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Articles 9061 - 9090 of 10317
Full-Text Articles in Physical Sciences and Mathematics
Phenolic Constituents From Phlomis Lycia, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Yukio Ogihara
Phenolic Constituents From Phlomis Lycia, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Yukio Ogihara
Turkish Journal of Chemistry
From the aerial parts of Phlomis lycia L. (Labiatae) a lignan glucoside, (-)-dihydrodehyrodiconiferyl alcohol-9-O-\beta -D-glucopyranoside (1); a caffeic acid ester, chlorogenic acid (2); three phenylethanoid glycosides, forsythoside B (3), alyssonoside (4) and leucosceptoside B(5); and two iridoid glucosides, lamiide (6) andauroside (7), were isolated. The structure elucidation of the isolated compounds was carried out by spectroscopic (UV, IR, 1D- and 2D-NMR, FAB-MS) methods. (-)-Dihydrodehyrodiconiferyl alcohol-9-O-\beta -D-glucopyranoside (1) and chlorogenic acid (2) were isolated for the first time from Phlomis species in this study.
A New Synthesis Of Bromobenzotropones: Oxidation Of 8-Bromo-5 H -Benzo[A]Cycloheptene, Ari̇f Daştan, Y. Kemal Yildiz, Cavi̇t Kazaz, Meti̇n Balci
A New Synthesis Of Bromobenzotropones: Oxidation Of 8-Bromo-5 H -Benzo[A]Cycloheptene, Ari̇f Daştan, Y. Kemal Yildiz, Cavi̇t Kazaz, Meti̇n Balci
Turkish Journal of Chemistry
The oxidation of 8-bromo-5H-benzo[a]cycloheptene with some oxidation reagents was studied. 2,3- and 4,5-benzotropone derivatives were obtained. The structures of the bromobenzotropones were determined by ^{1}H- and ^{13}C-NMR data.
Synthesis And Electronic Structure Of New Aryl- And Alkyl-Substituted 1,3,4-Oxadiazole-2-Thione Derivatives, Feray Aydoğan, Zuhal Turgut, Nüket Öcal, Safi̇ye Sağ Erdem
Synthesis And Electronic Structure Of New Aryl- And Alkyl-Substituted 1,3,4-Oxadiazole-2-Thione Derivatives, Feray Aydoğan, Zuhal Turgut, Nüket Öcal, Safi̇ye Sağ Erdem
Turkish Journal of Chemistry
New 5-alkyl and 3-(2,4-dimethylphenyl) substituted 1,3,4-oxadiazole-2-thione derivatives were synthesized by the ring closure reactions of various acylhydrazides with carbon disulphide. Mannich bases for some of these compounds were also synthesized by condensation with benzaldehyde and primary amines. All new compounds were characterized by spectral data. Most of them were tested for their antibacterial and antituberculostatic activity. Molecular orbital calculations at the HF/6-31G** level were also performed to determine the optimized geometrical structures. Results indicated electron delocalization over several atoms of the ring. An additional study on the tautomeric equilibrium between 1,3,4-oxadiazole-2-thione and its thiol form showed that the thione tautomer …
Iridoid And Phenylpropanoid Glycosides From Phlomis Grandiflora Var. Fimbrilligera And Phlomis Fruticosa, Tayfun Ersöz, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Iridoid And Phenylpropanoid Glycosides From Phlomis Grandiflora Var. Fimbrilligera And Phlomis Fruticosa, Tayfun Ersöz, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Turkish Journal of Chemistry
From the aerial parts of Phlomis grandiflora var. fimbrilligera, two iridoid glucosides, 8-epi-loganin (1) and auroside (2), together with five phenylethanoid glycosides, forsythoside B (3), alyssonoside (4), verbascoside (5), hattushoside (6) and phlomisethanoside (7), were isolated. Iridoid glucosides auroside (2) and lamiide (8) and phenylethanoid glycosides, forsythoside B (3), alyssonoside (4), and verbascoside (5) as well as a lignan glucoside, syringaresinol-4 ' -O-\beta -D-glucoside (9), were characterized from the overground parts of P. fruticosa. The structures of the isolates were elucidated by means of one and two dimensional (COSY, HSQC and HMBC) NMR techniques and ESI MS.
Pyrrolizidine Alkaloids From Symphytum Sylvaticum Boiss. Subsp. Sepulcrale. (Boiss.& Bal.) Greuter & Burdetvar. Sepulcrale And Symphytum Aintabicum Hub.- Mor. & Wickens, Semra Kurucu, Murat Kartal, Muhammad Iqbal Choudhary, Gülaçti Topçu
Pyrrolizidine Alkaloids From Symphytum Sylvaticum Boiss. Subsp. Sepulcrale. (Boiss.& Bal.) Greuter & Burdetvar. Sepulcrale And Symphytum Aintabicum Hub.- Mor. & Wickens, Semra Kurucu, Murat Kartal, Muhammad Iqbal Choudhary, Gülaçti Topçu
Turkish Journal of Chemistry
Pyrrolizidine alkaloid (Echimidine-N-oxide) was isolated from Symphytum sylvaticum Boiss. subsp. sepulcrale (Boiss. & Bal.) Greuter & Burdet var. sepulcrale and pyrrolizidine alkaloid (Echimidine) was isolated from Symphytum aintabicum Hub. - Mor. & Wickens. The structures of the isolated compounds were elucidated based on IR, EIMS, ^{1}H, and ^{13}C NMR analysis and also on 2D NMR (COSY, HMBC, HMQC) experiments.
Thermodynamic And Kinetic Parameters Concerning Complex Formation Between 3-Hydroxy- And 1-Aminopyrene And Pyridine, Nursel Acar, Özgül Koçak
Thermodynamic And Kinetic Parameters Concerning Complex Formation Between 3-Hydroxy- And 1-Aminopyrene And Pyridine, Nursel Acar, Özgül Koçak
Turkish Journal of Chemistry
Systems formed by the pyrene derivatives 3-hydroxypyrene and 1-aminopyrene with pyridine were studied. The thermodynamic and kinetic parameters of the systems were calculated using the changes in the absorption and emission spectra which occur due to hydrogen bond or complex formation. The decrease of the formation rate constant in the series methylcyclohexane, benzene, and o-chlorotoluene may be due to a more difficult formation of the hydrogen bond complex due to the increase of the dielectric constant in the solvent series.
Glycine Transport Through A Charged Polysulfone Cation Exchange Membrane, Nuri̇ Ünlü, Hüseyi̇n Kara, Mustafa Ersöz
Glycine Transport Through A Charged Polysulfone Cation Exchange Membrane, Nuri̇ Ünlü, Hüseyi̇n Kara, Mustafa Ersöz
Turkish Journal of Chemistry
The transport of glycine through a charged polysulfone cation exchange membrane was studied as a function of pH at different initial conditions of less than pH 5.9 and the glycine permeability was explained under the experimental conditions as pH dependent interfacial transport. The glycine permeability increases with a decreasing pH in the receiver phase. The largest permeability was obtained if the initial pH on the source side was pH 5.9 and that on the opposite side was pH 2.0. The transport phenomena can be explained by the interfacial transport based on the interfacial chemical reaction (protonation, deprotonation or ion-exchange) between …
Solvent, Temperature And Concentration Effects On The Adsorption Of Poly(N-Butyl Methacrylate) On Alumina From Solutions, Nursel Pekel, Olgun Güven
Solvent, Temperature And Concentration Effects On The Adsorption Of Poly(N-Butyl Methacrylate) On Alumina From Solutions, Nursel Pekel, Olgun Güven
Turkish Journal of Chemistry
Adsorption of poly(n-butyl methacrylate) (PnBMA) on alumina from solution was studied by UV and FT-IR Photoacoustic Spectroscopy techniques. The effects of the solvent, temperature, concentration, and molecular weight of the polymer on adsorption were investigated. Three solvents, cyclohexane, carbon tetrachloride and benzene, were employed. The adsorption was dependent on molecular weight and much more polymer was adsorbed in cyclohexane than in other solvents on the alumina surface. A decrease in adsorption was observed with increasing temperature. The results are in conformity with Langmuir's isotherm. The differences observed in Langmuir parameters were explained by polymer-polymer, polymer-solvent, polymer-adsorbent, and solvent-adsorbent interactions.
The Kinetics And Mechanism Of Oxidation Of Vanillin By Diperiodatonickelate(Iv) In Aqueous Alkaline Medium, Chandrashekhar Kathari, Pandurang Pol, Sharanappa Nandibewoor
The Kinetics And Mechanism Of Oxidation Of Vanillin By Diperiodatonickelate(Iv) In Aqueous Alkaline Medium, Chandrashekhar Kathari, Pandurang Pol, Sharanappa Nandibewoor
Turkish Journal of Chemistry
The title reaction was investigated in aqueous alkaline medium. A first order dependence in diperiodatonickelate (IV) (DPN) and an apparent fractional order in both vanillin and alkali were obtained. Periodate has a retarding effect on the reaction. The effect of added products and the ionic strength of the reaction medium have no significant effect on the reaction rate. A decrease in the dielectric constant of the medium decreases the rate of reaction. Effects of temperature on the rate of reaction were studied. A mechanism based on experimental results was proposed, and constants involved in the mechanism were evaluated. A good …
Synthesis, Spectral And Fungicidal Studies On Dioxobridged Binuclear Niobium(V) And Tantalum(V) Complexes Of N-Alkylphenothiazines, Boregowda Keshavan, Hunasegala Kempe Gowda
Synthesis, Spectral And Fungicidal Studies On Dioxobridged Binuclear Niobium(V) And Tantalum(V) Complexes Of N-Alkylphenothiazines, Boregowda Keshavan, Hunasegala Kempe Gowda
Turkish Journal of Chemistry
Six new dioxobridged binuclear complexes of the type [MO(L)Z]_{2}Z, where M=niobium(V) or tantalum(V), L=N-alkylphenothiazines (NAPs) and Z=tartrate and oxalate for niobium and tantalum respectively, were synthesized. The stoichiometry of the complexes was proposed on the basis of elemental analyses, molar conductance, magnetic and thermal data. The coordination behaviour of the ligands was determined with the help of spectroscopic studies. The fungicidal activity of the complexes was evaluated.
Aspertins A-D: Further Piperidine Alkaloids From Andrachne Aspera} (Euphorbiaceae), Viqar Uddin Ahmad, Arshad Kamal, Muhammad Shaiq Ali
Aspertins A-D: Further Piperidine Alkaloids From Andrachne Aspera} (Euphorbiaceae), Viqar Uddin Ahmad, Arshad Kamal, Muhammad Shaiq Ali
Turkish Journal of Chemistry
The aerial parts of Andrachne aspera belonging to the family Euphorbiaceae yielded four new piperidine alkaloids: aspertin-A (1), aspertin-B (2), aspertin-C (3) and aspertin-D (4). The structures of isolated alkaloids were elucidated by NMR, mass spectrometery and chemical means.
Diels-Alder Reactions Using 5 M Liclo_{4} -Diethyl Ether Catalyst, Mesut Kacan, H. R. Ferhat Karabulut
Diels-Alder Reactions Using 5 M Liclo_{4} -Diethyl Ether Catalyst, Mesut Kacan, H. R. Ferhat Karabulut
Turkish Journal of Chemistry
The rate acceleration of Diels-Alder reactions in 5.0 M lithium perchlorate-diethyl ether was re-examined using itaconic anhydride and itaconic acid. Rate acceleration was observed for non-functionalised dienes, but functionalised dienes gave the starting or polymeric materials.
Synthesis Of 2'-Deoxy-2'-Fluoro-L-Arabinofuranosyl Imidazole Derivatives, Süreyya Ölgen
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.
Determination Of Zinc In Aerosol Samples By Discrete Nebulization Flame Atomic Absorption Spectrometry, Deni̇z Yurtsever Sarica, Di̇lek Akim, Tuncel Özden
Determination Of Zinc In Aerosol Samples By Discrete Nebulization Flame Atomic Absorption Spectrometry, Deni̇z Yurtsever Sarica, Di̇lek Akim, Tuncel Özden
Turkish Journal of Chemistry
A well-known analytical method, ``discrete nebulization'', which is suitable for samples having a limited amount like body fluids, high solid content or salt solutions, and less volatile metals, has been further developed for zinc determination in aerosol samples. The effects of injection volume and nebulizer aspiration rate on absorbance and precision were studied. A calibration graph was obtained linearly up to 1.75 mg/L Zn with a 0.9988 correlation coefficient and 3.09\% RSD using 50 \mu L injection volume, values comparable to conventional continuous nebulization. The detection limit (3S) achieved by the method was calculated to be 1.09 ng or 0.020 …
Determination Of Trace Elements In Iron Minerals By Atomic Absorption Spectrometry, Trajce Stafilov, Dragica Zendelovska
Determination Of Trace Elements In Iron Minerals By Atomic Absorption Spectrometry, Trajce Stafilov, Dragica Zendelovska
Turkish Journal of Chemistry
A method for the determination of lead, cobalt, nickel, chromium, zinc and manganese in iron minerals siderite (FeCO_3), hematite (Fe_{2}O_{3), pyrite and marcasite (FeS_{2) by flame and Zeeman electrothermal atomic absorption spectrometry (ETAAS) was developed. Interferences were investigated by measuring the absorbance of the elements investigated in series of samples with varying mass ratios of the elements investigated and iron as the potential interfering element. It was found that there was no interference in the determined mass ratios of iron on the absorbance of Mn and Zn and that they could be directly analyzed by flame and electrothermal atomic absorption …
A Comparative Study For Basic Characterization Of Three Clinoptilolite Specimens, Eva Chmielewska, Eva Samajova, Jan Kozac
A Comparative Study For Basic Characterization Of Three Clinoptilolite Specimens, Eva Chmielewska, Eva Samajova, Jan Kozac
Turkish Journal of Chemistry
Physicochemical and mineralogical characteristics of the clinoptilolite tuffs of Chinese, Slovakian and American origin were investigated using various techniques, i.e. X - ray powder diffraction, water vapour desorption, ion exchange and chemical analysis.
A Semi-Empirical Study On Metal Ion/Murexide Complexation, N. Zeynep Atay, Tereza Varnali
A Semi-Empirical Study On Metal Ion/Murexide Complexation, N. Zeynep Atay, Tereza Varnali
Turkish Journal of Chemistry
Modeling of the metal ion/ligand complexation reactions between divalent metal cations (M^{2 +} ) and hydrophilic tridentate ligand murexide (Mu^{-} ) in water, water+glycerol, and in glycerol was carried out. Kinetic studies showed that the rate of the reaction is very dependent on the metal ion, with Zn^{2 +} > Ni^{2 +} , but, reactions are slower in dispersed glycerol than in dispersed water. Theoretical calculations, which have shown a metal ion dependence, were consistent with the experimental observations. The entropy values calculated in all solvents were negative and were similar in value, indicating that these spontaneous reactions are enthalpy driven.
Ft-Ir And Ft-Raman Studies On 3-Aminophthalhydrazide And N-Aminophthalimide, N. Puviarasan, V. Arjunan, S. Mohan
Ft-Ir And Ft-Raman Studies On 3-Aminophthalhydrazide And N-Aminophthalimide, N. Puviarasan, V. Arjunan, S. Mohan
Turkish Journal of Chemistry
The FT-infrared (400-4000 cm^{-1} ) and FT-Raman (100-3500 cm^{-1} ) spectra of N-aminophthalimide and 3-aminophthalhydrazide were recorded. The observed frequencies were assigned to various modes of vibrations on the basis of normal coordinate analysis, assuming C_{S} point group symmetry. The potential energy distribution associated with normal modes is also reported. The assignments of fundamental vibrations agree well with the calculated frequencies.
Application Of Quantitative Structure-Retention Relationships (Qsrr) To A Set Of Organic Bromo And Nitrile Derivatives, Gustavo P. Romanelli, Juan Carlos Autino, Eduardo A. Castro
Application Of Quantitative Structure-Retention Relationships (Qsrr) To A Set Of Organic Bromo And Nitrile Derivatives, Gustavo P. Romanelli, Juan Carlos Autino, Eduardo A. Castro
Turkish Journal of Chemistry
The retention times are studied for two sets of 1-bromo-2-aryiloxyetanes and 3- aryloxypropiononitriles derivatives by means of Quantitative Structure-Retention Relationships (QSRR}). Five quantum mechanical molecular descriptors are used to calculate the regression equations. The fitting polynomials are computed in several-variable at first, second, and third order equations. Results are only significant when resorting to several-variable formulae which seems to point out the rather complex physical chemistry nature of the property under study.
Flow Injection Extraction - Spectrophotometric Determination Of Bismuth With Di-(Hydrogenated Tallow Alkyl) Dimethylammonium Chloride, S. A. Barakat
Flow Injection Extraction - Spectrophotometric Determination Of Bismuth With Di-(Hydrogenated Tallow Alkyl) Dimethylammonium Chloride, S. A. Barakat
Turkish Journal of Chemistry
Bismuth(III) (0-25 \mu g/ml) is determined spectrophotometricaly at 513 nm after extraction into dichloromethane of the ion associate di-(hydrogenatedtallowalkyl)dimethylammonium tetraiodobismuthate. The reagent stream is distilled water, merged with 1.0 M sulfuric acid, 5% potassium iodide and 5% (w/v) ascorbic acid solution. The reagent stream is 0.2% (w/v) di-(hydrogenatedtallowalkyl)dimethylammonium chloride solution. The injection rate is 15 h^{-1}. The calibration graph is linear up to 25 \mu g/ml. The detection limit is 0.35 \mu g/ml Bi. The system is applied on water samples and copper-based alloys.
Spectrophotometric Studies Of The Behavior Of P-Amino-N, N-Dimethyl Aniline With Ferric Nitrate In Methanol, Ali Hassoon Al-Taiar, Suhad K. Shubber, A. Megherbi
Spectrophotometric Studies Of The Behavior Of P-Amino-N, N-Dimethyl Aniline With Ferric Nitrate In Methanol, Ali Hassoon Al-Taiar, Suhad K. Shubber, A. Megherbi
Turkish Journal of Chemistry
The UV-visible absorption bands of the new complex were obtained using p-amino-N, N-dimethyl aniline as an electron donor with ferric nitrate as an electron acceptor in methanol at 25°C. The values of association constant K^{AD}, molar extinction coefficient \varepsilon^{AD}, and absorption band energy of charge transfer complex h \varepsilon_{CT} were calculated. The ionization potential of the donor I^{D}, was calculated from the complex band energy. The kinetics of the above association reaction were studied. This reaction was found to be a first order. The values of the rate constant of the forward reaction k_{1}, the rate constant of the reverse …
An Indirect Lectin Affinity Bioassay For Uromodulin, Zeki̇ Topcu
An Indirect Lectin Affinity Bioassay For Uromodulin, Zeki̇ Topcu
Turkish Journal of Chemistry
Uromodulin is a monomeric glycoprotein excreted in large amounts in urine. Most of the assay methods for quantifying uromodulin rely on the availability of antibodies to this glycoprotein. This study reports a new bioassay for uromodulin without requiring the presence of antibodies. The bioassay is based on the lectin affinity of the glycoprotein and the known interaction between uromodulin and the tumor necrosis factor. The measuring range of the bioassay described in this paper is between 0.13 and 1.25 \mu g/ml, which makes it a potential method for clinical use.
Efficient Synthesis Of 1-Alkoxycarbonyl-Methyl-2-Alkylpyrroles From Dichloro- And Methoxychloropropylalkyl Ketones, Raik A. Gadzhili, Raya A. Nadzhafova, Özge Şeşenoğlu
Efficient Synthesis Of 1-Alkoxycarbonyl-Methyl-2-Alkylpyrroles From Dichloro- And Methoxychloropropylalkyl Ketones, Raik A. Gadzhili, Raya A. Nadzhafova, Özge Şeşenoğlu
Turkish Journal of Chemistry
The condensation reaction of 2,3-dichloropropyl- and 2-methoxy-3-chloropropyl alkyl ketones with alkyl 2-aminoacetate salts leads to 1-alkoxy-carbonylmethyl-2-alkylpyrroles. These compounds, with various bases, gave 1-carbamoylmethyl-, 1-dialkylaminocarbonylmethyl-, 1-carbazoyl methyl-2-alkylpyrroles and potassium salt of 2-alkyl-pyrrolyl-1-acetic acid.
Determination Of Ternary Mixtures Of Vitamins (B_{1}, B_{6}, B_{12}) By Zero-Crossing Derivative Spectrophotometry, Mahmure Üstün Özgür, İkbal Koyuncu
Determination Of Ternary Mixtures Of Vitamins (B_{1}, B_{6}, B_{12}) By Zero-Crossing Derivative Spectrophotometry, Mahmure Üstün Özgür, İkbal Koyuncu
Turkish Journal of Chemistry
A new method for determining ternary mixtures of vitamin B_{1}, B_{6} and B_{12} using second derivative spectrophotometry is described. The procedure is accurate, nondestructive and does not require any separation step or the solving of equations. Calibration graphs were linear up to 20 \mu gml^{-1} of vitamin B_{1} at 228.9 nm (r=0.9999), vitamin B_{6} at 309.6 nm (r=0.9999) and vitamin B_{12} at 361.7 nm (r=0.9998). The method was successfully applied for analyzing synthetic mixtures and commercial pharmaceutical preparations.
Alteration Of Three Turkish Bentonites By Treatment With Na_{2}Co}_{3} And H}_{2}So}_{4}, Nuray Yildiz, Ayla Çalimli
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.
The Effects Of Benzoic Acid In Chloride Solutions On The Corrosion Of Iron And Aluminum, Si̇bel Zor
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 …
The Effect Of Acid Activation On Some Physicochemical Properties Of A Bentonite, Müşerref Önal, Yüksel Sarikaya, Tülay Alemdaroğlu, İhsan Bozdoğan
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 …
Production Of Mesophase Pitch From Coal Tar And Petroleum Pitches Using Supercritical Fluid Extraction, Mustafa Zafer Özel, Keith D. Bartle
Production Of Mesophase Pitch From Coal Tar And Petroleum Pitches Using Supercritical Fluid Extraction, Mustafa Zafer Özel, Keith D. Bartle
Turkish Journal of Chemistry
Supercritical fluid extraction (SFE) is currently being investigated as a possible technique in the production of high quality mesophase pitch from coal tar and petroleum pitches. Mesophase pitch is used to make high technology products, such as carbon fibre. The conventional production of mesophase pitch initially involves the removal of low molecular weight species from coal tar and petroleum pitches. The remaining residue is then transformed into a mesophase pitch through a polymerisation process. The aim of this study involves the extraction of light molecular weight species using SFE. Both petroleum and coal tar pitch contain complex aromatic molecules with …
Simultaneous Determination Of Fe(Ii) And Fe(Iii) In Pharmaceutical Samples By Post-Column Derivatization/Hplc, Hami̇de Z. Şenyuva, Deni̇z Yurtsever Sarica, Tuncel Özden
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 …
Chemical Exfoliation Characteristics Of Karakoç Phlogopite In Hydrogen Peroxide Solution, Erol Üçgül, İsmai̇l Gi̇rgi̇n
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 …