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2008

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Articles 511 - 540 of 713

Full-Text Articles in Chemistry

Potentiometric Utility Of The New Solid-State Sensor Based On Crowned Ionophore For The Determination Of K^+, Bariş Kemer, Mustafa Özdemi̇r Jan 2008

Potentiometric Utility Of The New Solid-State Sensor Based On Crowned Ionophore For The Determination Of K^+, Bariş Kemer, Mustafa Özdemi̇r

Turkish Journal of Chemistry

All solid-state contact poly vinyl chloride (PVC) membrane potassium-selective electrode has been developed. The construction of the ion selective electrode membrane was organized using ionophore 4,4'-bis[4''-phenoxy(15-crown-5) methyl]benzyl in PVC cocktail. The potentiometric performance characteristics of the electrode were investigated by a computerized system. The electrode was found highly selective to K^+ ions over a wide variety of other cations. The electrode almost exhibited a Nernstian response (\ge 55 (\pm15) mV/decade of K activity) to K^+ within the concentration range 1.5 x 10^{-1} - 1.0 \times 10^{-5} M. The operational pH range of the electrode was 5--7. The response time of …

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Novel Analogues Of 2-Pyrazoline: Synthesis, Characterization, And Antimycobacterial Evaluation, Ahmet Özdemi̇r, Gülhan Turan Zitouni, Zafer Asim Kaplancikli Jan 2008

Novel Analogues Of 2-Pyrazoline: Synthesis, Characterization, And Antimycobacterial Evaluation, Ahmet Özdemi̇r, Gülhan Turan Zitouni, Zafer Asim Kaplancikli

Turkish Journal of Chemistry

Fourteen new 1-[(N,N-disubstitutedthiocarbamoylthio)acetyl]- 3-(2-thienyl)-5-aryl-2-pyrazoline derivatives were synthesized by reacting 1-(chloroacetyl)-3-(2-thienyl)-5-aryl-2-pyrazolines and appropriate sodium salts of N,N-disubstituted dithiocarbamoic acids in acetone. The structures of the synthesized compounds were confirmed by UV, IR, ^1H-NMR, and FAB^+-MS spectral data. The compounds were evaluated for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv using the BACTEC 460 radiometric system and BACTEC 12B medium. The preliminary results showed that all of the tested compounds were inactive against the test organism.

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Preparation And Potentiometric Study Of Promethazine Hydrochloride Selective Electrodes And Their Use In Determining Some Drugs, Nabil S. Nassory, Shahbaz A. Maki, Bashaer A. Al-Phalahy Jan 2008

Preparation And Potentiometric Study Of Promethazine Hydrochloride Selective Electrodes And Their Use In Determining Some Drugs, Nabil S. Nassory, Shahbaz A. Maki, Bashaer A. Al-Phalahy

Turkish Journal of Chemistry

Promethazine hydrochloride selective electrodes were constructed based on promethazine-phosphotun- gstic acid ion pair in PVC matrix membrane. The plasticizers used were di-butyl phosphate (DBP), tri-n-butyl phosphate (TBP), o-nitro phenyl octyl ether (ONPOE), and di-n-butyl phthalate (DBPH). The electrodes based on DBP, TBP, and ONPOE gave the same linear range between 1 x 10^{-4} and 1 x 10^{-1} M, while the one based on DBPH ranged between 5 x 10^{-4} and 1 x 10^{-1}M. The slopes for linear range ranged from 40 to 56 mV/decade with correlation coefficients lying between 0.9984 and 0.9993. The best detection limit was 2 x 10^{-5}M …

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Langmuir Aggregation Of Congo Red On Cpc And Its Application, Xiang-Hu Liu, Jiao-Rong Ren, Ya-Nan Huang, Jing Bai, Hong-Wen Gao Jan 2008

Langmuir Aggregation Of Congo Red On Cpc And Its Application, Xiang-Hu Liu, Jiao-Rong Ren, Ya-Nan Huang, Jing Bai, Hong-Wen Gao

Turkish Journal of Chemistry

In this paper, microsurface adsorption-spectral correction technique (MASCT) was used to research the interaction between negatively charged sodium diphenyl diazo-bis-\alpha -naphthylamine-4-sulfonate (Congo Red, CR) and positively charged cetylpyridinium chloride (CPC) in a pH 2.03 BR buffer solution. The experiment results indicate that CR was absorbed on the surface of CPC mainly through electrostatic attraction. This aggregation obeys the Langmuir isothermal adsorption equation. The maximal binding number of CR to CPC was calculated to be 1.2 and the adsorption constant was about 2.03 \times 10^5 L/mol. This CR-CPC binding product is insensitive to a concentrated electrolyte solution, but higher temperature influences …

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Electrocatalytic Oxidation Of Hydroxylamine At A Quinizarine Modified Glassy Carbon Electrode: Application To Differential Pulse Voltammetry Detection Of Hydroxylamine, Mohammad Mazloumardakani, Payam Ebrahimi Karami, Hossein Naeimi, Bibifatemeh Mirjalili Jan 2008

Electrocatalytic Oxidation Of Hydroxylamine At A Quinizarine Modified Glassy Carbon Electrode: Application To Differential Pulse Voltammetry Detection Of Hydroxylamine, Mohammad Mazloumardakani, Payam Ebrahimi Karami, Hossein Naeimi, Bibifatemeh Mirjalili

Turkish Journal of Chemistry

The electrocatalytic behavior of hydroxylamine was studied on a glassy carbon electrode modified by electrodeposition of quinizarine, using cyclic voltammetry, chronoamperometry, and rotating disk voltammetry as diagnostic techniques. Cyclic voltammetry showed that the catalytic current of the system depends on the concentration of hydroxylamine. The magnitude of the peak current for quinizarine increased sharply in the presence of hydroxylamine and proportional to hydroxylamine concentration. The diffusion coefficient of hydroxylamine and the catalytic rate constant for the catalytic reaction of quinizarine with hydroxylamine were also estimated using a rotating disk electrode experiment. The kinetics parameters of this process were calculated, and …

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Thermal Decomposition Of Metal Complexes Of Type Mlx_2 (M = Co(Ii), Cu(Ii), Zn(Ii), And Cd(Ii); L = Die; X = No_3^{1-}) By Tg-Dta-Dtg Techniques In Air Atmosphere, Muhammad Arshad, Saeed Ur-Rehman, Ammad Hussain Qureshi, Khalid Masud, Muhammad Arif, Aamer Saeed, Riaz Ahmed Jan 2008

Thermal Decomposition Of Metal Complexes Of Type Mlx_2 (M = Co(Ii), Cu(Ii), Zn(Ii), And Cd(Ii); L = Die; X = No_3^{1-}) By Tg-Dta-Dtg Techniques In Air Atmosphere, Muhammad Arshad, Saeed Ur-Rehman, Ammad Hussain Qureshi, Khalid Masud, Muhammad Arif, Aamer Saeed, Riaz Ahmed

Turkish Journal of Chemistry

The nitrate complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula M(DIE)(NO_3)_2, where M = Co(II), Cu(II), Zn(II), and Cd(II), were synthesized. The compositions of metal complexes and ligand were investigated by elemental analysis in order to ensure their purity and the structure elucidations were based on conductivity measurements, room temperature magnetic moment studies, proton NMR, and electronic and IR spectra. The thermal behavior of these complexes possessing distorted tetrahedral geometry and their ligand was studied by means of thermoanalytical techniques in static air atmosphere in order to determine their mode of decomposition and thermal stability. All these …

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The Synthesis And Antimicrobial Activity Of \\\\Gamma-Butyrolactone Derivatives, Slobodan Sukdolak, Slavica Solujic-Sukdolak, Nenad Vukovic, Tanja Milosevic Jan 2008

The Synthesis And Antimicrobial Activity Of \\\\Gamma-Butyrolactone Derivatives, Slobodan Sukdolak, Slavica Solujic-Sukdolak, Nenad Vukovic, Tanja Milosevic

Turkish Journal of Chemistry

This paper examines the synthesis of \gamma-butyrolactone compounds 2, 3, 4, 5, and 9, and their potential antimicrobial nature and ability. The structures of all the compounds mentioned above were determined and confirmed with elemental analyses, and IR, ^1H-NMR, and ^{13}C-NMR spectroscopy. The in vitro antimicrobial activity of compounds 2, 3, 4, 5, and 9 was examined and evaluated against the following pathogens: Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Aspergillus niger, and Candida albicans. Compound 5 (20 mg/mL) demonstrated high antimicrobial activity against S. epidermidis, which was closely comparable to the antimicrobial …

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Synthesis And Selective Extractant Properties Of A Calixarene Thioether Derivative And Its Oligomeric Analogue, Gülderen Uysal Akkuş, Selma Aslan, F. Fulya Taktak, Shahabuddin Memon Jan 2008

Synthesis And Selective Extractant Properties Of A Calixarene Thioether Derivative And Its Oligomeric Analogue, Gülderen Uysal Akkuş, Selma Aslan, F. Fulya Taktak, Shahabuddin Memon

Turkish Journal of Chemistry

Herein we report the synthesis of a novel calix[4]arene thioether derivative (4) and its oligomeric analogue (5). The liquid-liquid extraction properties of these compounds towards the selected metal cations were evaluated, and it was concluded, based on our observations, that these compounds demonstrated remarkable affinity towards the selected metal cations. Nevertheless, is a good extractant and very selective for Hg^{2+} ions, whereas, in the case of its oligomeric analogue 5, the situation is quiet different. It was observed that 5 could not efficiently retain the parent selective behavior by extracting all of the selected metal ions from the aqueous to …

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Hydrogenation Of Citral Over Pt And Pt-Sn Catalysts, Hi̇lal Aykaç, Selahatti̇n Yilmaz Jan 2008

Hydrogenation Of Citral Over Pt And Pt-Sn Catalysts, Hi̇lal Aykaç, Selahatti̇n Yilmaz

Turkish Journal of Chemistry

Hydrogenation of citral on monometallic (Pt) and bimetallic (Pt-Sn) catalysts was investigated. It was found that the catalyst activities and product distributions were different over Na-Y and Clino supports. Among monometallic catalysts, Pt/Na-Y was more selective to citronellol (3.9%) and unsaturated alcohols, geraniol and nerol, (14.1%). Sn addition increased the catalyst activities. However, its effect on product distribution differed. Yield of geraniol+nerol changed from 5.1% to 19.7% over Clino. However, selectivity to unsaturated alcohols over Na-Y decreased when it was prepared as a bimetallic catalyst support. Unsaturated alcohol formation was favored when there was a metal support interaction over monometallic …

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Synthesis And Properties Of Novel Photosensitive Poly(Amide-Imide)S Containing Chalcone Moiety And Aromatic Diamines In The Main Chain, Khalil Faghihi, Zohreh Mozafari Jan 2008

Synthesis And Properties Of Novel Photosensitive Poly(Amide-Imide)S Containing Chalcone Moiety And Aromatic Diamines In The Main Chain, Khalil Faghihi, Zohreh Mozafari

Turkish Journal of Chemistry

Six new poly(amide-imide)s were synthesized by the polycondensation reaction of 1,3-bis[4,4'-bis(trimellityimido) phenyl]-2-propenone (6) with 3,3'-diamino diphenyl sulfone (7a), 4,4'-diamino diphenyl sulfone (7b), 4,4'-diamino diphenyl ether (7c), 1,5-diamino naphthalene (7d), 6-phenyl-1,3,5-triazine (7e), and 6-choloro-1,3-diazine (7f) in a medium consisting of N-methyl-2- pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel poly(amide-imide)s (8a-f) in high yield and with inherent viscosities between 0.42 and 0.62 dL/g. The resulting polymers were characterized by elemental analysis, viscosity measurement, solubility testing, thermo-gravimetric analysis (TGA & DTG), FT-IR, and UV-VIS spectroscopy.

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Production Of (S)-(-)-1-(1´-Napthyl) Ethanol By Rhodotorula Glutinis Isolate Using Ram Horn Peptone, Esabi̇ Başaran Kurbanoğlu, Kani̇ Zi̇lbeyaz, Namudar I. Kurbanoğlu, Mesut Taşkin, Hamdullah Kiliç Jan 2008

Production Of (S)-(-)-1-(1´-Napthyl) Ethanol By Rhodotorula Glutinis Isolate Using Ram Horn Peptone, Esabi̇ Başaran Kurbanoğlu, Kani̇ Zi̇lbeyaz, Namudar I. Kurbanoğlu, Mesut Taşkin, Hamdullah Kiliç

Turkish Journal of Chemistry

The bioreduction of 1-acetonaphthone 1 by locally isolated Rhodotorula glutinis strains using ram horn peptone (RHP) gave (S)-(-)-1-(1´-naphthyl) ethanol (2), an important pharmaceutical intermediate. R. glutinis strains were isolated from the water of fermented Salix leaves. Optimum fermentation conditions for the production of 2 were 200 rpm, 32 °C, and pH 6.5. The production of 2 with excellent enantiomeric excess (>99%), and good conversion (100%) and yield (78%) under optimum conditions was achieved up to preparative scale via a fermenter. Wide temperature, pH, time, and agitation ranges did not affect the enantiomeric excess (ee) of the bioreduction product. A …

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High Yielding Oxidative Deprotection Of Silyl And Pyranyl Ethers To Their Corresponding Carbonyl Compounds With Strontium Manganate In The Presence Of Aluminium Chloride In Solution And Under Solvent-Free Conditions, Mostafa Gholizadeh, I. Mohmmadpoor Baltork Jan 2008

High Yielding Oxidative Deprotection Of Silyl And Pyranyl Ethers To Their Corresponding Carbonyl Compounds With Strontium Manganate In The Presence Of Aluminium Chloride In Solution And Under Solvent-Free Conditions, Mostafa Gholizadeh, I. Mohmmadpoor Baltork

Turkish Journal of Chemistry

Strontium manganate (SrMnO_4) in the presence of aluminium chloride (AlCl_3) is an efficient reagent for the high yielding oxidative deprotection of aromatic and aliphatic silyl and pyranyl ethers into their corresponding carbonyl compounds, in solution and under solvent-free conditions.

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Preparation Of Palladium Composite Membranes On Pore Structure Modified And Non-Modified Supports By Electroless Plating Procedure, Sali̇ha Kiliçarslan, Osman Muzaffer Afyon, Meltem Doğan Jan 2008

Preparation Of Palladium Composite Membranes On Pore Structure Modified And Non-Modified Supports By Electroless Plating Procedure, Sali̇ha Kiliçarslan, Osman Muzaffer Afyon, Meltem Doğan

Turkish Journal of Chemistry

The effects of pore structure of the support on the plating morphology, thickness, and composition were investigated in an electroless plating procedure. Some of the plating studies were carried out directly on commercially available porous glass supports, while others were performed on modified supports. Two modification steps with alumina were applied on tubular supports. Formation of a 60-\mu m-thick layer on the modified support was detected by SEM analysis after the first 2 plating steps, while layer formation was not observed on the non-modified support. It was shown that the formation of a new layer started on the modified support, …

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Potentiometric Determination Of The Stability Constants Of Lanthanide Complexes With Iminodiacetic Acid In Water And Dioxane-Water Mixtures, Sevgi̇ Arzik, Ebru Mavi̇oğlu Ayan, A. Sedat Çelebi̇ Jan 2008

Potentiometric Determination Of The Stability Constants Of Lanthanide Complexes With Iminodiacetic Acid In Water And Dioxane-Water Mixtures, Sevgi̇ Arzik, Ebru Mavi̇oğlu Ayan, A. Sedat Çelebi̇

Turkish Journal of Chemistry

The protonation constants of iminodiacetic acid (H_2 ida) and the stability constants of its complexes with Nd(III), Sm(III), Gd(III), Dy(III), and Er(III) ions at metal/ligand mole ratios of 1:1, 1:2, and 1:3 at 25 °C and 0.1 M ionic strength in aqueous medium and 20%, 45%, and 70% w/w dioxane-water mixtures were determined by the potentiometric method using the BEST computer program. The stability constants of the complexes that formed increased as the dioxane content increased. The stability of all the analogues' complexes, both in aqueous medium and in dioxane-water mixtures, were in the order of Nd(III) < Sm(III) < Gd(III) < Dy(III) < Er(III).

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Synthesis And Characterization Of New Tridentate Iminooxime Ligands And Their Co(Iii) Complexes, Hasene Mutlu, Gazi̇ İrez Jan 2008

Synthesis And Characterization Of New Tridentate Iminooxime Ligands And Their Co(Iii) Complexes, Hasene Mutlu, Gazi̇ İrez

Turkish Journal of Chemistry

In this study, (hydroxyimino)(2-phenyl(1,2,3,4-tetrahydroquinazolin- 2-yl))methane (H_2L^1) and (hydroxyimino)(2-(2-thienyl)(1,2,3,4- tetrahydroquinazolin-2-yl))methane (H_2L^2) were synthesized by the condensation of 2-(hydroxyimino)-1-phenylethan-1-one (INAP) and 2-(hydroxyimino)-1-(2-thienyl)ethan-1-one (INAT) with 2-aminobenzylamine (2-ABA). Complexes of these ligands with Co^{3+} were prepared with a metal:ligand ratio of 1:2. The ligands and their complexes were elucidated on the basis of elemental analyses, AAS, FT-IR, ^1H- and ^{13}C-NMR spectra, mass spectra, magnetic susceptibility measurements, and molar conductivity.

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Comparison Of Catalytic Activities Of Carbon Supported Pt And Pt-Ru Catalysts For Methanol Oxidation In Neutral And Basic Media By Cyclic Voltammetry, Abdul Sattar Ali Khan, Riaz Ahmed, Muhammad Latif Mirza Jan 2008

Comparison Of Catalytic Activities Of Carbon Supported Pt And Pt-Ru Catalysts For Methanol Oxidation In Neutral And Basic Media By Cyclic Voltammetry, Abdul Sattar Ali Khan, Riaz Ahmed, Muhammad Latif Mirza

Turkish Journal of Chemistry

The catalytic activities of an equal amount of 3 different carbon supported catalysts containing 10% Pt, 20% Pt + 10% Ru, and 30% Pt were evaluated in neutral and basic media for methanol oxidation by cyclic voltammetry. The prominent oxidation peak for methanol appeared in the forward anodic sweep at around 1.0 V in neutral medium, while in basic medium it appeared at significantly lower potential close to 0.2 V. The peak current for methanol oxidation was higher on a catalyst containing higher Pt loading. The comparison of polarization behavior of 20% Pt + 10% Ru and 30% Pt catalysts …

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Synthesis And Cloning Of A Small Bacillus Pheromone Gene (Comx_{Ro-B-2}) By Primer-Dimer Formation With Pcr, Devri̇m Demi̇r Dora, Tanil Kocagöz, Fi̇li̇z Öner Jan 2008

Synthesis And Cloning Of A Small Bacillus Pheromone Gene (Comx_{Ro-B-2}) By Primer-Dimer Formation With Pcr, Devri̇m Demi̇r Dora, Tanil Kocagöz, Fi̇li̇z Öner

Turkish Journal of Chemistry

ComX pheromone is the major extracellular signaling peptide stimulating transformation in response to high cell density in Bacillus species. In this study, Bacillus mojavensis ComX_{(RO-B-2)} pheromone gene was cloned to pGEMT-Easy vector based on TA cloning of PCR products. The gene encoding 11 amino acid peptides of Bacillus mojavensis RO-B-2 strain ComX pheromone (GLQIYTNWVPS) was obtained by PCR amplification of 2 primers complementary to each other at their 3' end. This eliminated the need for the original bacterial gene as DNA template for PCR. The amplified PCR products were ligated directly without any modification by T4 DNA ligase into pGEMT-Easy …

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Preparation, Characterization, And Potentiometric Titrations Of Some New Di-[3-(3-Alkyl/Aryl-4,5-Dihydro-1h-1,2,4-Triazol-5-One-4-Yl)-Azomethinphenyl] Isophthalate/Terephthalate Derivatives, Haydar Yüksek, Özlem Gürsoy Kol Jan 2008

Preparation, Characterization, And Potentiometric Titrations Of Some New Di-[3-(3-Alkyl/Aryl-4,5-Dihydro-1h-1,2,4-Triazol-5-One-4-Yl)-Azomethinphenyl] Isophthalate/Terephthalate Derivatives, Haydar Yüksek, Özlem Gürsoy Kol

Turkish Journal of Chemistry

3-Alkyl(Aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with di-(3-formylphenyl) isophthalate (3) and di-(3-formylphenyl) terephthalate (6) to afford the corresponding 6 novel di-[3-(3-alkyl/aryl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl)- azomethinphenyl] isophthalates (4) and 6 novel di-[3-(3-alkyl/aryl-4,5- dihydro-1H-1,2,4-triazol-5-one-4-yl)-azomethinphenyl] terephthalates (7), respectively. The acetylation reactions of compounds 4 and 7 were investigated, and 5 and 8 type compounds were obtained, respectively. The new compounds synthesized were characterized by using IR, ^1H-NMR, ^{13}C-NMR, and UV spectral data together with elemental analysis. In addition, to investigate the effects of solvents and molecular structure upon acidity, compounds 4 and 7 were titrated potentiometrically with tetrabutylammonium hydroxide in 5 non-aqueous solvents (isopropyl alcohol, tert-butyl alcohol, N,N-dimethylformamide, acetone, …

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Adhesion Enhancement Of Polymeric Films On Glass Surfaces By A Silane Derivative Of Azobisisobutyronitrile (Aibn)., Sudhir Mulik, Chariklia Sotiriou-Leventis, Nicholas Leventis Jan 2008

Adhesion Enhancement Of Polymeric Films On Glass Surfaces By A Silane Derivative Of Azobisisobutyronitrile (Aibn)., Sudhir Mulik, Chariklia Sotiriou-Leventis, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Adhesion of polymeric films on surfaces can be due to a combination of van der Waals, electrostatic or covalent interactions between the two materials. The interfacial adhesion between a polymer film and glass or metal can be improved by using a broad class of silane coupling agents. Typically, silane coupling compounds used for adhesion improvement have structure similar to (R´O)3-Si-R, where R´O- is an alkoxy group and -R is an organofunctional group. Under appropriate reaction conditions alkoxy groups condense with hydroxyl groups available on the surface, resulting in surfaces decorated with organofunctional -R groups, which promote formation of covalent bonding …

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Glass Transition Behavior Of Poly(Methyl Acrylate) End-Grafted By Atrp To Amorphous Silica, Manikantan B. Nair, Frank D. Blum Jan 2008

Glass Transition Behavior Of Poly(Methyl Acrylate) End-Grafted By Atrp To Amorphous Silica, Manikantan B. Nair, Frank D. Blum

Chemistry Faculty Research & Creative Works

Ultra-thin polymer films attached to solid substrates (supported films) have attracted significant interest in recent years. Supported films are used in the design of advanced materials like photoresists, lubricants and other electronic devices. Glass transition temperatures (Tgs) of supported polymer films have also been of significant interest. The Tg has been shown to depend on the thickness of the polymer film on the surface and the inherent nature of the surface. The effect of end-grafting of a polymer chain to a surface, on the Tg of the polymer has been studied previously.1 Reports on the study of glass transition behaviors …

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Modeling The Fate Of Pharmaceuticals And Personal Care Products In Sewage Treatment Plants, Craig D. Adams Jan 2008

Modeling The Fate Of Pharmaceuticals And Personal Care Products In Sewage Treatment Plants, Craig D. Adams

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Chemical fate models can be used to estimate the transformation reactions and the partitioning behavior of pharmaceuticals and personal care products (PPCPs) in sewage treatment plants (STPs). Modeling the fate of PPCPs in a STP requires parameters such as rate constants or partition coefficients that are often unique to a specific STP, and that may exhibit significant temporal variability. Chemical fate models provide both a valuable test of our understanding of the fundamental underlying mechanisms regarding the fate of PPCPs in STPs, as well as a means of providing both qualitative and quantitative estimates for PPCP removal. This paper is …

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Salt Marshes As A Source Of Chromophoric Dissolved Organic Matter (Cdom) To Southern California Coastal Waters, Catherine D. Clark, Liannea P. Litz, Stanley B. Grant Jan 2008

Salt Marshes As A Source Of Chromophoric Dissolved Organic Matter (Cdom) To Southern California Coastal Waters, Catherine D. Clark, Liannea P. Litz, Stanley B. Grant

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

To determine chromophoric dissolved organic matter (CDOM) sources in Southern California coastal waters, optical properties of a river outlet and adjacent tidally flushed salt marshes were monitored (dry season; June July 2001). Average absorption coefficients doubled at ebb vs. flood tides (4.8 +/- 1.5 vs. 2.1 +/- 0.9 m(-1); 300 nm), suggesting significant salt marsh CDOM inputs into coastal waters. Average spectral slopes were not statistically different for any sites or tides (0.010 +/- 0.002 nm(-1)), consistent with salt marsh CDOM dominating coastal waters. Three-dimensional fluorescence excitation-emission matrices (EEMs) at ebb tide showed contributions from terrestrial, protein, and marine humic-like …

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7Β-Hydroxy­Artemisinin, Paulo B. Carvalho, Bo Liu, Yunshan Wu, John S. Williamson, Mitchell A. Avery Jan 2008

7Β-Hydroxy­Artemisinin, Paulo B. Carvalho, Bo Liu, Yunshan Wu, John S. Williamson, Mitchell A. Avery

Office for Research Publications and Presentations

Crystals of the title compound [systematic name: (3R,6R,7S,8aR,9R,12aR)-7-hydr­oxy-3,6,9-trimethyl­octa­hydro-3,12-ep­oxy[1,2]dioxepino[4,3-i]isochromen-10(3H)-one], C15H22O6, were obtained from microbial transformation of artemisinin by a culture of Cunninghamella elegans. The stereochemistry of the compound is consistent with the spectroscopic findings in previously published works. A weak O—H⋯O hydrogen bond occurs in the crystal structure, together with intermolecular C—H⋯O hydrogen bonds.

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Photochemical Studies Of Nutraceuticals In The Presence Of Cyclodextrins, Zlata Tofzikovskaya, Christine O'Connor, Mary Mcnamara Jan 2008

Photochemical Studies Of Nutraceuticals In The Presence Of Cyclodextrins, Zlata Tofzikovskaya, Christine O'Connor, Mary Mcnamara

Conference Papers

The photostability studies of Folic acid and Menadione Sodium Bisulfite, also known as vitamin K3, were carried out in their aqueous solutions at room temperature. Solutions of Folic acid ( 4.8 x 10-5 M) and Menadione Sodium Bisulfite (4.0 x 10-4 M) were exposed to ultraviolet radiation at a wavelength of 365 nm. During exposure absorbance of both solutions was measured using a Perkin Elmer Lamda 900 UV/VIS/NIR Spectrometer. During the stability tests it was noted that addition of β Cyclodextrin (1:1 ratio) to aqueous solutions containing the vitamin slowed down the photodegradation process. The unique shape of Cyclodextrins allows …

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Optimising Design Parameters Of Enzyme-Channelling Biosensors, Dana Mackey, Tony Killard Jan 2008

Optimising Design Parameters Of Enzyme-Channelling Biosensors, Dana Mackey, Tony Killard

Conference Papers

Two mathematical models for an electrochemical biosensor are proposed and compared with a view to determining the ratio of two immobilized enzymes which maximizes the amperometric signal amplitude.

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Evaluation Of A Naive Model For Square Wave Voltammetry At A Microelectrode, Patrick Enright, John Cassidy, Tony Betts Jan 2008

Evaluation Of A Naive Model For Square Wave Voltammetry At A Microelectrode, Patrick Enright, John Cassidy, Tony Betts

Articles

A square wave voltammetric waveform ( SWV) was applied to an inlaid microdisk electrode in a solution of K4[Fe(CN)6]. A simple model relying on the assumption of steady state current throughout the scan was used to model the current potential behaviour. However, experimental peak current magnitudes were between 30% and 50% greater than those predicted by the model. The model predicts an increase of peak current and peak width at half height with pulse height Esw and no effect of the parameters frequency, f and step height, ΔEs. Experimental peak current magnitudes and peak current magnitudes predicted by the model …

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Simultaneous Measurements Of Electronic Conduction And Raman Response In Molecular Junctions, Daniel R. Ward, Naomi J. Halas, James M. Tour, Jacob W. Ciszek, Yanpeng Wu, Peter Nordlander, Douglas Natelson Jan 2008

Simultaneous Measurements Of Electronic Conduction And Raman Response In Molecular Junctions, Daniel R. Ward, Naomi J. Halas, James M. Tour, Jacob W. Ciszek, Yanpeng Wu, Peter Nordlander, Douglas Natelson

Chemistry: Faculty Publications and Other Works

Electronic conduction through single molecules is affected by the molecular electronic structure as well as by other information that is extremely difficult to assess, such as bonding geometry and chemical environment. The lack of an independent diagnostic technique has long hampered single-molecule conductance studies. We report simultaneous measurement of the conductance and the Raman spectra of nanoscale junctions used for single-molecule electronic experiments. Blinking and spectral diffusion in the Raman response of both para-mercaptoaniline and a fluorinated oligophenylyne ethynylene correlate in time with changes in the electronic conductance. Finite difference time domain calculations confirm that these correlations do not result …

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Imaging Of Metal Ion Dissolution And Electrodeposition By Anodic Stripping Voltammetry – Scanning Electrochemical Microscopy, Mario A. Alpuche-Aviles, John E. Baur, David O. Wipf Jan 2008

Imaging Of Metal Ion Dissolution And Electrodeposition By Anodic Stripping Voltammetry – Scanning Electrochemical Microscopy, Mario A. Alpuche-Aviles, John E. Baur, David O. Wipf

CAS Publications

We have developed a new imaging method for SECM employing fast scan anodic stripping voltammetry (ASV) to provide sensitive and selective imaging of multiple chemical species at interfaces immersed in solution. A rapid CV scan (100 V/s) is used along with a short preconcentration time (300-750 ms) to allow images to be acquired in a normal SECM time frame. A Hg-Pt film electrode is developed having an equivalent Hg thickness of 40 nm that has good sensitivity at short preconcentration times and also retains thin-film behavior with high-speed voltammetric stripping. Fast scan anodic stripping currents are shown to be linear …

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X-Ray Lithography Of Metal And Semiconductor Nanoparticles, Nicholas Leventis, Suchi Guha, Massimo F. Bertino, Raghuveer Reddy Gadipalli, Brian R. Heckman, John Katsoudas, Ralu Divan, Lane A. Martin, Derrick C. Mancini Jan 2008

X-Ray Lithography Of Metal And Semiconductor Nanoparticles, Nicholas Leventis, Suchi Guha, Massimo F. Bertino, Raghuveer Reddy Gadipalli, Brian R. Heckman, John Katsoudas, Ralu Divan, Lane A. Martin, Derrick C. Mancini

Physics Faculty Research & Creative Works

In the last few years, a considerable amount of research has focused on the three-dimensional fabrication of contacts and electronic devices. Most techniques, however, are essentially based on photoreduction, and are limited to noble- and semi-noble metals. We present here a general method that allows patterning of porous matrices in 3D with metal, but also with semiconductor nanoparticles which is of potential relevance for microfabrication applications. In our method, the pore-filling solvent of a sol-gel material is exchanged with a solution of precursors. The precursors are photodissociated and nanoparticles are formed when the monoliths are irradiated. In a series of …

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Simulation Of Arsenic Partitioning In Tributaries To Drinking Water Reservoirs, Eid A. Alkhatib Jan 2008

Simulation Of Arsenic Partitioning In Tributaries To Drinking Water Reservoirs, Eid A. Alkhatib

Chemistry & Physics Faculty Publications

Arsenic released by bottom sediments was determined by experiments in which the sediments were artificially re-suspended using a particle entrapment simulator (PES) to simulate river conditions. Sediment cores were collected from various tributaries to drinking water reservoirs in Connecticut spiked with arsenic, and run in the PES at simulated bed-flow shear stresses from 0.0 to 0.6 N/m2. Under equilibrium conditions, the dissolved fraction of arsenic was found to range from 8.3 to 22.1 ug/1, which in most cases exceeded EPA Maximum Contaminant Level (MCL) of 10 ug/1. Experimental results from these simulations have shown that bed-flow shear stress causes an …

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