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Full-Text Articles in Physical Sciences and Mathematics
Isothermal Compressibility And Isobaric Thermal Shrinkage Of A Porous $\Alpha$-Alumina Compact: Thermodynamic Calculations, Yüksel Sarikaya, Müşerref Önal, Abdullah Devri̇m Pekdemi̇r
Isothermal Compressibility And Isobaric Thermal Shrinkage Of A Porous $\Alpha$-Alumina Compact: Thermodynamic Calculations, Yüksel Sarikaya, Müşerref Önal, Abdullah Devri̇m Pekdemi̇r
Turkish Journal of Chemistry
Two methods were proposed to calculate the thermodynamic parameters of porous ceramic compacts depending on their molar volume change with applied pressure and heating temperature, respectively. Molar volume of the porous $\alpha $-alumina ($\alpha $-Al$_{2}$O$_{3})$ compact was evaluated according to literature depending on both the applied pressure at room temperature and the heating temperature at atmospheric pressure. The isothermal compressibility coefficient, Gibbs energy, and work done on the compact by compression were calculated. The thermal shrinkage coefficient and activation energy as well as the change in enthalpy, entropy and Gibbs energy were calculated for partial sintering. The spontaneous nature of …
Influence Of Leachate On The Oligocene-Miocene Clays Of The İstanbul Area, Turkey, Sadik Öztoprak, Davut Laçi̇n
Influence Of Leachate On The Oligocene-Miocene Clays Of The İstanbul Area, Turkey, Sadik Öztoprak, Davut Laçi̇n
Turkish Journal of Earth Sciences
Oligo-Miocene clay outcrops on the European side (west and northwest part) of İstanbul were analysed. Formerly, a landfill and sanitary landfill were built on the clay. Mineral liners of the current and extending parts of the İstanbul landfill consist of these clays, since they include a considerable amount of smectite, illite, and kaolinite. With this feature, these clays are also an important candidate for the buffer material of repositories for nuclear wastes of newly planned nuclear power plants. In this context, one Miocene and two Oligocene clay samples were subjected to leachate under low stress using an odometer device during …
Investigation Of The Adsorption Kinetics Of Methylene Blue Onto Cotton Wastes, Bi̇lal Acemi̇oğlu, Murat Ertaş, Mehmet Hakki Alma, Mustafa Usta
Investigation Of The Adsorption Kinetics Of Methylene Blue Onto Cotton Wastes, Bi̇lal Acemi̇oğlu, Murat Ertaş, Mehmet Hakki Alma, Mustafa Usta
Turkish Journal of Chemistry
Cotton stalk (CS), cotton waste (CW), and cotton dust (CD), which are cotton wastes, were used as adsorbents to study the adsorption kinetics of methylene blue from aqueous solution. Kinetics of the batch adsorption experiment was investigated according to the pseudo-first order, the pseudo-second order, and the intraparticle diffusion models used commonly in the literature. The effects of the initial concentration, solution pH, and temperature on kinetic parameters (adsorption rate constant, initial adsorption rate, equilibrium adsorption capacity, etc.) were studied. The results showed that the adsorption process was well fitted to the pseudo-second order model for all adsorbents. The activation …
Structural, Physical, And Electrical Properties Of Boro-Vanadate-Iron Glasses Doped With K_2o Alkali, Harshvadan R. Panchal
Structural, Physical, And Electrical Properties Of Boro-Vanadate-Iron Glasses Doped With K_2o Alkali, Harshvadan R. Panchal
Turkish Journal of Physics
The structural, physical, and electrical properties of semiconducting oxide glasses with composition xK_2O: (95-X) [B_2O_3: 2V_2O_5]: 5Fe_2O_3 (0 \le x \le 30) have been studied. The glasses were prepared by splat-quenching method. Fourier transform infrared spectroscopy (FTIR) studies of these glasses were carried out to study the effect of the modifier and glass former in the glasses. These changes in the molecular structure, bond length, and vibrational group were studied in the spectral range of 400-1350 cm^{-1}. The increase in the intensity and shifting of vibrational bands occurred towards lower wave numbers at 1400-1350 cm^{-1}, 1200 cm^{-1}, and 100-940 cm^{-1}. …
Electrochemistry Of 2,6-Diaminopurine On Multiwall Carbon Nanotube Modified Glassy Carbon Electrode, Ebru Mavi̇oğlu Ayan, Şükri̇ye Karabi̇beroğlu, Zekerya Dursun
Electrochemistry Of 2,6-Diaminopurine On Multiwall Carbon Nanotube Modified Glassy Carbon Electrode, Ebru Mavi̇oğlu Ayan, Şükri̇ye Karabi̇beroğlu, Zekerya Dursun
Turkish Journal of Chemistry
The electrochemical oxidation of 2,6-diaminopurine (2,6-DAP) was studied in pH 7.4 phosphate buffer solution on multiwall carbon nanotube modified glassy carbon electrode (MWCNT/GCE) over a temperature range of 20 to 50 °C using cyclic voltammetry. 2,6-DAP oxidation on MWCNT/GCE showed a well-defined and irreversible oxidation peak at about 0.72 V vs. Ag/AgCl at pH 7.4. The oxidation potential of 2,6-DAP linearly varied with pH over the range of 3.0 to 10.0 with a slope of --0.0547 V/pH, implying that 2 protons were accompanied by 2 electrons transferred in the electrochemical reaction. The activation energy, Ea, of oxidation reaction was found …
Design And Characterization Of Amino And Chloro Functionalized Rhombohedral Silsesquioxanes, Ahmet Gültek, Turgay Seçki̇n, Hali̇l İbrahi̇m Adigüzel
Design And Characterization Of Amino And Chloro Functionalized Rhombohedral Silsesquioxanes, Ahmet Gültek, Turgay Seçki̇n, Hali̇l İbrahi̇m Adigüzel
Turkish Journal of Chemistry
A more rapid and a versatile synthetic approach for the preparation of polyhedral silsesquioxanes (POSS) by hydrolytic condensation of organosilicon monomers in the presence of a Pt catalyst was studied. The structural properties of POSS molecules were determined by X-ray powder diffraction analysis, yielding a rhombohedral unit cell with a = 11,52796Å and \alpha = 94,9754° for octaaminopropyl-POSS, and a rhombohedral unit cell with a = 11,51421Å, \alpha = 96,7214° for octachloropropyl-POSS. The activation energies were found to be 64.8, and 89.1 kJ/mol for octaaminopropyl-POSS and octachloropropyl-POSS, respectively. The products were also characterized by Fourier transform infrared spectroscopy, ^1H and …
Amps-1d Modeling Of A-Si:H N^{+}-I-N^{+} Structure: The Validity Of Space Charge Limited Current Analysis, Aynur Eray, G. Nobile
Amps-1d Modeling Of A-Si:H N^{+}-I-N^{+} Structure: The Validity Of Space Charge Limited Current Analysis, Aynur Eray, G. Nobile
Turkish Journal of Physics
In this paper, the AMPS-1D (Analysis of Microelectronic and photonic structure) simulation program is used to understand the origin of the differences observed in Space Charge Limited Current (SCLC) analysis in thin and thick a-Si:H n^{ +} -i- n^{+} structure. For that purpose, the problem of applicability of SCLC measurements to n^{+}-i-n^{+} a-Si:H samples are investigated by using both the thin (0.3 \mu m) and thick (3 \mu m) samples. The simulation results show that activation energy in thick samples is larger than in thinner samples, which are an agreement with the experimental results. It is emphasized that this method …
Thermochemical And Green Luminescence Analysis Of Zinc Oxide Thin Films Grown On Sapphire By Chemical Vapor Deposition, Abdelkader Djelloul, R. A. Rabadanov
Thermochemical And Green Luminescence Analysis Of Zinc Oxide Thin Films Grown On Sapphire By Chemical Vapor Deposition, Abdelkader Djelloul, R. A. Rabadanov
Turkish Journal of Physics
This study has been carried out to detail an integral thermochemical analysis of the principal reaction in the production of zinc oxide (ZnO) thin films, including developing an analytical form of the equilibrium constant. Zinc oxide thin films prepared by chemical vapor deposition have been studied in terms of deposition time and substrate temperature. The growth of the single-crystal films present two regimes depending on the substrate temperature, with increasing constant growth rates at lower, and higher, temperature ranges, respectively. Growth rates above 6 \mu m \cdot min^{-1} can be achieved at T_s = 880 K. The variation of the …
Evaluation Of Thermal Decomposition Kinetics Of Borax Pentahydrate Using Genetic Algorithm Method By Isothermal Analysis, Ömer Şahi̇n, A. Nusret Bulutcu
Evaluation Of Thermal Decomposition Kinetics Of Borax Pentahydrate Using Genetic Algorithm Method By Isothermal Analysis, Ömer Şahi̇n, A. Nusret Bulutcu
Turkish Journal of Chemistry
The thermal calcination of borax pentahydrate was investigated for both dehydration and decomposition steps at temperatures between 392 and 573 K in a controlled fluidized bed drier. The best kinetic parameters (reaction rate constants, reaction order and equilibrium values) of both steps were determined by the genetic algorithm (GA) method for each calcination temperature in respect of relative standard deviation. The values of the kinetic parameters showed that the dehydration step of borax pentahydrate was controlled by a homogeneous reaction of the order of about 2/3 whereas the decomposition step was controlled by a reaction order of about 1. These …
Kinetics Of Aqueous Pyrite Oxidation By Potassium Dichromate - An Experimental Study, Paul Chirita
Kinetics Of Aqueous Pyrite Oxidation By Potassium Dichromate - An Experimental Study, Paul Chirita
Turkish Journal of Chemistry
The kinetics of pyrite oxidation in perchloric acid solutions were investigated at temperatures ranging from 30°C to 40°C, potassium dichromate concentration from 0.001 to 0.05 mol L^{ - 1}, particle size fractions from 50 to 150 \mu m and pH values down to 2.83. The rate of the oxidation reaction is described by the following expression: r = bkS^{0.51}[K_{2}Cr_{2}O_{7}]^{0.64}[H^{+} ]^{0.22} where S is the surface area of reacting solid, r represents the amount of Fe release in solution per unit surface area per unit time, b is a stoichiometric factor, k is the rate constant, and [K_{2}Cr_{2}O_{7}] and [H^{+} ] …