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Abstract: Barium hexaferrite nanoplatelets (BHF NPLs) are permanent nanomagnets with the magnetic easy axis aligned perpendicular to their basal plane. By combining this specific property with optimised surface chemistry, novel functional materials were developed, e.g., ferromagnetic ferrofluids and porous nanomagnets. We compared the interaction of chemically different phosphonic acids, hydrophobic and hydrophilic with 1–4 phosphonic groups, with BHF NPLs. A decrease in the saturation magnetisation after functionalising the BHF NPLs was correlated with the mass fraction of the nonmagnetic coating, whereas the saturation magnetisation of the NPLs coated with a tetraphosphonic acid at 80 °C was significantly lower than expected. We showed that such a substantial decrease in the saturation magnetisation originates from the disintegration of BHF NPLs, which was observed with atomic-resolution scanning transmission electron microscopy and confirmed by a computational study based on state-of-the-art first-principles calculations. Fe K-edge XANES (X-ray absorption near-edge structure) and EXAFS (Extended X-ray absorption fine structure) combined with Fourier-transformed infrared (FTIR) spectroscopy confirmed the formation of an Fe–phosphonate complex on the partly decomposed NPLs. Comparing our results with other functionalised magnetic nanoparticles confirmed that saturation magnetisation can be exploited to identify the disintegration of magnetic nanoparticles when insoluble disintegration products are formed.
Keywords: barium hexaferrite, Fe XANES, EXAFS, magnetic nanoparticles
Published in RUNG: 06.07.2023; Views: 1082; Downloads: 4
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Abstract: Lactic acid bacteria (LAB) are naturally present in grapes, musts and wines. During malolactic fermentation, besides the beneficial conversion of L-malic to L-lactic acid, LAB can form also other compounds like biogenic amines (BAs). BAs are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing BAs can lead to food poisoning such as histamine poisoning. Histamine, the most studied BA, is known to cause headaches, oedema, vomiting. In the last years, BAs associated pathways have been described as strain dependent and not as species dependent. Because of the high variability of microorganisms to decarboxylase amino acids, the detection of bacteria that have the possibility to transform precursor amino acid into BAs is very important in order to estimate the risk of BAs accumulation in wines. Since in previous years during project AGROTUR I we detected the higher BA content in some wines, we decided to focus on the presence of BA-producing LAB in Refošk grapes and wines. Therefore, during AGROTUR II project LAB collection of autochthonous lactic acid bacteria was set-up by isolating LAB from Refošk grapes and wines, originated from the grape growing cross-border region Karst (Slovenia). Over 600 isolates were obtained using MRS medium with added cycloheximide and 2% tomato juice. In parallel, also selective enrichment was performed using MRS medium described above with additionally added 5% ethanol. BA-producing LAB were primarily detected in microtiter-plate format using the decarboxylase screening medium with added amino acids (histidine, lysine, ornithine or tyrosine), which enable us to identify histamine-, cadaverine-, ornithine and tyrosine-producing LAB. Selected representatives from each BA-producing LAB groups were further on confirmed with chromatographic analysis (HPLC) and molecular methods (multiplex PCR method). BA-producing LAB were in majority represented by thyramin-producers, thereafter followed cadaverine-producers, with putrescine and histamine producers being the least presented. This screening of the BA-producing LAB is also incorporated in our on-going accurate selection of LAB starters for potential production of Refošk wines.
Keywords: biogenic amines, lactic acid bacteria, refošk, grape, wine
Published in RUNG: 22.01.2020; Views: 3312; Downloads: 0
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Keywords: Nanoparticle, sintering-Hexaferrite nanoplatelets, Magnetic properties, Fusion grain growth
Published in RUNG: 17.07.2019; Views: 3023; Downloads: 0
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Keywords: motiviranje za branje, strategije, M. Sarto, recepcija, evalvacija
Published in RUNG: 24.01.2019; Views: 4269; Downloads: 134
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Abstract: V magistrski nalogi so predstavljene trgovske poti Gaberk iz Vipavskih brd ter vpliv le-teh na spreminjajočo se družbeno vlogo ženske v družini in vasi. Zaradi specifičnih družbeno-gospodarskih razmer, v katerih so živele, je bilo njihovo življenje kmečke gospodinje vse prej kot vpeto med štiri stene. Igrale so več vlog: bile so matere, žene, vaščanke, trgovke oziroma brangerce, kontrabantke in migrantke. Brangerca je ženska, ki je na razne nelegalne ali pollegalne načine nosila jajca, maslo, sezonsko zelenjavo, maline, meso, žganje in druge pridelke v italijanska mesta, jih tam prodala ali menjala in prinesla domov nekaj denarja ali živil in gospodinjskih potrebščin. Ker je državna oblast brangerski način trgovanja omejevala s plačilom taks in dajatev, predvsem pa je bila obdavčena dobičkonosna trgovina z žganjem in tobakom, so ženske pričele s tihotapljenjem. Tako so iz legalnih brangerc postale kontrabantke oziroma tihotapke, trgovke, ki so skušale priti do svojih strank po skrivnih poteh, predvsem pa z domiselno skritim trgovskim blagom. V iskanju boljših pogojev za življenje so se Gaberke tudi izseljevale v bližnja italijanska mesta. V uvodu je predstavljen koncept naloge, teze in metodološka izhodišča. Jedrni del vstavi zgodbe brangerc v različne zgodovinske okoliščine (prva svetovna vojna, vinska kriza po postavitvi rapalske meje ter končno postavitev državne meje med Jugoslavijo in Italijo). Na podlagi podatkov, pridobljenih z metodo ustne zgodovine ter ohranjenega arhivskega ter matičnega gradiva, je predstavljeno vsakdanje življenje žensk ter njihove vloge. V sklepnemu poglavju so zgoščena spoznanja o vrednotenju ženskega dela in vlogah ženske znotraj družine ter vasi. Sklepnemu poglavju sledi seznam literature in virov ter povzetek v angleškem jeziku.
Keywords: brangerca, kontrabant, krožne selitve, izseljevanje, Trst, Vipavska brda, rapalska meja
Published in RUNG: 14.09.2016; Views: 5707; Downloads: 259
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