A bio‐safe cyclophosphazene derivative flame retardant for polylactic acid composites: Flammability and cytotoxicity

An efficient bio‐safe cyclophosphazene flame retardant, 1,5,9,13,16,20‐Hexaoxa‐7,14,21‐triaza‐6λ⁴,8λ⁴,5λ⁴‐triphosphatrispiro[5.1.5.1.5.1]heneicosa‐6,8(14),15(21)‐triene (HCPO), was synthesized, and then was incorporated into polylactic acid (PLA) to improve the fire safety. The chemical structure of HCPO was confirmed by Fourier‐transformed infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. The thermal stability of the compound was characterized by thermogravimetric (TG) analyzer. The cytotoxic effects of HCPO to cells were evaluated. Fire behavior and thermal stability of PLA composites were investigated by vertical burning, limiting oxygen index (LOI), TG analysis, and cone calorimeter. The morphology of residual charring was observed by scanning electron microscope. The results showed HCPO was bio‐safe, and highly effective to enhance the flame retardancy of PLA composites. The LOI value was increased from 18.4 to 27.5 and UL‐94 grade achieved V‐0 for the PLA composite containing only 2% HCPO and 2% pentaerythrotol. It was demonstrated that intermolecular cross‐linking reaction between pentaerythrotol and HCPO in high temperature range could accelerate the formation of compact char layers.     

泡沫镍负载Fe2O3@Ni3S2纳米线网状结构电极的制备及其电催化析氧性能

通过两步水热法制备泡沫镍(NF)负载Fe_2O_3纳米粒子@Ni_3S_2纳米线网状结构电极(Fe_2O_3@Ni_3S_2/NF)。运用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、N_2吸附-脱附测试等方法对电极材料的物相和微观结构特征等进行了表征。水热条件下原位表面化学刻蚀生成的Ni_3S_2纳米线与三维多孔NF基体间拥有强结合力和低界面电阻,Fe_2O_3粒子均匀分布在纳米线的表面。在1 mol·L~(-1)的KOH溶液中,运用线性扫描伏安测试(LSV)、计时电位法、电化学交流阻抗测试(EIS)等对电极的电催化析氧(OER)性能进行了测试。结果表明:在100 mA·cm~(-2)的超高电流密度下,Fe_2O_3@Ni_3S_2/NF电极的OER过电势仅为223 mV,比Ni_3S_2/NF材料的过电势降低了285 mV;经过10 h计时电位测试,性能保持率高达80%。     

“Solid-Liquid” Vitrimers Based on Dynamic Boronic Ester Networks

The "solid-liquid" behavior of vitrimers have not been systematically investigated. Herein, a series of "solid-liquid" vitrimers bearing varying contents of dynamic boronic ester bonds were synthesized via thiol-ene click reactions. These vitrimers allow for flexibile modulation of their network structures and thus show a range of intriguing properties including high stretchability, flexible transition from elasticity to plasticity, strong strain rate dependence, and solid-liquid performance. The dynamic association rate of boronic ester bonds within these vitrimers could be apparently accelerated via increasing the content of boronic ester, which could be used to shape-program the flat vitrimer films into various complex 3 D structures just with external force. Materials with such versatile dynamic behavior may open up a range of new applications.     

透明质酸纳米材料在荧光/光声成像和光疗中的应用

荧光/光声成像和光疗技术的生物医学应用引起了人们越来越多的关注, 然而很多荧光/光声造影剂存在生物相容性较差, 缺乏肿瘤靶向性, 信噪比较低, 功能单一等共性问题, 严重限制其诊疗应用. 透明质酸具有优异的生物相容性和主动肿瘤靶向性, 可被透明质酸酶降解, 并且易于化学修饰和实现多种超分子弱相互作用力协同工作. 因此, 人们将透明质酸与荧光/光声造影剂结合制备纳米材料, 使其在细胞乃至活体的标记性能和治疗效果获得了很大的改善. 本文综述了将两类物质结合制备纳米材料的方法, 着重阐述了纳米材料的结构与性能关系, 为其未来设计和开发提供了指导, 最后对存在的主要问题以及未来的重要研究方向进行了分析和展望.     

Preparation and electroluminescent application of iridium(III) complexes containing sulfur-containing phenylpyridazine ligands

Transition Metal Chemistry - Four iridium(III) complexes (1–4) with sulfur-containing phenylpyridazine ligands were successfully synthesized and characterized. The structure of complex 3 was...     

Large-area periodic lead halide perovskite nanostructures for lenticular printing laser displays

Lenticular printing technique provides a promising way to realize stereoscopic displays,especially,when microscopic optical structures are integrated into light-emitting materials/devices.Here,we fabricated large-area periodic structures with a spatial resolution at a wavelength scale from hybrid perovskite materials via a space-confined solution growth method.It takes advantages of both high refractive index contrast and high luminescence brightness,which allows the optical modulation on not only the reflection of illumination,but also the light emission from hybrid perovskites.The distributed feedback within these periodic structures significantly improves the degree of polarization and directionality of laser actions while their threshold is also reduced.These findings enable us to present a prototype of lenticular printing laser displays that vary emission colors at different view angles,which may find applications in creating high-resolution and high-contrast holographical images.     

The Analysis of Phenolic Compounds in Walnut Husk and Pellicle by UPLC-Q-Orbitrap HRMS and HPLC

Husk and pellicle as the agri-food waste in the walnut-product industry are in soaring demand because of their rich polyphenol content. This study investigated the differential compounds related to walnut polyphenol between husk and pellicle during fruit development stage. By using ultra-high performance liquid chromatography-quadrupole-orbitrap (UHPLC-Q-Orbitrap), a total of 110 bioactive components, including hydrolysable tannins, flavonoids, phenolic acids and quinones, were tentatively identified, 33 of which were different between husk and pellicle. The trend of dynamic content of 16 polyphenols was clarified during walnut development stage by high-performance liquid chromatography (HPLC). This is the first time to comprehensive identification of phenolic compounds in walnut husk and pellicle, and our results indicated that the pellicle is a rich resource of polyphenols. The dynamic trend of some polyphenols was consistent with total phenols. The comprehensive characterization of walnut polyphenol and quantification of main phenolic compounds will be beneficial for understanding the potential application value of walnut and for exploiting its metabolism pathway.     

Generation of Glycosyl Radicals from Glycosyl Sulfoxides and Its Use in the Synthesis of C‐linked Glycoconjugates

We here report glycosyl sulfoxides appended with an aryl iodide moiety as readily available, air and moisture stable precursors to glycosyl radicals. These glycosyl sulfoxides could be converted to glycosyl radicals by way of a rapid and efficient intramolecular radical substitution event. The use of this type of precursors enabled the synthesis of various complex C‐linked glycoconjugates under mild conditions. This reaction could be performed in aqueous media and is amenable to the synthesis of glycopeptidomimetics and carbohydrate‐DNA conjugates.     

Antioxidative Cassane Diterpenoids from the Seeds of Caesalpinia minax

Five new cassane diterpenoids, caesalmins I–M ( 1 – 5 ), and 23 known analogs were isolated from the seeds of Caesalpinia minax. Their structures were elucidated by spectroscopic methods and comparison with reported data. The antioxidant properties of 1 – 28 were determined by the method of oxygen radical absorbance capacity of fluorescein (ORAC‐FL), and 14 compounds exhibited good antioxidant activities with ORAC‐FL values of 2.24–4.89 Trolox equivalents. The structure? activity relationship of the active compounds was also discussed.