TY  - JOUR
AU  - Tadić, Marin
AU  - Trpkov, Đorđe
AU  - Kopanja, Lazar
AU  - Vojnović, Sandra
AU  - Panjan, Matjaž
PY  - 2019
UR  - https://linkinghub.elsevier.com/retrieve/pii/S0925838819312587
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8133
AB  - In this work, we present the magnetic and structural properties of α-Fe 2 O 3 nanoparticles synthesized by the hydrothermal synthesis method. XRD, FTIR and Raman spectroscopy indicate that the samples consist of single-phase α-Fe 2 O 3 nanoparticles. A microstructural analysis by TEM and SEM shows: (i) irregular nanoparticles (∼50 nm), (ii) plate-like nanoparticles (with thickness t∼10 nm and diameter d∼50–80 nm) and (iii) microsized ellipsoid 3D superstructures (with length l∼3.5 and diameter d∼1.5 μm) composed of nanosized building blocks (∼50 nm). We used circularity, elongation and convexity measures to quantitatively analyze the shape of the particles. Irregular hematite nanoparticles were synthesized using a water solution of ferric precursor and sodium acetate during the hydrothermal reaction (reaction conditions: T = 180 °C, t = 12 h). The same hydrothermal reaction temperature, reaction duration and ferric precursor (without sodium acetate) were used for synthesizing hematite ellipsoid 3D superstructures. Addition of urea and glycine surfactants in hydrothermal reaction resulted in the formation of nanoplate hematite particles. The role of these surfactants on the structure and morphology of the particles was also investigated. Magnetic measurements at the room temperature displayed a wide range of coercivities, from H C = 73 Oe for irregular nanoparticles, H C = 689 Oe for nanoplates to H C = 2688 Oe for hematite ellipsoid 3D superstructures. The measured coercivity for the ellipsoid superstructure was about 35 times higher than in the case of irregular hematite nanoparticles and about 4 times than the coercivity of hematite nanoplates. Magnetic properties of synthesized samples were related to their structure and morphology. We conclude that shape anisotropy influenced enhancement of the coercivity in hematite nanoplates whereas hematite ellipsoid 3D superstructure (nanoparticle clusters) induced the formation of multidomain magnetic structure and highest coercivity revealing its superior structure for enhanced magnetic properties. The synthesized hematite nanoparticle structures exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating a safe use of these nanoparticles for practical applications. © 2019 Elsevier B.V.
T2  - Journal of Alloys and Compounds
T1  - Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties
VL  - 792
SP  - 599
EP  - 609
DO  - 10.1016/j.jallcom.2019.03.414
ER  - 

@article{
author = "Tadić, Marin and Trpkov, Đorđe and Kopanja, Lazar and Vojnović, Sandra and Panjan, Matjaž",
year = "2019",
abstract = "In this work, we present the magnetic and structural properties of α-Fe 2 O 3 nanoparticles synthesized by the hydrothermal synthesis method. XRD, FTIR and Raman spectroscopy indicate that the samples consist of single-phase α-Fe 2 O 3 nanoparticles. A microstructural analysis by TEM and SEM shows: (i) irregular nanoparticles (∼50 nm), (ii) plate-like nanoparticles (with thickness t∼10 nm and diameter d∼50–80 nm) and (iii) microsized ellipsoid 3D superstructures (with length l∼3.5 and diameter d∼1.5 μm) composed of nanosized building blocks (∼50 nm). We used circularity, elongation and convexity measures to quantitatively analyze the shape of the particles. Irregular hematite nanoparticles were synthesized using a water solution of ferric precursor and sodium acetate during the hydrothermal reaction (reaction conditions: T = 180 °C, t = 12 h). The same hydrothermal reaction temperature, reaction duration and ferric precursor (without sodium acetate) were used for synthesizing hematite ellipsoid 3D superstructures. Addition of urea and glycine surfactants in hydrothermal reaction resulted in the formation of nanoplate hematite particles. The role of these surfactants on the structure and morphology of the particles was also investigated. Magnetic measurements at the room temperature displayed a wide range of coercivities, from H C = 73 Oe for irregular nanoparticles, H C = 689 Oe for nanoplates to H C = 2688 Oe for hematite ellipsoid 3D superstructures. The measured coercivity for the ellipsoid superstructure was about 35 times higher than in the case of irregular hematite nanoparticles and about 4 times than the coercivity of hematite nanoplates. Magnetic properties of synthesized samples were related to their structure and morphology. We conclude that shape anisotropy influenced enhancement of the coercivity in hematite nanoplates whereas hematite ellipsoid 3D superstructure (nanoparticle clusters) induced the formation of multidomain magnetic structure and highest coercivity revealing its superior structure for enhanced magnetic properties. The synthesized hematite nanoparticle structures exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating a safe use of these nanoparticles for practical applications. © 2019 Elsevier B.V.",
journal = "Journal of Alloys and Compounds",
title = "Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties",
volume = "792",
pages = "599-609",
doi = "10.1016/j.jallcom.2019.03.414"
}

Tadić, M., Trpkov, Đ., Kopanja, L., Vojnović, S.,& Panjan, M.. (2019). Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties. in Journal of Alloys and Compounds, 792, 599-609.
https://doi.org/10.1016/j.jallcom.2019.03.414

Tadić M, Trpkov Đ, Kopanja L, Vojnović S, Panjan M. Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties. in Journal of Alloys and Compounds. 2019;792:599-609.
doi:10.1016/j.jallcom.2019.03.414 .

Tadić, Marin, Trpkov, Đorđe, Kopanja, Lazar, Vojnović, Sandra, Panjan, Matjaž, "Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties" in Journal of Alloys and Compounds, 792 (2019):599-609,
https://doi.org/10.1016/j.jallcom.2019.03.414 . .

TY  - JOUR
AU  - Kopanja, Lazar
AU  - Lončar, Boris B.
AU  - Žunić, Dragiša
AU  - Tadić, Marin
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8590
AB  - The goal of the nanoparticle synthesis is, first of all, the production of nanoparticles that will be more similar in size and shape. This is very important for the possibility of studying and applying nanomaterials because of their characteristics that are very sensitive to size and shape such as, for example, magnetic properties. In this paper, we propose the shape analysis of the nanoparticles using three shape descriptors – elongation, convexity and circularity. Experimental results were obtained by using TEM images of hematite nanoparticles that were, first of all, subjected to segmentation in order to obtain isolated nanoparticles, and then the values of elongation, convexity and circularity were measured. Convexity C x ( S ) is regarded as the ratio between shape’s area and area of the its convex hull. The convexity measure defines the degree to which a shape differs from a convex shape while the circularity measure defines the degree to which a shape differs from an ideal circle. The range of convexity and circularity values is (0, 1], while the range of elongation values is [1, ∞). The circle has lowest elongation (ε = 1), while it has biggest convexity and circularity values ( C x = 1; C = 1). The measures ε( S ), C x ( S ), C ( S ) proposed and used in the experiment have the few desirable properties and give intuitively expected results. None of the measures is good enough to describe all the shapes, and therefore it is suggested to use a variety of measures so that the shapes can be described better and then classify and control during the synthesis process.
T2  - Journal of Electrical Engineering
T1  - Nanoparticle shapes: Quantification by elongation, convexity and circularity measures
VL  - 70
IS  - 7
SP  - 44
EP  - 50
DO  - 10.2478/jee-2019-0040
ER  - 

@article{
author = "Kopanja, Lazar and Lončar, Boris B. and Žunić, Dragiša and Tadić, Marin",
year = "2019",
abstract = "The goal of the nanoparticle synthesis is, first of all, the production of nanoparticles that will be more similar in size and shape. This is very important for the possibility of studying and applying nanomaterials because of their characteristics that are very sensitive to size and shape such as, for example, magnetic properties. In this paper, we propose the shape analysis of the nanoparticles using three shape descriptors – elongation, convexity and circularity. Experimental results were obtained by using TEM images of hematite nanoparticles that were, first of all, subjected to segmentation in order to obtain isolated nanoparticles, and then the values of elongation, convexity and circularity were measured. Convexity C x ( S ) is regarded as the ratio between shape’s area and area of the its convex hull. The convexity measure defines the degree to which a shape differs from a convex shape while the circularity measure defines the degree to which a shape differs from an ideal circle. The range of convexity and circularity values is (0, 1], while the range of elongation values is [1, ∞). The circle has lowest elongation (ε = 1), while it has biggest convexity and circularity values ( C x = 1; C = 1). The measures ε( S ), C x ( S ), C ( S ) proposed and used in the experiment have the few desirable properties and give intuitively expected results. None of the measures is good enough to describe all the shapes, and therefore it is suggested to use a variety of measures so that the shapes can be described better and then classify and control during the synthesis process.",
journal = "Journal of Electrical Engineering",
title = "Nanoparticle shapes: Quantification by elongation, convexity and circularity measures",
volume = "70",
number = "7",
pages = "44-50",
doi = "10.2478/jee-2019-0040"
}

Kopanja, L., Lončar, B. B., Žunić, D.,& Tadić, M.. (2019). Nanoparticle shapes: Quantification by elongation, convexity and circularity measures. in Journal of Electrical Engineering, 70(7), 44-50.
https://doi.org/10.2478/jee-2019-0040

Kopanja L, Lončar BB, Žunić D, Tadić M. Nanoparticle shapes: Quantification by elongation, convexity and circularity measures. in Journal of Electrical Engineering. 2019;70(7):44-50.
doi:10.2478/jee-2019-0040 .

Kopanja, Lazar, Lončar, Boris B., Žunić, Dragiša, Tadić, Marin, "Nanoparticle shapes: Quantification by elongation, convexity and circularity measures" in Journal of Electrical Engineering, 70, no. 7 (2019):44-50,
https://doi.org/10.2478/jee-2019-0040 . .

TY  - JOUR
AU  - Tadić, Marin
AU  - Kralj, Slavko
AU  - Kopanja, Lazar
PY  - 2019
UR  - https://linkinghub.elsevier.com/retrieve/pii/S1044580318323763
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8005
AB  - We report monodisperse, chain-like particles (nanochains) consisted of silica-coated maghemite (γ-Fe2O3) nanoparticle clusters prepared by colloidal chemistry and magnetic field-induced self-assembly of nanoparticle clusters. In order to quantify the shapes of chain-like particles, we have used the measure for shape convexity which is also called solidity. We functionalize the surface of the nanochains with amino (–NH2) and carboxyl groups (–COOH) in order to modify surface charge. These surfaces of nanochains provide better colloidal stability and their potential for practical applications in biomedicine. The enhanced colloidal stability of the surface modified nanochains is confirmed by Zeta potential (ζ-potential) analysis. Magnetic properties of the nanochains show superparamagnetic state at room temperature since the nanochains are composed of tiny nanoparticles as their building blocks. The measured M(H) data at room temperature have been successfully fitted by the Langevin function and magnetic moment μp = 20,526 μB for sphere-like nanoparticle clusters and μp = 20,767 μB for nanochains are determined. The determined magnetic parameters have revealed that the nanochains show a magnetic moment of the nanoparticles higher than the one of individual nanoparticle clusters. These differences can be attributed to the collective magnetic properties of superparamagnetic iron oxide nanoparticles (SPION) assembled in different morphologies (isotropic and anisotropic morphology). © 2018
T2  - Materials Characterization
T1  - Synthesis, particle shape characterization, magnetic properties and surface modification of superparamagnetic iron oxide nanochains
VL  - 148
SP  - 123
EP  - 133
DO  - 10.1016/j.matchar.2018.12.014
ER  - 

@article{
author = "Tadić, Marin and Kralj, Slavko and Kopanja, Lazar",
year = "2019",
abstract = "We report monodisperse, chain-like particles (nanochains) consisted of silica-coated maghemite (γ-Fe2O3) nanoparticle clusters prepared by colloidal chemistry and magnetic field-induced self-assembly of nanoparticle clusters. In order to quantify the shapes of chain-like particles, we have used the measure for shape convexity which is also called solidity. We functionalize the surface of the nanochains with amino (–NH2) and carboxyl groups (–COOH) in order to modify surface charge. These surfaces of nanochains provide better colloidal stability and their potential for practical applications in biomedicine. The enhanced colloidal stability of the surface modified nanochains is confirmed by Zeta potential (ζ-potential) analysis. Magnetic properties of the nanochains show superparamagnetic state at room temperature since the nanochains are composed of tiny nanoparticles as their building blocks. The measured M(H) data at room temperature have been successfully fitted by the Langevin function and magnetic moment μp = 20,526 μB for sphere-like nanoparticle clusters and μp = 20,767 μB for nanochains are determined. The determined magnetic parameters have revealed that the nanochains show a magnetic moment of the nanoparticles higher than the one of individual nanoparticle clusters. These differences can be attributed to the collective magnetic properties of superparamagnetic iron oxide nanoparticles (SPION) assembled in different morphologies (isotropic and anisotropic morphology). © 2018",
journal = "Materials Characterization",
title = "Synthesis, particle shape characterization, magnetic properties and surface modification of superparamagnetic iron oxide nanochains",
volume = "148",
pages = "123-133",
doi = "10.1016/j.matchar.2018.12.014"
}

Tadić, M., Kralj, S.,& Kopanja, L.. (2019). Synthesis, particle shape characterization, magnetic properties and surface modification of superparamagnetic iron oxide nanochains. in Materials Characterization, 148, 123-133.
https://doi.org/10.1016/j.matchar.2018.12.014

Tadić M, Kralj S, Kopanja L. Synthesis, particle shape characterization, magnetic properties and surface modification of superparamagnetic iron oxide nanochains. in Materials Characterization. 2019;148:123-133.
doi:10.1016/j.matchar.2018.12.014 .

Tadić, Marin, Kralj, Slavko, Kopanja, Lazar, "Synthesis, particle shape characterization, magnetic properties and surface modification of superparamagnetic iron oxide nanochains" in Materials Characterization, 148 (2019):123-133,
https://doi.org/10.1016/j.matchar.2018.12.014 . .

TY  - JOUR
AU  - Trpkov, Đorđe
AU  - Panjan, Matjaž
AU  - Kopanja, Lazar
AU  - Tadić, Marin
PY  - 2018
UR  - https://linkinghub.elsevier.com/retrieve/pii/S0169433218317872
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7770
AB  - We report on glycine-free and glycine-assisted hydrothermal synthesis of microsized superstructures composed of self-assembled hematite nanoparticles. An X-ray powder diffraction measurements of the samples confirm good crystallization of the hematite nanoparticles with hydrothermal reaction time-dependent crystallite sizes in a range from ∼15 nm (45 h) to ∼26 nm (90 h). The FTIR and Raman spectroscopy confirm hematite structure, whereas TEM measurements reveal nanoparticle sub-units (subparticles). The computational analyses of particle shape show that the addition of glycine surfactant in hydrothermal reaction leads to more spherical shape of hematite hierarchical structures and smaller sizes. We found strong coercivity increases (up to ∼3 times) in the samples synthesized in the presence of glycine. The coercivity values from HC = 1305 Oe (mushroom-like shape synthesized by glycine-free hydrothermal reaction) to HC = 3725 Oe (sphere-like shape synthesized by glycine-assisted hydrothermal reaction) were obtained at 300 K. These results and their comparison with other described in the literature (e.g. bulk, wires, urchin-like, rods, tubes, plates, star-like, dendrites, platelets, irregular, nanocolumns, spindles, disks hematites, etc.) reveal that the hematite superstructures possess good magnetic properties. We propose that the glycine, oriented subparticles, exchange and dipole-dipole interactions may play an important role in the development of magnetic properties.
T2  - Applied Surface Science
T1  - Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures
VL  - 457
SP  - 427
EP  - 438
DO  - 10.1016/j.apsusc.2018.06.224
ER  - 

@article{
author = "Trpkov, Đorđe and Panjan, Matjaž and Kopanja, Lazar and Tadić, Marin",
year = "2018",
abstract = "We report on glycine-free and glycine-assisted hydrothermal synthesis of microsized superstructures composed of self-assembled hematite nanoparticles. An X-ray powder diffraction measurements of the samples confirm good crystallization of the hematite nanoparticles with hydrothermal reaction time-dependent crystallite sizes in a range from ∼15 nm (45 h) to ∼26 nm (90 h). The FTIR and Raman spectroscopy confirm hematite structure, whereas TEM measurements reveal nanoparticle sub-units (subparticles). The computational analyses of particle shape show that the addition of glycine surfactant in hydrothermal reaction leads to more spherical shape of hematite hierarchical structures and smaller sizes. We found strong coercivity increases (up to ∼3 times) in the samples synthesized in the presence of glycine. The coercivity values from HC = 1305 Oe (mushroom-like shape synthesized by glycine-free hydrothermal reaction) to HC = 3725 Oe (sphere-like shape synthesized by glycine-assisted hydrothermal reaction) were obtained at 300 K. These results and their comparison with other described in the literature (e.g. bulk, wires, urchin-like, rods, tubes, plates, star-like, dendrites, platelets, irregular, nanocolumns, spindles, disks hematites, etc.) reveal that the hematite superstructures possess good magnetic properties. We propose that the glycine, oriented subparticles, exchange and dipole-dipole interactions may play an important role in the development of magnetic properties.",
journal = "Applied Surface Science",
title = "Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures",
volume = "457",
pages = "427-438",
doi = "10.1016/j.apsusc.2018.06.224"
}

Trpkov, Đ., Panjan, M., Kopanja, L.,& Tadić, M.. (2018). Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures. in Applied Surface Science, 457, 427-438.
https://doi.org/10.1016/j.apsusc.2018.06.224

Trpkov Đ, Panjan M, Kopanja L, Tadić M. Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures. in Applied Surface Science. 2018;457:427-438.
doi:10.1016/j.apsusc.2018.06.224 .

Trpkov, Đorđe, Panjan, Matjaž, Kopanja, Lazar, Tadić, Marin, "Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures" in Applied Surface Science, 457 (2018):427-438,
https://doi.org/10.1016/j.apsusc.2018.06.224 . .

TY  - JOUR
AU  - Kopanja, Lazar
AU  - Tadić, Marin
AU  - Kralj, Slavko
AU  - Žunić, Joviša
PY  - 2018
UR  - https://linkinghub.elsevier.com/retrieve/pii/S0272884218308812
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7917
AB  - Due to advances in electron microscopy and to the development of novel nanoparticle structures with different morphologies and the dependence of physical properties on the nanoparticle morphology, there is a need for a more precise analysis of nanoparticle structure and morphology. That should provide a simple and unambiguous comparison of nanoparticles' shapes and of material properties that depend on the shape, which has been lacking thus far. Here we study nanochains consisting of silica-coated iron oxide (maghemite, gamma-Fe2O3) nanoparticle clusters covered by an additional layer of silica (core-shell structure). We have developed an algorithm for image segmentation and a quantitative analysis of nanochain shape from real TEM images. To that end we used two distinct measures of circularity and elongation measure (the aspect ratio measure). We show that the relative position and the area of the links, as well as the links' shape lead to significant differences in the measured aspect ratio of the entire nanochain (substantially influence the elongation of nanochains). We have also analyzed the core-shell structures in nanochains, and computed the shell's share in the overall area of observed nanochains. A Matlab code was developed and used for the computation of the elongation measure of shapes appearing in electron microscopy images. Here we have investigated magnetic properties of synthetic nanochains, that revealed superparamagnetic behavior at room temperature (SPION) with the possibility of tuning the magnetization values (approx. from 19 to 46 emu/g). We have compared of magnetization M(H) curves of the anisotropic nanochains and of isotropic nanoparticle (nanochain links), with the conclusion that the nanochains have a higher magnetic susceptibility, which fact can be understood as a consequence of their anisotropic shapes. The nanochains may be applied in biomedicine and magnetic separation, due to their morphology and magnetic properties.
T2  - Ceramics International
T1  - Shape and aspect ratio analysis of anisotropic magnetic nanochains based on TEM micrographs
VL  - 44
IS  - 11
SP  - 12340
EP  - 12351
DO  - 10.1016/j.ceramint.2018.04.021
ER  - 

@article{
author = "Kopanja, Lazar and Tadić, Marin and Kralj, Slavko and Žunić, Joviša",
year = "2018",
abstract = "Due to advances in electron microscopy and to the development of novel nanoparticle structures with different morphologies and the dependence of physical properties on the nanoparticle morphology, there is a need for a more precise analysis of nanoparticle structure and morphology. That should provide a simple and unambiguous comparison of nanoparticles' shapes and of material properties that depend on the shape, which has been lacking thus far. Here we study nanochains consisting of silica-coated iron oxide (maghemite, gamma-Fe2O3) nanoparticle clusters covered by an additional layer of silica (core-shell structure). We have developed an algorithm for image segmentation and a quantitative analysis of nanochain shape from real TEM images. To that end we used two distinct measures of circularity and elongation measure (the aspect ratio measure). We show that the relative position and the area of the links, as well as the links' shape lead to significant differences in the measured aspect ratio of the entire nanochain (substantially influence the elongation of nanochains). We have also analyzed the core-shell structures in nanochains, and computed the shell's share in the overall area of observed nanochains. A Matlab code was developed and used for the computation of the elongation measure of shapes appearing in electron microscopy images. Here we have investigated magnetic properties of synthetic nanochains, that revealed superparamagnetic behavior at room temperature (SPION) with the possibility of tuning the magnetization values (approx. from 19 to 46 emu/g). We have compared of magnetization M(H) curves of the anisotropic nanochains and of isotropic nanoparticle (nanochain links), with the conclusion that the nanochains have a higher magnetic susceptibility, which fact can be understood as a consequence of their anisotropic shapes. The nanochains may be applied in biomedicine and magnetic separation, due to their morphology and magnetic properties.",
journal = "Ceramics International",
title = "Shape and aspect ratio analysis of anisotropic magnetic nanochains based on TEM micrographs",
volume = "44",
number = "11",
pages = "12340-12351",
doi = "10.1016/j.ceramint.2018.04.021"
}

Kopanja, L., Tadić, M., Kralj, S.,& Žunić, J.. (2018). Shape and aspect ratio analysis of anisotropic magnetic nanochains based on TEM micrographs. in Ceramics International, 44(11), 12340-12351.
https://doi.org/10.1016/j.ceramint.2018.04.021

Kopanja L, Tadić M, Kralj S, Žunić J. Shape and aspect ratio analysis of anisotropic magnetic nanochains based on TEM micrographs. in Ceramics International. 2018;44(11):12340-12351.
doi:10.1016/j.ceramint.2018.04.021 .

Kopanja, Lazar, Tadić, Marin, Kralj, Slavko, Žunić, Joviša, "Shape and aspect ratio analysis of anisotropic magnetic nanochains based on TEM micrographs" in Ceramics International, 44, no. 11 (2018):12340-12351,
https://doi.org/10.1016/j.ceramint.2018.04.021 . .

TY  - JOUR
AU  - Kopanja, Lazar
AU  - Kovačević, Zorana
AU  - Tadić, Marin
AU  - Žužek, Monika Cecilija
AU  - Vrecl, Milka
AU  - Frangež, Robert
PY  - 2018
UR  - http://link.springer.com/10.1007/s00418-018-1670-0
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7762
AB  - Detailed shape analysis of cells is important to better understand the physiological mechanisms of toxins and determine their effects on cell morphology. This study aimed to develop a procedure for accurate morphological analysis of cell shape and use it as a tool to estimate toxin activity. With the aim of optimizing the method of cell morphology analysis, we determined the influence of ostreolysin A and pleurotolysin B complex (OlyA/PlyB) on the morphology of murine neuronal NG108-15 cells. A computational method was introduced and successfully applied to quantify morphological attributes of the NG108-15 cell line before and after 30 and 60 min exposure to OlyA/PlyB using confocal microscopy. The modified circularity measure (Formula presented.) for shape analysis was applied, which defines the degree to which the shape of the neuron differs from a perfect circle. It enables better detection of small changes in the shape of cells, making the outcome easily detectable numerically. Additionally, we analyzed the influence of OlyA/PlyB on the cell area, allowing us to detect the cells with blebs. This is important because the formation of plasma membrane protrusions such as blebs often reflects cell injury that leads to necrotic cell death. In summary, we offer a novel analytical method of neuronal cell shape analysis and its correlation with the toxic effects of the pore-forming OlyA/PlyB toxin in situ.
T2  - Histochemistry and Cell Biology
T1  - Confocal micrographs: automated segmentation and quantitative shape analysis of neuronal cells treated with ostreolysin A/pleurotolysin B pore-forming complex
VL  - 150
IS  - 1
SP  - 93
EP  - 102
DO  - 10.1007/s00418-018-1670-0
ER  - 

@article{
author = "Kopanja, Lazar and Kovačević, Zorana and Tadić, Marin and Žužek, Monika Cecilija and Vrecl, Milka and Frangež, Robert",
year = "2018",
abstract = "Detailed shape analysis of cells is important to better understand the physiological mechanisms of toxins and determine their effects on cell morphology. This study aimed to develop a procedure for accurate morphological analysis of cell shape and use it as a tool to estimate toxin activity. With the aim of optimizing the method of cell morphology analysis, we determined the influence of ostreolysin A and pleurotolysin B complex (OlyA/PlyB) on the morphology of murine neuronal NG108-15 cells. A computational method was introduced and successfully applied to quantify morphological attributes of the NG108-15 cell line before and after 30 and 60 min exposure to OlyA/PlyB using confocal microscopy. The modified circularity measure (Formula presented.) for shape analysis was applied, which defines the degree to which the shape of the neuron differs from a perfect circle. It enables better detection of small changes in the shape of cells, making the outcome easily detectable numerically. Additionally, we analyzed the influence of OlyA/PlyB on the cell area, allowing us to detect the cells with blebs. This is important because the formation of plasma membrane protrusions such as blebs often reflects cell injury that leads to necrotic cell death. In summary, we offer a novel analytical method of neuronal cell shape analysis and its correlation with the toxic effects of the pore-forming OlyA/PlyB toxin in situ.",
journal = "Histochemistry and Cell Biology",
title = "Confocal micrographs: automated segmentation and quantitative shape analysis of neuronal cells treated with ostreolysin A/pleurotolysin B pore-forming complex",
volume = "150",
number = "1",
pages = "93-102",
doi = "10.1007/s00418-018-1670-0"
}

Kopanja, L., Kovačević, Z., Tadić, M., Žužek, M. C., Vrecl, M.,& Frangež, R.. (2018). Confocal micrographs: automated segmentation and quantitative shape analysis of neuronal cells treated with ostreolysin A/pleurotolysin B pore-forming complex. in Histochemistry and Cell Biology, 150(1), 93-102.
https://doi.org/10.1007/s00418-018-1670-0

Kopanja L, Kovačević Z, Tadić M, Žužek MC, Vrecl M, Frangež R. Confocal micrographs: automated segmentation and quantitative shape analysis of neuronal cells treated with ostreolysin A/pleurotolysin B pore-forming complex. in Histochemistry and Cell Biology. 2018;150(1):93-102.
doi:10.1007/s00418-018-1670-0 .

Kopanja, Lazar, Kovačević, Zorana, Tadić, Marin, Žužek, Monika Cecilija, Vrecl, Milka, Frangež, Robert, "Confocal micrographs: automated segmentation and quantitative shape analysis of neuronal cells treated with ostreolysin A/pleurotolysin B pore-forming complex" in Histochemistry and Cell Biology, 150, no. 1 (2018):93-102,
https://doi.org/10.1007/s00418-018-1670-0 . .

TY  - JOUR
AU  - Nikolić, Violeta N.
AU  - Spasojević, Vojislav
AU  - Panjan, Matjaž
AU  - Kopanja, Lazar
AU  - Mraković, Ana Đ.
AU  - Tadić, Marin
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1559
AB  - Several Fe2O3/SiO2 nanostructures were synthesized by the combination of the microemulsion and a sol-gel methods. Based on X-ray powder diffraction (XRD) and magnetic measurements (giant coercivity similar to 2.13 T) we identified epsilon-Fe2O3 (hard magnet) as the dominant crystalline phase. TEM analysis showed a wide size distribution of iron oxide nanoparticles (from 4 to 50 nm) with various morphologies (spherical, ellipsoidal and rod-like). We quantitatively described (computational analysis, MATLAB code) morphological properties of nanoparticles using the ellipticity of the shapes. The as-synthesized hard magnetic material was subjected to a post-annealing treatment at different temperatures (200, 500, 750, 1000 and 1100 degrees C) in order to investigate stability, formation and transformation of the epsilon-Fe2O3 polymorph. We found decreasing coercivity in the thermally treated samples up to the temperature of 750 degrees C (H-c=1245 Oe), followed by an observation of a surprising jump in coercivity H-c similar to 1.5 T after post-annealing at 1000 degrees C. We conclude that the re-formation of the epsilon-Fe2O3 structure during post-annealing at 1000 degrees C is the origin of the observed phenomena. The phase transformation epsilon-Fe2O3 - GT alpha-Fe2O3 and crystallization of amorphous silica in quartz and cristobalite were observed in the sample treated at 1100 degrees C.
T2  - Ceramics International
T1  - Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties
VL  - 43
IS  - 10
SP  - 7497
EP  - 7507
DO  - 10.1016/j.ceramint.2017.03.030
ER  - 

@article{
author = "Nikolić, Violeta N. and Spasojević, Vojislav and Panjan, Matjaž and Kopanja, Lazar and Mraković, Ana Đ. and Tadić, Marin",
year = "2017",
abstract = "Several Fe2O3/SiO2 nanostructures were synthesized by the combination of the microemulsion and a sol-gel methods. Based on X-ray powder diffraction (XRD) and magnetic measurements (giant coercivity similar to 2.13 T) we identified epsilon-Fe2O3 (hard magnet) as the dominant crystalline phase. TEM analysis showed a wide size distribution of iron oxide nanoparticles (from 4 to 50 nm) with various morphologies (spherical, ellipsoidal and rod-like). We quantitatively described (computational analysis, MATLAB code) morphological properties of nanoparticles using the ellipticity of the shapes. The as-synthesized hard magnetic material was subjected to a post-annealing treatment at different temperatures (200, 500, 750, 1000 and 1100 degrees C) in order to investigate stability, formation and transformation of the epsilon-Fe2O3 polymorph. We found decreasing coercivity in the thermally treated samples up to the temperature of 750 degrees C (H-c=1245 Oe), followed by an observation of a surprising jump in coercivity H-c similar to 1.5 T after post-annealing at 1000 degrees C. We conclude that the re-formation of the epsilon-Fe2O3 structure during post-annealing at 1000 degrees C is the origin of the observed phenomena. The phase transformation epsilon-Fe2O3 - GT alpha-Fe2O3 and crystallization of amorphous silica in quartz and cristobalite were observed in the sample treated at 1100 degrees C.",
journal = "Ceramics International",
title = "Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties",
volume = "43",
number = "10",
pages = "7497-7507",
doi = "10.1016/j.ceramint.2017.03.030"
}

Nikolić, V. N., Spasojević, V., Panjan, M., Kopanja, L., Mraković, A. Đ.,& Tadić, M.. (2017). Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties. in Ceramics International, 43(10), 7497-7507.
https://doi.org/10.1016/j.ceramint.2017.03.030

Nikolić VN, Spasojević V, Panjan M, Kopanja L, Mraković AĐ, Tadić M. Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties. in Ceramics International. 2017;43(10):7497-7507.
doi:10.1016/j.ceramint.2017.03.030 .

Nikolić, Violeta N., Spasojević, Vojislav, Panjan, Matjaž, Kopanja, Lazar, Mraković, Ana Đ., Tadić, Marin, "Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties" in Ceramics International, 43, no. 10 (2017):7497-7507,
https://doi.org/10.1016/j.ceramint.2017.03.030 . .

TY  - JOUR
AU  - Tadić, Marin
AU  - Kopanja, Lazar
AU  - Panjan, Matjaž
AU  - Kralj, Slavko
AU  - Nikodinović-Runić, Jasmina
AU  - Stojanović, Zoran S.
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1449
AB  - Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase alpha-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10-20 nm thickness, 80-100 nm landscape dimensions (aspect ratio 5) and 3-4 nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core-shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity H-C = 2340 Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications. (C) 2017 Elsevier B.V. All rights reserved.
T2  - Applied Surface Science
T1  - Synthesis of core-shell hematite (alpha-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity
VL  - 403
SP  - 628
EP  - 634
DO  - 10.1016/j.apsusc.2017.01.115
ER  - 

@article{
author = "Tadić, Marin and Kopanja, Lazar and Panjan, Matjaž and Kralj, Slavko and Nikodinović-Runić, Jasmina and Stojanović, Zoran S.",
year = "2017",
abstract = "Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase alpha-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10-20 nm thickness, 80-100 nm landscape dimensions (aspect ratio 5) and 3-4 nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core-shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity H-C = 2340 Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications. (C) 2017 Elsevier B.V. All rights reserved.",
journal = "Applied Surface Science",
title = "Synthesis of core-shell hematite (alpha-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity",
volume = "403",
pages = "628-634",
doi = "10.1016/j.apsusc.2017.01.115"
}

Tadić, M., Kopanja, L., Panjan, M., Kralj, S., Nikodinović-Runić, J.,& Stojanović, Z. S.. (2017). Synthesis of core-shell hematite (alpha-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity. in Applied Surface Science, 403, 628-634.
https://doi.org/10.1016/j.apsusc.2017.01.115

Tadić M, Kopanja L, Panjan M, Kralj S, Nikodinović-Runić J, Stojanović ZS. Synthesis of core-shell hematite (alpha-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity. in Applied Surface Science. 2017;403:628-634.
doi:10.1016/j.apsusc.2017.01.115 .

Tadić, Marin, Kopanja, Lazar, Panjan, Matjaž, Kralj, Slavko, Nikodinović-Runić, Jasmina, Stojanović, Zoran S., "Synthesis of core-shell hematite (alpha-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity" in Applied Surface Science, 403 (2017):628-634,
https://doi.org/10.1016/j.apsusc.2017.01.115 . .

TY  - JOUR
AU  - Nikolić, Violeta N.
AU  - Tadić, Marin
AU  - Panjan, Matjaž
AU  - Kopanja, Lazar
AU  - Cvjetićanin, Nikola
AU  - Spasojević, Vojislav
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1400
AB  - Magnetic properties of Fe2O3/SiO2 samples were studied after being produced by sol-gel synthesis and formation of epsilon-Fe2O3 polymorph. Samples were thermally treated, using different annealing temperatures and annealing times. The size and morphological characteristics of the iron oxide nanoparticles were examined using a TEM microscope. We used the ellipticity of shapes, which is a measure of how much the shape of a nanoparticle differs from a perfect ellipse, in order to quantitatively describe morphological properties of nanoparticles. Coercivity measurements were used to identify and monitor the formation of the epsilon-iron oxide phase during the thermal treatments (annealing). Coercivity values were in the range from 1.2 to 15.4 kOe, which is in accordance with previous experience regarding the existence of epsilon-Fe2O3. We have determined the optimal formation conditions for the epsilon-Fe2O3 polymorph (t=1050 degrees C for 7 h, H-c=15.4 kOe), as well as the narrow temperature interval (1050-1060 C) in which the polymorph abruptly vanished (H-c=2300 Oe), on the basis of results of the magnetic properties. The threshold temperature for the epsilon-Fe2O3 phase transformation was measured as 1060 degrees C. We found that different annealing temperatures and annealing times significantly affected magnetic properties of the examined samples.
T2  - Ceramics International
T1  - Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase
VL  - 43
IS  - 3
SP  - 3147
EP  - 3155
DO  - 10.1016/j.ceramint.2016.11.132
ER  - 

@article{
author = "Nikolić, Violeta N. and Tadić, Marin and Panjan, Matjaž and Kopanja, Lazar and Cvjetićanin, Nikola and Spasojević, Vojislav",
year = "2017",
abstract = "Magnetic properties of Fe2O3/SiO2 samples were studied after being produced by sol-gel synthesis and formation of epsilon-Fe2O3 polymorph. Samples were thermally treated, using different annealing temperatures and annealing times. The size and morphological characteristics of the iron oxide nanoparticles were examined using a TEM microscope. We used the ellipticity of shapes, which is a measure of how much the shape of a nanoparticle differs from a perfect ellipse, in order to quantitatively describe morphological properties of nanoparticles. Coercivity measurements were used to identify and monitor the formation of the epsilon-iron oxide phase during the thermal treatments (annealing). Coercivity values were in the range from 1.2 to 15.4 kOe, which is in accordance with previous experience regarding the existence of epsilon-Fe2O3. We have determined the optimal formation conditions for the epsilon-Fe2O3 polymorph (t=1050 degrees C for 7 h, H-c=15.4 kOe), as well as the narrow temperature interval (1050-1060 C) in which the polymorph abruptly vanished (H-c=2300 Oe), on the basis of results of the magnetic properties. The threshold temperature for the epsilon-Fe2O3 phase transformation was measured as 1060 degrees C. We found that different annealing temperatures and annealing times significantly affected magnetic properties of the examined samples.",
journal = "Ceramics International",
title = "Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase",
volume = "43",
number = "3",
pages = "3147-3155",
doi = "10.1016/j.ceramint.2016.11.132"
}

Nikolić, V. N., Tadić, M., Panjan, M., Kopanja, L., Cvjetićanin, N.,& Spasojević, V.. (2017). Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase. in Ceramics International, 43(3), 3147-3155.
https://doi.org/10.1016/j.ceramint.2016.11.132

Nikolić VN, Tadić M, Panjan M, Kopanja L, Cvjetićanin N, Spasojević V. Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase. in Ceramics International. 2017;43(3):3147-3155.
doi:10.1016/j.ceramint.2016.11.132 .

Nikolić, Violeta N., Tadić, Marin, Panjan, Matjaž, Kopanja, Lazar, Cvjetićanin, Nikola, Spasojević, Vojislav, "Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase" in Ceramics International, 43, no. 3 (2017):3147-3155,
https://doi.org/10.1016/j.ceramint.2016.11.132 . .

TY  - JOUR
AU  - Kopanja, Lazar
AU  - Kralj, Slavko
AU  - Žunić, Dragiša
AU  - Lončar, Boris B.
AU  - Tadić, Marin
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1089
AB  - For the first time, particle shape analysis of silica coated iron oxide (maghemite/magnetite) nanoparticle clusters (core-shell nanostructures) is discussed using computational methods. We analyzed three samples of core-shell nanostructures synthesized with different thickness of the silica shell. A new computational method is presented and successfully applied to the segmentation of the core-shell nanoparticles, as one of the main problems in image analysis of the TEM micrographs. We have introduced the circularity coefficient, marked with k(circ) and defined as the ratio of circularity measure C-2(S) of nanoparticles core and circularity measure core-shell nanoparticles in order to answer the question how the shell affects the overall shape of the final core-shell structure, with respect to circularity. More precisely, the circularity coefficient determines whether the circularity of the core-shell nanoparticle is higher, lower or equal to the circularity of the core. We have also determined the shells share in the overall area of the core-shell nanoparticle. The core-shell nanoparticle clusters here investigated exhibit superparamagnetic properties at room temperature, thus emphasizing their potential for use in practical applications such as in biomedical and particle separation. We show that the saturation magnetization strength can be easily adjusted by controlling the thickness of the silica shell. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
PB  - Elsevier
T2  - Ceramics International
T1  - Core-shell superparamagnetic iron oxide nanoparticle (SPION) clusters: TEM micrograph analysis, particle design and shape analysis
VL  - 42
IS  - 9
SP  - 10976
EP  - 10984
DO  - 10.1016/j.ceramint.2016.03.235
ER  - 

@article{
author = "Kopanja, Lazar and Kralj, Slavko and Žunić, Dragiša and Lončar, Boris B. and Tadić, Marin",
year = "2016",
abstract = "For the first time, particle shape analysis of silica coated iron oxide (maghemite/magnetite) nanoparticle clusters (core-shell nanostructures) is discussed using computational methods. We analyzed three samples of core-shell nanostructures synthesized with different thickness of the silica shell. A new computational method is presented and successfully applied to the segmentation of the core-shell nanoparticles, as one of the main problems in image analysis of the TEM micrographs. We have introduced the circularity coefficient, marked with k(circ) and defined as the ratio of circularity measure C-2(S) of nanoparticles core and circularity measure core-shell nanoparticles in order to answer the question how the shell affects the overall shape of the final core-shell structure, with respect to circularity. More precisely, the circularity coefficient determines whether the circularity of the core-shell nanoparticle is higher, lower or equal to the circularity of the core. We have also determined the shells share in the overall area of the core-shell nanoparticle. The core-shell nanoparticle clusters here investigated exhibit superparamagnetic properties at room temperature, thus emphasizing their potential for use in practical applications such as in biomedical and particle separation. We show that the saturation magnetization strength can be easily adjusted by controlling the thickness of the silica shell. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.",
publisher = "Elsevier",
journal = "Ceramics International",
title = "Core-shell superparamagnetic iron oxide nanoparticle (SPION) clusters: TEM micrograph analysis, particle design and shape analysis",
volume = "42",
number = "9",
pages = "10976-10984",
doi = "10.1016/j.ceramint.2016.03.235"
}

Kopanja, L., Kralj, S., Žunić, D., Lončar, B. B.,& Tadić, M.. (2016). Core-shell superparamagnetic iron oxide nanoparticle (SPION) clusters: TEM micrograph analysis, particle design and shape analysis. in Ceramics International
Elsevier., 42(9), 10976-10984.
https://doi.org/10.1016/j.ceramint.2016.03.235

Kopanja L, Kralj S, Žunić D, Lončar BB, Tadić M. Core-shell superparamagnetic iron oxide nanoparticle (SPION) clusters: TEM micrograph analysis, particle design and shape analysis. in Ceramics International. 2016;42(9):10976-10984.
doi:10.1016/j.ceramint.2016.03.235 .

Kopanja, Lazar, Kralj, Slavko, Žunić, Dragiša, Lončar, Boris B., Tadić, Marin, "Core-shell superparamagnetic iron oxide nanoparticle (SPION) clusters: TEM micrograph analysis, particle design and shape analysis" in Ceramics International, 42, no. 9 (2016):10976-10984,
https://doi.org/10.1016/j.ceramint.2016.03.235 . .

TY  - JOUR
AU  - Kopanja, Lazar
AU  - Milošević, Irena
AU  - Panjan, Matjaž
AU  - Damnjanović, Vesna
AU  - Tadić, Marin
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/901
AB  - We report the synthesis and magnetic properties of hematite/amorphous silica nanostructures. Raman spectroscopy showed the formation of a hematite phase. A transmission electron microscopy (TEM) revealed spherically shaped hematite nanoparticles, well-dispersed in an amorphous silica matrix. In order to quantitatively describe morphological properties of nanoparticles, we use the circularity of shapes as a measure of how circular a shape is. Diameters of about 5 nm and a narrow size distribution of nanoparticles are observed. The obtained hematite nanoparticles exhibit superparamagnetic properties at room temperature (SPION). The sample does not display the Morin transition. The FC hysteresis loop at 5 K has shown an exchange bias effect. These results have been compared to those previously reported for alpha-Fe2O3/SiO2 nanosystems in the literature. These comparisons reveal that the sol-gel combustion method yields hematite nanoparticles with a higher magnetization and magnetic moment. These data indicate the existence of an additional factor that contributes to magnetization. We suggest that the increased magnetization is due to an increased number of the surface spins caused by the breaking of large numbers of exchange bonds between surface atoms (disordered structure). This leads to an increase in the magnetic moment per a hematite nanoparticle and an exchange bias effect. We have concluded that the combustion-related part of this synthesis method enhances surface effects, i.e. it promotes the breaking of bonds and surface disordered layers, which results in these magnetic properties. Such interesting structural and magnetic properties of hematite might be important in future practical applications and fundamental research. (C) 2015 Elsevier B.V. All rights reserved.
PB  - Elsevier
T2  - Applied Surface Science
T1  - Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix
VL  - 362
SP  - 380
EP  - 386
DO  - 10.1016/j.apsusc.2015.11.238
ER  - 

@article{
author = "Kopanja, Lazar and Milošević, Irena and Panjan, Matjaž and Damnjanović, Vesna and Tadić, Marin",
year = "2016",
abstract = "We report the synthesis and magnetic properties of hematite/amorphous silica nanostructures. Raman spectroscopy showed the formation of a hematite phase. A transmission electron microscopy (TEM) revealed spherically shaped hematite nanoparticles, well-dispersed in an amorphous silica matrix. In order to quantitatively describe morphological properties of nanoparticles, we use the circularity of shapes as a measure of how circular a shape is. Diameters of about 5 nm and a narrow size distribution of nanoparticles are observed. The obtained hematite nanoparticles exhibit superparamagnetic properties at room temperature (SPION). The sample does not display the Morin transition. The FC hysteresis loop at 5 K has shown an exchange bias effect. These results have been compared to those previously reported for alpha-Fe2O3/SiO2 nanosystems in the literature. These comparisons reveal that the sol-gel combustion method yields hematite nanoparticles with a higher magnetization and magnetic moment. These data indicate the existence of an additional factor that contributes to magnetization. We suggest that the increased magnetization is due to an increased number of the surface spins caused by the breaking of large numbers of exchange bonds between surface atoms (disordered structure). This leads to an increase in the magnetic moment per a hematite nanoparticle and an exchange bias effect. We have concluded that the combustion-related part of this synthesis method enhances surface effects, i.e. it promotes the breaking of bonds and surface disordered layers, which results in these magnetic properties. Such interesting structural and magnetic properties of hematite might be important in future practical applications and fundamental research. (C) 2015 Elsevier B.V. All rights reserved.",
publisher = "Elsevier",
journal = "Applied Surface Science",
title = "Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix",
volume = "362",
pages = "380-386",
doi = "10.1016/j.apsusc.2015.11.238"
}

Kopanja, L., Milošević, I., Panjan, M., Damnjanović, V.,& Tadić, M.. (2016). Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix. in Applied Surface Science
Elsevier., 362, 380-386.
https://doi.org/10.1016/j.apsusc.2015.11.238

Kopanja L, Milošević I, Panjan M, Damnjanović V, Tadić M. Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix. in Applied Surface Science. 2016;362:380-386.
doi:10.1016/j.apsusc.2015.11.238 .

Kopanja, Lazar, Milošević, Irena, Panjan, Matjaž, Damnjanović, Vesna, Tadić, Marin, "Sol-gel combustion synthesis, particle shape analysis and magnetic properties of hematite (alpha-Fe2O3) nanoparticles embedded in an amorphous silica matrix" in Applied Surface Science, 362 (2016):380-386,
https://doi.org/10.1016/j.apsusc.2015.11.238 . .

TY  - JOUR
AU  - Kopanja, Lazar
AU  - Žunić, Dragiša
AU  - Lončar, Boris B.
AU  - Gyergyek, Sašo
AU  - Tadić, Marin
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1198
AB  - We propose using a new circularity measure, and an ellipticity measure. Observing an example of hematite (alpha-Fe2O3) nanoparticles, we compared and discussed a new circularity measure, with a standard measure. It has been shown that using the new measure gives better results when working with low-quality images or with low-resolution images. Using the same images modified ellipticity measure has also been discussed. We have analyzed the problems arising from computing the elongation of a shape. We have shown that the standard approach to compute elongation is not appropriate for some particles. We presented the application of the modified approach to solve this problem. (C) 2016 Elsevier Ltd. All rights reserved.
T2  - Measurement
T1  - Quantifying shapes of nanoparticles using modified circularity and ellipticity measures
VL  - 92
SP  - 252
EP  - 263
DO  - 10.1016/j.measurement.2016.06.021
ER  - 

@article{
author = "Kopanja, Lazar and Žunić, Dragiša and Lončar, Boris B. and Gyergyek, Sašo and Tadić, Marin",
year = "2016",
abstract = "We propose using a new circularity measure, and an ellipticity measure. Observing an example of hematite (alpha-Fe2O3) nanoparticles, we compared and discussed a new circularity measure, with a standard measure. It has been shown that using the new measure gives better results when working with low-quality images or with low-resolution images. Using the same images modified ellipticity measure has also been discussed. We have analyzed the problems arising from computing the elongation of a shape. We have shown that the standard approach to compute elongation is not appropriate for some particles. We presented the application of the modified approach to solve this problem. (C) 2016 Elsevier Ltd. All rights reserved.",
journal = "Measurement",
title = "Quantifying shapes of nanoparticles using modified circularity and ellipticity measures",
volume = "92",
pages = "252-263",
doi = "10.1016/j.measurement.2016.06.021"
}

Kopanja, L., Žunić, D., Lončar, B. B., Gyergyek, S.,& Tadić, M.. (2016). Quantifying shapes of nanoparticles using modified circularity and ellipticity measures. in Measurement, 92, 252-263.
https://doi.org/10.1016/j.measurement.2016.06.021

Kopanja L, Žunić D, Lončar BB, Gyergyek S, Tadić M. Quantifying shapes of nanoparticles using modified circularity and ellipticity measures. in Measurement. 2016;92:252-263.
doi:10.1016/j.measurement.2016.06.021 .

Kopanja, Lazar, Žunić, Dragiša, Lončar, Boris B., Gyergyek, Sašo, Tadić, Marin, "Quantifying shapes of nanoparticles using modified circularity and ellipticity measures" in Measurement, 92 (2016):252-263,
https://doi.org/10.1016/j.measurement.2016.06.021 . .