Initial Electrical Conductivity Research Articles

Efficiency of hydrogen peroxide production by ac capillary discharge in water solution

Efficiency of hydrogen peroxide production by an ac driven underwater capillary discharge was investigated quantitatively. The concentration of formed hydrogen peroxide was measured by a colorimetric method using a specific reaction between H2O2 and a titanium reagent. The amount of formed H2O2 increases linearly during the first hour of the discharge duration. The initial rate and corresponding total energy yield of H2O2 formation by the capillary discharge were determined for initial electrical conductivity of aqueous solution in the range of 100–500 µS cm−1 and average applied power in the range 30–90 W. It comes out that the total energy yield of H2O2 formation, derived from the initial rate of H2O2 formation and the average applied power, increases linearly with average applied power and that solution conductivity has only a negligible effect on the energy yield. A maximum total energy yield of H2O2 formation of 0.9 g kWh−1 was obtained for a 500 µS cm−1 aqueous solution.

Hydrogen peroxide production in capillary underwater discharges

Hydrogen peroxide production by an AC driven capillary underwater discharge was investigated quantitatively. Concentration of formed hydrogen peroxide was measured by a colorimetric method using a specific reaction between H2O2 and a titanium reagent. It comes out that the amount of H2O2 increases linearly during the first hour of the discharge duration and is slightly higher at the high voltage side of the capillary. The initial rate of H2O2 formation by the capillary discharge was therefore determined for initial electrical conductivity of aqueous solution in the range of 100 ÷ 500 µS cm−1. The initial rate of H2O2 formation increases with applied power at fixed initial conductivity of aqueous solution. Experiments performed at fixed applied power indicate that the initial conductivity appears to have only negligible effect on the initial rate of H2O2 formation.

Influence of electric current density on the bactericidal effectiveness of pulsed electric field treatments

A procedure applying equivalent pulsed electric field (PEF) treatments of similar peak electric field intensity, total treatment time, and treatment temperature, while delivering different amounts of electric current, was successfully developed in this study. Listeria innocua suspended in McIllvaine buffer was subjected to five PEF treatments, each with a peak electric field intensity of 28.85 kV/cm applied for 60 μs at 44.3 °C, with peak electric currents of 1.94, 2.20, 2.76, 3.51, and 4.21 kA, respectively. To apply the described treatments, the charge voltage, pulsing frequency, and initial temperature and electrical conductivity of the treated media were adjusted, based on calculations made using pertinent fundamental mathematical models. Neither the amount of electric current flowing through the treated product, nor the amount of delivered electric energy or the electric conductivity of the studied media showed any influence on the bactericidal effectiveness of the applied treatments within the studied range.

Electrical Conductivity and Redox Behaviour of Yttrium-Substituted SrTiO3: Dependence on Preparation and Processing Procedures

The electrical conductivity and redox behaviour of 10 mol% yttrium-substituted SrTiO 3 (with and without 5 mol% Co co-substitute at Ti site) were studied in relation to their potential use as alternative redox-stable anode materials. The P O2 at which the samples experience a high temperature process (e.g., sintering) determines the initial electrical conductivity, and the conductivity under the proposed application conditions is then determined by the re-equilibration kinetics. Due to the slow ionic transports on both anion and cation sublattices during the re-equilibration, it is practically difficult to obtain the true equilibrium conductivity values. Therefore the property of a sample depends to a very large extent on its particular history. Porous and fine-grained samples indeed show much faster re-equilibration kinetics than dense and coarse-grained samples. While the initial electrical conductivities of high-temperature reduced samples are quite high, some extent of degradation is observed upon redox cycling, which is worth further investigation.

Influence of solvent on temperature and thermal peak broadening in capillary zone electrophoresis.

The present paper deals with the role of the solvent on thermal peak broadening. One main solvent property that determines the magnitude of the temperature gradient due to the generation of Joule heat in capillary zone electrophoresis is the thermal conductivity. As organic solvents have lower thermal conductivity than water (methanol and acetonitrile, e.g., nearly by a factor of 3) it can be hypothesized that the temperature gradient inside the capillary is more pronounced in organic solvents compared to an aqueous solution. On the other hand, the temperature dependence of the ion mobility (which is responsible for the velocity profile and thus for thermal peak broadening) is smaller in organic solvents. To get insight into the thermal effect of the solvent, first the temperature of a solution in a cylindrical tube was calculated utilizing the heat balance equation. It was shown that the two theoretical models most common in the literature (based on the analytical solution or on an assumption of the parabolic temperature profile in the tube, respectively) give the same results. The latter model was chosen for the further calculations, adding a quadratic term to express the electric conductivity as a function of the temperature. The temperature at the inner capillary wall and center as function of the capillary dimensions and the electric power was computed for electrolytes with a given conductivity at 25.0 degrees C with water, methanol, and acetonitrile as solvents. Capillary cooling systems used were circulating liquid cooling, enforced air-cooling, and natural convection in still air. The mean temperature (averaged over the cross section) resulting from Joule heating was compared with experimentally determined temperatures established upon application of an electric field; the latter temperature was derived from the measurement of the electric conductance of the background electrolyte solution and its (measured) temperature dependence. All investigations were carried out with solutions of the same initial electric conductivity (about 0.5 S.m(-1) at 25.0 degrees C). Agreement is found for natural convection conditions, and the deviation between theoretical and experimental results for the forced air and circulated liquid cooling systems can be related to the poorly defined thermal conditions of the capillaries in commercial instrumentation (with a part in a thermostated cassette and a part outside). For given conditions the temperature gradients in the organic solvents exceed largely those in water, independent of the type of cooling. As a consequence, the thermal plate height is significantly larger in organic solvents, at least under conditions where the deviation from the Nernst-Einstein limiting case is not too high. However, even for the maximum applicable field strengths the thermal plate height contributions are negligible compared to longitudinal diffusion in all solvents.

Rooting Foliage Plant Cuttings in Compost-formulated Substrates

Three composts, derived from municipal solid waste with biosolids, yard trimmings, and yard trimmings with biosolids, were mixed by volume with sphagnum peat and pine bark to formulate 12 substrates. After characterizing physical and chemical properties, the substrates, along with a control, were used for rooting single eye cuttings of pothos (Epipremnum aureum) and terminal cuttings of maranta (Maranta leuconeura) and schefflera (Schefflera arboricola) in enclosed polyethylene tents. All cuttings initiated roots with no significant difference in root numbers per cutting 14 days after sticking, but root lengths 21 days and root-ball coverage ratings 45 days after sticking were significantly affected by substrates. Five of 12 compost-formulated substrates resulted in root lengths of cuttings equal to or longer than the control. In addition to desirable physical properties such as bulk density, total porosity, and air space, common chemical characteristics of the five substrates included low concentration of mineral elements, initial electrical conductivity ≤3.0 dS·m-1 based on the pour through extraction method, and pH between 3.8 to 5.0. The five substrates were formulated by combining composted municipal solid waste with biosolids or yard trimmings with biosolids volumetrically at 20% or less or composted yard trimmings at 50% or less with equal volumes of sphagnum peat and pine bark.

Chloride diffusivity based on migration testing

The present article presents the results of an experimental investigation, where the chloride diffusivities from steady-state migration, non-steady-state migration, and electrical conductivity measurements were compared. A very good correlation between all these diffusivities were obtained, but the non-steady-state migration testing gave a chloride diffusivity that was about 10 times higher than from the steady-state migration and up to several times higher than that from the conductivity method. A good correlation was also observed between the initial electrical conductivity, the conductivity of NaCl saturated concrete, and the charge passed through the concrete. The correlation was further good between the electrical conductivity and the diffusivity obtained from both the steady-state and the non-steady-state migration method. For a given binder system and type of concrete, measurements of initial electrical conductivity appear to provide a good basis both for estimation of chloride diffusivity and for routine control of concrete quality.

Effect of Controlled-Release Fertilizer Application Rates on Bedding Plant Growth In Substrates Containing Compost

Growth of ‘Accent Orange’ impatiens (Impatiens wallerana Hook.f) and ‘Blue Rhea’ salvia (Salvia farinacea Benth.) plants were compared in substrates containing 0, 30, 60, or 100% compost made from biosolids and yard trimmings and fertilized with 13N-5.7P-10.8K Nutricote (type 100 plus minors) top-dressed at transplanting at 0.5, 1, 2, or 4 g per pot (6, 12, 24, or 48 kg·100 m−2). Initial substrate cation exchange capacity (CEC), pH, electrical conductivity (EC), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were greater in substrates containing 30, 60 or 100% compost than in substrates containing 0% compost. Shoot dry mass of impatiens and salvia plants increased as fertilizer application rate increased in all substrates. Final impatiens and salvia substrate EC concentrations also increased as fertilizer application rate increased from 0.5 to 4 g in all substrates. There was no difference in impatiens or salvia shoot dry mass among the substrates when plants were fertilized with 0.5 g. However, shoot dry mass of impatiens plants fertilized with 4 g increased as the percentage of compost in the substrate increased. The shoot dry mass of salvia plants fertilized with 4 g increased as the percentage of compost increased to 60% but then decreased. At the low fertilization rates, substrates containing compost made from biosolids and yard trimmings did not appear to supply sufficient nutrients to increase plant growth beyond that achieved in 0% compost. However, at higher fertilization rates, Nutricote apparently augmented the nutrients provided by substrates containing compost and increased plant growth beyond that achieved in 0% compost.

Remoção de carga orgânica e produtividade da aveia forrageira em cultivo hidropônico com águas residuárias da suinocultura

Um estudo para quantificar a produtividade de aveia forrageira e a eficiência na remoção da carga orgânica de águas residuárias da suinocultura, utilizadas em diferentes proporções para composição da solução nutritiva do cultivo hidropônico, foi realizado dentro de um galpão contendo sistemas individualizados de cultivo, constituídos por tanques de 3,20 x 0,80 m, equipados com sistemas de aeração. Foram utilizadas as proporções de 70, 50, 30 e 10% de águas residuárias da suinocultura no preparo da solução nutritiva, todas representadas por valores de condutividade elétrica inicial de 4,2, 2,8, 1,8 e 0,97 dS m-1, respectivamente, e a aveia semeada sobre tela plástica, dentro dos tanques de cultivo. Diariamente, determinou-se a concentração de oxigênio dissolvido, a condutividade elétrica e a temperatura das soluções nutritivas e do ar dentro do galpão, enquanto semanalmente foram coletadas amostras das soluções para determinação da concentração de DQO e DBO. Utilizou-se um tratamento com solução nutritiva convencional como testemunha, enquanto o cultivo hidropônico de aveia forrageira, com aproveitamento de águas residuárias da suinocultura no preparo da solução nutritiva, proporcionou produtividades de até 31,5 t ha-1 ano-1 e diminuição significativa da carga orgânica da solução nutritiva.

Nickel coarsening in annealed Ni/8YSZ anode substrates for solid oxide fuel cells

In order to study the nickel coarsening in porous Ni/8YSZ anode cermets of solid oxide fuel cells (SOFC), a series of exposure tests was carried out with anode substrates used in SOFC development at the Research Centre Jülich. The changes in electrical conductivity as well as in the microstructure of the material were investigated. The microstructure of the cermets was characterized by digital on-line image analysis and microstructural parameters were determined for the metallic and the ceramic phase as well as for porosity. A decrease of 33% of the initial electrical conductivity was measured after exposing the cermet in Ar/4% H 2/3% H 2O at 1000°C for 4000 h, which is linked to the agglomeration of the metallic particles of this material. The durability of anode cermets for operations of up to 40 000 h was estimated on the basis of the measured grain coarsening and the decrease of conductivity. The microstructural parameters — like volume fraction, particle and pore size — were used to model the electrical conductivity by theoretical microstructure–property relationships.

Environmental implication of soils amended with anaerobically digested sewage sludge in Hong Kong.

Rainfall leaching soil column trials wereused to characterize the downward movement ofpotential contaminants through a sandy loam and sandysoil following the application of an anaerobicallydigested sewage sludge at the rates of 10 and 25%(v/v). Leachate pH did not vary significantly withsludge application except for sandy loam with 25%sludge, while initial electrical conductivity (EC) anddissolved organic carbon (DOC) increased linearly withsludge application and declined shortly to levelsfound in soils without sludge. A higher initialleaching loss of ammonium (NH4+) was found in sandy soilthan loamy sand due to its lower cation exchangecapacity. Nitrate (NO3-) was the dominant anion inleachates with an average in excess of 10 mg L-1 NO3- at all loading rates after 12 weeks. The highestconcentration of NO3- occurred with the highest sludgeapplication rate. Leachate zinc (Zn) content increasedin loamy sand columns at the high sludge loading rateat the end of the experiment owing to the reduced pHfollowing nitrification. No significant difference inleachate copper (Cu) and phosphate (PO43-) contents werenoted for both soils receiving various sludgeapplication rates. Evaluation of the soluble nutrientspresent in the soil profiles at the end of theleaching experiment showed that EC, NH4+ and PO43- increased according to sludge application rate up toa depth of 20 cm. Significant accumulation of NO3- wasfound in sandy loam with sludge application to thedepth of 50 cm. Analyses of leachates and soils forthe selected contaminants revealed that NO3- leaching islikely to occur without plant growth at the currentapplication rate. Therefore, the application rate forsludge should not exceed 10% (v/v), and the provisionof vegetation on the amended soil would reduce theleaching loss of NO3-.

Comparison of Salvia Growth in Seaweed Compost and Biosolids Compost

Salvia ‘Red Hot Sally’ (Salvia splendens F. Sellow ex Roem. & Schult.) shoot dry mass and number of flower spikes was significantly greater in substrates containing compost made from biosolids and yard trimmings (SYT) than in substrates containing compost made from seaweed and yard trimmings (SW). Initial substrate electrical conductivity (EC), nitrogen (N), phosphorus (P), and potassium (K) concentrations also were greater in substrates containing SYT than in substrates containing SW. Salvia shoot dry mass and flower number increased as the percentage of SYT compost increased from 0 to 60% but decreased at 100% SYT. Initial EC levels in 100% SYT were more than twice as high as the levels measured in the other percentages. Shoot dry mass and number of flowers of plants grown in 30, 60, and 100% SW, however, was similar to plants grown in 0% SW. There were no differences in plant quality rating among the treatments and all salvia plants grown in both compost products were considered saleable.

CONTAINER PRODUCTION OF UNDERUTILIZED URBAN TREES USING KENAF AND COCONUT COIR PITH

Growth responses during nursery production in 2.2- and 11.4-liter plastic containers to conventional and alternative media of four species of small trees of limited availability for potential use in urban sites in the southwest United States (Acacia wrightii, Chilopsis linearis, × Chitalpa tashkentensis, and Rhus lanceolata) were compared to that of a commercially available small tree (Fraxinus velutina). Four media combinations, at 3:1 (v/v) of bark: sand (conventional), bark: coconut coir pith, kenaf stalk core: peatmoss, and kenaf: coir, with three fertilizer concentrations (3.6, 7.2, and 10.7 kg·m–3 of 18N–2.6P–10K Osmocote) were tested with each species. All species exhibited commercially acceptable growth (80 to 167 cm mean heights in 11.4-liter containers in 240 days) with near 100% survival in most media and fertilizer combinations with the following exceptions: shoot extension of Rhus lanceolata was reduced by 20 to 30 cm and survival by 20% to 50% in kenaf media with high fertility rates; and Acacia wrightii had acceptable shoot extension but exhibited poor trunk diameter growth across media relative to the other species. Slightreductions in growth of some species were noted with kenaf media and slight increases with coconut coir, but differences were not likely of commercial significance. Kenaf media was significantly lighter (20% to 80%) than bark media, but had elevated initial electrical conductivity (EC) and shrank to 60% to 70% of its initial volume after 240 days. Kenaf: peatmoss media had a slightly lower mean pH (6.34) compared to the other media (pH 6.41–6.49).

Availability and Persistence of Macronutrients from Lime and Preplant Nutrient Charge Fertilizers in Peat-based Root Media

Using incubation and container culture with subirrigation for up to 28 days, three experiments were conducted with six liming materials of different particle sizes and six blended preplant nutrient charge (PNC) fertilizers. Liming material, particle size, and incorporation rate had an effect on the initial pH (3.5 to 6.1) and the final stable pH (4.8 to 7.8) with one type of Canadian sphagnum peat that did not contain an incorporated PNC. Saturated media extract (SME) Ca and Mg concentrations were <25 and 15 mg·liter-1, respectively, for both pulverized and superfine dolomitic lime at incorporation rates up to 7.2 kg·m-3. For the blended PNC fertilizers in media containing lime, initial electrical conductivity (EC) and SME nutrient concentrations ranged from (EC) 1.0 to 2.9 dS·m-1, (mg·liter-1) 60 to 300 N, 4 to 105 PO4-P, 85 to 250 K, 120 to 400 Ca, and 60 to 220 Mg. However, within two days, the rapid stratification of fertilizer salts within the pot caused macronutrient concentrations to increase in the top 3 cm of root medium (top layer) by an average of 180% and decrease in the remaining root medium in the pot (root zone) by an average of 57% compared to that measured in the medium at planting. Nutrient concentrations in the top layer continued to increase even when those in the root zone fell below acceptable levels recommended for an SME. The importance of fertilizer salt stratification within a pot lies in the reduced availability of nutrients to the plant and illustrates the limited persistence of the PNC fertilizers. Testing nutrients in container media several days after planting rather than in freshly mixed media may be more representative of the starting point for a nutritional management program.

高温超電導多芯銀シース線の電流・磁場分布と交流損失解析

The Bean model was introduced to a 3-D simulation code so that the electromagnetic phenomena in superconductors can be analyzed. The AC loss of a cylindrical superconductor which was obtained by the simulation with this code under a forced AC current was compared with the analytical result based on the Bean model. According to the results, the value of AC loss of the simulation coincided with that of the theoretical analysis if the initial electric conductivity was appropriately selected according to the mesh size. The current and magnetic field distribution as well as AC loss of the multi-filamentary superconducting wires were analyzed by the code under an external longitudinal magnetic field. The current distribution profile indicated the existence of current flow, with a density an order of magnitude larger than that of a typical eddy current, which seemed to link the adjacent superconducting filaments. This current component, thereby, gives rise to the AC loss of the silver region in addition to the eddy current. A reasonable agreement was found in terms of AC loss between the simulation and the experiment.

Salt Release Model for Suspended Sediments

Fluvial sediment has been reported a natural diffuse source of salinity in the Upper Colorado River Basin. This paper describes experimental and mathematical modeling to identify major factors controlling salt release from suspended sediments. Salt release characteristics of suspended sediments were studied using sediments from various locations in the Price River Basin, a tributary to the Colorado River. The sediments were mixed with water in the laboratory and the change in electrical conductivity of the solutions was monitored while varying the following factors: dilution, particle size, mixing velocity, and initial electrical conductivity. The Buckingham Pi Theorem was employed to develop equations for predicting the electrical conductivity of sediment‐water solutions as a function of factors controlling salt release from suspended sediments. The salt release equations were verified with additional laboratory data. In a companion paper incorporation of the salt release equations into a watershed erosi...

Tomato Plant Response to Soil Salinity1

AbstractTomato (Lycopersicon esculentum var. VF 145) plants were grown in a greenhouse to determine the effects of salinity on growth and yield. The plants were grown in soil (Typic Xerofluvents, coarse‐loamy, mixed, nonacid, thermic) using regular or four‐compartment containers allowing splitting of the root systems. Nutrient solutions made saline with NaCI and CaCl2 to electrical conductivities (EC) of 1, 2, 3, 4, and 5 dS/m (dS/M = mmho/cm, referenced at 25°C) were applied twice a day in the undivided root systems. In the split‐root series, each of the four compartments was irrigated with solutions of different EC, while the regular containers were irrigated with a nutrient solution satinized to a level equivalent to the mean value of the solutions used for irrigating the four‐compartment units. The nutrient solutions were recycled through the containers, so that responses of plants subjected to increasing salinity up to 35 dS/m could be evaluated. With increasing salinity fruit fresh weights decreased markedly, with lesser decreases in shoot weights in both systems. Plants with their root systems divided and growing in containers with differentially salinized soil were less severely affected. Yield and growth correlated better with the initial electrical conductivity (ECin) of the nutrient solutions applied than with the EC values of the solutions extracted from the soil. Roots were less sensitive to root‐zone salinity than were tops. In the split‐root system, any reduction in the root growth in the compartments with high salinity levels was compensated for by more growth of those portions of the root system in the less saline environment. During the latter part of the growing period, levels of soil solution salinity were generally greater in the soils in which plants were grown in the undivided root systems than in soils in the split‐root systems.

Oxidation mechanism and electrical behavior of Cu–Ag alloys under arcing conditions

High temperatures associated with arcing cause Cu–Ag alloys to oxidize and acquire increased resistivities when utilized in electrical switches. This oxidation involves formation of copper oxides at the surface and as precipitates randomly distributed in the arced layer and bulk of the alloy. As such, the change of resistivity with the extent of oxidation resembles a percolation process: specimens with an initial good electrical conductivity exhibit an abrupt transition to a poor conductivity when the buildup of oxide precipitates blocks paths in the conductive metal matrix.

Soil physical and chemical properties measured in an “ashbed” following windrow burning

Summary Some physical and chemical properties were measured in soils collected from within and outside a burned windrow formed during the conversion of eucalypt forest to pine plantation. Bulk density was lower while initial infiltration rate, electrical conductivity and pH were higher in windrow soils than in the bay soils adjacent to the windrow. The implications of these results in relation to tree growth as well as soil changes are discussed and it is suggested that increased tree growth in windrows may be partly attributed to changes in both soil physical and chemical properties following heaping and burning.

Reclamation of Saline‐Sodic Soils by Leaching

AbstractSeven lysimeters containing sandy loam or clay loam soils were reclaimed by ponded or unsaturated leaching following a saline irrigation experiment of 2.5 years duration. Initial soil electrical conductivity was as high as ECe = 25 mmho/cm with associated exchangeable sodium percentages (ESP) up to 60%. Substantial quantities of solid gypsum and lime were present in the soil profile from precipitation reactions during the crop irrigation stage.Drainage volumes were expressed in pore volume units to scale out differences between water retention and leaching rates. Plots of scaled chloride concentrations (Cl/Cl initial) vs. pore volumes were similar for all lysimeters, with essentially all chloride removed by 1.5 pore volumes. Total salt removal was well described by a single curve (C/Cinft)(PV) = 0.8 for all treatments. Standard cation exchange equilibrium equations were used in a chromatographic displacement model to produce an algebraic equation to describe exchangeable Na reductions as a function of leaching pore volumes. This model, along with a model for calculating exchangeable Mg reductions, was in good agreement with measured changes for all treatments.No special amendments were required to maintain high permeability during leaching, even when distilled water was used, because of redissolution of previously precipitated Ca salts.