bluuebunny/crossref_metadata_2025 huggingface dataset:
ARCHBISHOP STEPINAC, THE INDEPENDENT STATE OF CROATIA AND WESTERN ALLIES
Authors: KOLJANIN MILAN , KOLJANIN DRAGICA
Published: December 2019

There are various doubts and ambiguities regarding the dispatch of the memorandum by the Government of the Independent State of Croatia (ISC) to the Western Allies asking for military intervention in early May 1945, giving rise to different interpretations in historiography. These varying interpretations are related to the circumstances of the dispatch of the memorandum, its text, the actions of prominent representatives of the Ustasha government, relations between the new Yugoslav authorities and Western allies, especially the British and the role of Archbishop Stepinac and the Holy See in the ISC. In order to understand the memorandum, it is necessary to consider the most important political and military circumstances at the end of World War II in Yugoslavia, especially the politics of the new Yugoslavia and the Western powers, primarily the British. The representatives of the Holy See in the ISC and the Archbishop of Zagreb, Alojzije Stepinac, played an important role in efforts to preserve the Ustasha state. This paper was written based on unpublished and published archival sources and relevant historiographical literature.
WESTERN PERCEPTION OF YUGOSLAVIA DURING 1980
Authors: BEŠTIĆ-BRONZA SLAVOJKA
Published: December 2019

In the late 1970s and early 1980s a new significant wave of cooling in the relations between NATO and the Warsaw Pact dominated various aspects of world politics. In this situation, Yugoslavia was at the centre of an intricate system of relations between the two blocs, especially with projections regarding the future of the country immediately before and after the death of Josip Broz Tito, who as a person then literally symbolized Yugoslavia on the world political scene. With the aftermath of the Iranian Revolution and the Soviet invasion of Afghanistan, the perception of a potential crisis in Yugoslavia absolutely dominated the world media during the first half of 1980. In the months before Tito’s death and during the first year after his funeral, the Western media were very active in trying to predict the fate of the Yugoslav federation and some of the predictions were very pessimistic, especially in the context of expectations of a potential Soviet invasion targeted towards Yugoslavia. In general, the character of Western media analysis of Yugoslav reality underwent a significant evolution in the short term and the viewpoint on the Yugoslav state changed quite rapidly, primarily in the negative context. In this regard, the examples of American, British and West German analytical approaches were particularly illustrative. As it is precisely within these three perceptions that change has been the greatest and most illustrative, it is the intention of this paper to concentrate only on aspects of those three perspectives.
HISTORIOGRAPHICAL WORK OF SIMEON PIŠČEVIĆ: BETWEEN CENTRAL EUROPE AND RUSSIA
Authors: ĐURIĆ ĐORĐE
Published: December 2019

The paper focuses on the historiographical work of Simeon Piščević (1731–1797) History of Serbian People (Istorija srpskog naroda) written in Russia at the end of the 18th century. Simeon Piščević was a Serb who started serving military in the Austrian army during the War of the Austrian Succession and then went to the Russian army, where he got as far as to the rank of general. Miloš Crnjanski partly based the main character of his novel Migrations (Seobe) on this person. The first part of the paper focuses on the history of his manuscript, which remained unknown until the end of the 19th century, while the second part presents the structure of this work, the sources on which the author relied and the methods that Piščević applied as a historian.
Discovering human protein diversity
Authors: Nedelkov Dobrin
Published: December 2019

Current emphasis on discovering and correlating human genetic variations lays the foundation for future studies of human protein diversity. Protein posttranslational processing, along with the translation of genetic variations, results in a complex, variable human proteome. Analyzing these protein variations on a grandeur scale has become feasible with the advent of mass spectrometry. Mass spectrometry is the only detection method today that can universally provide information about specific protein structural modifications, without a priori knowledge of the modification. However, high-throughput separation approaches are needed to effectively prepare the proteins for mass spectrometric interrogation. Such are the immunoaffinity separations that target single proteins by using highly specific antibodies for their affinity retrieval from the biological fluids. The resulting combination of immunoaffinity separation with MALDI-TOF mass spectrometry, termed Mass Spectrometric Immunoassay (MSIA), has been recently applied in two large studies of protein diversity. The results of these studies reveal a human protein diversity that is far more complex than the variations observed at the genetic level. Assessing the human proteome variations among and within populations will be an important future undertaking with significant clinical and diagnostic implications.
A novel environmentally friendly 2,4,6-trinitrotoluene (TNT) based explosive
Authors: Nyanhongo Gibson S. , Aichernig Nina , Ortner Marcus , Steiner Walter , Guebitz Georg M.
Published: December 2019

A novel bioremediation technology has been developed. This technology involves the incorporation of a newly isolated Pseudomonas putida GG04 and Bacillus sp. SF into an explosive formulation to enhance biodegradation of TNT residues and explosives which fail to detonate due to technical problems. The incorporation of these microorganisms into the explosive did not affect the quality of the explosive in terms of detonation velocity while complete degradation of TNT moieties upon transfer in liquid media was observed after 4 days. The incorporated microorganisms sequentially reduced TNT leading to the formation of hydroxylamnidnitrotoluenes (HADNT), 4-amino-2,6- dinitrotoluenes; 2-amino-4,6-dinitrotoluenes, different azoxy compounds; 2,6-diaminonitrotoluenes and 2,4- diaminonitrotoluenes. Aminodinitrotoluenes (AMDNT) and diamninonitrotoluenes (DAMNT) constituted the predominant metabolites which steadily increased achieving 41μM and 63 μM in P. putida GG04 cultures and, 73 μM and 109 μM in Bacillus SF cultures, respectively. Although both microorganisms use NAD(P)H dependent enzymes to transform TNT, P. putida GG04 has a preference for NADPH. The accumulation of AMDNT and DAMNT was effectively prevented in the presence of guaiacol and catechol. A 89 % reduction of AMDNT and a 80 % of DAMNT was achieved in P. putida GG04 cultures, while in Bacillus sp. SF, 91 % and 70 % reduction was achieved. This demonstrates that biodegradation of TNT in the presence of humic material is effective in immobilizing TNT metabolites. Addition of acetonitrile (1:4) to TNT and to its biodegradation products with sequential freezing of the samples at –20 °C was effective in concentrating and enhancing detection signals to identify TNT contaminates sites.
Development and validation of spectrophotometric method for phenylephrine hydrochloride estimation in nasal drops formulations
Authors: Savić Ivana , Nikolić Goran , Banković Vladimir
Published: December 2019

Simple, accurate and reproducible UV-spectrophotometric method was developed and validated for the estimation of phenylephrine hydrochloride in pharmaceutical nasal drops formulations. Phenylephrine hydrochloride was estimated at 291 nm in 1 mol⋅dm-3 sodium hydroxide (pH 13.5). Beer’s law was obeyed in the concentration range of 10–100 μg⋅cm−3 (r2 = 0.9990) in the sodium hydroxide medium. The apparent molar absorptivity was found to be 1.63×103 dm3⋅mol−1⋅cm−1. The method was tested and validated for various parameters according to the ICH (International Conference on Harmonization) guidelines. The detection and quantitation limits were found to be 0.892 and 2.969 μg⋅cm−3, respectively. The proposed method was successfully applied for the determination of phenylephrine hydrochloride in pharmaceutical nasal drops formulations. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 1 %), while being simple, cheap and less time consuming, and hence can be suitably applied for the estimation of phenylephrine hydrochloride in different dosage forms.
Studies on biologically important copper(II) / manganese(II) / uranyl(II) – norvaline binary complexes
Authors: Tewari Brij Bhushan
Published: December 2019

In coordination compounds studies, a knowledge of the magnitude of the stability constants of complexes is necessary for preliminary quantitative treatment. Described herein is a method that involves the use of advanced ionophoretic technique for the study of the equilibria in binary complex systems in solution. This method is based upon the migration of a spot of the metal ion on a paper strip at different pH values of background electrolyte containing 0.1 M perchloric acid and 0.01 M norvaline. A graph of pH against mobility provides information about the nature of the complexation and helps in calculating stability constants. Using this method, the stability constants of binary complexes metal(II) – norvaline have been determined to be (8.11 ± 0.02, 7.03 ± 0.09); (3.77 ± 0.11, 2.39 ± 0.07) and (7.59 ± 0.05, 6.17 ± 0.04) (log K values) for Cu(II), Mn(II) and UO2(II) complexes, respectively, at 35 ºC.
Vibrational study and spectra-structure correlations in magnesium disaccharinate heptahydrate, Mg(sac)2⋅7H2O
Authors: Jovanovski Gligor , Makreski Petre , Šoptrajanov Bojan
Published: December 2019

Infrared and Raman vibrational spectra of magnesium disaccharinate heptahydrate, Mg(sac)2⋅7H2O, in the 4000–380 cm–1 region (for infrared) and 4000–100 cm–1 region (for Raman) were studied. The assignment of the spectra was based on the experimental data for the previously studied metal saccharinates as well as the literature data for the ab initio calculations on the free deprotonated saccharinato species. Special attention was paid to the analysis of the H2O, CO and SO2 stretching modes. The spectral picture in the regions of the water, carbonyl and sulfonyl stretches is correlated with the number of the crystallographically determined non-equivalent H2O, CO and SO2 structural units. It was found that the presence of seven crystallographically different water molecules in the structure (fourteen different Ow⋅⋅⋅O and Ow⋅⋅⋅N distances) is not reflected in the appearance of the expected fourteen IR bands in the region of the OD stretching vibrations of the isotopically isolated HDO molecules. This must be due to the existence in the structure of several Ow⋅⋅⋅O or Ow⋅⋅⋅N hydrogen bonds with very similar strengths causing an overlap of the corresponding bands in the spectrum. Despite the presence of two carbonyl groups with practically identical C–O distances [124.2(3) and 124.0(3) pm], two clearly separated bands are registered in the carbonyl stretching region of the IR (1660 and 1627 cm–1) and Raman spectrum (1648 and 1620 cm–1). On the other hand, although two nonequivalent SO2 groups are present in the structure of Mg(sac)2⋅7H2O, only one pair of bands due to SO2 stretchings [νas(SO2 and νs(SO2) modes] is registered in the IR spectrum.
Application of micro-raman and ft-ir spectroscopy in forensic analysis of automotive topcoats in the Republic of Macedonia
Authors: Skenderovska Maja , Minčeva-Šukarova Biljana , Andreeva Liljana
Published: December 2019

Raman and infrared spectroscopy are two complementary spectroscopic techniques that can produce fast, efficient and accurate detection of the pigments and/or binders used in automotive topcoats. Micro-Raman spectroscopy, due to its non-destructiveness, has been extensively used for identification of pigments and dyes in forensic investigation of hit-and-run accidents. This technique provides very useful and significant information from very small samples of evidence without any previous preparation of the sample. The recorded Raman spectra of the unknown/ suspected samples can be compared with a spectrum of the referent sample, which can coincide with the one already existing in the Raman database of pigments. In order to form our own spectral database of automotive paints for forensic investigations in hit-and-run offences in Republic of Macedonia, an investigation of automotive topcoats of different origins was carried out. In our previous study, pigments in some automotive topcoats, produced by Mobihel, have been identified using micro- Raman and FT-IR spectroscopy. In the present study, we report micro-Raman and FT-IR spectra of ten base coat automotive topcoats, as well as some of their mixtures, produced by Glasürit. In order to demonstrate the availability and/or the advantages of the micro-Raman spectroscopic technique in forensic investigation in road accidents, four successfully solved cases from the police investigation in hit-and-run accidents are presented in this work.
Determination of dimethoate, 2,4-dichlorophenoxy acetic acid, mecoprop and linuron pesticides in environmental waters in Republic of Macedonia by high performance liquid chromatography
Authors: Nestorovska-Krsteska Aleksandra , Mirčeska Meri , Aaron Jean-Jacques , Zdravkovski Zoran
Published: December 2019

An HPLC-UVDAD method for determination of dimethoate, 2,4-dichlorophenoxy acetic acid (2,4-D), mecoprop (MCPP) and linuron in environmental waters was developed. The water samples were concentrated and extracted by a solid phase extraction (SPE) method on Bond Elut PPL cartridges. After extraction the investigated compounds were separated on Stability RP Pesticides chromatographic column using mobile phase composed of acetonitrile- water-acetic acid in volume fractions of 39:59:2 and flow rate of 0.7 mL/min. Ultraviolet absorption detection was carried out for dimethoate, 2,4-D and MCPP at 229 nm, and for linuron at 249 nm. Recoveries made from 500 mL of drinking waters using solid phase extraction ranged between 64.3–92.1 %. The method was applied to environmental waters in Macedonia that receive runoffs from agriculture lands. The levels of pesticides under study ranged between 0.31 μg/L and 7.05 μg/L, depending on the compound and sampling period.
Polymer composites containing waste dust from power production I. Influence of particles’ mechanical activation on composite’s strength characteristics
Authors: Koleva Milena , Vassilev Venceslav , Vassilev Gergo
Published: December 2019

Polymer composites containing filler of waste dust from power production were studied. Waste particles were mechanically treated at room temperature for 30 minutes and the influence of mechanical activation on particles size distribution, chemical composition, and shape was established. Composites’ strength characteristics (bending, compressive and impact strength) were tested depending on the amount of waste dust in the composite. The optimal results were achieved at waste concentrations up to 10 wt. %.
Experimental design approach for the development and validation of an enantiospecific RP-HPLC method for simultaneous determination of clopidogrel and related compounds
Authors: Petkovska Rumenka , Cornett Claus , Dimitrovska Aneta
Published: December 2019

An enantiospecific RP-HPLC method was developed and validated for the simultaneous determination of clopidogrel and four related compounds specified as impurities. Experimental design was applied during the method optimization (Full factorial 23 design) and robustness testing (Central Composite Face Centered design). Laboratory mixtures of clopidogrel and its impurities in a concentration ratio of 1: 5.0×10–4 were used as an investigation matrix. The three independent variables were the acetonitrile content in the mobile phase, pH of the mobile phase, and the column temperature. A Chromatographic Response Function (CRF) was used for estimation of the system response resolution (Rs). Separation was achieved using mobile phase composition of ACN: Buffer solution pH 6.5 (40:60 v/v) at 30 ºC. A CHIRAL-AGP 4.0 mm × 100 mm, 5.0 μm particle size column was used. The total time for chromatographic separation was approximately 10.0 min. The method was validated for its selectivity, linearity, precision, accuracy and robustness.
Assay of the phenolic profile of merlot wines from Macedonia: Effect of maceration time, storage, SO2 and temperature of storage
Authors: Ivanova Violeta , Stefova Marina , Vojnoski Borimir
Published: December 2019

Spectrophotometric assays of total anthocyanins, total phenolics, total catechins, total flavonoids, color intesity and hue were performed on Merlot wines obtained with 3, 6 and 10 days of maceration, containing 30 and 70 ppm SO2. Changes of phenolic contents were observed during three stages of the wines: after maceration, after 6 and 16 months in order to check the effect of maceration time, SO2 and storage of the wines. Wines were stored at low and higher temperature to check also the influence of storage temperature on the studied parameters. It was found that maceration time influences the content of polyphenol compounds, observing increasing of their concentrations with increased maceration time, while lower contents were measured in the wines after 16 months of storage (3006, 1732 and 1602 mg/l total phenolics and 478, 188 and 98.5 mg/l total anthocyanins, after maceration, after 6 and 16 months of storage, respectively, in wine with 30 ppm SO2). SO2 had not a significant effect, whereas higher temperature caused slight changes of polyphenols contents.
Effect of extraction techniques on yield and composition of soybean oil
Authors: Nikolić Nada Č. , Cakić Suzana M. , Novaković Sanja M. , Cvetković Mirjana D. , Stanković Mihajlo Z.
Published: December 2019

This paper investigated the yield and chemical composition of soy seeds oils obtained by different solvents and by different extraction apparatuses with the aim to compare oils yield and composition. The maximal oil yield with trichloroethylene was achieved by the Soxhlet apparatus after 150 minutes of extraction (21.4 g/100 g) and very satisfactory yield of 20.4 g/100 g, with similar chemical composition, was achieved by reflux, only after 60 minutes. During the Tilepape extraction, the contact of oil with air was continuous and more intensive oxidation reactions occurred and γ-linolenic and linolenic acids were not detected. Between some oil fatty acids and some chemical values, the correlation coefficients were performed by the program STATISTICA version 5.0. The results showed a proper correlation between the iodine value and the oleic acid content as well as between the peroxide value and the linoleic acid content.
Applications of non-linear frequency response for investigation of adsorption systems
Authors: Petkovska Menka
Published: December 2019

Two main directions of application of nonlinear frequency response and the concept of higher order frequency response functions (FRFs) in investigation of adsorption systems are presented, one for development of novel methods for investigation of equilibrium and kinetics of adsorption systems, and the other for fast estimation of periodic steady-states of cyclic adsorption processes. The main advantages of the nonlinear FR methods for estimation of adsorption equilibrium and kinetics are: (1) It is possible to discriminate between different kinetic mechanisms and to select the correct one from the shapes of the second and higher order FRFs. (2) Both equilibrium and kinetic parameters can be estimated from the FRFs. Different experimental arrangements are presented. Estimation of periodic steady-states of cyclic adsorption processes is illustrated on the example of periodic operation of an adsorption column with modulation of the inlet concentration and the column temperature.
Simultaneous determination of sulfonylurea herbicide synthetic binary mixtures by a partial least square method combined with micellar-enhanced photochemically-induced fluorescence application to tap water analysis
Authors: Coly Atanasse , Aaron Jean-Jacques
Published: December 2019

A combination of the partial least square method in its first variable (PLS-1) with micellar-enhanced photochemically- induced fluorescence (MEPIF) was developed for the simultaneous determination of synthetic binary mixtures of four sulfonylurea herbicides in aqueous micellar solutions, and applied to tap water analysis. Because of their similar features, the MEPIF emission spectra of these herbicides were found to severely overlap in the whole wavelength region. After optimization of the calibration matrix, the PLS-1-MEPIF method was applied to the resolution of chlorsulfuron/metsulfuron methyl and sulfometuron methyl/3-rimsulfuron binary mixtures. The analytical results obtained by the PLS-1-MEPIF method were presented and compared to those of the first-derivative PIF one. An application of the PLS-1-MEPIF method to the quantitative analysis of Paris tap water samples spiked with the herbicide binary mixtures led to recovery values ranging between 63 and 118 %, depending on the mixture.
Meteorite Struga – overview of previous chemical and recent spectroscopic analyses
Authors: Minčeva-Šukarova Biljana
Published: December 2019

Meteorite Struga fell more than 35 years ago near the town of Struga, Republic of Macedonia. Its fall was notified in the Bulletien of the Geological Institute in Skopje in 1973. Since that time, only one chemical analysis has been reported (in 1990) and most recently, preliminary spectrosocpic investigations (in 2006 and in 2008) have been performed. However, this meteorite has not yet been classified in the World’s Database of Meteorites. The aim of this paper is to collect and summarize all available data published until now on this meteorite and open the possibility to clasify it and list it in the World’s Database of Meteorites. In order to make the results more available, the details of the previous chemical and the recent spectrosocpic analyses on this meteorite are presented in this paper. Collected information from both analyses were used for the description of the characteristics of this meteorite. Previous chemical analysis and the recent spectrosocpic investigations are in good agreement and confirm the earlier classification of this meteorite as stony chondrite of H type.
Wiener and detour indices of a new type of nanostar dendrimers
Authors: Karbasioun A. , Ashrafi Ali Reza
Published: December 2019

The Wiener and detour indices of a molecular graph G are defined as the sum of the lengths of all shortest and longest paths between the vertices of G. In this paper the exact formulae for the Wiener and detour indices of a new type of nanostar dendrimers are given.
Modification of β-galactosidase for use in organic mono-phase hexanol system
Authors: Nikolovska-Nedelkoska Daniela , Mladenoska Irina , Poposka Filimena , Winkelhausen Eleonora , Kuzmanova Slobodanka
Published: December 2019

Different methods for preparation of the Aspergillus oryzae β-galactosidase were evaluated and the total enzyme activity was determined in hexanol mono-phase system using p-nitrophenyl-β-D-galactoside as a substrate. Several supports such as Acurell EP-100, Amberlite IRC (50), Celite, Dowex, Eupergit C and silica gel were tested in order to select the most suitable matrix for immobilization of the β-galactosidase for performing transgalactosylation reactions in hexanol. Celite and Amberlite IRC (50) were selected as the most appropriate carriers. Albumin, PEG 6000, starch and glycine, added prior to the immobilization procedure, acted as stabilizers of the galactosidase. By adding albumin on Celite, a 3.3-fold increase of enzyme activity was achieved. Sodium dodecyl sulphate (SDS), dioctyl sulfosuccinate (AOT), Tween 65 and crown ether were used directly in the reaction medium in order to increase its homogeneity. Addition of SDS to the medium resulted in a 3.65-fold increased activity of the β- galactosidase deposited on Celite. A micro-emulsion system created by addition of AOT resulted in an increased catalytic activity. The β-galactosidase showed enhanced total activity with increased water activity in the system having the highest value for the water activity close to the saturation level (0.92).
Preparation and recycling of polymer eco-composites I. comparison of the conventional molding techniques for preparation of polymer eco-composites
Authors: Srebrenkoska Vineta , Bogoeva Gaceva Gordana , Dimeski Dimko
Published: December 2019

The interest in natural fiber-reinforced polymer composites is growing rapidly due to their high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. In this study, the compression and injection molding of polypropylene (PP) and polylactic acid (PLA) based composites reinforced with rice hulls or kenaf fibers was carried out and their basic properties were examined. Rice hulls from rice processing plants and natural lignocellulosic kenaf fibers from the bast of the plant Hibiscus Cannabinus represent renewable sources that could be utilized for composites. Maleic anhydride grafted PP (MAPP) and maleic anhydride grafted PLA (MAPLA) were used as coupling agents (CA) to improve the compatibility and adhesion between the fibers and the matrix. Composites containing 30 wt % reinforcement were manufactured by compression and injection molding, and their mechanical and thermal properties were compared. It was found that the techniques applied for manufacturing of the eco-composites under certain processing conditions did not induce significant changes of the mechanical properties. The flexural strength of the compressed composite sample based on PP and kenaf is 51. 3 MPa in comparison with 46.7 MPa for the same composite produced by injection molding technique. Particularly, PP-based composites were less sensitive to processing cycles than PLA-based composites. The experimental results suggest that the compression and injection molding are promising techniques for processing of eco-composites. Moreover, the PP-based composites and PLA-based composites can be processed by compression and injection molding. Both composites are suitable for applications as construction materials.
Study of molten Li2Co3 electrolysis as a method for production of carbon nanotubes
Authors: Dimitrov Aleksandar T.
Published: December 2019

The production of carbon nanotubes (CNTs) by electrolysis in molten Li2CO3 was investigated by studying the effect of the electrolyte, temperature of the electrolyte and cathodic overpotential. Cyclic voltametry clearly shows that instead of the expected Li discharge of the cathode as a first reaction, some early electrochemical reaction starts at a potential of –0.1 V, as a result of which, instead of the expected process of intercalation into the graphite lattice and CNTs formation, deposition of carbon occurs with the graphite cathode acting as the substrate. The carbon deposit obtained during the process of electrolysis together with the solidified salt, after dissolving in water, filtering and drying, was inspected with scanning electron microscopy (SEM). The results show that, among the observed structures and impurities, there are no CNTs. The morphology of the product is different from others previously observed, with a shape like sheets of flowers, and very small nano-balls. The impurities are metal particles from the salt and the impurities originating from the salt. For better understanding and confirmation of these result, cyclic voltametry and electrolytic deposition of carbon on a molybdenum electrode was also investigated. Molten LiCl was used as a base electrolyte with adding of 1, 5 and 10 % of Li2CO3. SEM observations and cyclic voltammograms confirm that under those conditions a process of carbon deposition occurs.
Paper ionophoretic technique in the study of biologically important beryllium(II) / cobalt(II)-homoserine binary complexes in solution
Authors: Tewari Brij Bhushan
Published: December 2019

Quantitative indication of the process of forming a complex comes from the evaluation of the stability constants, which characterize the equilibria corresponding to the successive addition of ligands. A method, involving the use of paper electrophoretic technique is described for the study of binary complex system in solution. Present method is based upon the migration of a spot of metal ions on a paper strip at different pH’s of background electrolyte. A graph of pH against mobility gives information about the binary complexes and permits calculation of their stability constants. The first and second stability constants of [Be(II)-homoserine] and [Co(II)-homoserine] complexes were found to be (7.13 ± 0.02; 6.11 ± 0.09) and (4.27 ± 0.07; 3.47 ± 0.11) (logarithm stability constant values) for Be(II) and Co(II) complexes, respectively, at ionic strength of 0.1 mol/L and a temperature of 35 °C.
New, simple and validated UV-spectrophotometric methods for the estimation of sodium usnate in preparations
Authors: Savić Ivana , Nikolić Goran , Savić Ivan , Zlatković Saša , Djokić Dragiša
Published: December 2019

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of sodium usnate in pharmaceutical preparations. Sodium usnate was estimated at 290 nm in water and phosphate buffer (pH 3):methanol (11:20 V/V). Beer’s law was obeyed in the concentration range of 0.1–5 μg·cm−3 (r = 0.997) in water and 1–12 μg·cm−3 (r = 0.999) in the phosphate buffer:methanol. The apparent molar absorptivity and Sandell’s sensitivity coefficient were found to be 3.16×104 dm3·mol−1·cm−1 and 11.58 ng·cm–2/0.001 A in water and 3.72×104 dm3·mol−1·cm−1 and 9.83 ng·cm–2/0.001 A in phosphate buffer:methanol, respectively, indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0721 and 0.2163 μg·cm–3 in water and 0.163, 0.489 μg·cm−3 in phosphate buffer:methanol, respectively. The proposed methods were successfully applied for the determination of sodium usnate in pharmaceutical preparations. The results demonstrated that the procedure is accurate, precise and reproducible (R.S.D. < 2 %).
Luminescence methods for study and determination of pollutants in the environment
Authors: Morales Tanausú Vega , Esponda Sarah Montesdeoca , Rodríguez José Juan Santana , Efremova Aaron Snezhana , Aaron Jean-Jacques
Published: December 2019

The analytical performances and applications of various luminescence spectrometric methods to the study and determination of pollutants present at low levels in the environment are reviewed for the last two decades (1990 – 2010). The first part concerns luminescence stationary systems, including fluorescence, photochemically-induced fluorescence, phosphorescence and related luminescence methods. In the second part, the combination of these luminescence methods with flow techniques such as high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and flow injection analysis (FIA) for the detection and determination of environmental pollutants is investigated. A part of the review is also devoted to the usefulness of organized supramolecular systems, such as micellar media, cyclodextrins and calixarenes, for improving the efficiency of luminescence methods.
Physical and chemical parameters impact on eosin spectral determinations
Authors: Kola Liljana
Published: December 2019

The fluorescence ability of Eosin enables its using as an artificial tracer in the water system studies. The problem deals with the application of Eosin to trace and determine water movements within the karstic system and under ground waters. The fluorescence intensity of fluorescent dyes in water samples depends on their physical and chemical properties, such as pH, temperature, presence of oxidants, etc. Besides that, the UV radiation may induce photochemical decomposition of Eosin which can cause large measurement errors. This paper presents the taken results studying the influence of these factors on Eosin fluorescence intensity using the concentration and synchron scan methods. The method we have elaborated for this purpose made it possible to optimize procedures we use to analyze water samples for the presence of Eosin and measure its content, even in trace levels by the means of the Perkin Elmer LS 55 Luminescence Spectrometer.
Kinetic and equilibrium studies of methylene blue removal from aqueous solution by adsorption on treated sawdust
Authors: Bello Olugbenga Solomon , Adelaide Oladipo Mary , Hammed Misbaudeen Abdul , Popoola Olalekan Abdul Muiz
Published: December 2019

The aim of this study is to use treated sawdust as an adsorbent for the removal of methylene blue (MB) dye. The adsorption equilibrium and kinetics of methylene blue dye on this adsorbent were then examined at 25 ºC. The adsorption isotherm of the methylene blue on the treated adsorbent was determined and correlated with common isotherm equations. The sorption data were then correlated with the Langmuir and the Freundlich adsorption isotherm models. The Langmuir isotherm exhibited a better fit for the adsorption data than the Freundlich isotherm with maximum monolayer adsorption capacity of 236.16 mg g–1. The kinetics of methylene blue adsorption on the treated adsorbent has also been studied by fitting the data in the Lagergren’s first order, the Ho-McKay’s pseudo second order, the Elovich and the Intraparticulate kinetic models. It was observed that the removal of methylene blue over the treated adsorbent undergoes the second order processes at all the concentrations of the dye. The kinetic parameters of this best-fit model were calculated and discussed.
Study of organochlorine pesticide residues in water, sediment and fish tissue in Lake Ohrid (Macedonia/Albania)
Authors: Veljanoska-Sarafiloska Elizabeta , Jordanoski Momčula , Stafilov Trajče , Stefova Marina
Published: December 2019

A systematic study has been performed for determination of a range of organochlorine pesticides in the water, sediments and fish samples in the Macedonian part of the Lake Ohrid and its larger tributaries. The obtained results give an overview of the contamination levels of these problematic compounds (i) at their potential sources in the river mouths, (ii) in the potentially affected, species-rich littoral section of the lake, and (iii) in the muscle tissue of one selected fish species Barbus peloponnesius, Valenciennes, collected near the rivers’ deltas. The organochlorine pesticides measured in all three matrixes were: γ-HCH, ΣHCH (sum of α-isomer, β-isomer and δ-isomer), endosulfan (total of α and β endosulfan), DDT metabolites (p,p’-DDE, p,p’-DDD and p,p’-DDT). The range of the observed concentrations for p,p’-DDT was between 0.006 μg l–1 in the water samples from Daljan and St. Naum and 0.036 μg l–1 in the water from the Koselska River. The values for p,p’-DDT measured in dry sediment ranged from 0.121 μg kg–1 in the sample from St. Naum to 1.8 μg kg–1 in the dry sediment from the Velgoška River and between 0.553 μg kg–1 for total endosulfan and 5.982 μg kg–1 for p,p’-DDE of wet fish biomass. The most abundant of the detected organochlorine pesticides was the sum of DDT metabolic forms, i.e. p,p’-DDT, p,p’-DDE and p,p’-DDD. The detected concentrations are clearly below toxic thresholds and consequently severe effects on the endemic species of Lake Ohrid are not very likely.
Dissolved inorganic antimony, selenium and tin species in water samples from various sampling sites of river vardar in Macedonia and Greece
Authors: Serafimovska Jožica Majda , Arpadjan Sonja , Stafilov Trajče , Ilik Popov Stanko
Published: December 2019

A highly effective liquid phase semi-microextraction procedure was applied for determination ofultra trace levels of dissolved inorganic species of antimony, tin and selenium in river Vardar (from the 2ndup to 420th km of the river) and its tributaries Crna Reka, Treska, Bregalnica, Pchinja and Lepenec usingelectrothermal atomic absorption spectrometry (ETAAS) for quantification. The concentrations for totaldissolved inorganic antimony were between 6 and 242 ng/l Sb, for Sn(II, IV) – in the range of 2.7–61 ng/lSn and for Se(IV, VI) – in the range of 15–75 ng/l Se. The higher oxidation states of antimony and seleniumwere found as the predominant form in the studied surface waters.
Removal of gas-phase benzene in an immobilized photocatalytic reactor
Authors: Jagannathan* Krishnan , Swaminathan Tyagarajan
Published: December 2019

The photocatalytic degradation of gas-phase benzene was studied in an immobilized – annular tube reactor using titanium dioxide as the photocatalyst. The main and interaction effects due to the influence of essential process parameters such as catalyst load (5 to 20 g·m–2), benzene concentration (0.2 – 3.1 g·m–3) and flow rate (0.2 to 1 l·min–1 corresponding to residence times of 14 s and 70 s respectively) on the removal of benzene were investigated, by carrying out experiments that were designed to express statistical significance. The main effects plot and Pareto plot provided good insight into the effect of different parameters on the removal of gas-phase benzene. A new, statistical measurement suggests that low gas–phase benzene concentration is more important for maintaining high removal efficiencies (96 %) in the photocatalytic reactor than both catalyst load and flow rate.
Simple and efficient method for detection of traces of rare earth elements in minerals by raman spectroscopy instrumentation
Authors: Makreski Petre , Jovanovski* Gligor , Runčevski Tomče , Jaćimović Radojko
Published: December 2019

As an effort to increase the knowledge about the abundance, distribution and geochemical behaviorof the rare earth elements (REEs), a simple and effective Raman spectroscopic method for detection of REEsin minerals is proposed. The proposed method based on Raman spectroscopy provides a lower detectionlimit for REEs compared to the modern analytical techniques. It could be practiced even in laboratoriesequipped only with FT-Raman instrumentation. This simple, inexpensive, rapid and straightforward Ramanmethod for REEs detection in minerals is a convenient experiment for undergraduate and postgraduatelaboratory courses.
Morphology and structure of bright electrodeposited metal coatings
Authors: Pavlović Miomir G. , Pavlović Ljubica J.
Published: December 2019

The properties which determine whether the metal surface is mirror bright are precisely determined by scanning electron microscopy (SEM), atomic forces microscopy (AFM), scanning tunneling microscopy (STM) and reflectance spectrophotometry investigations. Mirror brightness of metal surfaces can be associated with the high degree of mirror reflection which approaches very nearly the ideal reflectance of the same metal with the lowest degree of diffuse reflection. Mirror brightness of the copper coatings and the copper surfaces polished both mechanically and electrochemically was determined by flat and mutually parallel parts of the surface, which are smooth on the atomic level and which point out towards layer structure of these surfaces. Mirror bright metal surfaces can be obtained only by electrochemical polishing or electrochemical deposition in the presence of brightening addition agents.
Electrocatalytic activity of hypo–hyper-d-electrocatalysts (Me/TiO2/MWCNTs) based on Co-Ru in alkaline hydrogen electrolyser
Authors: Paunović Perica , Popovski Orce , Stoevska Gogovska Dafinka , Lefterova Elefteria , Slavcheva Evelina , Dimitrov Aleksandar T.
Published: December 2019

This study is concerned with preparation and characterization of Co-Ru based hypo-hyper d-electrocatalysts aimed for water electrolysis. The composition of the studied electrocatalysts was: 10 % mixed metallic phase (Co : Ru = 1 : 1 wt., Co:Ru = 4 : 1 wt. and Co : Ru : Pt = 4 : 0.5 : 0.5), 18 % TiO2 as a crystalline anatase deposited on activated multiwalled carbon nanotubes (MWCNTs). For comparison, corresponding electrocatalysts with pure hyper d-metallic phase (Co and Ru) were prepared. The structural characterization of the studied electrocatalysts was performed by means of XRD, SEM and FTIR analysis. The prepared hypo-hyper d-electrocatalysts were electrochemically studied by cyclic voltammetry and potentiodynamic method in the alkaline hydrogen electrolyser. The order of the catalytic activity for hydrogen evolution of studied electrocatalysts was the following: Ru > CoRuPt (4 : 0.5 : 0.5, wt.) > CoRu (1 : 1 wt.) > CoRu (4 : 1 wt.) > Co. The electrocatalyst with only 20 % precious metals (Pt and Ru) in the metallic phase (the rest being Co-metal) exhibited excellent performance approaching that of the electrocatalyst with 100 % precious metallic phase (Ru).
Electrometallurgy: electrochemical, economic and environmental (3E) aspects
Authors: Paunović Perica
Published: December 2019

This paper is concerned with electrolysis processes aimed for production and refining of metals. This engineering field is named electrometallurgy. The main aspects of electrometallurgy such as electrochemical, energetic/economic and environmental ones are given. The peculiarity of electrorefining and electrowining in both aqueous electrolytes and molten salts are shown. The impact of energetic parameters, such as cell voltage and current efficiency on the economic justification of the electrolysis process is analyzed. It is emphasized that electrolysis is considerably cleaner technology than the pyrometallurgical production and refining of metals.
Dielectric constant and induced dipole moment of edible oils subjected to conventional heating
Authors: Pecovska Gjorgjevich Margareta , Andonovski Aleksandar , Velevska Julijana
Published: December 2019

The frequency dependence of dielectric constant, dielectric loss factor and conductivity are studied for five edible oils in the frequency range 100 kHz to 13 MHz at different temperatures using frequency domain spectroscopy. The dielectric constant is found similar for all the samples and in agreement with the previous reports. The dielectric loss is low (<0.01) except for the virgin olive oil with value of 0.05. Dielectric loss peak frequency is at  4 MHz for corn oil and around 5.2 MHz for the others. At this frequency conductivity is of the order of 10-7-10-9 S/cm, and decreases with temperature following the behavior of the dielectric losses. Refractive index, molar and orientation polarization are calculated for all types of oils using novel theory proposed by N. M. Putintsev and D. N. Putintsev [1]. Data show that the orientation polarization contributes to the observed dielectric constant at low temperatures and frequencies.  This indicates that the edible oils are not pure nonpolar dielectrics. Induced dipole moments of oils are calculated for 400 kHz and 10 MHz at 300 K and 318 K. The results are discussed and correlated as a function of temperature and frequency to establish their relationship.
Characterization of urinary bioactive phenolic metabolites excreted after consumption of a cup of mountain tea (Sideritis scardica) using liquid chromatography – tandem mass spectrometry
Authors: Petreska Stanoeva Jasmina , Bagashovska Daniela , Stefova Marina
Published: December 2019

A nutrition experiment was performed for studying the bioavailability of polyphenols from Sideritis with healthy human subjects, who consumed a standardized Sideritis decoction after which urine was collected and analyzed. 35 polyphenolic compounds in the ingested decoction and 63 of their metabolites in urine collected after ingestion were identified using HPLC/MSn. It was shown that polyphenols present in Sideritis decoction are extensively conjugated to glucuronides, sulfates and also transformed to methylated forms after oral administration. In the analyzed urine samples, 31 different metabolites of hypolaetin, methylhypolaetin, isoscutellarein, methylisoscutellarein and apigenin, and 32 phenolic acids metabolites were detected, hypolaetin and isoscutellarein metabolites being the most abundant. This enabled polyphenols metabolites patterns to be obtained, which is a crucial step towards revealing the bioavailability and metabolism of phenolic compounds from Sideritis in human. The identification and structure elucidation of these metabolites provided essential data for further studies of Sideritis polyphenols bioavailability.
Analytical application of acidic victoria blue 4R mixture with KBrO3 for the kinetic determination of traces of antimony(III) by spectrophotometry
Authors: Mitić Violeta , Nikolić-Mandić Snežana , Stankov-Jovanović Vesna
Published: December 2019

The present paper describes a simple, selective and sensitive kinetic method for the determination of trace amounts of Sb(III) in the presence of Sb(V) based on its inhibition effect on the redox reaction between bromate and Victoria blue 4R (V.B. 4-R) in hydrochloric acid media. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of V.B. 4-R at 596.3 nm. Optimum operating conditions regarding reagent concentrations were established. The optimized conditions yielded a theoretical detection limit of 1.30·10‒8 g cm–3 Sb(III) based on the 3S0 criterion. The method allows the determination of Sb(III) in the range of 5·10‒8 ‒ 1.1·10‒6 g cm–3. The effects of certain foreign ions the reaction rate were determined for an assessment of the selectivity of the method. The kinetic parameters of the reaction were reported, and the rate equations were suggested. The results were validated statistically and through recovery studies. The proposed method has been successfully applied to the determination of Sb(III) in various model and real samples.
RP-HPLC-DAD method for simultaneous determination of desmedipham, phenmedipham and ethofumesate in a pesticide formulation
Authors: Velkoska-Markovska Lenče , Petanovska-Ilievska Biljana , Vodeb Lila
Published: December 2019

A fast, simple, precise and accurate reversed-phase high-performance liquid chromatography (RPHPLC)method with UV-DAD for simultaneous determination of desmedipham, phenmedipham and ethofumesate in the pesticide formulation “Inter OF” has been developed. The analysis was performed on a LiChrospher 60 RP-select B (25 cm × 0.4 cm, 5 μm, Merck) analytical column, with mobile phase of methanol/water (60/40, V/V), flow rate of 1 ml/min, UV-detection at 230 nm and constant column temperature at 25 ºC. The following parameters were determined for the developed method: retention factor, separation factor, limit of detection (LOD), limit of quantification (LOQ), precision of obtained results for peak area, linearity, recovery of analyte and active ingredients quantity in a pesticide formulation.
Ceric ammonium nitrate and manganese(III) acetate mediated radical oxidation and addition reactions of anthracene and 9-substituted anthracenes
Authors: Zengin Mustafa , Sonmez Faith , Arslan Mustafa , Kucukislamoglu Mustafa
Published: December 2019

Radical oxidation and addition reactions of anthracene (1), 9-methylanthracene (2) and 9-phenylanthracene (3) were investigated with dimethyl malonate (4) in the presence of ceric ammonium nitrate (CAN) and manganese(III) acetate (Mn(OAc)3). Although mostly anthraquinone derivatives and bianthrone were obtained with CAN, substituted 9,10-dihydroanthracene and 9,10-substituted anthracene derivatives were obtained with Mn(OAc)3. Dimethylmalonyl addition products (5a, 33 % and 5b, 42 %) were obtained in higher yield than quinones (5d, 8 % and 5e, 3 %) using Mn(OAc)3 as oxidant. 9a (96 %) and 9b (84 %) were synthesized in high yield and substitution products (7a, 44 % and 8b, 56 %) were obtained in higher yields than quinones (5d and 5e) using CAN as oxidant. The reactions were carried out in non-acidic medium (dichloromethane and methanol). Based on the structures of the isolated products a mechanism for these transformations was proposed.