The mechanism of cell damage during acute pancreatitis (AP) has not been fully elucidated, and there is still a lack of specific or effective treatments. Increasing evidence has implicated mitochondrial dysfunction as...The mechanism of cell damage during acute pancreatitis (AP) has not been fully elucidated, and there is still a lack of specific or effective treatments. Increasing evidence has implicated mitochondrial dysfunction as a key event in the pathophysiology of AP. Mitochondrial dysfunction is closely related to calcium (Ca^(2+)) overload, intracellular adenosine triphosphate depletion, mitochondrial permeability transition pore openings, loss of mitochondrial membrane potential, mitophagy damage and inflammatory responses. Mitochondrial dysfunction is an early triggering event in the initiation and development of AP,and this organelle damage may precede the release of inflammatory cytokines, intracellular trypsin activation and vacuole formation of pancreatic acinar cells. This review provides further insight into the role of mitochondria in both physiological and pathophysiological aspects of AP, aiming to improve our understanding of the underlying mechanism which may lead to the development of therapeutic and preventive strategies for AP.展开更多
Food systems are deeply affected by climate change and air pollution,while being key contributors to these environmental challenges.Understanding the complex interactions among food systems,climate change,and air poll...Food systems are deeply affected by climate change and air pollution,while being key contributors to these environmental challenges.Understanding the complex interactions among food systems,climate change,and air pollution is crucial for mitigating climate change,improving air quality,and promoting the sustainable development of food systems.However,the literature lacks a comprehensive review of these interactions,particularly in the current phase of rapid development in the field.To address this gap,this study systematically reviews recent research on the impacts of climate change and air pollution on food systems,as well as the greenhouse gas and air pollutant emissions from agri-food systems and their contribution to global climate change and air pollution.In addition,this study summarizes various strategies for mitigation and adaptation,including adjustments in agricultural practices and food supply chains.Profound changes in food systems are urgently needed to enhance adaptability and reduce emissions.This review offers a critical overview of current research on the interactions among food systems,climate change,and air pollution and highlights future research directions to support the transition to sustainable food systems.展开更多
Pipe cooling is an effective method of mass concrete temperature control, but its accurate and convenient numerical simulation is still a cumbersome problem. An improved embedded model, considering the water temperatu...Pipe cooling is an effective method of mass concrete temperature control, but its accurate and convenient numerical simulation is still a cumbersome problem. An improved embedded model, considering the water temperature variation along the pipe, was proposed for simulating the temperature field of early-age concrete structures containing cooling pipes. The improved model was verified with an engineering example. Then, the p-version self-adaption algorithm for the improved embedded model was deduced, and the initial values and boundary conditions were examined. Comparison of some numerical samples shows that the proposed model can provide satisfying precision and a higher efficiency. The analysis efficiency can be doubled at the same precision, even for a large-scale element. The p-version algorithm can fit grids of different sizes for the temperature field simulation. The convenience of the proposed algorithm lies in the possibility of locating more pipe segments in one element without the need of so regular a shape as in the explicit model.展开更多
This paper proposes a fuel-optimal deorbit scheme for space debris deorbit using tethered space tug.The scheme contains three stages named respectively as dragging,maintenance and swinging.In the first stage,the tug,p...This paper proposes a fuel-optimal deorbit scheme for space debris deorbit using tethered space tug.The scheme contains three stages named respectively as dragging,maintenance and swinging.In the first stage,the tug,propelled by continuous thrust,tows deorbit to a transfer orbit with a tether.Then in the second stage,the combination of the tug and the debris flies unpowered and uncontrolled to a swing point on the transfer orbit.Finally,in the third stage,the tug is propelled at the swing point and the rotation speed of the tethered system increases such that the debris obtains enough velocity increment.The trajectory optimization of the first stage is established considering the total fuel consumption of the three stages,whereas the dynamic model is simplified for computation efficiency.The solution to the optimal problem is obtained using a direct method based on Gauss pesudospectral discretization.Then a model predictive controller is designed to track the open-loop optimal reference trajectories,reducing the states’deviations caused by model simplification and ignorance of perturbations.Furthermore,it is proved that the fuel-optimal swing point is the apogee of the transfer orbit.The paper analyzes the fuel consumption of a typical scenario and demonstrates effectiveness of the proposed deorbit scheme numerically.展开更多
BACKGROUND Ulcerative colitis(UC)is a chronic,nonspecific intestinal inflammatory disease.Acupuncture and moxibustion is proved effective in treating UC,but the mechanism has not been clarified.Proteomic technology ha...BACKGROUND Ulcerative colitis(UC)is a chronic,nonspecific intestinal inflammatory disease.Acupuncture and moxibustion is proved effective in treating UC,but the mechanism has not been clarified.Proteomic technology has revealed a variety of biological markers related to immunity and inflammation in UC,which provide new insights and directions for the study of mechanism of acupuncture and moxibustion treatment of UC.AIM To investigate the mechanism of electroacupuncture(EA)and herb-partitioned moxibustion(HM)on UC rats by using proteomics technology.METHODS Male Sprague-Dawley rats were randomly divided into the normal(N)group,the dextran sulfate sodium(DSS)-induced UC model(M)group,the HM group,and the EA group.UC rat model was prepared with 3%DSS,and HM and EA interventions at the bilateral Tianshu and Qihai acupoints were performed in HM or EA group.Haematoxylin and eosin staining was used for morphological evaluation of colon tissues.Isotope-labeled relative and absolute quantification(iTRAQ)and liquid chromatography-tandem mass spectrometry were performed for proteome analysis of the colon tissues,followed by bioinformatics analysis and protein-protein interaction networks establishment of differentially expressed proteins(DEPs)between groups.Then western blot was used for verification of selected DEPs.RESULTS The macroscopic colon injury scores and histopathology scores in the HM and EA groups were significantly decreased compared to the rats in the M group(P<0.01).Compared with the N group,a total of 202 DEPs were identified in the M group,including 111 up-regulated proteins and 91 down-regulated proteins,of which 25 and 15 proteins were reversed after HM and EA interventions,respectively.The DEPs were involved in various biological processes such as biological regulation,immune system progression and in multiple pathways including natural killer cell mediated cytotoxicity,intestinal immune network for immunoglobulin A(IgA)production,and FcγR-mediated phagocytosis.The Kyoto Encyclopedia of Genes and Genomes pathways of DEPs between HM and M groups,EA and M groups both included immuneassociated and oxidative phosphorylation.Network analysis revealed that multiple pathways for the DEPs of each group were involved in protein-protein interactions,and the expression of oxidative phosphorylation pathway-related proteins,including ATP synthase subunit g(ATP5L),ATP synthase beta subunit precursor(Atp5f),cytochrome c oxidase subunit 4 isoform 1(Cox4i1)were down-regulated after HM and EA interventions.Subsequent verification of selected DEPs(Synaptic vesicle glycoprotein 2A;nuclear cap binding protein subunit 1;carbamoyl phosphate synthetase 1;Cox4i1;ATP synthase subunit b,Atp5f1;doublecortin like kinase 3)by western blot confirmed the reliability of the iTRAQ data,HM and EA interventions can significantly downregulate the expression of oxidative phosphorylation-associated proteins(Cox4i1,Atp5f1)(P<0.01).CONCLUSION EA and HM could regulate the expression of ATP5L,Atp5f1,Cox4i1 that associated with oxidative phosphorylation,then might regulate immune-related pathways of intestinal immune network for IgA production,FcγR-mediated phagocytosis,thereby alleviating colonic inflammation of DSSinduced UC rats.展开更多
This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is bas...This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is based on the derivation that the peak acceleration is dependent on the product of phase current and current gradient idi/dt.However,the derivation may cause errors due to saturation effect.Thus in this paper,the discrete sample data are firstly acquired based on DC pulse measurement method,by which electromagnetic,torque and peak acceleration characteristics can all be acquired.Then the entire peak acceleration characteristics are obtained by improved Least Square Support Vector Machine(LSSVM).Based on the obtained static peak acceleration characteristics,the time-varied radial vibration model is established based on superposition of natural oscillations of dominant vibration modes.Finally,a simulation model is built up using MATLAB/Simulink.The good agreement between simulation and experiment shows that the proposed method for modeling is feasible and accurate,even under saturation.In addition,since LSSVM does not need any prior knowledge,it is much easier for modeling compared with other existing literatures.展开更多
Spintronics is a new discipline focusing on the research and application of electronic spin properties. After the discovery of the giant magnetoresistance effect in 1988, spintronics has had a huge impact on scientifi...Spintronics is a new discipline focusing on the research and application of electronic spin properties. After the discovery of the giant magnetoresistance effect in 1988, spintronics has had a huge impact on scientific progress and related applications in the development of information technology. In recent decades, the main motivation in spintronics has been efficiently controlling local magnetization using electron flow or voltage rather than controlling the electron flow using magnetization. Using spin-orbit coupling in a material can convert a charge current into a pure spin current(a flow of spin momenta without a charge flow) and generate a spin-orbit torque on the adjacent ferromagnets. The ability of spintronic devices to utilize spin-orbit torques to manipulate the magnetization has resulted in large-scale developments such as magnetic random-access memories and has boosted the spintronic research area. Here in, we review the theoretical and experimental results that have established this subfield of spintronics. We introduce the concept of a pure spin current and spin-orbit torques within the experimental framework, and we review transport-, magnetization-dynamics-, and opticalbased measurements and link then to both phenomenological and microscopic theories of the effect. The focus is on the related progress reported from Chinese universities and institutes, and we specifically highlight the contributions made by Chinese researchers.展开更多
Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor,substrate and solvent,which leads to energy loss and obvious heat transfer limits.In this study,induction heatin...Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor,substrate and solvent,which leads to energy loss and obvious heat transfer limits.In this study,induction heating was employed to boost the catalytic Suzuki-Miyaura cross-coupling reactions by using conductive superparamagnetic microspheres with loaded Pd nanoparticles as heterogeneous catalysts.It was found that,at the same apparent reaction temperatures,the reactions by adopting the induction heating all exhibit better catalytic performance with higher conversion and yield,as compared to the reactions using conventional joule heating.The improvement is mainly attributed to the localized heating effect endowed by high efficiency of the heat transfer from the heat source to catalytic sites,which dissipates the electromagnetic energy through Néel relaxation mechanism.Moreover,it has be found that the reactions have been largely accelerated,resulting in much shorter reaction time required to approach a given value of reactant conversion.These results indicate that the unique heating method based on the superparamagnetic nanomaterials as both the inductive component and catalyst support holds a promising application for fast and efficient heterogeneous catalytic process,and exhibits potential for improving energy transfer efficiency and reducing the side reactions attributed to the uneven temperature profile.展开更多
The influence of austenitizing temperature and austenite grain size on the crystallographic characteristics and mechanical properties of transformation products was investigated in a low-alloy steel.Annealing at a low...The influence of austenitizing temperature and austenite grain size on the crystallographic characteristics and mechanical properties of transformation products was investigated in a low-alloy steel.Annealing at a lower temperature after austenitization at 1050℃ can reduce the vacancy concentration and enhance the stability of austenite,thereby determining the martensite-start(Ms)temperature and density of twin-related V1/V2 variant pairs.V1/V2 variant pairs are predominately generated by autocatalytic nucleation,which can promote transformation by self-accommodation.Annealing at 800℃ after austenitization at 1050℃ generated the highest content of V1/V2 variant pairs,which contributed to high values of strength,Charpy impact energy,and elongation.In addition to refining the austenite grain size,niobium(Nb)microalloying increases the packet boundaries of the transformation products,mainly because the refined austenite grains provide more nucleation sites for the martensitic transformation.However,the density of block boundaries decreases after austenite refinement by Nb microalloying,owing to insufficient autocatalytic nucleation.展开更多
Two years after the coronavirus disease 2019(COVID-19)pandemic,acute hepatitis of unknown etiology in children(AHUCD)began to be reported worldwide.The novel coronavirus and adenovirus were found in pathogen and antib...Two years after the coronavirus disease 2019(COVID-19)pandemic,acute hepatitis of unknown etiology in children(AHUCD)began to be reported worldwide.The novel coronavirus and adenovirus were found in pathogen and antibody tests in AHUCD cases reported by the World Health Organization.Children are not exposed to the viruses that children are generally exposed to owing to COVID-19 infection preventive measures such as isolation and wearing masks;therefore,some researchers have speculated that this disease is related to reduced exposure to pathogens.Some scientists have also speculated that the disease is related to liver injury and adenoviral hepatitis,which are the sequelae of COVID-19.Some evidence also suggests a weak association between the disease and COVID-19 vaccination.Therefore,further research and investigation of the pathogenesis,preventive measures,and early treatment of hepatitis of unknown etiology are required.This study aimed to synthesize available evidence to further elucidate this disease in order to treat and prevent it effectively.展开更多
Vibration absorption efficiency of a variable⁃stiffness nonlinear energy sink(NES)was investigated when the main oscillator was subjected to harmonic and impulse excitations.The slow flow equations of the coupled syst...Vibration absorption efficiency of a variable⁃stiffness nonlinear energy sink(NES)was investigated when the main oscillator was subjected to harmonic and impulse excitations.The slow flow equations of the coupled system were derived by using the complexification⁃averaging method,and the nonlinear equations which describe the steady⁃state response were obtained.As the harmonic excitation force increased,the system which comprises constant⁃stiffness NES generated higher branch responses,greatly reducing the vibration absorption efficiency.The influence of nonlinear stiffness on the responses of the system was investigated.Results show that,with the increase of harmonic exciting force,a reduction of NES stiffness can eliminate the higher branch responses and even the frequency band of strongly modulated responses.The vibration absorption efficiency of variable⁃stiffness NES attached to the linear oscillator for different amplitudes of impulse excitation was investigated.Results show that the proper reduction of nonlinear stiffness under increasing impulse excitation can greatly increase the vibration absorption efficiency of NES,and the variable⁃stiffness design can effectively mitigate the negative influences of the increase of the excitation amplitude on the efficiency of constant⁃stiffness NES.展开更多
Objective:While age has been recognized as a noteworthy factor in preoperative graft selection,the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientifi...Objective:While age has been recognized as a noteworthy factor in preoperative graft selection,the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientific community.This study aimed to explore the correlation between the diameter of autologous tendon grafts and age in anterior cruciate ligament reconstruction(ACLR).Methods:A retrospective review of 388 patients who underwent arthroscopic ACLR with hamstring autografts was performed.Patients were grouped by age to analyze differences in hamstring autograft dia-meter and tendon cross-sectional area(CSA).We explored the correlations between age and graft diameter and between age and the CSA of the popliteal tendon while controlling for the influence of other pertinent variables.Results:Compared with female patients,male patients presented significantly greater autograft diameters and hamstring tendon CSAs(P<0.05).Notably,graft diameter and hamstring tendon CSA varied significantly across different age groups(P<0.05);patients aged>32 years were substantially more likely to have a graft diameter exceeding 8 mm and a CSA surpassing 18.5 mm^(2) than their≤32-year-old counterparts were(P<0.05).Conclusion:This study revealed that graft diameter varies across different age groups,with age independently influencing graft diameter.展开更多
In this paper, we summarize 3D perception-oriented algorithms for perceptually driven 3D video coding. Several perceptual ef- fects have been exploited for 2D video viewing; however, this is not yet the case for 3D vi...In this paper, we summarize 3D perception-oriented algorithms for perceptually driven 3D video coding. Several perceptual ef- fects have been exploited for 2D video viewing; however, this is not yet the case for 3D video viewing. 3D video requires depth perception, which implies binocular effects such as con fl icts, fusion, and rivalry. A better understanding of these effects is necessary for 3D perceptual compression, which provides users with a more comfortable visual experience for video that is de- livered over a channel with limited bandwidth. We present state-of-the-art of 3D visual attention models, 3D just-notice- able difference models, and 3D texture-synthesis models that address 3D human vision issues in 3D video coding and trans-mission.展开更多
基金supported by a grant from the Fund of Chengdu Medical College (CYZYB22-03)。
文摘The mechanism of cell damage during acute pancreatitis (AP) has not been fully elucidated, and there is still a lack of specific or effective treatments. Increasing evidence has implicated mitochondrial dysfunction as a key event in the pathophysiology of AP. Mitochondrial dysfunction is closely related to calcium (Ca^(2+)) overload, intracellular adenosine triphosphate depletion, mitochondrial permeability transition pore openings, loss of mitochondrial membrane potential, mitophagy damage and inflammatory responses. Mitochondrial dysfunction is an early triggering event in the initiation and development of AP,and this organelle damage may precede the release of inflammatory cytokines, intracellular trypsin activation and vacuole formation of pancreatic acinar cells. This review provides further insight into the role of mitochondria in both physiological and pathophysiological aspects of AP, aiming to improve our understanding of the underlying mechanism which may lead to the development of therapeutic and preventive strategies for AP.
基金supported by the National Natural Science Foundation of China(42277087,42130708,42471021,42277482,and 42361144876)the Natural Science Foundation of Guangdong Province(2024A1515012550)+3 种基金the Hainan Institute of National Park grant(KY-23ZK01)the Tsinghua Shenzhen International Graduate School Cross-disciplinary Research and Innovation Fund Research Plan(JC2022011)the Shenzhen Science and Technology Program(JCYJ20240813112106009 and ZDSYS20220606100806014)the Scientific Research Start-up Funds(QD2021030C)from Tsinghua Shenzhen International Graduate School。
文摘Food systems are deeply affected by climate change and air pollution,while being key contributors to these environmental challenges.Understanding the complex interactions among food systems,climate change,and air pollution is crucial for mitigating climate change,improving air quality,and promoting the sustainable development of food systems.However,the literature lacks a comprehensive review of these interactions,particularly in the current phase of rapid development in the field.To address this gap,this study systematically reviews recent research on the impacts of climate change and air pollution on food systems,as well as the greenhouse gas and air pollutant emissions from agri-food systems and their contribution to global climate change and air pollution.In addition,this study summarizes various strategies for mitigation and adaptation,including adjustments in agricultural practices and food supply chains.Profound changes in food systems are urgently needed to enhance adaptability and reduce emissions.This review offers a critical overview of current research on the interactions among food systems,climate change,and air pollution and highlights future research directions to support the transition to sustainable food systems.
基金supported by the National Natural Science Foundation of China(Grant No.51109071)
文摘Pipe cooling is an effective method of mass concrete temperature control, but its accurate and convenient numerical simulation is still a cumbersome problem. An improved embedded model, considering the water temperature variation along the pipe, was proposed for simulating the temperature field of early-age concrete structures containing cooling pipes. The improved model was verified with an engineering example. Then, the p-version self-adaption algorithm for the improved embedded model was deduced, and the initial values and boundary conditions were examined. Comparison of some numerical samples shows that the proposed model can provide satisfying precision and a higher efficiency. The analysis efficiency can be doubled at the same precision, even for a large-scale element. The p-version algorithm can fit grids of different sizes for the temperature field simulation. The convenience of the proposed algorithm lies in the possibility of locating more pipe segments in one element without the need of so regular a shape as in the explicit model.
基金supported by the National Natural Science Foundation of China(No.11772023)。
文摘This paper proposes a fuel-optimal deorbit scheme for space debris deorbit using tethered space tug.The scheme contains three stages named respectively as dragging,maintenance and swinging.In the first stage,the tug,propelled by continuous thrust,tows deorbit to a transfer orbit with a tether.Then in the second stage,the combination of the tug and the debris flies unpowered and uncontrolled to a swing point on the transfer orbit.Finally,in the third stage,the tug is propelled at the swing point and the rotation speed of the tethered system increases such that the debris obtains enough velocity increment.The trajectory optimization of the first stage is established considering the total fuel consumption of the three stages,whereas the dynamic model is simplified for computation efficiency.The solution to the optimal problem is obtained using a direct method based on Gauss pesudospectral discretization.Then a model predictive controller is designed to track the open-loop optimal reference trajectories,reducing the states’deviations caused by model simplification and ignorance of perturbations.Furthermore,it is proved that the fuel-optimal swing point is the apogee of the transfer orbit.The paper analyzes the fuel consumption of a typical scenario and demonstrates effectiveness of the proposed deorbit scheme numerically.
基金the National Natural Science Foundation of China No.81973955,82004475 and 82174501Shanghai Clinical Research Center for Acupuncture and Moxibustion No.20MC1920500+1 种基金Clinical Key Specialty Construction Foundation of Shanghai No.shslczdzk04701Natural Science Foundation of Shanghai No.21ZR1460200
文摘BACKGROUND Ulcerative colitis(UC)is a chronic,nonspecific intestinal inflammatory disease.Acupuncture and moxibustion is proved effective in treating UC,but the mechanism has not been clarified.Proteomic technology has revealed a variety of biological markers related to immunity and inflammation in UC,which provide new insights and directions for the study of mechanism of acupuncture and moxibustion treatment of UC.AIM To investigate the mechanism of electroacupuncture(EA)and herb-partitioned moxibustion(HM)on UC rats by using proteomics technology.METHODS Male Sprague-Dawley rats were randomly divided into the normal(N)group,the dextran sulfate sodium(DSS)-induced UC model(M)group,the HM group,and the EA group.UC rat model was prepared with 3%DSS,and HM and EA interventions at the bilateral Tianshu and Qihai acupoints were performed in HM or EA group.Haematoxylin and eosin staining was used for morphological evaluation of colon tissues.Isotope-labeled relative and absolute quantification(iTRAQ)and liquid chromatography-tandem mass spectrometry were performed for proteome analysis of the colon tissues,followed by bioinformatics analysis and protein-protein interaction networks establishment of differentially expressed proteins(DEPs)between groups.Then western blot was used for verification of selected DEPs.RESULTS The macroscopic colon injury scores and histopathology scores in the HM and EA groups were significantly decreased compared to the rats in the M group(P<0.01).Compared with the N group,a total of 202 DEPs were identified in the M group,including 111 up-regulated proteins and 91 down-regulated proteins,of which 25 and 15 proteins were reversed after HM and EA interventions,respectively.The DEPs were involved in various biological processes such as biological regulation,immune system progression and in multiple pathways including natural killer cell mediated cytotoxicity,intestinal immune network for immunoglobulin A(IgA)production,and FcγR-mediated phagocytosis.The Kyoto Encyclopedia of Genes and Genomes pathways of DEPs between HM and M groups,EA and M groups both included immuneassociated and oxidative phosphorylation.Network analysis revealed that multiple pathways for the DEPs of each group were involved in protein-protein interactions,and the expression of oxidative phosphorylation pathway-related proteins,including ATP synthase subunit g(ATP5L),ATP synthase beta subunit precursor(Atp5f),cytochrome c oxidase subunit 4 isoform 1(Cox4i1)were down-regulated after HM and EA interventions.Subsequent verification of selected DEPs(Synaptic vesicle glycoprotein 2A;nuclear cap binding protein subunit 1;carbamoyl phosphate synthetase 1;Cox4i1;ATP synthase subunit b,Atp5f1;doublecortin like kinase 3)by western blot confirmed the reliability of the iTRAQ data,HM and EA interventions can significantly downregulate the expression of oxidative phosphorylation-associated proteins(Cox4i1,Atp5f1)(P<0.01).CONCLUSION EA and HM could regulate the expression of ATP5L,Atp5f1,Cox4i1 that associated with oxidative phosphorylation,then might regulate immune-related pathways of intestinal immune network for IgA production,FcγR-mediated phagocytosis,thereby alleviating colonic inflammation of DSSinduced UC rats.
基金This work was supported by the National Natural Science Foundation of China under Grant 51277026 and 61674033Natural Science Foundation of Jiangsu Province under Grant BK20161148the Scientific Research Foundation of Graduate School of Southeast University under Grant YBJJ1822.(Corresponding author:Weifeng Sun.)。
文摘This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is based on the derivation that the peak acceleration is dependent on the product of phase current and current gradient idi/dt.However,the derivation may cause errors due to saturation effect.Thus in this paper,the discrete sample data are firstly acquired based on DC pulse measurement method,by which electromagnetic,torque and peak acceleration characteristics can all be acquired.Then the entire peak acceleration characteristics are obtained by improved Least Square Support Vector Machine(LSSVM).Based on the obtained static peak acceleration characteristics,the time-varied radial vibration model is established based on superposition of natural oscillations of dominant vibration modes.Finally,a simulation model is built up using MATLAB/Simulink.The good agreement between simulation and experiment shows that the proposed method for modeling is feasible and accurate,even under saturation.In addition,since LSSVM does not need any prior knowledge,it is much easier for modeling compared with other existing literatures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674142,51771099,11429401,and 51471081)the Program for Changjiang Scholars and Innovative Research Team in University,China(Grant No.IRT-16R35)
文摘Spintronics is a new discipline focusing on the research and application of electronic spin properties. After the discovery of the giant magnetoresistance effect in 1988, spintronics has had a huge impact on scientific progress and related applications in the development of information technology. In recent decades, the main motivation in spintronics has been efficiently controlling local magnetization using electron flow or voltage rather than controlling the electron flow using magnetization. Using spin-orbit coupling in a material can convert a charge current into a pure spin current(a flow of spin momenta without a charge flow) and generate a spin-orbit torque on the adjacent ferromagnets. The ability of spintronic devices to utilize spin-orbit torques to manipulate the magnetization has resulted in large-scale developments such as magnetic random-access memories and has boosted the spintronic research area. Here in, we review the theoretical and experimental results that have established this subfield of spintronics. We introduce the concept of a pure spin current and spin-orbit torques within the experimental framework, and we review transport-, magnetization-dynamics-, and opticalbased measurements and link then to both phenomenological and microscopic theories of the effect. The focus is on the related progress reported from Chinese universities and institutes, and we specifically highlight the contributions made by Chinese researchers.
基金supported by the National Natural Science Foundation of China(Nos.52006032,22001009)the Natural Science Foundation of Anhui Province(No.2008085QB60)。
文摘Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor,substrate and solvent,which leads to energy loss and obvious heat transfer limits.In this study,induction heating was employed to boost the catalytic Suzuki-Miyaura cross-coupling reactions by using conductive superparamagnetic microspheres with loaded Pd nanoparticles as heterogeneous catalysts.It was found that,at the same apparent reaction temperatures,the reactions by adopting the induction heating all exhibit better catalytic performance with higher conversion and yield,as compared to the reactions using conventional joule heating.The improvement is mainly attributed to the localized heating effect endowed by high efficiency of the heat transfer from the heat source to catalytic sites,which dissipates the electromagnetic energy through Néel relaxation mechanism.Moreover,it has be found that the reactions have been largely accelerated,resulting in much shorter reaction time required to approach a given value of reactant conversion.These results indicate that the unique heating method based on the superparamagnetic nanomaterials as both the inductive component and catalyst support holds a promising application for fast and efficient heterogeneous catalytic process,and exhibits potential for improving energy transfer efficiency and reducing the side reactions attributed to the uneven temperature profile.
基金financially supported by the National Key Research and Development Program of China(Grant No.2020YFB0311000)the Research Center for Iron based New Materials(School of Materials Science and Engineering,Tsinghua University&Masteel Co.Ltd.).
文摘The influence of austenitizing temperature and austenite grain size on the crystallographic characteristics and mechanical properties of transformation products was investigated in a low-alloy steel.Annealing at a lower temperature after austenitization at 1050℃ can reduce the vacancy concentration and enhance the stability of austenite,thereby determining the martensite-start(Ms)temperature and density of twin-related V1/V2 variant pairs.V1/V2 variant pairs are predominately generated by autocatalytic nucleation,which can promote transformation by self-accommodation.Annealing at 800℃ after austenitization at 1050℃ generated the highest content of V1/V2 variant pairs,which contributed to high values of strength,Charpy impact energy,and elongation.In addition to refining the austenite grain size,niobium(Nb)microalloying increases the packet boundaries of the transformation products,mainly because the refined austenite grains provide more nucleation sites for the martensitic transformation.However,the density of block boundaries decreases after austenite refinement by Nb microalloying,owing to insufficient autocatalytic nucleation.
文摘Two years after the coronavirus disease 2019(COVID-19)pandemic,acute hepatitis of unknown etiology in children(AHUCD)began to be reported worldwide.The novel coronavirus and adenovirus were found in pathogen and antibody tests in AHUCD cases reported by the World Health Organization.Children are not exposed to the viruses that children are generally exposed to owing to COVID-19 infection preventive measures such as isolation and wearing masks;therefore,some researchers have speculated that this disease is related to reduced exposure to pathogens.Some scientists have also speculated that the disease is related to liver injury and adenoviral hepatitis,which are the sequelae of COVID-19.Some evidence also suggests a weak association between the disease and COVID-19 vaccination.Therefore,further research and investigation of the pathogenesis,preventive measures,and early treatment of hepatitis of unknown etiology are required.This study aimed to synthesize available evidence to further elucidate this disease in order to treat and prevent it effectively.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.11402170 and 11402165)the Tianjin Natural Science Foundation of China(Grant Nos.17JCYBJC18800 and 17JCZDJC38500)
文摘Vibration absorption efficiency of a variable⁃stiffness nonlinear energy sink(NES)was investigated when the main oscillator was subjected to harmonic and impulse excitations.The slow flow equations of the coupled system were derived by using the complexification⁃averaging method,and the nonlinear equations which describe the steady⁃state response were obtained.As the harmonic excitation force increased,the system which comprises constant⁃stiffness NES generated higher branch responses,greatly reducing the vibration absorption efficiency.The influence of nonlinear stiffness on the responses of the system was investigated.Results show that,with the increase of harmonic exciting force,a reduction of NES stiffness can eliminate the higher branch responses and even the frequency band of strongly modulated responses.The vibration absorption efficiency of variable⁃stiffness NES attached to the linear oscillator for different amplitudes of impulse excitation was investigated.Results show that the proper reduction of nonlinear stiffness under increasing impulse excitation can greatly increase the vibration absorption efficiency of NES,and the variable⁃stiffness design can effectively mitigate the negative influences of the increase of the excitation amplitude on the efficiency of constant⁃stiffness NES.
基金This work was supported by the Fundamental Research Funds for the Central Universities(WK9110000143)the USTC Research Funds of the Double First-Class Initiative(YD9110002060)the Health Research Program of Anhui(AHWJ2022b060)。
文摘Objective:While age has been recognized as a noteworthy factor in preoperative graft selection,the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientific community.This study aimed to explore the correlation between the diameter of autologous tendon grafts and age in anterior cruciate ligament reconstruction(ACLR).Methods:A retrospective review of 388 patients who underwent arthroscopic ACLR with hamstring autografts was performed.Patients were grouped by age to analyze differences in hamstring autograft dia-meter and tendon cross-sectional area(CSA).We explored the correlations between age and graft diameter and between age and the CSA of the popliteal tendon while controlling for the influence of other pertinent variables.Results:Compared with female patients,male patients presented significantly greater autograft diameters and hamstring tendon CSAs(P<0.05).Notably,graft diameter and hamstring tendon CSA varied significantly across different age groups(P<0.05);patients aged>32 years were substantially more likely to have a graft diameter exceeding 8 mm and a CSA surpassing 18.5 mm^(2) than their≤32-year-old counterparts were(P<0.05).Conclusion:This study revealed that graft diameter varies across different age groups,with age independently influencing graft diameter.
文摘In this paper, we summarize 3D perception-oriented algorithms for perceptually driven 3D video coding. Several perceptual ef- fects have been exploited for 2D video viewing; however, this is not yet the case for 3D video viewing. 3D video requires depth perception, which implies binocular effects such as con fl icts, fusion, and rivalry. A better understanding of these effects is necessary for 3D perceptual compression, which provides users with a more comfortable visual experience for video that is de- livered over a channel with limited bandwidth. We present state-of-the-art of 3D visual attention models, 3D just-notice- able difference models, and 3D texture-synthesis models that address 3D human vision issues in 3D video coding and trans-mission.
