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Effect of synthesis route of mesoporous zirconia based Ni catalysts on coke minimization in conversion of biogas to synthesis gas
Hande Mustu, Sena Yaşyerli, Nail Yaşyerli, Gülşen Doğu, Timur Doğu, Petar Djinović, Albin Pintar, 2015, original scientific article

Abstract: Mesoporous zirconia and nickel incorporated zirconia catalysts were prepared following different routes. Synthesis of mesoporous zirconia and Ni incorporated zirconia with very narrow pore size distributions and high surface area was achieved. Ni incorporated mesoporous zirconia materials showed high activity in carbon dioxide reforming of methane, performed at 600 °C. Coke formation during dry reforming was eliminated over the Ni incorporated zirconia catalyst prepared by the one-pot procedure, using Pluronic P123 as the surfactant. It was shown that Ni was very well distributed within this material with cluster sizes smaller than the detection limit of XRD. This catalyst also showed highly stable catalytic performance. However, the catalysts prepared by the impregnation method showed higher activity but much higher coke formation than the catalyst prepared by the one-pot route.
Keywords: Biogas, syngas, dry reforming, mesoporous zirconia, coke
Published in DiRROS: 12.02.2015; Views: 4777; Downloads: 842
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295.
Amino- and ionic liquid-functionalised nanocrystalline ZnO via silane anchoring - an antimicrobial synergy
Marjeta Čepin, Vasko Jovanovski, Matejka Podlogar, Zorica Crnjak Orel, 2015, original scientific article

Abstract: Temperature has critical impact on food quality and safety within food supply chain, therefore, food should be kept at the defined storage temperature range. Final consumer should be assured when buying food about actual temperature and thermal history of the selected food product and this is why it should be indicated on the packed or prepacked item. The chromogenic temperature indicator for cold food chain was prepared from suitable active material packed in the properly structured holder. When temperature rises above the defined storage temperature, the active material changes colour and physical state (solid/liquid). Simultaneously, special packaging structure enables irreversible recording of the time exposed to the elevated temperature. The active material was made of thermochromic composite, consisting of dye, developer and solvent. It changes colour at its melting point, being coloured below and discoloured above it. The temperature is called activation temperature of the composite. Its value was adjusted by appropriate solvent and additives used for preparation of the composite, to reach the desired value. The temperature dependent colour change of the composite was determined by colorimetric measurements. The conditions for best observation of the change by naked eye were also examined. The structure of the active material’s holder was analyzed for best displaying of the time spend at high temperature (above the activation temperature). Functioning of the indicator was examined with growth of pathogens as a function of migration of the active material at temperature above the required storage temperature of the food. It was found out that the described chromogenic temperature indicator for cold food chain shows the thermal history of food storage by colour-, phase- and migration changes of the active composite material and consequently would be reliable as indicator in cold food chain to indicate temperature abuse and would disclose potential growth of psychrophilic microorganisms.
Keywords: Chromogenic temperature indicator, Food cold chain, Food quality and safety, Temperature control, Thermal history
Published in DiRROS: 16.12.2014; Views: 6177; Downloads: 946
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296.
Post-polymerization modification of poly(L-glutamic acid) with d-(+)-glucosamine
Peter Perdih, Sašo Čebašek, Alenka Možir, Ema Žagar, 2014, original scientific article

Abstract: Carboxyl functional groups of poly(L-glutamic acid) (PGlu) were modified with a D-(+)-glucosamine (GlcN) by amidation using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4- methylmorpholinium chloride (DMTMM) as a coupling reagent. The coupling reaction was performed in aqueous medium without protection of hydroxyl functional groups of D-(+)-glucosamine. Poly(L-glutamic acid) and GlcN functionalized polyglutamates (P(Glu-GlcN)) were thoroughly characterized by 1D and 2D NMR spectroscopy and SEC-MALS to gain detailed information on their structure, composition and molar mass characteristics. The results reveal successful functionalization with GlcN through the amide bond and also to a minor extent through ester bond formation in position 1 of GlcN. In addition, a ratio between the α- and β-form of glucosamine substituent coupled to polyglutamate repeating units as well as the content of residual dimethoxy triazinyl active ester moiety in the samples were evaluated.
Keywords: poly(L-glutamic acid), glucosamine, glycopolypeptide
Published in DiRROS: 16.12.2014; Views: 4582; Downloads: 917
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297.
The hazard assessment of nanostructured CeO [sub] 2-based mixed oxides on the zebrafish Danio rerio under environmentally relevant UV-A exposure
Anita Jemec Kokalj, Petar Djinović, Ilja Gasan Osojnik Črnivec, Albin Pintar, 2015, original scientific article

Abstract: The effect of nanomaterials on biota under realistic environmental conditions is an important question. However, there is still a lack of knowledge on how different illumination conditions alter the toxicity of some photocatalytic nanomaterials. We have investigated how environmentally relevant UV-A exposure (intensity 8.50 ± 0.61 W/m2, exposure dose 9.0 J/cm2) affected the toxicity of cerium oxide (CeO2)-based nanostructured materials to the early-life stages of zebrafish Danio rerio. Pure cerium oxide (CeO2), copper–cerium (CuO–CeO2) (with a nominal 10, 15 and 20 mol.% CuO content), cerium–zirconium (CeO2–ZrO2) and nickel and cobalt (Ni–Co) deposited over CeO2–ZrO2 were tested. It was found that under both illumination regimes, none of the tested materials affected the normal development or induced mortality of zebrafish early-life stages up to 100 mg/L. Only in the case of CuO–CeO2, the growth of larvae was decreased (96 h LOEC values for CuCe10, CuCe15 and CuCe20 were 50, 50 and 10 mg/L, respectively). To conclude, CeO2-based nanostructured materials are not severely toxic to zebrafish and environmentally relevant UV-A exposure does not enhance their toxicity.
Keywords: Nickel cobalt nanocrystalline catalysts, UV-A phototoxicity, UV-shielding, zebrafish
Published in DiRROS: 16.12.2014; Views: 9168; Downloads: 625
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