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Articles 2551 - 2580 of 2628
Full-Text Articles in Physical Sciences and Mathematics
Phase Transition Of Hydrolyzed Polyacrylamide Gels In Aqueous Solutions Of Poly(Ethylene Glycol), Nilhan Kayaman, Oğuz Okay, B. M. Baysal
Phase Transition Of Hydrolyzed Polyacrylamide Gels In Aqueous Solutions Of Poly(Ethylene Glycol), Nilhan Kayaman, Oğuz Okay, B. M. Baysal
Turkish Journal of Chemistry
Hydrolyzed polyacrylamide gels immersed in aqueous solutions of poly(ethylene glycol) (PEG) of molecular weight 300 exhibit a discontinuous volume change upon continuous increase of the PEG concentration in the external solution. As the duration of hydrolysis increases, that is, as the proportion of the ionic groups on the network chains increases, the critical concentration of PEG required for a discontinuous volume change rises and, also, the magnitude of the volume collapse becomes larger. Experimental results indicate that the gel collapse in PEG solution is due to the osmotic deswelling of the ionic gel rather than due to a complex formation …
High Rates Of Fluorescence Quenching Between Perylene Dodecyldiimide And Certain \Pi-Electron Donors, S. İçli̇, H. İci̇l, İ. Gürol
High Rates Of Fluorescence Quenching Between Perylene Dodecyldiimide And Certain \Pi-Electron Donors, S. İçli̇, H. İci̇l, İ. Gürol
Turkish Journal of Chemistry
Perylene bis-n-dodecyl diimide is found to quench fluorescenc emissions of naphthalene, phenanthrene and dihydrocarbazolocarbazole molecules at rates of 4.4\times10^{11}, 2.8\times10^{12} and 2.5\times10^4 M^{-1} sec^{-1}, in respective order of aromaticity. These unusulally high rates of fluorecence quenchings are attributed to Perrin model static quenching and presence of electron transfer through singlet excited state of perylene diimide. Calculated free energy of electron transfer, \Delta G_{ET}=-120.5 kJ/mol, between perylene diimide and dihydrocarbazolocarbazole is taken as evidence for observation of high fluorescence quenching rate for carbazolocarbazole molecule. Keywords: Fluorescence quenching, Photoenergy transfer, Perylene diimide and Carbazolocarbazole
Possible Roles Of Transition Metals In Cloudwater Relative To The Solar Short-Wave Radiation Absorption Anomaly, Xudong Huang, S. Sinan Keski̇n, Francis Pink, İlhan Ölmez
Possible Roles Of Transition Metals In Cloudwater Relative To The Solar Short-Wave Radiation Absorption Anomaly, Xudong Huang, S. Sinan Keski̇n, Francis Pink, İlhan Ölmez
Turkish Journal of Chemistry
Measurements of the absorption of solar short-wave radiation by clouds exceed those predicted by theoretical calculations. In order to understand the roles of minor and trace species in this absorption anomaly, cloudwater samples were collected from individual precipitating clouds and analyzed for trace metals and anionic species. Two generalized approaches were used to assess the direct impact of the absorption of solar short-wave radiation by transition metals and/or their anionic complexes. Additionally, it was suggested that iron and manganese may act as catalyts in the formation of sulfate aerosols which efficiently scatter solar radiation.
Constituents Of Salvia Verticillata, Ufuk Sönmez, Gülaçtı Topçu, Ayhan Ulubelen
Constituents Of Salvia Verticillata, Ufuk Sönmez, Gülaçtı Topçu, Ayhan Ulubelen
Turkish Journal of Chemistry
Three new and fourteen known compounds were isolated from the roots of {\it Salvia verticillata L.} Spectral methods were used for the structure determination besides TLC comparisons with authentic samples for the known compounds.
Immobilization Of Glucose Oxidase And Urease In Hydrogel Matrices, İhsan Gürel, M.Yakup Arica, Vasıf Hasirci
Immobilization Of Glucose Oxidase And Urease In Hydrogel Matrices, İhsan Gürel, M.Yakup Arica, Vasıf Hasirci
Turkish Journal of Chemistry
Immobilization of glucose oxidase and urease in hydrogels of 2-hydroxyethyl methacrylae, and N-vinyl pyrrolidone (NVP) was achieved by irradiation (using UV kand \gamma- rays). The effect of radiation on entrapment efficiencies, retention of activities and swelling rates was obtained. To optimize the system, duration of exposure, reaction temperature, co-monomer concentrations, initiator and cross linker compositions were varied. The repeated reusability of the generated products was also tested. It was found that\gamma-irradiation at very low temperatures did not have a detrimental effect on the enzyme activity. Incorporation of more hydrophilic monomer (NVP), influenced matrix morphology and entrapment efficiencies and retained enzyme …
A Study Of The Thermodynamical Interactions Of Bisphenol-A Polycarbonate With Some Solvents By Gas Chromatography, Özlem Cankurtaran, Ferdane Yilmaz
A Study Of The Thermodynamical Interactions Of Bisphenol-A Polycarbonate With Some Solvents By Gas Chromatography, Özlem Cankurtaran, Ferdane Yilmaz
Turkish Journal of Chemistry
Retentin diagrams of polycarbonate for n-nonane, ethyl acetate and n-butyl acetate were obtained using inverse gas chromatography in the temperature range 80-240^{\circ}C. The specific retention volumes, V^{\circ}_{g} the Flory-Huggins interaction parmeters, \chi^{\infty}_{12}, interaction parameters, \chi^{\ast}_{12}, and effective exchange-energy parameters \bar{X}_{12} of the equation-of-state theory of polycarbonate for n-octane, n-nonane, n-decane, ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate and isoamyl acetate were obtained in the temperature range 200-240^{\circ}C. The parameter \delta_2 was estimated to be 10.7 (cal/cm^3)^{1/2} at room temperature using the \chi^{\infty}_{12} extrapolated to room temperature. Keywords: Bisphenol-A polycarbonate, polymer-solvent interactions, inverse gas chromatography, solubility parameter.
Photoelectron Spectroscopy: A Tool In Sorption Studies, Şefik Süzer, Hasan N. Erten
Photoelectron Spectroscopy: A Tool In Sorption Studies, Şefik Süzer, Hasan N. Erten
Turkish Journal of Chemistry
Photoelectron spectroscopy using AlK\alpha (h\nu=1486.3 eV) has been applied to study the sorption of Cs^+, Sr^{2+}, Ba^{2+}, Zn^{2+} and Co^{2+} on magnesite kaolinite, smectite and chlorite. From the observed intensities of photoelectron peaks it was determined that in magnesite the sorption affinity of the above ions follow the order: Ba^{2+}>Co^{2+}\congSr^{2+}\congZn^{2+}>Cs^+. The order for the sorption of Ba^{2+} and Cs^+ are also determined as chlorite>magnesite>smectite>kaolinite and smectite>chlorite\congkaolinite>magnesite, respectively.
A Topological Approach To The Stabilities Of Isomeric Hückel And Mobius Type Cyclacenes, Lemi Türker
A Topological Approach To The Stabilities Of Isomeric Hückel And Mobius Type Cyclacenes, Lemi Türker
Turkish Journal of Chemistry
Within the constraints of Hückel molecular orbital theory, Hückel and Mobius type cyclacenes were investigated in terms of their angle of total \pi-electron energy, O_{\pi}, and cos O_{\pi} to find out how structural changes affect the stabilities. It has been theoretically deduced that as the number of benzenoid rings (R) increases the isomeric Hückel and Mbius type cyclacenes should have comparable stabilities, although for low values of R odd-Hückel type and even-Mobius type are predicted to be more stable.
Potentiometric And Spectroscopic Determinaton Of Acid Dissociation Constants Of Some Phenols And Salicylic Acids, Rahmiye Aydin, Ulviye Özer, Naciye Türkel
Potentiometric And Spectroscopic Determinaton Of Acid Dissociation Constants Of Some Phenols And Salicylic Acids, Rahmiye Aydin, Ulviye Özer, Naciye Türkel
Turkish Journal of Chemistry
The dissociation constant of the catechol derivatives 4-nitrocatechol (NCAT), 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DBHA), 3,4-dihydroxyhenylacetic acid (3,4-DPHA) and 3,4-dihydroxycinnamic acid (3,4-DHCA) were identified in 0.1M NaClO_4 ionic medium, at t=25^{\circ}C, by potentiometry. In addition, the first and second dissociation constants of the salicylic acid derivatives 5-nitrosalicylic acid (5-NSA), 4-hydroxysalicylic acid (4-HSA) 5-nitrosalicylic acid (5-HSA) were also determined by potentiometry. Furthermore, the second acid dissociation constants of these ligands were evaluated in I=0.1M NaClO_4 ionic medium, at a temperature of 25^{\circ}C by computer analysis of spectroscopic data.
Polymer Light Emitting Diodes, Frank E. Karasz, Bin Hu, Zhou Yang
Polymer Light Emitting Diodes, Frank E. Karasz, Bin Hu, Zhou Yang
Turkish Journal of Chemistry
Polyphenylene vinylene-based conjugated-nonconjugated alternating block copolymers form the active chromophores in a series of light emitting diodes (LEDs). The quantum efficiency and brightness of these devices can be improved by several orders of magnitude by incorporation of appropriate carrier transport layers and by rational choice of electrodes. Further improvements can be gained by blending of the active chromophores with high or low molecular weight species.
Novel Architectures Of Macromolecular Systems, Gerhard Wegner
Novel Architectures Of Macromolecular Systems, Gerhard Wegner
Turkish Journal of Chemistry
An important thrust in modern macromolecular chemistry is to construct complex architectures either directly from monomer units, or to design macromolecules capable of forming a desired superstructure by self-organization. Chain-rigidity is an example of a structural principle leading to self organization depending on the aspect ratio of the molecular objects and their mutual interactions. These molecularly defined objects serve as the building blocks of systems for which ultrathin layers composed of hairy rod macromolecules (HRM) are an example. Depending on architectural details layered architectures of HRM are models for molecular nanocomposites, exhibit interesting optical, electrochemical, dielectric or barrier properties. They …
Analytical Applications Of Organic Conducting Polymer Electrodes, Nada F. Atta, George C. Russell, Z. Wang, N. Akmal, J.F. Rubinson, S.K. Lunsford, E. Karagözler, O. Y. Ataman, H. Zimmer, H.B. (Jr.) Mark, Ahmed Galal
Analytical Applications Of Organic Conducting Polymer Electrodes, Nada F. Atta, George C. Russell, Z. Wang, N. Akmal, J.F. Rubinson, S.K. Lunsford, E. Karagözler, O. Y. Ataman, H. Zimmer, H.B. (Jr.) Mark, Ahmed Galal
Turkish Journal of Chemistry
Electrodes modified by he electrodeposition of conducting polymers were used for the detection and quantitative determination of some inorganic, organic, and biological molecules. Monomers used were five membered ring heterocycles or crown ethers and their derivatives. The polymer films were deposited on glassy carbon or platinum substrates. The resulting electrodes were used in the amperometric mode or in the potentiometric mode for flow injection and chromatographic analyses. The results showed that the proposed modified surface catalyzes the oxidation of organic and biological compounds. The detection of electroinactive inorganic anions, such as F^-, Cl^-, Br^-, NO_2^- and NO^-_3 was also possible …
Reduction Of Combustion Generated Pollution: Process Modifications And Energy Efficient Power Cycles, Janos M. Beer
Reduction Of Combustion Generated Pollution: Process Modifications And Energy Efficient Power Cycles, Janos M. Beer
Turkish Journal of Chemistry
Theoretical bases of combustion process modifications aimed at the reduction of pollutant emission are examined. It is shown, as an example, of how the minimization of emissions of nitrogen oxides leads to a design protocol that translates results of modeling and of bench scale experiments into guidelines for industrial design. The formation and emission of polycyclic aromatic compounds is also considered, because their formation is strongly favored in "low NO_x flames". In power generation the pollutant emission can be reduced effectively by the improvement of the ``heat rate,"i.e., the thermodynamic efficiency of the power cycle. Combined gas turbine-steam cycles which …
Synthesis And Characterization Of Complexes Of Co(Ii), Ni(Ii), Cd(Ii), Hg(Ii) And Pd(Ii) With Some N-Phenyl-N^{1}-2-[4-Phenyl-(Substituted) Thiazolyl]- Thioureas, B. Narayana, M. R. Gajendragad
Synthesis And Characterization Of Complexes Of Co(Ii), Ni(Ii), Cd(Ii), Hg(Ii) And Pd(Ii) With Some N-Phenyl-N^{1}-2-[4-Phenyl-(Substituted) Thiazolyl]- Thioureas, B. Narayana, M. R. Gajendragad
Turkish Journal of Chemistry
The Synthesis and characterization of the complexes of Co(II), Ni(II), Pd(II), Cd(II) and Hg(II) with N-phenyl-N^{1}-2(-4-phenylthiazoly)thiourea (PPT) and N-phenyl-N^{1}-2-(4-methylphenylthiazolyl)-thiourea (PMPT) and Co(II), Cd(II), and Hg(II) complexes of N-phenyl-N^{1}-2-(4-p- chlorophenylthiazolyl) thiourea (PCPT) are included in this paper. Based on analytical results, electronic and infrared spectral data and magnetic susceptibility measurements, plausible structures have been proposed.
Factors Influencing The Angle Of Total Ii-Electron Energies Of Alternant Hydrocarbons, Lemi Türker
Factors Influencing The Angle Of Total Ii-Electron Energies Of Alternant Hydrocarbons, Lemi Türker
Turkish Journal of Chemistry
Within the framework of the Hückel molecular orbital theory, the topological factors affecting the angle of total \pi-electron energies of alternant hydrocarbons were investigated.
Spectrophotometric Determination Of The Pk_A Values Of Some Aminoacid Complexes Of Pentacyanoferrate(Ii) And Pentacyanoruthenate(Ii), Yakup Baran, Şebnem Baran, N. Kemal Tunali
Spectrophotometric Determination Of The Pk_A Values Of Some Aminoacid Complexes Of Pentacyanoferrate(Ii) And Pentacyanoruthenate(Ii), Yakup Baran, Şebnem Baran, N. Kemal Tunali
Turkish Journal of Chemistry
The syntheses, pK_a and spectrospcopic characterization of [Fe(CN)_5(H_2O)]^{-3} and [Ru(CN)_5(H_2O)]^{-3} complexes of alanine(Ala), glycine(Gly), valine(Val), lysine(Lys), arginine(Arg) and cysteine(Cys) complexes were investigated in aqueous solution. The spectra of the complexes containing amino acid ligands were similar to that of [Fe(CN)_5(NH_3)]^{-3}. The pK_a values of the complexes were measured by spectrophotometric titration at 22^{\circ}C and \mu =0.100 M(NaClO_4).
Carbonic Anhydrase From Nicotiana Tabacum Leaves, Nazan Demi̇r, Yaşar Demi̇r
Carbonic Anhydrase From Nicotiana Tabacum Leaves, Nazan Demi̇r, Yaşar Demi̇r
Turkish Journal of Chemistry
In this study, carbonic anhydrase (CA: carbonate hydrolyase; E.C.4.2.1.1) was purified from adult {\it Nicotiana tabacum} leaves and studied biochemically. The enzyme was purified twice times by using (NH$_4)_2SO_4 precipation and DEAE-cellulose column chromatography, and its activity was determined for two different substrates (CO_2 and p-nitrophenyl acetate). The enzyme obtained from the ion exchange column was purified 40.7 fold and the purity was controlled by 3\%-10\% discontinuous SDS-PAGE. The pH of the purified enzyme varied between 6.0 and 7.2, the optimum being 6.9. V_{max} and K_m values were calculated with p-nitrophenyl acetate (0.1524 mM, 0.5446 mM, respectively) as substrate. The …
Determination Of Ponceau 4r And Tartrazine In Various Food Samples By Derivative Spectrophotometric Methods, Sedat Sayar, Yüksel Özdemi̇r
Determination Of Ponceau 4r And Tartrazine In Various Food Samples By Derivative Spectrophotometric Methods, Sedat Sayar, Yüksel Özdemi̇r
Turkish Journal of Chemistry
Derivative spectrophotometric methods were originally developed for determining Ponceau 4R and Tartrazine in order to resolve their binary mixtures. The method permits the simultaneous determinations of these food colorants in various food samples. Recovery by derivative methods was nearly 100 \%.
Epr Spectroscopy Of Dog-Rose Polyphenoloxidase, Çiğdem Nuhoğlu, Fatih Ucun, Enise Ayyildiz, Y. Kemal Yoğurtçu, Halis Şaki̇roğlu, İrfan Küfrevi̇oğlu
Epr Spectroscopy Of Dog-Rose Polyphenoloxidase, Çiğdem Nuhoğlu, Fatih Ucun, Enise Ayyildiz, Y. Kemal Yoğurtçu, Halis Şaki̇roğlu, İrfan Küfrevi̇oğlu
Turkish Journal of Chemistry
Polyphenoloxidase(PPO) of dog-rose fruit was extracted and purified through (NH\4)\2SO\4 precipitation and dialysis. The optimum conditions for this purpose, i.e., pH and temperature, were determined with 4-methylcatechol optimum pH and temperature and found to be pH 8.5 and 20\ci, respectively. The inhibition effect of ascorbic acid was investigated and the I_{50} value was found to be 1.57\times10^{-4} M. The activity of dog-rose PPO was investigated by electron paramagnetic resonance (EPR) at different pH levels and temperatures. The optimum conditions obtained from both spectrophotometry and EPR were compared.
^1h Nmr, Infrared And Mass Spectrometry Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Muhammad Mazhar, Moazzam Hussain Bhatti, Sohail Mahmood, Abida Kalsoom
^1h Nmr, Infrared And Mass Spectrometry Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Muhammad Mazhar, Moazzam Hussain Bhatti, Sohail Mahmood, Abida Kalsoom
Turkish Journal of Chemistry
The di- and tri-organotin derivatives R\2SnL\2 and R\3SnL where R = CH\3, n--C\4H\9, C\6H\5, C\6H_{11} and C\6H\5CH\2 and L = 1-nitroso-2-naphthoxy were synthesized. These derivatives were characterized by elemental analysis, infrared, ^1H NMR and mass spectrometry.
Some Remarks On Solid State Polymerization, George Adler
Some Remarks On Solid State Polymerization, George Adler
Turkish Journal of Chemistry
No abstract provided.
Calculation Of Spreading Pressure Of Water On Cellulosic Films From Contact Angle Data, H. Yıldırım Erbi̇l
Calculation Of Spreading Pressure Of Water On Cellulosic Films From Contact Angle Data, H. Yıldırım Erbi̇l
Turkish Journal of Chemistry
The correlations between the surface properties of the modified cellulose papers with their toner compatibility were investigated. The surface tension components of the cellulosic films, their interfacial tension with the liquid drops and the work of adhesion components were calculated using van Oss-Good's One-Liquid contact angle approach. The electron donor (or Lewis base) \gamma^- components of the cellulosic films were found to represent the main interactions with the the electron acceptor (acidic) \gamma^+ components of the contacting liquids. Allyl ketene dimer (AKD) grafting of the cellulose affected the surface properties; the higher the substitution of the hydroxyl group, the smaller …
A Quantum-Chemical Investigation On 5,5'-Bi(1h-1.2,4-Triazole)), A. A. İki̇zler, R. Abbasoğlu, N. Saltek, M. Şeri̇fova
A Quantum-Chemical Investigation On 5,5'-Bi(1h-1.2,4-Triazole)), A. A. İki̇zler, R. Abbasoğlu, N. Saltek, M. Şeri̇fova
Turkish Journal of Chemistry
The conformational analysis of flexible 5,5'-bi(1H-1,2,4-triazole) molecule containing various reaction centers has been performed by the semiempirical methods MNDO,AM1 and PM3, and the internal rotation barrier calculated. The most stable conformation of the molecule has been determined to be the planar trans conformation. According to the three methods, 5,5'-bi(1H-1,2,4-triazole) molecule (C) has been found to be relatively more stable than its tautomer 3,3'-bi(1H-1,2,4-triazole)(B) and to be less stable than its other tautomer 3,3'-bi(4H-1,2,4-triazole)(A). Moreover, the electronic properties of 5,5'-bi(1H-1,2,4-triazole) molecule and the effect of conformational changing on electronic and geometric properties have also been investigated. To determine the protonation sites …
The Reliability Of Jung-Biggs-Moorhead Method For Cholesterol Determination In The Presence Of Ergosterol, Lemi Türker, Şahinde Demi̇rci̇, Marjan Akdağ
The Reliability Of Jung-Biggs-Moorhead Method For Cholesterol Determination In The Presence Of Ergosterol, Lemi Türker, Şahinde Demi̇rci̇, Marjan Akdağ
Turkish Journal of Chemistry
In the present study, the reliability of Jung-Biggs-Moorhead method for cholesterol determination has been tested in the presence of another steroid, ergosterol. It was observed that presence of ergosterol interferes with the absorbance measurement of cholesterol. When both steroids are present in the sample maximum absorption wavelength are not shifted by the mutual interaction but absorbance values are changed considerably. Therefore this method may be used only for qualitative bu not quantitative analysis for cholesterol in the presence of ergosterol.
Synthesis And Characterisation Of Anhydrous Magnesium Phosphate Mg$_3$(Po$_4$)$_2$, A. Baykal, M. Kizilyalli, R. Kniep
Synthesis And Characterisation Of Anhydrous Magnesium Phosphate Mg$_3$(Po$_4$)$_2$, A. Baykal, M. Kizilyalli, R. Kniep
Turkish Journal of Chemistry
The synthesis and characterization of anhydorus Mg_3(PO$_4)_2 was investigated. Mg_3(PO$_4)_2 is reported to have similar structural arrangements with Co_3(PO_4)_2 and \gamma-Zn_3(PO_4)_2 compounds. The sample was prepared by a new technique which is the reaction of MgCl_2.6H_2O and Na_3PO_4.12H_2O solutions at pH=5.1, which was adjusted by adding concentrated H_3PO_4 to the reaction mixture and heating the precipitated product at 600^{\circ}C untill constant weight. The purity of the product was checked by X-ray powder diffraction, IR, density measurement, SEM and DTA analysis. The monoclinic unit cell dimensions of product are a=7.605 (2), b=8.233 (3), c=5.080 (1)A^{\circ} and \beta= 94.19^{\circ} (3), which was …
Hydrolysis And Condensation Reactions Of Methacrylate-Modified Aluminum Alkoxides, Ertuğrul Arpaç, Efraim Avşar
Hydrolysis And Condensation Reactions Of Methacrylate-Modified Aluminum Alkoxides, Ertuğrul Arpaç, Efraim Avşar
Turkish Journal of Chemistry
The hydrolysis of aluminum tri-sec-butoxide and compounds obtained by substituting the larger functional groups for the present alkly groups in Al(O-sec-Bu)_3, and the reaction of these products with a polymerizable organic ligand, i.e. methacrylic acid, were studied together with the hydrolysis reactions of the final products. A good method of preparing high-tech materials and new composites uses organo-substituted silicon esters and/or alkoxides of various elements in a polycondensation process. Introducing a suitable organic network into the inorganic backbone gives desirable properties in new coating materials. The preparation of such materials is possible via the hydrolysis of metal alkoxides. Usually, different …
The Investigation Of Aluminum Sulfate-Potassium Chloride Solid Phase Reaction, İ. Ayhan Şengi̇l
The Investigation Of Aluminum Sulfate-Potassium Chloride Solid Phase Reaction, İ. Ayhan Şengi̇l
Turkish Journal of Chemistry
It was found that aluminum sulfate reacts with potassium chloride to produce K_{2}SO_{4}, Al_{2}O_{3}, and Cl_{2} in the solid phase at 700 ^{\circ}C. This reaction was investigated with thermal analysis under air and nitrogen atmosphere. By changing temperature and time parameters, the actual yield of conversion in question was examined analytically and the optimum temperature and time were found for the reaction. The rate expression of the solid phase reaction was also investigated and the rate equation was obtained.
Analysis Of Retention In Supercritical Fluid Chromatography And Its Relation To Solubility, Z. Şermin Gönenç, Uğur Akman, Aydın K. Sunol
Analysis Of Retention In Supercritical Fluid Chromatography And Its Relation To Solubility, Z. Şermin Gönenç, Uğur Akman, Aydın K. Sunol
Turkish Journal of Chemistry
The effects of temperature, pressure and supercritical fluid density on the solubility-retention relationship of solutes in supercritical fluid chromatography are investigated. New retention data for naphthalene, phenanthrene, benzoic acid and 2-methoxy-naphthalene is obtained as a function of pressure at different temperatures. The bulk of the data is taken near the critical region of the mobile gas where the anomalities are expected. This data is used to compare two approaches for thermodynamic modeling of pressure dependence of solute retention. In these approaches, mobile-phase partial molar volumes of the solutes are determined either from bulk solubility data or from infinite-dilution fugacity coefficients. …
Quantum-Chemical Investigations On The Functionalized 1h-Pyrimidines, İsmail Yildirim, Makbule Tezcan, Yahya Güzel, Emin Saripinar, Yunus Akçamur
Quantum-Chemical Investigations On The Functionalized 1h-Pyrimidines, İsmail Yildirim, Makbule Tezcan, Yahya Güzel, Emin Saripinar, Yunus Akçamur
Turkish Journal of Chemistry
Conformational analysis and quantum-chemical calculations were carried out by means of the methods MMP2 and SCF MO LCAO in the CNDO/2 and MNDO approximation for the series of compounds being functionalized 1H- pyrimidines. The analysis of the electron density distribution depending on the substituents' nature was done on the basis of the data obtained.
Investigation Of Acid Sites On V_{2}O_{5}/Tio_{2}(A) Catalysts By Ftir With Adsorption Of Pyridine, Ahmet Akbaş, Holger Mi̇tzel, Dieter Höni̇ce
Investigation Of Acid Sites On V_{2}O_{5}/Tio_{2}(A) Catalysts By Ftir With Adsorption Of Pyridine, Ahmet Akbaş, Holger Mi̇tzel, Dieter Höni̇ce
Turkish Journal of Chemistry
The V_{2}O_{5}/TiO_{2}(A) catalysts were prepared by the grafting and their Br\"{o}nsted and Lewis acid sites were investigated with pyridine adsorption by using FTIR Spectroscopy. The results obtained showed that monolayer or less coverage of the surface of the support, TiO_{2}(A), took place up to V_{2}O_{5} content of 11.88 \%. When V_{2}O_{5} amount was higher then 11.88 \%, the support was covered as multilayer. Pyridine adsorption studies showed that the number of the Lewis acid sites of the V_{2}O_{5}/TiO_{2}(A) catalysts decreased with increasing of V_{2} O_{5} amount. The number of the Br\"{o}nsted acid sites increased with increasing V_{2}O_{5} content, reached a …