Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor trans...Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor transport(CVT).With the increase of growth time,the dislocation densities in the crystal decreased from about 1×10^(6) to 6×10^(3) cm^(-2).The carrier concentration decreased from 1.24×10^(19) to 1.57×10^(17)cm^(-3),while the carrier mobility increased from 63.8 to 179 cm^(2)/(V·s).The optical transmittance in the VIS-NIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations.The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage,and the crystal qualities were consequently improved.The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent.The GaN/Al_(2)O_(3) seeds may have a potential application value in the industrial production of ZnO single crystals.展开更多
Porous Pt thin films were prepared on carbon papers by a single-step ultra-high dc magnetron sputtering method to obtain ideal electrodes for proton exchange membrane fuel cells.The platinum loading of the electrocata...Porous Pt thin films were prepared on carbon papers by a single-step ultra-high dc magnetron sputtering method to obtain ideal electrodes for proton exchange membrane fuel cells.The platinum loading of the electrocatalyst layer is controlled at about 0.1 mg·cm^(-2).Structural characteristics and catalytic activities of the films were analyzed by scanning electron microscopy,atomic force microscopy,X-ray diffraction,cyclic voltammetry,and stress durability testing methods.The effect of treatment conditions of a substrate on the structural and performance characteristics of the catalytic films was shown as well.Films produced on acid-treated carbon papers at the argon pressure of 0.01 mbar possessed a homogeneous,highly developed surface along with a porous structure.Compared to Pt/TCPW(Toray carbon papers soaked in ultrapure water)electrodes,the film obtained on the acid-treated substrate had a larger electrochemical surface area(163.33 m^(2)·g^(-1))and exhibited better catalytic stability and durability due to a porous structure as a result of Pt particle accumulation.展开更多
目的:探究维持性泼尼松与硫唑嘌呤片治疗视神经脊髓炎患者临床效果。方法:选取孝感市第一人民医院2019年7月-2020年7月纳入的80例视神经脊髓炎患者,随机分为对照组(n=40)和观察组(n=40),对照组采用硫唑嘌呤片治疗,观察组采用维持性泼尼...目的:探究维持性泼尼松与硫唑嘌呤片治疗视神经脊髓炎患者临床效果。方法:选取孝感市第一人民医院2019年7月-2020年7月纳入的80例视神经脊髓炎患者,随机分为对照组(n=40)和观察组(n=40),对照组采用硫唑嘌呤片治疗,观察组采用维持性泼尼松治疗。评估两组治疗前、治疗3、6、12个月后的扩展残疾状态量表(expanded disability status scale,EDSS)评分,以及视力状况、AQP4抗体阳性表达率、疗效满意度。结果:与治疗前相比,治疗3、6、12个月后两组EDSS评分逐渐降低,且观察组评分低于对照组(P<0.05);治疗3、6、12个月后观察组视力状况明显优于对照组(P<0.05);治疗6个月后,观察组AQP4抗体阳性表达率显著低于对照组(P<0.05);观察组疗效满意度显著高于对照组(P<0.05)。结论:维持性泼尼松治疗视神经脊髓炎患者能有效降EDSS评分,改善患者的视力状况,降低患者血清AQP4抗体阳性表达率,提高疗效满意度。展开更多
The nucleation process of graphene films prepared by pulsed laser deposition has been investigated in detail. It is found that graphene nucleates at the steps on the substrate surface firstly, from aggregation of nucl...The nucleation process of graphene films prepared by pulsed laser deposition has been investigated in detail. It is found that graphene nucleates at the steps on the substrate surface firstly, from aggregation of nuclei into particles. High pulsed laser energy offers large incident energy for carbon particles deposited on the surface of the substrate, which is beneficial to the nucleation of graphene. A lot of steps are formed on the copper substrate due to the high temperature, so that the high incident energetic carbon species are able to form a stable nucleus at the steps. As the incident particles increases, the graphene nuclei are combined to grow together. Further, it is found that graphene tends to form few layer graphene particles instead of large graphene sheets.展开更多
Magnetic nanoscale systems,including nanodots,nanofibers,nanowires and nanoparticles,are currently attracting great interest due to their interesting physical and promising applications in various fields,such as magne...Magnetic nanoscale systems,including nanodots,nanofibers,nanowires and nanoparticles,are currently attracting great interest due to their interesting physical and promising applications in various fields,such as magnetic recording,sensors,target drugs and catalysts,as well as others.To achieve ultrahigh recording density,the method of heat assisted magnetic recording(HAMR) has been introduced.In this work,with the help of a Monte Carlo method,the mechanisms of thermally assisted magnetization switching in FePt single-domain particles driven by an external magnetic field are investigated,where the temperature in the particles is assumed to follow a Gaussian distribution.Two nucleation modes are observed for different distributions of temperature.One is initiated by many droplets,which join each other at the boundary of the system;the other is ini-tiated by many droplets at the boundary,but in growth tending toward the inner part of the system.An inverse proportional relationship between the metastable lifetime and the distribution is also found.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.11905199,11904299,and U1930124)。
文摘Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor transport(CVT).With the increase of growth time,the dislocation densities in the crystal decreased from about 1×10^(6) to 6×10^(3) cm^(-2).The carrier concentration decreased from 1.24×10^(19) to 1.57×10^(17)cm^(-3),while the carrier mobility increased from 63.8 to 179 cm^(2)/(V·s).The optical transmittance in the VIS-NIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations.The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage,and the crystal qualities were consequently improved.The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent.The GaN/Al_(2)O_(3) seeds may have a potential application value in the industrial production of ZnO single crystals.
基金Funded by the Doctoral Fund of Southwest University of Science and Technology(Nos.19zx7131 and 18zx7132)the Applied Fundamental Research Projects of Science and Technology Department of Sichuan Province(No.2020YJ0333)+1 种基金the Science and Technology on Plasma Physics Laboratory:6142A04180405Science and Technology on Plasma Physics Laboratory:ZY2018-07。
文摘Porous Pt thin films were prepared on carbon papers by a single-step ultra-high dc magnetron sputtering method to obtain ideal electrodes for proton exchange membrane fuel cells.The platinum loading of the electrocatalyst layer is controlled at about 0.1 mg·cm^(-2).Structural characteristics and catalytic activities of the films were analyzed by scanning electron microscopy,atomic force microscopy,X-ray diffraction,cyclic voltammetry,and stress durability testing methods.The effect of treatment conditions of a substrate on the structural and performance characteristics of the catalytic films was shown as well.Films produced on acid-treated carbon papers at the argon pressure of 0.01 mbar possessed a homogeneous,highly developed surface along with a porous structure.Compared to Pt/TCPW(Toray carbon papers soaked in ultrapure water)electrodes,the film obtained on the acid-treated substrate had a larger electrochemical surface area(163.33 m^(2)·g^(-1))and exhibited better catalytic stability and durability due to a porous structure as a result of Pt particle accumulation.
文摘目的:探究维持性泼尼松与硫唑嘌呤片治疗视神经脊髓炎患者临床效果。方法:选取孝感市第一人民医院2019年7月-2020年7月纳入的80例视神经脊髓炎患者,随机分为对照组(n=40)和观察组(n=40),对照组采用硫唑嘌呤片治疗,观察组采用维持性泼尼松治疗。评估两组治疗前、治疗3、6、12个月后的扩展残疾状态量表(expanded disability status scale,EDSS)评分,以及视力状况、AQP4抗体阳性表达率、疗效满意度。结果:与治疗前相比,治疗3、6、12个月后两组EDSS评分逐渐降低,且观察组评分低于对照组(P<0.05);治疗3、6、12个月后观察组视力状况明显优于对照组(P<0.05);治疗6个月后,观察组AQP4抗体阳性表达率显著低于对照组(P<0.05);观察组疗效满意度显著高于对照组(P<0.05)。结论:维持性泼尼松治疗视神经脊髓炎患者能有效降EDSS评分,改善患者的视力状况,降低患者血清AQP4抗体阳性表达率,提高疗效满意度。
基金Funded by the National Natural Science Foundation of China(No.51521001)the“111”Project(No.B13035)
文摘The nucleation process of graphene films prepared by pulsed laser deposition has been investigated in detail. It is found that graphene nucleates at the steps on the substrate surface firstly, from aggregation of nuclei into particles. High pulsed laser energy offers large incident energy for carbon particles deposited on the surface of the substrate, which is beneficial to the nucleation of graphene. A lot of steps are formed on the copper substrate due to the high temperature, so that the high incident energetic carbon species are able to form a stable nucleus at the steps. As the incident particles increases, the graphene nuclei are combined to grow together. Further, it is found that graphene tends to form few layer graphene particles instead of large graphene sheets.
基金support by the Fund for Talents Introduction of Chongqing University of Arts and Sciences (Grant No. Z2011RCYJ03)
文摘Magnetic nanoscale systems,including nanodots,nanofibers,nanowires and nanoparticles,are currently attracting great interest due to their interesting physical and promising applications in various fields,such as magnetic recording,sensors,target drugs and catalysts,as well as others.To achieve ultrahigh recording density,the method of heat assisted magnetic recording(HAMR) has been introduced.In this work,with the help of a Monte Carlo method,the mechanisms of thermally assisted magnetization switching in FePt single-domain particles driven by an external magnetic field are investigated,where the temperature in the particles is assumed to follow a Gaussian distribution.Two nucleation modes are observed for different distributions of temperature.One is initiated by many droplets,which join each other at the boundary of the system;the other is ini-tiated by many droplets at the boundary,but in growth tending toward the inner part of the system.An inverse proportional relationship between the metastable lifetime and the distribution is also found.
