Сп. „Химия“, книжка 5/2009

Bulgarian Educational Tradition

Didactics in Chemistry as an Academic Subject: Doc. Ludmila Genkova

Резюме. Two periods of the development of the Bulgarian didactics of chemistry exist – (1) as a non-academic subject (in the Kingdom of Bulgaria (1878-1946)) and (2) as an academic subject (in the Peoples Republic in Bulgaria (1946-1990)). The second period is presented by the complete list of publications of Doc. Dr. Ludmila Genkova (b. 1931). This bibliography gives an idea about the content, style, peculiarities and value of the publications in the field of science education during the period of question.
Keywords: chemistry education, Peoples Republic of Bulgaria, Genkova

B.V. Toshev

New Approaches

The Fourth Law of Thermodynamics or the Law of Maximum Entropy Production (LMEP)

Резюме. In their recent paper entitled „A Fourth Law of Thermodynamics“ Morel and Fleck propose what they say is a simply stated yet powerful new universallaw that accounts for the ubiquitous production of order from disorder that characterizes
the visible world and thereby, and in other ways, significantly expands the domain of thermodynamics. While we agree with their characterization of the law as the Fourth Law of Thermodynamics, and that it significantly expands thermodynamics, and that it is universal in scope applying near and far from equilibrium to all ranges and scales, and that it provides the basis for spontaneous transformations from disorder to order, the mistake they make is that the law is not a new law. It was proposed and demonstrated by my colleagues and me as „The Law of Maximum Entropy Production“(LMEP or previously MEP) more than two decades ago and subsequently in numerous articles since. This error in their paper, however, in no way diminishes what they say is the validity or significance of the law. The law with some additional background and context is further discussed.
Keywords: maximum entropy production, fourth law of thermodynamics, spontaneous order

R. Swenson

Interdiscipinary

Problems from „Bulgarian Arithmetic“ (1856): An Example for Forming Key Competences

Резюме. Some of the problems of Nikolov’s Bulgarian Arithmetic, published in 1856, related to natural sciences, are reviewed. The review shows that the Bulgarian
education in the mid-nineteenth century is directed to acquiring a knowledge that may readily be applied in the everyday life. At the same time, using that method
of combination of different teaching subjects and taking into account real life situations, key competencies could be formed by the students. This seems to be a good lesson for the contemporary times. Such interactive and practical approach could be successfully used and implementing in all natural sciences for raising the interest and motivation of the students.
Keywords: education in nineteenth century, natural sciences, interdisciplinary, key competences, interactive methods

S. Manev, V. Dimitrova

Teaching Efficiency

A Study of Students’ and Teachers’ Perceptions and Expectations of Their Learning in Secondary Science Classrooms

Резюме. Ten secondary science teachers volunteered themselves and one of their classes to participate in the Constructivist Learning Environment Survey (CLES. This paper concentrates on the students’ perceptions and expectations of their learning of science. The anonymous survey revealed that both students and their teachers would prefer that classroom to be more interactive, relative and democratic in practice. There was no correlation with gender identification in this study as the genders
responded equally in perceptions and expectations of learning styles, and classroom voice. Surveyed Bulgarian students are eager to learn new learning methodologies,have relevancy in their studies and desire to have a voice in their classroom. It would be to the benefit of teachers and teacher trainers to be privy to what students are thinking. If teachers and students can come together in perceptions and expectations, teaching and learning will improve in schools and the interests in science, technology and related areas will improve as result of implementation of student participation.
Keywords: science education, constructivist approach, teaching and learning, Constructivist Learning Environment Servey (CLES)

J.E. Hollenbeck, M. Kirova, E. Boiadjieva, A. Tafrova-Grigorova

Reviews

A Book That One Looks for (Dukov & Tsvetkov, 2009)

I. Lirkov

Editorial

The Bulgarian Teacher in the Past and Present

Резюме. The school environment is not the best in the present times. But the Bulgarian teachers experienced difficulties in the past times as well. Nevertheless the Bulgarian teachers, then and now, are always with the knowledge for the value of their work in school. An illustration of the consolidation of the former teachers community is the „Teachers anthem“. The text and music of that march is presented here by scanning its first edition in 1905.

B.V. Toshev

Chemistry & History of Chemistry: An Online Supplement

Experiments for Hydrophilic and Hydrophobic Interactions Analysis of N-Methyl Ureas with Water Using Density and Surface Tension

Резюме. Surface tension (gamma ± mNm-1) of urea, 1-methylurea (MU), 1, 3-dimethylurea (DMU) and 1,1,3,3-tetramethylurea (TMU) as N, N’-ureas were obtained at 7.99 to 7.01 pH and 293.15, 298.15 and 303.15 K temperatures for 0.005 to 0.25 mol kg-1 at an interval of 0.005 mol kg-1 solutions. Limiting surface tension gamma_0 data were obtained from regression analysis. The contributions of -CH3 (methyl) groups were analyzed from a difference of the gamma_0 values of consecutive ureas. The gamma_0 data illustrated weakening of hydrophilic and strengthening of hydrophobic interactions with each -CH3 group and inferred a shift from hydrophilic-hydrophilic to hydrophilic-hydrophobic interactions. The gamma_0 data illustrated a structure making action of the TMU.
Keywords: hydrophobic, hydrophilic, tetramethylurea, interactions, structure breaking

Man Singh

Chemistry & History of Chemistry: An Online Supplement

Cutting Edge Device Over Usual Surface Tension, Interfacial Tension, Viscosity Experimental Measurements for Saturated Hydrocarbons and Dithioerythritol: Air Filter Fitted Survismeter

Резюме. Interfacial tension (IFT) of pentane, hexane, heptane and octane saturated pure hydrocarbons with water interfaces depicted as Liquid-liquid interfaces (LLI) and surface tension and viscosities for 2.5, 5.0, 7.5 and 1.0 aqueous millimoles/L Dithioerythritol (DTE) are reported. The IFT are decreased in the order: octane – hexane – pentane – heptane. The viscosities increase and the surface tension showed micelle formation with DTE compositions. The interfacial tension, surface tension and viscosities are frequently measured parameters for soaps, detergents, cosmetics, inkjet inks, syrups, sol-gels, solvents, fuels, textile spinning, paper technology, drug surface area and disintegration etc. Individually usual viscometers, stalgmometers/tensiometers are in use where suction is must for either lifting the sample up or dropping the sample downwards. In this process atmospheric air is used for pressure variations inside instrumental parts. The atmospheric air is heavily contaminated with so many pollutants like SOx, COx, NOx (x = 1,2,3), HCl, H2O vapors, volatile organic compounds (VOC) and polychlorinated biphenyls (PCB). Air filter fitted Survismeter was used for measurements of the parameters using purified air for developing pressure gradients.
Keywords: hydrocarbons, interfacial tension, surfactant, interactions, pollutants

Man Singh

Chemistry & History of Chemistry: An Online Supplement

Opto Mechanical Properties of FeCl3 in Absence and Presence of PVA (Polyvinyl Alcohol) and 50% (v/v) Ethanol – Water Mixtures

Резюме. The optical and mechanical properties for the different solutions were studied at room temperature. From the measured refractive indices of FeCl3 solutions in absence and presence of 10% PVA (Polyvinyl alcohol), the molar refraction (RM), specific refractivity (e) and the polarizabilities were estimated. The same parameters were also evaluated in presence of 50% mixed ethanol water solvents. The mechanical tension parameters like elastic modulus (E) and Shear modulus for FeCl3+10% PVA solutions in absence and presence of 50% ethanol – water mixtures were evaluated. The opto-mechanical properties of FeCl3 solutions in the title conditions were discussed.
Keywords: ferric chloride, polyvinyl alcohol, optical properties, mechanical properties

N.A. El-Shishtawi, M.A. Hamada, E.A. Gomaa

Chemistry & History of Chemistry: An Online Supplement

Synthesis Characterization and Antibacterial Activity of Some 1-Aroyl-3-aryl Thioureas

Резюме. An efficient synthesis of some 1-aroyl-3-aryl thioureas (1a-j) is reported. Substituted aroyl chlorides were treated with an equimolar quantity of potassium thiocyanate in acetone to afford the corresponding isothiocyantes which were not separated followed by reaction with an equimolar amount of substituted anilines to furnish the 1-aroyl-3-arylthiourea derivatives (1a–j). The structures were confirmed by spectroscopic data and elemental analyses. All of the synthesized compounds (1a-j) were assayed in vitro for their antimicrobial activity against Gram positive and Gram negative bacteria and were found to exhibit moderate to potent activity towards the tested microorganisms, compared to the standard drugs.
Keywords: 1-aroyl-3-aryl thioureas, antibacterial, synthesis

A. Saeed, N. Abbas, H. Rafique, S. Rashid, A. Hameed

Chemistry & History of Chemistry: An Online Supplement

Pharmaceutical Excipients from the Point of View of a Medicinal Chemist

Резюме. A new elective discipline of pharmaceutical study – Chemistry of pharmaceutical excipients, which could present structural and analytical profiles of the most interesting and important groups of pharmaceutical excipients has been established at the Pharmaceutical faculty of Veterinary and Pharmaceutical University in Brno, Czech Republic. The discipline consists of 2 hours of lectures per week and 16 hours of laboratory per semester. The matter of study is divided into 6 themes of lectures and 2 thematic sections of laboratory. Examination is performed orally and students can randomly choice two of 15 questions which also cover up whole the matter of the discipline. The courses have begun since the session 2007/2008 and the interest of students in them gradually growths. The first students passed the courses with excellent rating.
Keywords: pharmaceutical excipients, structure, SAR, synthesis, analytical specifics

O. Farsa

Свързани статии:

Сп. „Химия“, книжка 1/2009 Сп. „Химия“, книжка 2/2009 Сп. „Химия“, книжка 3/2009 Сп. „Химия“, книжка 4/2009