Piezoelectric active vibration control holds paramount importance in space structures.An embedded piezoelectric actuator with a sandwich configuration is proposed,which enhances control accuracy by integrating various...Piezoelectric active vibration control holds paramount importance in space structures.An embedded piezoelectric actuator with a sandwich configuration is proposed,which enhances control accuracy by integrating various components.Firstly,the electromechanical coupling characteristics of the actuator are revealed,and the model is established.Secondly,the equivalent model of a cylindrical cantilever beam is investigated as the object,and the feasibility of the vibration control of the actuator is verified by simulation.Finally,the prototype comprised of two actuators,which respectively use the proposed embedded actuators for producing the vibration and suppressing the vibration,is developed,and the measurement system is constructed.Experimental results demonstrate the excellent control efficiency in two orthogonal directions,achieving a minimum vibration amplitude control of 0.00102 mm and a maximum vibration control of-42.74 d B.The integrated structure offers fast response,lightness,adaptability,and high control efficiency,which is conducive to enhancing the vibration control.展开更多
BACKGROUND Acute liver failure(ALF)with sepsis is associated with rapid disease progression and high mortality.Therefore,early detection of high-risk sepsis subgroups in patients with ALF is crucial.AIM To develop and...BACKGROUND Acute liver failure(ALF)with sepsis is associated with rapid disease progression and high mortality.Therefore,early detection of high-risk sepsis subgroups in patients with ALF is crucial.AIM To develop and validate an accurate nomogram model for predicting the risk of sepsis in patients with ALF.METHODS We retrieved data from the Medical Information Mart for Intensive Care(MIMIC)IV database and the Fifth Medical Center of Chinese PLA General Hospital(FMCPH).Univariate and multivariate logistic regression analysis were used to identify risk factors for sepsis in ALF and were subsequently incorporated to construct a nomogram model[sepsis in ALF(SIALF)].The discrimination ability,calibration,and clinical applicability of the SIALF model were evaluated by the area under receiver operating characteristic curve,calibration curves,and decision curve analysis,respectively.The Kaplan-Meier curves were used for robustness check.The SIALF model was internally validated using the bootstrapping method with the MIMIC validation cohort and externally validated by the FMCPH cohort.RESULTS A total of 738 patients with ALF patients were included in this study,with 510 from the MIMIC IV database and 228 from the FMCPH cohort.In the MIMIC IV cohort,387(75.89%)patients developed sepsis.Multivariate logistic regression analysis revealed that age[odds ratio(OR)=1.016,95%confidence interval(CI):1.003-1.028,P=0.017],total bilirubin(OR=1.047,95%CI:1.008-1.088,P=0.017),lactate dehydrogenase(OR=1.001,95%CI:1.000-1.001,P<0.001),albumin(OR=0.436,95%CI:0.274-0.692,P=0.003),and mechanical ventilation(OR=1.985,95%CI:1.269-3.105,P=0.003)were independent risk factors associated with sepsis in patients with ALF.The SIALF model demonstrated satisfactory accuracy and clinical utility with area under receiver operating characteristic curve values of 0.849,0.847,and 0.835 for the internal derivation,internal validation,and external validation cohort,respectively,which outperformed the Sequential Organ Failure Assessment scores of 0.733,0.746,and 0.721 and systemic inflammatory response syndrome scores of 0.578,0.653,and 0.615,respectively.The decision curve analysis and calibration curves indicated superior clinical utility and efficiency than other score systems.Based on the risk stratification score derived from the SIALF model,the Kaplan-Meier curves effectively discriminated the real high-risk subpopulation.To enhance the clinical utility,we constructed an online dynamic version,enabling physicians to evaluate patients’condition and track disease progression in real-time.CONCLUSION Based on easily identifiable clinical data,we developed the SIALF model to predict the risk of sepsis in patients with ALF.The model demonstrated robust predictive efficiency,outperformed Sequential Organ Failure Assessment and systemic inflammatory response syndrome scores,and was validated in an external cohort.The model-based risk stratification and online calculator might further facilitate the early detection and appropriate treatment for this subpopulation.展开更多
BACKGROUND Post-operative infection is a common and serious complication following drugeluting trans arterial chemo embolization(D-TACE)in patients with hepatocellular carcinoma(HCC),potentially compromising treatment...BACKGROUND Post-operative infection is a common and serious complication following drugeluting trans arterial chemo embolization(D-TACE)in patients with hepatocellular carcinoma(HCC),potentially compromising treatment efficacy and increasing morbidity.AIM To investigate the risk factors associated with post-operative infection in HCC patients undergoing D-TACE,and to provide evidence for clinical prevention and targeted intervention strategies.METHODS Clinical data of 77 primary HCC patients who underwent D-TACE in our hospital from January 2022 to December 2023 were retrospectively analyzed.Patient demographics,laboratory test results,tumor characteristics,and surgery-related parameters were collected.Univariate and multivariate logistic regression analyses were performed to identify risk factors for post-operative infection.RESULTS Post-operative infection occurred in 20 cases(25.97%)among the 77 patients.Univariate analysis showed that age≥65 years,Child-Pugh grade B,tumor diameter≥5 cm,operation time≥120 minutes,preoperative albumin<35 g/L,and comorbid diabetes were significantly associated with post-operative infection(P<0.05).Multivariate logistic regression analysis identified Child-Pugh grade B(OR=2.851,95%CI:1.426-5.698),operation time≥120 minutes(OR=2.367,95%CI:1.238-4.523),and preoperative albumin<35 g/L(OR=2.156,95%CI:1.147-4.052)as independent risk factors for post-operative infection.CONCLUSION Liver function status,operation time,and preoperative albumin level are significant factors affecting post-operative infection in HCC patients undergoing D-TACE.For high-risk patients,enhanced perioperative management,appropriate timing of surgery,and active improvement of nutritional status should be implemented to reduce the risk of post-operative infection.展开更多
The degradation of animal carcasses can lead to rapid waste release(e.g.,pathogenic bacteria,viruses,prions,or parasites)and also result in nutrient accumulation in the surrounding environment.However,how viral profil...The degradation of animal carcasses can lead to rapid waste release(e.g.,pathogenic bacteria,viruses,prions,or parasites)and also result in nutrient accumulation in the surrounding environment.However,how viral profile responds and influences nutrient pool(carbon(C),nitrogen(N),phosphorus(P)and sulfur(S))in polluted water caused by animal carcass decomposition had not been explored.Here,we combined metagenomic analysis,16S rRNA gene sequencing and water physicochemical assessment to explore the response of viral communities under different temperatures(23℃,26℃,29℃,32℃,and 35℃)in water polluted by cadaver,as well as compare the contribution of viral/bacterial communities on water nutrient pool.We found that a total of 15,240 viral species were classified and mainly consisted of Siphoviridae.Both temperature and carrion reduced the viral diversity and abundance.Only a small portion of the viruses(∼8.8%)had significant negative correlations with temperature,while most were not sensitive.Our results revealed that the viruses had lager contribution on nutrient pool than bacteria.Besides,viral-related functional genes involved in C,N,P and S cycling.These functional genes declined during carcass decomposition and covered part of the central nutrient cycle metabolism(including carbon sugar transformation,denitrification,P mineralization and extracelluar sulfate transfer,etc.).Our result implies that human regulation of virus communities may be more important than bacterial communities in regulating and managing polluted water quality and nutrition.展开更多
We examined the possible multiple defects induced by acute and prolonged exposure to high levels of manganese（Mn） solution by monitoring the endpoints of lifespan,development,reproduction,and stress response.Our dat...We examined the possible multiple defects induced by acute and prolonged exposure to high levels of manganese（Mn） solution by monitoring the endpoints of lifespan,development,reproduction,and stress response.Our data suggest that acute exposure（6 h） to Mn did not cause severe defects of life span,development,and reproduction,similarly,no significant defect could be found in animals exposed to a low concentration of Mn（2.5 μmol/L） for 48 h.In contrast,prolonged exposure（48 h） to high Mn concentrations（75 and 200 μmol/L） resulted in significant defects of life span,development,and reproduction,as well as the increase of the percentage of population with hsp-16.2：：gfp expression indicating the obvious induction of stress responses in exposed animals.Moreover,prolonged exposure（48 h） to high concentrations（75 and 200 μmol/L） of Mn decreased the expression levels of antioxidant genes of sod-1,sod-2,sod-3,and sod-4 compared to control.Therefore,prolonged exposure to high concentrations of Mn will induce the severe defects of life span,development,and reproduction in nematodes possibly by affecting the stress response and expression of antioxidant genes in Caenorhabditis elegans.展开更多
Dear Editor, A microgravity environment in space, the elasticity of the tether,and complex flexible appendages make the tethered-towing system a nonlinear and underactuated system, which is sensitive and difficult to ...Dear Editor, A microgravity environment in space, the elasticity of the tether,and complex flexible appendages make the tethered-towing system a nonlinear and underactuated system, which is sensitive and difficult to stabilize. This letter develops a controller based on wave propagation for tethered towing of defunct satellites, and carries out a robustness analysis of the controller via numerical simulation.展开更多
The insulation effect of ceramic coating in a turbine blade is of great importance for the service of engine in the field of aviation industry. Fabricating microstructure in the thermal barrier coatings(TBCs) is consi...The insulation effect of ceramic coating in a turbine blade is of great importance for the service of engine in the field of aviation industry. Fabricating microstructure in the thermal barrier coatings(TBCs) is considered to be able to enhance the thermal insulation effect. In this study, the traditional three-layer structure, containing ceramic top coat, bonding coat and substrate, is firstly simplified into a double-layer structure, where only ceramic layer and substrate are left, for analyzing the thermal insulation. Afterwards, the thermal insulation effect of the designed microstructure in the bonding coat of the three-layer structure is further studied. Column-like microstructures, filled with hollow ceramic microspheres in the interspace, are designed to improve the thermal insulation effect. The size parameters of the designed microstructure were optimized. The existence of the designed microstructure can significantly prolong the efficiency of thermal barrier coatings. The insulation temperature between the heating surface and lower surface of the substrate can exceed 300℃ and the thermal balance time has a big improvement of 240 s, more than 50%, than the traditional TBCs structure. Compared with the TBCs structure without microstructure, the designed microstructure can significantly improve the insulation temperature of more than 110℃.展开更多
This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear Volterra delay-integro-differential equations. We investigate the dissipativity properties of （k, l）- algebraic...This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear Volterra delay-integro-differential equations. We investigate the dissipativity properties of （k, l）- algebraically stable multistep Runge-Kutta methods with constrained grid and an uniform grid. The finite- dimensional and infinite-dimensional dissipativity results of （k, /）-algebraically stable Runge-Kutta methods are obtained.展开更多
A method is proposed to select the target sequence for a J 2-perturbed multiple debris rendezvous mission aimed at removing dozens of debris from several thousand debris candidates running on sun-synchronous orbits(SS...A method is proposed to select the target sequence for a J 2-perturbed multiple debris rendezvous mission aimed at removing dozens of debris from several thousand debris candidates running on sun-synchronous orbits(SSO).The solving methodology proceeds in two steps:Firstly,the variance of the right ascension of ascending node(RAAN)of the debris group is used for narrowing down the potential debris candidate;secondly,the debris of the candidate group that has closest RAAN to the current debris is chosen as the next debris.The low thrust near-minimum-fuel trajectories of each rendezvous leg are obtained by the indirect optimization method.The proposed approach is demonstrated for the problem of the 8th China Trajectory Optimization Competition(CTOC).The radar cross section(RCS)of the debris is also considered in the first step since the primary performance index of the competition is to maximize the total RCS of the debris visited.The results show that the proposed approach achieves better performance within a competition period.Of the many rendezvous sequences found,the best one submitted for the competition obtained a total RCS of 184 by accomplishing rendezvous with 70 debris within a transfer duration of one year.展开更多
Background:Severe fever with thrombocytopenia syndrome virus(SFTSV)is a tick-borne bunyavirus that could cause a severe hemorrhagic fever termed SFTS with a high fatality rate of up to 30%.Importantly,SFTSV is frequen...Background:Severe fever with thrombocytopenia syndrome virus(SFTSV)is a tick-borne bunyavirus that could cause a severe hemorrhagic fever termed SFTS with a high fatality rate of up to 30%.Importantly,SFTSV is frequently transmitted from person-to-person and patients’blood or excreta are considered as the risk factors for transmission of SFTSV.However,the mechanism of person-to-person transmission of SFTSV is still elusive.Methods:In this study,wild-type(WT)C57BL/6 J mice and a lethal SFTSV mouse model IFNAR−/−A129 mice were utilized to evaluate whether SFTSV could be transmitted via oral or ocular routes.C57BL/6 J mice were inoculated with cell-cultured SFTSV via oral and ocular inoculation.IFNAR−/−A129 mice were inoculated with cell-cultured SFTSV or SFTSV infected mouse acute sera via oral and ocular inoculation.Results:We found that SFTSV antibody positive rates in C57BL/6 J mice were 70%(7/10)and 30%(3/10)in the oral inoculation group and ocular inoculation group,respectively on day 21 post SFTSV inoculation.The mortality rates of IFNAR−/−mice with oral and ocular inoculation of cell-cultured SFTSV were 100%and 83.33%(5/6),respectively on day 6 post inoculation.The mortality rates of IFNAR−/−mice with oral and ocular inoculation of SFTSV infected mouse acute serum were 100%and 66.67%(4/6),respectively on day 9 post inoculation.Conclusions:Together,our results show that SFTSV can be transmitted effectively through oral and ocular mem-brane,suggesting exposure to SFTS positive excreta may be a high-risk factor of nosocomial transmission of SFTSV in hospitals and/or families.Family members and healthcare workers should be protected properly during taking care of SFTS patients to prevent SFTSV nosocomial infection.展开更多
作为锂离子电池的潜在替代品,钠离子电池由于成本、安全性等方面的优势吸引了广泛关注.但如何进一步提高其正极材料的能量密度仍是挑战,而通过激活阴离子氧化还原提供额外容量是一种可行的策略.本文报告了一种高性能锰基氧化物正极材料,...作为锂离子电池的潜在替代品,钠离子电池由于成本、安全性等方面的优势吸引了广泛关注.但如何进一步提高其正极材料的能量密度仍是挑战,而通过激活阴离子氧化还原提供额外容量是一种可行的策略.本文报告了一种高性能锰基氧化物正极材料,Na_(0.67)Mg_(0.1)Zn_(0.1)Mn_(0.8)O_(2)(NMZMO).通过共掺杂策略协同激活阴离子氧化还原,此材料首圈可以放出~233 mAh g^(-1)的超高容量,明显高于Mg或Zn单掺杂的同类材料.综合多种光谱技术,作者证明了更高的容量源于更强的阴离子氧化还原活性.结合中子全散射以及共振非弹性X射线散射发现,Mg与Zn在高电压下会向面外迁移至四面体位点,诱导面内重排形成空位团簇,将氧阴离子以分子O_(2)的形式困于其中.Mg/Zn共存时,刺激了彼此更多的向面外迁移,为形成更多晶内分子O_(2)提供先决条件.本文提出了关于阴离子氧化还原的新见解,并为高容量钠电正极材料的开发提供了理论依据.展开更多
A precise dynamic model for towing and removing a defunct satellite with solar panels in orbit using a tethered net often has low computational efficiency owing to the complex contact and collision between the net and...A precise dynamic model for towing and removing a defunct satellite with solar panels in orbit using a tethered net often has low computational efficiency owing to the complex contact and collision between the net and panels,which is not conducive to research.To solve this problem,a“single main tether–multiple subtether”bifurcation structure with beads was employed as the tethered net model.This study investigated the dynamics of tethered defunct satellites with solar panels,particularly the behavior of the attitude of the tethered satellite,oscillation of the main tether,and vibration of solar panels under different conditions.The results showed that different attachment configurations of the subtethers and the flexibility of the main tether have an evident impact on the dynamic characteristics of the system.展开更多
Background:During the course of an epidemic of a potentially fatal disease,it is difficult to accurately estimate the case fatality rate(CFR)because many calculation methods do not account for the delay between case c...Background:During the course of an epidemic of a potentially fatal disease,it is difficult to accurately estimate the case fatality rate(CFR)because many calculation methods do not account for the delay between case confirmation and disease outcome.Taking the coronavirus disease-2019(COVID-19)as an example,this study aimed to develop a new method for CFR calculation while the pandemic was ongoing.Methods:We developed a new method for CFR calculation based on the following formula:number of deaths divided by the number of cases T days before,where T is the average delay between case confirmation and disease outcome.An objective law was found using simulated data that states if the hypothesized T is equal to the true T,the calculated real-time CFR remains constant;whereas if the hypothesized T is greater(or smaller)than the true T,the real-time CFR will gradually decrease(or increase)as the days progress until it approaches the true CFR.Results:Based on the discovered law,it was estimated that the true CFR of COVID-19 at the initial stage of the pandemic in China,excluding Hubei Province,was 0.8%;and in Hubei Province,it was 6.6%.The calculated CFRs predicted the death count with almost complete accuracy.Conclusions:The method could be used for the accurate calculation of the true CFR during a pandemic,instead of waiting until the end of the pandemic,whether the pandemic is under control or not.It could provide those involved in outbreak control a clear view of the timeliness of case confirmations.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52275022,52175015 and U2037603)the Natural Science Foundation of Jiangsu Province,China(Nos.BK20222011 and BK20230093)the State Key Laboratory of Mechanics and Control for Aerospace Structures,China(No.MCAS-S-0223G01)。
文摘Piezoelectric active vibration control holds paramount importance in space structures.An embedded piezoelectric actuator with a sandwich configuration is proposed,which enhances control accuracy by integrating various components.Firstly,the electromechanical coupling characteristics of the actuator are revealed,and the model is established.Secondly,the equivalent model of a cylindrical cantilever beam is investigated as the object,and the feasibility of the vibration control of the actuator is verified by simulation.Finally,the prototype comprised of two actuators,which respectively use the proposed embedded actuators for producing the vibration and suppressing the vibration,is developed,and the measurement system is constructed.Experimental results demonstrate the excellent control efficiency in two orthogonal directions,achieving a minimum vibration amplitude control of 0.00102 mm and a maximum vibration control of-42.74 d B.The integrated structure offers fast response,lightness,adaptability,and high control efficiency,which is conducive to enhancing the vibration control.
基金Supported by National Key Research and Development Program,No.2022YFA1103501。
文摘BACKGROUND Acute liver failure(ALF)with sepsis is associated with rapid disease progression and high mortality.Therefore,early detection of high-risk sepsis subgroups in patients with ALF is crucial.AIM To develop and validate an accurate nomogram model for predicting the risk of sepsis in patients with ALF.METHODS We retrieved data from the Medical Information Mart for Intensive Care(MIMIC)IV database and the Fifth Medical Center of Chinese PLA General Hospital(FMCPH).Univariate and multivariate logistic regression analysis were used to identify risk factors for sepsis in ALF and were subsequently incorporated to construct a nomogram model[sepsis in ALF(SIALF)].The discrimination ability,calibration,and clinical applicability of the SIALF model were evaluated by the area under receiver operating characteristic curve,calibration curves,and decision curve analysis,respectively.The Kaplan-Meier curves were used for robustness check.The SIALF model was internally validated using the bootstrapping method with the MIMIC validation cohort and externally validated by the FMCPH cohort.RESULTS A total of 738 patients with ALF patients were included in this study,with 510 from the MIMIC IV database and 228 from the FMCPH cohort.In the MIMIC IV cohort,387(75.89%)patients developed sepsis.Multivariate logistic regression analysis revealed that age[odds ratio(OR)=1.016,95%confidence interval(CI):1.003-1.028,P=0.017],total bilirubin(OR=1.047,95%CI:1.008-1.088,P=0.017),lactate dehydrogenase(OR=1.001,95%CI:1.000-1.001,P<0.001),albumin(OR=0.436,95%CI:0.274-0.692,P=0.003),and mechanical ventilation(OR=1.985,95%CI:1.269-3.105,P=0.003)were independent risk factors associated with sepsis in patients with ALF.The SIALF model demonstrated satisfactory accuracy and clinical utility with area under receiver operating characteristic curve values of 0.849,0.847,and 0.835 for the internal derivation,internal validation,and external validation cohort,respectively,which outperformed the Sequential Organ Failure Assessment scores of 0.733,0.746,and 0.721 and systemic inflammatory response syndrome scores of 0.578,0.653,and 0.615,respectively.The decision curve analysis and calibration curves indicated superior clinical utility and efficiency than other score systems.Based on the risk stratification score derived from the SIALF model,the Kaplan-Meier curves effectively discriminated the real high-risk subpopulation.To enhance the clinical utility,we constructed an online dynamic version,enabling physicians to evaluate patients’condition and track disease progression in real-time.CONCLUSION Based on easily identifiable clinical data,we developed the SIALF model to predict the risk of sepsis in patients with ALF.The model demonstrated robust predictive efficiency,outperformed Sequential Organ Failure Assessment and systemic inflammatory response syndrome scores,and was validated in an external cohort.The model-based risk stratification and online calculator might further facilitate the early detection and appropriate treatment for this subpopulation.
文摘BACKGROUND Post-operative infection is a common and serious complication following drugeluting trans arterial chemo embolization(D-TACE)in patients with hepatocellular carcinoma(HCC),potentially compromising treatment efficacy and increasing morbidity.AIM To investigate the risk factors associated with post-operative infection in HCC patients undergoing D-TACE,and to provide evidence for clinical prevention and targeted intervention strategies.METHODS Clinical data of 77 primary HCC patients who underwent D-TACE in our hospital from January 2022 to December 2023 were retrospectively analyzed.Patient demographics,laboratory test results,tumor characteristics,and surgery-related parameters were collected.Univariate and multivariate logistic regression analyses were performed to identify risk factors for post-operative infection.RESULTS Post-operative infection occurred in 20 cases(25.97%)among the 77 patients.Univariate analysis showed that age≥65 years,Child-Pugh grade B,tumor diameter≥5 cm,operation time≥120 minutes,preoperative albumin<35 g/L,and comorbid diabetes were significantly associated with post-operative infection(P<0.05).Multivariate logistic regression analysis identified Child-Pugh grade B(OR=2.851,95%CI:1.426-5.698),operation time≥120 minutes(OR=2.367,95%CI:1.238-4.523),and preoperative albumin<35 g/L(OR=2.156,95%CI:1.147-4.052)as independent risk factors for post-operative infection.CONCLUSION Liver function status,operation time,and preoperative albumin level are significant factors affecting post-operative infection in HCC patients undergoing D-TACE.For high-risk patients,enhanced perioperative management,appropriate timing of surgery,and active improvement of nutritional status should be implemented to reduce the risk of post-operative infection.
基金supported by the National Natural Science Foundation of China (No.42007026)the Medical Innovation and Development Project of Lanzhou University (lzuyxcx-2022-172)
文摘The degradation of animal carcasses can lead to rapid waste release(e.g.,pathogenic bacteria,viruses,prions,or parasites)and also result in nutrient accumulation in the surrounding environment.However,how viral profile responds and influences nutrient pool(carbon(C),nitrogen(N),phosphorus(P)and sulfur(S))in polluted water caused by animal carcass decomposition had not been explored.Here,we combined metagenomic analysis,16S rRNA gene sequencing and water physicochemical assessment to explore the response of viral communities under different temperatures(23℃,26℃,29℃,32℃,and 35℃)in water polluted by cadaver,as well as compare the contribution of viral/bacterial communities on water nutrient pool.We found that a total of 15,240 viral species were classified and mainly consisted of Siphoviridae.Both temperature and carrion reduced the viral diversity and abundance.Only a small portion of the viruses(∼8.8%)had significant negative correlations with temperature,while most were not sensitive.Our results revealed that the viruses had lager contribution on nutrient pool than bacteria.Besides,viral-related functional genes involved in C,N,P and S cycling.These functional genes declined during carcass decomposition and covered part of the central nutrient cycle metabolism(including carbon sugar transformation,denitrification,P mineralization and extracelluar sulfate transfer,etc.).Our result implies that human regulation of virus communities may be more important than bacterial communities in regulating and managing polluted water quality and nutrition.
基金supported by the National Natural Science Foundation of China (No. 30771113, 30870810)the Program for New Century Excellent Talents in University
文摘We examined the possible multiple defects induced by acute and prolonged exposure to high levels of manganese（Mn） solution by monitoring the endpoints of lifespan,development,reproduction,and stress response.Our data suggest that acute exposure（6 h） to Mn did not cause severe defects of life span,development,and reproduction,similarly,no significant defect could be found in animals exposed to a low concentration of Mn（2.5 μmol/L） for 48 h.In contrast,prolonged exposure（48 h） to high Mn concentrations（75 and 200 μmol/L） resulted in significant defects of life span,development,and reproduction,as well as the increase of the percentage of population with hsp-16.2：：gfp expression indicating the obvious induction of stress responses in exposed animals.Moreover,prolonged exposure（48 h） to high concentrations（75 and 200 μmol/L） of Mn decreased the expression levels of antioxidant genes of sod-1,sod-2,sod-3,and sod-4 compared to control.Therefore,prolonged exposure to high concentrations of Mn will induce the severe defects of life span,development,and reproduction in nematodes possibly by affecting the stress response and expression of antioxidant genes in Caenorhabditis elegans.
文摘Dear Editor, A microgravity environment in space, the elasticity of the tether,and complex flexible appendages make the tethered-towing system a nonlinear and underactuated system, which is sensitive and difficult to stabilize. This letter develops a controller based on wave propagation for tethered towing of defunct satellites, and carries out a robustness analysis of the controller via numerical simulation.
基金financially supported by the National Natural Science Foundation of China(11372037,11572041,and 11232008)
文摘The insulation effect of ceramic coating in a turbine blade is of great importance for the service of engine in the field of aviation industry. Fabricating microstructure in the thermal barrier coatings(TBCs) is considered to be able to enhance the thermal insulation effect. In this study, the traditional three-layer structure, containing ceramic top coat, bonding coat and substrate, is firstly simplified into a double-layer structure, where only ceramic layer and substrate are left, for analyzing the thermal insulation. Afterwards, the thermal insulation effect of the designed microstructure in the bonding coat of the three-layer structure is further studied. Column-like microstructures, filled with hollow ceramic microspheres in the interspace, are designed to improve the thermal insulation effect. The size parameters of the designed microstructure were optimized. The existence of the designed microstructure can significantly prolong the efficiency of thermal barrier coatings. The insulation temperature between the heating surface and lower surface of the substrate can exceed 300℃ and the thermal balance time has a big improvement of 240 s, more than 50%, than the traditional TBCs structure. Compared with the TBCs structure without microstructure, the designed microstructure can significantly improve the insulation temperature of more than 110℃.
基金supported by National Natural Science Foundation of China (No. 11171125,91130003)Natural Science Foundation of Hubei (No. 2011CDB289)Youth Foundation of Naval University of Engineering (No.HGDQNJJ10003)
文摘This paper is concerned with the numerical dissipativity of multistep Runge-Kutta methods for nonlinear Volterra delay-integro-differential equations. We investigate the dissipativity properties of （k, l）- algebraically stable multistep Runge-Kutta methods with constrained grid and an uniform grid. The finite- dimensional and infinite-dimensional dissipativity results of （k, /）-algebraically stable Runge-Kutta methods are obtained.
基金We are very grateful to the organizers of the 8th China Trajectory Optimization Competition for the interesting and complex problemMost methods presented in this paper were developed under the National Natural Science Foundation of China(Nos.11172036,11572037,and 11402021)the Excellent Young Scholars Research Fund of Beijing Institute of Technology(No.2015YG0101).
文摘A method is proposed to select the target sequence for a J 2-perturbed multiple debris rendezvous mission aimed at removing dozens of debris from several thousand debris candidates running on sun-synchronous orbits(SSO).The solving methodology proceeds in two steps:Firstly,the variance of the right ascension of ascending node(RAAN)of the debris group is used for narrowing down the potential debris candidate;secondly,the debris of the candidate group that has closest RAAN to the current debris is chosen as the next debris.The low thrust near-minimum-fuel trajectories of each rendezvous leg are obtained by the indirect optimization method.The proposed approach is demonstrated for the problem of the 8th China Trajectory Optimization Competition(CTOC).The radar cross section(RCS)of the debris is also considered in the first step since the primary performance index of the competition is to maximize the total RCS of the debris visited.The results show that the proposed approach achieves better performance within a competition period.Of the many rendezvous sequences found,the best one submitted for the competition obtained a total RCS of 184 by accomplishing rendezvous with 70 debris within a transfer duration of one year.
基金This study was supported by the National Natural Sci-ence Funds of China(81971939 and 31570167)the Fundamental Research Funds for the Central Universities(2042021kf0046).
文摘Background:Severe fever with thrombocytopenia syndrome virus(SFTSV)is a tick-borne bunyavirus that could cause a severe hemorrhagic fever termed SFTS with a high fatality rate of up to 30%.Importantly,SFTSV is frequently transmitted from person-to-person and patients’blood or excreta are considered as the risk factors for transmission of SFTSV.However,the mechanism of person-to-person transmission of SFTSV is still elusive.Methods:In this study,wild-type(WT)C57BL/6 J mice and a lethal SFTSV mouse model IFNAR−/−A129 mice were utilized to evaluate whether SFTSV could be transmitted via oral or ocular routes.C57BL/6 J mice were inoculated with cell-cultured SFTSV via oral and ocular inoculation.IFNAR−/−A129 mice were inoculated with cell-cultured SFTSV or SFTSV infected mouse acute sera via oral and ocular inoculation.Results:We found that SFTSV antibody positive rates in C57BL/6 J mice were 70%(7/10)and 30%(3/10)in the oral inoculation group and ocular inoculation group,respectively on day 21 post SFTSV inoculation.The mortality rates of IFNAR−/−mice with oral and ocular inoculation of cell-cultured SFTSV were 100%and 83.33%(5/6),respectively on day 6 post inoculation.The mortality rates of IFNAR−/−mice with oral and ocular inoculation of SFTSV infected mouse acute serum were 100%and 66.67%(4/6),respectively on day 9 post inoculation.Conclusions:Together,our results show that SFTSV can be transmitted effectively through oral and ocular mem-brane,suggesting exposure to SFTS positive excreta may be a high-risk factor of nosocomial transmission of SFTSV in hospitals and/or families.Family members and healthcare workers should be protected properly during taking care of SFTS patients to prevent SFTSV nosocomial infection.
基金supported by the National Key R&D Program of China(2020YFA0406203)Shenzhen Fundamental Research Program(GXWD20201231165807007-20200807125314001)the National Natural Science Foundation of China(U2032167 and 52072008)。
文摘作为锂离子电池的潜在替代品,钠离子电池由于成本、安全性等方面的优势吸引了广泛关注.但如何进一步提高其正极材料的能量密度仍是挑战,而通过激活阴离子氧化还原提供额外容量是一种可行的策略.本文报告了一种高性能锰基氧化物正极材料,Na_(0.67)Mg_(0.1)Zn_(0.1)Mn_(0.8)O_(2)(NMZMO).通过共掺杂策略协同激活阴离子氧化还原,此材料首圈可以放出~233 mAh g^(-1)的超高容量,明显高于Mg或Zn单掺杂的同类材料.综合多种光谱技术,作者证明了更高的容量源于更强的阴离子氧化还原活性.结合中子全散射以及共振非弹性X射线散射发现,Mg与Zn在高电压下会向面外迁移至四面体位点,诱导面内重排形成空位团簇,将氧阴离子以分子O_(2)的形式困于其中.Mg/Zn共存时,刺激了彼此更多的向面外迁移,为形成更多晶内分子O_(2)提供先决条件.本文提出了关于阴离子氧化还原的新见解,并为高容量钠电正极材料的开发提供了理论依据.
文摘A precise dynamic model for towing and removing a defunct satellite with solar panels in orbit using a tethered net often has low computational efficiency owing to the complex contact and collision between the net and panels,which is not conducive to research.To solve this problem,a“single main tether–multiple subtether”bifurcation structure with beads was employed as the tethered net model.This study investigated the dynamics of tethered defunct satellites with solar panels,particularly the behavior of the attitude of the tethered satellite,oscillation of the main tether,and vibration of solar panels under different conditions.The results showed that different attachment configurations of the subtethers and the flexibility of the main tether have an evident impact on the dynamic characteristics of the system.
文摘Background:During the course of an epidemic of a potentially fatal disease,it is difficult to accurately estimate the case fatality rate(CFR)because many calculation methods do not account for the delay between case confirmation and disease outcome.Taking the coronavirus disease-2019(COVID-19)as an example,this study aimed to develop a new method for CFR calculation while the pandemic was ongoing.Methods:We developed a new method for CFR calculation based on the following formula:number of deaths divided by the number of cases T days before,where T is the average delay between case confirmation and disease outcome.An objective law was found using simulated data that states if the hypothesized T is equal to the true T,the calculated real-time CFR remains constant;whereas if the hypothesized T is greater(or smaller)than the true T,the real-time CFR will gradually decrease(or increase)as the days progress until it approaches the true CFR.Results:Based on the discovered law,it was estimated that the true CFR of COVID-19 at the initial stage of the pandemic in China,excluding Hubei Province,was 0.8%;and in Hubei Province,it was 6.6%.The calculated CFRs predicted the death count with almost complete accuracy.Conclusions:The method could be used for the accurate calculation of the true CFR during a pandemic,instead of waiting until the end of the pandemic,whether the pandemic is under control or not.It could provide those involved in outbreak control a clear view of the timeliness of case confirmations.
