Influence of dopant concentration on electrical quantum transport behaviors in junctionless nanowire transistors

We discuss the random dopant effects in long channel junctionless transistor associated with quantum confinement effects. The electrical measurement reveals the threshold voltage variability induced by the random dopant fluctuation.Quantum transport features in Hubbard systems are observed in heavily phosphorus-doped channel. We investigate the single electron transfer via donor-induced quantum dots in junctionless nanowire transistors with heavily phosphorusdoped channel, due to the formation of impurity Hubbard bands. While in the lightly doped devices, one-dimensional quantum transport is only observed at low temperature. In this sense, phonon-assisted resonant-tunneling is suppressed due to misaligned levels formed in a few isolated quantum dots at cryogenic temperature. We observe the Anderson-Mott transition from isolate electron state to impurity bands as the doping concentration is increased.     

水体中甲基叔丁基醚(MTBE)的植物修复

研究凤眼莲对水体中甲基叔丁基醚(MTBE)的吸收转移规律和富集特征. 结果表明: 胁迫5 d后, 处理Ⅰ(整株凤眼莲)中MTBE的平均浓度减少了94.25%, 处理Ⅱ(去叶凤眼莲)中MTBE的平均浓度减少了近50%, 处理Ⅰ比处理Ⅱ约减少44%, 而处理Ⅲ（对照）中MTBE的平均浓度只减少7.3%, 表明凤眼莲叶片的蒸腾作用是水溶液中MTBE减少的主要原因. 将实验所得数据进行回归分析得出： 20 ℃时, 水体中MTBE消失符合一级动 力学方程； 处理Ⅰ、 处理Ⅱ的消失速率明显大于处理Ⅲ. 凤眼莲暴露在ρ_MTBE<1 110 mg/L溶液中时, 培养5 d未观察到MTBE对植物的毒性, 蒸腾量与生物量比值变化不明显,当ρ_MTBE=1 480 mg/L时, 凤眼莲的蒸腾量与生物量比值明显减小, 凤眼莲叶片边缘干枯和萎黄. MTBE在凤眼莲根、 茎、 叶中的分布比例约为1 ∶1.5 ∶0.5, 其分布规律为： 茎>根>叶.     

生活垃圾堆肥处理对重金属形态的影响

选用抚顺市生活垃圾作为堆肥原料,在控制条件下进行好氧堆肥试验,研究生活垃圾中重金属在堆肥过程中形态的变化.结果表明,堆肥处理不能降低生活垃圾中重金属总量,但影响重金属的形态.铁锰氧化物结合态Cd的比例提高8.7％；有机结合态Cr的比例提高26.7％;残渣态Hg、Pb和As的比例有所上升；稳定形态Hg、Pb、Cr、As的比例上升.研究结果对生活垃圾堆肥化处理的重金属环境安全性具有指导意义.     

Meso-四(对羟基苯基)卟啉及其金属配合物的合成与表征

以丙酸为溶剂，用吡咯和对羟基苯甲醛直接合成了Meso-四（对羟基苯基）卟啉，探讨了溶剂丙酸和无水乙醇的用量对反应产率的影响；利用液相法合成了Mesc〉四（对羟基苯基）卟啉与Fe^3＋，Mn^2＋，Co^2＋，Ni^2＋，Cu^2＋和Zn^2＋ 6种金属离子形成的配合物，探讨了Meso-（对羟基苯基）卟啉与金属盐用量的比例对产率的影响；利用UV-Vis和MS对合成的物质进行表征．     

浅谈学生心理健康的培养

本文分析了心理健康的含义和标准;说明了学校教育工作对培养学生心理健康的重要意义;研究了心理健康培养的内容和方法。     

加入WTO对中国社会保障制度的影响及对策

加入WTO将对我国社会经济体制和社会结构产生巨大冲击。面对机遇和挑战,我们必须加强社会保障制度建设,充分发挥社会保障作为社会稳定器的作用,化解加入WTO后外来冲击的风险。     

便携式气相色谱-质谱联用仪现场测定畜禽粪便堆肥中挥发性有机物

采用便携式气相色谱-质谱联用仪进行了畜禽粪便堆肥排放气体中挥发性有机物质的现场分析.结果表明,在堆肥排放气体中可检测到含硫物质、脂肪烃、芳香烃及含氯有机物共20种物质.在已定量的8种物质中,CS2浓度最高,达到204 mg/m3;CS2和二甲二硫超过《恶臭污染物排放标准》(GB1455-93)的限值;SO2和苯超过《室内空气质量标准》(GB/T 18883-2002)的限值.本方法避免了常规检测中易出现的组分分解等问题,SO2测定值较常规方法提高59.3％.本方法操作方便,结果准确,适于对挥发性有机化合物的在线监测.     

Electric-field-dependent charge delocalization from dopant atoms in silicon junctionless nanowire transistor

We study electric-field-dependent charge delocalization from dopant atoms in a silicon junctionless nanowire transistor by low-temperature electron transport measurement. The Arrhenius plot of the temperature-dependent conductance demonstrates the transport behaviors of variable-range hopping(below 30 K) and nearest-neighbor hopping(above 30 K).The activation energy for the charge delocalization gradually decreases due to the confinement potential of the conduction channel decreasing from the threshold voltage to the flatband voltage. With the increase of the source–drain bias, the activation energy increases in a temperature range from 30 K to 100 K at a fixed gate voltage, but decreases above the temperature of 100 K.     

Transport spectroscopy through dopant atom array in silicon junctionless nanowire transistors

We demonstrate electron transport spectroscopy through a dopant atom array in n-doped silicon junctionless nanowire transistors within a temperature range from 6 K to 250 K. Several current steps are observed at the initial stage of the transfer curves below 75 K, which result from the electron transport from Hubbard bands to one-dimensional conduction band. The current-off voltages in the transfer curves have a strikingly positive shift below 20 K and a negative shift above 20 K due to the electrostatic screening induced by the ionized dopant atoms. There exists the minimum electron mobility at a critical temperature of 20 K, resulting from the interplay between thermal activation and impurity scattering. Furthermore, electron transport behaviors change from hopping conductance to thermal activation conductance at the temperature of 30 K.     

基于RBF神经网络的直接模型参考自适应控制

大多数的现代被控对象均具有非线性的特性,使得采用传统的PI、PID控制很难取得较好的控制效果.人工神经网络,在一定条件下可以任意精度逼近任意非线性函数且具有较强的自学习、自适应、自组织能力.故将其应用于非线性严重的装置的控制,可充分发挥其非线性映射能力和自学习、自适应、自组织的能力,实现对非线性装置的高性能控制.相比于Sigmoid激发函数的BP神经网络,RBF神经网络具有更简洁的网络结构和更快的收敛速度且可避免收敛于局部极值点,使得RBF神经网络更适合于在线应用同时也具有更好的控制效果.本文采用RBF神经网络构成神经网络NN进行自适应控制.为进一步加快神经网络的学习收敛速度,本文采用变学习速率的神经网络学习算法,学习速率随收敛过程误差的大小而自适应地进行调整,这可大大加快神经网络学习训练的收敛速度.本文对RBF神经网络直接自适应控制策略应用于非线性被控装置的控制进行了仿真研究,仿真结果表明,系统的动态响应快,超调小,稳态精度高,有较强的跟踪能力,具有较好的控制效果.