Electrical Conductivity Ratio Research Articles

Assessment of interaction between the aquifers by geochemical signatures in an urbanised coastal region of India

Multi-layered coastal aquifers are complex aquifer systems with two or more aquifers divided by the impermeable or semi permeable layers. The objective is to assess the interaction between the aquifers using geochemical indicators in the urbanised multi-layered coastal aquifer of Sankaraparani river basin, India. Hydrogeologically, the coastal part of this region comprises of alluvium formation as upper aquifer and sandstone formation as lower aquifer. Groundwater samples were collected from 33 representative wells during June 2017 and January 2018. Electrical conductivity, pH, and alkalinity were measured in the field while the concentration of major ions was analysed in the laboratory. The groundwater level in the upper aquifer varies from 7.4 to 18 m msl. Na-Cl type groundwater is dominant in the upper aquifer whereas Ca-HCO3 and mixed Ca-Na-HCO3 type groundwater is dominant in lower aquifer. The processes that controls the groundwater chemistry are sulphate reduction, freshening ion exchange, calcite dissolution and conservative mixing of seawater and freshwater. Significantly different values of electrical conductivity, sodium and chloride ratio, base exchange index as well as the different geochemical facies between the upper and lower aquifer indicates the absence of interaction between the aquifers near to the coast. Whereas in the west, the similarity in these confirms the interaction and both the formation function as single aquifer. The groundwater in the upper aquifer is affected by seawater intrusion upto 2 km whereas the lower aquifer is not affected.

The role of 5d electrons spin in quantum ferromagnetism and transport properties of double perovskites Cs2ZCl/Br6 (Z = Ta, W) for spintronic applications

The role of 5d electrons of transition metals in double perovskites Cs2ZCl/Br6 (Z = Ta, W) has been probed for advanced spintronic technology. The magnetic and transport properties are computed by using Wein2K code and BoltzTraP code. The exchange mechanism is explained by the measurement of crystal field energy, exchange energy and hybridization process. The half metallic ferromagnetism is illustrated by double-exchange model and exchange constants while spin polarization is illustrated by integer value of total magnetic moments and polarization factor computations. The issue of stability is clarified by formation energy and tolerance factor conditions. In the end, thermoelectric properties are analyzed by thermal to electrical conductivity ratio, Seebeck coefficient, and power factor.

Long-term Fertilization with Liquid Cattle Manure Leaves Legacy Nutrients, but not Organic Carbon and Has No Effect on Soil Microbial and Physical Properties a Year after Last Application

ABSTRACT Long-term liquid cattle manure (LCM) application can enhance soil fertility, increase soil organic carbon, and improve soil properties. We investigated the residual effects of long-term fertilization with LCM on physical, chemical and microbial properties of a calcareous soil. The effects of LCM, common inorganic fertilization, recommended fertilization or non-fertilized control were investigated in field plots with corn (Zea mays L.), 1 year after the cessation of 16-years of experimentation. The residual concentrations of soil available P, K, Cu, Zn, B and total N but not NO3-N remained significantly higher with LCM, while there were no differences in soil pH, electrical conductivity and sodium adsorption ratio, compared to the other treatments. The previously observed increase of soil organic C with LCM was no longer evidenced. For aggregate size distribution and stability, microbial biomass N, easily extractable glomalin-related soil protein, number and morphotypes of arbuscular mycorrhizal fungal spores and percentage of root length colonization, there was no difference among treatments. Microbial growth and activity were limited by C, while the calcareous nature of the soil was more important than glomalin for soil aggregation. In conclusion, the residual effects of LCM were limited to soil nutrient increase.

Dynamics of a compound droplet under the combined influence of electric field and shear flow

The work demonstrates the dynamics of a compound droplet under the combined influence of an applied electric field and shear flow. For the case of dielectric fluids, the deformation of both the inner and outer interfaces can be modulated by either variation of the permittivity contrast between the fluids or the applied electric field. The investigations for leaky dielectric fluids reveal that the ratio of electrical permittivity and conductivity between the two phases play a critical role in deciding the magnitude of deformation and orientation of the compound droplet. The electric field can be suitably applied to engender breakup of the compound

Thermoelectric Power of Silver Telluride Thin Films and its Thermal Conductivity Applications

The hydrothermal technique was used to create straight single crystal silver telluride nanowires with a diameter of around 200 nm and a length of up to micrometers of decades. There has been no template or surfactant used in the process. As-synthesized products are high purity and well-crystallized, confirmed by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectrum, transmission electron microscopy (TEM), and a high-resolution SAED pattern. Differential scanning calorimetry was used to observe the reversible structural phase shift from the low-temperature monoclinic structure to the high-temperature face-centered cubic structure. Furthermore, the dramatic drop in electrical current in a single nanowire at the phase transition temperature is revealed, paving the way for future research into the manufacturing of one-dimensional nanoscale devices. Silver telluride (Ag2Te) has large thermoelectric coefficients and it was tested by using resistor graph and calculated the values of it, thermal conductivity and Seebeck coefficient were discussed with respect to the temperature of thin films. Semiconductors were superior thermoelectric material due to higher ratio of electrical and thermal conductivities. Therefore, the AgTe thin films deposited on indium tin oxide (ITO) substrates were employed, thermoelectric power and thermal conductivity measurements, respectively.

Effects of gypsum, irrigation and tillage on a sodic Yellow Kandosol at Carnarvon, Western Australia

Context Kandosol soils are widely distributed in Australia and are frequently used for irrigated cropping. However, under intensive irrigated cropping they can degrade due to poor structural stability where surface soil aggregates break down as a result of slaking and dispersion; the slaking is associated with low soil organic carbon levels (<1.0 g/100 g) on these frequently cultivated soils, and the dispersion is related to the moderate level of exchangeable sodium percentage (ESP) combined with low electrical conductivity (EC) levels in the soil solution. Aims To investigate the effects of applied gypsum (0, 2 and 10 t/ha), irrigation with water of low EC (0.5 dS/m) and low sodium adsorption ratio (≤2), and two tillage practices, i.e. conventional tillage (CT) and reduced tillage (RT), on the structure of a marginally sodic (ESP 6) Yellow Kandosol soil. Methods The experiment was conducted at Carnarvon, Western Australia. Key results After 2 years the soil EC (1:5) and ESP levels were significantly reduced on all plots at the three gypsum rates. The three gypsum rates also significantly affected exchangeable calcium (Ca) and magnesium (Mg) and soluble Ca and Mg levels, as well as pH and dispersion values. Micromorphological examination indicated less dispersed clay with gypsum application. Conclusions The EC results indicated that the soil will require frequent re-application of gypsum to maintain electrolyte levels and prevent dispersion. With some of the variables, RT compared to CT demonstrated greater through-flow, which was attributed to the presence of more macropores in RT. Implications A change in management from semi-arid chenopod shrublands used for grazing to intensely cultivated horticulture will require careful consideration of factors causing soil structural instability.

Strain-tunable giant anisotropic conductivity in the polar metal of KNbO3/BaTiO3 ferroelectric superlattice

Anisotropy in crystals originates from different periodicity atomic arrangements along with different crystallographic directions, leading to different physical properties of the crystal in different directions, which is particularly pronounced in two-dimensional (2D) materials. In this work, by using first-principles calculations, we predicted the tunable giant electrical anisotropy of the KNbO3/BaTiO3 (KNO/BTO) ferroelectric superlattice (SL) between in-plane and out-of-plane directions through the in-plane strain-engineering. The anisotropy ratio of electrical conductivity and electronic thermal conductivity shows an exponentially increase when the KNO/BTO SL undergoes a strain from tensile to compressive, and their anisotropy ratio can be tuned from several times to over 105 at room temperature. In addition, the compressively strained KNO/BTO SL has a large out-of-plane Seebeck coefficient and a high anisotropic thermopower. This anisotropy of the KNO/BTO SL primarily derives from the proportion of electrons occupied by dxy and dxz/dyz orbitals and that proportion is highly dependent on the polarization intensity of the KNO/BTO SL. Moreover, the ferroelectric and ferromagnetic properties of the KNO/BTO SL can be tuned by strain due to the coexistence of polar structure and metallicity. Our results provide a road map for creating multifunctional materials at perovskite oxides interfaces, which may be favorable for designing new volatile memory devices with anisotropy-based ultrafast and low-power properties.

Assessing agricultural salt-affected land using digital soil mapping and hybridized random forests

Salinization and alkalization are predominant environmental problem world-wide which their accurate assessment is essential for determining appropriate ways to deal with land degradation, for better soil and crop management. In the current research, a combination of random forests and covariate data were used to assess spatial variability of soil salinity and sodicity in 436 km2 agricultural salt-affected land in Kurdistan Province, Iran. Using the conditioned Latin hypercube sampling method, 295 soil samples were sampled across the study area, and then soil reaction (pH), electrical conductivity (EC), and sodium adsorption ratio (SAR) were measured. Covariate data including terrain attributes, remotely-sensed data, groundwater table, and categorical maps were acquired. Random forest (RF) models were used to predict the spatial distribution of pH, EC, and SAR by making a relationship between soil data and covariates. Furthermore, three optimization algorithms (particle swarm optimization-PSO, genetic algorithm-GA, and bat algorithm-BAT) were used to explore if the hybridized RF works better than the standard RF. Results of 10-fold cross-validation with 100 replications indicated that the accuracy of RF + PSO was higher for predicting pH (RMSE = 0.52 and R2 = 0.67), EC (RMSE = 2.32 dSm−1 and R2 = 0.57), and SAR (RMSE = 8.98 and R2 = 0.54, respectively) in comparison to the other implemented models. Furthermore, the results disclosed that the most important covariates to predict pH, EC, and SAR were groundwater table, categorical maps, salinity index, and multi-resolution ridge top flatness. Besides, the results indicated that the mean values for pH, EC, and SAR in lowland and bare land were significantly different from the other physiographic units and land uses, respectively. Importantly, the classified map of salt-affected soils highlighted areas with a high risk of exceeding critical threshold values of pH, EC, and SAR, which is located in the center of the study area, and showed that 6.30%, 3.1%, and 4.6% of the study area are saline-sodic soil, saline soil, and sodic soil, respectively. These up to date spatial soil information on severity of soil salinity and sodicity is crucial for agricultural management of affected areas and the proposed method can be used to the other similar regions.

Effect of natural and artificial afforestation reclamation on soil properties and vegetation in coastal saline silt soils

Sparse vegetation and soil desertification are widespread phenomena in coastal regions due to the accumulation of excess sodium in soil, which results in degraded land quality and ecological impairment. Artificial reclamation approaches, including physical, chemical, hydro-technical, and phytoremediation techniques, have failed mainly due to freshwater shortages, high costs, and a relative lack of salt-tolerant plant types suitable for the landscape ecology. In recent years, a method based on water-salt regulation through drip irrigation combined with agronomic engineering including soil removal, layout of a gravel and sand layer, soil backfilling and land leveling, has been developed and was successfully applied in coastal saline wastelands in China. This paper presents the results of a study concerning responses of soil properties and vegetation in coastal saline wastelands reclaimed through natural and artificial afforestation using water-salt regulation based on drip irrigation. Different reclamation time spans (4–6 years) and afforestation modes (orchard, protection forest, poplar forest, and mixed forest) were compared. The results showed that after 4 years of drip irrigation, the soil bulk density decreased from 1.7 to 1.8 g/cm3 to levels typical of farmland and field water holding capacity increased. Additionally, the soil electrical conductivity and sodium adsorption ratio decreased significantly as the severely saline soil shifted to non-saline conditions, thereby creating a suitable environment for the soil microbial community and plant seed germination. As a result, vegetation cover and plant and bacteria species diversity increased and the soil received increasing organic matter inputs; thus, developing a higher organic carbon content and carbon to nitrogen ratio. These results suggested the feasibility of using water-salt regulation through drip irrigation to develop a good quality environment in coastal saline wastelands without soil amendments, especially with a rapid reclamation process. This approach could help to arrest desertification due to salinity, aid the rehabilitation of wastelands, and thus contribute to improvements in the local environment.

Electrohydrodynamics of a droplet in a highly confined domain: A numerical study

In this paper, electrohydrodynamics (EHD) deformation of a droplet in a highly confined domain is studied by using the incompressible smoothed particle hydrodynamics method. Simulations are performed for six different systems of a droplet and ambient fluid corresponding to different electrical properties. The effects of confinement ratios, from 0 to 0.95, on the droplet deformation are discussed thoroughly. It is shown that the deformation is highly dependent on the ratios of electrical permittivity, electrical conductivity, and confinement ratio. To demonstrate the droplet behavior, electric force components on the droplet interface are calculated and discussed in detail. It is shown that the interaction of these forces plays a major role in the droplet deformation. Furthermore, it is illustrated that the pressure force becomes significant at high confinement ratios and affects the droplet behavior in addition to the electric forces. Different values of unbounded deformation are selected for the EHD simulation. The effect of unbounded deformation on the droplet behavior is also discussed, and it is found that the unbounded deformation influence is important in some of the systems and confinement ratios.

Shear viscosity to electrical conductivity ratio in the quasiparticle models

We examine the temperature dependence of the shear viscosity η to electrical conductivity σ ratio, as well as the specific shear viscosity and the scaled electrical conductivity in QCD with light and strange quarks. Our calculations are performed in kinetic theory under the relaxation time approximation combined with the quasiparticle model. We compute all transport parameters using the isotropic and transport cross sections and compare our results to a class of quasiparticle models for the QGP with Nf = 2 + 1. The results depending on different schemes are examined. The ratio (η∕s)∕(σ∕T) quantifies the relation between the relaxation times of gluons and quarks and specifies their comparative role in the evolution of the QGP. We find an excellent agreement with the (η∕s)∕(σ∕T) ratio deduced from the dynamical quasiparticle model in which the quasiparticles are characterized not only by their effective masses but also by finite widths.

Salt dome related soil salinity in southern Iran: Prediction and mapping with averaging machine learning models

AbstractIn order to manage soil salinity effectively, it is necessary to understand the origin and the spatial distribution of salinity. There are about 120 salt dome outcrops in southern Iran and little is known about their contribution as the potential sources of salts and the spatial pattern of salts around them. Six machine learning algorithms were applied to model topsoil electrical conductivity (EC) and sodium adsorption ratio (SAR) in the Darab Plain (surrounded by six salt domes), Fars Province. Decision trees (DT), k‐nearest neighbours (kNN), support vector machines (SVM), Cubist, random forests (RF) and extreme gradient boosting (XGBoost) were used as primary models and the Granger–Ramanathan (GR) method was used to combine the predictions of these models. The results showed that remotely sensed data contributed more to predict EC and SAR than terrain‐based data. In terms of root mean square errors (RMSE), Cubist followed by the RF model, tended to give the best estimates of EC, whereas for SAR, RF performed best and was followed closely by SVM and Cubist. Compared to the primary models, the GR method on average resulted in a decrease of 6.1% and 3.9% in RMSE and an increase of 10% and 10.9% in R2 for EC and SAR, respectively. The spatial pattern of SAR and EC suggested that the contribution of salt domes in soil salinization varied significantly according to their hydraulic behaviour in relation to adjacent aquifers and their activity. In general, the model averaging approach showed the potential to improve the estimates of EC and SAR.

Effect of semiconductor to metal transition on thermoelectric performance in oxide nanocomposites of SrTi0.85Nb0.15O3 with graphene oxide

Donor doped SrTiO3 based perovskites are considered as very promising candidates for high temperature thermoelectric applications, but the figure of merit (ZT) of these n-type oxide thermoelectrics need to be enhanced for making it commercially viable. However, it is challenging to improve the transport properties of these oxides in order to achieve high ZT. Here we put forward a strategy of boosting the electron transport by inducing semiconductor to metal transition in Nb doped SrTiO3 (STN) by formation of nanocomposites with graphene oxide (GO). We could enhance electrical conductivity remarkably by gradual incorporation of GO in the matrix of STN, which changed its semiconductor (dσ/dT>0) behavior into metallic (dσ/dT<0) for more than 1 wt% GO content. GO sheets embedded in the grain boundaries of polycrystalline STN facilitated electron transport without increasing much it's thermal conductivity, resulting in the order of magnitude increase in the ratio of electrical conductivity and thermal conductivity in the temperature range from 300 K to 1200 K. Hence, ZT of STN ceramics was raised by 50 times due to GO incorporation. Maximum ZT of 0.5 was attained at 1200K in n-type bulk oxide nanocomposite made of environmentally benign, earth-abundant elements.

Hydrochemistry and quality assessment of qanat water compared to wells using laboratory studies and literature review (case study of Samalghan plain, North Khorasan, Iran)

The development of civilizations and human societies has been dependent on water. Without the qanats, many human settlements could not be built, and the qanat is still a major source, and in some cases, the only source of agricultural and potable water supply in many parts of world. However, in densely populated areas, the qanat has lost its importance as a valuable source of water and has been replaced by the well. This study set out to compare the utility of using the qanats and deep wells through the library and laboratory studies. A total of 26 samples were collected and analyzed for: pH, Chlorides (Cl−), Electrical Conductivity (EC) and Sodium Absorption Ratio (SAR). Also, 40 soil sample were taken from the farms irrigated with qanat and well water and analyzed for the EC, SAR, pH, lime percentage and soluble sodium and exchangeable sodium. An area outside the study area was selected and surveyed as the control area with the same conditions as the well and qanat tailwater. The samples were transferred to the Atomic Absorption Laboratory of Yazd University of Natural Resources. The results of soil samples showed that the lime percentage in qanat water-irrigated soil sample was higher than well water-irrigated soils, whereas there were no significant differences in other quality indexes between the irrigation with qanat and the deep well water. Finally in the taken water samples the EC, Cl−, SAR values of the qanat water were lower than the well water but the pH values of the qanat water was slightly higher than the well water. With regard to the high amount of water loss in the world, the studies on finding the most optimal way to use this vital agent are very important.

Probing of Optoelectronic and Transport Properties of Zinc Based ZnY2X4 (X = S, Se) Spinels for Renewable Energy

The spinels chalcogenide are emerging materials for solar cells and other renewable energy applications. we have elaborated the electronic and optical properties of ZnY2(S/Se)4 by modified Becke and Johnson potential. The computed band gaps 1.66 eV and 1.10 eV correspond to visible region which increase their significance for solar cells. The optical properties are elaborated by dielectric constants, refractive index, and absorption coefficient. Furthermore, the thermoelectric properties are depicted by BoltzTraP code in terms of thermal conductivity to electrical conductivity ratio, Seebeck coefficient and figure of merit. Finally, two important ratios (i.e. Pugh’s (B/G > 1.75) and Poisson (υ > 0.26) described the brittle nature of ZnY2S4 and ductile nature of ZnY2Se4 spinels. The large value of Debye and melting temperature is reported for ZnY2S4 than ZnY2Se4.

The study of optical and thermoelectric properties of lead-free variant iodes (K/Rb)2TiI6; Renewable energy

The solar cells and thermoelectric generators are the main sources of renewable energy. In current article, we have analyzed the electronic, optical, and transport characteristics of K2TiI6 and Rb2TiI6 by density functional theory (DFT) based Wien2k code through modified Becke and Johnson (mBJ) potential. The structural and thermodynamic stability are certified by tolerance factor (0.99–1.0) and negative formation energy. The bonding nature is illustrated by color charge density. The band gap of 1.39eV and 1.48eV for K2TiI6 and Rb2TiI6 demonstrate the maximum absorption of light takes place in visible region (1.5eV–3eV), which makes them new potential materials for solar cells. Moreover, the reflection of light and optical loss is negligible in the visible region. The transport characteristics have been explained by classical Boltzman transport (CBT) based BoltzTraP code in terms of thermal to electrical conductivity ratio, Seebeck coefficient, and figure of merit. The figure of merit lies between 0.75 to 0.76, which is decent for thermoelectric characteristics.

Assessment of the impact of land-cover change on water quality: case study of the Chiba watershed, Nabeul, Tunisia

Water scarcity and water quality degradation are important problems that can affect human well-being. Population growth, unplanned urbanization, land-cover change, and the intensification of agricultural and industrial activities are the main reasons for water resource issues. The main aim of this work was to evaluate the effect of land-cover change on groundwater quality in the Chiba watershed, Nabeul, Tunisia. A remote-sensing technique was used to identify the principal transitions in land cover between 1998 and 2018. Additionally, four water quality indicators (electrical conductivity, chloride concentration, nitrate concentration, and sodium absorption ratio) were utilized to investigate variations in water quality in the study area. It was found that most of the watershed was covered with agricultural land in 1998 (87.5%) and 2018 (88.6%). Based on a comparison of these two periods, various types of land-cover transitions were observed. Moreover, the water quality indicators revealed that the salinity hazard and nitrate contamination in the watershed were high. The spatial relationship between water contamination level and land-cover transition category indicated that barren land to built-up land transitions had the strongest negative effect on water quality among all of the main land-cover transitions. Demonstrating the impact of land-cover change on water quality should encourage local decision makers and water managers to implement strategies for sustainable urban planning and periurban agriculture.

Linear instability driven by an electric field in two-layer channel flow of Newtonian and Herschel–Bulkley fluids

We investigate the linear stability characteristics of a pressure-driven two-layer channel flow of immiscible Newtonian and Herschel–Bulkley fluids subjected to an applied electric field normal to the flow. The linear stability equations are derived and solved using an accurate spectral Chebyshev collocation method. It is found that the electric field can stabilise or destabilise the flow depending on the electrical properties of the fluids. We also observe that increasing the electric permittivity ratio and decreasing the electrical conductivity ratio, while keeping the rest of the parameters constant, enhances the growth rate of the disturbances. The “Reynolds stress” of the Newtonian layer and the work done by the velocity and stress disturbances tangential to the interface are found to be the mechanism of the instability observed due to the applied electric field. A parametric study is also conducted by varying the thickness of the bottom layer, Bingham number and flow index of the Herschel–Bulkley fluid. Increasing Bingham number is found to be stabilising or destabilising depending on the thickness of the non-Newtonian layer and the maximum disturbance growth occurs at an optimum value of non-Newtonian layer thicknesses. Increasing the shear-thinning and shear-thickening nature is shown to destabilise the flow. Our study is relevant in many microfluidic and electronic cooling applications.

Simulations of a weakly conducting droplet under the influence of an alternating electric field.

We investigate the electrohydrodynamics of an initially spherical droplet under the influence of an external alternating electric field by conducting axisymmetric numerical simulations using a charge-conservative volume-of-fluid based finite volume flow solver. The mean amplitude of shape oscillations of a droplet subjected to an alternating electric field for leaky dielectric fluids is similar to the steady-state deformation under an equivalent root mean squared direct electric field for all possible electrical conductivity ratio and permittivity ratio of the droplet to the surrounding fluid. In contrast, our simulations for weakly conducting media show that this equivalence between alternating and direct electric fields does not hold for . Moreover, for a range of parameters, the deformation obtained using the alternating and direct electric fields is qualitatively different, that is, for low and high , the droplet becomes prolate under alternating electric field but deforms to an oblate shape in the case of the equivalent direct electric field. A parametric study is conducted by varying the time period of the applied alternating electric field, the permittivity and the electrical conductivity ratios. It is observed that while increasing has a negligible effect on the deformation dynamics of the droplet for , it enhances the deformation of the droplet when for both alternating and direct electric fields. We believe that our results may be of immense consequence in explaining the morphological evolution of droplets in a plethora of scenarios ranging from nature tobiology.

Role of 5d orbital of Re in ferromagnetism and thermoelectric characteristics of Cs2ReCl/Br6 double-perovskites: a density functional theory study

The controlling of characteristics of electronic devices by the spin of the electrons is an integration field of new technology. The magnetic and thermoelectric properties of Cs2ReCl/Br6 double-perovskites are explored by the Wien2k and BoltzTraP code. The comparison of energies released in ferromagnetic and paramagnetic states reveals the lower energy state is the ferromagnetic state. The challenge of stability in the FM state is solved by negative formation energy and tolerance factor in the cubic phase. The half-metallic ferromagnetism has been analyzed from band structures and the density of states. The mechanism of HM ferromagnetism is illustrated by the partial density of states in terms of p–d hybridization and the double exchange model. The Spin polarization factor and integer value of total magnetic moment confirm the 100% spin polarization. The thermoelectric response demonstrated by thermal to electrical conductivity ratios and figure of merit which increases the potential of studied materials for thermoelectric devices.