Statistical Analysis of the Measurement Noise in Dynamic Impedance Spectra.

Different strategies can be used to acquire dynamic impedance spectra during a cyclic voltammetry experiment. The spectra are then analyzed by fitting them with a model using a weighted non-linear least-squares minimization algorithm. The choice of the weighting factors is not trivial and influences the value of the extracted parameters.

Thermally Regenerable Redox Flow Battery.

The efficient production of energy from low-temperature heat sources (below 100 °C) would open the doors to the exploitation of a huge amount of heat sources such as solar, geothermal, and industrial waste heat. Thermal regenerable redox-flow batteries (TRBs) are flow batteries that store energy in concentration cells that can be recharged by distillation at temperature <100 °C, exploiting low-temperature heat sources. Using a single membrane cell setup and a suitable redox couple (LiBr/Br ), a TRB has been developed that is able to store a maximum volumetric energy of 25.

Electrochemical Methods for Lithium Recovery: A Comprehensive and Critical Review.

Due to the ubiquitous presence of lithium-ion batteries in portable applications, and their implementation in the transportation and large-scale energy sectors, the future cost and availability of lithium is currently under debate. Lithium demand is expected to grow in the near future, up to 900 ktons per year in 2025. Lithium utilization would depend on a strong increase in production.

Dynamic Impedance Spectroscopy of Nickel Hexacyanoferrate Thin Films.

Dynamic multi-frequency analysis (DMFA) is capable of acquiring high-quality frequency response of electrochemical systems under non-stationary conditions in a broad range of frequencies. In this work, we used DMFA to study the kinetics of (de-)intercalation of univalent cations (Na and K) in thin films of nickel hexacyanoferrate (NiHCF) during cyclic voltammetry. For this system, the classic stationary electrochemical impedance spectroscopy fails due to the instability of the oxidized form of NiHCF.

Cylindrical flowing-junction cell for the investigation of fluctuations and pattern-formation in miscible fluids.

We describe a flowing-junction cell with cylindrical symmetry suitable to investigate fluctuations and pattern formation at the diffusing interface between two miscible phases of a liquid mixture. The continuous outflow of the remixed fluid through a thin slit located at the midheight of the sample allows the preparation of an initially sharp interface. The system can be used in both gravity-stable and unstable conditions.

Asymmetric time-cross-correlation of nonequilibrium concentration fluctuations in a ternary liquid mixture.

Equilibrium phenomena are characterized by time symmetry. Thermodynamic fluctuations are also time-symmetric at equilibrium. Conversely, diffusion of a solute in a liquid in the presence of a gradient is a nonequilibrium phenomenon, which gives rise to long-range fluctuations with amplitude much larger than the equilibrium one for small enough wave number.

Space-Charge Effects at the LiLaZrO/Poly(ethylene oxide) Interface.

Composites consisting of garnet-type LiLaZrO (LLZO) ceramic particles dispersed in a solid polymer electrolyte based on poly(ethylene oxide) (PEO) have recently been investigated as a possible electrolyte material in all solid state Li ion batteries. The interface between the two materials, that is, LLZO/PEO, is of special interest for the transport of lithium ions in the composite. For obtaining the desired high ionic conductivity, Li ions have to pass easily across this interface.

Nonequilibrium fluctuations during diffusion in liquid layers.

Theoretical analysis and experiments have provided compelling evidence of the presence of long-range nonequilibrium concentration fluctuations during diffusion processes in fluids. In this paper, we investigate the dependence of the features of the fluctuations from the dimensionality of the system. In three-dimensional fluids the amplitude of nonequilibrium fluctuations can become several orders of magnitude larger than that of equilibrium fluctuations.

Intercalation into a Prussian Blue Derivative from Solutions Containing Two Species of Cations.

Reversible mixed-ion intercalation in nonselective host structures has promising applications in desalination, mixed-ion batteries, wastewater treatment, and lithium recovery through electrochemical ion pumping. One class of host compound that possesses many of the requirements needed for such applications (cost effectiveness, fast ion kinetics, and stability in an aqueous medium) includes the Prussian blue derivatives. Herein, the fundamental process of intercalation of multiple cations is studied at the thermodynamic level by means of galvanostatic cycling.

Salinity Gradients for Sustainable Energy: Primer, Progress, and Prospects.

Combining two solutions of different composition releases the Gibbs free energy of mixing. By using engineered processes to control the mixing, chemical energy stored in salinity gradients can be harnessed for useful work. In this critical review, we present an overview of the current progress in salinity gradient power generation, discuss the prospects and challenges of the foremost technologies - pressure retarded osmosis (PRO), reverse electrodialysis (RED), and capacitive mixing (CapMix) and provide perspectives on the outlook of salinity gradient power generation.

Correlations and scaling properties of nonequilibrium fluctuations in liquid mixtures.

Diffusion in liquids is accompanied by nonequilibrium concentration fluctuations spanning all the length scales comprised between the microscopic scale a and the macroscopic size of the system, L. Up to now, theoretical and experimental investigations of nonequilibrium fluctuations have focused mostly on determining their mean-square amplitude as a function of the wave vector. In this work, we investigate the local properties of nonequilibrium fluctuations arising during a stationary diffusion process occurring in a binary liquid mixture in the presence of a uniform concentration gradient, ∇c_{0}.

Capacitive mixing with electrodes of the same kind for energy production from salinity differences.

The capacitive mixing technique is aimed at producing renewable energy from salinity differences, for example between sea and river water. The technique makes use of two electrodes that modify their potential in opposite directions when the concentration of the solution in which they are immersed is changed, as a consequence of the dynamics of the electric double layer which forms in the ionic solution. Unfortunately, it is difficult to find two electrodes presenting both optimal performances and opposite potential variations.

Fluorimetric detection of the earliest events in amyloid β oligomerization and its inhibition by pharmacologically active liposomes.

Background: Amyloid β (Aβ) peptide aggregation is the main molecular mechanism underlying the development of Alzheimer's disease, the most widespread form of senile dementia worldwide. Increasing evidence suggests that the key factor leading to impaired neuronal function is accumulation of water-soluble Aβ oligomers rather than formation of the senile plaques created by the deposition of large fibrillary aggregates of Aβ. However, several questions remain about the preliminary steps and the progression of Aβ oligomerization.

Polyelectrolyte-coated carbons used in the generation of blue energy from salinity differences.

In this work we present a method for the production of clean, renewable electrical energy from the exchange of solutions with different salinities. Activated carbon films are coated with negatively or positively charged polyelectrolytes using well-established adsorption methods. When two oppositely charged coated films are placed in contact with an ionic solution, the potential difference between them will be equal to the difference between their Donnan potentials, and hence, energy can be extracted by building an electrochemical cell with such electrodes.

Modification of the surface of activated carbon electrodes for capacitive mixing energy extraction from salinity differences.

The "capacitive mixing" (CAPMIX) is one of the techniques aimed at the extraction of energy from the salinity difference between sea and rivers. It is based on the rise of the voltage between two electrodes, taking place when the salt concentration of the solution in which they are dipped is changed. We study the rise of the potential of activated carbon electrodes in NaCl solutions, as a function of their charging state.

Violation of the mass-action law in dilute chemical systems.

The mass-action law, which predicts the rates of chemical reactions, is widely used for modeling the kinetics of the chemical reactions and their stationary states, also for complex chemical reaction networks. However, violations of the mass-action equations have been reported in various cases: in confined systems with a small number of molecules, in non-ideally-stirred systems, when the reactions are limited by the diffusion, at high concentrations of reactants, or in chemical reaction networks with marginally stable mass-action equations. In this paper, I describe a new mechanism, leading to the violation of the mass-action equations, that takes place at a low concentration of at least one of the reactants; in this limit, the reaction rates can be easily inferred from the chemical reaction network.

Capacitive mixing for the extraction of energy from salinity differences: survey of experimental results and electrochemical models.

The "capacitive mixing" (CAPMIX) technique is an emerging technology aimed at the extraction of energy from salinity differences, e.g. between sea and river waters.

Magnetic tweezers measurements of the nanomechanical stability of DNA against denaturation at various conditions of pH and ionic strength.

The opening of DNA double strands is extremely relevant to several biological functions, such as replication and transcription or binding of specific proteins. Such opening phenomenon is particularly sensitive to the aqueous solvent conditions in which the DNA molecule is dispersed, as it can be observed by considering the classical dependence of DNA melting temperature on pH and salt concentration. In the present work, we report a single-molecule study of the stability of DNA against denaturation when subjected to changes in solvent.

Looking for chemical reaction networks exhibiting a drift along a manifold of marginally stable states.

I recently reported some examples of mass-action equations that have a continuous manifold of marginally stable stationary states [Brogioli, D., 2010. Marginally stable chemical systems as precursors of life.

Biophysical characterization of a binding site for TLQP-21, a naturally occurring peptide which induces resistance to obesity.

Recently, we demonstrated that TLQP-21 triggers lipolysis and induces resistance to obesity by reducing fat accumulation [1]. TLQP-21 is a 21 amino acid peptide cleavage product of the neuroprotein VGF and was first identified in rat brain. Although TLQP-21 biological activity and its molecular signaling is under active investigation, a receptor for TLQP-21 has not yet been characterized.

Thermodynamic relation between voltage-concentration dependence and salt adsorption in electrochemical cells.

Electrochemical cells containing two electrodes dipped in an ionic solution are widely used as charge accumulators, either with polarizable (supercapacitor) or nonpolarizable (battery) electrodes. Recent applications include desalination ("capacitive deionization") and energy extraction from salinity differences ("capacitive mixing"). In this Letter, we analyze a general relation between the variation of the electric potential as a function of the concentration and the salt adsorption.

Single-molecule study of the DNA denaturation phase transition in the force-torsion space.

We use the "magnetic tweezers" technique to show the structural transitions that the DNA undergoes in the force-torsion space. In particular, we focus on the regions corresponding to negative supercoiling. These regions are characterized by the formation of the so-called denaturation bubbles, which play an essential role in the replication and transcription of DNA.

Ions Transport and Adsorption Mechanisms in Porous Electrodes During Capacitive-Mixing Double Layer Expansion (CDLE).

A model of the electro-diffusion of ions in porous electrodes is applied to analyze the dynamics of capacitive-mixing extraction of energy from salinity gradients with carbon porous electrodes. The complex time-evolution of the cell voltage observed in experiments is satisfactorily described. The asymmetry on the duration of the solution-change steps performed in open circuit is found to be due to the nonlinear voltage-concentration relationship of the electric double layers and to a current that redistributes the counterions along the depth of the electrode leading to nonuniform charge and salt adsorption.

Photon correlation spectroscopy with incoherent light.

Photon correlation spectroscopy (PCS) is based on measuring the temporal correlation of the light intensity scattered by the investigated sample. A typical setup requires a temporally coherent light source. Here, we show that a short-coherence light source can be used as well, provided that its coherence properties are suitably modified.

Marginal stability in chemical systems and its relevance in the origin of life.

Concentration fluctuations are always present in solutions; it has been noticed that, in chemical systems, they can lead to deviations from what is expected from mass-action equations. I recently described the class of the "marginally stable" chemical systems; namely, a system that have an infinity of stationary states forming a continuous curve, and I showed that they present such deviations, which appear as a drift along the stationary-state curve [Phys. Rev.