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61.
Semanur Parlayan Aysel Başoğlu Yasemin Göbel Miraç Ocak Hakan Alp Halit Kantekin Ümmühan Ocak 《Journal of inclusion phenomena and macrocyclic chemistry》2010,67(3-4):451-460
A new 14-membered crown ether with nitrogen–sulfur donor atom carrying two anthryl groups was designed and synthesized by the reaction of the corresponding macrocyclic compound and 9-(chloromethyl) anthracene. The influence of metal cations such as Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ on the spectroscopic properties of the ligand was investigated in acetonitrile–dioxane solution (1/1) by means of absorption and emission spectrometry. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constant of the novel ligand with Fe2+, Fe3+, Al3+, Cd2+, Cu2+, Zn2+, Pb2+ and Hg2+ cations. Absorption spectra show isobestic points in the spectrophotometric titration of these cations. The presence of excess of Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ cations caused an enhancement of anthryl fluorescence. Especially, the enhancement in case of the interaction of Hg2+ and Al3+ cations with the ligand was pronounced. 相似文献
62.
Hasan Tanak Yavuz Köysal Yasemin Ünver Metin Yavuz Şamil Işık Kemal Sancak 《Structural chemistry》2009,20(3):409-416
The Imidazole compound, Ethyl N′-3-(1H-imidazol-1-yl) propylcarbamoyl benzohydrazonate monohydrate, has been synthesized and
characterized by IR, NMR, electronic spectroscopy, and X-ray single-crystal determination. Molecular geometry from X-ray experiment
of the title compound in the ground state has been compared using the density functional method (B3LYP) with 6-31G+(d) basis
set. To determine conformational flexibility, molecular energy profile of the title compound was obtained by DFT calculations
with respect to two selected degrees of torsional freedom, which were varied from −180° to +180° in steps of 10°. Besides,
molecular electrostatic potential (MEP), natural bond orbitals (NBO), frontier molecular orbitals (FMO), and thermodynamic
properties were performed at B3LYP/6-31G+(d) level of theory. 相似文献
63.
Berg Peter; Caglar Atife; Promislow Keith; St-Pierre Jean; Wetton Brian 《IMA Journal of Applied Mathematics》2006,71(2):241-261
** Corresponding author. Email: wetton{at}math.ubc.ca*** Email: Peter.Berg{at}uoit.ca**** Email: caglara{at}uwgb.edu***** Email: kpromisl{at}math.msu.edu****** Email: jean.st-pierre{at}ballard.com A mathematical model describing the effects of electrical couplingof proton exchange membrane unit fuel cells through shared bipolarplates is developed. Here, the unit cells are described by simple,steady-state, 1D models appropriate for straight reactant gaschannel designs. A linear asymptotic version of the model isused to give analytic insight into the effect of the coupling,including estimates of the extent of the coupling in terms ofthe number of adjacent cells affected. An efficient numericalmethod is developed to solve the non-linear coupled system.Numerical results showing the effects on stack voltage due toa single cell with anomalous oxidant flow rate are given. Theeffects on stack performance due to end plate effects are alsogiven. It is shown that electrical coupling has a significanteffect on fuel cell performance. 相似文献
64.
Yasemin Yüksel Durmaz Görkem Yilmaz Yusuf Yağci 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):423-428
Photoactive N‐alkoxy 4‐phenyl pyridinium and N‐alkoxy isoquinolinium ion terminated polystyrenes with hexafluoroantimonate counter anion were prepared and characterized. For this purpose, mono‐ and dibrominated polystyrenes were prepared by atom transfer radical polymerization (ATRP). The reaction of these polymers with silver hexafluoroantimonate in the presence of 4‐phenylpyridine N‐oxide and isoquinoline N‐oxide in dichloromethane produced desired polymeric salts with the corresponding functionalities. Irradiation of these photoactive polystyrenes produced alkoxy radicals at chain ends capable of initiating free radical polymerization of methyl methacrylate (MMA). This way, depending on the number of functionality, AB or ABA type block copolymers were formed which were characterized with the aid of gel permeation chromatography and 1H NMR spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 423–428, 2007. 相似文献
65.
Undoped and tin (Sn) doped ZnO films have been deposited by sol gel spin coating method. The Sn/Zn nominal volume ratio was 1, 3 and 5% in the solution. The effect of Sn incorporation on structural and electro-optical properties of ZnO films was investigated. All the films have polycrystalline structure, with a preferential growth along the ZnO (002) plane. The crystallite size was calculated using a well-known Scherrer's formula and found to be in the range of 26-16 nm. X-ray diffraction patterns of the films showed that Sn incorporation leads to substantial changes in the structural characteristics of ZnO films. The SEM measurements showed that the surface morphology of the films was affected from the Sn incorporation. The highest average optical transmittance value in the visible region was belonging to the undoped ZnO film. The optical band gap and Urbach energy values of these films were determined. The absorption edge shifted to the lower energy depending on the Sn dopant. The shift of absorption edge is associated with shrinkage effect. The electrical conductivity of the ZnO film enhanced with the Sn dopant. From the temperature dependence of conductivity measurements, the activation energy of ZnO film increased with Sn incorporation. 相似文献
66.
Two trans‐bis(saccharinato) (sac) complexes of cadmium(II ) with 2‐aminomethylpyridine (ampy) and 2‐aminoethylpyridine (aepy) were synthesized and characterized by means of elemental analysis, FT‐IR spectroscopy and thermal analysis. In addition, their solid‐state structures were determined by single crystal X‐ray diffraction studies. The [Cd(sac)2(ampy)2] ( 1 ) and [Cd(sac)2(aepy)] ( 2 ) complexes consist of neutral monomeric units and crystallize in the orthorhombic (Pbca) and monoclinic (P21/c) crystal systems, respectively. The cadmium(II ) ions in 1 and 2 sit on inversion centres andexhibit distorted octahedral coordination by two sac anions and two aminopyridine ligands. The sac ligands in both complexes are N‐coordinated and located in trans positions, while the ampy and aepy ligands act as a bidentate ligand forming two symmetrically chelate rings around cadmium(II ). IR spectra and thermal decompositions of the complexes are also discussed. 相似文献
67.
Cationic PLA nanoparticles for DNA delivery: comparison of three surface polycations for DNA binding, protection and transfection properties 总被引:6,自引:0,他引:6
Munier S Messai I Delair T Verrier B Ataman-Onal Y 《Colloids and surfaces. B, Biointerfaces》2005,43(3-4):163-173
Biodegradable cationic nanoparticles (cNP) made of poly(lactide) (PLA) have been shown to be promising carrier systems for in vivo DNA delivery and immunization. In previous work, we have described a versatile approach for the elaboration of cationic PLA cNP based on the use of pre-formed particles and subsequent adsorption of a model polycation, the poly(ethylenimine) (PEI). Here, we evaluated two more polycations, chitosan and poly(2-dimethyl-amino)ethyl methacrylate (pDMAEMA)) to determine the most suitable one for the development of PLA cNP as DNA carriers. Cationic PLA-PEI, PLA-chitosan and PLA-pDMAEMA nanoparticles were compared for interaction with plasmid DNA and, more importantly, with regards to the biological properties of bound DNA. pDMAEMA coating yielded the most positively charged nanoparticles with the highest DNA binding capacity (32 mg/g). Loaded with DNA, all three cNP were in the same size range ( approximately 500 nm) and had a negative zeta potential (-50 mV). PLA-chitosan was the only cNP that released DNA at pH 7; the two others required higher pH. Adsorption and release from cNP did not alter structural and functional integrity of plasmid DNA. Moreover, DNA coated onto cNP was partially protected from nuclease degradation, although this protection was less efficient for PLA-chitosan than others. The highest transfection efficiency in cell culture was obtained with PLA-pDMAEMA carriers. We have shown that at least three different cationic polymers (chitosan, PEI, pDMAEMA) can be used for the production of PLA-based particulate DNA carriers and most probably other cationic polymers can also be used in the same purpose. PLA-pDMAEMA cNP were the most promising system for DNA delivery in this in vitro study. Our future work will focus on the in vivo evaluation of these gene delivery systems. 相似文献
68.
Alemdar Bayraktar Ahmet Can Altunişik Barış Sevim Murat Emre Kartal Temel Türker Yasemin Bilici 《Nonlinear dynamics》2009,58(4):655-673
In this paper, it is aimed to compare the near- and far-fault ground motion effects on the nonlinear dynamic response of dams
including dam–reservoir–foundation interaction. Two different types of dams, which are concrete arch and concrete faced rockfill
dams, are selected to investigate the near- and far-fault ground motion effects on the dam responses. The behavior of reservoir
water is taken into account using Lagrangian approach. The Drucker–Prager material model is employed in nonlinear analyses.
Near and far-fault strong ground motion records, which have approximately identical peak ground accelerations, of Loma Prieta
(1989) earthquake are selected for the analyses. Displacements, maximum and minimum principal stresses are determined using
the finite element method. The displacements and principal stresses obtained from the analyses of dams subjected to each fault
effect are compared with each other. It is clearly seen that there is more seismic demand on displacements and stresses when
the dam is subjected to near-fault ground motion. 相似文献
69.
Gülen Ferah Kemal Colakoglu Yasemin Oztekin Ciftci Soner Ozgen Sefa Kazanc 《Central European Journal of Physics》2007,5(2):207-220
In this study, molecular dynamics simulations are performed by using a modified form of Morse potential function in the framework
of the Embedded Atom Method (EAM). Temperature-and pressure-dependent behaviours of bulk modulus, second-order elastic constants
(SOEC), and the linear-thermal expansion coefficient is calculated and compared with the available experimental data. The
melting temperature is estimated from 3 different plots. The obtained results are in agreement with the available experimental
findings for iridium.
相似文献
70.
Y. Caglar S. Ilican M. Caglar 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(3):251-256
It has recently been shown that growth of a multilayer
structure with one or more delta-layers at high temperature leads to
spreading and asymmetrization of the dopant distribution [see, for
example, E.F.J. Schubert, Vac. Sci. Technol. A. 8, 2980 (1990), A.M. Nazmul, S. Sugahara, M. Tanaka, J. Crystal Growth 251, 303 (2003); R.C. Newman, M.J. Ashwin, M.R. Fahy, L. Hart, S.N. Holmes, C. Roberts, X. Zhang, Phys. Rev. B 54, 8769 (1996); E.F. Schubert, J.M. Kuo, R.F. Kopf, H.S. Luftman, L.C. Hopkins, N.J. Sauer, J. Appl. Phys. 67, 1969 (1990); P.M. Zagwijn, J.F. van der Veen, E. Vlieg, A.H. Reader, D.J. Gravesteijn, J. Appl. Phys. 78, 4933 (1995); W.S. Hobson, S.J. Pearton, E.F. Schubert, G. Cabaniss, Appl. Phys. Lett. 55, 1546 (1989); Delta Doping of Semiconductors, edited by E.F. Schubert (Cambridge University Press, Cambridge, 1996); Yu.N. Drozdov, N.B. Baidus', B.N. Zvonkov, M.N. Drozdov,
O.I. Khrykin, V.I. Shashkin, Semiconductors 37, 194 (2003); E. Skuras, A.R. Long, B. Vogele, M.C. Holland, C.R. Stanley, E.A. Johnson, M. van der Burgt, H. Yaguchi, J.
Singleton, Phys. Rev. B 59, 10712 (1999); G. Li, C. Jagadish, Solid-State Electronics 41, 1207 (1997)]. In this
work analytical and numerical analysis of dopant dynamics in a
delta-doped area of a multilayer structure has been accomplished
using Fick's second law. Some reasons for asymmetrization of a
delta-dopant distribution are illustrated. The spreading of a
delta-layer has been estimated using example materials of a
multilayer structure, a delta-layer and an overlayer. 相似文献