WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 15Citation - Scopus: 18Preparation and Characterization of Magnesium Stearate, Cobalt Stearate, and Copper Stearate and Their Effects on Poly(vinyl Chloride) Dehydrochlorination(John Wiley and Sons Inc., 2015) Gönen, Mehmet; Egbuchunam, Theresa Obuajulu; Ülkü, Semra; İnal, Fikret; Balköse, Devrim; İnal, Fikret; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyPreparation and characterization of pure metal soaps and investigation of their effects on poly(vinyl chloride) (PVC) dehydrochlorination were the objectives of the present study. Magnesium stearate (MgSt2), cobalt stearate (CoSt2), and copper stearate (CuSt2) were prepared by a precipitation method. An aqueous sodium stearate (NaSt) solution was mixed at 500 rpm with respective metal salt solutions at 75oC. The precipitates that formed were collected by filtration, washed with water, and ultimately dried at 105oC under reduced pressure. Lamellar crystals that melted on heating were obtained. Solid-liquid phase transitions were observed by optical microscopy at 160oC, 159oC, and 117oC for MgSt2, CoSt2, and CuSt2, respectively. However, the melting points of MgSt2, CoSt2, and CuSt2 were determined as 115oC, 159oC, and 111oC, respectively, by analysis by differential scanning calorimetry. The onset temperature of the mass loss was the lowest at 255oC for CuSt2 and the lowest activation energy for thermal decomposition was 18 kJ/mol for CuSt2. CoSt2 was effective in extending the induction time of PVC dehydrochlorination at both 140oC and 160oC. The activation energy calculated from stability time decreased from 175 kJ/mol for a blank PVC sample to 114, 105, and 107 kJ/mol for MgSt2, CoSt2, and CuSt2-containing PVC samples, respectively. All three metal soaps accelerated the dehydrochlorination of PVC. J. VINYL ADDIT. TECHNOL., 21:235-244, 2015.Article Citation - WoS: 4Citation - Scopus: 4Pentobarbital-Mediated Regulation of Alternative Polyadenylation in Drosophila Glutathione S-Transferase D21 Mrnas(American Society for Biochemistry and Molecular Biolog, 2004) Akgül, Bünyamin; Akgül, Bünyamin; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyTwo nearly identical, gstD21(L) and gstD21(S) mRNAs whose polyadenylation sites differ by 19 nucleotides, are transcribed from the intronless glutathione S-transferase D21 gene in Drosophila. Both mRNAs are intrinsically very labile, but exposure to pentobarbital renders them stabilized beyond what can be attributed to transcriptional activation. We have reconstituted this PB-mediated mRNA stabilization in a transgene (D21L) that contains the full-length gstD21(L) sequence. We have also constructed a similar transgene (D21L-UTR), which matches D21L but excluded the native 3′-UTR. D21L-UTR produces a relatively stable RNA, whose stability is unaffected by pentobarbital. Following pentobarbital treatment of wild-type flies, the levels of gstD21(L) and gstD21(S) mRNAs hold at a relatively constant ratio (L/S) of 1.4 ± 0.2. In transgenic flies, heat shock induction of D21L mRNA changed the L/S ratio to 0.6 ± 0.1, and it was further reduced to 0.3 ± 0.1 as D21L mRNA accumulated in the presence of PB. The ratio returned nearly normal (1.1 ± 0.1) as the D21L mRNA decayed over 12 h after terminating induction. In constrast, when D21L-UTR was present, the ratio remained constant (1.7 ± 0.2) even under various induction conditions and during recovery. Thus, the 3′-UTR, which was the critical difference between these two transgenes, must have some role in determining the L/S ratio. Induced D21L mRNA alone is not sufficient to cause reversible changes in the ratio. Such changes require the presence of pentobarbital. Therefore, pentobarbital may regulate this L/S ratio by affecting the choice of polyadenylation sites for the gstD21 mRNAs through sensing the concentrations of the native 3′-UTR sequences.Article Citation - WoS: 70Citation - Scopus: 84Mechanical Properties and Microstructural Evaluation of Aa5013 Aluminum Alloy Treated in the Semi-Solid State by Sima Process(Elsevier Ltd., 2004) Saklakoğlu, Nurşen; Tanoğlu, Metin; Tanoğlu, Metin; Öztaş, Özgü; Çubukcuoğlu, Önder; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe microstructure and mechanical properties of AA5013 aluminum alloys prepared by strain-induced melt activation (SIMA) process were studied to investigate the effects of cold working and heat treatment conditions. The specimens subjected to deformation ratios of 30 and 50% and various heat treatment time and temperature regimes were characterized in the present study. The results revealed that for the desired microstructure of the alloy, the optimum heat treatment temperature and time were 650°C and 60min, respectively, for both deformation ratios. However, the specimens with 50% cold working exhibited more brittle behavior while they contain finer grains with uniform distribution along the cross-sections as compared to 30% cold working.