Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2012

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 18181 - 18210 of 19373

Full-Text Articles in Entire DC Network

Design And Synthesis Of New 1,2,4-Triazole Derivatives Containing Morpholine Moiety As Antimicrobial Agents, Deni̇z Şahi̇n, Hacer Bayrak, Ahmet Demi̇rbaş, Nesli̇han Demi̇rbaş, Şengül Alpay Karaoğlu Jan 2012

Design And Synthesis Of New 1,2,4-Triazole Derivatives Containing Morpholine Moiety As Antimicrobial Agents, Deni̇z Şahi̇n, Hacer Bayrak, Ahmet Demi̇rbaş, Nesli̇han Demi̇rbaş, Şengül Alpay Karaoğlu

Turkish Journal of Chemistry

2-Morpholine-4ylethyl-3H-1,2,4-triazole-3-ones (2a, 2b) were obtained from the condensation between the corresponding ethoxycarbonylhydrazones and 2-morpholinoethanamine. 2a was converted to acetohydrazide (4) via the formation of an ester derivative (3). Treatment of 2a and 2b with several aryl sulfonyl chlorides afforded the corresponding 2-arylsulfonyl-1,2,4-triazole-3-ones (5a-c and 6). The reaction of hydrazide (4) with benzyl iso- and benzyl isothiocyanate produced the corresponding carboxamide (8a) and carbothioamide (8b). The basic treatment of 8b yielded 5-mercapto-4H-1,2,4-triazol-3-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-one (10). The synthesis of 1,3-thiazol-2(3H)-ylidene-1,2,4-triazol-1- ylacetohydrazide (11) and 1,3-oxazole-2(3H)-ylidene-1,2,4-triazole- 1-yl)acetohydrazide (9) derivatives was performed from the reaction of 8a and 8b with substituted phenacyl bromides. All the newly synthesized …

Go to article

Copolymerization Of N-Vinyl Pyrrolidone With Methyl Methacrylate By Ti(Iii)-Dmg Redox Initiator, Ajithkumar Manayan Parambil, Yashoda Malagar Puttaiahgowda, Prasannakumar Shankarappa Jan 2012

Copolymerization Of N-Vinyl Pyrrolidone With Methyl Methacrylate By Ti(Iii)-Dmg Redox Initiator, Ajithkumar Manayan Parambil, Yashoda Malagar Puttaiahgowda, Prasannakumar Shankarappa

Turkish Journal of Chemistry

Redox copolymerization of N-vinyl-2-pyrrolidone (NVP) with methyl methacrylate (MMA) was carried out using titanium(III)-- dimethylglyoxime [Ti(III)-DMG] redox initiator in aqueous sulfuric acid-alcohol media. The resulting copolymer was characterized by FTIR, ^1H-NMR, and ^{13}C-NMR spectroscopic methods and elemental analysis. Thermal properties of the copolymer were determined by differential scanning calorimetric technique and thermogravimetric analysis. The reactivity ratios of the monomers were computed by Fineman-Ross, Kelen-Tudos, and extended Kelen-Tudos methods at lower conversion. The reactivity ratios obtained r_1 (MMA) 1.69 and r_2 (NVP) 0.03 showed richer content of MMA than NVP in the copolymer having extreme ideal behavior. The distribution of monomer …

Go to article

Reaction Kinetics Of Carbon Dioxide With 2-Amino-2-Hydroxymethyl-1,3-Propanediol In Aqueous Solution Obtained From The Stopped Flow Method, Cyril Sunday Ume, Erdoğan Alper Jan 2012

Reaction Kinetics Of Carbon Dioxide With 2-Amino-2-Hydroxymethyl-1,3-Propanediol In Aqueous Solution Obtained From The Stopped Flow Method, Cyril Sunday Ume, Erdoğan Alper

Turkish Journal of Chemistry

Carbon dioxide (CO_2) capture has attracted great interest these days due to the role of CO_2 in global warming and its effects in industrial processes. Thus, higher energy efficient and affordable technologies are required for its removal so as to address these problems. In this work, the reaction kinetics of CO_2 with 2-amino-2-hyroxymethyl- 1,3-propanediol (AHPD), a sterically hindered amine (SHA), was studied by direct stopped flow method. The aim was to research CO_2 absorbent with better CO_2 absorption capacity and reaction kinetics than the commonly applied amine solvents. The study was carried out at 288, 298, and 303 K in …

Go to article

Evaluation Of Thermodynamic Parameters Of Cadmium Adsorption On Sand From Temkin Adsorption Isotherm, Abdul Sattar Ali Khan Jan 2012

Evaluation Of Thermodynamic Parameters Of Cadmium Adsorption On Sand From Temkin Adsorption Isotherm, Abdul Sattar Ali Khan

Turkish Journal of Chemistry

Thermodynamic parameters provide clues for finding the spontaneity of a given process at a given temperature. In the present work, the Temkin adsorption model was applied for evaluation of the thermodynamic parameters of cadmium adsorption studied on sand. The lateral interaction energy parameter was found to be unity, which showed that the heat of adsorption is directly proportional to the fraction of free adsorption sites. The values of \Delta H° and \Delta S° were --4.8 kJ mol^{-1} and 42 J mol^{-1} K^{-1}, respectively. The value of \Delta G° was negative, indicating the spontaneity of cadmium adsorption on sand.

Go to article

The Reaction Of Dialkyl Acetylenedicarboxylates With 2-Oxo-2-Phenylacetaldehyde In The Presence Of Primary Amines: Synthesis Of Alkyl 2-Benzoyl-4-Alkylamino-5-Oxo-2,5-Dihydro-3-Furan Carboxylate Derivatives, Javad Safaei Ghomi, Fariba Salimi, Ali Ramazani, Fatemeh Zeinali Nasrabadi, Yavar Ahmadi Jan 2012

The Reaction Of Dialkyl Acetylenedicarboxylates With 2-Oxo-2-Phenylacetaldehyde In The Presence Of Primary Amines: Synthesis Of Alkyl 2-Benzoyl-4-Alkylamino-5-Oxo-2,5-Dihydro-3-Furan Carboxylate Derivatives, Javad Safaei Ghomi, Fariba Salimi, Ali Ramazani, Fatemeh Zeinali Nasrabadi, Yavar Ahmadi

Turkish Journal of Chemistry

A 3-component domino reaction approach between a primary amine, a dialkyl acetylenedicarboxylate, and 2-oxo-2- phenylacetaldehyde that affords novel alkyl 2-benzoyl-4-alkylamino- 5-oxo-2,5-dihydro-3-furan carboxylate derivatives is reported. The reaction sequence consists of an initial Michael addition of primary amines to dialkyl acetylenedicarboxylates, followed by an aldol-like reaction with 2-oxo-2-phenylacetaldehyde, and then \gamma -lactonization to afford the products. This cascade reaction sequence represents a rapid and unprecedented route to the described biologically interesting molecules.

Go to article

Symmetric, Twinned, And Double-Decker Phthalocyanines Substituted By Trialkylated Pentaerythritol, Muzaffer Köç, Ayşe Gül Gürek, Fabienne Dumoulin, Vefa Ahsen Jan 2012

Symmetric, Twinned, And Double-Decker Phthalocyanines Substituted By Trialkylated Pentaerythritol, Muzaffer Köç, Ayşe Gül Gürek, Fabienne Dumoulin, Vefa Ahsen

Turkish Journal of Chemistry

Trialkylated pentaerythritol was chosen as a bulky substituent for a set of 3 free-base phthalocyanines: a symmetric, a twinned, and a double-decker derivative. The bulkiness of this substituent lowered the aggregation of the phthalocyanines. The electronic absorptions were comparatively investigated: the twinned phthalocyanine exhibited a significant near-infrared shifted absorption. The neutral radical Eu(III) complex was oxidized by bromine. These 3 phthalocyanines are promising for use as molecular materials.

Go to article

A New Absorption Based Co_2 Sensor Based On Schiff Base Doped Ethyl Cellulose, Sevi̇nç Zehra Topal, Kadri̇ye Erteki̇n, Beri̇n Yeni̇gül, Ayşe Erçağ Jan 2012

A New Absorption Based Co_2 Sensor Based On Schiff Base Doped Ethyl Cellulose, Sevi̇nç Zehra Topal, Kadri̇ye Erteki̇n, Beri̇n Yeni̇gül, Ayşe Erçağ

Turkish Journal of Chemistry

This paper reports absorption-based CO_2 sensing of the pH-active Schiff base 2-[(2-hydroxymethylphenylimino) methyl]-5-bromo-phenol (SB) in an ethyl cellulose (EC) matrix with and without Teflon coating. The CO_2 sensitivity of the SB dye in the EC matrix was evaluated in the presence of nonadecafluorodecanoic acid and tetrabutyl ammonium hydroxide. When exposed to CO_2, the sensing films exhibited 76% of overall relative signal change and responded to CO_2 over a wide range: 1%-100 % (v/v). However, the slope of the spectral response between 1% and 5% (v/v) is more significant. The response time (\tau_{90}) was 15 s, and limit of detection (LOD) …

Go to article

Design, Synthesis, And Biological Evaluation Of Indole-Based 1,4-Disubstituted Piperazines As Cytotoxic Agents, Meri̇ç Köksal Akkoç, Mi̇ne Yarim Yüksel, İrem Durmaz, Rengül Çeti̇n Atalay Jan 2012

Design, Synthesis, And Biological Evaluation Of Indole-Based 1,4-Disubstituted Piperazines As Cytotoxic Agents, Meri̇ç Köksal Akkoç, Mi̇ne Yarim Yüksel, İrem Durmaz, Rengül Çeti̇n Atalay

Turkish Journal of Chemistry

A series of 3-[(4-substitutedpiperazin-1-yl)methyl]-1H-indole derivatives were synthesized, and their structures were confirmed by spectral analysis. All the compounds were tested for their cytotoxic activity in vitro against 3 human tumor cell lines: human liver (HUH7), breast (MCF7), and colon (HCT116). Among the designed derivatives, most of the compounds showed significant cytotoxicity against liver and colon cancer cell lines with lower IC_{50} concentrations than the standard drug 5-fluorouracil. Compound 3s, with 3,4-dichlorophenyl substituent on the piperazine ring, was the most active in suppressing the growth of all screened cancer cells.

Go to article

Simultaneous Determination Of Dopamine, Uric Acid, And Tryptophan Using An Mwcnt Modified Carbon Paste Electrode By Square Wave Voltammetry, Hadi Beitollahi, Alireza Mohadesi, Saeedeh Khalilizadeh Mahani, Hassan Karimi Maleh, Ali Akbari Jan 2012

Simultaneous Determination Of Dopamine, Uric Acid, And Tryptophan Using An Mwcnt Modified Carbon Paste Electrode By Square Wave Voltammetry, Hadi Beitollahi, Alireza Mohadesi, Saeedeh Khalilizadeh Mahani, Hassan Karimi Maleh, Ali Akbari

Turkish Journal of Chemistry

A highly sensitive method was investigated for the simultaneous determination of dopamine (DA), uric acid (UA), and tryptophan (TRP) using a multiwall carbon nanotubes/5-amino-3',4'-dimethoxy-biphenyl-2-ol modified carbon paste electrode (5ADMBCNPE). The 5ADMBCNPE displayed excellent electrochemical catalytic activities towards the oxidation of DA, UA, and TRP. The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV), which showed a shift in the oxidation peak potential of DA at 160 mV to a less positive value compared with an unmodified carbon paste electrode. Square wave voltammetry (SWV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed …

Go to article

Titrimetric Determination Of Anionic Surfactant Content In Anionic/Nonionic Surfactant Mixture Solution By Anionic Surfactant Selective Electrode, Junwei Wang, Zhiping Du, Wanxu Wang, Wei Xue Jan 2012

Titrimetric Determination Of Anionic Surfactant Content In Anionic/Nonionic Surfactant Mixture Solution By Anionic Surfactant Selective Electrode, Junwei Wang, Zhiping Du, Wanxu Wang, Wei Xue

Turkish Journal of Chemistry

A new polyvinyl chloride (PVC) membrane electrode for determining the concentration of sodium dodecylsulfate (SDS) based on a neutral ion pair complex of dodecyltrimethylammonium-dodecylsulfate (DTA^+DS^-) as ionophore is described in this paper. The construction and characteristic performance of the PVC membrane electrode displays a Nernstian slope of --56.9 \pm 0.3 mV/decade in the concentration range of 2.0 \times 10^{-6} to 3.2 \times 10^{-3} mol L^{-1} and a detection limit of 1.6 \times 10^{-6} mol L^{-1}. The lifetime of the electrode is more than 3 months without showing significant change in the values of slope or linear concentration range. The electrode …

Go to article

Synthesis And Cytotoxic Evaluation Of Uracil C-Mannich Bases, Hüseyi̇n İstanbullu, Istvan Zupko, Vi̇ldan Alptüzün, Erçi̇n Erci̇yas Jan 2012

Synthesis And Cytotoxic Evaluation Of Uracil C-Mannich Bases, Hüseyi̇n İstanbullu, Istvan Zupko, Vi̇ldan Alptüzün, Erçi̇n Erci̇yas

Turkish Journal of Chemistry

This study covers the design, synthesis, characterization, and cytotoxic activity of a series of uracil C-Mannich bases. Among them, one hybrid compound (1), a molecular combination of the potential antimetabolite substituted uracil and nitrogen mustard, having potential alkylating capability, was prepared as a Mannich base. The other compound was synthesized with the replacement of chlorines in the ethyl chains with hydroxyl groups for testing for anticancer activity. Some of Mannich bases having several amino groups with different pKa values were also synthesized and investigated in terms of cytotoxic activity. Their chemical structures were confirmed by means of their UV, IR, …

Go to article

Determination Of Lidocaine Based On Electrocatalysis Of A Chemically Modified Electrode, Gamze Tan, Gülçi̇n Bolat, Mehmet Ali̇ Onur, Serdar Abaci Jan 2012

Determination Of Lidocaine Based On Electrocatalysis Of A Chemically Modified Electrode, Gamze Tan, Gülçi̇n Bolat, Mehmet Ali̇ Onur, Serdar Abaci

Turkish Journal of Chemistry

The potential application of biochemically modified electrodes was investigated for construction of a drug biosensor. The electrocatalytic response of lidocaine was examined through modified electrodes using the electron transfer ability of hemoglobin (Hb) immobilized on gold film modified with a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA). According to the results of voltammetric studies, Au/MPA/Hb electrodes exhibited high sensitivity and good electrocatalytic activity for the reduction of lidocaine, motivating us to construct drug biosensors. With this study, a new electroanalytical procedure is proposed for the determination of lidocaine level in medical applications or therapeutic formulations containing lidocaine as the active …

Go to article

Facile And Rapid Synthesis Of Some Novel Polysubstituted Imidazoles By Employing Magnetic Fe_3o_4 Nanoparticles As A High Efficient Catalyst, Bahador Karami, Khalil Eskandari, Abdolmohammad Ghasemi Jan 2012

Facile And Rapid Synthesis Of Some Novel Polysubstituted Imidazoles By Employing Magnetic Fe_3o_4 Nanoparticles As A High Efficient Catalyst, Bahador Karami, Khalil Eskandari, Abdolmohammad Ghasemi

Turkish Journal of Chemistry

Multicomponent, one-pot, highly efficient, and environmentally adapted synthesis of some novel polysubstituted imidazoles by the use of various aldehydes, benzil, aliphatic, and aromatic primary amines and ammonium acetate in the presence of Fe_3O_4 nanoparticles as catalyst under solvent-free condition is explained. A highly efficient role of Fe_3O_4 nanoparticles as catalyst in this synthesis was shown. By this advantage, several polysubstituted imidazoles as pharmaceutical important molecules can be prepared in high yield and high purity. This method is very easy and rapid for the synthesis of imidazole derivatives. All products were deduced from their IR and NMR spectroscopic data. The Fe_3O_4 …

Go to article

In Situ Formed 1-Hexyl-3-Methylimidazolium Hexafluorophosphate For Dispersive Liquid-Liquid Microextraction Of Pd(Ii) Prior To Electrothermal Aas And Spectrophotometry, Habibollh Eskandari Jan 2012

In Situ Formed 1-Hexyl-3-Methylimidazolium Hexafluorophosphate For Dispersive Liquid-Liquid Microextraction Of Pd(Ii) Prior To Electrothermal Aas And Spectrophotometry, Habibollh Eskandari

Turkish Journal of Chemistry

1-Hexyl-3-methylimidazolium hexafluorophosphate was prepared in situ and used as extractant in dispersive liquid-liquid microextraction. Ultra-trace amounts of Pd(II) could be accurately determined by electrothermal atomic absorption spectrometry (ETAAS) and spectrophotometry after extraction by the formed micro-droplets of the ionic liquid phase. 1-(2-Pyridylazo)-2-naphthol was used to produce a hydrophobic palladium complex prior to extraction. The effects of concentrations of reagents, reaction and extraction times, and the other parameters were investigated and optimized. Beer's law was obeyed in the ranges of 0.015-0.900 and 1.50-63.0 ng mL^{-1} Pd(II) by ETAAS and spectrophotometry, respectively. Under the optimized conditions, the limit of detection (LOD) by …

Go to article

Determination Of Ultratrace Amounts Of Dichloro-Nitrobenzene And Dichloro-Nitroaniline In Water Samples Using Solidified Floating Organic Drop Microextraction (Sfodme) And Gas Chromatography, Shayessteh Dadfarnia, Mohammad Mirzaei, Ali Mohammad Haji Shabani, Batoul Ramazanzadeh Jan 2012

Determination Of Ultratrace Amounts Of Dichloro-Nitrobenzene And Dichloro-Nitroaniline In Water Samples Using Solidified Floating Organic Drop Microextraction (Sfodme) And Gas Chromatography, Shayessteh Dadfarnia, Mohammad Mirzaei, Ali Mohammad Haji Shabani, Batoul Ramazanzadeh

Turkish Journal of Chemistry

Solidified floating organic drop microextraction (SFODME) in combination with gas chromatography with an electron capture detector was used for separation/enrichment and determination of 2,5-dichloro-nitrobenzene, 2,3-dichloro-nitrobenzene, and 2,6-dichloro-4-nitroaniline in water samples. The main parameters affecting the performance of SFOME, such as solvent volume, extraction time, stirring rate, extraction temperature, sample volume, nature of the solvent and ionic strength were optimized. Under the optimum experimental conditions, good relative standard deviations of 7.5%, 6.9%, and 9.3% for 7 extractions and determination of 50 ng L^{-1} of 2,5-dichloro-nitrobenzene, 2,3-dichloro-nitrobenzene and 2,6-dichloro-4-nitroaniline were obtained, respectively. Enrichment factors of 1390, 1398, and 1362 and detection limits …

Go to article

Reduction, Mannich Reaction And Antimicrobial Activity Evaluation Of Some New 1,2,4-Triazol-3-One Derivatives, Seda Fandakli, Serap Başoğlu, Hakan Bektaş, Meltem Yolal, Ahmet Demi̇rbaş, Şengül Alpay Karaoğlu Jan 2012

Reduction, Mannich Reaction And Antimicrobial Activity Evaluation Of Some New 1,2,4-Triazol-3-One Derivatives, Seda Fandakli, Serap Başoğlu, Hakan Bektaş, Meltem Yolal, Ahmet Demi̇rbaş, Şengül Alpay Karaoğlu

Turkish Journal of Chemistry

Ethyl[4-arylmethyleneamino-3-(4-metylphenyl)-5-oxo-4,5-dihydro- 1H-1,2,4-triazole-1-yl]acetates (3a-e and 10a-d) were obtained starting from 4-amino-2,4-dihydro-3H-1,2,4-triazol-3-ones (1 and 9) in 2 steps. The treatment of 3a-e with NaBH_4 resulted in the formation of 3 kinds of product incorporating carboxcilic acid (4a-c) or alcohol (5a-e) functionality. [4-{[(4-Methoxyphenyl)methylene]amino}- and 4-{[pyridin-4-ylmethylene]amino}-3-(4-methylphenyl)-5-oxo-4,5-dihydro-1H- 1,2,4-triazole-1-yl] acetic acids (6a, 6e) were obtained by the hydrolysis of the corresponding esters (5a-5e). The treatment of 6a with NaBH_4 caused the reduction of only the imine bond; the carboxyl group remained unchanged. Then this carboxylic acid was converted to the corresponding hydrazide (8) in 2 steps by reaction with ethanol and hydrazine hydrate, respectively. The synthesis …

Go to article

Synthesis And Characterization Of Bis(Azine) Ligands And Metal Complexes: Dna-Interaction And Extraction Properties For Metals And Dichromate Anions, Sultan Kulaksizoğlu, Cansu Gökçe, Ramazan Güp Jan 2012

Synthesis And Characterization Of Bis(Azine) Ligands And Metal Complexes: Dna-Interaction And Extraction Properties For Metals And Dichromate Anions, Sultan Kulaksizoğlu, Cansu Gökçe, Ramazan Güp

Turkish Journal of Chemistry

Two new bis(bidentate) azine ligands were prepared by linking (1Z,1'Z)-1,1'-{butane-1,4-diylbis[oxyben-zene-4,1- diyl(1Z)eth-1-yl-1-ylidene]}dihydrazine to salicylaldehyde and pyridine-2-carbaldehyde, 1,4-bis{4-{(1E)-1-((2E)-(2- hydroxybenzene--2-ylmethy-lidene)hydrazonylidene)ethyl}phenoxy}butane (H_2L^1), and 1,4-bis{4-{(1E)-1-((2E)-(pyridine--2-ylmethylidene) hydrazonylidene)ethyl}phenoxy}butane (L^2), respecti- vely. Two kinds of copper(II) and nickel(II) complexes with different ligands were prepared. Reaction of H_2L^1 with Cu(II) and Ni(II) acetate with 1:1 molar ratio gave double stranded binuclear bis(azine) complexes with stoichiometry [M(L^1)]_2 containing {M^{II}N_2O_2} centers. On the other hand, 1:1 molar ratio reaction of Cu(II) and Ni(II) chloride with L^2 yielded mononuclear metal complexes with general stoichiometry [M(L^2)Cl_2] containing {M^{II}N_2N_2} centers. The structures of both bis(azine) ligands and complexes were identified by elemental analysis, infrared …

Go to article

Synthesis And Antimicrobial Activity Of Some Novel 4-Hydroxyquinolin-2(1h)-Ones And Pyrano[3,2-C] Quinolinones From 3-(1-Ethy1-4-Hydroxy-2-Oxo-1,2-Dihydroquinolin-3-Yl)-3-Oxopropanoic Acid, Hany Mohamed Hassanin, Magdy Ahmed Ibrahim, Youssef Abdel-Salam Alnamer Jan 2012

Synthesis And Antimicrobial Activity Of Some Novel 4-Hydroxyquinolin-2(1h)-Ones And Pyrano[3,2-C] Quinolinones From 3-(1-Ethy1-4-Hydroxy-2-Oxo-1,2-Dihydroquinolin-3-Yl)-3-Oxopropanoic Acid, Hany Mohamed Hassanin, Magdy Ahmed Ibrahim, Youssef Abdel-Salam Alnamer

Turkish Journal of Chemistry

Chlorination, bromination, and condensation reactions of 3-(1-ethy1-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-3-oxopropanoic acid (3) were studied. Some novel 4-hydroxyquinolin-2(1H)-ones and pyrano[3,2-c]quinolin-2(1H)-ones were also prepared. The structures of the novel compounds were established by elemental analyses and spectral data. All the products were also screened in vitro for their antimicrobial activity.

Go to article

Preparation, Morphology, And Thermal And Optical Properties Of Thin Films Of Ferric Chloride/Polyethylene Oxide Composites, Sabiha Sultana, Muhammad Saleem Khan, Muhammad Humayun Jan 2012

Preparation, Morphology, And Thermal And Optical Properties Of Thin Films Of Ferric Chloride/Polyethylene Oxide Composites, Sabiha Sultana, Muhammad Saleem Khan, Muhammad Humayun

Turkish Journal of Chemistry

Pure poly (ethylene oxide) (PEO) films and PEO-FeCl_3 films of various concentration were prepared and studied for thermal and optical properties. Various analytical techniques like XRD, EDX, SEM, TGA, and UV were used to examine the structural properties of PEO and PEO-FeCl_3 systems. X-ray scans (XRD) revealed the existence of some crystalline part in the PEO matrix. The concentration of FeCl_3 has a great effect on the crystallinity of PEO. Thermogravimetric analysis (TGA) data established that accumulation of FeCl_3 to PEO films enhanced the thermal stability of PEO. The optical properties of these systems were also studied in the UV-Visible …

Go to article

Chemical And Biotransformation Of Gelomulide F: A Rare Diterpene Lactone, Humaira Yasmeen Gondal, Muhammad Iqbal Choudhary Jan 2012

Chemical And Biotransformation Of Gelomulide F: A Rare Diterpene Lactone, Humaira Yasmeen Gondal, Muhammad Iqbal Choudhary

Turkish Journal of Chemistry

Chemical and biotransformations of a rare diterpene lactone, Gelomulide F (1), from the cytotoxic extract of leaves of Suregada multiflora were studied. Fermentation of compound 1 with Sachromyces cerevisiae transformed it to Gelomulide D (2) and E (3), whereas its treatment with 2N KOH yielded Gelomulide D (2). In addition, a novel compound (4) was obtained by its diastereo and chemoselective reduction with NaBH_4. All of these compounds were characterized on the basis of extensive ^1H-NMR, ^{13}C-NMR, 2D NMR, and mass spectral analyses.

Go to article

Preparation Of 2-(N,N-Dialkylamino)-2,4,6- Cycloheptatrien-1-One Derivatives From An Isocyanide, A Primary Amine, Propionaldehyde, And Tropolone Via Ugi-Smiles Coupling Reaction In The Presence Of Silica Nanoparticles, Abdolhossain Massoudi, Issa Amini, Ali Ramazani, Fatemeh Zeinali Nasrabadi Jan 2012

Preparation Of 2-(N,N-Dialkylamino)-2,4,6- Cycloheptatrien-1-One Derivatives From An Isocyanide, A Primary Amine, Propionaldehyde, And Tropolone Via Ugi-Smiles Coupling Reaction In The Presence Of Silica Nanoparticles, Abdolhossain Massoudi, Issa Amini, Ali Ramazani, Fatemeh Zeinali Nasrabadi

Turkish Journal of Chemistry

The use of Smiles rearrangement in Ugi-type couplings with tropolone allows very straightforward multicomponent formation of 2-(N,N-dialkylamino)-2,4,6-cycloheptatrien-1-one derivatives. The 4-component reaction of isocyanides, tropolone (2-hydroxy-2,4,6- cycloheptatrien-1-one), primary amines, and propionaldehyde in the presence of silica nanoparticles (silica NPs, ca. 42 nm) proceeds easily in methanol to form the title compounds in a new Ugi--Smiles-type reaction.

Go to article

Synthesis Of 3-Pyrroline-2-Ones From Amino Acids And An Aryl Amine, Nezi̇re Saygili, Cemi̇l Aydoğan Jan 2012

Synthesis Of 3-Pyrroline-2-Ones From Amino Acids And An Aryl Amine, Nezi̇re Saygili, Cemi̇l Aydoğan

Turkish Journal of Chemistry

The conversion of the amino group of amino dicarboxylicacid esters and an aryl amine into N-substituted pyrrolinone derivatives with dimethoxydihydrofurane is described. The conversion also occurs with serine methylester but it decomposes very quickly.

Go to article

Synthesis And Antioxidant And Antimicrobial Evaluation Of Novel 4-Substituted-1h-1,2,4-Triazole Derivatives, Sultan Baytaş, Evi̇n Kapçak, Tülay Çoban, Hati̇ce Özbi̇lge Jan 2012

Synthesis And Antioxidant And Antimicrobial Evaluation Of Novel 4-Substituted-1h-1,2,4-Triazole Derivatives, Sultan Baytaş, Evi̇n Kapçak, Tülay Çoban, Hati̇ce Özbi̇lge

Turkish Journal of Chemistry

A series of 4-benzyl/phenyl-3-(1-methyl-1H-indole-2-yl)-1H- 1,2,4-triazole-5(4H)-thione (4a,b) and 2-{4-[benzyl/phenyl-5- (substitutedbenzylthio)]-4H-1,2,4-triazole-3-yl}-1-methyl-1H-indole derivatives (5a-p) were synthesized and evaluated for their in vitro scavenging of DPPH and superoxide radical, and lipid peroxidation inhibition effects as well as their antimicrobial properties. DPPH radical scavenging capacity was found to be equipotent with BHT and found in compounds containing 1,2,4-triazole-5(4H)-thione moiety (4a,b). With regard to antimicrobial properties, compound 5k showed slight antimicrobial activity against all the test microorganisms.

Go to article

Evaluation Of A Wide Rim Phosphorylated Calix[4]Arene's Properties As A Sensory Molecule In An Er(Iii)-Pvc Membrane Sensor, Abbas Ali Zamani, Massoumeh Parinejad, Fataneh Jamali, Mohammad Reza Yaftian, Dominique Matt Jan 2012

Evaluation Of A Wide Rim Phosphorylated Calix[4]Arene's Properties As A Sensory Molecule In An Er(Iii)-Pvc Membrane Sensor, Abbas Ali Zamani, Massoumeh Parinejad, Fataneh Jamali, Mohammad Reza Yaftian, Dominique Matt

Turkish Journal of Chemistry

This study concerns the evaluation of ionophoric properties of a functionalized calix[4]arene, named 5,17-bis(diphenylphosphinoyl)- 25,26,27,28-tetrapropoxycalix[4]arene (Calix), by its application as a sensing material in an erbium(III)-PVC membrane potentiometric sensor. A membrane formed by 30% PVC, 65% dioctyl phthalate (DOP) as plasticizing solvent mediator, 2% sodium tetraphenyl borate (NaTPB) as ion excluder, and 3% of Calix as ionophore shows the best performance of the sensor. The prepared sensor presents a nearly Nernstian response (a slope of 20.0 \pm 0.5 mV/decade) over a concentration range of 1 \times 10^{-7}--1 \times 10^{-3} M of erbium ions, with a limit of detection of 3.8 …

Go to article

Synthesis, Structural Characterization, And Benzyl Alcohol Oxidation Activity Of Mononuclear Manganese(Ii) Complex With 2,2'-Bipyridine: [Mn(Bipy)_2(Clo_4)_2], İbrahi̇m Kani̇, Mehmet Kurtça Jan 2012

Synthesis, Structural Characterization, And Benzyl Alcohol Oxidation Activity Of Mononuclear Manganese(Ii) Complex With 2,2'-Bipyridine: [Mn(Bipy)_2(Clo_4)_2], İbrahi̇m Kani̇, Mehmet Kurtça

Turkish Journal of Chemistry

A manganese(II) complex of 2,2'-bipyridine (bipy) was synthesized and characterized by X-ray diffraction, IR, and UV-vis spectroscopy. The activity of the complex was tested for oxidation of benzyl alcohols using t-BuOOH as an oxidant in organic solvents and in an organic/water biphasic system (hexane/H_2O, toluene/H_2O). The effect of solvent, temperature, oxidant, and some additives (KBr, N(C_4H_9)Br, and N-bromosuccinimide) on the oxidation of benzyl alcohol is reported. The results show that benzyl alcohol was selectively converted to benzaldehyde in 71.9% yield within 4 h in acetonitrile. Control experiments performed without catalyst and the corresponding metal salt as catalyst produced no benzaldehyde …

Go to article

Mwcnt/Nano-Zro_2 As A New Solid Phase Extractor: Its Synthesis, Characterization, And Application To Atomic Absorption Spectrometric Determination Of Lead, Orhan Murat Kalfa, Özcan Yalçinkaya, Ali̇ Rehber Türker Jan 2012

Mwcnt/Nano-Zro_2 As A New Solid Phase Extractor: Its Synthesis, Characterization, And Application To Atomic Absorption Spectrometric Determination Of Lead, Orhan Murat Kalfa, Özcan Yalçinkaya, Ali̇ Rehber Türker

Turkish Journal of Chemistry

Nanoscale ZrO_2 was synthesized on a multiwall carbon nanotube (MWCNT) and designed as a new solid phase extractor for metal ion preconcentration. The characterization of the synthesized material was achieved by transmission electron microscope (TEM) and X-ray diffraction (XRD). Then the new nanoscale material was applied to preconcentration of lead(II) from various matrices. Different experimental factors including pH of the sample solution, sample volume, flow rate of the sample solution, and volume and concentration of the eluent for the preconcentration step were examined. The effect of interfering ions on the recovery of the lead(II) was also investigated. The recovery of …

Go to article

The Reduction Of Storm Surge By Vegetation Canopies: Three-Dimensional Simulations, Y. Peter Sheng, Andrew Lapetina, Gangfeng Ma Jan 2012

The Reduction Of Storm Surge By Vegetation Canopies: Three-Dimensional Simulations, Y. Peter Sheng, Andrew Lapetina, Gangfeng Ma

Civil & Environmental Engineering Faculty Publications

Significant buffering of storm surges by vegetation canopies has been suggested by limited observations and simple numerical studies, particularly following recent Hurricanes Katrina, Rita, and Wilma. Here we simulate storm surge and inundation over idealized topographies using a three-dimensional vegetation-resolving storm surge model coupled to a shallow water wave model and show that a sufficiently wide and tall vegetation canopy reduces inundation on land by 5 to 40 percent, depending upon various storm and canopy parameters. Effectiveness of the vegetation in dissipating storm surge and inundation depends on the intensity and forward speed of the hurricane, as well as the …

Go to article

Theoretical Properties Of The Weighted Generalized Rayleigh And Related Distributions, Xueheng Shi, Broderick O. Oluyede, Marvis Pararai Jan 2012

Theoretical Properties Of The Weighted Generalized Rayleigh And Related Distributions, Xueheng Shi, Broderick O. Oluyede, Marvis Pararai

Mathematical Sciences: Faculty Publications

In this paper, a new class of weighted generalization of the Rayleigh distribution is constructed and studied. The statistical properties of these distributions including the behavior of hazard or failure rate and reverse hazard functions, moments, moment generating function, mean, variance, coecient of variation, coecient of skewness, coecient of kurtosis are obtained. Other important properties including entropy (Shannon, beta and generalized) which are measures of the uncertainty in these distributions are also presented.

Go to article

Theoretical Properties Of The Length-Biased Inverse Weibull Distribution, Jing X. Kersey, Broderick O. Oluyede Jan 2012

Theoretical Properties Of The Length-Biased Inverse Weibull Distribution, Jing X. Kersey, Broderick O. Oluyede

Mathematical Sciences: Faculty Publications

We investigate the length-biased inverse Weibull (LBIW) distribution, deriving its density function, hazard and reverse hazard functions, and reliability function. The moments, moment-generating function, Fisher information and Shannon entropy are also given. We discuss parameter estimation via the method of moments and maximum likelihood, and hypothesis testing for the LBIW and parent distributions.

Go to article

Signal To Noise Ratio Estimation Using The Expectation Maximization Algorithm, Ahmed Almradi Jan 2012

Signal To Noise Ratio Estimation Using The Expectation Maximization Algorithm, Ahmed Almradi

Theses

Signal to Noise Ratio (SNR) estimation when the transmitted symbols are unknown is a common problem in many communication systems, especially those which require an accurate SNR estimation. For instance, modern wireless communication systems usually require accurate estimate of SNR without knowledge of the transmitted symbols. In addition, SNR estimation is required in order to perform efficient signal detection, power control, and adaptive modulation In this study, Non data Aided (NDA) SNR estimation for Binary Phase Shift Keying (PBSK) and Quadrature Phase Shift Keying (QPSK) using the Expectation Maximization (EM) algorithm is developed. The assumption here is that the received …

Go to article

First Prev Next Last