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2009

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Articles 13141 - 13170 of 14008

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On The Structure Sensitivity Of Co Oxidation On Alumina Supported Pd--Pt Bimetallic Catalysts, Sarp Kaya, Ebru Erunal, Riad Shaltaf, Şi̇nasi̇ Elli̇altioğlu, Deni̇z Üner Jan 2009

On The Structure Sensitivity Of Co Oxidation On Alumina Supported Pd--Pt Bimetallic Catalysts, Sarp Kaya, Ebru Erunal, Riad Shaltaf, Şi̇nasi̇ Elli̇altioğlu, Deni̇z Üner

Turkish Journal of Chemistry

CO oxidation reaction was studied over monometallic and bimetallic palladium--platinum catalysts at 25:75, 50:50, and 75:25 Pd:Pt atomic fractions co-impregnated over a \gamma -Al_2O_3 support. The size of the metal particles, measured by modified hydrogen chemisorption, increased as the Pd fractions in the catalyst increased. The surface compositions and site metal distributions of the catalysts determined from Monte Carlo simulations indicated that Pd atoms segregated to the surface: at low Pd levels, Pd occupied preferentially 6 and 7 coordinated defect-like sites. As the Pd fraction increased, first 8 coordinated (100) and then 9 coordinated (111) planes were populated. At low …

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Synthesis And Leishmanicidal Evaluation Of Novel 4-Substituted-2,2-Dimethyl-7-(Prop-2-Ynyloxy)Chromenes, Babak H. Alizadeh, Alireza Foroumadi, Susan K. Ardestani, Fatemeh Poorrajab, Abass Shafiee Jan 2009

Synthesis And Leishmanicidal Evaluation Of Novel 4-Substituted-2,2-Dimethyl-7-(Prop-2-Ynyloxy)Chromenes, Babak H. Alizadeh, Alireza Foroumadi, Susan K. Ardestani, Fatemeh Poorrajab, Abass Shafiee

Turkish Journal of Chemistry

Substituted 4-chromenes were synthesized via the Grignard coupling reaction of various substituted phenyl- and benzylmagnesium chlorides with 2,2-dimethyl-7-(prop-2-ynyloxy)chroman-4-one (1) in relatively good yield (60%-85%). The benzylic-substituted derivatives were a mixture of 2 exo and endo regioisomers, and the exo compounds were a mixture of E and Z isomers. Structural analysis of the exo and endo isomers, as well as E and Z of exo isomers were based on H-NMR, ^{13}C-NMR, and NOESY experiments. The synthetic compounds were examined for in vitro activity against Leishmania major and compound 9 (a, b) was the most active, with inhibitory activity of 36%.

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A Convenient Synthesis Of 2-Azido And 2-Thiocyanato-2,3-Unsaturated Cyclic Ketones, Mesut Boz, Ömer Zai̇m, Hi̇lal Esen Jan 2009

A Convenient Synthesis Of 2-Azido And 2-Thiocyanato-2,3-Unsaturated Cyclic Ketones, Mesut Boz, Ömer Zai̇m, Hi̇lal Esen

Turkish Journal of Chemistry

2-Azido and 2-thiocyanato-2,3-unsaturated ketones were synthesized by utilizing functionalization of 5- or 6-membered cycloalkane-1,2-diones, namely diosphenols, with dimethylthiocarbomoyl chloride, which activates the system towards reaction with nucleophiles in acidic conditions. Replacement of the enolic oxygen of the diosphenols with azide and thiocyanate may be achieved by treating their dimethylthiocarbamates with sodium azide or potassium thiocyanate in boiling acetonitrile/acetic acid.

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Silver Ion-Assisted Ring Expansions In Different Solvent Systems, Mesut Boz, Hafi̇ze Çalişkan, Ömer Zai̇m Jan 2009

Silver Ion-Assisted Ring Expansions In Different Solvent Systems, Mesut Boz, Hafi̇ze Çalişkan, Ömer Zai̇m

Turkish Journal of Chemistry

Several ring expansion products carrying vinylic bromo functionality were synthesized by opening of the geminal dibromobicyclo[n.1.0]alkanes ring. Dibromocarbene was formed from bromoform and potassium tert-butoxide in hexane. Its reaction with various cyclic alkenes was the resultant dibromobicyclo[n.1.0]alkanes. Then, opening was performed using AgNO_3 in various solvent systems, such as acetic acid/DMSO, acetic acid/DMF, CH_3OH/acetone, and H_2O/DMF.

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Study Of The Polymerization Of Methyl Methacrylate Initiated By Thioxanthone Derivatives: A Magnetic Field Effect, Sevnur Keski̇n, Meral Aydin, Igor Khudyakov, Nergi̇z Arsu Jan 2009

Study Of The Polymerization Of Methyl Methacrylate Initiated By Thioxanthone Derivatives: A Magnetic Field Effect, Sevnur Keski̇n, Meral Aydin, Igor Khudyakov, Nergi̇z Arsu

Turkish Journal of Chemistry

Free radical photopolymerization of methyl methacrylate (MMA) initiated by 2-mercaptothioxanthone (TX-SH), thioxanthone-thioacetic acid (TXSCH_2COOH), and thioxanthone-carboxymethoxy acetic acid (TXOCH_2COOH) as so called one-component initiators was performed with and without an external magnetic field (MF). These initiators contain light-absorbing and electron/hydrogen-donating fragments in one molecule and do not require an additional hydrogen donor, and initiate the polymerization of MMA in the air. Polymerization experiments were performed in solutions with 3 different optical densities at \lambda 365 nm, where the photoinitiator absorbs. It was observed that application of MF leads to both larger conversion and higher molecular weight of the prepared PMMA, …

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Improved Photostability Of Pvc Films In The Presence Of 2-Thioacetic Acid-5-Phenyl-1,3,4-Oxadiazole Complexes, Emad A. Yousif, Salah A. Aliwi, Ameer A. Ameer, Jaleel R. Ukal Jan 2009

Improved Photostability Of Pvc Films In The Presence Of 2-Thioacetic Acid-5-Phenyl-1,3,4-Oxadiazole Complexes, Emad A. Yousif, Salah A. Aliwi, Ameer A. Ameer, Jaleel R. Ukal

Turkish Journal of Chemistry

The photostabilization of poly(vinyl chloride) (PVC) films by 2-thioacetic acid-5-phenyl-1,3,4-oxadiazole with Sn(II), Ba(II), Ni(II), Zn(II), Cu(II), and Ca(II) complexes was investigated. PVC films containing different concentrations of complexes ranging from 0.1% to 0.5% by weight were produced by the same casting method from THF solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and polyene indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (\Phi _{cs}) of these complexes in PVC films was evaluated …

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Synthesis And Evaluation Of Phenytoin Derivatives As Anticonvulsant Agents, Meenakshi Deodhar, Pravin Sable, Ashok Bhosale, Kapil Juvale, Rahul Dumbare, Pramod Sakpal Jan 2009

Synthesis And Evaluation Of Phenytoin Derivatives As Anticonvulsant Agents, Meenakshi Deodhar, Pravin Sable, Ashok Bhosale, Kapil Juvale, Rahul Dumbare, Pramod Sakpal

Turkish Journal of Chemistry

2,5-Dioxo-4,4-diphenylimidazolidine-1-carboxylic acid (2) was reacted with methyl ester of different amino acids (1a-c) and substituted benzhydrols (3a-b) in pyridine and in the presence of N,N dicyclohexyl carbodiimide (DCC) to yield a series of the title compounds, methyl 2-(2,5-dioxo-4,4-diphenylimidazolidine-1-carboxamido) substituted propanoate (4a-c) and benzhydryl 2,5-dioxo-4,4-diphenyl imidazolidine-1-carboxylate (5a-b). The structures of these compounds were established on the basis of their spectral (IR, ^1H-NMR) data. These newly synthesized derivatives of phenytoin were evaluated in terms of anticonvulsant activity.

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A Density Functional Theory Study Of Oxidation Of Benzene To Phenol By N_2o On Fe- And Co-Zsm-5 Clusters, Mehmet Ferdi̇ Fellah, Işik Önal Jan 2009

A Density Functional Theory Study Of Oxidation Of Benzene To Phenol By N_2o On Fe- And Co-Zsm-5 Clusters, Mehmet Ferdi̇ Fellah, Işik Önal

Turkish Journal of Chemistry

Density functional theory (DFT) calculations were carried out in the study of oxidation of benzene to phenol by N_2O on relaxed [(SiH_3)_4AlO_4M] (where M=Fe, Co) cluster models representing Fe- and Co-ZSM-5 surfaces. The catalytic cycle steps are completed for both Fe-ZSM-5 and Co-ZSM-5 clusters. The general trend of the results that were obtained in terms of activation barriers for the Fe-ZSM-5 cluster is in agreement with the experimental and theoretical literature. It was observed that the phenol formation step is the rate-limiting step for both clusters and Co-ZSM-5 surface has a lower activation barrier than the Fe-ZSM-5 surface (i.e. 35.82 …

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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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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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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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A Novel Naphthoquinone Glycoside From Rubia Peregrina L., Ufuk Özgen, Cavi̇t Kazaz, Hasan Seçen, İhsan Çaliş, Maksut Coşkun, Peter J. Houghton Jan 2009

A Novel Naphthoquinone Glycoside From Rubia Peregrina L., Ufuk Özgen, Cavi̇t Kazaz, Hasan Seçen, İhsan Çaliş, Maksut Coşkun, Peter J. Houghton

Turkish Journal of Chemistry

A phytochemical study was performed on the subterranean parts (roots and rhizomes) of Rubia peregrina. The substances were isolated from chloroform, ethyl acetate, and water soluble parts of the methanolic extract using several chromatographic techniques. 1-Hydroxy-2-methyl-9,10-anthraquinone (1), 1,3-dihydroxy-2-methyl- 9,10-anthraquinone (2), and 1,3-dihydroxy-2-methoxymethyl-9,10- anthraquinone (3) were isolated from the chloroform phase; and asperuloside (4), asperulosidic acid (5), rubiadin 3-O-\beta-primeveroside (6), lucidin 3-O-\beta -primeveroside (7), deacetylasperulosidic acid (8), liriodendrin (9), and a new naphthoquinone glycoside, 2-hydroxy-3-O-\beta-primeveroside naphthalene-1,4-dione (inkumoside, 10), from the aqueous phase. The structures of the compounds were elucidated by means of spectral analysis (^1H-NMR, ^{13}C-NMR, 2D-NMR--COSY, HMBC, HMQC-, EI-MS and …

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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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Comparison Of Photochromic Properties And Thermal Stabilities Of Fulgide, Fulgimide, And Benzimidazole[1,2-A]Pyrrolidine-2-One Derivatives, Mahmut Köse, Ersi̇n Orhan Jan 2009

Comparison Of Photochromic Properties And Thermal Stabilities Of Fulgide, Fulgimide, And Benzimidazole[1,2-A]Pyrrolidine-2-One Derivatives, Mahmut Köse, Ersi̇n Orhan

Turkish Journal of Chemistry

New thermally stable photochromic fulgimides and benzimidazole[1,2-a]pyrrolidin-2-one derivatives of furylfulgide and thienylfulgide were prepared and their photochromic properties were investigated. Thermal stabilities of some of the new isomers in an alcoholic solution and in PMMA (poly(methyl methacrylate)) polymer films, and pyrolytic behaviors in inert atmosphere with TGA were compared. The colored form of fulgimide and that of benzimidazole[1,2-a]pyrrolidin- 2-one derivatives showed large bathochromic shifts for visible absorption maximum compared with the colored form of corresponding fulgides. The imides and benzimidazole[1,2-a]pyrrolidin-2-one derivatives of fulgide displayed better thermal stability than corresponding fulgides.

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Synthesis Of Methyl (E)-2',4''-Thiazachalcones And Their N-Alkyl Derivatives, Photochemistry With Theoretical Calculations And Antimicrobial Activities, Asu Usta, Ahmet Yaşar, Nuran Yayli, Şengül Alpay Karaoğlu, Nuretti̇n Yayli Jan 2009

Synthesis Of Methyl (E)-2',4''-Thiazachalcones And Their N-Alkyl Derivatives, Photochemistry With Theoretical Calculations And Antimicrobial Activities, Asu Usta, Ahmet Yaşar, Nuran Yayli, Şengül Alpay Karaoğlu, Nuretti̇n Yayli

Turkish Journal of Chemistry

A series of 9 new (E)-thiazachalcones (1-3), and their N-alkyl substituted derivatives (4-6), and stereoselective dimerization products (7-9) were synthesized, then tested for antimicrobial activity against all test microorganisms except Pseudomonas aeruginosa. The new compounds (1-6) without dimerization products (7-9) showed good antimicrobial property against Staphylococcus aureus, Listeria monocitogenes, and Enterococcus faecalis. The possible dimerization products of compounds (1-3) were calculated theoretically. Experimental and theoretical calculation showed that \delta-truxinic type dimer is the most stable isomer.

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A Highly Soluble Asymmetric Perylene-Bis (Dicarboximide)-Acceptor System Incorporating A Methylene Bridged Methoxybenzene-Donor: Solvent Dependence Of Charge Transfer Interactions, Rene M. Williams Jan 2009

A Highly Soluble Asymmetric Perylene-Bis (Dicarboximide)-Acceptor System Incorporating A Methylene Bridged Methoxybenzene-Donor: Solvent Dependence Of Charge Transfer Interactions, Rene M. Williams

Turkish Journal of Chemistry

The synthesis and photophysical properties of an asymmetrically substituted perylene-bis(dicarboximide), (PDI), system (1) containing a methylene bridged 4-methoxy-benzene donor and a solubilizing branched C_{13} alkyl chain are described. As compared to most PDIs, the fluorescence of 1 is strongly quenched in polar (but not in non-polar) solvents due to a photo-induced electron transfer process. Transient absorption spectroscopy and time resolved emission in e.g. acetonitrile indicates that upon excitation the radical anion of the PDI is formed with a rate of ca. 3.5 \times 10^9s^{-1}, and the charge transfer state has a lifetime of ca. 3 ns. A Frontier Molecular Orbital …

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Secondary Metabolites From Nepeta Heliotropifolia, Zühal Güvenalp, Hi̇lal Özbek, Ayşe Kuruüzüm-Uz, Cavi̇t Kazaz, L. Ömür Demi̇rezer Jan 2009

Secondary Metabolites From Nepeta Heliotropifolia, Zühal Güvenalp, Hi̇lal Özbek, Ayşe Kuruüzüm-Uz, Cavi̇t Kazaz, L. Ömür Demi̇rezer

Turkish Journal of Chemistry

Two iridoid glycosides, ixoroside (1) and nepetanudoside B (2); 1 phenylpropanoid glycoside, coniferine (3); 2 flavone glycosides, apigenin 7-O-glucuronide (4) and apigenin 7-O-glucopyranoside (5); 2 triterpenes, oleanolic acid (6) and ursolic acid (7); and 1 sterol, \beta-sitosterol (8), were isolated from the aerial parts of Nepeta heliotropifolia Lam. (Lamiaceae). Their structures were identified by means of spectroscopic methods (1D- and 2D-NMR, UV, and EIMS).

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Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay Jan 2009

Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay

Turkish Journal of Chemistry

Fe-PILCs via different conditions using smectites from Hancili (Turkey) and Wyoming (USA) were synthesised. Presaturation had little effects on the basal spacing values while it had important effects on thermal stabilities of the products. Products having basal spacing (d_{001}) around 1.30 nm and surface area up to 160 m^2 g^{-1} were obtained. The thermal behaviour, X-ray diffraction (XRD) patterns, and nitrogen adsorption/desorption experiments confirmed that thermally stable and micro-mesoporous products were obtained although at elevated calcination temperature. Delaminated sample with basal spacing value of 2.79 nm was obtained. Surface acidity of clay was enhanced by pillaring. Chemically sorbed pyridine Fourier …

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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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4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol Jan 2009

4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol

Turkish Journal of Chemistry

A series of 3-hydroxy-6-methyl-2-((4-substitutedpiperazin-1- yl)methyl)-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperazine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli, S. paratyphi, S. flexneri, E. gergoviae, and M. smegmatis were assessed in vitro by using broth dilution for determination of the minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. Among the synthesized compounds; compound 7 showed a 4 \mu g/mL MIC value for M. smegmatis, whereas the other compounds demonstrated moderate to high activity. Those tested in the supercoiling …

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A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan Jan 2009

A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan

Turkish Journal of Chemistry

Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the oxide layer formed on a copper disc electrode and the changes that took place when treated potentiostatically in the range of -0.3 V to 0.9 V in aqueous buffer solution of pH 9.2. Equivalent circuits were used to model the response of the electrode, initially at equilibrium to an applied potential. These circuits were proposed for different potential ranges in order to illustrate the Cu/oxide/electrolyte system and its properties in terms of 2 interfaces. A criterion for the applicability of equivalent circuit models was discussed. Changes in the …

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The Third Space: The Use Of Self-Study To Examine The Culture Of A Science Classroom, Dashia M. Magee Jan 2009

The Third Space: The Use Of Self-Study To Examine The Culture Of A Science Classroom, Dashia M. Magee

Dissertations and Theses @ UNI

Science educators are in the position to create bridges between their students and the world of science (Aikenhead, 1996, 1999). This connection has often been described as the third space (Bhabha, 1994; Moje, Collazo, Carrillo, & Marx, 2001; Wallace, 2004), which is represented as a combination or a meeting of the students' world and the world of science. In this study, I examined my role in creating the third space through the use of self-study. Self-study is a form of research, educators use to understand their practice (Austin & Senese, 2004; Loughran, 2004; Northfield & Loughran, 1996). It is a …

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Geobiology: Evidence For Early Life On Earth And The Search For Life On Other Planets, Sherry L. Cady, Nora Noffke Jan 2009

Geobiology: Evidence For Early Life On Earth And The Search For Life On Other Planets, Sherry L. Cady, Nora Noffke

OES Faculty Publications

Extensive research efforts in the subdisciplinary field of geobiology have focused on the interactions between Earth and life through time. As a consequence, gaps in our knowledge of Earth’s history are closing, and the search for life beyond Earth is expanding. A few examples of geobiology studies designed to advance our understanding of life on early Earth and to improve the chances of finding life on other planets are provided to highlight recent developments and research areas that are on the verge of new discoveries.

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Introducing Interior-Point Methods For Introductory Operations Research Courses And/Or Linear Programming Courses, Goran Lesaja Jan 2009

Introducing Interior-Point Methods For Introductory Operations Research Courses And/Or Linear Programming Courses, Goran Lesaja

Mathematical Sciences: Faculty Publications

In recent years the introduction and development of Interior-Point Methods has had a profound impact on optimization theory as well as practice, influencing the field of Operations Research and related areas. Development of these methods has quickly led to the design of new and efficient optimization codes particularly for Linear Programming. Consequently, there has been an increasing need to introduce theory and methods of this new area in optimization into the appropriate undergraduate and first year graduate courses such as introductory Operations Research and/or Linear Programming courses, Industrial Engineering courses and Math Modeling courses. The objective of this paper is …

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Early Neoproterozoic Origin Of The Metazoan Clade Recorded In Carbonate Rock Texture: Reply, Fritz Neuweiler, Elizabeth C. Turner, David J. Burdige Jan 2009

Early Neoproterozoic Origin Of The Metazoan Clade Recorded In Carbonate Rock Texture: Reply, Fritz Neuweiler, Elizabeth C. Turner, David J. Burdige

OES Faculty Publications

We (Neuweiler et al., 2009) used scanning electron microscopic, fluorescence spectroscopic, fluorescence microscopic, and thin-section analytical work from modern, Cretaceous, Silurian, and early Neoproterozoic reefal material to make a geological case for an early Neoproterozoic origin of animals. In a modern analogue for ancient petrographic textures, degradative calcification of the extracellular collagenous matrix (ECM) of a modern siliceous sponge can be directly observed (Neuweiler et al., 2007).

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Cirene Air-Sea Interactions In The Seychelles-Chagos Thermocline Ridge Region, J. Vialard, J. P. Duvel, M. J. Mcphaden, P. Bouruet-Aubertot, B. Ward, E. Key, D. Bourras, R. Weller, P. Minnett, A. Weil Jan 2009

Cirene Air-Sea Interactions In The Seychelles-Chagos Thermocline Ridge Region, J. Vialard, J. P. Duvel, M. J. Mcphaden, P. Bouruet-Aubertot, B. Ward, E. Key, D. Bourras, R. Weller, P. Minnett, A. Weil

OES Faculty Publications

A field experiment in the southwestern Indian Ocean provides new insights into ocean-atmosphere interactions in a key climatic region.

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Thin Layer Formation During Runaway Stratification In The Tidally Dynamic San Francisco Estuary, Alexander B. Bochdansky, Stephen M. Bollens Jan 2009

Thin Layer Formation During Runaway Stratification In The Tidally Dynamic San Francisco Estuary, Alexander B. Bochdansky, Stephen M. Bollens

OES Faculty Publications

During the course of a year, we repeatedly collected high-resolution vertical fluorometer data timed to coincide with a specific state during the tidal cycle. The time (end of the ebb during neap tide) and the location (a deep channel half-way between the Golden Gate and the point of tidally averaged bottom salinity of 2 psu) were chosen with the goal to observe runaway stratification. We consistently found at least one pronounced chlorophyll peak in the water column; however, the vertical location of these peaks varied within three types including surface, bottom and subsurface maxima. Our results showed that heterogeneity of …

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A Robust, Multisite Holocene History Of Drift Ice Off Northern Iceland: Implications For North Atlantic Climate, John T. Andrews, Dennis A. Darby, Dennis Eberle, Anne E. Jennings, Matthias Moros, Astrid Ogilvie Jan 2009

A Robust, Multisite Holocene History Of Drift Ice Off Northern Iceland: Implications For North Atlantic Climate, John T. Andrews, Dennis A. Darby, Dennis Eberle, Anne E. Jennings, Matthias Moros, Astrid Ogilvie

OES Faculty Publications

An important indicator of Holocene climate change is provided by evidence for variations in the extent of drift ice. A proxy for drift ice in Iceland waters is provided by the presence of quartz. Quantitative xray diffraction analysis of the < 2 mm sediment fraction was undertaken on 16 cores from around Iceland. The quartz weight (wt.)% estimates from each core were integrated into 250-yr intervals between −0.05 and 11.7 cal. ka BP. Median quartz wt.% varied between 0.2 and 3.4 and maximum values ranged between 2.8 and 11.8 wt.%. High values were attained in the early Holocene and minimum values were reached 6–7 cal. ka BP. Quartz wt.% then rose steadily during the late Holocene. Our data exhibit no correlation with counts on haematite-stained quartz (HSQ) grains from VM129-191 west of Ireland casting doubt on the ice-transport origin. A pilot study on the provenance of Fe oxide grains in two cores that cover the last 1.3 and 6.1 cal. ka BP indicated a large fraction of the grains between 1 and 6 cal. ka BP were from either Icelandic or presently unsampled sources. However, there was a dramatic increase in Canadian and Russian sources from the Arctic Ocean ~1 cal. ka BP. These data may indicate the beginning of an Arctic Oscillation-like climate mode.

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Mild And Efficient Iodination Of Aromatic Compounds With Trichloroisocyanuric Acid/I_2/Wet Sio_2 System, Batool Akhlaghinia, Marzieh Rahmani Jan 2009

Mild And Efficient Iodination Of Aromatic Compounds With Trichloroisocyanuric Acid/I_2/Wet Sio_2 System, Batool Akhlaghinia, Marzieh Rahmani

Turkish Journal of Chemistry

Iodoarenes can be obtained using trichloroisocyanuric acid/I_2/wet SiO_2 system at room temperature with high yield in CH_2Cl_2.

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