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Articles 7411 - 7440 of 10319
Full-Text Articles in Physical Sciences and Mathematics
Blending Rudists With Technology; Non-Destructive Examination Of The Internal And External Structures Of Rudists Using High Quality Scanning And Digital Imagery, Ann Molineux, Robert W. Scott, Jessie Maisano, Richard Ketcham, Louis Zachos
Blending Rudists With Technology; Non-Destructive Examination Of The Internal And External Structures Of Rudists Using High Quality Scanning And Digital Imagery, Ann Molineux, Robert W. Scott, Jessie Maisano, Richard Ketcham, Louis Zachos
Turkish Journal of Earth Sciences
Certain formations within the Cretaceous of Texas include zones of silicified rudists. Such diagenetic alteration, combined with the timing of alteration, has preserved many structural features of the rudist suitable for computed tomography (CT scanning). The excellent density differences between those skeletal structures (silica) and the internal sediment (calcitic mud) or later crystallization (calcite), fulfill a fundamental requirement for such analysis. The Jackson School of Geosciences at The University of Texas provides access to a high resolution computed tomography scanning system. This equipment, not identical to medical scanners, provides higher resolution and sophisticated software to analyze the imagery. Several rudist …
Surface And Subsurface Characteristics Of The Çankırı Basin (Central Anatolia, Turkey): Integration Of Remote Sensing, Seismic Interpretation And Gravity, Nuretdi̇n Kaymakçi, Şenol Özmutlu, Paul M. Van Van Dijk, Yakup Özçeli̇k
Surface And Subsurface Characteristics Of The Çankırı Basin (Central Anatolia, Turkey): Integration Of Remote Sensing, Seismic Interpretation And Gravity, Nuretdi̇n Kaymakçi, Şenol Özmutlu, Paul M. Van Van Dijk, Yakup Özçeli̇k
Turkish Journal of Earth Sciences
The geology of the Çankırı Basin has been studied using multi-source data including satellite images, aerial photos, gravimetric data and seismic sections, which are subsequently used to generate maps and a 3D model of that part of the basin covered by the seismic sections. From the compilation, three different phases of deformation are recognized. The earliest phase is characterized by thrusting during the Early Tertiary. The second deformation phase is characterized by extensional deformation associated with normal faulting in the latest Early Miocene to Middle Miocene. The third, and the last, phase is characterized by compressional deformation manifested by inversion …
Volcanic Rocks From Foça-Karaburun And Ayvalik-Lesvos Grabens (Western Anatolia) And Their Petrogenetic-Geodynamic Significance, Samuele Agostini, Murat Tokçaer, Mehmet Yilmaz Savaşçin
Volcanic Rocks From Foça-Karaburun And Ayvalik-Lesvos Grabens (Western Anatolia) And Their Petrogenetic-Geodynamic Significance, Samuele Agostini, Murat Tokçaer, Mehmet Yilmaz Savaşçin
Turkish Journal of Earth Sciences
The Foça-Karaburun and Ayvalık-Lesvos grabens (western coast of Anatolia, Turkey) are two important NW-SE-trending extensional areas generated in response to the Early Miocene-Holocene extension of the Western Anatolian region, related to the opening of the "unconventional" back-arc basin of the Aegean Sea. The abundance of geo-structural evidence and the occurrence of volcanic rocks representing all the stages of the Aegean-Western Anatolia volcanism render the Foça-Karaburun and Ayvalık-Lesvos Grabens key localities to exemplify the petrogenetic and geodynamic evolution of the area. In this context, the Foça-Karaburun and Ayvalık-Lesvos grabens, possibly formerly a single graben, formed along an original NE-SW-trending extension, later …
Statistical Evaluation Of Bivariate, Ternary And Discriminant Function Tectonomagmatic Discrimination Diagrams, Surendra P. Verma
Statistical Evaluation Of Bivariate, Ternary And Discriminant Function Tectonomagmatic Discrimination Diagrams, Surendra P. Verma
Turkish Journal of Earth Sciences
This work applies a statistical methodology involving the calculation of success rates to evaluate a total of 28 tectonomagmatic discrimination diagrams: four bivariate (Ti/Y-Zr/Y; Zr-Zr/Y; Ti/1000-V; and Nb/Y-Ti/Y); six ternary (Zr-3Y-Ti/1000; MgO-Al2O3-FeOt, Th-Ta-Hf/3; 10MnO-15P2O5-TiO2; Zr/4-Y-2Nb; and La/10-Nb/8-Y/15); and three old (Score1-Score2; F1-F2; and F2-F3) and three sets of new discriminant function diagrams (each set consisting of five DF1-DF2 type diagrams proposed during 2004-2008). I established and used extensive geochemical databases of Miocene to Recent fresh rocks from island arcs, back arcs, continental rifts, ocean-islands, and mid-ocean ridges. Rock and magma types were inferred from a SINCLAS computer program. Although some …
Sensitivity Analysis On Relations Between Earthquake Source Rupture Parameters And Far-Field Tsunami Waves: Case Studies In The Eastern Mediterranean Region, Seda Yolsal, Tuncay Taymaz
Sensitivity Analysis On Relations Between Earthquake Source Rupture Parameters And Far-Field Tsunami Waves: Case Studies In The Eastern Mediterranean Region, Seda Yolsal, Tuncay Taymaz
Turkish Journal of Earth Sciences
We present several sensitivity tests, that were applied to exhibit the effects of earthquake source rupture characteristics on amplitudes, frequency contents and arrival times of earthquake generated tsunami waves in the far field, as case studies in the eastern Mediterranean. The investigated earthquake parameters are principally epicentral location, focal mechanism parameters (strike, dip and rake angles), faulting area dimensions, maximum displacement and focal (centroid) depth. We have implemented a numerical method of TUNAMI-N2 based on non-linear shallow-water theory to obtain synthetic water surface fluctuations at selected pseudo tide gauge locations in the eastern Mediterranean. It has been observed that the …
Thermal Evolution Of The Permo−Triassic Karakaya Subduction-Accretion Complex Between The Biga Peninsula And The Tokat Massif (Anatolia), Ilaria Federici, William Cavazza, Aral Okay, Olivier Beyssac, Massimiliano Zattin, Sveva Corrado, Francesco Dellisanti
Thermal Evolution Of The Permo−Triassic Karakaya Subduction-Accretion Complex Between The Biga Peninsula And The Tokat Massif (Anatolia), Ilaria Federici, William Cavazza, Aral Okay, Olivier Beyssac, Massimiliano Zattin, Sveva Corrado, Francesco Dellisanti
Turkish Journal of Earth Sciences
The results of the combined application of a series of analytical methods (clay mineralogy, vitrinite reflectance, Raman microspectroscopy) placed tight constraints on the thermal evolution of the Karakaya Complex of northern Anatolia, a mostly Permo-Triassic subduction-accretion complex resulting from the progressive closure of the Palaeotethys. The thermal evolution of the Karakaya Complex is the result of Permian-Triassic subduction-accretion processes, and was not significantly affected by later Alpine-age tectonism, as shown by Liassic shallow-water siliciclastic and carbonate deposits overlying unconformably the Karakaya Complex which did not undergo any significant burial. The Lower Karakaya Complex, comprising metabasite and subordinate marble and phyllite, …
Late Campanian Rudist Assemblages And Biometrical Analysis Of Pseudopolyconites From Bačevica (Eastern Serbia), Tunis Giorgio, Tarlao Alceo, Radoicic Rajka
Late Campanian Rudist Assemblages And Biometrical Analysis Of Pseudopolyconites From Bačevica (Eastern Serbia), Tunis Giorgio, Tarlao Alceo, Radoicic Rajka
Turkish Journal of Earth Sciences
The lithological and faunal succession cropping out close to the famous palaeontological locality of Bacevica (Eastern Serbia) is described along a very discontinuous and ill-exposed section. Since the section is dominated by clastic sediments, no-vestige of the so-called 'Vrbovac reef' has been observed. Rhythms consisting of a limestone breccia lower unit and a fossil-rich upper part characterize the base of the section while rare silt and sand-rich limestone breccias and prevailing silty/sandy soils are the lithologies observed in the upper part of the same. The faunal succession shows an alternation of monospecific-paucispecific assemblages and much more diverse assemblages of rudists. …
The Morphology And Function Of The Upper Valve Of Vaccinites Vesiculosus (Woodward), Dietrich Schumann
The Morphology And Function Of The Upper Valve Of Vaccinites Vesiculosus (Woodward), Dietrich Schumann
Turkish Journal of Earth Sciences
The evolutionary transformation of the upper valve (UV) to a probable particle filter system in some hippuritid genera belongs to the most drastic changes in pelycipod shell structures. The basic architecture of this product is well known since long times. Again discussed is the functional role of the canal system. The bottom of the canals is very smooth. The canal system of Vaccinites vesiculosus is completely roofed by a particular graceful sieve. A water exchange between the canals did not exist. The uppermost part of the upper valve (the sieve) most probably was an endoskeleton. The upper valve was not …
Chemical Bath Deposition And Characterization Of Cu_2o-Cu_Xs Thin Films, D. D. O. Eya
Chemical Bath Deposition And Characterization Of Cu_2o-Cu_Xs Thin Films, D. D. O. Eya
Turkish Journal of Physics
Cu_2O-Cu_xS thin films have been deposited on glass substrate by chemical bath deposition technique. The films were obtained by depositing Copper Sulphide (Cu_xS) on Copper (I) Oxide (Cu_2O) and then Cu_2O on Cu_xS. The peak solar transmittance across the thin films were found to be
Determination Of Ceftriaxone, Ceftizoxime, Paracetamol, And Diclofenac Sodium By Capillary Zone Electrophoresis In Pharmaceutical Formulations And In Human Blood Serum, Amber Solangi, Saima Memon, Arfana Mallah, Najma Memon, Muhammad Yar Khuhawar, Muhammad Iqbal Bhanger
Determination Of Ceftriaxone, Ceftizoxime, Paracetamol, And Diclofenac Sodium By Capillary Zone Electrophoresis In Pharmaceutical Formulations And In Human Blood Serum, Amber Solangi, Saima Memon, Arfana Mallah, Najma Memon, Muhammad Yar Khuhawar, Muhammad Iqbal Bhanger
Turkish Journal of Chemistry
A simple and fairly fast capillary zone electrophoresis method has been developed for the determination and separation of ceftriaxone, ceftizoxime, paracetamol, and diclofenac sodium in a mixture, in pharmaceutical formulations, and in blood serum. A 50 mM sodium tetraborate background electrolyte solution (pH 9.0) was found to be suitable for separation of all the drugs. An uncoated fused-silica capillary of a total length of 57 cm (effective length 50 cm) was used for separation. All the analytes were completely separated within 8.0 min at an applied voltage of 30 kV and detection was performed at 214 nm .Validation of the …
Biotransformation Of Danazol By Fusarium Solani And Gibberella Fujikuorii, And Prolyl Endopeptidase Inhibition Studies Of Transformed Products, Azizuddin Shaikh, Muhammad Iqbal Choudhary
Biotransformation Of Danazol By Fusarium Solani And Gibberella Fujikuorii, And Prolyl Endopeptidase Inhibition Studies Of Transformed Products, Azizuddin Shaikh, Muhammad Iqbal Choudhary
Turkish Journal of Chemistry
Biotransformation of danazol (17\beta-hydroxy-17\alpha-pregna-2,4-dien-20-yno-[2,3-d] isoxazole) (1) on fermentation with Fusarium solani yielded 17\beta-hydroxy-2-(hydroxymethyl)-17\alpha -pregn-4-en-20-yn-3-one (2) and 17\beta -hydroxy-2-(hydroxymethyl)-17\alpha-pregna-1,4-dien-20-yn-3-one (3), while the fermentation of 1 with Gibberella fujikuorii yielded compound 2 only. The structures of these compounds were deduced on the basis of modern spectroscopic techniques. Prolyl endopeptidase inhibition activities of danazol (1) and its transformed products 2 and 3 are also studied.
A Model Based Nonlinear Adaptive Controller For The Passive Bilateral Telerobotic System, Ufuk Özbay, Erkan Zergeroğlu, İlyas Kandemi̇r
A Model Based Nonlinear Adaptive Controller For The Passive Bilateral Telerobotic System, Ufuk Özbay, Erkan Zergeroğlu, İlyas Kandemi̇r
Turkish Journal of Electrical Engineering and Computer Sciences
IIn this paper, we propose a new adaptive controller scheme for the bilateral telerobotic/teleoperation systems. The proposed controller achieves asymptotic tracking despite the parametric uncertainties associated with both master and slave robots while ensuring the passivity of the closed loop system. Extensive simulation studies are presented to illustrate the feasibility and efficiency of the proposed adaptive controller.
Stratigraphy And Larger Foraminifera Of The Eocene Shallow-Marine And Olistostromal Units Of The Southern Part Of The Thrace Basin, Nw Turkey, Ercan Özcan, György Less, Aral İ. Okay, Mária Báldi-Beke, Katalin Kollányi, İsmai̇l Ömer Yilmaz
Stratigraphy And Larger Foraminifera Of The Eocene Shallow-Marine And Olistostromal Units Of The Southern Part Of The Thrace Basin, Nw Turkey, Ercan Özcan, György Less, Aral İ. Okay, Mária Báldi-Beke, Katalin Kollányi, İsmai̇l Ömer Yilmaz
Turkish Journal of Earth Sciences
The Eocene marine sequence in the southern part of the Thrace Basin (NW Turkey) involves a variety of platform and deep-marine olistostromal units, the stratigraphy of which have been vigorously debated in the past. A detailed analysis of larger foraminifera in these either foraminifera or foraminifera-coral-coralline algae-dominated platform and associated comparatively deeper-marine units permits us to establish a high-resolution biostratigraphy in the context of shallow benthic zonation (with SBZ zones) of Tethyan Paleogene. The oldest zone (SBZ 5, corresponding to the basal Ypresian) was observed only in olistoliths. An old erosional remnant of a transgressive shallow-marine to basinal sequence (Dişbudak …
Statistical Evaluation Of Classification Diagrams For Altered Igneous Rocks, Surendra P. Verma, Rodolfo Rodriguez Rios, Rosalinda González-Ramírez
Statistical Evaluation Of Classification Diagrams For Altered Igneous Rocks, Surendra P. Verma, Rodolfo Rodriguez Rios, Rosalinda González-Ramírez
Turkish Journal of Earth Sciences
The International Union of Geological Sciences (IUGS) has proposed recommendations for the classification of relatively fresh volcanic rocks, but with no specific instructions for altered volcanic rocks, other than discouraging the use of the total alkalis versus silica diagram. The Nb/Y-Zr/TiO2 diagram has been in use for the classification of altered rocks now for over 30 years. Recently (during 2007) another diagram (Co-Th) has been proposed to replace this old diagram, particularly for altered arc rocks. Using an extensive database of all kinds of relatively fresh rocks from four tectonic settings (island arc, continental rift, ocean island, and mid-ocean ridge), …
The Impact Of Tsunamis On The Island Of Majorca Induced By North Argelian Seismic Sources, José A. Álvarez-Gómez, Maitane Olabarrieta, Mauricio González, Luís Otero, Emilio Carreño, José M. Martínez-Solares
The Impact Of Tsunamis On The Island Of Majorca Induced By North Argelian Seismic Sources, José A. Álvarez-Gómez, Maitane Olabarrieta, Mauricio González, Luís Otero, Emilio Carreño, José M. Martínez-Solares
Turkish Journal of Earth Sciences
The north of Algeria is the main earthquake-related tsunami generation zone that threatens the Balearic Islands. In this work we review the major seismic series of the area -the 1980 El Asnam and the 2003 Boumerdes-Zemmouri earthquakes– in order to obtain a probable worst characteristic earthquake rupture. We estimate rupture dimensions of 55 km x 16 km, reaching the fault plane a depth of 13 km. The dip and rake have been taken as constants, with values of 50° and 90° respectively, while the strike is adjusted to the local tectonic structure. With these characteristics a magnitude M_w= 7.3 earthquake …
Oligocene History Of The Çardak - Dazkırı Subbasin (Denizli, Sw Turkey): Integrated Molluscan And Planktonic Foraminiferal Biostratigraphy, Yeşi̇m İslamoğlu, Aynur Hakyemez
Oligocene History Of The Çardak - Dazkırı Subbasin (Denizli, Sw Turkey): Integrated Molluscan And Planktonic Foraminiferal Biostratigraphy, Yeşi̇m İslamoğlu, Aynur Hakyemez
Turkish Journal of Earth Sciences
The detailed analysis of molluscan and planktonic foraminiferal fauna in the Oligocene Çardak-Dazkırı sub-basin, in northeastern Denizli provin ce (western Turkey) allowed accurate dating of the deposits, together with interpretation of their depositional environments. Gastropod, bivalve, scaphopod and planktonic foraminiferal assemblages identified in ten sections reveal a succession which was deposited between the Late Rupelian and Early Chattian. Planktonic foraminifera, documented for the first time in the basin, indicate the P19 Zone (Turborotalia ampliapertura Zone) of the Late Rupelian at the base of the succession whereas Molluscan fauna, determined for the first time in this study, assign the whole succession, …
Application Of The Normalized Full Gradient (Nfg) Method To Resistivity Data, Ali̇ Aydin
Application Of The Normalized Full Gradient (Nfg) Method To Resistivity Data, Ali̇ Aydin
Turkish Journal of Earth Sciences
This paper proposes the application of the normalized full gradient (NFG) method to resistivity studies and illustrates that the method can greatly reduce the time and work load needed in detecting buried bodies using resistivity measurement. The NFG method calculates resistivity values at desired electrode offsets by extrapolation of a function of resistivity measurements (i.e. the gradient) to other depth levels using resistivity measurements done at one electrode offset only. The performance and reliability of the NFG method is tested on laboratory and field resistivity data from two sites by comparing the trend of the resistivity values at six or …
Taxonomy Of Rudists From The Campanian Transgressive Sediments Of Brašljevica, Donje Orešje And Sv. Martin, Northern Croatia, Alan Moro, Vlasta Cosovic, Josip Benic, Jasmina Dokmanovic
Taxonomy Of Rudists From The Campanian Transgressive Sediments Of Brašljevica, Donje Orešje And Sv. Martin, Northern Croatia, Alan Moro, Vlasta Cosovic, Josip Benic, Jasmina Dokmanovic
Turkish Journal of Earth Sciences
Rudists are common fossils in transgressive Upper Cretaceous deposits in three localities placed in northwestern part of Croatia. Their appearances coincide with the beginning of a transgressive sequence through floatstones-thickets. Within the rudist community, Vaccinites Fischer 1887, Hippurites Lamarck 1801 and Hippuritella Douvillé 1908 could be differentiated according to their general or generic morphological elements. The age of deposits was obtained from the Sr-isotope composition of the rudist shells as well as the micro- and nannofossil community from sediments overlying the rudists-bearing sediments at the Donje Oresje and Brasljevica localities. According to this data the age of the transgressive sediments …
Morphology, Taxonomy And Lifestyle Of The Maastrichtian Rudist Bivalve Thyrastylon, Simon Francis Mitchell
Morphology, Taxonomy And Lifestyle Of The Maastrichtian Rudist Bivalve Thyrastylon, Simon Francis Mitchell
Turkish Journal of Earth Sciences
The rudist bivalve Thyrastylon is redescribed based on extensive material collected from Jamaica. The new material shows that the left valve contains slits, and that this is the diagnostic feature of the genus. The genus is redefined as follows: a radiolitid rudist with no ligamental infold, stretched cellular microstructure and compact layers in the outer layer of the right valve; the radial bands are partially infolded into the shell layer of the right valve; the left valve has oscules developed above the radial bands and has concentric, slit-like pores that penetrate the shell and open out onto the inner part …
Numerical Ages Of Selected Rudist Bivalvia: Preliminary Results, Robert W. Scott
Numerical Ages Of Selected Rudist Bivalvia: Preliminary Results, Robert W. Scott
Turkish Journal of Earth Sciences
The ranges of most biostratigraphically diagnostic fossils have been calibrated to the geologic time scale in mega-annums. Five methods for integrating fossil ranges with the numerical geologic time scale are currently used: (1) species in stratigraphic positions with radiometrically dated beds; (2) strontium isotopes of unaltered shell material; (3) cyclostratigraphic frequencies of enclosing strata; (4) integration with zones and sequence stratigraphy; and (5) graphic correlation. Preliminary studies show that rudist occurrences have been calibrated in numerical ages by Sr isotopes, zonal integration and graphic correlation. Where the same species are dated by two methods, a more complete range is the …
Cellular Distribution Of Activity For Three Enzymes With Maltose Binding Protein As Fusion Partner And The Structural Implications, Özde F. Ütkür, Berna Sariyar Akbulut, Amable Hortaçsu
Cellular Distribution Of Activity For Three Enzymes With Maltose Binding Protein As Fusion Partner And The Structural Implications, Özde F. Ütkür, Berna Sariyar Akbulut, Amable Hortaçsu
Turkish Journal of Chemistry
The bacterial SEC pathway is commonly used for secretion of heterologous proteins in E. coli by fusing them to transported proteins to facilitate downstream processing. While some proteins are translocated very efficiently, some reside in the cytoplasm. In this work, maltose binding protein (MBP) was fused to 3 cytoplamic enzymes from Thermus thermophilus (serine protease, 251 residues; glucose isomerase, 381 residues; pullulanase, 718 residues) to study the protein transport from the cytoplasm by quantifying the distribution of activities in different cellular compartments. Pullulanase activity was harvested exclusively in the periplasm; however, glucose isomerase activity was harvested exclusively in the cytoplasm. …
Electro-Oxidation Of Some Non-Steroidal Anti-Inflammatory Drugs On An Alumina Nanoparticle-Modified Glassy Carbon Electrode, Mahla Tabeshnia, Hossein Heli, Ali Jabbari, Ali A. Moosavi-Movahedi
Electro-Oxidation Of Some Non-Steroidal Anti-Inflammatory Drugs On An Alumina Nanoparticle-Modified Glassy Carbon Electrode, Mahla Tabeshnia, Hossein Heli, Ali Jabbari, Ali A. Moosavi-Movahedi
Turkish Journal of Chemistry
The electro-oxidation of mefenamic acid, diclofenac, and indomethacin on glassy carbon and alumina nanoparticle-modified glassy carbon electrodes in a phosphate buffer solution at physiological pH was studied. The techniques of cyclic voltammetry, chronoamperometry, impedance spectroscopy, and steady state polarization measurements were applied. The drugs were irreversibly oxidized on bath electrodes via an anodic peak and the process was controlled by diffusion in the bulk of solution. Alumina nanoparticles increased the oxidation current, and lowered the peak and onset potentials. As such, alumina nanoparticles had an electrocatalytic effect, both kinetically and thermodynamically. The kinetic parameters of heterogeneous electron transfer and diffusion …
Influence Of Alcl_3 On The Optical Properties Of New Synthesized 3-Armed Poly(Methyl Methacrylate) Films, Adnan Kurt
Influence Of Alcl_3 On The Optical Properties Of New Synthesized 3-Armed Poly(Methyl Methacrylate) Films, Adnan Kurt
Turkish Journal of Chemistry
Three-armed poly(methyl methacrylate)[PMMA] was synthesized by atom transfer radical polymerization at 100 °C using benzene-1,3,5-triyl tris(4-(bromomethyl) benzoate as 3-armed initiator and a cuprous(I) bromide/2,2'-bipyridine catalytic system. The characterization of PMMA was confirmed by FT-IR, ^1H-NMR, GPC, DSC, and TGA techniques. Optical absorption measurements were also studied by UV-VIS technique. Transmittance and reflectance measured in the wavelength range 300-700 nm were used to calculate the optical constants. The changes in dispersion and Urbach parameters were investigated as a function of AlCl_3 content. The wide band tails increased in width and the optical energy gap decreased from 2.39 to 1.28 eV as …
Multichannel Spectrophotometry For Analysis Of Organophosphate Paraoxon In Beverages, Miroslav Pohanka, Jana Zdarova Karasova, Kamil Kuca, Jiri Pikula
Multichannel Spectrophotometry For Analysis Of Organophosphate Paraoxon In Beverages, Miroslav Pohanka, Jana Zdarova Karasova, Kamil Kuca, Jiri Pikula
Turkish Journal of Chemistry
Multichannel spectrophotometry was performed to assay for paraoxon in spiked beverages. A 96-well microplate was used for this purpose. The measuring protocol was based on inhibition of the enzyme acetylcholinesterase by paraoxon that resulted in decreased or no reaction of the enzyme product thiocholine with Ellman's reagent (5,5'-dithiobis [2-nitrobenzoic acid]). The above assay was practically tested using spiked drinking water, mineral water, and coffee. Analytical parameters such as the limit of detection, time, and sample size consumption were adequate. The limit of detection for beverages ranged from 32 to 48 ppb corresponding to 0.32-0.48 ng of paraoxon in absolute values. …
Ionic Liquids As Solvent For Efficient Esterification Of Carboxylic Acids With Alkyl Halides, Yetki̇n Gök, Bülent Alici, Engi̇n Çeti̇nkaya, İsmai̇l Özdemi̇r, Özlem Özeroğlu
Ionic Liquids As Solvent For Efficient Esterification Of Carboxylic Acids With Alkyl Halides, Yetki̇n Gök, Bülent Alici, Engi̇n Çeti̇nkaya, İsmai̇l Özdemi̇r, Özlem Özeroğlu
Turkish Journal of Chemistry
The selective esterification of carboxylic acid derivatives with a variety of alkyl halides was carried out using ionic liquid as solvent in the presence of triethylamine. The reaction was found to proceed under relatively mild conditions with excellent conversions (up to 99%) and selectivities. The ionic liquid was recycled and reused.
Chelating Agent Free Solid Phase Extraction (Caf-Spe) Method For Separation And/Or Preconcentration Of Iron(Iii) Ions, Özcan Yalçinkaya, Orhan Murat Kalfa, Ali̇ Rehber Türker
Chelating Agent Free Solid Phase Extraction (Caf-Spe) Method For Separation And/Or Preconcentration Of Iron(Iii) Ions, Özcan Yalçinkaya, Orhan Murat Kalfa, Ali̇ Rehber Türker
Turkish Journal of Chemistry
This paper presents a chelating agent free solid phase extraction (CAF-SPE) method for the separation and/or preconcentration of trace iron(III) ions. This method is based on the sorption of Fe(III) ions without using any chelating agent onto Amberlyst 36 resin. A good relative standard deviation (3%), high recovery (>95%), high enrichment factor (100), and low detection limit (0.32 \mu g L^{-1}) were obtained. The adsorption capacity of resin was 117 mg g^{-1} for iron(III). The method was applied for the determination of iron various in water and commercial tea bag samples. The accuracy of the method was confirmed by …
Isolation Of Bis(1,4-Diphenyl-1,4-Bis(2-Pyridyl)-2,3-Diaza-1,3-Butadiene) Disilver With Bridging (N-N) Dinucleating Subunits: Formation Of A 6-Membered Chelate Ring, Amitabha Datta, Neerish Revaprasadu
Isolation Of Bis(1,4-Diphenyl-1,4-Bis(2-Pyridyl)-2,3-Diaza-1,3-Butadiene) Disilver With Bridging (N-N) Dinucleating Subunits: Formation Of A 6-Membered Chelate Ring, Amitabha Datta, Neerish Revaprasadu
Turkish Journal of Chemistry
A novel Ag(I) dinuclear complex {[(C_6H_5)(C_5H_4N)-C=N-N=C- (C_5H_4N)(C_6H_5)]Ag}_2.ClO_4(ClO_4) (1/2CH_3CN) (1) that was derived under mild conditions, during the course of combination of AgClO_4 with a polymorphic azine ligand, 1,4-diphenyl-1,4-bis(2-pyridyl)-2,3- diaza-1,3-butadiene (L) (condensed product of phenyl 2-pyridyl ketone and hydrazine monohydrate) is reported. The aforementioned complex is based on a central rotationally flexible diazine subunit (N-N). The azine ligand, L, having the N_2 dinucleating fragment, provides a coordination focus for pairs of metal centres and ultimately leads to the formation of a 6-membered chelate ring in 1.
Comparative Kinetic Studies On The Alkaline Hydrolysis Of Halogen Substituted Isocoumarins, Hafiz Badaruddin Ahmad, Muhammad Aslam Malana, Muhammad Yousaf, Muhammad Rehan, Mazhar Abbas
Comparative Kinetic Studies On The Alkaline Hydrolysis Of Halogen Substituted Isocoumarins, Hafiz Badaruddin Ahmad, Muhammad Aslam Malana, Muhammad Yousaf, Muhammad Rehan, Mazhar Abbas
Turkish Journal of Chemistry
Kinetics of the hydrolysis of 3-(2'-chloro-6'-fluorobenzyl) isocoumarin (1), 3-(4'-fluorophenyl)isocoumarin (3), 3-(2'- fluorophenyl)isocoumarin (5), 3-(2'-chlorophenyl)isocoumarin (7), and 3-(4'-chlorophenyl)isocoumarin (9) were studied spectrophotometrically in the presence of aqueous solution of potassium hydroxide. The rates of hydrolyses for these isocoumarins were compared. The data for isocoumarin (1) were further investigated to probe the reaction mechanism. The dependence of pseudo-first order rate constant k_{obs} on hydroxide ion concentration is fitted by the expression k_{obs} = k_o + k_1[OH] + k_2 [OH]^2, showing the formation of monoanionic and dianionic tetrahedral intermediates during the course of reaction. The magnitude of k_o shows significant participation of solvent …
A Theoretical Study Of The Effects Of Polar Substitution On The Activation Barriers For Internal Rotation Around The C-N Bond In P-Substituted Nitrosobenzenes: Comparison Of Dft And Mp2 Calculations, Şafak Özhan Kocakaya, Necmetti̇n Pi̇ri̇nççi̇oğlu
A Theoretical Study Of The Effects Of Polar Substitution On The Activation Barriers For Internal Rotation Around The C-N Bond In P-Substituted Nitrosobenzenes: Comparison Of Dft And Mp2 Calculations, Şafak Özhan Kocakaya, Necmetti̇n Pi̇ri̇nççi̇oğlu
Turkish Journal of Chemistry
The activation barriers for internal rotation around the C-N bond in p-substituted nitrosobenzenes were calculated using the density functional theory (DFT) and second-order Møller-Plesset (MP2) methods with the 6-31+g(d) basis set. The polarisable continuum model (PCM) was used to model the solvent effect. An explicit water molecule was also introduced to form a hydrogen bond with the nitrosogroup and its effect on the barrier was studied by DFT. The barriers were well-correlated with Hammett sigma^+ rather than sigma values, meaning a strong resonance effect. The MP2 method produces better and comparable results with the few available experimental values.
An Efficient One-Pot Synthesis Of Dihydropyrimidinones Catalyzed By Zirconium Hydrogen Phosphate Under Solvent-Free Conditions, Mustafa Küçüki̇slamoğlu, Şenol Beşoluk, Mustafa Zengi̇n, Mustafa Arslan, Mehmet Nebi̇oğlu
An Efficient One-Pot Synthesis Of Dihydropyrimidinones Catalyzed By Zirconium Hydrogen Phosphate Under Solvent-Free Conditions, Mustafa Küçüki̇slamoğlu, Şenol Beşoluk, Mustafa Zengi̇n, Mustafa Arslan, Mehmet Nebi̇oğlu
Turkish Journal of Chemistry
A simple, efficient, and practical procedure for the Biginelli reaction using zirconium hydrogen phosphate [Zr(H_2PO_4)_2] as a novel solid acid catalyst is described under solvent-free conditions in high yields. The catalyst exhibited remarkable reactivity and it is reusable.