POLITIKA ODRŽIVOG RAZVOJA NAUTIČKOG TURIZMA : završni rad

Rad ne sadrži sažetak

POLITIKA ODRŽIVOG RAZVOJA NAUTIČKOG TURIZMA : završni rad

Rad ne sadrži sažetak

Fungi and bacteria in biological control against pathogens

Zbog stalnog povećanja upotrebe kemijskih pesticida i njihovog štetnog djelovanja na ljudsko zdravlje i okoliš, sve veće zanimanje pobuđuju metode biološke kontrole uzročnika biljnih bolesti. Biološka kontrola je mjera koja podrazumijeva korištenje mikroorganizama koji smanjuju populaciju štetnika i patogena i na taj način štite biljku i kontroliraju razvoj bolesti. U Hrvatskoj je trenutno na tržištu prisutan samo jedan biofungicid, na bazi bakterije iz roda Pseudomonas, za suzbijanje uzročnika bijele noge (Rhizoctonia solani) na krumpiru, batatu, čičoki i kineskom jamu te uzročnika srebrolikosti gomolja (Helminthosporium solani) na krumpiru. Vrste Bacillus thuringiensis, Bacillus subtilis i Pseudomonas fluorescens su najvažniji predstavnici bakterija uključenih u biokontrolu protiv uzročnika biljnih bolesti. Do danas je na svjetskom tržištu prisutno ili je u procesu registracije 28 sredstava na bazi različitih vrsta roda Trichoderma, koji većinom djeluju protiv fitopatogenih gljiva iz rodova Pythium, Rhizoctonia i Fusarium. Najzastupljenije vrste roda Trichoderma koje se koriste u biološkoj kontroli su Trichoderma harzianum, Trichoderma viride i Trichoderma koningii. Upotreba antagonističkih gljiva i bakterija u biološkoj kontroli brojnih uzročnika bolesti predstavlja važnu alternativu kojom bi se mogli zamijeniti kemijski pesticidi ili u što većoj mjeri smanjiti njihova primjena. Cilj rada je prikazati antagonističke gljive i bakterije koje se koriste u biološkoj kontroli te opisati njihove složene mehanizme djelovanja.Because of the constant increase in the use of chemical pesticides and their harmful effects on human health and the environment, the growing interest in the use of alternative methods for biological control of plant pathogens is increasing Biological control is a measure that involves microorganisms that reduce the population of pests and pathogens, thus protect the plant and control the development of the disease. In Croatia, there is only one biofungicide on the market based on the genus Pseudomonas, and it was registered in 2017 for the suppression of white foot root (Rhizoctonia solani) on potato, sweet potato, Jerusalem artichoke and Chinese yam and tuber rupture (Helminthosporium solani). Species Bacillus thuringiensis, Bacillus subtilis and Pseudomonas fluorescens are the most important representatives of the bacteria involved in the biocontrol against plant diseases. To date, there are present or are in the process of registering 28 strains based on different strains of Trichoderma species, most of which are active against phytopathogenic fungus from genus Pythium, Rhizoctonia and Fusarium. The most common species of the genus Trichoderma used in biological control are Trichoderma harzianum, Trichoderma viride and Trichoderma koningii. The use of antagonistic fungi and bacteria in the biological control of many pathogens are an important alternative in substituting chemical pesticides and reducing their application to a greater extent. The aim of this paper is to show latter antagonistic fungi and bacteria used in biological control and describe their complex mechanisms of action

Development of macroporous bioceramic materials based on multi-ion doped calcium-hydroxyapatite coated with chitosan

In recent years, scientists have been working on developing biocompatible materials that closely mimic the structure and properties of natural biological tissues for their application in hard tissue regeneration and controlled drug release. Human bones and teeth primarily consist of calcium-phosphate crystals with small amounts of various ions incorporated into their crystal structure. The aim of this study was to examine the possibility of processing macroporous bioceramic scaffolds based on calcium-hydroxyapatite (HAp) doped with magnesium (Mg), strontium (Sr) and fluorine (F) ions, subsequently coated with polymer chitosan. In this study, the doped HAp powder was synthesized by a hydrothermal process, and scaffolds were made using the sponge replica method, sintered and then coated with the chitosan. The influence of dopant ions and chitosan on the scaffold's microstructure, mechanical properties, bioactivity, cytotoxicity and drug release properties was examined. Energy dispersive spectroscopy confirmed that Mg and Sr are incorporated in all powder samples, while the presence of F was confirmed in samples synthesized with 1 and 2 mol.% F in the precursor solution. The phase composition of powders and scaffolds determined by X-ray analysis showed the presence of HAp and β-tricalcium phosphate phase (β-TCP) in scaffolds. In the compressive strength (CS) test, coated scaffolds showed significantly higher CS compared to uncoated scaffolds. Scanning electron microscopy was used to examine the morphology of nanostructured powders, microstructure, and the bioactivity of the scaffolds. The uncoated scaffolds showed satisfactory bioactivity after being immersed in simulated body fluid for 28 days, while lower bioactivity was observed in the coated scaffolds due to the slow degradation of chitosan. The synthesized scaffolds also demonstrated to have a positive impact on cell viability, even slightly stimulating the cell proliferation. Additionally, scaffolds were shown to successfully release drug. In concusion, the addition of ions and chitosan polymer significantly improved the properties of the obtained scaffolds, which indicates their potential application in tissue engineering and controlled drug release.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Assessment of neutrophil-lymphocyte and platelet-lymphocyte ratio in patients with hashimoto's thyroiditis

INTRODUCTION: The ratio of neutrophils-lymphocytes (NLR) and platelet-lymphocytes (PLR) is a new parameter in the assessment of patients with Hashimoto's thyroiditis OBJECTIVE: The aim of this study was to investigate the effect of NLR and PLR in patients with Hashimoto's thyroiditis MATERIALS AND METHODS: In this cross-sectional study, subjects were subjected to tests of thyroid gland function, antithyroid antibodies, as well as laboratory analyzes of blood count with determination of NLR and PLR. The respondents were grouped into two groups. The first group was patients with Hashimoto's thyroiditis (HT), while the second group consisted of healthy individuals who represented the control group. RESULTS: NLR was statistically significantly higher in patients with HT compared to the control group (2.62±0.8 and 2.43±0.8, respectively; p=0.02), while PLR was higher in people with HT compared to the control group, but without statistical significance significance (169±42.5; 159±40.3; p=0.08). Among the examined patients with HT, the group with hypothyroidism showed statistically higher NLR values compared to the group of patients with euthyroid status (2.7±0.9 ; 2.31±0.7 p=0.03). Among the examined patients with HT, the group with hypothyroidism showed statistically higher PLR values compared to the group of patients with euthyroid status, as well as the group with subclinical hypothyroidism (177.8±48.2; 148.3±39.3; 155.5±42.5 p=0.04). NLR and PLR show a statistically significant positive correlation with the level of TSH, Anti TPO and TG At in the group with HT. CONCLUSION: NLR and PLR can serve as practical and valuable markers of the clinical course of the disease, but also markers of autoimmune diseases that progress with chronic inflammation

The effect of hydrothermal synthesis parameters on cation-doped calciumhydroxyapatite

Calcium hydroxyapatite (HAP) presents the main mineral component of human bones and teeth, and thus is widely used bioceramic material for thehard tissue repair and regeneration. The biological HAP is never found pure in nature butdoped with multiple therapeutic ions, such as Cu, Mg, Sr, Zn, etc., which are found to play important roles in bone metabolism and growth. Hence, foreign cations have been introduced into the synthetic calcium hydroxyapatite, in order to induce a specific biological response after implementation, such as osteogenesis, angiogenesis, improved cell attachment and proliferation. However, the presence of the cations leads to the lattice distortion of the calcium-hydroxyapatite, resulting in different physico-chemical and mechanical properties. The hydrothermal synthesis of calcium hydroxyapatite leads to nanosized rod-like particles, which were found to possess properties close to those of the biological HAP. The aim of this study was to investigate the effect of hydrothermal synthesis parameters on physico-chemical and mechanical properties of mono- and binary cation-doped calcium hydroxyapatite by employing XRD, SEM and Hardness by Vickers tests. The temperature applied during the hydrothermal synthesis (150- 180 °C) was found to influence the hardness of the HAP based compacts sintered at 1200 °C.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

An additional students’ task at Descriptive Geometry

At the Faculty of Civil Engineering, University of Belgrade, beside the obligatory forms of lectures and exercises, freshmen students have the opportunity to widen their practical experience in application of geometric knowledge, gained at Descriptive Geometry course, through non obligatory workshop. It was organized at the Faculty classrooms during two days, such that a group of students (three students) works on a creative geometry task, within given conditions. Starting from free choice of an existing or imagery type of architectural structure (a whole building or its roofng structure) students should provide its geometric interpretation of orthogonal projections on a 3D physical model of coordinate system -1; 3D model in Auto-CAD sofware (the alternative is cardboard model) - 2; presentation of a structure in 3D augmented reality application “Augment” – 3; visual appearance of a structure in architecture/design (a photo image) -4; poster summary of the sub-tasks – 5. The satisfactory completion of a task would enable a student to get higher grade in the fnal exam at Descriptive geometry course. Based on the results of additional questionnaire administered to the participants at the end of the workshop, besides good achievement, creativity, self-confdence and high-quality teamwork signifcantly contribute to overall satisfaction of students

Mg/Cu co-substituted hydroxyapatite – Biocompatibility, mechanical properties and antimicrobial activity

The aim of this study was to improve the mechanical properties and to optimize antimicrobial activity of hydroxyapatite (HAP) by simultaneous doping with Mg and Cu ions in order to obtain material that would be able to assist in the bone/tooth healing process, prevent post-implementation infections and provide satisfying values of hardness and fracture toughness for biomedical application. Ion doping was done during the hydrothermal synthesis of HAP powders, whereby the content of Mg ions in the starting solution was varied between 1-20 mol. % with regard to Ca ions, while the amount of Cu ions was kept constant at 0.4 mol. %. The green compacts were sintered for 2 h at temperatures ranging 750–1200 °C depending on the Mg content, chosen in agreement with dilatometry results. Presence of Mg ions was found to favour transition from HAP to β−tricalcium phosphate phase (β−TCP), which enabled formation of biphasic HAP/β−TCP and pure β−TCP phase at 160 °C during hydrothermal synthesis. In vitro investigation of antimicrobial activity against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis showed satisfactory antimicrobial activity. MTT assay performed on MRC-5 and L929 cell lines showed excellent cytocompatibility and cell proliferation. Maximum hardness by Vickers and fracture toughness values, 4.96 GPa and 1.75 MPa m1/2 respectively, were obtained upon addition of 5 mol. % Mg, as a consequence of the lowest grain size and porosity, as well as the highest densification rate. This is, to the best of our knowledge, the highest fracture toughness for HAP or β-TCP ceramics reported thus far.This is the peer-reviewed version ofthe article: Veljović, Đorđe, Matić, Tamara, Stamenić, Tanja, Kojić, Vesna, Dimitrijević Branković, Suzana, Lukić, Miodrag J., Jevtić, Sanja, Radovanović, Željko, Petrović, Rada, Janaćković, Đorđe, "Mg/Cu co-substituted hydroxyapatite – Biocompatibility, mechanical properties and antimicrobial activity" in Ceramics International, 45, no. 17, Part A (2019):22029, [https://doi.org/10.1016/j.ceramint.2019.07.219

Sodium Periodate Oxidation of Raw Jute Fabric – A Novel Approach for Tuning the Jute Structure and Properties

This investigation represents a novel approach for tuning the jute structure and properties using sodium periodate (NaIO4) oxidation. The obtained results revealed that the jute fabrics exhibited an increase in the aldehyde group content (for up to 114.7%) with an increase in the NaIO4 concentration and/or oxidation duration. Due to the decline in the cellulose lateral order index (LOI) and fiber crystallinity index after oxidation, it can be concluded that jute crystalline areas are affected by sodium periodate oxidation. Both mentioned parameters are responsible for fabric mechanical properties, so, it was expected that by decreasing the LOI and jute fibers’ crystallinity, their maximum force and stiffness will decrease too. This behavior is also attributed to the fiber damage, which is the most pronounced for the fabric treated with 0.4% NaIO4 for 120 min. Besides slightly deteriorated mechanical properties, fabrics oxidized with 0.2% NaIO4 for 60 or 120 min and with 0.4% NaIO4 for 60 min showed lower mass loss (6.78-12.22%) after 750 abrasion cycles compared to the raw jute (18.94%). Furthermore, oxidation led to obtaining fabrics with enhanced moisture sorption and water retention power that are inversely proportional to the fiber crystallinity. Due to the opportunity for tuning fiber structure and properties oxidized fabrics can be considered for various applications such as geo-prebiotic supports for cyanobacteria growth in biocarpet engineering, i.e., to promote a sustainable relationship between the microbiota and abiotic constituents on the degraded land surface

Hemocompatibility evaluation of N-doped carbon quantum dots

Nitrogen-doped carbon quantum dots (N-CQDs) are promising next generation nanomaterials for potential biomedical applications such as bioimaging, biosensing, and drug/gene delivery. However, N-CQDs biocompatibility has not been extensively investigated. Here, we report physico-chemical characteristics of newly synthetized N-CQDs and their effects on red blood cells (RBC), by analyzing their hemolytic activity, impact on RBC rheology/morphology, and oxidative stress induction. N-CQDs were prepared by hydrothermal method using citric acid and urea as precursors. Structural analyses of as prepared N-GQDs, observed by HRTEM/EDS, showed that the lateral dimensions of the particles are in the 10 to 20 nm range, as well as that the carbon, oxygen, and nitrogen are present in the nanosystem. Based on AFM measurements, the average height of N-CQDs was 3.9±0.08 Å. Photoluminescence emission (PLE) spectrum demonstrated that N-CQDs exhibit stable and strong fluorescence in green (520 nm) region, upon 410 nm excitation. FTIR spectroscopy indicated vibrational bands, characteristic for carbon structures and primary amines (Ndoping). N-CQDs were negatively charged with an average Zeta potential of -15.3 mV as confirmed by DLS. To investigate hemocompatibility of N-CQDs, the RBC, the most abundant cells in blood, were treated with different concentration of N-CQDs (10-400 ug/ml) for 2h. Obtained results showed that there was no hemolytic activity. Moreover, ektacytometry analysis demonstrated that N-CQDs did not affect deformability of RBC. Fluorescent microscopy analyses revealed that treatment with N-CQDs did not induce significant morphological aberrant forms of RBC which was also confirmed by SEM analyses. Flow cytometry confirmed only slight RBC morphological changes based on FSC/SSC analysis. Furthermore, using ROS sensitive dye flow cytometry analyses suggested that N-CQDs did not induce oxidative stress in RBC. Taken together, our findings highlighted that exposure of RBC to N-CQDs only led to the attachment of N-CQDs on RBC membranes, but there is no other evidence of their nanotoxicity. These findings suggested that N-CQDs synthetized from ecofriendly precursors are potentially biocompatible and safe for biomedical application