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The binary zinc telluride with the s-elements were synthesized by solid-phase method from the tellurium (IV) oxides, zinc and sodium (potassium) carbonates. The types of symmetry, unit cell parameters, X-ray and pycnometric densities of the synthesized compounds were determined by X-ray analysis.
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Conductive cuprate BSCCO (2212) ceramics, exhibiting superconductivity a low temperatures (80 – 100К) can find other applications as well, such as an additive in the zinc electrode of nickel-zinc batteries. Ni-Zn cells are a potential cheaper alternative to replace toxic nickel-cadmium batteries. The positive effect of cuprate ceramic additives has been previously demonstrated. The study, presented here is focused on the electrochemical characterization of Bi2Sr2CaCu2Ox (BSCCO 2212) nanocomposite conductive ceramics as an additive to the zinc electrode at 25oC and 50oC in an alkaline electrolyte containing KOH and Na3PO4. Three coin type electrodes (15mm in diameter) were investigated by Electrochemical Impedance Spectroscopy measurements by a Bio-logic SP-200 potentiostat in a wide frequency range (106 - 0.1 Hz). The tests were performed in a three-electrode electrochemical cell with different negative electrodes – one with “classic” conductive carbon additive, another with BSCCO 2212 additive, and the third without any additives (only ZnO). The obtained impedance spectra are compared and equivalent circuit models are proposed.
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The calibration of method for determination of phthalates by means of GC/MS was done. The obtained working range for different phthalates is as following: DBP 58.8 – 1175,3 ppb; BBP 75,2 – 1504,6 ppb; DEHP 72,7 – 1454,2 ppb; DOP 59,1 – 1182,2 ppb; DINP 484,5 – 9690,3 ppb; DIDP 573,9 – 11477,0 ppb. Dicyclohexylphtalate (DICHP) was selected as an internal standard. Hexane is used as a solvent for preparation of standard solutions of phthalates.
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A series of 4-(substituted benzylidene-amino)-2,3-dimethyl-1-phenyl-3-pyrazoline-5-ones (3a-l) was obtained using sonochemical assisted reaction. The synthesized Schiff bases were evaluated for their antiviral, antibacterial, anticandida, DPPH scavenging and anti-tyrosinase activities in vitro. The antimicrobial screening results revealed that amongst the tested imines, compound 3l appeared to be а promising one (with a minimal inhibitory concentration 47 ug/ml). The most potent DPPH scavengers were azometines 3a and 3g. No significant inhibition on the monophenolase activity in vitro of mushroom tyrosinase was observed.
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Colloidal solutions of ~2 nm CdSe nanoparticles have been obtained by electrosynthesis with simultaneous extraction into p-xylene. The effect of electrolyte composition on the structure of electrodeposited CdSe nanoparticles has been established, their absorption and photoluminescence spectra have been analyzed. Exciton absorption of light by synthesized CdSe nanoparticles splits into three bands, which is characteristically for the small CdSe nanoparticles. Photoluminescence excited at wavelengths corresponding to curve bending decreases in intensity within the 350 -550 nm region with a maximum of 430 nm. This fact indicates on the formation of small (~ 2 nm) of CdSe nanoparticles in the process of electrosynthesis as well. Studies have shown that by the proposed method of electrochemical synthesis it is possible to obtain nanoparticles that are promising for the creation of optical liquid–crystalline composites.
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The previously reported 6-amino-4-(4-chlorophenyl)-3-methyl-1,4-dihydropyrano [2, 3-c] pyrazole-5-carbonitrile 1 was prepared and utilized as a precursor for novel heterocycles such as Benzoxazinone 4, Pyrazolopyranopyrimidines 8, 9, 12, 13 and 20 tetrazolopyrimidine 15 and triazolopyrimidine 16 with anticipated antimicrobial activity. The structural features of these novel heterocycles were characterized and confirmed by their spectral analysis as well as elemental analyses.
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The present study seeks the connection between reflection as a specific process and emotional competence of teachers who work with children with special needs. Pedagogical reflection as a personal and pedagogical trait of special pedagogues and its relation to their emotional competence as a part of their descriptive profile has a great importance for the quality of their professional activity and its results. The use of concept of social and emotional competence of special pedagogues as a theoretical ground for the stimulation of personal development appears to be effective with regard to the search of new solutions in the challenges of their professional life.
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Adult education performs important functions related to the implementation of the modern philosophies of lifelong learning and life-wide learning. This requires establishing a particular type of educational management – the management of adult education and training of specific managers – those responsible at different levels for managing the sector, the institutions and the services for adult education – known collectively as “adult education managers.” To perform successfully their functions related to the management of the system (sector) of adult education and of the institutions for formal and non-formal education, which offer educational services for adults and carry out the process of adult education, these managers need to acquire and develop a specific competency (or a set of competencies) and a specific managerial culture. The author presents arguments supporting the need for training such managers. The parameters of their managerial culture are outlined in terms of its content: managerial competence, managerial values, managerial beliefs and convictions as well as managerial behavior. A special emphasis is placed on the managerial competence of adult education managers regarded as the sum of competencies related to the management of the organization and educational activities in general (“production management”), human resource management, and operations management (the set of specific activities of all units and all people employed directly or providing and facilitating the process of adult learning and the functioning of the institutions offering it).
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The paper presents the main results of the work of an international group of students in the frames of the research project “Geometry Scrabble in Cloud”. The study consisted in creating and solving problems that were generalizations and natural analogues of a starting problem. It applied analytical geometry methods and was software supported by GeoGebra, Geometer’s Sketchpad and Maple. As a result various problems were created leading to loci like Euler line, curves of second degree and also curves of higher order.
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The paper is dedicted to the problems of the mathematical education in German taking place in the Technical University, Sofia. It focuses on the homework as an integral part of the learning process. The need of considering the suggested problematics is justified: the lesrner should be able to use literaure in German, to express him/herself correctly in writing and orally, and should be capable in transfering mathematical knowledge; at the same time the tasks which the instructor faces are connected with the solution of linguistic, methodological and procedural problems appearing in the mathematical education in German.
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The paper proposes possibilities to solve some groups of logarithmic equations by the help of the computer program Excel. The goal is to improve the capacities and to increase the interest of students studying mathematics in the secondary school.
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The paper describes some properties of two notable points inthe convex quadrilateral, which naturally generalize the circum-center and theorthocenter of the inscribed quadrilateral.
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There are four backbones to analyze time-series in general and forecast time-series for financial markets: Chaos-theory, Fuzzy logic, Neural networks and Genetic algorithms. The first one is considered in (Magenreuter, 2016a), while the second one – in (Magenreuter, 2016c) and the third one – in (Magenreuter, 2016b). The present paper is dedicated to the fourth backbone including promising outcomes in financial markts.
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The article analyses the results of a project, witch was realized with a leading team of lecturers from Sofia University “St. Kliment Ohridsky” and another seven Bulgarian higher schools.The text contains methodology and technology of professional-pedagogical training of 4500 Bulgarian teachers at national level. Teachers are from the primary education system.It presents also a developed training package of: a teacher’s handbook/ handbook, a teacher’s manual, basic and additional instructional materials on intercultural education. The training is conducted in two modules: attendance and distance. The results of the 227 trainings conducted in all regions of the Republic of Bulgaria are discussed.It analyses how these results influence the new law in the Republic of Bulgaria on pre-school and school education and the accompanying state educational standards.
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On the occasion of the anniversary, the author not only reminds the cultural and pedagogical heritage of Angel Uzunov from Rakitovo but also tries to update the idea of the scientific potential of educational practice in the “living” life without intermissions of the social pedagogue. And on the “background” of the deinstitutionalization of Labor-educative School – and to protect, however, the right of children to be what they are; to act together (“we”; “our class”) and to dream courageously.
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The article discusses the key events leading to the ideation, initiation, and establishment of the first programming contests for high school students in Bulgaria. The competitions preceding the First National Olympiad in Informatics (NOI) are presented in detail. More specifically, they include the programming contests, initiated by the author and held in Shoumen, Plovdiv and Pazardjik in 1982, 1983, and 1984 respectively. At the time, the main programming language used was FORTRAN for IBM/360 compatible computers. Next, the first NOI is discussed at length. Some of the subsequent NOIs are also outlined. The paper also includes facts about the Winter Mathematics Competitions and the high school student competitions held during the Spring Conferences of the Union of Bulgarian Mathematicians. A brief historical data about the Spring Tournament in Informatics is also presented. Due to its factual nature, the article contains an extensive list of references, including text excerpts, citations, pictures, and other relevant materials, supporting the historical facts related to the competitions in informatics.
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The International Mathematical Olympiad is one of the respectable events and one of the most long-lived international educational and scientific competitions. It is the largest, oldest and most prestigious scientific Olympiad for high school students. The 59th edition of the event took place in Cluj-Napoca, Romania, 3–14 July 2018. The present paper is dedicated to the sixth problem on the Olympiad paper. A detailed analysis of the problem is proposed in a methodological way, which will be useful for students and teachers in the preparatory process for future participations in mathematical competitions.
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The paper proposes to include possibilities of the experimental environment of the program Excel in varying the problem solving of some groups exponential equations by secondary students.
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The article structures and systematizes knowledge rationally, which adaptively correlates the managing and self-managing activity of learners. The contemporary requirements for intensification today impose developing learning potential to the highest degree. In line with these requirements, there is a need to offer possibilities for developing the lecture as a basic form of instruction within the University.
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