油基-金纳米流体的制备及热稳定性

分别采用N-十六烷基-N-(羟乙基)-N,N-二甲基溴化铵(CHDAB)和丁烷-1,4-二(N-十六烷基-N,N-二甲基溴化铵)(G16-4-16)2种阳离子表面活性剂作为金属表面修饰剂, 在石油醚/正丁醇/水混合体系中用KBH₄ 还原HAuCl₄制备出亲油性纳米金. 其中, 双子表面活性剂G16-4-16显示出更好的包裹分散作用, 其包裹的纳米金粒径分布范围较窄, 平均粒径为5.2 nm. 将该纳米金颗粒分散在液态烷烃、 甲苯和长链烷基醇等溶剂中可制成稳定的油基纳米流体. 采用紫外-可见光谱法跟踪热稳定性随时间的变化, 结果表明, 该纳米流体显示了较好的热稳定性, 在130 ℃稳定时间达20 h. 采用点热源法测定了该纳米流体的导热系数, 结果表明, 50 ℃时添加质量分数1.5%的纳米金可以使其导热系数增大约17%.     

模板分子诱导的微孔镧系-2-羧基肉桂酸超分子配合物的合成与结构

由水热法合成了2个微孔镧系超分子配合物[Ln(CCA)(OH)(phen)(H2O)]n·n(phen)·nH2O(Ln=Yb,1;Er,2;H2CCA=2-羧基肉桂酸;phen=1,10-菲啰啉),并用元素分析、IR及X-射线单晶衍射对其进行了表征。晶体结构研究表明,2个配合物都是由配体2-羧基肉桂酸连接而形成的一维双链结构,该链状结构通过氢键和π-π堆积作用扩展为具有微孔结构的超分子。1,10-菲啰啉在微孔结构的形成过程中起到了模板剂的作用。     

纳米纤维素晶须的表面醋酸酯化改性及复合材料的力学性能

采用硫酸水解法制备纳米纤维素晶须, 再以冰醋酸为分散介质, 浓硫酸为催化剂, 醋酸酐为酯化剂对纳米纤维素晶须进行不同程度醋酸酯化改性, 得到醋酸酯化的纳米纤维素. 采用红外光谱(FTIR)、 X射线光衍射(XRD)、 透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对改性产物进行分析和表征. 结果表明, 改性纳米纤维素晶须中醋酸酯基的平均取代度过小或过大时均不适宜用作复合材料的增强相. 当改性纳米纤维素晶须中醋酸酯基的平均取代度为0.05时, 醋酸酯化反应只发生在纳米纤维素晶须的表面. 此时, 晶须能在丙酮中稳定悬浮, 表现出流动双折射现象, 并保持了改性前纳米纤维素晶须的棒状形态和高结晶度. 将这种改性后的纳米纤维素晶须作为增强相与醋酸纤维素通过溶液浇铸法制成纳米复合膜, 结果显示, 与空白醋酸纤维素膜相比, 添加改性纳米纤维素晶须后, 纳米复合膜的拉伸强度、 杨氏模量和断裂伸长率都得到了提高. 在玻璃化转变区间纳米复合膜储能模量的降低幅度小于空白膜.     

浙江大学基础化学实验研究生助教的实践和探索

研究生助教是对研究生自身能力的培养和锻炼,同时也补充了本科教学教师资源。提高本科教学的质量,需要加强对研究生助教的培训、指导、管理和考评,也需要加强课程教学的统一规范管理,加强对学生学习的督促和引导。本文探讨了基础化学实验研究生助教的教学经验,并对今后实验教学管理以及研究生助教的培养等提出一些思考和建议。     

Performance of non-thermal DBD plasma reactor during the removal of hydrogen sulfide

Destruction of hydrogen sulfide using dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. Three types of DBD reactor were compared in terms of specific energy density (SED), equivalent capacitances of the gap (Cg) and the dielectric barrier (Cd), energy yield (EY), and H₂S decomposition. In addition, byproducts during the decomposition of H₂S and destruction mechanism were also investigated. SED for all the reactors depended almost linearly on the voltage. In general, Cg decreased with increasing voltage and with the existence of pellet material, while Cd displayed the opposite trend. The removal efficiency of H₂S increased substantially with increasing AC frequency and applied voltage. Longer gas residence times also contributed to higher H₂S removal efficiency. The choice of pellet material was an important factor influencing the H₂S removal. The reactor filled with ceramic Raschig rings had the best H₂S removal performance, with an EY of 7.30 g/kWh. The likely main products in the outlet effluent were H₂O, SO₂, and SO₃.     

Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots

Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence （ps TRPL） experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.     

Isospin effects of the Skyrme potential and the momentum dependent interaction at intermediate energy heavy ion collisions

We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio.     

环戊叉基环戊酮的烷基化反应研究

研究了环戊叉基环戊酮与不同类型烷化剂的反应规律；讨论了不同催化剂对烷基化反应的催化性能，发现ＮａＮＨ２和ＮａＨ具有较好的催化作用；讨论了烷基化产物的结构，证实了烷基化反应发生在羰基的α双键碳原子上。     

Periodic Wave Solutions for （2＋1）-Dimensional Boussinesq Equation and （3＋ 1）-Dimensional Kadomtsev-Petviashvili Equation

For describing various complex nonlinear phenomena in the realistic world, the higher-dimensional nonlinear evolution equations appear more attractive in many fields of physical and engineering sciences. In this paper, by virtue of the Hirota bilinear method and Riemann theta functions, the periodic wave solutions for the （2＋1）-dimensional Boussinesq equation and （3＋1）-dimensional Kadomtsev Petviashvili （KP） equation are obtained. Furthermore, it is shown that the known soliton solutions for the two equations can be reduced from the periodic wave solutions.