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2009

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Book Review: Helping Students Learn In A Learner-Centered Environment By Terry Doyle (Stylus, 2008), Delena Bell Gatch Jan 2009

Book Review: Helping Students Learn In A Learner-Centered Environment By Terry Doyle (Stylus, 2008), Delena Bell Gatch

Physics & Astronomy: Faculty Publications

Excerpt: According to Terry Doyle in his book Helping Students Learn in a Learner-Centered Environment, “Most important, this book has been written to answer the single most asked question I hear when working with faculty groups: How do I help my students adjust to a learner-centered practice?” As desired, Doyle has offered some excellent answers for faculty struggling to transform their students into lifelong learners.

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Comment On "On The Theory Of Nuclear Resonant Forward Scattering Of Synchrotron Radiation", Gilbert R. Hoy, Jos Odeurs Jan 2009

Comment On "On The Theory Of Nuclear Resonant Forward Scattering Of Synchrotron Radiation", Gilbert R. Hoy, Jos Odeurs

Physics Faculty Publications

Recently, in a paper by Kohn and Smirnov, a formula previously derived by Kagan et al. was developed to explain the forward scattering of gamma radiation by a nuclear-resonant sample excited by pulsed synchrotron radiation. Their derivation followed, directly, a procedure developed by Heitler, Harris, and Hoy. Previously, a completely different formula was developed by Hoy et al. to explain the same process. As a result, Kohn and Smirnov discuss the correctness and validity of the two models. In this Comment a detailed numerical comparison of the two theories has also been made. It is shown that their comparison is …

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Electrochemical And Optical Properties Of An Azo Dye Based Conducting Copolymer, Ati̇lla Ci̇haner, Fati̇h Algi Jan 2009

Electrochemical And Optical Properties Of An Azo Dye Based Conducting Copolymer, Ati̇lla Ci̇haner, Fati̇h Algi

Turkish Journal of Chemistry

The electrochemical and optical properties of a novel conducting copolymer called poly(2,5'-dimethyl-[4-(2,5-di-thiophen- 2-yl-pyrrol-1-yl)-phenyl]azobenzene-co-(3,4-ethylenedioxythiophene)) (poly(1-co-EDOT)) are reported. Electrochemically synthesized poly(1-co-EDOT) based on the azo dye has a well-defined and reversible redox couple (0.37 V vs. Ag/AgCl) with good cycle stability. The copolymer film exhibits high conductivity (13 S/cm) as well as electrochromic behavior (magenta when neutralized and transmissive sky blue when oxidized). Furthermore, electro-optically active copolymer film has a low band gap of 1.79 eV with a \pi-\pi* transition at 555 nm.

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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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Three-Component Process For The Synthesis Of Some Pyrrole Derivatives Under Microwave Irradiation, Farhad Hatamjafari, Nasser Montazeri Jan 2009

Three-Component Process For The Synthesis Of Some Pyrrole Derivatives Under Microwave Irradiation, Farhad Hatamjafari, Nasser Montazeri

Turkish Journal of Chemistry

We report a short and efficient 3-component reaction for synthesis of a series of [1,2-b]pyrrole derivatives from ninhydrin, alkyl propiolates, and simple primary amines under solvent free and microwave irradiation. This method provides a new route to produce pyrrole derivatives in good to excellent yields.

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Synthesis, Characterization, And Antibacterial Activity Of Some Transition Metals With The Schiff Base N-(2-Furanylmethylene)-3-Aminodibenzofuran, Aurora Reiss, Stelian Florea, Theodor Caproiu, Nicolae Stanica Jan 2009

Synthesis, Characterization, And Antibacterial Activity Of Some Transition Metals With The Schiff Base N-(2-Furanylmethylene)-3-Aminodibenzofuran, Aurora Reiss, Stelian Florea, Theodor Caproiu, Nicolae Stanica

Turkish Journal of Chemistry

This paper presents the structure and antibacterial properties of some complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) with a new Schiff base N-(2-furanylmethylene)-3- aminodibenzofuran. The structure of each complex was characterized by spectroscopic methods (IR, UV-Vis, ^1H-NMR, and ESR), conductometric and magnetic data, and thermogravimetric and elementary analysis. According to these data, we propose an octahedral geometry for Co(II), Ni(II), and Cu(II) complexes, and a tetrahedral geometry for Zn(II), Cd(II), and Hg(II) complexes. Antibacterial activity of the ligand and its complexes was tested against selected bacteria. The ligand and all the complexes possess antimicrobial activity, and antimicrobial activity …

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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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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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Cover And Contents Jan 2009

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

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Development Of Alumina Supported Alkaline Catalysts Used For Biodiesel Production, Oğuzhan İlgen, Ayşe Ni̇lgün Akin Jan 2009

Development Of Alumina Supported Alkaline Catalysts Used For Biodiesel Production, Oğuzhan İlgen, Ayşe Ni̇lgün Akin

Turkish Journal of Chemistry

The transesterification of canola oil with methanol was studied in a heterogeneous system, using \gamma-Al_2O_3 supported alkaline catalysts. All the catalysts were prepared by incipient-wetness impregnation of an aqueous solution of alkaline compounds on \gamma-Al_2O_3 support. The effects of alkaline compound, methanol/canola oil molar ratio, reaction temperature, catalyst amount, and reaction time in biodiesel production were investigated. The catalyst with KOH loaded on \gamma-Al_2O_3 gave the highest basicity and the best catalytic activity for this reaction. The highest FAME yield obtained was 89.40%.

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Synthesis And Biological Activity Of 4-(4-Hydroxybenzylidene)-2- (Substituted Styryl) Oxazol-5-Ones And Their O-Glucosides, Vijay Taile, Kishor Hatzade, Pravin Gaidhane, Vishwas Ingle Jan 2009

Synthesis And Biological Activity Of 4-(4-Hydroxybenzylidene)-2- (Substituted Styryl) Oxazol-5-Ones And Their O-Glucosides, Vijay Taile, Kishor Hatzade, Pravin Gaidhane, Vishwas Ingle

Turkish Journal of Chemistry

The 4-(4-hydroxybenzylidene)-2-methyl oxazol-5-ones 1 were treated with various aldehydes in the presence of acetic acid to form 4-(4-hydroxybenzylidene)-2-(substituted styryl) oxazol-5-ones 2a-i, which were glucosylated using \alpha-acetobromoglucose as a glucosyl donor to afford 4-(4-o-\beta-d-tetra-o-acetyl-glucoxybenzylidene)-2- (substituted styryl) oxazol-5-ones 3a-i, which were deacetylated using zinc acetate in absolute methanol to form 4-(4-o-\beta-d-glucoxybenzylidene)- 2-(substituted styryl) oxazol-5-ones 4a-i. The compounds showed good antimicrobial and antifungal activity.

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Investigation Of Biodiesel Production From Canola Oil Using Amberlyst-26 As A Catalyst, Oğuzhan İlgen, Ayşe Ni̇lgün Akin, Nezahat Boz Jan 2009

Investigation Of Biodiesel Production From Canola Oil Using Amberlyst-26 As A Catalyst, Oğuzhan İlgen, Ayşe Ni̇lgün Akin, Nezahat Boz

Turkish Journal of Chemistry

The transesterification of canola oil to fatty acid methyl esters was studied using Amberlyst-26 as a solid catalyst. The influence of reaction conditions, such as the reaction time, methanol to oil molar ratio, amount of catalyst, effect of co-solvent, and alcohol and oil types, were determined. When the reaction was carried out at 45 °C with a canola oil to methanol molar ratio of 6:1, a reaction time of 1.5 h, and 3 wt.% of catalyst, oil conversion was about 67%. Methanol was much more reactive than ethanol and isopropyl alcohol (IPA) in the transesterification reaction. The conversion of canola …

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[Pd(Me-Xanthate)_2]: Synthesis, Characterization, And X-Ray Structure, Saira Shahzadi, Saqib Ali, Rehana Jabeen, Muhammad Kaleem Khosa Jan 2009

[Pd(Me-Xanthate)_2]: Synthesis, Characterization, And X-Ray Structure, Saira Shahzadi, Saqib Ali, Rehana Jabeen, Muhammad Kaleem Khosa

Turkish Journal of Chemistry

Potassium methyl xanthate and its complex [Pd(Me-Xanthate)_2] were synthesized at room temperature under stirring conditions. The ligand and the complex were characterized by elemental analysis, IR, NMR (^1H, ^{13}C) and XRD. NMR data revealed that potassium methyl xanthate acts as a bidentate specie and the complex exhibits 4-coordinated geometry in solution. In solid state, the palladium atom is coordinated to the 2 sulfur atoms of the xanthate ligand and the complex exhibits distorted square planar geometry.

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Cover And Contents Jan 2009

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

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Synthesis Of 5-Arylamino-1h (2h)-Tetrazoles And 5-Amino-1-Aryl-1h-Tetrazoles From Secondary Arylcyanamides In Glacial Acetic Acid: A Simple And Efficient Method, Ali Reza Modarresi-Alam, Mahmoud Nasrollahzadeh Jan 2009

Synthesis Of 5-Arylamino-1h (2h)-Tetrazoles And 5-Amino-1-Aryl-1h-Tetrazoles From Secondary Arylcyanamides In Glacial Acetic Acid: A Simple And Efficient Method, Ali Reza Modarresi-Alam, Mahmoud Nasrollahzadeh

Turkish Journal of Chemistry

A simple and efficient method for the preparation of 5-arylamino-1H (2H)-tetrazoles (3a-i) and 5-amino-1-ary-1H-tetrazoles (4a-i), with excellent yields and high purity, from secondary arylcyanamides (1a-i) at room temperature in glacial acetic acid is described. Tautomers 3a-i were separated from tautomers 4a-i by crystallization in ethanol. A mechanism was introduced in glacial acetic acid. The ratio of isomers is described based on the electronic and steric effects of various substituents. The electron withdrawing group (-NO_2) increased the ratio of 4:3. The rate of product formation was enhanced by introducing electron donating substituents. ^1H-NMR and ^{13}C-NMR chemical shifts and multiplicities are also …

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Ferric Hydrogen Sulfate As An Efficient Heterogeneous Catalyst For Environmentally Friendly Greener Synthesis Of 1,8-Dioxo-Octahydroxanthenes, Hamid Reza Shaterian, Asghar Hosseinian, Majid Ghashang Jan 2009

Ferric Hydrogen Sulfate As An Efficient Heterogeneous Catalyst For Environmentally Friendly Greener Synthesis Of 1,8-Dioxo-Octahydroxanthenes, Hamid Reza Shaterian, Asghar Hosseinian, Majid Ghashang

Turkish Journal of Chemistry

Ferric hydrogen sulfate was used as an environmentally friendly heterogeneous acidic catalyst for the greener, 1-pot, 3-component synthesis of 1,8-dioxo-octahydroxanthene via condensation reactions between aromatic aldehydes and dimedone under solvent-free thermal and microwave irradiation as well as in aqueous media conditions in short periods of times with excellent yields. The catalyst was easily separated in simple work-up and was recycled several times without loss of reactivity under the described reaction conditions.

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The Role Of The Entropy Factor On The Adsorption Of An Optical Brightener On Pulp, Greta Radeva, Eva Valcheva, Stefka Veleva Jan 2009

The Role Of The Entropy Factor On The Adsorption Of An Optical Brightener On Pulp, Greta Radeva, Eva Valcheva, Stefka Veleva

Turkish Journal of Chemistry

The present paper reports results of the thermodynamic study of adsorption of 2 optical brighteners (Tinopal UP and Leucophor AP) on pulp. The entropy non-homogeneity of the pulp surface was confirmed and the coefficients of entropy non-homogeneity were determined. The entropy effect on the variation of Gibbs free energy of the process studied was followed.

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Synthesis, Spectral Characterization, And Antimicrobial Activity Of Arsenic(Iii) And Bismuth(Iii) Tri[3(2´-Hydroxyphenyl)-5-(4-Subsituted Phenyl)Pyrazolinates], Umesh Nath Tripathi, Afshan Siddqui, Jeeven Singh Solanki, Mohammad Safi Ahmad, Arpan Bhardwaj, Tulsi Ram Thapak Jan 2009

Synthesis, Spectral Characterization, And Antimicrobial Activity Of Arsenic(Iii) And Bismuth(Iii) Tri[3(2´-Hydroxyphenyl)-5-(4-Subsituted Phenyl)Pyrazolinates], Umesh Nath Tripathi, Afshan Siddqui, Jeeven Singh Solanki, Mohammad Safi Ahmad, Arpan Bhardwaj, Tulsi Ram Thapak

Turkish Journal of Chemistry

Arsenic(III) tripyrazolinates and bismuth(III) tripyrazolinates of the type M(C_{15}H_{12}N_2OX)_3 [where C_{15}H_{12}N_2OX = 3(2'-hydroxyphenyl)-5-(4-substituted phenyl)pyrazoline] have been synthesized by the reaction of MCl_3 and sodium salt of pyrazolines in 1:3 molar ratio in anhydrous benzene at elevated temperature. These newly synthesized derivatives have been characterized by elemental analysis (C, H, N, As, and Bi), molecular weight measurement, spectral [IR and multinuclear NMR (^1H & ^{13}C)] and x-ray diffraction studies. The bonding mode of pyrazolines and coordination no. of arsenic(III) and bismuth(III) in these derivatives have been discussed. Antibacterial and antifungal potential of free pyrazoline and some arsenic(III) tripyrazolinates and bismuth(III) tripyrazolinates …

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Water-Gas Shift Reaction Over Bimetallic Pt-Ni/Al_2o_3 Catalysts, Burcu Selen Çağlayan, Ahmet Erhan Aksoylu Jan 2009

Water-Gas Shift Reaction Over Bimetallic Pt-Ni/Al_2o_3 Catalysts, Burcu Selen Çağlayan, Ahmet Erhan Aksoylu

Turkish Journal of Chemistry

The water-gas shift (WGS) activity of bimetallic Pt-Ni/Al_2O_3 catalysts was investigated in the temperature range 200-450 °C using an idealized feed composition consisting of 3% CO and 6%-10% H_2O. The effects of the Ni content, space velocity, and H_2O/CO ratio on the catalytic performance of the catalysts were studied. An increase in the Ni content and H_2O/CO ratio shifted the carbon monoxide conversion--temperature curve toward lower reaction temperatures. No detectable methane formation was observed in the catalytic reaction tests. The results indicate that Pt-Ni/Al_2O_3 catalysts are highly selective and active for water-gas shift reactions under idealized conditions.

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The Effect Of Electrocatalytic Activity And Crystal Structure Of Pbo_2 Surfaces On Polyphenylene Oxide (Ppo) Production In Acetonitrile, Serdar Abaci, Atti̇la Yildiz Jan 2009

The Effect Of Electrocatalytic Activity And Crystal Structure Of Pbo_2 Surfaces On Polyphenylene Oxide (Ppo) Production In Acetonitrile, Serdar Abaci, Atti̇la Yildiz

Turkish Journal of Chemistry

The crystallographic nature of PbO_2 films was changed by optimizing the electrolysis conditions in an electrodeposition solution of PbO_2. These PbO_2 films were then used to prepare PPO films. It was determined that \alpha and \beta modifications, and relative degrees of crystallinity had profound effects on the electrocatalytic performance of PbO_2 films in the production PPO films.

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A Mild Method For The Cleavage Of Ketals Using Ibx, Abdul Rauf Raza Jan 2009

A Mild Method For The Cleavage Of Ketals Using Ibx, Abdul Rauf Raza

Turkish Journal of Chemistry

Investigation on the total synthesis of batrachotoxin 1 revealed that the cyclic ketals could be cleaved to ketone with IBX in DMSO at 70-81 °C under very mild conditions. A variety of functional groups showed no interference under these conditions except vinyl bromides, which, in fact, inhibits the single electron transfer to IBX.

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Chiral Calixarenes, Abdulkadi̇r Sirit, Mustafa Yilmaz Jan 2009

Chiral Calixarenes, Abdulkadi̇r Sirit, Mustafa Yilmaz

Turkish Journal of Chemistry

No abstract provided.

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Cover And Contents Jan 2009

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

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Quantitative Structure--Retention Study Of Some 2,4-Dioksotetrahydro- 1,3--Thiazole Derivatives Using The Partial Least Squares Method, Tatjana Djakovic-Sekulic, Costel Sarbu, Nada Perisic-Janjic, Zagorka Lozanov-Crvenkovic Jan 2009

Quantitative Structure--Retention Study Of Some 2,4-Dioksotetrahydro- 1,3--Thiazole Derivatives Using The Partial Least Squares Method, Tatjana Djakovic-Sekulic, Costel Sarbu, Nada Perisic-Janjic, Zagorka Lozanov-Crvenkovic

Turkish Journal of Chemistry

Thin-layer chromatography on rice starch support and aqueous ammonia--organic modifier (methanol, dioxane, and acetone) mobile phases was used to study the effect on retention of the chromatographic system and the physicochemical properties of twelve 2,4-dioxotetrahydro-1,3-thiazoles. A multivariate approach to the retention behaviour of the investigated compounds with 3 quite different organic solvents was used to explain the interactions between the 1,3-thiazoles and the mobile phases. Partial least-squares (PLS) regression was used to quantify differences between the observed data and recognize the molecular properties with the greatest effect on retention for each modifier. Good correlation was obtained between experimental and calculated …

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Nitric Oxide Releasing Derivatives Of [(2-Chloroethyl)Ureido] Benzoic Acid Esters As Potential Antineoplastic Agents, Hülya Akgün, Barkin Berk, Di̇lek Demi̇r Erol, Güldem Mercanoğlu, Ömer Faruk Bayrak, Berrak Çağlayan, Asli Dedeağaç, Işil Aksan Kurnaz Jan 2009

Nitric Oxide Releasing Derivatives Of [(2-Chloroethyl)Ureido] Benzoic Acid Esters As Potential Antineoplastic Agents, Hülya Akgün, Barkin Berk, Di̇lek Demi̇r Erol, Güldem Mercanoğlu, Ömer Faruk Bayrak, Berrak Çağlayan, Asli Dedeağaç, Işil Aksan Kurnaz

Turkish Journal of Chemistry

New series of [(2-chloroethyl)ureido] benzoic acids (compounds 3-8) and nitric oxide releasing derivatives of [(2-chloroethyl)ureido] benzoic acid esters (compounds 9-14) were synthesized as potential anti-cancer agents. These compounds were screened for their anti-proliferative activities on A549 (human lung carcinoma) cells and for their cytotoxic effects on L929 (mouse fibroblast) cells. The compounds 3-8 exhibited mild cytotoxic effects on L929 cells (cell viability from 100% to 85% -- 90% only) whereas they had very little anti-proliferative activities towards A549 lung carcinoma cells. On the other hand, compounds 10, 11, and 13 had some growth inhibition activity in A549 (human lung carcinoma) …

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Synthesis And Antimicrobial And Antitumor Activity Of Some New [1,2,4] Triazole-5-One Derivatives, Yasemi̇n Ünver, Esra Düğdü, Kemal Sancak, Mustafa Er, Sengül Alpay Karaoğlu Jan 2009

Synthesis And Antimicrobial And Antitumor Activity Of Some New [1,2,4] Triazole-5-One Derivatives, Yasemi̇n Ünver, Esra Düğdü, Kemal Sancak, Mustafa Er, Sengül Alpay Karaoğlu

Turkish Journal of Chemistry

4-[Arylidene-amino]-3-thiophen-2-ylmethyl-4,5-dihydro[1,2,4]triazole-5-one compounds (3a-g) with Schiff base character were obtained from the reaction of 4-amino-3-thiophen-2-ylmethyl-4,5-dihydro-1H-[1,2,4]triazole-5-one (2) with various aldehydes. 1-(2-Oxo-2-phenyl-ethyl)-4-[arylidene-amino]-3-thiophen-2-ylmethyl-4,5- dihydro-1H-[1,2,4]triazole-5-ones (4a-g) were synthesized from the reaction of corresponding compounds 3a-g with bromoacetophenone. 1-(2-Hydroxy-2-phenyl-ethyl)- 3-thiophen-2-ylmethyl-4-[aryl-amino]4,5-dihydro-1H-[1,2,4]triazole-5-ones (5a-g) and 1-(2-hydroxy-2-phenyl-ethyl)-3-thiophen-2-ylmethyl-4-[arylidene-amino] 4,5-dihydro-1H-[1,2,4]triazole-5-ones (6b,d,e) were obtained from the selective reduction of 1-(2-oxo-2-phenyl-ethyl)-4-[arylidene-amino]-3-thiophen-2ylmethyl- 4,5-dihydro-1H-[1,2,4] triazole-5-ones (4) with NaBH_4. They were characterized by IR, H-NMR,^{13}C-NMR, and elemental analyses. Compounds 2, 3a, 3c, 3g, 4f, 5b, and 5g showed good antifungal activity against yeast-like fungi. Compounds selected by the National Cancer Institute (NCI, USA) were investigated for antitumor activity.

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The Use Of A Lock-In Amplifier To Stabilize The Frequency Of A Laser Diode, Jose M. Juarez Jan 2009

The Use Of A Lock-In Amplifier To Stabilize The Frequency Of A Laser Diode, Jose M. Juarez

College Honors Program

We have designed, constructed, and tested a lock-in amplifier with readily available electronic components and homebuilt analog circuits. Its performance is comparable to that of a commercial unit, but it costs significantly less and is much more compact. The various components of our lock-in amplifier are discussed and the basic principles behind the function and operation of this versatile device are explained. We have also assembled a laser system and used the output signal of our lock-in amplifier in a negative feedback loop to stabilize the frequency of our laser to an atomic reference frequency.

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Sentiment Classification Of Reviews Using Sentiwordnet, Bruno Ohana, Brendan Tierney Jan 2009

Sentiment Classification Of Reviews Using Sentiwordnet, Bruno Ohana, Brendan Tierney

Conference papers

Sentiment classification concerns the use of automatic methods for predicting the orientation of subjective content on text documents, with applications on a number of areas including recommender and advertising systems, customer intelligence and information retrieval. SentiWordNet is an opinion lexicon derived from the WordNet database where each term is associated with numerical scores indicating positive and negative sentiment information. This research presents the results of applying the SentiWordNet lexical resource to the problem of automatic sentiment classification of film reviews. Our approach comprises counting positive and negative term scores to determine sentiment orientation, and an improvement is presented by building …

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Gate-To-Channel Parasitic Capacitance Minimization And Source-Drain Leakage Evaluation In Germanium Pmos, Raymond T. Krom Jan 2009

Gate-To-Channel Parasitic Capacitance Minimization And Source-Drain Leakage Evaluation In Germanium Pmos, Raymond T. Krom

Theses

This work studies the behavior of both gate-to-channel capacitance (CGC) and source-channel-drain/well leakage in metal-gate/high-κ/Ge PMOS technology (W = 10 μm and L = 10; 5; 1 μm) under development at IMEC. The hole drift-mobility of germanium is ~4X that of silicon, leading researchers to evaluate germanium as a possible channel material replacement for PMOS expected at the 32 nm technology node. In particular this study focuses on—but is not restricted to—(1) the presence of a parasitic gate-to-channel capacitance (CGC), the large non-ideal trap assisted conductance which contributes to it, and its function versus Ge-PMOS architecture and gate length; (2) …

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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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