Conductance of KCI-Glycerol Solutions: Test of the Fuoss Paired Ion Model

Abstract

The electrical conductance of KC1 in glycerol solutions has been measured at concentrations between 1.5 mol m^?3 and 353 mol m^?3 at 22°C. The results are compared with the Fuoss paired ion model and fits to the data are obtained assuming a Gurney co-sphere having a radius in the approximate range 6 ± 10^?10 m to 9 ± 10^?10 m. The model leads to an estimate of ionic association which is less than that given by the theory of Bjerrum.     

Z形石墨带的电子输运性质: 形状与尺寸效应

基于格林函数方法及Landauer-Büttiker公式, 研究了纳米石墨带异质结的电子输运性质, 石墨带异质结由Z 形石墨带与两个锯齿型石墨带电极构成. 研究发现电导大小依赖其几何构型. 由于电子局域在锯齿型石墨带边缘, 因此在费米能级附近出现了电导隙或电导谷. 调节结间石墨带的宽度, 发现准束缚态的存在诱导许多尖锐的电导峰, 电导峰的数目几乎与结间的石墨带长度无关. 在低能区, 当θ为60°或150°时, 宽度均匀的Z型石墨带仍然保持弹道输运特征. 因此, Z形纳米石墨带可选择地应用于未来的纳微电路.     

Synthesis,identification and study of electrical conductivity of the doped poly aniline

Poly aniline and poly aniline doped with 2,5-dimethyl benzene sulfonic acid (PXSA), 4-hydroxy-m-benzene disulfonic acid (PDSA), 3-chloro-4-hydroxybenzene sulfonic acid (OCPSA) were prepared. The polymers are identified by FT-IR and UV–vis spectroscopy. The ionic conductivities of poly aniline and poly aniline doped with 2,5-dimethyl benzene sulfonic acid (PXSA), 4-hydroxy-m-benzene disulfonic acid (PDSA), 3-chloro-4-hydroxybenzene sulfonic acid (OCPSA) were studied as a function of weight of the dopant compounds. It is noted that an increase of the conductance of poly aniline by doping with OCPSA, and became equal to 0.001321 Ω^?1 for 1 g higher than the conductance for the poly aniline when it is doped with OCPSA.     

Numerical modelling of unsteady convective–diffusive heat transfer with a control volume hybrid method

Presented in this paper is a numerical methodology for the solution of the parabolic governing partial differential equation that describes unsteady advection–diffusion heat transfer. The formulation presented here is shown to be free from the numerical oscillation commonly associated with advection–diffusion heat transfer regardless of the value of the Peclet number. The formulation involves the absorption of the advection term in the unsteady heat equation into the capacitance term. This process is achieved with the use of a control volume methodology applied to each nodal element on a finite-volume mesh. This is shown to ensure that spurious energy losses and gains are avoided and provides for consistency between temperature and energy change. This approach provides unconditional stability and it is shown that good accuracy is achievable with relatively large time-steps.     

α-Fe_2O_3掺杂对In_2O_3电导和气敏性能的影响

用化学共沉淀法制备了α－Ｆｅ２Ｏ３掺杂的Ｉｎ２Ｏ３纳米晶微粉,研究了α－Ｆｅ２Ｏ３掺杂对Ｉｎ２Ｏ３电导和气敏性能的影响．结果表明,α－Ｆｅ２Ｏ３和 Ｉｎ２Ｏ３间可形成有限固溶体Ｉｎ２－ｘＦｅｘＯ３（０≤ｘ≤０．４０）;Ｆｅ３＋对 Ｉｎ２Ｏ３晶格中Ｉｎ３＋格位的部分取代,大大增强了阴阳离子间的结合力,导致材料中氧空位Ｖｏｘ数骤降、自由电子的浓度变稀和电导下降．ｎ（Ｆｅ３＋）：ｎ（Ｉｎ３＋）＝５：５的共沉淀粉于 ８００℃下灼烧 ４ ｈ所得的 α－Ｆｅ２Ｏ３掺杂Ｉｎ２Ｏ３传感器元件,对 ４５μｍｏｌ·Ｌ－１Ｃ２Ｈ５ＯＨ的灵敏度达５４．０,为相同浓度干扰气体汽油的８倍多．     

On the voltage sensitivity of current in electronic transport

The sensitivity of current-to-voltage is treated by defining an adequate parameter useful for a wide variety of cases within the context of ballistic electron transport. This parameter may be conceived as a normalized conductance which is studied in relation to electronic density of states.     

Concentration-dependence of faradaic currents and conductivity in a polystyrene sulfonic latex suspension

The conductivity, κ, in a suspension of polystyrene sulfonic latex without supporting electrolyte showed a linear dependence on the volume fraction, v_f, of the latex for v_f<0.03 with a finite intercept. In contrast, this deviated upward from the linear line for v_f>0.03. These variations were qualitatively consistent with the dependence of the voltammetric reduction current of H⁺ on v_f without supporting electrolyte. The current values were only a few percent of the theoretical diffusion-controlled current that could be observed in the suspension with supporting electrolyte. This fact indicates the electrostatic immobilization of the hydrogen ions by sulfonic latex particles. A plot of the current against κ at common values of v_f showed that the current for v_f>0.07 was smaller than the value predicted from the conductivity. This can be explained in terms of a combination of the increase in electrostatically unbounded H⁺ estimated by conductance measurements and electric migration in which the electrochemical depletion of [H⁺] also causes the depletion of the latex.     

镁掺杂对In2O3电导和气敏性能的影响

用共沉淀法制备了Mg2 + 掺杂的In2 O3 纳米粉 ,研究了镁掺杂对In2 O3 电导和气敏性能的影响 .结果表明 :MgO和In2 O3 间可形成有限固溶体In2 -xMgxO3 (0≤x≤ 0 .40 ) ;MgIn× 电离的空穴对材料导带电子的湮灭 ,使掺镁纳米粉的电导变得很小 ;n(Mg2 + )∶n(In3 + ) =1∶2共沉淀物于 90 0℃下热处理 4h ,用所得的纳米粉制作的传感器在 32 0～ 370℃下 ,对 45 μmol/LC2 H5OH的灵敏度达 10 2 .5 ,为相同浓度干扰气体Petrol的 12倍多 .     

高效毛细管电泳电导法快速检测复方维生素B片中的VB1、VB12、VB6和VC

采用高效毛细管电泳电导法同时分离、测定了复方维生素B片中的主要成分VB1, VB12,VB6和VC的含量.研究了运行缓冲溶液的酸度和浓度、电泳电压、进样时间等因素对电泳的影响.在优化的实验条件下40 mmol/L Tris -4 mmol/L H3BO3 (pH 8.0) 的缓冲溶液中加入0.30 mmol/L CTAB(溴化十六烷基三甲基铵),分离电压为15 kV,上述4组分在5 min内得到良好的分离.维生素B1,B12,B6和VC的线性范围分别为5.5～1.0 mg/mL; 15～1.5 mg/mL; 1.0～0.40 mg/mL和6.6～0.80 mg/mL; 检测限分别为0.80 μg/mL, 4.0 μg/mL, 0.50 μg/mL, 2.9 μg/mL; 5次测定峰高的相对标准偏差分别为2.2%, 1.6%, 3.9%, 2.8%.5次测定的平均回收率分别为99%, 94%, 100%, 97%.     

Thermodynamic dissociation constants of salicylic and monochloroacetic acids in mixed solvent systems from conductance measurements at 25°C

The molar conductances of dilute solutions of salicylic and monochloroacetic acids in binary mixtures of methanol, ethanol, 1-propanol, N,N-dimethylformamide, acetone, acetonitrile, tetrahydrofuran and dioxane with water have been measured at 25°C. The Lee-Wheaton conductance equation was fitted to the data in order to derive thermodynamic dissociation constants and limiting molar conductances. The results were compared with those in the literature pertaining to analogous media, mostly derived potentiometrically. The findings are interpreted in terms of a solvent effect on the ionization of these acids in mixed solvent systems.This paper is dedicated to the late Professor Raymond M. Fuoss on his 3^rd anniversary.