A Study on Voltametric Electro-kinetic Mechanism of Catechol at l-glutamic Acid-Carbon Paste Sensor

2017 ◽  
Vol 33 (1-2) ◽  
pp. 1
Author(s):  
Tadesse Abrha ◽  
Rishi Pal ◽  
R. C. Saini
Keyword(s):  
Electron Transfer ◽  
Glutamic Acid ◽  
Rate Constant ◽  
Living Organism ◽  
Active Species ◽  
Electrochemical Process ◽  
Single Step ◽  
Body Parts ◽  
Carbon Paste ◽  
Electronic Chemical

Quinones and quinoles, the pervasive components of living organism, perform different biochemical and physiological activities. These compounds have found their widespread applications as life saving drugs in cancer chemotherapy, antioxidant, anti bacterial and antifungal agents. These contribute as components of biological electron transfer chains located indifferent body parts. Electrochemical redox behavior of catechol using cyclic and differential pulse voltammetry at the surface of ℓ-glutamic acid modified carbon paste sensor was observed quite sensitive. There was a remarkable increase in the magnitude of both peak currents of catechol at the surface of modified electrode as compared to that of bare carbon paste electrode. Optimizations of working parameters for both techniques have been performed to perk up the working efficiency during experimentation. The electrochemical process occurs under both the diffusion and adsorption controlled conditions. The kinetic parameters such as heterogeneous electron transfer rate constant for electrode process (K<sub>h</sub>), diffusion coefficient (D), standard rate constant of surface reaction (k°), electron transfer coefficient (α) and the average surface concentrations of electro-active species (χ<sub>1</sub>&amp;χ<sub>2</sub>) at the electro-chemical barriers catechol/o-quinone radical and o-quinone radical/o-quinone were calculated. The calculated value of K<sub>h</sub> lie in close vicinity to limiting value of a complete irreversible process and in far range of quasi-reversible process. In the higher range of applied scan rates at lower potentials of the used potential window, the forward scan revealed the formation of well stable reaction intermediate, at relatively slower rate. This is the rate determining step of the oxidation process but in case of reduction pulse of the same scan rate, there is no indication of any reduction intermediate moieties. The chemical process during electrochemical oxidation of catechol follows pseudo first order kinetics. Furthermore, a two step oxidation, Electronic-Chemical-Electronic-Chemical reactions (ECEC) mechanism has been proposed and single step reduction has been observed for the coupled redox process at the sensor/analyte interface.

Studies on Cerium Electrochemistry in High Temperature Ionic Liquids

2018 ◽  
Vol 69 (1) ◽  
pp. 112-115
Author(s):  
Ana Maria Popescu ◽  
Virgil Constantin
Keyword(s):  
Molten Salts ◽  
Electrochemical Techniques ◽  
Active Species ◽  
Single Step ◽  
Cathodic Process ◽  
Molybdenum Electrode ◽  
Solute Interaction ◽  
Ohmic Drop ◽  
State Potential ◽  
Direct Discharge

The cathodic behavior of Ce3+ ions in LiF-NaF-BaF2, LiF-NaF-NaCl and NaCl-KCl molten salts at 730� C has been studied using different electrochemical techniques. The decomposition potential (Ed) and the cathodic overvoltage were determined by introducing NaCeF4 as electrochemical active species using steady-state potential-current curves recorded under galvanostatic conditions. The values of |Ed| were 1.85 V in LiF-NaF-BaF2, 2.114 V in LiF-NaF-NaCl and 2.538 V in NaCl-KCl, respectively. It was also found that the ohmic drop potential in melt is not dependent on NaCeF4 concentration and it rises as the current intensity increases. The Tafel slopes and other kinetic parameters were calculated on the assumption that the cathodic process consisted of direct discharge of Ce3+, with no solvent-solute interaction. In order to elucidate the mechanisn of cathodic process the cyclic voltammetry technique was finally used. From the evolution of the voltammograms we conclude that the electrochemical reduction of Ce3+ ion is actually a reversible process on the molybdenum electrode and cathodic reduction of Ce3+ takes place in one single step involving three electron exchange. Our study adds to the accumulating data and confirms available results of electrodeposition of metalic cerium from molten salts using NaCeF4 as solute.

Discovery of THICZs as Chemical Sensors: Synthesis, Spectrophotometric,Voltammetric and DFT Studies

2019 ◽  
Vol 09 ◽  
Author(s):  
Mardia T. El Sayed ◽  
Ibrahim H.I. Habib ◽  
Nermien M. Sabry ◽  
Sergey A. Pisarev ◽  
Mohamed El-Naggar ◽  
...  
Keyword(s):  
Electrochemical Behaviour ◽  
Molecular Size ◽  
Active Species ◽  
Carbon Paste ◽  
Reversible Redox ◽  
Energy Relationships ◽  
Linear Solvation Energy ◽  
Solute Interactions ◽  
Homo Lumo ◽  
Paste Electrode

Absorption spectra of tetrahydro[3,2-b]indolo-carbazoles (THICZs) with various molecular size and alkyl tails have been recorded in various solvents in the range between 200 to 600 nm. The photo physical behaviour of dissolved THICZs depends on the nature of its environment. The solvatochromic behaviours of THICZs and solvent solute interactions can be analysed by means of linear solvation energy relationships concept proposed by Kamlet and Taft. Compound 4 show excellent properties for sensing small molecules. The electrochemical behaviour of some THICZs was investigated at carbon paste electrode where two electrode reactions were involved, irreversible oxidation-one electron transfer and quasi-reversible redox reactions forming phenolic followed by quinolone moiety electro active species. The DFT-calculated molecular orbital energies (B3LYP/6-31G) and HOMO-LUMO gaps for some presented indolocarbazoles have been performed.

Formation of CT complexes and electron transfer from excited molecules of anthracene derivatives to methylviologen in aqueous and micellar media

1987 ◽  
Vol 52 (7) ◽  
pp. 1658-1665
Author(s):  
Viktor Řehák ◽  
Jana Boledovičová
Keyword(s):  
Electron Transfer ◽  
Complex Formation ◽  
Fluorescence Quenching ◽  
Rate Constant ◽  
Formation Constants ◽  
Dynamic Quenching ◽  
Micellar Media ◽  
Complex Formation Constants ◽  
Anthracene Derivatives ◽  
Ct Complexes

Disodium 1,5- and 1,8-anthracenedisulphonate (ADS) and 9-acetylanthracene form coloured CT complexes with methylviologen (MV2+) in aqueous and micellar media. The complex formation constants and molar absorptivities were determined by the Benesi-Hildebrandt method. In the fluorescence quenching, its static component plays the major role. The dynamic quenching component is determined by the rate constant of electron transfer from the S1 state of ADS to MV2+.

The Effect of p-Toluidine on the Two-Step Electroreduction of Zn(II) in Water-Methanol and Water-Dimethylformamide

1999 ◽  
Vol 64 (4) ◽  
pp. 585-594 ◽  
Author(s):  
Barbara Marczewska
Keyword(s):  
Electron Transfer ◽  
Binary Mixtures ◽  
Rate Constant ◽  
Rate Constants ◽  
Electrode Surface ◽  
Mercury Electrode ◽  
Forward Rate ◽  
Solvent Molecules ◽  
Activated Complex

The acceleration effect of p-toluidine on the electroreduction of Zn(II) on the mercury electrode surface in binary mixtures water-methanol and water-dimethylformamide is discussed. The obtained apparent and true forward rate constants of Zn(II) reduction indicate that the rate constant of the first electron transfer increases in the presence of p-toluidine. The acceleration effect may probably be accounted for by the concept of the formation on the mercury electrode an activated complex, presumably composed of p-toluidine and solvent molecules.

scholarly journals Biosensing Membrane Base on Ferulic Acid and Glucose Oxidase for an Amperometric Glucose Biosensor

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3757
Author(s):  
Gabriela Valdés-Ramírez ◽  
Laura Galicia
Keyword(s):  
Ferulic Acid ◽  
Glucose Oxidase ◽  
Aqueous Media ◽  
Glucose Biosensor ◽  
Single Step ◽  
Coefficient Of Determination ◽  
The Novel ◽  
Carbon Paste ◽  
Glucose Response ◽  
Glucose Biosensors

A biosensing membrane base on ferulic acid and glucose oxidase is synthesized onto a carbon paste electrode by electropolymerization via cyclic voltammetry in aqueous media at neutral pH at a single step. The developed biosensors exhibit a linear response from 0.082 to 34 mM glucose concentration, with a coefficient of determination R2 equal to 0.997. The biosensors display a sensitivity of 1.1 μAmM−1 cm−2, a detection limit of 0.025 mM, and 0.082 mM as glucose quantification limit. The studies reveal stable, repeatable, and reproducible biosensors response. The results indicate that the novel poly-ferulic acid membrane synthesized by electropolymerization is a promising method for glucose oxidase immobilization towards the development of glucose biosensors. The developed glucose biosensors exhibit a broader linear glucose response than other polymer-based glucose biosensors.

Anthropomorphic Metaphor in the English Veterinary Terminology

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
O Syrotin ◽  
Keyword(s):  
Veterinary Medicine ◽  
Conceptual Analysis ◽  
Living Organism ◽  
Functional Similarity ◽  
Social Characteristics ◽  
Body Parts ◽  
Way Of Life ◽  
Cognitive Transfer ◽  
The Social ◽  
Natural Fact

Introduction. The article is devoted to the presentation of the results of the study of metaphorization and the study of metaphorical terms, widely represented in the English terminology of veterinary medicine. The purpose of the article is to represent the features of the anthropomorphic metaphorical name in the English terminology of veterinary medicine. Materials and methods of research. The study of metaphorization as a way of forming English veterinary terms was conducted by us on the basis of lexicographic data recorded in English terminological dictionaries of veterinary medicine. Results of the research. The analysis of lexicographic material allowed to identify four donor domains that served as a source of metaphorical names in the terminology of veterinary medicine: HUMAN, LIVING ORGANISM, NATURAL FACT, ARTIFACT. Conceptual analysis of metaphorical terms of veterinary medicine revealed that one of the most productive metaphors used in the creation of terminological units is anthropomorphic. In anthropomorphic metaphorization, the names are transferred from the donor domain HUMAN to the recipient domain VETERINARY. The article attempts to consider the cognitive basis of anthropomorphic metaphor as one of the mechanisms of creation of veterinary terms in English. Based on the theory of conceptual metaphor, it was found that the sources of anthropomorphic metaphor are the biological characteristics of people, the names of body parts and properties of a living organism. Semantic groups of metaphorical terms formed on the basis of cognitive transfer of tokens related to the structure of the human body, its behavior, inherent qualities, life and way of life in the field of veterinary medicine based on external or functional similarity between donor and recipient domains are considered. Сonclusions. Thus, the study allows us to conclude that the terms-metaphors occupy a certain niche in the terminology of veterinary medicine in English and ensure their effective functioning in the language of veterinarians. Conceptual analysis of metaphorical terms of veterinary medicine revealed that one of the most productive is anthropomorphic metaphor. As a result of anthropomorphic metaphorization, new terms of veterinary medicine are formed on the basis of cognitive transfer of tokens that relate to the social characteristics of a person that determine his appearance, behavior or condition, in the field of veterinary medicine on the basis of external or functional similarity between donor and recipient domains.

Bromine oxidation of a nickel(II) bis(oxime-imine) complex. Evidence for a single-step outer-sphere two-electron transfer?

1987 ◽  
Vol 26 (19) ◽  
pp. 3089-3094 ◽  
Author(s):  
A. Graham Lappin ◽  
Peter Osvath ◽  
Subhash Baral
Keyword(s):  
Electron Transfer ◽  
Outer Sphere ◽  
Single Step
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