SCIDAR - Дигитална архива Универзитета у Крагујевцу
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Rearing systems and production in organic poultry farming
No full textPoultry farming on free-range can be organized in various ways,
depending on the type and characteristics of facilities and outdoor areas.
Generally, these rearing systems can be categorized into a fixed facility freerange
system and a mobile facility free-range system (structures on wheels). In
organic poultry production, two organic production systems are prevalent:
organic egg production and organic meat production.Publishe
Predicting the yield stress and tensile strength of two stainless steel using artificial intelligence
No full textPublishe
Comparative analysis of production and slaughter parameters of fast-growing broiler hybrids
No full textThis study aimed to explore how hybrid varieties impact broiler
chickens' production and slaughter performance. We applied standard rearing
techniques over a 42-day period. The trial involved a total of 420 broiler chickens
of the following hybrids: Cobb 500 and Ross 308. Weekly performance tests were
conducted, assessing average daily gain, feed consumption, feed conversion rate,
mortality, and European Poultry Efficiency Factor. After controlling for final
body weights on the 42nd day, a random sample of 12 broilers per genotype, with
an equal gender distribution, was selected for slaughter parameter analysis.
Following slaughter traits were determined: pre-slaughter weight of chickens,
slaughter yield, share of abdominal fat, chicken thigh circumference, and chest
angle. The results revealed no significant difference in food consumption between
the examined hybrids. Chickens of the Cobb 500 genotype exhibited significantly
higher (p<0.01) gain and a more favorable feed conversion rate. Due to its better
vitality, feed conversion rate, and gain, Cobb 500 chickens demonstrated
significantly higher (p<0.01) European Poultry Efficiency Factor values. In
contrast, Ross 308 chickens displayed statistically significantly lower (p<0.05)
slaughter yield and chest angle values. At the same time, the proportion of
abdominal fat and chicken thigh circumference showed no significant difference
between the tested hybrids.Publishe
ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF ZIZYPHUS JUJUBA L. LEAF EXTRACTS
Full text linkThe aim of the present study was to investigate the biological activities of the extracts obtained from leaf of Ziziphus jujuba. To reach this purpose, total phenolic content (TPC), total flavonoid content (TFC), DPPH and ABTS radical scavenging activity, as well as antibacterial activity extracts were evaluated. The content of total phenols in leaf ranged from 22.71 to 28.69 mg GAE/g, the total content of flavonoids ranged from 5.15 mg RE/g to 8.25 mg RE/g depending on the applied extraction method. All extracts showed very high antioxidant activity. The ethanol extracts of Ziziphus jujuba leaf were screened for antibacterial activities against Salmonella typhimurium, Salmonella enteritidis, Listeria ivanovii, Listeria monocytogenes, Staphylococcus aureus and Pseudomonas aerogenes using microdilution method. Furthermore, the highest antibacterial activity was observed against Salmonella typhimurium and Salmonella enteritidis. The present results suggested the promising antioxidant and antibacterial properties of Ziziphus jujuba leaf extracts, which can be used in the fabrication of functional bioactive ingredients for different purposes.Publishe
Synthesis, structural properties and DNA protective activity of ferrocenyl N‐acyl pyrazolines
No full textTwo series of new ferrocenyl pyrazolines have been synthesized by the reaction of ferrocenyl chalcones and their analogues with hydrazine hydrate in the presence of corresponding carboxylic acid. Single-crystal X-ray crystallographic data were used for detailed analysis of the interesting versatility of four compounds in the formation of intermolecular interactions. The analysis revealed an excellent structural flexibility of the present ferrocenyl pyrazoline molecules for the non-covalent interactions, with a particular contribution of the ferrocene units. In addition, for comparison with crystallographic findings, we investigated the protective effect of all compounds on DNA against hydroxyl and peroxyl radicals induced by Fe2+, H2O2, and 2,20 -azobis(2-amidinopropane) dihydrochloride (AAPH). The results indicated that all compounds showed rather similar DNA protective activity, which was comparable with quercetin as a well-known protective compound. This similarity in antigenotoxic action could be explained by the established excellent structural flexibility of ferrocenyl pyrazolines for the formation of different intermolecular interactions as important structural property for molecular recognition.Publishe
Energy performance of relatively small sports halls used as public warming shelters
Full text linkTo provide a warm place for the most vulnerable citizens during the 2022/2023 energy crisis, some municipalities have set up public halls as warming shelters. Thus, the present study analyzes the energy performance of a gymnasium in Southeastern Europe that is repurposed to be used as a public warming hall. The study conducted 15 EnergyPlus simulations, covering 5 states of gymnasium occupancy and three heating, ventilation and air conditioning scenarios. Two scenarios were designed to reduce the possibility of viral disease transmission, in the case public health emergency occurs. The study indicates that gymnasiums with natural ventilation consume more energy than they would with more advanced HVAC systems. This way, when occupancy increases, building energy consumption decreases (from 171 kWh/m2 to 102 kWh/m2). Contrary to that, in more advanced heating, ventilation, and air conditioning scenarios, energy consumption slowly increases with occupancy. Due to the utilization of heat recovery and air recirculation systems, these scenarios require approximately 60% to 80% less energy compared to the base scenario. The complex simulations performed in this study provided relatively simple formulas that can be extrapolated to determine hall energy performance for any hall occupancy. These formulas can be used by nonexperts and applied to similar buildings in other locations.Accepted for publishin
ELEVATIONAL EARTH-SHELTERED BUILDINGS WITH SELECTIVE COATED SOUTHERN FACADE WALLS
No full textУ овом раду представљен је нови пасивни соларни дизајн у зградарству, који се може користити у циљу редуковања потрошње (финалне и примарне) енергије за грејање и емисије СО2. Наиме, позитивни ефекти од градње елевационих земуница додатно се могу појачати премазивањем јужних фасадних зидова (грађевински елементи који нису у непосредном контакту са земљиштем) одговарајућим селективним премазима. Нумеричком истраживању била је подвргнута елевациона земуница на територији града Крагујевца, моделирана у скаду са Правилником о енергетској ефикасности зграда. Симулациони сценарио био је базиран на следећим варијаблама: дебљина стиропора у конструкцији јужних фасадних зидова (прва варијабла) и оптичке (апсорптивност и емисивност) карактеристике селективних премаза (друга варијабла). Иако је употреба селективних премаза углавном ограничена на апсорбере соларних пријемника за загревање воде, њихова примена у зградарству такође може бити од великог значаја.Publishe
ASSESSMENT OF STUDENTS’ ATTITUDES TOWARDS DISTANCE MATHEMATICS LEARNING USING K-NEAREST NEIGHBOUR CLASSIFIER
Full text linkRecently, distance learning has emerged as a focal point of investigation within the field of education, particularly due to the COVID-19 pandemic. Considering the characteristics of mathematics instruction, distance mathematics education has been intensively researched worldwide. In the present research we explore students’ attitudes toward various aspects of distance learning in mathematics. Secondary and
high school students (n=532) participated in the study and they expressed their attitudes about distance mathematics education using a Likert-type scale. The survey comprised 26 questions, intending to assess the effectiveness of distance learning and its impact on understanding and acquiring mathematical content. The use of the k-Nearest Neighbors (KNN) classifier helped classify students’ attitudes based on various factors. While KNN does not directly model relationships between variables, its analysis in this research provides insights into the effectiveness of distance learning and its potential impact on students’ ability to acquire mathematical content. To evaluate our model’s performance, we calculated the mean accuracy using cross-validation. The accuracy for the students’ statement that the distance mathematics education was effective is 0.81, and for the for the second statement that students agree that they can adopt mathematical contents in online learning environment is 0.85. These results suggest that our model effectively predicts students’ attitudes toward distance learning in mathematics. Moreover, this methodology provides insights into the effectiveness of distance mathematics instruction and the factors influencing students’ attitudes.https://eme.upol.cz/proceedings/Collection_of_Abstract_EME2024.pdfPublishe
TOWN(S) IN THE LYRICAL WRITINGS OF MILOSAV TEŠIĆ
No full textThe main intention of the work is to look at the problematic relationship between the
lyrical subject and the town on the example of Milosav Tešić’s lyrical writings From the habitat of
birch grandfathers. In the mentioned part, the town is presented as the antipode of the homeland,
so it was initially marked as a negative entity. The lyrical subject strives to strengthen his authentic
existence, which is threatened in the urban environment, by returning to the nature of his native
land. However, within the structure of lyrical writings, it is possible to see the formation of another, completely differently conceived townhttps://www.philologiamediana.com/index.php/phm/article/view/894/838Publishe
Potential of Melittin to induce apoptosis and overcome multidrug resistance in human colon cancer cell line
Full text linkIn this study, the anticancer effect of Melittin was demonstrated through its antiproliferative and proapoptotic effects on HT-29 cells, as well as its ability to reverse multidrug resistance. Melittin directly affects the death receptor-dependent apoptotic pathway via increase of the Fas receptor protein expression, Caspase 8 gene expression and activity of Caspase 8. Results of decreased Caspase 9 gene and protein expression, and multi-fold increased expression of Bcl-2 gene suggest that mitochondria and the inner apoptotic pathway are not involved in the execution of Melittin induced apoptosis, as well as redox regulation of apoptosis based on decreased concentration of superoxide anion radicals and no effect glutathione levels. Specially significance of this work are results on ability of Melittin to modulate the metabolism and export system in cancer cells. Based on the increased expression of all the investigated genes related to the biotransformation process, it can be assumed that CYP1A1, CYP1B1, GSTP1 and MRP2 are involved in metabolism of Melittin in HT-29 cells. P-glycoprotein is associated with the occurrence of resistance in anticancer therapy, so its reduced gene and protein expression by Melittin represents significant result in terms of possible therapeutic application and examination.Publishe