Effect of crystallization route on the properties of LiMn2O4 thin films prepared by spin coating

LiMn₂O₄ thin films were prepared by spin coating through intermediate amorphous layer route (IALR) and intermediate crystallized layer route (ICLR). The phase identification, surface morphology, and electrochemical properties of the films prepared by different crystallization routes were studied by X-ray diffraction, scanning electron microscopy, and galvanostatic charge–discharge experiments. The results show that both films prepared by different crystallization routes are homogeneous and crack free. Compared with the film prepared by IALR, the film prepared by ICLR shows smaller grain size and is smoother and denser. The LiMn₂O₄ film prepared by ICLR delivers the specific capacity of 39.8 μAh?cm^?2?μm^?1, which is higher than 35.6 μAh?cm^?2?μm^?1 for the one prepared by IALR. The capacity loss of the film prepared by ICLR after being cycled 100 times is 3.4 %, which is smaller than that of 5.5 % for the film prepared by IALR. The film prepared by ICLR shows higher specific capacity and better cycling behavior than the one prepared by IALR.     

Thermal transport in lithium-ion battery: A micro perspective for thermal management

In recent years, lithium ion (Li-ion) batteries have served as significant power sources in portable electronic devices and electric vehicles because of their high energy density and rate capability. There are growing concerns towards the safety of Li-ion batteries, in which thermal conductivities of anodes, cathodes, electrolytes and separator play key roles for determining the thermal energy transport in Li-ion battery. In this review, we summarize the state-of-the-art studies on the thermal conductivities of commonly used anodes, cathodes, electrolytes and separator in Li-ion batteries, including both theoretical and experimental reports. First, the thermal conductivities of anodes and cathodes are discussed, and the effects of delithiation degree and temperature of materials are also discussed. Then, we review the thermal conductivities of commonly used electrolytes, especially on solid electrolytes. Finally, the basic concept of interfacial thermal conductance and simulation methods are presented, as well as the interfacial thermal conductance between separator and cathodes. This perspective review would provide atomic perspective knowledge to understand thermal transport in Li-ion battery, which will be beneficial to the thermal management and temperature control in electrochemical energy storage devices.     

Paul阱中两个Bi+共线的能量本征态性质

通过对Paul阱中共线两Bi 形成的系统波函数、能谱和相对距离的平均值的精确计算,计算得到的频率、能量是目前的离子阱实验能达到的值;并且对共线两个Bi 的相对几率分布和系统能量本征态进行分析.     

二阶微分方程反周期边值问题解的存在性

在这篇文章中,我们考虑了一类非线性二阶常微分方程反周期边值问题．利用上下解方法结合单调迭代技巧,我们得到了解的存在性结果．     

活性炭负载对甲苯磺酸催化微波合成环己酮乙二醇缩酮

在微波辐射下,以活性炭负载对甲苯磺酸为非均相催化剂,不用溶剂,用环己酮和乙二醇为原料合成环己酮乙二醇缩酮。重点考察了酮醇物质的量比、催化剂用量、微波功率和辐射时间对产品收率的影响。实验结果表明,活性炭负载对甲苯磺酸有着良好的催化活性,当环己酮的加入量为0.2mol,n（环己酮）：n（乙二醇）=1：1.6,催化剂用量为反应物总质量的0.75%,微波功率450W,辐射时间4min时,缩酮收率可达76.7%,且催化剂重复使用6次仍保持较高活性。     

Fan Ky不等式的一个新改进

利用Gram矩阵的正定性和可变单位向量建立了Fan Ky不等式的一个新的改进,并且建立了反向Fan Ky不等式.对于非奇异矩阵,得到了Fan Ky不等式以及反向Fan Ky不等式的推广.     

A projection-filter method for solving nonlinear complementarity problems

The Josephy-Newton method attacks nonlinear complementarity problems which consists of solving, possibly inexactly, a sequence of linear complementarity problems. Under appropriate regularity assumptions, this method is known to be locally (superlinearly) convergent. Utilizing the filter method, we presented a new globalization strategy for this Newton method applied to nonlinear complementarity problem without any merit function. The strategy is based on the projection-proximal point and filter methodology. Our linesearch procedure uses the regularized Newton direction to force global convergence by means of a projection step which reduces the distance to the solution of the problem. The resulting algorithm is globally convergent to a solution. Under natural assumptions, locally superlinear rate of convergence was established.     

Effect of node deleting on network structure

The ever-increasing knowledge of the structure of various real-world networks has uncovered their complex multi-mechanism-governed evolution processes. Therefore, a better understanding of the structure and evolution of these networked complex systems requires us to describe such processes in a more detailed and realistic manner. In this paper, we introduce a new type of network growth rule which comprises addition and deletion of nodes, and propose an evolving network model to investigate the effect of node deleting on network structure. It is found that, with the introduction of node deleting, network structure is significantly transformed. In particular, degree distribution of the network undergoes a transition from scale-free to exponential forms as the intensity of node deleting increases. At the same time, nontrivial disassortative degree correlation develops spontaneously as a natural result of network evolution in the model. We also demonstrate that node deleting introduced in the model does not destroy the connectedness of a growing network so long as the increasing rate of edges is not excessively small. In addition, it is found that node deleting will weaken but not eliminate the small-world effect of a growing network, and generally it will decrease the clustering coefficient in a network.     

Volume growth of some uniformly contractible Riemannian manifolds

It is shown that if a uniformly contractible Riemannian n-manifold (M,g) is K-quasi-isometric to an n-dimensional normed space\((V^{n},\|\cdot\|)\), (K ≥  1), then\(\liminf_{R\rightarrow \infty}\frac{{Vol}_g( {Ball}_{R})}{R^{n}\omega_{n}}\geq\frac{1}{K^{2n}}\) where ω _n is the volume of the unit Euclidean ball. In particular, if M is uniformly contractible and\(d_{GH}((M,d_g), (V^n,\|\cdot\|)) < \infty \), then M has at least Euclidean volume growth. This corollary covers an earlier result by Burago and Ivanov. Our results are motivated by a volume growth theorem contained in Gromov’s book [Gromov in Progress in Mathematics, vol. 152, Birkhäuser, Boston, 1999, p. 256], we give a detailed proof of this theorem. Using the same argument, we also derive a generalization of the theorem which is pointed out by Gromov.     

钯催化炔丙醇与叔丁基异腈选择性合成吡咯并呋喃衍生物和氨基甲酸酯

报道了钯催化下炔丙醇与叔丁基异腈反应高选择性合成吡咯并呋喃衍生物和氨基甲酸酯的新方法.在10%(摩尔分数)Pd(OAc)₂与110%(摩尔分数)LiBr存在下,一分子炔丙醇与三分子叔丁基异腈在水的参与下发生“有序的”异腈三重插入反应,以56%～73%的产率高选择性地生成了吡咯并呋喃衍生物;而在10%(摩尔分数)Pd(PPh₃)₄和110%(摩尔分数)K₃PO₄存在下,一分子炔丙醇与一分子叔丁基异腈在空气中氧气的参与下发生简单氧化偶联反应,以51%～74%的产率生成了氨基甲酸酯.该方法仅通过简单改变钯催化剂与盐的种类就能得到不同产物,且反应选择性高,分别为吡咯并呋喃亚胺衍生物和氨基甲酸酯提供了有吸引力的合成途径.