Browsing by Author "Milanova V."

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    Nanocomposites based on intermetallic nanoparticles template synthesized using different supports
    (2013-12-17) Milanova V.; Petrov T.; Denev I.; Markova I.
    A template synthesis of intermetallic (Cu-Sn, Ni-Sn) nanoparticles has been carried out using different supports through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of CuCl2.2H2O, SnCl2.2H2O, NiCl2.6H2O, respectively, at mass ratio Cu:Sn (Ni:Sn) = 40:60 at room temperature and atmospheric pressure. The obtained nanocomposites are of a type - inert matrix/Cu-Sn (Ni-Sn) nanoparticles. Porous carbon (C-foam), carbon powder (C-powder) and AlN-powder (commercial products) have been used as supports. The influence of the quantity of citric acid as a surfactant on the morphology of the Cu-Sn nanoparticles deposited on and inside the C-foam pores has been studied. A physico-chemical investigation of the prepared nanocomposites based on Cu-Sn (Ni-Sn) nanoparticles is carried out with SEM/EDS, and XRD analyses.
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    Study of carbon-based nanocomposites with intermetallic (Co-Sn, Ni-Sn) nanoparticles
    (2014-01-01) Milanova V.; Petrov T.; Chauvet O.; Markova I.
    Intermetallic (Co-Sn, Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of CoCl 26H2O, NiCl26H2O, and SnCl 22H2O at different mass ratios Co:Sn and Ni:Sn. Subsequently, carbon-based nanocomposites are obtained. A ``template`` technique which involves borohydride reduction of intermetallic nanoparticles on a support (carbon foam, carbon powder, graphite ) is used. Samples are studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The influence of the different supports used on the morphology, structure, phase composition and element composition of the synthesized composite materials is investigated. Phases, CoSn2 (Co:Sn = 1:2), Co3Sn2 (Co:Sn = 3:2), Ni3Sn 2 (Ni:Sn = 3:2), Ni3Sn (Ni: Sn = 3:1) are achieved. They are in correspondence with the phase diagrams of the Co-Sn and Ni-Sn binary systems. © 2014 Advanced Study Center Co. Ltd.
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    Synthesis and study of carbon-based nanocomposites with Co-Sn nanoparticles for electrode materials
    (2015-01-01) Milanova V.; Markova I.; Piskin M.; Stankulov T.; Petrov T.; Denev I.
    Intermetallic Co-Sn nanoparticles have been synthesized through a template borohydride reduction with NaBH4, using a carbon-containing support in a mixture of aqueous solutions of the corresponding chloride salts (CoCl2.6H2O and SnCl2.2H2O) at mass ratio Co:Sn = 35:65. The ratio is chosen in accordance with the Co-Sn binary system phase diagram. The ``template`` technique involves reductive precipitation of intermetallic nanoparticles on a support. Fluorinated graphite (CF) and graphite/β-cyclodextrin (Dx) hydrate have been used as supports. Subsequently, carbon polymer-based nanocomposites with Co-Sn nanoparticles have been obtained. The content of the polymer in the obtained nanocomposites varies between the samples. The reductive precipitation was carried out at room temperature and atmospheric pressure. Samples were studied by physic-chemical and electrochemical analyses. The morphology, structure, phase composition and surface element content of the prepared nanocomposites have been investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The nanocomposite morphology is typical for the alloy materials. CoSn2 and CoSn phases are formed according to the Co-Sn binary system phase diagram. The surface element composition has proven the existence of Co and Sn. Electrochemical study of these nanocomposite materials has been carried out by a cycling voltammetry. The samples are assembled in argon filled glove box and are electrochemically tested as electrode materials (anodes) in a Li-ion battery. The charge-discharge tests have shown that these nanocomposite materials, containing a CoSn2 phase, are characterized by a stable specific capacity after the 20 cycles, better cyclicibility and higher efficiency, as compared to the Co-Sn alloy. Their measured capacity is a reason to be an alternative replacement of the graphite electrodes in Li-ion batteries.
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    SYNTHESIS OF NEW TRIAZOLE AND THIADIAZOLE DERIVATIVES OF THE N,N’-DISUBSTITUTED BENZIMIDAZOLE-2-THIONE AND EVALUATION OF THEIR ANTITUMOR POTENTIAL
    (2022-01-01) Anastassova N.; Georgieva I.; Milanova V.; Tzoneva R.; Radev K.; Yancheva D.; Mavrova A.
    In the present study series of triazole-, thiadiazoleand thiosemicarbazone-benzimidazole hybrid compounds were synthesized as potential anti-cancer agents. In order to determine their antitumor potential and cytotoxic effect (via MTT assay) lung adenocarcinoma (A549) and breast cancer (MDA-MB-231) cell lines were examined. For detection of apoptosis induced by drug treatment, DAPI staining was performed in order to observe the apoptotic alterations in cell nuclei. It was found that the thiadiazole derivative 12 leads to the occurrence of micronuclei, suggesting genotoxic effect. Furthermore, a wound healing assay was performed in order to test whether any changes in cell motility occurred upon treatment with the newly synthesized hybrids, since both cell lines are examples of highly invasive tumours. The cell motility of MDA-MB-231 was impeded mostly by compound 12 (15 % of wound closure) and in A549 compound 9 reduced cell motility by 46 % compared to the control. The obtained results suggest that compound 12 possesses a promising anticancer effect.