Determination of the combined effect of grape seed extract and cold atmospheric plasma on foodborne pathogens and their environmental stress knockout mutants.

The study aimed to explore the antimicrobial efficacy of grape seed extract (GSE) and cold atmospheric plasma (CAP) individually or in combination against and wild type (WT) and their isogenic mutants in environmental stress genes. More specifically, we examined the effects of 1% (wt/vol) GSE, 4 min of CAP treatment, and their combined effect on 10403S WT and its isogenic mutants Δ, Δ, Δ, Δ as well as K12 and its isogenic mutants Δ, Δ, and Δ. In addition, the sequence of the combined treatments was tested.

On the evaluation of the antimicrobial effect of grape seed extract and cold atmospheric plasma on the dynamics of Listeria monocytogenes in novel multiphase 3D viscoelastic models.

The demand for products that are minimally processed and produced in a sustainable way, without the use of chemical preservatives or antibiotics have increased over the last years. Novel non-thermal technologies such as cold atmospheric plasma (CAP) and natural antimicrobials such as grape seed extract (GSE) are attractive alternatives to conventional food decontamination methods as they can meet the above demands. The aim of this study was to investigate the microbial inactivation potential of GSE, CAP (in this case, a remote air plasma with an ozone-dominated RONS output) and their combination against L.

A Systematic Quantitative Determination of the Antimicrobial Efficacy of Grape Seed Extract against Foodborne Bacterial Pathogens.

Concerns regarding the role of antimicrobial resistance (AMR) in disease outbreaks are growing due to the excessive use of antibiotics. Moreover, consumers are demanding food products that are minimally processed and produced in a sustainable way, without the use of chemical preservatives or antibiotics. Grape seed extract (GSE) is isolated from wine industry waste and is an interesting source of natural antimicrobials, especially when aiming to increase sustainable processing.

Optimisation of memory B cell expansion/differentiation for interrogation of rare peripheral memory B cell subset responses.

Human memory B cells play a vital role in the long-term protection of the host from pathogenic re-challenge. In recent years the importance of a number of different memory B cell subsets that can be formed in response to vaccination or infection has started to become clear. To study memory B cell responses, cells can be cultured allowing for an increase in cell number and activation of these quiescent cells, providing sufficient quantities of each memory subset to enable full investigation of functionality.

A new approach for the simulation of electrochemiluminescence (ECL).

The validity and accuracy of our new numerical approach implemented in KISSA-1D software when applied to a theoretical study of different types of electrochemiluminescence (ECL) is established by comparison with existing analytical solutions and others specifically derived in this work, as well as with independent numerical solutions obtained by using commercial software. The efficiency and comprehensiveness of this approach are illustrated by using a representative series of published ECL reaction schemes taken as typical case studies when ECL is generated by a single electrode under amperometric or voltammetric conditions, even when rate constants used in the simulations far exceed any of their realistic experimental limits.

Importance of correct prediction of initial concentrations in voltammetric scans: contrasting roles of thermodynamics, kinetics, and natural convection.

In order to successfully model an electrochemical reaction mechanism one must ensure that all the equations, including initial conditions, satisfy the pertinent thermodynamic and kinetic relationships. Failure to do so may lead to invalid results even if they are mathematically correct. This fact has been previously emphasized (Luo, W.

A novel approach to the simulation of electrochemical mechanisms involving acute reaction fronts at disk and band microelectrodes.

A new simulation algorithm is presented for describing the dynamics of diffusion reactions at the most common microelectrode 1D (planar, cylindrical, spherical) and 2D geometries (band, disk) for electrochemical mechanisms of any complexity and involving fast homogeneous reactions of any kind. A series of typical electrochemical mechanisms that create the most severe simulation difficulties is used to establish the exceptional performance and accuracy of this algorithm, which stem from the combination of (quasi)conformal transformation of space and a new method for auto-adaptive grid compression.

Capacitive and solution resistance effects on voltammetric responses at a disk microelectrode covered with a self-assembled monolayer in the presence of electron hopping.

This article extends our previous works (Amatore, C.; Oleinick, A.; Svir, I.

Electrochemical determination of flow velocity profile in a microfluidic channel from steady-state currents: numerical approach and optimization of electrode layout.

In this article, the numerical approach for flow profile reconstruction in a microfluidic channel equipped with band microelectrodes introduced previously by the authors, based on transient currents, is extended to the exclusive use of steady-state currents. It is shown that, although the currents obey steady state, the flow velocity profile in the channel may be reconstructed rapidly with a high accuracy, provided a sufficient number of electrodes performing under steady state are considered. The present theory demonstrates how the electrode widths and sizes of gaps separating them can be optimized to achieve better performance of the method.

Diffusion with moving boundary on spherical surfaces.

In this work, we illustrate two approaches to the simulation of surface diffusion over a sphere coupled with the formation of a cluster by reactive particles as a paradigm of a wide variety of problems occurring in many areas of nanosciences and biology. The problem is treated using a Brownian motion approach and a numerical solution of the corresponding continuous Fick's laws of diffusion. While being computationally more expensive, the Brownian motion approach allows one to consider a wider range of situations, particularly those corresponding to relatively high concentrations of diffusing particles and the ensuing problem of particle overlap when they are ascribed finite sizes.

Theory of long-range diffusion of proteins on a spherical biological membrane: application to protein cluster formation and actin-comet tail growth.

Breaking of symmetry is often required in biology in order to produce a specific function. In this work we address the problem of protein diffusion over a spherical vesicle surface towards one pole of the vesicle in order to produce ultimately an active protein cluster performing a specific biological function. Such a process is, for example, prerequisite for the assembling of proteins which then cooperatively catalyze the polymerization of actin monomers to sustain the growth of actin tails as occurs in natural vesicles such as those contained in Xenopus eggs.

Theory and simulation of diffusion-reaction into nano- and mesoporous structures. Experimental application to sequestration of mercury(II).

The complex problem of diffusion-reaction inside of bundles of nanopores assembled into microspherical particles is investigated theoretically based on the numerical solutions of the physicochemical equations that describe the kinetics and the thermodynamics of the phenomena taking place. These theoretical results enable the delineation of the main factors that control the system reactivity and examination of their thermodynamic and kinetic effects to afford quantitative predictions for the optimization of the particles' dimensional characteristics for a targeted application. The validity and usefulness of the theoretical approach disclosed here are established by the presentation of the complete analysis of the performance of thiol-functionalized microspheres aimed for sequestration of Hg(II) ions from solutions to be remediated.

In situ and on-line monitoring of hydrodynamic flow profiles in microfluidic channels based on microelectrochemistry: optimization of channel geometrical parameters for best performance of flow profile reconstruction.

A theoretical approach for flow profile reconstruction in a rectangular microfluidic channel equipped with one or two microband electrodes working in generator-collector and generator-generator regimes was proposed by us previously (ChemPhysChem 2005, 6, 1581-1589; ChemPhysChem 2006, 7, 482-487). The purpose of the current study is to determine the ranges of dimensionless parameters corresponding to the highest sensitivity of the minimized functional to the shape of the flow profile. By application of a cubic spline to approximate the flow profile and analysis of the least-squares functional, which can then be represented as a function of one variable, we derive the area of optimal method performance.

Time-dependent diffusion-migration at cylindrical and spherical microelectrodes: steady- and quasi-steady-state analytical solution can be used under transient conditions.

Mass transport at cylindrical and spherical microelectrodes involving diffusion and migration is analyzed by means of numerical simulation under transient conditions. The origin of the intrinsic difficulties encountered during the numerical solution of the diffusion-migration equations using implicit finite differences are outlined, especially for the particular case when the number of electrons transferred equals the charge number of the electroactive species. The numerical results for transient conditions have been compared to the general analytical solutions for the current enhancement or diminishment due to migration under steady- and quasi-steady-state conditions at 1D geometry microelectrodes (Amatore, C.

Confocal microscopy imaging of electrochemiluminescence at double band microelectrode assemblies: numerical solution of the inverse optical problem.

A realistic theoretical model describing the outcome of confocal microscopic imaging of electrochemiluminescence (ECL) light emission is derived for a two parallel band microelectrodes assembly operated under steady state. The model takes into account the experimental distortions ensuing from a) the specific finite shape of the sampling volume in confocal microscopy, b) the light arising directly from out-of-focus area but transmitted through the microscope diaphragm or c) transmitted after reflection from the polished platinum band electrodes. The model is based on a detailed optical, physico-mathematical and numerical analysis of the problem at hand, and on simulations of the concentration distribution of the species giving rise to the ECL generation.

Experimental and theoretical study of the surface-controlled dissolution of cylindrical particles. Application to solubilization of potassium hydrogen carbonate in hot dimethylformamide.

In this paper we present a mathematical model for the surface-controlled dissolution of cylindrical solid particles. This is employed to interpret experimental data published previously for the dissolution of potassium bicarbonate in dimethylformamide at elevated temperatures. Significant kinetic differences in assuming cylindrical rather than spherical shapes are reported with the former representing a closer approximation to the true shape of the particles as revealed by scanning electron microscopy.

Heterogeneous kinetics of the dissolution of an inorganic salt, potassium carbonate, in an organic solvent, dimethylformamide.

Understanding the mechanisms of solid-liquid systems is fundamental to the development and operation of processes for the production of agrochemicals and pharmaceuticals. The use of a strong inorganic base in an organic solvent, typically, potassium carbonate in dimethylformamide, is often used to facilitate the formation of a required anionic organic nucleophile. In this paper, the dissolution kinetics of potassium carbonate in dimethylformamide at elevated temperatures is studied in the presence of ultrasound, as revealed via monitoring of the deprotonation of 2-cyanophenol by dissolved K2CO3.

Reactions at the solid-liquid interface: surface-controlled dissolution of solid particles. The dissolution of potassium bicarbonate in dimethylformamide.

We present a mathematical model for the surface-controlled dissolution of solid particles. This is applied to the dissolution of a solid having different particle size distribution functions: those of a monodispersed solid containing particles of all one size, a two-size-particle distribution, and a Gaussian distribution of the particle sizes. The dissolution of potassium bicarbonate in dimethylformamide is experimentally studied indirectly at elevated temperatures.

Modelling release of nitric oxide in a slice of rat's brain: describing stimulated functional hyperemia with diffusion-reaction equations.

The physicochemical process of nitric oxide (NO degrees ) release from an active neuron is modelled based on the results obtained experimentally in independent series of experiments reported elsewhere in which the NO degrees release elicited by patch-clamping a single neuron (stellate neuron from cerebellum area) is monitored by an ultramicroelectrode introduced into a slice of living rat's brain. This process is believed to be central to brain behaviour by coupling neuronal activity with the blood supply to active areas of the living brain through precise control of NO degrees -mediated dilatation of blood capillary vessels. This work, based on the conformal mapping approach initially proposed in a previous work, aims to model the overall physicochemical and diffusional processes giving rise to the release of NO degrees by a neuron and during its collection at an electrode sensor.

Comparative solubilisation of potassium carbonate, sodium bicarbonate and sodium carbonate in hot dimethylformamide: application of cylindrical particle surface-controlled dissolution theory.

A surface-controlled dissolution of cylindrical solid particles model is applied to potassium carbonate, sodium bicarbonate and sodium carbonate in dimethylformamide at elevated temperatures. Previously published data for the dissolution of potassium carbonate is interpreted assuming a cylindrical rather than a spherical shape of the particles, the former representing a closer approximation to the true shape of the particles as revealed by scanning electron microscopy. The dissolution kinetics of sodium carbonate and sodium bicarbonate in dimethylformamide at 100 degrees C were investigated via monitoring of the deprotonation of 2-cyanophenol with dissolved solid to form the 2-cyanophenolate anion that was detected with UV-visible spectroscopy.

In situ and online monitoring of hydrodynamic flow profiles in microfluidic channels based upon microelectrochemistry: optimization of electrode locations.

Herein, we extend our previous approach concerning the reconstruction of profiles of pressure-driven hydrodynamic flow in microfluidic channels based on current measurements at band electrode(s) [see the preceding paper ChemPhysChem 2005, 6, 1581]. We address the central issue of optimization of geometrical parameters describing the electrode(s) assembly (a single band and two bands working in generator-collector mode) within the channel flow cell to enhance the speed and precision of the flow profile reconstruction method.

In situ and online monitoring of hydrodynamic flow profiles in microfluidic channels based upon microelectrochemistry: concept, theory, and validation.

Herein, we propose a method for reconstructing any plausible macroscopic hydrodynamic flow profile occurring locally within a rectangular microfluidic channel. The method is based on experimental currents measured at single or double microband electrodes embedded in one channel wall. A perfectly adequate quasiconformal mapping of spatial coordinates introduced in our previous work [Electrochem.

A comparative electrochemical study of diffusion in room temperature ionic liquid solvents versus acetonitrile.

Measurements on the diffusion coefficient of the neutral molecule N,N,N',N'-tetramethyl-para-phenylenediamine and the radical cation and dication generated by its one- and two-electron oxidation, respectively, are reported over the range 298-348 K in both acetonitrile and four room temperature ionic liquids (RTILs). Data were collected using single and double potential step chronoamperometry at a gold disk electrode of micrometer dimension, and analysed via fitting to the appropriate analytical expression or, where necessary, to simulation. The variation of diffusion coefficient with temperature was found to occur in an Arrhenius-type manner for all combinations of solute and solvent.

Marcus theory of outer-sphere heterogeneous electron transfer reactions: dependence of the standard electrochemical rate constant on the hydrodynamic radius from high precision measurements of the oxidation of anthracene and its derivatives in nonaqueous solvents using the high-speed channel electrode.

The validity of Marcus theory for outer-sphere heterogeneous electron transfer for the electro-oxidation of a range of anthracene derivatives in alkyl cyanide solvents is investigated. The precision measurement of these fast electron transfers (k(0) >or= 1 cm s(-1)) is achieved by use of the high-speed channel electrode and, where necessary, fast-scan cyclic voltammetry. First, the solvent effect on the rate of electron transfer is studied by considering the first oxidation wave of 9,10-diphenylanthracene in the alkyl cyanide solvents: acetonitrile, propionitrile, butyronitrile, and valeronitrile.