Variation In Specific Conductivity Research Articles

Effect of Benzheterazoles on the Micellar Behavior of Sodium Dodecylsulfate in Dimethylsulfoxide: A Conductometric and Spectroscopic Approach

AbstractIn this article, we report intermolecular interactions in terms of the effect of benzfused heterocyclic compounds, i.e., 2‐thioureidobenzimidazole and 2‐thioureidobenzoxazole (0.00, 0.01, and 0.05 mol kg−1), on the micellization behavior of sodium dodecylsulphate (SDS) (1–52 mmol kg−1) in dimethylsulphoxide (DMSO) at different temperatures (293.15–313.15 K) through conductometric and spectroscopic investigations. The variation of specific conductance with SDS concentration has been utilized to estimate the critical micelle concentration ( CMC). The above‐performed techniques infer that the presence of additives results in a decrease in the CMC values. Various standard thermodynamic parameters such as free energy change (), enthalpy change (), and entropy change () of micellization have been determined using the temperature dependence of CMC. The above calculated parameters and also UV–visible and fluorescence spectroscopy have been used to obtain information regarding the various interactions between the compounds and surfactant aggregates. In addition, an attempt has also been made to examine the minimum inhibitory concentration (MIC) of the heterocompounds, which indicates the effectiveness of these compounds against fungus growth at a particular concentration. These synthetic heterocyclic compounds find increasing applications in material science, medicinal chemistry, and biochemistry due to their antifungal and antioxidant properties.

Evolution of noble gas and water isotopes along the regional groundwater flow path of the Konya Closed Basin, Turkey

Noble gas and water isotope compositions of regional groundwater were investigated along two transects in the Konya Closed Basin (KCB) of central Turkey. According to the 3He/4He versus Ne/He plot of samples, crust (up to 86%) and mantle (up to 26%) appear to be the primary and secondary sources of dissolved He in groundwater, respectively. After the beginning of both transects where the flow domain is confined, both 3He and 4He accumulate steadily in groundwater. Thereafter, the intermediate recharge from the surface in the unconfined part of regional flow system disrupts the steady accumulation trend of 3He and 4He. Effect of intermediate recharge on regional groundwater is also indicated by the spatial variations in specific conductance, temperature, water isotopes, and tritium signals. At the last part of the flow domain where the system becomes confined again 3He and 4He start to accumulate in the eastern transect whereas they continue to decline in the western transect probably because of degassing to atmosphere through thinner confining unit. The 4He accumulation rates based on radiocarbon ages and 4He concentrations along both transects between the mountain flank and Obruk Plateau are in agreement with literature values but differ from each other. The accumulation rate along the eastern and western transects are 4.93 × 10-11 cm3 STP/g•year and 1.99 × 10-10 cm3 STP/g•year, respectively. These values reveal that the 4He accumulation rates may differ at least four times at different parts of a single aquifer, which are located 30 to 60 km apart. It is understood that any groundwater age-dating attempt by 4He requires a firm pre-assessment of spatial 4He accumulation rates. He isotope signal in the groundwater of KCB proves the mantle and/or crustal gas input into the carbonate aquifer in which an on-going hypogenic karst development has been suspected.

Embolism resistance of three boreal conifer species varies with pit structure

While tracheid size of conifers is often a good proxy of water transport efficiency, correlations between conifer wood structure and transport safety remain poorly understood. It is hypothesized that at least some of the variation in bordered pit and tracheid structure is associated with both transport efficiency and embolism resistance. Stem and root samples from three boreal Pinaceae species were collected to test this hypothesis. Tracheid and pit anatomy were studied using light microscopy as well as scanning and transmission electron microscopy. While tracheid size explained at least 90% of the variation in specific conductivity for stem and root samples, the strongest correlations with embolism resistance occurred at the pit level. Both torus thickness and depth of the pit chamber showed a linear increase with greater vulnerability to cavitation. Greater embolism resistance was correlated with increasing wood density and tracheid wall reinforcement. A thinner torus may be more flexible and better able to seal the pit aperture. The pit chamber depth is proportional to the distance that the margo needs to deflect for pit aspiration.

Modeling study of migration-driven lateral instability in autocatalytic systems

The lateral stability of reaction fronts in simple autocatalytic models with the components carrying various charges is investigated when the system is exposed to an inhomogeneous electric field parallel to the direction of propagation. The enhanced migrational flux of the reactant destabilizes the planar front giving rise to a cellular structure because the electric field strength is greater on the reactant side of the reaction front. The onset of instability depends not only on the charge difference between the reactant and the autocatalyst but also on the variation of specific conductance in the course of the reaction, which results in a difference in electric field strength on the opposite sides of the reaction front.

Near Real-Time Monitoring and Mapping of Specific Conductivity Levels Across Lake Texoma, USA

A submersible sonde equipped with a specific conductivity probe, linked with a global positioning satellite receiver was developed, deployed on a small boat, and used to map spatial and temporal variations in specific conductivity in a large reservoir. 7,695 sample points were recorded during 8 sampling trips. Specific conductivity ranged from 442,uS/cm to 3,378,uS/cm over the nine-month study. The data showed five statistically different zones in the reservoir: 2 different riverine zones, 2 different riverine transition zones, and a lacustrine zone (the main lake zone). These data were imported to a geographic information system where they were spatially interpolated to generate 8 maps showing specific conductivity levels across the entire surface of the lake. The highly dynamic nature of water quality, due to the widely differing nature of the rivers that flow into the reservoir and the effect of large inflows of fresh water during winter storms is easily captured and visualized using this approach.

A Reexamination of the Relationship between Electrofishing Catch Rate and Age‐0 Walleye Density in Northern Wisconsin Lakes

AbstractWe quantified the relationship between the population density (number/acre) of age‐0 walleyes Sander vitreus (formerly Stizostedion vitreum) and electrofishing catch per effort (CPE; number/mi) in 19 Wisconsin lakes to update a 1982 analysis by Serns, who used linear regression through the origin to develop a model from a small data set that has been widely used to estimate age‐0 walleye density from electrofishing CPE. We added new data, explicitly tested for the linearity of the relationship, and accounted for the effect of measurement errors. We found that electrofishing CPE was nonlinearly related to the population density of age‐0 walleyes, which indicated that the catchability of age‐0 walleyes to electrofishing declined with population density. The measurement errors in electrofishing CPE were more than nine times as great as those in age‐0 walleye population density, so that the parameters of the relationship between electrofishing CPE and age‐0 walleye density were accurately estimated by ordinary‐least‐squares linear regression. Among lakes, the variation in the catchability of age‐0 walleyes to electrofishing was positively related to the variation in specific conductivity but not to the variation in other physical features (shoreline complexity or littoral area) or chemical features (alkalinity or pH). Within lakes, the variation in the catchability of age‐0 walleyes to electrofishing was negatively related to the variation in temperature at the time of sampling. We recommend that electrofishing CPE only be used as a crude index of age‐0 walleye population density.

Physicochemical properties of mixed surfacant systems: sodium dodecyl benzene sulfonate with triton X 100

The physicochemical properties of a mixed surfactant system were studied under various conditions. The surfactants were anionic sodium dodecyl benzene sulfonate and nonionic Triton X 100. Variation of specific conductivity with concentration was used to determine the critical micelle concentration of anionic as well as the mixed surfactants. Iodine solubilization method was used to determine the CMC of the nonionic surfactant. The interaction parameter between the surfactant molecules were calculated. The wetting, foaming and detergent properties of mixed surfactant systems were studied. The variation of contact angle of the solution with teflon surface as a function of surfactant concentration was found to be a reasonably good method to determine the critical micelle concentration. Viscosity and cloud points were also determined. All these quantities are discussed.

Quantitative Treatment of the Variation of some Physico-Chemical Properties of Purified Colloidal Electrolytes with Dilution

It is generally assumed that in aqueous solution each particle or macromolecule of the colloidal electrolyte is surrounded by an ion-atmosphere in which the number density of the counterions is greater than that of the co-ions, but the particle or the macro molecule with its ion-atmosphere, as a whole, is electrically neutral and that the thickness of the ion-atmosphere is small compared to the distance between the centres of two neighbouring particles except when the concentration of the colloid is very high. Starting with this simplified picture and assuming further that in a highly purified colloidal solution the thickness of the ion atmosphere and the activities of the (diffusible) ions in the inter micellar solution do not change appreciably with dilution equations have been deduced to account quantitatively for the variation of (1) counter-ion activity, (2) the specific conductivity and (3) the osmotic pressure with the concentration of the colloidal electrolyte. The equations have been subjected to test using the data available in the literature on congo red, cetylsulphonic acid benzopurpurin 4B and its isomer prepared from metatolidine, azarectic (neem gum) acid, gum arabic acid, polyacrylic acids, clay acids and their salts and have been found satisfactory. Furthermore, using the aforesaid expression for the variation of specific conductivity with dilution, Smoluchowski's equation for the electroviscous behaviour of colloids has been modified and equations have been deduced to account for the variation of electro-viscosity of solutions of colloidal electrolytes with dilution. These equations have been subjected to test using the data available in the literature on viscosity of sols of sodium thymus nucleate, gum arabic acid, polyacrylic acids of different degrees of polymerisation, silver iodide, bovine serum albumin. β-lactoglobulin, ribonuclease and mono-disperse polystyrene lattices prepared by emulsion polymerisation using Na-stearate and Na-dodecylsulphate as emulsifiers and have been found satisfactory.

Changes in Electrical Properties during Hydration and Setting of Cements

Variations in specific conductivity during hydration and setting of cements and clinker minerals have been reported. Measurements on the specific conductivity, for 48 hrs at regular intervals, of the suspensions of cement with adequate W/C ratio have shown two peaks in a plot of time vs specific conductivity and only one peak in case of clinker mineral. The effect of gypsum additive on specific conductivity during hydration of cement is also described. Suitable explanations for variations in conductivity, and effect of gypsum on conductivity, during hydration and setting of cements have been proposed.

Preparation and Properties of One-Dimensional Bis(OXALATO)Platinates

Abstract The preparation of the new 1-D conductors (NH4)1.169[Pt(C2O4)2][mddot]H2O (Am-OP) and [(CH3)2NH2]1.61 [Pt(C2O4)2] (DMA-OP) is described. The average intra-chain Pt-Pt separation is 2.82 A in Am-OP and 2.80 A in DMA-OP. The specific conductivity in the platinum atom chain direction is ˜50 Ω−1 cm−1 and ˜20 Ω−1 cm−1 for Am-OP and DMA-OP respectively. The variation of specific conductivity with temperature in the platinum atom chain direction is compared with that of other 1-D metallic complexes.

Factors Influencing the Spatial Distribution of Phytoplankton in a Small Productive Lake

(I) A study of the horizontal and vertical distribution of the phytoplankton in a small productive lake, Esthwaite Water in the Lake District, was made during thermal stratification. Distribution patterns of the phytoplankton were related to horizontal variations in specific conductance and pH and to the vertical distribution of temperature and oxygen. (2) A diel study of the changes in the vertical distribution of the dominant algal species, chlorophyll a, temperature and oxygen was also made at the time of maximum phytoplankton density. (3) Appreciable non-uniform horizontal distribution of the phytoplankton was observed only when buoyant blue-green algae or the dinoflagellate Ceratium hirundinella were present. (4) On most occasions horizontal variations of phytoplankton density showed clear systematic patterns related to wind-induced water movements. These patterns were particularly pronounced when individual species formed well-defined vertical aggregations in regions of upwelling or downwelling water. (5) Observations on the vertical distribution of Ceratium showed that this alga underwent diel vertical migrations, with a proportion of the population aggregating at the metalimnion at night. During calm weather large daytime sub-surface accumulations of the alga were found. Vertical perturbations of such small-scale, vertical aggregations may have produced the extreme small-scale horizontal variations of algal concentration noted on two occasions. (6) Daily mean wind speeds above 100 km day 1 were normally sufficient to break down patches of phytoplankton, whereas values below 50 km day-' allowed the formation of dense, small-scale, near-surface aggregations of Ceratium. (7) Lateral transport of algal cells at the metalimnion by water currents could assist in maintaining high nutrient gradients at the cell surface, and contribute to the sustained growth of the phytoplankton.

Solute Variations in Small Catchment Streams: Some Comments

The study of temporal variations in solute concentrations in streams has attracted the attention of many workers during the last twenty years. They have demonstrated that solute concentration can exhibit marked seasonal and stormbased variation and several important controls on solute levels have been proposed. In order to document variations in solute concentrations over short periods of time, in response to hydrometeorological controls, an intensive sampling programme is required. Results obtained from continuous monitoring and frequent sampling in some Devon streams are presented to illustrate the nature and extent of short-term temporal variations in solute levels. IN a recent paper, Imeson (1973) has pointed to the increasing interest in the solute loads of rivers shown by geomorphologists and ecologists and to the particular need to focus attention upon temporal variations. However, if it is suggested that this particular field has received little attention, then this ignores a considerable volume of literature representing studies by workers in various disciplines and which can be only briefly sampled in this communication. The variation in solute levels associated with fluctuations in discharge has been documented by many workers, particularly in the United States. In 1948, Hem (1948) pointed to interesting temporal variations in specific conductance and chloride concentration in rivers of the southwestern United States and these were attributed primarily to the dilution of baseflow constituents during periods of high flow, although diurnal fluctuations were also described. This dilution effect was subsequently substantiated, elaborated and quantified by many other studies (e.g. Durum, I953; Korven and Wilcox, 1964; Ward, I963). Goto (1961) described detailed stormperiod variations in several chemical components within a Japanese stream and Hendrickson and Krieger (I960) and Toler (1965) reported clockwise and anticlockwise hysteretic effects in the relationship between solute concentrations and discharge during individual storm events in American rivers. Examples have also been cited where certain solute concentrations exhibit either a positive relationship with discharge or no significant relationship at all (e.g. Edwards, I973). The frequent use of the dilution effect to explain temporal variations in solute levels has prompted the application of simple mixing models based on the mass balance equation and involving individual run-off components (e.g. Hart et al., 1964; Hem, I970; Steele, 1968; Walling, I974) or theoretical storage reservoirs (Hall, I970, I97I; Johnson et al., 1969). Other studies have highlighted control by additional factors. Seasonal effects on the relationship between solute concentrations and discharge have been described by Glancy et al. (1972), Gunnerson (1967), Ledbetter and Gloyna (1964) and Steele (1968). Work in Russia (e.g. Skakalskiy, 1966) has focused attention on the flow paths of individual run-off components. Temporarily increased concentrations during the initial periods of storm run-off events have been related to the 'flushing' of accumulated salts by Edwards (i973), Steele (1968) and Walling (1974), and Gburek and Heald (1970) have attempted to distinguish between those ions which show smooth changes during storm events and those which fluctuate more rapidly as a result of control

Flooded rice soils of Northern Australia. II. Chemical profiles

Changes in chemical and electrochemical properties of a flooded calcareous soil sown to rice were monitored during the season of flooding. Considerable variations in specific conductivity, individual cation concentrations, bicarbonate concentration, and carbon dioxide pressures were observed within the soil profile to depths of 30 cm. Redox potential and pH tended to be uniform within a profile except when CaSO4 or H2SO4 were added to the surface soil. Both field and pot experiments showed profile variations in soil properties and the significance of this is discussed in terms of the root distribution of rice.

Dielectric dispersion and its temperature variation in calcite single crystals

The variation of dielectric constant and loss of calcite single crystals with frequency and temperature over wide ranges (102 to 2.4×1010c/s and −193 to 450 °C) in two orientations of the crystal, namely, the electric field (i) parallel to the optic axis and (ii) perpendicular to the optic axis, has been studied and the results reported. The dielectric constant at 25 °C in both orientations (E‖, 7.8 andE⊥, 8.2) is frequency-independent. The dielectric loss shows a minimum in the 105 to 108 c/s region. Dielectric constant as a function of temperature exhibits two distinct regions: frequency-independent (−193 to 50 °C) and frequency-dependent (50 to 450 °C). The temperature variation of specific conductivity can be represented by a sum of two exponentials, e.g.,\(\sigma = Ae^{ - E_1 /kT} + Be^{ - E_2 /kT}\) with the usual notation; the constants have different values in the two orientations. The intrinsic conductivity with larger activation energy (E‖ 0.91 eV andE⊥ 1.05 eV) is attributed to the movement of lattice vacancies in the crystal. The 15% larger value for the intrinsic activation energy alongE⊥ optic axis over the other orientation may be due to a probably large electrostatic interaction between the charge carriers and the lattice ions in this orientation.

Seasonal Variation in Specific Conductivity of Wood in Tropical Plants with Reference to Leaf Fall

1. There is a fundamental distinction between monopodial and sympodial growth, the conductivity in the latter falling off rapidly from the base to the apex. 2. The distinction drawn by Farmer between deciduous and evergreen trees refers primarily to the respective demands made by them on the water supply for purposes of transpiration. 3. There is a correlation between the period of leaf fall and the increased capacity of the wood for conducting water.