Both sustainable development in environment and safety of high-power systems require to develop a novel lead-free dielectric capacitor with high energy density(Wrec)at low applied electric field.In this work,a remarka...Both sustainable development in environment and safety of high-power systems require to develop a novel lead-free dielectric capacitor with high energy density(Wrec)at low applied electric field.In this work,a remarkably high Wrec of 2.9 J/cm^(3) accompanying with energy storage efficiency of 56% was achieved in Ag_(0.9)Sr_(0.05)NbO_(3) ceramic at a low applied electric field of 190 kV/cm,by improving antiferroelectricity and introducing relaxor behaviour.The improved anti-ferroelectric stability was attributed to the decreased tolerance factor and average electronegativity difference,while the relaxor behaviour was associated with the increased disordered local structure by Sr-doping.Moreover,the Ag_(0.9)Sr_(0.05)NbO_(3) ceramics also exhibited outstanding temperature stability in energy density with small variation less than 5% over 20-140℃.The results indicate that the Ag_(0.9)Sr_(0.05)NbO_(3) ceramic is a promising candidate for low-electric-field driving capacitors.展开更多
The NaNbO_(3) antiferroelectrics have been considered as a potential candidate for dielectric capacitorsapplications. However, the high-electric-field-unstable antiferroelectric phase resulted in low energystorage den...The NaNbO_(3) antiferroelectrics have been considered as a potential candidate for dielectric capacitorsapplications. However, the high-electric-field-unstable antiferroelectric phase resulted in low energystorage density and efficiency. Herein, good energy storage properties were realized in (1-x)NaNbO_(3)- xNaTaO_(3) ceramics, by building a new phase boundary. As a result, a high recoverable energy density(Wrec) of 2.2 J/cm3 and efficiency (h) of 80.1% were achieved in 0.50NaNbO_(3)-0.50NaTaO_(3) ceramic at300 kV/cm. The excellent energy storage performance originates from an antiferroelectric-paraelectricphase boundary with simultaneously high polarization and low hysteresis, by tailoring the ratio ofantiferroelectric and paraelectric phases. Moreover, the 0.50NaNbO_(3)-0.50NaTaO_(3) ceramic also exhibitedgood temperature and frequency stability, together with excellent charge-discharge performance. Theresults pave a good way of designing new NaNbO_(3)-based antiferroelectrics with good energy storageperformance.展开更多
The immune responses and the function of immune cells among asymptomatic severe acute respiratory syndrome coronavirus 2(SARS‐CoV‐2)infection cases,especially in immuno‐compromised individuals,remain largely unknow...The immune responses and the function of immune cells among asymptomatic severe acute respiratory syndrome coronavirus 2(SARS‐CoV‐2)infection cases,especially in immuno‐compromised individuals,remain largely unknown.Here we present a case of asymptomatic SARS‐CoV‐2 infection that lasted for at least 67 days.The patient has administrated Thymalfasin as 1.6 mg per dose every other day from Day 45 to 70,plus 200 mg per dose Arbidol antiviral therapy three doses per day from Day 48 to 57.Throughout the infection,no anti‐SARS‐CoV‐2 specific IgM or IgG antibodies were detected.Instead,the patient showed either a low percentage or an absolute number of non‐classical monocytes,dendritic cells(DCs),CD4^(+)T cells,and regulatory T cells(Tregs),which may account for the clinical feature and absence of antibody response.This case may shed new light on the outbreak management related to control/prevention,treatment,and vaccination of SARS‐CoV‐2 and other virus infections in immunocompromised individuals.展开更多
基金supported by National Natural Science Foundation of China(Grants 11864004)Guangxi Natural Science Foundation(Grants 2017GXNSFBA198132,2016GXNSFAA380214,2016GXNSFCB380006 and 2017GXNSFFA198015)+2 种基金Science and Technology Major Project of Guangxi,(Grant AA17204100)Innovation Project of Guangxi Graduate Education(Grant YCSW2019053)the funds of the State Key Laboratory of New Ceramics and Fine Processing,Tsinghua University,Beijing(100084),China.
文摘Both sustainable development in environment and safety of high-power systems require to develop a novel lead-free dielectric capacitor with high energy density(Wrec)at low applied electric field.In this work,a remarkably high Wrec of 2.9 J/cm^(3) accompanying with energy storage efficiency of 56% was achieved in Ag_(0.9)Sr_(0.05)NbO_(3) ceramic at a low applied electric field of 190 kV/cm,by improving antiferroelectricity and introducing relaxor behaviour.The improved anti-ferroelectric stability was attributed to the decreased tolerance factor and average electronegativity difference,while the relaxor behaviour was associated with the increased disordered local structure by Sr-doping.Moreover,the Ag_(0.9)Sr_(0.05)NbO_(3) ceramics also exhibited outstanding temperature stability in energy density with small variation less than 5% over 20-140℃.The results indicate that the Ag_(0.9)Sr_(0.05)NbO_(3) ceramic is a promising candidate for low-electric-field driving capacitors.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.11864004 and 52072080)The author also thanks to the fund(Grant No.20KF-16)from the Key Laboratory of New Processing Technology for Nonferrous Metal&Materials,Ministry of Education/Guangxi Key Laboratory of Optical and Electronic Materials and Devices,Guilin University of Technology,Guilin(541004),China.
文摘The NaNbO_(3) antiferroelectrics have been considered as a potential candidate for dielectric capacitorsapplications. However, the high-electric-field-unstable antiferroelectric phase resulted in low energystorage density and efficiency. Herein, good energy storage properties were realized in (1-x)NaNbO_(3)- xNaTaO_(3) ceramics, by building a new phase boundary. As a result, a high recoverable energy density(Wrec) of 2.2 J/cm3 and efficiency (h) of 80.1% were achieved in 0.50NaNbO_(3)-0.50NaTaO_(3) ceramic at300 kV/cm. The excellent energy storage performance originates from an antiferroelectric-paraelectricphase boundary with simultaneously high polarization and low hysteresis, by tailoring the ratio ofantiferroelectric and paraelectric phases. Moreover, the 0.50NaNbO_(3)-0.50NaTaO_(3) ceramic also exhibitedgood temperature and frequency stability, together with excellent charge-discharge performance. Theresults pave a good way of designing new NaNbO_(3)-based antiferroelectrics with good energy storageperformance.
基金funded by Natural Science Foundation of Hebei Province granted to XC(no.H2020206352)Novel Coronavirus Project to GH by Jiangmen Science and Technology Bureau(2020020500410003915)Guangzhou Emergency Response Plan to D.L(EKPG21-27)。
文摘The immune responses and the function of immune cells among asymptomatic severe acute respiratory syndrome coronavirus 2(SARS‐CoV‐2)infection cases,especially in immuno‐compromised individuals,remain largely unknown.Here we present a case of asymptomatic SARS‐CoV‐2 infection that lasted for at least 67 days.The patient has administrated Thymalfasin as 1.6 mg per dose every other day from Day 45 to 70,plus 200 mg per dose Arbidol antiviral therapy three doses per day from Day 48 to 57.Throughout the infection,no anti‐SARS‐CoV‐2 specific IgM or IgG antibodies were detected.Instead,the patient showed either a low percentage or an absolute number of non‐classical monocytes,dendritic cells(DCs),CD4^(+)T cells,and regulatory T cells(Tregs),which may account for the clinical feature and absence of antibody response.This case may shed new light on the outbreak management related to control/prevention,treatment,and vaccination of SARS‐CoV‐2 and other virus infections in immunocompromised individuals.