Conductivity exponent in three-dimensional percolation by diffusion based on molecular trajectory algorithm and blind-ant rules

Diffusion on random systems above and at their percolation threshold in three dimensions is carried out by a molecular trajectory method and a simple lattice random walk method, respectively. The classical regimes of diffusion on percolation near the threshold are observed in our simulations by both methods. Our Monte Carlo simulations by the simple lattice random walk method give the conductivity exponent μ/ν=2.32±0.02 for diffusion on the incipient infinite clusters and μ/ν=2.21±0.03 for diffusion on a percolating lattice above the threshold. However, while diffusion is performed by the molecular trajectory algorithm either on the incipient infinite clusters or on a percolating lattice above the threshold, the result is found to be μ/ν=2.26±0.02. In addition, it takes less time step for diffusion based on the molecular trajectory algorithm to reach the asymptotic limit comparing with the simple lattice random walk.     

Universal scaling behaviors of meteorological variables’ volatility and relations with original records

Volatility series (defined as the magnitude of the increments between successive elements) of five different meteorological variables over China are analyzed by means of detrended fluctuation analysis (DFA for short). Universal scaling behaviors are found in all volatility records, whose scaling exponents take similar distributions with similar mean values and standard deviations. To reconfirm the relation between long-range correlations in volatility and nonlinearity in original series, DFA is also applied to the magnitude records (defined as the absolute values of the original records). The results clearly indicate that the nonlinearity of the original series is more pronounced in the magnitude series.     

Detection of human erythrocytes influenced by iron deficiency anemia and thalassemia using atomic force microscopy

PurposeIron deficiency anemia (IDA) and thalassemia (THAL) are two types of microcytic anemia, and both of these conditions disturb the morphology and function of erythrocytes at the molecular level. The ability to distinguish between thalassemic and iron deficiency anemia microcytosis has important clinical implications. The purpose of this study was to show that pathophysiological changes to erythrocytes could be detected at the nanometer scale, which is important for the early diagnosis of anemia and for distinguishing between IDA and THAL.MethodsBlood samples were taken from six healthy volunteers and six patients with either iron deficiency anemia or thalassemia. Changes in the morphological of erythrocytes were studied at the nanometer level using atomic force microscopy (AFM).ResultsThere were dramatic overall shape and surface membrane deformations of the erythrocytes associated with iron deficiency anemia and thalassemia compared to healthy erythrocytes. Healthy and pathological erythrocytes of iron deficiency anemia and thalassemia could be distinguished by the morphologic parameters of width, length, the ratio of length to width, valley, peak, valley-to-peak, standard deviations, and surface fluctuation. These AFM parameters of erythrocyte morphology differed greatly between iron deficiency anemia and thalassemia.ConclusionAFM was found to be an extremely useful tool for detecting and distinguishing between iron deficiency anemia and thalassemia. Erythrocyte morphology is an important determinant for diagnosing and distinguishing IDA and THAL.     

Direct observation of Sn crystal growth during the lithiation and delithiation processes of SnO(2) nanowires

Tin (Sn) crystal growth on Sn-based anodes in lithium ion batteries is hazardous for reasons such as possible short-circuit failure by Sn whiskers and Sn-catalyzed electrolyte decomposition, but the growth mechanism of Sn crystals during battery cycling is not clear. Here we report different growth mechanisms of Sn crystal during the lithiation and delithiation processes of SnO(2) nanowires revealed by in situ transmission electron microscopy (TEM). Large spherical Sn nanoparticles with sizes of 20-200nm grew instantaneously upon lithiation of a single-crystalline SnO(2) nanowire at large current density (j>20A/cm(2)), which suppressed formation of the Li(x)Sn alloy but promoted agglomeration of Sn atoms. Control experiments of Joule-heating (j≈2400A/cm(2)) the pristine SnO(2) nanowires resulted in melting of the SnO(2) nanowires but not Sn particle growth, indicating that the abnormal Sn particle growth was induced by both chemical reduction (i.e., breaking the SnO(2) lattice to produce Sn atoms) and agglomeration of the Sn atoms assisted by Joule heating. Intriguingly, Sn crystals grew out of the nanowire surface via a different "squeeze-out" mechanism during delithiation of the lithiated SnO(2) nanowires coated with an ultra-thin solid electrolyte LiAlSiO(x) layer. It is attributed to the negative stress gradient generated by the fast Li extraction in the surface region through the Li(+)-conducting LiAlSiO(x) layer. Our previous studies showed that Sn precipitation does not occur in the carbon-coated SnO(2) nanowires, highlighting the effect of nanoengineering on tailoring the electrochemical reaction kinetics to suppress the hazardous Sn whiskers or nanoparticles formation in a lithium ion battery.     

不对称三苯胺-锌酞菁的合成及性能研究

以对氨基酚、对硝基氯苯、8-羟基喹啉、4-硝基邻苯二甲腈以及醋酸锌为主要原料,合成了不对称2(3)-[二(对硝基苯基)氨基苯氧基]-9(10),16(17),23(24)-三(8-喹啉氧)锌酞菁(TQPc).用核磁、红外、元素分析等表征TQPc以及前驱化合物结构,TQPc的电子吸收光谱表现出了强烈的π-π*跃迁现象.利用紫外光谱研究了其N,N-二甲基甲酰胺(DMF)和CH2Cl2溶液的吸收光谱性质,结果表明在DMF中主要以单体的形式存在,浓度在0.223×10-5～2.587×10-5mol/L时,TQPc在CH2Cl2溶液中有二聚体的存在,经计算得到平衡常数为0.24×105L/mol.用循环伏安法研究了TQPc的氧化还原行为,结合差分伏安数据计算了能级结构,LUMO(-1.04 V vs SCE)和HOMO(0.78 V vs SCE)与纳米TiO2导带能级匹配,可作为性能较好的电荷传输材料用于染料敏化太阳能电池.     

单轴、双轴应变Si拉曼谱应力模型

本文依据拉曼光谱原理, 基于Secular方程及拉曼选择定则分别获得了单轴、 双轴(001), (101), (111)应变Si材料应变张量与拉曼谱线移动的定量关系, 并在此基础上, 基于广义胡克定律最终建立了单轴、双轴(001), (101), (111)应变Si材料拉曼谱峰与应力的理论关系模型. 该模型建立过程详细、系统, 所得结果全面、量化, 可为应变Si材料应力的测试分析提供重要理论参考.     

基于高频雷达多普勒谱预测风向的一种新方法

通过高频雷达一阶多普勒谱与海上风向的关系, 提出了一种基于神经网络和多波束采样法相结合预测海面风向的新方法. 在神经网络不同输入、输出参数情况下对扩展因子为奇数时的仿真数据进行了风向预测, 并在扩展因子为偶数时结合多波束采样法进行风向预测, 消除了风向的模糊性. 通过预测数据和仿真数据对比, 发现两者符合较好. 从神经网络和多波束采样法相结合的预测结果中可以看出, 风向的误差大约为4°—6°, 风向扩展因子的平均误差为0.26, 为预测海面风场的研究提供一种新的思路和方法.     

质子注入能量对垂直腔面发射激光器的阈值和功率的影响

文章研究了如何兼顾质子注入型垂直腔面发射激光器的功率和阈值性能.从模拟和实验两方面分析了质子注入能量与器件功率和阈值特性的关系.发现注入能量过高时,损伤有源区,降低了功率性能.而能量过低则会减弱对注入电流的限制,增加阈值.计算和实验结果表明,对于文中的器件结构,315 keV的注入能量是合适的.在10μm的注入孔径下获得器件的阈值为4.3 mA,功率为1.7 mW.     

兰州重离子加速器冷却储存环中电子冷却性能

为了在兰州重离子加速器冷却储存环(HIRFL-CSR)上开展一维离子束序化的研究,在CSR主环上,对6.39 MeV/u的58Ni19+离子束进行了冷却累积实验。测量了离子束与电子束之间不同的水平、垂直夹角以及不同电子束剖面的情况下,束流累积及束流寿命变化情况;重点研究了离子束衰减过程中动量分散随离子数的变化规律,拟合计算得到了动量分散随离子数按照幂函数衰减的指数;在给定离子数的情况下,动量分散随夹角、电子束剖面的依赖关系,为下一步在CSR上获得纵向一维有序化离子束的研究做准备。在实验中观测到在较大的夹角情况下,离子束出现纵向振荡和中心频率移动。     

Modal interferometer based on tapering single-mode-multimode-single-mode fiber structure by hydrogen flame

A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-singlemode (SMS) fiber structure heated by hydrogen flame.The interference fringe begins to form when tapering length is 19.8 mm,and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller.Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5μm.The temperature and axial strain dependences of the tapered SMS structure are characterized,and the measured temperature and strain coefficients are +7 pm/℃and -9.536 pm/με, respectively.