Browsing by Author "Dimitrova M."
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Item A novel 1,8-naphthalimide probe for selective determination of Hg2+ in a wide pH window(2018-01-01) Krasteva P.; Dimitrova M.; Georgiev N.; Bojinov V.This paper reports the synthesis and photophysical investigation of a novel 1,8-naphthalimide fluorophore containing 2-amino-1,3,4-thiadiazole fragment at C-4 position. Absorption and fluorescence characteristics of the dye as a function of pH were investigated in water/ethanol (1:1, v/v) solution. It was found that the synthesized 1,8-naphthalimide did not show significant changes in the emission properties in a wide pH range. Furthermore the ability of the synthesized compound to detect cations was evaluated by the changes in its fluorescence intensity in the presence of metal ions (Co2+, Cu2+, Fe3+, Ni2+, Pb2+, Cd2+, Zn2+ and Hg2+). Only Hg2+, among the tested metal ions, was efficiently detected due to the aggregation caused quenching process. The results obtained indicate the potential of the novel compound acting as a fluorescent ``onoff`` switch for selective determination of Hg2+ in a wide pH window.Item Asymptotic properties of solutions of a class of impulsive differential equations of second order with a retarded argument(1997-01-01) Bainov D.; Dimitrova M.; Dishliev A.Some asymptotic properties are studied for the solutions of a class of impulsive differential equations of second order with retarded argument and fixed moments of impulse effect. Sufficient conditions are found for oscillation of all bounded solutions. © 1997, Department of Mathematics, Tokyo Institute of Technology. All rights reserved.Item Asymptotic properties of solutions of a class of impulsive differential equations of second order with a retarded argument(1997-01-01) Bainov D.; Dimitrova M.; Dishliev A.Some asymptotic properties are studied for the solutions of a class of impulsive differential equations of second order with retarded argument and fixed moments of impulse effect. Sufficient conditions are found for oscillation of all bounded solutions. © 1997, Department of Mathematics, Tokyo Institute of Technology. All rights reserved.Item Natural Zeolite-Cellulose Phosphate Nanocomposites: Preparation and Advance Electrochemical Study(2023-07-01) Tsacheva I.; Dimitrova M.; Gigova A.; Dimitrov O.; Uzun D.The scope of this research study is to investigated the green method for preparing and applying cost-effective and environmentally friendly electrocatalytic materials from natural zeolite (clinoptilolite) and cellulose phosphate using microwave irradiation. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX) and Brunauer-Emmett-Teller (BET), were used for the physicochemical characterization of nanocomposites. The newly obtained nanocomposites were studied electrochemically using cyclic voltammetry, linear sweep, galvanostatic measurements, and Tafel slopes. The results show that the obtained nanocomposites can find applications as promising electrocatalytic materials for seawater electrolysis for hydrogen production at oxygen evolution reactions (OER) and for electrochemical purification of organic pollutants.Item Oscillation of the solutions of a class of impulsive differential equations with a deviating argument(1998-01-01) Bainov D.; Dimitrova M.; Dishliev A.Sufficient conditions are found for oscillation of all solutions of a class of impulsive differential equations with deviating argument. ©1998 by North Atlantic Science Publishing Company.Item Oscillation of the solutions of a class of impulsive differential equations with a deviating argument(1998-01-01) Bainov D.; Dimitrova M.; Dishliev A.Sufficient conditions are found for oscillation of all solutions of a class of impulsive differential equations with deviating argument. ©1998 by North Atlantic Science Publishing Company.Item Oscillation of the solutions of impulsive differential equations and inequalities with a retarded argument(1998-01-01) Bainov D.; Dimitrova M.; Dishliev A.Sufficient conditions for oscillation of all solutions of a class of impulsive differential equations and inequalities with a retarded argument and fixed moments of impulse effect are found. © 1998 Rocky Mountain Journal of Mathematics. © 1998 Applied Probability Trust.Item Oscillation of the solutions of impulsive differential equations and inequalities with a retarded argument(1998-01-01) Bainov D.; Dimitrova M.; Dishliev A.Sufficient conditions for oscillation of all solutions of a class of impulsive differential equations and inequalities with a retarded argument and fixed moments of impulse effect are found. © 1998 Rocky Mountain Journal of Mathematics. © 1998 Applied Probability Trust.Item Synthesis, chemosensing properties and logic behaviour of a novel ratiometric 1,8-naphthalimide probe based on ICT and PET(2016-08-01) Georgiev N.; Dimitrova M.; Todorova Y.; Bojinov V.A novel fluorescence sensing 1,8-naphthalimide designed on the ``receptor1-fluorophore-spacer-receptor2`` model is synthesized and investigated. The novel probe comprising aminotriazole and hydroxyphenyl substituents is capable to operate simultaneously via ratiometric ICT and PET signalling mechanism. The synthesized compound shows excellent signalling properties towards protons, hydroxyl anions and Cu2+ ions. Due to the remarkable fluorescence changes in the presence of these analytes the system is able to act as a two output combinatorial logic circuit with three chemical inputs. Input3-Disabled XNOR, INHIBIT and IMPLICATION logic gates were obtained. Because of the parallel action of disabled-XNOR and disabled-INHIBIT gates a magnitude digital comparator with disable capability is achievable.