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4 results on '"S. Ahmadifar"'

1. Experimental and modeling study of liquid phase equilibria for (water + phosphoric acid + sec-alcohols) systems

Author

A. Ghanadzadeh Gilani, S. Ahmadifar, and T. Taki

Subjects
Cloud point, UNIQUAC, Chemistry, Phase (matter), Non-random two-liquid model, Thermodynamics, General Materials Science, Titration, Physical and Theoretical Chemistry, Solubility, Ternary operation, Tie line, Atomic and Molecular Physics, and Optics
Abstract

The present study is focused on determination of the liquid-liquid equilibrium (LLE) data for (water + phosphoric acid + 2-pentanol or 4-methyl-2-pentanol) ternary systems at T = (298.2, 308.2, and 318.2) K and p = 0.1 Mpa. Despite of the structural similarity of the chosen sec-alcohols, their polarity and hydrophobicity are different. Thus, the influence of the chemical structure as well as temperatures on the liquid phase behaviour was investigated. Solubility and tie line data were measured using different titration methods such as cloud point, acidimetric, and the Karl Fisher titration techniques. The refractive index measurements were also carried out on the aqueous phase. The experimental tie line data were correlated using the thermodynamic models of NRTL and UNIQUAC. The binary interaction parameters were optimized by the MATLAB fminsearch function. Both the ternary systems exhibit type-1 phase behavior. The quality of the tie-lines was checked using the Othmer-Tobias equation. Distribution coefficients and separation factors were calculated over the biphasic regions.

Published
2019

2. Experimental and correlational study of phase equilibria in aqueous mixtures of phosphoric acid with aromatic hydrocarbons at various temperatures

Author

A. Ghanadzadeh Gilani, H. Ghanadzadeh Gilani, and S. Ahmadifar

Subjects
Cumene, UNIQUAC, Aqueous solution, Analytical chemistry, Atomic and Molecular Physics, and Optics, chemistry.chemical_compound, chemistry, Non-random two-liquid model, Organic chemistry, General Materials Science, Physical and Theoretical Chemistry, Solubility, Ternary operation, Benzene, Phosphoric acid
Abstract

Experimental solubility and tie-line data were obtained for (water + phosphoric acid + ethyl benzene or cumene) ternary systems at T = (298.15, 308.15 and 318.15) K and P = 101.32 kPa. The experimental tie-line values were correlated using the thermodynamic models of UNIQUAC and NRTL. The quality of the experimental results was determined through the Othmer–Tobias and Hand plots. Distribution coefficients and separation factors were evaluated over the immiscibility regions. The influence of temperature on biphasic region is found to be negligible.

Published
2015

3. Zymographic Determination of Intrinsic Specific Activity of Oxidases in the Presence of Interfering Proteins.

Author

Le TC, Mateescu MA, Ahmadifar S, Marcocci L, and Pietrangeli P

Subjects
Animals, Catalase analysis, Catalase chemistry, Cattle, Enzyme Activation, Hydrogen Peroxide chemistry, Rosaniline Dyes, Spectrophotometry methods, Staining and Labeling, Substrate Specificity, Electrophoresis, Polyacrylamide Gel, Oxidoreductases analysis, Oxidoreductases chemistry, Proteins analysis, Proteins chemistry
Abstract

Zymography on peroxidase-entrapped gels enables the determination of the intrinsic specific activity (ISA) of H 2 O 2 -producing oxidases in the presence of interfering enzymes including catalase (decomposing hydrogen peroxide). To reveal the searched oxidase, the zymography gel is incubated first in the developing solution containing the appropriate substrate of the oxidase and an oxidizable chromogen such as o-phenylenediamine (o-PDA) peroxidase substrate. The zymographic gel, after image analysis, can be restained by Coomassie Blue for molecular weights, for the whole electrophoretic pattern and for the protein concentration, thus allowing for the determination of oxidase ISA.

Published
2018
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4. Zymographic approach to determine the intrinsic enzyme specific activity of diamine oxidase in presence of interfering enzymes.

Author

Ahmadifar S, Le TC, Marcocci L, Pietrangeli P, and Mateescu MA

Subjects
Hydrogen Peroxide metabolism, Peroxidases, Putrescine, Amine Oxidase (Copper-Containing) metabolism, Electrophoresis, Polyacrylamide Gel
Abstract

The purpose of this investigation was to elaborate a fast zymographic assay of oxidase enzymes in the presence of interfering enzymes as catalase (which disturbs current dosages based on H 2 O 2 detection). This method also allows the determination of intrinsic specific activity (ISA) of oxidases, such as diamine oxidase (DAO) or glucose oxidase (GOD). The SDS-PAGE gels with entrapped peroxidase have been obtained by polymerization of acrylamide and bis-acrylamide in the presence of horse-radish peroxidase. The entrapped peroxidase was uniformly distributed in the PolyacrylAmide (PAA) material and did not migrate during electrophoresis. The obtained PAA gels allow the electrophoretic separation of various oxidases from contaminating proteins. As an example, to reveal DAO, the resulting PAA-gel should be incubated after the electrophoretic run in the developing solution containing putrescine (a DAO substrate) and o-phenylenediamine (a HRP substrate) to give coloured bands on the gel in the presence of DAO-generated H 2 O 2 . The results showed that is possible to determine the DAO in the presence of interfering catalase because they migrate differently. Thus, the H 2 O 2 released in situ by DAO is no more decomposed by catalase because of its different mobility. It was also found that the same electrophoretic gel, after zymography, can be restained by Coomassie Blue for quantitation of proteins corresponding to the zymographic bands. With the obtained enzyme units and protein concentration it is also possible to calculate the intrinsic specific activity of DAO directly from the intensities of enzyme bands in zymography and from those of protein bands (Coomassie Blue staining), quantified by densitometry., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Published
2017
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