In Situ Confocal Microprobe Raman Spectroscopy Study of the Oxygen Species over Cerium Oxide

Ｃｏ￣ｎｄｅｎｃｅａｕｔｈｏｒ．Ｏａｆ（（ｋ６＜ｌ）ａｄｓｐｅｃｉｅｓＰｅａｋｓｗｅｒｅｆｏｕｎｄｔｏｄｉｓａｐｐｅａｒａｔ５７３＇Ｋ．Ｄｕｒｉｎｇｔｈｅｔｅｍｐｅｒａｔｕｒｅｅｌｅｖａｔｉｏｎ，ｔｈｅＣｅＯＺＦＺｇａｎｄＯ２－Ｐｅａｋｓｗｅｒｅｆｏｕｎｄｔｏｂｒｏａｄｅｎａｎｄｓｈｉｆｔｔｏｌｏｗｅｒｗａｖｅｎｕｍｂｅｒｓ．ＴｈｅｆｈａｌｕｅｎｃｙｓｈｉｆｔｗｉｌｈｒｅｓｅｃｔｔｏｔｅｍｐｅｒａｔｕｒｅｉｓａｗｅｌｌｋｎｏｗｎｐｈｅｎｏｍｅｎｏｎｉｎＲａｍａｎｓｐｅｃｔｒｏｓｃｏｐｙｏｆｓｏｌｉｄｓａｎｄｉｔｉｓｒｅｌａｔｅｄｔｏｔｈｅｔｈｅｒｍａ］ｅｘｐａｎｓｉｏｎｏｆｌａｔｔｉｃｅｐａｒａｍｅｔｅｒｓ．Ａｔ１０２３＇Ｋ，ｔｈｅＯ２－ａｄｓｐｅｃｉｅｓ（ａｔ１１５９ｃｍ－ｌ）ａｎｄＣｅＯＺＦ２，（ａｔ４４９ｃｍ－ｌ）ｐｅａｋｓｗｅｒｅｆｏｕｎｄｔｏｒｅｍａｉｎｅｘｉｓｔｉｎｇｏｎｔｈｅｓｕｒｆａｃｅｏｆｃｅｒｉｕｍｏａｌｄｅ．ＷｈｅｎｔｈｅＯＺ－ｐｒｅｔｒｅａｔｅｄＣｅＯＺｓａｍｐｌｅｗａｓｗａｒｍｅｄｓｕｃｃｅｓｓｉｖｅｌｙｉｎａｆｌｏｗｏｆＣｄ，ｔｈｅｒｅａｃｈｏｎｓｏｆＣａｂｗｉｔｈｌａｎｉｃｅｏ     

The Active Oxygen Species for Oxidative Coupling of Methane over CeO_2/BaF_2 Catalyst by in Situ Confocal Microprobe Raman Spectroscopy

ＴｈｅＡｃｔｉｖｅＯｘｙｇｅｎＳｐｅｃｉｅｓｆｏｒＯｘｉｄａｔｉｖｅＣｏｕｐｌｉｎｇｏｆＭｅｔｈａｎｅｏｖｅｒＣｅＯ２／ＢａＦ２ＣａｔａｌｙｓｔｂｙｉｎＳｉｔｕＣｏｎｆｏｃａｌＭｉｃｒｏｐｒｏｂｅＲａｍａｎＳｐｅｃｔｒｏｓｃｏｐｙ＊＊Ｓｕｐｐｏｒｔｅ...     

Preliminary Study on Cordycepin-DNA Interaction by Raman Spectroscopy

The interaction of cordycepin with calf thymus DNA was investigated at physiological pH with drug/DNA molar ratio of 8. The Raman spectroscopy results indicated that the intercalation of high concentration cordycepin and the interaction of cordycepin with PO2 group led to a major reduction of B-form DNA structure in favor of A-form DNA.     

Investigation of Bis(α-Phenylethylamido)Methylphosphonates by NMR Spectroscopy

Abstract

The influence of the relative location of chiral carbon and phosphorus atoms and the position of the aryl-group on diastereomeric anisochronity in non-racemic mixtures of enantiomers has been examined. The optical isomers of methanephosphonic acid bis(α-phenylethylamide) (I), which contain pro-chiral phosphorus atom, were synthesized by the reaction of methanephosphonic acid dichloride(II) with (+)- or (-) -α-phenylethylamine (III). The extent of chemical shift nonequivalence in ³¹P and ¹H NMR spectra of non-racemic mixtures of RR- and SS-I was negligible. It can be explained by the absence of aryl-amino group, favouring intermolecular association, effect of SCADA¹, and the long distance between the chiral center and pro-chiral phosphorus. Phosphonylation of non-racemic mixtures of (+)- and (-)-III by II proceeds stereospecifically giving mixture of RR-, SS-I, and two meso-compounds analyzed by ³¹P ¹H NMR.     

Investigation and Application of Polarographic Catalytic Wave of Oxygen Reduction Caused by Mefenamic Acid

The polarographic catalytic wave of oxygen reduction caused by mefenamic acid (MA) with redox properties was reported in this paper. The electrochemical process of the catalytic wave was proposed that the superoxide anion O(?) was generated polarographically and the dismutation of the O(?) was catalyzed by MA to reproduce O_2 and H_2O_2. This explained chemically the scavenging of the O_2~- by MA im biomedical area. Based on the catalytic wave, a new method for the determination of MA by single-sweep polarography was developed.     

Investigation on the Electrochemical Polymerization of Catechol by Means of Rotating Ring—disk Electrode

The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring-disk electrode (RRDE) experiments show that at low pH values,the electrochemical polymerization of catechol was performed by one step,and at higher pH values,the electrochemical polymerization of catechol was carried out by two steps,i.e.oxidation of catechol and followed by polymerization.The intermediates generated at the disk were detected at the ring electrode in the ring potential region of -0.2 to 0 V(vs.Ag/AgCl).One of reasons for the decrease in the ratio of ir to id with increasing the ring potential is caused by formation of positively charged intermediates at the disk electrode.This ratio increases with increasing the rotation rate of the RRDE,which indicates that the intermediates are not stable.A shielding effect during polymerization of catechol was observed when the ring potential was set at 0.1 V (vs.Ag/AgCl).The electron spin resonance(ESR) of polycatechol show that polycatechol possesses unpaired electrons.The images of polycatechol films synthesized at differentconditions are described.     

Characterization of Greek Wines by Ultraviolet–Visible Absorption Spectroscopy and Statistical Multivariate Methods

Optical absorption spectroscopy has been used to study Cretan Greek wine matured for 3 months in various barrels. Vilana and Dafni white and Kotsifali and Mandilari red wines were analyzed. The total phenolic index for all varieties and color characteristics for only the red wine were determined. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) demonstrated that the absorption spectra, combined with multivariate statistical methods, may be used to identify these varieties. The results of principal component analysis were used to infer the chemical compounds responsible for the discrimination between varieties.     

Investigation of the Interaction between Isoflavonoids and Bovine Serum Albumin by Fluorescence Spectroscopy

The interactions of bovine serum albumin （BSA） with three structurally related isoflavonoids, genistein, puerarin and daidzein, were studied under physiological conditions by fluorescence spectroscopic technique. The quenching mechanism of these compounds with BSA was suggested as static quenching and the binding constants were determined at different temperatures based on the fluorescence quenching results. The transfer efficiency of energy and distance between the acceptor and BSA were investigated on the basis of the mechanism of the Forster energy transference. According to the thermodynamic parameters it has been suggested that the acting force be mainly hydrophobic force. The comparison of binding potency of the three isoflavonoids to BSA showed that the substitution by 5-OH and 8-Glc could enhance the binding affinity. All these obtained in the work can make us better understand the mode of the action and pharmacological activities of the isoflavonoids.     

Investigation of RNA-Ligand Interactions by (19) F NMR Spectroscopy Using Fluorinated Probes

Spy swap: The interaction between an unlabeled RNA and unlabeled ligands (red hexagon) can be monitored by (19) F?NMR spectroscopy using small fluorinated diamines (green star) as spy reporters. This technique also enables the visualization of the conformational capture of a riboswitch by its ligand.     

Studies on the Coordination of Pr(Ⅲ) with Adrenaline by Potentiometry and Absorption Spectroscopy

AsanextensiontoourpreviousworkI'2,thecoordinati0n0fPr(III)withadrenaline(3,4-dihydroxy-a-(methylamin0methyl)baIcohol,(HO)=C,H,CH(OH)CH,NHCH,)hasbeeninvestigatedbypotentiometryandabsorptionspectroscopyinthepresentw0rk.PotentiometrictitrationswerecarriedoutonapHS-3CpHmeterunderbi0logicalconditions(37'Candanionicstrengthof0.l5m0l/LNaCl)byusingthetitrationtechniquesdescribedinprevi0uspapers3'4.TheabsorptionspectraofPr(lII)-adrenalinesystemwererec0rdedinvisibleregi0natvariouspHvalueswit…     

CeO2基固溶体氧缺位拉曼光谱表征的研究进展

总结了拉曼光谱表征CeO2基固溶体中氧缺位的研究成果,评述了氧缺位的生成和影响氧缺位浓度观察值的因素,并提出了亟待解决的问题.CeO2基固溶体的拉曼谱图中出现三个重要的特征拉曼峰(465、560、600cm-1),一般分别归属于CeO2的F2g振动模式、氧缺位和MO8型缺陷物种.研究发现氧缺位的产生与掺杂金属离子价态有关,而MO8型缺陷物种的产生与掺杂金属离子半径有关.CeO2基固溶体中氧缺位浓度观察值(AD/AF2g)与样品吸光度和表面富集有关.原位拉曼光谱研究表明:气氛及温度影响CeO2基固溶体的吸光度变化,从而影响拉曼光谱采样深度,导致氧缺位浓度观察值的变化.     

锰—铈复合氧化物催化剂表面氧的性质

氧化锰催化剂广泛用于一氧化碳常温氧化及汽车尾气的净化等,CeO_2是氧化物催化剂的优良助剂。非贵金属催化剂中添加CeO_2能提高催化剂的氧化活性已有很多报道,但有关Ce对氧化锰结构及表面氧脱附性能影响的研究尚不多见。本文运用XRD、DTA和TPD-MS等手段对共沉淀法制得的Mn-Ce复合氧化物进行了物相结构和脱氧活性研究。     

玻碳电极上DTAB对氧还原反应的促进作用

用旋转圆盘玻碳电极研究了阳离子表面活性剂十二烷基三甲基溴化铵(DTAB)对氧还原反应的影响. 结果表明, DTAB明显提高了玻碳电极对氧还原的电催化活性. 通过对氧还原电流与旋转速度的关系以及动力学电流与电位的Tafel关系分析, 发现DTAB提高了玻碳电极对氧还原反应电荷传递步骤的传递系数, 因此加快了氧还原的动力学过程.     

氧化铈对氧化锰表面氧脱附与恢复性能的影响

采用TPD-MS技术研究了Mn-Ce-O体系催化剂的表面氧脱附(供出)和恢复性能,并以甲醇氧化反应为探针考察了催化剂在不同气氛下的氧化活性。结果表明,氧化铈的存在并不影响氧化锰O₂-TPD特征峰的位置,但氧化锰表面的吸附氧数量明显增加,氧化锰表面吸附氧的恢复能力随氧化铈含量的增加而增大。催化剂对甲醇的氧化活性与其表面吸附氧数量有很好的对应关系。催化剂表面氧恢复能力越大,对甲醇的氧化活性受气相氧影响越小。     

Synthesis of PrBa2Cu4O8 by Solution Method under Ambient Oxygen Pressure

A highly homogeneous and nearly monophasic PrBa₂Cu₄O₈ compound has been synthesized at 1 atm of oxygen via a route employing polymeric ethylenediamine/citric acid precursors. The PrBa₂Cu₄O₈ compound with a trace amount of BaCuO₂ was synthesized for the first time by sintering the pellets at the temperature of 875 °C under ambient oxygen pressure. The temperature coefficient of the resistivity is positive below 190 K while above 190 K is negative. The superconducting transition was not detected down to 4.2 K. Samples were characterized by X-ray diffraction, scanning electron microscopy, thermal analysis, and transport and magnetic measurements.     

Oxygen species on NiO/Al2O3 and their reactivities

Oxygen species on fresh and treated NiO/Al₂O₃ and their activities for oxidation of ethane and ethylene were investigated using catalytic property measurements, ethane and ethylene pulse experiments and O₂–TPD–MS experiments. The results revealed that there are two kinds of active oxygen species (the more active one and the less active one) on fresh NiO/Al₂O₃ catalyst, but there is only one active oxygen species, the less active one, on treated NiO/Al₂O₃ catalyst. The more active oxygen species can convert ethane or ethylene to carbon dioxide by one step while the less active one can only convert ethane to ethylene, but cannot convert ethane and/or ethylene to carbon dioxide. The more active oxygen species can be removed from the catalyst by heating from 350 to 850 °C. The amounts of desorption oxygen on the catalysts are proportional to their selectivity to carbon dioxide.     

用尖晶石型化合物NiCo2O4和复合镀技术制备析氧电极

为减少析氧电位、提高电极的稳定性、降低能耗和成本，人们一直在努力合成各种过渡金属复合氧化物作为析氧的电催化材料［１］．研究表明，尖晶石型化合物ＮｉＣｏ２Ｏ４对氧的析出有较高的催化活性［２］．但因其制备方法多为喷涂热解法，需４００℃以上温度，因此易发生...