二甲醚电氧化及其阳极催化剂研究

Anode electro-catalysts for direct dimethyl-ether fuel cell (DDFC), Pt/C, PtRu/C (1∶1) and PtSn/C (3∶2), were prepared by chemical impregnation-reduction method with formaldehyde as the reductant. DME electro-oxidation and adsorption at Pt electrode and Pt electro-catalysts were investigated by Cyclic Voltammetry(CV), Quasi-steady state polarization and Gas Chromatography(GC). CV showed that there were two current peaks of DME electro-oxidation at Pt electrode around 0.8V (vs RHE); DME was adsorbed at Pt electrode more weakly and slowly than oxygen, methanol, even hydrogen; the onset potential of DME oxidation was 50mV less than that of methanol, and DME peak potential 110 mV lower, thus more advantageous for using in fuel cells than methanol. GC showed that small amount of HCHO was generated during DME electro-oxidation. The mechanism of DME electro-oxidation was proposed. Among the three electro-catalysts (Pt/C, PtRu/C and PtSn/C), Pt alloy catalysts, especially PtRu/C, showed a higher performance toward DME electro-oxidation, as in the case of methanol. Temperature experiments showed that both DME electro-oxidation and adsorption on Pt and Pt alloy catalysts were favored with increased temperature.     

一种重结晶的操作方法

一种重结晶的操作方法肖亚平，贝涣智（南京师范大学化学系２１００９７）做重结晶实验时，通常是在回流下用溶剂使固体溶解，冷却时晶体析出。当在溶剂中存在溶解度较小的杂质时还需趁热过滤。这种做法溶剂量大，产品损失较多。作者在进行微量实验时常需进行微量固体的重...     

新疆藁本挥发油的抑菌活性及组分分析

为了明确中药材新疆藁本挥发油对植物病原真菌的熏蒸抑制活性及分析其化学组分,为新疆藁本挥发油在农业上的应用提供参考依据。采用水蒸气蒸馏法提取新疆藁本挥发油,通过生长速率法测定其挥发油对小麦赤霉病菌、水稻胡麻斑病菌、草莓灰霉病菌和苹果炭疽病菌4种植物病原真菌的熏蒸抑制作用,并利用气质联用仪(GC-MS)分析新疆藁本挥发油的化学组分。结果表明,新疆藁本挥发油对供试的4种植物病原真菌均有强烈的熏蒸抑制作用,有效中浓度(EC_(50))分别为0.98、1.01、1.46、2.79μL/皿。GC-MS从新疆藁本挥发油中共检测到23个组分,鉴定出其中17个,占挥发油总量的99.796%,其主要组分为肉豆蔻醚(94.328%)、2-莰烯(3.018%)等。新疆藁本挥发油可作为抑制植物病原真菌的天然活性成分资源,开发利用。     

低温丁苯橡膠的分子量分佈

由於性能上的優點,生產量最大的丁苯橡膠,近年來已逐漸趨向於使用低溫聚合產物。高聚物的性質与高分子的分子量、分子量分佈以及化學結構有着密切關係,高溫聚合的丁苯橡膠分子量分佈測定的結果,從粘度數據推斷,約有25％的丁苯橡膠分子有顯著的支化或交聯。本工作對一個低轉化率(16％,試樣Ⅲ)和一個較高轉化率(66％,試樣Ⅰ)的低溫(5°)乳液聚合的丁苯橡膠,用分級沉澱和粘度法測定了它們的分子量分佈。     

二茂锆羧酸配合物的合成——二茂锆氢化物与α,β—不饱和酸或钠盐反应的研究

本文研究了Cp_2ZrH_2与丙烯酸和Cp_2Zr(H)Cl与丙烯酸钠、巴豆酸钠的反应。产物由IR 1~H和~(13)CNMR、ESR谱、气相色谱以及化学方法分析鉴定。产物水解得到与底物相应的饱和酸.用~1H NMR方法考察了Cp_2ZrH_2与丙烯酸的反应过程,用IR方法考察了Cp_2Zr(H)Cl与丙烯酸钠的反应过程。实验结果表明,上面两种反应首先消除H_2或NaCl,形成锆氧健,然后碳碳双键还原生成二茂锆羧酸盐配合物,其中羧酸根离子与二茂锆桥式双齿配位。     

Synthesis of Calix[4]arene Derivatives with NLO Properties

The new chromophore compounds with NLO properties were prepared by Knoevenagel condensation from forrnyl or diformyl calix[4/arene and isophorone derivatives in the presence of piperidine and acetic acid, respectively. In these chromophore calix[4]arenes, the ring locked trienes were employed as the conjugation bridge and electron acceptor in D-π-A units. The NMR spectra demonstrated that they existed in a cone conformation and consequently non-conjugated D-π-A units could be oriented at nearly the same direction.     

惯导辅助单历元解算模糊度测姿方法

GNSS与INS在测姿方面的组合理论上可以提升精度，但实际中有时会由于GNSS模糊度固定率低、固定出错、易受干扰等原因导致其精度相对INS过低，以至于组合精度不佳。针对以上问题，提出一种用惯导辅助解算模糊度的方法（IAACM），利用惯导信息辅助解算模糊度浮点解，在固定模糊度后得出更精准稳定的GNSS载体姿态，该姿态可与INS姿态再次组合有效提升测姿精度。该方法在解算模糊度层面引入了惯导信息，具有不受卫星数量限制，单历元固定模糊度，误差稳定等优势。利用高精度GNSS接收机与光纤惯导组合搭建试验平台，在城市道路环境中进行跑车测试，验证模糊度固定情况及测姿精度。试验表明，该方法可提供更精准的模糊度浮点解，并可单历元固定模糊度，有效提升模糊度固定率，使测姿精度大幅提高。     

中立型分数阶微分滑模系统的稳定性

文章主要讨论中立型分数阶微分滑模控制系统的稳定性问题.首先介绍分数阶积分、微分及广义Gronwall不等式的一些定义,然后构造切换面,给出控制律,最后通过李雅普诺夫定理来证明切换面存在,并得出系统的稳定性成立.     

Fmoc-His(Mtt)-OH的合成

以二氯二甲基硅烷为双保护试剂,在碱性条件下组氨酸(His)的咪唑环和α-氨基位分别引入4-甲基-三苯甲基(Mtt)和9-笏甲氧羰基(Fmoc)保护基,合成了Fmoc-His(Mtt)-OH,其结构经1H NMR和MS确证。