|Education: Theory & Practice:|
|I. Hadjiali, T. Kolarova|
The Intellectual Reflection of 15-17 Years-Old Students in the Teaching of "Biology and Health Education": Levels and Trends of Development [In Bulgarian]
Full text: PDF (440 K)
|N. Tsankov, V. Guyviiska|
Chimerical Groups in School as a Social and Educational Phenomenon
Full text: PDF (473 K)
|N. Tsankov, V. Guyviiska|
"Symbolic Capital" of the Bulgarian School [In Bulgarian]
Full text: PDF (324 K)
IUPAC Approved Permanent Names of the Chemical Elements 113, 115, 117 and 118: The Seventh Period of the Periodic Table of the Chemical Elements Is Completed [In Bulgarian]
Full text: PDF (336 K)
|S. Kusairi, A. Hidayat, N. Hidayat|
Web-Based Diagnostic Test: Introducing Isomorphic Items to Assess Students' Misconceptions and Error Pattern
Full text: PDF (687 K)
|F. Rahmawati, T. Martini, N. Iswati|
Kinetics of Photo-Electro-Assisted Degradation of Remazol Red 5B
Full text: PDF (746 K)
|O. A. Saputra, W. A. Lestrari, D. A. Saputra, K. S. Rini, E. Pramono|
Comparison Study of Different Inorganic Silica Based Reinforcement Kaolin and 3-Clycydiloxypropyl Trimethoxysilane on Mechanical, Water Uptake and Swelling Area Properties of Chitosan Composites
Full text: PDF (732 K)
|M. Firdaus, Petiha, T. Kusumaningsih|
Simple Technique for Determing the Forward Rate Constant of Reversible Reaction
Full text: PDF (567 K)
|Bulgarian Educational Tradition:|
|B. V. Toshev|
Forgotten Bulgarian Teachers: Simeon Hristov [In Bulgarian}
Full text: PDF (873 K)
|From the Research Laboratories:|
|A. Dragoeva, V. Koleva, Z. Stoyanova, E. Zayova, S. Ali|
Allelopatic and In Vitro Anticancer Activity of Stevia and Chia
Full text: PDF (533 K)
|R. Hoti, N. Troni, H. Ismaili, G. Mulliqi-Osmani, V. Thaci|
Novel Heteroarylamino-Chromen-2-Ones and Their Antibacterial Activity
Full text: PDF (654 K)
|Science and Society:|
|N. Suprapto, A. Zamroni, E. A. Vudianto|
One Decade of the "Lusi" Mud Volcano: Physical, Chemical, and Geological Dimensions
Full text: PDF (940 K)
|B. V. Toshev|
Fundamentals of the General Methodology of Natural Science, 1929
Full text: PDF (976 K)
Khimiya, Volume 26, Issue 4(2017)
Khimiya. 26, 487-497 (2017) Author(s): I. Hadjiali, T. Kolarova:
Abstract.The study was aimed at identifying possible levels at which the intellectual reflection manifests in secondary students from grade 9th to 11th and trends in its development during a three-year experimental teaching in "Biology and health education". The methodological basis of the study is the conception of reflective approach which is specified to educational technology for the purposes of organized training. The diagnostic tools include three cognitive test with a reflective end. Through them we measured two main characteristics of the intellectual reflection: productivity (focusing on the students’ knowledge transition in familiar and unfamiliar contexts) and awareness of the reflection (focusing on the students’awareness of the own strategies for solving learning tasks). According to the intensity with which they occur in the process of learning and using the SPSS 13 software, the students were separated in four cluster groups: K 1 (zero productivity in solving reflective tasks and unawareness of the own cognitive strategies), K 2 (low productivity and medium level of awareness of the own cognitive actions), K 3 (medium productivity and high awareness of the own cognitive actions) and K 4 (high productivity and high awareness of the own cognitive actions). The cluster analysis of the survey results is a ground for drawing out some major trends in the development of intellectual reflection in the context of experimental teaching: (1) The most highlighted are the transitions from low to medium level of productivity and of medium to high level of awareness of the reflection; (2) The high productivity and high awareness of the reflection most often occur simultaneously in the learning of biology.
Keywords: cluster analysis, high school biology education, intellectual reflection, levels of intellectual reflection, reflective approach
Khimiya. 26, 498-509 (2017) Author(s): N. Tsankov, V. Guyviiska:
Abstract.The problem discussed is related to the need for clear socio-pedagogical parameters of (criminal groups) gangs in schools. The different interpretations link them to difficult children, youth subcultures, and street gangs while chimerical groups are a possible conceptual projection on them. We are attempting at a socio-pedagogical reading of a community of children and adolescents with deviant behavior but not juvenile offenders, which makes us face legal terms and delinquent behavior. A chimerical group of dealers, pimps, prostitutes and other subjects with deviant behavior at school imitates the behavior of criminal groups in society, borrowing mechanisms and means and also creating their own social networks. Unlike real life criminal groups, though, chimerical groups are a subject of education activities as a function of the school institution. The most timely the pedagogical intervention of the school institution (not only as socializing and training), the greater the chances these children and adolescents’ lives to be saved and their personality preserved.
Keywords: chimerical group, gang, difficult children, youth subculture, clans, identity, prevention, re-socialization, education/pedagogy
Khimiya. 26, 510-518 (2017) Author(s): N. Tsankov, V. Guyviiska:
Abstract.This study is influenced by the ideas of the French sociologist Pierre Bourdieu. The assumption is that the external differentiation of the school system conceals a social selection of students, teachers and parents. On an empirical level, the answer to the question of the existence of symbolic capital at school and the students’ explicit or implicit awareness of it is sought.
Keywords: symbolic capital, symbolic power, practical logic, objectified and incorporated history, symbolic field
Khimiya. 26, 519-525 (2017) Author(s): I. Dukov:
Abstract.After the fulfilment of the IUPAC criteria for the discovery of new elements, the priority for the discovery of element 113 has been judged to the RIKEN collaboration team in Japan, the priority for the discovery of elements 115 and 117 – to the Dubna – Livermore – Oak Ridge collaboration and the priority for the discovery of element 118 – to the Dubna – Livermore collaboration. The discoverers proposed names and symbols of the new elements: nihonium for element 113 (symbol Nh); moscovium for element 115 (symbol Mc); tennessine for element 117 (symbol Ts); oganesson for element 118 (symbol Og). After expert and public review, the proposed names and symbols have been approved. The translation of the elements names from English to Bulgarian was commented since direct translation is not always possible. After approval of the names of elements 113, 115, 117 and 118, the seventh period of the periodic table of the chemical elements is complete.
Keywords: new elements, naming, IUPAC
Khimiya. 26, 526-539 (2017) Author(s): S. Kusairi, A. Hidayat, N. Hidayat:
Abstract.The misconceptions and error patterns of students are crucial to assess in order to support effective physics learning. However, exploring students’ misconceptions and error patterns is not easy. A web-based diagnostic test is an alternative approach to help the teacher in obtaining such information and giving quick feedback to students. In this article, we report the development of a new model of the web-based diagnostic test. The model uses isomorphic multiple-choice items, in which each learning indicator consists of three multiple-choice items with distracters that are based on students’ misconceptions or error patterns. The model provides feedback to students and teachers based on the consistency of the students’ answers. According to experts’ reviews, the model is valid and worth using. The preliminary field test of the model of the web-based diagnostic test has been used with some physics students. The web-based diagnostic test could be a new alternative for physics teachers and researchers to identify students’ misconceptions and error patterns.
Keywords: isomorphic item, misconception and error pattern, web-based diagnostic system
Khimiya. 26, 540-556 (2017) Author(s): F. Rahmawati, T. Martini, N. Iswati:
Abstract.This research studies a kinetics of photo-electro-assisted degradation of dyes. The kinetics study applied the Buttler-Volmer kinetics for electro-assisted reaction in combination with the regular chemical kinetics for photodegradation. The result then being compared with the regular chemical kinetics application for both photo-electro-assisted degradation. The degradation cell was designed by separating the anodic and cathodic cell, in which the dye solution was placed in the anodic cell. As the solvent, water molecules, also be able to undergo electro-oxidation, therefore in this research pH of the solution was recorded during reaction whether in the anodic or cathodic cell. The result shows that oxidation of H2O occured in an anodic cell in competition with the dye oxidation. However, the dye oxidation proceeds faster than H2O oxidation. In which, the rate constant of dye oxidation is 2.7795 × 10-3. Meanwhile, the rate constant of H2O oxidation in the anodic cell is 7.9738 × 10-11. In addition, the study also found that the degradation cell undergoes polarization. It is indicated by the low value of the cathodic rate constant, i.e. 3.2805 × 10-10. The cathodic cell is only filled with water, therefore, the reducing species is only H2O molecules. The result also shows that Cu-TiO2/Graphite also has adsorption ability in which the dye molecules were adsorbed with adsorption constant of 5.56 10-2 ppm-1.
Keywords: reaction kinetics, photo-degradation, electro-degradation, photo-electro-degradation
Khimiya. 26, 557-569 (2017) Author(s): O. A. Saputra, W. A. Lestrari, D. A. Saputra, K. S. Rini, E. Pramono:
Abstract.The blending of chitosan with different types of silica-based reinforcement materials, kaolin clay and (3-glycidyloxypropyl) trimethoxysilane via solution casting method had been carried out. This study was focused on the mechanical, water uptake and swelling area comparison between chitosan/kaolin (referred as Cs/Kao) and chitosan/(3-glycidyloxypropyl) trimethoxysilane (Cs/GPTMS) composites. Fourier transform infra-red (FTIR) characterization was also conducted in this study for functional group analysis. Mechanical properties, such as tensile strength, elongation percentage and young’s modulus, were performed according to ASTM D882-02 standard method. Based on the mechanical test, it can be concluded that different types of silica-based reinforcement materials resulted different mechanical properties. The GPTMS filled chitosan had higher tensile strength value than Cs/Kao at 15% filler loading but lower in another concentrations. Moreover, water uptake and swelling area value of Cs/GPTMS was lower than Cs/Kao at 15% filler content.
Keywords: chitosan, composites, kaolin, GPTMS, silica-based reinforced materials
Khimiya. 26, 570-581 (2017) Author(s): M. Firdaus, Petiha, T. Kusumaningsih:
Abstract.The forward rate constant of reversible reactions can be used to estimate the concentration of the reactants at a given time (and then the products by using stoichiometric coefficients), to control the quality of the products, to calculate the backward rate constant (by using equilibrium constant), to determine the activation energy, and to predict the reaction mechanisms. Most commonly, the determination of a forward rate constant is done by using the equilibrium concentrations. However, this approach is inefficient since to a certain extent a lot of reactions takes a long time to reach an equilibrium state. The method without using equilibrium concentration is also introduced. Nevertheless, it cannot be used to determine the backward rate constant. This study presents a simple and appropriate technique, using irreversible approach on three data at the early stages of a reversible reaction. The data for first order for both directions and first order for forward and second order for back reaction were obtained from literatures. The results were then compared with that obtained from conventional technique. The results show that, with error percentage less than 5%, the new technique is valid and reliable.
Keywords: forward rate constant, reversible reaction, irreversible approach, equilibrium concentrations, simple technique
Khimiya. 26, 582-592 (2017) Author(s): B. V. Toshev:
Abstract.A biographical sketch of Simeon Hristov (1852-1910) is presented. The author of the present article advocates for using by pupils and teachers “historical trips” in the past in order to overcome the cultural trauma, which is a feature of the modern education.
Keywords: Bulgarian teachers, Bulgarian education, Simeon Hristov
Khimiya. 26, 593-604 (2017) Author(s): A. Dragoeva, V. Koleva, Z. Stoyanova, E. Zayova, S. Ali:
Abstract.Stevia rebaudiana (Bertoni) Bertoni (Asteraceae) and Salvia hispanica L. (Lamiaceae) (chia) are functional foods used worldwide today. Additionally, aerial parts of both plants contain valuable secondary metabolites. Chemical composition of stevia and chia exhibits wide variations depending on geographic region, climatic conditions, time of plant collection etc. Nowadays there is a renewed interest on plants bioactive compounds concerning two important health problems: contamination of the environment with agrochemicals and inability to treat cancer. The aim of this study was to evaluate allelopathic and in vitro anticancer activity of water extracts made from the aerial parts of micropropagated stevia and chia grown in Bulgaria in laboratory conditions. The allelopathic potential was evaluated using germination and root/shoot elongation assays and Allium cepa-test. Water extracts of plants tested had no significant influence on seed germination, but affected seedling growth. Chia was more effective in suppressing growth, as compared to stevia. Effective Concentration causing 50% growth inhibition (EC50) value was determined: 11.12 g/l (stevia) and 6.17 g/l (chia). After exposure to extracts (EC50, for 24 h) mitotic indices in root meristem cells were extremely low. In such a case it is not recommended to score chromosomal aberrations. The results of the study revealed that water extract of chia possess much stronger allelopathic activity than stevia. Cytotoxic effect in vitro was evaluated using cell proliferation/viability of human hepatoma cell line SK-HEP-1. In the present study, stevia and chia water extracts had no influence on cancer cell line tested.
Keywords: chia, stevia, allelopathy, cytotoxicity, Allium cepa-test, SK-HEP-1 cell line
Khimiya. 26, 605-614 (2017) Author(s): R. Hoti, N. Troni, H. Ismaili, G. Mulliqi-Osmani, V. Thaci:
Abstract.A series of heteroarylamino-chromen-2-ones 4(a-c) were synthesized by condensation reactions under catalytic conditions. 5-(3-Nitro-2-oxo-2H-chromen-4-ylamino)-3H-imidazole-4-carboxamide 4a, 4-(7-Hydroxy-5-methyl-[1,8]-naphthyridin-2-ylamino)-3-nitrochromen-2-one 4b and 4-(4-methylbenzothiazol-2-ylamino)-3-nitrochromen-2-ones 4(c-d) were synthesized by condensation of 4-chloro-3-nitrochromen-2-one 2 with corresponding heteroarylamines 3(a-d) under reflux reaction conditions. Alkali hydrolysis of compounds 4(a-d) afforded the 2-hydroxy-ω-nitroacetophenone 5. The structures of the obtained compounds were established on the basis of FTIR and NMR spectrometric data and their elemental analysis. Compounds of series 4(a-c) were screened for their antibacterial activity against S. aureus, E. coli and Klebsiella by Diffusion Disc Method. Compounds 4(a-c) displayed considerable activity against these microorganisms and the impact of substitutions in antimicrobial activity was also explored.
Keywords: Chromen-2-one, imidazole, naphtyridine, benzothiazole, zones of inhibition
Khimiya. 26, 615-629 (2017) Author(s): N. Suprapto, A. Zamroni, E. A. Vudianto:
Abstract.In this article, we have raised more recent phenomenon of mud volcano disaster since May 2006 until now in Sidoarjo, East Java- Indonesia. This rare occurrence has invited the public to enjoy, even for scientist as a mean of doing research or for public as a curiosity. A mud volcano is a geological formation created by the expulsion of pressurized gasses and mud from below the Earth’s crust. By using a systematic review process, the authors review the phenomena by using physical, chemical, and geological approaches. The review process comprises five phases: framing questions for a review, identifying relevant work, assessing the quality of studies, summarizing evidences, and interpreting the findings. The results show the physical and chemical dimensions of mud volcano and depict to what extent the physical and geological efforts to stop the disaster. In this study, there are some additional references and sources of new knowledge for scientists, citizens, and government.
Keywords: chemistry, geology, Indonesia, mud volcano, physics