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Articles 29041 - 29070 of 34711

Full-Text Articles in Physical Sciences and Mathematics

The Attempted Synthesis Of A Phenolphthalein-Capped Beta-Cyclodextrin, Susan Elizabeth Miller Jan 2000

The Attempted Synthesis Of A Phenolphthalein-Capped Beta-Cyclodextrin, Susan Elizabeth Miller

Dissertations, Theses, and Masters Projects

No abstract provided.

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A Computational Approach To Determining Stability Constants For Transition Metal Ion Complexes, Jason St. Clair Jan 2000

A Computational Approach To Determining Stability Constants For Transition Metal Ion Complexes, Jason St. Clair

Honors Theses

The complexation of metal ions in natural waters plays a critical role in defining the metal's biogeochemistry, Numerous investigators have used various experimental techniques to measure complexation constants in the laboratory, but many constants are still poorly undefined or have yet to be investigated due to the difficulty of some of the experiments. A computational approach to obtaining these constants for complexes of Fe(lII), Fe(D), Cr(lli), Cu(lI), Zn(II), and Cd(II) was explored with varying degrees of success. Calculated Gibbs Free Energies were compared to experimental stability constants. Calculations were performed using Spartan's DFT package at the pEP level and with …

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Adsorption Of Some Heavy Metal Ions From Aqueous Solution By Activated Carbon And Comparison Of Percent Adsorption Results Of Activated Carbon With Those Of Some Other Adsorbents, İlhan Uzun, Fuat Güzel Jan 2000

Adsorption Of Some Heavy Metal Ions From Aqueous Solution By Activated Carbon And Comparison Of Percent Adsorption Results Of Activated Carbon With Those Of Some Other Adsorbents, İlhan Uzun, Fuat Güzel

Turkish Journal of Chemistry

In this study, removal of some heavy metals ions (Mn^{2+}, Fe^{2+}, Ni^{2+} and Cu^{2+}) from aqueous solution by adsorption was investigated. For this purpose, high-grade MnSO_4.H_2O, FeSO_4.7H_2O, NiSO_4.7H_2O and CuSO_4.5H_2O were used as heavy metal samples. The commercial activated carbon (Merck 2514), chitosan and agar were used as adsorbents. The pH of each solution was not controlled. This is because the net interaction between the adsorbent and the heavy metal could be disturbed by the buffer solution. Therefore, all experiments were carried out in a pH range from 5.3 to 5.5. The equilibrium adsorption contact times were determined for M …

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Determination Of Nizatidine-Guest Complexation Constants And Computer Aided Molecular Design, Carolyn J. Mordas Jan 2000

Determination Of Nizatidine-Guest Complexation Constants And Computer Aided Molecular Design, Carolyn J. Mordas

Honors Theses

Nizatidine, N-[2-[[[2-[(dimethylamino)methyl]-4-thiazoly]]methy1]thio]ethyl]-N'- methyl- 2-nitro-I,l, ethenediamine, has been investigated for its potential to act as a host to small molecules through hydrogen bonding and pi-pi interactions. In previous work, pyridoxine (vitamin B6) was hypothesized to have a high guest-host binding constant with nizatidine. This was supported through experimental methods involving one and two dimensional NMR spectroscopy, UV-visible spectroscopy, and high performance liquid chromatography. Computer aided molecular design and three dimensional conformationally flexible database searching led to the discovery of other possible guests, including albuterol, which has exhibited even higher binding constants from HPLC.

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Study Of The Amplitude Of Pressure And Thrust Oscillations In A Lab-Scale Hybrid Rocket, Ann Wright, Lawrence Dunn, Brian Alford, Justin Patton, M. Keith Hudson Jan 2000

Study Of The Amplitude Of Pressure And Thrust Oscillations In A Lab-Scale Hybrid Rocket, Ann Wright, Lawrence Dunn, Brian Alford, Justin Patton, M. Keith Hudson

Journal of the Arkansas Academy of Science

Hybrid rockets are being studied as a potential replacement for the solid rocket boosters on the NASA space shuttle. One physical characteristic of hybrid rockets that must be understood and overcome is potentially severe pressure oscillations during combustion. Pressure oscillations inside the rocket combustion chamber lead to oscillations in the thrust of the rocket. These oscillations are damaging to potential human passengers and cargo and must be minimized. Current theories surmise that the oscillations are caused by combustion chamber geometry, oxygen feed line parameters, and/or fuel combustion characteristics. This study focuses on the role of the fuel characteristics in pressure …

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Studies Directed At The Synthesis Of Trialkoxysilyl Substituted Nlo Chromophores, Ida J. Kuhr Jan 2000

Studies Directed At The Synthesis Of Trialkoxysilyl Substituted Nlo Chromophores, Ida J. Kuhr

Browse all Theses and Dissertations

The synthesis of trialkoxyalkyl substituted NLO chromophores has been investigated. The chromophore 2-(7-(3-hydroxydiphenylamino)-9,9-diethyl-2-fluorenyl)-benzothiazole was prepared by a five step process. Bromination of fluorene yielded 2,7-dibromo-fluorene which could be converted to 2,7-dibromo-9,9-diethylfluorene by alkylation with ethyl iodide in DMSO.Reaction of 2,7-dibromo-9,9-diethylfluorene with one equivalent of butyl lithium followed by reaction with DMF provides 2-bromo-7-formyl-9,9-diethylfluorene. Condensation of 2-bromo-7-formyl-9,9-diethylfluorene and 2-aminobenzenethiol in DMSO results in the formation of 2-(7-bromo-9,9-diethyl-2-fluorenyl)benzothiazole. The conversion of 3-hydroxydiphenylamine to 3-benzyloxy-diphenylamine was accomplished with benzyl bromide and potassium carbonate in DMF. A palladium catalyzed coupling of 3-benzyloxydiphenylamine and 2-(7-bromo-9,9-diethyl-2-fluorenyl)benzothiazole provided 2-(7-(3-hydroxydiphenyl-amino)-9,9-diethyl-2-fluorenyl)benzothiazole. Several attempts to alkylate 2-(7-(3-hydroxydiphenylamino)-9,9-diethyl-2-fluorenyl)benzothiazole with trimethoxysilylmethyl chloride …

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(N2o)2⋅So2: Rotational Spectrum And Structure Of The First Van Der Waals Trimer Containing Sulfur Dioxide, Rebecca A. Peebles, Robert L. Kuczkowski Jan 2000

(N2o)2⋅So2: Rotational Spectrum And Structure Of The First Van Der Waals Trimer Containing Sulfur Dioxide, Rebecca A. Peebles, Robert L. Kuczkowski

Rebecca A. Peebles

No abstract provided.

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Cross-Linking Of Polystyrene By Friedel-Crafts Chemistry: Multi-Functional Additives, Hongyang Yao, Jin Zhu, Michael A. Mckinney, Charles A. Wilkie Jan 2000

Cross-Linking Of Polystyrene By Friedel-Crafts Chemistry: Multi-Functional Additives, Hongyang Yao, Jin Zhu, Michael A. Mckinney, Charles A. Wilkie

Chemistry Faculty Research and Publications

Various multifunctional aromatic compounds were synthesized and tested to ascertain if they were able to cross-link polystyrene. Catalysis and inhibition at high temperature were studied to achieve control over the cross-linking temperature, in order to develop suitable formulations which may function as flame retardants.

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On The Stabilizing Action Of Protein Denaturants: Acetonitrile Effect On Stability Of Lysozyme In Aqueous Solutions, Evgueni Kovriguine, Sergey A. Potekhin Jan 2000

On The Stabilizing Action Of Protein Denaturants: Acetonitrile Effect On Stability Of Lysozyme In Aqueous Solutions, Evgueni Kovriguine, Sergey A. Potekhin

Chemistry Faculty Research and Publications

Stability of hen lysozyme in the presence of acetonitrile (MeCN) at different pH values of the medium was studied by scanning microcalorimetry with a special emphasis on determination of reliable values of the denaturational heat capacity change. It was found that the temperature of denaturation decreases on addition of MeCN. However, the free energy extrapolation showed that below room temperature the thermodynamic stability increases at low concentrations of MeCN in spite of the general destabilizing effect at higher concentrations and temperatures. Charge-induced contribution to this stabilization was shown to be negligible (no pH-dependence was found); therefore, the most probable cause …

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Novel (Heteromolecular) Π-Complexes Of Aromatic Cation Radicals. Isolation And Structural Characterization, P. Le Maguères, Sergey V. Lindeman, Jay K. Kochi Jan 2000

Novel (Heteromolecular) Π-Complexes Of Aromatic Cation Radicals. Isolation And Structural Characterization, P. Le Maguères, Sergey V. Lindeman, Jay K. Kochi

Chemistry Faculty Research and Publications

Extensive (electron) delocalization in the novel heteromolecular π-complex of the hindered naphthalene cation radical (OMN+•) with naphthalene (NAP) accompanies the pronounced charge-transfer absorption band at ∼1100 nm in the near-IR. X-ray crystallography establishes the viability of the unusual “club sandwich” structure despite the repulsive electrostatic forces inherent to the dicationic unit.

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A Study On N-Hydroxyamide Ethoxycarbonylhydrazones, A. Aykut İki̇zler, Ahmet Demi̇rbaş, Rza Abbasoğlu Jan 2000

A Study On N-Hydroxyamide Ethoxycarbonylhydrazones, A. Aykut İki̇zler, Ahmet Demi̇rbaş, Rza Abbasoğlu

Turkish Journal of Chemistry

The structures and electronic properties of N-hydroxyamide ethoxycarbonylhydrazones were investigated by a quantum-chemical method AMl. The total energies, heats of formation, dipol moments, ionization potentials, proton affinities and energies of frontier molecular orbitals (E_{HOMO} and E_{LUMO}) were calculated and discussed. The stabilities of the tautomeric forms and of E and Z isomers for these compounds were determined. The complex forming ability of these compounds with metal cations was also studied. The geometry and electronic properties of the complexes formed by N-hydroxyacetamide ethoxycarbonylhydrazone with Ni^{2+} and Cu^{2+} were investigated using ZINDO/1 semiempirical method. Moreover, these complexes were synthesized and identified.

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The Measurement Of Surface Areas Of Some Silicates By Solution Adsorption, Oğuz İnel, Fatma Tümsek Jan 2000

The Measurement Of Surface Areas Of Some Silicates By Solution Adsorption, Oğuz İnel, Fatma Tümsek

Turkish Journal of Chemistry

In this study, the adsorption from solution technique was used for the determination of surface areas of some silicate samples (bentonite, sepiolite, zeolitic tuff and kaolin). Methylene blue (MB), orthophenanthroline (OP) and p-nitrophenol (PNP) were selected as solutes. The adsorption data was found to conform with the Langmuir equation within the concentration range studied, and Langmuir constants were determined for each of the samples. The surface area values obtained were compared with those determined by nitrogen adsorption. Also the results were discussed with respect to the cation exchange capacities of the samples. The specific surface area values of the samples …

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Properties Of Electrodeposited Cadmium Sulfide Films For Photovoltaic Devices With Comparison To Cds Films Prepared By Other Methods, Fi̇gen Kadirgan, Duli Mao, Wenjie Song, Tim Ohno, Brian Mccandless Jan 2000

Properties Of Electrodeposited Cadmium Sulfide Films For Photovoltaic Devices With Comparison To Cds Films Prepared By Other Methods, Fi̇gen Kadirgan, Duli Mao, Wenjie Song, Tim Ohno, Brian Mccandless

Turkish Journal of Chemistry

Films of CdS for photovoltaic devices were electrochemically deposited on tin oxide coated glass substrates at different conditions. The films were found to be smooth and uniform with a small grain size. X-ray diffraction measurement and analysis indicated a hexagonal phase rather than the cubic phase. The surface composition of the films was investigated by Auger Spectroscopy. Electrochemical deposition parameters were studied to obtain the optimum conditions for the best CdS films. Our films are compared from the pinhole number and particulate point of view with the films prepared by other methods.

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Fundamental Noise Studies In Flame Atomic Magneto-Optic Rotation And Atomic Absorption Spectrometry, Ahmet T. İnce, Richard D. Snook, Jhon B. Dawson Jan 2000

Fundamental Noise Studies In Flame Atomic Magneto-Optic Rotation And Atomic Absorption Spectrometry, Ahmet T. İnce, Richard D. Snook, Jhon B. Dawson

Turkish Journal of Chemistry

A study of inherent noise sources present in a purpose built flame atomic magneto-optic rotation (AMOR) spectrometer system was carried out with a view to identifying their sources. Two different optical configurations were employed, a crossed polariser and a 45° offset polariser configuration. The offset polariser configuration was operated in both an AMOR and atomic absorption (AA) mode for the noise measurements. Two main interference frequencies were found to occur in all the optical measurement modes. An interference flame feature frequency (15.5 Hz -39.0 Hz) which arose from an ``organ-pipe'' effect in the gas flow through the flame cooling sheets. …

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Synthesis And Reactivity Of Some Mannich Bases. Vi. New Arylamine Mannich Bases Derived From 2-Hydroxy-5-Methylacetophenone, Gheorghe Roman, Diana Nanu, Eugenia Comanita, Bogdan Comanita Jan 2000

Synthesis And Reactivity Of Some Mannich Bases. Vi. New Arylamine Mannich Bases Derived From 2-Hydroxy-5-Methylacetophenone, Gheorghe Roman, Diana Nanu, Eugenia Comanita, Bogdan Comanita

Turkish Journal of Chemistry

The amine exchange reaction has been applied for obtaining a new series of arylamine Mannich bases from variously substituted aromatic amines and 3-(dimethylamino)-1-(2'-hydroxy-5'-methylphenyl) propan-1-one. The structures of the newly synthesised Mannich bases have been investigated by IR, ^1H- and ^{13}C-NMR and shown to be in good agreement with the proposed ones.

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Studies On The Methylation Of 5-Nitro-Benzimidazoles, Mashooda Hasan, Farzana Shaheen, Uzma Yunus Jan 2000

Studies On The Methylation Of 5-Nitro-Benzimidazoles, Mashooda Hasan, Farzana Shaheen, Uzma Yunus

Turkish Journal of Chemistry

Methylation of 2H, 5-nitro- (1) and 2-ethyl, 5-nitro- (2) benzimidazoles separately with methyl iodide in acetone in the presence of potassium carbonate yielded 2H, 5/6-nitro-(3A and 3B) and 2-ethyl, 5/6-nitro- (4A and 4B) methylbenzimidazoles respectively. Methylation of 1 and 2 in dimethylformamide in place of acetone yielded not only 3A, 3B and 4A, 4B respectively, but in addition 1,3-dimethyl-5-nitro-benzimidazol-2-one (5) was also obtained in each case. The structure of the synthesized compounds was determined with the help of mass and ^1H NMR spectroscopic analysis.

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Synthesis Of 4-Benzyl-1-Piperazineglyoxime And Its Use In The Spectrophotometric Determination Of Nickel, Mustafa Maci̇t, Hümeyra Bati, Beki̇r Bati Jan 2000

Synthesis Of 4-Benzyl-1-Piperazineglyoxime And Its Use In The Spectrophotometric Determination Of Nickel, Mustafa Maci̇t, Hümeyra Bati, Beki̇r Bati

Turkish Journal of Chemistry

A new reagent, 4-benzyl-1-piperazineglyoxime(BPGH_2), was synthesized and used for developing a simple and rapid extractive method for the spectrophotometric determination of nickel. This method is based on the selective extraction of nickel complex from aqueous solution into carbontetrachloride and the measurement of the absorption at 267 nm. The method was applied to the determination of nickel ion in some standard and practical samples.

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Determination Of Thermodynamic Parameters Of Some Complexes Of 9-Ethyl-3-Carbazolecarboxaldehyde 4-Phenyl-3-Thiosemicarbazone (Eccapt), E. Güler Akgemci̇, Tevfi̇k Atalay Jan 2000

Determination Of Thermodynamic Parameters Of Some Complexes Of 9-Ethyl-3-Carbazolecarboxaldehyde 4-Phenyl-3-Thiosemicarbazone (Eccapt), E. Güler Akgemci̇, Tevfi̇k Atalay

Turkish Journal of Chemistry

The complexes of Cu(II), Co(II), Zn(II), and Cd(II) with 9-ethyl-3-carbazolecarboxaldehyde 4-phenyl-3-thiosemicarbazone were synthesized and their stability constants were determined using a spectrophotometric method at different temperatures (25, 30, 35 and 40 \pm 0.1°C) and ionic strengths (0.05, 0.01 and 0.20 M KNO_3) in 50% (v/v) aqueous DMF. From these constants, the thermodynamic stability constants and thermodynamic parameters (\Delta G°, \Delta H° and \Delta S°) were calculated.

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The Synthesis Of Manganese(Iii) Acetate In Bipolar Packed-Bed And Trickle-Bed Electrode Cells, Altan Güvenç, Belgi̇n Karabacakoğlu, Ö. Mete Koçkar, A. Tarik Pekel Jan 2000

The Synthesis Of Manganese(Iii) Acetate In Bipolar Packed-Bed And Trickle-Bed Electrode Cells, Altan Güvenç, Belgi̇n Karabacakoğlu, Ö. Mete Koçkar, A. Tarik Pekel

Turkish Journal of Chemistry

In this research, the electrochemical oxidation of Mn(II) acetate to Mn(III) acetate was investigated in aqueous acetic acid solution, using a bipolar particulate electrode cell. In order to determine the effect of flow modes on the yield of Mn(III) acetate, which is an important oxidizing agent and catalyst in organic reactions, a bipolar particulate electrode cell was employed both in flooded and trickle flow modes. The experiments were conducted at controlled potentials of 50-250 volts using the solution (10% H_2O, 90% CH_3COOH, 0.1 M Mn(CH_3COO)_2.4H_2O, 0.1 M CH_3COONa.3H_2O) and at an optimum flow rate of 0.04 ml.s^{-1}. The values of …

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Some Properties Of Cu, Zn-Superoxide Dismutase From Sheep Erythrocyte, Leman Tarhan, M. Nalan Tüzmen Jan 2000

Some Properties Of Cu, Zn-Superoxide Dismutase From Sheep Erythrocyte, Leman Tarhan, M. Nalan Tüzmen

Turkish Journal of Chemistry

Superoxide dismutase (SOD) was isolated from sheep erythrocyte. SOD activity was measured under the optimized assay conditions by observing the variations of autoxidation rate of 6-hydroxydopamine (6-OHDA). The enzyme was characterized as containing copper and zinc and was insensitive to chloroform-ethanol mixture but inhibited by cyanide and hydrogen peroxide. The activity variations and stability properties of sheep erythrocyte Cu, Zn-SOD were investigated under the optimized activity assay conditions by observing inhibition change at the autoxidation rate of 6-OHDA. The optimum pH and temperature of sheep erythrocyte Cu, Zn-SOD were found to be 9.4 and 30$^{\circ}$C respectively. The enzyme showed high …

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Magnitudes Of Back Diffusion During Long-Term Diffusive Sampling Of Volatile Organic Compounds Using Carbotrap And Chromosorb 106, Naci̇ye Kiliç, James A. Ballantine Jan 2000

Magnitudes Of Back Diffusion During Long-Term Diffusive Sampling Of Volatile Organic Compounds Using Carbotrap And Chromosorb 106, Naci̇ye Kiliç, James A. Ballantine

Turkish Journal of Chemistry

The aim of the research was to investigate the magnitudes of the losses of some volatile organic compounds from the solid adsorbents, Carbotrap and Chromosorb 106 due to back diffusion during long-term diffusive sampling of volatile organic compounds in the environment. Experiments were performed by loading the compounds to be tested on the adsorbent tubes and leaving them in an outdoor environment to simulate the real life sampling conditions over a 14 day period. The losses due to back diffusion were investigated for both the high and the low initial concentrations of the fourteen compounds covering a wide range of …

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Swelling Behavior Of Acrylamide-2-Hydroxyethyl Methacrylate Hydrogels, Belma Işik Yürüksoy Jan 2000

Swelling Behavior Of Acrylamide-2-Hydroxyethyl Methacrylate Hydrogels, Belma Işik Yürüksoy

Turkish Journal of Chemistry

In this study, hydrogels of poly(acrylamide-co-2-hydroxyethyl methacrylate) having different properties were prepared by a redox polymerization method. Poly(ethylene glycol), PEG 4000 was included in the polymerization recipe to increase the microporosity of the resultant polymeric structures. AAm/HEMA hydrogels with different properties were obtained by changing initial AAm/HEMA mole ratio, total monomer, PEG 4000 and crosslinker concentrations.

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Solvent Extraction Of Fe^{3+} Cation By Diazo-Coupling Calix[4]Arenes, Hasaletti̇n Deli̇göz, Emi̇n Erdem, Hasan Kocaokutgen Jan 2000

Solvent Extraction Of Fe^{3+} Cation By Diazo-Coupling Calix[4]Arenes, Hasaletti̇n Deli̇göz, Emi̇n Erdem, Hasan Kocaokutgen

Turkish Journal of Chemistry

The solvent extraction of Fe^{3+} cations from the aqueous to the organic (chloroform) phase was carried out using p-tert-butyl calix[4]arene(\underline{1}), calix[4]arene(\underline{2}), diazo-coupling calix[4]arenes [p-(4-n-butyl-phenylazo)calix[4]arene (\underline{3}), p-(4-phenylazophenylazo)calix[4]arene(\underline{4}), p-(4-acetanilidazo)calix[4]arene(\underline{5}), p-(N'-2-thyazol-2ylsulphanylazo)calix[4]arene(\underline{6}) and p-(2-thyazolazo)calix[4]arene(\underline{8}) and the derivatives of phenol [2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(\underline{8}) (Bromo-PADAP) and 2-hydroxy-5-methyl\-phenylazonapthol(\underline{9}) (HMPAN)]. It was found that the compounds (\underline{1}-\underline{9}) showed the highest extractability toward Fe^{3+} at pH 4.5-5.4 Compound \underline{5} shows strong binding ability to Fe^{3+} ion. Based on the method of continuous variation, calixarene \underline{5} formed a 1:1 complex with Fe^{3+} ion.

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X-Ray Diffraction Study Of Heat-Treated Graphitized And Ungraphitized Carbon, Rizwan Hussain, Riaz Qadeer, Mahmood Ahmad, M. Saleem Jan 2000

X-Ray Diffraction Study Of Heat-Treated Graphitized And Ungraphitized Carbon, Rizwan Hussain, Riaz Qadeer, Mahmood Ahmad, M. Saleem

Turkish Journal of Chemistry

Heat treatment of graphitized and ungraphitized carbon samples was carried out in air and argon atmosphere from ambient temperature to 700$^{\circ}$C. The changes in degree of amorphousness, mean crystallite size and interlayer separations were studied employing x-ray diffraction. The results revealed an increase in crystallinity when graphitized carbon was heated to 100 ^oC and above. This enhanced degree of arrangement is indicative of the removal of residual impurities entrapped during the production processes. In ungraphitized carbon, the transition from amorphous to crystalline character was not observed upon heat treatment.

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Stereoselective Synthesis Of Butenolide And Butyrolactone Derivatives, Abdulkadi̇r Sirit Jan 2000

Stereoselective Synthesis Of Butenolide And Butyrolactone Derivatives, Abdulkadi̇r Sirit

Turkish Journal of Chemistry

Optically active butenolide and $\gamma$-butyrolactone derivatives were prepared by removing (R)-phenyl glycinol and (1R, 2R)-norpseudoephedrine used as chiral auxiliaries from butenolides and \gamma-butyrolactones in two steps. The structures of these products were determined using ^1H NMR, ^{13}C NMR, Mass spect., IR and microanalysis.

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High Fluorescence Emissions Of Some Natural Benzofurane Derivatives Isolated From Styrax Officinalis, Siddik İçli̇, Hüseyi̇n Anil, Bi̇rcan Di̇ndar, Özgen Alankuş Çalişkan, Yurdanur Yayla, Andrey O. Doroshenko, Serap Alp Jan 2000

High Fluorescence Emissions Of Some Natural Benzofurane Derivatives Isolated From Styrax Officinalis, Siddik İçli̇, Hüseyi̇n Anil, Bi̇rcan Di̇ndar, Özgen Alankuş Çalişkan, Yurdanur Yayla, Andrey O. Doroshenko, Serap Alp

Turkish Journal of Chemistry

The fluorescent properties of several natural benzofuran derivatives, egonols, isolated from {\it Styrax officinalis}, were determined. The studied egonol derivatives were found to be effective UV organic luminophores, with quantum yields of near to unity, \( \varphi_{f} \) = 0.92. The fluorescence quenching experiments with electron donor molecules of aniline, N,N-dimethylaniline and carbazolocarbazole, presented very high efficiency of quenching at above diffusion quenching rates of 4.5$\times$10\( ^{10} \), 2.1$\times$10\( ^\times \) and 5.6$\times$10\( ^{12} \) s\( ^{-1} \)mol\( ^{-1} \), respectively. A strong electron acceptor molecule, tetranitrofluorenone, presented quenching rate of 2.6$\times$10\( ^{11} \) s\( ^{-1} \)mol\( ^{-1} \). It …

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Heavy Metal Removal From Aquatic Systems By Northern Anatolian Smectites, Çi̇ğdem Arpa, Ridvan Say, Nuray Şatiroğlu, Sema Bektaş, Yuda Yürüm, Ömer Genç Jan 2000

Heavy Metal Removal From Aquatic Systems By Northern Anatolian Smectites, Çi̇ğdem Arpa, Ridvan Say, Nuray Şatiroğlu, Sema Bektaş, Yuda Yürüm, Ömer Genç

Turkish Journal of Chemistry

Competitive adsorption of the heavy metal ions Cu(II), Cd(II) and Pb(II) from aqueous media onto northern Anatolian smectites with a mean particle diameter of 200 $\mu$m, was investigated. The adsorption rate and capacity of the smectite for the selected heavy metal ions, containing different amounts of these ions (5-900 mg/L) at values ranging from pH 1.0 to 7.0 were studied. Very high adsorptions rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 30 minutes. The maximum adsorption of metal ions onto the smectite were found to be 41.46 mg Cd(II), 36.11 mg Pb(II) and …

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The Effect Of Peripheral Circuits On The Total \Pi-Electron Energies Of Cyclacenes, Lemi̇ Türker Jan 2000

The Effect Of Peripheral Circuits On The Total \Pi-Electron Energies Of Cyclacenes, Lemi̇ Türker

Turkish Journal of Chemistry

Within the framework of the Hückel molecular orbital theory, certain linear models are developed to express the contribution of peripheral circuits of cyclacenes into their total \pi-electron energies, which explain why cyclacenes exhibit the cryptoannulenic behavior as their peripheral circuits which are annulenic in character.

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Spectroscopic Studies Of Charge-Transfer Complexes Of 2,3-Dichloro-5,6-Dicyano-P-Benzo-Quinone, M. S. Subhani̇, N. K. Bhatti̇, M. Mohammad, A. Y. Khan Jan 2000

Spectroscopic Studies Of Charge-Transfer Complexes Of 2,3-Dichloro-5,6-Dicyano-P-Benzo-Quinone, M. S. Subhani̇, N. K. Bhatti̇, M. Mohammad, A. Y. Khan

Turkish Journal of Chemistry

Charge-transfer complexes of 2,3-dichloro-5, 6-dicyano-p-benzoquinone (DDQ) p-acetotoluidide, acetanilid, biphenyl and naphthalene were studied and their absorption spectra in solution were recorded. Absorption spectral data were obtained in CH_2Cl_2, CHCl_3, CCl_4 and mixture (CH_2Cl_2 + V) at different temperatures. Two charge-transfer bands were observed in each case. Spectral characterization of these complexes was determined and correlated with the ionization potential of the donor. Variation in thermodynamic parameters were also found to be due to change in donor and solvent.

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Atmospheric Deposition Of Pb, Zn, Cu, And Cd In Amman, Jordan, Kamal A. Momani, Anwar G. Jiries, Qasem M. Jaradat Jan 2000

Atmospheric Deposition Of Pb, Zn, Cu, And Cd In Amman, Jordan, Kamal A. Momani, Anwar G. Jiries, Qasem M. Jaradat

Turkish Journal of Chemistry

Atmospheric samples were collected using a low-volume air sampler and dustfall containers during the summer of 1995 at different sites in the city of Amman, Jordan. The heavy metal contents in settleable particles (dustfall) as well as in air particulates (suspended) were analyzed by graphite furnace atomic absorbation spectrophotometry. The atmospheric concentrations of Zn, Cu, Pb, and Cd were 344, 170, 291, and 3.8 ng/m$^3$, respectively. The levels of these elements in the dustfall deposition were 505, 94, 74 and 3.1 $\mu$g/g, respectively. The fluxes and dry deposition velocities of these heavy metals were determined and compared with the findings …

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