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Combined use of biomarkers to assess the impact of untreated wastewater from the Danube River, Serbia
Get PDFIn this study a battery of bioassays, both in vivo (metals and metalloids concentrations, erythrocyte morphometry, comet assay, micronucleus assay, and histopathological analyses) on vimba bream Vimba vimba (L., 1758) and white bream Blicca bjoerkna (L., 1758), and in vitro (treatment of HepG2 cells with native water samples) was applied to assess the harmful potential of untreated wastewater. Faecal indicator bacteria were quantified to assess the microbiological water quality. Vimba bream had significantly higher Fe concentrations in both liver and muscle, while white bream had higher Ca and Cu concentrations in liver. Vimba bream had a significantly higher level of DNA damage in both liver and blood cells, in comparison to white bream. Low levels of micronucleus and nuclear abnormalities were observed in both species. Erythrocytes morphometry did not show significant interspecific differences. Histopathological analyses revealed a similar response of the studied species, with a significantly higher presence of ceroid pigments in the liver of vimba bream. Treatment of HepG2 cells revealed the high genotoxic potential of water downstream of the discharge point. The results of this study clearly demonstrate the importance of effect-based monitoring, in order to enforce more efficient management of natural resources and implementation of wastewater treatment systems
Activity Coefficients of the System {yKCl + (1 − y)KH2PO4}(aq) at T = 298.15 K Determined by Cell Potential Measurements
Get PDF: Zero-current cell potential measurements were used
to determine the solution activity coefficient in a ternary system
{yKCl + (1 − y) KH2PO4}(aq) at temperature T = 298.15 K. The
cell of the type K−ISE|KCl(mKCl), KH2PO4(mKH2PO4
)|Ag|AgCl was
used in the total ionic strength range, Im = 0.0886−1.0046 mol
kg−1
. In order to generate a set of parameters that can be applied in
a wide range of mixed solution ionic strengths, the Pitzer,
Scatchard, and Clegg−Pitzer−Brimblecombe models were used to
fit all available experimental data, including cell potential and
isopiestic measurements from the literature. The experimental and
calculated values of thermodynamic properties for the studied
system are in excellent agreement. Potential interactions and solution structure were discussed by means of the excess free energy of
mixing via potential pairs, triplets, or quads for the investigated solution using the Scatchard model mixing parameter
Tracking and forecasting of students progress using Multiple-Criteria Decision Making and kNN methods
Get PDFThe paper discusses a problem in higher education related to students' progress and performance in exams. During the semester, every student would benefit from information about whether their work on the course is sufficient to achieve the desired result on the final exam. If it was pointed out to them at the right moment that success in the subject is likely to be absent, it could encourage them to increase efforts for the rest of the semester and thus in the end achieve their goal. However, if a bad result is expected for most participants, a change in the teaching method should be considered. Therefore, in this research, two aims have been set: to determine the moment during the semester when it can be said that a certain student will not successfully complete the course and to check that the teaching methods are appropriate. In order to give advice to the student in a timely manner, at certain moments during the semester, it is necessary first to diagnose the level of their knowledge, and then make a prediction of the expected result on the exam. In the solution proposed in this paper, in five time moments (t2,...,t6) the student's knowledge is assessed using the Multiple-Criteria Decision Making (MCDM) method - PROMETHEE II, which considers four criteria (attendance, activity, homework, and test), and the teacher's preferences. Thus, a progress function for a given student is obtained, which shows how they are progressing toward the set goal. Based on the values of the progress function in milestones t2-t6, student achievement is categorized through grades. In this investigation, we have used the k-Nearest Neighbors (kNN) Algorithm for grade classification. Our findings clearly justify that MCDM and kNN models are appropriate for tracking, classifying, and forecasting student grades
Electrodeposited Co-Ru alloys at Ti2AlC suport as the catalysts for hydrogen production by water electrolysis towards sustainable economic development
Get PDFElectrodeposited Co-Ru alloys at Ti2AlC suport as the catalysts for hydrogen production by water electrolysis towards sustainable economic development
Nevenka Elezovic1*, D. Kutyla2, M. Krstajić Pajić3, U. Lačnjevac1, P. Zabinski2
1*University of Belgrade, Institute for Multidisciplinary Research, Kneza Viseslava 1, 11000 Belgrade, Serbia, *invited-presenting author – [email protected]
2 Faculty of Non-Ferrous Metals, AGH University of Science and Technology, Mickiewicza Ave. 30, 30-059 Krakow, Poland;
3 University of Belgrade, Faculty of Technology and Metallurgy, 11000 Belgrade, Serbia;
Abstract
Cobalt-ruthenium alloys were electrochemically deposited at Ti2AlC suport from hloride based acid electrolyte. Thin layers of Co-Ru were obtained by potentiostatic electrodeposition in the potential range of -0.6 V to -1.0 V vs SCE. The chemical composition and physical-chemical characterization have been performed by X-ray Fluorescence spectroscopy (XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM-EDS). It was found that increasing of Co content in the alloy led to gradual shift of the crystalline structure from HCP to FCC Co-Ru solid solution. The electrochemical characterization of the catalysts was done by linear sweep voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in alkaline electrolyte. The optimal conditions for deposition of nanocrystalline Co-Ru alloys with superior activity for hydrogen evolution were discussed in terms of activity and stability, as well as commercial acceptable costs for the catalysts production.
Acknowledgements: This work was supported by the Ministry of Science and Technological Development Republic of Serbia (Contract No. 451-03-68/2023-14/200053 and Contract No. 451-03-68/2023-14/200135). The authors would like to thank Prof. M. Barsoum, Drexel University–Philadelphia USA for Ti2AlC preparation.
Keywords: Electrodeposition; Co– Ru alloys; MAX phases; Hydrogen Renewable Energy; Water splitting;
Biography
Dr Nevenka R. Elezovic completed her PhD in 2005, from University of Belgrade. She is currently Research Professor at the Institute for Multidisciplinary Research, University of Belgrade. Her research interests include: Nanostructured materials and alloys for low temperature fuel cells and water electrolysis application - green energy production. Since 2013 she has been serving as national representative of Serbia and member of the European board in European Academy of Surface Technology:
http://www.east-site.net.
She has published more than 40 papers in high impact peer reviewed journals of eminent Publishers such as Elsevier, Royal Society of Chemistry, Springer, The Electrochemical Society and more than 70 conference papers. She has been serving as a reviewer for: Energy and Environmental Science, Applied Materials and Interfaces, Journal of Materials Chemistry A, Electrochimica Acta, Applied Catalysis B: Environmental, Journal of the Electrochemical Society, International Journal of Hydrogen Energy, as well as adjudicative (senior) reviewer for Energy and Environmental Science. She has given numerous invited lectures at the International conferences, recently at International Summit on Conventional and Sustainable Energies, 2018 Orlando, Florida, USA; Global Experts Meeting in Green Energy, 2019, Rome, Italy; Materials, the Building Block for the Future 3rd AAAFM-UCLA, 2021 Los Angeles USA; Euro-Global Climate Change conference, 2022, Paris, France.
Web page: http://www.imsi.bg.ac.rs/en/researchers/nevenka-r-elezovi
Results of selective removal of the black bullhead (Ameiurus melas) in two different lentic system
Get PDFIn the sake of better understanding of the mechanisms that drive interactions between
invasive species and their ecosystems, results of selective removal of the black bullhead
(Ameiurus melas) in two different lentic systems were compared. Ponjavica Nature Park has
characteristical watercourse of the plains with very slow flow and the coastal remains of
wetlands. Markovačko reservoir was built for the needs of the irrigation system of the
nearby agricultural land. Both systems suffer dominance of the black bullhead,
characterized as a species of "globally high risk". Combining results of the mass removal,
the effects on the native fish populations have been empirically demonstrated and
quantified. Black bullhead selective removal in Ponjavica lasted from August - October
2018, April - September 2019, with 20,145 black bullhead individuals removed. It showed
decreased abundance of bleak (Alburnus alburnus) 2.3 times, while the abundances of
roach (Rutilus rutilus) and European perch (Perca fluviatilis) remained almost unchanged. A
significant increase in abundance was recorded in rudd (Scardinius erythrophthalmus) (5.3
times). The abundances of topmouth gudgeon (Pseudorasbora parva), pumpkinseed
(Lepomis gibbosus), and Prussian carp (Carassius gibelio) increased 25.5, 4.9, and 4.2 times,
respectively. The mass removal of black bullhead on Markovačko Lake lasted from August -
October 2020, April - September 2021, and 15,921 black bullhead specimens were
removed. When the post removal state from Markovačko lake was determined, two species
appeared in the sample for the first time: European perch and chub (Squalius cephalus). The
abundance of bleak increased 3 times, abundance of Prussian carp reduced 8 and black
bullhead 16 times. The abundance of roach decreased 11, rudd 10, pike-perch (Sander
lucioperca) 4 and freshwater bream (Abramis brama) 2 times. The abundances of
pumpkinseed increased 10, Monkey goby (Neogobius fluviatilis) 3 and topmouth gudgeon
2.5 times. The results showed that the fyke nets can be most effectively and selectively
applied to control the abundance of black bullhead, because simplicity and nonharmfulness
to other species. It is not possible to completely remove this species from the
ecosystem, but reduce the negative impact by suppression (removal programs) and
containment of existing state is crucial
Assessment of macro-, trace- and toxic elements in Small Indian mongoose, Herpestes auropunctatus (Hodgson, 1836), from Montenegro: potential use for biomonitoring
No full textThe aim of this study was to determine the concentrations of 28 elements in the liver, kidney, muscle, and heart of a small Indian mongoose from Montenegro. Element concentrations were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Significant differences in elemental concentrations between analyzed tissues were observed for Ag, Al, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, P, S, Se, and Zn. The concentrations of Ag, Fe, Mo, and S were significantly different between all analyzed tissues. Muscle tissue is characterised by higher concentrations of some macroelements (K, Mg, S) and liver tissue by higher concentrations of some trace elements (Fe, Mn, Mo, and Zn). Cardiac tissue could be the target organ for bioaccumulation of Ag and Se. The molar ratio Se:Hg was higher than 1 in all studied tissues. There were few significant differences between element concentrations in mongooses from three analyzed (Airport, Saline, Inland) groups. Significantly higher concentrations of Ag and Se were found in liver tissue of Inland mongooses compared to animals from Airport and Saline. There were few significant differences (Zn in liver and muscle, Fe in muscle) in element concentrations between females and males
CHARACTERISATION OF MUNG BEAN (VIGNA RADIATA L.) SEEDS USING FLUORESCENCE SPECTROSCOPY AND MULTIVARIATE ANALYIS
Get PDFMung bean (Vigna radiata L.) is a leguminous plant cultivated mainly in south-east Asia and used as an ingredient in local cuisine. Its principal nutritional value is contained in its constituents such as starch, proteins, (poly)phenols, and natural antioxidants. Fluorescence spectroscopy is increasingly used as a method of choice for food analysis; due to the presence of different fluorophores originating from aromatic amino acids and secondary metabolites, it is useful for proteins and phenolics detection. In this study, the total protein and phenolic contents of mung bean seed extracts were determined using the Bradford method and Folin–Ciocalteu (FC) reagent, respectively. Antioxidant activity was determined using DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay. Fluorescence spectra were recorded for a series of excitation-emission wavelengths. Further, we used the multivariate analysis on the recorded excitation-emission fluorescence matrix of the studied samples. The results showed the presence of three different fluorescence components, with the position of the emission maximum corresponding to the fluorophore of proteins (component 1 with excitation/emission peak maxima at Ex 290/Em 345 nm) and phenolics (component 2 - Ex 295/Em 395 nm and component 3 - Ex 350/Em 450 nm). This fluorescence-based method could be a useful approach for estimating the nutrient properties of leguminous food
ENHANCED PROPERTIES OF PVDF COMPOSITES BY ACTIVE PHASE SILANIZATION
Get PDF0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3/polyvinylidene fluoride flexible composite films were prepared by the hot-pressing method. Surface modification of active phase particles was performed using two coupling agents, namely, (3- aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane (DDTES) to enable good adhesion of active phase particles with the polymer matrix. The highest amount of electroactive PVDF β- phase was formed in APTES-modified samples while in DDTES samples mainly γ- phase was formed. Dielectric permittivity values and dielectric losses decreased for silanized samples due to reduced tension at the interface between particles and polymer. Strong intermolecular interaction between the PVDF chains and the APTES-modified particles led to enhanced breakdown strength of these samples. After the polarization of films, energy harvesting potential was evaluated for all samples. The highest voltage output of ~ 15 V and power ~ 225 μW were obtained for a single APTES-modified harvester [1-2]
Intrinsic Fluorescence Markers for Food Characteristics, Shelf Life, and Safety Estimation: Advanced Analytical Approach
No full textFood is a complex matrix of proteins, fats, minerals, vitamins, and other components. Various analytical methods are currently used for food testing. However, most of the used methods require sample preprocessing and expensive chemicals. New analytical methods are needed for quick and economic measurement of food quality and safety. Fluorescence spectroscopy is a simple and quick method to measure food quality, without sample preprocessing. This technique has been developed for food samples due to the application of a front-face measuring setup. Fluorescent compounds–fluorophores in the food samples are highly sensitive to their environment. Information about molecular structure and changes in food samples is obtained by the measurement of excitation–emission matrices of the endogenous fluorophores and by applying multivariate chemometric tools. Synchronous fluorescence spectroscopy is an advantageous screening mode used in food analysis. The fluorescent markers in food are amino acids tryptophan and tyrosine; the structural proteins collagen and elastin; the enzymes and co-enzymes NADH and FAD; vitamins; lipids; porphyrins; and mycotoxins in certain food types. The review provides information on the principles of the fluorescence measurements of food samples and the advantages of this method over the others. An analysis of the fluorescence spectroscopy applications in screening the various food types is provided
Comparison of field performance and fruit quality among newly released Italian June-bearing strawberry cultivars
Get PDFThe aim of this study was to compare newly released June-bearing
strawberry cultivars (‘Quicky’, ‘Sandra’, ‘Lofty’, ‘Nadja’ and ‘Aprica’) in terms of
their phenology, vegetative growth, productivity and fruit quality to identify their
potential for wider cultivation. A field study was conducted in a strawberry
plantation established in July 2020 in double rows on beds covered with black
polyethylene foil (Šid, Serbia). The cultivars were evaluated in 2021–2022 for their
flowering and ripening time, productivity, plant growth, biometrical and nutritional
fruit traits (soluble solids content – SSC, total acids – TAs, vitamin C, total
anthocyanins – TACY, total phenolics – TPC and total antioxidant capacity – TAC).
The cultivar ‘Quicky’ started to ripen earliest, while ‘Aprica’ was the latest in both
experimental years. The number of branch crowns per plant was significantly higher
in ‘Sandra’ and ‘Lofty’, whereby ‘Sandra’ had also the highest number of leaves per
rosette (41.5) in comparison with the other tested cultivars. The cultivar ‘Aprica’ was
superior in terms of productivity (1061 g/plant and 4.67 kg/m2
), fruit weight (29.9 g)
and fruit shape index (1.15). Contrary to this, ‘Nadja’ was the least productive
cultivar (608 g/plant and 2.68 kg/m2). The cultivars ‘Lofty’ and ‘Sandra’ showed the
highest SSC values and were also characterized by a considerably high level of TPC
(1.29 mg GAE eq g-1 FW) and TACY (24.4 mg pg-3-g eq 100 g-1 FW), respectively.
Variability among the tested cultivars could serve as an important criterion for the
selection of new high-performing cultivars for a given growing region