磷酸钒锂/石墨烯复合正极材料的制备及表征

通过三聚氰胺甲醛树脂(MR)中的羟基与石墨烯氧化物(GO)中的羧基发生的沉淀反应来制备功能化的氧化石墨烯前驱体,然后利用溶胶-凝胶及高温热处理方法制备磷酸钒锂/石墨烯复合材料,利用此材料制备了电池电极,并对电极材料进行了结构和电化学表征。结果表明,所得磷酸钒锂为单斜晶系结构,石墨烯堆叠程度显著降低,也有效避免了磷酸钒锂颗粒的团聚,提高了材料的电化学性能。电池的充放电曲线极化较小,在3.0~4.3 V的区间内20 C倍率仍有86 mA·h/g的可逆容量。0.1 C循环100次后容量为119.7 mA·h/g,容量保持率94%。在3.0~4.8 V的高电压区间,10 C倍率下可逆容量80 mA·h/g,0.1 C循环100次后仍有145.6 mA·h/g的可逆容量。优异的循环和倍率性能以及较低的碳含量符合锂离子正极材料实用的要求。     

棕榈壳焦CO2气化过程中反应性及结构特性研究

850℃下,利用管式炉制备了不同转化率的棕榈壳CO₂气化焦,通过热重分析仪研究了气化焦的CO₂气化反应性,采用比表面积分析、拉曼光谱、X射线荧光光谱和扫描电镜-能谱等分析手段,考察了气化焦孔隙结构、碳组成、矿物元素含量与分布随转化率的变化。结果表明,在CO₂气化过程中,随着转化率的提高,棕榈壳气化焦固定碳的含量逐渐降低,有序化碳的相对含量为0.30~0.33,对气化过程起到一定的抑制作用;灰分含量逐渐增加,但气化反应指数R_s呈现先降低后升高的过程。转化率小于23%时,R_s与气化焦比表面积的变化趋势一致;23%< 转化率< 31%时,R_s基本不变;31%< 转化率< 68%时,比表面积随转化率线性增加,R_s取决于孔隙比表面积、矿物元素催化2个因素的协同作用,当转化率> 56 %时,该催化作用变得明显,同时碳的有序化程度开始降低;转化率> 68%时,R_s主要受矿物元素的催化作用控制。     

Memristor hyperchaos in a generalized Kolmogorov-type system with extreme multistability

Memristor chaotic systems have aroused great attention in recent years with their potentials expected in engineering applications. In this paper, a five-dimension (5D) double-memristor hyperchaotic system (DMHS) is modeled by introducing two active magnetron memristor models into the Kolmogorov-type formula. The boundness condition of the proposed hyperchaotic system is proved. Coexisting bifurcation diagram and numerical verification explain the bistability. The rich dynamics of the system are demonstrated by the dynamic evolution map and the basin. The simulation results reveal the existence of transient hyperchaos and hidden extreme multistability in the presented DMHS. The NIST tests show that the generated signal sequence is highly random, which is feasible for encryption purposes. Furthermore, the system is implemented based on a FPGA experimental platform, which benefits the further applications of the proposed hyperchaos.     

Some Interface Electrochemical Properties of Kaolinite

The interface electrochemical properties of clay were theoretically analyzed to obtain some relationships among point of zero net charge （PZNC）, point of zero net proton charge （PZNPC）, intrinsic surface reaction equilibrium constants （K in 1-pK model, Ka1^int and Ka2^int in 2-pK model, ＊KNa^int and ＊KNO3^int in inert electrolyte chemical binding model） and structural negative charge density （σst） of clay, and some interface electrochemical parameters of kaolinite were measured. The following main conclusions were obtained. For clay possessing structural negative charges, the PZNC independent of electrolyte concentration （c） should exist just as amphoteric solid without structural charges such as oxides or hydroxides. A common intersection point （CIP） should appear among the potentiometric （or acid-base） titration curves at different c and the pH at the CIP should be PHPZNC. A CIP among potentiometric titration curves at different c for kaolinite was observed, and the value of PHPZNC of kaolinite was 2.16. The values of pHPZNPC were decreased with increasing c, which arises from the presence of structural negative charges of kaolinite. In addition, it was observed that a good linear relationship existed between pHPZNPC and 1g c. According to the values of PHPZNC and σst measured, the intrinsic surface reaction equilibrium constants, pK and pKa1^int and pKa2^int of 1-pK and 2-pK models could be directly calculated for clay, and the values of pK, pKa1^int and pKa2^int for kaolinite were 2.93, 1.90 and 3.97, respectively. These experimental values of pKa1^int and pKa2^int for kaolinite are obviously lower than those optimized with fitting programs in literatures, which maybe arises from the introduction of a type of permanent negatively charged sites in the models of literatures. An interesting result obtained in this study is that the inert electrolyte chemical binding does not exist for kaolinite, which also arises from the presence of structural negative charges.     

双马来酰亚胺树脂增韧研究（1）新型增韧剂的合成、表征及预聚物制备

合成了一种新的增韧剂双（６－稀丙基对甲酚）甲烷（ＭＢＡＰＣ），用元素分析（ＥＡ）、富里哀红外（ＦＴ－ＩＲ）、质谱（ＭＳ）、核磁共振（Ｈ－ＮＭＲ）等方法进行了表征。同时合成了二苯甲烷型双马来酰亚胺（ＭＤＡ－ＢＭＩ）。首次以ＭＢＡＰＣ增韧ＭＤＡ－ＢＭＩ并用溶液法制备了改性ＭＤＡ－ＢＭＩ预聚物。研究了该预聚物的热性能、溶解性和贮存稳定性。     

拟除虫菊酯类农药的NMR研究Ⅰ.α-对取代苯基异戊酸及其类似化合物的手性和前手性NMR研究

α-对取代苯基异戊酸是合成拟除虫菊酯的重要中间化合物,其结构中有手性和前手性两个甲基。为了解构效与活性的关系,本文对其结构特点进行了仔细的考察。用手性位移试剂Eu(hfbc)₃和位移试剂Eu(fod)₃^-分离了对映体的¹H和¹³C的信号,并作出了一定的解释,为鉴定化合物的光学纯度找出了一种简便的方法。对异丙基上的两个非对映异位甲基作了详细的观察,确定了优势构象,并对其作了标识,实验与由简单模型的计算结果一致。本文认为在对这两个非对映异位甲基信号位移差别大小的影响中,取代基的体积效应起了相当重要的作用。     

化痰止咳类中草药中金属元素的含量测定

采用4∶1的混酸体系作为消解液进行样品消解,火焰原子吸收光谱法(FAAS)测定了6种化痰止咳类中草药中金属元素Cu、Mn、Zn、Fe、Ca和Mg的含量.结果表明,6种中草药均含有丰富的金属元素Mg、Ca和较丰富的Fe、Mn,对化痰止咳类中草药的药效起到了促进作用.