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11.
Effect of low-density static magnetic field on the oxidation of ammonium by Nitrosomonas europaea and by activated sludge in municipal wastewater
Jasmina Filipič, Barbara Kraigher, Brigita Tepuš, Vanja Kokol, Ines Mandić-Mulec, 2015, izvirni znanstveni članek

Opis: Ammonium removal is a key step in biological wastewater treatment and novel approaches that improve this process are in great demand. The aim of this study is to test the hypothesis that ammonium removal from wastewater can be stimulated by static magnetic fields. This was achieved by analysis of the effects of static magnetic field (SMF) on the growth and activity of Nitrosomonas europaea, a key ammonia-oxidising bacterium, where increased growth and increased ammonia oxidation rate were detected when bacteria were exposed to SMF at 17 mT. Additionally, the effect of SMF on mixed cultures of ammonia oxidisers in activated sludge, incubated in sequencing batch bioreactors simulating wastewater treatment process, was assessed. SMFs of 30 and 50 mT, but not of 10 mT, increased ammonium oxidation rate in municipal wastewater by up to 77 % and stimulated ammonia oxidiser growth. The results demonstrate the potential for use of static magnetic fields in increasing ammonium removal rates in biological wastewater treatment plants.
Ključne besede: odpadne vode, bakterije, Nitrosomonas europaea, statično magnetno polje, biološke čistilne naprave, nitrifikacija
Objavljeno: 24.07.2017; Ogledov: 513; Prenosov: 278
.pdf Celotno besedilo (323,02 KB)
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12.
Magnetic field effects on redox potential of reduction and oxidation agents
Mojca Božič, Lucija Črepinšek-Lipuš, Vanja Kokol, 2008, izvirni znanstveni članek

Opis: Redox potentials of two reducing (sodium dithionite and glucose) and two oxidizing (hydrogen peroxide and sodium hypochlorite) agents were monitored at various concentrations and at different temperatures for 30-75 minutes after the exposure of their water solutions (glucose and hypochlorite solutions once; sodium dithionite and hydrogen peroxide solutions one, two and/or three-times) to the static magnetic field of flux density of 0.9 V s M-2 . The aim of the investigation was to suggest improvements, i.e., intensification and stability, of the reduction-oxidation ability of selected agents applicable in textile fibre processing, primarily bleaching and vat dyeing. Results of the experiments show that magnetic treatment (of solutions) raises both the reducing ability of glucose and the oxidation ability of hydrogen peroxide and sodium hypochlorite, promising some technological and economical benefits for the textile industry as well as forother fields of chemistry.
Ključne besede: magnetic water treatment, sodium dithionite, glucose, hydrogen peroxide, sodium hypochlorite, redox potential, textile vat processing
Objavljeno: 05.07.2017; Ogledov: 520; Prenosov: 69
.pdf Celotno besedilo (206,88 KB)
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13.
Native cellulose nanofibrills induce immune tolerance in vitro by acting on dendritic cells
Sergej Tomić, Vanja Kokol, Dušan Mihajlović, Aleksandar Mirčić, Miodrag Čolić, 2016, izvirni znanstveni članek

Opis: Cellulose nanofibrills (CNFs) are attractive biocompatible, natural nanomaterials for wide biomedical applications. However, the immunological mechanisms of CNFs have been poorly investigated. Considering that dendritic cells (DCs) are the key immune regulatory cells in response to nanomaterials, our aim was to investigate the immunological mechanisms of CNFs in a model of DC-mediated immune response. We found that non-toxic concentrations of CNFs impaired the differentiation, and subsequent maturation of human monocyte-derived (mo)-DCs. In a co-culture with CD4+T cells, CNF-treated mo-DCs possessed a weaker allostimulatory and T helper (Th)1 and Th17 polarizing capacity, but a stronger capacity to induce Th2 cells and CD4+CD25hiFoxP3hi regulatory T cells. This correlated with an increased immunoglobulin-like transcript-4 and indolamine dioxygenase-1 expression by CNF-treated mo-DCs, following the partial internalization of CNFs and the accumulation of CD209 and actin bundles at the place of contacts with CNFs. Cumulatively, we showed that CNFs are able to induce an active immune tolerance by inducing tolerogenic DCs, which could be beneficial for the application of CNFs in wound healing and chronic inflammation therapies.
Ključne besede: nanocellulose, cytotoxicity, T-cell proliferation, cytokine production, in vitro
Objavljeno: 23.06.2017; Ogledov: 636; Prenosov: 291
.pdf Celotno besedilo (2,87 MB)
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14.
The study of release of chlorhexidine from preparations with modified thermosensitive poly-n-isopropylacrylamide microspheres
Witold Musiał, Bojana Vončina, Vanja Kokol, Janusz Pluta, 2012, izvirni znanstveni članek

Opis: The aim of this study was to investigate and compare the release rates of chlorhexidine (CX) base entrapped in the polymeric beads of modified poly-N-isopropylacrylamides (pNIPAMs) at temperatures below and over the volume phase transition temperature (VPTT) of synthesized polymers: pNIPAM-A with terminal anionic groups resulting from potassium persulfate initiator, pNIPAM-B with cationic amidine terminal groups, and pNIPAM-C comprising anionic terminals, but with increased hydrophobicity maintained by the N-tert-butyl functional groups. The preparations, assessed in vitro below the VPTT, release an initial burst of CX at different time periods between 120 and 240 min, followed by a period of 24 h, when the rate of release remains approximately constant, approaching the zero-order kinetics; the release rates for the polymers beads are as follows: pNIPAM-C>pNIPAM-B>pNIPAM-A. The pattern of release rates at temperature over the VPTT is as follows: pNIPAM-C>pNIPAM-A>pNIPAM-B. In the presence of pNIPAM-C, the duration between the start of the release and the attained minimal inhibitory concentration (MIC) for most of the microbes, in conditions over the VPTT, increased from 60 to 90 min. The release prolongation could be ascribed to some interactions between the practically insoluble CX particle and the hydrophobic functional groups of the polymer.
Ključne besede: chlorhexidine, synthesized polymers, thermosensitivity
Objavljeno: 15.06.2017; Ogledov: 479; Prenosov: 286
.pdf Celotno besedilo (2,68 MB)
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Konstruiranje in izdelava komore za hlajenje s tekočim dušikom
Jasmin Vehabović, 2015, diplomsko delo

Opis: Namen naloge je opisati konstruiranje in izdelavo hladilne komore za hlajenje polimernih vzorcev, pri katerem lahko nadzorujemo hitrost in temperaturo ohlajanja. Potrebno je zmodelirati sistem v programskem paketu SolidWorks ter ga nato izdelati, po izdelavi testirati komoro in opisati postopek uporabe ter narediti preizkuse ohlajanja in meritve analizirat, na koncu pa podati možnosti optimiranja sistema.
Ključne besede: porozni polimeri, konstruiranje, hladilna komora, regulator, zamrzovanje polimernih vzorcev
Objavljeno: 27.10.2015; Ogledov: 1232; Prenosov: 62
.pdf Celotno besedilo (4,58 MB)

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STRUKTURNE SPREMEMBE BIOPOLIMERNIH MATERIALOV MED TOPLOTNO OBDELAVO IN STISKANJEM
Tilen Rajbar, 2014, diplomsko delo

Opis: Zaradi pomanjkanja fosilnih virov in negativnega vpliva plastike in polimerov na osnovi nafte na okolje so raziskave usmerjene k njihovi zamenjavi z naravnimi in obnovljivimi viri. V diplomskem delu so prikazane mehanske in druge lastnosti termoplastičnega škroba z dodatki različnih nanodelcev. Namen diplomskega dela je bil razviti biopolimerni film na osnovi škroba za industrijsko rabo in s čim manjšo prepustnostjo vodne pare ter čim boljšimi mehanskimi lastnostmi. Material smo gnetli v Brabenderjevem gnetilniku pri različnih temperaturah in obratih ter ga stisnili na laboratorijski stiskalnici. Določevali smo natezno trdnost, prepustnost vlage skozi vzorec, viskoznost, termično analizo, posnetke površin vzorcev in kemijske spremembe z infrardečo spektroskopijo. Ugotovili smo, da filmi termoplastičnega škroba, ki smo jih uporabili v diplomskem delu, ne zadoščajo pogojem za neposredno industrijsko rabo.
Ključne besede: termoplastični škrob, brabenderjev gnetilnik, plastifikator, nanodelci, prepustnost vodne pare, mehanske lastnosti, biopolimerni filmi
Objavljeno: 22.09.2014; Ogledov: 1088; Prenosov: 157
.pdf Celotno besedilo (3,02 MB)

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