Browsing by Author "Demir, Fatma"

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    Bursa'nın gerdanlğı: Irgandı Köprüsü
    (Bilkent University, 2020) Göktuğ, Gül; Akartürk, Cansu; Göktuğ, Nur; Demir, Fatma; Peker, Cansu
    Bursa'nın Osmangazi ilçesini Yıldırım ilçesine bağlayan Irgandı Köprüsü II. Murad döneminde 1442 Hace Muslihiddin tarafından inşa edilmiştir. İpekyolu üzerinde yer alan bu köprü 31 dükkân ve bir mescit ile 2 adet depo şeklinde tasarlanmıştır. Çarşılı köprülerin dünyadaki sayılı örneklerinden biri ve Türkiye'deki tek örneği olan Irgandı köprüsü orijinal yapısıyla yüzyıllar boyu yerli ve yabancı seyyahların ilgisini çekmiştir. 1773 yangınına, 1855 depremlerine ve 1922 Yunan işgaline maruz kalan köprünün hasarlarını onarabilmek adına köprüde çeşitli restorasyonlar gerçekleştirilmiştir. Son restorasyonu 2004 yılında Osmangazi Belediyesi tarafından tamamlanan köprü günümüzde bir sanat köprüsüne dönüşmüştür. Dükkânlarında geleneksel el sanatları sergilenen köprü bugün adeta bir kültür geçididir ve ziyaretçilerini beklemektedir.
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    Formation and characterization of mechanochemically generated free lignin radicals from olive seeds
    (Scientific and Technical Research Council of Turkey - TUBITAK,Turkiye Bilimsel ve Teknik Arastirma Kurumu, 2021-04-28) Demir, Fatma
    In this study, formation and quantification of mechanochemically generated free radicals of lignin were evaluated after the extraction of lignin from olive seeds and detailed lignin characterization was performed. Lignin was extracted from crushed olive seeds as an insoluble solid using Klason method. Isolated lignin was mechanochemically grinded under cryo conditions using Cryomill and particlesizes were determined by using Zeta Sizer, structural changes were followed by XRD and FTIR-ATR; thermal stabilities were tracked by TGA and DSC. In order to enable solubility demanding studies (such as 1 H-NMR and GPC), acylation of lignin was accomplished. ESR measurements were completed to prove the nature of the radicals. Free radicals cavenging activity of olive seed lignin was determined and quantified using 2-diphenyl-1-picrylhydrazyl (DPPH) method. Number of created mechanoradicals (per gram of olive seed lignin) was calculated from the corresponding UV-Vis spectra. Finally, morphological changes of the lignin over cryomilling was evaluated using SEM
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    Why does wood not get contact charged? Lignin as an antistatic additive for common polymers
    (American Chemical Society, 2020) Özel, Mertcan; Demir, Fatma; Aikebaier, Aizimaiti; Kwiczak-Yiğitbaşı, Joanna; Baytekin, H. Tarık; Baytekin, Bilge
    Contact electrification (CE), or the development of surface charges upon contact and separation, is a millennia-old scientific mystery and the source of many problems in the industry. Since the 18th century, efforts to understand CE have involved ranking materials according to their charging propensities. In all these reports, wood, an insulator, turns out to be surprisingly immune to CE. Here, we show that this unique antistatic nature of wood is attributable to its lignin content, i.e., lignin removal from wood ceases the antistatic property, and (re)addition brings it back. The antistatic action of lignin (also an insulator) is proposed to be related to its radical scavenging action and can be explained through the bond-breaking mechanism of CE. Our results also show that lignin, a sustainable, low-cost biopolymer, can be used as an antistatic additive in some representative examples of elastomers and thermoplastics, displaying the universal nature of its antistatic action.