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Articles 29401 - 29430 of 34709
Full-Text Articles in Physical Sciences and Mathematics
Neural Networks In The Analysis Of Water-Soluble Sulfonylurea Herbicides Using An Lc/Ms, Joseph Michael Pompano
Neural Networks In The Analysis Of Water-Soluble Sulfonylurea Herbicides Using An Lc/Ms, Joseph Michael Pompano
Theses and Dissertations
In this research, a hidden node pruning algorithm was developed for an artificial neural network (ANN) that automatically determined a more efficient size of the hidden layer, caused the ANN to resize itself, and then continued to train using a standard back-propagation algorithm. The hidden-node pruning algorithm was based on determining the number of significant eigenvalues present in the matrix of values produced by the hidden layer, starting with an excessive number of hidden nodes.
Eight sulfonylurea herbicides were used as the target analytes in this study. The ability of an ANN to simplify the sample preparation needed for analysis …
Impedance Characteristics Of Conducting Polypyrrole-Poly(Ethylvinylether) Graft Films, E. Kalaycioğlu, Levent Toppare, T. Grchev, M. Cvetkovska, Y. Yağci
Impedance Characteristics Of Conducting Polypyrrole-Poly(Ethylvinylether) Graft Films, E. Kalaycioğlu, Levent Toppare, T. Grchev, M. Cvetkovska, Y. Yağci
Turkish Journal of Chemistry
Impedance characterization of graft copolymers of poly(2-(N-pyrrolyl)ethylvinylether) and polypyrrole (doped with BF_4^-) was elucidated in comparison with pure polypyrrole doped with BF_4^-.
^{13}C-And ^{31}P-Nmr Study Of Tetracarbonylbis(Diphenylphosphino)Alkanemetal(0) Complexes Of The Group 6 Elements, Zahi̇de Özer, Sai̇m Özkar
^{13}C-And ^{31}P-Nmr Study Of Tetracarbonylbis(Diphenylphosphino)Alkanemetal(0) Complexes Of The Group 6 Elements, Zahi̇de Özer, Sai̇m Özkar
Turkish Journal of Chemistry
Tetracarbonylbis(diphenylphosphino)alkanemetal(0) complexes of the general formula M(CO)_4[(C_6H_5)_2P (CH_2)_nP(C_6H_5)_2] (M: Cr, Mo, W; n: 1, 2, 3) were synthesized from the reaction of M(CO)_4(\eta^{2:2}-1,5-cyclooctadiene) with the appropriate ligand and characterized by means of IR and NMR (^{13}C and ^{31}P) spectroscopy. Spectroscopic data shows that two phosphorus atoms in the complexes are identical and occupy two cis-coordiantion sites in a pseudo-octahedral coordination sphere of the metal. The comparative study of the coordination shift and the ^{31}P-^{13}C coupling constant reveals that two carbonyl groups trans to one of two phosphorus atoms in the diphosphine ligand are shifted toward the lower magnetic field more …
Chemical Constituents Of Centaurea Cuneifolia, Ümi̇t Aslan, Sevi̇l Öksüz
Chemical Constituents Of Centaurea Cuneifolia, Ümi̇t Aslan, Sevi̇l Öksüz
Turkish Journal of Chemistry
The whole plant material fo Centaurea cuneifolia Sm. afforded three sesquiterpene lactones; cnicin (1), dehydromelitensin (2) and dehydromelitensin-8-[(2^{'}-\alpha-hydroxy-\beta- hydroxyethyl)-acryloyl)] (3), the lignan; (-)-arctigenin (4), flavonoids; salvigenin (5), eupatilin (6), jaceosidin (7), acacetin (8), kaemferol (9), 5,7,4^{'}-trihydroxy-3-methylether (10), 5-hydroxy-3^{'},^{'},6,7-tetramethoxyflavone (11) and 5-hydroxy-3^{'},4^{'},7,8-tetramet hoxyflavone (12), a triterpene; \alpha-amyrin and a sterol; \beta-sitosterol. The structures of the isolates were determined by IR, UV, ^1H and ^{13}C NMR and MS spectroscopy.
Effects Of Ozonation On Cod Elimination Of Substituted Aromatic Compounds In Aqueus Solution, Şermi̇n Gül, Osman Seri̇ndağ, Hami̇t Boztepe
Effects Of Ozonation On Cod Elimination Of Substituted Aromatic Compounds In Aqueus Solution, Şermi̇n Gül, Osman Seri̇ndağ, Hami̇t Boztepe
Turkish Journal of Chemistry
The chemical oxygen demand (COD) change of various substituted aromatic compounds, namely benzoic acid, p-aminobenzoic acid, p-toluenesulfonic acid, sulfanilic acid, nitro benzene, resorcinol, p-cresol, o- cresol, o-toluidine, aniline and 8-hydroxyquinoline were investigated at ozone doses of 5, 10, 15 and 20 mg O_{3}\cdotmin^{-1}, respectively. Percent COD removal of initial compounds after ozonation was compared with reported biodegradation results. The pH change and percent removal of selected compounds were also evaluated in ozone does of 20 mg O_{3}\cdotmin^{-1} up to 80 min. ozonation. The results showed that high ozone doses are needed to obtain better elimination of initial compounds and also …
An Efficient Acetylation Of Primary And Secondary Aliphatic Alcohols With Acetic Anhydride In The Presence Of Graphite Bisulphate, Hasan Seçen, A. Hami̇t Kalpar
An Efficient Acetylation Of Primary And Secondary Aliphatic Alcohols With Acetic Anhydride In The Presence Of Graphite Bisulphate, Hasan Seçen, A. Hami̇t Kalpar
Turkish Journal of Chemistry
In cyclohexane, thirteen examples of primary and secondary aliphatic alcohols were easily converted to the corresponding acetate derivatives within a short time, ranging from 5 min to 2.5 h, and in good yields close to 90%, using acetic anhydride as reagent and graphite bisulphate as an efficient catalyst.
Thermodynamics Of The Dissociation Of Chromium Soap Solutions In Benzene-Dimethyl Formamide, Hüseyi̇n Topallar, Yüksel Bayrak
Thermodynamics Of The Dissociation Of Chromium Soap Solutions In Benzene-Dimethyl Formamide, Hüseyi̇n Topallar, Yüksel Bayrak
Turkish Journal of Chemistry
Critical micelle concentrations and dissociation constants for chromium soaps (myristate, palmitate and stearate) in a mixture of benzene and dimethyl formamide (7:3, vol/vol) were determined by means of conductivity measurements. These soaps behave as simple moderate electrolytes in dilute solutions. Critical micelle concentrations and dissociation constants decreased with increasing numbers of carbon atoms in the soap molecules. Thermodynamic parameters such as heat of dissociation, \DeltaH_d, change in free energy, \DeltaG_d, and entropy, \DeltaS_d, per mole for the dissociation process were also evaluated.
The Effect Of Phosphate Ions (Po^{3-}_4) On The Corrosion Of Iron In Sulphat Solutions, Günay Kilinççeker, B. Yazici, M. Erbi̇l, H. Gali̇p
The Effect Of Phosphate Ions (Po^{3-}_4) On The Corrosion Of Iron In Sulphat Solutions, Günay Kilinççeker, B. Yazici, M. Erbi̇l, H. Gali̇p
Turkish Journal of Chemistry
The effect of phosphate ions on the corrosion of iron in sulphate solutions at different temperatures (293 K, 313 K, 333 K and 353 K) and at different pH (pH=2.1, 7.2 and 12.3) values was investigated. The electrochemical three-electrode technique was employed. The cathodic and anodic current-potential curves were obtained by strating from the corrosion potential measured against SCE and polarizing it first in cathodic and then in anodic direction. The results obtained indicate that at high pH (pH=7.2 and 12.3) SO^{2-}_{4}+PO^{3-}_{4}ions together reduce the corrosion rate of iron to a greater extent than SO^{2-}_{4} alone. At low pH (pH=2.1), …
The Role Of Electrolytically Co-Deposited Platinum-Palladium Electrodes On The Electrooxidation Of D. Glucose In Alkaline Medium: A Synergistic Effect, İpek Beceri̇k
Turkish Journal of Chemistry
The electrooxidation of D. glucose was investigated on platinum-palladium alloy electrodes of different compositions in alkaline aqueous solutions. The surface characteristics of the alloys in contact with electrolytic solution were studied using cyclic voltammetry. In particular, a surface enrichment in platinum due to a preferential dissolution of palladium was shown. Enhanced electrocatalytic activity at about 37 at. % in Pd was obtained when compared to pure metals, thus leading to a synergistic effect. The electrocatalytic activity of different alloys for D. glucose oxidation has been chacterized by exchange current densities obtained from extrapolation of Tafel lines to calculated equilibrium potential. …
Synthesis And Spectral Characterisation Of Novel Azo-Azomethine Dyes, Hati̇ce Karaer, İsmai̇l E. Gümrükçüoğlu
Synthesis And Spectral Characterisation Of Novel Azo-Azomethine Dyes, Hati̇ce Karaer, İsmai̇l E. Gümrükçüoğlu
Turkish Journal of Chemistry
The synthesis of novel azo-azomethine dye derivatives of substituted Schiff bases were carried out by the reaction of substituted 1-naphtylamine with 4-nitro and 2-chloro benzenediazonium tetraflouroborate salts as a coupling component. These compounds were identified by IR, UV-Vis and ^1H-NMR spectroscopic techniques, and elemental analysis.
Electrooxidation Of Linear Alkyl Benzene Sulfonate (Las) On Pt Electrodes, Bi̇rgül Yazici, Si̇bel Zor
Electrooxidation Of Linear Alkyl Benzene Sulfonate (Las) On Pt Electrodes, Bi̇rgül Yazici, Si̇bel Zor
Turkish Journal of Chemistry
The electrochemical behaviour of linear alklybenzene sulfonate (LAS) on Pt electrodes was investigated in 0.05M Na_2SO_4 and in 0.1M NaCl at pH=8 by the potentiokinetic method and by electrolysis. The anodic and cathodic semilogarithmic current-potential curves were obtained between -1.6V - +1.6V. The experimental discharge potentials were determined by means of current-potential-curves obtained by electrolysis between 0-3V. The percentages of surface active material remaining in the solution after specified periods (0-6hrs) were determined for different initial concentrations of LAS (30, 150, 300 ppm) by using a potentiostat at +1.6V and by applying a potential of 20V via a direct current …
The Application Of A Scanning Electron Microscope With An Energy Dispersive X-Ray Analyser (Sem/Edxa) For Gunshot Residue Determination On Hands For Some Cartridges Commonly Used In Turkey, Kezban Gökdemi̇r, Ertan Seven, Yüksel Sarikaya
The Application Of A Scanning Electron Microscope With An Energy Dispersive X-Ray Analyser (Sem/Edxa) For Gunshot Residue Determination On Hands For Some Cartridges Commonly Used In Turkey, Kezban Gökdemi̇r, Ertan Seven, Yüksel Sarikaya
Turkish Journal of Chemistry
The primers of the 10 commonly used cartridges in Turkey, MKE MP5, GECO Luger, FC Luger, WIN Luger, S&B Luger, WRA Luger, FNB Luger, P Luger, KF 80 Luger and SINTOX ACTION Luger were first examined with a SEM/EDXA. Then these cartridges used in test firings and the GSR on the hands of the test shooters was collected using adhesive-coated sample stubs and examined with a SEM/EDXA. Samples were scanned by viewing the BSE (Backscattered electron) image and, brighter and spherical particles were located, and then analysed with an EDXA. The elemental compositions of the GSR of the studied cartridges …
Nepetalactones And Other Constituents Of Nepeta Nuda Ssp. Albiflora, Gamze Kökdi̇l, Sabi̇ha M. Yalçin, Gülaçti Topçu
Nepetalactones And Other Constituents Of Nepeta Nuda Ssp. Albiflora, Gamze Kökdi̇l, Sabi̇ha M. Yalçin, Gülaçti Topçu
Turkish Journal of Chemistry
The hexane extract of Nepeta nuda ssp. albiflora led to the isolation of six known monoterpene nepetalactones, 4a\alpha,7\alpha,7a\alpha-nepetalactone (1), 4a\alpha,7\alpha,7a\beta-nepetalactone (2), 4a\beta,7\alpha,7a\beta-nepetalactone (3), 4a\beta,7\alpha,7a\alpha-nepetalactone (4), 4a\alpha,7\beta,7a\beta-nepetalactone (5), 3\alpha-hydroxy-4a\alpha,7\alpha,7a\alpha-dihydron\-epe\-tal\-actone (=nepetalic acid) (6) and a dimeric 5,9-dehydronepetalactone (7) along with two known steroids \beta-sitosterol and sitosterol 3-one and a triterpene betulinic acid. The acetone extract of the same plant afforded compound 7 in a higher yield in addition to compounds 2 and 6, and sesquiterpene caryophyllene oxide, the iridoid glucoside 1,5,9-epideoxyloganic acid, the triterpenoids oleanolic, ursolic and betulinic acids, and sitosterol 3\beta-glucoside.
Nonyl-And Dodecylamines Intercalated Bentonite And Illite From Turkey, Gülten Akçay, M. Kadi̇r Yurdakoç
Nonyl-And Dodecylamines Intercalated Bentonite And Illite From Turkey, Gülten Akçay, M. Kadi̇r Yurdakoç
Turkish Journal of Chemistry
Bentonite and illite were interacted with nonyl- and dodecylammonium salt solutions to see how the alkylammonium ions became attached and oriented within the interlamellar space of the clays. X-ray diffraction analyses were carried out to obtain information on the interlamellar organization and orientation of the adsorbed alkylammonium compounds. Thermogravimetric analysis (TG, DTG) and Fourier Transform Infrared Analyses (FTIR) were performed to characterize the samples and to determine the amounts adsorbed by the clay samples. The modification process was effective in nonyl- and dodecylammonium bentonites. Alkylammonium ions were adsorbed in the interlamellar space of the clays. Regarding the orientation of the …
Transition Metal Compound Mediated Reduction Of \Alpha-Amino Acids To 1,2-Amino Alcohols With Nabh_4 In Water, Ayhan S. Demi̇r, İdris M. Akhmedov, Özge Şeşenoğlu
Transition Metal Compound Mediated Reduction Of \Alpha-Amino Acids To 1,2-Amino Alcohols With Nabh_4 In Water, Ayhan S. Demi̇r, İdris M. Akhmedov, Özge Şeşenoğlu
Turkish Journal of Chemistry
A new efficient and cost-effective method for the preparation of 1,2-amino alcohols is described. The reactions of amino acids with NaBH_4 in the presence of NiCl_2 or MoO_3 in water give 1,2-amino alcohols in high yield. When optically pure amino acids were used, optically pure 1,2-amino alcohols were obtained.
Synthesis And Properties Of The Phthalocyanines Containing Eugenol (4-Allyl-2-Methoxyphenol), Erbi̇l Ağar, Selami̇ Şaşmaz, Ayşen Ağar
Synthesis And Properties Of The Phthalocyanines Containing Eugenol (4-Allyl-2-Methoxyphenol), Erbi̇l Ağar, Selami̇ Şaşmaz, Ayşen Ağar
Turkish Journal of Chemistry
New metal-free and metallophthalocyanines (M=Cu(II), Ni(II), Co(II), Zn(II) and Fe(II)) substituted with eugenol (4-allyl-2-methoxyphenol) from 1,2-dicyano-4-nitrobenzen are described. Cyclotetramerization of the substituted phthalonitrile leads to a product very soluble in common organic solvents. The characterization of the compounds was accomplished by elemental analysis, ^1H NMR, ^{13}C NMR, IR and UV-VIS spectral data.
Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Catechol Derivatives, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer
Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Catechol Derivatives, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer
Turkish Journal of Chemistry
The interactions of scandium(III) and yttrium(III) ions with catechol derivatives; catechol(H_2L, CAT), 4-nitrocatechol(H_2L, 4NCAT) and 2,3-dihydroxynaphthalene- 6-sulphonic acid(H_2L, DHN) were investigated in different metal ion:ligand mole ratios, by potentiometry and spectrophotometry. The stoichiometries of formed complexes have been defined by Job's method and formation curves have been drawn for some complexes, whenever possible. The stability contants of the fourteen formed complexes in definite stoichiometries have been determined, in an ionic medium of 0.1M KNO_3 or NaClO_4 at a temperature of 25°C. Noticeably, complexes of scandium(III) ion formed at much lower pH values than complexes of yttrium(III) ion, and its catechol …
Synthesis, Characterization And In Vitro Degradation Of Poly(Dl-Lactide)/Poly(Dl-Lactide-Co-Glycolide) Films, Menemşe Gümüşdereli̇oğlu, Günday Deni̇z
Synthesis, Characterization And In Vitro Degradation Of Poly(Dl-Lactide)/Poly(Dl-Lactide-Co-Glycolide) Films, Menemşe Gümüşdereli̇oğlu, Günday Deni̇z
Turkish Journal of Chemistry
Poly(dl-lactide) (PLA) homopolymers and poly(dl-lactide-co-glycolide) (PLGA) copolymers were synthesized from their cyclic dimers, i.e. dl-lactide and glycolide, by ring-opening polymerization in the presence of catalyst stannous octoate and chain control agent lauryl alcohol. The effects of catalyst and chain control agent concentrations, reaction temperature, and reaction time on the molecular weight and yield of homopolymers were studied. The homopolymers were obtained in the intrinsic viscosity 0.1 to 1.0 dl/g range by changing the polymerization conditions. The copolymers in two different lactide/glycolide ratios, i.e. 90:10 and 70:30 and in 0.60 intrinsic viscosity were synthesized. The polymers were further characterized by IR, …
A Study Of The Thermodynamic Properties Of Poly [2-(3-Mesityl-3-Methylcyclobutyl)-2-Hydroxyethyl Methacrylate] At Infinite Dilution Using Inverse Gas Chromatography-2-Hydroxyethyl, İsmet Kaya, Kadi̇r Demi̇relli̇
A Study Of The Thermodynamic Properties Of Poly [2-(3-Mesityl-3-Methylcyclobutyl)-2-Hydroxyethyl Methacrylate] At Infinite Dilution Using Inverse Gas Chromatography-2-Hydroxyethyl, İsmet Kaya, Kadi̇r Demi̇relli̇
Turkish Journal of Chemistry
Some thermodynamic quantities were obtained for the interactions of poly [2-(3-mesityl-3-methylcyclobutyl)-2-hydroxyethyl methacrylate] with alcohols, ketones, acetates, aromatics and alkanes by inverse gas chromatography in the temperature range 160-200°C. The specific retention volumes, V°_g, weight fraction activity coefficients of solute probes at infinite dilution, \Omega^{\infty}_1, Flory-Huggins thermodynamic interaction parameters, \chi^{\infty}_{12} between polymer and solvents were determined. The partial molar free energy, \Delta \bar{G}^{\infty}_{1}, the partial molar heat of mixing, \Delta\bar{H}^{\infty}_1 at infinite dilution and the solubility parameters of the polymer, \delta_2 were calculated.
Some Chemical Constituents From Marine Algae Of Karachi Coast (Arabian Sea), Muhammad Shaiq Ali, Viqar Uddin Ahmad, Farah Mahzar, Iqbal Azhar, Khan Usmanghani
Some Chemical Constituents From Marine Algae Of Karachi Coast (Arabian Sea), Muhammad Shaiq Ali, Viqar Uddin Ahmad, Farah Mahzar, Iqbal Azhar, Khan Usmanghani
Turkish Journal of Chemistry
Some commonly available marine algae have been collected from the Karachi coast of Arabian Sea for the search of new chemical constituents having biological importance. The structures of purified samples have been elucidated with the aid of modern spectroscopic techniques. Among the known constituents a new metabolite (1) has been isolated from the brown alga Iyengaria stellata.
Adsorption Of Copper And Cadmium Lons By Activated Carbon From Rice Hulls, Murat Teker, Mustafa İmamoğlu, Ömer Saltabaş
Adsorption Of Copper And Cadmium Lons By Activated Carbon From Rice Hulls, Murat Teker, Mustafa İmamoğlu, Ömer Saltabaş
Turkish Journal of Chemistry
The removal of copper (II) and cadmium (II) ions from aqueous solutions, by adsorption on activated carbon prepared from rice hulls (ACRH), was investigated depending on pH, activated carbon dosage, contact time, initial metal concentration and solution temperature. The optimum values of pH, ACRH dosage and contact time were determined to be 5-8, 0.5 g ACRH/25 mL solution an 60 minutes respctively for the adsorption of Cu (II) ions and 5-8, 1.5 g ACRH/25 mL solution and 60 minutes for the adsorption of Cd (II) ions. From the initial concentrations, the constants for the Freundlich and Langmuir isotherm were calculated …
Investigation Of Adsorption Isotherms Of Myristic, Palmitic And Stearic Acids On Rice Hull Ash, Hüseyi̇n Topallar, Yüksel Bayrak
Investigation Of Adsorption Isotherms Of Myristic, Palmitic And Stearic Acids On Rice Hull Ash, Hüseyi̇n Topallar, Yüksel Bayrak
Turkish Journal of Chemistry
The adsorption of myristic, palmitic and stearic acids on rice hull ash from isooctane as solvent was studied and conformed to a Langmuir isotherm. Monolayer coverage was determined to be 40.08, 38.43 and 37.27 mg/g, respectively. The free energy of adsorption, \Delta G°_{ads}, for the adsorption was determined to be -6,25, -6.32 and -6.39 kcal mol^{-1} for the adsorbates, respectively. The equilibrium parameter indicated that rice hull ash is a good adsorbent for myristic, palmitic and stearic acids examined.
Determination Of Activation Energy For The Number Average Degree Of Polymerization Using The Fluorescence Method, Önder Pekcan, Yaşar Yilmaz
Determination Of Activation Energy For The Number Average Degree Of Polymerization Using The Fluorescence Method, Önder Pekcan, Yaşar Yilmaz
Turkish Journal of Chemistry
A novel method based on steady state fluorescence measurements is introduced for measuring the activation energy of the number average degree of polymerization (NADP). Pyrene (Py) was used as a fluorescence probe for real time monitoring of free-radical polymerization (FRP) of methyl methacrylate (MMA). In situ FRP experiments were performed at various temperatures. Positive activation energy for NADP was measured and found to be 9.2 kcal/mol.
Contamination Of Roadside Soil, Plants, And Air With Heavy Metals In Jordan, A Comparative Study, Quasem M. Jaradat, Kamal A. Momani
Contamination Of Roadside Soil, Plants, And Air With Heavy Metals In Jordan, A Comparative Study, Quasem M. Jaradat, Kamal A. Momani
Turkish Journal of Chemistry
Copper, lead, cadmium, and zinc levels were analyzed by atomic absorption spectrophotometry in surface soil, plants, and air samples taken from both sides of the major highway connecting Amman with the southern parts of Jordan. Elevated levels of the studied elements were found in both soil and plants on the east side and on the west side of the road compared with the background values. The higher levels of heavy metals east of the road were due to the westerly prevailing wind at the sampling sites. The comtamination decreased exponentially with distance from the edge of the road and dropped …
Determination Of Patent Blue V And Carmoisine In Gelatine Desserts By Derivative Spectrophotometry, Yüksel Özdemi̇r, Ayşe Arzu Akkan
Determination Of Patent Blue V And Carmoisine In Gelatine Desserts By Derivative Spectrophotometry, Yüksel Özdemi̇r, Ayşe Arzu Akkan
Turkish Journal of Chemistry
A first-derivative spectrophotometric method was developed for quantitative determination of two synthetic organic dyes, Carmoisine and Patent Blue V, which are under governmental regulations all over the world because of their toxicity and carcinogenity. In this study, Carmoisine and Patent Blue V were simultaneously determined in their binary mixtures by first-derivative spectrophotometry. The method was applied to different gelatine desserts. The first-derivative derivative method did not eliminate turbid background in the samples. A simple background correction procedure involving a C_{18}-cartridge sample preparation step was developed for determination of dyes in gelatine dessert by first-derivative spectrophotometry. The C_{18}-cartridge sample preparation step …
Chlorination Of Two Turkish Lignites In Water And Water-Carbon Tetrachloride Media, Semra Karaca, Yücel Yaşar Kadioğlu, Sami̇h Bayrakçeken, M. Şahi̇n Gülaboğlu
Chlorination Of Two Turkish Lignites In Water And Water-Carbon Tetrachloride Media, Semra Karaca, Yücel Yaşar Kadioğlu, Sami̇h Bayrakçeken, M. Şahi̇n Gülaboğlu
Turkish Journal of Chemistry
The chlorine uptake of two Turkish lignites during chlorinolysis with chlorine gas in water and water-carbon tetrachloride media at ambient pressure (\cong 610 mmHg) was examined. The effects of speed of stirring (5-20s^{-1}), particle size (74-88, 150-180 and 250-425 \mu m), temperature (13-70°C) and chlorination time (0-18000 s) were studied. It is shown that the amount of chlorine uptake of both coals increased with decreasing particle size and increasing temperature.
Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Salicylic Acid, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer
Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Salicylic Acid, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer
Turkish Journal of Chemistry
The interactions of Sc(III) and Y(III) ions with salicyclic acid, SA (H_2L), were studied in aqueous solution by means of potentiometric and spectroscopic methods. The binding of SA occurs in Y(III):SA system, either in (1:1) or (1:2) mole ratios. The stability constants of the mono protonated complex, YHL^{2+}, and Y(HL)_2^+ type complex were calculated. The coordination of Sc(III) to SA was defined by means of Job's plot and its formation curve. The stability constants of ScL^+ and Sc(HL)L type complexes were determined by analysis of the potentiometric data; the coordination of SA to Sc(III) occurred through carboxylate and phenolic oxygens. …
Conformational Analysis Of Linear Peptide (Glu^1-Leu^2-Leu^3-Gly^4-Gly^5-Arg^6-Phe^7nh_2 ), Lütfü Demi̇r, Abdulhali̇k Karabulut, Gökhan Budak, Yusuf Şahi̇n, Nagif Sefteroğlu
Conformational Analysis Of Linear Peptide (Glu^1-Leu^2-Leu^3-Gly^4-Gly^5-Arg^6-Phe^7nh_2 ), Lütfü Demi̇r, Abdulhali̇k Karabulut, Gökhan Budak, Yusuf Şahi̇n, Nagif Sefteroğlu
Turkish Journal of Chemistry
Conformational energy-minimization of the Sea Anemone and Sea Pansy neuropeptide Pol-RFamide (Glu^1-Leu^2-Leu^3-Gly^4-Gly^5-Arg^6-Phe^7-NH_2) was carried out by molecular mechanics (MM). The linkage bonds were characterized by the torsion angles \theta, \psi and \omega and the side groups were characterized by the torsion angles \chi_1, \chi_2, \chi_3\ldots The energy-map for each monopeptide of the Pol-RFamide I was drawn in the range of -180° to 180° with increments of 20°. Conformation facilities for monopeptides were determined from these maps. These results were used in the analysis of the dipeptide (Glu^1-Leu^2). Then, the (Glu^1-Leu^2-Leu^3) tripeptide was examined using the calculated results for the dipeptide. …
^1h Nmr Spectra Of Some Amidrazone Derivatives, Şule Bahçeci̇, Haydar Yüksek, A. Aykut İki̇zler
^1h Nmr Spectra Of Some Amidrazone Derivatives, Şule Bahçeci̇, Haydar Yüksek, A. Aykut İki̇zler
Turkish Journal of Chemistry
Fifteen amidrazone derivatives (six being new compounds) were synthesized and their proton magnetic resonance spectra were recorded in trifluoroacetic acid (TFA). The protonation shifts, related to alkyl groups and observed on comparison of the spectra run in a neutral solvent and TFA, were attributed to an amidinium-type resonance of the resulting cations in the acidic medium.
Thin Layer Chromatographic Separation And Quantitation Of L-Dopa And L-Tyrosine In Mixtures, Gülendem Günendi̇, Farünni̇sa Pamuk
Thin Layer Chromatographic Separation And Quantitation Of L-Dopa And L-Tyrosine In Mixtures, Gülendem Günendi̇, Farünni̇sa Pamuk
Turkish Journal of Chemistry
A new TLC separation and quantitation method for L-tyrosine and L-Dopa mixtures was developed. The minimum tyrosine and Dopa quantities which can be measured by this technique are 0.7 and 1.5 \mu g respectively. The method may be used to measure the kinetic parameters of polyphenoloxidase as well as to trace the enzyme catalyzed conversion of L-tyrosine into L-Dopa. For a set of 20 measurements the maximum difference between any two measurements of spot areas was found to be 3 mm^2 (4.5\%) for L-Dopa (4 \mu g) and 2mm^2 (5.6\%) for L-tyrosine (1\mu g).