On the Road [In Bulgarian]
Development of the University Physical Chemistry in Two Historic Epochs [In Bulgarian]
Abstract. The development, after its establishment in 1925, of the Department of Physical Chemistry of the University of Sofia during two epochs of our state â€“ the Kingdome of Bulgaria and the Peoples Republic of Bulgaria â€“ has been shortly reviewed. During these 65 years the department has been consecutively headed by Prof. Ivan Stranski, Prof. Rostislav Kaischew and Prof. Alexei Scheludko. The merits of these great Bulgarian scientists for the Department as well as for the erection of the Bulgarian physicochemical scientific school, including its composite part â€“ the Bulgarian colloid scientific school, have been underlined.
Keywords: Department of Physical Chemistry, University of Sofia, Kingdom of Bulgaria, Peoples Republic of Bulgaria, Ivan Stranski, Rostislav Kaischew, Alexey Scheludko
Pycknometric Evaluation of Crystallinity and Porosity in Pyroxene Glass-Ceramics from Industrial Wastes [In Bulgarian]
Abstract. Glass-ceramics are polycrystalline materials, containing amorphous and crystal phases and obtained by controlled crystallization of glasses with suitable compositions. The parent batch is melted, the melt is formed and thus prepared samples partially crystallize at secondary heat-treatment. The crystallization process can be controlled by addition of appropriate nucleating agents in the glass compositions. The evaluation of an optimal thermal cycle and crystallinity of the material are very important, since they control the main properties of glass-ceramics. The aim of present work is to investigate the evolution of crystallinity in two iron-rich glass-ceramics by metallurgical wastes using non-traditional pycnometric method. After the crystallization both glasses form similar pyroxene phase, but due to different compositions and nucleation behaviors their crystallinity and morphology are quite diverse.
Keywords: crystallinity, density, glass-ceramics, industrial wastes
A. Kamusheva, A. Karamanov
The Bulgarian Physicochemical Tradition and the Institute of Physical Chemistry „Academician Rostoslaw Kaischew“
Abstract. The paper traces out the foundation and establishment of the Institute of Physical Chemistry (IPC) at Bulgarian Academy of Sciences as one of the leading institutions in the field of physical chemistry in Bulgaria. The main thematic areas of research are specified and their development over more than 50 years is followed. World-recognised contributions in fundamental and applied research of IPC researchers are pointed out. Data for the publication activity of the Institute and its impact in the scientific literature are presented. The frames of the contemporary research activities of IPC are outlined.
Keywords: physical chemistry, phase formation, crystal growth, electrocrystallization, galvanic coatings, thin liquid films, colloid systems, electrooptics
Letters to the Editor
Geographic Coordinates and Attitudes of Synoptic Stations in Bulgaria [In Bulgarian]
Education: Theory & Practice
Historical Roots and Development of Constructivism [In Bulgarian]
Abstract. The essential core of constructivist theory of learning is that knowledge is not transmitted and passively received, but rather, is the result of active cognizing by the individual. Learners transform information and construct new knowledge from their own previous knowledge and experiences. The conceptual core of constructivist learning is that learners actively learn through interaction with each other, with their teacher and through hands-on activities, discovery and inquiry. The constructivist ideas have roots that extend back to the antiquity philosophers and medieval thinkers and develop into an epistemological philosophical theory. Mainly due to the works of Jean Piaget, Lev Vygotsky, John Dewey and their successors constructivism becomes a leading educational approach and acquires great popularity as a way of organization of education in the last decades of the 20th century. The school education in the Third Bulgarian Kingdom (1878-1946 Ð³.) is dominated by liberal European ideas. Initially, it is influenced by Herbartâ€™s educational conception. Later, in the first decades of the 20th century some ideas of the educational reform movements like Deweyâ€™s views of experiential education that students should learn through practice, enter and spread out in Bulgaria. The growing number of books and articles on constructivism shows that the constructivist approach in education has become a modern educational paradigm which is implemented in the classroom as a constructivist learning environment.
Keywords: constructivism, theory of learning, science education
Happy Numbers: Play as a Tool for Learning and Inventing of Problems [In Bulgarian]
Abstract. The paper discusses a popular game within an elementary school in Sofia, invented by one of its students. It suggests an approach to introduce an Android programming for kids on the basis of the game, how new mathematical problems could be invented and solved by Excel functions and computations and demonstrates first steps in doing research in elementary mathematics. A happy number is defined as a four-digit number of a car plate in Bulgaria, where an arithmetic operation of the first two digits equals the result of another (or same) arithmetic operation of the last two digits. A mobile app simulating the game is developed and the longest consecutive raw of happy numbers is found. Additional problems are formulated and suggestions are provided to teachers how to use this and other similar games to develop research interests and creative mathematical skills.
Keywords: arithmetic skills, games, coding for kids, calculative problem solving
Interdisciplinary Project for Enhancing Students’ Interest in Chemistry
Abstract. A student research project for sampling and analysis of drinking water from different Bulgarian regions has been parallel incorporated into analytical and organic courses at the second level of high engineering education in Bulgaria. The degree of quality of drinking water has been evaluated in five cities from different Bulgarian regions: Stara Zagora, Gorna Oryahovitsa, Parvomai, Dupnica and Sofia. The students analyzed water samples for pH, hardness, organic compounds, sodium, potassium and heavy metals ions like cadmium, copper, iron, lead and manganese using titrimetric methods, atomic absorption and atomic emission spectrometry, potentiometry and voltamperometry. The article also describe pre-lab activities related to the â€œwater quality projectâ€ in order to increase student motivation, independence, and critical thinking skills. Students have been motivated to perform the seminar and practical work and get used to an approach often used in the chemical engineeringâ€™ practice. Students have been explored parameters concerning water quality from different sources and had an opportunity to evaluate the data critically and to answer the pre-lab questions. Based on student results the â€œwater projectâ€ became overwhelmingly popular with students while challenging them to think critically and work independently on problem solving tasks. Thanks to the â€œwater quality projectâ€ we found that the studentâ€™s willingness to carry out a scientific work is increased. The students become more motivated and committed to the learning process.
Keywords: problem solving, drinking water project, analytical chemistry, organic chemistry
S. Georgieva, P. Todorov, Z. Genova, P. Peneva
Assessment of the Perceptions of the Learning Environment in University Groups [In Bulgarian]
Abstract. The studies of student perceptions of learning environment supports the efforts of teachers to develop more effective approaches to design and evaluation of learning in high schools. This article presents the validation and the use of a modified version of the research instrument „Survey research of constructivist learning environment (CLES)“ in Technical University – Sofia. The questionnaire evaluates perceptions of learners of six psychological dimensions: the importance for student, scientific uncertainty, critical voice, â€œstudent â€“ teacherâ€ interaction, interaction between students, attitudes. In this version of the survey the cognitive focus is extended with scale „Attitudes“, including statements that ask students for their preconception of the group and its level as well as its impact on their interest and satisfaction. After applying of different approaches to training in the spirit of constructivist ideas, the survey was conducted with 40 students from the bachelorâ€™s program „Heat“. The results show that all they perceive the learning environment in the course in Environmental Engineering as fully constructivist environment. The study demonstrates high internal consistency of the different categories and the possibility of the actual form of the questionnaire to distinguish between perceptions of students in small groups and itâ€™s practical viability in order to assessment the constructivist transformation in universities.
Keywords: professional education, constructivist learning environment survey, engineering ecology, attitudes
N. Ilieva, E. Boiadjieva