Synthesis of Obyanamide, a Marine Cytotoxic Cyclic Depsipeptide

Obyanamide 1 is a cyclic depsipeptide that was recently isolated from the marine cyanobacterium Lyngbya confervoides by Moore and co-workers1. This compound displayed a potent inhibitory effect on both KB and LoVo cells in vitro. Several structural analog…     

层状LiMnO_2正极材料的研究进展

层状LiMnO2 化合物的研究是目前锂离子电池正极材料锂锰氧化物研究工作的新热点 ,本文综述了近年来国内外LiMnO2 化合物的研究进展 ,主要阐述了具有层状和扭曲层状结构的m LiMnO2和o LiMnO2 的结构、电性能、合成和改性方法等方面的研究状况 ,重点介绍了离子交换法合成层状LiMnO2 的原因和机理。探索新的合成方法和掺杂其它金属离子改性以提高循环性能是今后LiMnO2 的研究趋势。     

白术挥发油中苍术酮氧化反应的动力学

白术挥发油;苍术酮;动力学方程;活化能;反应机理     

球形钴酸锂的乳液法合成及其结构、性能研究

采用一种特殊乳液法, 制备了锂离子电池正极材料球形LiCoO₂. 分别研究了一次颗粒尺寸、烧结时间对于二次造粒的影响. 还对LiCoO₂球体内部的结构进行了SEM和HRTEM研究, 发现一次颗粒非常紧密地融合在一起, 晶体边界区域没有明显的非晶相区, 也没有纳米级别的孔洞、裂缝. 电化学性能研究表明, 在900 ℃烧结4 h的材料具有较高的首次放电容量(143 mAh•g^－1)和良好的循环性能     

刚性链嵌段共聚物研究 Ⅱ．含双酚S的聚醚醚酮共聚物合成与性能

series of multiblock copolymers composed of polyetheretherketone (PEEK) and 4, 4'-dihydroxydiphenylsulfone (DHDPS) were synthesized by polycondensation. The property of copolymers were characterics by DSC, IR, WAXD and TGA. The results indicate that the T_g of copolymers increases with increasing DHDPS content' When the DHDPS content of the copolymers is less than 22% (the average degree of polymerization of PEEK oligomers is more than 6), the copolymers are Crystalline polymers. The highest T_g of the Crystalline copolymers is 160℃,the lowest T_m is 304℃.     

Improved hygrothermal durability of flax/polypropylene composites after chemical treatments through a hybrid approach

There are growing research interests in flax fibers due to their renewable ‘green’ origin and high strength. However, these natural fibers easily absorb moisture and have poor adhesion with polymer matrix leading to low interfacial strength for the composites. A hybrid chemical treatment technique combining alkali (sodium hydroxide) and silane treatments is adopted in the current study to modify flax fibers for improved performances of flax/polypropylene composites. Changes in chemical composition, microstructure, wettability, surface morphology, crystallinity and tensile properties of single flax fiber before and after chemical treatments were comprehensively characterized using techniques including SEM, FTIR, AFM, XRD, micro-fiber tester, etc. It was found that hemicellulose and lignin at the fiber surface were removed due to alkali treatment, which helped to reduce moisture absorption of the composites. Alkali-treated flax fibers were later subjected to silane treatment, which helped to improve the compatibility between flax fiber and polypropylene matrix. After alkali-silane hybrid chemical treatment, moisture absorption of the composites was further decreased. At the same time, the interfacial bonding strength between flax and polypropylene is significantly enhanced. All these results validate the great advantage of the hybrid chemical treatment approach for flax/polypropylene composites, which has the potential to promote the application of chemical treatment techniques in the plant fiber composite industry.

Graphic abstract

     

Tris(2,2''''-bipyridyl)ruthenium(Ⅱ) electrochemiluminescence (ECL) enhanced by rutin on platinum electrode

Ru(bpy)_(3~(2 )) electrochemiluminescence (ECL) was applied to determination of rutin. ECL intensity of Ru(bpy)_(3~(2 ))could be enhanced in the presence of rutin in basic solution on platinum electrode. At pH 9.9, light emission intensity was found to be linear with rutin in the range of 1-50 mmol/L.     

从蓖麻油制取10-羟基癸酸的研究

本文报道了从蓖麻油制取10-羟基癸酸的研究,发现了从蓖麻油制取10-羟基癸酸的新的工艺路线和最佳的工艺条件,用氢氧化钠用量、2-辛醇量、反应时间和反应温度四因子三水平L_9(3~4)进行了正交试验,发现最佳工艺条件是:氢氧化钠(g)/蓖麻油(g):1.25:2-辛醇量(g)/蓖麻油(g):2:反应时间:6h;反应温度:180℃。在这一新的工艺路线和最佳工艺条件下,10-羟基癸酸产率可达75％。     

催化裂化汽油脱硫添加剂USY/ZnO/Al2O3的性能评价

 在固定流化床催化裂化装置上，以减压蜡油为原料，对制备的U\r\nSY／ZnO／Al2O3催化裂化汽油脱硫添加剂的性能进行了评价．结果表明\r\n，随着添加剂添加量和剂油比的增加，生成汽油的硫含量降低．在500\r\n℃和剂油比为5的条件下，在FCC平衡催化剂中添加30％的添加剂时，汽\r\n油的硫含量可由不加添加剂时的1230μg／g降低到770μg／g左右．添\r\n加剂的添加量（10％）较低时，对催化裂化产物的分布基本没有影响；\r\n添加30％的添加剂时，焦炭的产率有所增加，但汽油收率基本不变．X\r\nRD表征结果表明，USY／ZnO／Al2O3添加剂中的ZnO对USY的晶相结构有\r\n一定的破坏作用，但随着反应与再生次数的增多，ZnO与Al2O3之间形成\r\n较为稳定的锌铝尖晶石结构，使添加剂的性能趋于稳定．     

耐高温α-淀粉酶结合Ca2+的研究

测定了耐高温α-淀粉酶分子中含10个Ca2+,脱钙酶逐量补钙后的活力及稳定性研究表明:酶分子中前8个Ca2+参与酶的催化作用,后2个Ca2+抖对酶结构起稳定作用.脱钙酶加钙后室温下的荧光光谱和CD谱表明:酶的构象虽有变化,但不显著,说明酶的构象对ca2+的依赖性很小.脱钙酶结合不同数目的Ca2+,于90℃加热15 min后,测其荧光光谱,结果表明,结合10个Ca2+时,酶保持最大的稳定构象;CD谱表明脱钙酶加热时仍具有一定的螺旋结构.这再次说明,酶的构象对ca2+依赖性较低.