Total Synthesis of Lajollamycin B

The first total synthesis of lajollamycin B, a structurally novel nitro-tetraene spiro-β-lactone/γ-lactone antibiotic, is described. The convergent synthesis involves the construction of the C8′–C11′ nitrodienylstannane and its coupling with the segment prepared from the C1′–C7′ ω-iodoheptadienoic acid and the right-hand heterocyclic fragment, which has been utilized for our previous syntheses of oxazolomycin A. The revision of the geometry of the terminal Δ^{10′, 11′}-double bond from E to Z is also described for the structure of natural lajollamycin B.     

等离子体电极普克尔盒研究进展

等离子体电极普克尔盒(PEPC)用作多程放大控制、自激振荡抑制以及反激光隔离,是大型高功率固体激光器的核心器件。本文从高功率固体激光器的发展对光开关提出的要求出发,系统地综述了等离子体电极普克尔盒的性能特点以及研究进展。重点介绍了中国工程物理研究院激光聚变研究中心近年来在PEPC研究方面所取得的进展,包括单脉冲驱动的组合口径PEPC、低损耗PEPC以及重复频率运转的PEPC。     

基于XPS对硫铁矿去除SeO2-3的机理研究

硒是动植物及人体生长必需的十五种微量元素之一，具有清除体内自由基、抗氧化、增强免疫力等功能，但其安全剂量的范围却很窄。利用扫描电子显微镜（SEM）和X射线衍射仪（XRD）对湿法球磨制备的硫铁矿形貌进行了表征。SEM观测发现加乙醇助磨后的硫铁矿为粒径大小较均匀的球形颗粒团聚体，粒径范围在17～200 nm之间，平均粒径138 nm。XRD衍射图谱中的特征峰与FeS₂衍射图谱中各峰位置基本一致，因此判定硫铁矿中主要化学组分为FeS₂，且图谱中基本没有杂峰，表明制备过程中并未混入杂质，样品纯度较高。实验结果表明，该法制备的硫铁矿具有颗粒粒径小、比表面积大、反应活性高等优点。研究中利用X射线光电子能谱仪（XPS）对硫铁矿去除水体中SeO2-₃的机理进行了研究。研究结果表明, （1）在较为广泛的实验pH范围（pH 2.2～11.5），硫铁矿均能有效去除水体中SeO2-₃，去除效率（除pH值7.8以外）均达到90%以上；（2）硫铁矿与SeO2-₃发生反应后，其主要组成元素的XPS特征峰结合能有所减小，表明硫铁矿表面发生了一定化学变化；（3）酸碱环境下硫铁矿去除SeO2-₃的机理不完全相同，酸性环境下，硫铁矿对SeO2-₃的去除是单纯的氧化还原过程，即硫铁矿中被酸活化的S2-₂将SeO2-₃还原为单质Se(0)，并且酸性越强，SeO2-₃去除效果越好；碱性环境下，SeO2-₃的去除过程中氧化还原与络合反应并存，硫铁矿表面有络合态Fe(OH)SeO₃和单质Se(0)两种存在形态，且碱性越强，络合态Fe(OH)SeO₃含量越高。以上研究结果为硫铁矿去除固定水体和土壤中以SeO2-₃为代表的可变价金属阴离子提供重要理论依据和应用基础。     

Hybrid numerical method for wall-resolved large-eddy simulations of compressible wall-bounded turbulence

Acta Mechanica Sinica - Bogies are responsible for a significant amount of aerodynamic resistance and noise, both of which negatively affect high-speed train performance and passenger comfort. In...     

Origins of Boosted Charge Storage on Heteroatom-Doped Carbons

Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance.     

Rationally Design of Near Infrared Light Responsive Micro‐Photoelectrodes for In Vivo Sensing of Neurotransmitter Molecules in Mouse Brain†

The accurate quantification of neurotransmitter molecules is an indispensable means to reveal the physiological mechanisms of neuro movement in molecular level. However, existing detection strategies cannot fully meet practical needs, and the on‐site and in vivo detection of neurotransmitters in brain remains a great challenge. Here, we report the development of a near infrared light responsive photoelectrochemical (PEC) detection method for in vivo quantification of neurotransmitter dopamine in mouse brain. Under guidance of density function theory calculations, a combination strategy of non‐metal cation doping and defect engineering is introduced to rationally design the micro‐photoelectrodes with excellent biocompatibility and stability and implements the in vivo PEC detection of dopamine in mouse brain. It opens up a new way for the accurate in vivo detection of biomolecules and allows researchers to make novel inquiries for long‐standing questions in a new way.     

Topography guiding the accelerated and persistently directional cell migration induced by vaccinia virus

The rapid transmission of vaccinia virus(VACV)in vivo is thought to be closely related to the cell migration induced by it.Cell migration involved in dynamic changes of cell-substrate adhesion and actin cytoskeleton organization,which can influence by the micro/nano-scale topographic structures that cells are naturally exposed to via contact guidance.However,migration behaviors of VACV-infected cells exposed to topographic cues are still unknown.Herein,we designed an open chip with microgrooved poly(dimethyl siloxane)(PDMS)substrate to explore the topography roles in VACV-induced cell migration.Differed from the random cell migration observed in traditional scratch assay on planar substrate,VACV-infected cells had a tendency to persistently migrate along the axis parallel to microgroove with increased velocity.Moreover,infected cells exhibited a dominant elongated protrusion aligned to the micro-grating axis compare to the shorter lamella extended in any direction on smooth substrate.Interestingly,the Golgi complex preferred to relocate behind the nucleus confined within the micro-grating axis in majority of infected migratory cells.The directional polarization of cells embodied in protrusion formation and Golgi reorientation was responsible for the directionally persistent migration behaviors induced by VACV on microgrooved substrate.Infected cells response to substrate topography,causing the actin-filled stretched protrusion containing numerous virions and accelerated movement is likely to facilitate direct and rapid spread of VACV.This work opens a window for us to understand the migration behaviors of infected cells in vivo,and also provides a cue for revealing the relationship between virus-induced cell migration and virus rapid spread.     

玻色化方法在超对称可积系统的应用

利用玻色化方法可以避免超对称可积系统中反对易费米场带来的计算困难. 本文以N=1超对称mKdVB系统为例, 利用玻色化方法, 将其转化为只有玻色场的耦合系统. 应用标准的WTC方法, 证明了该耦合系统具有Painlevé性质. 运用Painlevé截断方法, 可以得到玻色化后超对称mKdVB系统的非局域对称. 为了求解与非局域对称相关的Lie第一性原理, 引入新的场将玻色化后系统拓展为更大的系统. 通过引入新的场, 该非局域对称局域化为Lie点对称. 因此, 可以利用Lie点对称约化方法研究拓展后的系统, 得到超对称mKdVB系统的孤子与其他孤波相互作用解.     

A reconfigurable terahertz polarization converter based on metal–graphene hybrid metasurface

A metal-graphene hybrid metasurface polarization converter is designed in this Letter.The unit cell of the hybrid metasurface is composed of a butterfly-shaped structure whose branches are connected by multi-layer graphene sheets.The proposed device can be reconfigured from linear-to-circular polarization to cross-polarization by changing the Fermi energy of graphene.The simulation results show that for three-layer graphene,the device acts as a linear-to-circular polarization converter when EF=0 eV and switches to a cross-polarization converter when EF=0.5 eV.Compared with single-layer graphene,the device with three-layer graphene can maintain the cross-polarization conversion performance under low Fermi energy.Furthermore,two equivalent circuits in the x and y directions are developed to understand the working mechanism of the device.     

NO分子宏观气体热力学性质的理论研究

采用量子统计系综理论,研究了基态NO分子宏观气体摩尔熵、摩尔内能、摩尔热容等热力学性质.首先应用课题组前期建立的变分代数法(variational algebraic method, VAM)计算获得了基态NO分子的完全振动能级,得到的VAM振动能级作为振动部分,结合欧拉-麦克劳林渐进展开公式的转动贡献,应用于经典的热力学与统计物理公式中,从而计算得到了1000-5000 K温度范围内NO宏观气体的摩尔内能、摩尔熵和摩尔热容.将不同方法计算得到的摩尔热容结果分别与实验值进行比较,结果表明基于VAM完全振动能级获得的结果优于其他方法获得的理论结果.振动部分采用谐振子模型对无限能级求和计算热力学性质的方法有一定的局限性,应当使用有限的完全振动能级进行统计求和.