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The effects of grains, pelleted and extruded feed on the fatty acid content in carp meat has not been examined yet. In this work, we present evidence that the high carbohydrate content in all three types of feed causes oleic acid to predominate in all meat samples. A higher PUFA content in the meat of fish fed with granulated feed was detected. The extruded feed diet led to 69% greater n-3, and 53% lower n-6 fatty acid contents. Their ratio is thus 2.64-fold higher than in meat of carp fed with pelleted feed. A higher content of n-3 fatty acids in fish fed with extruded feed was the consequence of higher DHA (1.6 times) and EPA (3.3 times) contents. The detected differences could be the consequence of the thermal treatment of extruded feed that makes the proteins, carbohydrates and lipids more accessible to fish than in a pelleted feed. [Projekat Ministarstva nauke Republike Srbije, br. TR 31075 i br. 173040]

In order to examine how extruded and pelleted feed affects the fatty acid composition of carp meat and Chironomidae larvae, two-month-old carp specimens were set in two fishponds (L1 and L2). The fatty acid composition of extruded and pelleted feed is characterized by a significantly higher content of ω-3 fatty acids and higher ω-3 to ω-6 fatty acids ratio (ω-3/ω-6) in extruded (11.34±0.12% and 0.315±0.005, respectively) compared to pelleted feed (7.72±0.08%, 0.180±0.001, respectively). The fatty acid composition of carp meat is characterized by higher ω-3 fatty acid content and ω-3/ω-6 in carp fed with extruded feed (L1, 6.98±0.53% and 0.295±0.022, respectively) compared to carp fed with extruded feed (L2, 5.46±0.07% and 0.232±0.009, respectively). Chironomidae larvae from the fishpond L2 had significantly higher ω-3 fatty acid content (8.22±0.89%), and therefore higher ω-3/ω-6 (0.81±0.09) in comparison to Chironomidae from the L1 fishpond where these parameters were 4.48±0.06% and 0.21±0.01, respectively. [Projekat Ministarstva nauke Republike Srbije, br. TR 31075 i br. 173040]

During the period from April to October in the production season of the year 2000, seven chemical parameters of the aquatic environment were analyzed twice a month for the amount of natural food (zooplankton and bottom fauna) on pond No. 4 at the Dubica Carp Farm in Banatska Dubica (Vojvodina, Serbia). Correlation between natural food and carp growth was analyzed as well. The investigations revealed negative correlation between the amount of natural food per kilogram of ichthyomass and pH (p < 0.001, r = -0.875), electroconductivity (p = 0.0294, r = -0.673), COD (p = 0.0052, r = -0.782), total water hardness (p = 0.0186, r = -0.709), and carbonate water hardness (p = 0.0087, r = -0.758). However, statistically significant positive correlation was found between the biomass of natural food (g/kg of ichthyomass) and concentration of nitrates (p < 0.01, r = 0.841) and phosphates (p = 0.0427, r = 0.640). Concerning com­ponents of natural food (zooplankton and bottom fauna), bottom fauna biomass had a very low production and showed no statistically significant correlation (p = 0.137, r = 0.491) with total natural food biomass whereas zooplankton biomass was very significantly correlated (p

Trout farming poses an increasing threat to quality of the water of clean highland streams. Research of this problem has focused primarily on changes in physico-chemical composition of the water and structure of the river bottom, and less on the effects on living organisms. In the present work, we investigated influence of the farm with the highest trout production in Serbia, the 'Riboteks' Trout Farm on the Trešnjica River, on its macrozoobenthos communities. Our investigations showed that the 'Riboteks' Trout Farm wastewaters caused a clear and statistically significant change of moderate intensity in all measured parameters describing the composition and structure of macrozoobenthos communities. These changes were most pronounced in the part of the watercourse closest to the influx of waste water (locality III) but remained statistically significant even 500 m downstream (locality IV) and were lost only about 3.5 km away from the influx of the farm's wastewater (locality V). The most pronounced were changes in the participation in total abundance of the Baetidae, Chironomidae, and Plecoptera. Additionally, results of the present work confirmed that the mass of fish on the trout farm is a parameter that adequately defines the strength of its action, above all the intensity of its influence on structure of the macrozoobenthos community.

The quality of water at the Dubica Fish Farm was evaluated by the saprobiological method using the Pantle-Buck saprobity index, during one carp production cycle in the year 2000. By qualitative and quantitative analysis of the zooplankton community, bioindicator species were selected for evaluation of water quality. During the whole period of research, the saprobity index indicated class II water quality, which is suitable for rearing carp in a semi-intensive system as far as natural food is concerned. There was a general trend of decrease in the saprobity index from the beginning to end of the season, its values ranging from 2.05 do 1.77, and a gradual improvement of water quality towards the end of the season. This is partly a result of natural processes (terminated degradation of introduced organic matter as well as settlement of suspended matter introduced with the supply water) and partly a consequence of the application of ichthyological, agrotechnical, and hydrotechnical measures. .

We investigated macroozobenthos communities in the Temska and Visočica Rivers at 10 localities during the summer and autumn of 2001. In 46 samplings of quantitative and 10 of qualitative analysis, 101 taxa from 17 groups of macrozoobenthos are identified. The most diverse group is the order Trichophtera (28 species from nine families). Less diverse with (only one species) are Nematomorpha, Hirudinea, Odonata, and Megaloptera. At all of the chosen localities, the most common species are Elmis aenea (70.00%), Ancylus fluviatilis, and Baetis sp. (60.00%). All those localities on the Visočica and Temska Rivers are very similar. The index of similarity varies from 12.5% (between Vi0 and Te0) to 70.7% (between Te1 and Te2). In the Temska River the Shannon-Weaver diversity index varies from 1.80 (at Te3) to 2.45 (at Te0). In the Visočica River, the highest diversity of macrozoobenthos is at the Vi3 locality (2.59), the lowest at Vi0 (1.40). Less diverse macrozoobenthos communities are found at the Vi0 and Te3 localities. At the same time, these localities have the highest values of Simpson's index (0.35 and 0.34, respectively).

In this work, the effect of physical parameters on the yield of fullerene synthesized in a hollow cathode plasma reactor is investigated. The experimental investigations done previously have shown that the fullerene yield depended on technical parameters - the current intensity, inert gas pressure, type of gas and interelectrode gap. The aim of this work was to show that the fullerene yield depends on physical parameters - carbon concentration, carbon flow rate from the interelectrode gap, axial temperature and temperature gradient between the are channel and the chamber walls as well. It was found that fullerene synthesis occurs in an inert heat bath with dimensions determined by the temperature gradient. The lower temperature limit is around 2000 K and the value of the upper limit is the value of the axis temperature which depends on the discharge conditions. The synthesis of fullerenes is more effective if the carbon concentration in the heat bath is large and the carbon flow rate from that zone to colder parts of chamber is small.

During the period 1988 - 1996 the Ephemeroptera diversity in West Serbia was studied. These investigations included 124 springs, considerable number of spring regions, as well as rivers: the Sušica, Djetinja, Skrapež Pocibrava, Banja, Gradac, Jablanica, Obnica and Kolubara. Total of 45 taxa belonging to 8 families were identified. At the majority of sampling locations: Baetis rhodani, Baetis sp., Ecdyonurus sp., Ephemera danica Ephemerella ignita, Caenis moesta, Habroleptoides modesta and Ilhitrogena semicolorata were present. The smallest Ephemeroptera diversity in the studied waters was recorded in springs and the greatest one in middle parts of the mountain running waters.

Hydrobiological investigations of the macrozoobenthos were carried out at eight localities in the Toplica river (a right-hand tributary of the Kolubara river) from April 2000 to January 2001. The bottom fauna was composed of 19 groups of macroinvertebrates with 85 determined taxa (61 identified to the species level, 24 to the generic level). The most varying groups were the insect orders Trichoptera (20 taxa), Ephemeroptera (15), and Diptera (13), while Isopoda, Decapoda, and insects belonging to orders Collembola, Heteroptera, Megaloptera, and Planipennia were the most uniform. The species Gammarus pulex fossarum Koch and Dugesia gonocephala Duges were the most abundant forms at the river source, and representatives of Ephemeroptera and Gammaridae were the most numerous in its upper course (at the second, third, and fourth locality). The Mollusca and Chironomidae larvae were the most abundant forms at the fifth locality (in the middle course), but no constant dominance of any animal group was recorded at the sixth one, where the dominance alternated among Chironomidae larvae (April, July 2000), Oligochaeta (October 2000) and Mollusca (January 2001). The lower course of the river (the seventh and eighth locality) was characterized by the dominance of the species of the phylum Mollusca (Amphimelania holandri Ferussac, Fagotia esperi Ferussac and Theodoxus transversalis Pfeiffer).

Among the diverse order of Hymenoptera, aquatic species are of special interest. During macrozoobenthos sampling in the rivers of Serbia in 2003 and during the period 2011−2012, pupae of Silo pallipes Fabricius, 1781 were recorded which were parasitized by an ichneumonid wasp Agriotypus armatus Curtis, 1832, this being the first record of it for the Balkan Peninsula. A total of 217 A. armatus specimens were collected at 29 localities situated along 16 watercourses of Serbia. All four parasitoid stages (egg, larva, pupa and resting adult) were recorded. The identity of the parasitoid was confirmed using standard molecular methods. This study also focuses on the ecology of the parasitoid and its host. The widespread distribution of A. armatus in Europe suggests the presence of this species in other Balkan countries, but this has not yet been confirmed due to a lack of surveys and/or the constantly increasing pollution of freshwaters.

The objective of this research is to assess the breeding value of male individuals and calculate heritability values for body weight and body length at 12 months of age in the rainbow trout population in the Republic of Serbia. The study utilized data on the physical development of trout obtained through the Center for Fisheries and Applied Hydrobiology “Mali Dunav”, Experimental Estate “Radmilovac” of the Faculty of Agriculture, University of Belgrade (CEFAH) Breeding Program for rainbow trout in the Republic of Serbia. The fish were raised in individual tanks under tightly controlled conditions at the CEFAH, until they reached 5 months of age. At this point, the fish were marked (with PIT tags Norway) and transferred to commercial fish farms, where monitoring of their production results continued. To estimate the breeding value for body weight and body length of rainbow trout at 12 months of age, we analyzed data collected between 2016 and 2020, which included a total of 2014 individuals. The breeding values were estimated using a sire model. The mixed model incorporated fixed effects (spawning year and sex) and a random effect for the individual sire. The heritability estimate at 12 months of age was 0.44 for body weight, and 0.45 for body length. The breeding values were estimated for 107 sires, with body weight values ranging from −37.83 to +37.83 g and body length values ranging from −14.00 to +14.00 mm. The substantial variation observed within the studied rainbow trout population suggests the potential for further genetic improvement. The high heritability values confirm that further selection can be based on the phenotype. The inclusion of high-quality and validated males in breeding programs will contribute to the enhancement of production characteristics within the existing rainbow trout population in Serbia.

Ruthenium complexes have gained significant attention due to the ruthenium similarity to iron, lower toxicity, and higher anticancer effectiveness than other compounds. In this contribution, five new isonicotinate-polyethylene glycol ester ligands were synthesised and characterised by NMR and IR spectroscopies. The corresponding Ru(II) complexes were also obtained, and their structure was investigated by traditional methods. The optimisation of structures was performed at B3LYP/6-31+G(d,p) level of theory for H, C, N and O atoms and B3LYP/LanL2DZ for Ru. The intramolecular stabilisation interactions were assessed through the natural bond orbital approach. The NMR chemical shifts were predicted by the gauge independent atomic orbital method and compared to the experimental values. High correlation coefficients and low mean absolute errors between these data sets proved that the predicted structures described well the experimental ones. The theoretical and experimental IR spectra were also compared, and differences in the most notable bands were described. One of the ligands (L5) and complexes (5) showed fluorescent properties due to methylisatoic moiety. The electronic spectra of this compound were modelled by the time dependent-density functional theory method. The difference of 11 nm between the experimental and the theoretical wavelength was explained by the interactions between the solvent and the solute. Further biological and theoretical studies are advised for this series of compounds.

Effective management of the maintenance of medical equipment (ME), especially high-tech one, is one of the main issues for the quality of health care, for the provision of cost-effective health services and for saving , even in developed countries, insufficient resources. Medical equipment maintenance (EM) includes all activities related to ensuring an adequate level of service and limiting the downtime of medical equipment in a healthcare organization. Traditionally, EM is categorized as preventive maintenance (PM) and corrective maintenance (CM). The principle of PM is prediction. PM can be planned and predictive, ie. Just-In-Time (JIT) maintenance. Predictive maintenance can only be applied to new high-tech medical devices that have built-in self-testing. Planned preventive maintenance is carried out in accordance with the maintenance plan for a certain period of time. As a rule, when creating the plan, we follow the manufacturer's recommendations for preventive maintenance of ME given in the technical documentation of the ME, especially in the instructions for the maintenance of the ME. Predictive or JIT maintenance makes it possible to detect and solve the problem before problems and contingencies actually occur, and this is done on the basis of intelligent monitoring and analysis of the state of ME at the right moment, which ensures the optimal time for intervention, so that maintenance performed only when necessary. The information system for the management of the maintenance of ME in healthcare institutions would interconnect healthcare institutions and enable the fast and safe exchange of data and information related to the maintenance of ME and enable the optimal maintenance of ME in healthcare institutions, increasing the availability of this equipment, especially high-tech equipment, with significant reduction of the total cost of maintaining ME (of the order of 30%). One of the main reasons for the unsustainability of the existing approach to the maintenance of ME in the healthcare institutions of Serbia is that each healthcare institution independently takes care of the maintenance of its own ME. This approach is expensive and significantly affects high maintenance costs. This approach needs to change.

The paper examines the influence of the key determinants of success in hotel industry in the Republic of Serbia. The research was conducted for the period from 2015 to 2020 on a sample of 23 hotels. The chosen length of the observation period covers a sufficient time interval to cover all heterogeneities in the structure of the observation units, as well as their changes over time, using the dynamic panel analysis model. The adequate sample size was determined by considering the size of the population, the desired level of confidence, and the value of the allowable sampling error. The results of the research have shown that determinants such as business success from the previous period, efficiency of use of total business assets, belonging to a hotel chain, size and increasing hotel concentration index have a positive impact on success in hotel industry. On the other hand, determinants such as hotel indebtedness, operating leverage and hotel age have a negative impact on business success. Determinants such as the quality of environmental protection management and socially responsible hotel business do not have a significant impact on success in hotel industry in the Republic of Serbia.

In order for the Health Technology Management Policy at the state level to be successfully implemented, first of all, adequate personnel are necessary, and among these, biomedical engineers play an important role. Biomedical engineers (clinical engineers) work in a wide range of settings and disciplines in the health sector and play a key role in: innovation, design and development of new technologies in health care; testing, implementation and development of new diagnostic tools and medical equipment; defining safety standards for medical equipment; maintenance of (complex) medical equipment. The Ministry of Health of the Republic of Serbia labeled the biomedical engineering workforce as a "critical workforce". This critical workforce is defined as "a workforce that contributes to critical and essential elements of health technology management, especially in the domain of maintenance and replacement of (complex) medical equipment, now and in the future".

Brown trout is a common type of fish grown for consumption in open and flowing fish ponds on the rivers of Bosnia and Herzegovina. We conducted this study during three seasons (spring, summer and autumn) to obtain a complete picture of the morphological and histological characteristics of selected trout tissues. The physicochemical characteristics of the water from the Pliva River near Pljeva and the fish pond where intensive breeding of trout is carried out were analyzed. These analyses have shown that there are no major deviations in water quality and that the water in the pond is of excellent quality. A total of 90 trout were harvested during all three seasons and their morphometric characteristics were determined by analyzing ten parameters. After the dissection of all individuals, histological and stereological analysis was performed to compare the tissues of the liver, stomach, gills and muscles. These analyses showed significant differences in the histoarchitecture of selected trout tissues from the pond compared to the river. Liver tissue had altered hepatocyte shape and presence of adipocytes; stomach tissue had stronger mucosa and weaker muscle layer; gill tissue had lower respiratory lamellae; while muscle tissue had a significant presence of adipose tissue in brown trout living in the fish pond compared to those in the river. All these changes are due to the quality of commercial feed and the inability to move freely.