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 7021 - 7050 of 7459

Full-Text Articles in Entire DC Network

Kinetic Spectrophotometric Determination Of Nanogram Levels Of Manganese (Ii) By Azo Dye -- Potassium Periodate -- 1,10-Phenanthroline System, Konstantin L. Mutaftchiev Jan 2002

Kinetic Spectrophotometric Determination Of Nanogram Levels Of Manganese (Ii) By Azo Dye -- Potassium Periodate -- 1,10-Phenanthroline System, Konstantin L. Mutaftchiev

Turkish Journal of Chemistry

The catalytic effect of manganese (II) on the oxidation of 3 - Methyl - 6 - (2 - hydroxyethoxy) - 2 - [2 - methoxy - 4 - N (N,N - diethylamino) phenylazo] benzothiazolium methylsulphate (MHMDPBM), with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media was studied. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 560 nm. Under the optimum conditions (4x10^{- 5} mol dm^{- 3} MHMDPBM, 4x10^{- 4} mol dm^{- 3} potassium periodate, 1x10^{- 4} mol dm^{- 3} 1,10-phenanthroline, 0.1 mol dm^{- 3} buffer -- pH 3.0, 70^oC, …

Go to article

Electron Ionization Mass Spectrometric Studies Of Homalicine Tertraacetate, Dihydrohomalicine Tetraacetate And Related Compounds, Nasim Hasan Rama, Muhammad Tahir Hussain Jan 2002

Electron Ionization Mass Spectrometric Studies Of Homalicine Tertraacetate, Dihydrohomalicine Tetraacetate And Related Compounds, Nasim Hasan Rama, Muhammad Tahir Hussain

Turkish Journal of Chemistry

Electron Ionization mass spectra of homalicine tetraacetate (3), dihydrohomalicine tetraaetate (4) and related compounds (5,6) are described with the help of EIMS. The molecular formulae are further confirmed by HREIMS peak matching of molecular ion peaks exhibited by EIMS.

Go to article

Determination Of The Protonation Constants Of Some Substituted Salicylideneanilines By The Spectrophotometric Method In Ethanol-Water Mixtures, M. Abdülkadi̇r Akay, Esi̇n Canel, Esma Kiliç, Fi̇tnat Köseoğlu Jan 2002

Determination Of The Protonation Constants Of Some Substituted Salicylideneanilines By The Spectrophotometric Method In Ethanol-Water Mixtures, M. Abdülkadi̇r Akay, Esi̇n Canel, Esma Kiliç, Fi̇tnat Köseoğlu

Turkish Journal of Chemistry

Protonation constants of salicylideneaniline and methyl-, ethyl-, methoxy- fluoro-, chloro-, bromo- and iodo- substituted salicylideneanilines were determined by spectrophotomeric titrimetry in 10, 30, 50 and 70% ethanol-water mixtures at constant ionic strength and at 25^{o}C. The results obtained from this work were compared with those obtained using the potentimetric method. The difference between the results found with these two methods was approximately \pm $ 0.20 logK units. The spectrophotometric method was judged to be more suitable than the potentiometric method for halogen substituted salicylideneanilines with the low logK values and in the solvent mixture containing 10% ethanol, due to the …

Go to article

Automated Recognition Of Ergogenic Aids Using Soft Independent Modeling Of Class Analogy (Simca), M. Praisler, J. Van Bocxlaer, A. De Leenheer, D. L. Massart Jan 2002

Automated Recognition Of Ergogenic Aids Using Soft Independent Modeling Of Class Analogy (Simca), M. Praisler, J. Van Bocxlaer, A. De Leenheer, D. L. Massart

Turkish Journal of Chemistry

The introduction of effective drug testing procedures in doping control reduced, but did not eliminate, their abuse by athletes. The most important analytical challenge is the recognition of the new analog compounds. In attempts to circumvent existing controlled substance laws, slightly modified chemical structures (by adding or changing substituents at various positions on the banned molecules) are used. As a result, no substance belonging to a prohibited class may be used nowadays, even if it has not been specifically listed. We present a chemometric procedure acting as an automated GC-FTIR screening test detecting the molecular structural similarity of unknown compounds …

Go to article

Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan Jan 2002

Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan

Turkish Journal of Chemistry

The Raman spectra of cis- and trans-1,4- polybutadiene were recorded in the region 100-4000 cm^{-1} and its infrared spectra were also measured in the wave number range 200--4000 cm^{-1}. The spectra were completely analysed. Probable assignments to observed bands were made with the help of intensities and normal co-ordinate analysis. The calculated normal frequencies were in good agreement with the experimental ones.

Go to article

Tightness Of Slip-Linked Polymer Chains, Ralf Metzler, Andreas Hanke, Paul G. Dommersnes, Yacov Kantor, Mehran Kardar Jan 2002

Tightness Of Slip-Linked Polymer Chains, Ralf Metzler, Andreas Hanke, Paul G. Dommersnes, Yacov Kantor, Mehran Kardar

Physics & Astronomy Faculty Publications

We study the interplay between entropy and topological constraints for a polymer chain in which sliding rings (slip links) enforce pair contacts between monomers. These slip links divide a closed ring polymer into a number of subloops which can exchange length among each other. In the ideal chain limit, we find the joint probability density function for the sizes of segments within such a slip-linked polymer chain (paraknot). A particular segment is tight (small in size) or loose (of the order of the overall size of the paraknot) depending on both the number of slip links it incorporates and its …

Go to article

Group-Fitted Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors, Nicholas Dimakis, Grant Bunker Jan 2002

Group-Fitted Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors, Nicholas Dimakis, Grant Bunker

Physics & Astronomy Faculty Publications

X-ray absorption fine structure (XAFS) spectroscopy is one of the few direct probes of the structure of metalloprotein binding that is equally applicable to proteins in crystals, solutions, and membranes. Despite considerable progress in the calculation of the photoelectron scattering aspects of XAFS, calculation of the vibrational aspects has lagged because of the difficulty of the calculations. We report here initial results that express single- and multiple-scattering Debye-Waller factors as polynomial functions of first shell radial distance for metal-peptide complexes, enabling quantitatively accurate full multiple-scattering XAFS data analysis of active sites of unknown structure at arbitrary temperatures without the use …

Go to article

Correlation Functions Near Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar Jan 2002

Correlation Functions Near Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar

Physics & Astronomy Faculty Publications

In a system with long-ranged correlations, the behavior of correlation functions is sensitive to the presence of a boundary. We show that surface deformations strongly modify this behavior as compared to a flat surface. The modified near surface correlations can be measured by scattering probes. To determine these correlations, we develop a perturbative calculation in the deformations in height from a flat surface. Detailed results are given for a regularly patterned surface, as well as for a self-affinely rough surface with roughness exponent ζ. By combining this perturbative calculation in height deformations with the field-theoretic renormalization-group approach, we also estimate …

Go to article

Η Photoproduction On The Proton For Photon Energies From 0.75 To 1.95 Gev, M. Bektasoglu, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, S. Stepanyan, J. Yun, Et Al., Clas Collaboration Jan 2002

Η Photoproduction On The Proton For Photon Energies From 0.75 To 1.95 Gev, M. Bektasoglu, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, A. Klein, S. E. Kuhn, S. Stepanyan, J. Yun, Et Al., Clas Collaboration

Physics Faculty Publications

Differential cross sections for γp→ηp have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W = 1.75  GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass ∼1.8  GeV couples to the ηN channel.

Go to article

Effect Of Cr3+ And So42- On The Structure Of Rust Layer Formed On Steels By Atmospheric Corrosion, Masato Yamashita, Hitoshi Uchida,, Desmond C. Cook . Jan 2002

Effect Of Cr3+ And So42- On The Structure Of Rust Layer Formed On Steels By Atmospheric Corrosion, Masato Yamashita, Hitoshi Uchida,, Desmond C. Cook .

Physics Faculty Publications

The effect of chromium ion (Cr3+) and sulfate ion (SO42-) on the structure of the rust layer formed by thin electrolyte-film corrosion of low-alloy steels has been examined. By using X-ray diffraction spectroscopy, it was found that coexistence of Cr3+ and SO42- in the electrolyte film covering the steel surface quickly forms the Cr-goethite (α-(Fe 1-X, CrX)OOH) layer which has been known as the final protective rust layer. Scanning vibrating electrode measurements showed that the rust layer formed under the electrolyte film containing Cr3+ and SO42- …

Go to article

Cover And Contents Jan 2002

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

Go to article

Synthesis And Characterization Of Some 3-Alkyl-4-Amino-5-Cyanomethyl-4h-1,2,4-Triazoles, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Kemal Sancak Jan 2002

Synthesis And Characterization Of Some 3-Alkyl-4-Amino-5-Cyanomethyl-4h-1,2,4-Triazoles, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Kemal Sancak

Turkish Journal of Chemistry

The preparation and characterization of some 3-alkyl-4-amino-5-cyanomethyl-4H-1,2,4-triazoles with active methylene groups are described and their structural properties using NMR and IR spectra and elemental analyses are given.

Go to article

Bifunctional Allyl-Sulphonium Salt As A Novel Addition--Fragmentation Agent For Photoinitiated Cationic Polymerization, Utku Küçüktömbeki̇ci̇, Mustafa Deği̇rmenci̇, Yusuf Yağci Jan 2002

Bifunctional Allyl-Sulphonium Salt As A Novel Addition--Fragmentation Agent For Photoinitiated Cationic Polymerization, Utku Küçüktömbeki̇ci̇, Mustafa Deği̇rmenci̇, Yusuf Yağci

Turkish Journal of Chemistry

Bifunctional allyl tetrahydrothiophenium hexafluoroantimonate was synthesized via a one-pot reaction of 3-chloro-2-chloromethylpropene with thiophene in the presence of sodium hexafluoroantimonate. The initiation capability of this salt, in conjunction with a photochemical free radical source such as 2,2-dimethoxy-2-phenyl acetophenone and benzophenone, via an addition-fragmentation mechanism in the cationic polymerization of cyclohexene oxide and butyl vinyl ether is investigated.

Go to article

Radio Frequency-Induced Plasma Polymerization Of Allyl Alcohol And 1-Propanol, Şennur Candan Jan 2002

Radio Frequency-Induced Plasma Polymerization Of Allyl Alcohol And 1-Propanol, Şennur Candan

Turkish Journal of Chemistry

The effect of the composite parameters' plasma power (P)-to-monomer flow rate (\phi) ratio (P/\phi) in the plasma polymerization of allyl alcohol and 1-propanol was studied. The radio-frequency plasmas of deposits operated at low power (1-15 W) were investigated using deposition rate measurements. Detailed chemical information on the plasma polymers was obtained by X-ray photoelectron spectroscopy (XPS). The study of the surface chemistry of films created from allyl alcohol and 1-propanol demonstrates the importance of the double bond for good \underline{C}-O group retention. The deposition rates of both plasma polymers were found to increase with increasing P. The comparison of the …

Go to article

Conformational Analysis Of Pol-Rfamide Ii (Glu}^{1}-Trp^{2}-Leu^{3}-Lys^{4}-Gly^{5}-Arg^{6}-Phe^{7}-Nh_{2}) Heptapeptide, Lütfü Demi̇r, Niftali Mihrali Godjaev Jan 2002

Conformational Analysis Of Pol-Rfamide Ii (Glu}^{1}-Trp^{2}-Leu^{3}-Lys^{4}-Gly^{5}-Arg^{6}-Phe^{7}-Nh_{2}) Heptapeptide, Lütfü Demi̇r, Niftali Mihrali Godjaev

Turkish Journal of Chemistry

The geometrical structure of the sea anemone and sea pansies neuropeptide Pol-RFamide II Glu^{1}-Trp^{2}-Leu^{3}-Lys^{4}-Gly^{5}-Arg^{6}-Phe^{7}-NH_{2} was carried out by molecular mechanics (MM). The linkage bonds are characterised by the torsional angles \phi, \psi and \omega and the side groups characterised by the torsional angles \chi_{1}, \chi_{2}, \chi_{3},... subsequently. The energy-map for each monopeptide of the Pol-RFamide II was drawn in the range of -180° to 180° with increments of 20°. Conformation facilities for monopeptides were decided from these maps. These results were used in the analysis of the dipeptide Glu^{1}-Trp^{2}. Then, the Glu^{1}-Trp^{2}-Leu^{3} tripeptide was examined by using the calculated results …

Go to article

Acid-Base Equilibria Of Some N-Substituted Thiophene-2-Carboxamidoximes In Non-Aqueous Media, Nedi̇me Dürüst, Yaşar Dürüst, İlknur Meri̇ç Jan 2002

Acid-Base Equilibria Of Some N-Substituted Thiophene-2-Carboxamidoximes In Non-Aqueous Media, Nedi̇me Dürüst, Yaşar Dürüst, İlknur Meri̇ç

Turkish Journal of Chemistry

The protonation constants of the amino nitrogens of some N-substituted thiophene-2-carboxamidoximes have been determined in acetic acid by means of potentiometric titration with perchloric acid. pK_{a} values of the title compounds were interpreted on the basis of structural effects due to the substituents and the main skeleton.

Go to article

Trace Element Accumulation In Selected Bioindicators Exposed To Emissions Along The Industrial Facilities Of Danube Lowland, Heide Spiegel Jan 2002

Trace Element Accumulation In Selected Bioindicators Exposed To Emissions Along The Industrial Facilities Of Danube Lowland, Heide Spiegel

Turkish Journal of Chemistry

The scope of this study was to investigate the effects of the atmospheric emissions of two significant industrial centres of the Danube Lowland: the Schwechat and Slovnaft refineries. In this connection the environmental pollution of emission zones by heavy metals on the base of selected bioindicators (soil, lucerne, wheat, earthworms) should be evaluated. The phenomenon of the atmospheric impact of heavy metal aerosols on the food chain and substance transfer for the model studied (soil - plants - terrestrial invertebrates) was quantified by transfer (bioaccumulation) factors. Due to the orographic depression between the Eastern Alps and Western Carpathian Mountains and …

Go to article

Synthesis Of 1,4-Diazepine Nucleosides, M. Zia-Ul-Haq, Shahid Hameed, Helmut Duddeck, Roshan Ahmed Jan 2002

Synthesis Of 1,4-Diazepine Nucleosides, M. Zia-Ul-Haq, Shahid Hameed, Helmut Duddeck, Roshan Ahmed

Turkish Journal of Chemistry

The phenolic \beta-diketones I prepared by modified Baker-Venkataraman rearrangement were converted to the flavones II in acidic medium which on treatment with aqueous ethylenediamine/propylenediamine gave diazepine derivatives III. After coupling with acetobromo sugars in the presence of mercuric cyanide and nitromethane, deacetylation in methanolic ammonia yielded nucleosides V. The structures of all the intermediates and final products were confirmed with the help of modern spectroscopic techniques.

Go to article

Dna Biosensor For Microcystis Spp. Sequence Detection By Using Methylene Blue And Ruthenium Complex As Electrochemical Hybridization Labels, Arzum Erdem, Kagan Kerman, Burcu Meri̇ç, Di̇lşat Özkan, Pinar Kara, Mehmet Özsöz Jan 2002

Dna Biosensor For Microcystis Spp. Sequence Detection By Using Methylene Blue And Ruthenium Complex As Electrochemical Hybridization Labels, Arzum Erdem, Kagan Kerman, Burcu Meri̇ç, Di̇lşat Özkan, Pinar Kara, Mehmet Özsöz

Turkish Journal of Chemistry

An electrochemical biosensor for the voltammetric detection of DNA sequences related to the bloom-forming genera of cyanobacteria, Microcystis spp., is described. A specific DNA ``probe'' is designed based on sequence polymorphism within the 16S ribosomal DNA (rDNA) of the Microcystis spp. These single-stranded probes were immobilized onto carbon paste electrode (CPE) with the adsorption at a controlled potential. The probes were hybridized with the complementary ``target'' sequences at the electrode. The formed hybrids on the electrode surface were evaluated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV) using methylene blue (MB) and tris (2,2' -- bipyridine) ruthenium (II) chloride …

Go to article

Spectrophotometric Determination Of Mexiletine Hydrochloride In Capsules Using Bromothymol Blue, Zeynep Aydoğmuş, S. Müge Çeti̇n, Sedat Tosunoğlu Jan 2002

Spectrophotometric Determination Of Mexiletine Hydrochloride In Capsules Using Bromothymol Blue, Zeynep Aydoğmuş, S. Müge Çeti̇n, Sedat Tosunoğlu

Turkish Journal of Chemistry

A new spectrophotometric method based on the formation of an ion-pair using bromothymol blue as ion-pair complexing reagent was developed for the determination of mexiletine hydrochloride in capsules. The ion-pair formed was highly coloured and easily extracted with dichloromethane. The calibration curve was linear over the concentration range 1.08--10.8 \mu g.ml^{-1} at \lambda_{max} = 408 nm (r = 0.9999). The results obtained from the developed method were compared statistically with those obtained by the British Pharmacopeia method.

Go to article

Anodic Behavior Of Tungsten In H_{3}Po_{4}-K_{2}So_{4}-H_{2}So_{4}/Koh Solutions, Mustafa Anik Jan 2002

Anodic Behavior Of Tungsten In H_{3}Po_{4}-K_{2}So_{4}-H_{2}So_{4}/Koh Solutions, Mustafa Anik

Turkish Journal of Chemistry

Potentiodynamic and potentiostatic polarizations were used to study the effect of pH on the anodic reaction characteristics of tungsten (W) in a very broad pH range (0.4-13). The open circuit potential was observed to decrease with a constant slope of 58 mV/pH, as pH increased. The oxide phase of W showed typical amphoteric surface behavior in the acidic regime. The oxide dissolution went through a minimum at pH 2.5, which was identified as the point of zero charge (pzc) of W--oxide. The oxide dissolution below the pzc was H^{+} -assisted and above the pzc was OH^{-}-assisted. At around the pzc …

Go to article

The Protonation Constants Of Some Aliphatic Alkylamines In Ethanol-Water Mixtures, Esma Kiliç, Gülteki̇n Gökçe, Esi̇n Canel Jan 2002

The Protonation Constants Of Some Aliphatic Alkylamines In Ethanol-Water Mixtures, Esma Kiliç, Gülteki̇n Gökçe, Esi̇n Canel

Turkish Journal of Chemistry

Protonation constants of methyl-, ethyl-, propyl- and butylamines Were determined potentiometrically using an electrode system calibrated in concentration units of hydrogen ion in ethanol-water mixtures (10\% -80\% ethanol, v/v) at an ionic strength of 0.1 and at 25°C. The trend in the values of protonation constants of these aliphatic amines was explained in terms of the number of alkyl groups and solvent composition. The basicity orders were found to be NH_{3} < R_{3}N < RNH_{2} < R_{2}NH (R:-CH_{3}, -C_{2}H_{5}, -n-C_{3}H_{7} and --n-C_{4}H_{9}) in all the solvent mixtures studied.

Go to article

Poly(Methacrylic) Acid And \Gamma-Methacryloxypropyltrimethoxy Silane/Clay Nanocomposites Prepared By In-Situ Polymerization, Ahmet Gültek, Turgay Seçki̇n, Yunus Önal, M. Gali̇p İçduygu Jan 2002

Poly(Methacrylic) Acid And \Gamma-Methacryloxypropyltrimethoxy Silane/Clay Nanocomposites Prepared By In-Situ Polymerization, Ahmet Gültek, Turgay Seçki̇n, Yunus Önal, M. Gali̇p İçduygu

Turkish Journal of Chemistry

Poly(methacrylic acid) and poly(acrylic acid) nanocomposites were prepared by in-situ polymerization of \gamma-methacryloxypropyltrimethoxysilane (A174)/clay nanocomposites in which the macromonomer was generated by grafting A-174 onto activated clay samples via hydroxyl groups or via intercalation. In- situ polymerization was carried out in the presence of an initiator. It was found that the structural affinity between the methacrylic or acrylic acid monomers and the amount of clay played an important role in the hybrid structure. The nanocomposites were quantified by both X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), and differential thermal analysis (DTA).

Go to article

Swelling Of Superabsorbent Acrylamide/Sodium Acrylate Hydrogels Prepared Using Multifunctional Crosslinkers, Erdener Karadağ, Dursun Saraydin Jan 2002

Swelling Of Superabsorbent Acrylamide/Sodium Acrylate Hydrogels Prepared Using Multifunctional Crosslinkers, Erdener Karadağ, Dursun Saraydin

Turkish Journal of Chemistry

Superwaterabsorbent acrylamide-sodium acrylate hydrogels were Prepared by free radical polymerization in aqueous solutions of acrylamide and of acrylamide with sodium acrylate as comonomer. For each copolymerization, nine different compositions were used and in all systems a concentration of a multifunctional crosslinker such as trimethylolpropane triacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate and N,N'-methylenebisacrylamide was employed. As a result of dynamic swelling tests, the influence of crosslinkers and the relative content of sodium acrylate on the swelling properties, the initial swelling rate and the swelling rate constant, swelling exponent, swelling coefficients and diffusional behaviour of water in the hydrogel systems were examined. …

Go to article

New Triterpenic Saponins From Cephalaria Transsylvanica, Süheyla Kirmizigül, Hüseyi̇n Anil Jan 2002

New Triterpenic Saponins From Cephalaria Transsylvanica, Süheyla Kirmizigül, Hüseyi̇n Anil

Turkish Journal of Chemistry

Three new triterpenic saponins, 3-O-[\beta-D-xylopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin 28-O-[\beta-D-glucopy\-ranosyl (1 \to 4)-\beta-D-glucopyranosyl] ester (1), 3-O-[\beta-D-glucopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin 28-O-[\beta -D-glucopyranosyl] ester (2) and 3-O-[\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin(3) were isolated from Cephalaria transsylvanica. After cleavage of the ester-glycosidic linkage of the bisdesmosidic compounds, two new prosapogenins, 3-O-[\beta-D-xylopyranosyl (1 \to 4)-\beta-D-glucpyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin (4) and 3-O-[\beta-D-glucopyranosyl (1 \to 4)- \beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin (5) were also isolated. The structures …

Go to article

Modeling Of Taqi Endonuclease Purification By Hplc, Mehmet Düzenli̇, Kutlu Ö. Ülgen Jan 2002

Modeling Of Taqi Endonuclease Purification By Hplc, Mehmet Düzenli̇, Kutlu Ö. Ülgen

Turkish Journal of Chemistry

The present work is based on the previously reported purification study of TaqI endonuclease^{5} and aimed to simulate the experimentally obtained chromatograms in order to reduce the time and cost in the design, optimization and scaling up of purification processes. Three different models depending on equilibrium, rate and plate theories are used in the mathematical description of experimental elution profiles and the solutions of the model equations are compared. The equilibrium-dispersive theory provides excellent results in predicting the experimental chromatograms. It is thus recognized that band dispersion takes place in the column through axial dispersion and nonequilibrium effects. The user-friendly …

Go to article

Synthesis And Spectral Characterization Of Unsymmetric Organotin(Iv) Derivatives, Sadiq-Ur Rehman, Saqib Ali, Moazzam H. Ghatti, Khadija Shahid, M. Mazhar, M. Kaleem, Amin Badshah Jan 2002

Synthesis And Spectral Characterization Of Unsymmetric Organotin(Iv) Derivatives, Sadiq-Ur Rehman, Saqib Ali, Moazzam H. Ghatti, Khadija Shahid, M. Mazhar, M. Kaleem, Amin Badshah

Turkish Journal of Chemistry

Unsymmetric Organotin(IV) compounds of general formula R_{4-n}SnR^\prime_{n} have been synthesized by the reaction of corresponding organotin(IV) chlorides with n-hexyl magnesium bromide prepared in dry ether in situ, where R = CH_{3}, n-C_{4}H_{9}, C_{6}H_{5}, C_{6}H_{5}CH_{2} and R^\prime = n-C_{6}H_{13}. The reactions were carried out in dry toluene, refluxed for 6 h and the final products were purified through vacuum distillation. These compounds were characterized by multinuclear NMR (^{1}H, ^{13}C, ^{119}Sn), IR spectroscopy and mass spectrometry to predict their structures. All spectroscopic results support the four-coordination and tetrahedral geometry of the compounds.

Go to article

Bromination Of Benzonorbornadiene Using A Mixture Of Sodium Bromide And Sodium Perborate At High Temperatures, Erdal Şenocak, Yavuz Taşkesenli̇gi̇l, Ferhan Tümer Jan 2002

Bromination Of Benzonorbornadiene Using A Mixture Of Sodium Bromide And Sodium Perborate At High Temperatures, Erdal Şenocak, Yavuz Taşkesenli̇gi̇l, Ferhan Tümer

Turkish Journal of Chemistry

Bromination of benzonorbornadiene (1) with sodium bromide in the presence of sodium perborate at room temperature gave only one product, the dibromide 2 produced via Wagner-Meerwein rearrangement. However, at high temperatures, bromination resulted predominantly in the formation of rearranged solvolytic products whose formation mechanisms are discussed.

Go to article

Pyridine And Benzene Templated Potential Peptidomimetics, Kadi̇r Dabak Jan 2002

Pyridine And Benzene Templated Potential Peptidomimetics, Kadi̇r Dabak

Turkish Journal of Chemistry

This study provides a new approach for the synthesis of pyridine and benzene templated potential peptidomimetics. By the attachment of various amino acid side chains in different combinations on the pyridine template at the 2- and 3- positions and on the benzene core at 1,2,4 positions, different peptidomimetics may be obtained. Arg-10, Leu-11 and Tyr-13 amino acid side chain mimics and their precursors were attached to the pyridine and benzene core with a special arrangement to produce potential peptidomimetics of omega-conotoxin MVIIA.

Go to article

Cover And Contents Jan 2002

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

Go to article

First Prev Next Last