scholarly journals Electroanalysis Applied to Compatibility and Stability Assays of Drugs: Carvedilol Study Case

2020 ◽  
Vol 13 (4) ◽  
pp. 70
Author(s):  
Murilo Ferreira de Carvalho ◽  
Luane Ferreira Garcia ◽  
Isaac Yves Lopes de Macedo ◽  
Ricardo Neves Marreto ◽  
Mayk Teles de Oliveira ◽  
...  
Keyword(s):  
Stearic Acid ◽  
Electrochemical Impedance ◽  
Peak Potential ◽  
Different Types ◽  
Treatment Of Hypertension ◽  
Study Case ◽  
Lipid Excipients ◽  
Biopharmaceutical Properties ◽  
Β Adrenergic Receptors ◽  
Selective Blocker

Carvedilol (CRV) is a non-selective blocker of α and β adrenergic receptors, which has been extensively used for the treatment of hypertension and congestive heart failure. Owing to its poor biopharmaceutical properties, CRV has been incorporated into different types of drug delivery systems and this necessitates the importance of investigating their compatibility and stability. In this sense, we have investigated the applicability of several electroanalytical tools to assess CRV compatibility with lipid excipients. Voltammetric and electrochemical impedance spectroscopy techniques were used to evaluate the redox behavior of CRV and lipid excipients. Results showed that Plurol® isostearic, liquid excipient, and stearic acid presented the greatest anode peak potential variation, and these were considered suitable excipients for CRV formulation. CRV showed the highest stability at room temperature and at 50 °C when mixed with stearic acid (7% w/w). The results also provided evidence that electrochemical methods might be feasible to complement standard stability/compatibility studies related to redox reactions.

scholarly journals Supramolecular assemblies of carbon nanocoils and tetraphenylporphyrin derivatives for sensing of catechol and hydroquinone in aqueous solution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Syeda Aqsa Batool Bukhari ◽  
Habib Nasir ◽  
Lujun Pan ◽  
Mehroz Tasawar ◽  
Manzar Sohail ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Linear Trend ◽  
Differential Pulse ◽  
Peak Potential ◽  
Limit Of Quantification ◽  
Efficient Detection ◽  
Good Repeatability ◽  
Ft Ir ◽  
Pulse Voltammetry

AbstractNon-enzymatic electrochemical detection of catechol (CC) and hydroquinone (HQ), the xenobiotic pollutants, was carried out at the surface of novel carbon nanocoils/zinc-tetraphenylporphyrin (CNCs/Zn-TPP) nanocomposite supported on glassy carbon electrode. The synergistic effect of chemoresponsive activity of Zn-TPP and a large surface area and electron transfer ability of CNCs lead to efficient detection of CC and HQ. The nanocomposite was characterized by using FT-IR, UV/vis. spectrophotometer, SEM and energy dispersive X-ray spectroscopy (EDS). Cyclic voltammetry, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy were used for the electrochemical studies. CNCs/Zn-TPP/GCE nanosensor displayed a limit of detection (LOD), limit of quantification (LOQ) and sensitivity for catechol as 0.9 µM, 3.1 µM and 0.48 µA µM−1 cm−2, respectively in a concentration range of 25–1500 µM. Similarly, a linear trend in the concentration of hydroquinone detection was observed between 25 and 1500 µM with an LOD, LOQ and sensitivity of 1.5 µM, 5.1 µM and 0.35 µA µM−1 cm−2, respectively. DPV of binary mixture pictured well resolved peaks with anodic peak potential difference, ∆Epa(CC-HQ), of 110 mV showing efficient sensing of CC and HQ. The developed nanosensor exhibits stability for up to 30 days, better selectivity and good repeatability for eight measurements (4.5% for CC and 5.4% for HQ).

scholarly journals Evaluation of the Corrosion Resistance of Phosphate Coatings Deposited on the Surface of the Carbon Steel Used for Carabiners Manufacturing

2020 ◽  
Vol 10 (8) ◽  
pp. 2753 ◽  
Author(s):  
Diana-Petronela Burduhos-Nergis ◽  
Petrica Vizureanu ◽  
Andrei Victor Sandu ◽  
Costica Bejinariu
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
Zinc Phosphate ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Phosphate Solution ◽  
Fire Extinguishing ◽  
Different Types ◽  
Iron Based ◽  
Corrosive Environments

This study aims to evaluate the corrosion resistance of carbon steel, used for carabiners manufacturing, coated with three different types of phosphate layer. The phosphate layers have been obtained by phosphate conversion coating with three different types of phosphate solutions: zinc-based solution, zinc-iron-based phosphate solution, and manganese-based phosphate solution. Additionally, the test was performed on zinc phosphate samples impregnated with molybdenum bisulfate-based oil and zinc phosphate samples further coated with a layer of elastomer-based paint. Considering the areas where the carabiners are used (civil engineering, navigation, oil industry, rescue operations, etc.), the corrosive environments studied are rainwater, Black Sea water, and fire extinguishing solution. The structure of the deposited layers was studied by scanning electron microscopy, while the interface structure between the alloy and corrosive environment was analyzed by electrochemical impedance spectroscopy. According to this study, the corrosion resistance of zinc-based phosphate coated samples and zinc/iron-based phosphate coated samples is higher than that of the studied carbon steel samples, despite the corrosion environment. Also, the most aggressive corrosion environment was the fire extinguishing solution.

COMPARATIVE ANALYSIS OF 14C AND TGA TECHNIQUES FOR THE QUANTIFICATION OF THE BIOMASS CONTENT OF END-OF-LIFE TIRES

2014 ◽  
Vol 87 (4) ◽  
pp. 664-678 ◽  
Author(s):  
Leticia Saiz-Rodríguez ◽  
José María Bermejo-Muñoz ◽  
Andrés Rodríguez-Díaz ◽  
Alberto Fernández-Torres ◽  
Antonio Rubinos-Pérez
Keyword(s):  
Thermogravimetric Analysis ◽  
Stearic Acid ◽  
Natural Rubber ◽  
End Of Life ◽  
Rubber Content ◽  
Thermogravimetric Method ◽  
Precise Method ◽  
Different Types ◽  
Reference Samples

ABSTRACT Thermogravimetric analysis (TGA) and 14C techniques were compared for the determination of the biomass content of end-of-life tires (ELTs). Samples of different types (of ELTs) were prepared, and the biomass fraction of each sample was measured using the two methods (TGA and 14C). Six reference samples were also prepared with known quantities of natural rubber and stearic acid in order to establish the calibration curve necessary for the thermogravimetric analysis and to verify the accuracy of the results of the 14C analysis. The conclusions were that the 14C technique is the more valid, reliable, and precise method for determining the biomass content of end-of-life tires, since the results of the 14C tests of the reference samples coincided perfectly with the actual natural rubber and stearic acid content. On the other hand, the results of the thermogravimetric method differed considerably from the known natural rubber content of the reference samples as well as from the results of the 14C technique. This method is therefore not appropriate for use in determining the biomass content of end-of-life tires.

scholarly journals Evaluating soil quality at a landfill: a study case from morocco (tangier)

2019 ◽  
Vol 9 (4) ◽  
pp. 317-325
Author(s):  
Ikram Chaer ◽  
Asmae El Cadi ◽  
Jamal Brigui ◽  
Khadija Ziat ◽  
Mohamed Khaddor
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Mineral Matter ◽  
X Ray Diffraction ◽  
Work Effort ◽  
Different Types ◽  
Ft Ir ◽  
Study Case ◽  
Ft Ir Spectroscopy

In recent decades, landfill sites have been a potential source of contamination, which can hurt the environment due to the accumulation of heavy metals and processed organic products. In the Tangier landfill, the different types of wastes are missing any prior treatment or any soil of protection. This behavior constitutes a risk factor of contamination for the soil and groundwater. Between the waste and soil, many physicochemical and biological reactions occur. The objective of this work effort is to derive a global and in-depth characterization of the organic and mineral matter of the soil samples from the Tangier landfill. The study of organic matter (OM) in soils helps to understand the evolution of soil contamination. Eight samples of soil have been studied using a range of chemical and physical analytical methods. FT-IR spectroscopy and X-ray diffraction analyses have used to investigate the nature of organic matter. The analysis of heavy metals in the soil showed that there is a significant presence of Pb, Cd, As, Cr and Zn quantities which are mainly due to industrial waste.

scholarly journals Hydrophobic Modification of Magnesium Hydroxide Coating Deposited Cathodically on Magnesium Alloy and its Corrosion Protection

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 477 ◽  
Author(s):  
Yongjun Zhang ◽  
Hui Cao ◽  
Hanxiong Huang ◽  
Zhiping Wang
Keyword(s):  
Surface Modification ◽  
Stearic Acid ◽  
Magnesium Hydroxide ◽  
Electrochemical Impedance ◽  
Mg Alloy ◽  
Hydrophobic Modification ◽  
Cathodic Deposition ◽  
Composite Surface ◽  
Static Contact ◽  
Short Period

In this paper, hydrophobic modification of magnesium hydroxide film prepared by cathodic deposition on ME20M Mg alloy was achieved with ethanol solution of stearic acid. The effects of solution concentration, temperature and treatment time on the surface wettability were investigated. The corrosion behaviors of typical samples were evaluated by droplet test, total immersion corrosion test as well as PDP (Potentiodynamic Polarization) and EIS (Electrochemical Impedance Spectroscopy) techniques, respectively. Adhesion of coatings to the substrate were examined by tape test. The surface morphology and chemical composition of typical coatings were characterized by SEM, FTIR and XRD respectively. The results indicate that the superhydrophobic surface with 151.5° water static contact angle and 1° sliding angle could be fabricated successfully by simple immersion in a low-concentration stearic acid solution for a short period. Compared with blank sample, the composite surface modification based on cathodic deposition (CD) plus hydrophobic treatment (HT) extended the discoloration time in droplet tests by nearly 25 fold, decreased the icorr (corrosion current density) by three orders of magnitude, and increased the characteristic impedance modulus at 0.1 Hz by nearly four orders of magnitude, indicating that the CD/HT composite surface modification could enhance the corrosion resistance of Mg alloy significantly.

scholarly journals The Roles of Alkyl Branches of Ionic Liquid in the Corrosion Resistance of Pb/Sb/Sn Grids Alloy in Lead-Acid Battery

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Behzad Rezaei ◽  
Ali Asghar Ensafi ◽  
Ahmad Reza Taghipour Jahromi
Keyword(s):  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Electrochemical Behaviour ◽  
Lead Acid Battery ◽  
Reverse Effect ◽  
Adsorption Model ◽  
Peak Potential ◽  
Ammonium Hydrogen ◽  
Lead Acid

This paper describes the effects of ionic liquids (ILs) including mono, bicyclohexyl, and tetrahexyl ammonium hydrogen sulphate on the corrosion behaviour of Pb/Sb/Sn grids alloy of lead-acid battery with Pb, Sb (1.66 wt%), and Sn (0.24 wt%). Electrochemical behaviour has been investigated using Tafel plots and electrochemical impedance spectroscopy with various concentrations of ILs as electrolyte additives in 4.0 mol⋅L-1sulphuric acid. The obtained results indicated that, by increasing number of alkyl or cycloalkyl branches in ILs, the corrosion rate of the lead alloy decreases, whereas inhibition efficiency shows a reverse effect. In the presence of all ILs in different concentrations, conversion current of PbSO4to PbO2(iaandic) increases, while the reversibility, deduced from peak potential differences, decreases. Also, the effect of ILs adsorption model on the corrosion behaviour of electrode was proposed.

A spermine conjugated stearic acid-g-chitosan oligosaccharide polymer with different types of amino groups for efficient p53 gene therapy

2016 ◽  
Vol 145 ◽  
pp. 695-705 ◽  
Author(s):  
Tingting Meng ◽  
Jie Wu ◽  
Hanxi Yi ◽  
Jingwen Liu ◽  
Binbin Lu ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Stearic Acid ◽  
P53 Gene ◽  
Chitosan Oligosaccharide ◽  
Amino Groups ◽  
Different Types

scholarly journals The Corrosion Properties of S355J2 Steel Welded Joint in Chlorides Environment

2018 ◽  
Vol 47 (4) ◽  
pp. 342-347
Author(s):  
Kamil Borko ◽  
Branislav Hadzima ◽  
Filip Pastorek
Keyword(s):  
Corrosion Resistance ◽  
Weld Metal ◽  
Welded Joint ◽  
Electrochemical Impedance ◽  
Base Material ◽  
Electrochemical Characteristics ◽  
Corrosion Properties ◽  
Electrochemical Tests ◽  
Different Types ◽  
Submerged Arc

Nowadays are steels the most used structural material for creation of constructions in different types of industry for lot of applications but suffer from unsatisfactory corrosion resistance in the presence of aggressive chlorides. Steel S355J2 represents common type steel for constructions. Very important property of S355J2 steel is weldability. S355J2 steel was welded by submerged arc welding (SAW) method. Corrosion resistance of welded joint was evaluated by electrochemical methods - linear polarization (LP) and electrochemical impedance spectroscopy (EIS). Results from electrochemical tests are general electrochemical characteristics - ECorr, iCorr, vCorr and RP. Environments for testing were solutions with different concentration of chlorides (0.01M, 0.1M and 1M NaCl solution). Difference of corrosion resistance between base material and weld metal is app. 14.5 %. This difference is preserved in all concentrations of tested environments. The highest corrosion resistance was reached by base material in 0.01M NaCl and the lowest corrosion resistance was reached by weld metal in 1M NaCl.

scholarly journals Ligands of Adrenergic Receptors: A Structural Point of View

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 936
Author(s):  
Yiran Wu ◽  
Liting Zeng ◽  
Suwen Zhao
Keyword(s):  
Adrenergic Receptors ◽  
Molecular Mechanisms ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Point Of View ◽  
Different Types ◽  
Treatment Of Hypertension ◽  
Ligand Discovery ◽  
G Protein Coupled ◽  
Structural Point

Adrenergic receptors are G protein-coupled receptors for epinephrine and norepinephrine. They are targets of many drugs for various conditions, including treatment of hypertension, hypotension, and asthma. Adrenergic receptors are intensively studied in structural biology, displayed for binding poses of different types of ligands. Here, we summarized molecular mechanisms of ligand recognition and receptor activation exhibited by structure. We also reviewed recent advances in structure-based ligand discovery against adrenergic receptors.

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