The joining of DP780 steel to Al5052 was conducted by laser lap welding,in which the metal vapor and spatters were monitored by a high-speed camera.A universal testing machine was used to test the mechanical propertie...The joining of DP780 steel to Al5052 was conducted by laser lap welding,in which the metal vapor and spatters were monitored by a high-speed camera.A universal testing machine was used to test the mechanical properties of the welded joints,and the changing law of lap tensile resistance with the laser welding parameters was analyzed.Optical microscope and scanning electron microscope were used to observe the macro-structure and micro-structure,respectively.Three different intermetallic compounds(IMCs)phases,i.e.banded Fe2Al5,FeAl2 and needle-like FeAl3 were generated at the steel/Al interface on microscopic observation.The aim of this research is to investigate the relationship among the lap tensile resistance,the welding parameters and the failure mode under different energy densities.Experimental results showed that the steel/Al joints have two different fracture modes at low heat input and high heat input.The failures happened along the heat-affected zone of the weld and along the steel/Al joint interface,respectively.And both of the two failure modes are brittle fractures.Additionally,cracks appeared at the fracture interface,and needle-like particle clusters were found in the fracture microstructure.展开更多
The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application res...The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application research in various areas,such as the early detection of breast tumors and cerebrovascular diseases.However,the microwave generator used in the traditional TAI technology is huge and expensive,and the temporal resolution is also too low due to the single-element scanning mechanism.Thus,it is difficult to meet the needs of clinical applications.In this paper,the iterative process and the analysis of related application scenarios from single-element scanning to portable and array-based TAI,such as the miniaturized microwave generator,handheld antenna,multi-channel data acquisition,and UI/TAIdual-modality imaging,are reviewed,and the future trends of this technology are discussed.This review helps researchers in the field of TAI learn the technological development process and future trends.It also deepens clinicians’understanding of TAI so as to put forward more application requirements.展开更多
Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here w...Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15,which encodes the Multidrug and Toxic Extru-sion(MATE)transporter DTX6.A point mutation at+932 bp in DTX6 causes a G311E amino acid substitution,enhancing the paraquat resistance ofpqt15-D,and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance.Moreover,heterologous expression of DTX6 and DTX6-D in Es-cherichia coil significantly enhances bacterial resistance to paraquat.Importantly,overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat,a near-commercial application level.DTX6/PQT15 is localized in the plasma membrane and endomembrane,and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells.Taken together,our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resis-tance by exporting paraquat out of the cytosol.These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.展开更多
Objective To investigate the influence of electroacupuncture(EA)on ghrelin and the phosphoinositide 3-kinase/protein kinase B/endothelial nitric oxide synthase(PI3K/Akt/eNOS)signaling pathway in spontaneously hyperten...Objective To investigate the influence of electroacupuncture(EA)on ghrelin and the phosphoinositide 3-kinase/protein kinase B/endothelial nitric oxide synthase(PI3K/Akt/eNOS)signaling pathway in spontaneously hypertensive rats(SHRs).Methods Eight Wistar-Kyoto rats were used as the healthy blood pressure(BP)control(normal group),and 32 SHRs were randomized into model group,EA group,EA plus ghrelin group(EA+G group),and EA plus PF04628935 group(a potent ghrelin receptor blocker;EA+P group)using a random number table.Rats in the normal group and model group did not receive treatment,but were immobilized for 20 min per day,5 times a week,for 4 continuous weeks.SHRs in the EA group,EA+G group and EA+P group were immobilized and given EA treatment in 20 min sessions,5 times per week,for 4 weeks.Additionally,1 h before EA,SHRs in the EA+G group and EA+P group were intraperitoneally injected with ghrelin or PF04628935,respectively,for 4 weeks.The tail-cuff method was used to measure BP.After the 4-week intervention,the rats were sacrificed by cervical dislocation,and pathological morphology of the abdominal aorta was observed using hematoxylin-eosin(HE)staining.Enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of ghrelin,nitric oxide(NO),endothelin-1(ET-1)and thromboxane A2(TXA2)in the serum.Isolated thoracic aortic ring experiment was performed to evaluate vasorelaxation.Western blot was used to measure the expression of PI3K,Akt,phosphorylated Akt(p-Akt)and eNOS proteins in the abdominal aorta.Further,quantitative real-time polymerase chain reaction(qRT-PCR)was conducted to measure the relative levels of mRNA expression for PI3K,Akt and eNOS in the abdominal aorta.Results EA significantly reduced the systolic BP(SBP)and diastolic BP(DBP)(P<0.05).HE staining showed that EA improved the morphology of the vascular endothelium to some extent.Results of ELISA indicated that higher concentrations of ghrelin and NO,and lower concentrations of ET-1 and TXA2 were present in the EA group(P<0.05).The isolated thoracic aortic ring experiment demonstrated that the vasodilation capacity of the thoracic aorta increased in the EA group.Results of Western blot and qRT-PCR showed that EA increased the abundance of PI3K,p-Akt/Akt and eNOS proteins,as well as expression levels of PI3K,Akt and eNOS mRNAs(P<0.05).In the EA+G group,SBP and DBP decreased(P<0.05),ghrelin concentrations increased(P<0.05),and the concentrations of ET-1 and TXA2 decreased(P<0.05),relative to the EA group.In addition,the levels of PI3K and eNOS proteins,the p-Akt/Akt ratio,and the expression of PI3K,Akt and eNOS mRNAs increased significantly in the EA+G group(P<0.05),while PF04628935 reversed these effects.Conclusion EA effectively reduced BP and protected the vascular endothelium,and these effects may be linked to promoting the release of ghrelin and activation of the PI3K/Akt/eNOS signaling pathway.展开更多
Paraquat(PQ)is the third most used broad-spectrum nonselective herbicide around the globe after glyphosate and glufosinate.Repeated usage and overreliance on this herbicide have resulted in the emergence of PQ-resista...Paraquat(PQ)is the third most used broad-spectrum nonselective herbicide around the globe after glyphosate and glufosinate.Repeated usage and overreliance on this herbicide have resulted in the emergence of PQ-resistant weeds that are a potential hazard to agriculture.It is generally believed that PQ resistance in weeds is due to increased sequestration of the herbicide and its decreased translocation to the target site,as well as an enhanced ability to scavenge reactive oxygen species.However,little is known about the genetic bases and molecular mechanisms of PQ resistance in weeds,and hence no PQ-resistant crops have been developed to date.Forward genetics of the model plant Arabidopsis thaliana has advanced our understanding of the molecular mechanisms of PQ resistance.This review focuses on PQ resistance loci and resistance mechanisms revealed in Arabidopsis and examines the possibility of developing PQ-resistant crops using the elucidated mechanisms.展开更多
Paraquat(1,1’-dimethyl-4,4’-bipyridinium dichloride,PQ)has been widely used as a broad spectrum nonselective herbicide in agriculture for decades(Baldwin et al.,1968).Plants absorb PQ from their environment and tran...Paraquat(1,1’-dimethyl-4,4’-bipyridinium dichloride,PQ)has been widely used as a broad spectrum nonselective herbicide in agriculture for decades(Baldwin et al.,1968).Plants absorb PQ from their environment and transport to the chloroplasts,the site of its action where it competes for electrons from photosystem I(PSI)and cyclically generates superoxide that is converted to H2O2by superoxide dismutases(SODs),resultantly accumulating a large amount of reactive oxygen species(ROS)and thereby killing plants(Farrington et al.,1973).展开更多
基金Project(51675104)supported by the National Natural Science Foundation of ChinaProject(202002020068)supported by the Guangzhou Municipal Special Fund Project for Scientific and Technological Innovation and Development,ChinaProject(2017KCXTD010)supported by the Innovation Team Project,Department of Education of Guangdong Province,China。
文摘The joining of DP780 steel to Al5052 was conducted by laser lap welding,in which the metal vapor and spatters were monitored by a high-speed camera.A universal testing machine was used to test the mechanical properties of the welded joints,and the changing law of lap tensile resistance with the laser welding parameters was analyzed.Optical microscope and scanning electron microscope were used to observe the macro-structure and micro-structure,respectively.Three different intermetallic compounds(IMCs)phases,i.e.banded Fe2Al5,FeAl2 and needle-like FeAl3 were generated at the steel/Al interface on microscopic observation.The aim of this research is to investigate the relationship among the lap tensile resistance,the welding parameters and the failure mode under different energy densities.Experimental results showed that the steel/Al joints have two different fracture modes at low heat input and high heat input.The failures happened along the heat-affected zone of the weld and along the steel/Al joint interface,respectively.And both of the two failure modes are brittle fractures.Additionally,cracks appeared at the fracture interface,and needle-like particle clusters were found in the fracture microstructure.
基金supported in part by the National Key Research and Development Program of China under Grant No.2018YFB1801503National Natural Science Foundation of China under Grants No.61931006,No.82071940,No.62101111,No.U20A20212,No.61921002,and No.U1930127+1 种基金Fundamental Research Funds for the Central Universities under Grants No.ZYGX2020ZB011 and No.ZYGX2019J013Medico-Engineering Cooperation Funds from University of Electronic Science and Technology of China under Grants No.ZYGX2021YGLH205 and No.ZYGX2021YGLH216.
文摘The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application research in various areas,such as the early detection of breast tumors and cerebrovascular diseases.However,the microwave generator used in the traditional TAI technology is huge and expensive,and the temporal resolution is also too low due to the single-element scanning mechanism.Thus,it is difficult to meet the needs of clinical applications.In this paper,the iterative process and the analysis of related application scenarios from single-element scanning to portable and array-based TAI,such as the miniaturized microwave generator,handheld antenna,multi-channel data acquisition,and UI/TAIdual-modality imaging,are reviewed,and the future trends of this technology are discussed.This review helps researchers in the field of TAI learn the technological development process and future trends.It also deepens clinicians’understanding of TAI so as to put forward more application requirements.
基金supported by grants from the National Natural Science Foundation of China(grant no.31770273).
文摘Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15,which encodes the Multidrug and Toxic Extru-sion(MATE)transporter DTX6.A point mutation at+932 bp in DTX6 causes a G311E amino acid substitution,enhancing the paraquat resistance ofpqt15-D,and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance.Moreover,heterologous expression of DTX6 and DTX6-D in Es-cherichia coil significantly enhances bacterial resistance to paraquat.Importantly,overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat,a near-commercial application level.DTX6/PQT15 is localized in the plasma membrane and endomembrane,and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells.Taken together,our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resis-tance by exporting paraquat out of the cytosol.These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.
基金This study was supported by the National Natural Science Foundation of China(No.81704137.No.82074516,and No.82104976)sichuan Science and Technology Department(No.2019YJ0331)Chengdu University of Traditional Chinese Medicine(No.ZRQN2020022).
文摘Objective To investigate the influence of electroacupuncture(EA)on ghrelin and the phosphoinositide 3-kinase/protein kinase B/endothelial nitric oxide synthase(PI3K/Akt/eNOS)signaling pathway in spontaneously hypertensive rats(SHRs).Methods Eight Wistar-Kyoto rats were used as the healthy blood pressure(BP)control(normal group),and 32 SHRs were randomized into model group,EA group,EA plus ghrelin group(EA+G group),and EA plus PF04628935 group(a potent ghrelin receptor blocker;EA+P group)using a random number table.Rats in the normal group and model group did not receive treatment,but were immobilized for 20 min per day,5 times a week,for 4 continuous weeks.SHRs in the EA group,EA+G group and EA+P group were immobilized and given EA treatment in 20 min sessions,5 times per week,for 4 weeks.Additionally,1 h before EA,SHRs in the EA+G group and EA+P group were intraperitoneally injected with ghrelin or PF04628935,respectively,for 4 weeks.The tail-cuff method was used to measure BP.After the 4-week intervention,the rats were sacrificed by cervical dislocation,and pathological morphology of the abdominal aorta was observed using hematoxylin-eosin(HE)staining.Enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of ghrelin,nitric oxide(NO),endothelin-1(ET-1)and thromboxane A2(TXA2)in the serum.Isolated thoracic aortic ring experiment was performed to evaluate vasorelaxation.Western blot was used to measure the expression of PI3K,Akt,phosphorylated Akt(p-Akt)and eNOS proteins in the abdominal aorta.Further,quantitative real-time polymerase chain reaction(qRT-PCR)was conducted to measure the relative levels of mRNA expression for PI3K,Akt and eNOS in the abdominal aorta.Results EA significantly reduced the systolic BP(SBP)and diastolic BP(DBP)(P<0.05).HE staining showed that EA improved the morphology of the vascular endothelium to some extent.Results of ELISA indicated that higher concentrations of ghrelin and NO,and lower concentrations of ET-1 and TXA2 were present in the EA group(P<0.05).The isolated thoracic aortic ring experiment demonstrated that the vasodilation capacity of the thoracic aorta increased in the EA group.Results of Western blot and qRT-PCR showed that EA increased the abundance of PI3K,p-Akt/Akt and eNOS proteins,as well as expression levels of PI3K,Akt and eNOS mRNAs(P<0.05).In the EA+G group,SBP and DBP decreased(P<0.05),ghrelin concentrations increased(P<0.05),and the concentrations of ET-1 and TXA2 decreased(P<0.05),relative to the EA group.In addition,the levels of PI3K and eNOS proteins,the p-Akt/Akt ratio,and the expression of PI3K,Akt and eNOS mRNAs increased significantly in the EA+G group(P<0.05),while PF04628935 reversed these effects.Conclusion EA effectively reduced BP and protected the vascular endothelium,and these effects may be linked to promoting the release of ghrelin and activation of the PI3K/Akt/eNOS signaling pathway.
基金This work was supported by grants from the National Natural Science Foundation of China(grant nos.31770273,31270302,and 30770189)。
文摘Paraquat(PQ)is the third most used broad-spectrum nonselective herbicide around the globe after glyphosate and glufosinate.Repeated usage and overreliance on this herbicide have resulted in the emergence of PQ-resistant weeds that are a potential hazard to agriculture.It is generally believed that PQ resistance in weeds is due to increased sequestration of the herbicide and its decreased translocation to the target site,as well as an enhanced ability to scavenge reactive oxygen species.However,little is known about the genetic bases and molecular mechanisms of PQ resistance in weeds,and hence no PQ-resistant crops have been developed to date.Forward genetics of the model plant Arabidopsis thaliana has advanced our understanding of the molecular mechanisms of PQ resistance.This review focuses on PQ resistance loci and resistance mechanisms revealed in Arabidopsis and examines the possibility of developing PQ-resistant crops using the elucidated mechanisms.
基金supported by the National Natural Science Foundation of China(31770273)。
文摘Paraquat(1,1’-dimethyl-4,4’-bipyridinium dichloride,PQ)has been widely used as a broad spectrum nonselective herbicide in agriculture for decades(Baldwin et al.,1968).Plants absorb PQ from their environment and transport to the chloroplasts,the site of its action where it competes for electrons from photosystem I(PSI)and cyclically generates superoxide that is converted to H2O2by superoxide dismutases(SODs),resultantly accumulating a large amount of reactive oxygen species(ROS)and thereby killing plants(Farrington et al.,1973).
