STUDY ON THE MECHANISM OF 1-OCTENE ZIEGLER-NATTA POLYMERIZATION BASED ON THE NUMBER OF ACTIVE CENTERS

The number of active centers (C_p)-t and k_p-t profiles of Solvay type TiCl_3 - AlR_3 (R=C_2H_5, i-C_4H_9) or Stauffer AA TiCl_3-Al (C_2H_5)_3 catalyzed 1-octene polymerization were determined by using an acetyl chloride quenching method as well as kinetic data. The results show that in the studied systems k_p decreases when C_p increases, indicating the presence of two or more types of different active centers. The C_(p~(-t)) plots of the Solvay TiCl_3-AlR_3 systems show the presence of both stable active centers and unstable centers which decay in the polymerization process. The phenomena are explained based on a model of active center plurality. The increases of C_p in the induction periods are also discussed.     

NdF3-LiF-Nd2O3熔盐体系中下阴极电解金属钕研究

设计了下阴极结构的稀土金属电解槽,该电解槽底部以钨材料为容器兼阴极,上部悬挂多块石墨作阳极,在NdF3·LiF-Nd2O3体系中,探索研究了液态下阴极电解制备金属钕的工艺技术条件.研究表明,在槽温990～1020℃,阴极电流密度1～3 A·cm-2.槽电压5.6 V条件下,电解可平稳进行,电流效率达65.64%,稀土回收率达88%～92%;该工艺与目前主流上插阴极电解工艺相比,其电解温度和槽电压明显降低,降低了电耗.     

以苯为模块自组装合成碳纳米片

在300 ℃苯溶剂中, 以无水三氯化铝为催化剂, 以苯和六氯乙烷为碳源, 基于傅克烷基化反应生成三氯乙烯苯, 并以之为模块自组装合成了具有叠层结构的碳微米颗粒, 其层片厚度为300～500 nm. 进而在反应体系和反应条件不变的情况下, 通过引入铝粉颗粒作为基底成功地诱导出厚度为30～50 nm的碳纳米片. 实验结果表明, 所得碳材料由纳米石墨微晶和非晶碳组成. 文中探讨了叠层结构的台阶长大机制, 以及碳纳米片在铝粉表面的异质形核机制.     

红参加工过程中梅拉德初级反应产物的研究

利用电喷雾质谱技术分析红参水层提取物,发现有不同于鲜参的成分,经进一步分析证明在红参加工过程中鲜参中的麦芽糖和氨基酸发生了梅拉德反应,生成了新的氨基酸衍生物.通过产物的模拟合成,电喷雾串联质谱以及傅立叶变换离子回旋共振质谱分析,对这几种成分进行了深入研究,鉴定出它们是麦芽糖分别与精氨酸,谷氨酸和天冬氨酸反应生成的双糖苷,是红参在加工过程中产生的特有成分.     

Chemoselective hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol over Ir-MoOx/Si02 catalyst

In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol （THFA） to 1,5-pentanediol in a continuous flow reactor. The effects of different noble metals （Ir, Pt, Pd, Ru, Rh）, supports and Ir contents were screened. Among the investigated catalysts, 4 wt%Ir-MoOx/SiO2 with a Mo/Ir atomic ratio of 0.13 exhibited the best catalytic performance. The synergy between Ix particles and the partially reduced isolated MoOx species attached on them is essential for the excellent catalytic performance of Ix-MoOx/SiO2. The catalyst exhibited a better hydrogenolysis efficiency of THFA with the selectivity of 1,5-pentanediol of 65%-74% at a conversion of THFA of 70%-75% when the initial THFA concentration is ranging from 20 wt% and 40 wt%. And higher system pressure was also in favor of the conversion of THFA. During a stability test, the conversion of THFA and 1,5-pentanediol yield over Ix-MoOz/SiO2 decreased with reaction time, which can be explained by the leaching of Mo species during the reaction.     

Mesoporous carbon material as cathode for high performance lithium-ion capacitor

The mesoporous carbon material with large pore volume and high surface area by a simple situ MgO template method is synthesized, which is utilized as cathode to assemble a high performance lithium ion capacitor.     

加强实验教学环境内涵建设 提高环境育人质量

在实验室里的实验教学过程涉及到教书育人、管理育人、服务育人和环境育人。一个良好的实验环境不仅能够对学生起到潜移默化的教育作用,而且对教书育人、管理育人和服务育人工作的开展和实施也能起到推动和促进作用。本文主要介绍厦门大学化学国家级实验教学示范中心"以学生为中心",在强化实验教学环境内涵建设、提高实验环境育人质量方面的一些做法和体会,以期更好地为实验教学"思政"提供可复制、可推广的建设方案。     

“元素化学实验”中的“异常”现象(一)--Mn元素化学实验中的“异常”现象及其探析

大一学生在“元素化学实验”教学过程中,对反应条件如温度、催化剂、酸度、浓度或试剂用量等因素的影响考虑不周,可能出现某些实验现象和预想的或理论分析的结果不一致的“异常”现象。本文就学生在Mn元素化学实验过程中遇到的一些“异常”现象进行分析和总结,借助生动直观的演示实验,引导学生探究“异常”现象产生的可能原因和直观认识反应条件对反应结果的影响,培养学生的观察、分析、判断、归纳、推理和解决实际问题的能力。     

完全与不完全叉形分岔实验

介绍一种可演示完全与不完全叉形分彷的实验装置，并分析其机理。本文对非线性动力学实验设计有一定启示作用。     

认股权证的等价鞅测度定价模型与数值方法

本文对认股权证应用等价鞅测度方法进行定价 .推导出计算更自然、更简单的类似 Black- Scholes模型的认股权证定价公式 .给出了一种比较好的数值计算方法 .并讨论了认股权证在中国证券市场的发展状况 .