超声波在废橡胶再生中应用的最新进展

全世界每年产生大量废旧橡胶，它们需要很长时间才能降解，这既污染环境，又浪费资源，解决此问题的唯一方法是再生利用。在众多再生方法中，新近出现的超声波脱硫再生法，被认为是最有希望的方法，本文详细地介绍了这方面的最新进展情况。     

Simultaneous determination of sulfite, sulfate, and hydroxymethanesulfonate in atmospheric waters by ion-pair HPLC technique

A reversed-phase ion-pair HPLC with indirect photometric detection for the simultaneous determination of sulfite, sulfate, hydroxymethanesulfonate (HMS), and other inorganic anions in atmospheric water has been developed. Separations were accomplished in less than 10 min in a cetylpyridinium-coated C₁₈ column with 0.5 mM potassium hydrogen phthalate-0.015% triethanolamine-3% methanol at pH 7.9 as mobile phase. Quantitation was carried out by the peak area method, with detection limits in the pmol range. UV light absorption responses were linear over a wide concentration range from several hundred μmoles to the detection limits of each anion. The application of the method provides a rapid and efficient technique for the quantitative determination of sulfur and other inorganic species in atmospheric liquids.     

石墨烯嵌锂的拉曼成像

锂离子电池由于具有高能量密度,高循环寿命,低自放电率的优势,成为当前使用最为广泛的储能器件。层状材料是极为常用的负极材料,其微观嵌锂行为的研究对提高电池的能量密度和循环寿命有重要意义。本工作发展了一种新的平板微电池结构,可用于研究锂离子在各类二维层状纳米材料中的嵌锂行为。我们用机械剥离的单片少层石墨烯为正极,热蒸镀的锂金属为负极,构成石墨烯电池,用恒电压放电的方法进行嵌锂测试。采用拉曼成像技术收集石墨烯G峰信号的空间分布,实现对锂的嵌入过程的显微观测。发现了锂在石墨烯中沿层间扩散迁移,以及石墨烯断层对锂扩散的阻碍作用。这些结果有助于理解放电时锂在石墨烯电极中扩散过程,并且这项研究开发的平板微电池结构可用于多种材料的电化学过程中的微观过程表征,同时可实现与光学、电学、电子显微学等多种表征手段的兼容,具有较好的应用前景。     

原位透射电镜研究正交相五氧化二铌纳米片的电化学储钠机制

由于正交相五氧化二铌(T-Nb₂O₅)为ReO₃型层状结构,锂、钠离子可以在其(001)平面快速脱嵌,而在[001]方向的传输一般较难。本研究通过原位透射电子显微镜(Transmission Electron Microscope,TEM)方法研究钠在T-Nb₂O₅纳米片(001)面内及[001]方向的钠离子电化学嵌入行为,发现由于纳米片晶体存在大量的位错和畴界,钠离子可通过这些缺陷穿越(001)面扩散,并进而在深层的(001)面内快速扩散。同时,本研究还发现刚合成的T-Nb₂O₅纳米片在[001]方向上存在调制结构,存在交替分布的压应变和张应变区域,而钠离子的嵌入可以调节这些应变分布。     

Multiple conformations of benzil in resorcinarene-based supramolecular host matrixes

Six supramolecular complexes incorporating benzil as a guest, CMCR*bipy*benzil (alpha) 1 (CMCR = C-methylcalix[4]resorcinarene), CMCR*bipy*benzil (beta) 2, CMCR*2bpe*benzil*ethanol 3 (bpe = trans-1,4-bis(pyridyl)ethylene), CMCR*2bpe*benzil*2H2O 4, CMCR.2bpeh*benzil*ethanol 5 (bpeh = bis-(1-pyridin-4-yl-ethylidene)-hydrazine), and CECR*2bpe.benzil 6 (CECR = C-ethylcalix[4]resorcinarene), have been synthesized by hydrothermal and conventional methods and characterized by X-ray diffraction. Resorcinarene adopts a boat conformation in 1-4 and a bowl conformation in 5 and 6. Compounds 1-4 show a brick-wall-like framework, in which two benzil molecules are incorporated. For 5, bpeh spacers link CMCR molecules to give a one-dimensional wavelike polymer in which one benzil guest is embedded within the polymer cavity. Complex 6 forms a carcerand-like capsule in which two benzil guests are encapsulated. The O=C-C=O torsion angles vary from 91.8 to 139.3 degrees and correlate with the length of the central C-C bond. The benzil concentration, which is approximately 6.2 mol/L in the neat crystals, varies between 1.01 and 1.51 mol/L in the structures studied, corresponding to a 6-fold dilution. The benzil molecules are disordered in the larger cavities of 4 and 5. The two benzoyl fragments are almost perpendicular in 3, which has the next largest cavity size when solvent volume is excluded, whereas a nearly trans-coplanar conformation occurs for the cavity with the smallest volume in 6.     

Controlled precipitation of solubilized carbon nanotubes by delamination of DNA

Polyaromatic molecules, such as rhodamine 6G and methylene blue, were found capable of precipitating DNA-solubilized single-walled carbon nanotubes from solution through a competitive binding mechanism whereby DNA is displaced from the nanotube surface, allowing the nanotubes to rebundle. This delamination of DNA also occurred when complementary oligonucleotides were used to hybridize specifically to the DNA coating on the nanotubes. These findings were expanded to include techniques for controlled desolubilization and to provide additional elucidation into the interaction of SWNTs and noncovalent solubilizing agents.     

Copper‐Catalyzed Aerobic Oxidative Cyclization Cascade to Construct Bridged Skeletons: Total Synthesis of (−)‐Suaveoline

Based on the discovery of copper‐catalyzed cyclopropanol ring‐opening addition to iminium ions, an unprecedented catalytic aerobic C?H oxidation/cyclopropanol cyclization cascade using CuCl₂ as the multifunctional catalyst and air as the oxidant was developed to construct the azabicyclo[3.3.1]nonane skeleton, which is widespread in natural products and medicines. Using this method, concise asymmetric total synthesis of the indole alkaloid (?)‐suaveoline was achieved. This study not only provides an efficient, low‐cost, and environmentally benign method for constructing such bridged frameworks, but also enriches the realm of cyclopropanol chemistry and C?H functionalization.     

Freestanding Carbon Nanotube Film for Flexible Straplike Lithium/Sulfur Batteries

Flexible lithium/sulfur (Li/S) batteries are promising to meet the emerging power demand for flexible electronic devices. The key challenge for a flexible Li/S battery is to design a cathode with excellent electrochemical performance and mechanical flexibility. In this work, a flexible strap-like Li/S battery based on a S@carbon nanotube/Pt@carbon nanotube hybrid film cathode was designed. It delivers a specific capacity of 1145 mAh g⁻¹ at the first cycle and retains a specific capacity of 822 mAh g⁻¹ after 100 cycles. Moreover, the flexible Li/S battery retains stabile specific capacity and Coulombic efficiency even under severe bending conditions. As a demonstration of practical applications, an LED array is shown stably powered by the flexible Li/S battery under flattened and bent states. We also use the strap-like flexible Li/S battery as a real strap for a watch, which at the same time provides a reliable power supply to the watch.     

Synthesis,Crystal Structure,and Electrochemical Properties of a Simple Magnesium Electrolyte for Magnesium/Sulfur Batteries

Most simple magnesium salts tend to passivate the Mg metal surface too quickly to function as electrolytes for Mg batteries. In the present work, an electroactive salt [Mg(THF)₆][AlCl₄]₂ was synthesized and structurally characterized. The Mg electrolyte based on this simple mononuclear salt showed a high Mg cycling efficiency, good anodic stability (2.5 V vs. Mg), and high ionic conductivity (8.5 mS cm^?1). Magnesium/sulfur cells employing the as‐prepared electrolyte exhibited good cycling performance over 20 cycles in the range of 0.3–2.6 V, thus indicating an electrochemically reversible conversion of S to MgS without severe passivation of the Mg metal electrode surface.     

三维氮掺杂碳纳米带的制备及其在锂硫电池中的应用

锂硫电池凭借其高的理论能量密度（2600 W·h·kg^-1）、丰富廉价的材料来源、且对环境友好等优势,而引起了人们的广泛关注.然而,锂硫电池活性物质导电性差、多硫化物易溶于有机电解液等问题所导致的硫正极倍率性能和循环稳定性差,仍然是困扰锂硫电池发展的挑战性难题.我们设计并以廉价易得的小分子化合物对苯二酚和甲醛为原料,通过缩聚反应、与氧化石墨烯原位复合、高温氮化制备了一类新型氮掺杂的碳纳米带固硫载体材料（NCNB-NG）.通过NCNB-NG复合纳米硫进一步得到的碳-硫复合正极材料（S@NCNB-NG）表现出更优异的倍率性能和循环稳定性,这主要得益于该碳质载体独特的微结构以及改善的导电性.