Tensile,thermal, and antibacterial characterization of composites of cellulose/modified Pennisetum purpureum natural fibers with in situ generated copper nanoparticles

Eco-friendly all cellulose composites were developed using cellulose as matrix and nanocomposite (in situ generated copper nanoparticles modified Napier Grass Fibers (NGFs)) as fillers for the antibacterial applications. The content of the nanocomposite filler was increased from 1?wt.% to 5?wt.% in the cellulose matrix. All these composites were characterized by Scanning Electron Microscopy (SEM), Tensile, Thermo Gravimetric Analysis (TGA), and antibacterial tests. SEM-EDX analysis revealed the in situ generation of copper nanoparticles on the surface of the films. Further, all cellulose composites showed good thermal stability. A minimum of 30% increase in char residue was observed in all cellulose nanocomposites compared to matrix. Antibacterial analysis indicated an excellent clear zone formation against both Gram Negative (Escherichia coli) and Gram Positive (Staphylococcus) bacteria. Hence, all these cellulose nanocomposite films can be considered as antibacterial packaging and dressing materials in medical field.     

PEO-PAN-PEO三明治结构新型固态聚合物电解质的研究

为了解决聚丙烯腈(PAN)聚合物电解质膜刚性强、界面接触状况差的问题,将聚氧化乙烯(PEO)电解质膜贴合在PAN电解质膜的两侧,形成三明治结构PEO-PAN-PEO新型聚合物电解质复合膜.在高温下PEO层具有的柔性大幅度增加了电极与电解质的接触面积,降低了界面阻抗,成功充当了全固态锂电池的电解质膜.以金属锂为负极、LiFePO4为正极所组装的全固态锂电池在60℃下工况良好,初始放电比容量是153mAh/g,40周容量保持率为87%.     

Binary electrocatalysts for organic oxidations

The electro-oxidation of formaldehyde and methanol has been studied on a number of binary platinum electrocatalysts. These comprised mixed electro-deposits of Pt with Sb, As, Bi, Hg, Re, Te or Sn and a range of homogeneous Pt-Rh alloys of different, known, surface composition. These systems were found to exhibit an enhanced activity over that of platinum alone, and this behaviour was correlated with the ease of adsorption of oxygen on the added metal. The activities for organic oxidation were compared with predictions of a model involving reaction between adsorbed oxygen and organic species on the metal surface. The proposed mechanism accounts for the behaviour of both homogeneous and heterogeneous alloy systems.     

A superhard orthorhombic carbon with all six-membered-ring in sp3 bonding networks

We identify by first-principles calculations a new diamond-like carbon phase with a 16-atom orthorhombic primitive cell in $Pbcn$ (${D_{2h}}^{14}$) symmetry. This new carbon allotrope consists of all $s{p}^3$ six-membered rings like as the reported BC8, BC12 and R16 carbon, while energetically more stable than these carbon phases. Its dynamical stability has been confirmed by phonon mode analysis and molecular dynamics simulations. The calculated bulk modulus (435 GPa) and Vickers hardness (93 GPa) are comparable to that of diamond, showing as a superhard carbon material. Electronic band calculations reveal that it is an insulator with an indirect band gap of 4.35 eV. Simulated X-ray diffraction spectrum presents a complicated pattern, showing an amorphous form of diamond, reflecting its structural complexity stemming from its multiple bond lengths and bond angles, but matches well with the diffractions peaks found in the diamond-rich coatings on stainless steel substrate. These findings lay a foundation for further study of this new diamond-like carbon allotrope and its outstanding properties.     

Characterizations of graphs G having all [1,k]-factors in kG

Let $k\ge 1$ be an integer and $G$ be a graph. Let $kG$ denote the graph obtained from $G$ by replacing each edge of $G$ with $k$ parallel edges. We say that $G$ has all $[1,k]$-factors or all fractional $[1,k]$-factors if $G$ has an $h$-factor or a fractional $h$-factor for every function $h:V\left(G\right)\to \{1,2,\dots ,k\}$ with $h\left(V\left(G\right)\right)$ even. In this note, we come up with simple characterizations of a graph $G$ such that $kG$ has all $[1,k]$-factors or all fractional $[1,k]$-factors. These characterizations are extensions of Tutte’s 1-Factor Theorem and Tutte’s Fractional 1-Factor Theorem.     

Sodium-23 MAS NMR study on nuclear quadrupole interaction in Na1−xAgxNO2

Ag-impurity effects on the first- and second-order quadrupole interaction (QI) at ²³Na site in an isomorphic mixed system, Na_1−xAg_xNO₂ (x=0, 0.0084, 0.026, 0.079, 0.094, 0.16), have been investigated by employing ²³Na (I=3/2) magic angle spinning nuclear magnetic resonance (MAS NMR) technique. The central transition (CT) and satellite transition (ST) are simultaneously observed with this system. From the spectral analysis, the quadrupole parameter and its distribution width are obtained as a function of Ag concentration. From the intensity loss of CT MAS centerband and of the envelope function of ST MAS sidebands due to impurities, the range of their influence on the second- and first-order QI is estimated. The estimated ranges contain the second and first neighbouring Na sites from the resonating ²³Na nucleus for the first- and second-order QI, respectively.     

大视场三反射面非共轴光学系统研究

本文研究了一种各面都是二次曲面的三反射面非共轴光学系统,并给出视场角为16°×2°,焦距为1500mm的设计结果.     

全光网络迂回路由的算法及性能分析

分别对波长通道（ＷＰ）和虚波长通道（ＶＷＰ）两种机制的全光网络迂回路由算法的阻塞性能进行了数值分析，并给出了一个任意拓扑全光网络的计算机数值模拟，对比了两种机制的网络阻塞性能。     

条件概率与贝叶斯公式

条件概率与贝叶斯公式是初等概率中的重点与难点,笔者在教学中发现很多学生在解这两方面的习题时,出错率很高,其原因就是不能全面,正确地理解条件概率的定义,以及不知道在什么情况下动用贝叶斯公式。本文就这一问题来阐述怎样正确掌握条件概率的概念及怎样正确运用贝叶斯公式解题。