Designing simplistic,efficient,durable,and highly eco-friendly electrocatalysts toward the hydrogen evolution reaction is essential for large-scale and economical practical applications.In this work,the as-fabricated ...Designing simplistic,efficient,durable,and highly eco-friendly electrocatalysts toward the hydrogen evolution reaction is essential for large-scale and economical practical applications.In this work,the as-fabricated CoFe_(2)O_(4)@boron-doped carbon(CoFe_(2)O_(4)@BC)nanoflowers consisted of nanosheets with a porous structure and plenty of enriched catalytic sites.The remarkable electrocatalytic activity of the asfabricated nanomaterial offers a worthwhile approach to improve the performance and stability of transition metal-boride electrocatalysts.Therefore,the as-synthesized CoFe_(2)O_(4)@BC 500℃ electrocatalyst displays a low geometrical overpotential of 58 mV at 10 mA cm^(-2)for the HER with a small Tafel slope of 50 mV dec^(-1) and long-term stability of 100 h in 1.0 M KOH solution.Ultimately,the outstanding CoFe_(2)O_(4)@BC 500℃ nanoflower displays significantly enhanced HER activity,which could be mainly attributed to the following factors:(i)unique flower-like nanoarchitecture fabrication,(ii)the exposure of plentiful active sites in the architecture of the CoFe_(2)O_(4)@BC 500℃ nanoflowers,(iii)electrical conductivity of the catalyst driven by the doping of boron,(iv)numerous defects in the porous structures of the nanoflowers and abundant electron delocalization,and(v)the synergistic co-existence of Co and Fe metals and boron,which promotes the electrochemical performance.Therefore,this work provides a unique strategic plan for the design of efficient and stable B-doped electrocatalysts in an alkaline solution.展开更多
A VME-based experiment system for n-y discrimination using the charge comparison method was established.A data acquisition program for controlling the programmable modules and processing data online via VME64X bus was...A VME-based experiment system for n-y discrimination using the charge comparison method was established.A data acquisition program for controlling the programmable modules and processing data online via VME64X bus was developed through the use of Lab VIEW.The two-dimensional（2D） scatter plots of the charge in the slow component vs.the total charge from ^（241）Am-Be and 252Cf neutron sources are presented.The 2D scatter plots of the energy vs.the ratio of the charge in the slow component to the total charge of the pulses are also presented.The quality of n-γ discrimination was checked by the figure-of-merit,and the results showed good performance of n-γ discrimination at the low energy range.Neutrons and γ-rays were separated above 50 keVee（electron-equivalent energy）.The quality of n-γ discrimination has been improved compared with others＇ results at five energies（150,250,350,450,550 keVee）.展开更多
In this paper a feasibility study of the Bc meson to measure its mass and lifetime is described with the general purpose detector at the LHC. The study solely concentrated on the J/ψn^＋, J/ψ→μ^＋μ^- decay channe...In this paper a feasibility study of the Bc meson to measure its mass and lifetime is described with the general purpose detector at the LHC. The study solely concentrated on the J/ψn^＋, J/ψ→μ^＋μ^- decay channel of the Bc and it was concluded that about 120 events can be selected in the first fb^-1 of data. With this data sample, the mass resolution was estimated to be 2.0（stat.） MeV/c^2 while the cτ resolution was found to be 13.1（stat.） p.m, i.e. the lifetime resolution to be 0.044（stat.） ps.展开更多
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.展开更多
Based on the surface passivation of n-type silicon in a silicon drift detector(SDD), we propose a new passivation structure of SiO2/Al2O3/SiO2 passivation stacks. Since the SiO2 formed by the nitric-acid-oxidation-of-...Based on the surface passivation of n-type silicon in a silicon drift detector(SDD), we propose a new passivation structure of SiO2/Al2O3/SiO2 passivation stacks. Since the SiO2 formed by the nitric-acid-oxidation-of-silicon(NAOS)method has good compactness and simple process, the first layer film is formed by the NAOS method. The Al2O3 film is also introduced into the passivation stacks owing to exceptional advantages such as good interface characteristic and simple process. In addition, for requirements of thickness and deposition temperature, the third layer of the SiO2 film is deposited by plasma enhanced chemical vapor deposition(PECVD). The deposition of the SiO2 film by PECVD is a low-temperature process and has a high deposition rate, which causes little damage to the device and makes the SiO2 film very suitable for serving as the third passivation layer. The passivation approach of stacks can saturate dangling bonds at the interface between stacks and the silicon substrate, and provide positive charge to optimize the field passivation of the n-type substrate.The passivation method ultimately achieves a good combination of chemical and field passivations. Experimental results show that with the passivation structure of SiO2/Al2O3/SiO2, the final minority carrier lifetime reaches 5223 μs at injection of 5×10^(15) cm^(-3). When it is applied to the passivation of SDD, the leakage current is reduced to the order of nA.展开更多
采用金属有机化学气相沉积(MOCVD)方法在Si衬底上实现了立方结构的Mg0.25Zn0.75O薄膜生长。在此基础上,实现了Mg0.25Zn0.75O/n-Si异质结型日盲紫外探测器。该探测器在-5 V偏压下,器件暗电流为0.02 m A。在0 V偏压下的峰值响应位于大约28...采用金属有机化学气相沉积(MOCVD)方法在Si衬底上实现了立方结构的Mg0.25Zn0.75O薄膜生长。在此基础上,实现了Mg0.25Zn0.75O/n-Si异质结型日盲紫外探测器。该探测器在-5 V偏压下,器件暗电流为0.02 m A。在0 V偏压下的峰值响应位于大约280 nm处,响应度为1.2 m A/W。展开更多
基金the National Natural Science Foundation(21676129)the Science&Technology Foundation of Zhenjiang(GY2016021,GY2017001 and YE201709)supported by the High Performance Computing Platform of Jiangsu University.
文摘Designing simplistic,efficient,durable,and highly eco-friendly electrocatalysts toward the hydrogen evolution reaction is essential for large-scale and economical practical applications.In this work,the as-fabricated CoFe_(2)O_(4)@boron-doped carbon(CoFe_(2)O_(4)@BC)nanoflowers consisted of nanosheets with a porous structure and plenty of enriched catalytic sites.The remarkable electrocatalytic activity of the asfabricated nanomaterial offers a worthwhile approach to improve the performance and stability of transition metal-boride electrocatalysts.Therefore,the as-synthesized CoFe_(2)O_(4)@BC 500℃ electrocatalyst displays a low geometrical overpotential of 58 mV at 10 mA cm^(-2)for the HER with a small Tafel slope of 50 mV dec^(-1) and long-term stability of 100 h in 1.0 M KOH solution.Ultimately,the outstanding CoFe_(2)O_(4)@BC 500℃ nanoflower displays significantly enhanced HER activity,which could be mainly attributed to the following factors:(i)unique flower-like nanoarchitecture fabrication,(ii)the exposure of plentiful active sites in the architecture of the CoFe_(2)O_(4)@BC 500℃ nanoflowers,(iii)electrical conductivity of the catalyst driven by the doping of boron,(iv)numerous defects in the porous structures of the nanoflowers and abundant electron delocalization,and(v)the synergistic co-existence of Co and Fe metals and boron,which promotes the electrochemical performance.Therefore,this work provides a unique strategic plan for the design of efficient and stable B-doped electrocatalysts in an alkaline solution.
文摘A VME-based experiment system for n-y discrimination using the charge comparison method was established.A data acquisition program for controlling the programmable modules and processing data online via VME64X bus was developed through the use of Lab VIEW.The two-dimensional（2D） scatter plots of the charge in the slow component vs.the total charge from ^（241）Am-Be and 252Cf neutron sources are presented.The 2D scatter plots of the energy vs.the ratio of the charge in the slow component to the total charge of the pulses are also presented.The quality of n-γ discrimination was checked by the figure-of-merit,and the results showed good performance of n-γ discrimination at the low energy range.Neutrons and γ-rays were separated above 50 keVee（electron-equivalent energy）.The quality of n-γ discrimination has been improved compared with others＇ results at five energies（150,250,350,450,550 keVee）.
文摘In this paper a feasibility study of the Bc meson to measure its mass and lifetime is described with the general purpose detector at the LHC. The study solely concentrated on the J/ψn^＋, J/ψ→μ^＋μ^- decay channel of the Bc and it was concluded that about 120 events can be selected in the first fb^-1 of data. With this data sample, the mass resolution was estimated to be 2.0（stat.） MeV/c^2 while the cτ resolution was found to be 13.1（stat.） p.m, i.e. the lifetime resolution to be 0.044（stat.） ps.
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51602340,51702355,and 61674167)the Natural Science Foundation of Beijing Municipality of China(Grant No.4192064)+1 种基金the National Key Research Program of China(Grant Nos.2018YFB1500500 and 2018YFB1500200)the JKW Project of China(Grant No.31512060106)。
文摘Based on the surface passivation of n-type silicon in a silicon drift detector(SDD), we propose a new passivation structure of SiO2/Al2O3/SiO2 passivation stacks. Since the SiO2 formed by the nitric-acid-oxidation-of-silicon(NAOS)method has good compactness and simple process, the first layer film is formed by the NAOS method. The Al2O3 film is also introduced into the passivation stacks owing to exceptional advantages such as good interface characteristic and simple process. In addition, for requirements of thickness and deposition temperature, the third layer of the SiO2 film is deposited by plasma enhanced chemical vapor deposition(PECVD). The deposition of the SiO2 film by PECVD is a low-temperature process and has a high deposition rate, which causes little damage to the device and makes the SiO2 film very suitable for serving as the third passivation layer. The passivation approach of stacks can saturate dangling bonds at the interface between stacks and the silicon substrate, and provide positive charge to optimize the field passivation of the n-type substrate.The passivation method ultimately achieves a good combination of chemical and field passivations. Experimental results show that with the passivation structure of SiO2/Al2O3/SiO2, the final minority carrier lifetime reaches 5223 μs at injection of 5×10^(15) cm^(-3). When it is applied to the passivation of SDD, the leakage current is reduced to the order of nA.
文摘采用金属有机化学气相沉积(MOCVD)方法在Si衬底上实现了立方结构的Mg0.25Zn0.75O薄膜生长。在此基础上,实现了Mg0.25Zn0.75O/n-Si异质结型日盲紫外探测器。该探测器在-5 V偏压下,器件暗电流为0.02 m A。在0 V偏压下的峰值响应位于大约280 nm处,响应度为1.2 m A/W。
