Wide band-gap gallium nitride(GaN)device has the advantages of large band-gap,high electron mobility and low dielectric constant.Compared with traditional Si devices,these advantages make it suitable for fast-switchin...Wide band-gap gallium nitride(GaN)device has the advantages of large band-gap,high electron mobility and low dielectric constant.Compared with traditional Si devices,these advantages make it suitable for fast-switching and high-power-density power electronics converters,thus reducing the overall weight,volume and power consumption of power electronic systems.As a review paper,this paper summarizes the characteristics and development of the state-of-art GaN power devices with different structures,analyzes the research status,and forecasts the application prospect of GaN devices.In addition,the problems and challenges of GaN devices were discussed.And thanks to the advantages of GaN devices,both the power density and efficiency of motor drive system are improved,which also have been presented in this paper.展开更多
Imaging precession targets based on the narrowband radar to distinguish the real warhead from mid-course targets is a new technique in missile defense systems. Aiming at the typical mid-course flying scene, this paper...Imaging precession targets based on the narrowband radar to distinguish the real warhead from mid-course targets is a new technique in missile defense systems. Aiming at the typical mid-course flying scene, this paper describes the principle of the narrowband imaging method, and analyzes the influence on the narrowband imaging by the target translational motion. Then the precision qualification is deduced for both the distance compensation and the velocity compensation, and the conclusion that the velocity compensation is more appropriate for the motion compensation in the narrowband imaging is given. Furthermore, this paper proposes a motion compensation algorithm for the narrowband radar which reduces the interference of the signal phase chaos caused by the rebuilt real signal phase, thus realizing the precise translational motion compensation of the narrowband signal. Finally, the effectiveness of this method is proved by both theoretic analysis and experiment results. ? 1990-2011 Beijing Institute of Aerospace Information.展开更多
THE More Electric Aircraft(MEA)/All Electric Aircraft(AEA)system is being widely recognized as the future for the aerospace industry to meet the power demands of increasing electric loads,reduce aircraft emissions,imp...THE More Electric Aircraft(MEA)/All Electric Aircraft(AEA)system is being widely recognized as the future for the aerospace industry to meet the power demands of increasing electric loads,reduce aircraft emissions,improve fuel economy,and lower the cost of the total system.展开更多
Background:Cisplatin-based chemotherapy with concurrent radiotherapy is a standard treatment for advanced esophageal squamous cell carcinoma(ESCC).NS1-binding protein(NS1-BP),a member of the BTB-kelch protein fam-ily,...Background:Cisplatin-based chemotherapy with concurrent radiotherapy is a standard treatment for advanced esophageal squamous cell carcinoma(ESCC).NS1-binding protein(NS1-BP),a member of the BTB-kelch protein fam-ily,has been shown to inhibit the proliferation of Hela cells by suppressing c-Myc.In the present study,we examined the potential function role of NS1-BP expression in ESCC,and particularly,the sensitivity of ESCC to radiotherapy.Methods:NS1-BP expression was examined using immunohistochemistry in two cohorts(n=98 for the training cohort;n=46 for independent validation cohort)of ESCC patients receiving cisplatin-based chemotherapy and con-current radiotherapy.Normal esophageal mucosal tissue blocks were used as a control.We also conducted a series of in vitro and in vivo experiments to examine the potential effects of over-expressing NS1-BP on ESCC cells,and particu-larly their sensitivity to ionizing irradiation.Results:In the training cohort,NS1-BP downregulation was observed in 59%(85/144)of the ESCC specimens.NS1-BP downregulation was associated with chemoradiotherapeutic resistance and shorter disease-specific survival(DSS)in both the training and validation cohorts.Over-expressing NS1-BP in cultured ESCC cells substantially increased the cellular response to irradiation both in vitro and in vivo.NS1-BP also significantly enhanced IR-induced apoptosis,and abrogated IR-induced G2/M cell-cycle arrest and ATM/Chk1 phosphorylation.Immunoprecipitation assays indicated that NS1-BP could interact with c-Myc promoter regions to inhibit its transcription.In ESCC tissues,c-Myc expression was inversely correlated with NS1-BP levels,and was associated with a shorter DSS.Conclusions:Our findings highlight the role and importance of NS1-BP in radiosensitivity of ESCC.Targeting the NS1-BP/c-Myc pathway may provide a novel therapeutic strategy for ESCC.展开更多
To improve the heat dissipation performance,this paper proposes a novel hybrid cooling method for high-speed high-power Permanent Magnet assisted Synchronous Reluctance Starter/Generator(PMa Syn R S/G)in aerospace app...To improve the heat dissipation performance,this paper proposes a novel hybrid cooling method for high-speed high-power Permanent Magnet assisted Synchronous Reluctance Starter/Generator(PMa Syn R S/G)in aerospace applications.The hybrid cooling structure with oil circulation in the housing,oil spray at winding ends and rotor end surface is firstly proposed for the PMa Syn R S/G.Then the accurate loss calculation of the PMa Syn R S/G is proposed,which includes air gap friction loss under oil spray cooling,copper loss,stator and rotor core loss,permanent magnet eddy current loss and bearing loss.The parameter sensitivity analysis of the hybrid cooling structure is proposed,while the equivalent thermal network model of the PMa Syn R S/G is established considering the uneven spraying at the winding ends.Finally,the effectiveness of the proposed hybrid cooling method is demonstrated on a 40 k W/24000 r/min PMa Syn R S/G experimental platform.展开更多
Background:Skin wound healing depends on the progress of different but overlapping stages of healing,including hemostasis,inflammatory,proliferative and remodeling.Failure of these stages to occur in a timely and grad...Background:Skin wound healing depends on the progress of different but overlapping stages of healing,including hemostasis,inflammatory,proliferative and remodeling.Failure of these stages to occur in a timely and gradual manner may result in non-healing pathological wounds.Macrophages and neutrophils have been shown to play an essential role in the inflammatory responses of wound tissue,and their active plasticity allows them to modulate tissue damage and repair functions.The ability of macrophages and neutrophils to regulate the occurrence and resolution of inflammatory processes is essential for the treatment of pathological wound healing.Methods:Mice were categorized into negative control,streptozotocin,streptozotocin+puerarin and puerarin groups.The traditional Chinese medicine extract puerarin was selected to treat different groups of mice with a full-thickness skin defect wound.Cells of the RAW264.7 cell line were stimulated under different puerarin conditions.Then,real time quantitative polymerase chain reaction(RT-qPCR),western blot,immunofluorescence and other assays were carried out to explore the effect of puerarin on wound healing and its molecular mechanism.Results:Animal experiments found that the wound healing of diabetic mice treated with puerarin was significantly accelerated,and histological analysis found that puerarin treatment markedly decreased the infiltration of macrophages and neutrophils in wound tissue.Through western blot,RT-qPCR and immunofluorescence experiments,it was observed that puerarin treatment remarkably inhibited nuclear factor kinase B(NF-κB)and mitogen-activated protein kinase(MAPK)signaling pathways,downregulated the expression of inflammatory cytokines and induced the M2 polarization of macrophages.At the cellular level,we also observed that puerarin improved M2 macrophage polarization and inhibited inflammatory pathway activation in a high-glucose culture.Conclusion:Puerarin has a significant therapeutic effect on wound healing in diabetic mice.The therapeutic effect is achieved by regulating macrophage polarization through suppressing NF-κB and MAPK signaling cascades.展开更多
High-speed Brushless DC Motors(BLDCMs)usually adopt a sensorless control strategy and operate in three-phase six-state drive mode.However,the sampling errors of the rotor position and the driving method increase the I...High-speed Brushless DC Motors(BLDCMs)usually adopt a sensorless control strategy and operate in three-phase six-state drive mode.However,the sampling errors of the rotor position and the driving method increase the Internal Power Angle(IPA),resulting in a decrease in the efficiency of the system.Conventional IPA reduction strategies are either sensitive to motor parameters,or ignore diode freewheeling during the commutation process,or require additional current sensors.In this paper,a new strategy to reduce the IPA is proposed.Firstly,a Zero-Crossing Point(ZCP)detection method for the back-EMF without filter is proposed to reduce the sampling errors of the rotor position.Secondly,the relationship between the non-energized terminal voltage and the ZCP of the corresponding back-EMF is analyzed.The non-energized terminal voltage that has completed the diode freewheeling is divided into two triangles by half of the bus voltage.When the IPA is suppressed,the areas of the two triangles are equal.Thirdly,an advanced angle for reducing the IPA is obtained through a PI regulator which can eliminate the deviation between the two areas.Finally,both a simulation model and an experimental circuit are built to verify the proposed control strategy.展开更多
The modification and functionalization of peptides is of great significance in modern biotechnology and drug development. Here we report a highly reactive Michael-type warhead for the covalently modification of cystei...The modification and functionalization of peptides is of great significance in modern biotechnology and drug development. Here we report a highly reactive Michael-type warhead for the covalently modification of cysteine on peptide and protein. By installing a vinyl group onto a methionine residue of peptide,the produced vinyl sulfonium can be efficiently nucleophilic added by appropriate cysteine residue of this peptide, and thus yield a cyclized peptide. This peptide cyclization strategy was proven to exhibit improved cell penetration and good stability. Moreover, a peptide ligand bearing vinyl sulfonium could covalently bind to the cysteine in the target protein, indicating the potential of vinyl sulfonium as a novel warhead for developing covalent peptide inhibitor.展开更多
基金This work was supported in part by the National Natural Science Foundation of China under Project 51877006,and in part by the Aeronautical Science Foundation of China 20162851016。
文摘Wide band-gap gallium nitride(GaN)device has the advantages of large band-gap,high electron mobility and low dielectric constant.Compared with traditional Si devices,these advantages make it suitable for fast-switching and high-power-density power electronics converters,thus reducing the overall weight,volume and power consumption of power electronic systems.As a review paper,this paper summarizes the characteristics and development of the state-of-art GaN power devices with different structures,analyzes the research status,and forecasts the application prospect of GaN devices.In addition,the problems and challenges of GaN devices were discussed.And thanks to the advantages of GaN devices,both the power density and efficiency of motor drive system are improved,which also have been presented in this paper.
基金supported by the National Natural Science Foundation of China(6127144261401481)
文摘Imaging precession targets based on the narrowband radar to distinguish the real warhead from mid-course targets is a new technique in missile defense systems. Aiming at the typical mid-course flying scene, this paper describes the principle of the narrowband imaging method, and analyzes the influence on the narrowband imaging by the target translational motion. Then the precision qualification is deduced for both the distance compensation and the velocity compensation, and the conclusion that the velocity compensation is more appropriate for the motion compensation in the narrowband imaging is given. Furthermore, this paper proposes a motion compensation algorithm for the narrowband radar which reduces the interference of the signal phase chaos caused by the rebuilt real signal phase, thus realizing the precise translational motion compensation of the narrowband signal. Finally, the effectiveness of this method is proved by both theoretic analysis and experiment results. ? 1990-2011 Beijing Institute of Aerospace Information.
文摘THE More Electric Aircraft(MEA)/All Electric Aircraft(AEA)system is being widely recognized as the future for the aerospace industry to meet the power demands of increasing electric loads,reduce aircraft emissions,improve fuel economy,and lower the cost of the total system.
基金supported by the National Nature Science Foundation of China(81401948,81472182,81372518 and 81472797).
文摘Background:Cisplatin-based chemotherapy with concurrent radiotherapy is a standard treatment for advanced esophageal squamous cell carcinoma(ESCC).NS1-binding protein(NS1-BP),a member of the BTB-kelch protein fam-ily,has been shown to inhibit the proliferation of Hela cells by suppressing c-Myc.In the present study,we examined the potential function role of NS1-BP expression in ESCC,and particularly,the sensitivity of ESCC to radiotherapy.Methods:NS1-BP expression was examined using immunohistochemistry in two cohorts(n=98 for the training cohort;n=46 for independent validation cohort)of ESCC patients receiving cisplatin-based chemotherapy and con-current radiotherapy.Normal esophageal mucosal tissue blocks were used as a control.We also conducted a series of in vitro and in vivo experiments to examine the potential effects of over-expressing NS1-BP on ESCC cells,and particu-larly their sensitivity to ionizing irradiation.Results:In the training cohort,NS1-BP downregulation was observed in 59%(85/144)of the ESCC specimens.NS1-BP downregulation was associated with chemoradiotherapeutic resistance and shorter disease-specific survival(DSS)in both the training and validation cohorts.Over-expressing NS1-BP in cultured ESCC cells substantially increased the cellular response to irradiation both in vitro and in vivo.NS1-BP also significantly enhanced IR-induced apoptosis,and abrogated IR-induced G2/M cell-cycle arrest and ATM/Chk1 phosphorylation.Immunoprecipitation assays indicated that NS1-BP could interact with c-Myc promoter regions to inhibit its transcription.In ESCC tissues,c-Myc expression was inversely correlated with NS1-BP levels,and was associated with a shorter DSS.Conclusions:Our findings highlight the role and importance of NS1-BP in radiosensitivity of ESCC.Targeting the NS1-BP/c-Myc pathway may provide a novel therapeutic strategy for ESCC.
基金co-supported by the National Natural Science Foundation of China(No.52177028)in part by the Aeronautical Science Foundation of China(No.201907051002)。
文摘To improve the heat dissipation performance,this paper proposes a novel hybrid cooling method for high-speed high-power Permanent Magnet assisted Synchronous Reluctance Starter/Generator(PMa Syn R S/G)in aerospace applications.The hybrid cooling structure with oil circulation in the housing,oil spray at winding ends and rotor end surface is firstly proposed for the PMa Syn R S/G.Then the accurate loss calculation of the PMa Syn R S/G is proposed,which includes air gap friction loss under oil spray cooling,copper loss,stator and rotor core loss,permanent magnet eddy current loss and bearing loss.The parameter sensitivity analysis of the hybrid cooling structure is proposed,while the equivalent thermal network model of the PMa Syn R S/G is established considering the uneven spraying at the winding ends.Finally,the effectiveness of the proposed hybrid cooling method is demonstrated on a 40 k W/24000 r/min PMa Syn R S/G experimental platform.
基金supported by The National Natural Science Foundation of China(81974288).
文摘Background:Skin wound healing depends on the progress of different but overlapping stages of healing,including hemostasis,inflammatory,proliferative and remodeling.Failure of these stages to occur in a timely and gradual manner may result in non-healing pathological wounds.Macrophages and neutrophils have been shown to play an essential role in the inflammatory responses of wound tissue,and their active plasticity allows them to modulate tissue damage and repair functions.The ability of macrophages and neutrophils to regulate the occurrence and resolution of inflammatory processes is essential for the treatment of pathological wound healing.Methods:Mice were categorized into negative control,streptozotocin,streptozotocin+puerarin and puerarin groups.The traditional Chinese medicine extract puerarin was selected to treat different groups of mice with a full-thickness skin defect wound.Cells of the RAW264.7 cell line were stimulated under different puerarin conditions.Then,real time quantitative polymerase chain reaction(RT-qPCR),western blot,immunofluorescence and other assays were carried out to explore the effect of puerarin on wound healing and its molecular mechanism.Results:Animal experiments found that the wound healing of diabetic mice treated with puerarin was significantly accelerated,and histological analysis found that puerarin treatment markedly decreased the infiltration of macrophages and neutrophils in wound tissue.Through western blot,RT-qPCR and immunofluorescence experiments,it was observed that puerarin treatment remarkably inhibited nuclear factor kinase B(NF-κB)and mitogen-activated protein kinase(MAPK)signaling pathways,downregulated the expression of inflammatory cytokines and induced the M2 polarization of macrophages.At the cellular level,we also observed that puerarin improved M2 macrophage polarization and inhibited inflammatory pathway activation in a high-glucose culture.Conclusion:Puerarin has a significant therapeutic effect on wound healing in diabetic mice.The therapeutic effect is achieved by regulating macrophage polarization through suppressing NF-κB and MAPK signaling cascades.
基金supported by the National Natural Science Foundation of China(No.51877006)the Key R&D Program of Shaanxi Province,China(No.2021GY-340 and 2020GY-140)the Aeronautical Science Foundation of China(No.20181953020)。
文摘High-speed Brushless DC Motors(BLDCMs)usually adopt a sensorless control strategy and operate in three-phase six-state drive mode.However,the sampling errors of the rotor position and the driving method increase the Internal Power Angle(IPA),resulting in a decrease in the efficiency of the system.Conventional IPA reduction strategies are either sensitive to motor parameters,or ignore diode freewheeling during the commutation process,or require additional current sensors.In this paper,a new strategy to reduce the IPA is proposed.Firstly,a Zero-Crossing Point(ZCP)detection method for the back-EMF without filter is proposed to reduce the sampling errors of the rotor position.Secondly,the relationship between the non-energized terminal voltage and the ZCP of the corresponding back-EMF is analyzed.The non-energized terminal voltage that has completed the diode freewheeling is divided into two triangles by half of the bus voltage.When the IPA is suppressed,the areas of the two triangles are equal.Thirdly,an advanced angle for reducing the IPA is obtained through a PI regulator which can eliminate the deviation between the two areas.Finally,both a simulation model and an experimental circuit are built to verify the proposed control strategy.
基金financial support from the National Key Research and Development Program"Synthetic Biology"Key Special Project of China (No. 2018YFA0902504)the China Postdoctoral Science Foundation (No. 2021M690220)+7 种基金the National Natural Science Foundation of China (Nos. 21778009 and21977010)the Natural Science Foundation of Guangdong Province(Nos. 2019A1515110487, 2020A1515010522 and 2019A1515111184)the Shenzhen Science and Technology Innovation Committee (Nos. JCYJ20180507181527112, JCYJ20180508152213145, and JCYJ20170817172023838)the Foundation for Basic and Applied Research of Guangdong Province (No. 2019A1515110489)Guangdong Medical Science Foundation (No. A2021413)financial support from Beijing National Laboratory of Molecular Science Open Grant (No. BNLMS20160112)Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions (No. 2019SHIBS0004)supported by the high-performance computing platform of Peking University。
文摘The modification and functionalization of peptides is of great significance in modern biotechnology and drug development. Here we report a highly reactive Michael-type warhead for the covalently modification of cysteine on peptide and protein. By installing a vinyl group onto a methionine residue of peptide,the produced vinyl sulfonium can be efficiently nucleophilic added by appropriate cysteine residue of this peptide, and thus yield a cyclized peptide. This peptide cyclization strategy was proven to exhibit improved cell penetration and good stability. Moreover, a peptide ligand bearing vinyl sulfonium could covalently bind to the cysteine in the target protein, indicating the potential of vinyl sulfonium as a novel warhead for developing covalent peptide inhibitor.
