Exchange Of Chloride Ions Research Articles

Effects of C479W Mutation on the Structure and Function of Band 3 Protein

Band 3, or anion exchanger 1 (AE1), is one of the indispensable transmembrane proteins involved in effective respiratory processes in the human body, mainly responsible for the exchange of bicarbonate and chloride ions on the plasma membrane of red blood cells. However, the effect of related gene mutations on Band 3 ion transport is not fully understood. In this work, we used all-atom molecular dynamics (MD) simulations to systematically investigate the effects of the mutation from cysteine (C) to tryptophan (W) at site 479 in Band 3 on the structure of Band 3 and its interaction with anions. We studied the kinetics of wild-type (WT) and mutant Band 3 interactions with bicarbonate and chloride ions on the microsecond scale. The results showed that the mutation at site 479 affected the stability of Band 3 structure and the distribution of anions, and changed the affinity of anions to different parts of Band 3. These findings provide some insights into the structural and functional effects of gene mutations in Band 3 and contribute to understanding Band 3 anion exchange.

A novel LDHs-VB3- inhibitor for rebar corrosion in simulated concrete pore solution: Synthesis, performance and mechanism

Developing novel chloride-trapping inhibitors is of great significance for enhancing the durability of marine concrete structures. In this study, a novel LDHs-VB3- inhibitor was synthesized through the ion exchange method. Then, the corrosion inhibition mechanism of LDHs-VB3- inhibitor for rebar in the whole process of release - capture - adsorption - retardation was studied using experiments and density functional theory (DFT) simulations. The chloride ion exchange test demonstrates that the LDHs-VB3- inhibitor has a chloride trapping capacity of 35.5 mg/g in the saturated Ca(OH)2 solution containing 0.14 M NaCl, implying that it could capture Cl- in concrete pore solution. According to the electrochemical tests, the critical chloride concentration of rebar in the simulated concrete solution containing LDHs-VB3- falls within a range of 0.22 M–0.28 M, which is much higher than that in the solution without LDHs-VB3- (0.10 M–0.14 M). DFT simulations indicate that LDHs-VB3- exhibits more positive binding energy and uneven binding forces in contrast to LDHs-Cl-. Consequently, VB3- could be easily replaced by Cl- and then released into the pore solution of concrete. Moreover, the released VB3- could adsorb on the α-Fe2O3 surface in a concrete environment via the interaction of surface Fe atoms with N and O atoms of VB3-. The preadsorbed VB3- could diminish the interaction of Cl- with the α-Fe2O3 surface by reducing electron transfer, thereby mitigating the risk of passive film breakdown and retarding the chloride-induced corrosion of rebars.

Investigating Disease‐Causing Mutations in SLC4 Transporter Homologs

The SLC4 family of transporters includes the archetypal transporter Band 3, or Anion Exchanger 1 (AE1), a bicarbonate and chloride ion exchanger essential for human respiration and the most abundant membrane protein in red blood cells. Mutations in SLC4 transporters such as AE1 can lead to diseases such as hereditary spherocytosis or renal tubular acidosis. The SLC4 family shares sequence and structural homology with borate transporters, which are found in plants and fungi and regulate cellular borate levels to protect against borate toxicity. Here we generated mutations in the S. cerevisiae borate transporter Bor1 homologous with known disease‐causing mutations of human AE1, and then tested for borate transport activity in a genetic complementation assay. Our results identify mutants with impaired function but wild‐type expression levels, as well as mutants with impaired function and depleted expression levels. These results are consistent with varying modes of deleterious impact of protein expression, sorting, and function that have been attributed to mutations in human AE1. These data show that mutations equivalent to disease‐causing mutations in human AE1 have major effects in ScBor1, strengthening the functional connection between SLC4 proteins and borate transporters. Additionally, we demonstrate that the ScBor1 D347 residue, which is homologous to the essential E681 of human AE1, can be complemented by the D347E but not D347N substitution, underscoring the necessity of having an acidic residue at this highly conserved functional location. Lastly, we identify several new amino acids critical for function through mutagenesis and complementation studies. These data collectively highlight similarities in the biochemical features of ScBor1 and HsAE1 and help shed light on the mechanisms of borate transporters and their SLC4 homologs.

Fluorescence Quenching of Graphene Quantum Dots by Chloride Ions: A Potential Optical Biosensor for Cystic Fibrosis

Cystic fibrosis is a genetic disorder caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes an ABC transporter-class ion channel protein, resulting in sticky and thick mucus secretion which clogs the airways and leads to respiratory failure and other complications. It also results in higher chloride ions (Clˉ) in body fluids. Cystic fibrosis is generally detected using the sweat chloride test and ion exchange chromatography, which are lab restricted. Therefore, there is a dire need to develop portable assays to monitor circulatory changes (Clˉ ion detection) to detect CF at the point of care. In this work, fluorescence quenching of graphene quantum dots (GQDs) was used as a property of the optical sensor for chloride ion detection. GQDs were synthesized by varying the carbonizing temperature and time, and then their optical and fluorescence (FL) quenching was investigated upon exposure to chloride ions in comparison with different ionic species. GQDs synthesized at 160°C for 50 min were chosen as they displayed the highest fluorescence. The morphological and optical characterization confirmed the preparation of 12–15 nm GQDs, which were amorphous in nature with the peak emission observed at 462 nm when excited at 370 nm. The fluorescence quenching response of GQDs with Clˉ ions displayed linearity up to 100 mM with a correlation coefficient of 0.98 and the lowest detection limit of approximately 10 mM Clˉ ions.

Pediococcus acidilactici Promotes the Longevity of C. elegans by Regulating the Insulin/IGF-1 and JNK/MAPK Signaling, Fat Accumulation and Chloride Ion.

Probiotics are known to contribute to the anti-oxidation, immunoregulation, and aging delay. Here, we investigated the extension of lifespan by fermented pickles-origin Pediococcus acidilactici (PA) in Caenorhabditis elegans (C. elegans), and found that PA promoted a significantly extended longevity of wild-type C. elegans. The further results revealed that PA regulated the longevity via promoting the insulin/IGF-1 signaling, JNK/MAPK signaling but not TOR signaling in C. elegans, and that PA reduced the reactive oxygen species (ROS) levels and modulated expression of genes involved in fatty acids uptake and lipolysis, thus reducing the fat accumulation in C. elegans. Moreover, this study identified the nrfl-1 as the key regulator of the PA-mediated longevity, and the nrfl-1/daf-18 signaling might be activated. Further, we highlighted the roles of one chloride ion exchanger gene sulp-6 in the survival of C. elegans and other two chloride ion channel genes clh-1 and clh-4 in the prolonged lifespan by PA-feeding through the modulating expression of genes involved in inflammation. Therefore, these findings reveal the detailed and novel molecular mechanisms on the longevity of C. elegans promoted by PA.

Preparation of well-structured hybrid material through ion exchange of chloride by 2,4,5-trichlorophenoxyacetic herbicide in a layered double hydroxide

The [Zn2–Al–Cl] layered double hydroxide (LDH) was used to successfully exchange chloride ions by 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), as a model of the carboxylate herbicide family. The total exchange was obtained after 6 h of stirring with a 2,4,5-T/Cl molar ratio of 10 and a pH of 7. The characterization by various techniques (XRD, FTIR, TG-DTG and SEM) indicates that this exchange led to the production of a new stable hybrid LDH phase intercalated by the herbicide. The structural analysis of the material, based on the interlayer distance of 1.855 nm, indicates that the 2,4,5-T anion takes a vertical arrangement in a double layer. The cohesion of the structure is ensured by hydrogen bonds between the carboxylate group of the herbicide and the hydroxyl groups of the LDH sheets. The exchange causes a modification of the type of symmetry from a 3R stacking mode for [Zn2–Al–Cl] (space group R3‾m) to a 2H for [Zn2–Al-2,4,5-T] (space group P63/mmc). This result confirms the already proven use of LDH materials as efficient anion exchangers for the trapping and elimination of this type of pollutant from wastewater.

Synthesis of imidazolium-based poly(ionic liquid)s and their application to ion-exchange materials

Linear and networked poly(ionic liquid)s, which were composed of polyoxetanes and imidazolium groups, were synthesized by cationic polymerization of mono- and di- functional oxetanyl monomers, and the properties of the obtained polymers were investigated. The monofunctional monomer, 3-(3-ethyl-3-oxetanylmethyl)-1,2-dimethylimidazolium bis(trifluoromethanesulfonyl)imide (OXDMImTFSI), was prepared from the reaction of 3-ethyl-3-oxetanylmethyl chloride with 1,2-dimethylimidazole followed by exchanging the chloride to bis(trifluonomethanesulfonyl)imide (TFSI). The difunctional monomer, 1,3-di(3-ethyl-3-oxetanylmethyl)-2-methylimidazolium bis(trifluoromethanesulfonyl)imide (DOXMImTFSI), was prepared from the reaction of 3-ethyl-3-oxetanylmethyl chloride with 2-methylimidazole and successive ion-exchange of chloride to TFSI. OXDMImTFSI was polymerized by addition of a catalytic amount of BF3 diethyl ether complex. The obtained linear polyOXDMImTFSI showed good stability toward heat and basic conditions. Networked polymer films were prepared by homo/co-polymerization of DOXMImTFSI or DOXMImTFSI/OXDMImTFSI liquid layers using the thermally latent cationic initiator, (1-naphthylmethyl) methyl p-hydroxyphenyl sulfonium hexafluoroantimonate (SI-60). The obtained films showed good ion-exchange ability between TFSI, Cl, and OH anions.

Adsorption of perchlorate from water using quaternary ammonium‐functionalized chitosan beads

AbstractPerchlorate, one of the persistent inorganic pollutants, was efficiently removed from water using quaternary ammonium‐functionalized cross‐linked chitosan beads (QACB). This synthesized bead was found to be efficient in terms of perchlorate removal capacity, 100% regeneration of used beads (using HCl or NaCl) and selectivity in the presence of coanions, namely, chloride, sulfate, carbonate, and nitrate. QACB removes perchlorate by exchange of chloride ions. QACB was able to remove >95% perchlorate from brackish water. Batch studies were carried out in order to optimize the condition for maximum perchlorate removal. The perchlorate removal capacity of QACB from 1,000 mg/L of aqueous solutions was 153.0 mg/g. The outcome of pH variation studies indicated that QACB is able to remove perchlorate in the pH ranges of 2–11. Equilibrium isotherm data of adsorption of perchlorate at temperature 303, 313, and 323 K were well fitted to the linear Freundlich, Langmuir, and Dubinin–Radushkevich isotherm models. The adsorption kinetics data were best described by the pseudo‐second‐order kinetic model. FTIR was used to confirm the interaction of perchlorate with QACB. A small‐scale column test was carried out to evaluate the capacity of QACB for removing perchlorate from brackish water.

Heats of exchange of chloride with pyridinecarboxylate ions in Dowex-1 anion exchanger

The heats of exchange of chloride with pyridinecarboxylic acids anions in Dowex-1 strongly basic anion exchanger was obtained by the microcalorimetric method at 298 K. Nicotinic acid, isonicotinic acid, dipicolinic and cinchomeronic acids as pyridinecarboxylic acids were selected. It has been revealed that the sorption of pyridinecarboxylic acid anions by Cl form of Dowex-1 anion exchanger from aqueous solutions is the endothermic process. The standard enthalpy values of the exchange of chloride by pyridinecarboxylate ions in Dowex-1 anion exchanger calculated via microcalorimetric experimental data are in the range of 3–14 kJ mol−1. The standard enthalpies of model reaction that simulated the anion exchange process were determined via quantum chemical calculations of the reagent formation enthalpies in vacuum in the framework of the MOPAC2016 program. The enthalpies of both ion exchange of chloride by pyridinecarboxylate and the model reaction increase in the sequence: nicotinate, isonicotinate, anion of dipicolinic acid, anion of cinchomeronic acid.

Synthesis and Properties of Hydroxyl-Containing Ionic Liquids

Hydroxyl-containing ionic liquids were synthesized by quaternization of 1,2-dimethyl-1H-imidazole, N-methylpyrrolidine, and pyridine with 2-chloroethanol or 6-chlorohexan-1-ol, followed by exchange of chloride ion for bis(trifluoromethanesulfonyl)azanide, and their properties were studied.

Reactive CeO2 nanofluids for UV protective films

We investigate surface modification by organo-trimethoxysilanes of nano-ceria and if such surface-modified nano-ceria can be transformed into solvent-free nanofluids. We also examine whether simultaneous modification with ionic liquid salts and with acrylate groups yields nanofluids suitable for forming UV-protective films and clear coatings by UV-initiated polymerization. Nominally 3nm diameter CeO2 was successfully synthesized and surface decorated with an ionic liquid salt and with acrylate groups to produce a core/shell structured solvent-free nanofluid after ion exchange of chloride for a soft polyoxyethylene sulfonate anion. This room temperature nanofluid melts at about −10°C and exhibits a glass transition at about −71°C. The melting enthalpy, about 19J/g, corresponds approximately to the gain in surface free energy of such nanofluid particles upon transforming from the solid state to liquid state. Robust films were made by UV photoinitiation of this nanofluid in combination with ethylene glycol dimethacrylate and with a polyoxyethylene diacrylate to yield cross-linked films with absorption coefficients α350nm=6.6±0.8cm2/mg and α300nm=24.5±3.5cm2/mg. Average near UV protection over 300–350nm of 1–3 optical density units can be obtained with 0.065–0.19mg/cm2 of CeO2. These materials appear almost three-fold more effective, per unit ceria, than previously reported clearcoats of nanoceria.

Determination of an engineering model for exchange kinetics of strong acid cation resin for the ion exchange of sodium chloride & sodium bicarbonate solutions

This study identified an appropriate engineering model which described the exchange kinetics of sodium ions with a strong acid cation resin. Synthetic resins have potential application for the demineralization of coal seam (CS) water prior to beneficial reuse. However, there is limited data regarding the kinetic behaviour of strong acid cation (SAC) resin for the removal of sodium ions, the most prevalent ions in the water collected from coal seams (produced water) during natural gas extraction. In particular, exchange kinetics need to be understood in relation to estimating how full scale columns of resin may perform. Kinetic analysis revealed that the exchange of sodium ions from both sodium chloride and sodium bicarbonate solutions with SAC resin reached equilibrium within minutes at ambient temperature. Optimal simulation of the kinetic data for both chloride and bicarbonate containing solutions was achieved by application of the Brouers, Weron and Sotolongo (BWS) fractal equation; and this should be used as the basis for development of an engineering model. The model parameters varied depending upon the ratio of resin to liquid employed in the tests, with rates showing substantial enhancement once an excess of resin exchange sites were present. The exchange process was apparently controlled in part by intraparticle diffusion, with three phases inferred for sodium chloride solutions and two for sodium bicarbonate solutions. Other rate limiting phenomena such as film diffusion appeared to play a role under certain conditions.

Pathogen-induced secretory diarrhea and its prevention.

Secretory diarrhea is a historically known serious health implication around the world which primarily originates through pathogenic microorganisms rather than immunological or genetical disorders. This review highlights infective mechanisms of non-inflammatory secretory diarrhea causing pathogens, known therapeutics and their efficacy against them. These non-inflammatory diarrheal pathogens breach cell barriers, induce inflammation, disrupt fluid secretion across the epithelium by alteration in ion transport by faulting cystic fibrosis transmembrane conductance regulator (CFTR), calcium activated chloride channels and ion exchanger functions. Currently, a variety of prevention strategies have been used to treat these symptoms like use of antibacterial drugs, vaccines, fluid and nutritional therapy, probiotics and prebiotics as adjuncts. In progression of the need for a therapy having quick physiological effects, withdrawing the symptoms with a wide and safe therapeutic index, newer antisecretory agents like potent inhibitors, agonists and herbal remedies are some of the interventions which have come into light through greater understanding of the mechanisms and molecular targets involved in intestinal fluid secretion. Although these therapies have their own pros and cons inside the host, the quest for new antisecretory agents has been a successful elucidation to reduce burden of diarrheal disease.

Ion exchange of sodium chloride and sodium bicarbonate solutions using strong acid cation resins in relation to coal seam water treatment

Coal seam gas exploration has resulted in the production of large volumes of associated water which contains dissolved salts dominated by sodium chloride and sodium bicarbonate. Ion exchange using synthetic resins has been proposed as a method for desalination of coal seam water to make it suitable for various beneficial reuse options. This study investigated the behaviour of solutions of sodium chloride and sodium bicarbonate with respect to exchange with Lanxess S108H strong acid cation (SAC) resin. Equilibrium isotherms were created for solutions of NaCl and NaHCO3 and an actual sample of coal seam water from the Surat Basin in southern Queensland. The exchange of sodium ions arising from sodium bicarbonate was found to be considerably more favourable than exchange of sodium ions from sodium chloride solutions. This latter behaviour was attributed to the secondary decomposition of bicarbonate species under acidic conditions which resulted in the evolution of carbon dioxide and formation of water. The isotherm profiles could not be satisfactorily fitted by a single isotherm model such as the Langmuir expression. Instead, two Langmuir equations had to be simultaneously applied in order to fit the sections of the isotherm attributable to sodium ion exchange from sodium bicarbonate and sodium chloride. The shape of the isotherm profile was dependent upon the ratio of sodium chloride to sodium bicarbonate in solution and there was a high degree of correlation between simulated and actual coal seam water solutions.

Specific ion effects of chloride vis-à-vis acetate, propionate and butyrate counterions on the cetylpyridinium headgroup at the micelle–solution and air–solution interfaces

Aliphatic carboxylate anions due to their varying kosmotropy and hydrophobicity are expected to compete with chloride ion for binding at interfaces. Such competition leads to the specific ion effect (SIE) and investigating the SIE at micelle/solution and air/solution interfaces has a bearing on the selectivity of ions at biological interfaces. In this paper, critical micelle concentration (cmc) values of aqueous cetylpyridinium chloride solution in the presence of acetate, propionate and butyrate anions were determined by surface tension and conductance methods. Hydrodynamic radii of the cetylpyridinium micelles were measured by using the dynamic light scattering technique. The dependence of cmc on the added salt concentration is explained in the light of the modified Corrin–Harkins (CH) equation. Non-linearity of the plots of the modified CH equation is shown to be due to exchange of carboxylate and chloride ions at the micellar interface. The surface excess values of CPC in the presence of carboxylate anions are also calculated in the light of the Gibbs adsorption isotherm. The main finding of this study is that a new method has been demonstrated for determining selectivity coefficient (it quantifies the SIE) on the basis of the modified CH equation.

Decreased mobility of heavy metals in Haihe River sediments: The possible role of tide gate

The impact of tide gate on heavy metal mobility in Haihe River sediments was studied in a laboratory leaching simulation experiment. The results indicated that seawater promoted a higher release of Cd and Cu than deionized water and river water, and river water extracts high amounts of Zn. This release may be a result of both the formation of chloride complexes and ion exchange. However, the salinity induced by seawater did not significantly enhance the mobility of Pb. This implied that the mobility of Cd and Cu can be reduced by the insufficiency of the salinity when constructing tide gates in the brackish zones of an estuary. In the acidification processes, Cd and Zn were not, but Cu and Pb were, affected by an increase of salinity and ionic strength.

Impacts of integrated strong-acid cation exchange and weak-base anion exchange process for successful removal of saline toxicity from model olive mill wastewater

In the present work, the performance of a fixed-bed ion exchange (IE) process comprising novel strong-acid cation exchange and weak-base anion exchange resins was examined for the removal of the ionic species, that is, sodium and chloride ions, responsible for the high salinity of olive mill wastewater from an olive mill working with the two-phase decanting technology exiting a primary–secondary treatment (OMW-2ST). Sodium IE efficiency was found to increase with an increment in the pH value up 5, whereas the optimum pH for chloride IE was equal to 1. Equilibrium behaviour of both species was accurately predicted by Langmuir isotherm, showing sodium uptake is 53.9% higher than for chloride. Sodium and chloride removal efficiencies decreased (from 97.0 to 74.0% and from 95.0 to 77.0%, respectively) when their initial concentration increased from 250 to 1000mgL−1. Finally, the integrated IE system in continuous mode ensured 80–90% average removal efficiencies for both ionic species and conductivity. IE efficiency loss below 5% after several regeneration cycles is a technical-economical key fact. The final treated effluent complied with the standards established by the Food and Agricultural Association (FAO) with the goal of reusing the regenerated water for irrigation purposes.

A combined ion exchange–nanofiltration process for water desalination: I. sulphate–chloride ion-exchange in saline solutions

Removal of chloride ions from saline water with seven different ion-exchange (IX) resins in sulphate form has been studied both on laboratory and pilot scales. It was found that sulphate–chloride exchange is very fast in aqueous solutions and that the feed salt concentration and the nature of the functional group of the resin play an important role in this process. It was shown that the chloride/sulphate separation factor depends on salt content in feed water and the higher the substitution of hydrogen atoms in amine functional group of anion exchange resin the higher chloride over sulphate selectivity. Exhausted IX resins were successfully regenerated using 0.2M Na2SO4 solution and multiple regeneration/saturation cycles proved that this did not affect the resin's performance on chloride ion removal. It was shown that the osmotic pressure of sea water was significantly reduced after SO4/Cl ion exchange. Due to the drop of osmotic pressure lower energy consuming nanofiltration membranes compared with reverse osmosis membranes might be used for salty water desalination after IX treatment.

The Topochemical Pseudomorphosis of a Chloride into a Bismuthide

The heterogeneous reaction of crystals of the novel intermetallic subhalide Bi12 Rh3 Cl2 with a solution of n-butyllithium at 70 °C led to the complete topochemical exchange of chloride ions for bismuth atoms, that is, the transformation into the isostructural metastable intermetallic superconductor Bi14 Rh3. The crystals underwent the reductive pseudomorphosis almost unchanged except some fissures perpendicular to the a-axis. Detailed inspections of the transformed crystals by electron microscopy indicated no volume defects that would indicate internal chemical reactions. Thus, extensive mass transport must have occurred through the seemingly dense crystal structure. An efficient transport mechanism, based on an unusual breathing mode of the three-dimensional network formed by edge-sharing [RhBi8 ] cubes and antiprisms, is proposed. The replacement of ionic interaction in the chloride by metallic bonding in the binary intermetallic compound closes the pseudo gap in the density of states at the Fermi level. As a result, the rod-packing of conducting, yet electrically isolated strands of [RhBi8] cubes in Bi12 Rh3 Cl2 turns into the three-dimensional metal Bi14 Rh3.

Geo-electrical Delineation and Geochemical Characteristics of Aquifer Systems in Kwa-Ibo River Watershed, Abia State, Nigeria

Kwa-Ibo River watershed of Abia State, Nigeria cuts across four Local Government Areas in the State and lies geologically within the Benin Formation of Niger Delta Basin. Due to the prolific nature of Benin Formation aquifers, preliminary investigations for groundwater exploitation are seldom done but due to the recent borehole failures and the ever increasing population density of the area, a proper documentation of the hydro-geological conditions of the area is essential. This led to a geo-electrical investigation whereby thirteen Vertical Electrical Sounding (VES) data were acquired and the computer-aided Resist software method was used for further processing and interpretation. The interpretation of the VES data reveals the existence of three to seven geo-electric layers Original Research Article Amos-Uhegbu et al.; JSRR, Article no. JSRR.2014.006 819 in the area and a variation in aquifer thicknesses with the least as 101m at VES Station 4 and the highest as 324m at VES Station 2. A comparison of some geo-electric sections generated from VES stations with some lithologs gave a good geological description of the study area. Water samples were taken from eleven boreholes for hydro-geochemical investigation which reveals the occurrence of two major groundwater types in the area with Calcium+Magnesium chloride bicarbonate [(Ca+Mg)-HCO3 + SO4Cl] dominating in the entire area except in the North-western part where Sodium+Potassium chloride bicarbonate [(Na+K)-HCO3-Cl] dominates. Further analysis shows that the geochemical processes resulting from the major geologic controls are chloride dissolution, silicate weathering, carbonate weathering and ion exchange and by using Gibb’s Diagram the recharge occurs through precipitation while the local geology is the source of major ion concentrations in the samples.