Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2002

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 7081 - 7110 of 7459

Full-Text Articles in Entire DC Network

Alteration Of Three Turkish Bentonites By Treatment With Na_{2}Co}_{3} And H}_{2}So}_{4}, Nuray Yildiz, Ayla Çalimli Jan 2002

Alteration Of Three Turkish Bentonites By Treatment With Na_{2}Co}_{3} And H}_{2}So}_{4}, Nuray Yildiz, Ayla Çalimli

Turkish Journal of Chemistry

In this study, fine fractions of bentonites from the Çankırı and Kütahya regions were treated with Na_{2}CO_{3} and H_{2}SO_{4}. The resulting materials were analysed by X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA, DTA) and infrared (IR) spectroscopy. Surface areas of the samples were also measured. The results showed that structural changes were observed by treatment with Na_{2}CO_{3} and H_{2}SO_{4}. These changes showed differences depending on exchangeable cations, clay type and the ratio of additives.

Go to article

The Effects Of Benzoic Acid In Chloride Solutions On The Corrosion Of Iron And Aluminum, Si̇bel Zor Jan 2002

The Effects Of Benzoic Acid In Chloride Solutions On The Corrosion Of Iron And Aluminum, Si̇bel Zor

Turkish Journal of Chemistry

In this work, the corrosion behavior of iron and aluminum was investigated in 0.1 M NaCl solutions with an initial pH value of 8 and containing various concentrations (0, 30, 150, 300 ppm) of benzoic acid. For this purpose, the anodic and cathodic semilogarithmic current-potential curves, weight loss and pH of the solution were determined over time. The changes in the concentrations of benzoic acid in the solutions with time were determined by a UV spectrophotometer. According to the results obtained in this investigation, benzoic acid in 0.1 M NaCl acts on iron and aluminum as an inhibitor. This effect …

Go to article

The Effect Of Acid Activation On Some Physicochemical Properties Of A Bentonite, Müşerref Önal, Yüksel Sarikaya, Tülay Alemdaroğlu, İhsan Bozdoğan Jan 2002

The Effect Of Acid Activation On Some Physicochemical Properties Of A Bentonite, Müşerref Önal, Yüksel Sarikaya, Tülay Alemdaroğlu, İhsan Bozdoğan

Turkish Journal of Chemistry

A white calcium bentonite (CaB) from the K\"{u}tahya region/Turkey was activated by heating it for 6 hours at 97°C in H_{2}SO_{4} solution. The mass percentage of H_{2}SO_{4} in the bentonite-acid mixture was varied from 0 to 70%. The chemical analysis (CA), cation exchange capacity (CEC), differential thermal analysis (DTA) curves and X-ray diffraction (XRD) patterns of the prepared samples were determined. The specific surface area (A) and the specific micropore-mesopore volume (V) were calculated respectively from the adsorption and desorption data of N_{2} obtained at liquid N_{2} temperature. How the calcium montmorillonite (CaM) layers in the CaB were decomposed during …

Go to article

Simultaneous Determination Of Fe(Ii) And Fe(Iii) In Pharmaceutical Samples By Post-Column Derivatization/Hplc, Hami̇de Z. Şenyuva, Deni̇z Yurtsever Sarica, Tuncel Özden Jan 2002

Simultaneous Determination Of Fe(Ii) And Fe(Iii) In Pharmaceutical Samples By Post-Column Derivatization/Hplc, Hami̇de Z. Şenyuva, Deni̇z Yurtsever Sarica, Tuncel Özden

Turkish Journal of Chemistry

A post-column derivatization HPLC method with visible absorbance detection at 521 nm was modified for the simultaneous determination of Fe(II) and Fe(III) in mixtures. The method was applied to pharmaceuticals marketed in Turkey. Iron species were separated on a post-column derivatization HPLC, IonPac CS5A (4x250 mm) analytical column using a pyridine-2,6-dicarboxylic acid based eluent. The determinations of Fe(II) and Fe(III) were also realized by the most common method of FAAS, total iron determination. Detection limits (3S) were found to be 0.109 \mu g/L for Fe(II) and 0.217 \mu g/L for Fe(III), respectively. The mean recovery of the HPLC and AAS …

Go to article

Chemical Exfoliation Characteristics Of Karakoç Phlogopite In Hydrogen Peroxide Solution, Erol Üçgül, İsmai̇l Gi̇rgi̇n Jan 2002

Chemical Exfoliation Characteristics Of Karakoç Phlogopite In Hydrogen Peroxide Solution, Erol Üçgül, İsmai̇l Gi̇rgi̇n

Turkish Journal of Chemistry

The chemical exfoliation characteristics of phlogopite samples taken from Sivas - Yıldızeli-Karakoç (Turkey) ore were investigated. H_{2}SO_{4}, HCl, HNO_{3}, H_{3}PO_{4} and H_{2}O_{2} solutions at varying concentrations were tested for chemical exfoliation and the best reagent for this purpose was determined to be hydrogen peroxide. In the exfoliation tests performed, hydrogen peroxide concentration, temperature and reaction time were observed to be important parameters, with solid/liquid ratio being of minor importance. The exfoliation characteristics of the material increased with increases in hydrogen peroxide concentration and depending on the reaction time (1-30 hours) a maximum value of a 49-fold increase in swelling was …

Go to article

Phytochemical Studies At The Bulbs Of Ornithogalum Umbellatum L., Temi̇ne Şabudak, Ülkü Oyman Jan 2002

Phytochemical Studies At The Bulbs Of Ornithogalum Umbellatum L., Temi̇ne Şabudak, Ülkü Oyman

Turkish Journal of Chemistry

Phytochemical examination of the bulbs of Ornithogalum umbellatum L. led to the isolation a new steroidal compound. Its structure was determined to be 3-O-(2'-methoxy-4'-(2-pentenal))-phenyl sitosterol (1) by spectroscopic data and chemical evidence.

Go to article

Cover And Contents Jan 2002

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

Go to article

Comparison Of Supercritical Fluid And Solvent Extraction Of Feverfew (Tanacetum Parthenium), Muammer Kaplan, Mark R. Simmonds, George Davidson Jan 2002

Comparison Of Supercritical Fluid And Solvent Extraction Of Feverfew (Tanacetum Parthenium), Muammer Kaplan, Mark R. Simmonds, George Davidson

Turkish Journal of Chemistry

High performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) analyses are used to show that supercritical fluid extraction (SFE) using carbon dioxide is an effective means of extracting a range of components from feverfew samples. It was found that the specific compositions of solvent extracts and SFE extracts are different. The amounts of the presumed active ingredient parthenolide have been confirmed to be very variable. Feverfew seeds were particularly rich in parthenolide, while dried powdered samples contained less and, in one case, none at all. The tunability of SFE has been demonstrated, and it was shown that successive extractions …

Go to article

Vapour Liquid Equilibrium In Asymmetric Mixtures Of N-Alkanes With Ethane, Anca Duta, Dan Geana Jan 2002

Vapour Liquid Equilibrium In Asymmetric Mixtures Of N-Alkanes With Ethane, Anca Duta, Dan Geana

Turkish Journal of Chemistry

The paper presents a vapour liquid equilibria study in binary mixtures of n-alkanes with high dimensional asymmetry. Each mixture contains ethane and alkanes higher than eicosane. Calculations were done using two equations of state, Peng-Robinson (PR) and Soave (SRK), in combination with van der Waals mixing rules, corrected with two interaction parameters. A limited temperature dependence of the interaction parameters was found. The correlations between the interaction parameters and the number of carbon atoms of the higher n-alkane led to equations valid for systems ethane + C_{3} up to C_{44}. The results of the prediction calculations were good, both with …

Go to article

A Conformational Exploration Of Dissymmetric Macrolides Antibiotics, Salah Belaidi, A. Dibi, M. Omari Jan 2002

A Conformational Exploration Of Dissymmetric Macrolides Antibiotics, Salah Belaidi, A. Dibi, M. Omari

Turkish Journal of Chemistry

Conformational analysis of the macrolides from 12 to 22 links was carried out using molecular mechanics. Calculations indicate that each studied macrocycle presents eight families of preferential conformers. They result from the combination of the conformations of the two systems diene and \alpha ,\beta -unsaturated ester. Among these conformers three families (F5, F6 and F3) have the lowest energy. The two families F5 and F6 adopt an s-cis conformation of the ester function and s-trans of the diene system with a pseudo-parallel arrangement of the two systems for the first family and a pseudo-antiparallel for the second. The third family …

Go to article

Synthesis Of 2'-Deoxy-2'-Fluoro-L-Arabinofuranosyl Imidazole Derivatives, Süreyya Ölgen Jan 2002

Synthesis Of 2'-Deoxy-2'-Fluoro-L-Arabinofuranosyl Imidazole Derivatives, Süreyya Ölgen

Turkish Journal of Chemistry

A new series of imidazole nucleosides was synthesized via direct condensation and construction of heterocyclic moiety from glycosyl amine templates. The characterization of the compounds was accomplished by elemental analysis, ^{1}H-NMR, ^{13}C-NMR, IR, UV-VIS spectral data and optical rotation.

Go to article

Phenylethanoid Glycosides From Scutellaria Galericulata, Tayfun Ersöz, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland Jan 2002

Phenylethanoid Glycosides From Scutellaria Galericulata, Tayfun Ersöz, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland

Turkish Journal of Chemistry

From the aerial parts of Scutellaria galericulata L., four phenylethanoid glycosides, 2-(4-hydroxyphenyl)-ethyl-(6-O-caffeoyl)-\beta -D-glucopyranoside (1), calceolarioside B (2), osmanthuside E (3) and martynoside (4), were isolated. The structure elucidations of the isolated compounds were performed by spectroscopic (UV, IR, ESI-MS, 1D- and 2D-NMR) methods. Compounds 1-4 demonstrated scavenging properties toward the 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical in TLC autographic assays.

Go to article

Bromination Of 2,3-Dibromobenzobarrelene At Different Conditions: Highly Brominated Benzobicyclic Systems, Ari̇f Daştan Jan 2002

Bromination Of 2,3-Dibromobenzobarrelene At Different Conditions: Highly Brominated Benzobicyclic Systems, Ari̇f Daştan

Turkish Journal of Chemistry

The electrophilic addition of bromine to 2,3-dibromobenzobarrelene at 10^oC led to the formation of completely rearranged products in high yield. Bromination of 2,3-dibromobenzobarrelene with molecular bromine in decalin at 150^oC and with DBTCE in CCl_{4} at 77^oC gave rearranged and non-rearranged products. The radical and ionic mechanism are discussed. All compounds were characterized properly, by NMR spectroscopy and chemical transformation.

Go to article

Synthesis Of New Substituted 6-(Morpholin-4-Yl)-1h-Benzimidazole Derivatives, Canan Kuş Jan 2002

Synthesis Of New Substituted 6-(Morpholin-4-Yl)-1h-Benzimidazole Derivatives, Canan Kuş

Turkish Journal of Chemistry

A series of various substituted benzimidazole derivatives containing fluoro and morpholino substituents at the 5 and 6 positions was synthesized and their structures were identified by spectroscopic techniques.

Go to article

The Simultaneous Determination Of Quinoline Yellow (E-104) And Sunset Yellow (E-110) In Syrups And Tablets By Second Derivative Spectrophotometry, Mahmure Üstün Özgür, İkbal Koyuncu Jan 2002

The Simultaneous Determination Of Quinoline Yellow (E-104) And Sunset Yellow (E-110) In Syrups And Tablets By Second Derivative Spectrophotometry, Mahmure Üstün Özgür, İkbal Koyuncu

Turkish Journal of Chemistry

A very simple spectrophotometric method using measurements at zero-crossing wavelength is described for resolving binary mixtures of the food dyes, Sunset Yellow (E-110) and Quinoline Yellow (E-104). Calibration graphs are linear up to 15.0 \mu gml^{-1} of Sunset Yellow (r = 0.9998), and Quinoline Yellow (r = 0.9999). The assay procedure for E-110 and E-104 in pharmaceutical products involves the extraction of the dyes with AcOH/NaOAc buffer solution (pH = 4.5), filtration, and measurement of the second derivative absorbance values at 410.0 nm for E-104 and 533.1 nm for E-110. This method was used for determining synthetic mixtures of these …

Go to article

Synthesis, Spectral And Thermal Degradation Kinetics Of Divalent Cadmium Complexes Of Dothiepine And Diphenhydramine, Halehatty S. Bhojya Naik, Parasuramapuma R. Chetana, Hosakere D. Revanasiddappa Jan 2002

Synthesis, Spectral And Thermal Degradation Kinetics Of Divalent Cadmium Complexes Of Dothiepine And Diphenhydramine, Halehatty S. Bhojya Naik, Parasuramapuma R. Chetana, Hosakere D. Revanasiddappa

Turkish Journal of Chemistry

Cadmium(II) complexes with 3-(6H-dibenzo[b,e] thiepin-11-ylidene) propyl dimethyl amine chloride (dot) and 2-diphenyl methoxy--N,N-dimethylamine hydrochloride (dp) were synthesised and characterised by reflectance, IR, ^{1}H NMR, magnetic moments and conductivity measurements. The new complexes studied for kinetics of thermal degradation by thermogravimetric analyses (TGA) and derivative thermogravimetric studies (DTG) in a static nitrogen atmosphere at a heating rate of 10°C min^{-1}. The kinetic and thermodynamic parameters such as energy of activation (Ea), frequency factor (lnA), enthalpy (\Delta H), free energy (\Delta H), and entropy (\Delta S) evaluated. The energy of activation values for the degradation of (dot) and (dp) complexes were found …

Go to article

Synthesis And Magnetic, Spectral And Thermal Studies On Metal 1,3,8,10,15,17,22,24-Octanitrophthalocyanines, Kallam R. Venugopala Reddy, Jathi Keshavayya Jan 2002

Synthesis And Magnetic, Spectral And Thermal Studies On Metal 1,3,8,10,15,17,22,24-Octanitrophthalocyanines, Kallam R. Venugopala Reddy, Jathi Keshavayya

Turkish Journal of Chemistry

A simple and novel method for the preparation of 1,3,8,10,15,17,22,24-octanitrophthalocyanine derivatives, MPcON's (M = Fe (III)Cl, Zn(II), Co(II), Cu(II) and Ni(II)), was developed. The dark green complexes were characterized by elemental analysis, electronic spectra, IR spectra, thermogravimetry, differential thermal analysis, powder X-ray diffraction and magnetic susceptibility.

Go to article

Solid-Phase Extraction Of Copper With Lead 4-Benzylpiperidinedithiocarbamate On Microcrystalline Naphthalene And Its Spectrophotometric Determination, Hasan Cesur, Beki̇r Bati Jan 2002

Solid-Phase Extraction Of Copper With Lead 4-Benzylpiperidinedithiocarbamate On Microcrystalline Naphthalene And Its Spectrophotometric Determination, Hasan Cesur, Beki̇r Bati

Turkish Journal of Chemistry

Using lead 4-benzylpiperidinedithiocarbamate complex (Pb(4-BPDC)_{2}), a solid-phase extraction method was developed for pre-concentration and spectrophotometric determination of copper in water samples. In this method, copper in large volume liquid phase quantitatively replaces lead on colorless Pb(4-BPDC)_{2} complex and naphthalene solid phase mixture forming Cu-4-benzylpiperidinedithiocarbamate complex (Cu(4-BPDC)_{2}). The solid phase containing colored Cu(4-BPDC)_{2} is dissolved in chloroform and its absorbance is measured at 437 nm against the reagent blank. The range of linearity is 0.4 -10 \mu gml^{-1} of copper in chloroform, the molar absorptivity of the complex determined from the linear portion of Beer's law plot is 8.197x10^{3} lmol^{-1}cm^{-1} and …

Go to article

Synthesis, Characterization And Thermal Analysis Of Organotin(Iv) Derivatives Of 4-(N-Maleoyl)Butanoate, Khadija Shahid, Saqib Ali, Moazzam H. Bhatti, Muhammad Mazhar, Sohail Mahmood, Sadiqur Rehman Jan 2002

Synthesis, Characterization And Thermal Analysis Of Organotin(Iv) Derivatives Of 4-(N-Maleoyl)Butanoate, Khadija Shahid, Saqib Ali, Moazzam H. Bhatti, Muhammad Mazhar, Sohail Mahmood, Sadiqur Rehman

Turkish Journal of Chemistry

Organotin(IV) derivatives of the type R_{4 - n}SnL_{n} where R = Me, n-Bu, Ph, L = 4 - (N-maleoyl)butanoate and n = 1 or 2 were synthesized by refluxing R_{3}SnCl and R_{2}SnCl_{2} with (4-(N-maleoyl)butanoate in the presence of triethylamine using dry toluene as solvent. These compounds were characterized by IR, multinuclear NMR and mass spectrometry. We also studied their thermal behavior and calculated the degradation pattern, energy of activation (E_{a}) and order of reaction (n).

Go to article

Electrochemical Behavior Of Benzo[C]Cinnoline And Its Bromo Derivatives, Ni̇lgün Seçken, M. Levent Aksu, Ali̇ Osman Solak, Emi̇ne Kiliç Jan 2002

Electrochemical Behavior Of Benzo[C]Cinnoline And Its Bromo Derivatives, Ni̇lgün Seçken, M. Levent Aksu, Ali̇ Osman Solak, Emi̇ne Kiliç

Turkish Journal of Chemistry

The electrochemical behavior of benzo[c]cinnoline and some of its bromo derivatives was studied. Two discrete 2-electron reduction waves in acidic and only one wave in basic media in ethyl alcohol-BR buffer system (l:5 v/v) were observed. A mechanism for the electrode reaction is proposed. Diffusion coefficients, formal potentials for and the derivatives, the number of electrons transferred were determined by using sampled current polarography, cyclic voltammetry, chronoamperometry, chronocoulometry and constant potential coulometry. Adsorption of the molecules on the surface of the mercury drop was analyzed and this phenomena was exploited to calculate the formal potentials and the diffusion coefficients of …

Go to article

The Second And Third Density Virial Coefficients Of Six Ar-Ne Mixtures At 25.0°C, Önder Korfali Jan 2002

The Second And Third Density Virial Coefficients Of Six Ar-Ne Mixtures At 25.0°C, Önder Korfali

Turkish Journal of Chemistry

In this paper we present a detailed experimental study of fractions, x_{Ar} = 0.0821, 0.2727, 0.3618, 0.5838, 0.7722 and 0.9049 at 25.0°C. The pressures are measured with a dead -- weight tester. The densities are determined from knowledge of the precise volume and weight measurement of the mixtures. Statistical analysis of the experimental data yielded very precise values for the second and third density virial coefficients. The second virial coefficients calculated with the least squares fitting method and corresponding to above argon mole fractions are 10^6B = 11.03, 9.16, 7.65, 1.83, -4.98 and --11.00 m^3mole^{-1}. Similarly the third virial coefficients …

Go to article

A Spectrophotometric Method For The Determination Of Prazosin Hydrochloride In Tablets, Mahmure Üstün Özgür, Sidika Sungur Jan 2002

A Spectrophotometric Method For The Determination Of Prazosin Hydrochloride In Tablets, Mahmure Üstün Özgür, Sidika Sungur

Turkish Journal of Chemistry

A rapid and sensitive analytical method was developed for the spectrophotometric assay of prazosin hydrochloride. The method is based on the formation of a coloured derivative between the drug and 1,2-naphthoquinone-4- sulphonic acid sodium salt (NQS). The reaction proceeds quantitatively at pH 4.5 and 70°C for 40 min. After the extraction of the derivative with chloroform: n-butanol (3:1), the absorbance was measured at 400 nm. The method was applied to commercially available tablets and the results were statistically compared with those obtained by ultraviolet spectrophotometric and differential pulse polarographic methods using t- and F-tests.

Go to article

Determination Of Oxygen And Nitrogen Impurities In Magnesium Metal By Vacuum Distillation And Icp-Oes Techniques, Javed Akhtar, S. K. Durrani, N. A. Chughtai, M. Munir, Bashir Mohammad Jan 2002

Determination Of Oxygen And Nitrogen Impurities In Magnesium Metal By Vacuum Distillation And Icp-Oes Techniques, Javed Akhtar, S. K. Durrani, N. A. Chughtai, M. Munir, Bashir Mohammad

Turkish Journal of Chemistry

Due to the various promising properties of magnesium as a structural material and certain other applications such as a reducing agent for refractory metals, magnesium metal has great commercial importance in many technical industries but the presence of oxygen and nitrogen impurities adversely affects its physico-chemical and mechanical properties. Therefore, the exact measurement of oxygen and nitrogen impurities is essential. The accuracy of analytical values of micro amounts of nitrogen and oxygen (\mu g.g^{-1} level) in magnesium metal has been measured indirectly. The conditions for the vacuum distillation (VD) method were optimized. Analysis of residue for magnesium content was studied …

Go to article

Application Of Proton Conducting Polymer Electrolytes To Electrochromic Devices, Ayhan Bozkurt Jan 2002

Application Of Proton Conducting Polymer Electrolytes To Electrochromic Devices, Ayhan Bozkurt

Turkish Journal of Chemistry

Electrochromic display devices have been fabricated using Polydiallyldimethylammonium dihydrogenphosphate (PAMA^+ H_2PO_4^-) blended with H_3PO_4 as the electrolyte and WO_3 as the electrochromic film. The WO_3 deposited glass electrodes were doped with protons to form H_xWO_3 in which color depends on the charge density (CD) ranging from 0.01 to 0.04 C/cm^2. Proton conducting films of PAMA^+ H_2PO_4^- 2 H_3PO_4 (2 moles of acid per polymer repeat unit) were sandwiched between two electrodes to obtain the following symmetric configuration: Glass/ITO/WO_3/H^+ -electrolyte film/H_xWO_3 /ITO/Glass. Prior to construction of the electrochromic windows, the electrochemical stability of polymer/acid blends was determined via cyclic voltammetry (CV).

Go to article

Electrodeposition Of Zinc From Chloride Solution, Yanjerappa Arthoba Naik, Thimmappa V. Venkatesha, Perdur Vasudeva Nayak Jan 2002

Electrodeposition Of Zinc From Chloride Solution, Yanjerappa Arthoba Naik, Thimmappa V. Venkatesha, Perdur Vasudeva Nayak

Turkish Journal of Chemistry

The electroplating of zinc is carried out in the presence of 3,4,5-Trimethoxy benzaldehyde from a chloride bath. The bath constituents are optimized through Hull cell experiments. Operating parameters such as pH, temperature, and current density are also optimized. The current efficiency and throwing power are measured at different current densities. Polarization study is carried out under galvanostatic conditions. Corrosion resistance test indicated good protection of steel by the coating. The consumption of brightener is determined in the laboratory scale. SEM photomicrographs revealed fine-grained structure of the deposit from the optimum bath. IR spectrum of the scratched deposit showed inclusion of …

Go to article

Determination Of Ascorbic Acid In Vegetables By Derivative Spectrophotometry, Zeynep Aydoğmuş, S. Müge Çeti̇n, Mahmure Üstün Özgür Jan 2002

Determination Of Ascorbic Acid In Vegetables By Derivative Spectrophotometry, Zeynep Aydoğmuş, S. Müge Çeti̇n, Mahmure Üstün Özgür

Turkish Journal of Chemistry

Determination of ascorbic acid (AA) in garlic, green pepper and chestnut was performed by derivative spectrophotometry without using any pre-separation or background correction techniques. The method is based on the measurement of the distances between two extremum values (peak-to-peak amplitudes) in second and third order derivative spectra of the extracts. Ten percent trichloroacetic acid was found to be the most suitable extraction solution. In the second order derivative spectrum the extrema of 253.2 and 259 nm for garlic, and in the third order derivative spectrum, the extrama of 256.4 and 261.6 nm for green pepper and chestrut samples were used …

Go to article

Determination Of Fatty Acid Composition And Total Trans Fatty Acids In Cereal-Based Turkish Foods, Orhan Dağlioğlu, Murat Taşan, Bariş Tunçel Jan 2002

Determination Of Fatty Acid Composition And Total Trans Fatty Acids In Cereal-Based Turkish Foods, Orhan Dağlioğlu, Murat Taşan, Bariş Tunçel

Turkish Journal of Chemistry

The fatty acid composition and trans fatty acids of 13 cereal-based foods produced by Turkish companies were analysed by capillary gas-liquid chromatography. The total fat contents of the samples ranged from 1.8 to 37.9%. Traditional Turkish white bread and bulgur had the lowest fat content (1.8% and 2.3% respectively) and wafer the highest (37.9%). The major fatty acids in the samples were C_{16:0}, C_{18:0}, trans C_{18:1}, C_{18:1} and C_{18:2}. Total unsaturated fatty acid contents varied between 49.0 and 80.3% of total fatty acids, and bulgur had the highest percentage among the samples. Except for bulgur, all the samples contained trans …

Go to article

Corrosion Of Reinforcing Steel In Concrete Immersed In Chloride Solution And The Effects Of Detergent Additions On Diffusion And Concrete Porosity, Hülya Kahyaoğlu, Mehmet Erbi̇l, Bi̇rgül Yazici, Ayşe Bahar Yilmaz Jan 2002

Corrosion Of Reinforcing Steel In Concrete Immersed In Chloride Solution And The Effects Of Detergent Additions On Diffusion And Concrete Porosity, Hülya Kahyaoğlu, Mehmet Erbi̇l, Bi̇rgül Yazici, Ayşe Bahar Yilmaz

Turkish Journal of Chemistry

In order to investigate the corrosion of reinforcing steel in concrete and the effects of chloride ions, oxygen diffusion and detergent additives of linear alkylbenzene (LAB) and linear alkylbenzene sulfonate (LAS), potentiokinetic experiments were carried out. Thus, by embedding steel electrodes into concrete specimens with a water/cement (W/C) ratio of 0.45, current-potential curves were obtained and the compressive strength of the specimens was measured. The electrochemical approach can be used to identify the effect of chloride on steel corrosion in concrete. It was found that the diffusion of chloride and oxygen through concrete and the reduction of oxygen on the …

Go to article

The Effect Of Nicotinamide On Iron Corrosion In Chloride Solutions, Tunç Tüken, Bi̇rgül Yazici, Mehmet Erbi̇l Jan 2002

The Effect Of Nicotinamide On Iron Corrosion In Chloride Solutions, Tunç Tüken, Bi̇rgül Yazici, Mehmet Erbi̇l

Turkish Journal of Chemistry

The use of nicotinamide ``3-pyridineamide'' as an iron corrosion inhibitor was tested in aerated aqueous solutions of NaCl and Na_2SO_4 for different pH values. Polarization resistance (R_p) measurements, polarization curves and AC impedance spectroscopy techniques were used to obtain experimental data. Nicotinamide (ND) was found to exhibit a cationic-type inhibitor behaviour in acidic solution of NaCl (pH 3) and also a weak inhibitory effect in acidic sulphate solution (pH 3). The impedance spectra at open circuit potential showed that the corrosion process of the metal was characterized by two distinguishable capacitive loops. The charge transfer resistance (R_t) and the polarization …

Go to article

Non-Covalent Immobilization Of Quince (Cydonia Oblonga) Polyphenol Oxidase, Hülya Yağar, Ayten Sağiroğlu Jan 2002

Non-Covalent Immobilization Of Quince (Cydonia Oblonga) Polyphenol Oxidase, Hülya Yağar, Ayten Sağiroğlu

Turkish Journal of Chemistry

A partially purified polyphenol oxidase from quince (Cydonia oblonga) was immobilized on bentonite by simple adsorption at pH 6.8. The properties of the immobilized enzyme were compared to those of the free enzyme. Optimum pH and temperature were determined to be 9.0 and 45°C, respectively, showing the alteration of pH and temperature profiles by immobilization. No drastic change was observed in the K_m value after immobilization. Catechol, L-DOPA, p-cresole and pyrogallol were tested as substrates. Thermal and storage stability and reusability experiments were carried out. It was observed that the immobilized enzyme had storage stability for a period of one …

Go to article

First Prev Next Last