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41.
Cell suspension cultures of Lavandula angustifolia Mill. ssp. angustifolia (syn.: L. officinalis Chaix.) afforded a fatty acid composition, cis and trans p-coumaric acids (=p-hydroxy cinnamic acids), and beta-sitosterol. The fatty acid composition was analyzed by GC-MS, and the structures of the isolated three compounds were determined by 1H- and 13C-NMR, and MS spectroscopic techniques. 相似文献
42.
A new derivate of 4-bromo-1,8-naphthalic anhydride and its quaternized analogue have been prepared and characterized. The interactions of both derivatives with human telomere quadruplex-DNA and ds-DNA have been comparatively studied by UV-visible (UV-Vis), fluorescent intercalator displacement assays, competition dialysis, circular dichroism (CD), agarose gel electrophoresis, and polyacrylamide gel electrophoresis. The results show that both derivatives can stabilize G-quadruplexes DNA, and they show different binding affinities for G-quadruplexes-DNA and ds-DNA. All spectroscopic studies have shown that the derivatives have a modest selectivity for G-quadruplex versus ds-DNA. 相似文献
43.
Supply chain inventories are prone to fluctuations and instability. Known as the bullwhip effect, small variations in the end item demand create oscillations that amplify throughout the chain. By using system dynamics simulation, we investigate some of the structural sources of the bullwhip effect, and explore the effectiveness of information sharing to eliminate the undesirable fluctuations. Extensive simulation analysis is carried out on parameters of some standard ordering policies, as well as external demand and lead-time parameters. Simulation results show that (i) a major structural cause of the bullwhip effect is isolated demand forecasting performed at each echelon of the supply chain, and (ii) demand and forecast sharing strategies can significantly reduce the bullwhip effect, even though they cannot completely eliminate it. We specifically show how each policy is improved by demand and forecast sharing. Future research involves more advanced ordering and forecasting methods, modelling of other well-known sources of bullwhip, and more complex supply network structures. 相似文献
44.
Ozgun Daglar Begum Gungor Gulce Guric Ufuk Saim Gunay Gurkan Hizal Umit Tunca Hakan Durmaz 《Journal of polymer science. Part A, Polymer chemistry》2020,58(6):824-830
In this study, two types of hyperbranched (HB) polythioether could readily be achieved in a short time at ambient temperature through a thiol-Michael addition reaction. Dimethyl acetylenedicarboxylate (DMADC) or methyl propiolate (A2) and trimethylolpropane tris(3-mercaptopropionate) (B3) monomers were reacted using an organobase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a catalyst in chloroform at room temperature to provide subsequent HB polythioethers. The effect of TBD concentration on the polymerization was studied for the DMDAC case monitoring the molecular weight evolution against time. HB polythioethers were characterized using spectroscopic (nuclear magnetic resonance) and chromatographic (gel permeation chromatography with refractive index and light-scattering detectors) techniques. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 824–830 相似文献
45.
Elif Baysak Ozgun Daglar Ufuk Saim Gunay Gurkan Hizal Umit Tunca Hakan Durmaz 《Journal of polymer science. Part A, Polymer chemistry》2018,56(19):2145-2153
Two different oxanorbornene monomers were prepared and copolymerized with butyl-functionalized oxanorbornene monomer through the ring-opening metathesis polymerization. The resulting polymers were then subjected to the aminolysis reactions with propylamine (PA) in the presence of methyl acrylate (MA) to capture, in situ, the latent thiol. It was found that the polymer, in which the thiolactone unit is close to the polymer backbone, did not undergo an efficient aminolysis reaction even an excess amount of PA was utilized, while the other polymer, in which the thiolactone unit away from the polymer backbone, did efficiently undergo aminolysis reaction even PA was used in low amounts. Besides, a variety of primary amine compounds along with MA were reacted with the polymer, in which the thiolactone group away from the polymer backbone, to test their reactivity toward the aminolysis reactions. All modified polymers were characterized by using conventional instruments such as gel permeation chromatography, nuclear magnetic resonance, and differential scanning calorimetry. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2145–2153 相似文献
46.
47.
Ufuk Taneri 《Journal of mathematical chemistry》1997,21(1):111-113
Bifurcations and stability of a molecular system are analyzed via a method which combines a perturbation skim with Harmonic
Balancing.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
48.
Ufuk Kumru Fabienne Dumoulin Erwann Jeanneau Fatma Yuksel Yari Cabezas Yunus Zorlu Vefa Ahsen 《Structural chemistry》2012,23(1):175-183
Three tert-butylsulfanylphthalonitriles have been prepared with optimized synthetic procedures. Their comparative structural analyses
have been completed, with a focus on IR and NMR spectroscopy and refined X-ray structural data. Miscellaneous parameters such
as UV absorption, melting points, and related polarity of the compounds are summarized. 相似文献
49.
Bilal Bugra Uysal Ufuk Saim Gunay Gurkan Hizal Umit Tunca 《Journal of polymer science. Part A, Polymer chemistry》2014,52(11):1581-1587
Aliphatic polycarbonate (PC) copolymer is synthesized by ring opening copolymerization of acrylate‐ and allyl‐functional cyclic carbonate monomers. The post‐polymerization functionalization of the resulting copolymer is performed quantitatively using a variety of thiol compounds via sequential Michael addition and photo‐induced radical thiol‐ene click reactions within relatively short reaction time at ambient temperature. This metal‐free click chemistry methodology affords the synthesis of biocompatible PC copolymer with multifunctional groups. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1581–1587 相似文献
50.
A novel polymeric metal-free phthalocyanine (M = 2H) and its metal complexes (M = Zn, Cu, Co and Ni) were prepared by the tetramerization reaction of 3,6,9-Tris(p-tolylsulfonyl)-1,11-bis(3,4-dicyanophenoxy)-3,6,9-triazaundecane 5 with the appropriate materials. The electrical conductivities of the metal-free phthalocyanine and the metal complexes, measured in air, were found to be ∼10−6–10−5 S m−1. The aggregation property of the zinc complex 7 was investigated with Ni2+, Cu2+, Co2+, Pb2+, Cd2+ and Ag+ cations. Thermal analysis of the polymers were done by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) at a heating rate of 10 °C min−1 under a nitrogen atmosphere. All the novel compounds were characterized by using elemental analysis, UV–Vis, FT–IR, NMR and MS spectral data and DSC, DTA/TG techniques. 相似文献