Markhacanasin C,cycloartane triterpenoid from the leaves of Markhamia stipulata var. canaense V.S. Dang

One new cycloartane triterpenoid, named markhacanasin C (1), together with three known triterpenoids, oleanolic acid (2), ursolic acid (3) and 6β,19α-dihydroxyursolic acid (4) were isolated by various chromatographic methods from the most cytotoxic fraction of the ethyl acetate extract of Markhamia stipulata var. canaense V.S. Dang leaves. Among them, 4 was reported for the first time from the genus Markhamia, while 2 and 3 were found for the first time from this species. Their structures were elucidated by IR, UV, HR-ESI-MS and NMR experiments. The cytotoxicity of isolated compounds (3 and 4) against three human cancer cell lines (HeLa, HepG2, and MCF-7) were evaluated. At the concentration of 100 μg/mL, 3 exhibited significant cytotoxic activity (86.36 ± 3.69%).     

Quantifying the Bonding Strength of Gold‐Chalcogen Bonds in Block Copolymer Systems

Gold‐chalcogen interactions are ubiquitous in gold biological and medicinal systems. Understanding the nature of these interactions can provide the basis for regulating their structures and functionalities, and a reasonable way to interpret the differences in various properties. However, the relative strength of gold‐chalcogen bonds remains controversial, and the conclusions of many related works are inconsistent. Thus, in this work, we successfully quantified the relative strength of Au‐X (X=S, Se, and Te from chalcogenide‐containing A‐B‐A type block copolymers) interactions at the single‐molecule level through single‐molecule force spectroscopy (SMFS) from a kinetic point of view and quantum chemical studies from a thermodynamic point of view. Both sets of results suggested that the strength of the Au‐X bonds decreases as Au‐Te>Au‐Se>Au‐S. Our findings unveiled the relative strength and nature of gold‐chalcogen interactions, which may help expand their application in electronics, catalysis, medicine and many other fields.     

具有多物理特性的X射线脉冲星导航地面验证系统

导航地面验证是X射线脉冲星导航研究必不可少的环节.针对导航算法验证需要真实连续的脉冲星信号的需求,同时避免X射线调制及探测难度大、成本高的问题,提出了一种基于可见光源的X射线脉冲星导航地面验证系统.该系统利用太阳系质心处脉冲星信号模型和航天器轨道信息,建立航天器处实时光子到达速率函数,再通过硬件系统转换成电压信号,利用该电压控制线性光源输出,最后经衰减、探测及甄别后获得航天器处的实时光子到达时间序列.该时间序列不仅具有导航脉冲星的轮廓特性、自转特性,还包括空间传播时间效应及宇宙X射线背景.本系统利用半物理装置对可见光进行调制及衰减,实时判断轨道各位置处导航脉冲星的可见性,实现X射线脉冲星信号传播过程的模拟.该系统提供四路可控输出信号,支持多种导航模式的验证.仿真系统的性能分析和功能验证结果表明,该系统具有良好的性能,可提供真实便捷的地面验证环境.     

微通道连续合成UiO-66系列改性MOF材料

采用内交叉指型微反应器连续合成UiO-66材料. 连续微通道法强化了物料之间的混合, 极大提高了生产效率, 晶体产物呈六面体形, 粒径在100 nm以下. 考察了温度、 总进料流量和停留时间等条件对合成过程及产物的影响. 结果表明, 升高温度有助于晶粒的生长; 随着总进料流量增大, 晶体粒径减小; 晶体的形成需要一定的停留时间, 超过该停留时间, 晶体粒径不再增大. 通过优化实验条件, 可以实现系列纳米级UiO-66-X材料(X=NH₂, NO₂, Br)的连续合成.     

Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Tracking membrane‐interacting molecules and visualizing their conformational dynamics are key to understanding their functions. It is, however, challenging to accurately probe the positions of a molecule relative to a membrane. Herein, a single‐molecule method, termed LipoFRET, is reported to assess interplay between molecules and liposomes. It takes advantage of FRET between a single fluorophore attached to a biomolecule and many quenchers in a liposome. This method was used to characterize interactions between α‐synuclein (α‐syn) and membranes. These results revealed that the N‐terminus of α‐syn inserts into the membrane and spontaneously transitions between different depths. In contrast, the C‐terminal tail of α‐syn is regulated by calcium ions and floats in solution in two conformations. LipoFRET is a powerful tool to investigate membrane‐interacting biomolecules with sub‐nanometer precision at the single‐molecule level.     

Synthesis and Characterization of a Pentiptycene‐Derived Dual Oligoparaphenylene Nanohoop

Structural designs combining oligoparaphenylene‐derived nanohoops with other functional organic building blocks should lead to novel molecular architectures with intriguing properties. Herein, we describe the synthesis of a pentiptycene‐derived chiral dual nanohoop molecule with key steps including ring expansion through dianthracene cycloreversion and transannular [4+2] cycloaddition across a 64‐membered macrocycle. The crystal structure of the nanohoop molecule displays an ordered packing pattern with long‐range channels in the solid state. Furthermore, nonracemizable enantiomers of the nanohoop were obtained through resolution and exhibited promising chiroptical properties.     

Unprecedented Eighteen‐Faceted BiOCl with a Ternary Facet Junction Boosting Cascade Charge Flow and Photo‐redox

Exposure of anisotropic crystal facets allows the directional transfer of photoexcited electrons (e^?) and holes (h⁺), for spatial charge separation. High‐index facets with a high density of low‐coordinated atoms always serve as reactive catalytic sites. However, preparation of multi‐facets or high‐index facets is highly challenging for layered bismuth‐based photocatalysts. Herein, we report the preparation of unprecedented eighteen‐faceted BiOCl with {001} top facets and {102} and {112} oblique facets via a hydrothermal process. Compared to the conventional BiOCl square plates with {001} top facets and {110} lateral facets, the eighteen‐faceted BiOCl has highly enhanced photocatalytic activity for H₂ evolution and hydroxyl radicals (^.OH) production. Theoretical calculations and photodeposition results disclose that the of eighteen‐faceted BiOCl has a well‐matched {001}/{102}/{112} ternary facet junction, which provides a cascade path for more efficient charge flow than the binary facet junction in BiOCl square plates.     

Ionic liquid-crystalline polymer-based quaternary phosphonium salt

A series of quaternary phosphonium salts based on ionic liquid-crystalline polymers which were synthesised by triphenylphosphine and brominated polysiloxanes containing cholesteryl mesogens. The chemical structures, liquid crystalline properties and antimicrobial performance of [ChP]Brs were investigated by a series of test methods. [ChP]Brs showed smectic A mesophase with a wide temperature range of liquid crystalline phase in the heating and cooling cycles. The glass transition temperature and clearing point temperature decreased with the increase of triphenylphosphine content. While the increase of phosphorus content lead to the increase of antibacterial properties of polymers. The liquid crystal polymer provides full spatial support for complete contact between phosphorus ions and bacteria, So that the quaternary phosphonium salt can be fully sterilised.     

POMs as Active Center for Sensitively Electrochemical Detection of Bisphenol A and Acetaminophen

A new type of electrochemical sensor based on multi-walled carbon nanotubes(MWCNTs), K2H4SiW11CuO39-6H2O(SiW11Cu) and gold nanoparticles(AuNPs) was prepared for the simultaneous detection of bisphenol A and acetaminophen. Differential pulse voltammetry(DPV), cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) were used for electrochemical characterization, and Fourier transfonn infrared spectroscopy(FTIR) was used to characterize the structure of polyoxometalates. Electrochemical experimental results show that the composite modified electrodes have good electrochemical activity as well as current response values of bisphenol A and acetaminophen when pH=7.0. At the same time, the modified electrode exhibits good stability and reproduction, and has good anti-interference ability to other substances. In practical application, the sensor obtained satisfactory results.     

The Optimal Uncertainty Relation

Employing the lattice theory on majorization, the universal quantum uncertainty relation for any number of observables and general measurement is investigated. It is found that 1) the least bounds of the universal uncertainty relations can only be properly defined in the lattice theory; 2) contrary to variance and entropy, the metric induced by the majorization lattice implies an intrinsic structure of the quantum uncertainty; and 3) the lattice theory correlates the optimization of uncertainty relation with the entanglement transformation under local quantum operation and classical communication. Interestingly, the optimality of the universal uncertainty relation found can be mimicked by the Lorenz curve, initially introduced in economics to measure the wealth concentration degree of a society.