<abstract xmlns="http://www.w3.org/1999/xhtml"> The foaming and emulsifying properties of pectins obtained from waste rose petals, citrus pressings, grapefruit peels and celery were studied. It was found that the highest foaming capacity showed pectin derived from celery. The effect of pectin concentration on the foaming capacity of pectin solutions was investigated. For all the investigated pectins increasing the concentration led to increase of the foaming capacity. Emulsifying activity and emulsion stability of model emulsion systems (50 % oil phase) with 0.6 % pectic solutions were determined. The highest emulsifying activity and stability showed pectin isolated by dilute acid extraction from waste rose petals.</abstract>

Foaming and emulsifying properties of pectin isolated from different plant materials

<abstract xmlns="http://www.w3.org/1999/xhtml">Abstract: Chemical modification of alginic acid has been done by ultrasonic irradiation to obtain its methylated, ethylated and isopropylated derivatives. The influence of ultrasonic frequency and power on esterification process of alginic acid has been investigated. Alginate derivatives have been characterized by degree of esterification (DE) and IR-FT spectroscopy. It has been found that 45 kHz ultrasonic frequency accelerated modification process as reduced the reaction time from 16 hours to 2 hours. The obtained results showed that ultrasound irradiation increased the reaction efficiency in methanol and depended on the ratio of the M/G.</abstract>

Chemical modification of alginic acid by ultrasonic irradiation

<abstract xmlns="http://www.w3.org/1999/xhtml"> A chemometric approach using artificial neural network for clusterization of biodiesels was developed. It is based on artificial ART2 neural network. Gas chromatography (GC) and Gas Chromatography - mass spectrometry (GC-MS) were used for quantitative and qualitative analysis of biodiesels, produced from different feedstocks, and FAME (fatty acid methyl esters) profiles were determined. Totally 96 analytical results for 7 different classes of biofuel plants: sunflower, rapeseed, corn, soybean, palm, peanut, “unknown” were used as objects. The analysis of biodiesels showed the content of five major FAME (C16:0, C18:0, C18:1, C18:2, C18:3) and those components were used like inputs in the model. After training with 6 samples, for which the origin was known, ANN was verified and tested with ninety “unknown” samples. The present research demonstrated the successful application of neural network for recognition of biodiesels according to their feedstock which give information upon their properties and handling.</abstract>

University “Prof. Dr. Assen Zlatarov” Bourgas, Bulgaria

Konstantin Preslavsky University of Shumen, Shumen, Bulgaria

Upon the opportunity to apply ART2 Neural Network for clusterization of biodiesel fuels

<abstract xmlns="http://www.w3.org/1999/xhtml"> Pattern recognition method (PRM) was applied to gas chromatographic (GC) data for a fatty acid methyl esters (FAME) composition of commercial and laboratory synthesized biodiesel fuels from vegetable oils including sunflower, rapeseed, corn and palm oils. Two GC quantitative methods to calculate individual fames were compared: Area % and internal standard. The both methods were applied for analysis of two certified reference materials. The statistical processing of the obtained results demonstrates the accuracy and precision of the two methods and allows them to be compared. For further chemometric investigations of biodiesel fuels by their FAME-profiles any of those methods can be used. PRM results of FAME profiles of samples from different vegetable oils show a successful recognition of biodiesels according to the feedstock. The information obtained can be used for selection of feedstock to produce biodiesels with certain properties, for assessing their interchangeability, for fuel spillage and remedial actions in the environment.</abstract>

University “Prof. Dr. Assen Zlatarov“, Bourgas 8010, Bulgaria

University of Plovdiv “Paisii Hilendarski”, Plovdiv, Bulgaria

Konstantin Preslavski University of Shumen, Shumen, Bulgaria

Determination and discrimination of biodiesel fuels by gas chromatographic and chemometric methods

<abstract xmlns="http://www.w3.org/1999/xhtml"> Trans boundary and local pollution, global climate changes and cosmic rays are the main areas of research performed at the regional Global Atmospheric Watch (GAW) station Moussala BEO (2925 m a.s.l., 42°10’45’’ N, 23°35’07’’ E). Real time measurements and observations are performed in the field of atmospheric chemistry and physics. Complex information about the aerosol is obtained by using a threewavelength integrating Nephelometer for measuring the scattering and backscattering coefficients, a continuous light absorption photometer and a scanning mobile particle sizer. The system for measuring radioactivity and heavy metals in aerosols allows us to monitor a large scale radioactive aerosol transport. The measurements of the gamma background and the gamma-rays spectrum in the air near Moussala peak are carried out in real time. The HYSPLIT back trajectory model is used to determine the origin of the data registered. DREAM code calculations [2] are used to forecast the air mass trajectory. The information obtained combined with a full set of corresponding meteorological parameters is transmitted via a high frequency radio telecommunication system to the Internet.</abstract>

Aerosol and gamma background measurements at Basic Environmental Observatory Moussala

<abstract xmlns="http://www.w3.org/1999/xhtml"> Corrosion is the cause of irretrievable loss of huge amounts of metals and alloys. The harmful effects of corrosion can be reduced significantly by applying appropriate methods of corrosion protection. One method to protect metals against corrosion is the formation of diffusion coatings on them. High corrosion resistance is typical for the boride diffusion layers. Aluminothermy is one of the main methods for diffusion saturation of the surface of metal products with various elements, including boron, and under certain conditions with aluminum, too. Samples of steel 45 were put to aluminothermic diffusion saturation with boron in a pressurized steel container at a temperature of 1100K, for 6 hours in powdered aluminothermic mixtures. The content of В2О3 in the starting mixtures decreased from the optimum - 20% to 0%, and the content of Al and the activator - (NH4)2.4BF3 is constant, respectively 7% and 0.5%. Al2O3 was used as filler. The borided samples were tested for corrosion resistance in 10% HCl for 72 hours. The results show that their corrosion resistance depends on the composition of the starting saturating mixture (mainly on the content of В2О3), and respectively on the composition, structure, thickness and degree of adhesion of the layer to the metal base.</abstract>

Diffusion Coatings as Corrosion Inhibitors

<abstract xmlns="http://www.w3.org/1999/xhtml"> The critical thickness (hcr) for foam films of n-dodecyl β-D maltoside (C12G2) and of its mixed solutions with dodecanol (C12Е0), hexaethyleneglycol dodecyl ether (C12E6) and dodecyl trimethylammonium bromide (C12TAB) of different molar ratio (50:1; 1:1;1:50) at low and high ionic strength was measured interferometrically. It was found that the hcr increases with the increase of the film radius independently of solutions composition. At low ionic strength the type of surfactant affects the critical thickness and the equilibrium state of the film. hcr for the films of mixture with C12E0 increases with the increase of the total surfactant concentration, while hcr for the films of mixture with C12TAB decreases. For the values of the critical thicknesses for films from individual surfactant solutions the following sequence hcr (C12TAB) > hcr (C12E6) > hcr (C12G2) is found. At high ionic strength the quantity of nonionic additive does not substantially affect the value of hcr, while the quantity of ionic additive influences it by two different ways (i) in 50:1 mixture C12TAB supports C12G2 in the reducing of negative charge; (ii) in 1:1 mixture C12TAB recharges the film surfaces. </abstract>

Faculty of Natural Sciences, Konstantin Preslavsky University of Shumen, 115 Universitetska str., 9712 Shumen, Bulgaria

Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Blvd, 1164 Sofia, Bulgaria

Critical thickness of foam films stabilized by nonionic, ionic surfactants and their mixtures

<abstract xmlns="http://www.w3.org/1999/xhtml"> Bacterial EPSs (exopolysaccharides) are believed to play an important role in the environment by promoting survival strategies such as bacterial attachment to surfaces and nutrient trapping, which facilitate processes of biofilm formation and development. These microbial biofilms have been implicated in corrosion of metals, bacterial attachment to prosthetic devices, fouling of heat exchange surfaces, toxicant immobilization, and fouling of ship hulls. In this paper, data on EPS production and the effect of EPS on corrosion of steel produced by Lactobacillus sp. are presented and discussed. Lactobacillus delbrueckii K27, Lactobacillus delbrueckii B8, Lactobacillus delbrueckii KO43, Lactobacillus delbrueckii K3, Lactobacillus delbrueckii K15 and Lactobacillus delbrueckii K17 was obtained from Collection of Department of General and Applied Microbiology, Sofia University. It was tested for its ability to produce exopolysaccharides when cultivated in a media containing 10% sucrose, 10% lacose and 10% maltose. The study of the corrosive stability of steel samples was conducted on the gravimetrique method. The rate of corrosion, the degree of protection, and coefficient of protection have been calculated. The structure of layer over steel plates was analysed by SEM (scanning electron microscopy) JSM 5510. It could be underlined that 10% sucrose, 10% lactose and 10% maltose in the media stimulated the process of protection of corrosion.</abstract>

Exopolysaccharides from lactic acid bacteria as corrosion inhibitors

<abstract xmlns="http://www.w3.org/1999/xhtml"> Cultural heritage of the European civilization constitutes cultural and spiritual property of the ancestors, as well as current generations of the Varna city. It represents both material and non-material value, defines the European culture. It includes all the environmental consequences arising from the interaction between the man and the surroundings over the course of history. Assessment of tourist potential of Varna performed on 9-14th September, 2014, by the members of the “European Traveler” scientific circle, students of tourist and recreation, as well as heritage and culture tourism at Kazimierz Wielki University in Bydgoszcz, made it possible to identify the main points of tourist recognizability in relation to the city and region. The staid points are predominantly based on the unique cultural assets of the city and the region - in large measure related to the origins of the European civilization - as well as current cultural events organized in the city.</abstract>

Cultural heritage of Varna and its tourist recognisability in Europe

<abstract xmlns="http://www.w3.org/1999/xhtml"> The effects of the carbon and nitrogen substrates on the growth of Bacillus sp. SG113 strain were studied. The use of organic nitrogen sources (peptone, beef extract, yeast extract, casein) leads to rapid cellular growth and the best results for the Bacillus strain were obtained with casein hydrolysate. From the inorganic nitrogen sources studied, the (NH4) 2SO4 proved to be the best nitrogen source. Casein hydrolysate and (NH4) 2SO4 stimulated the invertase synthesis. In the presence of Jerusalem artichoke, onion and garlic extracts as carbon sources the strain synthesized from 6 to 10 times more inulinase.</abstract>

Effects of nitrogen and carbon sources on the production of inulinase from strain Bacillus sp. SG113

AHEAD OF PRINT

Volume 11 (2024): Issue 1 (March 2024)

Volume 10 (2023): Issue 3 (November 2023)

Volume 10 (2023): Issue 2 (July 2023)

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Volume 9 (2022): Issue 3 (November 2022)

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Volume 8 (2021): Issue 3 (November 2021)

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Volume 8 (2021): Issue 1 (March 2021)

Volume 7 (2020): Issue 3 (November 2020)

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Volume 7 (2020): Issue 1 (March 2020)

Volume 6 (2019): Issue 2 (December 2019)

Volume 6 (2019): Issue 1 (March 2019)

Volume 5 (2018): Issue 2 (December 2018)

Volume 5 (2018): Issue 1 (March 2018)

Volume 4 (2017): Issue 1 (March 2017)

Volume 3 (2016): Issue 1 (March 2016)

Volume 2 (2015): Issue 1 (December 2015)

Acta Scientifica Naturalis

 Acta Scientifica Naturalis is the official journal of the Konstantin Preslavsky University of Shumen and has been published with no major interruptions since 1973 under the name of the Annual of the Konstantin Preslavsky University- Chemistry, Biology, Physics, Geography.   The main objective of Acta Scientifica Naturalis is to publish original research findings in the fields of the Natural Sciences and related sciences:    Chemistry - Atmospheric Chemistry, Bioinorganic Chemistry, Bioorganic Chemistry, Catalysis, Combinatorial Chemistry, Computational Chemistry, Coordination Chemistry, Geochemistry, Inorganic Chemistry, Macromolecular Chemistry, Materials Science, Medicinal Chemistry, Ocean Chemistry, Organic Chemistry, Organometallic Chemistry, Physical Chemistry, Polymer Chemistry, Supramolecular Chemistry, Theoretical Chemistry.   Biology and Ecology - Animals Physiology, Anthropology, Applied Ecology, Biochemistry, Bioecology,　Biophysics, Botany, Cell Biology, Embryology, Entomology, General Ecology, Genetics, Helminthology, Human Physiology, Hydrobiology, Immunology, Microbiology, Molecular Biology, Molecular Genetics, Morphology, Mycology, Neurobiology, Parasitology, Plant Physiology, Radiobiology, Virology, Zoology.   Plant Growing and Plant Protection - Biological Plant Protection, Cereals, Entomology, Fruit growing, Herbology, Horticulture, Integrated Plant Protection, Legumes, Phytopathology, Technical crops, Vegetable production, Viticulture.   Physics - Atomic and Molecular Physics, Condensed Matter Physics, Electromagnetism, Gas Discharge and Plasma Physics, High Energy Physics, Hydrodynamics, Interdisciplinary Physics, Mathematical Physics, Medical Physic, Neutron Physics and Nuclear Reactor, Nuclear Physics, Particle Physics, Radiophysics and Electronics, Theoretical Physics, Thermal Physics, Wave Physics.   Astronomy and Astrophysics - Applied Geophysics, Astrophysics and Stellar Astronomy, Atmospheric Physics, Earth Magnetism and Gravimetry, Geophysics, Heliophysics, Meteorology, Near-Earth Space Physics, Oceanic Physics, Seismology, Stellar Mechanics.   Earth Sciences - Cartography, Climate Change, Geodemography, Geography of Tourism, Geomorphology, GIS, Hydrology, Morphostructurs, Morphotectonic, Paleogeography, Quaternary Movements, Risk, Social Geography.　   Tourism - Cognitive Tourism, Ecotourism, Extreme Tourism, Mountain Tourism, Recreational Tourism, River Tourism, Rural Tourism, Sea Tourism, etc.      The abbreviated title of the journal is ASN, which should be used in bibliographies, footnotes and bibliographical references strips.   Article Publication Charges (APC)   To publish in Acta Scientifica Naturalis, authors are required to pay an article processing charge (EUR 120). It includes our maintenance, publication and submission to global indexing and tracking organizations and archiving to allow instant access to the article and associated supplementary documents for each user.   Archiving   Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.   Plagiarism Policy   The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process.   Open Access License   This journal provides immediate open access to its content under the Creative Commons BY 3.0 license. Authors who publish in this journal agree to the terms of the Creative Commons BY 3.0 license. 