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Erythron profile and liver enzymes as potential biomarkers of water and sediment pollution in vimba bream (Vimba vimba) from the Danube River: effects of varying pollution and sampling season
No full textFish erythrocytes are ellipsoidal nucleated cells that are released from the erythropoietic sites, and become increasingly elliptical and less spherical in the course of their life. The relative abundance of the different developmental stages (immature, intermediary and mature) of erythrocytes represents an erythron profile that can be used as a sensitive indicator of contamination. Transaminase (aspartate aminotransferase, AST; alanine aminotransferase, ALT) activities, which are sensitive biochemical markers of liver function and the general physiological state of fish, could also be a good indicator of pollution. In this study, a benthopelagic fish vimba bream (Vimba vimba) was sampled at three locations characterised by different levels of pollution (Zemun - relatively clean, Višnjica - moderately polluted, and Banovci - heavily polluted) to assess the potential of the mentioned parameters as biomarkers of water and sediment pollution. In 2016-2017, a total of 156 vimba bream specimens were sampled and analysed in Zemun (92 specimens were collected in spring, 24 in summer, 30 in autumn, and 10 in winter) to determine the seasonal changes of investigated parameters. In Višnjica, 16 specimens were collected in autumn 2018 and in Banovci 5 specimens were collected in summer 2017. The total length and body mass of each fish were measured and used to calculate the Fulton’s condition factor. Blood smears were prepared on microscopic slides and stained with the Bio-Diff kit. Random fields were photographed and approximately 50 erythrocytes, per individual, were analysed. Three morphometric parameters (area, perimeter, and length) of the erythrocytes were measured using the ImageJ programme. Serum was separated from blood and AST and ALT activities were measured using Randox assay. At each site, the overall condition of the analysed fish was good (K > 1). During the year the highest percentage of immature erythrocytes was observed in summer, when the temperature was highest and oxygen concentration and saturation were lowest. A higher percentage of mature erythocytes could indicate lower feeding effort or starvation, which was observed, and expected, in the winter season. The morphometric parameters of erythrocytes were significantly lower in autumn compared to the other seasons. Only in intermediary erythrocytes all three parameters correlated with temperature, oxygen concentration and oxygen saturation. Compared to Višnjica (autumn) and Banovci (summer), fish from Zemun had a higher proportion of immature erythrocytes. Fish from Višnjica had significantly higher morphometric parameters of erythrocytes for all developmental stages (except area in mature stage), while from Banovci had significantly lower parameters, compared to the individuals from Zemun. Transaminase activities showed no significant seasonal differences and there were no differences in their activities between fish from Zemun and Višnjica. Enzymes did not show significant correlation with temperature, oxygen concentration and oxygen saturation. The percentage of immature erythocytes could be an indication of environmental stress, and while the highest percentage in summer could be related to hypoxia during the summer months, the highest percentage found in fish from the Zemun sampling site, less polluted than Višnjica and Banovci, should be interpreted with caution since comparison involved different sampling seasons and years and various number of sampled fish
Pseudomonas avellanae - Nov patogen leske u Srbiji
No full textFitopatogena bakterija Pseudomonas avellanae prouzrokovač bakterioznog raka i izumiranja leske (Corylus avellana), inficira sprovodno tkivo grana i stabla dovodeći do sušenja grana i lisća. Velike štete na zasadima leske su beležene u oblastima severne Grcke i u centralnoj ltaliji. Obzirom na ekonomski značaj, štete koje prouzrokuje i fitosanitarni rizik, ovaj patogen je prema Evropskoj Regulativi 2019/2072 svrstan na listu regulisanih nekarantinskih štetnih organizama (RNQP). Obzirom da je leska jedini domaćin bakterije P. avellanae i da nije izolovan iz plodova sa zaraženih stabala, jedini način procenjen kao rizik od introdukcije i prenosa patogena predstavlja zaraženi sadni materijal. P. avellanae je prvi put opisan kao patovar P. syringae pv. avellanae (1993. godine), dok su nakon toga molekularne analize dovele do preklasifikacije u posebnu vrstu P. avellanae ( 1996. godine ). Dalja istraživanja, u kojima su vršena upoređivanja sojeva poreklom iz Grcke i ltalije ukazala su na postojanje dva razlicita fitopatogena: P. s. pv. avellanae, koji je izolovan samo u ltaliji, i P. avellanae, koji je izolovan i u Grckoj i u ltaliji. Najintenzivniji simptomi infekcije leske sa P. avellanae javljaju se tokom letnjih meseci, kada dolazi do naglog uvenuća listova i sušenja grana, a kada se proširi na stabla često rezultira izumiranjem cele biljke. Osuseni listovi mogu ostati pričvršćeni za grane dug period, nakon što bi obično otpali u jesen. U slučaju jake infekcije stabla u jesen, ono može potpuno odumreti sledećeg leta. lako bez simptoma, izdanci iz oštećenih stabala imaju veliku verovatnoću da prenose bakteriju i ne bi trebalo da se koriste za razmnožavanje. Takođe, važno je napomenuti da čak i kada su obolela stabla uklonjena sa lokaliteta, svako novo zasađeno stablo leske verovatno ce ponovo biti zaraženo sa P. avellanae. Na podrucju Bačke (Vojvodina) u Srbiji je tokom leta 2024. godine, u zasadu leske (sorta Tonda di Giffoni) u fenofazi zrenja plodova i semena (faze 81-89 BBCH skale) beležen simptom brze uvelosti lišća i mrke diskoloracije sprovodnog tkiva stabla i grana. Primenom konvencionalnih i molekularnih metoda identifikacije utvrdeno je prisustvo bakterije P. avellanae. Ovaj nalaz predstavlja rastuću pretnju P. avellanae za proizvodnju leske na području Evrope, te njegovo širenje na različite regione i potencijalni uticaj na zdravstveno stanje zasada naglašava potrebu za pojačanim nadzorom i strategijom upravljanja.ISBN broj nije dostupan
Influence of Drying Treatment on Antioxidant Activitiy in Four Differently Pigmented Maize (Zea mays L.) Seed Cultivars
No full textConsidered as one of the major food sources worldwide, maize contains a significant quantity
of bioactive compounds that contribute to certain health-promoting benefits. Seed quality is
influenced by drying conditions. In this study, the effects of drying treatment and temperature
on the antioxidant activity of four differently pigmented maize seed cultivars were evaluated.
The seeds were dried for 1 hour at 45 °C and 90 °C, while the control seeds were at room
temperature (25 °C). DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay was used to determine the
antioxidant activitiy of the analyzed pigmented seeds before and after drying. Obtained results
exhibit a statistically significant increase (p<0.005) in the antioxidant activitiy in the light and
dark red-coloured maize seeds after the drying treatment compared to the control. At the same
time, there was no significant increase (p>0.005) in the white and yellow seeds in the same
conditions. The percentage of antioxidant activity also increases with rising temperature, being
higher in seeds that were exposed to drying at 90°C than at 45°C. Results of the fluorescent
spectroscopy analysis of the four maize cultivars indicate the differences in their emission
spectral parameters. The drying conditions and the increase in temperature to which the seeds
were exposed resulted in an increase of the fluorescence spectral maximum intensity. Both of
the used methods are proven as reliable indicators not just for monitoring changes resulted from
the drying of the seeds but also for the estimation of seed quality
Electrodeposited Co–Sn alloys on Ni mesh substrates for large-scale water splitting
No full textThe continuously increasing demand for electricity, depletion of carbon-based resources, and rising ecological concerns have reinforced the goal of minimizing greenhouse gas emissions by the middle of this century. High-purity hydrogen, produced via water electrolysis powered by renewables, can be stored and utilized in fuel cells to generate zero-emission electricity. Moreover, it has potential applications in industrial sectors beyond energy production and transportation. Due to its maturity, scalability, and the abundance of materials used in electrode manufacturing, alkaline water electrolysis (AWE) is a favored pathway for electrocatalytic hydrogen production. Achieving low cell voltage at industrially relevant current densities requires addressing key factors affecting cell efficiency. However, the primary challenge in commercializing AWE systems remains the need for efficient, durable, and cost-effective catalysts for the hydrogen evolution reaction (HER) at the cathode, particularly when avoiding platinum-group metals. Recently, our research has focused on the electrodeposition of Ni–Sn coatings onto porous Ni substrates as highly efficient HER cathodes in alkaline zero-gap flow electrolyzers [1]. In this work, we extend the electrodeposition technique to Co–Sn binary alloys on Ni mesh substrates, which are commonly used in commercial-scale AWE cells. A series of Co–Sn/Ni mesh samples are prepared using galvanostatic electrodeposition from a glycine-pyrophosphate bath. The composition of the deposition bath and the deposition current density are varied to determine the effects of microstructure and chemical composition of Co–Sn coatings on their HER activity. Electrochemical characterization of Co–Sn/Ni mesh electrodes in 1 M KOH using a 3-electrode system confirms the high quality of the coatings, as no detachment or sudden performance deterioration is observed even at higher HER currents. Additionally, a reduction in HER overpotential of approximately 300 mV and 190 mV at a current density of –200 mA cm–2 is noted, compared to bare Ni mesh and Co-coated Ni mesh, respectively, as shown in Figure 1. Finally, electrochemical measurements are conducted in a zero-gap flow electrolyzer to evaluate the industrial potential of Co–Sn coatings
Analysis of the economic profitability of different bell pepper production methods-Abstract
No full textNumerous factors can affect the outcomes of pepper production; therefore, it is crucial to analyze
the most significant ones and understand how their variations impact production results. This paper analyzes the financial viability of pepper production in protected areas (greenhouses) and in open-fields. Through differential calculation and an analysis of efficiency and profitability coefficients, key differences in costs and revenues were identified. The results show that, although production in a protected area requires a larger investment, it achieves a more favorable financial outcome. For every EUR of total costs, a higher income of 0.05 EUR is generated, while the total financial result on an area of 1,000 m² is more favorable by 4,555.00 EUR. A sensitivity analysis confirmed that both production methods are resilient to changes in market conditions, specifically an increase in production costs or a decrease in revenues
SUSTAINABLE GROWING MEDIA: HYDROCHAR FROM GRASSLAND BIOMASS AS A PEAT ALTERNATIVE
No full textBog peat is a limited resource, but still forms the main component for the production of growth media. Due to the negative impact of peat use on the carbon footprint of ecosystems and the landscape, demand for peat substitutes is increasing. The objective of the substrate producers is to use regional, ecologically beneficial substrates that can be achieved through hydrothermal conversion by providing the process of converting biomass into peat-like properties. This method was investigated with materials originating from landscape conservation as starting material with the aim of using the generated peat substitute in culture experiments. The hydrothermal carbonization of the biomass from extensive grassland was first carried out in preliminary experiments on a laboratory scale by varying the temperature and holding time. Hydrothermally carbonized plant residues (hydrochar) were obtained on the basis of three different temperatures (150 °C, 170 °C, 190 °C) and their chemical properties were analyzed. In the study, three different mixtures of a commercial growing medium with addition of 10, 20 and 30 % v/v of hydrochar were examined. The substrate chemical properties of the hydrochar mixtures differed only slightly. The hydrochar mixtures, a pure peat substrate and a peat substrate mixed with wood fibres, were used for substrate hydraulic, chemical and phytotoxic experiments. In addition, extensive cultivation and storage experiments of the described admixtures of the various varieties produced with Chinese cabbage, impatiens and daisies were carried out. Comparable plant growth could be observed for some of the tested qualities, but fungal and odour problems leave room for improvement, especially in terms of post-processing. The relationship between the growth of plants and soil chemical properties have been studied and presented. It was found that the chemical analyzes showed no dominant influence on the growth behaviour. Presumably, the hydrothermally carbonized material fixed the added nitroge
DETERMINANTS OF RYEGRASS YIELD IN COMMERCIAL GROWING MEDIA: NUTRIENTS AND HYDRAULIC TRAITS
No full textGrowing media are made for horticultural use as a mixture of various organic and mineral components. In this study, a total of 34 commercially available growing media were tested for the performance of biomass growth in ryegrass. The aim of the study was to determine which properties of growing media have a greater influence on the performance of grass plant growth. Specifically, the effects of chemical and hydraulic characteristics on ryegrass growth were examined. These results are intended to help in subsequent investigations to find alternative mixing components for the substitution of peat. The variables for the hydraulic assessment were the water capacity in the slightly plant-related area, the air capacity and the capillary water increase. The hydraulic parameters were measured with the HYPROP system (HYdraulicPROPerty Analyzer). The chemical properties (carbon, nitrogen, phosphorous, potassium, magnesium,) were determined by analyzing the total and plant-available nutrients. Additionally, substance loss was determined during the vegetation period. Effects of the chemical and hydraulic properties on ryegrass biomass growth were tested via multiple regression analysis. Ryegrass biomass growth varied widely over the different growing media. The multiple regression showed that substrate loss, plant-available nitrogen (Nav) and phosphorus (Pcal) were significantly associated with increases of yield. Overall, the model explains 44.6% of the variance of Yield. Nav explains 21%, loss 13% and Pcal almost 10% of the variance. Moreover, substance loss was significantly correlated with biomass growth. We also found a higher biomass yield on peat-rich substrates compared to peat-free substrates. These results show in conclusion that commercially available potting soils vary strongly in their content and properties, and confirm the importance of peat for horticulture. Further studies are needed t
Electrodeposited Ni-MoOx coatings as high efficiency catalysts for green hydrogen production in alkaline solution
No full textNi-MoOx catalysts were electrodeposited on Ni mesh 40 under severe hydrodynamic conditions
from the electrolyte containing 2.0 M NH4Cl + 0.2 M NiCl2 and MoOx powder of different
concentations. XRD analysis of as-prepared MoOx powder, obtained by modified rheological
procedure [1], confirmed that sample contains following compounds: MoO2.8, H2MoO4, MoO3,
MoO2 and (NH4)2Mo2O7. XPS analysis confirmed the following coating composition: Mo6+ and
Ni2+ species being placed on top of the surface, while Mo4+, Mo5+ and Ni0 were detected deeper in the coating (fig. 1).
SEM-EDS surface and cross-section analysis of samples showed that coatings with higher amount
of Mo had higher roughness. The amorphous structure of the Ni-MoOx coatings was confirmed by
SAED analysis. The HER was investigated in 30 wt. % KOH at 70 oC. The lowest overpotential at j
= -500 mA cm-2 was only -88 mV for the best activity Ni-MoOx sample. A new approach to
electrochemical impedance spectroscopy analysis [2], from Nyquist plots enabled determination of
the exchange current densities for the charge transfer reaction, intermediate adsorption reaction and total HER. It was clearly indicated that any of the partial reactions could be rate determining ones.
Advantages and disadvantages of these novel catalyts in comparison to state of the art were
discussed, as well
Effects of Beech Wood Surface Treatment with Polyethylenimine Solution Prior to Finishing with Water-Based Coating
No full textThe surfaces of beech wood samples were treated with polyethylenimine (PEI) solutions at three different concentrations—0.5%, 1% and 2%—and two molecular weights—low molecular weight (LMW) and high molecular weight (HMW). The effects of PEI surface treatment of wood were characterized by FT-IR spectroscopy, the penetration depth of PEI (EPI fluorescence spectroscopy), the bonding position of PEI (by SEM), the wetting and surface energy, and the water uptake. After PEI treatment, the samples were coated with a water-based transparent acrylic coating (WTAC). The dry film thickness, the penetration depth of the coating, the adhesion strength and the surface roughness of the coated wood surface were evaluated. EPI fluorescence and SEM micrographs showed that PEI HMW chains were deposited on the surface, in contrast to PEI LMW, which penetrates deeper into layers of the wood cells. Treatment with a 1% PEI HMW solution resulted in a 72% reduction in water uptake of the wood (compared to untreated samples after 5 min of applying water droplets to the surface) and a 23.2% reduction in surface energy (compared to untreated samples) while maintaining the adhesion strength of the applied WTAC. The lower water uptake of the treated wood samples reduced the roughness of the coated surface, which is particularly important when the wood surface is finished with water-based coatings
Trends in Commercial and Recreational Fisheries in Serbia (2008–2023): Implications for Ecosystem-Based Management
No full textFisheries in Serbia have a centuries-long tradition and importance for the society. It is primarily organized through designated fishing areas, managed by public or private entities, fishing associations, or unions. These areas are allocated through public competitions and governed by specific legal obligations. Depending on the area, fishing can be either commercial, recreational, or both. Most fisheries are concentrated along major rivers, particularly the Danube, Sava, and Tisza.
This study evaluates and compares trends in commercial and recreational fishery in Serbia between 2008 and 2023 by analyzing fishing pressure and catch statistics over a 16-year period. Although available statistical data have limitations, trends are evident. Only landing data are officially recorded, though actual catch may differ. The total annual landings ranged from 1,931 to 5,384 tons. Commercial fishing dominated between 2008 and 2011, after which recreational fishing became more prominent. The number of commercial fishermen declined by half, reaching 429 in 2023, while recreational fishers steadily increased, peaking at 109,606 in 2022. The average annual freshwater catch during this period was 3,258 tons, which is a third higher than the average recorded in the previous decade (1995–2004), when around 1,200 commercial fishermen were active.
Recreational fishing has shown significant growth, driven by increasing participation. However, due to the large and dispersed nature of this group, effective monitoring and control remain challenging. Despite this, the cumulative impact of recreational fishing on aquatic resources is substantial and should not be underestimated. The observed trends in both fishing sectors reflect changes in legislation, enforcement, and management practices.
The findings underline the urgent need to shift towards an ecosystem-based fisheries management approach that recognizes the growing influence of recreational fishing. Such an approach would contribute to the sustainable use and conservation of freshwater biodiversity, aligning with regional and EU strategies for protecting aquatic ecosystems in the Danube River Basin