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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.

Once employed merely to curb pitting corrosion in condenser tubes, cathodic protection is now used throughout the circulating‐water system of a power station, and sometimes beyond.

Electrochemical measurements were used to characterize the inhibiting effectiveness of Curcuma and saffron, considered as green inhibitors in a corrosive environment 3% NaCl on A106 Gr B carbon steel.

This study/paper aims to polarization and potentiodynamic impedance spectroscopy techniques were performed on A106 Gr B carbon steel in the 3% NaCl environment only and containing various concentrations of Curcuma and Saffron (0.005, 0.01, 0.02, 0.04, g/L) after 30 min of immersion; these measures were taken at a temperature of (298 ± 1)K. A voltlab PGZ 301 assembled by A 106 Gr B carbon steel working electrode, a platinum counter electrode (CE) and a saturated calomel electrode as the reference electrode were used in the experiment. In this research, potentiodynamic polarization and electrochemical impedance spectroscopy were used.

The inhibition efficiencies increased with increase in the concentrations of the inhibitor but decreased with rise in temperature. The obtained results show an optimal efficiency with 0.04 g/L which are ordered of 78 and 96 per cent successively for the two inhibitors. Curcuma and saffron acts as a mixed type inhibitor. Adsorption of the inhibitor molecules corresponds to Langmuir adsorption isotherm. Mechanism of inhibition was also investigated by calculating the thermodynamic and activation parameters like (ΔG), (E_a), (ΔH_a) and (ΔS_a). The inhibitor molecules followed physical adsorption on the surface of carbon steel.

The present trend in research on environmental friendly corrosion inhibitors is concentrating on products of natural origin due principally to non-toxicity and eco-friendliness. Among these natural products are curcuma and saffron.

The purpose of this paper is to show how to obtain a supercapacitor with high specific power (P) and high specific energy (E_p) simultaneously.

The carbon aerogels are obtained by ambient pressure drying method instead of supercritical drying method and carbon aerogels/Ni(OH)₂ composites are prepared by in situ polymerisation. A series of asymmetric supercapacitors based on carbon aerogels/Ni(OH)₂ composites as positive electrode and activated carbon as negative electrode, respectively, are assembled. The electrochemical performances of carbon aerogels/Ni(OH)₂ composites and supercapacitors are studied.

The results show that the specific capacitance (C_P) of carbon aerogels/Ni(OH)₂ composites is 584 F/m². The working potential of supercapacitors could be increased to 1.6V. When the mass ratio of carbon aerogels and Ni(OH)₂ is 3:7, the mass ratio of positive electrode and negative electrode is 1:1, the E_P and P of the supercapacitor is higher than 10.5 Wh/kg and 578 W/kg, respectively, when the current varies from 50 mA to 100 mA and the attenuation ratio of C_P is only 8.3 per cent after 10,000 cycles at 100 mA.

The supercapacitors can be used in the field of automobile engineering and can solve the problems of energy shortage and environmental pollutions.

The supercapacitor based on carbon aerogels/Ni(OH)₂ composites as positive electrode and activated carbon as negative electrode is novel and the synthetic properties of the supercapacitor are excellent.

The purpose of this paper is to investigate the effects of chloride ion concentration and applied bias voltage on the electrochemical migration (ECM) behavior between Cu and Ag under an NaCl thin electrolyte layer (TEL).

A self-made experimental setup for the ECM behavior between Cu and Ag was designed. An HD video measurement microscopy was used to observe the typical dendrite/corrosion morphology and pH distribution. Short-circuit time (SCT), short-circuit current density and the influence of the galvanic effect between Cu and Ag on their ECM behavior were studied by electrochemical tests. The surface morphology and composition of dendrite were characterized by FESEM/EDS.

The SCT increased with increasing NaCl concentration but decreased with increasing applied bias voltage, and the SCT between Cu and Ag was less than that between Cu and Cu because their galvanic effect accelerated the dissolution and migration of Cu. When NaCl concentration was less than or equal to 6 mmol/L, cedar-like dendrite was formed, whereas no dendrite formed and only precipitation occurred at high chloride ion concentration (100 mmol/L). The composition of the dendrite between Cu and Ag was copper.

The significance of this study is to clarify the ECM failure mechanism of printed circuit board (PCB) with an immersion silver surface finish (PCB-ImAg).

This study provides a basic theoretical basis for the selection of protective measures and metal coatings for PCB.

The social implication of this study is to predict the service life of PCB.

The ECM behavior of dissimilar metals under a TEL was investigated, the influence of the galvanic effect between them on their ECM was discussed, and the SCT increased with increasing NaCl concentration.

The purpose of this paper is to provide useful information pertaining to the corrosion inhibition mechanism of BTA and its derivatives on copper.

The photoelectrochemical behavior of copper electrodes in buffered borax solutions (pH 9.2) containing BTA and its derivatives was comparatively studied by using a photoelectrochemical technique. It was possible to analyze the inhibition mechanism of the derivatives of BTA for copper corrosion from the photoelectrochemical results. The photoresponse of the Cu electrode in buffered borax solutions containing BTA and its derivatives was measured. Different concentrations and different kinds of inhibitors may result in different photoresponses on the Cu electrode in buffered borax solutions.

The photoresponse for copper electrodes in solutions containing a certain amount of BTA exhibits an n‐type response during anodic polarization and, the greater the n‐type photoresponse, the better the performance of the inhibitor. The photoresponse for copper electrodes in solutions containing 4CBTA, or 5CBTA, or CBT‐1, always exhibited p‐type behavior during anodic polarization, but the photoresponse changed very evidently during cathodic polarization. The larger the maximum cathodic photocurrent, then the greater was the effectiveness of the corrosion inhibitor. In consequence, it is possible to evaluate inhibitors according to Φ_V and i_ph at more negative potentials. The more negative the Φ_V and i_ph, the better is the inhibition. It was shown that the inhibition mechanism of the derivatives of BTA with a −COOH group was different from that occurring with ester groups. The former could make the Cu₂O film on the Cu electrode thicker. The photocurrent was observed to increase when the potential was scanned to more negative potentials in the presence of certain concentrated inhibitors. It is therefore possible to evaluate the performance of inhibitors according to the value of the cathodic photocurrent. The larger the cathodic photocurrent, the better is the inhibition effect of the compound. The latter could increase the density of the polymer film on the copper electrode and prevent O²⁻ in the solution from entering the copper surface and changing the stoichiometric ratio of Cu₂O. The photocurrent type could transfer from p‐ to n‐type according to the action of certain concentrated inhibitors when the potential was scanned to more positive potentials. The value of the anodic photocurrent can be used to evaluate the effectiveness of inhibition. The larger the anodic photocurrent, the greater is the inhibition effect.

The paper provides useful information pertaining to the corrosion inhibition mechanism of BTA and its derivatives on copper. The photoelectrochemical technique is an effective method with which to evaluate the effectiveness of corrosion inhibitors and to investigate the mechanism of corrosion inhibition on copper.

The efficiency of two anticorrosive pigments containing aluminium polyphosphate was studied. Pigments were analysed by current analytical techniques and characterised by FT‐IR spectrometry. The anticorrosive properties of the selected pigments were evaluated following the electrochemical behaviour of a steel electrode in pigments suspensions. In a second stage, solvent‐borne paints with 30 and 10% v/v of the pigment and PVC/CPVC (pigment volume concentration/critical pigment volume concentration) ratio 0.8 were formulated. Three resins were chosen as film forming materials: an alkyd, an epoxy and a vinyl. The performance of the resulting anticorrosive paints was assessed by accelerated (salt spray cabinet and humidity chamber) and electrochemical tests (corrosion potential, ionic resistance and polarisation resistance). The anticorrosive performance of the tested paints was closely related with pigment composition. The nature of the resin was also of importance; in this sense, epoxy paints showed the best anticorrosive performance. Good correlation has been obtained between accelerated and electrochemical tests.

This paper aims to provide a detailed review of weak interaction biosensors and several common biosensor methods for magnifying signals, as well as judiciously guide readers through selecting an appropriate detecting system and signal amplification method according to their research and application purpose.

This paper classifies the weak interactions between biomolecules, summarizes the common signal amplification methods used in biosensor design and compares the performance of different kinds of biosensors. It highlights a potential electrochemical signal amplification method: the G protein signaling cascade amplification system.

Developed biosensors which, based on various principles, have their own strengths and weaknesses have met the basic detection requirements for weak interaction between biomolecules: the selectivity, sensitivity and detection limit of biosensors have been consistently improving with the use of new signal amplification methods. However, most of the weak interaction biosensors stop at the research stage; there are only a minority realization of final commercial application.

This paper evaluates the status of research and application of weak interaction biosensors systematically. The G protein signaling cascade amplification system proposal offers a new avenue for the research and development of electrochemical biosensors.

This paper aims to develop an inexpensive, portable, sensitive and environmentally friendly electrochemical sensor to quantify trace metals.

A sensor was constructed by modifying carbon paste electrode for the determination of lead, cadmium and zinc ions using square wave anodic stripping voltammetry (SWASV). The modified electrode was prepared by inserting homogeneous mixture of 2-hydroxy-acetophenonethiosemicarbazone, graphite powder and mineral oil. Various important parameters controlling the performance of the sensor were investigated and optimized. Electrochemical behavior of modified electrode was characterized by cyclic voltammetry.

Modified carbon pastes electrodes showed three distinct peaks at −0.50, −0.76 and −1.02 V vs silver/silver chloride corresponding to the oxidation of lead, cadmium and zinc ions at the electrode surface, respectively. The highest peak currents for all the metal ions under study were observed in the phosphate buffer solution at pH 1 with a deposition time of 70 s. The sensor exhibited linear behavior in the range of 0.25-12.5 μg mL-1 for lead and cadmium and 0.25-10.0 μg mL⁻¹ for zinc. The limit of detection was calculated as 78.81, 96.17 and 91.88 ng mL⁻¹ for Pb2⁺, Cd2⁺and Zn2⁺, respectively. The modified electrode exhibited good stability and repeatability.

A chemically modified electrode with Schiff base was applied to determine the content of cadmium, lead and zinc ions in aqueous solutions using SWASV.

The results of the electrochemical noise observations in 0H18N9 steel are presented. Current noise was obtained by potentiostatic measurements in aqueous solution of 0.1M H₂SO₄ and 0.06M Cl⁻. The recorded noise had an evident trend and peaks that are typically observed during pitting corrosion. The trend was removed by means of the third order polynomial approximation. The statistical hypothesis, i.e. the difference between the approximation and the observed noise, was tested. The results confirmed that current noise caused by pitting corrosion has nonstationary or weakly stationary character. The recorded noise was analysed using the Joint Time‐Frequency Analysis method, which is appropriate for nonstationary signals. The derived results confirmed the presence of pitting corrosion. It was usual for a few pits to form on the surface of the electrodes in distinct phases, and these were observed as peaks in current fluctuations.