The morphology and structural stability of metal/2D semic on ductor interfaces strongly affect the performa nee of 2D electronic devices and synergistic catalysis. However, the structural evolution at the interfaces h...The morphology and structural stability of metal/2D semic on ductor interfaces strongly affect the performa nee of 2D electronic devices and synergistic catalysis. However, the structural evolution at the interfaces has not been well explored particularly at atomic resolution. In this work, we study the structural evoluti on of Au nan oparticles (NPs) on few-layer MoS2 by high resol utio n transmissi on electro n microscopy (HRTEM) an d quan titative high-angle annular dark field seanning TEM. It is found that in the transition of Au from nan oparticles to den drites, a dynamically epitaxial align ment betwee n Au and MoS2 lattices is formed, and Moirc patter ns can be directly observed in HRTEM images due to the mismatch between Au and M0S2 lattices. This epitaxial alignment can occur in ambient conditions, and can also be accelerated by the irradiation of high-energy electron beam. In situ observation clearly reveals the rotation of Au NPs, the atom migration inside Au NPs, and the transfer of Au atoms between neighboring Au NPs, finally leading to the formation of epitaxially aligned Au dendrites on M0S2. The structural evoluti on of metal/2D semico nductor in terfaces at atomic scale can provide valuable information for the design and fabricatio n of the metal/2D semicon ductorn ano-devices with desired physical and chemical performa nces.展开更多
Developing non-precious metal catalysts with high activity and stability for electrochemical hydrogen evolution reaction(HER)is of great significance in both scie nee and tech no logy.In this work,N-doped CMK-3,which ...Developing non-precious metal catalysts with high activity and stability for electrochemical hydrogen evolution reaction(HER)is of great significance in both scie nee and tech no logy.In this work,N-doped CMK-3,which was prepared with a casting method using SBA-15 as thehard template and ammonia as the nitrogen source,has been utilized to hold MoS2 and restrict its growth to form MoS2@N-CMK-3 composite.As a result,M0S2 was found to have poorly crystallized and the limited space of porous N-CMK-3 made its size much small.Then there are moreactive sites in MoS2.Accordingly,MoS2@N-CMK-3 has exhibited good electrocatalytic performance toward HER in acids with a quite small Tafelslope of 32 mV·dec^-1.And more importantly,compared to MoS2@CMK-3,its stability has been greatly improved,which can be attributedto the interaction between M0S2 and nitrogen atoms avoiding aggregation and mass loss.This work provides an idea that doping a porouscarbon support with nitrogen is an effective way to enhance the stability of the catalyst.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDs)such as molybdenum disulfide(M0S2)have been intensively investigated because of their exclusive physical properties for advaneed electronics and optoelectronics...Two-dimensional(2D)transition metal dichalcogenides(TMDs)such as molybdenum disulfide(M0S2)have been intensively investigated because of their exclusive physical properties for advaneed electronics and optoelectronics.In the present work,we study the M0S2 transistor based on a novel tri-gate device architecture,with dual-gate(Dual-G)in the channel and the buried side-gate(Side-G)for the source/drain regi ons.All gates can be in depe ndently con trolled without in terfere nee.For a MoS2 sheet with a thick ness of 3.6 nm,the Schottky barrier(SB)and non-overlapped channel region can be effectively tuned by electrostatically doping the source/drain regions with Side-G.Thus,the extri nsic resista nee can be effectively lowered,and a boost of the ON-state cur re nt can be achieved.Mean while,the cha nn el c ontrol remai ns efficient under the Dual-G mode,with an ON-OFF current ratio of 3 x 107 and subthreshold swing of 83 mV/decade.The corresponding band diagram is also discussed to illustrate the device operati on mechanism.This no vel device structure ope ns up a new way toward fabricati on of high-performance devices based on 2D-TMDs.展开更多
介绍一种主要为室内定位提供测距基础的系统。该系统由两个对等的节点组成,节点1发送通过无线发出的同步握手信号,节点2收到同步信号后开始计时并回应握手信号,节点1确认握手成功后开始发送声波脉冲信号,节点2收到脉冲信号后停止计时,...介绍一种主要为室内定位提供测距基础的系统。该系统由两个对等的节点组成,节点1发送通过无线发出的同步握手信号,节点2收到同步信号后开始计时并回应握手信号,节点1确认握手成功后开始发送声波脉冲信号,节点2收到脉冲信号后停止计时,定时器的时间就是声波在空气中的传播时间,进而确定点和点之间的距离。节点主要是由声波发射接收电路、CC1100无线电模块和STC12C5A0S2单片机等组成。STC12C5A0S2内部带有捕获定时器的功能,能准确地抓住定时器的值。声波发射接收电路主要由NE555,LM386和NE5532构成,能高频喇叭发送和接收10.25 k Hz声波信号。系统在测试的过程中,随着距离的增大,误差会有所加大,在10 m范围内误差小于10%,可以满足定位测距的需求。在实际的应用过程中还可以通过系统标定等数据处理手段,进一步提高测量精度,满足更高的测距要求。展开更多
目的探讨SOX2基因对人骨关节炎(OA)软骨细胞凋亡的影响及机制。方法以正常软骨组织作为对照,通过Western blotting检测OA软骨组织SOX2蛋白表达。从人OA中分离软骨细胞,参照Lipofectamine^(TM)2000说明将重组体pcDNA3.1-SOX2及空载体pcDN...目的探讨SOX2基因对人骨关节炎(OA)软骨细胞凋亡的影响及机制。方法以正常软骨组织作为对照,通过Western blotting检测OA软骨组织SOX2蛋白表达。从人OA中分离软骨细胞,参照Lipofectamine^(TM)2000说明将重组体pcDNA3.1-SOX2及空载体pcDNA3.1转染软骨细胞,并设置空白对照组。AG490作为JAK2/STAT3信号通路抑制剂,各组细胞处理48 h,通过流式细胞术、ROS试剂盒分别检测各组细胞凋亡率及ROS水平。Western blotting检测JAK2、p-JAK2、STAT3和p-STAT3的蛋白相对表达量。结果人OA软骨组织SOX2表达明显低于在正常软骨组织表达(0.065±0.009 vs 0.313±0.028,P<0.05)。转染pcDNA3.1-SOX2的OA软骨细胞SOX2表达明显高于空白组(0.556±0.048 vs 0.122±0.013,P<0.05)。pcDNA3.1-SOX2可明显降低OA软骨细胞凋亡率(3.11±0.42 vs 8.54±0.68)及ROS水平(23.46±2.15 vs 52.67±4.41),上调p-JAK2(0.142±0.013 vs 0.065±0.009)和p-STAT3表达(0.218±0.020 vs 0.126±0.015)(P<0.05),AG490(15.23±1.13 vs 8.15±0.62)可诱导OA软骨细胞凋亡,而pcDNA3.1-SOX2可减弱AG490对OA软骨细胞凋亡促进作用(P<0.05)。结论SOX2可抑制OA软骨细胞凋亡,其机制可能与激活JAK2/STAT3信号通路有关。展开更多
As the major source of air pollution,sulfur dioxide(S0_(2))emissions have become the focus of global attention.However,existing studies rarely consider spatial effects when discussing the relationship between foreign ...As the major source of air pollution,sulfur dioxide(S0_(2))emissions have become the focus of global attention.However,existing studies rarely consider spatial effects when discussing the relationship between foreign direct investment(FDI)and S0_(2) emissions.This study took the Yangtze River Delta as the research area and used the spatial panel data of 26 cities in this region for 2004-2017.The study investigated the spatial agglomeration effects and dynamics at work in FDI and S0_(2) emissions by using global and local measures of spatial autocorrelation.Then,based on regression analysis using a results of traditional ordinary least squares(OLS)model and a spatial econometric model,the spatial Durbin model(SDM)with spatial-time effects was adopted to quantify the impact of FDI on S0_(2) emissions,so as to avoid the regression results bias caused by ignoring the spatial effects.The results revealed a significant spatial autocorrelation between FDI and S0_(2) emissions,both of which displayed obvious path dependence characteristics in their geographical distribution.A series of agglomeration regions were observed on the spatial scale.The estimation results of the SDM showed that FDI inflow promoted S0_(2) emissions,which supports the pollution haven hypothesis.The findings of this study are significant in the prevention and control of air pollution in the Yangtze River Delta.展开更多
基金National Natural Science Foundation of China (Nos. 11604010 and 11674023), 111 Project (No. B170003)Fundamental Research Funds for the Central Universities (No. FRF-BD- 18-004A).
文摘The morphology and structural stability of metal/2D semic on ductor interfaces strongly affect the performa nee of 2D electronic devices and synergistic catalysis. However, the structural evolution at the interfaces has not been well explored particularly at atomic resolution. In this work, we study the structural evoluti on of Au nan oparticles (NPs) on few-layer MoS2 by high resol utio n transmissi on electro n microscopy (HRTEM) an d quan titative high-angle annular dark field seanning TEM. It is found that in the transition of Au from nan oparticles to den drites, a dynamically epitaxial align ment betwee n Au and MoS2 lattices is formed, and Moirc patter ns can be directly observed in HRTEM images due to the mismatch between Au and M0S2 lattices. This epitaxial alignment can occur in ambient conditions, and can also be accelerated by the irradiation of high-energy electron beam. In situ observation clearly reveals the rotation of Au NPs, the atom migration inside Au NPs, and the transfer of Au atoms between neighboring Au NPs, finally leading to the formation of epitaxially aligned Au dendrites on M0S2. The structural evoluti on of metal/2D semico nductor in terfaces at atomic scale can provide valuable information for the design and fabricatio n of the metal/2D semicon ductorn ano-devices with desired physical and chemical performa nces.
基金This work was supported by the Nature Science Foundation of Zhejiang Province(No.LY20B010004)and the National Natural Science Foundation of China(Nos.21671152,51672193,51420105002, 21671014).
文摘Developing non-precious metal catalysts with high activity and stability for electrochemical hydrogen evolution reaction(HER)is of great significance in both scie nee and tech no logy.In this work,N-doped CMK-3,which was prepared with a casting method using SBA-15 as thehard template and ammonia as the nitrogen source,has been utilized to hold MoS2 and restrict its growth to form MoS2@N-CMK-3 composite.As a result,M0S2 was found to have poorly crystallized and the limited space of porous N-CMK-3 made its size much small.Then there are moreactive sites in MoS2.Accordingly,MoS2@N-CMK-3 has exhibited good electrocatalytic performance toward HER in acids with a quite small Tafelslope of 32 mV·dec^-1.And more importantly,compared to MoS2@CMK-3,its stability has been greatly improved,which can be attributedto the interaction between M0S2 and nitrogen atoms avoiding aggregation and mass loss.This work provides an idea that doping a porouscarbon support with nitrogen is an effective way to enhance the stability of the catalyst.
基金This work was supported by the National Key Research and Development Program of China(Nos.2016YFA0203900 and 2018YFA0306101)Shanghai Municipal Science and Technology Commission(No.18JC1410300)Natural Science Foundation of China(No.61874154).
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs)such as molybdenum disulfide(M0S2)have been intensively investigated because of their exclusive physical properties for advaneed electronics and optoelectronics.In the present work,we study the M0S2 transistor based on a novel tri-gate device architecture,with dual-gate(Dual-G)in the channel and the buried side-gate(Side-G)for the source/drain regi ons.All gates can be in depe ndently con trolled without in terfere nee.For a MoS2 sheet with a thick ness of 3.6 nm,the Schottky barrier(SB)and non-overlapped channel region can be effectively tuned by electrostatically doping the source/drain regions with Side-G.Thus,the extri nsic resista nee can be effectively lowered,and a boost of the ON-state cur re nt can be achieved.Mean while,the cha nn el c ontrol remai ns efficient under the Dual-G mode,with an ON-OFF current ratio of 3 x 107 and subthreshold swing of 83 mV/decade.The corresponding band diagram is also discussed to illustrate the device operati on mechanism.This no vel device structure ope ns up a new way toward fabricati on of high-performance devices based on 2D-TMDs.
文摘介绍一种主要为室内定位提供测距基础的系统。该系统由两个对等的节点组成,节点1发送通过无线发出的同步握手信号,节点2收到同步信号后开始计时并回应握手信号,节点1确认握手成功后开始发送声波脉冲信号,节点2收到脉冲信号后停止计时,定时器的时间就是声波在空气中的传播时间,进而确定点和点之间的距离。节点主要是由声波发射接收电路、CC1100无线电模块和STC12C5A0S2单片机等组成。STC12C5A0S2内部带有捕获定时器的功能,能准确地抓住定时器的值。声波发射接收电路主要由NE555,LM386和NE5532构成,能高频喇叭发送和接收10.25 k Hz声波信号。系统在测试的过程中,随着距离的增大,误差会有所加大,在10 m范围内误差小于10%,可以满足定位测距的需求。在实际的应用过程中还可以通过系统标定等数据处理手段,进一步提高测量精度,满足更高的测距要求。
文摘目的探讨SOX2基因对人骨关节炎(OA)软骨细胞凋亡的影响及机制。方法以正常软骨组织作为对照,通过Western blotting检测OA软骨组织SOX2蛋白表达。从人OA中分离软骨细胞,参照Lipofectamine^(TM)2000说明将重组体pcDNA3.1-SOX2及空载体pcDNA3.1转染软骨细胞,并设置空白对照组。AG490作为JAK2/STAT3信号通路抑制剂,各组细胞处理48 h,通过流式细胞术、ROS试剂盒分别检测各组细胞凋亡率及ROS水平。Western blotting检测JAK2、p-JAK2、STAT3和p-STAT3的蛋白相对表达量。结果人OA软骨组织SOX2表达明显低于在正常软骨组织表达(0.065±0.009 vs 0.313±0.028,P<0.05)。转染pcDNA3.1-SOX2的OA软骨细胞SOX2表达明显高于空白组(0.556±0.048 vs 0.122±0.013,P<0.05)。pcDNA3.1-SOX2可明显降低OA软骨细胞凋亡率(3.11±0.42 vs 8.54±0.68)及ROS水平(23.46±2.15 vs 52.67±4.41),上调p-JAK2(0.142±0.013 vs 0.065±0.009)和p-STAT3表达(0.218±0.020 vs 0.126±0.015)(P<0.05),AG490(15.23±1.13 vs 8.15±0.62)可诱导OA软骨细胞凋亡,而pcDNA3.1-SOX2可减弱AG490对OA软骨细胞凋亡促进作用(P<0.05)。结论SOX2可抑制OA软骨细胞凋亡,其机制可能与激活JAK2/STAT3信号通路有关。
基金Under the auspices of National Natural Science Foundation of China(No.41771140)National Key R&D Program of China(No.2018YFE0105900)。
文摘As the major source of air pollution,sulfur dioxide(S0_(2))emissions have become the focus of global attention.However,existing studies rarely consider spatial effects when discussing the relationship between foreign direct investment(FDI)and S0_(2) emissions.This study took the Yangtze River Delta as the research area and used the spatial panel data of 26 cities in this region for 2004-2017.The study investigated the spatial agglomeration effects and dynamics at work in FDI and S0_(2) emissions by using global and local measures of spatial autocorrelation.Then,based on regression analysis using a results of traditional ordinary least squares(OLS)model and a spatial econometric model,the spatial Durbin model(SDM)with spatial-time effects was adopted to quantify the impact of FDI on S0_(2) emissions,so as to avoid the regression results bias caused by ignoring the spatial effects.The results revealed a significant spatial autocorrelation between FDI and S0_(2) emissions,both of which displayed obvious path dependence characteristics in their geographical distribution.A series of agglomeration regions were observed on the spatial scale.The estimation results of the SDM showed that FDI inflow promoted S0_(2) emissions,which supports the pollution haven hypothesis.The findings of this study are significant in the prevention and control of air pollution in the Yangtze River Delta.
