Yilmaz-Savaşkan, Sevil | Abbasoğlu, Rza | Hazer, Baki

Article | 2003 | Journal of Molecular Modeling9 ( 4 ) , pp.230 - 234

The conformational analysis of polynorbornene (PNB) chains was investigated with the AM1, MM2, AMBER and OPLS methods taking into consideration the possibility of binding of norbornene monomers to each other at various positions, i.e. exo-exo, exo-endo, endo-endo. The chain that is formed by connecting exo-endo positions of the monomers has lower torsional barrier energy than those formed with bonds at other positions and has more flexibility. It is determined that the thredisyndiotactic chain formed by exo-endo addition adopts a helix structure and has a coil shape. The disyndiotactic chain formed by connecting norbornene monomers . . .in mixed type has a linear structure. It is found that the repeat unit conformations of thredisyndiotactic and disyndiotactic chains of PNB are TGTG- and (TGTG-)2, respectively Daha fazlası Daha az

Koçer, Halil | Borcaklı, Mehlika | Demirel, Songün | Hazer, Baki

Article | 2003 | Turkish Journal of Chemistry27 ( 3 ) , pp.365 - 373

Poly(3-hydroxy alkanoate)s (PHA)s are bacterial polyesters that have, due to their biodegradability and biocompatibility, attracted considerable industrial interest. All the substrates used in feeding Alcaligenes eutrophus and Pseudomonas oleovorans have been reviewed as far as we know, and some more new substrates or mixtures have been used in PHA production by microorganisms. Alcaligenes eutrophus was fed with 4-pentenoic acid, 2-hydroxy ethyl methacrylate (HEMA), corn oil acids, linseed oil acids and limonene as well as mixtures of acetic acid and glucose or lactose. Either HEMA as a sole carbon source or the mixture of glucose d . . .id not produce polyester; limonene as a sole carbon source gave few dry cells and very few mgl-1 Poly (3-hydroxy butyrate-co-3-hydroxy valerate)(PHBV) containing 5 mol-% of hydroxy valerate (HV) units. Poly(3-hydroxy butyrate), (PHB), was obtained from corn oil acids and the mixture of glucose (15 gl-1) and acetic acid (2.5 gl-1); Poly (3-hydroxy butyrate-co-3-hydroxy valerate) (PHBV) was obtained in moderate yield from 4-pentenoic acid as a sole carbon source and the rest of the substrates above. Pseudomonas oleovorans was fed with linoleic acid, laurel seed oil acids, corn oil acids, laurel leaf oil, rose oil and limonene. Medium chain length polyesters were obtained from linoleic acid, corn oil acids and laurel seed oil acids, but the others did not give any detectable polyester. The polymers obtained were characterized by size exclusion chromatography, 1H and 13C NMR, FT-IR, thermal analysis and fast atom bombardment-mass spectrometer techniques Daha fazlası Daha az

Kopaç, Türkan | Kocabaş, Sefa

Article | 2003 | Chemical Engineering Communications190 ( 05.Aug ) , pp.1041 - 1054

In this study sulfur dioxide adsorption and rate were investigated on molecular sieve 5A zeolite in a packed bed system at 473 K. The experimental adsorption isotherms were compared with Langmuir, Freundlich, and Dubinin-Radushkevitch-Kaganer (DRK) adsorption isotherm models. The simple Langmuir and the Freundlich models provided a better description of sulfur dioxide sorption on molecular sieve 5A zeolite, so that a selective surface adsorption mechanism for adsorption of sulfur dioxide on molecular sieve 5A zeolite can he suggested. The breakthrough behavior for sulfur dioxide adsorption on molecular sieve 5A was also investigated . . . in this study. The experimental breakthrough curves were compared with deactivation models proposed by Orbey et al., and the recent models of Suyadal et al. and Yaşyerli et al. The deactivation models were found to give good agreement with the experimental results Daha fazlası Daha az

Yapar, Tuğba | Hazer, Baki

Article | 2003 | Süleyman Demirel Üniversitesi Burdur Eğitim Fakültesi Dergisi4 ( 6 ) , pp.85 - 98

Bu çalışmada kimyasal maddeler konusunda tümevarım ve tümdengelim içerik yaklaşımları karşılaştırılmıştır. Tümevarım içerik sırasında atomun yapısı ve priyodik tablo, kimyasal bağlar, moleküller arası çekim kuvvetleri, sıvı, katı ve gazların özellikleri ve kimyasal maddeler üniteleri sırasıyla işlenirken, tümdengelimde tam tersi bir sırayla üniteler işlenmiştir. Bu araştırma 1999-2000 güz döneminde 74 öğrenci ile yapılmıştır. Bilişsel işlem beceri testi, çoktan seçmeli test ve yazılı sınav kullanılmıştır. Gözlem ve görüşmede yapılmıştır. Veriler MANOVA istatistiği ile analiz edilmiştir. Yazılı sınava göre gruplar arasında anlamlı fa . . .rklar bulunmuştur. Gözlem ve görüşme sonuçları tümevarım içerik sırasının tümdengelime gore öğrenciler üzerinde daha pozitif etkisi olduğunu göstermektedir The comparison of inductive and deductive content sequence of the concept of chemical substances has been studied. Inductive content sequence was ordered in the structure of atom and periodic table, chemical bonding, intermolecular forces and properties of liquids and solids and chemical substances, while deductive content sequence was reverse. This research was applied on 74 freshman students in 1999-2000 spring terms. The students were equally divided in to two groups which one of the group took chemistry course in deductive content sequence and the other group took inductive content sequence. Science process skill test, multiple choice test and essay type test were applied on these students. Observations and interviews with some students were also made during the course. The data obtained from the tests were analyzed with Multivariate analysis of Variance (MANOVA). After the completion of the content sequence, the students who took the course in inductive content sequence, achieved better than students who took the course in deductive content sequence on essay type test results. Additionally gender resulted not significant on dependent variables. Observations and interviews results indicated that inductive content sequence had positive effect on the students Daha fazlası Daha az