In the past decades,residual stresses have attracted wide attention due to their significant influences on material’s strength,fatigue life,and dimensional stability.Various residual stress measurement methods have b...In the past decades,residual stresses have attracted wide attention due to their significant influences on material’s strength,fatigue life,and dimensional stability.Various residual stress measurement methods have been developed such as X-ray diffraction,neutron diffraction,crack compliance,and hole drilling.These methods may suffer from different disadvantages including radiation,high cost,destructive,unportable,etc.In this work,an in situ residual stress measurement method was proposed based on instrumented indentation using a piezoelectric bimorph cantilever.A Vickers’indenter was fabricated onto the free end of the cantilever for pressing into the sample and a strain gauge was bonded on the cantilever to monitor the indentation load.During testing,the contact area was extracted by tracking the cantilever’s contact resonance frequency based on the electromechanical impendence method.Different from traditional indentation-based methods that use a single hardness value to compute the residual stress,here the indentation force-contact area(F-S)curves with and without residual stresses were measured to derive the residual stress based on an empirical model.Experiments were then conducted on a specially designed CrMnCu specimen with different applied stresses.Results show that the measured residual stress values agreed well with the applied stresses monitored by a strain gauge.The proposed residual stress measurement method holds great promise for in situ residual stress estimation due to its portable apparatus,simple operation procedure and insensitiveness to testing environment.展开更多
The flashover performance of insulating materials plays an important role in the development of high-voltage insulation systems.In this paper,silicone rubber(SIR)is modified by CF4 radio frequency capacitively coupled...The flashover performance of insulating materials plays an important role in the development of high-voltage insulation systems.In this paper,silicone rubber(SIR)is modified by CF4 radio frequency capacitively coupled plasma(CCP)for the improvement of surface insulation performance.The discharge mode and active particles of CCP are diagnosed by the digital single-lens reflex and the spectrometer.Scanning electron microscopy and x-ray photoelectron spectroscopy are used for the surface physicochemical properties of samples,while the surface charge dissipation,charge accumulation measurement,and flashover test are applied for the surface electrical characteristics.Experimental results show that the fluorocarbon groups can be grafted and the surface roughness increases after plasma treatment.Besides,the surface charge dissipation is decelerated and the positive charge accumulation is inhibited obviously for the treated samples.Furthermore,the surface flashover voltage can be increased by 26.67%after 10 min of treatment.It is considered that strong electron affinity of C–F and increased surface roughness can contribute to deepening surface traps,which not only inhibits the development of secondary electron emission avalanche but also alleviates the surface charge accumulation and finally improves the surface flashover voltage of SIR.展开更多
Neurodegenerative diseases,such as Alzheimer’s disease(AD),Parkinson’s disease(PD),amyotrophic lateral sclerosis(ALS),and huntington’s disease,pose significant threats to human health,with current treatment op-tion...Neurodegenerative diseases,such as Alzheimer’s disease(AD),Parkinson’s disease(PD),amyotrophic lateral sclerosis(ALS),and huntington’s disease,pose significant threats to human health,with current treatment op-tions remaining limited.Piezoelectric materials,known for their ability to convert mechanical energy into electrical signals at the nanoscale,hold great promise in the diagnosis and treatment of neurodegenerative diseases due to their excellent electromechanical properties,environmental stability,and sensitivity.This review systematically outlines the working principles and classifications of piezoelectric materials.Subsequently,the recent advances in piezoelectric materials and their applications in the diagnosis and treatment of neurode-generative diseases are highlighted.Finally,the challenges and perspectives regarding the development of future piezoelectric materials are discussed.This review aims to provide a comprehensive reference for the further application of piezoelectric materials in neurodegenerative diseases.展开更多
The distribution of measurement noise is usually assumed to be Gaussian in the optimal phasor measurement unit(PMU)placement(OPP)problem.However,this is not always accurate in practice.This paper proposes a new OPP me...The distribution of measurement noise is usually assumed to be Gaussian in the optimal phasor measurement unit(PMU)placement(OPP)problem.However,this is not always accurate in practice.This paper proposes a new OPP method for smart grids in which the effects of conventional measurements,limited channels of PMUs,zero-injection buses(ZIBs),single PMU loss contingency,state estimation error(SEE),and the maximum SEE variance(MSEEV)are considered.The SEE and MSEEV are both obtained using a robust t-distribution maximum likelihood estimator(MLE)because t-distribution is more flexible for modeling both Gaussian and non-Gaussian noises.The A-and G-optimal experimental criteria are utilized to form the SEE and MSEEV constraints.This allows the optimization problem to be converted into a linear objective function subject to linear matrix inequality observability constraints.The performance of the proposed OPP method is verified by the simulations of the IEEE 14-bus,30-bus,and 118-bus systems as well as the 211-bus practical distribution system in China.展开更多
To the Editor:Vascular dementia(VD)is a clinical disease characterized_by cognitive dysfunction and intellectual decline caused byvarious cerebrovascularfactors.The high incidence of VD in middle-aged and elderly peop...To the Editor:Vascular dementia(VD)is a clinical disease characterized_by cognitive dysfunction and intellectual decline caused byvarious cerebrovascularfactors.The high incidence of VD in middle-aged and elderly people has become a major medical and social problem worldwide.li Since its specific pathogenesis has not been fully elucidated,clinical practice is stillfocused on improving cognition and sAylmteprntoamtivaetilcy,t rweiathtm heignht,seuffcehc taivse pnierascse atanmd faenwd sdidoen eepffeezcitl.s2,i traditional Chinese medicine has drawn medical attention and become a hotspot in the medical research field.展开更多
Intestinal disease is a group of complex digestive system diseases imposing a significant burden globally.Identifying the risk factors and potential complications of intestinal disease is important for its prevention ...Intestinal disease is a group of complex digestive system diseases imposing a significant burden globally.Identifying the risk factors and potential complications of intestinal disease is important for its prevention and treatment.However,traditional observational clinical studies are limited by confounding factors and reverse causation,making causal inference challenging.Mendelian randomisation(MR)method has been developed to effectively mitigate these constraints and assess the causal relationships.This review briefly introduces the MR method,summarises MR research on intestinal disease and delineates the prospective avenues for future research.Conventional risk factors,such as lifestyle behaviours(eg,physical activity,smoking and alcohol consumption),nutrients(eg,selenium),obesity markers(eg,body mass index and waist-to-hip ratio)and inflammatory biomarkers,have been validated in MR studies.Multiomics MR studies are becoming novel hotspots,which provide a theoretical foundation for the exploration of pathogenesis and the investigation of new drug targets.However,most of the recent studies are based on European individuals,and thus it is necessary to replicate the results in other ancestries.Moreover,triangulation integrating MR and other epidemiology methods is suggested as a validated paradigm for causal inference in future MR studies.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFF0716800)National Natural Science Foundation of China(Grant No.12102393).
文摘In the past decades,residual stresses have attracted wide attention due to their significant influences on material’s strength,fatigue life,and dimensional stability.Various residual stress measurement methods have been developed such as X-ray diffraction,neutron diffraction,crack compliance,and hole drilling.These methods may suffer from different disadvantages including radiation,high cost,destructive,unportable,etc.In this work,an in situ residual stress measurement method was proposed based on instrumented indentation using a piezoelectric bimorph cantilever.A Vickers’indenter was fabricated onto the free end of the cantilever for pressing into the sample and a strain gauge was bonded on the cantilever to monitor the indentation load.During testing,the contact area was extracted by tracking the cantilever’s contact resonance frequency based on the electromechanical impendence method.Different from traditional indentation-based methods that use a single hardness value to compute the residual stress,here the indentation force-contact area(F-S)curves with and without residual stresses were measured to derive the residual stress based on an empirical model.Experiments were then conducted on a specially designed CrMnCu specimen with different applied stresses.Results show that the measured residual stress values agreed well with the applied stresses monitored by a strain gauge.The proposed residual stress measurement method holds great promise for in situ residual stress estimation due to its portable apparatus,simple operation procedure and insensitiveness to testing environment.
基金supported by National Natural Science Foundation of China(Nos.11775175,U1766218,51827809)Natural Science Research Fund of Higher Education of Anhui Province(No.KJ2020A0246)。
文摘The flashover performance of insulating materials plays an important role in the development of high-voltage insulation systems.In this paper,silicone rubber(SIR)is modified by CF4 radio frequency capacitively coupled plasma(CCP)for the improvement of surface insulation performance.The discharge mode and active particles of CCP are diagnosed by the digital single-lens reflex and the spectrometer.Scanning electron microscopy and x-ray photoelectron spectroscopy are used for the surface physicochemical properties of samples,while the surface charge dissipation,charge accumulation measurement,and flashover test are applied for the surface electrical characteristics.Experimental results show that the fluorocarbon groups can be grafted and the surface roughness increases after plasma treatment.Besides,the surface charge dissipation is decelerated and the positive charge accumulation is inhibited obviously for the treated samples.Furthermore,the surface flashover voltage can be increased by 26.67%after 10 min of treatment.It is considered that strong electron affinity of C–F and increased surface roughness can contribute to deepening surface traps,which not only inhibits the development of secondary electron emission avalanche but also alleviates the surface charge accumulation and finally improves the surface flashover voltage of SIR.
基金supported by the National Natural Science Foundation of China(82172222,82000456)Shanghai Jiao Tong University“Star Project”of Biomedical Multi-discipline Research Program(YG2024ZD13).
文摘Neurodegenerative diseases,such as Alzheimer’s disease(AD),Parkinson’s disease(PD),amyotrophic lateral sclerosis(ALS),and huntington’s disease,pose significant threats to human health,with current treatment op-tions remaining limited.Piezoelectric materials,known for their ability to convert mechanical energy into electrical signals at the nanoscale,hold great promise in the diagnosis and treatment of neurodegenerative diseases due to their excellent electromechanical properties,environmental stability,and sensitivity.This review systematically outlines the working principles and classifications of piezoelectric materials.Subsequently,the recent advances in piezoelectric materials and their applications in the diagnosis and treatment of neurode-generative diseases are highlighted.Finally,the challenges and perspectives regarding the development of future piezoelectric materials are discussed.This review aims to provide a comprehensive reference for the further application of piezoelectric materials in neurodegenerative diseases.
基金supported by the National Natural Science Foundation of China (No.61903314)Basic Research Program of Science and Technology of Shenzhen,China (No.JCYJ20190809162807421)+1 种基金Natural Science Foundation of Fujian Province (No.2019J05020)National Research Foundation,Prime Minister’s Office,Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE)programme。
文摘The distribution of measurement noise is usually assumed to be Gaussian in the optimal phasor measurement unit(PMU)placement(OPP)problem.However,this is not always accurate in practice.This paper proposes a new OPP method for smart grids in which the effects of conventional measurements,limited channels of PMUs,zero-injection buses(ZIBs),single PMU loss contingency,state estimation error(SEE),and the maximum SEE variance(MSEEV)are considered.The SEE and MSEEV are both obtained using a robust t-distribution maximum likelihood estimator(MLE)because t-distribution is more flexible for modeling both Gaussian and non-Gaussian noises.The A-and G-optimal experimental criteria are utilized to form the SEE and MSEEV constraints.This allows the optimization problem to be converted into a linear objective function subject to linear matrix inequality observability constraints.The performance of the proposed OPP method is verified by the simulations of the IEEE 14-bus,30-bus,and 118-bus systems as well as the 211-bus practical distribution system in China.
基金National Natural Science Foundation of China(No.81860805)Guangxi University of Chinese medicine(No.2018001)Guangxi Key Laboratory of Chinese Medicine Foundation Research(No.KJT1701202)。
文摘To the Editor:Vascular dementia(VD)is a clinical disease characterized_by cognitive dysfunction and intellectual decline caused byvarious cerebrovascularfactors.The high incidence of VD in middle-aged and elderly people has become a major medical and social problem worldwide.li Since its specific pathogenesis has not been fully elucidated,clinical practice is stillfocused on improving cognition and sAylmteprntoamtivaetilcy,t rweiathtm heignht,seuffcehc taivse pnierascse atanmd faenwd sdidoen eepffeezcitl.s2,i traditional Chinese medicine has drawn medical attention and become a hotspot in the medical research field.
基金supported by the National Natural Science Foundation of China(U23A20492 and 8217033803).
文摘Intestinal disease is a group of complex digestive system diseases imposing a significant burden globally.Identifying the risk factors and potential complications of intestinal disease is important for its prevention and treatment.However,traditional observational clinical studies are limited by confounding factors and reverse causation,making causal inference challenging.Mendelian randomisation(MR)method has been developed to effectively mitigate these constraints and assess the causal relationships.This review briefly introduces the MR method,summarises MR research on intestinal disease and delineates the prospective avenues for future research.Conventional risk factors,such as lifestyle behaviours(eg,physical activity,smoking and alcohol consumption),nutrients(eg,selenium),obesity markers(eg,body mass index and waist-to-hip ratio)and inflammatory biomarkers,have been validated in MR studies.Multiomics MR studies are becoming novel hotspots,which provide a theoretical foundation for the exploration of pathogenesis and the investigation of new drug targets.However,most of the recent studies are based on European individuals,and thus it is necessary to replicate the results in other ancestries.Moreover,triangulation integrating MR and other epidemiology methods is suggested as a validated paradigm for causal inference in future MR studies.
