|B. V. Toshev|
The Post-Normal Science: Features and New Trends [In Bulgarian]
Full text: PDF (395 K)
|B. Stoykova, M. Chochkova, G.Ivanova, L. Mukova, N. Nikolova, L. Nikolaeva-Glomb, P. Vojtíšek, T. Milkova, M. Štícha, D. Havlíček |
Synthesis of Fluorinated Hydroxycinnamoyl Derivatives of Anti-Influenza Drugs and Their Biological Activity
Full text: PDF (647 K)
|R. Chayrov, V. Veselinova, V. Markova, L. Mukova, A. Galabov, I. Stankova|
Synthesis and Antiviral Activity of Some Amino Acids Derivatives of Influenza Virus Drugs
Full text: PDF (571 K)
|K. Chuchkov, S. Nakova, L. Mukova, A. Galabov, I. Stankova|
New Derivatives of Oseltamivir with Bile Acids
Full text: PDF (445 K)
|M. Vakarelska-Popovska, Z. Velkov|
Monohydroxy Flavones. Part III: The Mulliken Analysis
Full text: PDF (539 K)
|T. Dzimbova, A. Chapkanov, T. Pajpanova|
Leu-Arg Analogues: Synthesis, IR Characterization and Docking Studies
Full text: PDF (831 K)
Synthesis of 2-Fluorimethyl-7-(arylsulfanylmetyl) Naphtalenes
Full text: PDF (374 K)
Investigation of the Etherification Process Under Model Mixture
Full text: PDF (366 K)
|I. Stoykova, T. Yankovska-Stefenova, L.Yotova, D. Danalev|
Modified Quechers Method for Determination of Methomyl, Aldicarb, Carbofuran and Propoxur in Liver
Full text: PDF (445 K)
|T. Haralanova, C. Girginov|
Organic Compounds as Inhibitors for Mild Steel in 1 M H2SO4
Full text: PDF (560 K)
|M. Mitov, Y. Hubenova|
Microbial X Cells - Innovative Multipurpose Bioelectrochemical Systems
Full text: PDF (746 K)
|E. Chorbadzhiyska, Y. Hubenova, S. Yankova, D. Yankov, M. Mitov|
Lactobacillus plantarum AC 11S as a Biocatalyst in Microbial Electrolysis Cell
Full text: PDF (623 K)
|G. Hristov, E. Chorbadzhiyska, M. Mitov|
Pd-Au Deposites on Ni-Foam as Anodic Electrocatalysts for Direct Borohydide Fuel Cell
Full text: PDF (600 K)
|I. Bardarov, Y. Hubenova, M. Mitov|
Sediment Microbial Fuel Cells as Power Sources for Small Electrical Consumers
Full text: PDF (1140 K)
|P. Petrova, I. Karadjova, M. Chochkova, I. Dakova|
Solid Phase Extraction of Au(III) Using Silica Gel Modified with 4-Aminoantipyrine Schiff Bases
Full text: PDF (405 K)
|N. Velitchkova, P. Petrova, S. Velichkov, N. Daskalova|
Inductively Coupled Plasma Optical Emission Spectroscopy - Determination of Rare Earth and Platinum Group of Elements
Full text: PDF (463 K)
|K. B. Omarov, Z. B. Absat, S. K. Aldabergenova, A. B. Siyazova, N. J. Rakhimzhanova, Z. B. Sagindykova |
Studying the Process of Deposition of Antimony with Calcium Carbonate
Full text: PDF (418 K)
Khimiya, Volume 24, Issue 3(2015)
Khimiya. 24, 329-339 (2015) Author(s): B. V. Toshev:
Abstract.By overcoming the bloc division of the world, science has restored its global entirety. Processes of differentiation of science were replaced by integrative processes which blurred the boundaries between the special scientific disciplines; multidisciplinary and interdisciplinary methods went at the forefront of research. For example, the old pedagogical disciplines amalgamated in a bulk science of education. Science education is considered to be an important research area of science of education which is built on the model 3P - Education (P), Psychology (P) and Philosophy (P). Project financing of research has replaced the institutional funding. Then, the triangle science - state – society was established. Science entered in its post-normal phase. Large scale research and mass higher education call for effective control over the state of the scientific sector of a country. Publication of scientific results in marginal literature now is not accepted. Therefore, changes occurred in scientometrics. The index of Hirsch was been assumed to be the most appropriate scientometric indicator for the quantitative evaluation of the scientific activity. It could be figured out for the researcher, for the academic journal, for the research institution, and, as well as, for the research sector of the whole country.
Keywords: post-normal science, integration, 3P-model, scientometrics, index of Hirsch
Khimiya. 24, 340-347 (2015) Author(s): B. Stoykova, M. Chochkova, G.Ivanova, L. Mukova, N. Nikolova, L. Nikolaeva-Glomb, P. Vojtíšek, T. Milkova, M. Štícha, D. Havlíček :
Abstract.The emergence of a novel pandemic influenza A (H1N1) strain in 2009 is an evident mark for the unremitting risk of respiratory viral diseases. Influenza outbreaks and development of desease and could be overcome by use of vaccines and antivirals. Currently, clinically applied influenza antivirals are limited to M2 ion channel blockers (amantadine and rimantadine) and neuraminidase inhibitors (oseltamivir and zanamivir). Development of resistant viral progeny though, is one of the major challenges to antiviral chemotherapy, in general. Resistant viral mutants are described to both classes of anti-influenza antivirals, as well. Therefore, the development of new antiviral agents for influenza treatment is a hot topic and a never ending task.Combining antiviral drugs with antioxidants in severe influenza-associated complications is of great therapeutic significance. Based on the prominent antioxidant activity of hydroxycinnamic acids, herein, we report the biological activity of newly synthesized am-ides obtained by coupling previously synthesized N-hydroxycinnamoyl amides of fluori-nated amino acids and a fragment of oseltamivir.
Keywords: M2 ion channel blockers, neuraminidase inhibitors, N-hydroxycinnamoyl fluorinated amino acids amides
Khimiya. 24, 348-354 (2015) Author(s): R. Chayrov, V. Veselinova, V. Markova, L. Mukova, A. Galabov, I. Stankova:
Abstract.A series of new rimantadine (RS)-1-(1-adamantyl)ethanamine) analogues with some amino acids (alanine, valine, phenylalanine) have been synthesized and their antiviral activity against influenza A virus has been studied. Among the tested compounds the moderate antiviral activity has been found for the alanyl-rimantadine.
Keywords: rimantadine, amino acids, influenza virus
Khimiya. 24, 355-362 (2015) Author(s): K. Chuchkov, S. Nakova, L. Mukova, A. Galabov, I. Stankova:
Abstract.Several derivatives of oseltamivir with bile acids (cholic, deoxycholic and chenodeoxycholic acids) were prepared, using N, N dicyclohexylcarbodiimide (DCC) as coupling reagent. The chemical modifications were made in order to enhance the bioavailability of the active substance and combating resistance to the neuraminidase inhibitor - oseltamivir. Moreover, the prepared products were tested for antiviral activity against virus A/Aichi/2/68 (H3N2) and confirmed by plaque reduction assay on MDCK cells. The studied compounds showed no effect against influenza virus A(H3N2).
Keywords: oseltamivir, bile acids, Iinfluenza virus
Khimiya. 24, 363-369 (2015) Author(s): M. Vakarelska-Popovska, Z. Velkov:
Abstract.The purpose of this article is to compare Mulliken charges in monohydroxy flavones in order to assess the intramolecular reasons determining the electron density distribution and reactivity in all ten isomers. What would also be estimated is the role of the position of the hydroxyl group in the radical-scavenging activity. The optimization procedure was performed on a DFT/B3LYP level and on a large orbital basis.
Keywords: Mulliken population analysis, monohydroxy flavones
Khimiya. 24, 370-379 (2015) Author(s): T. Dzimbova, A. Chapkanov, T. Pajpanova:
Abstract.Leu-Arg is a kyotorphin receptor antagonist. It is very important to control antinociception and this could be achieved by modifications in agonist’s or antagonist’s molecules. Two analogues of Leu-Arg were synthesized, their IR- spectral characteristics were defined, and preliminary docking studies were performed. The results show that new analogues bind receptor thus they could be used for further analysis and their biological activity could be tested in vitro and in vivo.
Keywords: kyotorhin, IR, docking, Mu-opioid receptor, GOLD
Khimiya. 24, 380-384 (2015) Author(s): J. Bogdanov:
Abstract.Starting from the readily available 2,7-bis(bromomethyl)naphthalene, two 2-fluoromethyl-7-(arylsulfanylmethyl) naphthalene derivatives were prepared in four steps. It was found that direct, partial treatment of 2,7-bis(bromomethyl)naphthalene with thiophenoxide could not be controlled and the major product was bis thiophenoxy derivative. The key synthetic intermediate was 2-bromomethyl-7-fluoromethylnaphthalene, which gave the final products, 2-fluoromethyl-7-(phenylsulfanylmethyl)naphthalene and 2-fluoromethyl-[(4-bromophenyl) sulphanylmethyl]naphthalene, when treated with the corresponding thiophenoxides under phase transfer catalytic conditions. The structure of the final products and the key intermediate was established by 1H NMR, 13C NMR spectroscopy, mass spectrometry and elemental analysis.
Keywords: 2-fluoromethyl-7-(phenylsulfanylmethyl)naphthalene, 2-fluoromethyl-[(4-bromophenyl)sulfanylmethyl]naphthalene, synthesis
Khimiya. 24, 385-389 (2015) Author(s): Y. Tasheva:
Abstract.The composition of fuel has changed tremendously, and also engine technology has played an important role in improvements related to combustion. At the same time the number of motor vehicles has increased rapidly world-wide and the cut-backs on harmful emissions have become of utmost importance. One of the major changes in gasoline composition has been the development of reformulated gasoline and the introduction of high-octane oxygen-containing compounds, known as oxygenates, into the gasoline pool.
Keywords: etherification, gasoline, model mixture, additive
Khimiya. 24, 390-396 (2015) Author(s): I. Stoykova, T. Yankovska-Stefenova, L.Yotova, D. Danalev:
Abstract.N-Methyl carbamates insecticides are widely used in homes, gardens, and agriculture. Unfortunately, traces of them can further be found into animal tissues, milk, honey, eggs, etc. Therefore, food safety is an integral part of the EU policy for protection of consumer’s health and maximum residue levels for pesticides are defined in specific Regulations. A modified QuEchERS method was developed and followed by selective analysis using a high performance liquid chromatography with fluorescence detector. This method was successfully validated for liver samples according to the recommendations in the document SANCO/12571/2013 and is proved to be reliable, accurate, precise and sensitive.
Keywords: QuEchERS, pesticides, N-methyl carbamates, HPLC
Khimiya. 24, 397-403 (2015) Author(s): T. Haralanova, C. Girginov:
Abstract.The inhibitory effect of two organic compounds has been studied: 2-(4-cyanophenyl)-1-oxo-1H-inden-3-yl acetate and 2-(4-fluorophenyl)-1-oxo-1H-inden-3-yl acetate on samples of Steel 3 in 0.1 M H2SO4. Using gravimetric analysis the corrosion rate, the inhibitor efficiency and its protective effect coefficient have been determined. All experiments are carried out varying the substance concentration in the interval (10-6 - 2x10-5 mol dm-3), at 25 ± 1°C. Тhe study of the inhibitors’ performance was assessed in stationary corrosion state. The estimated values of the parameters characterizing the corrosion processes demonstrate a satisfactory inhibitory effect of the investigated substances.
Keywords: corrosion, steel 3, organic compounds, inhibitors
Khimiya. 24, 404-416 (2015) Author(s): M. Mitov, Y. Hubenova:
Abstract.This paper reviews the state-of-the art of the bioelectrochemical systems (BESs), utilizing whole living cells as biocatalysts, which has been intensively developed during the last decade. The principles of operation, specificity and potential applications of different BESs, based on microbial fuel cells and microbial electrolysis cells, are summarized and discussed.
Keywords: bioelectrochemical systems, microbial fuel cells, microbial electrolysis cells, practical application
Khimiya. 24, 417-424 (2015) Author(s): E. Chorbadzhiyska, Y. Hubenova, S. Yankova, D. Yankov, M. Mitov:
Abstract.This study demonstrates for the first time the utilization of the bacterial strain Lactobacillus plantarum АС 11S as a biocatalyst in microbial electrolysis cell (MEC). The microorganisms were preliminarily immobilized on carbon felt, used as a bioanode in single-chamber membrane-free MEC reactor. The microbial electrolysis was carried out at applied external voltages of 0.8 V and 1.0 V. Experiments with an abiotic control were also performed. At both applied voltages a hydrogen production was registered when a bioanode was used. Cathodic hydrogen recovery of 67 % and 90 % was achieved at 0.8 V and 1.0 V, respectively.
Keywords: microbial electrolysis cell, Lactobacillus plantarum АС 11S, biocatalyst, hydrogen production
Khimiya. 24, 425-432 (2015) Author(s): G. Hristov, E. Chorbadzhiyska, M. Mitov:
Abstract.In this study, Pd and Au were deposited on Ni-foam and examined as electrocatalysts for borohydride electrooxidation. The Pd-Au deposits were developed by co-deposition from mixed solutions of Pd2+ and Au3+ with different ratios of both metals. The corrosion resistance of the obtained materials in 6M KOH electrolyte was evaluated by linear voltammetry. The electrocatalytic performance of the developed electrodes towards borohydride electrooxidation reaction was analysed by means of chronopotentiometric and anodic polarization measurements in stabilized alkaline solution of sodium borohydride. The obtained results with different electrodes were compared and discussed in respect to their potential application as anodes in Direct Borohydride Fuel Cells.
Keywords: Pd-Au catalyst, borohydride electrooxidation, direct borohydride fuel cell
Khimiya. 24, 433-440 (2015) Author(s): I. Bardarov, Y. Hubenova, M. Mitov:
Abstract.Sediment Microbial Fuel Cells (SMFCs) are considered as reliable devices for conversion of the chemical energy of organic matter, containing in aquatic sediments, into electrical energy. In this study, nine freshwater SMFCs were connected in series or in parallel and used for charging ultracapacitors in different switch modes. Several methods for boosting voltage were explored in order to gain usable values for supplying low-power electronic devices or sensors. The collected data were compared and the optimal regime was selected for further development of power management system, based on the use of SMFCs as autonomous power sources.
Keywords: sediment microbial fuel cell, energy conversion, bioelectrochemical power sources, power management system
Khimiya. 24, 441-448 (2015) Author(s): P. Petrova, I. Karadjova, M. Chochkova, I. Dakova:
Abstract.The degree of extraction of Au (III) from hydrochloric acid solutions on 4-aminoantipyrine Schiff bases modified silica gel was studied. Quantitative sorption of Au (III) on the surface of the sorbent containing azomethine group was achieved in the presence of 0.1-1 mol/L HCl. Metal retained on the sorbent surface can be recovered with 0.7 M thiourea in 2 M HCl as eluent, with desorption efficiency exceeding 99 %. FAAS was used to quantify Au (III) in eluates and effluates. The presence of competitor ions as Al (III), Cu (II), Fe (III), Mn (II), Ni (II), Zn (II) has unsignificant influence on binding properties of sorbent.
Keywords: solid phase extraction; noble metals; 4-aminoantipyrine schiff base
Khimiya. 24, 449-465 (2015) Author(s): N. Velitchkova, P. Petrova, S. Velichkov, N. Daskalova:
Abstract.The economic importance of rare earth elements and platinum group of elements has led to the development of analytical methods, which have to ensure their accurate quantification in different type of samples. Radial viewing 40.68 MHz inductively coupled plasma optical emission spectrometry (ICP-OES) and the Q - concept for the quantification of spectral interference were used in the determination of rare earth and platinum group of elements in materials with variable matrix constituents. Improvement of the detection limits was achieved by optimal line selection in the presence of different matrix constituents and by optimization of the operating conditions. The Mg II 280.270 nm/Mg I 285.213 nm line intensity ratios was measured to evaluate the robustness of the operating conditions. The lowest detection limits were obtained under non-robust conditions in a pure solvent and in the presence of rare earth matrices (excitation temperature 6200 K). In the case of platinum group of elements in the presence of complex matrix, containing Al, Ca, Fe, Mg, Mn, P and Ti, the lowest detection limits were derived under robust conditions (excitation temperature 7200 K).
Keywords: ICP-OES, rare earth elements, platinum group elements, matrix effects, detection limits
Khimiya. 24, 466-470 (2015) Author(s): K. B. Omarov, Z. B. Absat, S. K. Aldabergenova, A. B. Siyazova, N. J. Rakhimzhanova, Z. B. Sagindykova :
Abstract.Industrial production of copper solutions, in addition to the basic components (Cu, Ni), contain undesirable impurities which include arsenic and antimony. The process of withdrawal of antimony in copper electrolyte with calcium carbonate, which is present in nature as known minerals and in many cases is a waste product. The use of calcium carbonate to clean technology solutions allows you to bring the content of antimony to the optimum content.
Keywords: copper production, electrolyte, antimony, calcium carbonate, copper, calcium antimonate