Electrical Conductivity Method Research Articles

Band gap engineering of MnO2 through in situ Al-doping for applicable pseudocapacitors

Band gap engineering was achieved by in situ doping method for high electrical conductivity and chemical activity of MnO2.

Genetic Algorithm Applying to Calculate the Great Wall Soil Water Electrical Conductivity

In this paper, we report a simple but effective algorithm to estimate the undetermined coefficients in the formula of soil water electrical conductivity value by the soil apparent electrical conductivity method. By doing so, the coefficients can be accurately obtained to further calculate the soil water electrical conductivity. According to the process of calculating the soil solution electrical conductivity based on the apparent conductivity of soil, the error of the calculation equation is effectively calculated by the two order curve fitting method. Meanwhile the genetic algorithm is adopted to reduce the influence of the data error generated by the proposed algorithm, and improve the accuracy of the data as well. The experimental results demonstrate that the solution by the proposed algorithm can be effectively obtained and the error change is in one direction simultaneously. With these advantages, we can use soil water electrical conductivity to calculate the content of soil salt.

Modified electrical conductivity test method for evaluation concrete permeability

Standard test method for bulk electrical conductivity (ASTM C1760) provides a rapid indication of the concrete's resistance to the penetration of chloride ions by diffusion. In this paper a new approach for assessing the bulk electrical conductivity of saturated specimens of hardened concrete is presented. The test involves saturating concrete specimens with a 5 M NaCl solution before measuring the conductivity of the samples. By saturating specimens with a highly conductive solution, they showed virtually the same pore solution conductivity. Different concrete samples yield different conductivity primarily due to differences in their pore structure. The feasibility of the method has been demonstrated by testing different concrete mixtures consisting ordinary and blended cement of silica fume (SF) and calcined perlite powder (CPP). Two standard test methods of RCPT (ASTM C1202) and Bulk Conductivity (ASTM C1760) were also applied to all of the samples. The results show that for concretes containing SF and CPP, the proposed method is less sensitive towards the variations in the pore solution conductivity in comparison with RCPT and Bulk Conductivity tests. It seems that this method is suitable for the assessment of the performance and durability of different concretes containing supplementary cementitious materials.

Synthesis and properties of tetrasiloxane Gemini imidazolium surfactants

Two tetrasiloxane Gemini imidazolium surfactants with methylene spacer groups ([Si4-s-Si4im]Cl2, s = 4, 6) were synthesized and characterized by 1H NMR and ESI-MS spectrum. The surface activity and thermodynamic properties in aqueous solution among three categories of surfactants, including [Si4-s-Si4im]Cl2, the corresponding monomer ([Si4mim]Cl) and hydrocarbon-based Gemini imidazolium surfactant ([C14-4-C14im]Cl2), were compared by surface tension and electrical conductivity methods. A series of surface activity parameters, including cmc, γ cmc, π cmc, pc20, Γ max and A min, and the adsorption isotherms were obtained from the surface tension plots. The results indicated that the tetrasiloxane Gemini imidazolium surfactant with the longer spacer group has the higher capacity to form micelles but lower efficiency to reduce surface tension. Besides, the cmc value of [Si4-s-Si4im]Cl2 was about one order of magnitude lower than that of [Si4mim]Cl. The tetrasiloxane-based surfactants have the higher capacity to low the surface tension than the hydrocarbon-based surfactant. The adsorption isotherms of the tetrasiloxane-based surfactants are similar to those of conventional hydrocarbon-based surfactants. The thermodynamic parameters of micellization process, namely, the standard Gibbs free energy (ΔG m θ), enthalpy (ΔH m θ) and entropy (ΔS m θ) originated from the electrical conductivity measurements at five different temperatures, suggested that the micellization of [Si4-s-Si4im]Cl2 and [C14-4-C14im]Cl2 is entropy-driven process whereas aggregation of [Si4mim]Cl is enthalpy-driven process at the whole investigated temperatures. The dynamic light scattering results indicate that the aggregation size of [Si4-4-Si4im]Cl2 (113.6 nm) is larger than [Si4-6-Si4im]Cl2 (101.7 nm).

A Quick Method for Determining Total Polar Compounds of Frying Oils Using Electric Conductivity

Oil qualities during 40 h unconsecutive frying process were analyzed by combined tradition chemical indexes and electric conductivity (EC), and the correlation between quality index of frying oil and total polar compounds (TPC) was also studied. The result shows that frying oil’s quality trends to deterioration with the extension of frying time. TPC was positively related to EC, acid value (AV), carbonyl value (CV), peroxide value (POV), and p-anisidine value (PAV) of frying oil. The correlation coefficient between TPC and other quality index decrease in the order of EC, AV, CV, POV, and PAV and were 0.9583, 0.9303, 0.9152, 0.7949, and 0.7082, respectively. EC has the highest correlation with TPC. Furthermore, repeated experiment showed that relative standard deviation ranged from 1.08 to 2.17 %, and there are no significant differences in TPC value by between traditional TPC method and EC method (P > 0.05). EC method could be a good selection to predict the TPC and discard point of frying oil.

In-site characterization of bed fluidity in a large gas–solid fluidized bed via electric conductance method

In various industrial applications in which a liquid is sprayed into a gas-fluidized bed such as Fluid CokersTM, fluid catalytic crackers and gas-phase polymerization reactors, parts of the bed or even the complete bed might become defluidized due to high liquid loading, agglomeration or sintering of particles. For instance, in Fluid Cokers, operating at lower temperatures increases the yield of liquid products and reduces sulphur emissions, but local defluidization may result in some bed regions with a disastrous impact on reactor operation. This loss of bed fluidity is called “bogging”.This study examines a novel method employing electrical conductance to detect local bogging in a large scale pilot fluid bed of about 7tonnes of silica sand. Bogging is induced by increasing the liquid load as well as by changing the atomization performance of a spray nozzle. Several other experimental methods, such as differential and static pressure measurements, image processing, and temperature measurements are evaluated.When liquid is injected into a fluidized bed, a fraction forms liquid–solid agglomerates while the remainder forms free moisture, consisting of individual particles coated with a thin layer of liquid. Liquid present as free moisture can be beneficial as it increases the mass and heat transfer processes and increases yields of valuable products. The results indicated that conductance measurements could be used for detecting bogging phenomena online. Bogging is shown to be directly associated with the local free moisture rather than the total moisture level. Increasing the atomization gas flowrate and, consequently, the free moisture, increases the bogging risk. A measurable critical, local free moisture value above which localized bogging occurs is identified.

Simultaneous determination of enthalpies of dilution and dissociation of protocatechuic acid in aqueous salt solutions by calorimetric measurements

Protocatechuic acid, a major metabolite of antioxidant polyphenols found in green tea, has been shown to prevent carcinogenesis or antitumor growth in vitro and in vivo studies. The dilution enthalpies ΔdilHm, dissociation enthalpies ΔdisHm and thermodynamic dissociation constants Ka for protocatechuic acid in aqueous NaCl or KCl solutions were simultaneously determined by mixing-flow microcalorimetry at T=298.15K. In order to verify the reliability of the fitted dissociation parameters, the values of dissociation enthalpies and thermodynamic dissociation constants were also determined by isothermal titration calorimetry and electrical conductivity methods. The Ka values obtained through the proposed method agree well with those reported in literatures and obtained by other techniques. Enthalpic interaction coefficients (h2, h3 and h4) were computed according to the McMillan–Mayer model. The trends of h2 and ΔdisHm for protocatechuic acid with increasing salt molality in both the salt solutions were obtained. The different influence of KCl and NaCl on the values of h2 and ΔdisHm were discussed in terms of (solute+solute) and (solute+solvent) interactions. The results showed that it is possible to perform in a single calorimetric experiment the simultaneous determination of dilution enthalpies, dissociation enthalpies and constants in a given solvent.

Study of the synthesis and crystallization kinetics of magnesium hydroxide

The crystallization kinetics of magnesium hydroxide in low concentration solutions has been studied using an electrical conductivity method. Using various experimental relationships, several kinetic factors could be determined during the nucleation and growth process. From measurements of ion concentrations at various temperatures, the induction period of nucleation could be determined. As concentration and temperature increase, the crystallization rate increases affecting the nucleation and crystal growth of Mg(OH)2. The crystal-solution interfacial surface tension was also calculated and shown to be affected by the magnesium anion source. The results show that a uniform particle size distribution of nuclei is formed during the initial homogeneous nucleation process and the nucleation and crystal growth rates can be represented by a first order reaction equation. Through the study of crystallization kinetics, a control strategy is proposed to synthesize a uniform particle size distribution of magnesium hydroxide.

Phase diagrams for pseudo-ternary system of {IPM (1) + [CTAB (21) + butan-1-ol (22)] (2) + water (3)} at temperature 303.15 K

The phase diagrams of the pseudo-ternary system {Isopropyl myristate (IPM) (1)+[hexadecyl-trimethyl-ammonium bromide (CTAB) (21)+butan-1-ol (22)] (2)+water (3)} at temperature 303.15K were constructed by visual observation and electrical conductivity methods. The effect of the mass ratio of CTAB to butan-1-ol (Km=m21/m22) and the water content on the phase diagram and on the microemulsion structure were discussed.

Experimental investigation of solute transport in unsaturated fractured rock

An experiment is designed to perform tracer tests in an unsaturated fractured rock with a horizontal fracture. Data from an intact and an artificial sandstone sample was collected and used to discuss the effect of the fracture on tracer migration. The delay time of the tracer in the fracture was further determined in terms of the fracture aperture involved. An alternative electrical conductivity (or electrical resistance) method was developed to measure the change in the tracer concentration with time and space. The method causes no disturbance to the flow and concentration fields, and is convenient to use. The test results show the fluctuations in the tracer concentrations and there were 2–3 peak values of concentration in the monitored sections related to the heterogeneity of the water content and pore distribution. Also, the fracture was found to delay migration of the tracer before it is filled with the tracer solution and quicken the velocity of migration afterwards. This results in accumulation of the tracer near the fracture. Furthermore, the delay time of the tracer increases with fracture aperture in a nonlinear manner.

Evaluation of the Ability to Control Biological Precipitation to Improve Sandy Soils

Biological soil improvement is a novel improvement technique in which chemical and biological processes leads to an improvement of physical and mechanical soil properties. Since this method is environmentally compatible and applicable to various soil types using different materials, it has turned into an efficient soil improvement method in numerous ground treatment projects. Microbiologically induced calcite precipitation (MICP) is one of the most well-known biological soil improvements method in which after the injecting bacterial suspension, reaction solution (cementation solution) into soil particles, calcium carbonate sediment is formed, and thereby soil properties are improved. In this paper, the ability to manage time and location when calcium carbonate sediments are biologically formed was investigated in sandy soil. The electrical conductivity method, unconfined compressive strength test and X-ray diffraction examinations were sequentially used to determine urease bacterial activity, measure the amount of the increased strength of treated soil and determine crystal type. The results showed good ability of this method to control time and location of biological precipitating. Furthermore, unconfined compressive strength of Caspian Sea coast sandy soil was increased up to 400kPa. The ability to manage time and location of biological precipitating indicates this method can be potentially used in different application such as mitigation of liquefaction, soil erosion control, immobilizing of pollutions in soil and other soil improvement projects.

Experimental Measurements of Particulate Matter Deliquescence and Crystallization Relative Humidity: Application in Heritage Climatology

Climate and pollution can lead to materials weathering. In this study, an innovative method is employed to evaluate the hazard for heritage stone substrates induced by the synergic effect of particulate matter (PM) and climate. In this respect, two hazard indicators for stone materials were determined: the time of wetness and the number of dissolution and crystallization cycles. The two indicators were computed by coupling experimental measurements of the PM deliquescence and crystallization relative humidity with climatic data. For the first time, these indicators were estimated based on the PM hygroscopic properties, considering its whole hysteresis loop and its consequent hydration level. The proposed method was applied to PM samples collected in the polluted Po Valley (Milan): the experimental measurements of both PM deliquescence and crystallization relative humidity were performed in an environmental-controlled chamber using an electrical conductivity method. The time of wetness and the number of dissolution and crystallization cycles were then calculated by coupling the PM deliquescence and crystallization relative humidity with climatic data of Milan over the last decade (2003–2013). Results point out that, depending on the seasons, different hazards were identified. In winter, high time of wetness (89 ± 11%) and low number of cycles (3 ± 3 cycles/month) were found. Conversely, summer was characterized by low time of wetness (20 ± 13%) and high number of cycles (11 ± 5 cycles/month). Interestingly, spring and fall resulted the most dangerous seasons for outdoor-exposed stones, since they presented both high time of wetness and number of cycles. Since the two indicators are calculated considering PM properties and climatic data, their values are site-specific, while the method used for their determination is of general application and it can be used for an efficient hazard assessment in a heritage climatology perspective.

Rapid methods for investigating salt concentration in soils : 1. Rapid survey method for soil electrical conductivity using electromagnetic measurements(Progress Review: Tsunami affected farmland)

Rapid methods for investigating salt concentration in soils : 1. Rapid survey method for soil electrical conductivity using electromagnetic measurements(Progress Review: Tsunami affected farmland)

Toxicity of Sumithion in Channa Punctatus: Biochemical and Hematological Studies

Introduction: Owing to their easy availability and accessibility, organophosphate and carbamates are the most commonly used pesticides worldwide in the pest control of crops. Acute toxicity and clinical manifestations of organophosphate pesticide are caused by excessive synaptic accumulation of acetylcholine (AChE). Objective: To analyze the biochemical parameters of serum cholesterol and hematological parameter of absolute erythrocyte count in fish Channa Punctatus exposed under organophosphate pesticide sumithion. Materials and Methods: This research study has been done in fish Channa Punctatus, which was exposed 24 to 96 hours to four different concentration of sumithion pesticide. Serum cholesterol was determined as biochemical biomarkers while absolute erythrocyte counts as hematological biomarker. Serum cholesterol was determined by zlatkis method (Zlatkis A; Zak B. and Boyale A. J. 1953)15. Absolute erythrocyte count was determined by electrical conductivity method of cell counting. Result: There was significant increase in serum cholesterol in Sumithion pesticide exposed, fish Channa Punctatus, comparative to normal control subject. The maximum rise of 18.93% (80.74 ± 78.56) in serum cholesterol was observed after exposure of 96 hrs at 0.40mg/l Sumithion pesticide. Toxicity of Sumithion resulted in decrease of absolute erythrocyte counts at all concentration of time intervals. Decrease was more pronounced with increasing time of exposures. The lowest erythrocyte count was 57.24% below control at the highest concentration of 0.73mg/L within 24hrs. Conclusion: Results of our study indicates that hypercholesterolemia & decreased level of erythrocyte count in fish channa punctatus exposed under sumithion pesticide are biochemical & hematological biomarker for human beings also. Therefore it is advised to pesticide workers to take all precautions regarding protection from pesticide exposure and proper use of prophylactic supplementation for their healt

New analytical method for electric current and multiple delamination cracks for thin CFRP cross-ply laminates using equivalent electric conductance

Carbon fiber reinforced polymer (CFRP) composites have low inter-lamina strength. One of the monitoring technologies is a self-sensing method that uses the electrical resistance change of a CFRP structure for detecting damage. The electric current distribution is vital information for the self-sensing method when optimizing the arrangement of probes to measure electric potential changes. We have developed a new orthotropic electric potential function analysis approach using affine transformation for unidirectional CFRP. In this study, the orthotropic electric potential function analysis method is improved to calculate the electric current of a thin cross-ply CFRP. Two types of stacking sequences for the beam-type cross-ply laminates were calculated to confirm the effectiveness of the improved method. The electrical voltage changes caused by multiple delamination cracks of a cross-ply laminate are new outcomes of this study. The analytical results were compared with computed results using the finite difference method. Consequently, the new equivalent electric conductance method proved to be effective for calculations of the electric current density of a cross-ply CFRP laminate. Furthermore, the new method for calculating the electric potential difference changes caused by multiple delamination cracks using orthotropic distributed doublet analysis, with the equivalent electric conductance, has also proved to be effective.

Effect of Sintering on Co-precipitated Nanoparticles of Mn Ferrite

Soft ferrites are useful for various applications due to their high resistivity and low eddy current losses. Nanoferrites of manganese (MnFe2O4) were prepared by chemical co-precipitation method. Synthesis conditions were optimized for phase purity. The prepared MnFe2O4 were characterized by using X-ray diffraction (XRD) and AC and DC measurements for electrical conductivity and advantageous transient plane source (ATPS) method for thermal transport properties (thermal conductivity, thermal diffusivity, and volumetric heat capacity). The XRD results confirmed the spinel structure of as-prepared nanoferrites. Samples were sintered at 750°C for 2 h, and after sintering, the structure of the material changed from spinel to garnet. The sintering procedure was repeated for five times and its effect was observed on Mn ferrite nanoparticles. These materials are useful for various purposes of applications, e.g., as a core material to increase the efficiency of switch-mode power supply (SMPS). Using data of DC electrical resistivity as a function of temperature, activation energy was calculated. Thermal transport properties of the synthesized samples are reported and these are rarely found in literature.

Characteristics of calcined natural zeolites for use in high-performance pozzolan blended cements

Two natural zeolites with different characteristics were calcined at various temperatures in order to improve the benefits provided by their use in blended cements as cement replacement material. Natural zeolites were firstly characterized for their crystallinity by X-ray diffraction analysis, specific surface area by nitrogen absorption, and pozzolanic activity by electrical conductivity method, before and after the calcination. In order to assess the performance of calcined natural zeolite as cement replacement material, blended Portland cement pastes and mortars with raw and calcined zeolites were tested for their water requirement, free lime content, pore size distribution and compressive strength. The experimental results indicated that calcined zeolites are more desirable with lower water requirement and higher strength performance as cement replacement material than the raw zeolites. Blended cement with calcined natural zeolite showed higher compressive strength performance, when compared to that with the raw zeolite due to decreased porosity and refined pore structure of the hardened cementitious system.

Synthesis and Surface Properties of Novel Gemini Imidazolium Surfactants

AbstractFive new Gemini imidazolium surfactants were synthesized from imidazole and 1‐bromoalkane (C8, C10, C12, C14, C16) to get 1‐alkylimidazole, which was further reacted with 1,3‐dichloropropan‐2‐ol to form the surfactant molecule, 1,1′‐(propane‐1,3‐diyl‐2‐ol) bis(3‐alkyl‐1H‐imidazol‐3‐ium) chloride. The structures of the five new surfactants and intermediates were characterized by 1H‐NMR, 13C‐NMR and IR spectra. Thermal properties of the five new surfactants were studied with thermogravimetric analysis and differential scanning calorimetry, the five new surfactants showed a transition from a crystalline phase to a thermotropic liquid–crystalline phase at around ca. 100 °C, which transformed to an isotropic liquid phase at around ca. 165 °C. The five new surfactants critical micelle concentrations (CMC) in the aqueous solutions were determined by surface tension and electrical conductivity methods. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γCMC), adsorption efficiency (pC20), and effectiveness of surface tension reduction (πCMC). In addition, with application of the Gibbs adsorption isotherm, maximum surface excess concentration (Γmax) and minimum surface area/molecule (Amin) at the air–water interface were obtained. The parameters β (degree of counterion binding to micelles), ΔGadsθ (Gibbs free energy of adsorption), and ΔGmicθ (Gibbs free energy change of micellization) were also derived. The results indicated that the five new Gemini surfactants exhibited very low CMC and a good efficiency in lowering the surface tension of water. The foamability and foam stability of the five new surfactants were also examined at different CMC.

Study of interaction between cationic surfactants and cresol red dye by electrical conductivity and spectroscopy methods

Interaction of anionic dye, cresol red (CR), with cationic surfactants, dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB), in aqueous solution in the submicellar and micellar concentration ranges has been investigated by using thermodynamic and spectroscopic methods. The equilibrium model has been used to calculate the standard free energy (∆Gmo), enthalpy (∆Hmo), and entropy (∆Smo) of micelle formation. The increase in the critical micelle concentration (cmc) with rise in temperature is attributed to the disruption of the structured water surrounding the hydrophobic groups of the surfactants. A marked decrease in the cmc is observed as the number of carbon atoms in the hydrophobic group increases from DTAB to CTAB. Higher values of the degree of ionization (α) of the micelles of DTAB and CTAB are obtained in the presence of CR than in its absence. Negative values of ∆Gmo and ∆Hmo for the surfactants in aqueous and in aqueous CR solutions show that the process of micellization is thermodynamically spontaneous and exothermic. The values of −T∆Smo are much higher than the ∆Hmo values, indicating that the micellization process is governed primarily by the entropy gain associated with it. The heat capacity of micellization (ΔCp,mο) is negative which is mainly due to the change in the exposure of the hydrophobic groups to the water molecules. UV–visible spectra suggest interaction between dye and surfactant monomers forming ion-pair complex in the pre-micellar region whereas above the cmc solubilization of dye in the micelle dominates over ion-pair formation.

Phase Diagrams for the Pseudoternary System of {Hexane (1) + [Hexadecyltrimethylammonium Bromide (21) + Butan-1-ol (22)] (2) + Water (3)} at a Temperature of 303.15 K

The phase diagrams of the pseudoternary system {hexane (1) + [hexadecyltrimethylammonium bromide (CTAB) (21) + butan-1-ol (22)] (2) + water (3)} at a temperature of 303.15 K were constructed by visual observation and electrical conductivity methods. The effect of the mass ratio of CTAB to butan-1-ol (Km = m21/m22) and the water content on the phase diagram and on the microemulsion structure were discussed.