Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
3 results
Search Results
Article Citation - WoS: 4Citation - Scopus: 3Ligand Engineering for Improving the Stability and Optical Properties of Cspbi3 Perovskite Nanocrystals(Elsevier B.V., 2024) Yuce Cakir,H.; Yalcinkaya,Y.; Demir,M.M.Inorganic lead halide perovskite nanocrystals (NCs) have recently become one of the research topics for optoelectronic applications due to their excellent photophysical properties. Despite their notable thermal stability over organic-inorganic halide perovskites, CsPbI3 NCs suffer from the phase instability of α-CsPbI3 phase at room temperature and under ambient conditions. Here, the effects of 4-Hydroxybenzoic acid (4-HBA) as an additive to standard oleic acid – oleylamine pair on the stability and optical properties of CsPbI3 perovskite NCs are discussed. 4-HBA addition into perovskite NC systems causes a compressive strain on perovskite lattice, which leads to the formation of a mixed phase α- and γ-CsPbI3 phases while pristine perovskite has α-CsPbI3 phase. Time-dependent stability of the perovskite NCs was tested under an ethanol (EtOH) medium. After EtOH exposure of the perovskite NCs, CsPbI3 NCs transformed to non-perovskite phase in 1 h while 4-HBA added CsPbI3 NCs still have perovskite phase after 48 h. In addition to the improved optical properties of the perovskite NCs, 4-HBA addition remarkably improves CsPbI3 perovskite stability. © 2024 Elsevier B.V.Conference Object Citation - Scopus: 1Strength Requirements of Permanent Metal Deck Forms Used for Lateral Bracing of Steel Bridge Girders(2006) Eğilmez, Oğuz Özgür; Helwig, T.A.; Herman, R.S.Permanent metal deck forms (PMDF) are often used in steel bridges to support the weight of the wet concrete during deck construction. Although the PMDF also has the potential to provide bracing to steel bridge girders during construction, the stiffness of the PMDF system as a lateral brace is drastically reduced by the eccentric support angle connection detail used to attach the forms to the girders. Laboratory tests have shown that a simple modification to the connection detail can substantially increase the stiffness of these PMDF systems and allow utilization of the PMDF for girder bracing. This paper presents results from a parametrical study conducted to determine stability and strength requirements for PMDF used to provide lateral bracing to steel bridge girders. Detailed FEA models were used to determine the stability bracing strength requirements for the fasteners that are used to connect the PMDF along the sidelaps of the sheets and to the girders. Design expressions are presented as well as an example demonstrating the use of the design equations.Article Citation - WoS: 20Citation - Scopus: 21Long Term Stability of Biodegradable Polymers on Building Limestone(Elsevier Ltd., 2019) Kaplan, Zişan; Böke, Hasan; Sofuoğlu, Aysun; İpekoğlu, BaşakSynthetic polymers can be replaced by biodegradable ones as adhesives, water repellents and consolidants on the stone surfaces and facades of the historic buildings in their conservation to minimize future deterioration. In this study, the long-term stability of two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-L-lactide (PLA), and an acrylic polymer (Paraloid B72) which is commonly used in conservation works of artefacts, were evaluated on limestone using a UV lamp-weathering chamber (up to 104 days) for future protection studies. Chemical and morphological changes induced by an accelerated weathering test were examined by Fourier Transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analyses. Protection efficiency of the polymers was determined by the changes in color, capillary water absorption, static contact angle on limestone. Paraloid B72, PHB, and PLA coatings significantly increased hydrophobicity while decreasing capillarity water absorption and caused negligible change in the color of the limestone. Protection efficiencies of PLA and PHB polymers were almost the same as that of Paraloid B72, a widely used acrylic polymer. However, PLA and PHB seemed to be favorable polymers as protective agents due to their reversibility and biodegradability, low chromatic changes, good hydrophobic behavior and good stability to weathering in reducing the effects of outdoor exposure on limestone surfaces.