Browsing by Subject "Thermostability"
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Item Open Access Antibacterial electrospun zein nanofibrous web encapsulating thymol/cyclodextrin-inclusion complex for food packaging(Elsevier, 2017-10) Aytac Z.; Ipek, S.; Durgun, Engin; Tekinay, T.; Uyar, TamerThymol (THY)/γ-Cyclodextrin(γ-CD) inclusion complex (IC) encapsulated electrospun zein nanofibrous webs (zein-THY/γ-CD-IC-NF) were fabricated as a food packaging material. The formation of THY/γ-CD-IC (1:1 and 2:1) was proved by experimental (X-ray diffraction (XRD), thermal gravimetric analysis (TGA), 1H NMR) and computational techniques. THY/γ-CD-IC (2:1) exhibited higher preservation rate and stability than THY/γ-CD-IC (1:1). It is worth mentioning that zein-THY/γ-CD-IC-NF (2:1) preserved much more THY as observed in TGA and stability of THY/γ-CD-IC (2:1) was higher, as shown by a modelling study. Therefore, much more THY was released from zein-THY/γ-CD-IC-NF (2:1) than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). Similarly, antibacterial activity of zein-THY/γ-CD-IC-NF (2:1) was higher than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). It was demonstrated that zein-THY/γ-CD-IC-NF (2:1) was most effective in inhibiting the growth of bacteria on meat samples. These webs show potential application as an antibacterial food packaging material.Item Open Access Cytotoxic and bioactive properties of different color tulip flowers and degradation kinetic of tulip flower anthocyanins(Pergamon Press, 2013) Sagdic, O.; Ekici, L.; Ozturk, I.; Tekinay, T.; Polat, B.; Tastemur, B.; Bayram, O.; Senturk, B.This study was conducted to determine the potential use of anthocyanin-based extracts (ABEs) of wasted tulip flowers as food/drug colorants. For this aim, wasted tulip flowers were samples and analyzed for their bioactive properties and cytotoxicity. Total phenolic contents of the extracts of the claret red (126.55. mg of gallic acid equivalent (GAE)/g dry extract) and orange-red (113.76. mg GAE/g dry extract) flowers were the higher than those of the other tulip flowers. Total anthocyanin levels of the violet, orange-red, claret red and pink tulip flower extracts were determined as 265.04, 236.49, 839.08 and 404.45. mg pelargonidin 3-glucoside/kg dry extract, respectively and these levels were higher than those of the other flowers. The extracts were more effective for the inhibition of Listeria monocytogenes, Staphylococcus aureus and Yersinia enterocolitica compared to other tested bacteria. Additionally, the cytotoxic effects of five different tulip flower extracts on human breast adenocarcinoma (MCF-7) cell line were investigated. The results showed that the orange red, pink and violet extracts had no cytotoxic activity against MCF-7 cell lines while yellow and claret red extracts appeared to be toxic for the cells. Overall, the extracts of tulip flowers with different colors possess remarkable bioactive and cytotoxic properties. © 2013 Elsevier Ltd.Item Open Access Encapsulation of vanillin/cyclodextrin inclusion complex in electrospun polyvinyl alcohol (PVA) nanowebs: prolonged shelf-life and high temperature stability of vanillin(2012-08) Kayaci, F.; Uyar, TamerWe produced functional nanowebs, containing vanillin, having prolonged shelf-life and high temperature stability facilitated by cyclodextrin (CD) inclusion complexation. Polyvinyl alcohol (PVA) nanowebs incorporating vanillin/cyclodextrin inclusion complex (vanillin/CD-IC) were produced via electrospinning technique. The vanillin/CD-IC was prepared with three types of CDs; α-CD, β-CD and γ-CD to find out the most favourable CD type for the stabilization of vanillin. PVA/vanillin/CD-IC nanofibres, having fibre diameters around ∼200 nm, were successfully electrospun from aqueous mixture of PVA and vanillin/CD-IC. Our results indicated that vanillin with enhanced durability and high temperature stability was achieved for PVA/vanillin/CD-IC nanowebs due to complexation of vanillin with CD, whereas the PVA nanofibres without CD-IC could not effectively preserve the vanillin. Additionally, we observed that PVA/vanillin/γ-CD-IC nanoweb was more effective for the stabilization and slow release of vanillin suggesting that the strength of interaction between vanillin and the γ-CD cavity is stronger when compared to α-CD and β-CD. © 2012 Elsevier Ltd. All rights reserved.Item Open Access Mesoporous metallic rhodium nanoparticles(Nature Publishing Group, 2017) Jiang B.; Li C.; Dag, Ö.; Abe, H.; Takei, T.; Imai, T.; Hossain, M. S. A.; Islam, M. T.; Wood, K.; Henzie, J.; Yamauchi, Y.Mesoporous noble metals are an emerging class of cutting-edge nanostructured catalysts due to their abundant exposed active sites and highly accessible surfaces. Although various noble metal (e.g. Pt, Pd and Au) structures have been synthesized by hard- and soft-templating methods, mesoporous rhodium (Rh) nanoparticles have never been generated via chemical reduction, in part due to the relatively high surface energy of rhodium (Rh) metal. Here we describe a simple, scalable route to generate mesoporous Rh by chemical reduction on polymeric micelle templates [poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA)]. The mesoporous Rh nanoparticles exhibited a ∼1/42.6 times enhancement for the electrocatalytic oxidation of methanol compared to commercially available Rh catalyst. Surprisingly, the high surface area mesoporous structure of the Rh catalyst was thermally stable up to 400 °C. The combination of high surface area and thermal stability also enables superior catalytic activity for the remediation of nitric oxide (NO) in lean-burn exhaust containing high concentrations of O 2.