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71.
Cuneyt Sevim Asil Oztekin Ozkan Bali Serkan Gumus Erkam Guresen 《European Journal of Operational Research》2014
The purpose of this paper is to develop an early warning system to predict currency crises. In this study, a data set covering the period of January 1992–December 2011 of Turkish economy is used, and an early warning system is developed with artificial neural networks (ANN), decision trees, and logistic regression models. Financial Pressure Index (FPI) is an aggregated value, composed of the percentage changes in dollar exchange rate, gross foreign exchange reserves of the Central Bank, and overnight interest rate. In this study, FPI is the dependent variable, and thirty-two macroeconomic indicators are the independent variables. Three models, which are tested in Turkish crisis cases, have given clear signals that predicted the 1994 and 2001 crises 12 months earlier. Considering all three prediction model results, Turkey’s economy is not expected to have a currency crisis (ceteris paribus) until the end of 2012. This study presents uniqueness in that decision support model developed in this study uses basic macroeconomic indicators to predict crises up to a year before they actually happened with an accuracy rate of approximately 95%. It also ranks the leading factors of currency crisis with regard to their importance in predicting the crisis. 相似文献
72.
Petra Hoffmann Marcel Hülsewig Sevim Duvar Holger Ziehr Michael Mormann Jasna Peter‐Katalinić Alexander W. Friedrich Helge Karch Johannes Müthing 《Rapid communications in mass spectrometry : RCM》2010,24(15):2295-2304
Shiga toxin (Stx, synonymous to verotoxin, VT) binds with high and low affinity to the globo‐series neutral glycosphingolipids (GSLs), globotriaosylceramide (Gb3Cer or Galα4Galβ4Glcβ1Cer, also known as CD77) and globotetraosylceramide (Gb4Cer or GalNAcβ3Galα4Galβ4Glcβ1Cer), respectively, which represent the targets of Stxs on many different cell types. B‐cell‐derived Raji cells and THP‐1 cells of monocytic origin are widely used for the investigation of Stx‐mediated cellular response, because Stx is known to cause cell death in both cell lines. Despite their functional importance, the Stx receptors of Raji and THP‐1 cells have so far not been investigated. This prompted us to explore the structures of their GSL receptors in detail by means of nanoelectrospray ionization quadrupole time‐of‐flight mass spectrometry (nanoESI‐QTOF‐MS) with collision‐induced dissociation (CID) in conjunction with Stx1 as well as anti‐Gb3Cer and anti‐Gb4Cer antibodies. Using the combination of a thin‐layer chromatography (TLC) overlay assay and MS1 and MS2 analysis we identified Gb3Cer (d18:1, C24:1/C24:0) as the prevalent Stx1‐receptor accompanied by less abundant Gb3Cer (d18:1, C16:0) in the neutral GSL fraction of Raji cells. The same Gb3Cer species but with almost equal proportions of the C24:1/C24:0 and C16:0 variants were found in THP‐1 cells. In addition, unusual hydroxylated Gb3Cer (d18:1, C24:1/C24:0) and Gb3Cer (d18:1, C26:1) could be identified in trace quantities in both cell lines. As the most obvious difference between Raji and THP‐1 cells we observed the expression of Gb4Cer in THP‐1 cells, whereas Raji cells failed to express this elongation product of Gb3Cer. Both short‐ and long‐chain fatty acid carrying Gb4Cer (d18:1, C16:0) and Gb4Cer (d18:1, C24:1/C24:0), respectively, were the prevalent Gb4Cer variants. This first report on the differential expression of Gb3Cer and Gb4Cer and their structural diversity in lymphoid and myeloid cell lines supports the hypothesis that such heterogeneities might play a functional role in the molecular assembly of GSLs in membrane organization and cellular signaling of Stx‐susceptible cells. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
73.
Poly(4-vinylbenzeneboronic acid), PVBBA was synthesized via free-radical polymerization of 4-vinylbenzeneboronic acid (4-VBBA) and followed by crosslinking with polyethylene glycol (PEG) with different molecular weights to produce boron containing crosslinked polymers. Prior to crosslinking, the materials were doped with CF3SO3Li at several stoichiometric ratios to get PVBBAPEGX-Y where X is the molecular weight of PEG and Y is the EO/Li ratio. The materials were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The ionic conductivity of these novel crosslinked electrolytes was studied by dielectric-impedance spectroscopy. Li-ion conductivity of these polymer electrolytes depends on the length of the side units as well as the doping ratio. PVBBAPEG200-10 illustrated a satisfactory ionic conductivity of 3.1 × 10?5 S/cm at 20 °C and 1.8 × 10?3 S/cm at 100 °C. 相似文献
74.
Mehmet Sirin Tutgun Deniz Sinirlioglu Sevim Unugur Celik Ayhan Bozkurt 《Ionics》2015,21(10):2871-2878
The preparation, thermal, morphological, and ion-conducting properties of new composite membranes based on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and nitrilotri(methylphosphonic acid) (NMPA)/hexagonal boron nitride (hBN) were carried out throughout this work. Fourier transform infrared (FTIR) spectroscopy was used to characterize the interactions between host polymer, NMPA, and inorganic additive, hBN. Thermal properties of the materials were examined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests. TGA results illustrated that all composite membranes are thermally stable up to 200 °C. The surface topography of the films was investigated by scanning electron microscopy (SEM) and verified that hBN uniformly dispersed into the PAMPS-NMPA matrix. The crystallinity of the membranes was characterized by using X-ray diffraction (XRD). X-ray patterns support semicrystalline nature of the composite materials. At anhydrous conditions, the maximum proton conductivity was found as 3.2?×?10?5 S cm?1 at 150 °C for PAMPS-NMPA-3hBN via impedance analyzer. 相似文献
75.
Abstract The structure, C16H14CdN6Ni, consist of corrugated polymeric networks made up of tetracyanonickelate ions coordinated to Cd. The 4-methyl pyridine molecules bound to Cd in trans positions are located on both sides of the network. The bonding in the networks occurs because of a departure of the Ni-C-N-Cd sequence of atoms from linearity at the C and N positions. The crystal structure of the title compound was determined as monoclinic by single crystal X-Ray diffraction technique. The crystal parameters of this compound are as follows: monoclinic C2/m, a=18.156(2) Å, b=7.581(2) Å. c= 6.983(2) Å, β = 110.09(2)°, V = 902.6(5) Å3 Z=2, Dx = 1.698 g/cm3, F(000) - 456, λ (MoKα) = 0.71070 Å, μ = 2.121 mm?1. The structure was solved by SHELXS-86 and refined by SHELXL-93. R = 0.02 for 1074 observed reflections with I > 2[sgrave] (I). 相似文献
76.
Sevim Akyüz 《Journal of inclusion phenomena and macrocyclic chemistry》1985,3(4):403-407
The results of an infrared and Raman spectroscopic study are reported for two new metal 2-methylpyridine tetracyanonickelate complexes, M(C6H7N)2Ni(CN)4, M=Ni or Cd. Their structure consists of corrugated polymeric layers of {M-Ni(CN)4} with 2-methylpyridine molecules bound directly to the metal (M). These complexes can act as host lattices in the formation of inclusion compounds with dioxane guest molecules. 相似文献
77.
A new calcium(II) complex of the saccharinate ligand (sac) with 2—hydroxyethylpyridinium (Hpyet) was synthesized and characterized by elemental analysis, FT—IR spectroscopy, thermal analysis and single crystal X—ray diffractometry. The [Ca(sac)2(H2O)2(Hpyet)2](sac)2 complex crystallizes in the triclinic space group (P1¯) with the cell dimensions a = 7.4360(7)Å, b = 12.5263(12)Å, c = 12.8329(13)Å, α = 82.534(8)°, β = 75.202(8)° and γ = 89.662(8)° (293 K). The title complex consists of a complex cation and two sac anions. In the complex cation, the calcium(II) ion is six—coordinate, bonding to two aqua ligands, two Hpyet ligands andtwo sac ligands located in the trans positions. Two of the sac ions are coordinated to the calcium(II) ion through the carbonyl O atom, while the other two remain outside the coordination sphere as the counter—ions. Thermal decomposition of the complex in air results in elimination of aqua, Hpyet, and sac ions, respectively. 相似文献
78.
Nurcan Ekici Ziya Kantarci Sevim Akyüz 《Journal of inclusion phenomena and macrocyclic chemistry》1991,10(1):9-18
Two new benzene clathrates of the form Cd(Pyrazine)M(CN)4C6H6, where M = Cd or Hg, have been prepared and their infrared and Raman spectra are reported. 相似文献
79.
Sevim Akyüz Andrew B. Dempster J.Eric D. Davies Kerry T. Holmes 《Journal of Molecular Structure》1977
The time-dependent changes which are observed in the infrared and Raman spectra of samples of the two Hofmann aniline clathrates M(NH3)2Ni(CN)4.an2 {M = Cd(II), Ni(II), an = C6H5NH2} indicate the occurrence of a solid state ligand replacement reaction in which the aniline guest molecule replaces the coordinated ammonia to give Man2Ni(CN)4 as the final product. The rate of replacement is greater for the cadmium than for the nickel clathrate, and for both clathrates evacuation of the sample greatly increases the rate of replacement. The Man2Ni(CN)4 complexes can themselves act as host lattices forming clathrates containing guest molecules such as aniline. 相似文献
80.
Infrared (4000?200 cm?1) and Raman (3500?50 cm?1) spectra are reported for metal(II) halide aniline complexes of the following stoichiometries: (MX2an2) (M Co, Ni or Hg, X Cl; M Mn, X Cl or Br; M Zn or Cd, X Cl, Br or I); (MX2an3) (M Mn, X Cl or Br; M Ni, X Cl); (CdCl2an) and an assignment is proposed for all the observed bands. Low-temperature (83 K) IR spectra are also reported and it is noted that whilst the aniline ring and CH mode values are virtually insensitive to temperature, the NH2 rocking and metal-ligand stretching mode values increase with decreasing temperature, whilst the NH2 stretching mode values decrease with decreasing temperature. 相似文献