Electrochemical study on the effect of polar and non-polar extract of Artemisia vulgaris on the corrosion inhibition of mild-steel in an acidic medium.

Electrochemical methods were used to characterize the inhibition efficacy of the extract of the high-altitude plant Artemisia vulgaris as an environmentally acceptable inhibitor for mild steel in 1.0 M H2SO4. The Artemisia vulgaris was extracted in hexane and methanol separately and applied on mild steel (MS) as an inhibitor. A detailed electrochemical characterization such as potentiodynamic polarization, open circuit potential, and electrochemical impedance spectroscopy (EIS) was performed on the MS surface covered with the extract molecules. The hexane extracts adsorbed slower to the MS surface than the methanol extract, but both molecular extracts showed similar corrosion inhibition efficacies (IE). The IE for 1000 ppm extract in hexane and methanol was 73.10% and 91.99%, respectively, after 0.5 hour immersion of MS, whereas it was 98.79% and 96.73% in hexane and methanol extract after 24 hours of immersion of MS in acidic medium. The IE of the methanol extract increased with concentration. From the EIS analytical analysis, adsorption of inhibitor molecules on the charge transfer kinetics was confirmed. The potentiodynamic polarization showed a decrease in current density with the concentration of methanol extract without affecting the Tafel slopes. ATR-FTIR of the extract indicated the presence of the different functionalities in it. Adsorption of the extract molecules on the metal surface obeyed the Langmuir adsorption isotherm. The computed value of ΔG* implies that the adsorption is of mixed type. The formation of a protective film of inhibitor molecules on the MS surface was confirmed from EIS and using a scanning electron microscope. The adsorption mechanism based on the experimental data supported by the thermodynamic calculations is highlighted in this article.

Trace level monitoring of Cu(II) ion using CuS particles based membrane electrochemical sensor.

Cu(II) monitoring is a matter of great interest to researchers due to its toxicity and adverse environmental effects. Among different methods for detecting Cu(II), ion-selective electrode (ISE) is more advantageous as they are low-cost, easy to fabricate, and highly selective. Here, we report a simple, inexpensive, and reproducible procedure for the fabrication of Cu(II) ion-selective electrodes using CuS particles and polyvinyl chloride (PVC) as a matrix. CuS particles, obtained by chemical precipitation, were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), and energy-dispersive X-Ray spectroscopy (EDX). Optimization of the membrane compositions was done to get a well-behaved sensor by varying amounts of CuS, PVC, and acetophenone (AP). A membrane composition of 0.4 g CuS, 0.5 g PVC, and 1.0 mL AP in 5.0 mL tetrahydrofuran (THF) gave a Nernstian slope of 27.31 mV per decade change of Cu(II) ion over a wide range of concentration down to 64 ppb (1 × 10-6 M). The sensor gave a fast response time of 25 s, and it indicated the endpoint in a potentiometric titration of Cu(II) with standard EDTA solution. A pH-independent potential response was obtained in the pH 4.0-6.0.

Asymmetric Lipid Transfer between Zwitterionic Vesicles by Nanoviscosity Measurements.

The interest in nano-sized lipid vesicles in nano-biotechnology relies on their use as mimics for endosomes, exosomes, and nanocarriers for drug delivery. The interactions between nanoscale size lipid vesicles and cell membranes involve spontaneous interbilayer lipid transfer by several mechanisms, such as monomer transfer or hemifusion. Experimental approaches toward monitoring lipid transfer between nanoscale-sized vesicles typically consist of transfer assays by fluorescence microscopy requiring the use of labels or calorimetric measurements, which in turn require a large amount of sample. Here, the capability of a label-free surface-sensitive method, quartz crystal microbalance with dissipation monitoring (QCM-D), was used to monitor lipid transfer kinetics at minimal concentrations and to elucidate how lipid physicochemical properties influence the nature of the transfer mechanism and dictate its dynamics. By studying time-dependent phase transitions obtained from nanoviscosity measurements, the transfer rates (unidirectional or bidirectional) between two vesicle populations consisting of lipids with the same head group and differing alkyl chain length can be estimated. Lipid transfer is asymmetric and unidirectional from shorter-chain lipid donor vesicles to longer-chain lipid acceptor vesicles. The transfer is dramatically reduced when the vesicle populations are incubated at temperatures below the melting of one of the vesicle populations.

Dataset for the selection of electrolytes for Electropolymerization of aniline.

The most investigated conducting polymer (CP) is polyaniline (PANI)), a promising polymer due to its excellent environmental stability, simplicity of synthesis, and high electrical conductivity [1], [2], [3], [4]. In corrosion protection applications, the PANI film has shown promising potential in protecting active metals such as iron by acting as physical barrier coatings, as a primer layer and as component in a multi-layer coating system [5]. The PANI has an excellent potential to replace the toxic metal, such as chromates, in corrosion protection and is considered a green anti-corrosion candidate [5], [6], [7]. The electrochemical synthesis of PANI coatings on active metals is accomplished by the dissolution of the metal at a potential lower than the monomer oxidation potential [8], [9]. Therefore, electrochemical synthesis of PANI coatings on active metal requires a proper choice of the electrolyte and solvent that should strongly passivate the metal without hindering the electropolymerization process [10], [11]. The data reported here are obtained while the anodic polarization of mild steel (MS) is carried out in succinic acid, sulphanilic acid, sodium orthophosphate, sodium potassium tartrate (Na-K tartrate), and benzoic acid in 3:1 alcohol-water (BAW) solutions [11]. However, the results of electrolytes sodium-potassium tartrate (Na-K tartrate) and benzoic acid in alcohol-water (BAW) are reported for the polymerization of aniline onto MS [11]. The SEM image of MS sample polarized in 0.3 M oxalic acid solution and 0.1 M aniline in 0.3 M oxalic acid is reported as a dataset or a supplementary material of the main manuscript 'The Effect of Electrolytes on the Coating of Polyaniline on Mild Steel by Electrochemical Methods and Its Corrosion Behaviour [11].'

Real-Time Monitoring of Interactions between Solid-Supported Lipid Vesicle Layers and Short- and Medium-Chain Length Alcohols: Ethanol and 1-Pentanol.

Lipid bilayers represent the interface between the cell and its environment, serving as model systems for the study of various biological processes. For instance, the addition of small molecules such as alcohols is a well-known process that modulates lipid bilayer properties, being considered as a reference for general anesthetic molecules. A plethora of experimental and simulation studies have focused on alcohol's effect on lipid bilayers. Nevertheless, most studies have focused on lipid membranes formed in the presence of alcohols, while the effect of n-alcohols on preformed lipid membranes has received much less research interest. Here, we monitor the real-time interaction of short-chain alcohols with solid-supported vesicles of dipalmitoylphosphatidylcholine (DPPC) using quartz crystal microbalance with dissipation monitoring (QCM-D) as a label-free method. Results indicate that the addition of ethanol at different concentrations induces changes in the bilayer organization but preserves the stability of the supported vesicle layer. In turn, the addition of 1-pentanol induces not only changes in the bilayer organization, but also promotes vesicle rupture and inhomogeneous lipid layers at very high concentrations.

Ionic strength dependent vesicle adsorption and phase behavior of anionic phospholipids on a gold substrate.

The authors report on the effect of ionic strength on the formation of supported vesicle layers of anionic phospholipids 1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol (DMPG) and dimyristoylphosphatidylserine (DMPS) onto gold. Using quartz crystal microbalance with dissipation monitoring the authors show that vesicle adsorption is mainly governed by NaCl concentration, reflecting the importance of electrostatic interactions in anionic lipids, as compared to zwitterionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine. At low ionic strength, low or no adsorption is observed as a result of vesicle-vesicle electrostatic repulsion. At medium ionic strength, the negative charges of DMPG and DMPS are screened resulting in larger adsorption and a highly dissipative intact vesicle layer. In addition, DMPS exhibits a peculiar behavior at high ionic strength that depends on the temperature of the process.