Browsing by Author "Dragoi, Elena-Niculina"

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    Ammonia free catalytic reduction of nitric oxide on Ni-embedded graphene nanostructure: A density functional theory investigation
    (2023) Genc, Ali Emre; Akca, Aykan; Karaman, Ceren; Camarada, Maria B.; Dragoi, Elena-Niculina
    In this study, the catalytic reduction reaction of NO (directly) without the presence of ammonia (NH3) was studied on the Ni-embedded graphene (Ni@GN) layer using periodic Density Functional Theory (DFT) calculations. Ni-embedded graphene surface can be synthesized experimentally and it is predicted that it will cost much less than single crystal surfaces due to the economic usage of the transition metal atoms. First of all, by optimizing the geometric structure of the Ni@GN layer, crucial geometric features and electron density differences (EDD) were obtained. Based on the different adsorption configurations of NO molecule, the reduction reaction was investigated by Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) based mechanisms. Finally, N2O degradation was analyzed in detail. It is shown that the Eley-Rideal model is a more dominant mechanism on the Ni@GN surface than the other model. In addition, all proposed reaction pathways for NO reduction are exothermic. This information can be used for the research and development of graphene-based materials for NO reduction; paves the way for finding new Ni-based catalysts based on active single transition metal atom embedded on different kind of defects.
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    Green and accurate analytical method for monitoring atropine in foodstuffs as a contaminant and in pharmaceutical samples
    (2023) Hamidian, Yasamin; Mostafazadeh, Reza; Erk, Nevin; Karaman, Ceren; Camarada, Maria Belen; Dragoi, Elena-Niculina
    Nowadays, atropine has been highlighted because of its anticholinergic effect and contamination in foodstuffs, and therefore, using an accurate and sensitive method for its determination is crucial in human health and food safety. In this study, a novel spectrophotometric method was suggested for the swift quantification of atropine. The proposed method was based on the formation of red ion-pair complexes between the drugs and the cyanidin reagent extracted from red cabbage ( RC). In this regard, the effect of pH, time, and temperature was explored and optimized. According to the results, atropine determining was shown the best performance in pH 2 at room temperature in 30 min. In addition, this method revealed linear responses from 10 nM to 1 mu M of atropine with limit of detection (LOD) value of 0.0019 mu M. Also, the selectivity value of this method was investigated in the presence of some drugs with the same structure and some common species as interferences. The results verified no interference in atropine determination, as well as, the results obtained from repeatability (RSD. 2.56) of this method were acceptable. Moreover, the applicability of this method was tested in buckwheat and atropine sulfate as food and pharmaceutical real sample, respectively. Real sample analysis was carried out with the standard addition method and the recovery percentages (96.54-104.87%) witnessed the high capability of this method in atropine determination.