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2009

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Articles 571 - 600 of 823

Full-Text Articles in Chemistry

Characterization And Electrochemical Study Of Nano-Composition Based Methylene Blue- And Riboflavin-Nafion On The Surface Of Gold Electrode, Saeed Rezaei-Zarchi, Aisha Javed, Hossein Mirjalili, Hossain Bari Abarghouei, Seyed Ali Hashemizadeh Jan 2009

Characterization And Electrochemical Study Of Nano-Composition Based Methylene Blue- And Riboflavin-Nafion On The Surface Of Gold Electrode, Saeed Rezaei-Zarchi, Aisha Javed, Hossein Mirjalili, Hossain Bari Abarghouei, Seyed Ali Hashemizadeh

Turkish Journal of Chemistry

A functional membrane, composed of the nanoparticles of methylene blue (MB) and Nafion, was constructed during the present study. The materials were characterized by the methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Visible and FT-IR. The average diameter of new nano-particles was estimated to be about 60 nm. A novel Nafion-riboflavin membrane was also constructed and characterized by the methods of SEM, TEM and UV-Visible spectroscopy. The estimated average diameter of the new nanoparticles was about 60 nm. The functional membranes of Nafion-riboflavin and Nafion-methylene blue showed a quasi-reversible electrochemical behavior, on the gold electrode, with …

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Synthesis, Reactions, And Antiarrhythmic Activities Of Some Novel Pyrimidines And Pyridines Fused With Thiophene Moiety, Abd El-Galil E. Amr, Naglaa A. Abdel-Hafez, Salwa F. Mohamed, Mohamed M. Abdalla Jan 2009

Synthesis, Reactions, And Antiarrhythmic Activities Of Some Novel Pyrimidines And Pyridines Fused With Thiophene Moiety, Abd El-Galil E. Amr, Naglaa A. Abdel-Hafez, Salwa F. Mohamed, Mohamed M. Abdalla

Turkish Journal of Chemistry

We report herein the synthesis and antiarrhythmic activities of some newly synthesized heterocyclic theino[2,3-c]pyrimidine and theino[2,3-c]pyridine derivatives fused with thiophene moiety. Initially the acute toxicity of the compounds was assayed via the determination of their LD_{50}. The antiarrhythmic activities for the compounds were determined and all the tested compounds were found more potent than Procaine amide^{\textregistered} and Lidocaine^{\textregistered} as positive antiarrhythmic controls.

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Application Of Fam Ligands In The Metal-Promoted Catalytic Enantioselective Synthesis Of Organic Compounds, Özdemi̇r Doğan, Philip P. Garner, Adnan Bulut Jan 2009

Application Of Fam Ligands In The Metal-Promoted Catalytic Enantioselective Synthesis Of Organic Compounds, Özdemi̇r Doğan, Philip P. Garner, Adnan Bulut

Turkish Journal of Chemistry

Novel ferrocenyl substituted aziridinyl methanol (FAM) ligands were synthesized and successfully used in metal-promoted catalytic enantioselective azomethine ylide cycloadditions, diethylzinc additions to enones, alkynylzinc additions to aldehydes, diethylzinc additions to aldehydes, and Henry reactions. These reactions are summarized in this report.

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Synthesis And In Vitro Anti-Helicobacter Pylori Activity Of 2-(Substituted Benzylthio)-5-(5-Nitro-2- Furyl)-1, 3, 4-Thiadiazole Derivatives, Hossein Nasr Isfahani, Khalil Faghihi, Atena Izadkhah, Meisam Shabanian Jan 2009

Synthesis And In Vitro Anti-Helicobacter Pylori Activity Of 2-(Substituted Benzylthio)-5-(5-Nitro-2- Furyl)-1, 3, 4-Thiadiazole Derivatives, Hossein Nasr Isfahani, Khalil Faghihi, Atena Izadkhah, Meisam Shabanian

Turkish Journal of Chemistry

Starting from (5-nitrofuran-2-yl)methylene diacetate, a new series of 2-[(substituted benzyl)thio]-5-(5-nitro-2-furyl)-1,3,4-thiadiazoles (6a-n) were synthesized and the structures of the compounds were determined using spectroscopic methods including mass spectrometry, ^1H-nuclear magnetic resonance, infrared spectroscopy, and elemental analysis. The in vitro anti-Helicobacter pylori activity of the synthesized compounds was evaluated by the disk diffusion method against the clinical isolates of Helicobacter pylori. The results indicated that most of the synthesized compounds exhibited significant inhibitory activity against H. pylori with respect to standard drug metronidazole. Compound 6l, containing the 2-chloro-6-fluorobenzylthio moiety, was the most potent compound tested.

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Synthesis And In Vitro Anti-Helicobacter Pylori Activity Of 2-(Substituted Benzylthio)-5-(5-Nitro-2- Furyl)-1, 3, 4-Thiadiazole Derivatives, Negar Mohammadhosseini, Ali Asadipor, Bahram Letafat, Mohsen Vosooghi, Farideh Siavoshi, Abbas Shafiee, Alireza Foroumadi Jan 2009

Synthesis And In Vitro Anti-Helicobacter Pylori Activity Of 2-(Substituted Benzylthio)-5-(5-Nitro-2- Furyl)-1, 3, 4-Thiadiazole Derivatives, Negar Mohammadhosseini, Ali Asadipor, Bahram Letafat, Mohsen Vosooghi, Farideh Siavoshi, Abbas Shafiee, Alireza Foroumadi

Turkish Journal of Chemistry

Starting from (5-nitrofuran-2-yl)methylene diacetate, a new series of 2-[(substituted benzyl)thio]-5-(5-nitro-2-furyl)-1,3,4-thiadiazoles (6a-n) were synthesized and the structures of the compounds were determined using spectroscopic methods including mass spectrometry, ^1H-nuclear magnetic resonance, infrared spectroscopy, and elemental analysis. The in vitro anti-Helicobacter pylori activity of the synthesized compounds was evaluated by the disk diffusion method against the clinical isolates of Helicobacter pylori. The results indicated that most of the synthesized compounds exhibited significant inhibitory activity against H. pylori with respect to standard drug metronidazole. Compound 6l, containing the 2-chloro-6-fluorobenzylthio moiety, was the most potent compound tested.

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Pregnane Steroids From The Heartwood Of Azadirachta Indica, Bina Shaheen Siddiqui, Syed Kashif Ali, Syed Tariq Ali, Fayyaz Ahmed Jan 2009

Pregnane Steroids From The Heartwood Of Azadirachta Indica, Bina Shaheen Siddiqui, Syed Kashif Ali, Syed Tariq Ali, Fayyaz Ahmed

Turkish Journal of Chemistry

The heartwood of Azadirachta indica (Meliaceae) yielded a new steroid (2\alpha, 3\beta, 4\beta-trihydroxypregnan-16-one) and 2 known steroids (2\beta, 3\beta, 4\beta-trihydroxypregnan-16-one and 2\alpha, 3\alpha, 4\beta-trihydroxypregnan-16-one). Their structures were elucidated through spectral studies including 2D NMR (COSY, NOESY, J-resolved, HMQC, HMBC) experiments.

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Study Of Binary Complexes Of Nickel(Ii), Copper(Ii), And Vanadium(V) With Acetazolamide In Aqueous Medium By Voltammetry, İclal Bulut Jan 2009

Study Of Binary Complexes Of Nickel(Ii), Copper(Ii), And Vanadium(V) With Acetazolamide In Aqueous Medium By Voltammetry, İclal Bulut

Turkish Journal of Chemistry

The voltammetric behaviour of acetazolamide, the systemic carbonic anhydrase inhibitor, in the presence of some metal ions (Cu(II), Ni(II), and V(V)) were investigated using square-wave and cyclic voltammetry in physiological pH (pH 7.4). Square-wave voltammogram of acetazolamide in the absence of metal ions gave only 1 reduction peak at -1.65 V attributed to a catalytic hydrogen peak. Three reversible peaks at -0.068, -0.262, and -0.434 V were observed for the solutions containing both copper(II) ions and acetazolamide in the SWV. The peak at -0.434 V was attributed to Cu(II)-acetazolamide complex. In the presence of acetazolamide, copper-acetazolamide complex formation was proved …

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Chemical Constituents And Mushroom Tyrosinase Inhibition Activity Of Chloroxylon Swietenia Leaves, G. Venkatateswara Rao, K. Sambasiva Rao, Tiruganasambandham Annamalai, Narayanasamy Radhakrishnan, Triptikumar Mukhopadhyay Jan 2009

Chemical Constituents And Mushroom Tyrosinase Inhibition Activity Of Chloroxylon Swietenia Leaves, G. Venkatateswara Rao, K. Sambasiva Rao, Tiruganasambandham Annamalai, Narayanasamy Radhakrishnan, Triptikumar Mukhopadhyay

Turkish Journal of Chemistry

From the leaves of Chloroxylon swietenia DC., 5 known secondary metabolites, namely 6, 8-diprenylumbelliferone (1), bergaptan (2), isopimpinellin (3), tritriacontanol (4), and isoquercetrin (5), were isolated from a folklore medicinal plant. Three compounds were isolated for the first time from this genus. The structures of these compounds were elucidated by UV, IR, 1D and 2D NMR techniques. Different fractions from the leaves of C. swietenia were investigated for their tyrosinase inhibition activity.

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2,2'-Binaphthylene Phosphorochloridite (Binol-Pcl) As A Bulky And Efficient Reagent For The Conversion Of Primary And Secondary Alcohols Into Iodides, And Tertiary Alcohols Stereo- And/Or Regioselectively Into Olefin(S), Nader Noroozi-Pesyan, Jabbar Kalaphy, Hossein Khani-Meinagh Jan 2009

2,2'-Binaphthylene Phosphorochloridite (Binol-Pcl) As A Bulky And Efficient Reagent For The Conversion Of Primary And Secondary Alcohols Into Iodides, And Tertiary Alcohols Stereo- And/Or Regioselectively Into Olefin(S), Nader Noroozi-Pesyan, Jabbar Kalaphy, Hossein Khani-Meinagh

Turkish Journal of Chemistry

Primary and secondary alcohols were transformed in high yield to corresponding iodides by 4-chloro-3,5-dioxaphosphacyclohepta [2,1-\alpha; 3,4-\alpha'] dinaphthalene (BINOL-PCl) at room temperature. The tertiary alcohols formed corresponding alkenes by stereo- and/or regioselective elimination reactions. (E)-1,2-Diphenyl-1-propene and 2,3-diphenyl-1-propene were stereoselectively obtained from 1,2-diphenyl-2-propanol, as representative. No (Z)-1,2-diphenyl-1-propene was observed. 2-Methyl-1-phenylcyclopentene and 3-methyl-2-phenylcyclopentene were regioselectively obtained from 2-methyl-1-phenylcyclopentanol. ^{13}C chemical shifts for the \alpha-methylene carbon of some alkyl iodides empirically calculated through a very simple additive relationship lead to similar or even better values than the reported values. All primary alkyl iodides showed the iodine heavy atom effect on the \alpha-methylene carbon chemical …

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Comparative Study Of Selective Co Oxidation Over Pt-Co-M/Al_2o_3 Catalysts (M=Ce, Mg, Mn, Zr, Fe) In Hydrogen-Rich Streams: Effects Of A Second Promoter, K. Erdem Uğuz, Ramazan Yildirim Jan 2009

Comparative Study Of Selective Co Oxidation Over Pt-Co-M/Al_2o_3 Catalysts (M=Ce, Mg, Mn, Zr, Fe) In Hydrogen-Rich Streams: Effects Of A Second Promoter, K. Erdem Uğuz, Ramazan Yildirim

Turkish Journal of Chemistry

The selective CO oxidation over Pt-Co/Al_2O_3 catalyst in hydrogen-rich streams was studied in the presence of Ce, Mg, Mn, Ze, and Fe as the second promoters. The catalysts were prepared using incipient to wetness co-impregnation, and tested in a microflow reaction system. The effects of the second promoter were investigated in near 100% CO conversion conditions both in the absence and presence of CO_2 and H_2O in the feed. 100% CO conversion was obtained with the addition of each second promoter at 110 °C while Pt-Co/Al_2O_3 catalyst had 96%-98% CO conversion. It was also found that changing the Pt ratio …

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Zeolite Catalyzed Efficient Synthesis Of Perimidines At Room Temperature, Akbar Mobinikhaledi, Naser Forughifar, Nemat Bassaki Jan 2009

Zeolite Catalyzed Efficient Synthesis Of Perimidines At Room Temperature, Akbar Mobinikhaledi, Naser Forughifar, Nemat Bassaki

Turkish Journal of Chemistry

Arylperimidines, 3(a-l), were synthesized in good yields by cyclocondensation reaction of 1,8-diaminonaphthalene and aromatic aldehydes in the presence of NaY zeolite as a catalyst. The simple environmentally benign nature, reusability of the catalyst, and the easy work-up reaction are some of the advantages of this protocol.

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Oxorhenium(V)-Mediated Syntheses And Structures Of Oxypyridinium-Ammonium Zwitterions, Abubak'r Abrahams, Thomas Gerber, Eric Hosten, Peter Mayer Jan 2009

Oxorhenium(V)-Mediated Syntheses And Structures Of Oxypyridinium-Ammonium Zwitterions, Abubak'r Abrahams, Thomas Gerber, Eric Hosten, Peter Mayer

Turkish Journal of Chemistry

Treatment of N,N-bis(2-hydroxybenzyl)-2-(2-aminoethyl) dimethylamine (H_2had) with trans-[ReO_2(py)_4]I in acetone affords the iodide salts of the oxypyridinium-ammonium zwitterions N^1-(2-hydroxybenzyl)-N^2,N^2-dimethyl-N^1-((2-oxypyridinium)-1- methyl)ethane-1,2-diamine [Hhpd]^+ and N^2,N^2-dimethyl-N^1- bis((2-oxypyridinium)-1- methyl)ethane-1,2-diamine [dod]^+. The products were characterized by X-ray structure analysis, and NMR and IR spectroscopy.

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Kinetics Of Co Oxidation Over Pt-Ceo_X Supported On Air-Oxidized Activated Carbon, Berri̇n Gülyüz, Şeyma Özkara Aydinoğlu, Ahmet Erhan Aksoylu, Zeynep İlsen Önsan Jan 2009

Kinetics Of Co Oxidation Over Pt-Ceo_X Supported On Air-Oxidized Activated Carbon, Berri̇n Gülyüz, Şeyma Özkara Aydinoğlu, Ahmet Erhan Aksoylu, Zeynep İlsen Önsan

Turkish Journal of Chemistry

Kinetics of low-temperature CO oxidation was studied under atmospheric pressure at 383 K in the initial rates region over 1wt%Pt-1wt%CeO_x supported on air-oxidized activated carbon (AC2). Feed concentrations of 1-5 mol% CO and 1-2.5 mol% O_2 with balance He were used for CO oxidation in the absence of hydrogen. A simple power-function rate expression was obtained with reaction orders of -0.24 in CO and 0.98 in O_2, and a plausible LHHW expression compatible with mechanisms reported in the literature was proposed. Feed concentrations of 5 mol% CO and 2.5 mol% O_2 were used for investigating the effect of the presence …

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Hydrogen Storage Via Physisorption: The Combined Role Of Adsorption Enthalpy And Entropy, Carlos Otero Arean, Barbara Bonelli, Montserrat Rodriguez Delgado, Edoardo Garrone Jan 2009

Hydrogen Storage Via Physisorption: The Combined Role Of Adsorption Enthalpy And Entropy, Carlos Otero Arean, Barbara Bonelli, Montserrat Rodriguez Delgado, Edoardo Garrone

Turkish Journal of Chemistry

Materials capable of cost-effective on-board hydrogen storage and delivery are currently being sought worldwide as a means to facilitate a hydrogen-based energy transition in the transportation sector. Among the solutions proposed, hydrogen storage by physisorption on porous solids constitutes a main avenue of research, and for intelligent design of such materials a detailed knowledge of gas adsorption thermodynamics is of the utmost importance. Analysis of the available data for hydrogen adsorption on alkali and alkaline-earth cation exchanged zeolites clearly shows that standard adsorption enthalpy (\Delta H^0) and entropy (\Delta S^0) are correlated, in the sense that larger \Delta S^0 values …

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Spectroscopic Studies And Hartree-Fock Ab Initio Calculations Of A Substituted Amide Of Pyrazine-2-Carboxylic Acid - C_{16}H_{18}Cln_3o, Chacko Yohannan Panicker, Hema Tresa Vanghese, Thaha Thansani Jan 2009

Spectroscopic Studies And Hartree-Fock Ab Initio Calculations Of A Substituted Amide Of Pyrazine-2-Carboxylic Acid - C_{16}H_{18}Cln_3o, Chacko Yohannan Panicker, Hema Tresa Vanghese, Thaha Thansani

Turkish Journal of Chemistry

A substituted amide of pyrazine-2-carboxylic acid was prepared and the IR spectrum was recorded and analysed. The compound prepared was identified by NMR and mass spectra. The vibrational frequencies of the title compound were computed using the Hartree-Fock level of theory using the 6-31G* basis set and compared with the experimental data. The red shift of the NH stretching frequency indicates weakening of the NH bond. The splitting of the NH stretching bond is due to Davidov coupling between neighbouring units. The first hyperpolarizability, infrared intensities, and Raman activities are reported. Methyl substitution affects all the carbon-nitrogen and carbon-carbon bond …

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Synthesis And Physical Studies Of Polycarbonate Of P-Tert-}Butylcalix[4]Arene: A Highly Selective Receptor For Na^+, Muhammad Ashram, Nawash Al Ghezawi, Ibrahim Abu Awaad, Gülsen Asman Jan 2009

Synthesis And Physical Studies Of Polycarbonate Of P-Tert-}Butylcalix[4]Arene: A Highly Selective Receptor For Na^+, Muhammad Ashram, Nawash Al Ghezawi, Ibrahim Abu Awaad, Gülsen Asman

Turkish Journal of Chemistry

The synthesis and characterization of a polycarbonate of p-tert-butylcalix[4]arene 4 are reported. It was synthesized by condensation of p-tert-butylcalix[4]arenetetraol derivative 3 with ethyl chloroformate. This new polymer possesses a hydrolyzable backbone and tunable hydrophobic/hydrophilic properties. The experimental results indicate that the polycarbonate was successfully synthesized with average molecular weight \overline{M}_{w}, (2.328 \times 10^4 g/mol), which was determined by static light scattering method using a Berry plot. The structure of this polymer was determined by IR spectroscopy. The thermal properties were investigated using differential scanning calorimetry (DSC). The degree of crystallinity was measured by means of XRD. The extraction ability of …

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A Systematic Study On The Absorption And Fluorescence Properties Of 2,4,6-Triaryl And Tripyridylpyridines, Esra Findik, Mustafa Arik, Mustafa Ceylan Jan 2009

A Systematic Study On The Absorption And Fluorescence Properties Of 2,4,6-Triaryl And Tripyridylpyridines, Esra Findik, Mustafa Arik, Mustafa Ceylan

Turkish Journal of Chemistry

Eight different 2,4,6-triaryl, and tripyridylpridines compounds were synthesized and their fluorescent properties were studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques in 6 different solvents. Especially, 2,4,6-triarylpyridines showed strong fluorescence properties with high fluorescence quantum yields but small Stokes shifts.

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Antioxidant Galloylated Flavonoids From Geranium Tuberosum L. Subsp. Tuberosum, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Suna Atasayar Sabuncuoğlu, Hi̇lal Özgüneş, Olov Sterner Jan 2009

Antioxidant Galloylated Flavonoids From Geranium Tuberosum L. Subsp. Tuberosum, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Suna Atasayar Sabuncuoğlu, Hi̇lal Özgüneş, Olov Sterner

Turkish Journal of Chemistry

Phytochemical investigations on the most active EtOAc extract led to the isolation of 9 flavonoids [quercetin (1), quercetin 3-O-\beta-glucopyranoside (2), quercetin 3-O-\beta-galactopyranoside (3), quercetin 3-O-(2''-O-galloyl)-\beta-glucopyranoside (4), quercetin 3-O-(2''-O-galloyl)-\beta-galactopyranoside (5), quercetin 3-O-(6''-O-galloyl)-\beta-glucopyranoside (6), quercetin 3-O-(6''-O-galloyl)-\beta-galactopyranoside (7), quercetin-3-O-\alpha -arabinofuranoside (8), and quercetin-3-O-\alpha-rhamnopyranosyl-(1\to 6)-\beta-glucopyranoside (9)] and a simple phenolic compound (methyl gallate) (10). The structures of the compounds were elucidated by 1- and 2-dimensional NMR techniques (^1H, ^{13}C, COSY, HMBC, and HMQC) and ESI-TOF-MS spectrometry. H_2O_2-induced lipid peroxidation inhibitor effects in human red blood cells of different extracts of G. tuberosum L. subsp. tuberosum aerial parts were also investigated. All the compounds tested …

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Reactions Of The Solvent-Stabilized Compound [Moocl_2(Thf)_2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization And Semiempirical Am1* Calculations, Gülşah Kiliçkaya, Başak Doğan, Nursel Acar, Işil Topaloğlu Sözüer Jan 2009

Reactions Of The Solvent-Stabilized Compound [Moocl_2(Thf)_2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization And Semiempirical Am1* Calculations, Gülşah Kiliçkaya, Başak Doğan, Nursel Acar, Işil Topaloğlu Sözüer

Turkish Journal of Chemistry

Reaction of the solvent-stabilized dioxo-molybdenum(VI) compound [MoO_2Cl_2(THF)_2] with PPh_3 yielded the oxomolybdenum(IV) species [MoOCl_2(THF)_2] (1) by the removal of one oxygen atom as PPh_3O. The complexes [MoOCl_2(=NC_6H_4CN)] 2, [MoOCl_2(CNC_6H_4OH)] 3, [MoOCl_2(=NC_6H_4NH_2)] 4, and [MoOCl_2(=NC_6H_4OCH_3)] 5, were synthesized by the reactions of [MoOCl_2(THF)_2] with XC_6H_4Y (X = NH_2, Y = CN; X= CN, Y = OH; X = Y = NH_2; X = NH_2, Y = OCH_3). All the new compounds were characterized by elemental analyses, and FTIR, UV-Vis, and ^1H- and ^{13}C-NMR spectra. Geometrical parameters and molecular orbital calculations showed that compounds 2-5 are stabilized by a charge transfer between …

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A Simple And Efficient One-Pot Multicomponent Synthesis Of \Beta-Acetamido Carbonyl Compounds With Zn(Hso_4)_2 And Co(Hso_4)_2 As Catalysts, Ahmad Reza Momeni, Maryam Sadeghi, Motahareh Hadizadeh Jan 2009

A Simple And Efficient One-Pot Multicomponent Synthesis Of \Beta-Acetamido Carbonyl Compounds With Zn(Hso_4)_2 And Co(Hso_4)_2 As Catalysts, Ahmad Reza Momeni, Maryam Sadeghi, Motahareh Hadizadeh

Turkish Journal of Chemistry

Zn(HSO_4)_2 and Co(HSO_4)_2 has been used as efficient catalysts for the preparation of \beta-acetamido carbonyl compounds by Dakin-West reaction.

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An Efficient One Pot Synthesis Of 1,4-Dihydropyridines Using Alumina Sulfuric Acid (Asa) Catalyst, Mustafa Arslan, Cüneyt Faydali, Mustafa Zengi̇n, Mustafa Küçüki̇slamoğlu, Hülya Demi̇rhan Jan 2009

An Efficient One Pot Synthesis Of 1,4-Dihydropyridines Using Alumina Sulfuric Acid (Asa) Catalyst, Mustafa Arslan, Cüneyt Faydali, Mustafa Zengi̇n, Mustafa Küçüki̇slamoğlu, Hülya Demi̇rhan

Turkish Journal of Chemistry

An efficient synthetic method for 1,4-dihydropyridines has been developed using 3 or 4 component condensation reactions of aldehydes, 1,3-dicarbonyl compounds, and ammonium acetate in the presence of alumina sulfuric acid catalyst in minimum methanol at reflux temperature. This procedure offers several advantages including high yields, an environmentally friendly procedure, short reaction times, and a simple work-up procedure.

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Preparation And Characterization Of Magnetic Chitosan Nanospheres, Doina Hritcu, Marcel I. Popa, Nuculina Popa, Vasile Badescu, Vera Balan Jan 2009

Preparation And Characterization Of Magnetic Chitosan Nanospheres, Doina Hritcu, Marcel I. Popa, Nuculina Popa, Vasile Badescu, Vera Balan

Turkish Journal of Chemistry

A method for the preparation of magnetite/chitosan composite nanoparticles was developed. Colloidal magnetite particles (Fe_3O_4 produced by co-precipitation and stabilized in suspension by adding a non-ionic surfactant (Pluronic F127) were subsequently covered with a layer of chitosan (CS) prepared by ionotropic gelation using sodium tripolyphosphate (STPP) as a crosslinking agent. The products were characterized in terms of the following parameters: size distribution and \zeta-potential (by laser diffraction analysis), surface morphology (TEM), composition (FTIR, elemental analysis), magnetic properties (magnetic susceptibility analysis), and concentration of surface functional groups (potentiometric titration). The synthesis parameters were optimized for obtaining uniformly distributed colloidally stable, biocompatible …

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Antioxidant And Anticholinesterase Constituents Of Salvia Poculata, Ufuk Kolak, Işil Hacibeki̇roğlu, Mehmet Öztürk, Fevzi̇ Özgökçe, Gülaçti Topçu, Ayhan Ulubelen Jan 2009

Antioxidant And Anticholinesterase Constituents Of Salvia Poculata, Ufuk Kolak, Işil Hacibeki̇roğlu, Mehmet Öztürk, Fevzi̇ Özgökçe, Gülaçti Topçu, Ayhan Ulubelen

Turkish Journal of Chemistry

Two triterpenoids, namely 2\alpha,3\alpha-dihydroxy-24-nor- 4(23),12-oleanadien-28-oic acid (1) and ursolic acid (2); 4 flavonoids, namely 5-hydroxy-7,4'-dimethoxyflavone (3), cirsimaritin (4), eupatilin (5), and salvigenin (6); a diterpenoid, namely sclareol (7); and a steroid, namely \beta-sitosterol (8), were isolated from the aerial parts of Salvia poculata Nab., a Turkish endemic Salvia species. Total phenolic and flavonoid contents of the crude extract were determined as pyrocatechol and quercetin equivalents, respectively. The antioxidant activity of the crude extract and the isolated compounds (2-8) was established using \beta-carotene bleaching, superoxide anion radical, and ABTS cation radical scavenging activity. In addition, the anticholinesterase activity of the crude …

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Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking Part Ii: Modeling And Optimization, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel Jan 2009

Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking Part Ii: Modeling And Optimization, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel

Turkish Journal of Chemistry

High purity, carbon monoxide-free hydrogen and filamentous carbon can be produced by thermo-catalytic cracking of methane. Carbon filaments continue to grow until the catalyst deactivates because of carbon encapsulation. Regeneration of catalyst is important to maintain a continuous process. Our work on optimization of the partial regeneration method showed that activity of the catalyst can be sustained for longer times by gasifying not all but some extent of the deposited carbon. In the previous work, a kinetic model was developed to be able to understand the reaction mechanism of deactivation of fresh catalyst at the molecular level. The objective of …

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A Collection Of Micrographs: Where Science And Art Meet, Vuk Uskoković Jan 2009

A Collection Of Micrographs: Where Science And Art Meet, Vuk Uskoković

Pharmacy Faculty Articles and Research

Micrographs obtained using different instrumental techniques are presented with the purpose of demonstrating their artistic qualities. The quality of uniformity currently dominates the aesthetic assessment in scientific practice and is discussed in relation to the classical appreciation of the interplay between symmetry and asymmetry in arts. It is argued that scientific and artistic qualities have converged and inspired each other throughout millennia. With scientific discoveries and inventions enriching the world of communication, broadening the space for artistic creativity and making artistic products more accessible than ever, science inevitably influences artistic creativity. On the other hand, the importance of aesthetic principles …

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Synthesis And Single Crystal Structure Analysis Of Three Novel Benzoylthiourea Derivatives, Gülten Kavak, Süheyla Özbey, Gün Bi̇nzet, Nevzat Külcü Jan 2009

Synthesis And Single Crystal Structure Analysis Of Three Novel Benzoylthiourea Derivatives, Gülten Kavak, Süheyla Özbey, Gün Bi̇nzet, Nevzat Külcü

Turkish Journal of Chemistry

N,N-dimethyl-N' -(2-methylbenzoyl)thiourea, C_{11}H_{14}N_2SO (HL^1), N,N-dibutyl-N' -(2-methylben\-zoyl)thiourea, C{17}H{26}N2SO (HL^2), and N,N-dihexyl-N' -(2-methylbenzoyl) thiourea, C{21}H{34}N2SO (HL^3) were synthesized and characterized by elemental analysis, spectroscopic methods (FT-IR, NMR), and single crystal X-ray diffraction. Compound HL^1 crystallizes in the monoclinic system, space group P21/c, Z = 4. Compound HL^3 also crystallizes in the monoclinic system, space group P21/n, Z = 8 with 2 independent molecules in the asymmetric unit. Compound HL^2 crystallizes in the orthorhombic system, space group Pcnn, Z = 8. In all compounds, molecules form dimers through the strong intermolecular N-H...S hydrogen bonds. Moreover, there are different types of intra- and inter-molecular …

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Phonon Confinement Effects In The Raman Spectrum Of Nanodiamond, Sebastian Osswald, Vadym Mochalin, Mickaël Havel, Gleb N. Yushin, Yury G. Gogotsi Jan 2009

Phonon Confinement Effects In The Raman Spectrum Of Nanodiamond, Sebastian Osswald, Vadym Mochalin, Mickaël Havel, Gleb N. Yushin, Yury G. Gogotsi

Chemistry Faculty Research & Creative Works

Nanodiamonds (ND) exhibit unique properties due to their small size and high surface-to-volume ratio compared to bulk diamonds. A reduction in crystal size also affects ND Raman spectra. The confinement of optical phonons in nanocrystals (<10 nm) results in asymmetrically broadened Raman lines, which are shifted toward lower wavenumbers. The phonon confinement model (PCM) relates the observed changes in the Raman spectra to the crystal size and can be used for size characterization at the nanoscale. While the PCM was successfully applied to a variety of materials including Si and BN, results remained unsatisfactory in the case of ND. In order to improve the agreement between the predictions of the model and experimental Raman spectra of ND, effects such as crystal size distribution, lattice defects, and the energy dispersion of the phonon modes were taken into consideration and incorporated into the PCM. This work has shown that phonon wave vectors from small vibrational domains lead to a broad shoulder peak at ~1250 cm-1, that is often observed in the Raman spectrum of ND.

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Phenyl-Substituted Siloxane Hybrid Gels That Soften Below 140[Degrees]C, Andrei Jitianu, Glenn Amatucci, Lisa C. Klein Jan 2009

Phenyl-Substituted Siloxane Hybrid Gels That Soften Below 140[Degrees]C, Andrei Jitianu, Glenn Amatucci, Lisa C. Klein

Publications and Research

A characteristic of so-called melting gels is that the gels, which are rigid at room temperature, are able to soften and resoften at temperatures around 110 [degrees]C. However, after consolidation at temperatures higher than 150 [degrees]C, the gels no longer resoften. Two systems of melting gels were investigated: phenyltrimethoxysilane (PhTMS)–diphenyldimethoxysilane (DPhDMS) and phenyltriethoxysilane (PhTES)–diphenyldiethoxysilane (DPhDES). The influence of disubstituted versus monosubstituted alkoxide on the softening behavior and the temperature of decomposition was studied. The consolidation temperature increased as the amount of disubstituted alkoxide increased, while the decomposition temperature increased only slightly. In general, the ethoxy-containing gels (maximum at 150[degrees]C) consolidated …

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Nanofiltration Membrane Pilot Studies For Disinfection By-Product Control, Eric J. Lynne Jan 2009

Nanofiltration Membrane Pilot Studies For Disinfection By-Product Control, Eric J. Lynne

Electronic Theses and Dissertations

Watertown, South Dakota currently uses conventional softening to treat ground water to remove hardness, iron and manganese, and natural organic matter. The distribution system has experienced elevated concentrations of disinfection by-products, which will require additional treatment to comply with future limits set by the Stage 2 Disinfectant/Disinfection By-Products Rule. A nanofiltration membrane system has been proposed to remove additional natural organic matter from the softened water. Removing the natural organic material disinfection by-product precursors should reduce the concentration of disinfection by-products. The use of nanofiltration membranes has been previously documented to reject total organic carbon, while allowing desirable levels of …

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Isolation And Analysis Of Cyanobacterial Dna, Tiffany Crosby Jan 2009

Isolation And Analysis Of Cyanobacterial Dna, Tiffany Crosby

Senior Honors Theses and Projects

Cyanobacteria are a phylum of bacteria that possess a diverse number of biological characteristics. One of the evolutionary innovations of the cyanobacteria are its ability to perform oxygenating photosynthesis, which all cyanobacteria are able to perform. It is believed that a form of metabolism became the dominant method for producting fixed carbon from carbon dioxide (CO2) at around 3.5 billion years ago. Instead of using hydrogen sulfide, whose generated waste products were difficult to eliminate, the photosynthetic cyanobacteria used water as their hydrogen source (1). Many cyanobacteria are also capable of fixing atmospheric nitrogen (2). Cyanobacteria are present …

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