Multicomponent composites are considered conducive to electromagnetic wave(EMW)absorption,as multiple loss synergistic effect from each component,enhance the attenuation ability of EMW and optimize impedance matching....Multicomponent composites are considered conducive to electromagnetic wave(EMW)absorption,as multiple loss synergistic effect from each component,enhance the attenuation ability of EMW and optimize impedance matching.In this study,carbon material was modified by both semi-conductive and magnetic matters to improve their absorbing performance.The carbon-based fibrous composites of CeO_(2)and Co were prepared by electrospinning and subsequent carbonization.At a filling rate of 35 wt.%,the CeCoC nanocomposite fibers exhibit a minimum RL value of−61.4 dB at 2.2 mm,and an effective absorption bandwidth(EAB)of up to 7.6 GHz.The excellent absorbing performance is derived from the improved dielectric loss and optimized impedance matching.The introduction of rare earth oxide CeO_(2)not only helps to maintain the fibrous structure,but also promotes conduction loss.Especially,oxygen vacancy defects introduced by CeO_(2)greatly improved the dielectric loss capacity.The introduction of Co particles optimizes the impedance matching to reduce the matching thickness and strengthen magnetic loss.This study demonstrates the potential of rare earth oxides in improving EMW absorption performance,and opens up new opportunities for the development of advanced materials for high-performance EMW absorption applications.展开更多
Aiming at addressing the issues of unclear dynamic response mechanisms and insufficient quantification of temperature coupling effects in building structures under long-duration blast loads,this study investigates typ...Aiming at addressing the issues of unclear dynamic response mechanisms and insufficient quantification of temperature coupling effects in building structures under long-duration blast loads,this study investigates typical composite beam-slab structures through integrated blast shock tube experiments and multiscale numerical simulations using Voronoi-coupled Finite-Discrete Element Method(VoroFDEM).The research systematically reveals the dynamic response mechanisms and damage evolution patterns of composite beam-slab structures subjected to prolonged blast loading.An environmenttemperature-coupled P-I curve damage assessment system is established,and a rapid evaluation method based on image crack characteristics is proposed,achieving innovative transition from traditional mechanical indicators to intelligent recognition paradigms.Results demonstrate that composite beam-slab structures exhibit three-phase failure modes:elastic vibration,plastic hinge formation,and global collapse.Numerical simulations identify the brittle-to-ductile transition temperature threshold at-10℃,and establish a temperature-dependent piecewise function-based P-I curve prediction model,whose overpressure asymptote displays nonlinear temperature sensitivity within-50-30℃.A novel dual-mode evaluation methodology integrating Voro-FDEM numerical simulations with image-based damage feature recognition is developed,enabling quantitative mapping between crack area and destruction levels.These findings provide theoretical foundations and technical pathways for rapid blast damage assessment and protective engineering design.展开更多
Aims:Splenectomy combined with pericardial devascularization is one of the important methods to treat hypersplenism,gastrointestinal bleeding,and other complications caused by liver cirrhosis;however,it is accompanied...Aims:Splenectomy combined with pericardial devascularization is one of the important methods to treat hypersplenism,gastrointestinal bleeding,and other complications caused by liver cirrhosis;however,it is accompanied by a high risk of portal vein thrombosis(PVT).This study aimed to explore the preventive and therapeutic effects of proximal splenic vein ligation(PSVL)with postoperative transcatheter anticoagulant therapy(TCAT)on PVT.Methods:This study retrospectively selected 143 patients with liver cirrhosis and portal hypertension,who received splenectomy combined with pericardial devascularization from June 30,2018 to June 30,2021.According to computed tomography photography,within 1 week before the operation,the patients were divided into a prevention group(without preoperative PVT,n=112)and a treatment group(preoperative PVT,n=31).Then,each group was subdivided based on the treatment and prevention measures into PSVL+TCAT(n=70)and systemic anticoagulant therapy(SAT)subgroups(n=73).The preventive and therapeutic effects of PSVL followed by TCAT on PVT were analyzed.Results:The operation time in the PSVL+TCAT subgroups was longer than that in the SAT subgroups(185±76 min vs.161±55 min;p<0.01).There was no difference between the two subgroups in terms of operative bleeding(345±82 mL vs.336±65 mL;p>0.50).There was no operative death,and all patients recovered uneventfully.In the prevention group,procedure-related complications occurred in two patients in the PSVL+TCAT subgroup(3.7%[2/54]),including one patient with slight pancreatitis and one patient with chylous leakage,owing to mobilization of the pancreas.The PVT incidence in the prevention group was significantly different between the two subgroups at postoperative 7th day,3rd month,and 6th month(PSVL+TCAT:0%,11.1%,and 5.6%vs.SAT:39.7%,31.0%,and 20.7%,respectively;all p<0.05).In the treatment group,the thrombus regression rate at postoperative 7th day and disappearance rates at the 3rd month and the 6th month of the PSVL+TCAT subgroup were significantly higher than those in the SAT subgroup after anticoagulant and thrombolysis therapy(PSVL+TCAT:75.0%,68.8%,and 87.5%vs.SAT:20.0%,26.7%,and 40.0%;all p<0.05).Conclusions:PSVL+TCAT reduces the risk of PVT after splenectomy and is safe and effective in treating PVT during surgery for portal hypertension.展开更多
There is an urgent demand for polymer dielectrics in the rapidly growing fields of electric vehicles and energy exploration.However,the existing polymer dielectrics suffer from poor energy density due to the decrease ...There is an urgent demand for polymer dielectrics in the rapidly growing fields of electric vehicles and energy exploration.However,the existing polymer dielectrics suffer from poor energy density due to the decrease of breakdown strength at elevated temperatures,which limits their widespread application.Ultralow content inorganic fillers(<1 vol.%)with appropriate size have been reported to enhance the polarization of polymer matrix,while their influence on breakdown still lack attention.In this work,we developed the dilute polyetherimide(PEI)-Al_(2)O_(3) nanocomposites with different filler size(5,20,and 80 nm)and studied the size effect of nanofillers on the breakdown resistance and energy storage performances of nanocomposite dielectrics.Based on the results of multiscale simulations and tests,the dilute fillers with smaller size(5 nm)exhibit more remarkable enhancement on charge trapping and mechanical strengthening of polymer matrix,and thus yielding higher breakdown strength and a discharged energy density of 4.69 J·cm^(-3)(150℃)and 2.56 J·cm^(-3)(200℃)with a high efficiency of 90%.A long charge-discharge cycling stability up to 105 cycles was also achieved at 150℃.展开更多
At present,in order to overcome electromagnetic interference and prevent electromagnetic harm,the research of new and efficient electromagnetic wave absorbing materials has become the research focus in the field of ma...At present,in order to overcome electromagnetic interference and prevent electromagnetic harm,the research of new and efficient electromagnetic wave absorbing materials has become the research focus in the field of materials science.The one-dimensional structure can promote the impedance matching and attenuation characteristics of the absorbing materials.Electrospinning,as an effective method to prepare nanofibers with high length-diameter ratio,has been widely concerned because it is suitable for struc-tural design of various materials.In this paper,the research progress and absorption properties of nano-fiber materials prepared by electrospinning combined with different processes are introduced.展开更多
基金financially supported by the National Key R&D Program of China(No.2021YFB3502500)the Natural Sci-ence Foundation of Shandong Province(Nos.2022HYYQ-014 and ZR2023QE150)+6 种基金the New 20 Funded Programs for universities of Jinan(No.2021GXRC036)the Provincial Key Research and Devel-opment Program of Shandong(No.2021ZLGX01)the National Nat-ural Science Foundation of China(Nos.22205131 and 22375115)the Postdoctoral Innovation Project of Shandong Province(No.SDCX-ZG-202202015)the Discipline Construction Expendi-ture for Distinguished Young Scholars of Shandong University(No.31370089963141)the Joint Laboratory Project of Elec-tromagnetic Structure Technology(No.637-2022-70-F-037)Qilu Young Scholar Program of Shandong University(No.31370082163127).
文摘Multicomponent composites are considered conducive to electromagnetic wave(EMW)absorption,as multiple loss synergistic effect from each component,enhance the attenuation ability of EMW and optimize impedance matching.In this study,carbon material was modified by both semi-conductive and magnetic matters to improve their absorbing performance.The carbon-based fibrous composites of CeO_(2)and Co were prepared by electrospinning and subsequent carbonization.At a filling rate of 35 wt.%,the CeCoC nanocomposite fibers exhibit a minimum RL value of−61.4 dB at 2.2 mm,and an effective absorption bandwidth(EAB)of up to 7.6 GHz.The excellent absorbing performance is derived from the improved dielectric loss and optimized impedance matching.The introduction of rare earth oxide CeO_(2)not only helps to maintain the fibrous structure,but also promotes conduction loss.Especially,oxygen vacancy defects introduced by CeO_(2)greatly improved the dielectric loss capacity.The introduction of Co particles optimizes the impedance matching to reduce the matching thickness and strengthen magnetic loss.This study demonstrates the potential of rare earth oxides in improving EMW absorption performance,and opens up new opportunities for the development of advanced materials for high-performance EMW absorption applications.
基金supported by Open Research Fund of State Key Laboratory of Target Vulnerability Assessment,Defense Engineering Institute,AMS,PLA(Grant No.YSX2024KFPG002)。
文摘Aiming at addressing the issues of unclear dynamic response mechanisms and insufficient quantification of temperature coupling effects in building structures under long-duration blast loads,this study investigates typical composite beam-slab structures through integrated blast shock tube experiments and multiscale numerical simulations using Voronoi-coupled Finite-Discrete Element Method(VoroFDEM).The research systematically reveals the dynamic response mechanisms and damage evolution patterns of composite beam-slab structures subjected to prolonged blast loading.An environmenttemperature-coupled P-I curve damage assessment system is established,and a rapid evaluation method based on image crack characteristics is proposed,achieving innovative transition from traditional mechanical indicators to intelligent recognition paradigms.Results demonstrate that composite beam-slab structures exhibit three-phase failure modes:elastic vibration,plastic hinge formation,and global collapse.Numerical simulations identify the brittle-to-ductile transition temperature threshold at-10℃,and establish a temperature-dependent piecewise function-based P-I curve prediction model,whose overpressure asymptote displays nonlinear temperature sensitivity within-50-30℃.A novel dual-mode evaluation methodology integrating Voro-FDEM numerical simulations with image-based damage feature recognition is developed,enabling quantitative mapping between crack area and destruction levels.These findings provide theoretical foundations and technical pathways for rapid blast damage assessment and protective engineering design.
基金funded by the Major Research&Development Program of the Ningxia Hui Autonomous Region (2022BEG02038)the Technology Benefit Project of the Ningxia Hui Autonomous Region (2021CMG03017).
文摘Aims:Splenectomy combined with pericardial devascularization is one of the important methods to treat hypersplenism,gastrointestinal bleeding,and other complications caused by liver cirrhosis;however,it is accompanied by a high risk of portal vein thrombosis(PVT).This study aimed to explore the preventive and therapeutic effects of proximal splenic vein ligation(PSVL)with postoperative transcatheter anticoagulant therapy(TCAT)on PVT.Methods:This study retrospectively selected 143 patients with liver cirrhosis and portal hypertension,who received splenectomy combined with pericardial devascularization from June 30,2018 to June 30,2021.According to computed tomography photography,within 1 week before the operation,the patients were divided into a prevention group(without preoperative PVT,n=112)and a treatment group(preoperative PVT,n=31).Then,each group was subdivided based on the treatment and prevention measures into PSVL+TCAT(n=70)and systemic anticoagulant therapy(SAT)subgroups(n=73).The preventive and therapeutic effects of PSVL followed by TCAT on PVT were analyzed.Results:The operation time in the PSVL+TCAT subgroups was longer than that in the SAT subgroups(185±76 min vs.161±55 min;p<0.01).There was no difference between the two subgroups in terms of operative bleeding(345±82 mL vs.336±65 mL;p>0.50).There was no operative death,and all patients recovered uneventfully.In the prevention group,procedure-related complications occurred in two patients in the PSVL+TCAT subgroup(3.7%[2/54]),including one patient with slight pancreatitis and one patient with chylous leakage,owing to mobilization of the pancreas.The PVT incidence in the prevention group was significantly different between the two subgroups at postoperative 7th day,3rd month,and 6th month(PSVL+TCAT:0%,11.1%,and 5.6%vs.SAT:39.7%,31.0%,and 20.7%,respectively;all p<0.05).In the treatment group,the thrombus regression rate at postoperative 7th day and disappearance rates at the 3rd month and the 6th month of the PSVL+TCAT subgroup were significantly higher than those in the SAT subgroup after anticoagulant and thrombolysis therapy(PSVL+TCAT:75.0%,68.8%,and 87.5%vs.SAT:20.0%,26.7%,and 40.0%;all p<0.05).Conclusions:PSVL+TCAT reduces the risk of PVT after splenectomy and is safe and effective in treating PVT during surgery for portal hypertension.
基金supported by National Natural Science Foundation of China(Nos.52421001 and 524B2016).
文摘There is an urgent demand for polymer dielectrics in the rapidly growing fields of electric vehicles and energy exploration.However,the existing polymer dielectrics suffer from poor energy density due to the decrease of breakdown strength at elevated temperatures,which limits their widespread application.Ultralow content inorganic fillers(<1 vol.%)with appropriate size have been reported to enhance the polarization of polymer matrix,while their influence on breakdown still lack attention.In this work,we developed the dilute polyetherimide(PEI)-Al_(2)O_(3) nanocomposites with different filler size(5,20,and 80 nm)and studied the size effect of nanofillers on the breakdown resistance and energy storage performances of nanocomposite dielectrics.Based on the results of multiscale simulations and tests,the dilute fillers with smaller size(5 nm)exhibit more remarkable enhancement on charge trapping and mechanical strengthening of polymer matrix,and thus yielding higher breakdown strength and a discharged energy density of 4.69 J·cm^(-3)(150℃)and 2.56 J·cm^(-3)(200℃)with a high efficiency of 90%.A long charge-discharge cycling stability up to 105 cycles was also achieved at 150℃.
基金supported by the National Key R&D Program of China (No.2021YFB3502500)Natural Science Foundation of Shandong Province (Nos.2022HYYQ-014,ZR2016BM16)+5 种基金the New 20 Funded Programs for Universities of Jinan (2021GXRC036)Provincial Key Research and Development Program of Shandong (2021ZLGX01)National Natural Science Foundation of China (No.22205131)Shenzhen municipal special fund for guiding local scientific and Technological Development (China 2021Szvup071)the Joint Laboratory Project of Electromagnetic Structure Technology (637-2022-70-F-037)Qilu Young Scholar Program of Shandong University (No.31370082163127).
文摘At present,in order to overcome electromagnetic interference and prevent electromagnetic harm,the research of new and efficient electromagnetic wave absorbing materials has become the research focus in the field of materials science.The one-dimensional structure can promote the impedance matching and attenuation characteristics of the absorbing materials.Electrospinning,as an effective method to prepare nanofibers with high length-diameter ratio,has been widely concerned because it is suitable for struc-tural design of various materials.In this paper,the research progress and absorption properties of nano-fiber materials prepared by electrospinning combined with different processes are introduced.
