Comparative numerical and experimental investigation of static and dynamic characteristics of composite plates

Marija Baltić,Jelena Svorcan,Bojan Perić,Miloš Vorkapić,Toni Ivanov,Ognjen Peković 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

In order to investigate both static and dynamic characteristics of composite plates and validate a contemporary, non-invasive experimental technique a comparative experimental and numerical analysis was performed. Three, geometrically the same but different in ply orientation, carbon-epoxy laminates were tested in both healthy and damaged conditions. Damages were inflicted in a shape of horizontal crack. Experiments and numerical simulations were performed by digital image correlation (DIC) and finite element method (FEM), respectively. Obtained time-responses of the tested structures were fast Fourier transformed (FFT) to frequency domain for a clearer understanding of natural frequencies and oscillation modes. Results are presented in tabular and graphical form. The overall correspondence of two sets of structural displacements is satisfactory. Some discrepancies might be contributed to the idealized geometry and restraint consideration. Also, due to the fast damping of higher tones, the errors in determining higher natural frequencies increase but still remain in 5 % range.

In vitro investigation of electrophoretically deposited bioactive hydroxyapatite/chitosan coatings reinforced by graphene

Marija Ðošic,Sanja Erakovic,Ana Jankovic,Maja Vukašinovic-Sekulic,Ivana Z. Matic,Jovica Stojanovic,이경엽,Vesna Miškovic-Stankovic,박수진 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.47 No.-

Graphene (Gr) and natural polymer chitosan (CS) were introduced to hydroxyapatite (HAP) to produce athree-component composite coating, which was fabricated by cathodic electrophoretic deposition on Tisubstrates in an ethanol suspension. These HAP/CS/Gr coatings were characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-rayphotoelectron spectroscopy (XPS) and electrochemical measurements and found that the graphene intoHAP/CS composites significantly improves their morphology, thermal stability, and bioactivity. BothHAP/CS and HAP/CS/Gr composite coatings are classified as non-cytotoxic when tested against healthyperipheral blood mononuclear cells (PBMC), while antibacterial activity against Staphylococcus aureusand Escherichia coli could not be verified.

Correlations among Stress Parameters, Meat and Carcass Quality Parameters in Pigs

Marija Dakmanovic,Milan Z. Baltic,Jelena Duric,Jelena Ivanovic,Ljuba Popovic,Milica Todorovic,Radmila Markovic,Srdan Pantic 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.3

Relationships among different stress parameters (lairage time and blood level of lactate and cortisol), meat quality parameters (initial and ultimate pH value, temperature, drip loss, sensory and instrumental colour, marbling) and carcass quality parameters (degree of rigor mortis and skin damages, hot carcass weight, carcass fat thickness, meatiness) were determined in pigs (n = 100) using Pearson correlations. After longer lairage, blood lactate (p<0.05) and degree of injuries (p<0.001) increased, meat became darker (p<0.001), while drip loss decreased (p<0.05). Higher lactate was associated with lower initial pH value (p<0.01), higher temperature (p<0.001) and skin blemishes score (p<0.05) and more developed rigor mortis (p<0.05), suggesting that lactate could be a predictor of both meat quality and the level of preslaughter stress. Cortisol affected carcass quality, so higher levels of cortisol were associated with increased hot carcass weight, carcass fat thickness on the back and at the sacrum and marbling, but also with decreased meatiness. The most important meat quality parameters (pH and temperature after 60 minutes) deteriorated when blood lactate concentration was above 12 mmol/L.

Theoretical Studies of the Electrical Discharge Characteristics of Sulfur Hexafluoride

Marija Radmilovi?- Radjenovi?,Branislav Radjenovi? 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

This paper contains results of the theoretical studies of the electrical breakdown properties in sulfur hexafluoride. Since the strong interaction of high-energy electrons with the polyatomic sulfur hexafluoride molecule causes their rapid deceleration to the lower energy of electron capture and dissociative attachment, the breakdown is only possible at relatively high field strengths. From the breakdown voltage curves, the effective yields that characterize secondary electron productions have been estimated. Values of the effective yields are found to be more consistent if they are derived from the experimentally determined values of the ionization coefficient and the breakdown voltages. In addition, simulations were performed using an one-dimensional Particle-in-cell/Monte Carlo collision code. The obtained simulation results agree well with the available experimental data with an error margin of less than 10% over a wide range of pressures and the gap sizes. The differences between measurements and calculations can be attributed to the differences between simulation and experimental conditions. Simulation results are also compared with the theoretical predictions obtained by using expression that describes linear dependence of the breakdown voltage in sulfur hexafluoride on the pressure and the gap size product.

The modelling of biosorption for rapid removal of organic matter with activated sludge biomass from real industrial effluents

Marija Vuković Domanovac,Monika Šabić Runjavec,Ernest Meštrović 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Biosorption is becoming increasingly important for the treatment of pollutants due to its cost-effectiveness,environmental friendliness and efficiency. For a more sustainable environment, more studies need to focus on theapplication of real industrial effluents. Increasing the initial concentration of activated sludge increases the specific surfacearea of the sludge, which allows for greater sorption of sorbates. The optimal initial concentration of activatedsludge in the process of biosorption of pollutants from pharmaceutical effluent was 5.12±0.13 g/L. The biosorptionprocess can be described by the Temkin model, where the estimated values of BT and AT ranged from 29.11 to 76.08and from 1.10 to 1.48 L/g, respectively. The overall efficiency of the biosorption process ranged from 9.5 to 40.2%. Theremoved toxicity averaged 41.1±7.88% for all experiments.

Effect of additives on the hydrothermal synthesis of manganese ferrite nanoparticles

Kurtinaitiene, Marija,Mazeika, Kestutis,Ramanavicius, Simonas,Pakstas, Vidas,Jagminas, Arunas Techno-Press 2016 Advances in nano research Vol.4 No.1

Superparamagnetic iron oxide nanoparticles (Nps), composed of magnetite, $Fe_3O_4$, or maghemite, ${\gamma}-Fe_2O_3$, core and biocompatible polymer shell, such as dextran or chitozan, have recently found wide applications in magnetic resonance imaging, contrast enhancement and hyperthermia therapy. For different diagnostic and therapeutic applications, current attempt is focusing on the synthesis and biomedical applications of various ferrite Nps, such as $CoFe_2O_4$ and $MnFe_2O_4$, differing from iron oxide Nps in charge, surface chemistry and magnetic properties. This study is focused on the synthesis of manganese ferrite, $MnFe_2O_4$, Nps by most commonly used chemical way pursuing better control of their size, purity and magnetic properties. Co-precipitation syntheses were performed using aqueous alkaline solutions of Mn(II) and Fe(III) salts and NaOH within a wide pH range using various hydrothermal treatment regimes. Different additives, such as citric acid, cysteine, glicine, polyetylene glycol, triethanolamine, chitosan, etc., were tested on purpose to obtain good yield of pure phase and monodispersed Nps with average size of ${\leq}20nm$. Transmission electron microscopy (TEM), X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), $M\ddot{o}ssbauer$ spectroscopy down to cryogenic temperatures, magnetic measurements and inductively coupled plasma mass spectrometry were employed in this study.

From neutrality to engagement: the modalities of understanding secondary teacher professionalism in dealing with LGBT issues

Bartulović Marija,Kušević Barbara,Širanović Ana 한국다문화교육학회 2023 Multicultural Education Review Vol.15 No.1

This paper provides a framework for analysing teachers’ various modes of positioning towards LGBT students, generated from their understanding of the concept of teacher professionalism. The main research question of the empirical study, conducted through application of focus groups, is how secondary school educators understand the concept of teacher professionalism in dealing with LGBT issues within the context of secondary school as a place where sexuality is both explicitly present and a taboo. The results, analysed within a neutral-engaged dichotomy of teacher positioning when dealing with LGBT issues, and interpreted from a critical-pedagogical perspective, point to different modalities of understanding and practicing teacher professionalism, as well as to the unsustainability of the neutral orientation of teachers when making both commonplace and unpredictable pedagogical decisions, which are inevitably politicized.

From White to Magenta

Ana Marija Grancaric,Martinia Ira Glogar,Lea Botteri 한국색채학회 2017 AIC 2017 Jeju Vol.2017 No.10

This paper presents two colours, white and magenta. From physical point of view white has the high level of luminosity, no saturation and no hue. By application of fluorescent whitening agents (FWA`s) white surfaces can reach great whiteness and brightness but in same time its spectral characteristics move slightly from achromatic point (AP) towards the blue spectrum of chromaticity diagram. In this paper, chemically bleached cotton fabrics is treated with stilbene derivate based fluorescent whitening agents and their whiteness degrees, spectral characteristics and relative intensity of fluorescence are presented. On the other hand magenta spreads to a large extent of spectrum by bridging two ends of a spectrum, the red and blue, different in their frequency and absorption energy. In this paper the analysis of one specific magenta colour will be performed from the aspects of spectral characteristic, specific energy and given specific wavelength of absorption.

Radioactivity of biological samples of patients treated with 90Y-DOTATOC

Jeremic Marija Z.,Matovic Milovan D.,Mijatovic Nenad R.,Pantovic Suzana B.,Krstic Dragana Z.,Miladinovic Tatjana B.,Nikezic Dragoslav R. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.10

Dosimetric studies in Nuclear Medicine are very important, especially with new therapeutic methods, the number of which has increased significantly with the Theranostic approach (determining diagnostictherapeutic pairs where similar molecules are labelled with different isotopes in order to diagnose and treat malignant diseases). Peptide receptor radionuclide therapy (PRRT) has been used successfully for many years to treat neuroendocrine tumors (NET). 90Y-DOTATOC is one of the radiopharmaceuticals used frequently in this type of therapy. In this work, blood and urine samples from 13 patients treated with 90Y-DOTATOC were measured by a liquid scintillation beta counter (LSC). Calibration of the beta counter for this type of measurement was done and all results are presented in the paper. The presented paper also provides a methodology for determining the measurement uncertainty for this type of measurement. Immediately after the administration of radiopharmaceuticals, the activity in the blood was different from 6.31% to 88.9% of the applied radioactivity, while 3 h after the termination of the application, the average value of radiopharmaceuticals in the blood was only 3.84%. The activity in the excreted urine depended on the time when the patients urinated after the therapy. It was measured that as much as 58% of the applied radioactivity was excreted in the first urine after the therapy in a patient who urinated 4.5 h after the completed application of the therapy. In most patients, the highest urine activity was in the first 10 h after the application, while the activities after that time were negligibly low. The described methodology of measuring and evaluating activity in blood and excreted urine can be applied to other radiopharmaceuticals used in nuclear medicine. It could be useful for researchers for dosimetric assessments in clinical application of PRRT

Correlations among Stress Parameters, Meat and Carcass Quality Parameters in Pigs

Dokmanovic, Marija,Baltic, Milan Z.,Duric, Jelena,Ivanovic, Jelena,Popovic, Ljuba,Todorovic, Milica,Markovic, Radmila,Pantic, Srdan Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.3

Relationships among different stress parameters (lairage time and blood level of lactate and cortisol), meat quality parameters (initial and ultimate pH value, temperature, drip loss, sensory and instrumental colour, marbling) and carcass quality parameters (degree of rigor mortis and skin damages, hot carcass weight, carcass fat thickness, meatiness) were determined in pigs (n = 100) using Pearson correlations. After longer lairage, blood lactate (p<0.05) and degree of injuries (p<0.001) increased, meat became darker (p<0.001), while drip loss decreased (p<0.05). Higher lactate was associated with lower initial pH value (p<0.01), higher temperature (p<0.001) and skin blemishes score (p<0.05) and more developed rigor mortis (p<0.05), suggesting that lactate could be a predictor of both meat quality and the level of preslaughter stress. Cortisol affected carcass quality, so higher levels of cortisol were associated with increased hot carcass weight, carcass fat thickness on the back and at the sacrum and marbling, but also with decreased meatiness. The most important meat quality parameters (pH and temperature after 60 minutes) deteriorated when blood lactate concentration was above 12 mmol/L.