Ion Concentration Ratio Research Articles

Ion Concentrations and Their Spatial Variability in Underground Water and Surface Water in Typical Terrestrial Ecosystems in China

The water chemistry data monitored during 2010-2015 by 33 terrestrial ecological stations from the Chinese Ecosystem Research Network (CERN) and the National Ecosystem Research Network of China (CNERN) were used to characterize ion concentrations and their spatial variability in underground water, still surface water, and flowing surface water from typical terrestrial ecosystems. The results showed the presence of mass-based concentrations of major anions, including HCO3- > SO42- > Cl- > CO32-. Among them, HCO3- and SO42- were dominant, and their sums accounted for 71.7%, 75.3%, and 74.9% of the total anions in underground water, still surface water, and flowing surface water, respectively. Cations were mainly Ca2+ and Na+, and their sums accounted for 69.7%, 64.8%, and 68.9% of the total cations in underground water, still surface water, and flowing surface water, respectively. The ion concentration and ion ratio in the underground water, still surface water, and flowing surface water differed largely among the studied regions. The hydrochemical type varied regionally, e.g., Na-Mg-SO4-Cl type, usually with high content of salinity, was found in the underground water of ecological systems in the Northwest arid and semiarid areas and in the East Huanghuaihai Plain; Ca-SO4-HCO3 type in underground water and Ca-HCO3-SO4 type in surface water were found in hilly areas with subtropical red soil; Na-Ca-HCO3-Cl type was present in underground water of south hilly areas with subtropical latosolic red soil; and Ca-HCO3 and Ca-Mg-HCO3 types were found in other ecological systems. Hydrochemical types had low inter-annual variation for both underground water and surface water.

Mechanism of Selective Ion Removal in Membrane Capacitive Deionization for Water Softening.

Capacitive deionization (CDI) is an emerging technology capable of selective removal of ions from water. While many studies have reported chemically tailored electrodes for selective ion removal, the selective removal of divalent cations (i.e., hardness) over monovalent cations can simply be achieved using membrane CDI (MCDI) equipped with ion exchange membranes (IEMs). In this study, we use both experimental and modeling approaches to systematically investigate the selective removal of Ca2+ over Na+. Specifically, the impacts of current density, hydraulic retention time, and feed composition on the selectivity of Ca2+ over Na+ were investigated. The results from our study suggest a universal correlation between the ratio of molar fluxes and the ratio of spacer channel ion concentrations, regardless of operating conditions and feed composition. Our analysis also reveals inherent and universal trade-off relationships between selectivity and the Ca2+ removal rate and between selectivity and the degree of Ca2+ removal. This fundamental understanding of the mechanism of selective ion removal in MCDI can also be applied to flow-electrode CDI processes that employ IEMs.

Secular variations in the carbonate chemistry of the oceans over the Cenozoic

Oceanic carbonate chemistry during the Cenozoic has affected the climatology, ecology, and marine geology of our planet; yet, we have limited means to know the evolution of that chemistry, due to a lack of preserved and unaltered seawater samples and a continuing paucity of proxies. Modeling is often used to address this problem; here, we offer a simple, data-driven, secular timescale, inverse model for the mean, Cenozoic, carbonate chemistry of the oceans. Inputs for the model include carbonate compensation depth (CCD), CaCO3 burial, seawater temperature, atmospheric CO2 and carbonate ion records, as well as a simple set of original, but justified, assumptions. The model retrodicts the total dissolved inorganic carbon (DIC), carbonate alkalinity (CAlk), and pH of the surface and deep waters of the ocean. The retrodicted DIC and CAlk records do not indicate any unusually elevated values in the early Cenozoic, as found in some past studies. If the CCD record from Lyle et al. (2008) is employed, the changes in DIC and CAlk appear entirely related to changes in the alkalinity input to the pelagic oceans and atmospheric CO2; however, with the CCD from Pälike et al. (2012), the increases in DIC and CAlk during the last 15 Ma reflect the effects of ocean cooling. Using either CCD-record, our model provides consistent retrodictions of the available pH record. Our results are not consistent with many past modeling assumptions, such as constancy of alkalinity in surface waters, or the ratio of shallow and deep carbonate ion concentrations. Finally, we use our results to provide new estimates of atmospheric CO2 based on Boron isotopes and find significantly lower CO2 values in the early Cenozoic than previous values.

Structure and Giant Magnetoresistance of Co-Fe/Cu Multilayer Films Electrodeposited from Various Bath Formulations

Detailed new results are reported on the preparation and giant magnetoresistance (GMR) of electrodeposited Co-Fe/Cu multilayer films by using four different baths (sulfamate, sulfate, ammonium chloride and sodium citrate type solutions). Two-pulse plating was applied for Co-Fe(5nm)/Cu(5nm) multilayer preparation by using galvanostatic pulses for the deposition of the magnetic layer. The Cu layer deposition potential was electrochemically optimized for each bath formulation by analyzing the current transients during the deposition of the non-magnetic layers. The optimal Cu deposition potential was found to be dependent both on the bath formulation and the Fe2+/Co2+ ion concentration ratio. The results of X-ray diffraction (XRD) measurements were in agreement with the composition of the samples. At low Fe content (about 10 at.% Fe) in the magnetic layer, an fcc structure was formed (in some cases, even multilayer satellites were observed). In samples with high Fe content (about 33 at.% Fe) in the magnetic layer, both fcc and bcc phases were present. A GMR behavior was observed for all multilayers, with a maximum GMR of about 4% in some cases. For multilayers from the sulfamate, sulfate and chloride baths, the GMR exhibited a multilayer-type behavior whereas the GMR of samples from the citrate bath was rather similar to the behavior of granular magnetic alloys containing also superparamagnetic regions.

Carbon quantum dot-sensitized and tunable luminescence of Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors with abundant colors via a sol–gel process

Efficient carbon quantum dot-sensitized luminescence of Ca19Mg2(PO4)14:Ln3+ (Ln3+ = Eu3+ and/or Tb3+) nanocrystalline phosphors with abundant colors.

Chemical Characteristics of Size-Resolved Aerosols in Coastal Areas during KORUS-AQ Campaign; Comparison of Ion Neutralization Model

Measurements for size-resolved chemical composition were made at the Anmyeon Island station on the western coast of the Republic of Korea between May 28 and June 20, 2016. This study determined the main chemical compositions of size-resolved particulate matter (i.e., organic carbon, elemental carbon, water-soluble organic carbon, water-soluble ions, and benzene carboxylic acids) from a total of eight chemically size-resolved sets using micro-orifice uniform deposit impactors. The sum of the species presents a prominent accumulation mode peak at a diameter of 0.56 μm without the coarse mode peak. In the accumulation mode, SO42− (49.3%) was the dominant particle component in the size range of 0.1–1.8 μm. Organic carbon and elemental carbon accounted for 13.5% and 0.4%, respectively. Benzene carboxylic acids indicate the accumulation mode peak at the diameter of 0.56 μm. The size-resolved equivalent ion concentration ratios between all measured cations and anions and the ion neutralization model, which uses four major ions, were compared. As a result, the concentration of Na+ is of importance in the accumulation mode for the equivalent ion concentration.

Effects of dielectric decrement on surface potential in a mixed electrolyte solution**Project supported by the National Natural Science Foundation of China (Grant Nos. 41501240, 41530855, 41501241, and 41877026), the Natural Science Foundation of Chongqing CSTC (Grant No. cstc2018jcyjAX0318), and the Fundamental Research Funds for the Central Universities, China (Grant No. XDJK2017B029).

Surface potential is an important parameter related to the physical and chemical properties of charged particles. A simple analytical model for the estimation of surface potential is established based on the Poisson–Boltzmann theory with the consideration of the dielectric decrement in mixed electrolyte. The analytical relationships between surface potential and charge density are derived in different mixed electrolytes with monovalent and bivalent ions. The dielectric decrease on the charged surface strongly affects the surface potential at a high charge density with different ion strengths and concentration ratios of counter-ions. The surface potential based on the Gouy–Chapman model is underestimated because of the dielectric decrement on the surface. The diffuse layer can be regarded as a continuous uniform medium only when the surface charge density is lower than 0.3 C·m−2. However, the surface charge densities of many materials in practical applications are higher than 0.3 C·m−2. The new model for the estimation of surface potential can return to the results obtained based on the Gouy–Chapman model at a low charge density. Therefore, it is implied that the established model that considers the dielectric decrement is valid and widely applicable.

Anthropogenic Transformation of Kyzyl-Yar Lake in Crimea: Multiyear Research Findings

Most of the hypersaline lakes located in the arid part of the Crimea have been undergoing anthropogenic transformations. We concentrate on the impact of the established water storage reservoir on the marine Kyzyl-Yar Lake (Western Crimea) over the period from 1985 to 2017. As a result of water seepage from the reservoir, the lake salinity decreased from 162 g/L in 1985 to 2–3 g/L in 2005 and subsequently remained steady at this level. Over 20 years, the lake changed from a hypersaline to freshwater lake. The accompanying changes included an altered ratio of ion concentrations in the water column and interstitial waters and increased Ca2+/Na+ and $${{{\text{SO}}_{4}^{{2 - }}} \mathord{\left/ {\vphantom {{{\text{SO}}_{4}^{{2 - }}} {{\text{C}}{{{\text{l}}}^{ - }}}}} \right. \kern-0em} {{\text{C}}{{{\text{l}}}^{ - }}}}$$ indicators. Substantial shifts occurred in the structure of the biological diversity and conditions of the bottom deposits, such as the disappearance of branchipoda crustaceans of the genus Artemia, which had been practically the only representative of the local fauna before, and the dominance of new species Cladocera and Cyclopoida in plankton.

Salt Partitioning in Complex Coacervation of Symmetric Polyelectrolytes

We perform a general thermodynamic analysis for the salt partitioning behavior in the coexisting phases for symmetric mixtures of polycation and polyanion solutions. We find that salt partitioning is determined by the competition between two factors involving the ratio of the polyelectrolyte concentration in the coacervate phase to that in the supernatant phase and the difference in the exchange excess chemical potential Δμex—the excess chemical potential difference between PE segments and small ions—between the coexisting phases. The enrichment of salt ions in the coacervate phase predicted by the Voorn–Overbeek theory is shown to arise from its neglect of chain connectivity in the excess free energy which results in Δμex = 0 under all conditions. We argue that chain connectivity in general leads to a finite value of Δμex, which decreases with increasing PE concentration. Explicit calculations using theories that include the chain connectivity correlations—a simple liquid-state theory and a renormalized Gaussian fluctuation theory—show nonmonotonic behavior of the salt-partitioning coefficient (the ratio of salt ion concentration in the coacervate phase to that in the supernatant phase): it is larger than 1 at very low salt concentrations, reaches a minimum at some intermediate salt concentration, and approaches 1 at the critical point. This behavior is consistent with recent computer simulation and experimental results.

Electronegative (3+1)-dimensional modulated excitations in plasmas

A three-dimensional electronegative plasma model is studied. Modulated ion-acoustic waves are investigated via the activation of modulational instability in the Davey-Stewartson equations, with three space variables. The contributions of the modulation angle (θ) and electronegative plasma parameters are discussed to that effect, including some particular cases such as the parallel and transverse modulations. The parametric linear stability analysis that is proposed shows that the growth rate of instability displays opposite regions of instability for parallel and transverse modulations when the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn) change.

Enhancement of selective Cu(II) sorption through preparation of surface-imprinted mesoporous silica SBA-15 under high molar concentration ratios of chloride and copper ions

We synthesized and characterized surface-imprinted poly (ethyleneimine) (PEI)-grafted mesoporous silica SBA-15 (Cu-imprinted PEI-SBA-15) for selective Cu(II) sorption from aqueous solutions. To enhance the Cu(II) selectivity of Cu-imprinted PEI-SBA-15, Cu(II) loading on PEI-SBA-15 was increased via Cu(II) sorption under high-molar-concentration ratios of chloride (Cl) and Cu(II) ions. Then, selective Cu(II) sorption sites were increased through imprinting processes (crosslinking and elution) on Cu-loaded PEI-SBA-15. Selective experiments were performed using Cu-imprinted PEI-SBA-15 prepared at various [Cl−]/[Cu(II)] ratios, ranging from 2 to 1000. In multinary solutions containing divalent ions, such as Cu(II), Pb(II), Zn(II), Ni(II), and Co(II), Cu(II) selectivity was highest (79.62) at a [Cl−]/[Cu(II)] ratio of 500; the relative Cu(II) selectivity for Cu-imprinted PEI-SBA-15 over PEI-SBA-15 was 29.24. In multinary solutions containing Cu(II) along with trivalent and tetravalent ions, such as Al(III), Cr(III), and Zr(IV), the Cu(II) selectivity was also highest (3.40) at a ratio of 500; the relative Cu(II) selectivity was 3.96. In this study, we demonstrated that the Cu(II) selectivity of surface-imprinted SBA-15 could be enhanced through its preparation under high [Cl−]/[Cu(II)] ratios.

Modulation of membrane potential and ion concentration of isolate ellipsoidal cell exposed to static electric field

Based on the model setting is carried out to describe the interaction between static electric field and cell and the calculation of the transmembrane potential, and the Nernst formula and the Boltzmann formula, the method which to analyze the influence of the static field on the quantity across ellipsoid-cell membrane is investigated by using the theorem of electromagnetic induction. Furthermore, numerical studies were used to detect and verify the transition of ion exchange across the membrane. Some interesting results are approached as follows. The exchange of ions across the membrane and fluctuation of membrane potential are dependent on the position, orientation of electric field applied on the membrane of cell and the cell-shape. With the increasing of the field angle (between the direction of applied field and the direction of ellipsoid semi-major axis) and the semi-axis ratio ρ , it is found that the maximal ratio of ion concentration on the side of the ellipsoid-cell will reduce when external field is applied on the cell membrane, and its positions θ max will increase. Under a certain cell superficial area or volume, θ max is increased as ρ goes up. The larger field intensity for the electrostatic field with the noise, the smaller signal to noise ratio, as a result, the rate of relative change of the ion concentration will increase. The mechanism for transition in transmembrane ions could be that media or cell can be polarized when appropriate electric field is applied on ellipsoid cell even noise is considered.

Biogenic synthesis of shape-tunable Au-Pd alloy nanoparticles with enhanced catalytic activities

Herein, we report the synthesis of bimetallic Au-Pd and monometallic Au and Pd nanoparticles (NPs) by successive reduction of the respective metal ions using phytochemicals in the form of plant extract under ambient conditions. Phytochemicals act both as reducing and shape directing agent for metal and alloy NPs. The synthesized nanostructures were characterized by different microscopic, spectroscopic and diffractometric techniques. Microscopic results confirmed that the shape and size of the alloy nanostructures can be tuned by varying the concentration ratio of metal ions in the reaction medium. Energy dispersive X-ray and X-ray photoelectron spectroscopic analysis confirmed the formation of bimetallic Au-Pd nanostructures. The purity and crystalline properties were studied by X-ray diffraction technique. UV–vis spectra were recorded to study the optical properties of the synthesized nanostructures. Further, we tested the catalytic activity of both the monometallic and bimetallic alloy nanostructures in borohydride reduction of hazardous organic dye molecules in aqueous medium. The bimetallic alloy NPs exhibit better catalytic activities compared to their respective monometallic nanoparticles.

Large amplitude ion-acoustic solitons in warm negative ion plasmas with superthermal electrons

Large amplitude ion-acoustic solitons are investigated in a plasma consisting of warm adiabatic positive and negative-ions and hot superthermal electrons having kappa distributions. Using Pseudo-potential method an energy integral equation is derived for the system. The latter is analysed to examine the existence regions of the solitary waves. It is found that negative ion concentration (α), spectral index (k) and ionic temperature ratio (σ1 or σ2) significantly influence the characteristic of the solitons. Our numerical analysis shows that the system also supports rarefactive solitons for some selected set of plasma parameters. It is also found that large amplitude ion-acoustic compressive and rarefactive solitons exist simultaneously for the same values of plasma parameters. Further an increase in the superthermality (i.e. decreasing the value of spectral index k) leads to shrinking the existing domain of the large amplitude ion-acoustic solitons. The amplitude of the compressive/rarefactive solitons increases with the increase in negative ion concentration (α). Whereas, on increasing ionic temperature ratio (σ1 or σ2) the amplitude of the compressive/rarefactive soliton decreases. The effect of negative-ion concentration (α), temperature ratio of two ion species (σ1 and σ2), Mach number (M) and spectral index (k) on the characteristics of solitons are discussed in detail. The results of the present investigation may be helpful to understand the nonlinear ion-acoustic solitary waves in space plasma and laboratory plasmas, where two distinct groups of ions and non-Boltzmann distribution electrons are present.

Two-dimensional modulated ion-acoustic excitations in electronegative plasmas

Two-dimensional modulated ion-acoustic waves are investigated in an electronegative plasma. Through the reductive perturbation expansion, the governing hydrodynamic equations are reduced to a Davey-Stewartson system with two-space variables. The latter is used to study the modulational instability of ion-acoustic waves along with the effect of plasma parameters, namely, the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). A parametric analysis of modulational instability is carried out, where regions of plasma parameters responsible for the emergence of modulated ion-acoustic waves are discussed, with emphasis on the behavior of the instability growth rate. Numerically, using perturbed plane waves as initial conditions, parameters from the instability regions give rise to series of dromion solitons under the activation of modulational instability. The sensitivity of the numerical solutions to plasma parameters is discussed. Some exact solutions in the form one-...

Selective separation and extraction of copper(II), iron(II, III), and Cerium(III, IV) ions from aqueous solutions by electroflotation method

Possibility of the electroflotation separation and extraction of cerium(II, IV), copper(II), and iron(II, III) from aqueous solutions is demonstrated. The optimal pH value and the concentration ratio of ions of the metals being separated, at which their electroflotation separation and extraction from aqueous solutions is the most efficient, was determined. It was shown that the electroflotation method is promising for selective separation and extraction of metal ions with various hydrate-formation pH values from aqueous solutions.

Electronegative nonlinear oscillating modes in plasmas

The emergence of nonlinear modulated waves is addressed in an unmagnetized electronegative plasma made of Boltzmann electrons, Boltzmann negative ions and cold mobile positive ions. The reductive perturbation method is used to reduce the dynamics of the whole system to a cubic nonlinear Schrödinger equation, whose the nonlinear and dispersion coefficients, P and Q, are function of the negative ion parameters, namely the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). It is observed that these parameters importantly affect the formation of modulated ion-acoustic waves, either as exact solutions or via the activation of modulational instability. Especially, the theory of modulational instability is used to show the correlation between the parametric analysis and the formation of modulated solitons, obtained here as bright envelopes and kink-wave solitons.

H and O isotopic differences in typhon and urban-induced heavy rain in Tokyo

Stable isotope ratios of hydrogen and oxygen of water are useful tracers of the hydrological cycle. For example, isotopes monitor the evapotranspiration in vegetated areas, local snow ice processes and stream water flow processes. δ18O and δD in rainwater reflect the processes of evaporation, condensation and precipitation. Heavy rains thus modify the stable isotope ratio of ground water, stream water and transpiration water vapor. However, the controlling factors of δ18O and δD are not clear. Here we analyzed the inorganic ion concentration and stable isotope ratio in 38 normal rainwater and 15 heavy rainwater samples were collected in Shinjuku, Tokyo, Japan, during four years from October 2012 to December 2015. Results show a decrease in δ18O and δD values with the total rainfall amount, thus highlighting the amount effect. δ18O and δD volume-weighted mean values in typhoon heavy rain were higher than the values estimated from amount effect, whereas δ18O and δD volume-weighted mean values in urban-induced heavy rain were lower. Typhoon heavy rain has high Na+ ratio and stable isotope ratios, while urban-induced heavy rain has low Na+ ratio and stable isotope ratio.

The critical role of logarithmic transformation in Nernstian equilibrium potential calculations.

The membrane potential, arising from uneven distribution of ions across cell membranes containing selectively permeable ion channels, is of fundamental importance to cell signaling. The necessity of maintaining the membrane potential may be appreciated by expressing Ohm's law as current = voltage/resistance and recognizing that no current flows when voltage = 0, i.e., transmembrane voltage gradients, created by uneven transmembrane ion concentrations, are an absolute requirement for the generation of currents that precipitate the action and synaptic potentials that consume >80% of the brain's energy budget and underlie the electrical activity that defines brain function. The concept of the equilibrium potential is vital to understanding the origins of the membrane potential. The equilibrium potential defines a potential at which there is no net transmembrane ion flux, where the work created by the concentration gradient is balanced by the transmembrane voltage difference, and derives from a relationship describing the work done by the diffusion of ions down a concentration gradient. The Nernst equation predicts the equilibrium potential and, as such, is fundamental to understanding the interplay between transmembrane ion concentrations and equilibrium potentials. Logarithmic transformation of the ratio of internal and external ion concentrations lies at the heart of the Nernst equation, but most undergraduate neuroscience students have little understanding of the logarithmic function. To compound this, no current undergraduate neuroscience textbooks describe the effect of logarithmic transformation in appreciable detail, leaving the majority of students with little insight into how ion concentrations determine, or how ion perturbations alter, the membrane potential.

Influence of electrical double-layer dispersion forces and size dependency on pull-in instability of clamped microplate immersed in ionic liquid electrolytes

Plate-type clamped microplate is of the most common constructive elements for developing in-liquid-operating devices. While the electromechanical behavior of clamped microplate in non-liquid environments has exclusively been addressed in the literature, no theoretical studies have yet been conducted on precise modeling of the clamped microplate in electrolyte liquid. Herein, the electromechanical response and instability of the clamped microplate immersed in ionic electrolyte media are investigated. The electrochemical force field is determined using double layer theory and linearized Poisson–Boltzmann equation. The presence of dispersion forces, i.e., Casimir and van der Waals attractions, are included in the theoretical model considering the correction due to the presence of liquid media between the interacting surfaces (three-layer model). To this end, a kind of microplate has been designed, i.e., a square microplate with all edges clamped supported. The strain gradient elasticity is employed to model the size-dependent structural behavior of the clamped microplate. To solve the nonlinear constitutive equation of the system, Extended Kantorovich Method, is employed and the pull-in parameter of the microplate are extracted. Impacts of the dispersion forces and size effect on the instability characteristics are discussed as well as the effect of ion concentration and potential ratio. It is found that the significant difference between the pull-in instability parameters in the modified strain gradient theory and the classical theory for thin microplates is merely due to the consideration of size effect parameter in the modified strain gradient theory. To confirm the validity of formulations, the numerical values of the results are compared. The results predicted via the aforementioned approach are in excellent agreement with those in the literature. Some new examples are solved to demonstrate the applicability of the procedure.