|Education: Theory & Practice:|
|R. Tomova, P. Galcheva, I. Trajkov, A. Hineva, S. Grigorova, R. Slavova, M. Slavova|
Chemometric Analysis in School Life in Varna
Full text: PDF (651 K)
|Y. Kiryakov, I. Hadjiali, D. Grozev|
The Attitudes of 13-14-Year-Old Students Towards Sciences in Non-Formal Education [In Bulgarian]
Full text: PDF (407 K)
|A. E. Burns, N. G.Burns, C. Kramer|
An Analytical Experiment Using Beer's Law for a Mixture of Two Dyes
Full text: PDF (396 K)
|Hamam Nabil, Sari Fouad, Ferrahi Mohammed Issam, Belbachir Mohammed|
Synthesis of Poly(tetrahydrofuran-co-epichlorohydrin) Using an Ecologic Catalyst Montmorillonite (Maghnite-H+)
Full text: PDF (749 K)
|A. A. Wasim, M. N. Khan, M. F. Wahab, S. Fazal-ur-Rehman|
Construction of Job's Plot in Case of High Spectral Overlap between the Reactants and the Complex: Application of Multuwavelrngth Linear Regression Analysis Using the Cu-EDTA System
Full text: PDF (932 K)
A New Easy Method for Assigning Absolute Configuration without the Use of Models
Full text: PDF (377 K)
Equations Used in Introduction the Concept of Resting Membrane Potential in Modern Textbooks of Human Physiology: Traditions and Alternatives
Full text: PDF (540 K)
|From the Research Laboratories:|
|D. Kumar, A. Kumar|
Spectral, Biological, Magnetic and Conductance Studies on the Coordination Compounds of a Newly Synthesized Thiazolidin-4-One
Full text: PDF (410 K)
|History and Philosophy of Science:|
The Cycles of Krebs [In Bulgarian]
Full text: PDF (1362 K)
From the Principle of Least Action to the Conservation of Quantum Information in Chemistry: Cane One Generalize the Periodic Table
Full text: PDF (337 K)
|B. V. Toshev|
Post Stamp for the Periodic Table of Mendeleev [In Bulgarian]
Full text: PDF (749 K)
Interdisciplinary Integration in Secondary School [In Bulgarian]
Full text: PDF (325 K)
Khimiya, Volume 28, Issue 4(2019)
Khimiya. 28, 431-444 (2019) Author(s): R. Tomova, P. Galcheva, I. Trajkov, A. Hineva, S. Grigorova, R. Slavova, M. Slavova:
Abstract.In this paper, the authors’ collective is presenting a questionnaire, designed and tested by them for the regular evaluation of the educational environment in high schools. It consists of 50 multiple choice questions about quality of learning and relations between school children and teachers. The questionnaire was tested on the students of three high schools in Varna. It was distributed to male and female students of the 9th, 10th and 11th grades. The data set consists of 693 objects − schoolboys and girls characterized by their answers to 50 questions each one ranked by values from 1 to 5. Non-hierarchical cluster analysis was applied to find patterns of similarity between the questions or between the pupils. The results verified the constructive value of the questionnaire as a method of evaluation of the educational environment in high schools.
Keywords: questionnaire, eucational environment, high school, cluster analysis
Khimiya. 28, 445-455 (2019) Author(s): Y. Kiryakov, I. Hadjiali, D. Grozev:
Abstract.This paper presents the results and their analysis of a recent attitude questionnaire, intended to measure the attitude of 13-14-year-old students towards science in non-formal educational framework. The questionnaire was filled out by students, participating in the Summer academies (July-August 2018) of University for Kids Foundation in Drenta, Elena Municipality, Veliko Tarnovo District of Bulgaria. The main tool of the research is a specially constructed atitude questionnaire, which includes 8 questions with open - and close-ended questions. The participating 40 students are from all over Bulgaria.
Keywords: attitudes towards science; non-formal education; science education
Khimiya. 28, 456-459 (2019) Author(s): A. E. Burns, N. G.Burns, C. Kramer:
Abstract.This is a short communication of an inexpensive and safe experiment used in Analytical Chemistry. The experiment uses the idea of Beer’s law from a Freshman Chemistry Laboratory course for one material, where the absorption of light changes with the amount of material. However, in this experiment, it is expanded for two materials. Plus, since both materials are dyes and usually readily available in a College or University, it makes it both affordable and easy to use.
Keywords: Beer’s law, analytical laboratory, visible spectroscopy
Khimiya. 28, 460-474 (2019) Author(s): Hamam Nabil, Sari Fouad, Ferrahi Mohammed Issam, Belbachir Mohammed:
Abstract.The copolymerization of Tetrahydrofuran (THF) with Epichlorohydrin (ECH) catalyzed by efficient and environmentally friendly catalyst called Maghnite-H+ was investigated , in the presence of a natural Algerian montmorillonite clay modified H2SO4, known as Maghnite-H, as proton source, a non-toxic and an efficient catalyst for cationic polymerization of many vinylic and hetero-cyclic monomers, this ecological catalyst replaces usual toxic catalysts such as Lewis and Bronsted acids ,the oxonium ion of tetrahydrofuran (THF) and (ECH) propagated the reaction of copolymerization, the operating conditions were opted in order to obtain a maximum yield of the linear polymer and a high average molecular mass as well. We have studied the kinetic of the reaction by the effect of the time, the temperature, the amount of Maghnite-H+ and the proportion of monomers according to the changes in yield and the intrinsic viscosity, the structure of polymers obtained was confirmed by IR analysis. 1H NMR, the average molecular mass and the polydispersity indices were determined by GPC, after these kinetic studies and analyzes obtained, it is possible to propose at the end a reaction mechanism of the copolymerization.
Keywords: green catalyst, tetrahydrofuran, epichlorohydrin, montmorillonite, copolymerization
Khimiya. 28, 475-484 (2019) Author(s): A. A. Wasim, M. N. Khan, M. F. Wahab, S. Fazal-ur-Rehman:
Abstract.Job’s method is extensively used to determine the stoichiometry of complex ions both in the field of education and research. However, the shape of the Job’s plot generally does not match to what is shown in the textbooks due to simultaneous absorption by other species involved in the equilibria. The conventional correction method deals the problem by assuming that no reaction would have occurred among the reactants and thus uses their formal concentrations for the correction of empirical data. The assumption is contradictory as, in solution equilibria, formal concentrations differ substantially from the respective equilibrium concentrations. Alternatively, multiwavelength linear regression analysis is used to determine the equilibrium concentrations of reactants in the system. The two correction methods, when applied on Cu-EDTA system, showed a significant difference between them. The comparative study is designed to evaluate the correction methods. Moreover, Microsoft Excel® was incorporated to transform tedious correction into quick and interesting processing of data.
Keywords: Job plot, continuous variation, absorbance Correction, stoichiometry
Khimiya. 28, 485-491 (2019) Author(s): R. Ramajayam:
Abstract.Four rules of thumb were developed to find the absolute configuration of a molecule without using any stereo model or hand analogies. This method will be a boon for students who are unable to visualize a three-dimensional structure or any model. A maximum thirty seconds is required to assign absolute configuration by using this method.
Keywords:chirality,absolute configuration, stereo model
Khimiya. 28, 492-504 (2019) Author(s): P. Raychev:
Abstract.In the system of medical education physiology is a discipline of key importance based on very dynamic field of scientific knowledge. Permanent emergence and accumulation of new facts and concepts make teaching of physiology challenging task where success and effectiveness are highly dependent on abilities of teaching staff and authors of textbooks constantly to evaluate, re-evaluate and improve teaching approaches, learning objectives and sometimes even to revise whole paradigms in organizing and prioritizing essential parts of the curriculum. Resting membrane potential (RMP) is a concept of critical importance in physiology and particularly in physiology of excitable structures. Equations quantitatively characterizing RMP are widely used in teaching practice as a tool bridging the gap between fundamental biophysical phenomena and complex physiological processes. Use of different equations in introduction the concept of RMP in modern teaching literature is studied and critically evaluated. Alternative approaches are discussed in search for improvement and optimization of traditional methods of teaching resting membrane potential in courses and textbooks of human physiology. Study is based on the review and content analysis of different editions of more than 25 modern textbooks of human physiology.
Keywords: medical education, physiology teaching, resting membrane potential, Goldman equation, Mullins-Noda equation, chord-conductance equation, sodium-potassium pump
Khimiya. 28, 505-514 (2019) Author(s): D. Kumar, A. Kumar:
Abstract.A dry benzene solution of the Schiff base, N-(2-hydroxyphenyl)-3'-carboxy-2'-hydroxybenzylideneimine upon reacting with mercaptoacetic acid undergoes cyclization and forms N-(2-hydroxyphenyl)-C-(3'-carboxy-2'-hydroxyphenyl) thiazolidin-4-one, LH3 (I). A MeOH solution of I reacts with CoII and CdII ions and forms the monomeric coordination compounds, [Co(LH)(MeOH)3](II) and [Cd(LH)(MeOH)](III). The coordination compounds have been characterized on the basis of elemental analyses, molar conductance, molecular weight, spectral (IR, reflectance, NMR) studies and magnetic susceptibility measurements. I behaves as a dibasic tridentate OOS donor ligand in these compounds. The compounds are non-electrolytes (M = 5.1-7.8 mho cm2 mol-1) in DMF. A tetrahedral structure for III and an octahedral structure for II are suggested. The ligand (I) and its coordination compounds shows antibacterial and antifungual activities towards bacteria, E. Coli. (Gram Negative) and S. Aureus (Gram Positive) as well as towards fungus, Candida Albicans.
Keywords: thiazolidin-4-one, coordination compounds, magnetic susceptibility, magnetically dilute, strong field and covalent character
Khimiya. 28, 515-524 (2019) Author(s): I. Kuleff:
Abstract.In the present paper the idea about the cycles discovered by Dr. Hans Krebs is given. The career of Dr Krebs in Germany and England is outlined and his cycles are described in details. It is given also the evaluation of his discovery both about the life and development of the biology as well.
Keywords: Krebs cycles, biography
Khimiya. 28, 525-539 (2019) Author(s): V. Penchev:
Abstract.In fact, the first law of conservation (that of mass) was found in chemistry and generalized to the conservation of energy in physics by means of Einstein’s famous “E=mc2”. Energy conservation is implied by the principle of least action from a variational viewpoint as in Emmy Noether’s theorems (1918): any chemical change in a conservative (i.e. “closed”) system can be accomplished only in the way conserving its total energy. Bohr’s innovation to found Mendeleev’s periodic table by quantum mechanics implies a certain generalization referring to the quantum leaps as if accomplished in all possible trajectories (according to Feynman’s interpretation) and therefore generalizing the principle of least action and needing a certain generalization of energy conservation as to any quantum change. The transition from the first to the second theorem of Emmy Noether represents well the necessary generalization: its chemical meaning is the generalization of any chemical reaction to be accomplished as if any possible course of time rather than in the standard evenly running time (and equivalent to energy conservation according to the first theorem). The problem: If any quantum change is accomplished in all possible “variations (i.e. “violations) of energy conservation” (by different probabilities), what (if any) is conserved? An answer: quantum information is what is conserved. Indeed, it can be particularly defined as the counterpart (e.g. in the sense of Emmy Noether’s theorems) to the physical quantity of action (e.g. as energy is the counterpart of time in them). It is valid in any course of time rather than in the evenly running one. That generalization implies a generalization of the periodic table including any continuous and smooth transformation between two chemical elements.
Keywords: conservation, Emmy Noether’s theorems of conservation, quantum information, periodic table, quantum chemistry