LongikaurinB的晶体结构分析

长管香茶菜B（LongikaurinB）分子的化学计量式为C22H30O7，Mr=406．47，用X射线衍射法确定其晶体结构，该结晶是无色透明柱状，属单斜晶系，空间和群为P21，晶胞参数：a=11．893（2），b=6.380（2），c=13．205（2）A，β=99．39（2）°，Z=2，V=988．5（4）A3，Dc＝1．366g／cm3，F（000）＝436，u＝0．9cm-1。应用直接法解析分子结构，以最小二乘法修正结构参数。最终可靠因子R=0.042，Ra=0.043。结果表明，该化合物为长管香茶菜B，属7，20-氧桥-对映-贝壳杉烯型工花化合物。结构与功能关系研究表明LongikaurinB化合物可能具有抗肿瘤生物活性。     

Improved Enantioselective Synthesis of Protected (3S,4S)-4-Amino-3,5-dihydroxypentanoic Acid (ADPA)

An improved enantioselective synthesis of protected (3S,4S)-4-amino-3,5-dihydroxypentanoic acid (ADPA) from L-serine has been developed. Enantioselectivity is improved by replacing the methyl ester with the tert-butyl ester and using neutral magnesium salt of esters to give β-keto ester.     

模糊熵算法在混沌序列复杂度分析中的应用

为了准确分析混沌序列的复杂性, 采用模糊熵算法(FuzzyEn) 对典型离散混沌系统和连续混沌系统的复杂度进行分析. 与近似熵(ApEn)、 样本熵(SampEn) 和强度统计复杂度算法相比, FuzzyEn算法是一种更有效的混沌复杂度测度算法, 且对相空间维数(m)、 相似容限度(r) 和序列长度(N) 的敏感性、 依赖性更低, 鲁棒性和测度值的连续性更好. 对混沌系统的复杂性分析表明, 连续混沌系统的复杂度远小于离散混沌系统, 但是如果利用高复杂度的离散混沌伪随机序列或经典 m序列对连续混沌系统产生的伪随机序列进行扰动, 则能大大提高混沌序列的复杂性. 为混沌序列在密码学和混沌保密通信中的应用提供了理论依据.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定TB9钛合金中微量Si

采用电感耦合等离子体原子发射光谱(ICP-AES)法对TB9钛合金中微量Si的测定进行了研究。总结了基体对较灵敏Si的8条分析线的光谱干扰,发现从Si 185.067nm到Si 288.158nm均有不同基体元素的干扰,对微量Si的测定影响很大。经研究对比,选用背景相对低且信噪比高的Si 288.158nm线,以试剂加定量V为空白来校正基体V的光谱叠加干扰,标准加入法测定。方法检出限0.04μg/mL,标准加入校准曲线的线性相关系数0.999 9。样品加标回收率为100%~105%,相对标准偏差(n=8)小于2.0%。方法简便可靠,可获得满意的分析结果。     

光动力蛋白C-PC中脱辅蛋白的空间结构研究

本文利用拉曼光谱分析技术,对纯化后的螺旋藻C藻蓝蛋白(CPC)分子,在0075mol/L盐溶液中的空间结构进行了分析。本文认为CPC的脱辅蛋白空间构象在此溶液和10℃条件下是α螺旋与β回转结构。“暴露的”酪氨酸占44%;色氨酸也处于部份“暴露”状态;β111的半胱氨酸不参与硫醚键的形成,有自由的CS单键伸缩振动模;谱中没有二硫键的存在。     

Visible-Light Photocatalytic Reduction of Aryl Halides as a Source of Aryl Radicals

Aryl- and heteroaryl units are present in a wide variety of natural products, pharmaceuticals, and functional materials. The method for reduction of aryl halides with ubiquitous distribution is highly sought after for late-stage construction of various aromatic compounds. The visible-light-driven reduction of aryl halides to aryl radicals by electron transfer provides an efficient, simple, and environmentally friendly method for the construction of aromatic compounds. This review summarizes the recent progress in the generation of aryl radicals by visible-light-driven reduction of aryl halides with metal complexes, organic compounds, semiconductors as catalysts, and alkali-assisted reaction system. The ability and mechanism of reduction of aromatic halides in various visible light induced systems are summarized, intending to illustrate a comprehensive introduction of this research topic to the readers.     

Overview of Ionogels in Flexible Electronics

Ionogels have aroused wide interests in the field of flexible electronics. The combination of solid‐state networks and ionic liquids opens up thousands of possibilities for ionogels. The unique structures of ionogels endow them excellent mechanical properties, conductivity and thermal stability to approach the challenge of flexible electronic. A large number of new ionogels have been developed by different methods including the exchange of solution, polymeric ionic liquid and in‐situ reactions in ionic liquids (gelation of low molecular weight gelators, self‐assembly of block polymers, formation of double‐network structure, ionogel nanocomposites and direct polymerization of polymerizable monomers). The aim of this review is to discuss different preparation methods of ionogels and the comparison of their advantages.     

低酸度淋洗液离子色谱法测定多聚磷酸盐

在国产阴离子分离柱上采用含钙和镁离子的淋洗液，由于Ｃａ＾２＋和Ｍｇ＾２＋与复杂的多聚磷酸根离子形成螯合物而提高了淋洗能力，加快了分析速度，大大降低了淋洗液的酸度和盐浓度，对几种工业三聚磷酸钠样品进行了测定，与化学法相比，相对误差小于１．５％，加入回收率在９９％－１０９％之间。     

Hydrophilic Quaternary Ammonium‐Group‐Containing [FeFe]‐Hydrogenase Models: Synthesis,Structures, and Electrocatalytic Hydrogen Production

The first quaternary ammonium‐group‐containing [FeFe]‐hydrogenase models [(μ‐PDT)Fe₂(CO)₄{κ²‐(Ph₂P)₂N(CH₂)₂NMe₂BzBr}] ( 2 ; PDT=propanedithiolate) and [(μ‐PDT)Fe₂(CO)₄{μ‐(Ph₂P)₂N(CH₂)₂NMe₂BzBr}] ( 4 ) have been prepared by the quaternization of their precursors [(μ‐PDT)Fe₂(CO)₄{κ²‐(Ph₂P)₂N(CH₂)₂NMe₂}] ( 1 ) and [(μ‐PDT)Fe₂(CO)₄{μ‐(Ph₂P)₂N(CH₂)₂NMe₂}] ( 3 ) with benzyl bromide in high yields. Although new complexes 1 – 4 have been fully characterized by spectroscopic and X‐ray crystallographic studies, the chelated complexes 1 and 2 converted into their bridged isomers 3 and 4 at higher temperatures, thus demonstrating that these bridged isomers are thermodynamically favorable. An electrochemical study on hydrophilic models 2 and 4 in MeCN and MeCN/H₂O as solvents indicates that the reduction potentials are shifted to less‐negative potentials as the water content increases. This outcome implies that both 2 and 4 are more easily reduced in the mixed MeCN/H₂O solvent than in MeCN. In addition, hydrophilic models 2 and 4 act as electrocatalysts and achieve higher i_cat/i_p values and turnover numbers (TONs) in MeCN/H₂O as a solvent than in MeCN for the production of hydrogen from the weak acid HOAc.     

Recent advances in energy storage mechanism of aqueous zinc-ion batteries

Aqueous rechargeable zinc-ion batteries(ZIBs)have recently attracted increasing research interest due to their unparalleled safety,fantastic cost competitiveness and promising capacity advantages compared with the commercial lithium ion batteries.However,the disputed energy storage mechanism has been a confusing issue restraining the development of ZIBs.Although a lot of efforts have been dedicated to the exploration in battery chemistry,a comprehensive review that focuses on summarizing the energy storage mechanisms of ZIBs is needed.Herein,the energy storage mechanisms of aqueous rechargeable ZIBs are systematically reviewed in detail and summarized as four types,which are traditional Zn²⁺insertion chemistry,dual ions co-insertion,chemical conversion reaction and coordination reaction of Zn²⁺with organic cathodes.Furthermore,the promising exploration directions and rational prospects are also proposed in this review.