间对硝基苯酚异构体的电化学测定及取代机理研究

制备了单壁碳纳米管修饰玻碳电极(SWCNT/GCE),采用伏安法研究了间、对硝基苯酚异构体在修饰电极上的电化学行为,分别观察到间硝基苯酚(m-NP)和对硝基苯酚(p-NP)的准可逆氧化还原峰,两物质氧化峰电位差为0.192V,说明间、对硝基苯酚异构体可在SWCNT修饰电极上同时测定.采用线性扫描伏安法优化了硝基苯酚同分异构体电化学响应条件.优化条件下,m-NP在浓度2.7×10~(-6)~1.0×10~(-4)mol/L范围内,其峰电流(Ip)和浓度呈线性关系;p-NP在浓度2.0×10~(-6)~1.0×10~(-4)mol/L范围内,Ip和浓度呈线性关系.两者的Ip都与扫速(v)成线性关系,这说明它们在修饰电极上的电化学过程均与吸附传质有关,电极过程是受吸附控制.基于Nicholson方法,获得m-NP和p-NP的电极反应速率常数(kS),并用Hammett方程计算出Hammett反应取代常数ρ.     

纳米金修饰电极上苯二酚的电催化及分析应用

利用恒电位沉积方法将HAuCl4直接还原成纳米金并沉积到玻碳电极表面。制备了对苯二酚异构体具有不同电催化作用纳米金修饰电极。在PBS缓冲溶液中,通过循环伏安法研究了苯二酚异构体及其混合物在纳米金修饰电极上的电化学行为,结果表明。苯二酚异构体在纳米金修饰电极上具有不同的电化学性质。对苯二酚和邻苯二酚在纳米金修饰电极上出现峰型良好的氧化还原峰,而间苯二酚几乎不产生氧化还原峰。比较对苯二酚和邻苯二酚在纳米金电极的的氧化还原峰。两者峰电位有较大区别,相互之间没有干扰,据此建立同时测定苯二酚混合物中的对苯二酚和邻苯二酚分析方法。     

金纳米粒子二维有序阵列的构筑和电化学性质

在水溶液中用柠檬酸钾还原氯金酸的方法合成了粒径为30～40nm的金纳米粒子,并用透射电镜和紫外可见光谱进行了表征;然后在表面经PVP修饰的导电玻璃上以自组装的方式构筑了金纳米粒子的二维有序阵列,并用扫描电镜和紫外可见光谱进行了表征;以所制备的金纳米粒子二维有序阵列作为电极,对硝基苯酚的电化学响应得到明显提高,金纳米有序阵列电极有望成为检测废水中对硝基苯酚的电化学传感器.     

石墨烯/纳米纤维素/亚甲基蓝修饰电极的电化学行为研究

采用电化学还原法在玻碳电极上直接制备了石墨烯/亚甲基蓝(GR/MB)﹑石墨烯/纳米纤维素(GR/NCC)﹑石墨烯/纳米纤维素/亚甲基蓝(GR/NCC/MB)修饰电极,研究了不同修饰电极的循环伏安行为.研究表明:相比GR/MB电极,GR/NCC/MB修饰电极对亚甲基蓝的电化学活性要高,氧化还原峰电流值可达4~5倍.其扫速的平方根与峰电流成线性关系.当石墨烯与纳米纤维素的质量比达到1.00∶4.60到1.00∶5.75时电化学活性最高.纳米纤维素和电化学还原的石墨烯通过协同作用增加亚甲基蓝的吸附能力,从而使GR/NCC/MB修饰电极表现出优异的电化学性能.     

硝基苯在纳米-γ-氧化铝修饰电极上的电还原特性

研究了硝基苯在纳米-γ-氧化铝修饰电极上的电化学行为,讨论了修饰剂用量、支持电解质溶液及其酸度、扫描速率、静置时间等因素对硝基苯电还原特性的影响,探讨了硝基苯在中性电解质溶液中的电还原机理.实验结果表明:纳米-γ-氧化铝修饰电极能显著提高硝基苯的还原峰电流,在-0.6～0 V电位范围内,硝基苯在该修饰电极上有一对准可逆氧化还原峰,随着pH增加,硝基苯的还原峰电位朝负电位方向移动.     

基于金-钯纳米粒子/石墨烯修饰电极测定药剂中的对乙酰氨基酚

利用电化学方法在石墨烯表面上沉积金-钯纳米粒子,制备了金-钯纳米粒子/石墨烯修饰玻碳电极.扫描电子显微镜和X-射线能谱仪对修饰电极组装过程进行了表征.采用循环伏安法研究了对乙酰氨基酚在修饰电极上的电化学行为,在p H 7.0的磷酸盐缓冲溶液中,对乙酰氨基酚在修饰电极上出现一对明显的氧化还原峰,其氧化还原峰电位分别为0.334V和0.299V.在最佳条件下,对乙酰氨基酚的氧化峰电流与其浓度在5.0×10-7-1.0×10-4mol/L范围内呈良好的线性关系,检出限(S/N=3)为1.0×10-7mol/L.利用该方法对药片中的对乙酰氨基酚含量进行检测,获得的结果令人满意.     

基于PbO_2电极电化学降解对硝基苯酚的研究

本工作采用电化学方法,制备钛基PbO2电极,用于对硝基苯酚溶液进行电化学降解.考察了溶液pH值、电流强度、支持电解质浓度等因素对对硝基苯酚去除率的影响,确定了对硝基苯酚电化学降解的最佳反应条件,并就对硝基苯酚的电化学降解历程进行了简要分析,提出了对硝基苯酚的可能降解途径.     

多壁纳米碳管修饰电极的制备及表征

报道了一种多壁纳米碳管修饰电极的制备方法并表征了它的电化学特性.经酸处理后的纳米碳管表面有碳酸根基团存在,当它被修饰到电极表面时会产生一对氧化还原峰.该修饰电极对发生在它表面上的电极反应具有明显的促进作用;对生物物质多巴胺的氧化还原具有稳定的电催化作用.     

纳米Al2O3修饰电极对3-硝基苯甲醛缩氨基硫脲的电催化氧化还原

运用多种电化学方法, 对3 硝基苯甲醛缩氨基硫脲在纳米 Al2O3 修饰玻碳电极(NA/GCE)及碳糊电极(NA/CPE)的电化学性质进行了研究. 结果表明, 3 硝基苯甲醛缩氨基硫脲在修饰电极上发生了电催化反应, 在 40 mmol/LTris HCl 0 1 mol/L KCl(pH=7 3)的缓冲溶液中, 0~0 45 V电位范围内, 3 硝基苯甲醛缩氨基硫脲在NA/GCE上有一对准可逆氧化还原峰, 式量电位(E°′)为 0 22V. E°′随 pH 增加而朝负方向移动, 在 pH 6 18~10 0 的范围内,其线性回归方程为E°′=0 6785-0 0589 pH, r=0 9987. 电极反应的电子数为 1 且有 1 个质子参与. 电极反应速率常数ks 为4 3088 s-1, 扩散系数D为2 54×10-3 cm2/s.     

尺寸稳定性阳极催化电极降解对硝基苯酚的研究

对硝基苯酚是一种芳香族的急性剧毒有机污染物,不仅危害大而且来源广泛,众多行业产生的污水中都包含对硝基苯酚。为了找到一种适合的DSA阳极来高效率地降解对硝基苯酚,对四种不同材料的阳极电极(钌铱钛(Ti/TiO_2-IrO_2-RuO_2)、钌铱钛锡(Ti/TiO_2-IrO_2-RuO_2-SnO_2)、铱钽钛(Ti/TiO_2-Ta_2O_5-IrO_2)和铱钽钛锡(Ti/TiO_2-Ta_2O_5-IrO_2-SnO_2))分别降解对硝基苯酚模拟废水的产物进行了研究。通过紫外分光光度法测定不同时间段的降解产物在最大吸收波长处的吸光度,比较四种阳极电极对对硝基苯酚模拟废水降解效果的优劣,结果显示涂层含有铱钌钛元素的电极对对硝基苯酚的降解效果最佳。由此讨论电极涂层材料在降解过程中所起的作用,提出电极的降解机理。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that