Nanochemistry and Materials : a Laboratory ManualJanja Stergar
, Irena Ban
, 2022, delovni zvezek za višje in visoke šole
Opis: The publication contains instructions for laboratory work in the subject Nanochemistry and Materials. Students are introduced to the experimental principles of nanochemistry in the laboratory. They learn about various synthesis and characterization methods, in conjunction with magnetic nanoparticles useful in biomedical and engineering applications. They learn about the safety of nanoparticles and their effects, impact on technology, and contribution to improving life on many levels when used properly. The instructions are written in English as they are intended for foreign students who choose the mentioned subject.
Ključne besede: magnetic nanoparticles, coprecipitation, microemulsion technique, X-Ray powder diffraction, dynamic light scattering
Objavljeno v DKUM: 29.08.2022; Ogledov: 186; Prenosov: 23
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Removal of neodymium ions from aqueous solution by magnetic nanoparticles : magistrsko deloAna Ambrož
, 2021, magistrsko delo
Opis: This work is focused on the synthesis and characterization of surface-functionalized
γ-Fe2O3-NH4OH@SiO2(APTMS) nanoparticles, their applications, and performance for Nd3+ removal from aqueous solutions, with an emphasis on the characterization of MNPs and Nd(NO3)3•6H2O.
The γ-Fe2O3 nanoparticles were obtained by the co-precipitation method, stabilized with ammonia solution, and functionalized by SiO2 and APTMS. Neodymium nitrate hexahydrate (Nd(NO3)3•6H2O) used in aqueous solution was synthesised from neodymium oxide (Nd2O3) powder. The thermal behaviour and stability of the magnetic nanoparticles and Nd(NO3)3•6H2O was studied with thermogravimetric analysis (TGA) in O2, N2, and air atmosphere. Transmission electron microscopy (TEM) images were obtained in order to analyse the particle morphology and measure the size distribution of the nanoparticles. The hydrodynamic diameter of particles and the zeta potential were measured to determine the stability of particles in the solution. ATR-FTIR spectroscopy was used to confirm the functionalization of the magnetic nanoparticles and the adsorption of Nd3+ ions. The effect of the REE adsorption on the MNPs was studied by comparing the sample’s UV-Vis absorption spectra.
The laboratory testing and analysis of the results indicate promising applications for the removal of the REE from aqueous solutions with magnetic nanoparticles. However, the coating of the MNP core by SiO2(APTMS) is inefficient for the removal of Nd3+ ions.
Ključne besede: Magnetic nanoparticles, Rare earth elements, Neodymium, Adsorption, Zeta potential, UV-Vis spectroscopy
Objavljeno v DKUM: 03.05.2021; Ogledov: 768; Prenosov: 137
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Functionalisation of silicone by drug-embedded chitosan nanoparticles for potential applications in otorhinolaryngologyUrban Ajdnik
, Lidija Fras Zemljič
, Matej Bračič
, Uroš Maver
, Olivija Plohl
, Janez Rebol
, 2019, izvirni znanstveni članek
Ključne besede: silicone, tympanostomy tube, chitosan, nanoparticles, drug delivery, antimicrobial activity
Objavljeno v DKUM: 22.03.2019; Ogledov: 868; Prenosov: 6
Functionalized copolymers from macrolactones by enzymatic ring-opening polymerizationMaja Ivanovski
, 2018, magistrsko delo
Opis: The work reported in the present thesis is focused predominantly to investigate how to synthesize random copolymers from ω-pentadecalatone (ω-PDL) and globalide (Gl) by enzymatic ring-opening polymerization (eROP). The reason for choosing this specific theme, i.e. "Functionalized copolymers from macrolactones by enzymatic ring-opening polymerization", was to explore a relatively new concept, in which two cyclic esters (macrolactones) – ω-PDL and Gl were synthesized by a combination of eROP and thiol-ene click reaction using biocatalyst Novozym 435 (lipase B from Candida antarctica). The aim was to position the newborn copolymer from ω-pentadecalactone and globalide among other biomaterials, identify possible applications and prepare nanoparticles that can be used in drug delivery systems.
Random copolymers PPDLx-r-PGly with different feed ratios were successfully synthesized and later modified via thiol-ene click reaction when using BAET as a suitable compound for this polymeric functionalization, due to its thiol functionality. Boc-amino deprotection lasted and at the end, graft-copolymers were obtained (PPDLx-r-(PGly-g-PBLGz).
Characterization methods were performed on GPC and NMR. The yield for all obtained random copolymers ranged between 67% and 88% and Mn between 14 000 g/mol and 45 000 g/mol depending on feed ratio of random copolymers. Meanwhile, the calculated yield for obtained grafted-copolymers ranged between 63% and 95%. Mn detected by GPC was around 7 000 g/mol for both grafted-copolymers (PPDL90(PGl10-PBLGz) and PPDL50(PGl50-PBLGz)) and Mw between 14 000 g/mol and 21 000 g/mol. Thermal analyses were performed on TGA and DSC. TGA showed that obtained PPDLx-r-PGly copolymers start to decompose at around 400 °C and grafted PPDLx-r-(PGly-g-PBLGz) copolymers at around 250 °C. DSC showed that PPDL and PGl are semicrystalline polymers with Tm ranging between (95 and 96 °C) for PPDL and (41 and 42 °C) for PGl.
AFM technique was used for nanoparticles characterization. The resulting surface and deep resolution of PPDL50(PGl50-PBLGz) nanoparticles was between (2 to 88.8 nm) and PPDL10(PGl90-PBLGz) between (2 nm to 94.4 nm).
Ključne besede: ring-opening polymerization, macrolactones, ω-pentadecalatone, globalide, nanoparticles, Novozym 435
Objavljeno v DKUM: 04.10.2018; Ogledov: 917; Prenosov: 226
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Impact of curvature on nematic topological defectsLuka Mesarec
, 2018, doktorska disertacija
Opis: Topological defects (TDs) appear almost unavoidably in continuous symmetry breaking phase transitions. The topological origin makes their key features independent of systems' microscopic details; therefore TDs display many universalities. Because of their strong impact on numerous material properties and their significant role in several technological applications it is of strong interest to find simple and robust mechanisms controlling the positioning and local number of TDs. There are strong evidences that in physics the fields are fundamental entities of nature and not particles. If this is the case then topological defects (TDs) might play the role of fundamental particles. An adequate testing ground to study and gain fundamental understanding of TDs are nematic liquid crystals. We present a numerical study of TDs within effectively two dimensional closed soft films exhibiting in-plane orientational ordering. Popular examples of such class of systems are liquid crystalline shells and various biological membranes.
We analyze the impact of extrinsic and intrinsic curvature on positions of topological defects (TDs) in two-dimensional (2D) nematic films. We demonstrate that both these curvature contributions are commonly present and are expected to be weighted by comparable elastic constants. A simple Landau-de Gennes approach in terms of tensor nematic order parameter is used to numerically demonstrate impact of the curvatures on position of TDs on 2D ellipsoidal nematic shells. We introduce the Effective Topological Charge Cancellation mechanism controlling localised positional assembling tendency of TDs and the formation of pairs (defect,antidefect) on curved surfaces. Furthermore, we estimate a critical depinning threshold to form pairs (defect,antidefect) using the electrostatic analogy. Finally, we show how one could efficiently switch among qualitatively different structures by using a relative volume of ordered shells, which represents a relatively simple naturally accessible control parameter.
In doctoral thesis, we developed theoretical model of erythrocyte membrane by using a hybrid Helfrich-Landau type mesoscopic approach, taking into account in-plane membrane ordering. We demonstrate that the derived extrinsic membrane energy term, which strongly depends on the local orientations of the molecules, is essential for the predicted broadening of the range of the relative volumes corresponding to the stable discocyte shapes, which is otherwise very narrow if only intrinsic curvature energy term dominates.
Ključne besede: Topological defects, Continuum fields, Nematic liquid crystals, Biological membranes, Nematic shells, Landau-de Gennes formalism, Topological charge, Nanoparticles, Gaussian curvature, Electrostatic analogy, Intrinsic curvature, Extrinsic curvature, Crystal growth nucleation, Relative
Objavljeno v DKUM: 09.03.2018; Ogledov: 1718; Prenosov: 134
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Synthesis of PMMA/ZnO nanoparticles composite used for resin teethDanica Popović
, Rajko Bobovnik
, Silvester Bolka
, Miroslav Vukadinovič
, Vojkan Lazić
, Rebeka Rudolf
, 2017, izvirni znanstveni članek
Opis: Wear resistance is one of the most important physical properties of the artificial teeth used in acrylic dentures. The goal of this research was to synthesize a new composite material made of matrix Poly-(methyl methacrylate)-PMMA with different percentages (2 % and 3 % of volume fractions) of zinc-oxide nanoparticles (ZnO NPs) as reinforcing elements, to improve its mechanical properties. The dynamic mechanical behaviour of this composite was studied through the DMA method in comparison to the pure PMMA supported by the characterization of their microstructures. Then the wear resistance was analysed on the samples, which were prepared in the form of teeth. In this context their vertical height loss was measured after 100,000 chewing cycles on a chewing simulator, before and after the artificial thermal ageing. Investigations showed that the PMMA/ZnO NP composites dampened the vibrations better than the pure PMMA, which could be assigned to the homogenous distribution of ZnO NPs in the PMMA matrix. It was found that the mean vertical height loss for the pure PMMA teeth was significantly higher (more than 4 times) compared to composite teeth made with ZnO NPs. Introducing the thermal artificial ageing led to the finding that there was no effect on the height loss by the composite material with 3 % of volume fractions of ZnO NPs. Based on this it was concluded that PMMA/ZnO NPs composites showed improved in-vitro wear resistance compared to acrylic-resin denture teeth, so this new composite material should be preferred when occlusal stability is considered to be of high priority.
Ključne besede: poly-methyl methacrylate, PMMA, zinc-oxide nanoparticles, composite, resin teeth
Objavljeno v DKUM: 12.12.2017; Ogledov: 1216; Prenosov: 409
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Nanotechnology in food safety and quality assessment : potentiality of nanoparticles in diagnosis of foodborne pathogensMaša Pintarič
, 2016, pregledni znanstveni članek
Opis: A rapid microbial detection in different biological and environmental material is a key of preventing several foodborne diseases. By implementing nanotechnology into food safety sector, a great step towards successful, reliable and sensible detection methods of foodborne pathogens has been achieved. Therefore, the aim of this review was to illustrate some of the principal functions of nanotechnology-based techniques, used for microbial detection in the last few years. Regarding consumer’s health, the review also discusses the question of safety, concerning human exposure to nanomaterials (NMs). Due to their different composition-unique properties, such as greater penetrability, reactivity and high surface to volume ratio, NMs have been coupled to several biomolecules and integrated in special system devices, resulting in improvement of sensitivity in transmitting biological signal informations in a shorter time. Among all the NMs, gold, magnetic and fluorescent nanoparticles (NPs) have been widely used, also in microbial diagnosis. Despite the success of linking nanotechnology to detection of foodborne pathogens, the exposure to various NMs could also be a matter of potential risk to human health, although conclusions still need to be definitely proven.
Ključne besede: nanotechnology, food safety, nanoparticles, diagnosis, foodborne pathogens
Objavljeno v DKUM: 14.11.2017; Ogledov: 1044; Prenosov: 159
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The magnetic and colloidal properties of $CoFe_2O_4$ nanoparticles synthesized by co-precipitationSašo Gyergyek
, Mihael Drofenik
, Darko Makovec
, 2014, izvirni znanstveni članek
Opis: Magnetic $CoFe_2O_4$ nanoparticles were synthesized by co-precipitation at 80 °C. This co-precipitation was achieved by the rapid addition of a strong base to an aqueous solution of cations. The investigation of the samples that were quenched at different times after the addition of the base, using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) and X-ray powder diffractometry, revealed the formation of a Co-deficient amorphous phase and $Co(OH)_2$, which rapidly reacted to form small $CoFe_2O_4$ nanoparticles. The nanoparticles grew with the time of aging at elevated temperature. The colloidal suspensions of the nanoparticles were prepared in both an aqueous medium and in a non-polar organic medium, with the adsorption of citric acid and ricinoleic acid on the nanoparticles, respectively. The measurements of the room-temperature magnetization revealed the ferrimagnetic state of the $CoFe_2O_4$ nanoparticles, while their suspensions displayed superparamagnetic behaviour.
Ključne besede: cobalt ferrite, nanoparticles, co-precipitation, colloidal suspensions, magnetic properties
Objavljeno v DKUM: 30.08.2017; Ogledov: 2314; Prenosov: 88
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Nanocomposite foams from iron oxide stabilized dicyclopentadiene high internal phase emulsions : preparation and brominationSebastijan Kovačič
, Christian Slugovc
, Gregor Ferk
, Nadejda B. Matsko
, 2014, strokovni članek
Opis: Nanocomposite polyHIPE foams with open-cellular morphology were obtained using nanoparticles ($γFe_2O_3/Fe_3O_4$), surfactant (Pluronic L121) or nanoparticle/surfactant stabilized dicyclopentadiene high internal phase emulsions (DCPD HIPEs). Upon curing, cavity sizes were found to vary drastically between 950 ± 360 µm down to 7 ±3 µm de- pending on the HIPE formulations. As-obtained nanocomposite polyHIPE foams were functionalized using elemental bromine in THF. Upon bromination the nanoparticles are moved from the cavities surfaces into the bulk phase of the polymer scaffold, which affects the inductive-heating capability of the magnetic nanocomposite foams decreasing it by the factor of 2.
Ključne besede: chemical technology, nanocomposites, bromination, microstructure, pickering HIPEs, $γFe_2O_3/Fe_3O_4$ nanoparticles, Ring Opening Metathesis Polymerization (ROMP), dicyclopentadiene, inductive heating
Objavljeno v DKUM: 24.08.2017; Ogledov: 869; Prenosov: 128
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Symmetry breaking and structure of a mixture of nematic liquid crystals and anisotropic nanoparticlesMarjan Krašna
, Matej Cvetko
, Milan Ambrožič
, 2010, izvirni znanstveni članek
Opis: Orientational ordering of a homogeneous mixture of uniaxial liquid crystalline(LC) molecules and magnetic nanoparticles (NPs) is studied using the Lebwohl-Lasher lattice model. We consider cases where NPs tend to be oriented perpendicularly to LC molecules due to elastic forces. We study domain-type configurations of ensembles, which are quenched from the isotropic phase. We show that for large enough concentrations of NPs the long range uniaxial nematic ordering is replaced by short range order exhibiting strong biaxiality. This suggests that the impact of NPs on orientational ordering of LCs for appropriate concentrations of NPs is reminiscent to the influence of quenched random fields which locally enforce a biaxial ordering.
Ključne besede: liquid crystals, nanoparticles, disorder, orientational order, quenched disorder, symmetry breaking
Objavljeno v DKUM: 03.08.2017; Ogledov: 988; Prenosov: 348
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