Browsing by Author "Piroeva I."

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    Effect of organic additives in citrate electrolyte on the properties of Ni-Co alloy
    (2015-01-01) Ignatova K.; Lilova D.; Piroeva I.
    The kinetics of independent and joined deposition of Ni and Co in citrate electrolyte in the presence of three types of additives: saccharine (SCH), urotropine (URT) and gelatine (GLT), is examined. Comparison is made between the chemical composition, the current cathodic efficiency (CCE) and the morphology of Ni-Co alloys depending on the type of the additive, both in constant potential mode (CPM) and in pulse potental mode (PPM). The study specifies the effect of GLT and SCH for formation of smooth, shiny, nanostructured Ni-Co coatings with average crystallite size less than 100 nm with a high CCE (about 80 % for SCH, and over 90 % for GLT), in both potential modes. The presence of SCH in the electrolyte with simultaneous application of PPM increases the content of Ni in the alloy to 25-30 mass % Ni. The optimum additive of SCH containing 0.5 - 1.0 g dm-3 is specified, wherein the electrolyte remains stable during continuous operation.
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    Effect of the electrodeposition conditions on the morphology and corrosion behavior of Ni-Co alloys part 1: Chemical composition, cathodic current efficiency, and morphology of Ni-Co alloys electrodeposited from citrate electrolyte
    (2016-01-01) Ignatova K.; Piroeva I.; Vladimitova-Atanasova S.
    Ni-Co alloys with varying cobalt content are electrodeposited in stationary potentiostatic mode employing citrate electrolyte, either with or without addition of saccharin (SHR) at different Ni/Co ratios and variable content of sodium citrate (Na3citrate) in the electrolyte. The changes in the microstructure, chemical composition and cathodic current efficiency of deposition (CCE) of Ni-Co alloys are studied. Scanning electron microscope, energy dispersive X-Ray and atomic absorbtion analysis are used to characterize the alloy coating.The alloy deposition is proved to be of an anomalous type. It is found that with the increase of the value of ratio Ni/Co in the solution from 1 to 5, the percentage of Ni in the Ni-Co alloy grows to 48 mass %, and the CCE decreases to about 70 %, whereas more fine-crystalline Ni-Co coatings (size of crystallites less than 100 nm) are deposited. The addition of SHR results in a strong decrease of CCE (up to 50 %), but also in formation of smooth and shimmering coatings with average size of crystallites much less than 50 nm. The coatings obtained from electrolyte with higher content of sodium citrate contain more Ni but are more coarse-crystalline, as the effect of the complexing agent is generally less pronounced in comparison with the case with SHR addition.
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    Fused Triazinobenzimidazoles Bearing Heterocyclic Moiety: Synthesis, Structure Investigations, and In Silico and In Vitro Biological Activity
    (2023-07-01) Anichina K.; Georgiev N.; Lumov N.; Vuchev D.; Popova-Daskalova G.; Momekov G.; Cherneva E.; Mihaylova R.; Mavrova A.; Atanasova-Vladimirova S.; Piroeva I.; Yancheva D.
    [1,3,5]Triazino[1,2-a]benzimidazole-2-amines bearing heterocyclic moiety in 4-position were synthesized. The compounds were characterized by elemental analysis, IR, 1H-NMR, 13C-NMR, and HRMS spectroscopy. The molecular geometry and electron structure of these molecules were theoretically studied using density functional theory (DFT) methods. The molecular structure of the synthesized fused triazinobenzimidazole was confirmed to correspond to the 3,4-dihydrotriazinobenzimidazole structure through the analysis of spectroscopic NMR data and DFT calculations. The antinematodic activity was evaluated in vitro on isolated encapsulated muscle larvae (ML) of Trichinella spiralis. The results showed that the tested triazinobenzimidazoles exhibit significantly higher efficiency than the conventional drug used to treat trichinosis, albendazole, at a concentration of 50 μg/mL. The compound 3c substituted with a thiophen-2-yl moiety exhibited the highest anthelmintic activity, with a larvicidal effect of 58.41% at a concentration of 50 μg/mL after 24 h of incubation. Following closely behind, the pyrrole analog 3f demonstrated 49.90% effectiveness at the same concentration. The preliminary structure-anti-T. spiralis activity relationship (SAR) of the analogues in the series was discussed. The cytotoxicity of the benzimidazole derivatives against two normal fibroblast cells (3T3 and CCL-1) and two cancer human cell lines (MCF-7 breast cancer cells and chronic myeloid leukemia cells AR-230) was evaluated using the MTT-dye reduction assay. The screening results indicated that the compounds showed no cytotoxicity against the tested cell lines. An in silico study of the physicochemical and pharmacokinetic characteristics of the novel synthesized fused triazinobenzimidazoles showed that they were characterized by a significant degree of drug-likeness and optimal properties for anthelmintic agents.
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    Fused Triazinobenzimidazoles Bearing Heterocyclic Moiety: Synthesis, Structure Investigations, and In Silico and In Vitro Biological Activity
    (2023-07-01) Anichina K.; Georgiev N.; Lumov N.; Vuchev D.; Popova-Daskalova G.; Momekov G.; Cherneva E.; Mihaylova R.; Mavrova A.; Atanasova-Vladimirova S.; Piroeva I.; Yancheva D.
    [1,3,5]Triazino[1,2-a]benzimidazole-2-amines bearing heterocyclic moiety in 4-position were synthesized. The compounds were characterized by elemental analysis, IR, 1H-NMR, 13C-NMR, and HRMS spectroscopy. The molecular geometry and electron structure of these molecules were theoretically studied using density functional theory (DFT) methods. The molecular structure of the synthesized fused triazinobenzimidazole was confirmed to correspond to the 3,4-dihydrotriazinobenzimidazole structure through the analysis of spectroscopic NMR data and DFT calculations. The antinematodic activity was evaluated in vitro on isolated encapsulated muscle larvae (ML) of Trichinella spiralis. The results showed that the tested triazinobenzimidazoles exhibit significantly higher efficiency than the conventional drug used to treat trichinosis, albendazole, at a concentration of 50 μg/mL. The compound 3c substituted with a thiophen-2-yl moiety exhibited the highest anthelmintic activity, with a larvicidal effect of 58.41% at a concentration of 50 μg/mL after 24 h of incubation. Following closely behind, the pyrrole analog 3f demonstrated 49.90% effectiveness at the same concentration. The preliminary structure-anti-T. spiralis activity relationship (SAR) of the analogues in the series was discussed. The cytotoxicity of the benzimidazole derivatives against two normal fibroblast cells (3T3 and CCL-1) and two cancer human cell lines (MCF-7 breast cancer cells and chronic myeloid leukemia cells AR-230) was evaluated using the MTT-dye reduction assay. The screening results indicated that the compounds showed no cytotoxicity against the tested cell lines. An in silico study of the physicochemical and pharmacokinetic characteristics of the novel synthesized fused triazinobenzimidazoles showed that they were characterized by a significant degree of drug-likeness and optimal properties for anthelmintic agents.