Booting the electrochemical properties of Fe-based anode by the formation multiphasic nanocomposite for lithium-ion batteries

Fe-based compounds with good environmental friendliness and high reversible capacity have attracted considerable attention as anode for lithium-ion batteries.But,similar to other transition metal oxides(TMOs),it is also affected by large volume changes and inferior kinetics during redox reactions,resulting in the destruction of the crystal structure and poor electrochemical performance.Here,Fe_3O_4/C nanospheres anchored on the two-dimensional graphene oxide as precursors are phosphated and sintered to build the multiphasic nanocomposite.XRD results confirmed the multiphasic nanocomposite composed of Fe_2O_3,Fe_3O_4 and Fe_3PO_7,which will facilitate the Li~+ diffusion.And the carbonaceous matrix will buffer the volume changes and enhance electron conduction.Consequently,the multiphasic Febased anode delivers a large specific capacity of 1086 mAh/g with a high initial Coulombic efficiency of 87% at 0.1 C.It also has excellent cycling stability and rate property,maintaining a capacity retention of～87% after 300 cycles and a high reversible capacity of 632 mAh/g at 10 C.The proposed multiphasic structure offers a new insight into improving the electrochemical properties of TMO-based anodes for advanced alkali-ion batteries.     

Dynamical analysis of boundary behaviors of current-controlled DC–DC buck converter

Nonlinear Dynamics - In this paper, the current-controlled DC–DC buck converter from a new perspective are studied through the switching theory of flow, and the analytical conditions of the...     

基于GPU加速的几何纹理合成方法

提出了一种基于GPU加速的几何纹理合成方法,以解决几何纹理合成过程中高计算量、高存储占用和高耗时等问题.首先,对样本几何纹理数据进行子块划分,并根据子块在样本中的位置关系设计可重用样本顶点数据的数据结构,优化存储以降低内存的占用率;然后,采用GPU多线程并发技术设计并行加速算法,将串行的几何纹理合成过程并行化,从而实现快速生成任意尺寸的新的几何纹理.实验结果表明,该算法不仅占用存储较少,而且在保证合成质量的同时极大地降低了几何纹理的合成耗时.     

Predicting melting temperature directly from protein sequences

Proteins of both hyperthermophilic and mesophilic microorganisms generally constitute from the same 20 amino acids; however, the extent of thermal tolerance of any given protein is an inherent property of its amino acid sequence. The present study is the first to report a rapid method for predicting Tm (melting temperature), the temperature at which 50% of the protein is unfolded, directly from protein sequences (the Tm Index program is available at http://tm.life.nthu.edu.tw/). We examined 75 complete microbial genomes using the Tm Index, and the analysis clearly differentiated hyperthermophilic from mesophilic microorganisms on this global genomic basis. These results are consistent with the previous hypothesis that hyperthermophiles express a greater number of high Tm proteins compared with mesophiles. The Tm Index will be valuable for modifying existing proteins (enzymes, protein drugs and vaccines) or designing novel proteins having a desired melting temperature.     

Comparative Study of Different Measurement Methods for Characterizing Rheological Properties of Lubrication Layer

The lubrication layer plays a governing role in predicting the pumpability of fresh concrete. To determine the effect of measurement methods on the characterization of the rheological properties of the lubrication layer, different measurement systems, including Sliper, tribometer, and the utilization of a mortar rheometer, were employed. The rheological properties and workability of bulk concrete were measured in parallel to investigate the correlation between them and the rheological properties of the lubrication layer. The results show that the measured values of the rheological parameters of the lubrication layer differ due to the systematic deviation between different measurement methods. The results obtained by both tribometer and mortar rheometer were well-correlated, having a linear relationship with the rheological parameters of bulk concrete. The correlation coefficient between results gained with Sliper and rheological parameters of concrete or lubrication layer determined with other methods was not high enough. Addition friction led to the large accidental error and overestimated yield stress obtained with Sliper. The workability of concrete is only suitable for characterizing the rheological properties of bulk concrete.     

胍基硅前驱体的合成及应用

以胍基取代的二甲基二氯硅烷与胺基锂反应合成了3种硅基化合物,使用核磁共振、高分辨质谱、元素分析对化合物结构进行了表征,通过热重分析(TGA)研究了化合物的热稳定性、挥发性、蒸汽压等性能。 3种化合物均具有良好的热稳定性及挥发性,无明显热分解过程,固体残留小于1%,接近纯挥发过程,最高蒸汽压在3600~5300 Pa,满足前驱体使用要求。 以二甲基-胍基-甲乙胺基-硅烷为前驱体,采用螺旋波等离子体气相沉积(HWPCVD)工艺制备了硅基薄膜,使用X射线光电子能谱(XPS)和扫描电子显微镜(SEM)分析了薄膜的化学组成和膜表面结构,XPS分析结果证实该薄膜为Si、N、C组成,实验结果表明,该类胍基硅化合物可作为硅基化学气相沉积(CVD)前驱体材料应用于集成电路制造。     

二溴羟基苯基荧光酮荧光熄灭法测定铜

研究了在pH 6 2～ 8 2磷酸二氢钾 磷酸氢二钠缓冲体系中 ,非离子表面活性剂TritonX 10 0存在下 ,铜 (Ⅱ )与二溴羟基苯基荧光酮 (DBH PF)形成 1∶2红色三元混配合物而使荧光熄灭 ,建立了荧光熄灭法测定铜的新方法。配合物的λex=5 3 0nm ,λem=5 60nm ,含量在 0～ 80 μg·L-1范围内有良好的线性关系 ,检测限为 0 2 μg·L-1。体系的灵敏度高 ,选择性好。Al(Ⅲ )、Fe(Ⅲ )、Ti(Ⅳ )的干扰 ,可用氟化钠、苦杏仁酸掩蔽。方法快速简便 ,用于人发、茶叶及水中微量铜的测定与AAS相符 ,RSD(n=5 ) <6 9% ,回收率在 98%～ 10 4 %之间。     

Calixarene/pillararene-based supramolecular selective binding and molecular assembly

This review mainly summarized the recent researches on the supramolecular selective binding and molecular assembly based on calixarene and pillararene. Several representative examples were provided to expound the progress in the area of recognition and sensing, multi-functional assembly and crosslinked multi-dimensional materials.     

Flexible and Hierarchical Metal–Organic Framework Composites for High‐Performance Catalysis

The development of porous composite materials is of great significance for their potentially improved performance over those of individual components and extensive applications in separation, energy storage, and heterogeneous catalysis. Now mesoporous metal–organic frameworks (MOFs) with macroporous melamine foam (MF) have been integrated using a one‐pot process, generating a series of MOF/MF composite materials with preserved crystallinity, hierarchical porosity, and increased stability over that of melamine foam. The MOF nanocrystals were threaded by the melamine foam networks, resembling a ball‐and‐stick model overall. The resulting MOF/MF composite materials were employed as an effective heterogeneous catalyst for the epoxidation of cholesteryl esters. Combining the advantages of interpenetrative mesoporous and macroporous structures, the MOF/melamine foam composite has higher dispersibility and more accessibility of catalytic sites, exhibiting excellent catalytic performance.