The conductivites of the Na and H ion-exchanged forms of kaolinitic clay rejects from sand-washing operations, both purified and as found naturally as a complex with soil organic matter, were examined. The two Na-clays showed linear conductivity-concentration characteristics, each having two regions with different slopes intersecting at ∼3.3% by weight of clay, which probably reflect a structural change from sol to gel. In the gel region, only the Na-counterions conducted, the reduction in conductivity with concentration being due to a smaller proportion of these ions in the Gouy layer and/or a decrease in their mobilities. In the sol, an additional, concentration-dependent conductivity arose from the electrophoretic motion of clusters of clay particles which gradually broke down on dilution. The two acid clays showed curved conductivity-concentration characteristics consistent with a weak acid dissociation equilibrium; the pKa values of 6.37 to 6.56 are close to those determined independently from titration with alkali. A stronger acid species detected in the titrations was not seen in the conductivity. The MOH2+/MOH/MO− model of the clay-surface species and one set of the predicted concentrations of each species (see preceding paper) are consistent with the observed conductivities. The MOH2+ species probably bridged the edges and faces of clay particles so that the H atoms were identical, but became different when alkali was added.

The hydrolysis and decomposition of M-hectorite (M being Na, Li, Mg, or Ca) in dilute solutions of M-chlorides were studied by recording the changes in electrical conductivity (EC) of the clay suspensions with time, and by chemical analyses of the interclay solutions and resulting solid phases. The rate of hydrolysis of the hectorites in suspension, as evaluated by the change of EC with time, was found to decrease with increase in salt concentration (to zero for Na-hectorite in NaCl concentration of 47 meq/liter), and to decrease with increase in the valency of the adsorbed cation (the rate of hydrolysis of Ca-hectorite was one sixth of that of Na-hectorite). The rate of Na-hectorite hydrolysis was determined by the concentration of protons at the clay surface as calculated from the diffuse double layer theory.

Conversely, in suspensions of Al-hectorite saturated with Na, the hydrolysis rates were not dependent on the electrolyte concentrations. This result can be explained by assuming that the hydroxy-Al polymers at the clay surface determine the proton concentration at the clay surface. Hectorites saturated with structural cations (such as Mg and Li) are chemically more stable than those saturated with Na and Ca. The presence of Li and Mg at the clay surface slowed down the diffusion release of these octahedral ions to the clay surface, compared with Na and Ca hectorite, respectively.

The specific conductivity, κg, of Na/Ca montmorillonite gels (0.02 and 0.04 g clay/cm3) as a function of the specific conductivity of the interclay solution, κw, was measured. For low values of κw (<3 mmho/cm) the conductivity curves were convex with respect to xw; at higher values they were linear. The κw at which deviation from linearity began increased with increasing sodium content from 0.7 mmho/cm for the Ca-montmorillonite gel to 2.6 mmho/cm for Na-montmorillonite gel. The intercept of the linear portion of the conductivity curve increased and its slope decreased with increasing exchangeable sodium. The experimental results were described by a conductance model comprised of two elements connected in parallel: an element consisting of the solid and solution phases connected in series, and another consisting of the solution phase. At low electrolyte concentrations, the first element accounts for the curvature of the κg-κw curve, whereas at high electrolyte concentrations, the second element dominates, and the curve is linear with a slope determined by a formation factor and an intercept determined by exchangeable cation mobility.

An adjustable parameter in the conductivity term for the first element, which accounts for the thickness of the clay particles, increased with exchangeable Na, and its numerical value indicated that the solid phase also includes the diffuse double layer. The mobility of the exchangeable cation relative to that in water increased from 4% for Ca to 41% for Na with the largest increase occurring between 20 and 40% exchangeable Na. Similar effects of exchangeable Na were evident on the axial ratio of the clay particles calculated from the slopes of the linear lines. These observations are consistent with an exchangeable-ion demixing model where the initial exchangeable Na is adsorbed on the external surfaces of the Ca-montmorillonite tactoids without affecting exchangeable ion mobility or tactoid size. Further additions of exchangeable Na result in Na adsorption on the internal surfaces of the tactoid and tactoid breakdown with a subsequent increase in both exchangeable ion mobility and the axial ratio of the clay particles.

Electrical conductivity is an important soil property related to salinity, and is often used for delineating other soil properties. The purpose of this study was to examine the influence of smectite properties on the complex electrical conductivity spectra of hydrated smectitic clays. Four smectites were saturated with Ca, Mg, Na or K and equilibrated at four relative humidities ranging from 56 to 99%. X-ray diffraction was used to determine fractions of the various smectite layer hydrates (0 to 4 layers of interlayer water molecules) in each sample. A vector network analyzer was used to determine the real component of the complex electrical conductivity spectra (σ′) for frequencies (f) ranging from 300 kHz to 3 GHz. Values of the dc electrical conductivity(σ0), the frequency where the slope changes in the spectra (fr), and the slope at the high-frequency end of the spectra (n) were determined by fitting σ′ to σ′(f) = σ0(1 + f/fr)n. Both σ0 and fr increased with the total amount of water, the amount of interlayer water, and, for saturating cations in the order K < Mg < Ca < Na. The opposite trends were observed for n. The values of these parameters were influenced by the type of smectite, but the trends were not consistent for the effect of layer charge. The results indicate that interlayer water in smectites contributes to the electrical conductivity of hydrated smectites, and that polarization of water by local electrical fields has a substantial influence on the complex electrical conductivity spectra of smectites. The accuracy of salinity estimates for soils and sediments that are based on conductivity measurements maybe adversely affected unless the effects of hydrated clays on electrical conductivity are considered.

The effect of milorganite, a commercially available organic soil amendment, on soil nutrients, plant growth, and yield has been investigated. However, its effect on soil hydraulic properties remains less understood. Therefore, this study aimed to investigate the effect of milorganite amendment on soil evaporation, moisture retention, hydraulic conductivity, and electrical conductivity of a Krome soil. A column experiment was conducted with two milorganite application rates (15 and 30% v/v) and a non-amended control soil. The results revealed that milorganite reduced evaporation rates and the length of Stage I of the evaporation process compared with the control. Moreover, milorganite increased moisture retention at saturation and permanent wilting point while decreasing soil hydraulic conductivity. In addition, milorganite increased soil electrical conductivity. Overall, milorganite resulted in increased soil moisture retention; however, moisture in the soil may not be readily available for plants due to increased soil salinity.

In this work, microwave planar resonators are printed with silver nanoparticle inks using two printing technologies, inkjet printing and aerosol jet printing, on polyimide substrates. The microwave resonators used in this paper operate in the frequency band 5–21 GHz. The printing parameters, such as the number of printed layers of silver nanoparticle inks, drop spacing, and sintering time, were optimized to ensure repeatable and conductive test patterns. To improve the electrical conductivity of silver deposits, which are first dried using a hot plate or an oven, two complementary sintering methods are used: intense pulsed light (IPL) and laser sintering. This paper presents the results of different strategies for increasing the final quality factor of printed planar resonators and the trade-offs (sintering time versus final conductivity/unloaded Q) that can be reached. Improvement of the resonator unloaded quality factor (up to +55%) and of the equivalent electrical conductivity (up to 14.94 S/μm) at 14 GHz have been obtained thanks to these nonconventional sintering techniques. The total sintering durations of different combinations of sintering techniques (hot plate, oven, IPL, and laser) range from 960 to 90 min with a final conductivity from 14.94 to 7.1 S/μm at 14 GHz, respectively.

The effects of the Mg/Si ratio and aging treatment on the strength and electrical conductivity of Al–Mg–Si 6201 conductor alloys were investigated. Four experimental alloys with different Mg/Si ratios of 2, 1.5, 1, and 0.86 and with a constant Mg level of 0.65 wt% were prepared. It was revealed that excessive Si (a low Mg/Si ratio) increased the peak strength, while the corresponding electrical conductivity decreased. To fulfill the minimum required electrical conductivity (52.5% IACS), the alloys with low Mg/Si ratios required a longer aging time after peak aging to improve electrical conductivity. The alloy with an Mg/Si ratio of ~1 was the best candidate, exhibiting the highest strength up to 54% IACS. On the high end of electrical conductivity (54–56% IACS), the alloy with an Mg/Si ratio of ~1.5 provides a better compromise between strength and electrical conductivity. Furthermore, the strengthening mechanisms and the factors influencing electrical conductivity were discussed for further optimization.

In this study, precipitate phase transformation behavior, microstructure, and properties of the Cu–1Cr–1Co–0.4Si (wt%) alloy were investigated. Precipitate phase transformation kinetic equations of the alloy under room temperature rolling (RTR) 90% deformation and aging at different temperatures (440–520 °C) were established. The alloy yielded excellent mechanical and electrical properties under RTR 90% deformation and aging at 440 °C for 1 h, and the corresponding hardness, yield strength (YS), ultimate tensile strength (UTS), elongation, and electrical conductivity were 181.6 HV, 573.6 MPa, 653.7 MPa, 7.3%, and 51.6% International Annealed Copper Standard, respectively. The precipitate phase transformation behavior determined the size and volume fraction of the precipitate phase fv, which played a key role in improving the YS. Impurity scattering caused by surplus Si atoms was mainly responsible for decreasing the electrical conductivity. Therefore, these results can provide a reliable theoretical guidance to prepare Cu–Cr–based alloys with high strength and high electrical conductivity.

We compared the electrical conductivity from two different aggregates of whey protein concentrates (WPC) film: conventional amorphous aggregation at natural pH (pH 6.5) and amyloid fibrils at a low pH (pH 2.0) far away from the isoelectric point. The two types of film fabricated by these solutions with different aggregate structures showed large variations in electrical conductivity and other properties. The WPC fibril film (pH 2.0) exhibited higher electrical conductivity than that of the conventional WPC film (pH 6.5), improved mechanical properties and oil resistance, due to varying morphology, higher surface hydrophobicity and more (absolute value) surface charge of film-forming solutions. The evidence from this study suggests that fibrilized WPC with high-ordered and β-sheets-rich structures fabricated high electrical conductivity film, which broadens the potential application of fibrils as functional bio-nanomaterials.

The electrical conductivity of dry polycrystalline olivine compacts (hot-pressed and sintered pellets) was measured at pressures of 1.0–4.0 GPa, at temperatures of 1073–1423 K, and at different oxygen fugacities via the use of a YJ-3000t multi-anvil press. Oxygen fugacity was controlled successfully by means of five solid buffers: Fe3O4-Fe2O3, Ni-NiO, Fe-Fe3O4, Fe-FeO and Mo-MoO2. Within the selected frequency range of 102–106 Hz, the experimental results indicate that the grain interior conduction mechanism is characterized by a semi-circular curve on an impedance diagram. As a function of increasing pressure, the electrical conductivity of polycrystalline olivine compacts decreases, whereas the activation enthalpy and the temperature-independent pre-exponential factors increase slightly. The activation energy and activation volume of polycrystalline olivine compacts were determined to be 141.02±2.53 kJ/mol and 0.25±0.05 cm3/mol, respectively. At a pressure of 4.0 GPa, electrical conductivity was observed to increase as a function of increasing oxygen fugacity, and the relationship between electrical conductivity and oxygen fugacity can be described as log10 (σ) = (2.47±0.085) + (0.096±0.023)×log10fO2 + (–0.55±0.011)/T, which presents the exponential factor q (˜0.096). Our observations demonstrate that the primary conduction mechanism for polycrystalline olivine compacts is a small polaron.

This Research Communication addresses the hypothesis that fat, protein, lactose and total solids content can be predicted using daily milk yield (DMY), pH, electrical conductivity (MEC) and refractive index (RI) of milk as predictors. It also addresses the possibility of these measurements being used for on-farm benchmarking activities towards selecting the highest yielding animals and flocks regarding milk quality traits (MQT). A total of 308 purebred Frizarta ewes were used for the study. From each individual ewe, a composite milk sample was collected. pH, MEC and RI of milk were measured and the samples were assayed for fat, protein, lactose and total solids content, using an automatic infrared milk analyser. The predictive value of DMY, pH, MEC and RI of milk on its MQT was assessed using multiple linear regression analysis. Significant regression equations were produced for all of the studied traits. RI and MEC were significant and reliable predictors for all studied MQT, whereas DMY was a significant predictor for most MQT with the exception of protein content. pH was a marginally significant predictor for some of the MQTs at the initial development of the equations but proved unreliable after bootstraping. Using these equations a number of ewes varying from 75 (for fat) to 97 (for protein) out of the 100 highest MQT yielders were correctly predicted, whereas, none of the ewes out of the 100 lowest MQT yielders was mispredicted as a high yielder for protein-, lactose- and total solids- content. Three out of 100 lowest fat-yielders were mispredicted as high fat-yielders. Similar equations can be used for benchmarking activities towards selecting the highest protein-, fat-, lactose- and total solids- yielding animals and flocks in cases where laboratories for MQT analyses are not readily available or the cost of chemical analyses is high. The method can be regarded as a handy tool for the dairy industry to readily assess milk quality at the farm level.

In Asia, a significant area under rice is affected by salinity. Salt stress can affect growth of crops as well as weeds. A study was conducted in a greenhouse to determine the effect of salinity (electrical conductivity [EC] of 1, 6, 12, 18, and 24 dS m−1) on growth of barnyardgrass, horse purslane, junglerice, and rice. Growth variables were analyzed using regression analysis. The tested levels of EC influenced leaf production of barnyardgrass and junglerice but not that of horse purslane. As compared with the control treatment (EC of 1 dS m−1), shoot biomass of barnyardgrass decreased by only 24% at 12 dS m−1, whereas rice biomass declined by 59% at this level of EC. At EC of 24 dS m−1, barnyardgrass still produced 4% of the biomass of the control treatment, whereas rice did not survive at this level of EC. Junglerice shoot biomass decreased by 73% at 18 dS m−1 EC compared with the control treatment, whereas rice shoot biomass declined by more than 86% at 18 dS m−1 EC. An EC of 10 dS m−1 was required to inhibit 50% shoot biomass of rice, whereas the EC to inhibit 50% shoot biomass of barnyardgrass and junglerice was 15 and 13 dS m−1, respectively. Shoot biomass of horse purslane was not influenced by the tested levels of EC. At the highest EC (24 dS m−1), at which rice did not survive, horse purslane shoot biomass was similar to that of the control treatment. In all weed species, data for root biomass showed trends similar to those of shoot biomass. The results of this study suggest that weeds were more tolerant to salt than rice, and horse purslane was the most tolerant species among the weeds.

Understanding the spatial variability of herbicide sorption to soil is important in determining the bioavailability as well as leaching potential of the chemical across a field. Multiple methods have been used to estimate herbicide sorption variability at the macroscale, but it has been difficult to measure soil heterogeneity or herbicide sorption at the individual field level. One method to determine soil heterogeneity is to create zones within a field based on maps of the apparent bulk soil electrical conductivity (ECa). These zones can be used to direct soil sampling to determine the fraction of organic carbon (foc) of each zone. The foc, in turn, can be used to predict the variability of herbicide binding among zones. Surface (0 to 30 cm) bulk-soil electrical conductivity (ECs) maps were made for three sandy fields in eastern Colorado, and soil samples were taken from the ECs zones within each field. The foc, and the soil–water partition coefficient (Kd) for EPTC, metribuzin, and metolachlor were determined for each sample. There were significant correlations between ECs and foc (R = 0.75) and between foc and Kd for EPTC, metribuzin, and metolachlor (R = 0.66, 0.61, and 0.71, respectively) across all three fields. Additional soil samples taken from the ECs zones located in previously unsampled areas of the three fields showed that one could reasonably predict Kd values for metribuzin, metolachlor, and possibly, EPTC based on the foc zones derived from ECs maps.

Greenhouse studies were conducted to determine the relative salinity tolerance of foxtail barley and seven desirable pasture grasses. Grass species were reed canarygrass, timothy, altai wildrye, tall fescue, tall wheatgrass, orchardgrass, creeping meadow foxtail, and foxtail barley. Grasses were exposed to increasing electrical conductivity levels of NaCl and CaCl2 salt solution over time. Grass species were compared using a cumulative value of salt exposure (ECdays), which was calculated to account for the electrical conductivity (EC) and the time a plant was exposed at that level of conductivity. Salinity tolerance varied among grass species. Increasing EC significantly reduced plant biomass of all species. All grass species experienced a 50% biomass reduction (GR50) between 271 and 512 ECdays in 2008 and between 297 and 575 ECdays in 2009. Foxtail barley was among the most salt tolerant (GR50 = 512 and 525 ECdays), requiring the highest salt exposure in 2008 and the second-highest exposure in 2009 to reduce biomass 50%. Grass mortality increased with increasing EC levels. Reed canarygrass and timothy were most susceptible to increasing salinity, with 50% mortality (LD50) of both grass species occurring between 983 and 1,186 ECdays. Moderate salinity tolerance was exhibited by orchardgrass, which required 1,977 and 1,844 ECdays; creeping foxtail, which required 1,998 and 2,431 ECdays; and tall fescue, which required 2,501 and > 2,840 ECdays to LD50 in 2008 and 2009, respectively. Foxtail barley, altai wildrye, and tall wheatgrass were most tolerant of salinity and persisted with little mortality occurring at 3,033 and 2,840 ECdays in 2008 and 2009, respectively. All grass species with higher growth rates than foxtail barley and altai wildrye were more susceptible to salinity, with the exception of tall wheatgrass. Growth rates of foxtail barley and altai wildrye were less than they were for other grasses, suggesting that slower growth rates may aid in salinity tolerance.

The apparent electrical conductivity of the subsurface along the Dutch coast between ‘Wassenaarse Slag’ (beach post 92.250) and north of Noordwijk aan Zee (beach post 77.750) reflects the spatial distribution of Holocene coastal deposits. Using a Geonics EM-34 a threefold division based on the mean electrical conductivity could be made in the outlet area of the River Old Rhine. 1) A section showing a sequence of sandy deposits that resembles the Schoorl Member of the Naaldwijk Formation on top of the Zandvoort Member of the Naaldwijk Formation. 2) A section underlain by a shallow clay/peat layer of varying thickness belonging to the Naaldwijk Formation (Walcheren Member) / Nieuwkoop Formation (Hollandveen Member), intercalated within the Schoorl Member and Zandvoort Member of the Naaldwijk Formation. South of the Old Rhine locally Wormer Member deposits of the Naaldwijk Formation underlie these clay/peat layers. 3) A section characterized by channel fill deposits of the former Rhine reaching to -20 m below Normaal Amsterdam Peil (N.A.P.), and belonging to deposits of the Wormer Member of the Naaldwijk Formation, and to two facies of the Naaldwijk Formation (Walcheren Member). The geophysical transect was calibrated using existing nearby drill hole data, so that a continuous snapshot of the subsurface was gained. Therefore this research also contributes to the recent genesis of this part of the Dutch coast.

We report a cost-effective, surfactant-free, and scalable synthesis technique for lead telluride (PbTe) nanocubes by a chemical precipitation method. The high-resolution transmission electron microscopy studies indicated the evolution of nucleation centers (spherical) into nanocubes with the addition of the Pb and Te atoms. The spark plasma sintered PbTe nanocubes exhibited an enhanced Seebeck coefficient, S > +400 µV, higher than the reported values of the bulk PbTe over an extended temperature range of 300–425 K, and a moderate electrical conductivity, σ ∼ 8000 S/m at 300 K. A significant reduction in the lattice thermal conductivity was observed due to effective phonon scattering from the presence of numerous interfaces introduced by nanostructuring. The resulting figure-of-merit (ZT) ∼ 0.45 at 300 K is higher than the reported values at this temperature in other PbTe nanostructures. Moreover, a moderate thermoelectric compatibility factor makes the PbTe nanocubes a potential candidate for green energy generation.

Solute leakage is used as an indicator of membrane damage during desiccation of recalcitrant seeds. We re-examined this phenomenon and its utility by comparing recalcitrant Spartina alterniflora and orthodox Spartina pectinata seeds, as well as drying isolated embryos or embryos isolated after whole-seed drying. During drying, intact seed leakage (electrical conductivity and absorbance at 280 nm) was independent of seed moisture content, dormant/non-dormant state or desiccation tolerance. Embryos from both Spartina species, isolated after drying within the intact seed, exhibited increased leakage, especially below 40% (dry weight basis, DWB) seed moisture, the critical water content for viability loss in Spartina alterniflora. When isolated embryos were dried, the pattern and extent of increased solute leakage were similar in both Spartina species, even though S. pectinata embryos were >95% viable and S. alterniflora embryos were < 20% viable. We conclude that increased solute leakage is an artefact of embryo excision and not an accurate indicator of desiccation damage to recalcitrant Spartina alterniflora seeds.

This report presents the overview of the results of investigation of transport properties of warm dense matter in the conditions with strong coupling generated as a result of the shock or multiple shock compression of substance up to the megabar pressure range. We consider the results of measurements of the electrical conductivity in two different regions. The first one is the high temperature region, where the temperatures are of the order or much higher than the ionization potential I of the compressed substance. The region of “pressure ionization” where T ≪ I is the most interesting from the point of view of the specific plasma phase transitions. A few amounts of experimental data on shock compressed matter viscosity are discussed. For the estimations of shear viscosity of strongly coupled plasma experimental data on measurements of electrical conductivity of hydrogen, deuterium and rare gases under intense shock compression were used. It is shown that the ratio of shear viscosity coefficient to volume density of entropy of strongly coupled plasma is of the order of a lower bound, predicted by Kovtun et al. (2005) in frames of string theory methods.