Physical Sciences and Mathematics Commons^™

Incorporation Of Edta For The Elimination Of Metal Inhibitory Effects In An Amperometric Biosensor Based On Mushroom Tissue Polyphenol Oxidase, Arzum Erdem, Di̇lşat Özkan, Burcu Meri̇ç, Kağan Kerman, Mehmet Özsöz

Turkish Journal of Chemistry

Enzyme based biosensors are highly selective devices which rely on the specific binding of the target analyte (the substrate) to the active-site regions of the enzyme. The enzymatic reaction between mushroom tissue polyphenol oxidase and its substrate phenol is coupled with the use of potassium ferrocyanide (K_{4}Fe(CN)_{6}) as the mediator in ammonia buffer solution (pH 8.80). The response of devices is often affected by the presence of inhibitors, which combine with the free enzyme in a manner that prevents substrate binding. The objective of this study is to describe an efficient and yet simple strategy to eliminate the interference of …

Investigation Of The Microporous And Mesoporous Structures Of The Reşadiye (Tokat/Turkey) Bentonite And Its Fractions, Müşerref Önal, Yüksel Sarikaya, Tülay Alemdaroğlu

Turkish Journal of Chemistry

It was determined by X-ray diffraction that, besides containing clay minerals such as montmorillonite and illite, the original bentonite contained also clinoptilolite, opal-C, quartz, calcite and dolomite. The original bentonite was separated into four fractions by decantation and precipitation from its aqueous suspension. The adsorption and desorption of nitrogen on the original bentonite and its fractions at 77 K were investigated. The specific surface areas of the samples were determined according to the methods of Brunauer-Emmett-Teller, de Boer-Lippens, and Harkins-Jura by using the adsorption data. The mesopore size distribution curves were plotted by using the desorption data. The specific micropore …

Investigations On The Electrochemical Surface Treatment Of Carbon Fibers, Erdal Bayramli, Levent Toppare, Naci̇ Kutay Eri̇nç

Turkish Journal of Chemistry

Desized polyacrylonitrile (PAN) based carbon fibers (CF) were chemically and electrochemically oxidized and reduced. CF surfaces were activated via cyclic voltammetry studies with anodic and cathodic scans. The changes in CF surfaces were studied by contact angle measurements. Lifshitz-van der Waals and acid-base components of single fibers were determined. In general, oxidation resulted in the formation of an acidic surface energy component and reduction gave rise to no change in the number of basic functionalities at the CF surface.

Modification Of Poly(Maleic Anhydride-Co-Styrene) With Hydroxyl Containing Compounds, Oya Gali̇oğlu Atici, Ahmet Akar, Roshan Rahimian

Turkish Journal of Chemistry

Soluble and cross-linked poly(maleic anhydride-co-styrene) copolymers were reacted with hydroxyl containing compounds such as salicylic acid, 2-phenyl ethanol, eugenol and paracetamole in acetone or dioxane solution at 50-80°C. The hydrolytic and controlled release behavior of the copolymers containing these compounds in water was studied. The extent of hydrolysis was found to be affected by the type of polymer support as well as time, temperature and the type of supported compound.

Secondary Amine Mediated Ring-Opening Of Tetrahydroimidazo[1,5- B ][1,2,4]Oxadiazol-2(1 H )-Ones, Necdet Coşkun

Turkish Journal of Chemistry

5,6,7,7a-Tetrahydroimidazo [1,5- b ][1,2,4]oxadiazol-2(1 H )-ones 1a-g converted to imidazoles in the presence of secondary amines. cis-Imidazooxadiazolones 1d-g gave the imidazoles 4d-g when treated with secondary amines, while the treatment of these compounds with tertiary amines afforded imidazoline 3-oxides 5d-g. In case of 1a-c, where R^1 is a hydrogen, tertiary amines induced elimination to give imidazoles 4a-c. In the case of 1a-c, probable trans elimination caused by triethylamine and pyridine and in the case of 1d-f, a concerted double cis elimination mediated by secondary amines is discussed.

Towards The Asymmetric Synthesis Of Ascochlorin, Özdemi̇r Doğan, Wolfgang Oppolzer

Turkish Journal of Chemistry

A synthetic approach is described to the asymmetric synthesis of ascochlorin (1), an antiviral antibiotic, based on the construction of a sesquiterpene unit via asymmetric Diels-Alder reaction of tigloyl sultam 4 & butadiene, and the introduction of the aromatic side chain (C9-C12 unit) by employing cuprate chemistry.

Determination Of Some Of The Physicochemical Properties Of Fine Alumina Powders Prepared By Emulsion Evaporation, Yüksel Sarikaya, İsmet Sevi̇nç, Müşerref Önal, Tülay Alemdaroğlu

Turkish Journal of Chemistry

In order to prepare fine alumina powders, an emulsion was prepared under optimum conditions. The emulsion was examined by optical microscopy and the prepared fine alumina powders were characterised by electron microscopy. The particles were formed of porous spheres and their sizes were between 1 and 10 \\mum. The powder samples were sintered by varying the temperature between 700 and 1600°C. The adsorption and desorption of nitrogen on these samples were investigated. By using the adsorption data, the specific surface areas were calculated according to different procedures and the correlation between them was discussed. The specific micropore and mesopore volumes …

Copper Extraction From Aqueous Solution By Pentaerythrityl Tetrabenzylamine, Derya Kara, Mahi̇r Alkan, Ümi̇t Çakir

Turkish Journal of Chemistry

The extraction of copper(II) from the aqueous phase with pentaerythrityl tetrabenzylamine (PETBA), which was synthesized from pentaerythrityl tetrabromide and benzyl amine, was studied. The influences of ionic strength, extraction time, pH and temperature were evaluated. The extraction results showed that the ionic strength had no effect on extraction efficiency and that the extraction equilibrium was established in a few minutes. The extraction percentage was independent of pH up to pH 7.6 and then decreased gradually to zero at about pH 11.5. The stoichiometry of the compound formed was estimated to be Cu_2L(NO_3)_4, where L is PETBA. It was concluded that …

Flow Injection Analysis For Boron Determination By Using Methyl Borate Generation And Flame Atomic Emission Spectrometry, Deni̇z Yurtsever Sarica, Nusret Ertaş

Turkish Journal of Chemistry

Boron is one of the least sensitive elements in atomic emission spectrometry. As various refractory substances interfere in the analysis and because of the low sensitivity, sample enrichment and the separation of the interfering matrix is needed. Methyl borate has many advantages because of its simple generation conditions and its stability in the absence of moisture. New procedures for the generation of methyl borate without using external heating have also been investigated to produce a more rapid determination of boron. The on-line combination of flow injection analysis using methyl borate generation with flame atomic emission spectrometry as the detector is …

Adsorption Of Non-Ionic Surface Active Agent On Fine Coal And Lignite, Zeki̇ Aktaş

Turkish Journal of Chemistry

The adsorption of Triton X-100 in aqueous solution on the less than 53 \\mum size fractions of Tunçbilek lignite and Zonguldak bituminous coal was studied. The adsorption isotherms were formed for 5, 30 and 1,440 (equilibrium) minutes. The isotherms were evaluated using both Langmuir and Freundlich adsorption equations. Concentrations of the reagent in the monolayer after equilibrium adsorption were determined to be 8.17 and 7.27 \\muM/g coal for the lignite and bituminous coal using the Langmuir adsorption equation. The specific adsorption capacity per unit area of Zonguldak bituminous coal was 5.3 times higher than that of Tunçbilek lignite. The adsorption …

Evaluation Of Sample Pre-Treatment Procedures For The Determination Of Cr, Ni And V In Biological Matrices By Etaas, Jan Medved, Jana Kubova, Eva Chmielewska, Vladimir Stresko

Turkish Journal of Chemistry

Electrothermal atomic absorption spectrometry (ETAAS) was applied for the determination of chromium, nickel and vanadium in biological materials (earthworms, feather, lucerne). Three different decomposition procedures of biological matrices are presented. The utilization of NH_4H_2PO_4, Mg(NO_3)_2 and Pd(NO_3)_2+ Mg(NO_3)_2 as chemical modifiers are investigated and compared. Optimal temperature conditions for the electrothermal determination of Cr, Ni and V are selected. Precision of the determination expressed as relative standard deviations for Cr, Ni and V varied from 6 to 22% . The detection limits are for Cr 8 \\mu g kg^{ - 1}, Ni 12 \\mu g kg^{ - 1}, and V …

Thermogravimetric Investigation Of The Dehydration Kinetics Of Ksf, K10 And Turkish Bentonite, Yalçin Tonbul, Kadi̇r Yurdakoç

Turkish Journal of Chemistry

The kinetic parameters for the dehydration of bentonite from Turkey, KSF and K10 were determined by using dynamic TG techniques. The Ozawa method is better for the dehydration of the clay samples than the first order equation of Coats and Redfern. The former function calculates consistently higher activation energies than the latter. The mean values of the activation energies in the \\alpha range 0.1-0.7, are 56-66 kJ mol^{-1} in the Ozawa method.

Selenium Speciation In Karakaya Dam Lake's Water (Malatya-Turkey), F. Zehra Küçükbay, Mustafa Demi̇r

Turkish Journal of Chemistry

Concentrations of total inorganic selenium, Se(IV), Se(VI) and organically bonded selenium from samples of Karakaya dam lake\\\'s water were determined using ammonium pyrollidine dithio carbamate (APDC) as a chelating agent and subsequent adsorption on amberlite type XAD-8 resins. Eluted analytes are taken up in a matrix free acidic solution suitable for graphite furnace atomic absorption spectroscopy (GFAAS). According to our results, levels of the total inorganic selenium, Se(IV), Se(VI) and organically bonded selenium were found to be between 0.11 \\pm 0.01 and 0.17 \\pm 0.01 \\mug/L, 0.07 \\pm 0.01 and 0.12 \\pm 0.01 \\mug/L, 0.02 \\pm 0.01 and 0.05 \\pm …

Silver Recovery From Waste Photographic Films By Using Enzymatic Method, Nuri̇ Naki̇boğlu, Duygu Toscali, İhsan Yaşa

Turkish Journal of Chemistry

A different enzymatic method was developed for stripping the silver from waste X-ray photographic films. The silver having purity of > 99% was recovered by smelting the obtained slurry in the presence of borax. Enzyme extract, obtained from Bacillus subtilis ATCC 6633 by modifying Horikoshi medium, was used for stripping the silver layer. The metal impurities (Al, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Sn) in the recovered silver were determined using the ICP-MS method. The results were compared those in with literature for high purity silver using the same method.

Oxidation Of Ethylenediaminetetraacetic Acid By N-Bromosuccinimide In Aqueous Alkaline Medium -- A Kinetic Study, S. K. Mavalangi, M. R. Kembhavi, S. T. Nandibewoor

Turkish Journal of Chemistry

The kinetics of oxidation of ethylenediaminetetraacetic acid (EDTA) by N-bromosuccinimide (NBS) in aqueous alkaline media was investigated at 25°C. Analysis of the results showed the reaction is first -- order with respect to [NBS] and apparently less than unit order each with respect to [EDTA] and [alkali]. The influence of the reaction products, ionic strength, temperature effect and dielectric constant of the medium on the rate of reaction was studied. The proposed mechanism is consistent with the observed kinetics. The reaction constants involved in the mechanism were derived. There is a good agreement between the observed and calculated rate constants …

Lewis Acid Catalyzed 1,3-Dipolar Cycloadditon Reactions Of Stabilized Azomethine Ylides, Özdemi̇r Doğan, Hasan Koyuncu, Ümi̇t Kanişkan

Turkish Journal of Chemistry

Diethylzinc was tested for the first time as the Lewis acid in 1,3-dipolar cycloaddition reactions of azomethine ylides to synthesize pyrrolidine derivatives. A new, easily applicable and highly selective method was developed for the synthesis of highly substituted pyrrolidines. By the application of this method, the synthesis of three new pyrrolidine derivatives was achieved.

Electrooxidation Of Methanol And Formic Acid On Platinum Dispersed Polypyrrole Electrodes, İpek Beceri̇k, Fi̇gen Kadirgan

Turkish Journal of Chemistry

The present study was performed in order to investigate the electrocatalytic properties of platinum incorporated polypyrrole films for methanol and formic acid oxidations. The behaviour of this modified electrode was characterised in acidic media (0.1M HClO_4). The electrodes exhibited excellent long-term stability in this media. After the modification and optimisation, the electrocatalytic properties of polypyrrole-metal particles and kinetics of the oxidation reactions were interpreted with regard to fuel cell applications.

Synergistic Solvent Extraction Of Zinc(Ii) And Cadmium(Ii) From Sulfate Medium By A Mixture Of 1 - Phenyl - 3 - Methyl - 4 - Benzoylpyrazol - 5 - One And Methyl - Isobutyl Ketone, Djamel Barkat, Zoubir Derriche, Abdelkader Tayeb

Turkish Journal of Chemistry

The solvent extraction of zinc(II) and cadmium(II) from sulfate medium by 1 - phenyl - 3 - methyl - 4 - benzoylpyrazol - 5 - one (HPMBP) was studied in the following parameter functions: pH, concentration of the extractant, nature of diluent, concentration of the mineral anion and synergism. In the absence of the synergic agent methyl - isobutyl ketone (MIBK), the complexes extracted are ZnL_2(H_2O)_{x(org)} and CdL_2(H_2O)_{y(org)} . In the presence of MIBK, the curves of extraction show the presence of several species of complexes that depend on the concentration of MIBK. For very weak concentrations, the extracted complexes …

Using Flash Animation And Streaming Video For Laboratory/Lecture Demonstrations In Large Enrollment Courses, Mark Anderson

Mark R. Anderson

No abstract is currently available.

Metal Binding Studies With Macrocyclic Hexathioethers: Transition Metal Complexes Of 22s6 And 20s6”,, Gregory Grant, Christopher Brandow, Chrystal Bruce, Mark Brandt, Rebecca Kirk, Sabrina Lee, Kerry Robinson, Larry Mehne

Chrystal D. Bruce

No abstract provided.

The Discovery-Oriented Approach To Organic Chemistry. 5. Stereochemistry Of E2 Elimination: Elimination Of Cis- And Trans-2-Methylcyclohexyl Tosylate, Ram S. Mohan, Marcus E. Cabay, Brad J. Ettlie, Adam J. Tuite, Kurt A. Welday

Ram S. Mohan

Deprotection Of Ketoximes Using Bismuth(Iii) Nitrate Pentahydrate, Ram S. Mohan, Bryce A. Nattier, Kyle J. Eash

Ram S. Mohan

The Discovery-Oriented Approach To Organic Chemistry. 4. Epoxidation Of P-Methoxy-Trans-Β-Methylstyrene. An Exercise In 1H Nmr And 13C Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Rebecca S. Centko

Ram S. Mohan

A Facile And Efficient Method For The Rearrangement Of Aryl-Substituted Epoxides To Aldehydes And Ketones Using Bismuth Triflate, Ram S. Mohan, Kaushik A. Bhatia, Kyle J. Eash, Nicholas M. Leonard, Matthew C. Oswald

Ram S. Mohan

An Efficient Method For The Chemoselective Synthesis Of Acylals From Aromatic Aldehydes Using Bismuth Triflate, Ram S. Mohan, Marc D. Carrigan, Kyle J. Eash, Matthew C. Oswald

Ram S. Mohan

Nonlinear Effects Of Physisorption On Static Friction, G.T. Gao, Xiao Cheng Zeng, Dennis J. Diestler

Xiao Cheng Zeng Publications

The effects of a physisorbed film on the force of static friction in a model contact (monatomic adsorbate confined between plane-parallel walls) were investigated by Monte Carlo simulation. At fixed coverage the friction curve (shear yield stress vs normal stress) exhibits a marked nonlinearity, which results from a competition between adsorbate–wall interactions that predominate at low loads and wall–wall interactions that set in beyond a threshold load, which increases with coverage. Previous proximal-probe and computer experiments, carried out at high coverages, see only the initial (low-load) linear portion of the friction curve.

High-Performance Liquid Chromatographic Separation Of Enantiomers Of Synthetic Amino Acids On A Ristocetin A Chiral Stationary Phase, Antal Péter, Gabriella Török, Daniel W. Armstrong, Géza Tóth, Dirk Tourwé

Chemistry Faculty Research & Creative Works

A macrocyclic glycopeptide, ristocetin A, was used as chiral stationary phase for the high-performance liquid chromatographic separation of enantiomers of 28 unnatural amino acids, such as analogues of phenylalanine, tyrosine and tryptophan, and analogues containing 1,2,3,4-tetrahydroisoquinoline, tetraline or 1,2,3,4-tetrahydro-2-carboline skeletons. Excellent resolutions were achieved for most of the investigated compounds by using reversed-phase or a new polar-organic mobile phase system. The conditions of separation were optimized by variation of the mobile phase composition, temperature and flowrate. Copyright (C) 2000 Elsevier Science B.V.

5. Burton Carl Anderson, Otto Vogl

Otto Vogl

No abstract provided.

The Environmental Science Minor: A Disciplinary Approach To Interdisciplinary Studies With A Grounding In Undergraduate Research, Brian E. Bodenbender, Edward C. Hansen, Graham F. Peaslee, Jonathan W. Peterson

Faculty Publications

No abstract provided.

Redox Studies On The Anti-Rheumatoid Arthritis Gold Drugs: Auranofin And Solganol, Ahmed A. Mohamed

Electronic Theses and Dissertations

The oxidative behavior of Auranofin, 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranosato-S(triethylphosphine)gold(I), was investigated by using cyclic voltammetry (CV) in 0.1 M Bu₄NBF₄/CH₂Cl₂ and 0.1 M Bu₄NPF₆/CH₂Cl₂ solutions using Pt working and auxiliary electrodes and a Ag/AgCl reference. CV studies at scan rates from 50-2,000mVs^-1 and Auranofin concentrations between 1 and 4mM, show two irreversible oxidation processes occurring at +1.1 V and +1.6 V vs. Ag/AgCl. Treatment of Auranofrn with the one electron oxidizing agent [Cp₂Fe]PF₆ gave a μ-thiolato digold cluster, [(Et₃PAu)₂(μ-SR)]₂^{2+ …}