M-LEARNING - A NEW FORM OF LEARNING AND EDUCATION

At each step, the Internet and information technologies are changing many aspects of life. We live; we buy, work, manage, and communicate new ways that technology has enabled. Information and communication technology are pervasive the technology of today. It finds application in every branch of industry, and in all areas of education and the basis for the successful operation of all social and state structures. Information and communication technology (ICT) provides a good foundation for creative and effective use of knowledge. Using mobile technology in education changes the basic view of learning when, where and how to learn. M-learning is a unique type of learning because students can access the lessons anytime, anywhere. Mobile learning is learning supported by mobile devices. It represents a new form of education. The notion of mobile learning covers a wide range of devices used for learning at any place at any time. These include various wired and wireless devices (mobile phones, PDA, iPod, Sony PSP, notebook devices...). M-learning offers the possibility of using mobile devices combine many benefits of e-learning in a single portable package that can be used at any time and anywhere using mobile devices. Mobile devices are emerging as one of the most promising technologies to support learning as they offer new opportunities that do not offer static devices.&nbsp

TOOL FOR INTERACTIVE VISUAL ANALYSIS OF LARGE HIERARCHICAL DATA STRUCTURES

In the Big Data era data visualization and exploration systems, as means for data perception and manipulation are facing major challenges. One of the challenges for modern visualization systems is to ensure adequate visual presentation and interaction.  Therefore, within this paper, we present a tool for interactive visualization of data with a hierarchical structure. It is a general-purpose tool that uses a graph-based approach. However, its main focus is on the visual analysis of concept lattices generated as the output of the Formal Concept Analysis algorithm. As the data grow, concept lattice can become complex and hard for visualization and analysis. In order to address this issue, functionalities important for the exploration of the large concept lattices are applied within this tool. The usage of the tool is presented in the example of visualization of concept lattices generated based on the available data on the Canadas open data portal and can be used for exploring the usage of tags within datasets

GENERATING KNOWLEDGE STRUCTURES FROM OPEN DATASETS' TAGS - AN APPROACH BASED ON FORMAL CONCEPT ANALYSIS

Under influence of data transparency initiatives, a variety of institutions have published a significant number of datasets. In most cases, data publishers take advantage of open data portals (ODPs) for making their datasets publicly available. To improve the datasets' discoverability, open data portals (ODPs) group open datasets into categories using various criteria like publishers, institutions, formats, and descriptions. For these purposes, portals take advantage of metadata accompanying datasets. However, a part of metadata may be missing, or may be incomplete or redundant. Each of these situations makes it difficult for users to find appropriate datasets and obtain the desired information. As the number of available datasets grows, this problem becomes easy to notice. This paper is focused on the first step towards decreasing this problem by implementing knowledge structures to be used in situations where a part of datasets' metadata is missing. In particular, we focus on developing knowledge structures capable of suggesting the best match for the category where an uncategorized dataset should belong to. Our approach relies on dataset descriptions provided by users within dataset tags. We take advantage of a formal concept analysis to reveal the shared conceptualization originating from the tags' usage by developing a concept lattice per each category of open datasets. Since tags represent free text metadata entered by users, in this paper we will present a method of optimizing their usage through means of semantic similarity measures based on natural language processing mechanisms. Finally, we will demonstrate the advantage of our proposal by comparing concept lattices generated using formal the concept analysis before and after the optimization process. The main experimental research results will show that our approach is capable of reducing the number of nodes within a lattice more than 40%

Biliverdin-copper complex at the physiological pH

Biliverdin (BV) is a degradation product of heme catabolism, which is rapidly converted to bilirubin (BR) by BV reductase 1. Biliverdin and unconjugated BR, commonly named bile pigments, have important function in biochemical processes. The presence of copper and other biological and toxic transitional metals at significant concentrations in bile implies the possibility that metal complexes with bile pigments can be formed 2. Consequently, our interest was to study the complex of BV with copper in physiological conditions – phosphate buffer with pH 7.4. UV-Vis spectrophotometry was applied to investigate formation/degradation of complex of BV with copper ions and to check stoichiometry by titration, showing that BV interacted with Cu2+ in 1:1 stoichiometry. Mass spectroscopy analysis confirmed this – ion at m/z 643.36 was detected. The results of Raman spectroscopy of BV were in good agreement with previous reports 3. Comparing spectra of BV and BV-Cu complex, the following differences were observed: a new band at low wave number is emerged for the complex may be attributed to Cu-N bond vibration; the band which was shifted to lower energies implicates increased stability of BV in the complex; intensity changes imply a more planar structure of BV in the complex, while stronger bands in complex imply higher delocalization of π-electrons and consequently a higher stability of the BV structure. Pertinent to this, it has been proposed that complexes of BV model compounds with Cu2+ may show unusual electronic structures that exhibit a significant ligand radical character. 1H NMR spectrum of BV in phosphate buffer had a poor resolution of signals, which may originate from aggregation, but this was of little relevance here, since the addition of copper ions led to very strong effect - the complete loss of almost all lines. The loss of signals represents the result of strong paramagnetic effects that may come from an unpaired e- that is delocalized in pπ orbitalss of the ring/ligand influencing all protons in the complex. The EPR spectrum of Cu2+ (S = 1/2; I = 3/2) in phosphate buffer shows that Cu2+ is weakly coordinated in an axial symmetry with one gr line and four lines coming from hyperfine coupling along gs. The addition of BV in equimolar concentration led to the loss of Cu2+ signal. The remaining signal in the [BV]/[Cu2+] = 1 system was broad, and did not show hyperfine structure. The g-value of the isotropic signal of BV-Cu complex was significantly lower than the average g-value of Cu2+ in the phosphate buffer indicating delocalization of the spin away from the metal nucleus. Similar EPR signals have been reported previously 4. Parallel-mode EPR showed no signal. Furthermore, the spectra were run over a wide field range and no half field lines were observed, either in parallel or in perpendicular mode. These results are consistent with S = 0 for the copper center. Further, redox properties of the complex were examined. BV showed a well-defined anodic peak. The [BV]/[Cu2+] = 2 system showed two additional oxidation peaks at much lower potentials than BV. The former potential corresponds to the oxidation of Cu1+, as we have shown previously 5. There was a slight consumption of O2 in [BV]/[Cu2+] = 1 system, which may be explained by traces of ‘free’ copper. However, in the presence of an excess of copper ([BV]/[Cu2+] = 0.5), the consumption of O2 was significant. This implies that ‘free’ Cu2+ reacts with the complex and ‘shuttles’ an e- to O2. The complex was susceptible to oxidizing agents but not to reducing agents. Considering the results obtained we conclude that, at physiological pH, BV builds a complex with copper ions in 1:1 stoichiometry. The formation of complex involves the rearrangement of electronic structure which provides increased energetic stability and strong paramagnetic effects. We believe that a complex with a highly delocalized unpaired e- and the formal BV•+-Cu1+ character best suites the outlined properties, but other structures of the complex cannot be completely ruled out. The presented results may shed new light on long-standing issues of BV chemistry and catalysis in biological systems

Biliverdin-copper complex at the physiological pH

Biliverdin (BV) is a degradation product of heme catabolism, which is rapidly converted to bilirubin (BR) by BV reductase 1. Biliverdin and unconjugated BR, commonly named bile pigments, have important function in biochemical processes. The presence of copper and other biological and toxic transitional metals at significant concentrations in bile implies the possibility that metal complexes with bile pigments can be formed 2. Consequently, our interest was to study the complex of BV with copper in physiological conditions – phosphate buffer with pH 7.4. UV-Vis spectrophotometry was applied to investigate formation/degradation of complex of BV with copper ions and to check stoichiometry by titration, showing that BV interacted with Cu2+ in 1:1 stoichiometry. Mass spectroscopy analysis confirmed this – ion at m/z 643.36 was detected. The results of Raman spectroscopy of BV were in good agreement with previous reports 3. Comparing spectra of BV and BV-Cu complex, the following differences were observed: a new band at low wave number is emerged for the complex may be attributed to Cu-N bond vibration; the band which was shifted to lower energies implicates increased stability of BV in the complex; intensity changes imply a more planar structure of BV in the complex, while stronger bands in complex imply higher delocalization of π-electrons and consequently a higher stability of the BV structure. Pertinent to this, it has been proposed that complexes of BV model compounds with Cu2+ may show unusual electronic structures that exhibit a significant ligand radical character. 1H NMR spectrum of BV in phosphate buffer had a poor resolution of signals, which may originate from aggregation, but this was of little relevance here, since the addition of copper ions led to very strong effect - the complete loss of almost all lines. The loss of signals represents the result of strong paramagnetic effects that may come from an unpaired e- that is delocalized in pπ orbitalss of the ring/ligand influencing all protons in the complex. The EPR spectrum of Cu2+ (S = 1/2; I = 3/2) in phosphate buffer shows that Cu2+ is weakly coordinated in an axial symmetry with one gr line and four lines coming from hyperfine coupling along gs. The addition of BV in equimolar concentration led to the loss of Cu2+ signal. The remaining signal in the [BV]/[Cu2+] = 1 system was broad, and did not show hyperfine structure. The g-value of the isotropic signal of BV-Cu complex was significantly lower than the average g-value of Cu2+ in the phosphate buffer indicating delocalization of the spin away from the metal nucleus. Similar EPR signals have been reported previously 4. Parallel-mode EPR showed no signal. Furthermore, the spectra were run over a wide field range and no half field lines were observed, either in parallel or in perpendicular mode. These results are consistent with S = 0 for the copper center. Further, redox properties of the complex were examined. BV showed a well-defined anodic peak. The [BV]/[Cu2+] = 2 system showed two additional oxidation peaks at much lower potentials than BV. The former potential corresponds to the oxidation of Cu1+, as we have shown previously 5. There was a slight consumption of O2 in [BV]/[Cu2+] = 1 system, which may be explained by traces of ‘free’ copper. However, in the presence of an excess of copper ([BV]/[Cu2+] = 0.5), the consumption of O2 was significant. This implies that ‘free’ Cu2+ reacts with the complex and ‘shuttles’ an e- to O2. The complex was susceptible to oxidizing agents but not to reducing agents. Considering the results obtained we conclude that, at physiological pH, BV builds a complex with copper ions in 1:1 stoichiometry. The formation of complex involves the rearrangement of electronic structure which provides increased energetic stability and strong paramagnetic effects. We believe that a complex with a highly delocalized unpaired e- and the formal BV•+-Cu1+ character best suites the outlined properties, but other structures of the complex cannot be completely ruled out. The presented results may shed new light on long-standing issues of BV chemistry and catalysis in biological systems

Supplementary data for article: Dimitrijević, M. S.; Bogdanović Pristov, J.; Žižić, M.; Stanković, D. M.; Bajuk-Bogdanović, D.; Stanić, M.; Spasić, S.; Hagen, W.; Spasojević, I. Biliverdin-Copper Complex at Physiological PH. Dalton Transactions 2019, 48 (18), 6061–6070. https://doi.org/10.1039/c8dt04724c

Supplementary material for: [https://pubs.rsc.org/en/content/articlelanding/2019/DT/C8DT04724C#!divAbstract]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3066]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3068

Znanje i stavovi beogradskih studenata medicine i stomatologije o upravljanju medicinskim otpadom

Introduction/Objective Knowledge and practical skills in medical waste (MW) management are of equal importance for medical and dental doctors. The first comparative study on the knowledge and skills in the field of MW management among Belgrade students was conducted with the goal of examining whether students of medicine and dentistry are equally familiar with this extremely important field. Methods a cross-sectional study included 558 students of the sixth year of studies (430 medical and 128 dental students) who completed an anonymous semi-structured questionnaire to determine attitudes and knowledge on MW management. Results the majority of medical and dental students had no training in MW management (79.5% and 74.6%, respectively). Dental students use protective equipment more frequently than medical students (94.5% vs. 42%, p lt 0.001). However, full vaccinal protection against hepatitis B is better among medical students compared to dental students (57.7% vs. 39.1%, p lt 0.001). Complete knowledge on postexposal prophylaxis is better among medical students compared to dental students (44.5% vs. 13.3%, p lt 0.001). However, dental students are more disciplined in reporting injuries (63.1% vs. 52.4%, p = 0.038). The students' knowledge on primary separation of infectious waste (93% vs. 77.8%, p lt 0.001) and used needles (80.3% vs. 70.4%, p = 0.007) is better among dental students compared to medical students' correct answers. Conclusion Dental students show better knowledge on MW management and are more disciplined in using personal infection protection compared to medical students. The students support continued training on MW management and investigations on this topic.Uvod/Cilj Znanje i praktične veštine upravljanja medicinskim otpadom su od posebnog značaja za doktore medicine i stomatologije. Komparativna studija o znanju i veštinama iz oblasti upravljanja medicinskim otpadom sprovedena je među beogradskim studentima prvi put, u cilju ispitivanja da li ovom izuzetno važnom oblašću studenti medicine i stomatologije vladaju podjednako dobro. Metode Ova studija preseka obuhvatila je 558 studenata šeste godine studija na Beogradskom univerzitetu (430 studenata medicine i 128 studenata stomatologije), koji su popunili anonimni upitnik o znanju i stavovima o upravljanju medicinskim otpadom. Rezultati Većina studenata stomatologije i medicine nisu imali nikakvu posebnu obuku iz upravljanja medicinskim otpadom (79,5% i 74,6%). Studenti stomatologije su češće koristili zaštitnu opremu (94,5% prema 42%, p lt 0,001). Vakcinalna zaštita od hepatitisa B je kompletnija među studentima medicine u odnosu na studente stomatologije (57,7% prema 39,1%, p lt 0,001). Znanje o profilaksi posle izloženosti bolja je među studentima medicine (44,5% prema 13,3%, p lt 0,001). Međutim, studenti stomatologije su ažurniji u pogledu prijavljivanja povreda na radnom mestu (63,1% prema 52,4%, p = 0,038). Znanje studenata o primarnoj separaciji infektivnog otpada i korišćenih igala je bolje među budućim stomatolozima (tačni odgovori 93% nasuprot 77,8%; p lt 0,001 i 80,3% prema 70,4%; p = 0,007). Zaključak Studenti stomatologije imaju bolje znanje o upravljanju medicinskim otpadom i disciplinovaniji su u pogledu korišćenja zaštitne opreme na radu u odnosu na studente medicine. Studenti podržavaju kontinuiranu edukaciju o upravljanju medicinskim otpadom i dalja istraživanja o ovoj temi

Structural, photocatalytic and photoelectrochemical characteristics of ZnO nanoparticles synthesized by a glycine-nitrate process

Zinc oxide is a semiconductor material which still, after a century of scientific research, shows great potential in modern day utilisements such as heterogenous photocatalysis of organic pollutants and as a photoanode material for efficient water splitting and oxygen generation. In this work zinc oxide was synthesized by a glycine-nitrate combustion process, which is a cheap, simple and efficient method for synthesizing transition metal oxides. The obtained powder was calcined at 400 and 500 °C and samples were characterized in detail using X-ray powder diffraction (XRPD), Fourier-trasform infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FESEM), photoluminescence spectroscopy (PL) and UV-Vis diffuse reflectance spectroscopy (DRS). Photoelectrocatalytic properties were investigated via electrochemical methods: linear voltammetry (LV), chronoamperometry (CA) and impedance spectroscopy (EIS). The results show that the obtained samples are nanocrystalline wurtzite zinc oxide with no impurities, with average particle diameters of 33 nm (annealed at 400 °C) and 48 nm (annealed at 500 °C). Both samples show significant amounts of various crystal deffects. The determined zinc oxide band gap was lower than the band gap of bulk zinc oxide. Photoelectrochemical measurements revealed that this material is photostable and reactive to light. Water oxidation is enhanced by exposing the light. Finally, photocatalytic properties were tested via determining kinetic parameters of organic pollutant decomposition. Both samples showed excellent photocatalytic activity by decomposing methylene blue and phenol

MODALITIES OF TENANTS PARTICIPATION IN THE REVITALIZATION OF OPEN SPACES IN COMPLEXES WITH HIGH-RISE HOUSING

Participation of tenants is an actual and very efficient instrument for revitalizing open spaces in complex with high-rise housing. The share of tenants in joint activities in open spaces and in their improvement contributes to the development of the feeling of pride of the tenant and the responsibility for the housing environment. Therefore, through participation, tenants become motivated to undertake activities that can prevent further devastation of open spaces. Modalities of tenants' participation are diverse and some of the key are: tenants' personalization, learning to improve common spaces (semi-public, semi-private) and collective gardening. The aim of this paper is to affirm the participation of tenants in the programs of revitalization of open spaces and articulation of its significance in complexes with high-rise housing in the context of improvement of quality of life. In these compilations there often occurs alienation, lack of awareness of tenants for the improvement of open space, and encouragement of  participation of tenants is of particular importance. In this context, this paper analyzes an example of good practice of revitalizing open spaces in the residential complex Eriksbo in Gothenburg, where a great diversity of modalities of tenants' participation can be identified

Supplementary data for article: Dimitrijević, M. S.; Bogdanović Pristov, J.; Žižić, M.; Stanković, D. M.; Bajuk-Bogdanović, D.; Stanić, M.; Spasić, S.; Hagen, W.; Spasojević, I. Biliverdin-Copper Complex at Physiological PH. Dalton Transactions 2019, 48 (18), 6061–6070. https://doi.org/10.1039/c8dt04724c

Supplementary material for: [https://pubs.rsc.org/en/content/articlelanding/2019/DT/C8DT04724C#!divAbstract]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3066]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3068