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Volume 29, Issue 2  (2020)

News:
M. Dobreva
Doc. Dr. Svoboda Beneva at 80 [In Bulgarian]

Full text: PDF (206 K)

147
Letters to the Editor:
M. Dobreva
Vigoria Foundation Awards for 2020 [In Bulgarian]

Full text: PDF (225 K)

152
Education: Theory & Practice:
M.R. Dokova-Koldanova, T.A. Kolarova, I.K. Lalkov
The Reflective Approach and Students' Understandings about Nature of Science in 10 - 11 Grade Biology Education [In Bulgarian]

Full text: PDF (569 K)

155
T. Tsankova
Study of Pupils' Opinion about the Use of Constructivist Methods in Teaching and Learning Biology [In Bulgarian]

Full text: PDF (324 K)

186
New Approaches:
P. Raychev
Sodium-Potassium Pump and Bioelectrogenesis in Teaching Physiology: Missconceptions and New Didactic Approach

Full text: PDF (287 K)

195
From the Research Laboratories:
A.M. Ghatole, M.K. Gaidhane, K.R. Lanjewar, K.M. Hatzade
Pharmacokinetics, Drug-Likeness, Medicinal Properties, Molecular Docking Analusis of Substituted Beta-Lactams Synthezied via [bmim][PF6]/[Et3NH]+[HSO4]-Catalized Coupling Reaction

Full text: PDF (877 K)

206
Personalities in Science:
B. Mutafschiev
Iwan N. Stranski: Myth and Man [In Bulgarian]

Full text: PDF (450 K)

245
Science and Society:
M. Slavova, R. Tomova
Hydrogen - Most Environmentally Efficacy Fuel [In Bulgarian]

Full text: PDF (403 K)

259
 

Khimiya, Volume 29, Issue 2(2020)

Khimiya. 29, 155-185 (2020) Author(s): M.R. Dokova-Koldanova, T.A. Kolarova, I.K. Lalkov:

Abstract.This study investigated the influence of the explicit reflective-based approach on students’ understandings about the nature of science (NOS) in the context of 10th -11th grade biology education. An instructional model was proposed on the ground of two major ideas: (1) teaching through explicit references to or discussion of NOS aspects („tentativeness”, „empirical basis”, “scientific method”, „theories/laws distinctions”, „creativity and imagination”, „socio-cultural influences”, „subjectivity”); (2) encouragement of students’ reflection on their own epistemological beliefs as they participated in resolving and discussing of socio-scientific issues, situated in a learning environment. The study was conducted with 24 high school students, who were taught using the instructional model, based on explicit reflective approach, for a period of 15 academic weeks. “Views on Nature of Science Questionnaire-Form C”, translated in Bulgarian, and follow-up semi-structured interview were used for identifying students’ target NOS views. The responses to the questions were grouped into three categories, articulated different NOS understandings: positivist, constructivist and intermediate. According to the data, the majority of students (≥ 50%) held positive views of 4 aspects of scientific knowledge („empirical basis”, „socio-cultural influences”, "subjectivity" and " theories/laws distinctions”) before the intervention, while only 5 learners had constructivist views on the „tentativeness” and the role of „creativity and imagination” in the science. The results of the whole study indicated that applying an explicit reflective approach significantly reduced students’ positivist understandings and encouraged their change towards intermediate and constructivist views of the nature of science.

Keywords: nature of science, understanding of nature of science, reflective approach, biology education

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Khimiya. 29, 186-194 (2020) Author(s): T. Tsankova:

Abstract.The article draws attention to the possibilities of project-based biology and constructivism.to change the traditional educational environment. There are significant differences between constructivist-based learning and traditional learning. The constructivist approach to teaching and learning in the natural sciences is applied to enable students to make own and meaningful connections between new and prior knowledge.

Keywords: constructivism; key competences; classroom environment

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Khimiya. 29, 195-205 (2020) Author(s): P. Raychev:

Abstract.Teaching and conceptualizing basic mechanisms underlying generation of resting membrane potential (RMP) is one of the starting and critically important points in all modern physiology courses and textbooks for students of medicine. Mastering concept on RMP and bioelectrogenesis is a basic precondition for students’ introduction into almost all fields of physiology, and particularly in physiology of excitable structures and sensory systems. Sodium-potassium pumps can be regarded as cells’ power plants which generate and maintain RMP. However, it is a strange paradox, taking into account importance of the subject, that one of the most widely-spread and persisting misconception among the students is just about the contribution of electrogenic effect (EE) of sodium-potassium pump (Na+/K+ pump) to the RMP. Fighting such critical misconceptions requires development and practical implementation of effective and specifically addressed didactic solutions in teaching-learning process of physiology.In the present report is proposed a new, compatible with active learning strategies, didactic model. It is based on quantifying specific contribution of electrogenic and non-electrogenic mechanisms of Na+/K+ pump to RMP. Implementation of the model can be done through Goldman-Hodgkin-Katz (GHK) and Mullins-Noda (MN) equations or through equations based on Millman theorem (also known as chord-conductance equations, CC). Newly developed model enables teaching staff to apply active learning strategies in this relatively complicated and abstract but very important part of physiology. Additional advantage of the model is that it allows demonstration, in a relatively simple and intuitive way, compatibility of MN equation with classical pump-leak model and limitations of GHK equation in conceptualizing bioelectrogenic processes in normal cells at steady state.

Keywords: medical education, active learning, resting membrane potential, electrogenic effect, sodium-potassium pump, Goldman-Hodgkin-Katz equations, Mullins-Noda equation, bioelectrogenesis.

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Khimiya. 29, 206-244 (2020) Author(s): A.M. Ghatole, M.K. Gaidhane, K.R. Lanjewar, K.M. Hatzade:

Abstract.Our examination planned to synthesize the azido β-lactam under reactive ionic liquids for new synthetic organic methodologies. These endeavors may provide more clarity to the analysis in the systems of natural responses utilizing ionic liquid as response media. The Schiff base witnesses quick responses with azido acidic acid in a [bmim][PF6]/[Et3NH]+[HSO4]- dissolvable framework, under mellow and unbiased response conditions to afford the corresponding azido β-lactam in high to quantitative yields. The library of substituted 3-azido-4-phenyl-1-(-phenylthiazol-2-yl) azetidin-2-one (3a-s) has screened antibacterial movement against clinically secluded Gram-positive bacteria, for example, Staphylococcus aureus, Gram-negative microbes Escherichia coli and Pseudomonas aeruginosa and for antifungal action against Candida albicans strains. Further, the synthesized compound has also assessed by a computational investigation by cooperation with the dynamic site of E150K from MRSA (PDB ID-4BL2). We present the new SwissADME web utensil that gives free access to a pool of quick yet reliable analytical models for physicochemical properties, pharmacokinetics, drug-likeness, and medicinal chemistry. Among them, in-house capable technique, for example, BOILED-Egg, iLOGP, and Bioavailability Radar, are readily available on the web.

Keywords: ionic liquid; azido β-lactam; MRSA; SwissADME; BOILED-egg; bioavailability radar

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Khimiya. 29, 245-258 (2020) Author(s): B. Mutafschiev:

Abstract.This text is written by Professor Boian Mutaftschiev (1932-2020). When Mutaftschiev joined the Department of Physical Chemistry of the University of Sofia, Professor Iwan Stranski, who established this University department in 1925, was in Germany without any possibility to came back in Bulgaria again. The meetings of the author with Prof. Stranski abroad are described in the present article.

Keywords: Physical Chemistry in Sofia, Department of Physical Chemistry, University of Sofia, Iwan Stranski, Iwan Stranski in Germany

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Khimiya. 29, 259-268 (2020) Author(s): M. Slavova, R. Tomova:

Abstract.Hydrogen can be obtained from the electrolysis of water by various renewable energy sources and stored until needed. Obtained from the most common chemical compound, hydrogen is the energy source with the potential to reduce the economy's dependence on oil. It is the environmentally friendly cleanest fuel because its only oxidation product is water, ie. no harmful products are formed. In the present work is considered the principle of action of so-called fuel cells in which hydrogen is oxidized by oxygen from the air. These are electrochemical cells in which chemical energy is converted into electrical energy. According to the principle of operation the fuel cells are three types: with proton-conducting electrolyte; with electron-conducting electrolyte and with dual membrane. Fuel cells are used in buildings for electricity and heating, as well as for transport. Vehicles with fuel cells are classified as zero emission transportation. The inclusion of the information in the in the course content will enrich students' knowledge of current environmental trends in greenhouse gas reduction.

Keywords: hydrogen, fuel cells, ecology trends, high school education

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