Vefa Ahsen, Emel Yilmazer, Özer Bekâroĝlu, Ahmet Gül, Özer Bekâroĝlu,
... ether moieties and its alkali metal binding property Vefa Ahsen, Vefa Ahsen TUBITAK — Research Institute for Basic Sciences, Department ... Istanbul, TurkeySearch for more papers by this author Vefa Ahsen, Vefa Ahsen TUBITAK — Research Institute for Basic Sciences, Department ...
Tópico(s): Organic Chemistry Cycloaddition Reactions
1987 - Wiley | Die Makromolekulare Chemie Rapid Communications
Salvador Almagro‐Moreno, Michael G. Napolitano, E. Fidelma Boyd,
... VC1758) , and two putative recombination directionality factors (RDFs), vefA (VC1785) and vefB (VC1809) encoded within VPI-2. We demonstrate that along with IntV2, the RDF VefA is essential for excision. We constructed a knockout mutant of vefA in V. cholerae N16961, and found that no ... of VPI-2 occurred, indicating that a functional vefA gene is required for excision. Deletion of the ...
Tópico(s): Salmonella and Campylobacter epidemiology
2010 - BioMed Central | BMC Microbiology
... I am indebted to my colleagues Nicholas Lash, Vefa Tarhan, Timothy Thompson, and Harvey Zabinsky at Loyola ... I am indebted to my colleagues Nicholas Lash, Vefa Tarhan, Timothy Thompson, and Harvey Zabinsky at Loyola ...
Tópico(s): Accounting Education and Careers
1984 - Wiley | The Journal of Finance
Thierry Toupance, Vefa Ahsen, Jacques Simon,
... and Poly(ethylene oxide)-Substituted Lutetium BisphthalocyaninesThierry Toupance, Vefa Ahsen, and Jacques SimonCite this: J. Am. Chem. ...
Tópico(s): Molecular Sensors and Ion Detection
1994 - American Chemical Society | Journal of the American Chemical Society
... 1Istanbul Universitesi, Deniz Bilimleri ve Işletmeciliği Enstitüsü, 34470, Vefa, Istanbul-Turkey Search for other works by this ... 1Istanbul Universitesi, Deniz Bilimleri ve Işletmeciliği Enstitüsü, 34470, Vefa, Istanbul-Turkey Niyazi Avsar 2Çukurova Universitesi, Mühendislik-Mimarlık ...
Tópico(s): Astro and Planetary Science
2004 - Micropaleontology Press | Micropaleontology
Tópico(s): Corporate Finance and Governance
1980 - Wiley | Journal of money credit and banking
Vefa Ahsen, Özer Bekacaronroĝlu,
Abstract 1, 3-Dipheny1-4, 5-bis(hydroxyimino)imidazolidine (LH2) has been prepared from anti-dichloroglyoxime, N,N′-diphenylmethylenediamine, and sodium bicarbonate in ethanol. Complexes of Cu(II), Ni(II), Co(II), Pd(II), and UO2(VI) and LH2 give a metal-ligand ratio of 1:2. A tetrahedral complex is obtained for the Ni(II) complex by coordination through N and O atoms. The (LH2)Co. H2O complex is squarepyramidal while the Cu(II), Pd(II) and UO2(VI) complexes are square-planar. The structures of the ...
Tópico(s): Synthesis and Characterization of Heterocyclic Compounds
1985 - Taylor & Francis | Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry
Vefa Ahsen, Emel Musluoǧlu, Ayşegül Gürek, Ahmet Gül, Özer Bekâroĝlu, Margareta Zehnder,
Abstract A new vicinal dioxime ligand with two crown‐ether groups, 1,2‐bis[(monoaza[15]crown‐5)‐ N ‐Yl]‐glyoxime(LH 2 ), has been prepared from cyanogen di‐ N ‐oxide and monoaza[15]crown‐5. Ni(II), Pd(II), and Pt(IV) complexes of LH 2 with or without alkali‐metal ions bound to macrocyclic groups have been isolated. The high affinity of [Pd(LH) 2 ] and [Ni(LH) 2 ] for the K + ion is observed in solvent extraction experiments. A single‐crystal X‐ray structure confirms the postulated geometry of [Pd(LH) 2 ]‐ The Pd‐ ...
Tópico(s): Metal-Catalyzed Oxygenation Mechanisms
1990 - Wiley | Helvetica Chimica Acta
Vefa Ahsen, Ayşegül Gürek, Ahmet Gül, Özer Bekâroĝlu,
2,3-Bis(hydroxyimino)-1,4,7,11-tetrathiacyclotridecane (H2L) has been prepared from 1,9-dimercapto-3,7-dithianonane and anti-dichloroglyoxime. Only mononuclear complexes with a metal–ligand ratio of 1:2 have been isolated with NiII and CoII; CuII and PdII form only trinuclear complexes. The reaction of the mononuclear complexes with CuII and PdII gives heterotrinuclear complexes. Tetrahedral distortion of the 13-membered macrocycle is observed in the paramagnetic [Pd3(HL)2]Cl4 and [Pd2Ni(HL)2]Cl4 compounds. ...
Tópico(s): Lanthanide and Transition Metal Complexes
1990 - Royal Society of Chemistry | Journal of the Chemical Society. Dalton transactions
This paper investigates the reason why innovations in money-supply announcements cause interest rates to change. The paper empirically discriminates between the liquidity premium and the expected inflation hypotheses by directly taking into account investors expectations regarding the Federal Reserve's monetary policy stance. The results support the liquidity premium hypothesis, and the model provides an explanation for the observed time variation in the response of interest rates to money announcement ...
Tópico(s): Fiscal Policy and Economic Growth
1990 - Wiley | Journal of money credit and banking
Although money stock targeting has been the strategic focus of Federal Reserve policy since the mid-1970's, operating policy — the tactics whereby the longer-run strategy is implemented over short-term intervals — has been changed by the Federal Reserve at least twice over this period. A particularly dramatic change in operating policy was announced by the Federal Reserve in October 1979. This paper provides empirical evidence that settles questions about the nature of this change and suggests that ...
Tópico(s): Economic, financial, and policy analysis
1987 - Elsevier BV | Journal of Monetary Economics
Vefa Ahsen, Füsun Gökçeli, Özer Bekâroĝlu,
SS′-Bis(4′-benzo[15-crown-5])dithioglyoxime (H2L) has been prepared from 4′-mercaptobenzo[15-crown-5], anti-dichloroglyoxime, and sodium bicarbonate in ethanol. Nickel(II), palladium(II), platinum(II), copper(II), cobalt(II), and cobalt(III) complexes of H2L have a metal–ligand ratio of 1:2 and the ligand co-ordinates through the two N atoms, as do most of the vic-dioximes. The complex [Pt(HL)2Cl2·4NaClO4] forms six-membered chelate rings and co-ordinates through N and O atoms. [Co(HL)2(PPh3)Cl·4NaClO4] ...
Tópico(s): Trace Elements in Health
1987 - Royal Society of Chemistry | Journal of the Chemical Society. Dalton transactions
M. ERTAS, Vefa Ahsen, Ahmet Gül, Özer Bekâroĝlu,
1,10-Dithia-4,7-diaza-5,6-bis(hydroxyimino)[10](1,1′)ferrocenophane has been prepared by the reaction of S,S′-bis(aminoethyl)(1,1′)dithiaferrocene with anti-di-chloroglyoxime. The nickel(II) complex of the new ligand has been isolated.
Tópico(s): Organometallic Compounds Synthesis and Characterization
1987 - Elsevier BV | Journal of Organometallic Chemistry
Abstract The relationship between unexpected interest rate movements and bank stock returns is analyzed in the context of the nominal contracting hypothesis. Unanticipated changes in interest rates should influence individual bank profits and stock returns depending on the maturity characteristics of their assets relative to their liabilities. This hypothesis is investigated by constructing portfolios on the basis of the nominal contracting positions of banks. The main conclusion of this paper is ...
Tópico(s): Monetary Policy and Economic Impact
1987 - Elsevier BV | Journal of Banking & Finance
Ali R. Koray, Vefa Ahsen, Özer Bekâroĝlu,
A novel, soluble copper phthalocyanine containing four benzo-15-crown-5 moieties was synthesized and characterized by elemental analysis, i.r. and u.v. spectroscopy, and its alkali cation-complexing capability and selectivity studied.
Tópico(s): Organic Chemistry Cycloaddition Reactions
1986 - Royal Society of Chemistry | Journal of the Chemical Society Chemical Communications
M. Bardin, E. Bertounesque, V. Plichon, J. Simon, Vefa Ahsen, Özer Bekâroĝlu,
Films of crown-ether substituted diphthalocyanine of lutetium (CR-Pc2Lu) have been studied by cyclic voltammetry. In contact with K+ or Na+ aqueous electrolyte, two reversible one-electron steps lead to the formation of the orange cation CR-Pc2Lu+ and to the blue anion CR-Pc2Lu−. With other alkali metal cations, the irreversibility of both steps increases in the order K+, Na+ ⪡ Li+ < Rb+, Cs+. In acid medium (HCl or HClO4), voltammetry cannot be performed in the absence of alkali cation added simultaneously ...
Tópico(s): Electrocatalysts for Energy Conversion
1989 - Elsevier BV | Journal of Electroanalytical Chemistry
Vefa Ahsen, Ayşegül Gürek, Emel Musluoǧlu, Özer Bekâroĝlu,
Abstract A monoaza crown ether substituted (phthalocyaninato)copper(II) complex 2 and its water‐soluble quaternary ammonium salt 3 were prepared from the corresponding dibromomonoaza crown ether derivative 1 and CuCN in pyridine.
Tópico(s): Metal-Catalyzed Oxygenation Mechanisms
1989 - Wiley | Chemische Berichte
Vefa Ahsen, Emel Yilmazer, Ayşegül Gürek, Ahmet Gül, Özer Bekâroĝlu,
Abstract Group‐IV‐A phthalocyanines with four crown ether substituents have been prepared from 4′,5′‐dicyanobenzo(15‐crown‐5), 4′,5′‐diiminoisoindolino(15‐crown‐5), or metal‐free phthalocyanine and the corresponding metal salts. The axial ligands of dichloro[tetra(15‐crown‐5)phthalocyaninato]silicon or ‐tin have been converted into dihydroxy derivatives by hydrolysis in aqueous Et 3 N. The catalytic effect of H 2 O‐free CaC1 2 in quinoline is used for the polycondensation of dihydroxysilicon‐phthalocyanine ...
Tópico(s): Magnetism in coordination complexes
1988 - Wiley | Helvetica Chimica Acta
Vefa Ahsen, Emel Yilmazer, Özer Bekâroĝlu,
Abstract (18‐Crown‐6)‐bridged phthalocyanine network polymers 4–8 as well as a low‐molecular‐weight model compounds with only one phthalocyanine unit ( 3a, b ) were prepared from tetracyanodibenzo‐18‐crown‐6 ( 2a ). The cyano end groups were partially converted into imido groups during the cyclotetramerization reaction, as detected from the IR spectra. In order to obtain structurally uniform compounds with the same end groups, the C N groups were hydrolyzed into imido groups with conc. sulfuric acid. The ...
Tópico(s): Magnetism in coordination complexes
1988 - Wiley | Die Makromolekulare Chemie
Vefa Ahsen, Emel Yilmazer, M. ERTAS, Özer Bekâroĝlu,
A straightforward and generalizable synthesis of metal-free and metal (Cu, Co, Ni, or Fe) derivatives of a symmetrically tetrasubstituted phthalocyanine derived from 15,16-dicyano-2,3,5,6,8,9,11,12-octahydro-benzo[1,4,7,10,13]pentaoxacyclopentadecine is described. The new compounds have been characterized by elemental analyses, and i.r., 1H n.m.r., u.v.–visible, and fast atom bombardment mass spectra. The alkali metal ions (sodium and potassium) bound to crown ether groups of the metal complexes force ...
Tópico(s): Metal-Catalyzed Oxygenation Mechanisms
1988 - Royal Society of Chemistry | Journal of the Chemical Society. Dalton transactions
Ümit İşçi, P. Afanasiev, J.M.M. Millet, E. V. Kudrik, Vefa Ahsen, Alexander B. Sorokin,
Mu-nitrido-bis [tetra-(hexyl-sulfonyl)phthalocyaninatoiron] (3a) and mu-nitrido-bis [tetra-(tert-butylsulfonyl) phthalocyaninatoiron] (3b) complexes have been prepared and fully characterized by electrospray ionization mass spectrometry, UV-Vis, FTIR, EPR, Mössbauer techniques as well as by X-ray photoelectron and Fe K-edge X-ray absorption spectroscopies. Small changes at the periphery of the phthalocyanine ligand introduce a difference in the iron oxidation state. While 3b with tert-butyl substituents ...
Tópico(s): Magnetism in coordination complexes
2009 - Royal Society of Chemistry | Dalton Transactions
Necmettin Kılınç, Devrim Atílla, Ayşe Gül Gürek, Zafer Ziya Öztürk, Vefa Ahsen,
In this study, the nitrogen dioxide (NO2) and ozone (O3) sensing properties of a series bis[tetrakis(alkylthio) phthalocyaninato] lutetium(III) complexes [(CnH2n+1S)4Pc]2Lu(III) (n = 6, 10, 16) are investigated as a function of concentration in the temperature range between 25 °C and 150 °C. The concentration ranges were 1–10 ppm for NO2, and 50 ppb–1 ppm for O3. The response time and the sensor response to NO2 are measured for approximately 1 min and 100% ppm−1, respectively, for compound 1 at room temperature. ...
Tópico(s): Gas Sensing Nanomaterials and Sensors
2009 - Elsevier BV | Sensors and Actuators B Chemical
Zafer Ziya Öztürk, Necmettin Kılınç, Devrim Atílla, Ayşe Gül Gürek, Vefa Ahsen,
Phthalocyanines (Pcs) are organic compounds able to act as chemical recognition systems because of the various physical effects induced in them by interaction with a large number of gases. The gas response, stability and other sensing characteristics of the Pc films are affected by many factors, such as film morphology, molecular orientation and so on. The interaction between the Pc coatings and the gas molecules may be classified in terms of irreversible chemical affinity, reversible (usually charge ...
Tópico(s): Gas Sensing Nanomaterials and Sensors
2009 - World Scientific | Journal of Porphyrins and Phthalocyanines
Tamara V. Basova, Vladimir Plyashkevich, Aseel Hassan, Ayşe Gül Gürek, Gülay Gümüş, Vefa Ahsen,
In this work, thin films of octasubstituted zinc phthalocyanine derivative (ZnPcR8) with bulky substituents R = –CH2N(SO2C6H5–CH3)CH2(CH2)8CH3 are investigated as active layers of optical sensors for the detection of pentachlorophenol. Using total internal reflection ellipsometry (TIRE) technique response characteristics of ZnPcR8 films to pentachlorophenol was studied in the concentration range 0.5–50 μg/l. It was demonstrated that the specific binding of pentachlorophenol molecules causes substantial ...
Tópico(s): Analytical Chemistry and Sensors
2009 - Elsevier BV | Sensors and Actuators B Chemical
Alina A. Pashkovskaya, Еlena А. Kotova, Yunus Zorlu, Fabienne Dumoulin, Vefa Ahsen, И. И. Агапов, Yuri N. Antonenko,
Photosensitized damage to liposome membranes was studied by using different dye-leakage assays based on fluorescence dequenching of a series of dyes upon their release from liposomes. Irradiation of liposomes with red light in the presence of a photosensitizer, trisulfonated aluminum phthalocyanine (AlPcS(3)), resulted in the pronounced leakage of carboxyfluorescein, but rather weak leakage of sulforhodamine B and almost negligible leakage of calcein from the corresponding dye-loaded liposomes. The ...
Tópico(s): Nanoplatforms for cancer theranostics
2009 - American Chemical Society | Langmuir
Mahmut Durmuş, Serkan Yeşi̇lot, Bünyemin Çoşut, Ayşe Gül Gürek, Adem Kılıç, Vefa Ahsen,
The aim of this study is to compare the photophysicochemical properties of hexaphenoxycyclotriphosphazenyl-substituted metal-free (1), mono-(phthalocyaninato) lutetium(III) (2) [LuIII(AcO)(Pc)] (Pc = phthalocyaninato, AcO = acetate) and bis-(phthalocyaninato) lutetium(III) (3) [LuIIIPc2]. The synthesis and characterization (using the elemental analysis, mass spectrometry, IR, 1H, and 31P NMR and UV–vis spectroscopy) of new compounds (2, 3) are described in this study. The electronic absorption and fluorescence ...
Tópico(s): Magnetism in coordination complexes
2009 - Elsevier BV | Synthetic Metals
Vladimir A. Gatchev, Todd Pulvino, Vefa Tarhan,
We develop a dynamic multi-equation model where firms make financing and investment decisions jointly subject to the constraint that sources must equal uses of cash. We argue that static models of financial decisions produce inconsistent coefficient estimates and that models that do not acknowledge the interdependence among decision variables produce inefficient estimates and provide an incomplete and potentially misleading view of financial behavior. We use our model to examine whether firms are ...
Tópico(s): Banking stability, regulation, efficiency
2009 - RELX Group (Netherlands) | SSRN Electronic Journal
Necmettin Kılınç, Devrim Atílla, Sadullah Öztürk, Ayşe Gül Gürek, Zafer Ziya Öztürk, Vefa Ahsen,
In this study, the effect of oxidizing gases, such as oxygen (O2), nitrogen dioxide (NO2), and ozone (O3), on a liquid-crystalline copper octakisalkylthiophthalocyanine[(C6S)8PcCu] thin film was investigated in the temperature range of 25–150 °C. Starting from a chloroform solution of (C6S)8PcCu, a jet-spray technique in an inert ambient atmosphere was used to coat the thin film of the compound on to an Interdigital Transducer (IDT) with gold electrodes. The concentration ranges for NO2 and O3 exposed ...
Tópico(s): Liquid Crystal Research Advancements
2009 - Elsevier BV | Thin Solid Films
Erkan Göksu, Vefa Sayraç, Cem Oktay, Mutlu Kartal, Mehmet Akçimen,
None of the techniques used for confirmation of endotracheal tube (ET) placement are proven reliable 100% of the time. The purpose of our study is to determine whether ultrasound can accurately detect the passage of ET through the trachea and esophagus and to see whether this visualization is augmented with the use of a metal stylet. A total of 7 physicians made assessments of ET positions using an ultrasound during their passage through the trachea or esophagus. A total of 40 esophageal and 40 tracheal ...
Tópico(s): Respiratory Support and Mechanisms
2009 - Elsevier BV | The American Journal of Emergency Medicine
Yunus Zorlu, Mahmut Ali Ermeydan, Fabienne Dumoulin, Vefa Ahsen, Huguette Savoie, Ross W. Boyle,
Tópico(s): Photochromic and Fluorescence Chemistry
2009 - Springer Science+Business Media | Photochemical & Photobiological Sciences