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2005

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Articles 31 - 60 of 562

Full-Text Articles in Chemistry

Electrochemical Disinfection Method To Treat Wastewater From Hospitals, Zhi-Fu Li, Ya-Dong Tan, Ning Xu, Shao-Hong Ren, Yu Zhao Nov 2005

Electrochemical Disinfection Method To Treat Wastewater From Hospitals, Zhi-Fu Li, Ya-Dong Tan, Ning Xu, Shao-Hong Ren, Yu Zhao

Journal of Electrochemistry

Electrochemical disinfection method was used to treat wastewater from hospitals. The mechanism of electrochemical disinfection was researched by using the different anode materials. The results showed that when the titanium coated with noble metal (Ru, Pt, Ir)oxide was used as an anode and stainless steel as a cathode, the current density was 6 mA/cm2, hydraulic retention time was 15 min,air flow rate was 40 L/h, the rate of anode effective area to the inner water volume was 1.0, the amount of total colibacillus was below 500 CFU/L after electrochemical disinfection,All these meet the first order of Effluent Discharge …

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Electrochemical Performance Of Li3.22Na0.569Mn5.78O12.0, Qing-Song Tong, Yong Yang, Jin-Ming Lian Nov 2005

Electrochemical Performance Of Li3.22Na0.569Mn5.78O12.0, Qing-Song Tong, Yong Yang, Jin-Ming Lian

Journal of Electrochemistry

By selecting LiOH·H2O and Mn(CH3COO)2·2H2O as starting-materials, the positive materials with the structure characterization of Li4Mn5O12 and composition of Li3.22Na0.569Mn5.78O12.0 were prepared by two-phase sintering method consisted of microwave and solid-state sintering processes. XRD patterns data showed that a pure Li4Mn5O12 phase was obtained by the fore-treatment of microwave sintering and the post-treatment of the solid-state sintering at 380℃. The charge-discharge tests showed that the newly prepared sample exhibited an initial capacity of 132 mAh·g …

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Electrochemical Controllable Preparation Of Hydroxyapatite Coating With Different Morphologies And Preliminary In Vitro Tests, Hai-Yan Shi, Ren Hu, Chang-Jian Lin Nov 2005

Electrochemical Controllable Preparation Of Hydroxyapatite Coating With Different Morphologies And Preliminary In Vitro Tests, Hai-Yan Shi, Ren Hu, Chang-Jian Lin

Journal of Electrochemistry

The Controllable electrochemical deposition has been developed to prepare the hydroxyapatite(HA) coatings on Ti substrate with different morphologies and structures. Three kinds of typical topography of HA coatings, i.e. standing-up, flower and ordered porous structures have been obtained. The XRD and FTIR results demonstrate high crystallinity of the coating and exclusion of other forms of calcium phosphates. In vitro tests reveal that the biological property is largely dependent on the structure and morphology of the HA coating. It has been found that all pure HA coating show good biocompatibilities, while only the HA coating with ordered porous structures exhibits best …

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Electrochemical Oxidation Of Organic Additives In Tin Plating Electrolytes, Yin-Mei Cheng, Lan-Kun Cai, Qiang Song Nov 2005

Electrochemical Oxidation Of Organic Additives In Tin Plating Electrolytes, Yin-Mei Cheng, Lan-Kun Cai, Qiang Song

Journal of Electrochemistry

Cyclic voltammetry(CV) was used to characterize the voltammetric behaviours of organic additives, e.g. PSA(phenolsulfonic acid) EN(ethoxylatedα-naphthol) and ENSA(ethoxylatedα-naphthol sulfonic acid), on the anode surface. In PSA solutions, an anodic peak was obtained and the peak potential was about 1.2V. In EN and ENSA solutions, two anodic peaks were obtained and the peak potentials were about(0.95V) and 1.3V. The products of galvanostatic electrolysis were separated by HPLC(high performance liquid chromatography) and analyzed by EI/MS(electron ionizing mass spectrometry). The mechnism of the electrochemical oxidation was also disussed.

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The Electrocatalystic Investigation Of 3,4-Dihydroxybenzoic Acid On The Modified Multiply Wall Carbon Nanotubes, Ming-Qi Li, Duo-Chang Cai, Xiao-Ying He Nov 2005

The Electrocatalystic Investigation Of 3,4-Dihydroxybenzoic Acid On The Modified Multiply Wall Carbon Nanotubes, Ming-Qi Li, Duo-Chang Cai, Xiao-Ying He

Journal of Electrochemistry

The electrochemical behavior of 3,4-Dihydroxybenzoic acid(DHBA) on modified multiply wall carbon nanotubes electrode was investigated by cyclic voltammetry(CV) and square wave voltammetry(SWV). Results show that in 0.1 mol/L HCl solutions the modified carbon nanotube electrode has an obvious electrocatalytic effect on the oxidation and deoxidization of DHBA. The oxidation current of DHBA is linear to it's concentration in the range of 4.0×10-6～1.0×10-4 mol/L and 2.0×10-4～8.0×10-4 1mol/L with correlation coefficient of 0.9995 and 0.9992. The detection limit is 1.0×10-6 mol/L.

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Solid Oxide Fuel Cells-Materials And Prospects, Molenda Janina, Marzec Jacek Nov 2005

Solid Oxide Fuel Cells-Materials And Prospects, Molenda Janina, Marzec Jacek

Journal of Electrochemistry

The paper summarizes and discusses the basic properties of solid oxide fuel cell (SOFC) components (electrode materials and electrolyte) from the point of view of their essential functional parameters suck as chemicalstability, transport, catalytic and thermomechanical properties under operational conditions in a SOFC. An interrela-tion between the defect structure of these materials related to oxygen nonstoichiometry and their electronic propertiesand catalytic activity was shown. Single-chamber fuel cell concept was also presented.

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Optimized Parameters For Electrochemical Fabrication Of P-Type Silicon-Based Two-Dimensional Photonic Crystals, Wan-Yun Zhang, Jia-Rong Ji, Xiao-Dong Yuan, Wei-Min Ye, Zhi-Hong Zhu Nov 2005

Optimized Parameters For Electrochemical Fabrication Of P-Type Silicon-Based Two-Dimensional Photonic Crystals, Wan-Yun Zhang, Jia-Rong Ji, Xiao-Dong Yuan, Wei-Min Ye, Zhi-Hong Zhu

Journal of Electrochemistry

A two-dimensional photonic band structure based on macroporous silicon with a gap centered at 20 μm has been achieved for the first time. A medium doped p-type (100) silicon substrate was patterned by the standard photolithograpgy and alkaline efthing. And this pre-patterned sample was then etched 90 μm deep by electrochemical pore formation in the mixture of hydrofluoric-acid and dimethylformamide (DMF) to produce a quare lattice of circular air rods with a lattice constant of 3.8 μm and the very high aspect ratio up to 30. The optimized electrochemical parameters such as eletrolytical components and the current density were 5 …

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A Continuous Operation For Electroreduction Of Oxalic Acid To Glyoxylic Acid, Xiao-Hui Hu, Xiang-Fei Yan, Yu-Zhong Su, Jun Li, Qing-Biao Li Nov 2005

A Continuous Operation For Electroreduction Of Oxalic Acid To Glyoxylic Acid, Xiao-Hui Hu, Xiang-Fei Yan, Yu-Zhong Su, Jun Li, Qing-Biao Li

Journal of Electrochemistry

A simulative-continuous-operation approach was proposed to study the continuous operation for electroreduction of oxalic acid to gloxylic acid using a packed bed reactor and a parallel reactor with cooled cathode in order to solve the low productivity problem in current state by using traditional reactor. The effects of the concentration of oxalic acid and temperature on this process were also studied. Results showed that,after 30min of the reaction(residence time), the mass fraction of the produced glyoxylic acid in the catholic solution could reach 3.76% and 3.66% with respect to a saturated oxalic acid method and a step-temperature decreasing method. From …

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The Mechanism Of Ethylenediamine On Electroless Ni-B Alloy Deposition, Sen-Lin Wang Nov 2005

The Mechanism Of Ethylenediamine On Electroless Ni-B Alloy Deposition, Sen-Lin Wang

Journal of Electrochemistry

The effects of ethylenediamine stabilizer on the deposition rate and on the stability of the plating bath for electroless deposition of Ni-B alloy were investigated. It was found that the addition of ethylenediamine greatly enhances the stability of the electroless plating bath. The electrochemical polarization including cathodic and anodic polarizations measurements were carried out to examine the effect of ethylenediamine on the deposition process. The results show that ethylenediamine affects both the cathodic and the anodic polarization processes. The oxidation current of the reducer and the reduction current of Ni-B alloy decrease greatly when ethylenediamine was added into the plating …

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Electrochemical Properties Of Aloe Emodin In Aqueous And Nonaqueous Solvents, Li-Ying Huang, Zhong-Cheng Wang, Li-Min Lai, Xin-Hua Lin, Wei Chen Nov 2005

Electrochemical Properties Of Aloe Emodin In Aqueous And Nonaqueous Solvents, Li-Ying Huang, Zhong-Cheng Wang, Li-Min Lai, Xin-Hua Lin, Wei Chen

Journal of Electrochemistry

Electrochemical properties of Aloe emodin in aqueous and nonaqueous solvents of DMSO were studied by cyclic voltammetry and linear sweep voltammetry at a platinum electode. A pairs of currents on the voltammogram may be attributed to a quasi-reversible-one-electron transfer in HAc-NaAc and DMSO, the peak potential in DMSO was found to move more negatively compared with that in HAc-NaAc. A new method for Aloe emodin determination is described. The peak current is proportional to the concentration of Aloe emodin over the ranges of 1.0×10-5~6.0×10-4 mol/L. The electrochemical properties of Aloe emodin were related to solvents.

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C-Terminal Tail Residue Arg1400 Enables Nadph To Regulate Electron Transfer In Neuronal Nitric-Oxide Synthase, Mauro Tiso, David Konas, Koustubh Panda, Elsa D. Garcin, Manisha Sharma, Elizabeth D. Getzoff, Dennis J. Stuehr Nov 2005

C-Terminal Tail Residue Arg1400 Enables Nadph To Regulate Electron Transfer In Neuronal Nitric-Oxide Synthase, Mauro Tiso, David Konas, Koustubh Panda, Elsa D. Garcin, Manisha Sharma, Elizabeth D. Getzoff, Dennis J. Stuehr

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

The neuronal nitric-oxide synthase (nNOS) flavoprotein domain (nNOSr) contains regulatory elements that repress its electron flux in the absence of bound calmodulin (CaM). The repression also requires bound NADP(H), but the mechanism is unclear. The crystal structure of a CaM-free nNOSr revealed an ionic interaction between Arg1400 in the C-terminal tail regulatory element and the 2′-phosphate group of bound NADP(H). We tested the role of this interaction by substituting Ser and Glu for Arg1400 in nNOSr and in the full-length nNOS enzyme. The CaM-free nNOSr mutants had cytochrome c reductase activities that were less repressed than in wild-type, and this …

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Process For The Preparation Of Citalopram Intermediate, Aslam A. Malik, Hasan Palandoken, Joy A. Stringer, Dershing Huang, Antonio Romero, Olivier Dapremont Nov 2005

Process For The Preparation Of Citalopram Intermediate, Aslam A. Malik, Hasan Palandoken, Joy A. Stringer, Dershing Huang, Antonio Romero, Olivier Dapremont

Chemistry and Biochemistry

The present invention provides, inter alia, a novel process for the preparation of Citalopram, a known antidepressant.

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Second Oh Overtone Excitation And Statistical Dissociation Dynamics Of Peroxynitrous Acid, I. M. Konen, E. X.J. Li, Thomas Alex Stephenson, M. I. Lester Nov 2005

Second Oh Overtone Excitation And Statistical Dissociation Dynamics Of Peroxynitrous Acid, I. M. Konen, E. X.J. Li, Thomas Alex Stephenson, M. I. Lester

Chemistry & Biochemistry Faculty Works

The second OH overtone transition of the trans-perp conformer of peroxynitrous acid (tp-HOONO) is identified using infrared action spectroscopy. HOONO is produced by the recombination of photolytically generated OH and NO(2) radicals, and then cooled in a pulsed supersonic expansion. The second overtone transition is assigned to tp-HOONO based on its vibrational frequency (10 195.3 cm(-1)) and rotational band contour, which are in accord with theoretical predictions and previous observations of the first overtone transition. The transition dipole moment associated with the overtone transition is rotated considerably from the OH bond axis, as evident from its hybrid band composition, indicating …

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The Role Of Phosducin-Like Protein And The Cytosolic Chaperonin Cct In G Beta Gamma Dimer Assembly, Ting Hu Nov 2005

The Role Of Phosducin-Like Protein And The Cytosolic Chaperonin Cct In G Beta Gamma Dimer Assembly, Ting Hu

Theses and Dissertations

Phosducin-like protein (PhLP), a G protein beta gamma subunit dimer binder and G protein signaling regulator, was suggested to regulate the activity of cytosolic chaperonin CCT by their high affinity interaction. In the present study, the three-dimensional structure of PhLP:CCT complex has been solved by cryoelectron microscopy. PhLP was found to bind only one of the chaperonin rings with both N- and C-terminal domains. It spans the central folding cavity of CCT and interacts with two opposite sides of the top apical region, inducing the constraining of the entry of the folding cavity. These findings support a putative role of …

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Structural And Chiroptical Properties Of The Two Coordination Isomers Of Ybdota-Type Complexes, Lorenzo Di Bari, Gennaro Pescitelli, A. Dean Sherry, Mark Woods Nov 2005

Structural And Chiroptical Properties Of The Two Coordination Isomers Of Ybdota-Type Complexes, Lorenzo Di Bari, Gennaro Pescitelli, A. Dean Sherry, Mark Woods

Chemistry Faculty Publications and Presentations

Studies of the structural, physical, and chemical properties of the lanthanide(III) complexes of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and related ligands are often complicated by the presence of two coordination isomers in solution. Since these coordination isomers are in exchange and cannot be separated, many techniques offer information only on the weighted average of the two isomers. Lanthanide ion complexes formed with the ligands S(RRRR)NO2BnDOTMA and S(SSSS)NO2BnDOTMA preferentially adopt only one of the two common coordination isomers in solution, so the ytterbium complexes of these ligands offer a unique opportunity to study …

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Inhibition Of Cellular Respiration By Doxorubicin, Zhimin Tao, Henry G. Withers, Harvey S. Penefsky, Jerry Goodisman, Abdul Kader Souid Nov 2005

Inhibition Of Cellular Respiration By Doxorubicin, Zhimin Tao, Henry G. Withers, Harvey S. Penefsky, Jerry Goodisman, Abdul Kader Souid

Chemistry - All Scholarship

Doxorubicin executes apoptosis, a process known to produce leakage of cytochrome c and opening of the mitochondrial permeability transition pores. To define the loss of mitochondrial function by apoptosis, we monitored cellular respiration during continuous exposure to doxorubicin. A phosphorescence analyzer capable of stable measurements over at least 5 h was used to measure [O(2)]. In solutions containing glucose and cells, [O(2)] declined linearly with time, showing that the kinetics of oxygen consumption was zero order. Complete inhibition of oxygen consumption by cyanide indicated that oxidations occurred in the respiratory chain. A decline in the rate of respiration was evident …

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Palladium-Imidazolium Carbene Catalyzed Heck Coupling Reactions And Synthesis Of A Novel Class Of Fluoroanthracenylmethyl Ptc Catalysts, Jiuqing Zhang Nov 2005

Palladium-Imidazolium Carbene Catalyzed Heck Coupling Reactions And Synthesis Of A Novel Class Of Fluoroanthracenylmethyl Ptc Catalysts, Jiuqing Zhang

Theses and Dissertations

Palladium catalyzed Heck coupling with aryl and alkenyl halides has become a powerful means of carbon-carbon bond formation. This standard synthetic method has been developed to a high level of utility using various catalysts, conditions and substrates. Yet significant drawbacks remain, including poor reactivity, the need for high temperatures and base, limited substrate generality, and selectivity. Mixed products often suffer from olefin migration following insertion. N-Heterocyclic carbenes (NHC) have proven to be electron-rich donors which provide higher stability and reactivity than phosphines. In a previous paper reported by our research group the imidazolium-palladium carbene has proven to be highly efficient …

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Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz Nov 2005

Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz

Faculty Publications

Nonadiabatic effects in quantum dynamics are described using a mixed polar/coordinate space representation of the wave function. The polar part evolves on dynamically determined potential surfaces that have diabatic and adiabatic potentials as limiting cases of weak localized and strong extended diabatic couplings. The coordinate space part, generalized to a matrix form, describes transitions between the surfaces. Choice of the effective potentials for the polar part and partitioning of the wave function enables one to represent the total wave function in terms of smooth components that can be accurately propagated semiclassically using the approximate quantum potential and small basis sets. …

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Performance Of Binary-Encounter-Bethe (Beb) Theory For Electron-Impact Ionization Cross Sections Of Molecules Containing Heavy Elements (Z > 10), Gregory E. Scott, Karl K. Irikura Nov 2005

Performance Of Binary-Encounter-Bethe (Beb) Theory For Electron-Impact Ionization Cross Sections Of Molecules Containing Heavy Elements (Z > 10), Gregory E. Scott, Karl K. Irikura

Chemistry and Biochemistry

The binary-encounter-Bethe (BEB) theory developed by Kim and coworkers has been successful for computing electron-impact ionization cross sections of many molecules. However, some recent publications have stated that BEB theory performs poorly for molecules that contain heavier elements such as chlorine and sulfur. We have found that the BEB calculations in those publications were performed incorrectly. When performed correctly, BEB predictions are as good for heavy-element molecules as for light-element molecules. We recommended recently that an alternative, less-confusing procedure be used for molecules that contain heavier elements. The alternative procedure, based upon effective core potentials (ECPs), does not require explicit …

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Total Syntheses Of (+)-Geldanamycin, (-)-Ragaglitazar, And (+)-Kurasoin A And Phase-Transfer-Catalyzed Asymmetric Alkylation, Erik J. Hicken Nov 2005

Total Syntheses Of (+)-Geldanamycin, (-)-Ragaglitazar, And (+)-Kurasoin A And Phase-Transfer-Catalyzed Asymmetric Alkylation, Erik J. Hicken

Theses and Dissertations

Geldanamycin possesses various biological activities as seen in the NCI 60 cell line panel (13 nM avg., 70 nM SKBr-3 cells). The predominant mode of action providing these unique results arises from the ability of geldanamycin (GA) to bind to the chaperone heat shock protein 90 (Hsp90). Despite its complicated functionality, the first total synthesis of GA was accomplished, which included two new reactions developed specifically to address the stereochemical features. The final step in the synthesis of GA was a demethylation-oxidation sequence to generate the desired para-quinone. This step could only be accomplished with HNO3/AcOH, producing GA in …

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Supramolecular Chemistry Of Nitrogen Dioxide, Yanlong Kang Nov 2005

Supramolecular Chemistry Of Nitrogen Dioxide, Yanlong Kang

Chemistry & Biochemistry Dissertations - Archive

Supramolecular chemistry has been defined as "chemistry beyond molecules", and involves investigating molecular systems held together reversibly by inter-molecular forces, not by covalent bonds. This dissertation discusses a supramolecular approach towards sensing, entrapment and utilization of NO2/N2O4 gases. Chapter 1 briefly discusses supramolecular chemistry and supramolecular chemistry of gases. In chapter 2, the interaction of NOx with metalloporphyrins is described. Specifically, ruthenium nitrosyl derivatives hold a special place in mimicking bio-relevant NO-metal interactions. A previously unnoticed reaction between NO2/N2O4 and a Ru(II) porphyrin is described. It causes disproportionation of N2O4 and leads to a stable nitrosyl nitrato complex. Our findings …

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Supramolecular Nanostructures Based On Calixarenes, Heng Xu Nov 2005

Supramolecular Nanostructures Based On Calixarenes, Heng Xu

Chemistry & Biochemistry Dissertations - Archive

This dissertation describes a systematic approach towards the design, synthesis, characterization, and application of calixarene-based supramolecular nanostructures. Chapter 1 briefly overviews the field of supramolecular chemistry and highlights its horizons. Chapter 2 introduces a modular strategy towards synthesis of nanoscale receptor macromolecules--calix-peptide conjugates. This strategy combines the unique host-guest capabilities of calixarene chemistry with synthetically flexible peptide synthesis. A series of calixarene amino acids was prepared and further utilized to synthesize calixarene dipeptides. Through this approach, calixarene amino acids are now available to be incorporated into peptide networks and nanostructured biologically relevant materials. Chapter 3 demonstrates supramolecular applications of calixarene-peptide …

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Neutron And Nuclear Inelastic Scattering Study Of The Einstein Oscillators In Ba-, Sr-, And Eu-Filled Germanium Clathrates, Raphaël P. Hermann, Werner Schweika, Olaf Leupold, Rudolf Rüffer, George S. Nolas, Fernande Grandjean, Gary J. Long Nov 2005

Neutron And Nuclear Inelastic Scattering Study Of The Einstein Oscillators In Ba-, Sr-, And Eu-Filled Germanium Clathrates, Raphaël P. Hermann, Werner Schweika, Olaf Leupold, Rudolf Rüffer, George S. Nolas, Fernande Grandjean, Gary J. Long

Chemistry Faculty Research & Creative Works

Inelastic neutron scattering measurements on Ba8Ga16Ge30 and Sr8Ga16Ge30 indicate the presence of soft local modes with Einstein oscillator energies of 4.9±0.1 and 4.4±0.1meV, modes which are associated with the lowest “rattling” mode of the Ba(B) and Sr(B) guests, respectively. Nuclear inelastic scattering measurements on Eu8Ga16Ge30 yield Einstein oscillator energies of between 3.0±0.3 and 7.5±1.2meV for the different modes of the Eu guests. Further, the resonant character of the measurements on Eu8Ga16Ge30 reveals, without question, that neither of the Eu guests …

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Effects Of Gramicidin-A On The Adsorption Of Phospholipids To The Air–Water Interface, Samares C. Biswas, Shankar B. Rananavare, Stephen B. Hall Nov 2005

Effects Of Gramicidin-A On The Adsorption Of Phospholipids To The Air–Water Interface, Samares C. Biswas, Shankar B. Rananavare, Stephen B. Hall

Chemistry Faculty Publications and Presentations

Prior studies suggest that the hydrophobic surfactant proteins, SP-B and SP-C, promote adsorption of the lipids in pulmonary surfactant to an air–water interface by stabilizing a negatively curved rate-limiting structure that is intermediate between bilayer vesicles and the surface film. This model predicts that other peptides capable of stabilizing negative curvature should also promote lipid adsorption. Previous reports have shown that under appropriate conditions, gramicidin-A (GrA) induces dioleoyl phosphatidylcholine (DOPC), but not dimyristoyl phosphatidylcholine (DMPC), to form the negatively curved hexagonal-II (HII) phase. The studies reported here determined if GrA would produce the same effects on adsorption of DMPC and …

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Large-Scale Molecular-Dynamics Simulation Of Nanoscale Hydrophobic Interaction And Nanobubble Formation, Takahiro Koishi, Kenji Yasuoka, Toshikazu Ebisuzaki, S. Yoo, Xiao Cheng Zeng Nov 2005

Large-Scale Molecular-Dynamics Simulation Of Nanoscale Hydrophobic Interaction And Nanobubble Formation, Takahiro Koishi, Kenji Yasuoka, Toshikazu Ebisuzaki, S. Yoo, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We performed large-scale molecular-dynamics simulation of nanoscale hydrophobic interaction manifested by the formation of nanobubble between nanometer-sized hydrophobic clusters at constrained equilibrium. Particular attention is placed on the tendency of formation and stability of nanobubbles in between model nanoassemblies which are composed of hydrophobic clusters (or patches) embedded in a hydrophilic substrate. On the basis of physical behavior of nanobubble formation, we observed a change from short-range molecular hydrophobic interaction to midrange nanoscopic interaction when the length scale of hydrophobe approaches to about 1 nm. We investigated the behavior of nanobubble formation with several different patterns of nonpolar-site distribution on …

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Possible Side Reactions Due To Water In Emulsion Polymerization By Late Transition Metal Complexes. 1. Water Complexation And Hydrolysis Of The Growing Chain, Iordan H. Hristov, Roger L. Dekock, Grant D. W. Anderson, Inigo Göttker-Schnetmann Oct 2005

Possible Side Reactions Due To Water In Emulsion Polymerization By Late Transition Metal Complexes. 1. Water Complexation And Hydrolysis Of The Growing Chain, Iordan H. Hristov, Roger L. Dekock, Grant D. W. Anderson, Inigo Göttker-Schnetmann

University Faculty Publications and Creative Works

The transition metal catalyzed ethylene polymerization in aqueous emulsion has been increasingly successful in the last couple of years. Water however adversely affects the polymerization process by (a) competing with ethylene for the binding site at the metal and (b) hydrolyzing the growing chain. Neutral salicylaldiminato and cationic diimine complexes of Ni and Pd with different substituent patterns are studied here by density functional theory to determine their propensity toward water complexation and hydrolysis of the growing chain. Experimental NMR studies have also been carried out on the protonolysis of the Ni(II)-based Grubbs catalyst. It is found that in general …

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Micron-Sized Polymeric Particles From Cashew Nut Shell Liquid: Influence Of Reaction Parameters On Particle Size, Ymm Makame, W Johnson, Ll Mkayula Oct 2005

Micron-Sized Polymeric Particles From Cashew Nut Shell Liquid: Influence Of Reaction Parameters On Particle Size, Ymm Makame, W Johnson, Ll Mkayula

Tanzania Journal of Science

Cashew nut shell liquid based polymer latexes of narrow size distribution and average particle sizes ranging from 0.1 to 0.4 µm were prepared by base catalysed emulsion polycondensation of cashew nut shell liquid of 820 centipoises viscosity with formaldehyde. The influence of emulsifier concentration, sodium hydroxide concentration and stirring rate on average particle size and size distribution was studied for the given geometry of the reactor and the stirrer. It was found that these variables have a significant effect on the particle size and particle size distribution and that average particles size can be predicted and controlled by the choice …

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Recent Trends In Accumulation Rate, Elemental And Isotopic Composition Of Organic Matter In The Magu Bay, Lake Victoria, Ann Muzuka, Jf Machiwa, C Lugomela Oct 2005

Recent Trends In Accumulation Rate, Elemental And Isotopic Composition Of Organic Matter In The Magu Bay, Lake Victoria, Ann Muzuka, Jf Machiwa, C Lugomela

Tanzania Journal of Science

Stable isotope composition of organic carbon (OC), 14C data, OC and nitrogen content of recently deposited sediments in Magu Bay of Speke Gulf, Lake Victoria are used to document accumulation rates, sources and distribution of organic matter in the bay. The stable isotope values of both organic carbon and nitrogen decrease towards offshore, and this trend is associated with increase in the contents of organic carbon and nitrogen. The isotope results show that the organic material deposited in the bay are generally derived from C4 type of plants and are not transported far from the river mouth. Also the results …

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Roadmap For High Efficiency Solid-State Neutron Detectors, R. J. Nikolic, Chin Li Cheung, C. E. Reinhardt, T. F. Wang Oct 2005

Roadmap For High Efficiency Solid-State Neutron Detectors, R. J. Nikolic, Chin Li Cheung, C. E. Reinhardt, T. F. Wang

Barry Chin Li Cheung Publications

Solid-state thermal neutron detectors are generally fabricated in a planar configuration by coating a layer of neutron-to-alpha converter material onto a semiconductor. The as-created alpha particles in the material are expected to impinge the semiconductor and create electron-hole pairs which provide the electrical signal. These devices are limited in efficiency to a range near (2-5%)/cm2 due to the conflicting thickness requirements of the converter layer. In this case, the layer is required to be thick enough to capture the incoming neutron flux while at the same time adequately thin to allow the alpha particles to reach the semiconductor. A …

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Synthesis And Structure-Activity Relationships Of Ss- And A-Piperidine Sulphone Hydroxamic Acid Matrix Metalloproteinase Inhibitors With Oral Antitumor Efficacy, Daniel Becker, Clara I. Villamil, Thomas E. Barta, Louis J. Bedell Oct 2005

Synthesis And Structure-Activity Relationships Of Ss- And A-Piperidine Sulphone Hydroxamic Acid Matrix Metalloproteinase Inhibitors With Oral Antitumor Efficacy, Daniel Becker, Clara I. Villamil, Thomas E. Barta, Louis J. Bedell

Chemistry: Faculty Publications and Other Works

α-Piperidine-β-sulfone hydroxamate derivatives were explored that are potent for matrix metalloproteinases (MMP)-2, -9, and -13 and are sparing of MMP-1. The investigation of the β-sulfones subsequently led to the discovery of hitherto unknown α-sulfone hydroxamates that are superior to the corresponding β-sulfones in potency for target MMPs, selectivity vs MMP-1, and exposure when dosed orally. α-Piperidine-α-sulfone hydroxamate 35f (SC-276) was advanced through antitumor and antiangiogenesis assays and was selected for development. Compound 35f demonstrates excellent antitumor activity vs MX-1 breast tumor in mice when dosed orally as monotherapy or in combination with paclitaxel.

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