Dimeric naphthalene diimide based small molecule acceptors: synthesis,characterization, and photovoltaic properties

Herein, we present two naphthalene diimide (NDI) dimer based small molecule acceptors, Bis-NDI-T-EG and Bis-NDI-BDT-EG, in which two NDI units are bridged, respectively, by a thiophene (T) or a benzodithiophene (BDT), and further symmetrically substituted by 2-methoxylethoxyl (EG), both through the bay-region. These two NDI dimers exhibit broad absorption in the visible region of 300–650 (800) nm and display a HOMO/LUMO energy level of −5.88 eV/−3.80 eV and −5.46 eV/−3.78 eV, respectively. When PBDTTT-C-T was chosen as the polymer donor, Bis-NDI-T-EG and Bis-NDI-BDT-EG exhibited efficiencies of 1.31% and 1.24%, respectively.     

Characterization and Electrochemical Performance of ZnO Modified LiFePO4/C Cathode Materials for Lithium-ion Batteries

To improve the electrical conductivity of LiFePO4 cathode materials, the ZnO modified LiFePO4/C cathode materials are synthesized by a two-step process including solid state synthesis method and precipitation method. The structures and compositions of ZnO modified LiFePO4/C cathode materials are characterized and analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy, which indicates that the existence of ZnOhas little or no effect on the crystal structure, particles size and morphology of LiFePO4. The electrochemical performances are also characterized and analyzed with charge-discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the existence of ZnO improves the specific capability and lithium ion diffusion rate of LiFePO4 cathode materials and reduces the charge transfer resistance of cell, and the one with 3 wt% ZnO exhibits the best electrochemical performance.     

Synthesis,crystal structures,and catalytic oxidation properties of oxidovanadium(V) complexes with Schiff base ligands

Two new Schiff base ligands 2-chloro-N′-(5-fluoro-2-hydroxybenzylidene)benzohydrazide (H₂L^a) and 4-fluoro-2-{[2-(2-hydroxyethylamino)ethylimino]methyl}phenol (HL^b) were synthesized and characterized. Their respective oxidovanadium complexes, [VOL^a(OMe)(MeOH)]·MeOH (1) and [VO(μ-O)L^b]₂ (2), were synthesized and characterized by spectroscopy and single-crystal X-ray diffraction. The coordination sphere of each V atom is octahedral. Both complexes showed selective heterogeneous catalytic properties with 74–98 % conversion, for the oxidation of cyclohexene, cyclopentene, and benzyl alcohol using H₂O₂ as primary oxidant.     

Cylindrical effects in weakly nonlinear Rayleigh Taylor instability

The classical Rayleigh–Taylor instability(RTI)at the interface between two variable density fluids in the cylindrical geometry is explicitly investigated by the formal perturbation method up to the second order.Two styles of RTI,convergent(i.e.,gravity pointing inward)and divergent(i.e.,gravity pointing outwards)configurations,compared with RTI in Cartesian geometry,are taken into account.Our explicit results show that the interface function in the cylindrical geometry consists of two parts:oscillatory part similar to the result of the Cartesian geometry,and non-oscillatory one contributing nothing to the result of the Cartesian geometry.The velocity resulting only from the non-oscillatory term is followed with interest in this paper.It is found that both the convergent and the divergent configurations have the same zeroth-order velocity,whose magnitude increases with the Atwood number,while decreases with the initial radius of the interface or mode number.The occurrence of non-oscillation terms is an essential character of the RTI in the cylindrical geometry different from Cartesian one.     

基于FlowStar软件的栅格舵气动特性模拟

栅格舵是由外部边框和内部若干薄栅格组成的一种新型气动力面和控制面。由于其具有尺寸小、重量轻和易折叠等结构特点,以及升力特性好、铰链力矩小和压心位置随马赫数变化小等良好的气动性能,越来越受到重视和广泛应用。但是,由于栅格舵是特殊的蜂窝结构,常规的结构网格生成困难,并且栅格壁之间存在严重的波系干扰,流场结构复杂,给数值模拟带来了挑战。本文针对栅格舵流场结构复杂、网格生成和数值模拟难度大的难题,采用国家数值风洞工程(NNW)项目团队自主开发的非结构混合网格流场软件FlowStar,对栅格舵气动特性开展了数值模拟研究。首先,通过十字栅格舵全弹标模外形,验证了数值模拟方法的可靠性。然后,通过研究栅格不同形状对栅格舵气动特性的影响规律,给出了栅格舵设计时尽量采用气动性能较高和结构强度较好的菱形栅格,以及尽可能少用或不用正三角形栅格的指导建议。最后,开展了类Space X迎风面局部弧形栅格舵气动特性模拟研究,结果表明,弧形后掠可以有效降低阻力,提高升阻比;攻角为0°时,与平直栅格舵相比,弧形后掠栅格舵在亚跨声速阶段,阻力降低约8%,马赫数大于2时,阻力降低约15%。本文研究可为栅格舵的设计提供参考和指导。     

一种面向激波噪声计算的加权优化紧致格式及非线性效应分析

在超声速流动中, 激波与湍流结构的相互作用会产生高强度的激波噪声. 激波噪声的高保真计算要求激波捕捉格式具有高阶精度、低耗散和低色散特性, 同时还要尽可能地减弱格式的非线性效应. 现有的六阶精度迎风/对称混合型加权非线性紧致格式CCSSR-HW-6在基于对称模板构造网格中心处的数值通量时引入了两级加权, 且两级加权都需要构造非线性的权系数, 因而非线性效应较强. 本文以修正波数的误差积分函数为优化目标函数, 优化了CCSSR-HW-6格式的非线性特性, 建立了加权优化紧致格式WOCS. 精度验证表明WOCS格式的精度高于5阶. 谱特性分析表明, 与原方法相比, WOCS格式的耗散误差和非线性效应显著降低. 典型激波噪声问题数值实验表明: WOCS格式不仅提高了对高频波的分辨能力, 而且显著地消除了数值解中因格式的非线性效应所导致的非物理振荡.      

分光光度法测定黔江肾豆中Fe含量

采用邻菲罗啉分光光度法测定肾豆中铁含量,方法简单、快捷、准确。样品经过湿法V（HCl04）＋V（HN03）=4＋1消解预处理,探讨了最佳波长、温度、酸度、显色剂用量以及显色时间等对测定结果的影响,在最佳实验条件下测定肾豆中铁元素含量,为肾豆进一步的研究和利用提供一定的参考数据。     

Turning the V site in V@2D-BC3N2 complex to high curvature state for efficient CO2 electroreduction to hydrocarbons

Hydrocarbons are promising products for CO₂ electroreduction (CRR) while is impeded by the low selectivity. Turning the curvature of the active site is an effective strategy to change the adsorption properties and further regulate the product distribution and reactivity. Herein, we have designed a novel V single atom catalyst (SAC) based on rolled two-dimensional (2D) BC₃N₂ substrate with different curvatures. The results have demonstrated that increased curvature can enhance the adsorption strength of CRR intermediates, which follows different mechanisms for systems with low and high curvature. This character eventually leads to the deviation away from the scaling line between E_ad[CO]∼E_ad[COOH] based on transition metals for V@2D-BC₃N₂ systems. 3-3 system is screened as the optimal candidate for hydrocarbons production due to the enhanced binding ability of adsorbates, which can increase the reactivity for hydrocarbons production and hinder the production of H₂ and HCOOH simultaneously.     

Accelerated discovery of novel high-performance zinc-ion battery cathode materials by combining high-throughput screening and experiments

Aqueous zinc ion batteries (AZIBs) have attracted much attention in recent years due to their high safety, low cost, and decent electrochemical performance. However, the traditional electrodes development process requires tedious synthesis and testing procedures, which reduces the efficiency of developing high-performance battery devices. Here, we proposed a high-throughput screening strategy based on first-principles calculations to aid the experimental development of high-performance spinel cathode materials for AZIBs. We obtained 14 spinel materials from 12,047 Mn/Zn-O based materials by examining their structures and whether they satisfy the basic properties of electrodes. Then their band structures and density of states, open circuit voltage and volume expansion rate, ionic diffusion coefficient and energy barrier were further evaluated by first-principles calculations, resulting in five potential candidates. One of the promising candidates identified, Mg₂MnO₄, was experimentally synthesized, characterized and integrated into an AZIB based cell to verify its performance as a cathode. The Mg₂MnO₄ cathode exhibits excellent cycling stability, which is consistent with the theoretically predicted low volume expansion. Moreover, at high current density, the Mg₂MnO₄ cathode still exhibits high reversible capacity and excellent rate performance, indicating that it is an excellent cathode material for AZIBs. Our work provides a new approach to accelerate the development of high-performance cathodes for AZIBs and other ion batteries.     

Thermosensitive injectable hydrogel loaded with hypoxia-induced exosomes maintains chondrocyte phenotype through NDRG3-mediated hypoxic response

Current clinical treatments cannot effectively delay the progression of osteoarthritis (OA). Consequently, joint replacement surgery is required for late-stage OA when patients cannot tolerate pain and joint dysfunction. Therefore, the prevention of OA progression in the early and middle stages is an urgent clinical problem. In a previous study, we demonstrated that NDRG3-mediated hypoxic response might be closely related to the development and progression of OA. In this study, an injectable thermosensitive hydrogel was established by cross-linking Pluronic F-127 and hyaluronic acid (HA) for the sustained release of hypoxia-induced exosomes (HExos) derived from adipose-derived mesenchymal stem cells. We demonstrated that for OA at the early and middle stages, the HExos-loaded HP hydrogel could maintain the chondrocyte phenotype by enhancing chondrocyte autophagy, reducing chondrocyte apoptosis, and promoting chondrocyte activity and proliferation through the NDRG3-mediated hypoxic response. This novel composite hydrogel, which could activate the NDRG3-mediated hypoxic response, may provide new ideas and a theoretical basis for the treatment of early- and mid-stage OA.