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2010

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Articles 781 - 810 of 950

Full-Text Articles in Chemistry

Production Of Multiwall Carbon Nanotube For Alcohol Sensor Application., Ebtehal Saleh Alshaqaq Jan 2010

Production Of Multiwall Carbon Nanotube For Alcohol Sensor Application., Ebtehal Saleh Alshaqaq

Student Works (2010-2019)

Multiwall carbon nanotube/polyethylene oxide (PEO), multiwall carbon nanoube/polyvinyl alcohol(PVA) and multiwall carbon nanotube/ polyvinyl alcohol(PVA)/zinc oxide(ZnO) have been tested as chemical sensors and detailed study on the effect of different gas concentration and material properties on gas sensitivity is presented. Initial composites were prepared by a simple solution casting and characterized by x-ray diffraction for ZnO, Fourier transform infra-red spectroscopy (FTIR) and scanning electron microscopy (SEM) to demonstrate crystallite size of ZnO, the morphology and surface area respectively. On the other hand, MWCNT/PEO , MWCNT/PVA , MWCNT/PVA/ZnO were prepared with different loading MWCNT and ZnO. The chemical sensing properties of …

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Electrodeposition Of Tin Using Tin(Ii) Methanesulfonate From Mixture Of Ionic Liquid And Methane Sulfonic Acid., Yang Kok Kee Jan 2010

Electrodeposition Of Tin Using Tin(Ii) Methanesulfonate From Mixture Of Ionic Liquid And Methane Sulfonic Acid., Yang Kok Kee

Student Works (2010-2019)

The electrodeposition of tin from Tin(II) Methane Sulfonate (MSA) with varying concentration in air and water stable 1-butyl-1-methyl-pyrrolidinium trifluoromethanesulfonate, (BMPOTF) ionic liquid at room temperature was studied. Cyclic Voltammetry served to characterize the electrochemical behavior of tin reduction and oxidation. The diffusion coefficient of stannous ions in the mixture of BMPOTF ionic liquid and MSA based electrolyte obtained via Randles-Sevcik and Cottrell equation was 2 × 10-7 cm2/s. Electroplating on copper panel was conducted under different current densities to determine BMPOTF based tin plating solution current efficiency. Mixture of BMPOTF and MSA based tin plating solution gave current efficiency as …

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Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, Wayne C. Stolte, Gunnar Ohrwall Jan 2010

Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, Wayne C. Stolte, Gunnar Ohrwall

Chemistry and Biochemistry Faculty Research

We have investigated the photofragmentation properties of the three-membered ring heterocyclic molecule ethylene sulfide or thiirane, C2H4S, by time-of-flight mass spectroscopy. Positive ions have been collected as a function of photon energy around the S K ionization threshold. Branching ratios were derived for all detected ions, which are informative of the decay dynamics and photofragmentation patterns of the core-excited species. We present a new assignment of the spectral features around the S K-edge.

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Realization Of Random-Field Ising Ferromagnetism In A Molecular Magnet, Bo Wen, P Subedi, Lin Bo, Y Yeshurun, M P. Sarachik, A D. Kent, A J. Millis, Christos Lampropoulos, G Christou Jan 2010

Realization Of Random-Field Ising Ferromagnetism In A Molecular Magnet, Bo Wen, P Subedi, Lin Bo, Y Yeshurun, M P. Sarachik, A D. Kent, A J. Millis, Christos Lampropoulos, G Christou

Chemistry Faculty Research and Scholarship

The longitudinal magnetic susceptibility of single crystals of the molecular magnet Mn12-acetate obeys a Curie-Weiss law, indicating a transition to a ferromagnetic phase at ∼0.9 K. With increasing magnetic field applied transverse to the easy axis, a marked change is observed in the temperature dependence of the susceptibility, and the suppression of ferromagnetism is considerably more rapid than predicted by mean-field theory for an ordered single crystal. Our results can instead be fit by a Hamiltonian for a random-field Ising ferromagnet in a transverse magnetic field, where the randomness derives from the intrinsic distribution of locally tilted magnetic …

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Electro-Oxidation Of Some Non-Steroidal Anti-Inflammatory Drugs On An Alumina Nanoparticle-Modified Glassy Carbon Electrode, Mahla Tabeshnia, Hossein Heli, Ali Jabbari, Ali A. Moosavi-Movahedi Jan 2010

Electro-Oxidation Of Some Non-Steroidal Anti-Inflammatory Drugs On An Alumina Nanoparticle-Modified Glassy Carbon Electrode, Mahla Tabeshnia, Hossein Heli, Ali Jabbari, Ali A. Moosavi-Movahedi

Turkish Journal of Chemistry

The electro-oxidation of mefenamic acid, diclofenac, and indomethacin on glassy carbon and alumina nanoparticle-modified glassy carbon electrodes in a phosphate buffer solution at physiological pH was studied. The techniques of cyclic voltammetry, chronoamperometry, impedance spectroscopy, and steady state polarization measurements were applied. The drugs were irreversibly oxidized on bath electrodes via an anodic peak and the process was controlled by diffusion in the bulk of solution. Alumina nanoparticles increased the oxidation current, and lowered the peak and onset potentials. As such, alumina nanoparticles had an electrocatalytic effect, both kinetically and thermodynamically. The kinetic parameters of heterogeneous electron transfer and diffusion …

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Inclusion And Release Of Theophylline From Chitosan Based Microparticles, Niculina Popa, Ovidiu Novac, Lenuta Profire, Doina Hritcu, Marcel Ionel Popa Jan 2010

Inclusion And Release Of Theophylline From Chitosan Based Microparticles, Niculina Popa, Ovidiu Novac, Lenuta Profire, Doina Hritcu, Marcel Ionel Popa

Turkish Journal of Chemistry

Chitosan (CS) based microparticles for controlled release of theophylline (THP) were obtained by ionic gelation. The microparticles were characterized by laser diffraction analysis (particle size), scanning electron microscopy (SEM), FTIR spectroscopy, and thermogravimetric analysis. The average diameter of the CS-THP microparticles was 182 \mu m. The FTIR spectra confirmed that new hydrogen bonds had formed between the carbonylic group belonging to THP and the amino group of CS, while the thermogravimetric analysis showed a modified stability in the obtained particles and confirmed the presence of an interaction between the drug and CS. The THP release process was monitored for up …

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Synthesis And Characterization Of Non-Symmetric Tetradentate Complexes Of Zn(Ii), Co(Ii), And Cu(Ii), Maryam Lashanizadegan, Shima Seraj Jan 2010

Synthesis And Characterization Of Non-Symmetric Tetradentate Complexes Of Zn(Ii), Co(Ii), And Cu(Ii), Maryam Lashanizadegan, Shima Seraj

Turkish Journal of Chemistry

The non-symmetrical tetradentate Schiff-base H_2L was obtained using the half-unit N-(1-hydroxy-2-acetophenone)-1-amino- 2-phenyleneimine (HL) with 2-hydroxyl-1-naphthaldehyde. ZnL, CoL, and CuL complexes were prepared and characterized by ^1H-NMR, IR, electronic, and atomic absorption spectra. The single crystal X-ray structure of CuL was determined. Crystal data for CuL are triclinic space group P-1, a = 8.3933 (17) Å, b = 11.197 (2) Å, c = 13.381 (3) Å, \alpha = 95.29 (3)°, \beta = 94.37 (3)°, \gamma = 95.82 (3)°, and z = 2.

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An Investigation Of Energy Transfer Between Coumarin 35 And Xanthene Derivatives In Liquid Medium, Mahmut Toprak, Mustafa Arik Jan 2010

An Investigation Of Energy Transfer Between Coumarin 35 And Xanthene Derivatives In Liquid Medium, Mahmut Toprak, Mustafa Arik

Turkish Journal of Chemistry

The energy transfer between coumarin 35 (C35) and pyronin compounds, which are xanthene derivatives, i.e. pyronin B (PyB) and pyronin Y (PyY), in methanol was investigated at room temperature by using steady-state absorption, emission, and time-resolved fluorescence spectroscopy. Fluorescence energy transfer rate constants (k_T) and critical radius (R_0) were determined for C35-PyB and C35-PyY molecular pairs in methanol. The obtained values of k_T and R_0 indicated that the dipole-dipole interaction between C35-PyB and C35-PyY molecular pairs accounted for the energy transfer mechanism. The energy transfer efficiency and the distance between the donor and acceptor (r) were also calculated for donor-acceptor …

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Direct Reductive Amination Of Carbonyl Compounds Using Sodium Borohydride-Silica Chloride, Heshmatollah Alinezhad, Mahmood Tajbakhsh, Neda Hamidi Jan 2010

Direct Reductive Amination Of Carbonyl Compounds Using Sodium Borohydride-Silica Chloride, Heshmatollah Alinezhad, Mahmood Tajbakhsh, Neda Hamidi

Turkish Journal of Chemistry

A simple and convenient procedure for reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride as an active, inexpensive, recoverable, and recyclable catalyst is described. The reactions were carried out with equimolar amounts of amine and carbonyl compound using silica chloride-sodium borohydride in THF at room temperature.

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Synthesis And Spectroscopic Studies Of Some New Organometallic Chelates Derived From Bidentate Ligands, Kiran Singh, Parvesh Puri Jan 2010

Synthesis And Spectroscopic Studies Of Some New Organometallic Chelates Derived From Bidentate Ligands, Kiran Singh, Parvesh Puri

Turkish Journal of Chemistry

A series of organosilicon(IV) and organotin(IV) complexes having the formulae R_2MCl(L^1), R_2MCl(L^2), R_2MCl(L^3), R_2MCl(L^4), R_2M(L^1)_2, R_2M(L^2)_2, R_2M(L^3)_2, and R_2M(L^4)_2, where M = Si and Sn, and R = CH_3, were synthesized with Schiff bases 5-mercapto-4-(pyridine-2-carboxalideneamino)-s-triazole (HL^1), 4-(furfuralideneamino)-5mercapto-s-triazole (HL^2), 4-(2-chlorobenzylideneamino)-5-mercapto-s-triazole (HL^3), and 4-(4-flourobenzylideneamino)-5-mercapto-s-triazole (HL^4). These complexes were characterized by elemental analysis, molar conductance, and spectroscopic studies, including UV, IR, ^1H, ^{13}C, ^{29}Si, and ^{119}Sn NMR spectroscopy. On the basis of these studies, the resulting complexes are proposed to have trigonal bipyramidal and octahedral geometries.

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Silica Supported Polyphosphoric Acid (Ppa-Sio_2): An Efficient And Reusable Heterogeneous Catalyst For The One-Pot Synthesis Of \Alpha -Amino Phosphonates, Malek Taher Maghsoodlou, Sayyed Mostafa Habibi-Khorassani, Reza Heydari, Nourollah Hazeri, Seyed Sajad Sajadikhah, Mohsen Rostamizadeh, Leila Keishams Jan 2010

Silica Supported Polyphosphoric Acid (Ppa-Sio_2): An Efficient And Reusable Heterogeneous Catalyst For The One-Pot Synthesis Of \Alpha -Amino Phosphonates, Malek Taher Maghsoodlou, Sayyed Mostafa Habibi-Khorassani, Reza Heydari, Nourollah Hazeri, Seyed Sajad Sajadikhah, Mohsen Rostamizadeh, Leila Keishams

Turkish Journal of Chemistry

An efficient green protocol is described for the preparation of \alpha -amino phosphonates, employing a one-pot three-component condensation reaction between aldehydes, amines, and trialkyl phosphites in the presence of PPA-SiO_2 under solvent-free conditions at 80 °C. The present procedure offer advantages such as high to excellent yields, short reaction time, inexpensiveness, recovery, and reusability of catalyst.

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Synthesis And Characterization Of Gold Nanoparticles Supported On Zinc Oxide Via The Deposition-Precipitation Method, Hanani Yazid, Rohana Adnan, Shafida Abdul Hamid, Muhammad Akhyar Farrukh Jan 2010

Synthesis And Characterization Of Gold Nanoparticles Supported On Zinc Oxide Via The Deposition-Precipitation Method, Hanani Yazid, Rohana Adnan, Shafida Abdul Hamid, Muhammad Akhyar Farrukh

Turkish Journal of Chemistry

Gold nanoparticles supported on zinc oxide nanoparticles were synthesized at several pH levels via the deposition-precipitation (DP) method. The effects of pH on gold loading, particle size, and particle size distribution on the support were studied at the iso-electric point (IEP) as well as below and above the IEP of ZnO. The addition of the support significantly changed the pH of the solution. The effects of adjusting the pH before and after the addition of the support into the gold chloride solution were also investigated. Gold particles with diameters of less than 5 nm were obtained. The results revealed that …

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Convenient Synthesis And Anion Recognition Property Of Acylhydrazone-Based Molecular Tweezer Receptors, Hai-Xian Ren, Ming-Gen Zhao, Ying-Jin Wang Jan 2010

Convenient Synthesis And Anion Recognition Property Of Acylhydrazone-Based Molecular Tweezer Receptors, Hai-Xian Ren, Ming-Gen Zhao, Ying-Jin Wang

Turkish Journal of Chemistry

Three acylhydrazone-based compounds were designed as novel neutral sensors for anions, and synthesized by simple steps in good yields. Their anion recognition properties were studied by UV-vis and ^1H-NMR spectroscopy. The results showed that the receptors 1, 2, and 3 all had a better selectivity for F^- and CH_3COO^-, but no evident binding with Cl^-, Br^-, I^-, NO_3^-, H_2PO_{4}^-, or HSO_{4}^-. The results indicated that anion recognition was achieved via convergent hydrogen bond interactions from acylhydrazone functionality on the side arms. The UV-vis data indicated that a 1:1 stoichiometry complex was formed between compounds 1, 2, or 3 and anions. …

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Synthesis And Super-Swelling Behavior Of A Novel Low Salt-Sensitive Protein-Based Superabsorbent Hydrogel: Collagen-G-Poly(Amps), Mohammad Sadeghi, Hossein Hosseinzadeh Jan 2010

Synthesis And Super-Swelling Behavior Of A Novel Low Salt-Sensitive Protein-Based Superabsorbent Hydrogel: Collagen-G-Poly(Amps), Mohammad Sadeghi, Hossein Hosseinzadeh

Turkish Journal of Chemistry

Superabsorbent polymers are obtained by the graft copolymerization of 2-acrylamido-2-methylpropanesul- fonic acid (AMPS) monomer onto collagen, using ammonium persulfate as a free radical initiator in the presence of methylene bisacrylamide as a crosslinker. Infrared spectroscopy and TGA thermal analysis were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). The effect of reaction variables on swelling capacity was investigated to achieve a hydrogel with improved water absorbency. Under the optimized conditions concluded, maximum capacity of swelling in distilled water was found to be 268 g/g. The swelling …

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Bromodimethylsulfonium Bromide/Tetrabutylammonium Nitrite: An Efficient Catalyst Mixture For The Nitration Of Phenols, Batool Akhlaghinia, Ali Reza Pourali Jan 2010

Bromodimethylsulfonium Bromide/Tetrabutylammonium Nitrite: An Efficient Catalyst Mixture For The Nitration Of Phenols, Batool Akhlaghinia, Ali Reza Pourali

Turkish Journal of Chemistry

Nitrophenols were obtained via direct nitration of phenols with tetrabutylammonium nitrite in the presence of bromodimethylsulfonium bromide at room temperature in high yields under aprotic conditions.

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Synthesis, Spectroscopic Characterization, Mass Spectrometry, And Crystal Structure Of N-{[(4-Bromophenyl)Amino]Carbonothioyl}Benzamide, Sohail Saeed, Naghmana Rashid, Moazzam Bhatti, Peter Jones Jan 2010

Synthesis, Spectroscopic Characterization, Mass Spectrometry, And Crystal Structure Of N-{[(4-Bromophenyl)Amino]Carbonothioyl}Benzamide, Sohail Saeed, Naghmana Rashid, Moazzam Bhatti, Peter Jones

Turkish Journal of Chemistry

N-{[(4-bromophenyl)amino]carbonothioyl}benzamide was synthesized and characterized by IR, ^1H- and ^{13}C-NMR, mass spectrometry, and elemental analysis. The crystal structure was determined from single crystal X-ray diffraction data. It crystallizes in monoclinic space group P2_1/n with unit cell dimensions a = 13.822(3) Å, b = 5.927(2) Å, c = 16.642(3) Å, and \beta = 103.963(3)°. There is a strong intramolecular hydrogen bond of the type N__H \Lambda O, with an H\Lambda O distance of 2.6129 (11) Å. The mass fragmentation pattern is also discussed.

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Effect Of Various Substituents On Intramolecular 1,1-Vinylboration, Synthesis Of 1-Silacyclobutene Derivatives, Ezzat Khan, Bernd Wrackmeyer Jan 2010

Effect Of Various Substituents On Intramolecular 1,1-Vinylboration, Synthesis Of 1-Silacyclobutene Derivatives, Ezzat Khan, Bernd Wrackmeyer

Turkish Journal of Chemistry

The reaction of 1-boryl-1-alkenyl chlorosilane derivatives with alkynyllithium reagents [Li-C\equiv C-R^3 (R^3~=~Ph, SiMe_3)] at low temperature (--78 °C) affords alkenyl(alkyn-1-yl)silanes. These compounds are precursors of 1-silacyclobutene derivatives, which are formed via intramolecular 1,1-vinylboration. This reaction works for various groups at silicon (R^1/R^2: R^1 = H, Me, Ph; R^2 = Me, Ph) and at the C=C and C\equiv C units (R/R^3: R = ^nBu, Ph; R^3 = ^nBu, Ph, SiMe_3). The conversion into 1-silacyclobutene derivatives is incomplete only in the case of R^3 = SiMe_3. The reactions were monitored by NMR spectroscopy in order to elucidate the reaction mechanism, and the …

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Solid Phase Extraction Of Copper, Nickel, And Cobalt In Water Samples After Extraction Using Surfactant Coated Alumina Modified With Indane-1,2,3-Trione 1,2-Dioxime And Determination By Flame Atomic Absorption Spectrometry, Mahdi Hosseini, Nasser Dalali, Ali Karimi, Kourosh Dastanra Jan 2010

Solid Phase Extraction Of Copper, Nickel, And Cobalt In Water Samples After Extraction Using Surfactant Coated Alumina Modified With Indane-1,2,3-Trione 1,2-Dioxime And Determination By Flame Atomic Absorption Spectrometry, Mahdi Hosseini, Nasser Dalali, Ali Karimi, Kourosh Dastanra

Turkish Journal of Chemistry

A simple method for simultaneous pre-concentration of Cu, Ni, and Co metal ions prior to their determination by flame atomic absorption spectrometry is reported. The method is based on the extraction of target ions via complexation with indane-1,2,3-trione 1,2-dioxime immobilized on sodium dodecyl sulfate (SDS) coated alumina. The metal content on the adsorbent was eluted with 4.5 mL of 2 mol L^{-1} nitric acid. The influences of the analytical parameters including pH, sample volume and flow rate, and eluent type and flow rate were investigated. The effect of matrix ions on the retentions of the analytes was also examined. The …

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Ethyl 5-Oxo-3-Arylamino-2,5-Dihydroisoxazole-4- Carboxylates As Sources Of Imidazopyrimidine And Aminoindole Derivatives, Ahmad Poursattar Marjani, Jabbar Khalafy Jan 2010

Ethyl 5-Oxo-3-Arylamino-2,5-Dihydroisoxazole-4- Carboxylates As Sources Of Imidazopyrimidine And Aminoindole Derivatives, Ahmad Poursattar Marjani, Jabbar Khalafy

Turkish Journal of Chemistry

The reaction of ethyl 5-oxo-3-arylamino-2,5-dihydroisoxazole-4- carboxylates with 2-chloropyrimidine and 2-chlorobenzoxazole gave the corresponding isoxazolones with pyrimidine and benzoxazole rings substituted on N-2. Their rearrangements with triethylamine in ethanol produced the corresponding imidazopyrimidine and aminoindole derivatives, respectively, through intramolecular cyclisation.

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An Efficient And Green Approach For The Synthesis Of Vinyl Aryl Ethers In The Presence Of Guanidine Hydrochloride, Seyed Mohammad Vahdat, Robabeh Baharfar Jan 2010

An Efficient And Green Approach For The Synthesis Of Vinyl Aryl Ethers In The Presence Of Guanidine Hydrochloride, Seyed Mohammad Vahdat, Robabeh Baharfar

Turkish Journal of Chemistry

A stereoselective procedure for vinyl aryl ether bond formation by direct coupling of dialkyl acetylenedicarboxylates and substituted phenols or naphthols under mild reaction conditions has been developed. Using guanidine hydrochloride as a new catalyst and water-acetone as green solvent, dialkyl acetylenedicarboxylates were reacted with substituted phenols or naphthols in room temperature to produce vinyl aryl ethers in good to excellent yields.

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Nile Blue-Hexacyanoferrate Carbon Paste Modified Electrode As An Amperometric Sensor For Determination Of Hydrazine, Reza Sabzi, Elnaz Minaie, Khalil Farhadi, Mirmaqsoud Golzan Jan 2010

Nile Blue-Hexacyanoferrate Carbon Paste Modified Electrode As An Amperometric Sensor For Determination Of Hydrazine, Reza Sabzi, Elnaz Minaie, Khalil Farhadi, Mirmaqsoud Golzan

Turkish Journal of Chemistry

The main problem associated with metal hexacyanoferrates (MHCFs) is their instability at high pH values. We synthesized a new Prussian Blue analogue, Nile-Blue hexacyanoferrate (NBHCF), that remains stable in 0.2 M KOH. A carbon paste (CPE) chemically modified electrode (ME) containing NBHCF was prepared as a stable electrochemical sensor for measuring hydrazine. A detailed characterization of the electrochemical and electrocatalytic behavior of NBHCF was performed using cyclic voltammetric, chronoamperometric, differential pulse voltammetric (DPV) and hydrodynamic amperometric methods. The NBHCF-modified electrode produced reproducible redox peaks and resulted in a linear increase in the oxidation signal of hydrazine with increasing concentration of …

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Cest And Paracest Mr Contrast Agents, Ileana Hancu, W. Thomas Dixon, Mark Woods, Elena Vinogradov, A. Dean Sherry, Robert E. Lenkinski Jan 2010

Cest And Paracest Mr Contrast Agents, Ileana Hancu, W. Thomas Dixon, Mark Woods, Elena Vinogradov, A. Dean Sherry, Robert E. Lenkinski

Chemistry Faculty Publications and Presentations

In this review we describe the status of development for a new class of magnetic resonance (MR) contrast agents, based on chemical exchange saturation transfer (CEST). The mathematics and physics relevant to the description of the CEST effect in MR are presented in an appendix published in the online version only. We discuss the issues arising when translating in vitro results obtained with CEST agents to using these MR agents in in vivo model studies and in humans. Examples are given on how these agents are imaged in vivo. We summarize the status of development of these CEST agents, and …

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Comparing The Chelating Abilities Of N-Acetylcysteine And N-Acetylcysteine Amide In Vitro For Lead Poisoning Treatment, Weiqing Chen Jan 2010

Comparing The Chelating Abilities Of N-Acetylcysteine And N-Acetylcysteine Amide In Vitro For Lead Poisoning Treatment, Weiqing Chen

Masters Theses

"Lead poisoning is a perennial and serious health problem around the world. The daily widespread use of lead has dramatically increased the degree and longevity of its exposure to humans, exacerbating the task of lead poisoning treatment. Lead exerts adverse effects on cardiovascular, central nervous, renal, gastrointestinal, and reproductive systems. The common treatment for lead poisoning is chelation therapy. Chelators were proposed to treat lead poisoning a very long time ago. However, chelators have severe side effects that could cause more problems, in addition to lead poisoning. Therefore, another group of drugs has been suggested --- antioxidants. This type of …

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Free-Standing And Reactive Thin Films Fabricated By Covalent Layer-By-Layer Assembly And Subsequent Lift-Off Of Azlactone-Containing Polymer Multilayers, Maren E. Buck, David M. Lynn Jan 2010

Free-Standing And Reactive Thin Films Fabricated By Covalent Layer-By-Layer Assembly And Subsequent Lift-Off Of Azlactone-Containing Polymer Multilayers, Maren E. Buck, David M. Lynn

Chemistry: Faculty Publications

We report an approach to the fabrication of free-standing and amine-reactive thin films that is based on the reactive layer-by-layer assembly and subsequent lift-off of azlactone-containing polymer multilayers. We demonstrate that covalently cross-linked multilayers fabricated using the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and a primary amine-containing polymer [poly(ethyleneimine) (PEI)] can be delaminated from planar glass and silicon surfaces by immersion in mildly acidic aqueous environments to yield flexible freestanding membranes. These free-standing membranes are robust and can withstand exposure to strong acid, strong base, or incubation in high ionic strength solutions that typically lead to the disruption and erosion of polymer …

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Langmuir Films Of Flexible Polymers Transferred To Aqueous/Liquid Crystal Interfaces Induce Uniform Azimuthal Alignment Of The Liquid Crystal, Michael I. Kinsinger, Maren E. Buck, Maria Victoria Meli, Nicholas L. Abbott, David M. Lynn Jan 2010

Langmuir Films Of Flexible Polymers Transferred To Aqueous/Liquid Crystal Interfaces Induce Uniform Azimuthal Alignment Of The Liquid Crystal, Michael I. Kinsinger, Maren E. Buck, Maria Victoria Meli, Nicholas L. Abbott, David M. Lynn

Chemistry: Faculty Publications

We reported recently that amphiphilic polymers can be assembled at interfaces created between aqueous phases and thermotropic liquid crystals (LCs) in ways that: (i) couple the organization of the polymer to the order of the LC and (ii) respond to changes in the properties of aqueous phases that can be characterized as changes in the optical appearance of the LC. This investigation sought to characterize the behavior of aqueous-LC interfaces decorated with uniaxially compressed thin films of polymers transferred by Langmuir-Schaefer (LS) transfer. Here, we report physicochemical characterization of interfaces created between aqueous phases and the thermotropic LC 4-cyano-4′-pentylbiphenyl (5CB) …

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Synthesis And Characterization Of Limpo[4] (M=Mn, Ni And Fe) Olivine Materials., Azlin Sanusi Jan 2010

Synthesis And Characterization Of Limpo[4] (M=Mn, Ni And Fe) Olivine Materials., Azlin Sanusi

Student Works (2010-2019)

Lithium transition metal phosphate, LiMPO4 compounds with olivine structure namely LiMnPO4, LiNiPO4 and LiFePO4 were successfully synthesized in the present work. LiMnPO4 and LiNiPO4 were synthesized by the sol-gel method with tartaric acid as the chelating agent. LiFePO4 was synthesized via the chemical precipitation and low temperature sterilizer heating method. TGA was carried out on LiMnPO4 and LiNiPO4 samples to determine the firing temperature of the gel precursor and the thermal stability of the prepared samples. LiMnPO4 was heated for 15 hours at various temperatures and LiNiPO4 was formed at 1000 oC with firing time of 24 hours. Firing of …

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Supramolecular Self-Assembly Strategies Involving Water Soluble Calixarenes., Irene Ling Jan 2010

Supramolecular Self-Assembly Strategies Involving Water Soluble Calixarenes., Irene Ling

Student Works (2010-2019)

Fundamental investigations of host-guest interactions on the supramolecular self-assembly involving water-soluble p-sulfonatocalix[4]arene, with a series of imidazolium-based cations and pyrrolidinium cation with variable alkyl chain lengths, which featured extensively in ionic liquids have been established. Combinatorial studies incorporating multiple components concerning p-sulfonatocalix[4]arene, imidazolium cations or pyrrolidinium cation, phosphonium cations and lanthanide ions have been developed, which yielded diverse solid state motifs with a common structural characteristic that the imidazolium or pyrrolidinium cation resides in the cavity of the calixarene. Shorter terminal alkyl chain of mono-imidazolium molecules, i.e. n-ethyl and n-butyl imidazoliums are confined in the „molecular capsule‟, being encapsulated by …

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Isolation And Identification Of A New Acetildenafil Analogue Used To Adulterate A Dietary Supplement: Dimethylacetildenafil, Ali̇ Hakan Göker, Maksut Coşkun, Mehmet Alp Jan 2010

Isolation And Identification Of A New Acetildenafil Analogue Used To Adulterate A Dietary Supplement: Dimethylacetildenafil, Ali̇ Hakan Göker, Maksut Coşkun, Mehmet Alp

Turkish Journal of Chemistry

A new sildenafil analogue was found to have been added illegally to a dietary supplement marketed for the enhancement of sexual function. The structure was determined as 5-(2-ethoxy-5- {[4-(3,5-dimethyl)piperazin-1-yl]-acetyl}phenyl)-1,6-dihydro-1-methyl-3- propyl-7H-pyrazolo [4,3-d]pyrimidin-7-one. Owing to the inclusion of a dimethyl group in acetildenafil, the detected compound was called dimethylacetildenafil. The sample was purified with column chromatography. The IR, LC/MS (ESI), and completely assigned NMR data of dimethylacetildenafil are reported for the first time. The structure was compared with that of acetildenafil and the results showed that the ethyl substitution at the 4-position of the piperazine ring had been replaced by a 3,5-dimethyl …

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Synthesis Of Some New Biheterocyclic Triazole Derivatives And Evaluation Of Their Antimicrobial Activity, Hakan Bektaş, Ahmet Demi̇rbaş, Nesli̇han Demi̇rbaş, Şengül Alpay Karaoğlu Jan 2010

Synthesis Of Some New Biheterocyclic Triazole Derivatives And Evaluation Of Their Antimicrobial Activity, Hakan Bektaş, Ahmet Demi̇rbaş, Nesli̇han Demi̇rbaş, Şengül Alpay Karaoğlu

Turkish Journal of Chemistry

2-{3-(4-Substitutedbenzyl)-4-[2-(1H-indol-3-yl)ethyl]-5-oxo-4,5- dihydro-1H-1,2,4-triazol-1-yl}-N'-(aryl-methylene)acetohydrazides (5a-g), 4-amino-2-{-(4-substitutedbenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol- 1-yl}-N'-(arylmethylene)acetohydrazides (6a,b), and 4-[2-(1H-indol- 3-yl)ethyl]-5-(4-substitutedbenzyl)-2-{5-(phenylamino)-1,3,4-thiadiazol- 2-yl]methyl}-2,4-dihydro-3H-1,2,4-triazol-3-ones (8a,b) were synthesized starting from 4-alkyl-5-(4-substitutedbenzyl)-2,4-dihydro- 3H-1,2,4-triazol-3-ones (2a-c) by several steps and their structures were well characterized by elemental analyses, IR, ^1H-NMR, ^{13}C-NMR, and mass spectral studies. They were also screened for their microbial activities. The obtained antimicrobial activity results revealed that 12 among the 24 compounds tested displayed variable growth inhibition effects on the tested gram-positive and gram-negative bacterial strains. None of the compounds showed antifungal activity against yeast-like fungi.

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Performance Evaluation Of Platinum-Based Catalysts For The Development Of Proton Exchange Membrane Fuel Cells, Abdul Sattar Ali Khan, Riaz Ahmed, Muhammad Latif Mirza Jan 2010

Performance Evaluation Of Platinum-Based Catalysts For The Development Of Proton Exchange Membrane Fuel Cells, Abdul Sattar Ali Khan, Riaz Ahmed, Muhammad Latif Mirza

Turkish Journal of Chemistry

Platinum-based catalysts are considered the most efficient catalysts for triggering electrochemical reactions in proton exchange membrane (PEM) fuel cells. In the present study, commercial catalysts containing 10% and 30% Pt supported on Vulcan XC-72 carbon were studied to assess their performance in PEM fuel cells. Both catalysts consisted of Pt particles of almost the same size. The utility of these catalysts in PEM fuel cells was studied by finding the real surface area and rate of electro-oxidation of methanol in 0.5 M H_2SO_4 by using cyclic voltammetry. The methanol oxidation reaction was used for characterization of catalysts of PEM fuel …

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