behaviors of biodegradable Mg-6Gd-0.5Zn-0.4Zr(wt%,GZ60K)alloy were evaluated under simulated body fluid(SBF)condition using ball-on-disk configuration and compared with those under dry sliding condition.The results show that under dry sliding and SBF conditions,the friction coefficient declines with increasing applied load and keeps stable with prolonging sliding time.The friction coefficient of the alloy effectively decreases in SBF as compared to dry sliding due to lubrication caused by SBF.The real wear rates under SBF condition are lower than those under dry sliding condition for each parameter.Nevertheless,the nominal wear rates are higher in SBF which are attributed to the more mass loss caused by corrosion but not wear.Both the nominal wear rate in SBF and the dry sliding wear rate increase with increasing applied load,and they decline firstly and then keep stable with prolonging sliding time.It is concluded that the wear of the alloy is restricted by the SBF,but the corrosion of the alloy is aggravated by the wear.
基金This work was financially supported by the National Natural Science Foundation of China(No.52071175)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province-Key Project,China(No.18KJA430008)+1 种基金the Key Research&Development Plan(Social Development)of Jiangsu Province,China(No.BE2020702)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX21_0923).
文摘In order to study the effects of Nd addition on microstructure and mechanical properties of Mg-Gd-Zn-Zr alloys,the microstruc-ture and mechanical properties of the as-cast Mg-12Gd-2Zn-xNd-0.4Zr(x=0,0.5wt%,and 1wt%)alloys were investigated by using optical microscope,scanning electron microscope,X-ray diffractometer,nano indentation tester,microhardness tester,and tensile testing machine.The results show that the microstructures mainly consist ofα-Mg matrix,eutectic phase,and stacking faults.The addition of Nd plays a significant role in grain refinement and uniform microstructure.The tensile yield strength and microhardness increase but the compression yield strength decreases with increasing Nd addition,leading to weakening tension-compression yield asymmetry in reverse of the Mg-12Gd-2Zn-xNd-0.4Zr alloys.The highest ultimate tensile strength(194 MPa)and ultimate compression strength(397 MPa)are obtained with 1wt%Nd addition of the alloy.
文摘This paper mainly investigates the coordinated anti-jamming channel access problems in multiuser scenarios where there exists a tracking jammer who senses the spectrum and traces the channel with maximal receiving power.To cope with the challenges brought by the tracking jammer,a multi-leader onefollower anti-jamming Stackelberg(MOAS)game is formulated,which is able to model the complex interactions between users and the tracking jammer.In the proposed game,users act as leaders,chose their channel access strategies and transmit firstly.The tracking jammer acts as the follower,whose objective is to find the optimal jamming strategy at each time slot.Besides,the existence of Stackelberg equilibriums(SEs)is proved,which means users reach Nash Equilibriums(NEs)for each jamming strategy while the jammer finds its best response jamming strategy for the current network access case.An active attraction based anti-jamming channel access(3ACA)algorithm is designed to reach SEs,where jammed users keep their channel access strategies unchanged to create access chances for other users.To enhance the fairness of the system,users will adjust their strategies and relearn after certain time slots to provide access chances for those users who sacrifice themselves to attract the tracking jammer.
基金supported by the National Natural Science Foundation of China(No.41120124003)the Ministry of Education of China(111 Project,No.B08030)+1 种基金the Research fund of Bureau of Science and Technology of Qinghai Province(No.2013-G-Q08A)the Fundamental Research Fund for National Universities,China University of Geosciences(Wuhan) (Nos.CUG120505 and CUG120113)
文摘Reservoir temperature estimation is vitally important for assessing the exploitation potential of a geothermal field.In this study,the concentrations of major chemical constituents in geothermal water sampled from boiling and hot springs in the Tengchong hydrothermal area were measured,and quartz and cationic solutes geothermometers were used to calculate subsurface temperatures.Log(Q/K) diagrams and Na-K-Mg triangular diagrams were applied to evaluating the equilibrium status of geothermal water samples with regard to reservoir minerals,and results were used to select suitable geothermometers.The results show that samples RH01,RH03,RH04,RH05,and LL16 were in or very close to full equilibrium with the selected minerals,and therefore a NaK geothermometer is appropriate.A K/Mg geothermometer,however,is applicable to LP08 and PZH18 whose chemical compositions adjusted to the shallow reservoir temperatures during their re-equilibrium processes.In contrast,cationic solute geothermometers are unsuitable for SQ20 and RH07,which are categorized as immature water in the Na-K-Mg diagram;a quartz geothermometer was adopted to evaluate the corresponding subsurface temperatures of these samples.According to the reservoir temperature estimation made in this study,there is at least one high-temperature reservoir below Rehai with a possible temperature range of 210-270 ℃.
基金The National Basic Research Program of China under contract No.2015CB755903the National Natural Science Foundation of China under contract Nos U1605214 and 31470133the Foundation of Quanzhou Normal University under contract No.2016YYKJ16。
文摘DNA polymerase δ(Polδ)plays a crucial and versatile role in DNA replication and DNA repair processes.Vent shrimp Rimicaris exoculata is the primary megafaunal community living in hydrothermal vents.In this study,the Polδfrom shrimp Rimicaris exoculata was cloned,expressed and characterized.The results showed that the Polδcatalytic subunit(POLD1),852 amino acids in length,shared high homology with crayfish Procambarus clarkii and shrimp Oratosquilla oratoria.The recombinant POLD1 expressed in Escherichia coli showed that the enzyme was active in a range of 20℃ to 40℃ with an optimum temperature at 25℃ and in a wide range of p H with an optimum at pH 6.0.The activities of POLD1 were significantly enhanced in the presence of Triton-X 100,Tween 20 and Mn^(2+).The K_(m)(dNTP)value of POLD1 was 4.7μmol/L.The present study would be helpful to reveal the characterization of Polδof deep-sea vent animals.
基金the National Key R&D Program of China(Nos.2017YFE0302000,2018YFE0309103,2019YFE030-10004,2017YFE0300501,2018YFE0310300,2018YFE0309100)National Natural Science Foundation of China(Nos.11775089,51821005,11905077 and 11575068)the China Postdoctoral Science Foundation(No.2019M652615)。
文摘In J-TEXT tokamak,fast electron bremsstrahlung diagnostic with 9 chords equipped with multichannel analyzer enables detailed studies of the generation and transport of fast electrons.The spatial profiles and energy spectrum of the fast electrons have been measured in two ECCD cases with either on-axis or off-axis injection,and the profiles processed by Abel-inversion are consistent with the calculated power deposition locations.Moreover,it is observed that the energy of fast electrons increases rapidly after turning off the ECCD,which may be attributed to the acceleration by the recovered loop voltage at low electron density.
基金supported by National MCF Energy R&D Program of China(No.2019YFE03010004)National Key R&D Program of China(No.2018YFE0309100)+1 种基金National Natural Science Foundation of China(Nos.11775089 and 51821005)National Magnetic Confinement Fusion Science Program of China(Nos.2015GB111002 and 2015GB104000)
文摘The avoidance of runaway electrons(REs) generated during plasma disruption is of great concern for the safe operation of tokamak devices.Experimental study on the suppression of runaway current by electrode biasing(EB) and limiter biasing(LB) has been performed on the J-TEXT tokamak,which could be an alternative way to suppress the runaway current.The experimental results show that the higher the voltage value,the smaller the runaway current in both EB and LB experiments.The runaway current can be completely suppressed at an electrode biased voltage of +450 V and a limiter biased voltage of +300 V.The comparison of the energy spectra during the runaway plateau phase shows that the maximum energy max(E_(RE)) and radiation temperature T_(HXR)hard x-rays(HXRs)are significantly reduced after the application of +200 V limiter biased voltage.The electric field generated by the biased voltage may be the key factor to suppress the runaway current,and the measured radial electric field increases obviously after the voltage is applied.This may result in an increase in the loss of REs to realize the suppression of runaway current.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China(No.2019YFE03010004)the National Key R&D Program ofChina(No.2018YFE0309100)National Natural Science Foundation of China(Nos.11775089,11905077,51821005)
文摘Electron cyclotron current drive(ECCD) efficiency research is of great importance for the neoclassical tearing mode(NTM) stabilization.Improving ECCD efficiency is beneficial for the NTM stabilization and the ECCD power threshold reduction.ECCD efficiency has been investigated on the J-TEXT tokamak.The electron cyclotron wave(ECW) power scan was performed to obtain the current drive efficiency.The current drive efficiency is derived to be approximately η_(0)=(0.06-0.16)×10^(19)A m^(-2)W^(-1)on the J-TEXT tokamak.The effect of the residual toroidal electric field has been included in the determination of the current drive efficiency,which will enhance the ECCD efficiency.At the plasma current of I_(p)=100 kA and electron density of n_(e)=1.5×10^(19)m^(-3),the ratio of Spitzer conductivity between omhic(OH)and ECCD phases is considered and the experimental data have been corrected.The correction results show that the current drive efficiency η_(1)caused by the fast electron hot conductivity decreases by approximately 79%.It can be estimated that the driven current is approximately 24 kA at 300 kW ECW power.
基金supported by National Natural Science Foundation of China(Nos.11865014,11765017,11764039,11475027,11274255,and 11305132)the Natural Science Foundation of Gansu Province(No.17JR5RA076)by the Scientific Research Project of Gansu Higher Education(No.2016A-005)。
文摘The spatially modulated electron distribution of plasma is the basis for obtaining programmable electron density patterns.It has an important influence on plasma technology applications.We propose an efficient scheme to realize controllable electron density patterns in underdense plasma based on the array laser-plasma interaction.Theoretical evidence for the realization of programmable electron density patterns and the corresponding electrostatic field is provided analytically,which is confirmed by particle-in-cell simulations.Results show that the spatial distribution of electron density in the propagation and transverse directions of the laser can be highly modulated to obtain rich programmable electron density patterns by adjusting the array pattern code and pulse width of the array laser beam.
文摘Dry eye disease is the most prevalent ocular surface disease in eye clinics.The deficiency of tears is regarded as one of the main pathogenic factors for this disease.Due to the fact that the components of tears are still far beyond our knowledge,the restoration of physiological tears remains the optimum choice for dry eye patients.However,the traditional way to stimulate tear production by systemic administration of muscarinic agonists usually encounters severe side effects.Recently,Nakamachi and colleagues reported that PACAP,a native neurotransmitter present in tear fluid,could stimulate main lacrimal gland secretion and relieve dry eye-like symptoms in PACAP knockout mice.The finding of PACAP and its underlying mechanisms suggest a new modality for dry eye treatment via targeted topical tear stimulations.
