快速高准确度的闪烁探测技术

闪烁探测器具有探测效率高和适于多种条件下应用等优点。但在高计数率测量时,光电倍增管出现的疲劳现象难以克服,其长期稳定性也较差。 本文提出一种措施,使闪烁探测器在每秒10~5个计数脉冲下获得了高的精度和好的稳定性。这项技术已经应用于FT-1型核子低含沙量计中。经测试表明,当每次测量历时为100秒时该仪器的计数精度和8小时长期     

退火炉自动控制系统设计

山东烟台钢管总厂冷拔分厂退火炉自动控制系统的设计以微机、智能仪表、变频调速器为主,具有控制精度高、降低消耗、操作维修方便、提高劳动生产率等特点。     

国家烟草专卖局现行职能缺陷刍议

2008年,国务院国家烟草专卖局调整为工业和信息化部管理的副部级国家局.这次调整对国家烟草专卖局的职责有所优化,但并未能根本触动"政企合一"的体制,缺陷明显,政策制定和贯彻落实时有冲突.     

R407C组分分离特性实验研究

针对H407C三元混合工质的非共沸特性,在组分分离实验台上进行了相应的分离实验。结果表明：不同的分离器在不同的加热功率下的分离效果不同;经过组分分离实验,R407C的组分有明显的改变,并且在一定的实验工况下可以得到较好的分离效果。经分离后,轻、重组分最高比例可达48．71％和98．23％。     

Cryogenic Exfoliation of 2D Stanene Nanosheets for Cancer Theranostics

Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedi-cal application remains largely un...     

Polyoxometalate‐Derived Hexagonal Molybdenum Nitrides (MXenes) Supported by Boron,Nitrogen Codoped Carbon Nanotubes for Efficient Electrochemical Hydrogen Evolution from Seawater

MXenes and doped carbon nanotubes (CNTs) have entered into research arenas for high‐rate energy storage and conversion. Herein, a method of postsynthesis of MXenes in boron, nitrogen codoped CNTs (BNCNTs) is reported with their electrocatalytical hydrogen evolution performance. The encapsulation of hexagonal molybdenum nitrate nanoparticles (h‐MoN NPs) into BNCNTs protects h‐MoN NPs from agglomeration and poisoning in the complex environment. In principle, the synergism of B and N dopants on the doped CNTs and confined h‐MoN NPs produces extremely active sites for electrochemical hydrogen evolution. Density functional theory calculations reveal that the active sites for hydrogen evolution originate from the synergistic effect of h‐MoN(001)/CN (graphitic N doping) and h‐MoN(001)/BNC. The h‐MoN@BNCNT electrocatalyst exhibits a small overpotential of 78 mV at 10 mA cm^?2 and Tafel slope of 46 mV per decade, which are dramatically improved over all reported MoN‐based materials and doped CNTs. Additionally, it also exhibits outstanding electrochemical stability in environments with various pH values and seawater media from South China Sea.     

SiO2/4H-SiC(0001)界面过渡区的ADXPS研究

采用角依赖X射线光电子谱技术(ADXPS)对高温氧化SiO2/4H-SiC(0001)界面过渡区的组成、成分分布等进行了研究.通过控制1%浓度HF酸刻蚀氧化膜的时间,制备出超薄膜(1～1.5nm)样品,同时借助标准物对照分析,提高了谱峰分解的可靠性.结果显示,高温氧化形成的SiO2/4H-SiC(0001)界面,同时存在着Si1+,Si2+,Si33+3种低值氧化物,变角分析表明,一个分层模型适合于描述该过渡区的成分分布.建立了过渡区的原子级模型并计算了氧化膜厚度.结合过渡区各成分含量的变化及电容-电压(C-V)测试分析,揭示了过渡区成分与界面态的直接关系.     

Enhancement of gas sensing properties of CdS nanowire/ZnO nanosphere composite materials at room temperature by visible-light activation

CdS nanowire/ZnO nanosphere materials (CdS/ZnO) with hierarchical structure were synthesized by a three-step solvothermal process. XRD, FESEM and TEM analysis confirmed the growth of ZnO nanospheres on the surface of CdS nanowires (NWs). The transient photovoltage (TPV) measurements revealed that the interface between CdS and ZnO can inhibit the recombination of photogenerated excess carriers and prolong the lifetime of excess carriers in CdS/ZnO materials. Moreover, the CdS/ZnO materials exhibit a dramatic improvement in optoelectronic performance and visible-light-irradiation gas sensing activity, which gave 1 order of magnitude larger than that of CdS NWs in response to formaldehyde. The enhancement of sensing properties is attributed to the interfacial transport of excess carriers.     

High pressure phase transitions for CdSe

The structure and pressure-induced phase transitions for CdSe are investigated using first-principles calculations. The pressure-induced phase transition sequence WZ/ZB → Rs → Cmcm → CsCl for CdSe is drawn reasonably for the fist time, the corresponding transition pressures are 3.8, 29 and 107 GPa, respectively and the intermediate states between the Cmcm structure and the CsCl structure should exist.     

一种谐振式密度（浓度）分析仪的研制与应用

矿浆浓度（密度）的测量一直是选矿行业的技术难题,对矿浆浓度（密度）的测量精度直接影响着选矿自动化的控制水平和控制效果。谐振式密度（浓度）分析仪是根据元器件振动衰减原理而设计,主要由音叉传感器、驱动检测电路、主控芯片、辅助电路和相应的壳体构成。浓度仪在工作时由激励线圈产生激励促使音叉体产生振动,振动频率由压电晶体检测出来,并通过移相和放大电路后转换为测量所需的电信号。当液体流经振动叉体时,因流体质量的改变引起谐振频率的变化,仪器采集系统采集这些频率变化。由于不同密度的流体流经振动系统时会产生不同的振动频率,仪器检测出振动频率变化后即可通过振动频率与密度间的函数关系式计算出流经流体的密度值,推算流经流体的浓度值。谐振式密度（浓度）分析仪在南京某选厂应用结果表明,该设备可以提高选矿过程浓度检测的准确性和可靠性。