Soret driven thermosolutal convection in an inclined porous layer: search of optimum conditions of separation and validity of the boundary layer theory

In this paper we present an analytical and numerical study of Soret convection in an inclined rectangular porous layer saturated with a binary fluid and subject to uniform heat fluxes. In the problem formulation, the Darcy model is considered and the results are presented for wide ranges of RT (50 ≤ RT ≤ 1000), θ(0°≤θ≤180°) and φ(-1 ≤ φ ≤ 1) for Le = 10, where RT, θ, φ, and Le are the thermal Darcy-Rayleigh number, the cavity inclination, the separation parameter, and the Lewis number, respectively. An analytical solution, derived on the basis of the parallel flow approximation, is validated numerically by solving the full governing equations with a finite difference method. It is found that the heat transfer is more sensitive to the variation of the cavity inclination than to the separation parameter while the mass transfer sensitivity is essentially related to positive values of φ in a short range of θ. The thresholds of RT and φ from which the boundary layer approximations can be considered valid (with a maximum deviation of 5% for the numerical results) are determined; they are found to be dependent on θ. For positive values of the separation parameter, the boundary layer regime is reached at relatively lower values of RT

Novel 6-aryl-7-alkyl/aryl-[1,2,4]triazolo[4,3-a][1,3,5]triazine-5(6H)-thiones, processes for their preparation, characterization and evaluation of their in vitro antioxidant activity

ABSTRACT. A series of nine new 6-aryl-7-alkyl/aryl-[1,2,4]triazolo[4,3-a][1,3,5]triazine-5(6H)-thiones (2a-i) were synthesized by a reaction of N-triazol-3-yl imidates (1) with three different isothiocyanate derivatives (RNCS)  in refluxing toluene. The structures of the final heterocyclic compounds were confirmed by 1H-NMR, 13C-NMR, FT-IR, elemental analysis, and mass spectral analysis. The target compounds (2a-i) were in vitro screened for their activity as antioxidants using DPPH (2,2′-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing/antioxidant power) methods. The results revealed that some triazolotriazine-5-(6H)thiones exhibited antioxidant activity ranging from moderate to high. The obtained findings revealed that the triazolotriazine-5-(6H)thiones (2g, 2h, and 2i) have superiority among all compounds, It is obvious that the presence of a hydroxyl group in the structure is essential for the antioxidant properties and should be taken into consideration in further design of structures with potential antioxidant properties.                     KEY WORDS: Imidates, Isothiocyanates, Antioxidant, Triazole, DPPH, FRAP   Bull. Chem. Soc. Ethiop. 2021, 35(3), 565-572. DOI: https://dx.doi.org/10.4314/bcse.v35i3.

Novel 6-aryl-7-alkyl/aryl-[1,2,4]triazolo[4,3-a][1,3,5]triazine-5(6H)-thiones, processes for their preparation, characterization and evaluation of their in vitro antioxidant activity

ABSTRACT. A series of nine new 6-aryl-7-alkyl/aryl-[1,2,4]triazolo[4,3-a][1,3,5]triazine-5(6H)-thiones (2a-i) were synthesized by a reaction of N-triazol-3-yl imidates (1) with three different isothiocyanate derivatives (RNCS)  in refluxing toluene. The structures of the final heterocyclic compounds were confirmed by 1H-NMR, 13C-NMR, FT-IR, elemental analysis, and mass spectral analysis. The target compounds (2a-i) were in vitro screened for their activity as antioxidants using DPPH (2,2′-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing/antioxidant power) methods. The results revealed that some triazolotriazine-5-(6H)thiones exhibited antioxidant activity ranging from moderate to high. The obtained findings revealed that the triazolotriazine-5-(6H)thiones (2g, 2h, and 2i) have superiority among all compounds, It is obvious that the presence of a hydroxyl group in the structure is essential for the antioxidant properties and should be taken into consideration in further design of structures with potential antioxidant properties.&#x0D;                    &#x0D; KEY WORDS: Imidates, Isothiocyanates, Antioxidant, Triazole, DPPH, FRAP&#x0D;  &#x0D; Bull. Chem. Soc. Ethiop. 2021, 35(3), 565-572.&#x0D; DOI: https://dx.doi.org/10.4314/bcse.v35i3.8</jats:p