用于碱性膜燃料电池的新型聚苯醚阴离子交换膜的制备与性能

以2,6-二甲基聚苯醚(PPO)为原料, 经溴代及N-甲基咪唑季铵化反应, 制备了N-甲基咪唑季铵化PPO, 并进行了红外光谱(FTIR)和氢核磁共振波谱(¹H NMR)表征.所得季铵化产物与聚乙烯醇(PVA)按不同比例共混后用戊二醛交联成膜, 在碱性液中浸泡转化为OH^-型, 得到一系列阴离子交换膜.通过扫描电子显微镜(SEM) 、交流阻抗(AC)、拉伸实验和热重分析(TGA)等手段考察了膜的微观形貌及电导率、力学性能、热稳定性及耐碱性等性能.结果表明, 膜的外观形貌平整均一; 含水率为50.4%~151.2%; 溶胀度为79.2%~164.2%; 离子交换容量为0.47~1.52 mmol/g; 90℃时, M4膜的电导率高达49.1 mS/cm; 断裂伸长率达到128%, 极大改善了PPO膜应力易裂的状况.同时, N-甲基咪唑鎓基团分解温度达到170℃, 高于常用的阴离子交换膜中的季铵基团(120℃).在2 mol/L的NaOH溶液中浸泡192 h后, 电导率仅下降19%, 具备良好的耐碱性能力.     

摩擦微观能量耗散机理的复合振子模型研究

提出无磨损界面摩擦微观能量耗散机理的复合振子模型，指出滑动摩擦过程同时存在整体做低频弹性振动的宏观振子和界面原子受激励产生热振动的微观振子，并在此基础上分析了宏观振子和微观振子对摩擦能量耗散的不同影响. 通过对界面原子的动力学分析，指出摩擦过程界面激励力的频率是能量转换的关键:在平衡力作用阶段，界面作用力的频率趋于零，因而可以直接作用到每个原子，力的作用效果是整体和均匀的；在失稳跳跃阶段,由于界面激励力的频率极高，造成摩擦界面原子获得的能量分布很不均匀，从而产生不可逆的能量耗散过程. 与目前通用的独立振子模型比较，复合振子模型能够更准确描述摩擦能量耗散过程，可为摩擦控制提供理论指导. 关键词： 摩擦 能量耗散机理 复合振子模型 独立振子模型     

Synthesis and crystal structure of EuBi2

The new hypervalent binary phase EuBi₂ was obtained from high temperature solid-state reactions of the pure metal elements in welded Ta tubes under argon atmosphere. Its structure was established by single-crystal X-ray diffraction. The title compound crystallizes in the tetragonal space group I4₁/amd (No. 141) with cell parameters of , and Z=8. The structure of EuBi₂ is isotypic with HfGa₂ and features 1D Bi⁻ zigzag anionic chains along both a- and b-axes and 2D Bi⁻ square sheets normal to c-axis. It can be formulated as Eu²⁺(Bi)_chain⁻(Bi)_square⁻.     

Production and Characterization of Biodiesel from Tung Oil

The feasibility of biodiesel production from tung oil was investigated. The esterification reaction of the free fatty acids of tung oil was performed using Amberlyst-15. Optimal molar ratio of methanol to oil was determined to be 7.5:1, and Amberlyst-15 was 20.8wt% of oil by response surface methodology. Under these reaction conditions, the acid value of tung oil was reduced to 0.72mg KOH/g. In the range of the molar equivalents of methanol to oil under 5, the esterification was strongly affected by the amount of methanol but not the catalyst. When the molar ratio of methanol to oil was 4.1:1 and Amberlyst-15 was 29.8wt% of the oil, the acid value decreased to 0.85mg KOH/g. After the transesterification reaction of pretreated tung oil, the purity of tung biodiesel was 90.2wt%. The high viscosity of crude tung oil decreased to 9.8mm²/s at 40 °C. Because of the presence of eleostearic acid, which is a main component of tung oil, the oxidation stability as determined by the Rancimat method was very low, 0.5h, but the cold filter plugging point, −11 °C, was good. The distillation process did not improve the fatty acid methyl ester content and the viscosity.     

2D d<Superscript>10</Superscript> Metal Assembly Frameworks: Construction of Metal–organic Architecture with Metal Thiocyanate and Dipyridyl Spacer

Abstract  

A new coordination polymer based on Group IB metal thiocyanates, [Ag₂^I (NCS)₂(dpds)₂]_n (1) (dpds = 2,2′-dipyridyldisulfide), has been synthesized by the pre-assembly method and characterized by X-ray crystallography. In 1, the Ag^I center adopts tetrahedral coordination geometry and the 2-D undulated layers of (4, 4) topology network is formed by dpds ligand with zigzag NCS⁻Ag chains.     

Se2(B2O7): a new type of second-order NLO material

Exploration on the compounds in the selenite-borate system led to the discovery of a new second-order NLO material, Se2B2O7, with a SHG efficiency of about 2.2 times that of KDP (KH2PO4). Its structure features a 3D network with helical tunnels, and it is transparent in the UV and visible region. The compound is a wide band gap semiconductor.     

新型流动注射电化学发光分析系统及性能表征

为研发电化学发光体外诊断试剂,设计了一种流动注射池,构建了喷射式流动注射电化学发光分析系统,并运用Ru(bpy)2+3/TPA混合进样模式对此系统进行了评估.在检测电位1.18 V,进样量100 μL,进样速度50 μL/s,TPA浓度10 mmol/L,样品缓冲液100 mmol/L PBS(pH 8.4), 载体缓冲液10 mmol/L PBS(pH 8.4)最优条件下,获得Ru(bpy)2+3的检出限(S/N=3)为0.005 μmol/L; 线性范围为0.01～5 μmol/L; RSD为1.02%.结果表明,此分析系统灵敏度高,线性范围宽,分析速度快,样品用量少,实现了进样、检测及清洗过程自动化.     

静磁场复合电流下时效对Cu—Cr—Zr合金组织及性能的影响

本文在经过固溶和冷变形处理Cu—Cr-Zr合金的等温时效过程中同时施加电流密度为100A／cm2的直流电流和不同磁感应强度的静磁场,发现电磁复合场能显著影响Cu—Cr-Zr合金的组织及性能．和无磁场下时效后合金性能相比,施加磁场后的合金电导率和显微硬度值均有一定程度的升高,其中在350℃,10T磁场下效果最明显,分别升高了22．1％IACS和25．3HV．利用透射电镜观察显微组织观察发现,施加磁场后合金组织中位错密度有所降低,同时出现了大量细小弥散的铬析出物,表明电磁复合场能进一步促进铜合金的时效过程,在低温时效时尤其明显．分析认为,电磁复合场对Cu-Cr-Zr合金时效过程的促进作用机理是磁场增强了电流的“电子风”效应．     

2,9-二甲基-1,10-菲咯啉的α-氨甲基吡啶衍生物的合成表征及其MnⅡ,CoⅡ,NiⅡ,CuⅡ,ZnⅡ配合物稳定性研究

以2,9-二甲基-1,10-菲咯啉为初始原料,合成了2,9-二甲基-1,10-菲咯啉的α-氨甲基吡啶衍生物-N,N'-二(2'-吡啶基)甲基-1,10-菲咯啉-2,9-二甲胺(L)。该配体经过元素分析、红外光谱、核磁共振氢谱表征。在25±0.1℃、I=0.1mol·dm^-3NaNO₃的条件下,用pH电位滴定法测定了该配体在水溶液中的质子化常数及其分别与Mn(Ⅱ),Co(Ⅱ),Ni(II),Cu(Ⅱ)和Zn(Ⅱ)的配合物的稳定常数,提出了配合物的可能结构。进一步讨     

2,9-二甲基-1,10-菲咯啉的dl-丙氨酸衍生物的合成表征及其镧(III)配合物与DNA作用光谱研究

以2,9-二甲基-1,10-菲咯啉为初始原料,合成了2,9-二甲基-1,10-菲咯啉的dl-丙氨酸衍生物:1,10-菲咯啉-2,9-二亚甲基亚氨基-(2,2'-二甲基)二乙酸(L).该配体经过元素分析、红外光谱、核磁共振氢谱表征.在25±0.1℃、I=0.1mol·dm-3NaNO3的条件下,用pH电位滴定法测定了该配体的质子化常数及其与 La(III)的配合物的稳定常数.通过电子光谱研究了La(III)的配合物与小牛胸腺DNA的相互作用.用溴化乙锭作为荧光探针研究了La(III)-L配合物与小牛胸腺DNA的相互作用的过程.作为对比,也研究了La(III)分别与 1,10-菲咯啉(Phen)、dl-丙氨酸(Ala)的配合物与小牛胸腺DNA的相互作用.结果表明La(III)-L配合物与小牛胸腺DNA作用既有共价键合,又有插入作用.