Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is fe...Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions, which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices. Here, we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions. Three mechanisms were found to be capable of lowering the relative energy of the O-phase, namely, more significant surface-bulk portion of(111) surfaces, compressive c-axis strain,and positive electric fields. Considering these mechanisms, we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial, respectively. These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm, ascribed to its lower surface energies. All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.展开更多
Phase engineering is an efficient strategy for enhancing the kinetics of electrocatalytic reactions.Herein,phase engineering was employed to prepare high‐performance phosphorous‐doped biphase(1T/2H)MoS_(2)(P‐BMS)na...Phase engineering is an efficient strategy for enhancing the kinetics of electrocatalytic reactions.Herein,phase engineering was employed to prepare high‐performance phosphorous‐doped biphase(1T/2H)MoS_(2)(P‐BMS)nanoflakes for hydrogen evolution reaction(HER).The doping of MoS_(2)with P atoms modifies its electronic structure and optimizes its electrocatalytic reaction kinetics,which significantly enhances its electrical conductivity and structural stability,which are verified by various characterization tools,including X‐ray photoelectron spectroscopy,high‐resolution transmission electron microscopy,X‐ray absorption near‐edge spectroscopy,and extended X‐ray absorption fine structure.Moreover,the hierarchically formed flakes of P‐BMS provide numerous catalytic surface‐active sites,which remarkably enhance its HER activity.The optimized P‐BMS electrocatalysts exhibit low overpotentials(60 and 72 mV at 10 mA cm^(−2))in H_(2)SO_(4)(0.5 M)and KOH(1.0 M),respectively.The mechanism of improving the HER activity of the material was systematically studied using density functional theory calculations and various electrochemical characterization techniques.This study has shown that phase engineering is a promising strategy for enhancing the H*adsorption of metal sulfides.展开更多
目的探讨环状RNA ACAP2(circACAP2)调节微小RNA(miR)-421/B细胞易位基因2(BTG2)轴对心肌梗死(MI)大鼠心肌损伤的影响。方法构建MI大鼠模型和H9c2细胞模型,将80只大鼠分为假手术组、MI组、小干扰RNA-阴性对照(si-NC)组、si-circACAP2组、...目的探讨环状RNA ACAP2(circACAP2)调节微小RNA(miR)-421/B细胞易位基因2(BTG2)轴对心肌梗死(MI)大鼠心肌损伤的影响。方法构建MI大鼠模型和H9c2细胞模型,将80只大鼠分为假手术组、MI组、小干扰RNA-阴性对照(si-NC)组、si-circACAP2组、pcDNA3.1组、pcDNA3.1-circACAP2组、pcDNA3.1-circACAP2+模拟物(mimic)NC组、pcDNA3.1-circACAP2+miR-421 mimic组,每组各10只。将缺氧H9c2细胞置于24孔板中,瞬时转染细胞,分为缺氧组、缺氧+si-NC组、缺氧+si-circACAP2组、缺氧+pcDNA3.1组、缺氧+pcDNA3.1-circACAP2组、缺氧+pcDNA3.1-circACAP2+mimic NC组、缺氧+pcDNA3.1-circACAP2+miR-421 mimic组,另取正常培养的H9c2细胞作为对照组。检测大鼠左心室射血分数(LVEF)、左心室短轴缩短率(LVFS)、心肌梗死情况、心肌组织病理变化、circACAP2、miR-421、BTG2 mRNA表达情况、乳酸脱氢酶(LDH)、肌酸激酶同工酶(CK-MB)活性、H9c2细胞活力和凋亡、心肌组织BTG2蛋白表达、H9c2细胞BTG2蛋白表达。结果MI组circACAP2、BTG2 mRNA表达高于假手术组(1.84±0.21 vs 1.00±0.10,1.68±0.17 vs 1.00±0.10),miR-421表达低于假手术组(0.49±0.05 vs 1.00±0.11,P<0.05);与假手术组比较,MI组梗死面积、CK-MB、LDH活性升高,LVFS、LVEF降低(P<0.05)。与si-NC组比较,si-circACAP2组心肌损伤减轻,LVFS、LVEF升高,梗死面积、CK-MB、LDH活性降低(P<0.05);与缺氧+si-NC组比较,缺氧+si-circACAP2组细胞活力升高,凋亡率、CK-MB和LDH活性降低(P<0.05)。与pcDNA3.1组比较,pcDNA3.1-circACAP2组心肌损伤加重,LVFS、LVEF降低,梗死面积、CK-MB、LDH活性升高(P<0.05);与缺氧+pcDNA3.1组比较,缺氧+pcDNA3.1-circACAP2组细胞活力降低,凋亡率、CK-MB、LDH活性升高(P<0.05)。结论circACAP2在MI大鼠和H9c2细胞中表达上调,沉默circACAP2可能通过调节miR-421/BTG2轴改善心脏功能,减少心肌损伤,提高心肌细胞活力。展开更多
基金Project supported by the Fund from the Ministry of Science and Technology(MOST)of China(Grant No.2018YFE0202700)the National Natural Science Foundation of China(Grant Nos.11974422 and 12104504)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.22XNKJ30)。
文摘Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions, which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices. Here, we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions. Three mechanisms were found to be capable of lowering the relative energy of the O-phase, namely, more significant surface-bulk portion of(111) surfaces, compressive c-axis strain,and positive electric fields. Considering these mechanisms, we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial, respectively. These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm, ascribed to its lower surface energies. All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.
基金National Natural Science Foundation of China,Grant/Award Number:NSFC‐U1904215National Research Foundation of Korea,Grant/Award Number:2021R1A2C2012127。
文摘Phase engineering is an efficient strategy for enhancing the kinetics of electrocatalytic reactions.Herein,phase engineering was employed to prepare high‐performance phosphorous‐doped biphase(1T/2H)MoS_(2)(P‐BMS)nanoflakes for hydrogen evolution reaction(HER).The doping of MoS_(2)with P atoms modifies its electronic structure and optimizes its electrocatalytic reaction kinetics,which significantly enhances its electrical conductivity and structural stability,which are verified by various characterization tools,including X‐ray photoelectron spectroscopy,high‐resolution transmission electron microscopy,X‐ray absorption near‐edge spectroscopy,and extended X‐ray absorption fine structure.Moreover,the hierarchically formed flakes of P‐BMS provide numerous catalytic surface‐active sites,which remarkably enhance its HER activity.The optimized P‐BMS electrocatalysts exhibit low overpotentials(60 and 72 mV at 10 mA cm^(−2))in H_(2)SO_(4)(0.5 M)and KOH(1.0 M),respectively.The mechanism of improving the HER activity of the material was systematically studied using density functional theory calculations and various electrochemical characterization techniques.This study has shown that phase engineering is a promising strategy for enhancing the H*adsorption of metal sulfides.
文摘目的探讨环状RNA ACAP2(circACAP2)调节微小RNA(miR)-421/B细胞易位基因2(BTG2)轴对心肌梗死(MI)大鼠心肌损伤的影响。方法构建MI大鼠模型和H9c2细胞模型,将80只大鼠分为假手术组、MI组、小干扰RNA-阴性对照(si-NC)组、si-circACAP2组、pcDNA3.1组、pcDNA3.1-circACAP2组、pcDNA3.1-circACAP2+模拟物(mimic)NC组、pcDNA3.1-circACAP2+miR-421 mimic组,每组各10只。将缺氧H9c2细胞置于24孔板中,瞬时转染细胞,分为缺氧组、缺氧+si-NC组、缺氧+si-circACAP2组、缺氧+pcDNA3.1组、缺氧+pcDNA3.1-circACAP2组、缺氧+pcDNA3.1-circACAP2+mimic NC组、缺氧+pcDNA3.1-circACAP2+miR-421 mimic组,另取正常培养的H9c2细胞作为对照组。检测大鼠左心室射血分数(LVEF)、左心室短轴缩短率(LVFS)、心肌梗死情况、心肌组织病理变化、circACAP2、miR-421、BTG2 mRNA表达情况、乳酸脱氢酶(LDH)、肌酸激酶同工酶(CK-MB)活性、H9c2细胞活力和凋亡、心肌组织BTG2蛋白表达、H9c2细胞BTG2蛋白表达。结果MI组circACAP2、BTG2 mRNA表达高于假手术组(1.84±0.21 vs 1.00±0.10,1.68±0.17 vs 1.00±0.10),miR-421表达低于假手术组(0.49±0.05 vs 1.00±0.11,P<0.05);与假手术组比较,MI组梗死面积、CK-MB、LDH活性升高,LVFS、LVEF降低(P<0.05)。与si-NC组比较,si-circACAP2组心肌损伤减轻,LVFS、LVEF升高,梗死面积、CK-MB、LDH活性降低(P<0.05);与缺氧+si-NC组比较,缺氧+si-circACAP2组细胞活力升高,凋亡率、CK-MB和LDH活性降低(P<0.05)。与pcDNA3.1组比较,pcDNA3.1-circACAP2组心肌损伤加重,LVFS、LVEF降低,梗死面积、CK-MB、LDH活性升高(P<0.05);与缺氧+pcDNA3.1组比较,缺氧+pcDNA3.1-circACAP2组细胞活力降低,凋亡率、CK-MB、LDH活性升高(P<0.05)。结论circACAP2在MI大鼠和H9c2细胞中表达上调,沉默circACAP2可能通过调节miR-421/BTG2轴改善心脏功能,减少心肌损伤,提高心肌细胞活力。
