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The purpose of this work is to explore electrical properties of an electrochemical sensor designed for the detection of malachite green (MG) present in an aqueous solution.

The present sensor consists in the spatial coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of an ionophore (D2HPA), a polymer (polyvinylchloride [PVC]) and a plasticizer (dioctyl phthalate [DOP]). Several techniques have been used to characterize this sensor: the cyclic voltammetry, the electrochemical impedance spectroscopy and the optical microscopy. The sensibility, the selectivity and the kinetic study of a modified platinum electrode have been evaluated by cyclic voltammetry.

The obtained results reveal the possibility of a linear relationship between the current of reduction peaks and MG concentration. A linear response was obtained in a wide-concentration range that stretches from 10⁻⁵ to 10⁻¹³ mol L⁻¹, with a good correlation coefficient (0.976) and a good detection limit of 5.74 × 10⁻¹⁴ mol L⁻¹ (a signal-to-noise ratio of 3). In addition, the voltammetric response of modified electrode can be enhanced by adding a layer of Nafion membrane. Under this optimal condition, a linear relationship was obtained, with a correlation coefficient of 0.986 and a detection limit of 1.92 × 10⁻¹⁸ mol L⁻¹.

In the present research, a convenient, inexpensive and reproducible method for the detection of MG was developed. The developed sensor is capable of competing against the conventional techniques in terms of speed, stability and economy.

A new electrochemical analysis based on ß-cyclodextrin (ß-CD) was developed for penicillin V (Peni-V) using polyaniline as a conducting polymer.

The preparation of modified electrode involves the incorporation of β-CD with membrane of polyaniline. Polyaniline, incorporating β-CD, was prepared by electrochemical polymerization method in a medium of hypochloride. Cyclic voltammetry and electrochemical impedance have been used to characterize this sensor. The detection and the kinetic study of modified platinum electrode are evaluated.

Results clearly indicate that β-CDs interfere with the polymerization mechanism with an inhibition factor. The inclusion phenomenon of β-CDs has been studied and applied to detect Peni-V. The principle of this electrochemical sensor is based on the chemical properties of β-CD, which were studied using the cyclic voltammetric method and impedance spectroscopy. The electrochemical behavior of Peni-V at concentrations between 10^–8 and 10^–2 M was measured versus Ag/AgCl at pH 7.4 and 30°C in a phosphate alkaline buffer. Relationship of Peni-V concentration in logarithmic mathematical form with current in potentiometric method and with resistance in impedimetric method were obtained.

The present study showed that the Pt electrode modified with Polyaniline–β-CD was an excellent candidate for sensitive penicillin analysis. The proposed electroanalytical technique is rapid, simple and inexpensive.

At present, carbonated drinks such as cola are especially favored by the younger generation. But because of its acid, it often leads to tooth demineralization, resulting in “cola tooth”. However, the influence of cola on the corrosion resistance of passive film of TiA10 alloy restorative materials is rarely reported. The purpose of this study was to analysis the corrosion resistance, composition of the passive film of TA10 alloy in different concentrations of Cola.

The passive behavior of TA10 alloy in artificial saliva (AS) and Cola was studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic voltammetry, Mott-Schottky techniques and combined with X-ray photoelectron spectroscopy and Auger electron spectroscopy (AES) surface analysis.

With the increase of cola content, the self-corrosion current density of the alloy increases sharply, and the corrosion resistance of the passive film is the best in AS, while Rp in cola is reduced to half of that in AS. The thickness of the passive film in AS, AS +cola and cola is about 9.5 nm, 7.5 nm and 6 nm, respectively. The passive film in cola has more defects and the carrier density is 1.55 times as high as that in AS. Cola can weaken the formation process of the protected oxide, promote the formation of high valence Ti-oxides and increase the content of Mo-oxides in the passive film.

These results have important guiding significance for the safe use of the alloy in the complex oral environments.

This paper aims to focus on the development and characterization of a new electrochemical sensor, designed for the detection of methylene blue present in aqueous medium.

This sensor is obtained through the coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of a receptor: β-cyclodextrin (β-CD), a polymer (polyvinylchloride) and a plasticizer (dioctylphtalate). Cyclic voltammetry method (CV) was used to investigate the electrical properties of this electrochemical sensor. The effect of the experimental parameters such as dye initial concentration, scan rate, interfering elements presence and additional Nafion membrane presence was investigated in this paper.

The results are interesting because the developed sensor gives a linear response in concentrations range of 10⁻¹³ M–10⁻³ M with a good correlation coefficient of 0.979 and a detection limit of 10⁻¹³ M, which reflects the sensitivity of this sensor to the target element. The sensibility value is equal to 2. 40 µA mol⁻¹ L.

The present study has shown that the modified electrode is a very good candidate in terms of price, sensibility and reproducibility for the construction of the sensitive sensor for the control of wastewater containing methylene blue.

The purpose of this paper is to reveal the mechanism of nitrite (NO_2⁻) for the surface passivation of carbon steels in acidic environments through investigating the influences of 0.01 mol/L NaNO₂ addition on the corrosion and passivation behaviors of Q235 carbon steel in acidic phosphate buffer (APB) solutions (pH 2 to 6).

The electrochemical techniques including open circle potential evolution, potentiodynamic polarization, electrochemical impedance spectroscopy and cyclic voltammetry were applied.

In APB solutions without NO_2⁻, the Q235 steel presented the electrochemical behaviors of activation (A), activation-passivation-transpassivation and self-passivation-transpassivation at pH 2 to 4, pH 5 and pH 6, respectively; the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6.

In APB solutions without NO_2⁻, the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6. With the addition of 0.01 mol/L NaNO₂, into APB solutions, the variation of corrosion rate showed the same rule, but the surface passivation occurred over the whole acidic pH range, including the anodic passivation at pH 2 to 4 and the spontaneous passivation at pH 5 to 6.

The purpose of this paper is to study the immobilization of porcine pancreatic lipase (PPL), in an organic matrix by a covalent cross-linking method to sense propylparaben (PP) present in aqueous solution.

PPL immobilization was performed by the covalent cross-linking method, using bovine serum albumin (BSA) in the presence of saturated glutaraldehyde vapor (GA). The preparation of the enzymatic membrane involves the incorporation of porcine pancreatic lipase (PPL), bovine serum albumin (BSA) and glycerol into a phosphate buffer solution (PBS). Characterization of this sensor was performed by impedance spectroscopy (EIS) and scanning electron microscope (SEM). The effect of experimental conditions such as PPL activity, potential, scan rate, PP concentration, pH and presence of interfering elements were studied by cyclic voltammetry.

Under the optimal experimental conditions, a number of significant factors were optimized. The method exhibited good linearity in the range of 10^–14 to 10^–9 mol/L with a good correlation coefficient of 0.957, detection limit (LOD) of 3.66 × 10^–15 mol/L and high sensitivity of 1.086 mA mol⁻¹L. The authors also obtained a very good coverage rate of the surface equal to 91.44%, and hydrolytic activity of lipase is evaluated to 26.64 mmol min⁻¹. The stability and the interference were also evaluated. The equivalent circuit used to explain the electrochemical behavior of modified electrode is a Randle circuit.

The main application of biosensors is the detection of biomolecules that are either indicators of a disease. For example, electrochemical biosensing techniques can be used as clinical tools to detect breast tumors, because these compounds (PP) were found in breast tumors.

The result registered in this paper indicates that the developed sensor is an efficient, fast, simple and inexpensive analytical tool that can be used for the analysis of water containing PP.

This paper aims to prepare third-order nonlinear optical (NLO) organic materials with large nonlinear optimization value, high damage threshold and ultrafast response time.

A series of novel symmetric and asymmetric compounds possessing third-order NLO properties were synthesized using 1,3,5-tribromobenzene as the basis. The photophysical and electrochemical properties, as well as the click reactions, were characterized by means of UV–VIS–NIR absorption spectroscopy and cyclic voltammetry.

The donor–acceptor chromophores were inserted into compound, making the molecule to have a broader absorption in the near-infrared regions and a narrower optical and electrochemical band gap. It also formed an electron-delocalized organic system, which has larger effects on achieving a third-order NLO response. The third-order NLO phenomenon of benzene ring complexes was experimentally studied at 532 nm using Z-scan technology, and some compounds showed the expected NLO properties.

The click products exhibit more NLO phenomena by performing different click combinations to the side groups, opening new perspectives on using the system in a variety of photoelectric applications.

Neglected tropical diseases (NTDs) are a set of infectious diseases that primarily affect low-income countries situated near the equator. Effective diagnostic tools hold the key to stemming the spread of these infectious diseases. However, specificity is a major concern associated with current diagnostic protocols. In this regard, electrochemical deoxyribonucleic acid (DNA) biosensors could play a crucial role, as highlighted by renewed interest in their research. The purpose of this study was to highlight the current scenario for the design and development of biosensors for the detection of NTDs related pathogens. This review highlights the different types of factors involved and the modifications used to enhance sensor properties.

The authors discuss the potential of electrochemical DNA biosensors as efficient, affordable diagnostic tools for the detection of pathogens associated with NTDs by reviewing available literature. This study discusses the biosensor components, mainly the probe selection and type of electrodes used, and their potential to improve the overall design of the biosensor. Further, this study analyses the different nanomaterials used in NTD-based electrochemical DNA biosensors and discusses how their incorporation could improve the overall sensitivity and specificity of the biosensor design. Finally, this study examines the impact such techniques could have in the future on mass screening of NTDs.

The findings provide an in-depth analysis of electrochemical DNA biosensors for the detection of pathogens associated with NTDs.

This review provides an update on the different types and modifications of DNA biosensors that have been designed for the diagnosis of NTD-related pathogens.

This research aims to unravel the role of salt contamination and corrosion inhibiting admixtures in the processes of cement hydration and rebar corrosion.

Mortar samples were prepared with NaCl and one of three corrosion inhibitors, sodium nitrite, disodium β‐glycerophosphate, or N,N′‐dimethylethanolamine, admixed. After 28 days curing, all steel‐mortar samples were ponded with 3 percent NaCl solution and electrochemical impedance spectroscopy (EIS) measurements were conducted periodically during the first 48 days. After 60 days of ponding by 3 percent NaCl solution, field‐emission scanning electron microscopy (FESEM) analyses were conducted on the fracture surface of the steel‐mortar sample.

The FESEM results revealed that admixing chlorides and inhibitors in fresh mortar changed the morphology and cement hydration product of hardener mortar at the steel‐mortar interface. The EIS data indicated that all inhibitors increased the polarization resistance of steel, implying reduced corrosion rate of the steel over 48‐day exposures to salt ponding. 0.05 M N,N′‐dimethylethanolamine was the most effective corrosion inhibitor, followed by 0.5 M sodium nitrite; whereas 0.05 M disodium β‐glycerophosphate was a slower and less capable corrosion inhibitor. The admixing of inhibitors in fresh mortar consistently increased the capacitance and decreased the electrical resistance of hardened mortar. The effect of sodium nitrite inhibitor on the resistance of steel mortar interfacial film compensated that of corrosive NaCl by participating to the formation of a protective ferric oxide film.

The results reported shed light on the complex role of admixed salt and corrosion inhibitors in cement hydration and their implications on the durability of steel‐reinforced concrete.

The purpose of this paper is to develop new knowledge in experimental characterization of contaminants in engine lubricants, using surface plasmon resonance (SPR) sensing that can be applicable for on‐line condition monitoring of lubricant quality and engine component performance.

The effect of change in optical properties (e.g. transparency, absorption, and refractive index) of engine lubricants caused by the introduction of contaminants, such as gasoline, coolant, and water, on the surface plasmon resonance characteristics is analyzed experimentally. In SPR measurement, variations in both the refractive index and absorption cause changes in the SPR curve, which is the dependence of reflectivity vs incidence angle. The SPR characteristics (e.g. refractivity) of engine lubricant contaminated by gasoline, water and coolant at different concentration are measured as a function of resonance angle and analyzed with respect to different concentration (1%‐10%) of contaminants. Also, pattern recognition analysis between fresh and used engine lubricants is performed, to show applicability of Bayesian classification methodology for on‐line monitoring and predicting engine lubricant condition.

It was shown experimentally that attenuation of surface plasmons due to introduction of contaminants to the engine lubricant leads to a noticeable change in resonance angle and reflectivity minimum of the SPR curve due to an increase in the dielectric permittivity. In addition, the changes in the SPR characteristics were observed between fresh and used engine lubricant, causing resonance angle and reflectivity minimum of the SPR curve to shift.

The knowledge generated in this study lays the informational basis to further develop an on‐line system for engine lubricant condition monitoring using miniaturized SPR sensors fully suitable for on board applications.

SPR characterization is originally applied for analysis of optical properties of engine lubricants caused by the introduction of contaminants, such as gasoline, coolant, and water.