scholarly journals Ab Initio Study of Potential Ultrafast Internal Conversion Routes in Oxybenzone, Caffeic Acid, and Ferulic Acid: Implications for Sunscreens

2014 ◽  
Vol 118 (51) ◽  
pp. 11999-12010 ◽  
Author(s):  
Tolga N. V. Karsili ◽  
Barbara Marchetti ◽  
Michael N. R. Ashfold ◽  
Wolfgang Domcke
Keyword(s):  
Ferulic Acid ◽  
Ab Initio ◽  
Caffeic Acid ◽  
Internal Conversion ◽  
Ab Initio Study

An ab initio study of Se-reacted GaAs(0 0 1) surfaces

1998 ◽  
Vol 184-185 (1-2) ◽  
pp. 80-84 ◽  
Author(s):  
W Faschinger
Keyword(s):  
Ab Initio ◽  
Ab Initio Study

Carrier Transport in 2-D Materials: an Ab Initio Study

2019 ◽  
Author(s):  
Mathieu Luisier ◽  
Aron Szabo ◽  
Cedric Klinkert ◽  
Christian Stieger ◽  
Martin Rau ◽  
...  
Keyword(s):  
Ab Initio ◽  
Carrier Transport ◽  
Ab Initio Study

Сrude Plant Extracts Mediated Polyphenol Oxidation Reactions in the Presence of 3-Methyl-2-Benzothiazolinone Hydrazone for the Determination of Total Polyphenol Content in Beverages

2018 ◽  
Vol 15 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Maria A. Morosanova ◽  
Anton S. Fedorov ◽  
Elena I. Morosanova
Keyword(s):  
Hydrogen Peroxide ◽  
Ferulic Acid ◽  
Gallic Acid ◽  
Caffeic Acid ◽  
Crude Extract ◽  
Reaction Rates ◽  
Green Bean ◽  
Polyphenol Content ◽  
Total Polyphenol ◽  
Total Polyphenol Content

Background: The consumption of antioxidants, including phenolic compounds, is considered important for preventing the oxidative damage diseases and ageing. The total polyphenol content (TPC) is the parameter used to estimate the quality of plant-derived products. Methods: Phenol oxidase activity of green bean (Phaseolus vulgaris) crude extract (in the presence of hydrogen peroxide) and banana (Musa sp.) pulp crude extract has been studied spectrophotometrically using catechol, gallic acid, caffeic acid, ferulic acid, and quercetin as substrates. All studied compounds have been oxidized in the presence of green bean crude extract and hydrogen peroxide; all studied compounds except ferulic acid have been oxidized in the presence of banana pulp crude extract. Michaelis constants (Km) and maximum reaction rates (Vmax) have been determined for oxidation in the presence of green bean crude extract and hydrogen peroxide (Km are 3.8×10-4 M, 1.6×10-3 M, 2.2×10-4 M, 2.3×10-4 M, 1.4×10-4 M and Vmax are 0.046 min-1, 0.102 min-1, 0.185 min-1, 0.053 min-1, 0.041 min-1 for catechol, gallic acid, caffeic acid, ferulic acid, and quercetin, respectively) and for oxidation in the presence of banana pulp crude extract (Km are 1.6×10-3 M, 3.8×10-3 M, 2.2×10-3 M, 4.2×10-4 M and Vmax are 0.058 min-1, 0.025 min-1, 0.027 min-1, 0.015 min-1 for catechol, gallic acid, caffeic acid, and quercetin, respectively). The influence of 3-methyl-2-benzothiazolinone hydrazone (MBTH) on the oxidation reactions kinetics has been studied: Michaelis constants values decrease and maximum reaction rates increase, which contributes to the increase in sensitivity of the determination. Results: Kinetic procedures of Total Polyphenol Content (TPC) determination using crude plants extracts in the presence of MBTH have been proposed (time of analysis is 1 min). For gallic acid (used as a standard for TPC determination) detection limit is 5.3×10-5 M, quantitation limit is 1.8×10-4 M, and linear range is 1.8×10-4 - 1.3×10-3 M for green bean crude extract; detection limit is 2.9×10-5 M, quantitation limit is 9.5×10-5 M, and linear range is 9.5×10-5 - 2.4×10-3 M for banana pulp crude extract. Proposed procedures are characterized by higher interference thresholds for sulfites, ascorbic acid, and citric acid compared to pure enzymes (horseradish peroxidase and mushroom tyrosinase) in the same conditions. Compared with standard Folin-Ciocalteu (FC) method the procedures described in this work are also characterized by less interference and more rapid determination. Conclusion: The procedures have been applied to TPC determination in tea, coffee, and wine samples. The results agree with the FC method for tea and coffee samples and are lower for wine samples, probably, due to sulfites interference.

Ion solvation by dipolar aprotic solvents. An ab initio study

1987 ◽  
Vol 52 (1) ◽  
pp. 6-13 ◽  
Author(s):  
Petr Kyselka ◽  
Zdeněk Havlas ◽  
Ivo Sláma
Keyword(s):  
Ab Initio ◽  
Geometry Optimization ◽  
Molecular Structures ◽  
Dimethyl Sulphoxide ◽  
Ion Solvation ◽  
Interaction Energies ◽  
Ab Initio Study ◽  
Solvation Energies ◽  
Dipolar Aprotic Solvents ◽  
Complete Geometry Optimization

The paper deals with the solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions in dimethyl sulphoxide, dimethylformamide, acetonitrile, and water. The ab initio quantum chemical method was used to calculate the solvation energies, molecular structures, and charge distributions for the complexes water···ion, acetonitrile···ion, dimethyl sulphoxide···ion, and dimethylformamide···ion. The interaction energies were corrected for the superposition error. Complete geometry optimization was performed for the complex water···ion. Some generalizations are made on the basis of the results obtained.

An ab initio study of the structural and mechanical alterations of Ti-Nb alloys

2018 ◽  
Vol 124 (24) ◽  
pp. 245102 ◽  
Author(s):  
J. J. Gutiérrez Moreno ◽  
D. G. Papageorgiou ◽  
G. A. Evangelakis ◽  
Ch. E. Lekka
Keyword(s):  
Ab Initio ◽  
Ab Initio Study

Ab initio study of pentacene on Au(001) surface

2005 ◽  
Vol 589 (1-3) ◽  
pp. 8-18 ◽  
Author(s):  
Kyuho Lee ◽  
Jaejun Yu
Keyword(s):  
Ab Initio ◽  
Ab Initio Study
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