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2001

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Articles 2611 - 2640 of 3030

Full-Text Articles in Physical Sciences and Mathematics

Bag Distributed Real-Time Operating System And Task Migration, Beki̇r Tevfi̇k Akgün Jan 2001

Bag Distributed Real-Time Operating System And Task Migration, Beki̇r Tevfi̇k Akgün

Turkish Journal of Electrical Engineering and Computer Sciences

BAG is a distributed operating system designed for real-time applications which is run on a distributed real-time system. The heterogeneously distributed BAG system consists of nodes which have VME-bus chassis, different types of processor modules, and an interconnection network. The operating system has three main parts having distributed properties: task migration, load balancing and a distributed file system. Heterogeneous task migration is based on the extended finite state machine (EFSM) programming model. The EFMS model has also eased the implementation of the migration mechanism. The load balancing algorithm is centralized in one node. But the overall system will be a …

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Avalanche And Bit Independence Properties For The Ensembles Of Randomly Chosen N \Times N S-Boxes, Işil Vergi̇li̇, Melek D. Yücel Jan 2001

Avalanche And Bit Independence Properties For The Ensembles Of Randomly Chosen N \Times N S-Boxes, Işil Vergi̇li̇, Melek D. Yücel

Turkish Journal of Electrical Engineering and Computer Sciences

Cryptographic test methods such as avalanche, strict avalanche and bit independence criteria, which measure the degree of security of the s-boxes of substitution-permutation networks, are applied to randomly generated ensembles of ( n \times n \) s-boxes. Statistical analysis of experimental data directs the work towards defining ``relative errors'' and examining the avalanche and strict avalanche criteria within ``relative error ranges''. Histograms of relative errors in each ensemble are evaluated, and combining the results of different ensembles corresponding to different values of the s-box size, variations of maximum relative errors versus the size of the s-box are depicted. Some predictions …

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Scalar Wave Diffraction By A Perfectly Soft Infinitely Thin Circular Ring, Fati̇h Di̇kmen, Ertuğrul Karaçuha, Yury Alexanderovich Tuchkin Jan 2001

Scalar Wave Diffraction By A Perfectly Soft Infinitely Thin Circular Ring, Fati̇h Di̇kmen, Ertuğrul Karaçuha, Yury Alexanderovich Tuchkin

Turkish Journal of Electrical Engineering and Computer Sciences

A new strong mathematically rigorous and numerically effective method for solving the boundary value problem of scalar (for example acoustic) wave diffraction by a perfectly soft (Dirichlet boundary condition) infinitely thin circular ring is proposed. The method is based on the combination of the Orthogonal Polynomials Approach, and on the ideas of the methods of analytical regularization. As a result of the suggested regularization procedure, the initial boundary value problem is equivalently reduced to the infinite system of the linear algebraic equations of the second kind, i.e., to an equation of the type ( (I + H) x = b …

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Meta-Genetic Programming: Co-Evolving The Operators Of Variation, Bruce Edmonds Jan 2001

Meta-Genetic Programming: Co-Evolving The Operators Of Variation, Bruce Edmonds

Turkish Journal of Electrical Engineering and Computer Sciences

The standard Genetic Programming approach is augmented by co-evolving the genetic operators. To do this the operators are coded as trees of indefinite length. In order for this technique to work, the language that the operators are defined in must be such that it preserves the variation in the base population. This technique can varied by adding further populations of operators and changing which populations act as operators for others, including itself, thus to provide a framework for a whole set of augmented GP techniques. The technique is tested on the parity problem. The pros and cons of the technique …

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An Integrated Design-Object Modeling Environment -- Pluggable Metamodel Mechanism --, Masaharu Yoshioka, Takayuki Sekiya, Tetsuo Tomiyama Jan 2001

An Integrated Design-Object Modeling Environment -- Pluggable Metamodel Mechanism --, Masaharu Yoshioka, Takayuki Sekiya, Tetsuo Tomiyama

Turkish Journal of Electrical Engineering and Computer Sciences

We propose a new integrated computational environment to support design object modeling, during engineering design process that requires a variety of design object models, such as a geometric model, a control model, and a finite element model. To integrate multiple design object models, we have developed a mechanism called a metamodel mechanism that maintains consistency among various models. The metamodel mechanism represents relationships among concepts used in these models and is useful, for example, to conduct concurrent engineering practices. In this framework, we formalize a design process as operations to the metamodel. This paper expands the concept of the metamodel …

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All-Optical Networking, Altan Koçyi̇ği̇t, Demeter Gökişik, Semi̇h Bi̇lgen Jan 2001

All-Optical Networking, Altan Koçyi̇ği̇t, Demeter Gökişik, Semi̇h Bi̇lgen

Turkish Journal of Electrical Engineering and Computer Sciences

A survey of recent literature on all optical networking is presented. Starting from multiplexing techniques and topological features, network design and performance issues are reviewed. Particular attention is devoted to Wavelength Division Multiplexing (WDM) networks. Static and dynamic solutions of the routing and wavelength assignment (RWA) problem are considered. Issues of current research are summarized.

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Performance Evaluation Of Safer K-64 And S-Boxes Of The Safer Family, Ekrem Aras, Melek D. Yücel Jan 2001

Performance Evaluation Of Safer K-64 And S-Boxes Of The Safer Family, Ekrem Aras, Melek D. Yücel

Turkish Journal of Electrical Engineering and Computer Sciences

If the characteristics of s-boxes of the SAFER family of ciphers are examined for the criteria of strict avalanche, bit independence, and XOR table distribution, experiments show that the ``exponentiating'' s-box has a weakness for an input difference of 128 (=10000000_{2}) and the ``logarithm-taking'' s-box has a weakness for an input difference of 253 (=11111101_{2}). However, since these experiments are performed by isolating the s-boxes from the general structure, they do not necessarily indicate a weakness in the overall algorithm. We propose a quick and rough test method, called the avalanche weight distribution criterion, to evaluate the overall performance of …

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A Framework For Performance And Value Assessment Of E-Business Systems In Corporate Travel Distribution, A.M. Chircu, Robert J. Kauffman Jan 2001

A Framework For Performance And Value Assessment Of E-Business Systems In Corporate Travel Distribution, A.M. Chircu, Robert J. Kauffman

Research Collection School Of Computing and Information Systems

This chapter proposes and illustrates a framework that the authors call the value life cycle for e-commerce systems. Based on recent research results that relate to technology investments in the corporate travel industry and related theoretical and empirical perspectives, the authors lay out the corporate travel e-commerce system solutions value life cycle. The perspective involves estimating the maximum value that that an organization can obtain by implementing an e-commerce system in a specific industry and competitive environment. It also considers multiple factors that act as value contingencies for the implementation process. These create barriers to value accrual and to …

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Analysis Of Wine For Penicillin, Gary Morris, James Yuan, Roy Williams Jan 2001

Analysis Of Wine For Penicillin, Gary Morris, James Yuan, Roy Williams

Chemistry & Biochemistry Faculty Publications

This study addresses the question of whether the antibiotic Penicillin, which is produced by the common mold Penicillium notatum, could possibly become a contaminate of wine during the fermentation process. The significance of this study is related to the potential health effects this agent might produce in those consumers who have an allergic response to Penicillin. It has been estimated that between 6% and 8% of the American population is subject to this type of allergic response. A method is developed for the detection of penicillin in wines using high-pressure liquid chromatography. We demonstrate that penicillin G hydrolyzes rapidly …

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Stm And Electrochemical Investigation Of Homoepitaxial Boron-Doped Cvd Diamond Films, John B. Cooper, Jason A. Moulton, Sacharia Albin, Bing Xiao Jan 2001

Stm And Electrochemical Investigation Of Homoepitaxial Boron-Doped Cvd Diamond Films, John B. Cooper, Jason A. Moulton, Sacharia Albin, Bing Xiao

Chemistry & Biochemistry Faculty Publications

Homoepitaxial growth of boron-doped CVD diamond films was carried out on (100) and (111) oriented substrates. Atomic resolution images were obtained for both (100) and (111) surfaces using scanning tunneling microscopy. STM images reveal the presence of a 2x1-monohydride reconstruction for the untreated (100) surface and a lxl reconstruction for the untreated (111) surface. No other atomically resolved reconstructions were observed under a wide range of growth conditions. Non-aqueous electrochemical investigations were carried out on the films exhibiting atomically resolved reconstructions. Evidence for potential-induced surface-reconstruction and surface chemical modification of the (100) 2xl-monohydride surface has been observed.

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Photocuring Of Acrylate Oligomers In The Presence Of Vinyl Phosphonic Acids As A Flame Retarding Monomer And The Properties Of The Cured Films, Tüli̇n İmamoğlu, Yusuf Yağci Jan 2001

Photocuring Of Acrylate Oligomers In The Presence Of Vinyl Phosphonic Acids As A Flame Retarding Monomer And The Properties Of The Cured Films, Tüli̇n İmamoğlu, Yusuf Yağci

Turkish Journal of Chemistry

Photocuring of formulations containing polyurethane based acrylates and a flame retarding monomer (FR), namely vinyl phosphonic acid with an \alpha -cleavage type photoinitiator; 2-hydroxy-2-methylphenyl propane-1-one were studied. The flame retardancy, and the physical and mechanical properties of the cured films were determined.

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Determination Of The Thermodynamic Properties Of Poly [2-(3-Phenyl-3-Methylcyclobutyl)-2-Hydroxyethyl Methacrylate-Co-Methacrylic Acid] At Infinite Dilution By Inverse Gas Chromatography, İsmet Kaya, Kadi̇r Demi̇relli̇ Jan 2001

Determination Of The Thermodynamic Properties Of Poly [2-(3-Phenyl-3-Methylcyclobutyl)-2-Hydroxyethyl Methacrylate-Co-Methacrylic Acid] At Infinite Dilution By Inverse Gas Chromatography, İsmet Kaya, Kadi̇r Demi̇relli̇

Turkish Journal of Chemistry

Some thermodynamic quantities were obtained for the interactions of poly [2-(3-phenyl -3- methylcyclobutyl)-2-hydroxyethyl methacrylate-co-methacrylic acid] Poly (PCHEMA-co-MA) with alcohols, ketones, acetates, aromatics and n-alkanes by inverse gas chromatography in the temperature range of 150-180^oC. The specific retention volumes, Vg^o, weight fraction activity coefficients of solute probes at infinite dilution, \Omega_{1}^{\infty} and Flory-Huggins thermodynamic interaction parameters, \chi_{12}^{\infty} between polymers and solvents were determined. The partial molar free energy, \DeltaG_{1}^{\infty} , the partial molar heat of mixing, \DeltaH_{1}^{\infty} , at infinite dilution and the solubility parameters of the polymer, \delta_{2} , were calculated. The copolymer was characterized by ^1 H-NMR, FT-IR and …

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Voltammetric And Polarographic Studies Of Eriochrome Black T - Nickel(Ii) Complex, Osman Çakir, Emi̇ne Ertürk Coşkun, Ender Bi̇çer, Semi̇ha Çakir Jan 2001

Voltammetric And Polarographic Studies Of Eriochrome Black T - Nickel(Ii) Complex, Osman Çakir, Emi̇ne Ertürk Coşkun, Ender Bi̇çer, Semi̇ha Çakir

Turkish Journal of Chemistry

The electrochemical behaviour of complexes of Eriochrome Black T (EBT) with Ni(II) was studied. It was observed that EBT forms 1:1 and 1:2 complexes with Ni(II) in 0.1 M phosphate buffer at pH 6.0 by using Square-wave voltammetry (SWV), Cyclic voltammetry (CV), Direct Current Polarography (Sampled DCP) and Controlled Potential Coulometry (CPC). It was found that the reduction processes of Ni(II)-EBT complexes are irreversible. The stability constants of the Ni(II)-EBT complexes were evaluated with the DeFord-Hume procedure at different ligand concentrations using SWV. The logarithm values of stability constants of 1:1 and 1:2 Ni(II)-EBT complexes are 8.17 and 11.17, respectively.

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The Sorption Of Metals On The Polysulfone Cation Exchange Membranes, Mustafa Ersöz, İlkay Hi̇lal Güğül, Aysel Çi̇men, Betül Leylek, Sali̇h Yildiz Jan 2001

The Sorption Of Metals On The Polysulfone Cation Exchange Membranes, Mustafa Ersöz, İlkay Hi̇lal Güğül, Aysel Çi̇men, Betül Leylek, Sali̇h Yildiz

Turkish Journal of Chemistry

The sorption of NaCl and CaCl_2 and monovalent-divalent cation salt mixtures on the polysulfone and polysulfone with polyester support cation exchange membranes were investigated. The sorption of monovalent-divalent cation salt mixtures in contact with NaCl+CaCl_2 salt mixtures were studied at a total concentration of 0.05 M. The obtained results for polysulfone type membranes were compared with Neosepta CL-25T and CM2 cation exchange membranes.

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Evidence For A Hybrid Ping Pong-Semirandom Mechanism For Human Jejunal Glutathione Disulfide Reductase, Nazmi̇ Özer, İzzet Hamdi̇ Öğüş Jan 2001

Evidence For A Hybrid Ping Pong-Semirandom Mechanism For Human Jejunal Glutathione Disulfide Reductase, Nazmi̇ Özer, İzzet Hamdi̇ Öğüş

Turkish Journal of Chemistry

Initial rate versus substrate concentration, [S], profiles (at pH 7.4, 37^oC) for human jejunal glutathione disulfide reductase indicated partial substrate inhibition by GSSG at fixed [NADPH] \le 40 \mu M. Saturation by NADPH assumed an increasingly sigmoidal character at fixed [GSSG] \ge 20 \mu M. The results were interpreted in terms of a hybrid ping pong-semirandom mechanism proceeding through both E.NADPH (ping pong pathway) and E.GSSG (ordered pathway) complexes. When V(apparent) versus [GSSG] and [NADPH] were plotted, hyperbolic curves were obtained. Plotting 1/Vm(apparent) versus 1/[NADPH] and 1/[GSSG] yielded two lines with different slopes but intersecting at the same point on …

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A Comparative Study On The Recovery Of Ecori Endonuclease From Two Different Genetically Modified Strains Of Escherichia Coli, Candan Tamerler, Zeynep İlsen Önsan, Betül Kirdar Jan 2001

A Comparative Study On The Recovery Of Ecori Endonuclease From Two Different Genetically Modified Strains Of Escherichia Coli, Candan Tamerler, Zeynep İlsen Önsan, Betül Kirdar

Turkish Journal of Chemistry

A laboratory scale procedure developed for the purification of EcoRI restriction endonuclease was applied to two different Escherichia coli} strains, E. coli 294 and E. coli M5248, which are genetically modified to overproduce the enzyme. The purification method consisted of three successive chromatographic steps including phosphocellulose and hydroxyapatite columns and further fractionation in a second phosphocellulose column. It was shown that the second phosphocellulose separation can be omitted in the case of E. coli 294. Quality control tests indicated enzyme preparations free of contaminants and endo- or exo-nucleases. The yields obtained at the final stage of the purification were 1.3x10^{5} …

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The Isolation Of Carboxylic Acids From The Flowers Of Delphinium Formosum, Nedi̇me Dürüst, Seçki̇n Özden, Esra Umur, Yaşar Dürüst, Mustafa Küçüki̇slamoğlu Jan 2001

The Isolation Of Carboxylic Acids From The Flowers Of Delphinium Formosum, Nedi̇me Dürüst, Seçki̇n Özden, Esra Umur, Yaşar Dürüst, Mustafa Küçüki̇slamoğlu

Turkish Journal of Chemistry

From the flowers of Delphinium formosum Boiss. et Huet. (Ranunculaceae) trans-aconitic, p-hydroxybenzoic, p-coumaric, caffeic and chlorogenic acids were isolated and identified. In addition, protocatechuic, vanillic and gentisic acids were identified.

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Spectrophotometric Determination Of Cobalt, Nickel Palladium, Copper, Ruthenium And Molybdenum Using Sodium Isoamylxanthate In Presence Of Surfactants, Ashok Kumar Malik, K. N. Kaul, B. S. Lark, W. Faubel, A. L. J. Rao Jan 2001

Spectrophotometric Determination Of Cobalt, Nickel Palladium, Copper, Ruthenium And Molybdenum Using Sodium Isoamylxanthate In Presence Of Surfactants, Ashok Kumar Malik, K. N. Kaul, B. S. Lark, W. Faubel, A. L. J. Rao

Turkish Journal of Chemistry

A direct method has been developed for the spectrophotometric determination of microamounts of Co(II), Ni(II), Cu(II), Pd(II), Ru(III) and Mo(VI) using sodium isoamylxanthate as a reagent in the presence of surfactant as solubilising agent. The method has been applied to the determination of these metal ions in various alloys and in environmental samples (fly ash).

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Unusual Chemical Constituents Of Lotus Garcinii (Fabaceae), Muhammad Shaiq Ali, Farman Ahmad, Viqar Uddin Ahmad, Iqbal Azhar, Khan Usmanghani Jan 2001

Unusual Chemical Constituents Of Lotus Garcinii (Fabaceae), Muhammad Shaiq Ali, Farman Ahmad, Viqar Uddin Ahmad, Iqbal Azhar, Khan Usmanghani

Turkish Journal of Chemistry

The methanol soluble part of Lotus garcinii, belonging to the family Fabaceae, yielded three new interesting metabolites: garceine (1), garoside (2) and garthiol (3), which have never been detected from any natural source. In addition, isophytol, hexadecanoic acid, cholesterol, oleanolic acid, butulinic acid and lupeol were also obtained for the first time from L. garcinii}. All the isolated metabolites were characterized by spectroscopic means.

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Determination Of Fluoride And Some Metal Ion Levels In The Drinking Waters In Kayseri Province, Şeri̇fe Tokalioğlu, Uğur Şahi̇n, Şenol Kartal Jan 2001

Determination Of Fluoride And Some Metal Ion Levels In The Drinking Waters In Kayseri Province, Şeri̇fe Tokalioğlu, Uğur Şahi̇n, Şenol Kartal

Turkish Journal of Chemistry

Fluorine is one of the most common elements in the Earth's crust. Fluoride is recognized to be the most effective caries-preventive agent. The main sources of fluoride for people are generally food and drinking water. For this reason, the fluoride and also the metal ion (Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn) concentrations in the drinking waters collected from the city center of Kayseri and its counties were investigated. In the determination of fluoride and of Na and K, an ion-meter with a combination-fluoride electrode and a flame photometer were used, respectively. The levels of …

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Synthesis And Structure Of Systems Containing Pyramidalized And Strained Double Bond: An Investigation On The Cycloaddition Reactions Of Cis- And Trans-3,8-Dicarbomethoxy-3,8-Dihydroheptalene, Nurullah Saraçoğlu, Abdullah Menzek, Meti̇n Balci Jan 2001

Synthesis And Structure Of Systems Containing Pyramidalized And Strained Double Bond: An Investigation On The Cycloaddition Reactions Of Cis- And Trans-3,8-Dicarbomethoxy-3,8-Dihydroheptalene, Nurullah Saraçoğlu, Abdullah Menzek, Meti̇n Balci

Turkish Journal of Chemistry

The cycloaddition reactions of cis-3,8-dicarbomethoxy-3,8-dihydroheptalene cis-2 and trans-3,8-dicarbomethoxy-3,8-dihydroheptalene trans-2 with various dienophiles such as dimethyl acetylenedicarboxylate (DMAD), p-benzoquinone, maleic anhydride, tetracyanoethylene, naphtoquinone gave monoaddition products 15-23. Further addition of benzyne and dimethyl acetylenedicarboxylate to 18 resulted in the formation of the compounds syn-25 and syn-26 having pyramidalized double bonds. The addition of benzyne to 21 and the addition of dimethyl acetylenedicarboxylate to 21, 22 and 23 gave the anti configuration products anti-26, 27 and 28, respectively. X-ray structures of syn-25, syn-26 and anti-26 show the pyramidalized angles to be 16.5^o, 19.9^o and 8.0^o, respectively.

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Cross-Correlation Noise Studies In Atomic Magnet-Optic Rotation Spectroscopy, Ahmet T. İnce Jan 2001

Cross-Correlation Noise Studies In Atomic Magnet-Optic Rotation Spectroscopy, Ahmet T. İnce

Turkish Journal of Chemistry

Analytical signals in an Atomic Magneto-Optic Rotation spectrometer are buried in noise at the limit of detection. The noisy analytical signals were analysed by carrying out mathematical correlation of their time domain waveforms. The noise components of signals were removed by auto-correlation to simplify the study. If noise interferes in analytical signals whose source is unclear, a cross-correlation of the output waveform with noise source may identify the source, e.g., mains frequencies and background radio signals. A cross-correlation will reveal whether the two signals are derived from the same source. This can also lead to an improvement in the signal …

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Simultaneous Determination Of Inorganic Anions And Organic Acids By Capillary Electrophoresis, Nevi̇n Özteki̇n, F. Bedi̇a Eri̇m Berker Jan 2001

Simultaneous Determination Of Inorganic Anions And Organic Acids By Capillary Electrophoresis, Nevi̇n Özteki̇n, F. Bedi̇a Eri̇m Berker

Turkish Journal of Chemistry

A rapid, easy, and reproducible method for the simultaneous determination of inorganic anions and organic acids is reported. The method is based on the separation of anions in a capillary coated with a cationic polymer, polyethyleneimine (PEI). Four inorganic anions (chloride, sulfate, iodate and phosphate) and eight organic acids (oxalate, tartarate, malate, succinate, citrate, acetate, lactate, and propionate) were separated and quantified within 7 min by using 2,6-pyridinedicarboxylic acid (PDC) as the background electrolyte. The minimum detection limits are 0.67-2.87 \mu g/mL for inorganic ions and 0.38-2.84 \mu g/mL for organic acids. Reproducibilities in migration times (RSD%) for both inorganic …

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Usefulness Of A Technique Based On Negative Corona Discharge For The Degradation Of Selected, Condensed Pahs: Application To The Oxidation Of Anthracene And Similar Structures, D. Tessi̇er, C. Oguic, J. Pinart, J. J. Aaron Jan 2001

Usefulness Of A Technique Based On Negative Corona Discharge For The Degradation Of Selected, Condensed Pahs: Application To The Oxidation Of Anthracene And Similar Structures, D. Tessi̇er, C. Oguic, J. Pinart, J. J. Aaron

Turkish Journal of Chemistry

The usefulness of negative corona discharge for oxidation of condensed polycyclic aromatic hydrocarbons (PAHs), including anthracene, naphthalene and 2,3-benzanthracene, adsorbed on a solid substrate is evaluated. In the case of anthracene, the application of corona discharge under high voltage (10-20 kV) for 10 to 180 min with a current intensity of 5-120 \mu A in a controlled, humid atmosphere leads to the progressive formation of anthraquinone. A kinetic study of the anthracene oxidation shows that the apparent half-lives range from 5 to 48 min, according to the initial anthracene amount (50-5000 nmol), indicating a reaction order between 0 and 1. …

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Photochemically-Induced Fluorescence Properties And Determination Of Flufenamic Acid, A Non-Steroidal Anti-Inflammatory Drug, In Urine And Pharmaceutical Preparation, Lei̇la Bettaieb, J. J. Aaron Jan 2001

Photochemically-Induced Fluorescence Properties And Determination Of Flufenamic Acid, A Non-Steroidal Anti-Inflammatory Drug, In Urine And Pharmaceutical Preparation, Lei̇la Bettaieb, J. J. Aaron

Turkish Journal of Chemistry

The photochemically-induced fluorescence (PIF) properties of flufenamic acid (FF), a non-steroidal anti-inflammatory drug (NSAID) were investigated in acidic (pH 1.0) aqueous solutions at room temperature. An optimization procedure, including the effects of UV irradiation time, pH and solvent, was established for the determination of FF. A linear logarithmic calibration plot was obtained over a wide concentration range of four orders of magnitude. A low limit of detection of 0.14 ng/mL was found. The relative standard deviation (RSD) was 6.6% . The PIF method was applied to the quantitative analysis of FF in urine and in a pharmaceutical preparation with satisfactory …

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Synthesis And Characterization Of Copper(Ii), Nickel(Ii), Cadmium(Ii), Cobalt(Ii) And Zinc(Ii) Complexes With 2-Benzoyl-3-Hydroxy-1-Naphthylamino-3-Phenyl-2-Propen-1-On, Mehmet Sönmez Jan 2001

Synthesis And Characterization Of Copper(Ii), Nickel(Ii), Cadmium(Ii), Cobalt(Ii) And Zinc(Ii) Complexes With 2-Benzoyl-3-Hydroxy-1-Naphthylamino-3-Phenyl-2-Propen-1-On, Mehmet Sönmez

Turkish Journal of Chemistry

Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes of 2-Benzoyl-3-hydroxy-1-naphthylamino-3-phenyl-2-propen-1-on, which is a derivative of carboxamide, were prepared and characterized by elemental, spectral and magnetic methods. Based on the analytical results, electronic and infrared spectral data and magnetic susceptibility measurements, suitable structures have been proposed. The formation of the complexes in solution was investigated conductometrically. 2-Benzoyl-3-hydroxy-1-naphthylamino-3-phenyl-2-propen-1-on was found to be a bidentate ligand coordinating through enolic oxygen and amide nitrogen. The complexes of Co(II) and Ni(II) are proposed to have an octahedral structure, while Cd(II), Cu(II) and Zn(II) are suggested to possess a square-planar environment in the complexes.

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A Novel Technique For Silver Extraction From Silver Sulphide Ore, Sevda Ayata, Hüseyi̇n Yildiran Jan 2001

A Novel Technique For Silver Extraction From Silver Sulphide Ore, Sevda Ayata, Hüseyi̇n Yildiran

Turkish Journal of Chemistry

A novel technique for silver extraction from Ag_2S is described. The method utilizes thiosulphate as complexing reagent and the redox reaction between SO_2 added as Na_2SO_3 powder and H_2S gas evolved. The parameters of the reaction such as pH, the reaction temperature, the complex equilibrium of Ag^+ ion with thiosulphate and the solubility of Ag_2S were investigated. Silver ions, obtained by this means are collected in high purity (99%) by applying appropriate electrolysis conditions. The interference from other metallic impurities, namely copper, gold, iron and zinc, is eliminated by choosing an appropriate electrolysis potential.

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Adsorption Of Some Textile Dyes By Hexadecyltrimethylammonium Bentonite, Özlem Ceyhan, Demet Baybaş Jan 2001

Adsorption Of Some Textile Dyes By Hexadecyltrimethylammonium Bentonite, Özlem Ceyhan, Demet Baybaş

Turkish Journal of Chemistry

In this study, hexadecyltrimethylammonium (HDTMA) bentonite was synthesized by placing alkylammonium cation onto bentonite. Adsorption of some textile dyes such as Everdirect Supra Yellow PG, Everdirect Supra Orange 26 CG, Everdirect Supra Rubine BL, Everdirect Supra Blue 4BL and Everdirect Supra Red BWS on Na-bentonite and HDTMA-bentonite was investigated. While the Na-bentonite had no affinity for the dyes, the HDTMA-bentonite showed significant adsorption from aqueous solution. The Langmuir and Dubinin-Rasdushkevich (D-R) isotherm equations were applied to the data and values of parameters of these isotherm equations were evaluated. The mean energy of adsorption, E, was also calculated from the adsorption …

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Reaction Mechanism And Kinetics Of Aqueous Solutions Of 2-Amino -2 Methyl-1,3- Propanediol And Carbonyl Sulphide, Erdoğan Alper Jan 2001

Reaction Mechanism And Kinetics Of Aqueous Solutions Of 2-Amino -2 Methyl-1,3- Propanediol And Carbonyl Sulphide, Erdoğan Alper

Turkish Journal of Chemistry

The mechanism and kinetics of the reaction between aqueous solutions of COS and a sterically hindered primary amine, 2-amino-2-methyl-1,3-propanediol (AMPD), were investigated at 288-303 K using a stopped-flow technique. It was found that the reaction order according to power law kinetics was between 1.12 and 1.16 for an amine concentration range of 0.5 to 1.5 kmol m^{-3} . This overall order indicated that the thiocarbamate formation was complex and possibly involved a zwitterion intermediate. However, the experimental results can also be explained in terms of a single-step termolecular reaction mechanism. The kinetic rate parameters for aqueous AMPD solutions were obtained …

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Optimization Of Process Parameters For Reactive Lactic Acid Extraction, Emi̇ne Kahya, Emi̇ne Bayraktar, Ülkü Mehmetoğlu Jan 2001

Optimization Of Process Parameters For Reactive Lactic Acid Extraction, Emi̇ne Kahya, Emi̇ne Bayraktar, Ülkü Mehmetoğlu

Turkish Journal of Chemistry

The reactive extraction method was used to separate lactic acid from its aqueous solutions. In this method, the amine in the solvent phase reacts with the lactic acid in the aqueous phase, resulting in the extraction of acid into the organic phase. In this study, Alamine 336 diluted with oleyl alcohol was used as the solvent. The effects of initial lactic acid concentration, pH, temperature, extraction time, stirring rate, the amount of Alamine 336 in oleyl alcohol and the ratio of organic phase volume to aqueous phase volume, V_{org}/V_{aq}, on the distribution coefficient of the lactic acid, K_D, were investigated. …

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