specific conductance
Recently Published Documents


TOTAL DOCUMENTS

310
(FIVE YEARS 50)

H-INDEX

33
(FIVE YEARS 3)

Author(s):  
Tae Jun Yoon ◽  
Jacob D. Riglin ◽  
Prashant Sharan ◽  
Robert P. Currier ◽  
Katie A. Maerzke ◽  
...  

Abstract Specific conductance and frequency-dependent resistance (impedance) data are widely utilized for understanding the physicochemical characteristics of aqueous and non-aqueous fluids and for evaluating the performance of chemical processes. However, the implementation of such an in-situ probe in high-temperature and high-pressure environments is not trivial. This work provides a description of both the hardware and software associated with implementing a parallel-type in-situ electrochemical sensor. The sensor can be used for in-line monitoring of thermal desalination processes and for impedance measurements in fluids at high temperature and pressure. A comparison between the experimental measurements on the specific conductance in aqueous sodium chloride solutions and the conductance model demonstrate that the methodology yields reasonable agreement with both the model and literature data. A combination of hardware components, a softwarebased correction for experimental artifacts, and computational fluid dynamics (CFD) calculations used in this work provide a sound basis for implementing such in-situ electrochemical sensors to measure frequency-dependent resistance spectra.


Phytotaxa ◽  
2022 ◽  
Vol 530 (2) ◽  
pp. 221-229
Author(s):  
EVGENIY GUSEV ◽  
YVONNE NĚMCOVÁ ◽  
MAXIM KULIKOVSKIY

Mallomonas voloshkoae sp. nov. was described from Russia based on silica-scale morphology studied by means of transmission and scanning electron microscopy. This species belongs to the section Striatae and is characterised by scales with wide anterior flanges, forming wing-like extensions. This species is most similar in scale ultrastructure to M. pechlaneri. Mallomonas voloshkoae was reported in four mountain lakes of the Transbaikal area and was found in acidic to slightly acidic conditions with very low values of specific conductance. Mallomonas pechlaneri was reported in Russia for the first time. This is the first record of this species after the description of this taxon in Europe. Mallomonas pechlaneri was found in three oligotrophic habitats in the Altay and Sayan Mountain areas.


2022 ◽  
Author(s):  
Paul M. Mayer ◽  
Michael J. Pennino ◽  
Tammy A. Newcomer-Johnson ◽  
Sujay S. Kaushal

AbstractStream restoration is a popular approach for managing nitrogen (N) in degraded, flashy urban streams. Here, we investigated the long-term effects of stream restoration involving floodplain reconnection on riparian and in-stream N transport and transformation in an urban stream in the Chesapeake Bay watershed. We examined relationships between hydrology, chemistry, and biology using a Before/After-Control/Impact (BACI) study design to determine how hydrologic flashiness, nitrate (NO3−) concentrations (mg/L), and N flux, both NO3− and total N (kg/yr), changed after the restoration and floodplain hydrologic reconnection to its stream channel. We examined two independent surface water and groundwater data sets (EPA and USGS) collected from 2002–2012 at our study sites in the Minebank Run watershed. Restoration was completed during 2004 and 2005. Afterward, the monthly hydrologic flashiness index, based on mean monthly discharge, decreased over time from 2002 and 2008. However, from 2008–2012 hydrologic flashiness returned to pre-restoration levels. Based on the EPA data set, NO3− concentration in groundwater and surface water was significantly less after restoration while the control site showed no change. DOC and NO3− were negatively related before and after restoration suggesting C limitation of N transformations. Long-term trends in surface water NO3− concentrations based on USGS surface water data showed downward trends after restoration at both the restored and control sites, whereas specific conductance showed no trend. Comparisons of NO3− concentrations with Cl− concentrations and specific conductance in both ground and surface waters suggested that NO3− reduction after restoration was not due to dilution or load reductions from the watershed. Modeled NO3− flux decreased post restoration over time but the rate of decrease was reduced likely due to failure of restoration features that facilitated N transformations. Groundwater NO3− concentrations varied among stream features suggesting that some engineered features may be functionally better at creating optimal conditions for N retention. However, some engineered features eroded and failed post restoration thereby reducing efficacy of the stream restoration to reduce flashiness and NO3− flux. N management via stream restoration will be most effective where flashiness can be reduced and DOC made available for denitrifiers. Stream restoration may be an important component of holistic watershed management including stormwater management and nutrient source control if stream restoration and floodplain reconnection can be done in a manner to resist the erosive effects of large storm events that can degrade streams to pre-restoration conditions. Long-term evolution of water quality functions in response to degradation of restored stream channels and floodplains from urban stressors and storms over time warrants further study, however.


2021 ◽  
Vol 25 (12) ◽  
pp. 6309-6332
Author(s):  
Maxime P. Boreux ◽  
Scott F. Lamoureux ◽  
Brian F. Cumming

Abstract. While interactions between groundwater and lake-water influence water chemistry, water balance, aquatic organisms, biochemical cycles and contamination levels, they remain a poorly studied component of lake hydrology. Identifying the controls of groundwater and lake-water interactions at the landscape level and classifying lakes into categories based on their degree of interaction with the groundwater can provide insights into a lake's sensitivity and vulnerability to environmental stressors. Such information can also provide baseline conditions for comparison to future changes that are important for water management and conservation. To this end, water chemistry and water isotopic composition were investigated in a set of 50 boreal lakes located at different elevations in an esker system near Timmins, Ontario. Analyses focused on stable isotopic ratios of hydrogen and oxygen and specific conductance as indicators of the position of a lake with respect to the influence of groundwater. Both isotopic composition and specific conductance distinguished higher-elevation groundwater-recharge lakes from lower-elevation groundwater-discharge lakes. Groundwater-recharge lakes were high-elevation lakes characterized by enriched isotopic values and low values of specific conductance. In contrast, groundwater-discharge lakes were isotopically depleted and had higher values of specific conductance and occurred at lower elevations. An intermediate group of lakes was also defined (termed seepage lakes) and had intermediate isotopic and water-chemistry characteristics compared to recharge and discharge lakes. Differences in water geochemistry between field campaigns revealed that upland groundwater-recharge lakes showed evidence of evaporative drawdown, indicating sensitivity to short-term changes in climate, whereas the lower-elevation groundwater-discharge lakes showed little variation between seasonal samples and consequently would likely be affected only by hydroclimatological changes of greater duration and magnitude.


2021 ◽  
Vol 3 ◽  
Author(s):  
Elizabeth A. Bihn ◽  
Kurt J. Mangione ◽  
Bill Lyons ◽  
Annette L. Wszelaki ◽  
John J. Churey ◽  
...  

An Irrigation Water Quality Database was developed to help assess the microbiological quality of irrigation water used in fruit and vegetable production in 15 counties in New York (NY) State. Water samples from Tennessee (TN) were also included in the database. Four water quality parameters, quantified generic Escherichia coli, specific conductance, pH, and turbidity, were tested. Ground, reservoir, and running water were sampled over 2 years (2009 and 2010), covering three seasons each year (spring, summer, and fall). TN data are for all three seasons in 2010 only. Overall in NY (254 total samples), ground water had a geometric mean of 1 most probable number (MPN)/100 ml, reservoir water had a geometric mean of 8 MPN/100 ml, and running water had a geometric mean of 52 MPN/100 ml. Overall in TN (63 total samples), ground water had a geometric mean of 1 colony forming unit (CFU)/100 ml, reservoir water had a geometric mean of 5 CFU/100 ml, and running water had a geometric mean of 38 CFU/100 ml. These values are all below the 126 MPN/100 ml United States Environmental Protection Agency's Ambient Water Quality Standards (AWQS) standard for fresh water. The presence of E. coli had very weak but sometimes statistically signficiant correlatation with water specific conductance, pH, and turbidity, depending on the water source but the r-squared effect was not strong enough to make the other measurements a substitute for testing specifically for E. coli in water.


2021 ◽  
Author(s):  
Kaytee Pokrzywinski ◽  
West Bishop ◽  
Christopher Grasso ◽  
Kaitlin Volk ◽  
Kurt Getsinger

US Environmental Protection Agency (USEPA) approved algaecides and herbicides are frequently utilized to manage nuisance algae and aquatic macrophytes. However, there is limited information available on the effectiveness of these products for the management of starry stonewort. Thus, the goal of this research was to discern effective chemical control products for later growth stages of starry stonewort using mesocosm studies. Eleven treatments were evaluated using various combinations of four copper-based products, endothall, diquat, and carfentrazone – all with USEPA registrations for use in aquatic sites. To assess treatment efficacy, water quality, photophysiology, biomass changes, and bulbil viability were evaluated. Nine of the eleven treatments yielded lower dissolved oxygen concentrations and higher specific conductance when compared to the control. Photophysiological response varied by condition, but seven of eleven treatments resulted in significantly lower fluorescent and maximum fluorescent yield. Five of these also exhibited significantly lower average photosynthetic yields, with combination treatments resulting in more drastic decreases. Ten of the eleven treatments had significantly less biomass compared to the control when measured via wet weight; however, only four treatments were significant when measured via dry weight. Lastly, all conditions utilizing copper-based products significantly reduced bulbil viability while non-copper products had no impact.


2021 ◽  
Vol 13 (17) ◽  
pp. 9898
Author(s):  
Fen Yang ◽  
Hossein Moayedi ◽  
Amir Mosavi

Predicting the level of dissolved oxygen (DO) is an important issue ensuring the sustainability of the inhabitants of a river. A prediction model can predict the DO level using a historical dataset with regard to water temperature, pH, and specific conductance for a given river. The model can be built using sophisticated computational procedures such as multi-layer perceptron-based artificial neural networks. Different types of networks can be constructed for this purpose. In this study, the authors constructed three networks, namely, multi-verse optimizer (MVO), black hole algorithm (BHA), and shuffled complex evolution (SCE). The networks were trained using the datasets collected from the Klamath River Station, Oregon, USA, for the period 2015–2018. We found that the trained networks could predict the DO level of 2019. We also found that both BHA- and SCE-based networks could predict the level of DO using a relatively simple configuration compared to that of MVO. From the viewpoints of absolute errors and Pearson’s correlation coefficient, MVO- and SCE-based networks performed better than BHA-based networks. In synopsis, the authors recommend MVO- and MLP-based artificial neural networks for predicting the DO level of a river.


Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2132
Author(s):  
Daniel Rui Chen ◽  
Megha Chitranshi ◽  
Paa Kwasi Adusei ◽  
Mark Schulz ◽  
Vesselin Shanov ◽  
...  

The carbon nanotube (CNT) is celebrated for its electrothermal property, which indicates the capability of a material to transform electrical energy into heat due to the Joule effect. The CNT nanostructure itself, as a one-dimensional material, limits the electron conduction path, thereby creating a unique heating phenomenon. In this work, we explore the possible correlation between CNT alignment in sheets and heating performance. The alignment of carbon nanotubes is induced by immersion and stretching in chlorosulfonic acid (CSA) solution. The developed CSA-stretched CNT sheet demonstrated excellent heating performance with a fast response rate of 6.5 °C/s and reached 180 °C in less than 30 s under a low voltage of 2.5 V. The heating profile of the stretched CNT sheet remained stable after bending and twisting movements, making it a suitable heating material for wearable devices, heatable smart windows, and in de-icing or defogging applications. The specific strength and specific conductance of the CSA-stretched CNT sheet also increased five- and two-fold, respectively, in comparison to the pristine CNT sheet.


2021 ◽  
Vol 37 (3) ◽  
pp. 704-709
Author(s):  
Rajesh Kumar Sharma ◽  
Priyanka Sharma

Physicochemical studies of amino acids in an aqueous medium can provide significant knowledge about the stabilization mechanism of proteins.In this study, the viscosity (ƞ), surface tension (γ), density (ρ) and the specific conductance (κ) measurements have been carried out for amino acid L-lysine (0.02 to 1.6M) in aqueous solutions at 293.15K. The experimental data shows that there is an increase in the viscosity, surface tension, conductance, and density of the L-lysine with and without glucose, sucrose, sodium chloride, and potassium chloride with concentration.The solute-solute and solute-solvent interactions have been discussed on the basis of all physicochemical parameters.


2021 ◽  
Author(s):  
John W. Ostrander ◽  
Carolyn Torres ◽  
Fride Vullum-Breuer ◽  
Dale Teeters

Abstract Solid state batteries, particularly for lithium ion based architecture have been the focus of development for over 20 years and are receiving even more attention today. Utilizing impedance spectroscopy (IS) measurements we investigate the response of conductivity versus incremental pressure increase by a piston-cylinder-type high pressure cell up to 1 GPa for some lithium conducting ceramics: LATP (Li1.3Al0.3Ti1.7(PO4)3), LLTO (Li5La3Ta2O12), LLT (Li0.33La0.55TiO3), LAGP (Li1.5Al0.5Ge1.5P3O12) and LLZO (Li7La3Zr2O12) for non-annealed and annealed samples.Isothermal, incremental pressure increase of powders allows for an in situ observation of the transition state conditions of poorly consolidated ceramic powders and the effects on grain boundary conditions prior to sintering. Specific conductance (σb) increased by several orders of magnitude in some samples, approaching 10-3 S∙cm-1, yet decreased in other samples. The affect of grain boundaries and affects of bulk capacitance as the sample dimensions are altered due to pressure, are attributed to some of this behavior and will be discussed. The understanding of some of these fundamental processes may be valuable in facilitating these and similar ceramics for use in commercial solid state battery systems.


Sign in / Sign up

Export Citation Format

Share Document