Сп. „Химия“, книжка 3/2017

Education: Theory & Practice

Perception of Preservice Science Teachers in the Constructivist Science Learning Environment

Резюме. Science learning was affected by various kinds of sources which students perceived and participated in classroom. The purpose of this study aims to investigate the science learning environment of preservice science teachers from Thailand and Czech Republic. Data were collected from 72 Czech and 37 Thai preservice science teachers by the six-element of CLES questionnaire. Findings revealed that preservice science teachers from Czech and Thai contexts had different level of constructivist science learning environment which is concerned classroom learning environments, and knowledge base for applying constructivist teaching into classroom. This may have implications for enhancing constructivist teaching in school context.

Keywords: learning environment, constructivist, CLES, national study

P. Nuangchalerm, J. Dostál

Teaching Efficiency

Interactive Methods and Possibilities of Their Implementation to the Education Process in „Biology and Health Education“, 7th Grade [In Bulgarian]

Резюме. The present study is a part of didactic experiments which purposes are to check the possibilities of implementation and effectiveness of some interactive methods of education in “Biology and Health education” in 7th grade. Proper interactive methods, adequate to the purposes of education of chosen methodological units from section “Role of the organisms in the Nature and their significance for the Human”, were designed. These methods were applied in real lessons. The effectiveness of those interactive methods was demonstrated.
Keywords: interactive methods, health education, Biology and Health education VII grade, students

M. Boycheva, R. Davidova, S. Marinova

Teaching Efficiency

Enhancing Thai Students’ Thinking Skills About Energy Issues: Influence of Local Values

Резюме. The study aimed to enhance Thai students’ thinking skills on learning about energy related to influence of local value. The participants consisted of 132 Grade 9 students from three different schools in Khon Kaen, in North East Thailand. The three participating teachers in these schools had adopted the STS energy unit that developed by researcher. The STS energy unit consists two sub-units:(1) Use energy in Thailand (issue of the increased petrol price); (2) Generation power (issue of the Mae-moh situation). Teachers had attended workshops before and during their adopting the unit. Methodology regarded interpretive paradigm. The students’ thinking skills was investigated through participant observation and informal interview for ten weeks. Their thinking skills were interpreted from the orientation of their posted questions. Based on Zohar & Dori (2003) study, three question orientation attributes including phenomenon or problem description, hazards related to the problem, and treatment or solution were applied for categorized students’ thinking skills. The proposing question in orientation of solution would be viewed as a higher level of understanding the problem than describing it, and finding treatment or solution was more positive and productive than just identifying hazards. Comparing between sub-unit one and two revealed that students across three schools gained more seeking practical solution to a given problem rather than being fixated on requiring about risks. Increasing the hazard and solution oriented questions indicated that the STS energy unit continually supported the development of their thinking skill classification from the sub-unit one to the sub-unit two.
Keywords: energy, science technology and society (STS), local value, thinking skills

C. Yuenyong

Experiments

Liquid-Liquid Extraction and Spectrophotometric Characterization of Some New Ion-Associated Complexes of Co(II) with INT: Application of the Developed Method for Analysis of Soil Cobalt Content

Резюме. The study presents a newly-developed method for extraction-spectrophotometric determination of Co(II) in samples by means of iodnitrotetrazolium chloride. The electronic spectrum of cobalt ion associated has a peak at 630 nm. At that wavelength the absorption is maximum. The ratio INT: [Co(SCN)4] in the triple ion-associate complex was 2:1, and due to the good solubility of the Co(II) ion associated and INT in 1,2 dichloroethane, maximum extraction in the organic phase was achieved after 30 s extraction. The molar absorptivity of the studied ion associate INT2[Co(SCN)4] was E630 = 0.6×103 dm3 mol-1 cm-1. Sendel’s sensitivity of the method was 9.8×10-2 microg.cm-2. The maximum quantity of Co extracted with INT was achieved at pH 2-7. The relationship between Co(II) concentration and absorption was linear in the range of 6 – 125 mg Co(II) in 10 cm-3 aqueous solutions.
Kewwords: Co, determination, INT, soils, spectrophotometry

L. Dospatliev, M. Ivanova

Advanced Science

Quantum Confinement of Mobile Na+ Ions in Sodium Silicate Glassy Nanoparticles

Резюме. The confinement of mobile Na+ ions in sodium silicate glassy nanoparticles is considered quantum mechanically to be under the influence of a spherical box potential. The values for the energies of mobile Na+ ions are determined theoretically for particle diameters of 1nm, 2nm and 5nm. For 1nm and 2nm particles, for a given value of the principal quantum number ‘n’, it is shown that the energy level separations between adjacent levels lie in the microwave region of the electromagnetic spectrum.
Keywords: glassy nanoparticles, nanostructures, nanostructured materials, amorphous oxides, quantum confinement, spherical box potential

S. Murthy

Advanced Science

Conservation of the Upstream Open Reading Frames in the Genes for the Erb-B2 Receptor Tyrosine Kinaze 2 in Vertebrates

Резюме. In humans a short open reading frame (ORF) precedes the sequence of the erb-b2 receptor tyrosine kinase 2 (ERB-B2). It is established that the upstream ORF plays an important role in ERB-B2 gene expression. In this report we show that an upstream ORF is present in all vertebrate genes coding for erb-b2 receptor tyrosine kinase 2. The position and the structure of erb-b2 upstream ORF is compared between six different vertebrates. Amphibians and all land vertebrates share the same uORF characteristics. In bony fishes, however, the upstream ORF is noticeably different. This suggests that the regulation of erb-b2 gene by uORF originated in its present form with the amphibians.
Keywords: receptor tyrosine kinase, upstream open reading frame, evolutionary conservation

L. Karagyozov

From the Research Laboratories

Optimization of Engine Oil Formulation Using Response Surface Methodology and Genetic Algorithm: A Comparative Study

Резюме. Two potent mathematical and statistical methods of response surface methodology (RSM) and genetic algorithm (GA) based on artificial neural network (ANN) were employed for prediction and optimization of three-constituent synthetic engine oil. Polyalpha olephin-4 (PAO4) Hitec 5780 (HI 5780), and Hitec 11100 (HI 11100) were used as base oil and the additives of the engine oil, respectively. The models were applied for the percentage of oil constituents and viscosity at 40 ËšC (Vis at 40 ËšC), viscosity at 100 ËšC (Vis at 100 ËšC), Viscosity index (VI), flash point (FP) and Noack of the finished oil. The range of the viscosity at 40 ºC and 100 ºC were selected according to ISO viscosity grade for engine oil. The optimization includes maximization of FP and VI and minimization of Noack. The obtained results showed that ANN has higher potential and capability and more accuracy for prediction and optimization of the process.
Keywords: engine oil formulation, PAO4, modeling, mixture design, artificial neural network, genetic algorithm

B. Azmoon, A. Semnani, R.J. Ansari, H.S. Langeroodi, M. Shirani, S.G. Nasab

From the Research Laboratories

Chemometric Assisted Spectrophotometric Estimation of Lansoprazole and Domeperidone in Bulk and Commercial Dosage Form

Резюме. Chemometric calibrations namely, Partial least square (PLS), principal component regression (PCR) and classical least square (CLS), were developed for the simultaneous determination of domeperidone and lansoprazole from combined pharmaceutical dosage forms. In these methods with chemometric techniques, the calibrations were constructed by using the absorption data matrix, with measurements in the range of 260-310 nm (Δλ = 1 nm) in their zero order spectra. The chemometric calibrations were realized by using R – software (version 2.1.1). The linearity range was found to be 4-36 µg ml-1 and 2-18 µgml-1 for DOMP and LANS respectively. The lower correlation coefficient values 0.9998, 0.9999 and 0.9992 for DOMP and 0.996, 0.998 and 0.999 for LANS respectively estimated for CLS, PCR and PLS respectively. The validity of the proposed methods was successfully assessed for analysis of both drugs in laboratory prepared mixtures and in commercial formulations.
Keywords: domperidone, lansoprazole, chemometric, R–software, validation, statistical parameters, standard addition

F. Sami, S. Majeed, T.A.S.T. Mohammed, N.F.A. Kamaruddin, M.Z. Atan, S.A.J. Bukhari, Namra, B. Hasan, M.T. Ansari

From the Research Laboratories

Evaluation of Antibacterial Activity of Different Solvent Extracts of Teucrium Chamaedrys (L.) Growing Wild in Kosovo

Резюме. In this study the antibacterial efficiency of different organic extracts from Teucrium chamaedrys (L.), growing wild in Kosovo, was examined. Methanol, ethyl acetate, acetone, diethyl ether, water and chloroform extracts were tested against three gram positive bacteria Staphylococcus aureus (food isolate), Staphylococus aureus (clinical isolate), Listeria monocytogenes (clinical isolate) one gram negative bacteria Escherichia coli (clinical isolate). The antibacterial activity was determined by using agar disc diffusion method. The inhibition zone of extracts was compared to that of penicillin G as standard. Based on the results, the most intense activity was shown by the plant`s extracts with water and ethyl acetate. The ethyl acetate extract showed activity in all of the concentrations 1, 3 and 5 mg/ml towards Staphylococcus aureus (food isolate), Eshcheria coli and Listeria monocytogenes. Ethyl acetate extract of the plant with concentration 5 mg/ml showed a stronger antibacterial activity towards bacteria Eshcheria coli with inhibition zone of 12 mm. Aqueous extract of the plant with concentration 5 mg/ml showed a stronger antibacterial activity against bacteria Esherichia coli with inhibition zone of 12 mm. Also aqueous extracts of the Teucrium chamaedrys (L.) showed a stronger antibacterial activity as penicillin G against bacteria Staphylococcus aureus (clinical isolate). The antibacterial activity of the Teucrium chamaedrys (L.) was due to the presence of various secondary metabolites such as phenols and flavonoids. Hence, this plant can be used to discover bioactive natural products that may serve as leads in the development of new pharmaceuticals.
Keywords: Teucrium chamaedrys (L.), antibacterial activity, agar disk diffusion method, organic extracts

A. Haziri, F. Faiku, R. Berisha, I. Mehmeti, S. Govori, I. Haziri

History and Philosophy of Science

The Unknown for the Known: A. M. Butlerov [In Bulgarian]

Резюме. Alexander Mikhailovich Butlerov (1828-1886) is a great Russian chemist. He is the creator of the theory of structure of the organic compounds. This article contains unknown details of Butlerov’s life and scientific activity. Putting emphasis on what is little known today about a scientist – unknown because it is forgotten or is deliberately hidden – has a great pedagogical value. Thus, the image of the scientist in question loses its schematic contour gets depth and lean human traits, which will enable the learner to better perceive his personality and understand his/her work.
Keywords: Butlerov, organic chemistry, structure of organic substances, occult studies

B. V. Toshev

Science and Society

Quality Assessment of Supply Water of Gjakova City (Kosovo): A Case Study of Correlation Coefficients between Chemical Data

Резюме. In this study the quality assessment of supply water of Gjakova in the period time January to October was investigated. Statistical studies have been carried out by calculating of basic statistical parameters, anomalies and correlation coefficients between different pairs of variables. From the results of field work and laboratory analyses it was found out that supply water of Gjakova fulfill the criteria set by the World Health Organization and the low distribution of physico-chemical parameters indicated lithological pollutions. The statistical regression analysis has been found a moderately high positive correlation relationship between pH and EC, consumption of KMnO4, Turbidity, Cl-, Al3+ and NO3-. Result dates suggest also strong positive correlations of EC with Turbidity, consumption of KMnO4, Cl-, Al3+ and NO3-. R-mode cluster analysis showed mutual links between studied parameters. It could be observed on water samples that EC has closest linkages with consumption of KMnO4 and they form first branch of the dendogram. Also EC has closest linkages with NO3- and they form second branch of the dendogram.
Keywords: quality assessment, supply water, statistical analysis, correlation coefficients, Gjakova

F. Gashi, N. Troni, A. Maxhuni, A. Mehmeti, J. Shabani

Свързани статии:

Сп. „Химия“, книжка 2/2017 Сп. „Химия“, книжка 4/2017 Сп. „Химия“, книжка 5/2017 Сп. „Химия“, книжка 6/2017