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Functional 3D printed polysaccharide derivative scaffolds for vascular graft application : doctoral disertation
Fazilet Gürer, 2023, doktorska disertacija

Opis: Tissue engineering (TE) is an interdisciplinary field that aims towards replacement, healing or reconstruction of damaged tissue and organs. Incurable diseases are currently treated with organ transplantation, that have the disadvantages of insufficient donors, immune response, and organ rejection after transplantation. TE imitate the functions of extracellular matrix (ECM) to develop biocompatible/biodegradable scaffolds with appropriate features which are utilized to provide mechanical support, cellular infiltration, migration, and tissue formation, and to mimic the biochemical and biophysical cues of cells. Several fabrication methods have been introduced to mimic the 3D structure of ECM and 3D printing is one of the additive manufacturing techniques, widely used in TE because of its feasibility to build complex tissue constructs and control over fabrication and cell distribution. The polysaccharide-peptide conjugate has gained enormous interest in recent years owing to its biocompatibility, degradability, flexibility, and structural matching to natural proteoglycans. In this context, we reported here on investigation of biocompatibility with HUVECs, surface modification of 3D printed PCL scaffolds with an amine group and chemically crosslinked oxidized HA-amino acid/peptide conjugates (OHACs) was used to develop a novel biomaterial for use as a tissue engineered vascular graft. Modified polysaccharides were characterized with respect to their chemical structure, charge, UV and fluorescence properties and cytotoxicity. The successful conjugation was demonstrated by XPS, and a decrease in the free amine peaks on the surface was observed after conjugation. In addition, the water contact angle measurements showed improved wetting, an indication that the conjugation to the PCL-A surface was successful. Finally, the biocompatibility of the novel scaffolds was characterized by the MTS and the live- dead assay. In both assays, proliferation of cells was observed after 7 days and cell spreading on the surface was detected by phalloidin staining of actin filaments. In conclusion, it was possible to prepare surface-active scaffolds by combining the advantages of biocompatibility and mechanical strength of polysaccharides and polyesters, respectively.
Ključne besede: 3D tiskanje, karboksimetilceluloza, hialuronska kislina, polikaprolakton, kemija karbodiimida, kemija Shiffove baze, endotelizacija 3D printing, carboxymethyl cellulose, hyaluronic acid, polycaprolactone, carbodiimide chemistry, shiff-base chemistry, endothelialization
Objavljeno v DKUM: 06.10.2023; Ogledov: 356; Prenosov: 41
.pdf Celotno besedilo (7,97 MB)

4.
Differences in chemistry teachers' acceptance of educational software according to their user type : an application of extended UTAUT model
Kateřina Chroustová, Andrej Šorgo, Martin Bilék, Martin Rusek, 2022, izvirni znanstveni članek

Opis: In this research, a model to determine chemistry teachers' acceptance of educational software in secondary education is proposed. The model extends the unified theory of acceptance and use of technology (UTAUT) model. Data were collected from 556 Czech chemistry teachers and analysed using structural equation modelling. With respect to the significant differences among technology users and various types of nonusers, the research model for each user group was tested too. The results showed significant differences in the individual models for each group of technology user. In the model for "current users" of educational software, the influence of facilitating conditions on current users' use of educational software behavioural intention is stressed. In addition, non-planning users' behavioural intention seems to be influenced by their personal innovativeness in IT, social influence, and performance expectancy. Behavioural intention and attitude towards using educational software affect each of the tested models, with attitudes being an even stronger predictor of educational software usage than behavioural intention. The models contribute to the understanding of teachers' acceptance of educational software, which can be utilized in both pre- and in-service teacher training, considering technology mastery a necessary teacher competence.
Ključne besede: chemistry teachers' motivation, educational software use, secondary education, technology acceptance
Objavljeno v DKUM: 01.09.2023; Ogledov: 387; Prenosov: 41
.pdf Celotno besedilo (1,61 MB)
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5.
Slovenian Chemistry Teachers' Understanding of Project-based Learning
Hanija Bujas, 2020, magistrsko delo

Opis: Project-based learning (PBL) is a teaching method through which students gain knowledge and skills while working on a project for an extended period of time. They investigate and respond to an authentic, engaging, and complex problem. The popularity of PBL is constantly rising. However, PBL is hard to understand and therefore harder to implement in schools. In the master's thesis we wanted to understand how Slovenian chemistry teachers understand PBL, and how do they implement it in their teaching of chemistry or chemistry related subjects. We created a questionnaire on Google forms and distributed it to chemistry teachers of all Slovenian lower secondary schools and general upper secondary schools. We gathered 130 answers, out of which 95 were teachers who teach in lower secondary schools and 35 who teach in general upper secondary schools. According to the results, teachers barely understand PBL. A majority of teachers are convinced that they use PBL, when the results show that in practice they do not. Project-based learning is often confused for problem-based learning, which is the main confusion for the teachers. Our respondents believe that, because of extensive curriculum and lack of time, it is not possible to fully implement PBL in Slovenian schools.
Ključne besede: project-based learning, teachers, chemistry, understanding
Objavljeno v DKUM: 29.10.2020; Ogledov: 996; Prenosov: 58
.pdf Celotno besedilo (1,28 MB)

6.
Using chemical models for developing natural science competences in teaching chemistry : from pupils as model assemblers to pupils as creators of self-made models
Darinka Sikošek, Mateja Žuželj, 2013, izvirni znanstveni članek

Opis: Chemical models are indispensable tool in chemistry class and enable secondary school pupils to develop complex thought processes and spatial concepts, both of which are necessary to improve their understanding of chemical concepts. In this research, special emphasis is given to complex competencies not only their acquisition, but rather how pupils develop them. For this purpose, a learning strategy has been developed, called learning by self-generating chemical models. Pupils learn individually on their own models, which are made from easily accessible, low-cost materials. The impact of workable models was investigated (assembly of commercial models and production of self-made models) on the (1) learning success using simple molecule shapes and (2) the degree of competence development which realized through the implemented activities. The study involved first-year secondary school-pupils, defined as self-creators of paper- and -wire models (experimental group) and assemblers of commercial models (called the control group). The appearance of the molecules being studied took the form of geometric shapes and structures, which pupils present by making of ball-, called wire-models from plasticine and wire or paper created, called paper models. Based on the results of statistical processing of the data, we found that self-creation of models (as an innovative approach) leads to better understanding and to subsequently sustained knowledge for the pupil. It should also be noted that pupils who were self-generators in comparisons to those who merely assembled the models, generally developed many complex skills in the areas of problem solving, practical competence, mathematical competence and critical thinking skills. The knowledge so acquired was also better understood.
Ključne besede: education, chemical models, competencies, chemistry, self-made models
Objavljeno v DKUM: 19.12.2017; Ogledov: 1338; Prenosov: 69
.pdf Celotno besedilo (734,46 KB)
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7.
Implementation of process-targeted activities of prospective chemistry teachers during continuous teaching practice : a rational comparative analysis of teaching methods according to the expressed competencies
Darinka Sikošek, Kornelia Žarić, 2013, izvirni znanstveni članek

Opis: The main aim of the teacher study program is to ensure the proper role of teaching practice, which is included in initial teacher training courses. It is necessary that teachers of chemistry gain or develop learner competencies for appropriate teaching/ learning in the chemistry subject by using innovative teaching methods. In terms of activities and methods correction of the continuous teaching practice model for prospective chemistry teachers in Pedagogical study program of 2nd degree "Educational Chemistry" which would ensure the creation of a competent chemistry teacher (active and innovative). The main result of the study is a list of potential competencies by prospective chemistry teachers using innovative teaching methods. These competencies can be developed and produced in the performance of activities defined by using continuous teaching practice, particularly in the areas of testing and assessment, experiential and collaborative learning, and experimental (laboratory and field) work. Each of these components is separately assessed by activity and competence.
Ključne besede: education, innovative teaching methods, competencies, chemistry
Objavljeno v DKUM: 15.12.2017; Ogledov: 1020; Prenosov: 109
.pdf Celotno besedilo (828,32 KB)
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8.
Development of the research tool to identify factors affecting the use of chemistry educational software
Kateřina Chroustová, Martin Bílek, Andrej Šorgo, 2015, izvirni znanstveni članek

Opis: Currently, the implementation of information and communication technologies (ICT) has been strongly recommended to science teachers. For identification the factors of successful ICT implementation the Unified Theory of Use and Acceptance of Technology (UTAUT) is applied, which works as the theoretical background of planned monitoring of Czech chemistry teachers´ attitudes to this problem. This theoretical review introduces the process of creating the modified UTAUT model serving as the basis for a research tool to be exploited for the future survey. Within this process three sources were exploited: (1) theories dealing with factors which influence user behaviour in relation to the use of modern technologies, (2) the analysis of research results focused on the acceptance and use of ICT in chemistry instruction and (3) results of researches conducted by the authors in the field of the effectiveness of the educational software used in chemistry teaching and learning. The conducted analysis of these three sources resulted in defining the presented survey and designing the appropriate theoretical model and research tool.
Ključne besede: education, chemistry education, educational software, teachers' attitudes
Objavljeno v DKUM: 15.12.2017; Ogledov: 1148; Prenosov: 149
.pdf Celotno besedilo (983,16 KB)
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9.
Synthesis, crystal structure and magnetic properties of a new hydroxylammonium fluoroferrate
Brina Dojer, Matjaž Kristl, Zvonko Jagličić, Amalija Golobič, Marta Kasunič, Mihael Drofenik, 2012, izvirni znanstveni članek

Opis: This paper reports on the synthesis of a new hydroxylammonium fluoroferrate, with the formula $(NH_3OH)_3FeF_6$, obtained after dissolving iron powder in hydrofluoric acid and adding solid $NH_3OHF$. This new compound has been characterized by chemical and thermal analysis, single-crystal X-ray diffraction, and magnetic measurements. The title compound crystallizes trigonal, R3c, with cell parameters a = 11.4154(2) Å, c = 11.5720(2) Å, Z = 6. The structure consists of $NH_3OH^+$ cations and isolated $FeF_6^{3–}$ octahedra in which the central ion lies on a threefold axis. The oxygen and nitrogen atoms of the hydroxylammonium cations are donors of hydrogen bonds to fluoride anions, resulting in a network of hydrogen bonds between counterions. The effective magnetic moment $µ_{eff}$ = 5.8 BM was calculated and perfectly matches the expected value of high-spin Fe(III) ions. The thermal decomposition of the compound was studied by TG, DSC, and X-ray powder diffraction.
Ključne besede: inorganic chemistry, crystallography, coordination compounds, synthesis, crystal structure, characterization of compounds, determination of the structure of compounds, X-ray diffraction, magnetic measurements, thermal analysis, TG, DSC, hydrogen bond, metal complexes, hydroxylammonium fluoromethalatehydroxylammonium, fluoroferrate
Objavljeno v DKUM: 25.08.2017; Ogledov: 1967; Prenosov: 67
.pdf Celotno besedilo (198,42 KB)
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10.
Synthesis and characterisation of hydroxylammonium fluorochromate
Matjaž Kristl, Mihael Drofenik, Ljubo Golič, Amalija Golobič, 2003, izvirni znanstveni članek

Opis: Reactions in the system $Cr – NH_3OHF – HF – H_2O$ were investigated. Green crystals of a new compound with the formula $(NH_3OH)_3CrF_6$ have been isolated from the water solution and characterized by chemical analysis. The compound crystallizes as triclinic, P-1, with cell parameters: a = 6.5461(2) Å, b = 6.9347(2) Å, c = 9.4072(3) Å, α = 86.772(1)°, β = 83.804(1)°, γ = 70.283(1)°. The effective magnetic moment, $µ_{eff}$ = 3.82 BM, was calculated from magnetic susceptibility measurements in the temperature range 80-290 K. The thermal decomposition of the compound was studied by TG and DSC analysis. $(NH_3OH)_3CrF_6$ decomposes above 125 °C in three steps and the residue has been identified by X-ray powder diffraction as $α – Cr_2O_3$.
Ključne besede: inorganic chemistry, structural chemistry, crystalline structure, coordination compounds, synthesis, inorganic reactions, thermal decomposition, characterization of compounds, TG, DSC, X-ray diffraction, chromium complexes, hydroxylammonium fluoro chromates, crystals
Objavljeno v DKUM: 25.08.2017; Ogledov: 1758; Prenosov: 110
.pdf Celotno besedilo (206,45 KB)
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