Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes.

Electrolytes are central to many technological applications, as well as life itself. The behavior and properties of electrolytes are often described in terms of ion pairs, whereby ions associate as either contact ion pairs (in which ions are "touching") solvent-separated ion pairs (in which ions' solvent shells overlap) or solvent-solvent-separated ion pairs (in which ions' solvent shells are distinct). However, this paradigm is generally restricted to statistically averaged descriptions of solution structure and ignores temporal behavior.

A first-principles alternative to empirical solvent parameters.

The use of solvents is ubiquitous in chemistry. Empirical parameters, such as the Kamlet-Taft parameters and Gutmann donor/acceptor numbers, have long been used to predict and quantify the effects solvents have on chemical phenomena. Collectively however, such parameters are unsatisfactory, since each describes ultimately the same non-covalent solute-solvent and solute-solute interactions in completely disparate ways.

Underscreening in concentrated electrolytes: re-entrant swelling in polyelectrolyte brushes.

Hypersaline environments are ubiquitous in nature and are found in myriad technological processes. Recent empirical studies have revealed a significant discrepancy between predicted and observed screening lengths at high salt concentrations, a phenomenon referred to as underscreening. Herein we investigate underscreening using a cationic polyelectrolyte brush as an exemplar.

Specific Ion Effects at the Vapor-Formamide Interface: A Reverse Hofmeister Series in Ion Concentration Depth Profiles.

Employing neutral impact collision ion scattering spectroscopy (NICISS), we have directly measured the concentration depth profiles (CDPs) of various monovalent ions at the vapor-formamide interface. NICISS provides CDPs of individual ions by measuring the energy loss of neutral helium atoms backscattered from the solution interface. CDPs at the vapor-formamide interface of Cl, Br, I, Na, K, and Cs are measured and compared to elucidate the interfacial specific ion trends.

COVID-19 and Lung Cavitation: A Clue to Pathogenesis?

Description Lung cavitation as a complication of COVID-19 is rare. A 56-year-old male presented with lung cavitation, small volume hemoptysis, and violaceous discoloration of the right great toe, 5 weeks after diagnosis with COVID-19 pneumonia. The digital changes were consistent with previously described microvascular changes called "COVID toe.

Quantitative Solvation Energies from Gas-Phase Calculations: First-Principles Charge Transfer and Perturbation Approaches.

We present a first-principles approach for the calculation of solvation energies and enthalpies with respect to different ion pair combinations in various solvents. The method relies on the conceptual density functional theory (DFT) of solvation, from which detailed expressions for the solvation energies can be derived. In addition to fast and straightforward gas phase calculations, we also study the influence of modified chemical reactivity descriptors in terms of electronic perturbations.

From Hofmeister to hydrotrope: Effect of anion hydrocarbon chain length on a polymer brush.

Hypothesis: Specific ion effects govern myriad biological phenomena, including protein-ligand interactions and enzyme activity. Despite recent advances, detailed understanding of the role of ion hydrophobicity in specific ion effects, and the intersection with hydrotropic effects, remains elusive. Short chain fatty acid sodium salts are simple amphiphiles which play an integral role in our gastrointestinal health.

Ion specificity in the measured concentration depth profile of ions at the Vapor-Glycerol interface.

Hypothesis: Specific ion effects are manifest universally across many systems and solvents. Whilst broad understanding of these effects is emerging particularly for bulk effects, the perturbation introduced by the interfaces are generally not understood. We hypothesise that through a careful investigation of the distribution of ions at the glycerol-vapor interface we can better understand specific ion effects in this system and at interfaces.

Understanding specific ion effects and the Hofmeister series.

Specific ion effects (SIE), encompassing the Hofmeister Series, have been known for more than 130 years since Hofmeister and Lewith's foundational work. SIEs are ubiquitous and are observed across the medical, biological, chemical and industrial sciences. Nevertheless, no general predictive theory has yet been able to explain ion specificity across these fields; it remains impossible to predict when, how, and to what magnitude, a SIE will be observed.

Colloidal Systems in Concentrated Electrolyte Solutions Exhibit Re-entrant Long-Range Electrostatic Interactions due to Underscreening.

Surface force measurements have revealed that at very high electrolyte concentrations as well as in neat and diluted ionic liquids and deep eutectic solvents, the range of electrostatic interactions is far greater than the Debye length. Here, we explore the consequences of this underscreening for soft-matter and colloidal systems by investigating the stability of nanoparticle dispersions, the self-assembly of ionic surfactants, and the thickness of soap films. In each case, we find clear evidence of re-entrant properties due to underscreening at high salt concentrations.

Hyperspectral time series datasets of maize during the grain filling period.

Objectives: Remotely sensed hyperspectral data are increasingly being used to assess crop development and growth throughout the growing season. Large datasets capturing key growth stages can be useful to researchers studying many physiological plant responses. A time series analysis of hyperspectral reflectance measurements taken during the grain filling period and published within a publicly accessible database are described herein.

The electrostatic origins of specific ion effects: quantifying the Hofmeister series for anions.

Life as we know it is dependent upon water, or more specifically salty water. Without dissolved ions, the interactions between biological molecules are insufficiently complex to support life. This complexity is intimately tied to the variation in properties induced by the presence of different ions.

Artificial neural networks for the prediction of solvation energies based on experimental and computational data.

The knowledge of thermodynamic properties for novel electrolyte formulations is of fundamental interest for industrial applications as well as academic research. Herewith, we present an artificial neural networks (ANN) approach for the prediction of solvation energies and entropies for distinct ion pairs in various protic and aprotic solvents. The considered feed-forward ANN is trained either by experimental data or computational results from conceptual density functional theory calculations.

Re-entrant swelling and redissolution of polyelectrolytes arises from an increased electrostatic decay length at high salt concentrations.

Hypothesis: A detailed understanding of the influence of electrolytes on the conformation of polyelectrolyte chains is an important goal made challenging by the strong coupling between electrostatic interactions and chain conformation. This challenge is particularly evident at moderate to high salt concentrations where mean-field theories of electrolytes are no longer applicable and are therefore unable to predict the interactions between neutral or like charged surfaces that leads to re-entrant swelling of DNA and other polyelectrolytes at high salt concentrations. Recent developments arising from studies of surface forces in ionic liquids that have been extended to include a wide variety of monovalent electrolytes reveal a hitherto unknown increase in the electrostatic decay length at high electrolyte concentrations.

Lifestyle information and commercial weight management groups to support maternal postnatal weight management and positive lifestyle behaviour: the SWAN feasibility randomised controlled trial.

Objectives: To assess feasibility of a future randomised controlled trial (RCT) of clinical and cost-effectiveness of lifestyle information and commercial weight management groups to support postnatal weight management to 12 months post-birth.

Design: Two-arm feasibility trial, with nested mixed-methods process evaluation.

Setting: Inner-city unit, south England.

Protocol for a two-arm feasibility RCT to support postnatal maternal weight management and positive lifestyle behaviour in women from an ethnically diverse inner city population: the SWAN feasibility trial.

Introduction: A high BMI during and after pregnancy is linked to poor pregnancy outcomes and contributes to long-term maternal obesity, hypertension, and diabetes. Evidence of feasible, effective postnatal interventions is lacking. This randomised controlled trial will assess the feasibility of conducting a future definitive trial to determine effectiveness and cost-effectiveness of lifestyle information and access to Slimming World® (Alfreton, UK) groups for 12 weeks commencing from 8 to 16 weeks postnatally, in relation to supporting longer-term postnatal weight management in women in an ethnically diverse inner city population.

Forces between zinc sulphide surfaces; amplification of the hydrophobic attraction by surface charge.

Smooth Zinc Sulphide (ZnS) surfaces were prepared by magnetron sputtering and the interaction forces were measured between them as a function of pH. At the isoelectric point (iep) of pH 7.1 the attractive force was well described by the van der Waals interaction calculated using Lifshitz theory for a layered system.

Does gas supersaturation by a chemical reaction produce bulk nanobubbles?

Hypothesis: Supersaturation of dissolved gas is the most commonly reported method for generating long-lived bulk nanobubbles. However, these reports are treated with skepticism because of the lack of techniques that directly show that these particles are gas filled bubbles. Therefore, this work has tested the hypothesis that supersaturation obtained by a chemical reaction produces long-lived nanosized bubbles in bulk using an established protocol that relies on evaluating the density of nanoparticles and measuring their response to external pressure.

Interaction of Particles with Surfactant Thin Films: Implications for Dust Suppression.

Understanding the interaction of particles with foams is important in antifoaming applications and dust suppression. In the former, the aim is for the particles to break the foam, whereas in the latter it is desirable that the stability of the foam is maintained or enhanced. The interaction of particles of different wettabilities with thin surfactant films is investigated with a Sheludko cell, enabling the thinning and rupture of the films to be studied in the presence and absence of a particle, using white-light interferometry.

Correction: What is the fundamental ion-specific series for anions and cations? Ion specificity in standard partial molar volumes of electrolytes and electrostriction in water and non-aqueous solvents.

[This corrects the article DOI: 10.1039/C7SC02691A.].

Generation of nanoparticles upon mixing ethanol and water; Nanobubbles or Not?

Hypothesis: The debate as to whether nanoparticles that are formed upon mixing ethanol and water are nanobubbles or other nanoparticles has continued over the past decade. In this work, we test the hypothesis that long lived bulk nanobubbles are produced upon mixing ethanol and water, using techniques that probe the density and the pressure response of the nanoparticles.

Experiments: Nanoparticles were generated spontaneously upon mixing high-purity ethanol and high-purity water.

Long-Term Stability of Surface Nanobubbles in Undersaturated Aqueous Solution.

Surface nanobubbles should not be stable for more than a few milliseconds; however they have been shown to persist for days. Pinning of the three-phase contact line of surface nanobubbles has been proposed to explain the discrepancy between the theoretical and experimental results. According to this model, two factors stabilize surface nanobubbles, namely solution oversaturation and surface pinning.

Armoured nanobubbles; ultrasound contrast agents under pressure.

Hypothesis: Robust methods for differentiating long-lived nanobubbles from other nanoparticles are required. Evaluation of the density and compressibility of nanoparticles should enable nanobubbles to be differentiated from other nanoparticles, although the response of nanobubbles to pressure can be strongly influenced by a coating of insoluble surfactant. Here we evaluate the response of nanobubbles armoured with a coating of insoluble surfactants in order to determine if they can be differentiated from other nanoparticles.

Volcano Plots Emerge from a Sea of Nonaqueous Solvents: The Law of Matching Water Affinities Extends to All Solvents.

The properties of all electrolyte solutions, whether the solvent is aqueous or nonaqueous, are strongly dependent on the nature of the ions in solution. The consequences of these specific-ion effects are significant and manifest from biochemistry to battery technology. The "law of matching water affinities" (LMWA) has proven to be a powerful concept for understanding and predicting specific-ion effects in a wide range of systems, including the stability of proteins and colloids, solubility, the behavior of lipids, surfactants, and polyelectrolytes, and catalysis in water and ionic liquids.