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Full-Text Articles in Physical Sciences and Mathematics

Immobilization Of Glucose Oxidase And Urease In Hydrogel Matrices, İhsan Gürel, M.Yakup Arica, Vasıf Hasirci Jan 1997

Immobilization Of Glucose Oxidase And Urease In Hydrogel Matrices, İhsan Gürel, M.Yakup Arica, Vasıf Hasirci

Turkish Journal of Chemistry

Immobilization of glucose oxidase and urease in hydrogels of 2-hydroxyethyl methacrylae, and N-vinyl pyrrolidone (NVP) was achieved by irradiation (using UV kand \gamma- rays). The effect of radiation on entrapment efficiencies, retention of activities and swelling rates was obtained. To optimize the system, duration of exposure, reaction temperature, co-monomer concentrations, initiator and cross linker compositions were varied. The repeated reusability of the generated products was also tested. It was found that\gamma-irradiation at very low temperatures did not have a detrimental effect on the enzyme activity. Incorporation of more hydrophilic monomer (NVP), influenced matrix morphology and entrapment efficiencies and retained enzyme …


A Study Of The Thermodynamical Interactions Of Bisphenol-A Polycarbonate With Some Solvents By Gas Chromatography, Özlem Cankurtaran, Ferdane Yilmaz Jan 1997

A Study Of The Thermodynamical Interactions Of Bisphenol-A Polycarbonate With Some Solvents By Gas Chromatography, Özlem Cankurtaran, Ferdane Yilmaz

Turkish Journal of Chemistry

Retentin diagrams of polycarbonate for n-nonane, ethyl acetate and n-butyl acetate were obtained using inverse gas chromatography in the temperature range 80-240^{\circ}C. The specific retention volumes, V^{\circ}_{g} the Flory-Huggins interaction parmeters, \chi^{\infty}_{12}, interaction parameters, \chi^{\ast}_{12}, and effective exchange-energy parameters \bar{X}_{12} of the equation-of-state theory of polycarbonate for n-octane, n-nonane, n-decane, ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate and isoamyl acetate were obtained in the temperature range 200-240^{\circ}C. The parameter \delta_2 was estimated to be 10.7 (cal/cm^3)^{1/2} at room temperature using the \chi^{\infty}_{12} extrapolated to room temperature. Keywords: Bisphenol-A polycarbonate, polymer-solvent interactions, inverse gas chromatography, solubility parameter.


Photoelectron Spectroscopy: A Tool In Sorption Studies, Şefik Süzer, Hasan N. Erten Jan 1997

Photoelectron Spectroscopy: A Tool In Sorption Studies, Şefik Süzer, Hasan N. Erten

Turkish Journal of Chemistry

Photoelectron spectroscopy using AlK\alpha (h\nu=1486.3 eV) has been applied to study the sorption of Cs^+, Sr^{2+}, Ba^{2+}, Zn^{2+} and Co^{2+} on magnesite kaolinite, smectite and chlorite. From the observed intensities of photoelectron peaks it was determined that in magnesite the sorption affinity of the above ions follow the order: Ba^{2+}>Co^{2+}\congSr^{2+}\congZn^{2+}>Cs^+. The order for the sorption of Ba^{2+} and Cs^+ are also determined as chlorite>magnesite>smectite>kaolinite and smectite>chlorite\congkaolinite>magnesite, respectively.


A Topological Approach To The Stabilities Of Isomeric Hückel And Mobius Type Cyclacenes, Lemi Türker Jan 1997

A Topological Approach To The Stabilities Of Isomeric Hückel And Mobius Type Cyclacenes, Lemi Türker

Turkish Journal of Chemistry

Within the constraints of Hückel molecular orbital theory, Hückel and Mobius type cyclacenes were investigated in terms of their angle of total \pi-electron energy, O_{\pi}, and cos O_{\pi} to find out how structural changes affect the stabilities. It has been theoretically deduced that as the number of benzenoid rings (R) increases the isomeric Hückel and Mšbius type cyclacenes should have comparable stabilities, although for low values of R odd-Hückel type and even-Mobius type are predicted to be more stable.


Potentiometric And Spectroscopic Determinaton Of Acid Dissociation Constants Of Some Phenols And Salicylic Acids, Rahmiye Aydin, Ulviye Özer, Naciye Türkel Jan 1997

Potentiometric And Spectroscopic Determinaton Of Acid Dissociation Constants Of Some Phenols And Salicylic Acids, Rahmiye Aydin, Ulviye Özer, Naciye Türkel

Turkish Journal of Chemistry

The dissociation constant of the catechol derivatives 4-nitrocatechol (NCAT), 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DBHA), 3,4-dihydroxyhenylacetic acid (3,4-DPHA) and 3,4-dihydroxycinnamic acid (3,4-DHCA) were identified in 0.1M NaClO_4 ionic medium, at t=25^{\circ}C, by potentiometry. In addition, the first and second dissociation constants of the salicylic acid derivatives 5-nitrosalicylic acid (5-NSA), 4-hydroxysalicylic acid (4-HSA) 5-nitrosalicylic acid (5-HSA) were also determined by potentiometry. Furthermore, the second acid dissociation constants of these ligands were evaluated in I=0.1M NaClO_4 ionic medium, at a temperature of 25^{\circ}C by computer analysis of spectroscopic data.


An Introduction To Topological Quantum Field Theories, Michael Atiyah Jan 1997

An Introduction To Topological Quantum Field Theories, Michael Atiyah

Turkish Journal of Mathematics

No abstract provided.


Augmented Graded Rings, Mashhoor Refai Jan 1997

Augmented Graded Rings, Mashhoor Refai

Turkish Journal of Mathematics

In this paper we study the augmented graded rings and give the ralationship between these rings and stronger properties of graded rings.


On Some Bounds For The Solutions Of The Semi-Discretized Time-Dependent Ginzburg-Landau Equations, Erhan Coşkun Jan 1997

On Some Bounds For The Solutions Of The Semi-Discretized Time-Dependent Ginzburg-Landau Equations, Erhan Coşkun

Turkish Journal of Mathematics

We study the two-dimensional system of Time-Dependent Ginzburg-Landau Equations (TDGL) for modeling a thin film of superconductor subject to a uniform magnetic field. We discretize the TDGL for the space variables using bond variables and staggered grid partitioning technique. By investigating the temporal evolution of semi-discrete Helmholtz enery functional and that of Semi-discretized TDGL, we provide bounds for some observable physical quantities of interest such as superelectron density, supercurrent density, charge density, electric field, and induced magnetic field.


Polymer Light Emitting Diodes, Frank E. Karasz, Bin Hu, Zhou Yang Jan 1997

Polymer Light Emitting Diodes, Frank E. Karasz, Bin Hu, Zhou Yang

Turkish Journal of Chemistry

Polyphenylene vinylene-based conjugated-nonconjugated alternating block copolymers form the active chromophores in a series of light emitting diodes (LEDs). The quantum efficiency and brightness of these devices can be improved by several orders of magnitude by incorporation of appropriate carrier transport layers and by rational choice of electrodes. Further improvements can be gained by blending of the active chromophores with high or low molecular weight species.


Novel Architectures Of Macromolecular Systems, Gerhard Wegner Jan 1997

Novel Architectures Of Macromolecular Systems, Gerhard Wegner

Turkish Journal of Chemistry

An important thrust in modern macromolecular chemistry is to construct complex architectures either directly from monomer units, or to design macromolecules capable of forming a desired superstructure by self-organization. Chain-rigidity is an example of a structural principle leading to self organization depending on the aspect ratio of the molecular objects and their mutual interactions. These molecularly defined objects serve as the building blocks of systems for which ultrathin layers composed of hairy rod macromolecules (HRM) are an example. Depending on architectural details layered architectures of HRM are models for molecular nanocomposites, exhibit interesting optical, electrochemical, dielectric or barrier properties. They …


Analytical Applications Of Organic Conducting Polymer Electrodes, Nada F. Atta, George C. Russell, Z. Wang, N. Akmal, J.F. Rubinson, S.K. Lunsford, E. Karagözler, O. Y. Ataman, H. Zimmer, H.B. (Jr.) Mark, Ahmed Galal Jan 1997

Analytical Applications Of Organic Conducting Polymer Electrodes, Nada F. Atta, George C. Russell, Z. Wang, N. Akmal, J.F. Rubinson, S.K. Lunsford, E. Karagözler, O. Y. Ataman, H. Zimmer, H.B. (Jr.) Mark, Ahmed Galal

Turkish Journal of Chemistry

Electrodes modified by he electrodeposition of conducting polymers were used for the detection and quantitative determination of some inorganic, organic, and biological molecules. Monomers used were five membered ring heterocycles or crown ethers and their derivatives. The polymer films were deposited on glassy carbon or platinum substrates. The resulting electrodes were used in the amperometric mode or in the potentiometric mode for flow injection and chromatographic analyses. The results showed that the proposed modified surface catalyzes the oxidation of organic and biological compounds. The detection of electroinactive inorganic anions, such as F^-, Cl^-, Br^-, NO_2^- and NO^-_3 was also possible …


Reduction Of Combustion Generated Pollution: Process Modifications And Energy Efficient Power Cycles, Janos M. Beer Jan 1997

Reduction Of Combustion Generated Pollution: Process Modifications And Energy Efficient Power Cycles, Janos M. Beer

Turkish Journal of Chemistry

Theoretical bases of combustion process modifications aimed at the reduction of pollutant emission are examined. It is shown, as an example, of how the minimization of emissions of nitrogen oxides leads to a design protocol that translates results of modeling and of bench scale experiments into guidelines for industrial design. The formation and emission of polycyclic aromatic compounds is also considered, because their formation is strongly favored in "low NO_x flames". In power generation the pollutant emission can be reduced effectively by the improvement of the ``heat rate,"i.e., the thermodynamic efficiency of the power cycle. Combined gas turbine-steam cycles which …


Synthesis And Characterization Of Complexes Of Co(Ii), Ni(Ii), Cd(Ii), Hg(Ii) And Pd(Ii) With Some N-Phenyl-N^{1}-2-[4-Phenyl-(Substituted) Thiazolyl]- Thioureas, B. Narayana, M. R. Gajendragad Jan 1997

Synthesis And Characterization Of Complexes Of Co(Ii), Ni(Ii), Cd(Ii), Hg(Ii) And Pd(Ii) With Some N-Phenyl-N^{1}-2-[4-Phenyl-(Substituted) Thiazolyl]- Thioureas, B. Narayana, M. R. Gajendragad

Turkish Journal of Chemistry

The Synthesis and characterization of the complexes of Co(II), Ni(II), Pd(II), Cd(II) and Hg(II) with N-phenyl-N^{1}-2(-4-phenylthiazoly)thiourea (PPT) and N-phenyl-N^{1}-2-(4-methylphenylthiazolyl)-thiourea (PMPT) and Co(II), Cd(II), and Hg(II) complexes of N-phenyl-N^{1}-2-(4-p- chlorophenylthiazolyl) thiourea (PCPT) are included in this paper. Based on analytical results, electronic and infrared spectral data and magnetic susceptibility measurements, plausible structures have been proposed.


Factors Influencing The Angle Of Total Ii-Electron Energies Of Alternant Hydrocarbons, Lemi Türker Jan 1997

Factors Influencing The Angle Of Total Ii-Electron Energies Of Alternant Hydrocarbons, Lemi Türker

Turkish Journal of Chemistry

Within the framework of the Hückel molecular orbital theory, the topological factors affecting the angle of total \pi-electron energies of alternant hydrocarbons were investigated.


Spectrophotometric Determination Of The Pk_A Values Of Some Aminoacid Complexes Of Pentacyanoferrate(Ii) And Pentacyanoruthenate(Ii), Yakup Baran, Şebnem Baran, N. Kemal Tunali Jan 1997

Spectrophotometric Determination Of The Pk_A Values Of Some Aminoacid Complexes Of Pentacyanoferrate(Ii) And Pentacyanoruthenate(Ii), Yakup Baran, Şebnem Baran, N. Kemal Tunali

Turkish Journal of Chemistry

The syntheses, pK_a and spectrospcopic characterization of [Fe(CN)_5(H_2O)]^{-3} and [Ru(CN)_5(H_2O)]^{-3} complexes of alanine(Ala), glycine(Gly), valine(Val), lysine(Lys), arginine(Arg) and cysteine(Cys) complexes were investigated in aqueous solution. The spectra of the complexes containing amino acid ligands were similar to that of [Fe(CN)_5(NH_3)]^{-3}. The pK_a values of the complexes were measured by spectrophotometric titration at 22^{\circ}C and \mu =0.100 M(NaClO_4).


Carbonic Anhydrase From Nicotiana Tabacum Leaves, Nazan Demi̇r, Yaşar Demi̇r Jan 1997

Carbonic Anhydrase From Nicotiana Tabacum Leaves, Nazan Demi̇r, Yaşar Demi̇r

Turkish Journal of Chemistry

In this study, carbonic anhydrase (CA: carbonate hydrolyase; E.C.4.2.1.1) was purified from adult {\it Nicotiana tabacum} leaves and studied biochemically. The enzyme was purified twice times by using (NH$_4)_2SO_4 precipation and DEAE-cellulose column chromatography, and its activity was determined for two different substrates (CO_2 and p-nitrophenyl acetate). The enzyme obtained from the ion exchange column was purified 40.7 fold and the purity was controlled by 3\%-10\% discontinuous SDS-PAGE. The pH of the purified enzyme varied between 6.0 and 7.2, the optimum being 6.9. V_{max} and K_m values were calculated with p-nitrophenyl acetate (0.1524 mM, 0.5446 mM, respectively) as substrate. The …


Determination Of Ponceau 4r And Tartrazine In Various Food Samples By Derivative Spectrophotometric Methods, Sedat Sayar, Yüksel Özdemi̇r Jan 1997

Determination Of Ponceau 4r And Tartrazine In Various Food Samples By Derivative Spectrophotometric Methods, Sedat Sayar, Yüksel Özdemi̇r

Turkish Journal of Chemistry

Derivative spectrophotometric methods were originally developed for determining Ponceau 4R and Tartrazine in order to resolve their binary mixtures. The method permits the simultaneous determinations of these food colorants in various food samples. Recovery by derivative methods was nearly 100 \%.


Epr Spectroscopy Of Dog-Rose Polyphenoloxidase, Çiğdem Nuhoğlu, Fatih Ucun, Enise Ayyildiz, Y. Kemal Yoğurtçu, Halis Şaki̇roğlu, İrfan Küfrevi̇oğlu Jan 1997

Epr Spectroscopy Of Dog-Rose Polyphenoloxidase, Çiğdem Nuhoğlu, Fatih Ucun, Enise Ayyildiz, Y. Kemal Yoğurtçu, Halis Şaki̇roğlu, İrfan Küfrevi̇oğlu

Turkish Journal of Chemistry

Polyphenoloxidase(PPO) of dog-rose fruit was extracted and purified through (NH\4)\2SO\4 precipitation and dialysis. The optimum conditions for this purpose, i.e., pH and temperature, were determined with 4-methylcatechol optimum pH and temperature and found to be pH 8.5 and 20\ci, respectively. The inhibition effect of ascorbic acid was investigated and the I_{50} value was found to be 1.57\times10^{-4} M. The activity of dog-rose PPO was investigated by electron paramagnetic resonance (EPR) at different pH levels and temperatures. The optimum conditions obtained from both spectrophotometry and EPR were compared.


^1h Nmr, Infrared And Mass Spectrometry Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Muhammad Mazhar, Moazzam Hussain Bhatti, Sohail Mahmood, Abida Kalsoom Jan 1997

^1h Nmr, Infrared And Mass Spectrometry Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Muhammad Mazhar, Moazzam Hussain Bhatti, Sohail Mahmood, Abida Kalsoom

Turkish Journal of Chemistry

The di- and tri-organotin derivatives R\2SnL\2 and R\3SnL where R = CH\3, n--C\4H\9, C\6H\5, C\6H_{11} and C\6H\5CH\2 and L = 1-nitroso-2-naphthoxy were synthesized. These derivatives were characterized by elemental analysis, infrared, ^1H NMR and mass spectrometry.


Some Remarks On Solid State Polymerization, George Adler Jan 1997

Some Remarks On Solid State Polymerization, George Adler

Turkish Journal of Chemistry

No abstract provided.


Calculation Of Spreading Pressure Of Water On Cellulosic Films From Contact Angle Data, H. Yıldırım Erbi̇l Jan 1997

Calculation Of Spreading Pressure Of Water On Cellulosic Films From Contact Angle Data, H. Yıldırım Erbi̇l

Turkish Journal of Chemistry

The correlations between the surface properties of the modified cellulose papers with their toner compatibility were investigated. The surface tension components of the cellulosic films, their interfacial tension with the liquid drops and the work of adhesion components were calculated using van Oss-Good's One-Liquid contact angle approach. The electron donor (or Lewis base) \gamma^- components of the cellulosic films were found to represent the main interactions with the the electron acceptor (acidic) \gamma^+ components of the contacting liquids. Allyl ketene dimer (AKD) grafting of the cellulose affected the surface properties; the higher the substitution of the hydroxyl group, the smaller …


A Quantum-Chemical Investigation On 5,5'-Bi(1h-1.2,4-Triazole)), A. A. İki̇zler, R. Abbasoğlu, N. Saltek, M. Şeri̇fova Jan 1997

A Quantum-Chemical Investigation On 5,5'-Bi(1h-1.2,4-Triazole)), A. A. İki̇zler, R. Abbasoğlu, N. Saltek, M. Şeri̇fova

Turkish Journal of Chemistry

The conformational analysis of flexible 5,5'-bi(1H-1,2,4-triazole) molecule containing various reaction centers has been performed by the semiempirical methods MNDO,AM1 and PM3, and the internal rotation barrier calculated. The most stable conformation of the molecule has been determined to be the planar trans conformation. According to the three methods, 5,5'-bi(1H-1,2,4-triazole) molecule (C) has been found to be relatively more stable than its tautomer 3,3'-bi(1H-1,2,4-triazole)(B) and to be less stable than its other tautomer 3,3'-bi(4H-1,2,4-triazole)(A). Moreover, the electronic properties of 5,5'-bi(1H-1,2,4-triazole) molecule and the effect of conformational changing on electronic and geometric properties have also been investigated. To determine the protonation sites …


The Reliability Of Jung-Biggs-Moorhead Method For Cholesterol Determination In The Presence Of Ergosterol, Lemi Türker, Şahinde Demi̇rci̇, Marjan Akdağ Jan 1997

The Reliability Of Jung-Biggs-Moorhead Method For Cholesterol Determination In The Presence Of Ergosterol, Lemi Türker, Şahinde Demi̇rci̇, Marjan Akdağ

Turkish Journal of Chemistry

In the present study, the reliability of Jung-Biggs-Moorhead method for cholesterol determination has been tested in the presence of another steroid, ergosterol. It was observed that presence of ergosterol interferes with the absorbance measurement of cholesterol. When both steroids are present in the sample maximum absorption wavelength are not shifted by the mutual interaction but absorbance values are changed considerably. Therefore this method may be used only for qualitative bu not quantitative analysis for cholesterol in the presence of ergosterol.


Synthesis And Characterisation Of Anhydrous Magnesium Phosphate Mg$_3$(Po$_4$)$_2$, A. Baykal, M. Kizilyalli, R. Kniep Jan 1997

Synthesis And Characterisation Of Anhydrous Magnesium Phosphate Mg$_3$(Po$_4$)$_2$, A. Baykal, M. Kizilyalli, R. Kniep

Turkish Journal of Chemistry

The synthesis and characterization of anhydorus Mg_3(PO$_4)_2 was investigated. Mg_3(PO$_4)_2 is reported to have similar structural arrangements with Co_3(PO_4)_2 and \gamma-Zn_3(PO_4)_2 compounds. The sample was prepared by a new technique which is the reaction of MgCl_2.6H_2O and Na_3PO_4.12H_2O solutions at pH=5.1, which was adjusted by adding concentrated H_3PO_4 to the reaction mixture and heating the precipitated product at 600^{\circ}C untill constant weight. The purity of the product was checked by X-ray powder diffraction, IR, density measurement, SEM and DTA analysis. The monoclinic unit cell dimensions of product are a=7.605 (2), b=8.233 (3), c=5.080 (1)A^{\circ} and \beta= 94.19^{\circ} (3), which was …


Hydrolysis And Condensation Reactions Of Methacrylate-Modified Aluminum Alkoxides, Ertuğrul Arpaç, Efraim Avşar Jan 1997

Hydrolysis And Condensation Reactions Of Methacrylate-Modified Aluminum Alkoxides, Ertuğrul Arpaç, Efraim Avşar

Turkish Journal of Chemistry

The hydrolysis of aluminum tri-sec-butoxide and compounds obtained by substituting the larger functional groups for the present alkly groups in Al(O-sec-Bu)_3, and the reaction of these products with a polymerizable organic ligand, i.e. methacrylic acid, were studied together with the hydrolysis reactions of the final products. A good method of preparing high-tech materials and new composites uses organo-substituted silicon esters and/or alkoxides of various elements in a polycondensation process. Introducing a suitable organic network into the inorganic backbone gives desirable properties in new coating materials. The preparation of such materials is possible via the hydrolysis of metal alkoxides. Usually, different …


A Lower Bound Of The First Eigenvalue Of Certain Self-Adjoint Elliptic Operators On Manifolds Containing Long Necks, Weimin Chen Jan 1997

A Lower Bound Of The First Eigenvalue Of Certain Self-Adjoint Elliptic Operators On Manifolds Containing Long Necks, Weimin Chen

Turkish Journal of Mathematics

In this note, under certain regularity and transversality conditions we obtain a sharp lower bound of the first eigenvalue for certain self-adjoint elliptic operators on manifolds with long necks. This result is used in the gluing construction of 3-dimensional Seiberg-Witten moduli spaces along T^2. See [C1], [C2].


Kirby Calculus In Manifolds With Boundary, Justin Roberts Jan 1997

Kirby Calculus In Manifolds With Boundary, Justin Roberts

Turkish Journal of Mathematics

Suppose there are two framed links in a compact, connected 3-manifold (possibly with boundary, or non-orientable) such that the associated 3-manifolds obtained by surgery are homeomorphic (relative to their common boundary, if there is one.) How are the links related? Kirby's theorem gives the answer when the manifold is S^3, and Fenn and Rourke extended it to the case of any closed orientable 3-manifold, or S^1 \tilde{\times} S^2. The purpose of this note is to give the answer in the general case, using only minor modifications of Kirby's original proof.


The Rank And The Crank Modulo 5, A. Bülent Eki̇n Jan 1997

The Rank And The Crank Modulo 5, A. Bülent Eki̇n

Turkish Journal of Mathematics

Let p(n) denote the number of partitions of n . Ramanujan's partition congruences are p(5n + 4) , p(7n + 5) and p(11n + 6) = mod 5, 7, and 11, respectively. These have been proved in number of ways. Atkin and Swinnerton-Dyer proved the congruences and some more relations about partition İn the case of mod5 and 7 in terms of rank, Garvan proved them in three cases in terms of crank. In this study, we give an another proof of their results in the case of mod5 by using the theory of modular forms. Although our method is …


On The Stability Results For Third Order Differential-Operator Equations, Varga Kalantarov, Aydın Ti̇ryaki̇ Jan 1997

On The Stability Results For Third Order Differential-Operator Equations, Varga Kalantarov, Aydın Ti̇ryaki̇

Turkish Journal of Mathematics

Sufficient conditions for the stability and the global asymptotic stability of the zero solution of third order linear differential- operator equations are established.


The Spectra And Fine Spectra For P-Cesáro Operators, Cafer Coşkun Jan 1997

The Spectra And Fine Spectra For P-Cesáro Operators, Cafer Coşkun

Turkish Journal of Mathematics

In [6], Rhaly computed the spectrum of p-Cesaro operator on the Hilbert space l_2 = {x = (x_k): \Sigma_k IX_kl^2 < infinite}. In the present paper, we study the spectrum and fine spectrum for p-Cesáro operators acting on C_o, the space of null sequences.