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Thermophoresis has emerged as a powerful tool for characterizing and manipulating colloids at the nano- and micro-scales due to its sensitivity to colloid–solvent interactions. The use of surfactants enables the tailoring of surface chemistry on colloidal particles and the tuning of interfacial interactions. However, the microscopic mechanisms underlying thermophoresis in surfactant solutions remain poorly understood due to the complexity of multiscale interaction coupling. To achieve a more fundamental understanding of the roles of surfactants, we investigated the thermophoretic behavior of silica beads in both ionic and nonionic surfactant solutions at various background temperatures. We provide a complete mechanistic picture of the effects of surfactants on interfacial interactions through mode-coupling analysis of both electrophoretic and thermophoretic experiments. Our results demonstrate that silica thermophoresis is predominantly governed by the dissociation of silanol functional groups at silica–water interfaces in nonionic surfactant solutions, while in ionic surfactant solutions, the primary mechanism driving silica thermophoresis is the adsorption of ionic surfactants onto the silica surface. [ABSTRACT FROM AUTHOR]

Concentrated ionic aqueous electrolytes possess a diverse array of applications across various fields, particularly in the field of energy storage. Despite extensive examination, the intricate relationships and numerous physical mechanisms underpinning diverse phenomena remain incompletely understood. Molecular dynamics simulations are employed to probe the attributes of aqueous solutions containing LiCl, NaCl, KCl, MgCl2, and CaCl2, spanning various solute fractions. The primary emphasis of the simulations is on unraveling the intricate interplay between these attributes and the underlying physical mechanisms. The configurations of cation-Cl− and Cl−–Cl− pairs within these solutions are disclosed. As the solute fraction increases, consistent trends manifest regardless of solute type: (i) the number of hydrogen bonds formed by the hydration water surrounding ions decreases, primarily attributed to the growing presence of counter ions in proximity to the hydration water; (ii) the hydration number of ions exhibits varying trends influenced by multiple factor; and (iii) the diffusion of ions slows down, attributed to the enhanced confinement and rebound of cations and Cl− ions from the surrounding atoms, concurrently coupled with the changes in ion vibration modes. In our analysis, we have, for the first time, clarified the reasons behind the slowing down of the diffusion of the ions with increasing solute fraction. Our research contributes to a better understanding and manipulation of the attributes of ionic aqueous solutions and may help designing high-performance electrolytes. [ABSTRACT FROM AUTHOR]

In recent years, ionic microgels have garnered much attention due to their unique properties, especially their stimulus-sensitive swelling behavior. The tunable response of these soft, permeable, compressible, charged colloidal particles is increasingly attractive for applications in medicine and biotechnologies, such as controlled drug delivery, tissue engineering, and biosensing. The ability to model and predict variation of the osmotic pressure of a single microgel with respect to changes in particle properties and environmental conditions proves vital to such applications. In this work, we apply both nonlinear Poisson–Boltzmann theory and molecular dynamics simulation to ionic microgels (macroions) in the cell model to compute density profiles of microions (counterions, coions), single-microgel osmotic pressure, and equilibrium swelling ratios of spherical microgels whose fixed charge is confined to the macroion surface. The basis of our approach is an exact theorem that relates the electrostatic component of the osmotic pressure to the microion density profiles. Close agreement between theory and simulation serves as a consistency check to validate our approach. We predict that surface-charged microgels progressively deswell with increasing microgel concentration, starting well below close packing, and with increasing salt concentration, in qualitative agreement with experiments. Comparison with previous results for microgels with fixed charge uniformly distributed over their volume demonstrates that surface-charged microgels deswell more rapidly than volume-charged microgels. We conclude that swelling behavior of ionic microgels in solution is sensitive to the distribution of fixed charge within the polymer-network gel and strongly depends on bulk concentrations of both microgels and salt ions. [ABSTRACT FROM AUTHOR]

Molecular simulations in an open environment, involving ion exchange, are necessary to study various systems, from biosystems to confined electrolytes. However, grand-canonical simulations are often computationally demanding in condensed phases. A promising method [L. Belloni, J. Chem. Phys. 151, 021101 (2019)], one of the hybrid nonequilibrium molecular dynamics/Monte Carlo algorithms, was recently developed, which enables efficient computation of fluctuating number or charge density in dense fluids or ionic solutions. This method facilitates the exchange through an auxiliary dimension, orthogonal to all physical dimensions, by reducing initial steric and electrostatic clashes in three-dimensional systems. Here, we report the implementation of the method in LAMMPS with a Python interface, allowing facile access to grand-canonical molecular dynamics simulations with massively parallelized computation. We validate our implementation with two electrolytes, including a model Lennard-Jones electrolyte similar to a restricted primitive model and aqueous solutions. We find that electrostatic interactions play a crucial role in the overall efficiency due to their long-range nature, particularly for water or ion-pair exchange in aqueous solutions. With properly screened electrostatic interactions and bias-based methods, our approach enhances the efficiency of salt-pair exchange in Lennard-Jones electrolytes by approximately four orders of magnitude, compared to conventional grand-canonical Monte Carlo. Furthermore, the acceptance rate of NaCl-pair exchange in aqueous solutions at moderate concentrations reaches about 3% at the maximum efficiency. [ABSTRACT FROM AUTHOR]

For industrial applications of self-assembled wormlike micelles, measurement and characterization of a micellar material's microstructure and rheology are paramount for the development and deployment of new high-performing and cost-effective formulations. Within this workflow, there are significant bottlenecks associated with experimental delays and a lack of transferability of results from one chemistry to another. In this work, we outline a process to predict microscopic and thermodynamic characteristics of wormlike micelles directly from rheological data by combining a more robust and efficient fitting algorithm with a recently published constitutive model called the Toy Shuffling model [J. D. Peterson and M. E. Cates, J. Rheol. 64, 1465–1496 (2020) and J. D. Peterson and M. E. Cates, J. Rheol. 65, 633–662 (2021)]. To support this work, linear rheology measurements were taken for 143 samples comprising a common base formulation of commercial sodium lauryl ether sulfate, cocamidopropyl betaine, and salt (NaCl). The steady state zero shear viscosity evident in linear rheology was measured in duplicate via direct steady and oscillatory shear experiments. Fitting the collected data to the model, we found trends in the microstructural and thermodynamic characteristics that agree with molecular dynamics simulations. These trends validate our new perspective on the parameters that inform the study of the relationship between chemical formulation and rheology. This work, when implemented at scale, can potentially be used to inform and test strategies for predicting self-assembled micellar structures based on chemical formulation. [ABSTRACT FROM AUTHOR]

Atmospheric aerosol particles can impact the optical depth of mixed-phase clouds through heterogeneous ice nucleation. Ice nucleating particles (INP) are therefore important contributors to global and local climate but remain under-parameterized in climate models, partially due to the complex interaction between composition and processing conditions. In this article, we study the ice nucleation (IN) activity of montmorillonite bentonite clay which is a common model dust INP, utilizing a 150-well microfluidic device. Refreezing tests are carried out for solutions across a range of salinity and pH to determine the impact of composition and processing on droplet freezing behavior, with and without an intermediate relative humidity (RH) cycling step. It is found that freezing order deviation dramatically increases after droplets undergo RH cycling, and the potential influence on IN activity of delamination of clay when subjected to changing RH conditions is discussed. Freezing order deviation decreases with increasing solution ionic strength, a trend linked to the delamination behavior of bentonite clays, and an overall decrease in IN activity at low pH is observed, possibly due in part to pH-dependent changes in clay aggregate size distribution. The authors conclude that pH changes and RH processing, such as those which naturally occur in the atmosphere, have a marked impact on the IN activity of clay-containing aerosol droplets. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

A facile room-temperature synthetic method is presented to produce alkali metal salts of tert-butyl phosphonic acid. The reaction between equimolar amounts of alkali metal carbonates and tert-butyl phosphonic acid in methanol results in the formation of [(tBuPO3H)Li(H2O)3•(H2O)] (1), [(tBuPO3)Na2(H2O)4]n (2), and [(tBuPO3H)K(H2O)]n (3). Solid-state structures of these compounds have been confirmed by single-crystal X-ray diffraction studies and further validated using numerous spectroscopic and analytical techniques. Compounds 1--3 are polymeric solids that are predominantly made up of a 1-D polymeric metal phosphonate chain. This synthetic approach leads to the formation of network structures/polymers in the solid state that otherwise are absent in solution due to the ionic nature of the interaction between the alkali metal ions and phosphonate anions. Apart from the multidentate nature of the phosphonate ligands, additional hydrogen bonding interactions involving water molecules, free P--OH groups, and P O moieties allow these chains to be propagated into 2-D sheets. We have further utilized the completely metalated sodium phosphonate 2 to synthesize layered metal phosphonates [(tBuPO3)Ca(H2O)]n (4), [(tBuPO3)Mn(H2O)]n (5) and [(tBuPO3)Co(H2O)]n (6) via a simple metathesis reaction. [ABSTRACT FROM AUTHOR]

We utilize molecular dynamics simulations to investigate the microstructures of ions and polyelectrolytes in aqueous solutions under external electric fields. By focusing on the multi-body interactions between ionic components and H2O molecules, as well as their responses to the external electric fields, we clarify several nontrivial molecular features of the ionic and polyelectrolyte solutions, such as the solvations of cations and anions, clustering of the ions, and dispersions/aggregations of polyelectrolyte chains, as well as the corresponding responses of H2O molecules in these contexts. Our simulations illustrate the variations in structures of ionic solutions caused by reversing the charge sign of the ions, and elucidate the disparity in structures between anionic and cationic polyelectrolyte solutions in the presence of the external electric fields. This work clarifies the mechanism for the alternations in complex multi-body interactions in aqueous solutions caused by the application electric field, which can contribute to the fundamental understanding of the physical and chemical natures of ion-containing and charged polymeric systems. [ABSTRACT FROM AUTHOR]

The conditions and influencing factors of hydrate formation is significant for hydrate technology. Combining with the existing literatures and the experimental data of this work, the phase equilibrium of CO2 hydrate in (NaCl/CaCl2/MgCl2) ionic solutions, pure water-sediment system and (NaCl/CaCl2/MgCl2) ionic solution-sediment systems under the static magnetic field (0.39 T) was studied. Moreover, the effect mechanism of magnetic field on hydrate phase equilibrium in different systems was analyzed in terms of intermolecular interaction. Under the same pressure, the magnetic field increased the phase equilibrium temperature of CO2 hydrate by 2.0–2.8 K in the three ionic solutions, which improved the hydrate formation conditions. This is mainly due to that the magnetic effect increases water activity and weakens the ionic hydration shells, thus promotes hydrate formation. In addition, compared with the ionic solution systems without magnetic field, the magnetic field increased the hydrate phase equilibrium temperature by 0.1–2.5 K in the ionic solution-sediment systems. However, the degree of temperature increase is less than that in the magnetic field-ionic solution systems, which is because the magnetic field enhances the binding between ions and the sediment particle in sediment-bearing systems. Compared with the magnetic field-ionic solution systems, the water activity in the magnetic field-ionic solution-sediment systems is lower, which makes hydrate formation more difficult. Moreover, with the movement of cations and anions in magnetic field, the crystals may be formed due to ion collisions, enhance the capillary action in ionic solution-sediment systems, and then hinder the hydrate formation. Therefore, the sediments can weaken the magnetic field promotion to hydrate formation. [ABSTRACT FROM AUTHOR]

The speciation and mobility of rare earth elements (REE) strongly depends on pH, which controls the formation of charged aqueous hydroxyl species. The latter potentially play an important role in controlling heavy REE adsorption on clay minerals in near-neutral to alkaline waters such as in regolith-hosted REE mineral deposits. However, accurate REE hydrolysis constants are needed for developing geochemical models that can predict the role of these charged species in natural systems. Here, we develop a robust experimental UV-Vis spectrophotometric method using m-cresol purple to determine in situ pH from 25 to 75 °C. This method is used to derive the average ligand number and hydrolysis constants of erbium (Er) at 25 °C in aqueous solutions with low ionic strength (≤0.001 mol L−1) at pH from ∼7 to 9.5 and in the presence of Er concentrations from 0 to 0.057 mM. The average ligand number ranges between 1 and 3 indicating that Er(OH)2+, Er(OH)2+ and Er(OH) 03 control speciation in the experiments. The logarithm of the Er hydrolysis constants (, n = 1 to 3) derived at infinite dilution for the reaction Er3+ + nH2O = Er(OH)n3−n + nH+ are: , ,. Implementation of these experimental data into a geochemical model indicates that the Er(OH)2+ and Er(OH) 03 species are both stable in a much wider pH range than previously predicted. Consequently, the positively charged REE hydroxyl complexes can potentially control the fractionation of light vs. heavy REE via adsorption as observed in the formation of certain regolith-hosted REE deposits. [ABSTRACT FROM AUTHOR]

Electrochemical reactions via carbocation intermediates remain fundamental transformations that build up molecular functionality and complexity in a sustainable manner. Enantioselective control of such processes is a great challenge in a highly ionic electrolyte solution. Here, we report an anodic generation of chiral α-imino carbocation intermediates by enamine catalysis. The chiral carbocation intermediates can be intercepted by a variety of nucleophiles such as alcohols, water and thiols with high stereoselectivity. The key SN1 step proceeds via a tertiary amine-mediated proton shuttle that facilitates facial selection in reacting with carbocation. Carbocations are useful synthetic intermediates which enable direct functionalization of carbon centers, but their generation in a manner that uses mild conditions and enables stereoselective interception remains a longstanding goal of organic chemists. Here, the authors use electrochemical enamine oxidation to synthesize chiral scaffolds from racemic α-branched aldehydes. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Implementing encapsulation techniques is pivotal in safeguarding bioactive molecules against environmental conditions for drug delivery systems. Moreover, the food‐grade nanocarrier is a delivery system and food ingredient crucial in creating nutraceutical foods. Nano α‐lactalbumin has been shown to be a promissory nanocarrier for hydrophobic molecules. Furthermore, the nanoprotein can enhance the tecno‐functional properties of food such as foam and emulsion. The present study investigated the nanostructured α‐lactalbumin protein (nano α‐la) as a delivery and controlled release system for bioactive molecules in a gastric‐intestinal in vitro mimic system.The nano α‐la was synthesized by a low self‐assembly technique, changing the solution ionic strength by NaCl and obtaining nano α‐la 191.10 ± 21.33 nm and a spherical shape. The nano α‐la showed higher encapsulation efficiency and loading capacity for quercetin than riboflavin, a potential carrier for hydrophobic compounds. Thermal analysis of nano α‐la resulted in a ΔH of −1480 J g−1 for denaturation at 57.44 °C. The nanostructure formed by self‐assembly modifies the foam volume increment and stability. Also, differences between nano and native proteins in emulsion activity and stability were noticed. The release profile in vitro showed that the nano α‐la could not hold the molecules in gastric fluid. The Weibull and Korsmeyer‐Peppas model better fits the release profile behavior in the studied fluids.The present study shows the possibility of nano α‐la as an alternative to molecule delivery systems and nutraceutical foods' formulation because of the high capacity to encapsulate hydrophobic molecules and the improvement of techno‐functional properties. However, the nanocarrier is not perfectly suitable for the sustainable delivery of molecules in the gastrointestinal fluid, demanding improvements in the nanocarrier. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Owing to their application in rock weathering concerning geostructural stability, enhanced geothermal systems, carbon sequestration, and enhanced oil recovery, the effect of rock–brine–CO2 interactions on the microstructural and mechanical properties of rocks has become a prevalent topic. Understanding the interplay among chemical, microstructural, and mechanical processes is essential to comprehend how they affect rock mechanical alteration. In this study, we examined the effects of chemo-mechanical loading on the microstructural features and mechanical alterations of individual components within the rock. Experiments involved exposing the Permian rock samples to either CO2 or N2-rich brine (a control condition) at a temperature and pressure of 100 °C and 1800 Psi, respectively, for varying duration (14 and 28 days). The ionic strength of the solution was adjusted to 1 M using NaCl. Micro-CT image analysis showed the dissolution of clay- and quartz-rich phases followed by their precipitation. After 14 days, the depth of the outer reacted zone reached roughly 1100 µm, and after 28 days, the depth increased to 1500 µm. Microscale mechanical analysis showed decreased indentation modulus of the clay- and quartz-rich phases after reacting with CO2-rich brine. This decrease in indentation modulus was more than 50% for quartz-rich phases for 28 days of reaction and was lower adjacent to the reacted surface. The decrease in mechanical properties was more pronounced at a distance of 400–600 µm from the reacted surface after 14 days of reaction with CO2-rich brine due to the pore-size controlled solubility phenomenon. Experiments conducted at a greater distance from the reacted surface (approximately 5 mm) revealed a weaker clay–quartz interface, possibly due to the formation of microcracks induced by the swelling of clay particles. Results for the N2 condition show a superficial mechanical alteration of the rock constituents limited to a depth of 200 µm from the reacted surface. Highlights: Study investigates chemo-mechanical and microstructural alteration of silicate-rich shale rock by CO2/ N2-rich brines. Dissolution of clay and quartz-rich phases followed by the precipitation of clay and quartz from the transformation of feldspar grains in CO2 condition. The modulus of clay- and quartz-rich zones decreased in reacted areas but increased near the surface in CO2 samples. N2 condition causes superficial mechanical alteration, minimal dissolution. Pore-size-controlled solubility play an important role in the evolution of porosity in the context of rock-fluid interaction. Experiments conducted at a greater distance from the reacted surface indicated a weakened clay–quartz interface under CO2 conditions. [ABSTRACT FROM AUTHOR]

The utilization of biodegradable hydrogels based on natural polysaccharides in the agricultural and biomedical sectors is anticipated to be a growing field of interest. Due to increasing environmental pollution, the current global goal is to synthesize sustainable materials based on natural polysaccharides to conserve natural resources for the future. In this study, we synthesized an amla-based hydrogel, denoted as AL-g-poly(MAA), using the graft-free radical polymerization method. Methacrylic acid (MAA) was employed as the monomer, N,N′-methylenebisacrylamide (MBA) served as the crosslinker, and ammonium persulfate (APS) acted as the initiator. The synthesized hydrogel, AL-g-poly(MAA), underwent optimization by adjusting seven parameters: initiator, solvent, time, monomer, power, pH, and crosslinker, to achieve the highest swelling percentage. The optimized values were as follows: solvent: 10 ml, time: 150 s, monomer: 0.039 mol/L, power: 60%, pH: 7, and crosslinker: 0.0648 mol/L. The cross-linking process was confirmed through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) techniques. The swelling behavior of the synthesized hydrogels was determined in saline solutions with varying ionic strengths and concentrations, revealing maximum swelling in solutions with lower ionic strengths and concentrations. Additionally, the density and porosity of the hydrogels were examined. The biodegradability of AL-g-poly(MAA) was tested through soil burial and vermicomposting experiments, demonstrating its significant potential for agriculture applications. Furthermore, both the backbone and the synthesized hydrogel were evaluated for antibacterial activity against four bacterial strains (Burkholderia gladioli, Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus cereus), revealing strong potential as an antimicrobial agent and therefore having applications in the biomedical field. The mechanism underlying the inhibitory effect of synthesized AL-g-poly(MAA) hydrogel on bacterial cell membranes is also discussed. [ABSTRACT FROM AUTHOR]

The physical interactions between anionic and cationic monomers and the layered silicate clay mineral Laponite (XLG) have received great attention because of their potential for a variety of applications such as strain sensitive sensors, wearable electronics, drug delivery systems, and tissue engineering applications. A detailed investigation of the interaction between XLG and charged monomers is presented in this article. The study includes the observation of the changes in the viscosity of the solutions and the mechanical performance of the gels at various concentrations by adding XLG to the ionic monomer solution. The ionic interactions between XLG and the charged monomers, driven by electrostatic forces, play a crucial role in gelation and formation of a three-dimensional network, giving the structure strain rate sensitivity. In this way, the addition of XLG nanoparticles not only improves the mechanical properties of the gels, but also gives us information about the microstructure of the mechanical properties that change depending on the strain rate. [ABSTRACT FROM AUTHOR]

Vulvovaginitis is a growing concern worldwide because of increasing drug resistance, drug toxicity, low bioavailability, and limitations of topical administration. The purpose of the study was to develop a novel mucoadhesive in situ gel of quercetin–cyclodextrin (CD)-loaded chitosan nanoparticles (NPs) for the treatment of vulvovaginitis. In this work, an innovative association between mucoadhesive (chitosan) and thermosensitive polymers (poloxamer 188 and 407) was used to treat vulvovaginitis. The formulation showed compatible pH (4.08) and a desired rheological behavior (viscosity—158.9 cps at 25.9°C, gelation temperature—37°C, and gelation time—65 s) suitable for vaginal application. The quercetin/sulfobutyl-ether-β-cyclodextrin-loaded chitosan NPs (QCD-NPs), prepared by the ionic-gelation method, showed higher in vitro antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa compared with the quercetin solution because of the ionic interaction between chitosan NPs and bacteria. Moreover, upon incorporating the QCD-NP in in situ gel, the clearance from the vagina might further reduce and longer residence can be achieved at the site of vaginal infection because of sol–gel transition at body temperature. The developed formulation was confirmed to be biocompatible, nonirritant (hen's egg chorioallantoic membrane assay), and bioadhesive (mucoadhesion test) with good antimicrobial efficacy and sustained drug release profile, paving the path for improved therapeutic interventions in the treatment of vulvovaginitis. [ABSTRACT FROM AUTHOR]

[Display omitted] At the interface between an ion-exchange membrane and a multi-electrolyte solution, charged species redistribute themselves to minimize the free energy of the system. In this paper, we explore the Donnan equilibrium of membranes with quaternary electrolyte (Na+/Mg2+/K+/Ca2+/Cl−) solutions, experimentally. The data was used to calculate the ion activity coefficients for six commercial cation-exchange membranes (CEMs). After setting one of the activity coefficients to an arbitrary value, we used the remaining (N-1) activity coefficients as fitting parameters to describe the equilibrium concentrations of (N) ionic species with a mean relative error of 3 %. At increasing solution ionic strengths, the equivalent ion fractions of monovalent counter-ions inside the membrane increased at the expense of the multivalent ones in alignment with the Donnan equilibrium theory. The fitted activity coefficients were employed in a transport model that simulated a Donnan dialysis experiment involving all four cations simultaneously. The arbitrary value assigned to one activity coefficient affects the calculated Donnan potential at the membrane interface. Nevertheless, this arbitrary value does not affect the prediction of the ion concentrations inside the membrane and consequently does not affect the modeled ion fluxes. [ABSTRACT FROM AUTHOR]

Neonicotinoids are widely used insecticides that accumulate in various environmental matrixes and potentially harm non-target organisms. However, the mechanism of sorption/desorption of neonicotinoids in different loess soils remains poorly understood. Therefore, this study investigated the sorption/desorption of nitenpyram (NIT), a commonly used neonicotinoid, in three different types of loess soils and examined factors influencing the adsorption process using batch experiments. The findings revealed that NIT reached adsorption equilibrium in 4 h in all three loess soil samples. The R2 value (> 0.898) obtained from fitting the sorption/desorption kinetics indicated a good match with the pseudo-second-order model, suggesting the involvement of multiple mechanisms, including chemisorption. The linear and Freundlich models also adequately described the sorption of NIT in loess soils. Additionally, a clear hysteresis phenomenon was observed. The adsorption capacity of NIT is significantly related to the adsorption temperature, solution pH and ionic strength. Upon increasing the initial concentration, the equilibrium adsorption capacity of NIT for gray-cinnamon soil, sierozem, and cultivated loessial soil increased from 3.56, 2.51, and 2.64 mg/kg to 8.49, 3.92, and 5.22 mg/kg, respectively. FTIR spectral analysis revealed that the adsorption of NIT in loess soil was primarily governed by mixed mechanism. This study elucidates the behavior and fate of NIT in soil–water systems in the Northwest, while also establishing a foundation for assessing its ecological risks. The findings have significant practical implications for the future development of environmental management and pollution control strategies. [ABSTRACT FROM AUTHOR]

We present the coupling of two frameworks—the pseudo-open boundary simulation method known as constant potential molecular dynamics simulations (CμMD), combined with quantum mechanics/molecular dynamics (QMMD) calculations—to describe the properties of graphene electrodes in contact with electrolytes. The resulting CμQMMD model was then applied to three ionic solutions (LiCl, NaCl, and KCl in water) at bulk solution concentrations ranging from 0.5 M to 6 M in contact with a charged graphene electrode. The new approach we are describing here provides a simulation protocol to control the concentration of electrolyte solutions while including the effects of a fully polarizable electrode surface. Thanks to this coupling, we are able to accurately model both the electrode and solution side of the double layer and provide a thorough analysis of the properties of electrolytes at charged interfaces, such as the screening ability of the electrolyte and the electrostatic potential profile. We also report the calculation of the integral electrochemical double layer capacitance in the whole range of concentrations analyzed for each ionic species, while the quantum mechanical simulations provide access to the differential and integral quantum capacitance. We highlight how subtle features, such as the adsorption of potassium graphene or the tendency of the ions to form clusters contribute to the ability of graphene to store charge, and suggest implications for desalination. [ABSTRACT FROM AUTHOR]

An ionic liquid (IL) is a salt in the liquid state that consists of a cation and an anion, one of which possesses an organic component. Because of their non-volatile property, these solvents have a high recovery rate, and, hence, they are considered as environment-friendly green solvents. It is necessary to study the detailed physicochemical properties of these liquids for designing and processing techniques and find suitable operating conditions for IL-based systems. In the present work, the flow behavior of aqueous solutions of an imidazolium-based IL, 1-methyl-3-octylimidazolium chloride, is investigated, where the dynamic viscosity measurements indicate non-Newtonian shear thickening behavior in the solutions. Polarizing optical microscopy shows that the pristine samples are isotropic and transform into anisotropic after shear. These shear thickened liquid crystalline samples change into an isotropic phase upon heating, which is quantified by the differential scanning calorimetry. The small angle x-ray scattering study revealed that the pristine isotropic cubic phase of spherical micelles distort into non-spherical micelles. This has provided the detailed structural evolution of mesoscopic aggregates of the IL in an aqueous solution and the corresponding viscoelastic property of the solution. [ABSTRACT FROM AUTHOR]

Polarimetric angle-resolved second-harmonic scattering (AR-SHS) is an all-optical tool enabling the study of unlabeled interfaces of nano-sized particles in an aqueous solution. As the second harmonic signal is modulated by interference between nonlinear contributions originating at the particle's surface and those originating in the bulk electrolyte solution due to the presence of a surface electrostatic field, the AR-SHS patterns give insight into the structure of the electrical double layer. The mathematical framework of AR-SHS has been previously established, in particular regarding changes in probing depth with ionic strength. However, other experimental factors may influence the AR-SHS patterns. Here, we calculate the size dependence of the surface and electrostatic geometric form factors for nonlinear scattering, together with their relative contribution to the AR-SHS patterns. We show that the electrostatic term is stronger in the forward scattering direction for smaller particle sizes, while the ratio of the electrostatic to surface terms decreases with increasing size. Besides this competing effect, the total AR-SHS signal intensity is also weighted by the particle's surface characteristics, given by the surface potential Φ0 and the second-order surface susceptibility χ s , 2 2 . The weighting effect is experimentally demonstrated by comparing SiO2 particles of different sizes in NaCl and NaOH solutions of varying ionic strengths. For NaOH, the larger χ s , 2 2 values generated by deprotonation of surface silanol groups prevail over the electrostatic screening occurring at high ionic strengths; however, only for larger particle sizes. This study establishes a better connection between the AR-SHS patterns and surface properties and predicts trends for arbitrarily-sized particles. [ABSTRACT FROM AUTHOR]

Factors affecting the swelling of cellulosic fibers are considered in this review. Emphasis is placed on aqueous systems and papermaking fibers, but the review also considers cellulose solvent systems, nanocellulose research, and the behavior of cellulosic hydrogels. The topic of swelling of cellulosic fibers ranges from effects of humid air, continuing through water immersion, and extends to hydrogels and the dissolution of cellulose, as well as some of its derivatives. The degree of swelling of cellulose fibers can be understood as involving a balance between forces of expansion (especially osmotic pressure) vs. various restraining forces, some of which involve the detailed structure of layers within the fibril structure of the fibers. The review also considers hornification and its effects related to swelling. The expansive forces are highly dependent on ionizable groups, pH, and the ionic strength of solution. The restraining forces depend on the nature of lignin, cellulose, and their detailed structural arrangements. [ABSTRACT FROM AUTHOR]

The validity of the theoretical Debye–Hückel length (κ−1), determined on the basis of the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, to characterize diffuse layer thickness has been experimentally challenged. A series of linear swelling tests using a LVDT apparatus was utilized to measure shale swelling as it interacted with various ionic solutions. A regression technique was employed to develop an empirical equation for an experimental Debye–Hückel length (κE−1) as a function of ionic strength (I) and swelling displacement (ΔL). Results showed that the measured κE−1 is less than the predicted κ−1 due to the physicochemical interactions of shale with the ionic solutions. Such discrepancy had a profound impact on the estimated electric potential (ψ/ψ0) and total interaction energy (VT) in the electrical diffuse double layer (EDDL). Moreover, the energy barrier was found to be smaller when κE−1 is used as the diffuse layer's thickness than when ±E−1 is used. Results also showed that increasing the ionic strength of the solution decreases the energy barrier and the distance (x) at which the energy barrier occurs (location). The blind reliance on theoretical (κ−1) may induce errors in characterizing clay behavior in the presence of ionic solutions, which could compromise the process of design and engineering, especially those related to wellbore stability problems. Practical Applications: Shale swelling is regarded to be one of the main causes of wellbore stability in shale formations drilled with water-based muds. The unfavorable exchange of water and ions between shale and water-based drilling muds may lead to the expansion or shrinkage of clay platelets. To avoid shale swelling, water extraction out of shale by means of chemical osmosis, through the addition of salts, is often adopted in order to reduce the amount of clay platelets separation between clays that make up shale formations. The separation distance between clay platelets is generally associated with the Debye–Hückel length, diffuse layer thickness. Therefore, many operators rely on theoretical Debye–Hückel length to get a first-hand estimate of the amount of shale swelling prior to the application of certain salt drilling muds. The blind reliance on theoretical Debye–Hückel length may underestimate the diffuse layer thickness and separation distance between clay platelets because it completely ignores the physicochemical interactions of clay with the ionic solutions. Such practice may induce errors in characterizing clay behavior in the presence of ionic solutions, which could compromise the process of design and engineering, especially those related to wellbore stability problems. This may eventually lead to wellbore collapse and loss of resources. [ABSTRACT FROM AUTHOR]

90Sr is one of the most monitored fission products. New efficient methods for strontium separation are therefore sought. Over the past 20 years, crown ethers solutions in ionic liquids (ILs) have been confirmed to efficiently extract strontium from acidic solutions. Despite all the work done in this field, the extraction mechanism is still not completely clear. Depending on experimental conditions, the extraction is believed to proceed either in the form of an ion-association complex [Sr·CE·(NO3)2] or via exchange between [Sr·CE]2+ and two IL cations. This work aims to study the influence of several extraction parameters and compare them with the presumed mechanisms. [ABSTRACT FROM AUTHOR]

It is a challenge that extracting rubidium directly from the salt lakes by electrochemical method, because of the low content of rubidium ions and other complex co-existing ions in the salt lakes. Copper hexacyanoferrate (CuHCF) with good electrochemical performance in desalination and aqueous batteries, may be used as the electrode material of electrochemical extracting rubidium. In this paper, CuHCF is synthesized by one-step precipitation method by adding copper ions in K3Fe(CN)6 solution. Cyclic voltammetry is studied with the CuHCF electrode sheets in alkali metal ions and simulated brine electrolytes. The alkali metal ions insertion and de-insertion in the electrodes are mainly controlled by diffusion process with cyclic stability. The diffusion rate of K+ is the largest, Li+ the smallest. The insertion and de-insertion process are reversible in Na+, K+ and Rb+ ionic solutions. The cyclic voltammetry current of the CuHCF electrode sheet in Na+ ionic solution shows two pairs of redox peaks. The cyclic voltammetry currents of CuHCF electrode sheet in simulated brine mainly show is the peak current of that in Na+ and K+ ionic solutions. [ABSTRACT FROM AUTHOR]

Background: Fluid therapy in veterinary medicine is pivotal for treating various conditions in pigs; however, standard solutions, such as Hartmann's solution, may not optimally align with pig physiology. This study explored the development and efficacy of a customized fluid therapy tailored to the ionic concentrations of pig blood, aiming to enhance treatment outcomes and safety in both healthy and diseased pigs. Results: The study involved two experiments: the first to assess the safety and stability of customized fluids in healthy pigs, and the second to evaluate the efficacy in pigs with clinical symptoms of dehydration. In healthy pigs, the administration of customized fluids showed no adverse effects, with slight alterations observed in pO2, hematocrit, and glucose levels in some groups. In symptomatic pigs, the customized fluid group did not show any improvement in clinical symptoms, with no significant changes in blood chemistry or metabolite levels compared to controls. The customized fluid group showed a mild increase in some values after administration, yet within normal physiological ranges. The study reported no significant improvements in clinical or dehydration status, attributing the observed variations in blood test results to the limited sample size and anaesthesia effects rather than fluid characteristics. Conclusions: Customized fluid therapy, tailored to mimic the ionic concentrations of pig blood, appears to be a safe and potentially more effective alternative to conventional solutions such as Hartmann's solution for treating pigs under various health conditions. Further research with larger sample sizes and controlled conditions is recommended to validate these findings and to explore the full potential of customized fluid therapy in veterinary practice. [ABSTRACT FROM AUTHOR]

Ionic liquids are known as efficient pretreatment solvents for cellulosic biomass, but typical cellulose-dissolving ionic liquids are toxic to microorganisms, hindering the fermentation process for bioethanol production. Although the ionic liquids can be removed by washing after pretreatment, it negatively impacts the energy balance. Therefore, successive/simultaneous biomass pretreatment, hydrolysis, and fermentation processes with low-toxicity ionic liquids are desired. Herein, especially for the beginners and students, the toxicity of ionic liquids and their mechanisms by which the microorganisms are destroyed are simply discussed. Furthermore, two currently evolving solutions, low-toxicity ionic liquids and ionic liquid-resistant microorganisms for bioethanol production, are discussed. To the best of my knowledge, this is the first review specifically focusing on bioethanol fermentation in ionic liquid solutions, whereas there are many reports on cellulose dissolution. [ABSTRACT FROM AUTHOR]

Three ionic liquids (ILs) and three deep eutectic solvents (DESs) with identical counterparts, as well as their aqueous solutions, were prepared for the selective extraction of alginate from Sargassum tenerrimum, a brown seaweed. It was found that the ILs and their hydrated systems were only able to extract alginate from the seaweed directly, while the DESs were not, as confirmed by molecular docking studies. When the quality of the polysaccharide was compared to that produced using the hydrated IL system with the widely used conventional method, it was discovered that the physicochemical and rheological characteristics of the alginate produced using the ILs as solvents were on par with those produced using the conventional method. The ILs can be seen as acceptable alternative solvents for the simple extraction of the polysaccharide straight from the seaweed given the consistency of the extraction procedure used in conventional extraction processes. The hydrated ILs were discovered to be more effective than their non-hydrated counterparts. The yield was also maximized up to 54%, which is much more than that obtained using a traditional approach. Moreover, the ionic liquids can also be recovered and reused for the extraction process. Additionally, any residual material remaining after the extraction process was converted into cellulose, making the process environmentally friendly and sustainable. [ABSTRACT FROM AUTHOR]

This study examines the behavior of single-walled carbon nanotubes (SWCNTs) suspended in a water-based ionic solution, driven by the combined mechanisms of electroosmosis and peristalsis through ciliated media. The inclusion of nanoparticles in ionic fluid expands the range of potential applications and allows for the tailoring of properties to suit specific needs. This interaction between ionic fluids and nanomaterials results in advancements in various fields, including energy storage, electronics, biomedical engineering, and environmental remediation. The analysis investigates the influence of a transverse magnetic field, thermal radiation, and mixed convection acting on the channel walls. The novel physical outcomes include enhanced propulsion efficiency due to SWCNTs, understanding the influence of thermal radiation on fluid behavior and heat exchange, elucidation of the interactions between SWCNTs and the nanofluid, and recognizing implications for microfluidics and biomedical engineering. The Poisson–Boltzmann ionic distribution is linearized using the modified Debye–Hückel approximation. By employing real-world approximations, the governing equations are simplified using long-wavelength and low-Reynolds-number approximation. Conducting sensitivity analyses or exploring the impact of higher-order corrections on the model's predictions in recent literature might alter the results significantly. This acknowledges the complexities of the modeling process and sets the groundwork for further enhancement and investigation. The resulting nonlinear system of equations is solved through regular perturbation techniques, and graphical representations showcase the variation in significant physical parameters. This study also discusses pumping and trapping phenomena in the context of relevant parameters. [ABSTRACT FROM AUTHOR]

Membrane fusion, merging two lipid bilayers, is crucial for fabricating artificial membrane structures. Over the past 40 years, in contrast to precise and controllable membrane fusion in-vivo through specific molecules such as SNAREs, controlling the fusion in-vitro while fabricating artificial membrane structures in physiological ionic solutions without fusion proteins has been a challenge, becoming a significant obstacle to practical applications. We present an approach consisting of an electric field and a few kPa hydraulic pressure as an additional variable to physically control the fusion, enabling tuning of the shape and size of the 3D freestanding lipid bilayers in physiological ionic solutions. Mechanical model analysis reveals that pressure-induced parallel/normal tensions enhance fusion among membranes in the microwell. In-vitro peptide-membrane assay, mimicking vesicular transport via pressure-assisted fusion, and stability of 38 days with in-chip pressure control via pore size-regulated hydrogel highlight the potential for diverse biological applications. Membrane fusion is crucial for fabricating artificial membranes. Here, the authors present an approach combining electric field with hydraulic pressure to physically control the fusion, enabling tuning of the shape and size of the 3D freestanding lipid bilayers in physiological solutions. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations were conducted on pure water and aqueous calciumand potassium chloride ternary solutions at different salts concentrations. To assess the local order within the solutions, the Monte Carlo simulations utilised the Madrid-2019 force field, usingtheTIP4P/2005 water model and scaled charges. The results demonstrate that as the salt concentrations increase, there is a notable decrease in the contribution of the structured tetrahedral arrangement of water molecules, favouring an unstructured configuration instead. The use of the nearest neighbour approach, provided unambiguous information regarding the radial and orientation characteristics of the unstructured configuration of water. Structures of the solvation shells around ions are also studied. The Monte Carlo simulations indicate that as the salt concentration increases, the hydration number around the cation decreases. This effect is likely due to the occasional substitution of some water molecules in the first hydration shell by chlorine ions. [ABSTRACT FROM AUTHOR]

The so‐called buoy‐effect, that is, the targeted surface enrichment of a Pt catalyst dissolved in ionic liquids (ILs), is achieved by attaching perfluorinated alkyl chains to the ligand system, which drags the metal complex toward the interface. Using angle‐resolved X‐ray photoelectron spectroscopy, it is demonstrated how this surface enrichment can be tailored by variation of the solvent IL. In [CnC1Im][PF6] ILs (n = 2, 4, 8), the surface is fully saturated with the complex at 10%mol bulk content, while in [C4C1Im][Tf2N] only at 20%mol saturation is observed. At low catalyst concentrations of 1%mol, where saturation is not yet reached, the enrichment increases with decreasing length of the IL alkyl chain. As a general rule, the degree of surface enrichment decreases with the decrease in surface tension of the solvent IL, that is, in the order [C2C1Im][PF6] > [C4C1Im][PF6] > [C8C1Im][PF6] > [C4C1Im][Tf2N]. In ILs with very low surface tension, enrichment is even suppressed. These results reveal the surface tension of the solvent IL as rational parameter for tailoring the interfacial structure of IL‐based catalyst systems, such as supported ionic liquid phase (SILP) catalysis, where the nature of the IL/gas interface is expected to strongly influence the performance of the process. [ABSTRACT FROM AUTHOR]

In recent years, hydrogel-based wearable flexible electronic devices have attracted much attention. However, hydrogel-based sensors are affected by structural fatigue, material aging, and water absorption and swelling, making stability and accuracy a major challenge. In this study, we present a DN-SPEZ dual-network hydrogel prepared using polyvinyl alcohol (PVA), sodium alginate (SA), ethylene glycol (EG), and ZnSO4 and propose a self-calibration compensation strategy. The strategy utilizes a metal salt solution to adjust the carrier concentration of the hydrogel to mitigate the resistance drift phenomenon to improve the stability and accuracy of hydrogel sensors in amphibious scenarios, such as land and water. The ExpGrow model was used to characterize the trend of the ∆R/R0 dynamic response curves of the hydrogels in the stress tests, and the average deviation of the fitted curves ϵ ¯ was calculated to quantify the stability differences of different groups. The results showed that the stability of the uncompensated group was much lower than that of the compensated group utilizing LiCl, NaCl, KCl, MgCl2, and AlCl3 solutions ( ϵ ¯ in the uncompensated group in air was 276.158, 1.888, 2.971, 30.586, and 13.561 times higher than that of the compensated group in LiCl, NaCl, KCl, MgCl2, and AlCl3, respectively; ϵ ¯ in the uncompensated group in seawater was 10.287 times, 1.008 times, 1.161 times, 4.986 times, 1.281 times, respectively, higher than that of the compensated group in LiCl, NaCl, KCl, MgCl2 and AlCl3). In addition, for the ranking of the compensation effect of different compensation solutions, the concentration of the compensation solution and the ionic radius and charge of the cation were found to be important factors in determining the compensation effect. Detection of events in amphibious environments such as swallowing, robotic arm grasping, Morse code, and finger–wrist bending was also performed in this study. This work provides a viable method for stability and accuracy enhancement of dual-network hydrogel sensors with strain and pressure sensing capabilities and offers solutions for sensor applications in both airborne and underwater amphibious environments. [ABSTRACT FROM AUTHOR]

A study of the liquid–liquid extraction of ReO4− anions from hydrochloric acid solutions using the ionic liquid Aliquat 336 (QCl: trialkyl(C8–C10)methylammonium chloride) via the well-known method of slope analysis along with the determination of the process parameters is presented. This study employs CCl4, CHCl3 and C6H12 as diluents. This study was carried out at room temperature (22 ± 2) °C and an aqueous/organic volumetric ratio of unity. The ligand effect on the complexation properties of ReO4− is quantitatively assessed in different organic media. The organic extract in chloroform media is examined through 1H, 13C and 15N NMR analysis as well as the HRMS technique and UV-Vis spectroscopy in order to view the anion exchange and ligand coordination in the organic phase solution. Final conclusions are given highlighting the role of the molecular diluent in complexation processes and selectivity involving ionic liquid ligands and various metal s-, p-, d- and f-cations. ReO4− ions have shown one of the best solvent extraction behaviors compared to other ions. For instance, the Aliquat 336 derivative bearing Cl− functions shows strongly enhanced extraction as well as pronounced separation abilities towards ReO4−. [ABSTRACT FROM AUTHOR]

This manuscript serves as the starting point for in-depth research of multicomponent, statistical, methacrylate-based copolymers that potentially mimic the behavior of proteins in aqueous solutions. These synthetic macromolecules are composed of specially chosen comonomers: methacrylic acid (MAA), oligoethylene glycol methyl ether methacrylate (OEGMA475), 2-(dimethylamino)ethyl methacrylate (DMAEMA) and benzyl methacrylate (BzMA). Monomer choice was based on factors such as the chemical nature of pendant functional groups, the polyelectrolyte/polyampholyte and amphiphilic character and the overall hydrophobic–hydrophilic balance (HLB) of the obtained quaterpolymers. Their synthesis was achieved via a one-pot reversible addition fragmentation chain transfer (RAFT) polymerization in two distinct compositions and molecular architectures, linear and hyperbranched, respectively, in order to explore the effects of macromolecular topology. The resulting statistical quaterpolymers were characterized via 1H-NMR and ATR-FTIR spectroscopies. Their behavior in aqueous solutions was studied by dynamic (DLS) and electrophoretic light scattering (ELS) and fluorescence spectroscopy (FS), producing vital information concerning their self-assembly and the structure of the formed aggregates. The physicochemical studies were extended by tuning parameters such as the solution pH and ionic strength. Finally, the quaterpolymer behavior in FBS/PBS solutions was investigated to test their colloid stability and biocompatibility in an in vivo-mimicking, biological fluid environment. [ABSTRACT FROM AUTHOR]

Soft robots claim the architecture of actuators, sensors, and computation demands with their soft bodies by obtaining fast responses and adapting to the environment. Sensory-motor coordination is one of the main design principles utilized for soft robots because it allows the capability to sense and actuate mutually in the environment, thereby achieving rapid response performance. This work intends to study the response for a system that presents coupled actuation and sensing functions simultaneously and is integrated in an arbitrary elastic structure with ionic conduction elements, called as soft sensory-motor system based on ionic solution (SSMS-IS). This study provides a comparative analysis of the performance of SSMS-IS prototypes with three diverse designs: toroidal, semi-toroidal, and rectangular geometries, based on a series of performance experiments, such as sensitivity, drift, and durability. The design with the best performance was the rectangular SSMS-IS using silicon rubber RPRO20 for both internal and external pressures applied in the system. Moreover, this work explores the performance of a bioinspired soft robot using rectangular SSMS-IS elements integrated in its body. Further, it investigated the feasibility of the robot to adapt its morphology online for environment variability, responding to external stimuli from the environment with different levels of stiffness and damping. [ABSTRACT FROM AUTHOR]

The existence of electrical potential in plant tissues has been studied for decades to understand its contribution toward the plants' health and developmental aspects. This potential is profoundly controlled and modulated by the electrokinetics involved in the flow navigated through the narrow conduits of a plant, which in turn is primarily governed by circadian rhythms. However, the interconnection between electrokinetics and the diurnal biological clock is yet to be understood. In this work, we unraveled the electrokinetics in response to the diurnal variations of a plant. Experiments conducted on water hyacinth stem indicate a cyclic variation of streaming potential synchronized with the changes introduced by circadian rhythm. In further efforts toward understanding the variation of streaming potential at different flow conditions, experiments were conducted on excised stem segments of Dracaena sanderiana, where the generated potential was studied against varying flow rates with different constitutive features of the flowing electrolyte. Notably, the resulting streaming potential from the flow of electrolytic solutions of different ionic strengths, species, and pH was found to align well with the fundamental premises of electrokinetics. These results are likely to expand our current knowledge of plant hydraulics by diligently examining the electrokinetics involved in the flow circuits of plants that undergo cyclic variations in close association with the circadian rhythms. [ABSTRACT FROM AUTHOR]

In this study, the spectrophotometric studies of aqueous ethanol solution of Congo red in various buffers solutions at room temperature 25oC and at different ionic strength of 0.05, 0.1, 0.3, and 0.5 KCl mol L-1 were investigated. The acidity constants of Congo red were estimated by three different methods. The two protonation stages were observed in pH range 2 - 4 and 4 - 6 as result as protonation of amino group and azo groups. The dependence of absorption spectra of Congo red on the ionic strength of solutions which exhibited blue shift with increases ionic strength in addition the shape and intensity were varied. Therefore, the acid-base equilibria shifted toward the higher pHs with the rise in ionic strength. Also, the acidity constants were affected by the ionic strength which the acidity constants decrease with increasing ionic strength of solution because the electrostatic interaction force increased. [ABSTRACT FROM AUTHOR]

The electric conductivity of ionic solutions is well understood at low ionic concentrations of up to a few millimolar but becomes difficult to unravel at higher concentrations that are still common in nature and technological applications. A model for the conductivity at high concentrations was recently put forth for monovalent electrolytes at low electric fields. The model relies on applying a stochastic density-functional theory and using a modified electrostatic pair-potential that suppresses unphysical, short-range electrostatic interactions. Here, we extend the theory to multivalent ions as well as to high electric fields where a deviation from Ohm's law known as the Wien effect occurs. Our results are in good agreement with experiments and recent simulations. [ABSTRACT FROM AUTHOR]

We have studied experimentally the electrical conductance–voltage curves of negatively and positively charged conical nanopores bathed in ionic solutions with monovalent, divalent, and trivalent cations at electrochemically and biologically relevant ionic concentrations. To better understand the interaction between the pore surface charge and the mobile ions, both single salts and salt mixtures have been considered. We have paid attention to the effects on the conductance of the cation valency, the pore charge asymmetry, and the pore charge inversion phenomena due to trivalent ions, both in single salts and salt mixtures. In addition, we have described how small concentrations of multivalent ions can tune the nanopore conductance due to monovalent majority ions, together with the effect of these charges on the additivity of ionic conductance and fluoride-induced negative differential conductance phenomena. This compilation and discussion of previously presented experimental data offers significant insights on the interaction between fixed and mobile charges confined in nanoscale volumes and should be useful in establishing and checking new models for describing ionic transport in the vicinity of charged surfaces. [ABSTRACT FROM AUTHOR]

Dynamic fluctuations in the hydrogen-bond network of water occur from femto- to nanosecond timescales and provide insight into the structural/dynamical aspects of water at ion–water interfaces. Employing terahertz spectroscopy assisted with molecular dynamics simulations, we study aqueous chloride solutions of five monovalent cations, namely, Li, Na, K, Rb, and Cs. We show that ions modify the behavior of the surrounding water molecules and form interfacial layers of water around them with physical properties distinct from those of bulk water. Small cations with high charge densities influence the kinetics of water well beyond the first solvation shell. At terahertz frequencies, we observe an emergence of fast relaxation processes of water with their magnitude following the ionic order Cs > Rb > K > Na > Li, revealing an enhanced population density of weakly coordinated water at the ion–water interface. The results shed light on the structure breaking tendency of monovalent cations and provide insight into the properties of ionic solutions at the molecular level. [ABSTRACT FROM AUTHOR]

Single‐stranded DNA oligonucleotides wrapping on the surface of single‐walled carbon nanotubes (SWCNTs), described as DNA corona, are often used as a dispersing agent for SWCNTs. The uneven distribution of DNA corona along SWCNTs is related to the photoelectric properties and the surface activity of SWCNTs. An ionic strength‐mediated "DNA corona defects" (DCDs) strategy is proposed to acquire an exposed surface of SWCNTs (accessible surface) as large as possible while maintaining good dispersibility via modulating the conformation of DNA corona. By adjusting the solution ionic strength, the DNA corona phase transitioned from an even‐distributed and loose conformation to a locally compact conformation. The resulting enlarged exposed surface of SWCNTs is called DCDs, which provide active sites for molecular adsorption. This strategy is applied for the arrangement of SWCNTs on DNA origami. SWCNTs with ≈11 nm DCD, providing enough space for the adsorption of "capture ssDNA" (≈7 nm width required for 24‐nt) extended from DNA origami structures are fabricated. The DCD strategy has potential applications in SWCNT‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Lack of safe water availability and access to clean water cause a higher risk of infectious diseases and other diseases as well. Heavy metals (HMs) are inorganic pollutants that cause severe threats to humans, animals, and the environment. Therefore, an effective HM removal technology is urgently needed. In the present study, a customized bipolar membrane electrodialysis process was used to remove HMs from aqueous solutions. The impacts of the feed ionic strength, applied electrical potential, and the type and concentration of HMs (Cd2+, Co2+, Cr3+, Cu2+, and Ni2+) on the process performance were investigated. The results showed that feed solution pH changes occurred in four stages: it first decreased linearly before stabilizing in the acidic pH range, followed by an increase and stabilization in the basic range of the pH scale. HM speciation in the basic pH range revealed the presence of anionic HM species. The presence of HMs on anion exchange membranes confirmed the contribution of these membranes for HM removal in the base channels of the process. While no clear trend was seen in the ionic strength solution, the maximum HM removal was observed when 1.5 g/L NaCl was used. The initial HM concentration showed a linear increase in HMs removal of up to 30 mg/L. A similar trend was seen with an increase in the applied electrical potential of up to 15 V. In general, the amount of HMs removed increased in the following order: Cd2+ ˃ Ni2+ ˃ Co2+ ˃ Cu2+ ˃ Cr3+. Under some operational conditions, however, the removed amount of Cu2+, Co2+, and Ni2+ was similar. The mass balance and SEM-EDX results revealed that the removed HMs were sorbed onto the membranes. In conclusion, this process efficiently separates HMs from aqueous solutions. It showed the features of diluate pH adjustment, reduction in the overall stack electrical resistance, and contribution of anion exchange membranes in multivalent cation removal. The mechanisms involved in HMs removal were diffusion and migration from the bulk solution, followed by their sorption on both cation and anion exchange membranes. [ABSTRACT FROM AUTHOR]

The reaction of carbonyl-to-imine/hemiaminal conversion in the atmospheric aqueous phase is a critical pathway to produce the light-absorbing N-containing secondary organic compounds (SOC). The formation mechanism of these compounds has been wildly investigated in bulk solutions with a low ionic strength. However, the ionic strength in the aqueous phase of the polluted atmosphere may be higher. It is still unclear whether and to what extent the inorganic ions can affect the SOC formation. Here we prepared the bulk solution with certain ionic strength, in which glyoxal and ammonium were mixed to mimic the aqueous-phase reaction. Molecular characterization by High-resolution Mass Spectrometry was performed to identify the N-containing products, and the light absorption of the mixtures was measured by ultraviolet-visible spectroscopy. Thirty-nine N-containing compounds were identified and divided into four categories (N-heterocyclic chromophores, high-molecular-weight compounds with N-heterocycle, aliphatic imines/hemiaminals, and the unclassified). It was observed that the longer reaction time and higher ionic strength led to the formation of more N-heterocyclic chromophores and the increasing of the light-absorbance of the mixture. The added inorganic ions were proposed to make the aqueous phase somewhat viscous so that the molecules were prone to undergo consecutive and intramolecular reactions to form the heterocycles. In general, this study revealed that the enhanced ionic strength and prolonged reaction time had the promotion effect on the light-absorbing SOC formation. It implies that the aldehyde-derived aqueous-phase SOC would contribute more light-absorbing particulate matter in the industrial or populated area where inorganic ions are abundant. [Display omitted] [ABSTRACT FROM AUTHOR]

A new hemicryptophane host with a ditopic molecular cavity combining a cyclotriveratrylene (CTV) unit with a tris‐urea moiety was synthesized. The complexation of halides, tetramethylammonium (TMA+) cation, and ion pairs was investigated. A positive cooperativity was observed, since halides display a higher binding constant when a TMA+ cation is already present inside the cage. When TMA+ was complexed alone, a decrease of temperature from 298 K to 230 K was required to switch from a fast to a slow exchange regime on the NMR time scale. Nevertheless, the prior complexation of a halide guest in the lower part of the host resulted in significant decrease of the exchange rate of the subsequent complexation of the TMA+ cation. Under these conditions, the 1H NMR signals characteristic of a slow exchange regime were observed at 298 K. Addition of an excess of salts, increases the ionic strength of the solution, restoring the fast exchange dynamics. This result provides insight on how the exchange rate of a cation guest can be modulated by the complexation of a co‐guest anion. [ABSTRACT FROM AUTHOR]

Bio-orthogonal chemistry provides a powerful tool for drug delivery systems due to its ability to generate therapeutic agents in situ, minimizing off-target effects. Bio-orthogonal transition metal catalysts (TMCs) with stimuli-responsive properties offer possibilities for controllable catalysis due to their spatial-, temporal-, and dosage-controllable properties. In this paper, we fabricated a stimuli-responsive bio-orthogonal catalysis system based on an enhanced green fluorescent protein (EGFP)–nanozyme (NZ) complex (EGFP-NZ). Regulation of the catalytic properties of the EGFP-NZ complex was directly achieved by modulating the ionic strength of the solution. The dielectric screening introduced by salt ions allows the dissociation of the EGFP-NZ complex, increasing the access of substrate to the active site of the NZs and concomitantly increasing nanozyme activity. The change in catalytic rate of the NZ/EGFP = 1:1 complex was positively correlated with salt concentration from 0 mM to 150 mM. [ABSTRACT FROM AUTHOR]

Nanofluidic diodes and ionic solutions find application in electrochemical circuits for information processing, controlled release, and signal conversion in hybrid devices. Here, we describe a physical model that accounts for the memory effects observed in conical nanopores in terms of the driving signal and ionic solution characteristics. The concepts invoked describe the device operation on the basis of the electrical interaction between the pore surface charges and the nanoconfined ionic solution. The physical insights provided can explain the experimental dependence of the nanofluidic tunability on the amplitude and frequency of the driving signal, the ionic concentration, and the solution pH. The model should also be useful for the design of electrochemical circuits based on ionic conduction in asymmetric memristors. [ABSTRACT FROM AUTHOR]

This document summarizes a study on the recovery of waste powder soap used in the wire drawing process. The study found that a physical separation method using ion solution was able to recover 98% of the sodium-based waste powder soap. The recovered material was analyzed using thermal and chemical analyses, which showed that the sodium content in the recycled soap was similar to that of the original soap. The study concluded that this recovery method was efficient and could be applied to different types of wires. The article emphasizes the importance of recycling processes for disposing of production-related waste in an environmentally friendly manner. [Extracted from the article]