Electrochemical behavior of gold and its associated minerals in alkaline thiourea solutions

The purpose of the study is to investigate the electrochemical behavior of two dental alloys: palladium alloy (Palidor) and Ni-Cr alloy (Verasoft) in three types of artificial saliva. Determination of corrosion potential and recording of linear and cyclic polarization curves were performed with PGP201 potentiostat (VoltaLab 21- Radelkis Copenhagen. In order to study the modifications produced on the surface of the electrodes, a complex optical microscope MC 1 research type (IOR, Romania) was used, adapted to a digital camera, which was connected to a computer for the digital acquisition of images . Two metal alloys based on Ag-Pd and Ni-Cr were used for the experiments. The materials used came from different types of dental restorations removed from the oral cavity of the patients after a 5-15 years period. As corrosion environments, three artificial saliva were used: Fusayama, Afnor and Rondelli. The Pd-Ag dental alloy exhibits a very good corrosion resistance and the treatment in the Afnor saliva does not affect the surface of the alloy. Electrochemical behavior in Fusayama-Meyer�s saliva of the alloy surface results in a series of spots representing deposits of insoluble salts resulting from the oxidation process, while in the Rondelli saliva there is a series of small corrosion points on the alloy surface. The behavior of the Verasoft alloy in the Afnor and Rondelli saliva is similar; In both solutions, the potential breakthroughs are very close, but in Fusayama-Meyer�s saliva, the potential for initiation of corrosion points is very low (206 mV), a potential that can be encountered in the oral cavity. All metals and metal alloys, even the noble and semi-precious ones, are susceptible to corrosion, forming compounds with properties different from those of the metal or base alloy, which change their surface condition. Metallic dental restorations are permanently affected by the factors of the oral environment (physical-mechanical, chemical and biological), being subjected to a continuous process of degradation.

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ChemInform Abstract: ELECTROCHEMICAL BEHAVIOR OF HALOAMIDES. THE ROLE OF ADDITIONAL FUNCTIONAL GROUPS ON THE REDUCTION PATTERN AND THE NATURE OF THE PRODUCTS

Chemischer Informationsdienst ◽

10.1002/chin.198524083 ◽

1985 ◽

Vol 16 (24) ◽

Author(s):

I. CARELLI ◽

A. INESI ◽

M. A. CASADEI ◽

B. DI RIENZO ◽

F. MICHELETTI MORACCI

Keyword(s):

Functional Groups ◽

Electrochemical Behavior

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Microstructure-electrochemical behavior relationships of hierarchically micro-mesoporous silicon oxycarbide derived materials obtained by the pyrolysis of trietoxysilane/dimethyldiphenylsiloxane hybrids

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2021.159427 ◽

2021 ◽

Vol 870 ◽

pp. 159427

Author(s):

M. Alejandra Mazo ◽

M. Teresa Colomer ◽

Aitana Tamayo ◽

Juan Rubio

Keyword(s):

Electrochemical Behavior ◽

Silicon Oxycarbide ◽

Mesoporous Silicon

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Graphite Studded with Facile-Synthesized Cu2O Nanoparticle-Based Cubes as a Novel Electrochemical Sensor for Highly Sensitive Voltametric Determination of Mebeverine Hydrochloride

Chemosensors ◽

10.3390/chemosensors9020035 ◽

2021 ◽

Vol 9 (2) ◽

pp. 35

Author(s):

Ahmed H. Naggar ◽

Ahmed Kotb ◽

Ahmed A. Gahlan ◽

Mahmoud H. Mahross ◽

Abd El-Aziz Y. El-Sayed ◽

...

Keyword(s):

Electron Microscope ◽

Lower Limit ◽

Electrochemical Behavior ◽

Cuprous Oxide ◽

Density Functional ◽

Limit Of Detection ◽

Biological Fluids ◽

Chemical Reduction ◽

Anodic Stripping Voltammetry ◽

Mebeverine Hydrochloride

Herein, a feasible chemical reduction method followed by intensive mixing was applied for the preparation of an attractive material based on graphite studded with cuprous oxide nanoparticle-based cubes (Cu2ONPs–C@G). Transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) were utilized for characterization. Cuprous oxide nanoparticles (Cu2ONPs), with a diameter range mainly distributed from 4 to 20 nm, aggregate to form microcubes (Cu2ONPs–C) with an average diameter of about 367 nm. Paste electrode was prepared using Cu2ONPs–C@G (Cu2ONPs–C@G/PE) for voltametric quantification of the musculotropic antispasmodic drug: mebeverine hydrochloride (MEB). The electrochemical behavior of MEB was studied using CV, and the optimum analytical parameters were investigated using square wave adsorptive anodic stripping voltammetry (SWAdASV). Moreover, density functional theory (DFT) was used to emphasize the ability of MEB to form a complex with Cu2+, confirming the suggested electrochemical behavior of MEB at Cu2ONPs–C@G/PE. With good stability and high reproducibility, SWAdASV of Cu2ONPs–C@G/PE shows successful quantification of MEB over the concentration range of 5.00 × 10−11–1.10 × 10−9 M with lower limit of detection (LOD) and lower limit of quantification (LOQ) values of 2.41 × 10−11 M and 8.05 × 10−11 M, respectively. Finally, accurate quantification of MEB in dosage forms (tablets) and biological fluids (spiked human urine and plasma samples) was achieved using Cu2ONPs-C@G/PE.

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