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From Simplicial Groups To Crossed Complexes, Z. Arvasi̇ Jan 1998

From Simplicial Groups To Crossed Complexes, Z. Arvasi̇

Turkish Journal of Mathematics

In this paper, we will give a short proof of the construction of the crossed complex of groups by using the higher order Peiffer elements.


On The Validity Of The Borel-Hirzebruch Formula For Topological Actions, D. Dönmez Jan 1998

On The Validity Of The Borel-Hirzebruch Formula For Topological Actions, D. Dönmez

Turkish Journal of Mathematics

We defined an equivalence among group actions and find sufficient conditions for actions of compact connected Lie groups on Euclidean spaces for which the topological version of the Borel-Hirzebruch formula holds.


On The Parabolic Class Number Of Some Subgroups Of Hecke Groups, R. Keski̇n Jan 1998

On The Parabolic Class Number Of Some Subgroups Of Hecke Groups, R. Keski̇n

Turkish Journal of Mathematics

In this paper we calculate the parabolic class number of subgroups of Hecke groups ( H(\sqrt{2}), H (\sqrt{3}) ).


Locally Volume-Minimizing Codimension-One Foliation Of The Solid Torus, İ. Kocayusufoğlu, D. L. Jhonson Jan 1998

Locally Volume-Minimizing Codimension-One Foliation Of The Solid Torus, İ. Kocayusufoğlu, D. L. Jhonson

Turkish Journal of Mathematics

The aim of this paper is to construct a specific codimension-1 foliation of \( D^2 \times S^1 \) with one Reeb component, and to show that this foliation locally minimizes the volume among foliations with the boundary torus as a leaf.


Codes On Superelliptic Curves, F. Özbudak, M. Glukhov Jan 1998

Codes On Superelliptic Curves, F. Özbudak, M. Glukhov

Turkish Journal of Mathematics

The purpose of this paper is to apply superelliptic curves with a lot of rational points to construct rather good geometric Goppa codes.


Cover And Contents Jan 1998

Cover And Contents

Turkish Journal of Mathematics

No abstract provided.


Cover And Contents Jan 1998

Cover And Contents

Turkish Journal of Zoology

No abstract provided.


Cover And Contents Jan 1998

Cover And Contents

Turkish Journal of Zoology

No abstract provided.


Elastic Scattering Of 344.5 Mev ^{12}C Ions From ^{11}B Nucleus, S.A.E. Khallaf, M.A. Abdel-Rahman, S.K. Abdel-Rahman, S.W.Z. Mahmoud Jan 1998

Elastic Scattering Of 344.5 Mev ^{12}C Ions From ^{11}B Nucleus, S.A.E. Khallaf, M.A. Abdel-Rahman, S.K. Abdel-Rahman, S.W.Z. Mahmoud

Turkish Journal of Physics

The angular distribution of the elastic scattering differential cross section of 344.5 MeV $^{12}$C ions from $^{11}$B nucleus is calculated and compared with the experimental data as well as the previously published calculations. The real part of the central optical potential is derived using the double-folding and single-folding procedures assuming Gaussian forms of the nucleon-nucleon and alpha-nucleon interactions, respectively. A nuclear matter density distribution function of $^{11}$B consisting of a spherical part plus a quadrupole term is used. The inclusion of the quadrupole term is found necessary to obtain good fits to the experimental data.


The Influence Of The Dispersion Of Boron Silicate On The Migration Of Non-Equilibrium Charge Carriers Generated By Eect Of An Electric Discharge, A.M. Hasanov Jan 1998

The Influence Of The Dispersion Of Boron Silicate On The Migration Of Non-Equilibrium Charge Carriers Generated By Eect Of An Electric Discharge, A.M. Hasanov

Turkish Journal of Physics

ESR was used in an investigation of the influence of Boron Silicate dispersion on the accumulation of paramagnetic centers (PC). It was observed that the rate of accumulation of PC increase by increasing of the grain size (r). At $r < 0.08$ mm the electrons ($F^+$-centers) are localized on the surface and with increasing grain size up to $0.08 < r < 0.22$ mm charge stratification takes place, the electrons are distributed in near-surface layer and the holes ($V$-centers) are localized in the bulk of the insulator. It was established that the transport of non-equilibrium charge carriers (NCC) from the bulk to the surface of Boron Silicate was due to a drift from the depth $(d \sim 10 \mu m)$ to a bulk-charge field generated by an electric discharge. The value of the surface field $E_s \sim 10^5 V/cm$ is determined by experimental results of the data. The kinetics of the isothermal annealing (300 K) are used to establish the influence of the surface field on the annihilation of NCC in the ''dead'' layer of separated charges.


Dynamical System Topology Preserved In The Presence Of Noise, Judy A. Kennedy, James A. Yorke Jan 1998

Dynamical System Topology Preserved In The Presence Of Noise, Judy A. Kennedy, James A. Yorke

Turkish Journal of Mathematics

We first give a precise definition of the terms ``topological horseshoe'' and ``generalized quadrilateral'' and then examine the behavior of a homeomorphism F on a locally compact, separable, locally connected metric space X (X is usually a manifold in applications) such that F restricted to some generalized quadrilateral Q in X is a topological horseshoe map. For a set Q \subset X we define and describe (1) the permanent set Z of Q to be \{x\in X:F^n(x)\in Q for all integers n\}, and (2) the entrainment set of Q to be E(Q)=\{x\in X: F^{-n} (x)\in Q for all sufficiently large …


On The Cohomology Ring Of The Infinite Flag Manifold Lg/D, Cenap Özel Jan 1998

On The Cohomology Ring Of The Infinite Flag Manifold Lg/D, Cenap Özel

Turkish Journal of Mathematics

In this work, we discuss the calculation of cohomology rings of LG / T. First we describe the root system and Weyl group of LG, then we give some homotopy equivalences on the loop groups and homogeneous spaces, and investigate the cohomology ring structures of LSU_2 /T and \Omega SU_2. Also we prove that BGG-type operators correspond to partial derivation operators on the divided power algebras.


On 3 Dimensional Isotropic Submaniolds Of A Space From, Takehiro Itoh, Koichi Ogiue Jan 1998

On 3 Dimensional Isotropic Submaniolds Of A Space From, Takehiro Itoh, Koichi Ogiue

Turkish Journal of Mathematics

We study 3-dimensional isotropic submanifolds of a space form with low-dimensional first normal space


Cover And Contents Jan 1998

Cover And Contents

Turkish Journal of Mathematics

No abstract provided.


Cover And Contents Jan 1998

Cover And Contents

Turkish Journal of Medical Sciences

No abstract provided.


Effect Of Acute And Regular Exercise Onantioxidative Enzymes, Tissue Damage Markersand Membran Lipid Peroxidation Of Erythrocytesin Sedentary Students, Recep Aslan, M. Ramazan Şekeroğlu, Mehmet Tarakçioğlu, Fahri Bayiroğlu, İsmail Meral Jan 1998

Effect Of Acute And Regular Exercise Onantioxidative Enzymes, Tissue Damage Markersand Membran Lipid Peroxidation Of Erythrocytesin Sedentary Students, Recep Aslan, M. Ramazan Şekeroğlu, Mehmet Tarakçioğlu, Fahri Bayiroğlu, İsmail Meral

Turkish Journal of Medical Sciences

15 healthy sedentary men, 19-25 years old an did not have any programmed physical activity, were studied. The subjects were asked to run submaximal 15-20 min every day for 5 weeks. Erythrocyte lipid peroxidation, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and glucose and uric acid levels were determined in blood samples which were taken before and immediately after acute exercise and after the end of 5-week training program. Malonaldialdehyde (MDA), sing of lipid peroxidation, creatin phosphokinase (CK), CK-MB, lactate dehydrigenase (LDH) concentrations increased (p


Cover And Contents Jan 1998

Cover And Contents

Turkish Journal of Medical Sciences

No abstract provided.


Hepatoerythropoietic Porphyria And Cerebralabnormalities, Mehmet Helvaci, Buket Özkaya, Işın Yaprak, Üstün Ezer Jan 1998

Hepatoerythropoietic Porphyria And Cerebralabnormalities, Mehmet Helvaci, Buket Özkaya, Işın Yaprak, Üstün Ezer

Turkish Journal of Medical Sciences

No abstract provided.


Tracheopathia Osteoplastica, Adil Zamani, Ayşe Gül Zamani, Ergün Bikmaz, Oktay İmeci̇k Jan 1998

Tracheopathia Osteoplastica, Adil Zamani, Ayşe Gül Zamani, Ergün Bikmaz, Oktay İmeci̇k

Turkish Journal of Medical Sciences

No abstract provided.


Characterization Of An All-Optical Device Based On Organic Materials, Hans-Martin Keller, Mark Andreas Bader, Gerd Marowsky Jan 1998

Characterization Of An All-Optical Device Based On Organic Materials, Hans-Martin Keller, Mark Andreas Bader, Gerd Marowsky

Turkish Journal of Chemistry

We present numerical and first experimental results for an all-optical switching device. The device consists of a periodically modulated nonlinear waveguide, where so-called gap solitons stabilize the switching process. The fabrication of Bragg gratings in different polymeric films, e.g. poly(phenylene vinylene), polydiacetylene or polystyrene by excimer laser photoablation was tested. In preparation of further experiments numerical calculations were performed to characterize the device under realistic conditions, including position dependent index modulations and absorption losses. In further time-dependent simulations the transition from the reflecting to the transparent state was investigated in detail. As a main result, the threshold intensity turns out …


Intrinsic Semiconducting Materials On Phthalocyanine Basis, Michael Hanack Jan 1998

Intrinsic Semiconducting Materials On Phthalocyanine Basis, Michael Hanack

Turkish Journal of Chemistry

Stacked transition metal macrocycles [MacM(L)]$_n$ with M e.g. Fe, Ru, Os, Co, Rh and Mac = phthalocyanine (Pc) 1,2- or 2,3-naphthalocyanine (1,2-, 2,3-Nc) were synthesized. The bridging ligands (L) may be e.g. pyrazine (pyz) or $s$-tetrazine (tz). In general, these complexes [MacM(L)]$_n$ are insoluble in organic solvents; however, soluble oligomers [R$_4$PcM(L)]$_n$ can be prepared using metallomacrocycles R$_n$PcM, R = $t$-bu, et, OR, M = Fe, Ru, which are substituted in the peripheric positions. A systematic investigation of the influence of the bridging ligands on the semiconducting properties in [MacM(L)]$_n$ reveals that changing L, e.g., from dabco over pyz to tz …


Phthalocyanines And Related Compounds: Subunits For The Preparation Of Molecular Materials, J. Garcia, A. Gonzalez, A. Gouloumis, E.M. Maya, M.D. Perez, B.D. Rey, P. Vazquez, T. Torres Jan 1998

Phthalocyanines And Related Compounds: Subunits For The Preparation Of Molecular Materials, J. Garcia, A. Gonzalez, A. Gouloumis, E.M. Maya, M.D. Perez, B.D. Rey, P. Vazquez, T. Torres

Turkish Journal of Chemistry

The design, synthesis, structural and physical characterization and engineering, and the study of the electrical conductivity and the nonlinear optical properties of phthalocyanines and molecular substances related to them, such as subphthalocyanines, hemiporphyrazines and triazolephthalocyanines were reviewed.


Azobenzene Side-Chain Liquid Crystalline Polyesters With Outstanding Optical Storage Properties, S. Hvilsted, M. Pedersen, N.C.R. Holme, P.S. Ramanujan Jan 1998

Azobenzene Side-Chain Liquid Crystalline Polyesters With Outstanding Optical Storage Properties, S. Hvilsted, M. Pedersen, N.C.R. Holme, P.S. Ramanujan

Turkish Journal of Chemistry

A flexible azobenzene side-chain liquid crystalline (SCLC) polyester architecture employed for reversible optical storage is described. The modular design allows four structural parameters to be individually modified. These parameters: {\em i}- the methylene side-chain spacer length, {\em ii}- the substituent on azobenzene, {\em iii}- the methylene main-chain segment length, and {\em iv}- the polyester molecular mass, all influence the optical storage properties. A general synthetic route to novel mesogenic azobenzene diols comprising parameters {\em i} and {\em ii} is outlined. Polyesters with molecular masses (parameter {\em iv}) up to 100,000 are routinely obtained by melt transesterification of the novel diols …


Electropolymerization Of Thiophene With And Without Aniline In Acetonitrile, Muzaffer Can, Kadir Pekmez, Nuran Pekmez, Attila Yildiz Jan 1998

Electropolymerization Of Thiophene With And Without Aniline In Acetonitrile, Muzaffer Can, Kadir Pekmez, Nuran Pekmez, Attila Yildiz

Turkish Journal of Chemistry

The electrooxidation behaviors of thiophene and 3-methylthiophene on a Pt surface in acetonitrile/tetrabutylammonium tetrafluoroborate solution were investigated using cyclic voltammetry. The electropolymerization of these monomers and electrochemical properties of polythiophene and poly(3-methylthiophene) were studied in neutral, acidic and basic media. Mechanisms related to the formation of polymers and electroactivity loss were proposed. The effect of thiophene on the electropreparation and properties of polyaniline were also investigated. The presence of thiophene in solutions of aniline in acetonitrile accelerates the formation and causes an improvement in the conductivity of polyaniline films. Thiophene, which catalyzes the polyaniline formation, enters into the structure of …


Poly(3-Alkylthiophene) Modifications, A. Bolognesi Jan 1998

Poly(3-Alkylthiophene) Modifications, A. Bolognesi

Turkish Journal of Chemistry

No abstract provided.


Xps Investigations On Conducting Polymers, Ş. Süzer, Ö. Bi̇rer, U.A. Sevi̇l, O. Güven Jan 1998

Xps Investigations On Conducting Polymers, Ş. Süzer, Ö. Bi̇rer, U.A. Sevi̇l, O. Güven

Turkish Journal of Chemistry

X-ray photoelectron spectroscopy, XPS, was used for the characterization of electrically conducting polymeric materials. In the spectrum of polypyrrole, PPy, the Nls region exhibits two peaks, at 402.0 and 399.8 eV, corresponding to -N$^+$- and -N- moieties, respectively. The intensity of the N$^+$ peak decreases as the material loses its conductivity, hence the ratio of the experimentally derived N$^+$/C atomic ratio correlates exponentially with the measured conductivity. A similar observation also exists between the F$^-$/C atomic ratio both in polypyrrole and polythiophene. In the XPS spectrum of the composite material prepared using polyaniline, PAN and polyvinylchloride, PVC, two different kinds …


Electrochromism Of Sol-Gel Derived Niobium Oxide Films, M. Maçek, B. Orel Jan 1998

Electrochromism Of Sol-Gel Derived Niobium Oxide Films, M. Maçek, B. Orel

Turkish Journal of Chemistry

Niobium oxide films are promising cathodic electrochromics that in many aspects can compete with the more frequently studied WO$_3$ films. The films reported herein were prepared using the sol-gel route from a NbCl$_5$ precursor. The electrochromic properties were pronounced for crystalline films that are heat-treated at 500^oC and exhibited transmittance changes between coloured and bleached states of 60 \% in the UV and 80 \% in the VIS-NIR regions. Improved bleaching and more reversible electrochromism of thick niobium oxide films (d $>$ 250 nm) were obtained by lithiation.


Electrically Conductive Polymer Grafts Prepared By Electrochemical Polymerization Of Pyrrole Onto Poly[(Methyl Methacrylate)-Co-(2-(N-Pyrrolyl) Ethyl Methacrylate)] Electrodes, Nuran Balci, Ural Akbulut, Levent Toppare, Dietmar Stanke, Manfred L. Hallensleben Jan 1998

Electrically Conductive Polymer Grafts Prepared By Electrochemical Polymerization Of Pyrrole Onto Poly[(Methyl Methacrylate)-Co-(2-(N-Pyrrolyl) Ethyl Methacrylate)] Electrodes, Nuran Balci, Ural Akbulut, Levent Toppare, Dietmar Stanke, Manfred L. Hallensleben

Turkish Journal of Chemistry

Pyrrole was grafted on poly[(methyl methacrylate)-co-(2-(N-pyrrolyl) ethyl methacrylate)] (PMMA-co-PEMA) using constant potential electrolyses. The thermal stability of PMMA-co-PEMA was improved as a result of electrochemical grafting with pyrrole. The electrochemical behavior of the films was studied by cyclic voltammetry. Pyrrole was found to be electroactive on PMMA-co-PEMA electrodes.


Dc Conduction In Electrochemically Synthesized Polypyrrole Films, Akif Kaynak Jan 1998

Dc Conduction In Electrochemically Synthesized Polypyrrole Films, Akif Kaynak

Turkish Journal of Chemistry

DC conductivity measurements were performed by modified four-probe rig on electrochemically synthesized polypyrrole films at a temperature range of -30^oC to 120^oC. Conductivity increased with temperature. The temperature dependence of conductivity was very high for lightly doped polymers, decreasing as the doping level increased. The model used to describe the conduction process was the conduction model originally developed for amorphous silicon by Mott and Davis. When applied to conducting polymers, it assumes that electron transport originates from localized or fixed states within the polymer chain. The charge transfer between the chains takes place by hopping, referred to as phonon-assisted hopping, …


Dimerization Of Pyrrole, Mine Yurtsever, Ersin Yurtsever Jan 1998

Dimerization Of Pyrrole, Mine Yurtsever, Ersin Yurtsever

Turkish Journal of Chemistry

Accurate ab-inito quantum mechanical calculations of pyrrole dimers are reported. The thermodynamical stabilities of dimers with $\alpha - \alpha, \alpha - \beta$, and $\beta - \beta$ type linkages are compared in order to predict the possibilities of branching in polypyrroles. Calculations employing large basis sets and including electron correlation effects predict the $\alpha - \alpha$ dimers as the most stable form. However, an $\alpha - \beta$ type bonding requires only 1.5-2.0 kcal/mol, and the energy necessary to introduce a $\beta - \beta$ type bond is 3.6-4.0 kcal/mol. These values show that a high degree of branching is possible even at …