Candida rugosa lipase immobilized onto titania: improved thermal stability and reuse potential

Enzyme catalyzed reactions have been extensively exploited for a wide range of applications in biotechnology. In spite of a broad implementation of enzymes in different fields, some constraints referred to their cost and process stability still exists. To overcome a limit related to short catalytic lifetime of enzymes in process conditions, a spectrum of immobilization methods have been extensively studied to increase stability and enhance reuse, offer easier separation, making production economically viable.V International Conference on Radiation in Various Fields of Research : RAD 2017 : book of abstracts; June 12-16, 2017; Budva, Montenegr

Supplementary data for the article: Izrael Živković, L. T.; Živković, L. S.; Beškoski, V. P.; Gopčević, K. R.; Jokić, B. M.; Radosavljević, D. S.; Karadžić, I. M. The Candida Rugosa Lipase Adsorbed onto Titania as Nano Biocatalyst with Improved Thermostability and Reuse Potential in Aqueous and Organic Media. Journal of Molecular Catalysis B: Enzymatic 2016, 133, S533–S542. https://doi.org/10.1016/j.molcatb.2017.06.001

Supplementary material for: [https://doi.org/10.1016/j.molcatb.2017.06.001]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/315]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3648

Candida rugosa lipase immobilized onto titania as nanobiocatalyst in organic solvent

Kinetic measurements can be used to predict the optimum kinetic behaviour of a particular biocatalyst. Based on those predictions, optimisation of biocatalytic reactions, as well as process design to improve productivity and reduce the cost of various processes can be performed.V International Conference on Radiation in Various Fields of Research : RAD 2017 : book of abstracts; June 12-16, 2017; Budva, Montenegr

APPLICATION OF EXPERIMENT IN THE REALIZATION OF GEOGRAPHICAL CONTENTS IN THE FIRST CYCLE OF COMPULSORY EDUCATION FROM A TEACHER’S PERSPECTIVE

School experiments enable students to gain knowledge through direct practical activities. The aim of the research study was to obtain information on the scope of application of models, experiments and research, as methodical solutions, when processing geographical content in the teaching of social, environmental and scientific education. An empirical study was conducted to analyze the experiences of 117 teachers, in the first cycle of compulsory education in the Republic of Serbia, about the application of this work method. The results of the research indicate that teachers occasionally realize geographical content, in the teaching of social, environmental and scientific education, through experiments, even though the resources needed for their implementation are accessible to all students. Experiments can be applied to explain the essence of physical geographical phenomena and processes, however, their use in teaching involves the training of teachers to use them, which, unfortunately, was mostly cited by teachers as a reason for occasional application. Greater attention should be given to training future teachers to apply the experiments in order to use this method more often when working with students, where they would work as a team, be active, creative, think critically, identify and explain phenomena and processes and relate to examples from everyday life.Publishe

Cooperation of the pre-service chemistry and geography teachers on an interdisciplinary lesson planning

The aim of this research was to examine the effects of a new platform for raising the pre-service chemistry and geography teachers’ awareness of cooperation possibilities associated with the planning relevant interdisciplinary lesson. The research featured the participation of 16 students of the Faculty of Chemistry and 28 students of the Faculty of Geography of Belgrade University. Two workshops were conducted within the research. During the first workshop the participants worked in small groups on the tasks which served to strengthen their awareness on the relevant science education. The second workshop comprised the jointly planning the interdisciplinary lessons in groups with members of the pre-service teachers of both subjects. The participants’ lesson plans contain goals that can be classified as those relevant for the individual and those relevant for society. Half of the lesson plans contained formulations of goals that can be assessed as relevant for certain professions. The activities planned for the attainment of the stated goals support an interdisciplinary approach, encompass the concepts envisaged by the chemistry and geography curricula, and the activities specific to these two subjects

Syntheses and characterization of 2-acetylpyridine-aminoguanidine and its copper(II) complexes: Crystallographic and antimicrobial study

The syntheses, physico-chemical and microbiological properties of the ligand, 2-acetylpyridine-aminoguanidine dihydrogensulfate monohydrate and its five complexes with Cu(II) are described. The compounds were characterized by single crystal X-ray crystallography. Common fragments encountered in some of the structures were compared by r.m.s. overlay calculations as well as half-normal probability plots. In these complexes the chelate ligand is coordinated in its neutral form in a tridentate N-3-coordination mode, via pyridine, azomethine and imino nitrogen atoms of the aminoguanidine fragment. In these complexes the Cu(II) ion is situated in moderately or severely distorted square-pyramidal surroundings. The antimicrobial activity of the ligand and the complexes were examined against 6 selected bacterial and 3 fungal strains.This is peer-reviewed version of the following article: Vojinović-Ješić, L. S.; Radanović, M. M.; Rodić, M. V.; Živković-Radovanović, V.; Jovanović, L. S.; Leovac, V. M. Syntheses and Characterization of 2-Acetylpyridine-Aminoguanidine and Its Copper(II) Complexes: Crystallographic and Antimicrobial Study. Polyhedron 2016, 117, 526–534. [https://doi.org/10.1016/j.poly.2016.06.032]Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3583

The Candida rugosa lipase adsorbed onto titania as nano biocatalyst with improved thermostability and reuse potential in aqueous and organic media

The immobilization of Candida rugosa lipase by adsorption was performed onto commercial titania powder (Degussa P25). The change of titania particles surface was diagnosed by means of FTIR and FESEM analysis, as well as by shift of zeta potential value towards that of lipase. A detailed study of the effect of immobilization on enzyme kinetic, temperature stability, as well as on potential for its reuse in aqueous organic media was undertaken. Immobilization of lipase altered enzyme affinity toward substrates with different length of carbon chain in hydrolytic reaction. The Vmax value decreased 2–8-fold, where major constraint was registered for the ester containing the longest carbon chain. Thermostability of lipase improved more than 7-fold at 60 °C. Significant potential for reuse in water solutions was also found after immobilization. In cyclohexane immobilized lipase catalyzed synthesis of amyl octanoate by ping-pong bi–bi mechanism with inhibition by amyl alcohol. Obtained kinetic constants were Vmax = 26.4 μmol min−1, KAc = 0.52 mol/L, KAl = 0.2 mol/L and Ki,Al = 0.644 mol/L. Esterification activity remained 60% after 5 reuse cycles in cyclohexane indicating moderate reuse stability. © 2017 Elsevier B.V.This is peer-reviewed version of the following article: Izrael Živković, L. T.; Živković, L. S.; Beškoski, V. P.; Gopčević, K. R.; Jokić, B. M.; Radosavljević, D. S.; Karadžić, I. M. The Candida Rugosa Lipase Adsorbed onto Titania as Nano Biocatalyst with Improved Thermostability and Reuse Potential in Aqueous and Organic Media. Journal of Molecular Catalysis B: Enzymatic 2016, 133, S533–S542. [https://doi.org/10.1016/j.molcatb.2017.06.001]Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3649

Supplementary data for the article: Izrael Živković, L. T.; Živković, L. S.; Beškoski, V. P.; Gopčević, K. R.; Jokić, B. M.; Radosavljević, D. S.; Karadžić, I. M. The Candida Rugosa Lipase Adsorbed onto Titania as Nano Biocatalyst with Improved Thermostability and Reuse Potential in Aqueous and Organic Media. Journal of Molecular Catalysis B: Enzymatic 2016, 133, S533–S542. https://doi.org/10.1016/j.molcatb.2017.06.001

Supplementary material for: [https://doi.org/10.1016/j.molcatb.2017.06.001]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/315]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3648

Stanje tvrdog i mekog periimplantnog tkiva u estetskoj regiji gornje vilice posle prezervacije alveolarnog grebena beta-trikalcijum fosfatom sa kolagenom tip I - studija sa jednogodišnjim periodom praćenja

Background/Aim. Alveolar ridge dimensional alterations following tooth extraction in the anterior maxilla often result in an inadequate bone volume for a correct implant placement. In order to obtain optimal bone volume various bone graft substitutes have become commercially available and widely used for socket grafting. The aim of this study was to examine and compare long-term clinical outcomes of dental implant therapy in the maxillary esthetic zone, after socket grafting with beta-tricalcium phosphate (TCP) combined with collagen type I, either with or without barrier membrane and flap surgery, after a 12-month follow-up. Methods. Twenty healthy patients were allocated to either C group (beta-TCP and type I collagen without mucoperiosteal flap coverage) or C+M group (beta-TCP and type I collagen barrier membrane with mucoperiosteal flap coverage). Following clinical parameters were assessed: implant stability (evaluated by a resonance frequency analysis - RFA), periimplant soft tissue stability (sulcus bleeding index - SBI, Mombelli sulcus bleeding index - MBI, periimplant sulcus depth, keratinized gingiva width, gingival level) and marginal bone level at the retroalveolar radiograms. Results. Within C+M group, RFA values significantly increased 12 weeks after implant installation compared to primary RFA values. Comparison between investigated groups showed a significantly reduced keratinized gingiva width in the C+M group compared to the C group after 3, 6, 9 and 12 months. Comparison between groups revealed significantly lower gingival level values in the C+M group at 9th and 12th month when compared to the C group. Conclusion. Implant treatment in the anterior maxilla could be effective when using a 9 months alveolar ridge preservation healing with combined treatment with beta-tricalcium phosphate and type I collagen, with regard to the peri-implant soft and hard tissue stability.Uvod/Cilj. Posle ekstrakcije zuba, dimenzionalne promene alveolarnog grebena u estetskoj regiji gornje vilice za posledicu često imaju nedovoljnu količinu kosti za ugradnju zubnih implanata. U vezi sa tim, primenjuju se različiti koštani zamenici sa ciljem očuvanja dimenzija alveolarnog grebena posle ekstrakcije zuba. Cilj rada bio je da se, posle prezervacije alveolarnog grebena beta-trikalcijum fosfatom (TCP) sa kolagenom tip 1, sa barijernom membranom i mukoperiostalnim režnjem i bez nje, ispitaju i uporede klinički ishodi zarastanja posle ugradnje zubnih implanata u estetskoj regiji gornje vilice, tokom jednogodišnjeg perioda praćenja. Metode. Dvadeset zdravih bolesnika podeljeno je u dve grupe: C (beta TCP/kolagen tip 1 bez barijerne membrane i mukoperiostalnog režnja) i C+M (beta TCP/kolagen tip 1 sa barijernom membranom i mukoperiostalnim režnjem). Praćeni su uobičajeni klinički parametri ishoda terapije: implantna stabilnost (analiza rezonantne frekvence), stanje mekih tkiva (indeks krvarenja, plak indeks, širina pripojne mukoze, recesija gingive) i nivo periimplantnog koštanog tkiva na retroalveolarnom radiogramu. Rezultati. U C+M grupi, implantna stabilnost posle 12 nedelja bila je značajno veća u odnosu na primarnu stabilnost. U C+M grupi, širina keratinizovane gingive bila je značajno manja posle 3, 6, 9 i 12 meseci u odnosu na C grupu. Recesija gingive bila je značajno veća u C+M grupi u odnosu na C grupu posle 9 i 12 meseci. Zaključak. Razmatrajući stabilnost mekog i tvrdog periimplantnog tkiva, terapija zubnim implantima može biti uspešna prilikom ugradnje u estetskoj regiji gornje vilice

Supplementary material for the article: Milenković, I.; Radotić, K.; Matović, B.; Prekajski, M.; Živković, L.; Jakovljević, D.; Gojgić-Cvijović, G.; Beškoski, V. Improving Stability of Cerium Oxide Nanoparticles by Microbial Polysaccharides Coating. Journal of the Serbian Chemical Society 2018, 83 (6), 745–757. https://doi.org/10.2298/JSC171205031M

Supplementary material for: [https://doi.org/10.2298/JSC171205031M]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2087