Effect of Nb<Superscript>5+</Superscript> charge neutralization substitution on the electrochemical performance of lithium-rich layered oxides

The effect of the Nb⁵⁺ substitution with a charge-compensated strategy in lithium-rich layered oxides (LLOs) Li_1.2Ni_0.13+xCo_0.13-xMn_0.54-xNb_xO₂ (x?=?0, 0.01, 0.02, and 0.03) has been investigated systematically. A hydroxide co-precipitation method followed by a high-temperature solid-state reaction is adopted in the synthesis process. Structural characterization confirms that the low dose substituting of Nb⁵⁺ in the layered structures forms a solid solution, and the samples show low cation mixing and enlarged Li⁺-diffusing channels, which imply favorable high-rate capability. The initial charge/discharge measurements suggest that the oxygen loss from the network during the delithiation process has been suppressed by the substitution of Nb⁵⁺ due to the formation of robust Nb–O bonds and a decrease in TM-O (TMs are transition metals) covalence. Moreover, these Nb–O bonds contribute to the stabilization of the crystalline framework, resulting in an excellent cycle stability with a mitigated voltage decay.     

Surface functionalization and surface recognition: Plasmon optical detection of molecular recognition at self assembled monolayers

The synthesis of biotin- functionalized organic mercaptans and their chemisorption on gold surfaces is described. Biotin bound covalently to self assembled monolayers is recognized by streptavidin from aqueous buffer solutions. Spacer length and packing density of the biotin labels on the organic surface determine the docking kinetics. With a flexible and hydrophilic spacer very fast -diffusion controlled-docking is observed. As an alternative method of self assembly the spreading of organic mercaptans on water surfaces is established. Pressure-area diagrams of different functionalized mercaptans and disulfides are shown and their monolayer properties are discussed.     

高韦伯数条件下黏性对液滴变形过程的影响

为探究液滴黏性对变形过程的影响,深入了解液滴在冲击波作用下变形破碎的行为机制。采用高速阴影技术在水平激波管上拍摄了高韦伯数（We=1 100～4 400）条件下,3种黏性硅油液滴的变形过程。结果表明随着黏性的提升：液滴演化出相应特征所需时间增大,同时会出现新的变形特征;液滴空间及位移特征参数的生长速率降低而变形时间、最大变形高度/位移都增大,这是因为提升的黏性力降低了变形速率、耗散了更多的动能并延长了液滴的变形过程;液滴表面最不稳定的Kelvin-Helmholtz波朝着大尺度、低生长率的方向发展,从而实现黏性对变形过程的延缓作用。随着最大变形位移的增大,最大变形高度首先线性增长,之后增幅降低。

     

复杂电磁环境下电子信息装备试验的综合集成方法分析

在复杂电磁环境下检验电子信息装备是一个复杂系统问题,综合集成方法是一种分析复杂系统的有效解决方法,它综合了还原论与整体论的优点,逐渐发展成为一个比较成熟的系统工程方法论。在简述综合集成方法基本理论的基础上,对电子信息装备试验检验的普遍问题进行了研究。分析了复杂电磁环境下电子信息装备试验的复杂性,指出了传统还原论方法在分析电子信息装备试验中的局限性和障碍,进一步讨论了综合集成方法在分析电子信息装备试验检验的实施过程,为电子装备试验检验提供了新的有效解决思路。     

多总体二阶随机占优对无约束的检验问题

该文将利用保序回归估计和Bootstrap方法对多总体二阶随机占优对无约束的检验问题进行研究,具体步骤如下:首先,利用保序回归估计和经验分布函数构造检验统计量;然后,利用Bootstrap方法给出检验问题的临界值和p值;最后,通过Monte Carlo模拟来说明该文所提出方法的可行性.     

Pr-modified Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> nanofibers as an anode material for lithium-ion batteries with outstanding cycling performance and rate performance

Pr-doped Li₄Ti₅O₁₂ in the form of Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0, 0.01, 0.03, 0.05, and 0.07) was synthesized successfully by an electrospinning technique. ICP shows that the doped samples are closed to the targeted samples. XRD analysis demonstrates that traces of Pr³⁺ can enlarge the lattice parameter of Li₄Ti₅O₁₂ from 8.3403 to 8.3765 Å without changing the spinel structure. The increase of lattice parameter is beneficial to the intercalation and de-intercalation of lithium-ion. XPS results identify the existence form of Ti is mainly Ti⁴⁺ and Ti³⁺ in minor quantity in Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0.05) samples due to the small amount of Pr³⁺. The transition from Ti⁴⁺ to Ti³⁺ is conducive to the electronic conductivity of Li₄Ti₅O₁₂. FESEM images show that all the nanofibers are well crystallized with a diameter of about 200 nm and distributed uniformly. The results of electrochemical measurement reveal that the 1D Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0.05) nanofibers display enhanced high-rate capability and cycling stability compared with that of undoped nanofibers. The high-rate discharge capacity of the Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0.05) samples is excellent (101.6 mAh g^?1 at 50 °C), which is about 58.48 % of the discharge capacity at 0.2 °C and 4.3 times than that of the bare Li₄Ti₅O₁₂ (23.5 mA g^?1). Even at 10 °C (1750 mA g^?1), the specific discharge capacity is still 112.8 mAh g^?1 after 1000 cycles (87.9 % of the initial discharge capacity). The results of cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS) illustrate that the Pr-doped Li₄Ti₅O₁₂ electrodes possess better dynamic performance than the pure Li₄Ti₅O₁₂, further confirming the excellent electrochemical properties above.     

The formation and electrochemical property of lithium-excess cathode material Li<Subscript>1.2</Subscript>Ni<Subscript>0.13</Subscript>Co<Subscript>0.13</Subscript>Mn<Subscript>0.54</Subscript>O<Subscript>2</Subscript> with petal-like nanoplate microstructure

Lithium-excess oxide shows great potential for its high specific capacity of exceeding 280 mAh g^?1. However, the poor rate capability caused by the poor electrochemical kinetics condition as well as the structure instability block the way of its application. Here, we aimed to improve the kinetics circumstance for lithium ion transference through the material bulk by synthesizing lithium-excess oxide with high specific surface area. Petal-like nanoplates and nanoparticles with excellent electrochemical performance were obtained at different sintering temperatures and times by the electrospinning-sintering method, which facilitates the sufficient contact of electrode and electrolyte and helps to reduce the polarization during the electrochemical reaction process. Cyclic voltammetry tests verify that a portion of oxidized oxygen is reduced reversibly at 3.0 V and the reduction of oxygen contributes to the discharge capacity. Electrochemical impedance spectroscopy plots illustrate the ameliorative electrochemical kinetics is conductive to the oxidation of oxygen at 4.5 V.     

矩形网格上二元切触插值的表现公式

In this paper, we make use of the generalized Vandermonde matrix, and set up formula of bivariate contact interpolation over rectangular grids and a example is given.