Intrinsic Dependence of Groundwater Cation Hydraulic and Concentration Features on Negatively Charged Thin Composite Nanofiltration Membrane Rejection and Permeation Behavior

Commercial nanofiltration membranes of different molecular weight cut-offs were tested on a pilot plant for the exploration of permeation nature of Ca, Mg, Mn, Fe, Na and ammonium ions. Correlation of transmembrane pressure and rejection quotient versus volumetric flux efficiency on nanofiltration membrane rejection and permeability behavior toward hydrated divalent and monovalent ions separation from the natural groundwater was observed. Membrane ion rejection affinity (MIRA) dimension was established as normalized TMP with regard to permeate solute moiety representing pressure value necessary for solute rejection change of 1%. Ion rejection coefficient (IRC) was introduced to evaluate the membrane rejection capability, and to indicate the prevailed nanofiltration partitioning mechanism near the membrane surface. Positive values of the IRC indicated satisfactory rejection efficiency of the membrane process and its negative values ensigned very low rejection affinity and high permeability of the membranes for the individual solutes. The TMP quotient and the efficiency of rejection for individual cations showed upward and downward trends along with flux utilization increase. Nanofiltration process was observed as an equilibrium. The higher the Gibbs free energy was, cation rejection was more exothermic and valuably enlarged. Low Gibbs free energy values circumferentially closer to endothermic zone indicated expressed ions permeation.

Monovalent Copper Ions Inhibit Enzymatic Systems

The effect of monovalent copper ions on enzymatic systems has hardly been studied to date; this is due to the low stability of monovalent copper ions in aqueous solutions, which led to the assumption that their concentration is negligible in biological systems. However, in an anaerobic atmosphere, and in the presence of a ligand that stabilizes the monovalent copper ions over the divalent copper ions, high and stable concentrations of monovalent copper ions can be reached. Moreover, the cell cytoplasm has a substantial concentration of potential stabilizers that can explain significant concentrations of monovalent copper ions in the cytoplasm. This study demonstrates the effect of monovalent and divalent copper ions on DNA polymerase, ligaseT4 DNA, the restriction enzymes EcoP15I and EcoR I, acid phosphatase, and α and βamylase enzymes. These systems were chosen because they can be monitored under conditions necessary for maintaining a stable concentration of monovalent copper ions, and since they exhibit a wide range of dependency on ATP. Previous studies indicated that ATP interacts with monovalent and divalent copper ions and stabilizing monovalent copper ions over divalent copper ions. The results showed that monovalent copper ions dramatically inhibit DNA polymerase and acid phosphatase, inhibit ligaseT4 DNA and the restriction enzyme EcoP15I, moderately inhibit α and β amylase, and have no effect on the restriction enzyme EcoR I. From the results presented in this work, it can be concluded that the mechanism is not one of oxidative stress, even though monovalent copper ions generate reactive oxygen species (ROS). Molecular oxygen in the medium, which is supposed to increase the oxidative stress, impairs the inhibitory effect of monovalent and divalent copper ions, and the kinetics of the inhibition is not suitable for the ROS mechanism.ATP forms a complex with copper ions (di and monovalent ions, where the latter is more stable) in which the metal ion is bound both to the nitrogen base and to the oxygen charged on the phosphate groups, forming an unusually distorted complex. The results of this study indicate that these complexes have the ability to inhibit enzymatic systems that are dependent on ATP.This finding can provide an explanation for the strong antimicrobial activity of monovalent copper ions, suggesting that rapid and lethal metabolic damage is the main mechanism of monovalent copper ions’ antimicrobial effect.

Monovalent Ions and Stress-Induced Senescence in Human Mesenchymal Endometrial Stem Cells

Monovalent ions are involved in growth, proliferation, differentiation of cells as well as in their death. This work concerns the ion homeostasis during senescence induction in human mesenchymal endometrium stem cells (hMESC): hMESCs subjected to oxidative stress (pulse H2O2 treatment) enter the premature senescence accompanied by persistent DNA damage, irreversible cell cycle arrest, cell hypertrophy, lipofuscin accumulation, enhanced β-galactosidase activity. Using flame photometry to estimate K+, Na+ content and Rb+ (K+) fluxes we found that during the senescence development in stress-induced hMESCs, Na+/K+pump-mediated K+ fluxes are enhanced due to the increased Na+ content in senescent cells, while ouabain-resistant K+ fluxes remain unchanged. Senescence progression is accompanied by a peculiar decrease in the K+ content in cells from 800-900 µmol/g to 500-600 µmol/g. Since cardiac glycosides are offered as selective agents for eliminating senescent cells, we investigated the effect of ouabain on ion homeostasis and viability of hMESCs and found that in both proliferating and senescent hMESCs, ouabain (1 nM-1 µM, 24-48 h) inhibited pump-mediated K+ transport (ID50 5x10-8 M), decreased cell K+/Na+ ratio to 0,1-0,2, however did not induce apoptosis. Comparison of the effect of ouabain on hMESCs with the literature data on the selective cytotoxic effect of cardiac glycosides on senescent or cancer cells suggests the ion pump blockade and intracellular K+ depletion should be synergized with target apoptotic signal to induce the cell death.

2021 Edward G. Weston Fellowship - Summary Report: Layered Sodium Manganese Oxide as a Versatile Battery Cathode for Insertion of Monovalent Ions (Li+, Na+, and K+) in Non-aqueous Electrolytes

The transition from fossil fuels to carbon-free forms of renewable energy has become a spotlight with the revolutionary emergence of efficient electrochemical energy storage systems. It enables us to realize electric mobility empowered by Li-ion battery technology. Nevertheless, for the past three decades, the development of battery technology has been very sluggish, and it warrants new strategies to meet the growing demand for high energy density. In this spirit, we are working to develop versatile battery cathodes, which can be used for electrochemical and electrocatalytic applications.

Comparative Analysis of the Effects of Monovalent and Divalent Ions on Imported Biopolymer-Xanthan Gum and Locally Formulated Biopolymers-Gum Arabic and Terminalia Mantaly

Aim: Polymer flooding is used for enhanced oil recovery. Only polymers that can withstand harsh environments work best. HPAM is mostly the polymer used for enhanced oil recovery because it is available and cheap, but it does not withstand high temperatures and high salinity reservoirs. Xanthan Gum withstands high temperatures and high salinity reservoirs, but it is expensive and plugs the reservoir. The aim of this study is to compare the salinity stability of gum Arabic and Terminalia Mantaly, a novel biopolymer, with commercial Xanthan gum. Study Design: Locally formulated biopolymers from gum Arabic exudates bought from Bauchi State in Nigeria and from Terminalia Mantaly exudates obtained from the University of Port Harcourt. The appropriate rheological tests were carried out at the laboratory. Place and Duration of Study: The laboratory experiments were carried out at the department of Petroleum Engineering, Covenant University, Ota in Ogun State of Nigeria between 2020 and 2021. Methodology: The gum Arabic, Terminalia Mantaly and Xanthan Gum powders were dissolved in deionized water to get various concentrations in ppm. The polymers were mixed and kept for 24 hours to achieve a homogenous solution. The Automated OFITE® Viscometer at different revolutions per minute (RPM) of 3 (Gel), 6, 30, 60, 100, 200, 300, and 600 was used to measure the rheological properties of the various concentrations before Sodium Chloride (NaCl) and Calcium Chloride (CaCl2) of various concentrations were added and allowed to hydrate for another 24 hours before measuring their rheological properties again. Results: The study showed that Xanthan Gum, Gum Arabic, and Terminalia Mantaly biopolymers can be used in high salinity reservoirs. Terminalia Mantaly, a novel biopolymer, is insensitive to salinity in monovalent and divalent ions. Conclusion: Xanthan gum exhibited high viscosity even at low concentrations. Gum Arabic exhibited good tolerance to salinity at NaCl 3.5%. Terminalia Mantaly was very stable with both monovalent and divalent ions. Divalent ions have more effects on polymers than monovalent ions in reservoirs. Recommendation: It is recommended that Terminalia Mantaly be investigated more, as it can replace imported biopolymers for Enhanced Oil Recovery (EOR).

The Role of Sulphonic and Phosphoric Pendant Groups on the Diffusion of Monovalent Ions in Polyelectrolyte Membranes: A Molecular Dynamics Study

Lithium-ion consumption has risen significantly in recent years due to its use in portable devices. Alternative sources of lithium, which include the recovery from brine using the sustainable and eco-friendly electrodialysis technology, has been explored. This technology, however, requires effective cation-exchange membranes that allow the selective permeation of lithium ions. In this study, we have investigated, via molecular dynamics simulations, the role of the two common charged groups, the sulfonic and the phosphoric groups, in promoting the adsorption of monovalent ions from brine comprising Li+, Na+, Mg2+, and Ca2+ ions. The analysis of the mean square displacement of the ions revealed that Li+ and Na+ ions exhibit superior diffusion behaviors within the polyelectrolyte system. The O-atoms of the charged groups bind strongly with the divalent ions (Mg2+ and Ca2+), which raises their diffusion energy barrier and consequently lowers their rate of permeation. In contrast, the monovalent ions exhibit weaker interactions, with Na+ being slightly above Li+, enabling the permeation of Li+ ions. The present study demonstrates the role of both charged groups in cation-exchange membranes in promoting the diffusion of Li+ and Na+ ions, and could serve as a guide for the design of effective membranes for the recovery of these ions from brine.

Cation-Chloride Cotransporters, Na/K Pump, and Channels in Cell Water and Ion Regulation: In silico and Experimental Studies of the U937 Cells Under Stopping the Pump and During Regulatory Volume Decrease

Cation-coupled chloride cotransporters play a key role in generating the Cl– electrochemical gradient on the cell membrane, which is important for regulation of many cellular processes. However, a quantitative analysis of the interplay between numerous membrane transporters and channels in maintaining cell ionic homeostasis is still undeveloped. Here, we demonstrate a recently developed approach on how to predict cell ionic homeostasis dynamics when stopping the sodium pump in human lymphoid cells U937. The results demonstrate the reliability of the approach and provide the first quantitative description of unidirectional monovalent ion fluxes through the plasma membrane of an animal cell, considering all the main types of cation-coupled chloride cotransporters operating in a system with the sodium pump and electroconductive K+, Na+, and Cl– channels. The same approach was used to study ionic and water balance changes associated with regulatory volume decrease (RVD), a well-known cellular response underlying the adaptation of animal cells to a hypoosmolar environment. A computational analysis of cell as an electrochemical system demonstrates that RVD may happen without any changes in the properties of membrane transporters and channels due to time-dependent changes in electrochemical ion gradients. The proposed approach is applicable when studying truly active regulatory processes mediated by the intracellular signaling network. The developed software can be useful for calculation of the balance of the unidirectional fluxes of monovalent ions across the cell membrane of various cells under various conditions.

Role of cation-chloride cotransporters, Na/K-pump, and channels in cell water/ionic balance regulation under hyperosmolar conditions: in silico and experimental studies of opposite RVI and AVD responses of U937 cells to hyperosmolar media

The work provides a modern mathematical description of animal cell electrochemical system under a balanced state and during the transition caused by an increase in external osmolarity, considering all the main ionic pathways in the cell membrane: the sodium pump, K+, Na+, Cl- electroconductive channels and cotransporters NC, KC, and NKCC. The description is applied to experimental data obtained on U937 cells cultured in suspension, which allows the required assays to be performed, including determination of cell water content using buoyant density, cell ion content using flame photometry, and optical methods using flow cytometry. The study of these cells can serve as a useful model for understanding the general mechanisms of regulation of cellular water and ionic balance, which cannot be properly analyzed in many important practical cases, such as ischemic disturbance of cellular ionic and water balance, when cells cannot be isolated. An essential part of the results is the developed software supplied with an executable file, which allows researchers with no programming experience to calculate unidirectional fluxes of monovalent ions through separate pathways and ion-electrochemical gradients that move ions through them, which is important for studying the functional expression of channels and transporters. It is shown how the developed approach is used to reveal changes in channels and transporters underlying the RVI and AVD responses to the hyperosmolar medium in the studied living U937 cells.

Adsorption and Release Characteristics of Purified and Non-Purified Clinoptilolite Tuffs towards Health-Relevant Heavy Metals

The occurrence of health-relevant contaminants in water has become a severe global problem. For treating heavy-metal-polluted water, the use of zeolite materials has been extended over the last decades, due to their excellent features of high ion exchange capacity and absorbency. The aim of this study was to assess the effect of heavy metal uptake of one purified (PCT) and two non-purified clinoptilolite tuffs (NPCT1 and NPCT2) in aqueous solutions on monovalent ions Ni+, Cd+, Cs+, Ba+, Tl+, and Pb+. Experiments were furthermore carried out in artificial gastric and intestinal fluids to mimic human digestion and compare removal efficiencies of the adsorbent materials as well as release characteristics in synthetic gastric (SGF) and intestinal fluids (SIF). Batch experiments show low sorption capacities for Ni+ and Cd+ for all studied materials; highest affinities were found for Ba+ (99–100%), Pb+ (98–100%), Cs+ (97–98%), and Tl+ (96%), depending on the experimental setup for the PCT. For the adsorption experiments with SGF, highest adsorption was observed for the PCT for Pb+, with an uptake of 99% of the lead content. During artificial digestion, it was proven that the PCT did not release Ba+ cations into solution, whereas 13574 ng·g−1 and 4839 ng·g−1 of Ba+ were measured in the solutions with NPCT1 and NPCT2, respectively. It was demonstrated that the purified clinoptilolite tuff is most effective in remediating heavy-metal-polluted water, particularly during artificial digestion (99% of Pb+, 95% of Tl+, 93% of Ba+). In addition, it was shown that the released amount of bound heavy metal ions (e.g., barium) from the non-purified clinoptilolite tuffs into the intestinal fluids was significantly higher compared to the purified product.