碳纤微电极及探头的噪声分析

安培法碳纤微电极放大器主要应用电化学原理对单个细胞分泌事件进行检测,这种检测获得的pA级微小电流信号极易受各类噪声影响.文章主要介绍在设计和使用安培法碳纤微电极放大器时如何克服各类噪声影响的问题,并建立了碳纤电极及探头的噪声理论模型,分析了噪声来源类型和各自特点,提出了降低噪声的方法和措施.     

NO在多壁碳纳米管修饰电极的电氧化行为

为研制生物医学和环境检测的NO电化学传感器,用碱和硝酸对多壁碳纳米管(MWCNTs)进行功能化.采用循环伏安法(CV)和电化学阻抗法(EIS)研究NO在多壁碳纳米管修饰电极上的电氧化行为,并探讨相应的反应机理.研究结果表明:当氧化电位较低(0.50～0.65 V)时,NO的电氧化受电极电位驱动,氧化速度随着电极电位的升高而加快;当电极电位达到一定值(0.70～0.80 V)时,其电极反应受电荷转移和扩散混合控制;当电极电位较高(0.85 V)时,NO的电极反应受扩散控制;与MWCNTs修饰电极相比,MWCNT-COOH修饰电极上反应的活化能(氧化峰电位)明显降低,其峰电流密度(反应速度)是MWCNTs修饰电极的1.4倍,说明MWCNT-COOH修饰电极能够有效地提高NO氧化的电催化活性和检测灵敏度.     

阳极扫描极化反向催化伏安法测定α-生育酚

用阳极极化的方式在银电极表面形成氧化银纳米粒子,继而以循环电位扫描方法将羧基化石墨烯沉积到该电极表面,成功制备了石墨烯/纳米氧化银/银电极,并应用于碱性溶液中α-生育酚的检测.采用循环伏安法分别对修饰电极和α-生育酚在修饰电极上的催化氧化行为进行了研究.并使用该修饰电极,利用阳极扫描极化反向催化伏安法检测了α-生育酚.实验结果表明,该修饰电极性能稳定,方法灵敏度高,差值峰电流与α-生育酚浓度分别在0.02~0.32μmol/L和0.32~4.0μmol/L范围内存在线性关系,方法检测限达到0.01μmol/L.     

石墨烯在金电极上固定方法的选择及免疫传感器的构建

分别利用重氮化法、滴涂法、非共价键合法及偶联法将石墨烯固定于电极表面,并对所得到的修饰电极进行电化学表征,分析结果显示重氮化法制备的石墨烯修饰电极性能更稳定,信号更灵敏,所以将其用于免疫传感器的制备.首先在金电极上制备对氨基苯硫酚和苯硫酚的混合自组装单分子膜(MSAM),再利用重氮化法将石墨烯固定在MSAM修饰电极表面,然后在其表面电沉积纳米金,最后通过金-氨键固定抗体(羊抗小鼠IgG),并对小鼠IgG进行了初步检测,线性范围为0.001～400μg/L,检测下限达到0.0014μg/L.结果表明,该传感器具有检测范围宽、灵敏度高的优良性能,在临床检验中具有广阔的应用前景.     

掺硼金刚石薄膜电极在检测抗坏血酸中的应用

采用掺硼的金刚石薄膜电极作为工作电极,对底液为1.0 mol/L的KCl溶液中的抗坏血酸进行了循环伏安以及阳极溶出法进行了检测.得到检测限为6.4×10-6mol/L,线性范围为8.0×10-6mol/L~3.1×10-4mol/L,相关系数为0.978.实验结果表明应用掺硼金刚石薄膜电极与其他电极的检测结果相差不大,且在电极再生性方面存在巨大的优势,使电极寿命更长,具有极好的应用前景.     

基于微创式电阻抗增敏测量的乳腺癌模型电场分析

生物电阻抗法对乳腺癌进行早期检测是非常有效的方法,但是在检测过程中由于角质层的高阻抗性使得目前广泛使用的表面电极产生很大的接触阻抗,造成测量误差,严重影响测量精度,是阻抗法进行乳腺癌早期诊断走向临床应用的最大制约因素之一.文中将微机电系统微针电极作为测量电极应用于乳腺癌早期检测,采用介入微创模式测量生物电阻抗,针对不同的电极-皮肤接触模式、电极接触面积、瘤体浸润位置和瘤体大小等不同影响因素进行数值仿真,结果表明微针电极采用微创介入式检测方法,跨越了角质层大幅降低了接触阻抗的影响,在乳腺癌早期检测中有较明显效果,能够提高乳腺癌早期检出率.     

4-羧基苯基共价修饰玻碳电极检测药物分子

将裸玻碳电极置于含有氨基前驱体的NaNO2酸性水溶液中,通过电化学还原的方法将4-羧基苯基(4-CP)共价修饰到玻碳电极表面.在36.8℃和pH=6.76的缓冲溶液中,通过线性扫描伏安法(LSV),用4-CP修饰的玻碳电极分别及同时检测扑热息痛(PCT)、阿司匹林(ASP)和咖啡因(CF),并分别获得了它们的校准曲线.结果表明,4-CP修饰的玻碳电极能分别及同时长期稳定的检测PCT和ASP,但是每次检测CF时电极都需要重新修饰.     

石墨烯/聚嘧啶复合膜修饰电极用于甲基对硫磷的电化学测定

采用一步电沉积法制备了石墨烯/聚嘧啶复合膜修饰电极.利用循环伏安法和方波伏安法研究了甲基对硫磷在该复合膜电极上的电化学行为.结果表明,该复合膜对甲基对硫磷具有灵敏度高、响应速度快等特点.在最佳条件下,甲基对硫磷的峰电流响应与其浓度在0.000 3～2.5 μmol/L范围内呈现良好的线性关系,检测限为0.05 nmol/L.该石墨烯/聚嘧啶复合膜修饰玻碳电极也表现出良好的稳定性、重现性和抗干扰能力,并可用于实际样品的检测.     

双衬层填埋场防渗层渗漏定位算法的研究

分析了利用高压直流电法进行防渗层渗漏定位的影响因素,指出了在回路电流一定的情况下,检测层异侧供电电极的位置对渗漏的定位没有影响,检测层同侧的供电电极与漏洞的水平距离越大越有利于检测,检测电极越靠近被检测层越有利于检测,而参比电极的位置不影响定位的精度.提出了利用层状介质模型的解析结果拟合其检测层电势分布规律曲线,利用检测到的电势分布来预判漏洞,在预判漏洞区基于局部最小二乘算法来反演定位漏洞的定位算法,并指出由于仪器检测精度和定位精度的限制,检测电极间距不能太大,在漏洞电流为80 mA,检测电极间距为2～4m的情况下,选取包围预判漏洞的7个点来定位漏洞的定位误差最小.     

氨基化溶胶-凝胶免疫电极检测乳腺癌抗原

利用氨基化溶胶一凝胶(sol-gel)的材料优势，结合交联固定技术，实现了乳腺癌抗体在电极表面的固定化，研制成用于检测乳腺癌抗原的非标记型Sol-gel/GA/抗体膜免疫电极。用红外光谱法和循环伏安法对电极的修饰过程进行表征。该法更好地保持了被固定抗体的活性，增强了免疫电极的稳定性，可用于生物环境中乳腺癌抗原的检测。     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the