A multifunctional separator with Mg(OH)2 nanoflake coatings for safe lithium-metal batteries

Dendrite growth and thermal runaway induce serious safety hazards,impeding the practical applications of lithium metal batteries(LMBs).Although extensive advances have been attained in terms of LMB safety,most work only focus on a single aspect at a time.This paper reports a multifunctional separator coated by Mg(OH)2 nanoflakes with various excellent properties including electrolyte wettability,ionic conductivity,Li+ transference number,puncture strength,thermal stability and flame retardance.When used in LMBs,the Mg(OH)2 nanoflake coatings enable uniform Li+ distributing,which makes it homogeneous to deposit lithium,realizing effective dendrite suppression and less volume expansion.Meanwhile,Mg(OH)2 coatings can ensure LMBs are in normal conditions without thermal runaway until 140 ℃.A part of lithium can be converted into Li+ ions by Mg(OH)2 during repeated charge/discharge cycles,not only reducing the risk of separator damage and consequent short circuit,but also replenishing the capacity loss of LMBs.The Mg(OH)2 nanoflakes can coat on all kinds of commercial separators to improve their performances,which offers a facile but effective strategy for fabricating multifunctional separators and a comprehensive insight into enhancing LMB safety.     

2,2-双(4-氯-2-氟苄基)丙二酸二乙酯的晶体结构和密度泛函理论研究

标题化合物是一个重要的精细化工中间体,可用于制备嘧啶类、吡唑类等产品。本文利用红外光谱(IR)、质谱(MS)、核磁共振氢谱(¹H NMR)、核磁共振碳谱(¹³C NMR)和X-射线单晶衍射对此化合物进行了表征,并在B3LYP/6-311G(d, p)模式下使用密度泛函理论(DFT)计算了此化合物的最稳定晶体结构以及最高占有分子轨道(HOMO)和最低占有分子轨道(LUMO)能量。结果表明,通过DFT优化的分子结构与X-射线单晶衍射确定的晶体结构基本一致,该化合物属于单斜方P2(1)/n空间群,晶胞参数为:a=1.563 9(10) nm, b=0.778 6(4) nm, c=1.838 2(10) nm,Z=4, ρ_c＝1.345 g·cm^-3,R=0.047 7,R_w=0.138 7。     

A multi-directional controllable multi-scroll conservative chaos generator:Modelling,analysis,and FPGA implementation

Combing with the generalized Hamiltonian system theory,by introducing a special form of sinusoidal function,a class of n-dimensional(n=1,2,3)controllable multi-scroll conservative chaos with complicated dynamics is constructed.The dynamics characteristics including bifurcation behavior and coexistence of the system are analyzed in detail,the latter reveals abundant coexisting flows.Furthermore,the proposed system passes the NIST tests and has been implemented physically by FPGA.Compared to the multi-scroll dissipative chaos,the experimental portraits of the proposed system show better ergodicity,which have potential application value in secure communication and image encryption.     

Lamb波频域逆散射全聚焦成像方法研究

Lamb波因其传播距离远、衰减小常被用于板状结构的无损检测中,在基于Lamb波损伤检测的诸多成像技术中,全聚焦方法(Total Focus Method,TFM)方法因其成像分辨率高、信噪比高而受青睐。然而Lamb波的频散效应导致时域延时量不能被准确计算,进而影响传统TFM方法对损伤定位及成像的精度;此外,既有的TFM方法仅以回波幅值作为成像指标,忽略了Lamb波与损伤的相互作用,故而不能通过损伤表面的物理参数增强成像质量。针对这两个问题,本文首先在时域TFM基础上发展了频域TFM,在计算中纳入频散关系以规避频散的影响;其次以包含明确的损伤特征参数--反射率为成像指标,结合频域TFM方法建立损伤逆散射模型,以实现对损伤的准确成像。仿真和实验结果表明:频域逆散射TFM成像方法能够实现对铝板结构中的损伤检测,在工程实践中具有应用价值。     

4′-苯基-2,2′∶6′,2″-三联吡啶镍配合物的合成与晶体结构

运用水热法合成了1个新的配合物[Ni(Phtpy)2](CH3COO)2(化合物1),(Phtpy=4′-苯基-2,2′∶6′,2″-三联吡啶),并通过X-射线单晶衍射方法确定了该化合物的晶体结构.结构分析表明化合物1属于三斜晶系,P-1空间群,晶胞参数a=0.905 60(8)nm,b=1.103 07(9)nm,c=2.020 14(15)nm,α=94.383 0(10)°,β=100.983 0(10)°,γ=106.312 0(10)°,V=1.883 1(3)nm3,Z=2,R1=0.087 2,wR2=0.183 1.配合物中存在3种氢键和多种π-π相互作用,使其成为一个3D配合物.     

三维锌基金属有机框架材料的合成及其晶体结构与热性能

以1,1'-双(二苯基膦)二茂铁氯化钯为催化剂,2,5-二溴苯甲醛和4-吡啶苯硼酸经"一锅法"反应合成了新化合物2,5-二(吡啶-4-基)苯甲醛(L)。以L和反式-4,4'-二苯乙烯二甲酸(H2SDA)为配体,与Zn(NO3)2·6H2O经溶剂热反应合成了一个四重穿插的三维金属有机框架材料[Zn2L(SDA)2]·2DMA(1),其结构和热性能经IR,元素分析,X-射线粉末衍射和TGA表征。1属四方晶系,P4(1)2(1)2空间群,晶胞参数a=17.452 0(9),b=17.452 0(9),c=18.360 6(14),V=5 592.1(6)3,Z=8,Dc=1.303 mg·cm-3,F(000)=2 268,μ=1.557 mm-1,R1=0.040 6,ωR2=0.114 7。1的结构中轮浆型双核Zn2(CO2)4单元被四个SDA分子连接形成一个二维层状结构,进而通过配体L桥连形成一个三维的网状结构,其热稳定性高达320℃。     

以gp41为靶标的小分子-多肽缀合物作为HIV-1融合抑制剂的设计、合成及活性初筛

芳基吡咯类小分子化合物NB-2衍生物(Noc或Npc)与衍生于C34中的靶标特异性多肽P26所形成的缀合物具有低纳摩尔水平的融合抑制活性.本文通过不同长度或不同柔性的连接臂将Noc或Npc与衍生于C34的靶标特异性多肽P27缀合,探讨了C34中a位残基I635和连接臂对缀合物活性的影响.人体免疫缺陷病毒1型(HIV-1)Env介导的细胞-细胞融合实验结果表明,多肽与小分子之间产生了强的协同作用.     

区间值度量空间中集值弱压缩映射的不动点

首先给出了区间值度量空间的定义以及区间值度量空间中收敛序列、Cauchy序列、区间数序列收敛等相关的基本概念,讨论了区间数序列具有的性质;然后给出并证明了区间值度量空间中集值弱压缩映射的不动点定理。     

Stereoselective interactions of chiral dipeptides on amylose based chiral stationary phases

Dipeptides are stereo-specifically involved in several biological functions that are challenging to separate enantiomerically. Elution order of enantiomers is an important issue in chiral chromatography. Amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase(CSP) is the best and most-widely-used CSP in chiral separations, but experimental data of enantiomeric separation of dipeptides on this CSP is lacking. Simulation studies were conducted to determine the order of elution and the chiral recognition mechanism of didpetides on this CSP. Results indicated that the docking energy of SR-enantiomers were higher than SS-antipodes. The range of docking energies for SR-enantiomers was -7.44 to -5.92 kcal/mol with CSP, but -7.15 to -5.87 kcal/mol for SS-stereoisomers. Therefore it is predicted that SS-enantiomer will elute first, followed by SR-antipode. Furthermore, hydrogen bondings, van der Waal’s interactions and electrostatic interactions were observed among SR- and SSenantiomers and chiral grooves of CSP. The number of hydrogen bonds was one in each enantiomer binding except S-Ala-R-Tyr, which contained two hydrogen bonds. No hydrogen bond was found in S-Ala-R-Trp, S-Leu-S-Trp, and S-Leu-S-Tyr dipeptides bindings. The chiral recognition mechanisms dictate different strengths of stereoselective bindings of the enantiomers on CSP.     

一种基于丹磺酰胺染料的高选择性汞(Ⅱ)离子荧光探针

对人类健康和社会环境而言,汞离子被认为是毒性最大的金属离子之一.本文设计、合成了一种新型基于丹磺酰胺染料的荧光探针,并研究了其对金属阳离子的识别性质.研究结果表明:该荧光探针在水溶液中,对汞离子具有高度的选择性和良好的灵敏度,且不受其它金属阳离子的干扰.该探针对汞离子的检测限可以达到2.1×10-8 mol/L.该探针极低的检测限和良好的水溶性表明其可用于活细胞中检测汞离子.生物成像实验证实该探针具有良好的细胞膜透性和生物相容性.