EcoLens: visual analysis of ecological regions in urban contexts using traffic data

Journal of Visualization - The increasing availability of spatiotemporal data provides unprecedented opportunities for understanding the structure of an urban area in terms of people’s...     

Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors

Three‐dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high‐performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D‐Ni‐core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as‐prepared material exhibits a high specific capacitance (726 F g^?1 at a charge/discharge rate of 1 A g^?1), good rate capability (a decay of 33 % in C_sp with charge/discharge rates increasing from 1 to 20 A g^?1), and high cycle stability (only a small decrease of 4.2 % in C_sp after 1000 cycles at a scan rate of 100 mV s^?1). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as‐prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg^?1) and superior long‐term cycle ability (only 4.4 % and 18.6 % loss in C_sp after 2000 and 5000 cycles, respectively).     

Physicochemical properties and bio-interfacial interactions of surface modified PDLLA-PAMAM linear dendritic block copolymers

Here, we demonstrate the applicability of self-assembling linear-dendritic block copolymers (LDBCs) and their nanoaggregates possessing varied surfaces as therapeutic nanocarriers. These LDBCs are comprised of a hydrophobic, linear polyester chemically coupled to a hydrophilic dendron polyamidoamine (PAMAM)—the latter of which acts as the surface of the self-assembled nanoaggregate in aqueous media. To better understand how surface charge density affects the overall operability of these nanomaterials, we modified the nanoaggregate surface to yield cationic (NH₃⁺), neutral (OH), and anionic (COO⁻) surfaces. The effect of these modifications on the physicochemical properties (i.e., size, morphology, and surface charge density), colloidal stability, and cellular uptake mechanism of the polymeric nanocarrier were investigated. This comparative study demonstrates the viability of nanoaggregates formed from PDLLA-PAMAM LDBCs to serve as nanocarriers for applications in drug delivery.     

Investigation of mononuclear,dinuclear, and trinuclear transition metal (II) complexes derived from an asymmetric Salamo‐based ligand possessing three different coordination modes

A new asymmetric Salamo‐based ligand H₂L was synthesized using 3‐tert‐butyl‐salicylaldehyde and 6‐methoxy‐2‐[O‐(1‐ethyloxyamide)]‐oxime‐1‐phenol. By adjusting the ratio of the ligand H₂L and Cu (II), Co (II), and Ni (II) ions, mononuclear, dinuclear, and trinuclear transition metal (II) complexes, [Cu(L)], [{Co(L)}₂], and [{Ni(L)(CH₃COO)(CH₃CH₂OH)}₂Ni] with the ligand H₂L possessing completely different coordination modes were obtained, respectively. The optical spectra of ligand H₂L and its Cu (II), Co (II) and Ni (II) complexes were investigated. The Cu (II) complex is a mononuclear structure, and the Cu (II) atom is tetracoordinated to form a planar quadrilateral structure. The Co (II) complex is dinuclear, and the two Co (II) atoms are pentacoordinated and have coordination geometries of distorted triangular bipyramid. The Ni (II) complex is a trinuclear structure, and the terminal and central Ni (II) atoms are all hexacoordinated, forming distorted octahedral geometries. Furthermore, optical properties including UV–Vis, IR, and fluorescence of the Cu (II), Co (II), and Ni (II) complexes were investigated. Finally, the antibacterial activities of the Cu (II), Co (II), and Ni (II) complexes were explored. According to the experimental results, the inhibitory effect was found to be enhanced with increasing concentrations of the Cu (II), Co (II), and Ni (II) complexes.     

Jordan函数r次方Jrk(n)的误差项的进一步性质

设k，r分别是自然数和非零整数，Jk(n)是Jordan函数。以E(x；k，r)表示和式sum from (n≤x) Jkr(n)的渐近公式中的误差项，本文研究了E(x；k，r)的某种加权平方积分均值。     

离心力场作用下多孔介质中强制对流换热的研究

对离心流化床中空气通过多孔物料层的强制对流换热进行了理论和实验研究。获得了气流和物料间强制对流换热的准则关联式。研究结果表明,在气流速度和温度梯度方向一致的条件下,强制对流换热比通常的边界层强制对流换热有所强化,其换热的准则关联式具有 Nu=CRePr的线性形式。从而验证了改变气流方向和热流密度矢量之间夹角可以强化换热的这一强化传热新原理。     

The Combinatorics of Laguerre,Charlier, and Hermite Polynomials

This paper describes several combinatorial models for Laguerre, Charlier, and Hermite polynomials, and uses them to prove combinatorially some classical formulas. The so-called “Italian limit formula” (from Laguerre to Hermite), the Appel identity for Hermite polynomials, and the two Sheffer identities for Laguerre and Charlier polynomials are proved. We also give bijective proofs of the three-term recurrences. These three families form the bottom triangle in R. Askey's chart classifying hypergeometric orthogonal polynomials.     

用不确定度评价测量结果中的有效自由度的作用

论述了有效自由度的计算方法及有效自由度量值在分析测量结果中的应用。     

汉米尔顿图泛圈性的奥尔型条件

本文所说的图是简单图,未定义的术语见[1,2].n 阶图 G,n≥3,若有长为 n 的圈,则说 G 是汉米尔顿图;若对每个 k,3≤k≤n,G 含有长为 k 的圈,则说 G 是泛圈图.定理1.在 n 阶图 G 中,若对任何点对 x,y∈V(G),xy(?)E(G),都有 d(x)+d(y)≥n,则 G 是汉米尔顿图.     

均苯三甲酸铕及铕镧配合物的合成及荧光性质

以均苯三甲酸为配体,水热条件下合成了均苯三甲酸铕及铕镧系列发光配合物La_xEu_1-x(BTC)·nH₂O(x=0,0.1,0.3,0.5,0.7,0.9),通过元素分析及化学滴定法测定了配合物的组成。用红外光谱对其进行了表征,确定了该系列配合物的组成为La_xEu_1-x(BTC)·nH₂O。研究了系列配合物的荧光性质,荧光光谱表明:该类配合物均能发出强的铕离子的特征荧光,并且镧元素的掺入能增强铕配合物的发光强度,但发射峰的位置基本上没有变化;其中⁵D₀→⁷F₁和⁵D₀→⁷F₂的跃迁发射较强,且均劈裂为两个峰(587,593nm)和(611,618nm),这是由于铕离子所处的配位环境引起的。