Electrodes modified by electrodeposition of CoTAA complexes as selective oxygen cathodes in a direct methanol fuel cell

The oxygen reduction reaction (ORR) at cobalt tetraazaanulene (CoTAA) modified electrodes was investigated. As a first approach, modified electrodes were prepared by electrodeposition of CoTAA on glassy carbon (GC). The modification of the GC surface was monitored by u.v.–vis. differential reflectance spectroscopy (UVDRS). The recorded spectra (i.e., absorbance as a function of wavelength and time) showed that the electrodeposition of CoTAA at 0.8 V vs Ag|AgCl, that is, at a potential where the TAA ligand is oxidized to TAA⁺, seems to produce a thin polymer film. Starting from these preliminary results, porous rotating disc electrodes (RDEs) were prepared by electrodeposition of CoTAA (0.8 V vs Ag|AgCl, 1 min) on graphite powder embedded in a recast Nafion^® film. The use of a porous RDE allowed comparison of the activity and selectivity of Pt nanoparticles and CoTAA for the ORR under experimental conditions close to those of a fuel cell cathode, that is, at the catalyst|Nafion^® interface. The activity towards the ORR of a porous electrode modified by electrodeposition of CoTAA is not affected when methanol is present in the electrolyte phase, whereas a noticeable decrease in the activity of Pt-based oxygen cathodes was observed under the same conditions. Half-cell life tests showed that CoTAA-modified electrodes and Pt-based electrodes have a comparable stability over a period of 90 min.     

Study of Heat Effect on the Composition of Dunes Sand of Ouargla (Algeria) Using XRD and FTIR

The spectra of x-ray diffraction (XRD) and infrared spectroscopy (FTIR) shows that the dunes sand of Ouargla’s region consists naturally of crystalline structures of α-quartz and gypsum, as well as other uncrystallized compounds with low concentrations like kaolinite and hematite, in addition to some organic compounds. The sand heating process at temperatures between 200 and 1200 °C affects its composition. By heating at 200 °C crystalline phases of anhydrite and bassanite appear due to the continuing loss of water from the gypsum. All the gypsum transforms into anhydrite, and the kaolinite transforms into metakaolin because of the breaking of the OH bond, producing water vapor by heating in the range of 400–800 °C. The heating at 1000 °C disassembles the kaolinite into aluminium-silicon and cristobalite, and leads to the emergence of a new crystalline phase related to wollastonite resulting from the start of a reaction between the anhydride and the quartz. Heating at 1200 °C leads to the disappearance of all the anhydrite because of its interaction with the quartz, producing the wollastonite and the release of sulfur dioxide SO₂ and oxygen O₂, in addition to the increase of the cristobalite proportion because of the disintegration of all the kaolinite into mullite and cristobalite, or the transformation of quartz phase into cristobalite. Also occuring is an interaction between the hematite and the quartz producing the ferrosilite characterized by its green color.     

杨梅黄素分子印迹聚合物的制备及其识别性能研究

以杨梅黄素(MYR)为模板分子、2-乙烯基吡啶(2-VP)为功能单体、二甲基乙二醇丙烯酸酯(EDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,甲醇为致孔剂,采用分子印迹技术制备了杨梅黄素分子印迹聚合物(MYR-MIP)。通过红外光谱、扫描电镜、热重分析等技术表征了MYR-MIP的理化性能;采用紫外光谱分析研究了MYR-MIP对MYR的等温吸附和动力学吸附特性,研究结果表明MYR-MIP对MYR具有良好的特异性吸附,并且在2 h内达到平衡吸附;高效液相色谱分析表明MYR-MIP对MYR具有优良的选择识别特性。     

环番的合成及其应用的研究进展

环番作为一种人工合成受体,具有多个活性位点和一定的空腔尺寸等诸多特性,因而具有分子识别、光学性质、催化活性和药物活性等诸多性质,在许多领域有着广泛的应用前景。总结了近年来环番的合成方法及各自的优缺点,并介绍了其性质、应用等方面的研究进展。     

荆芥挥发油-β-CD对苯酚的吸附及其在卷烟中的应用

采用饱和水溶液法制备荆芥挥发油-β-CD包合物,并用紫外可见分光光度法、X-射线衍射对包合物进行表征。研究了β-CD和荆芥挥发油-β-CD包合物吸附溶液中苯酚的性能。此外,还将β-CD以及荆芥挥发油-β-CD包合物作为添加剂添加到卷烟滤嘴中,研究其对卷烟主流烟气中苯酚的影响。结果表明,β-CD和荆芥挥发油-β-CD包合物吸附溶液中苯酚的动力学模型都是准二级动力学模型。当添加剂用量为30mg时,β-CD以及荆芥挥发油-β-CD包合物对卷烟主流烟气中苯酚的降低率分别为74.01%和88.9%。此外,添加剂还可以有效降低卷烟主流烟气中总粒相物的含量。     

Synthesis and Pharmacological Evaluation of a series of the Agomelatine Analogues as Melatonin MT1/MT2 Agonist and 5‐HT2C Antagonist

Agomelatine is a naphthalenic analogue of melatonin that is in clinical use for the treatment of major depressive disorders. Interestingly, while agomelatine exhibits potent affinity for melatonin receptors, it binds with only moderate affinity to the serotonin 5‐HT_2C receptor. Optimization of agomelatine toward this target could further potentiate its clinical efficacy. To explore this hypothesis and to access derivatives in which a key point of agomelatine metabolism is blocked, a series of naphthalenic derivatives was designed and synthesized as novel analogues of agomelatine. Most of the prepared compounds exhibited good binding affinity at the melatonin MT₁ and MT₂ receptor subtypes. Two compounds, an acetamide and an acrylamide derivative, exhibited good binding affinities at both the human melatonin (MT) receptors and the serotonin 5‐HT_2C receptor subtype, with pK_i values of 7.96 and 7.95 against MT₁, 7.86 and 8.68 against MT2, and 6.64 and 6.44 against 5‐HT_2C, respectively.     

2-羟基-1-萘醛缩对氨基水杨酸希夫碱钴配合物的合成、表征及其性质研究

合成2-羟基-1-萘醛缩对氨基水杨酸希夫碱钴配合物,通过紫外吸收法、红外光谱法、元素分析法对其进行结构表征。利用荧光光谱法,采用Stern-Volmer方程、双对数回归曲线模型处理数据,计算得出不同温度下配合物与牛血清白蛋白(BSA)的结合常数、结合位点数。     

Elaboration and thermal analysis of nanocomposites based on poly(methyl methacrylate‐co‐4‐vinylpyridine) and Maghnia bentonite

Nanocomposites based on an organically modified bentonite, from Maghnia Algeria (OBT) and a copolymer of methyl methacrylate with 4‐vinylpyridine (PMM4VP) synthesized in dioxan at room temperature using a neutral Ni(II)α‐benzoinoxime complex as a single component initiator, were elaborated via solution intercalation method and characterized by several techniques. X‐ray diffraction and transmission electron microscopy investigations indicate that mainly exfoliated and intercalated PMM4VP/OBT nanocomposites were elaborated and that the degree of exfoliation decreases with an increase of the OBT loading. Thermal analyses of these nanocomposites compared with their virgin copolymer confirmed a significant improvement of their thermal stability as evidenced by an increase of 28°C in their onset degradation temperatures. In addition, differential scanning calorimetry displayed an increase in the range of 12–18°C in their glass transition temperatures relative to their virgin copolymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

槲皮素金属配合物的研究进展

槲皮素具有广泛的生物活性和多方面的药理作用,有完整的大π键共轭体系、强配位氧原子及合适的空间构型,可与多种金属离子螯合成稳定的环状配合物。研究表明:槲皮素金属配合物具有抗癌、抗炎、抗氧化、清除自由基和降血糖等作用。槲皮素金属配合物生物活性明显高于槲皮素,药理作用显著。综述了槲皮素金属配合物的研究进展,介绍了槲皮素与主族、副族和稀土金属元素形成配合物的研究现状,为此类化合物的研究提供科学依据。     

硅噻菌胺合成新工艺

[目的]硅噻菌胺是小麦全蚀病选择性防治药剂,然而该药剂的规模合成存在着很大挑战,为此,研究开发了硅噻菌胺的新合成工艺。[方法]该工艺以3-氯-2-丁酮、丙炔酸甲酯为起始原料,通过取代、环合、硅烷化和酰胺化等4步反应,方便地得到目的产物。[结果]该工艺具有原料易得、反应易控、反应媒介易于回收使用、单步收率高等特点。[结论]具有工业应用前景。