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Articles 781 - 810 of 1553

Full-Text Articles in Chemistry

Structural, Magnetic, And Transport Properties Of Zr-Substituted La₀.₇ Sr₀.₃ Mn O₃, Minseob Kim, Jinbo Yang, Qingsheng Cai, William Joseph James, William B. Yelon, Paul Ernest Parris, Satish K. Malik May 2007

Structural, Magnetic, And Transport Properties Of Zr-Substituted La₀.₇ Sr₀.₃ Mn O₃, Minseob Kim, Jinbo Yang, Qingsheng Cai, William Joseph James, William B. Yelon, Paul Ernest Parris, Satish K. Malik

Chemistry Faculty Research & Creative Works

Zr-substituted perovskites La0.7Sr0.3 Mn1-x Zrx O3 with 0 ≤ x ≤ 0.20 were investigated by neutron diffraction (ND), magnetization, electric resistivity, and magnetoresistance measurements. ND refinements reveal that substituted Zr4+ goes only to the Mn site. Because of its large size, this leads to a Zr-solubility limit at x ≤ 0.10. The x ≤ 0.10 samples exhibit a rhombohedral structure (R3c) from 10 K to room temperature. For the x ≤ 0.10 samples, the cell parameters a and c, and volume increase continuously with increasing Zr content. In addition, the structural distortion of …

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Reliable Structures And Energetics For Two New Delocalized Π⋯Π Prototypes: Cyanogen Dimer And Diacetylene Dimer, Brian W. Hopkins, Adel M. Elsohly, Gregory S. Tschumper Apr 2007

Reliable Structures And Energetics For Two New Delocalized Π⋯Π Prototypes: Cyanogen Dimer And Diacetylene Dimer, Brian W. Hopkins, Adel M. Elsohly, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

Two new prototypes delocalized π⋯π complexes are introduced: the dimers of cyanogen, (N≡C-C≡N)2, and diacetylene, (HC≡C-C≡CH)2. These dimers have properties similar to larger delocalized π⋯π systems such as benzene dimer but are small enough that they can be probed in far greater detail with high accuracy electronic structure methods. Parallel-slipped and T-shaped structures of both cyanogen dimer and diacetylene dimer have been optimized with 15 different procedures. The effects of basis set size, theoretical method, counterpoise correction, and the rigid monomer approximation on the structure and energetics of each dimer have been examined. MP2 and CCSD(T) optimized geometries for all …

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Water Borne Film-Forming Compositions, Michael R. Van-De-Mark, Nantana Jiratumnukul Jan 2007

Water Borne Film-Forming Compositions, Michael R. Van-De-Mark, Nantana Jiratumnukul

Chemistry Faculty Research & Creative Works

The present invention provides a film-forming composition comprising a particulate polymer or emulsified liquid prepolymer, water and a coalescent aid comprising an ester having the formula RCOOX wherein R and X are independently hydrocarbyl or substituted hydrocarbyl, and at least one of R and X contain at least two unsaturated carbon— carbon bonds. The coalescent aid helps lower the minimum film formation temperature of low glass transition temperature coatings and high glass transition temperature coatings and allows optimum film formation at ambient temperatures. The coalescent aid of this coating composition is not volatile like conventional coalescent aids but rather remains …

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Unleaded Drinking Water: Equilibrium Potential Measurements For Monochloramine Disinfectant, Brandi Clark Jan 2007

Unleaded Drinking Water: Equilibrium Potential Measurements For Monochloramine Disinfectant, Brandi Clark

Opportunities for Undergraduate Research Experience Program (OURE)

The strength of monochloramine, NH2CI, as an oxidizing agent can be linked to its effect on Pb levels in drinking water. In this study, the equilibrium potential was measured as a function of pH from pH 8 to 12 and compared to a theoretical plot of formal potentials derived from the Nemst equation. The measured equilibrium potential was consistently about 300 mV more negative than the calculated potential - NH2CI is a weaker oxidizing agent than predicted. When the measured potentials are plotted on a Pourbaix diagram, it is found that NH2CI can oxidize …

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Photosensitization Of Photoconductive And Photorefractive Composites Through The Inclusion Of Semiconductor Nanocrystals, Tyler Martin Fears Jan 2007

Photosensitization Of Photoconductive And Photorefractive Composites Through The Inclusion Of Semiconductor Nanocrystals, Tyler Martin Fears

Opportunities for Undergraduate Research Experience Program (OURE)

A novel synthesis of NiS nanocrystals included in photorefractive polymeric composites is described. The nanocrystals were characterized using visible-absorption spectroscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. We further demonstrate the ability to enhance aspects of the composites' photorefractive performance by performing ligand exchange on the nanocrystals prior to their incorporation into the polymer composite. It was originally believed that this modification of the nanocrystals' surface characteristics would result in an enhanced charge-transfer process between the nanocrystal and the charge transporting matrix. However, when the photo conductivities were determined and used in calculating the quantum efficiencies associated with the …

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Polymer Gels: Mimickin G Biological Environments, Joshua Carey Jan 2007

Polymer Gels: Mimickin G Biological Environments, Joshua Carey

Opportunities for Undergraduate Research Experience Program (OURE)

A comparison of the hydrolysis of pyruvic acid in polymer gels and in aqueous environment will be studied using NMR techniques. Relaxation time and diffusion rates will be determined and compared to show the mimicking capability of the polymer gels to that of biological environments. This will allow for a means in which chemical reactions can be performed in a medium that more closely resembles the rate that the reaction would occur in biological systems.

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Effects Of Monochloramine And Free Chlorine On Copper Dissolution In Drinking Water, Ryan C. Abington Jan 2007

Effects Of Monochloramine And Free Chlorine On Copper Dissolution In Drinking Water, Ryan C. Abington

Opportunities for Undergraduate Research Experience Program (OURE)

The effects of the disinfectant's free chlorine and monochloramine have been studied on thin copper films using the electrochemical quartz crystal microbalance, scanning electron microscopy and x-ray diffraction. It has been found that after twenty-four hours of immersion, the hypochlorite and the monochloramine both convert some of the copper into cuprous oxide. However, after immersion in monochloramine, tiny pinholes in the copper develop on the electrode and the gold substrate is visible underneath. This leads to suggest that while free chlorine may oxidize copper, monochloramine will oxidize copper and can cause pitting in the metal.

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Mesoporous Matrices For Quantum Computation With Improved Response Through Redundance, T. E. Hodgson, Massimo F. Bertino, Nicholas Leventis, Irena D'Amico Jan 2007

Mesoporous Matrices For Quantum Computation With Improved Response Through Redundance, T. E. Hodgson, Massimo F. Bertino, Nicholas Leventis, Irena D'Amico

Physics Faculty Research & Creative Works

We present a solid state implementation of quantum computation, which improves previously proposed optically driven schemes. Our proposal is based on vertical arrays of quantum dots embedded in a mesoporous material which can be fabricated with present technology. The redundant encoding typical of the chosen hardware protects the computation against gate errors and the effects of measurement induced noise. The system parameters required for quantum computation applications are calculated for II-VI and III-V materials and found to be within the experimental range. The proposed hardware may help minimize errors due to polydispersity of dot sizes, which is at present one …

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Crosslinking 3d Assemblies Of Silica Nanoparticles (Aerogels) By Surface-Initiated Free Radical Polymerization Of Styrene And Methylmethacrylate, Nicholas Leventis, Chariklia Sotiriou-Leventis, Sudhir Mulik Jan 2007

Crosslinking 3d Assemblies Of Silica Nanoparticles (Aerogels) By Surface-Initiated Free Radical Polymerization Of Styrene And Methylmethacrylate, Nicholas Leventis, Chariklia Sotiriou-Leventis, Sudhir Mulik

Chemistry Faculty Research & Creative Works

Quasi-stable, ultra-low density, three-dimensional assemblies of nanoparticles are referred to as aerogels. Aerogels are open-cell foams derived from supercritical fluid (SCF) drying of wet gels. Their large internal void space is responsible for low dielectric constants, low thermal conductivities and high acoustic impedance. At the same time though those materials are fragile and impractical for high load applications. The fragility problem has been addressed by casting a thin conformal polymer coating over the entire internal porous surface of the nanostructure.1 That process is referred to as crosslinking. The coating connects chemically skeletal nanoparticles and renders interparticle necks wider. Thus, the …

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Irradiation And Metal-Containing Conjugated-Polymer Nanocomposites, Frank D. Blum, Zhe-Fei Li, Sunil K. Pillalamarri, Massimo F. Bertino Jan 2007

Irradiation And Metal-Containing Conjugated-Polymer Nanocomposites, Frank D. Blum, Zhe-Fei Li, Sunil K. Pillalamarri, Massimo F. Bertino

Chemistry Faculty Research & Creative Works

In recent years, there has been considerable interest in inorganic/organic hybrid materials that combine the desirable properties of both classes. These composite materials may find significant application in a variety of applications such as sensors, memory and energy conversion, to name just a few. In our laboratories, we have recently made a series of studies on the production of polymer nanofibers and their composites with nanometals. Much of this work has focused on the production of polyaniline (PANI) nanofibers that have been made from one-pot syntheses in aqueous solutions where the polymerization was influenced by -radiation1 or UV-radiation.2 in the …

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A Mössbauer Spectral Study Of The Gdco₄₋ₓfeₓb Compounds, Fernande Grandjean, Raphäel P. Hermann, Eustachy S. Popiel, Gary J. Long Jan 2007

A Mössbauer Spectral Study Of The Gdco₄₋ₓfeₓb Compounds, Fernande Grandjean, Raphäel P. Hermann, Eustachy S. Popiel, Gary J. Long

Chemistry Faculty Research & Creative Works

The iron-57 Mössbauer spectra of the GdCo4-xFexB compounds, where x is 0.10, 0.15, 0.20, 0.25, 1, 2, 2.5, and 2.6, have been measured at room temperature and reveal relatively small iron hyperfine fields of approximately 12-18 T, relatively large quadrupole interactions of approximately +0.9 and -1 mm/s, and three very different types of spectra for x=0.10 and 0.15, x=0.25, 1, and 2, and x=2.5 and 2.6. The differences result from both the different easy magnetization directions in these compounds and the different cobalt and/or iron occupancies of the crystallographic 2c and 6i sites. The spectra have …

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Quantification Of Steroid Sex Hormones Using Solid-Phase Extraction Followed By Liquid Chromatography-Mass Spectrometry, Youssef Filali-Meknassi, Muriel Auriol, Craig D. Adams, Rao Y. Surampalli Jan 2007

Quantification Of Steroid Sex Hormones Using Solid-Phase Extraction Followed By Liquid Chromatography-Mass Spectrometry, Youssef Filali-Meknassi, Muriel Auriol, Craig D. Adams, Rao Y. Surampalli

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, the occurrence of trace amounts of natural and synthetic steroid estrogens in the aquatic environment was studied using liquid chromatography coupled with electrospray mass spectrometry, following solid-phase extraction (SPE). the SPE was performed with C18 and NH2 cartridges. the first objective was to develop a reliable method for analyzing steroid estrogens (resulting from human and animal excretions) in different matrices. the method developed was then applied to quantify the occurrence of natural and synthetic hormones (estrone [E1], 17β-estradiol [βE2], 17α-estradiol [αE2], estriol [E3], and 17α-ethinylestradiol [EE2]) in environmental samples in surface water and wastewater treatment plant (WWTP) …

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Hyphenated Hplc-Ms Technique For Analysis Of Compositional Monosaccharides Of Transgenic Corn Glycoprotein And Characterization Of Degradation Products Of Diazinon, Fonofos And Aldicarb In Various Oxidation Systems, Tongwen Wang Jan 2007

Hyphenated Hplc-Ms Technique For Analysis Of Compositional Monosaccharides Of Transgenic Corn Glycoprotein And Characterization Of Degradation Products Of Diazinon, Fonofos And Aldicarb In Various Oxidation Systems, Tongwen Wang

Doctoral Dissertations

"The studies of this dissertation are composed of two sections. The first one deals with the analysis of compositional monosaccharides of transgenic corn glycoproteins. The method used in this study involved derivatization of monosaccharides with two fluorophores followed by HPLC/fluorescence detection for quantitative studies, and by HPLC/SSI/MS for identification confirmation of individual monosaccharide...The second section investigates the degradation processes of several pesticides including diazinon, fonofos and aldicarb in various oxidation systems"--Abstract, page iv.

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Physical Analysis Of Human Hair, Lea Marie Dankers Jan 2007

Physical Analysis Of Human Hair, Lea Marie Dankers

Masters Theses

"Physical analysis of human hair has been performed to determine the effects of chemical treatments on hair samples. Five samples including an untreated sample were analyzed using various methods. The methods included differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and carbon-13 cross polarization/magic-angle spinning nuclear magnetic resonance (¹³C CP/MAS NMR)"--Abstract, page iii.

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Synthetic Methods For Biologically Relevant Organofluorine Compounds, Meher Perambuduru Jan 2007

Synthetic Methods For Biologically Relevant Organofluorine Compounds, Meher Perambuduru

Doctoral Dissertations

"This thesis describes novel synthetic methodologies for the synthesis of biologically relevant organofluorine compounds"--Abstract, page iii.

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Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony Jan 2007

Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony

Doctoral Dissertations

"Ethanol and ionizing radiation exposure are independently known to cause tissue damage through various mechanisms. Non-enzymatic and enzymatic metabolism of ethanol, the latter via the cytochrome P₄₅₀2E1-dependent pathway, produces free radicals which deplete cellular glutathione (GSH). Ionizing radiation exposure has been shown to induce lipid peroxidation, DNA damage, protein oxidation, and GSH depletion, as well. It was postulated that initial exposure to ethanol, followed by ionizing radiation, would result in heightened oxidative stress. The in vitro model used in this investigation was HepG2 cells (human hepatocellular liver carcinoma cell line), while the in vivo model was Cd-1 mice"--Abstract, page iii.

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Energetics Of Oxaspirocycle Prototypes: 1,7-Dioxaspiro[5.5]Undecane And 1,7,9-Trioxadispiro[5.1.5.3]Hexadecane, Abby Jones Weldon, Gregory S. Tschumper Nov 2006

Energetics Of Oxaspirocycle Prototypes: 1,7-Dioxaspiro[5.5]Undecane And 1,7,9-Trioxadispiro[5.1.5.3]Hexadecane, Abby Jones Weldon, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

(Chemical Equation Presented) The relative gas-phase energetics of several low-lying isomers of 1,7-dioxaspiro[5.5]undecane and 1,7,9-trioxadispiro[5.1.5. 3]hexadecane have been calculated with second-order Møller-Plesset perturbation theory and basis sets as large as aug-cc-pVQZ. Relative energies in THF, dichloromethane, acetone, and DMSO have been estimated with corrections from polarized continuum model calculations at the B3LYP/6-311+G(d) level. In the most stable conformation of 1,7-dioxaspiro[5.5]undecane, both rings adopt chair conformations, and both oxygens are axially disposed (2A). It is more than 2 kcal mol-1 more stable than all the other conformers. In agreement with previous work, the "twist-boat" trans isomer (3A) is the most …

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Multicentered Integrated Qm:Qm Methods For Weakly Bound Clusters: An Efficient And Accurate 2-Body:Many-Body Treatment Of Hydrogen Bonding And Van Der Waals Interactions, Gregory S. Tschumper Aug 2006

Multicentered Integrated Qm:Qm Methods For Weakly Bound Clusters: An Efficient And Accurate 2-Body:Many-Body Treatment Of Hydrogen Bonding And Van Der Waals Interactions, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

An efficient integrated QM:QM technique for the description of weakly bound clusters is presented. The computational technique described here takes advantage of the recently developed multicentered (MC) integrated QM:QM methods and reliably describes hydrogen bonding and van der Waals interactions by treating all 2-body interactions with a high-level QM method and the many-body interactions with a low-level QM method. Even for small clusters of He, Ne, HF, and water, the MC QM:QM methods are typically 1-3 orders of magnitude faster than the high-level method while introducing an error of less than 1% in the interaction energy. © 2006 Elsevier B.V. …

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Microwave Reflectometry As A Novel Diagnostic Tool For Detection Of Skin Cancers, Pratik Mehta, Kundan Chand, Deepak Narayanswamy, Daryl G. Beetner, R. Zoughi, William V. Stoecker Aug 2006

Microwave Reflectometry As A Novel Diagnostic Tool For Detection Of Skin Cancers, Pratik Mehta, Kundan Chand, Deepak Narayanswamy, Daryl G. Beetner, R. Zoughi, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

More than 1 000 000 people are diagnosed with skin cancer each year in the United States, and more than 10 000 people die from the disease. Methods such as visual inspection and dermoscopy are available for early detection of skin cancers, but improvement in accuracy is needed. This paper investigates the use of microwave reflectometry as a potential diagnostic tool for detection of skin cancers. Open-ended coaxial probes were used to measure microwave properties of skin. The influences of measurement parameters such as probe application pressure, power level, and variation in reflection properties of skin with location and hydration …

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Direct Experimental Evidence For The Atomic Tunneling Of Europium In Crystalline Eu₈Ga₁₆Ge₃₀, Raphäel P. Hermann, Veerle M. Keppens, Pierre Bonville, George S. Nolas, Fernande Grandjean, Gary J. Long, Hans Martin Christen, Bryan C. Chakoumakos, Brian C. Sales, David G. Mandrus Jul 2006

Direct Experimental Evidence For The Atomic Tunneling Of Europium In Crystalline Eu₈Ga₁₆Ge₃₀, Raphäel P. Hermann, Veerle M. Keppens, Pierre Bonville, George S. Nolas, Fernande Grandjean, Gary J. Long, Hans Martin Christen, Bryan C. Chakoumakos, Brian C. Sales, David G. Mandrus

Chemistry Faculty Research & Creative Works

Mössbauer-effect and microwave absorption experimental evidence unambiguously demonstrates the presence of slow, ~450 MHz, tunneling of magnetic europium between four equivalent sites in Eu8Ga16Ge30, a stoichiometric clathrate. Remarkably, six of the eight europium atoms, or 11% of the constituents in this solid, tunnel between these four sites separated by 0.55 Å. The off centering of the atoms or ions in crystalline clathrates appears to be a promising route for producing Rabi oscillators in solid-state materials.

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Characterizing The Potential Energy Surface Of The Water Dimer With Dft: Failures Of Some Popular Functionals For Hydrogen Bonding, Julie A. Anderson, Gregory S. Tschumper Jun 2006

Characterizing The Potential Energy Surface Of The Water Dimer With Dft: Failures Of Some Popular Functionals For Hydrogen Bonding, Julie A. Anderson, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

Ten stationary points on the water dimer potential energy surface have been examined with ten density functional methods (X3LYP, B3LYP, B971, B98, MPWLYP, PBE1PBE, PBE, MPW1K, B3P86, and BHandHLYP). Geometry optimizations and vibrational frequency calculations were carried out with the TZ2P(f,d)+dif basis set. All'ten of the density functionals correctly describe the relative energies of the ten stationary points. However, correctly describing the curvature of the potential energy surface is far more difficult. Only one functional (BHandHLYP) reproduces the number of imaginary frequencies from CCSD(T) calculations. The other nine density functionals fail to correctly characterize the nature of at least one …

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Isotopes Tell Sun's Origin And Operation, Oliver Manuel, Sumeet A. Kamat, Michael Mozina Jun 2006

Isotopes Tell Sun's Origin And Operation, Oliver Manuel, Sumeet A. Kamat, Michael Mozina

Chemistry Faculty Research & Creative Works

Modern versions of Aston's mass spectrometer enable measurements of two quantities - isotope abundances and masses - that tell the Sun's origin and operation. Isotope analyses of meteorites, the Earth, Moon, Mars, Jupiter, the solar wind, and solar flares over the past 45 years indicate that fresh, poorly-mixed, supernova debris formed the solar system. The iron-rich Sun formed on the collapsed supernova core and now itself acts as a magnetic plasma diffuser, as did the precursor star, separating ions by mass. This process covers the solar surface with lightweight elements and with the lighter isotopes of each element. Running difference …

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Cerium-Based Spontaneous Coating Process For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Matthew O'Keefe, Eric L. Morris, Scott A. Hayes, Paul Yu, Alex Williams, Berny F. Rivera Vasquez, Xuan Lin May 2006

Cerium-Based Spontaneous Coating Process For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Matthew O'Keefe, Eric L. Morris, Scott A. Hayes, Paul Yu, Alex Williams, Berny F. Rivera Vasquez, Xuan Lin

Chemistry Faculty Research & Creative Works

A cerium-based coating for corrosion resistance is applied by exposing a cleaned aluminum-based component to a corrosion-inhibiting cerium solution containing cerium ions in the presence of an oxidizing agent. The coating deposits spontaneously without an external source of electrons.

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Molecular Dynamics Of Polystyrene Solutions In Microwave Fields, Mark J. Purdue, James M. D. Macelroy, D. F. O'Shea, Macduff O. Okuom, Frank D. Blum May 2006

Molecular Dynamics Of Polystyrene Solutions In Microwave Fields, Mark J. Purdue, James M. D. Macelroy, D. F. O'Shea, Macduff O. Okuom, Frank D. Blum

Chemistry Faculty Research & Creative Works

Equilibrium and nonequilibrium molecular dynamics simulation techniques were used to assess the influence of an applied microwave field on the dynamics of methylamine-methanol and methylamine-dimethylformamide (DMF) solutions bound within atactic polystyrene over a range of polymer densities from 35 to 96 wt % polymer. Atomistically detailed systems were studied, ranging from 3000 to 10 644 particles, using previously established potential models. Structural and dynamical properties were determined in the canonical (NVT) ensemble at 298 K. The simulated DMF self-diffusion coefficients in polystyrene solutions were compared with the zero-field experimental results established with pulsed-gradient spin-echo NMR spectrometry. A simulated external microwave …

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Thermal Analysis Of Adsorbed Poly(Methyl Methacrylate) On Silica, Frank D. Blum, Erin N. Young, Gregory Smith, Oliver C. Sitton May 2006

Thermal Analysis Of Adsorbed Poly(Methyl Methacrylate) On Silica, Frank D. Blum, Erin N. Young, Gregory Smith, Oliver C. Sitton

Chemistry Faculty Research & Creative Works

Modulated differential scanning calorimetry has been used to quantify the glass transitions of small, adsorbed amounts of poly (methyl methacrylate) (PMMA) on silica. While a relatively narrow, single glass transition was found for bulk PMMA, broader two-component transitions were found for the adsorbed polymer. a two-state model based on loosely bound polymer (glass transition similar to bulk) and more tightly bound polymer (glass transition centered around 156°C) was used to interpret the thermograms. on the basis of this model, the amount of tightly bound polymer was found to be approximately 1.3 mg/m 2, corresponding to a 1.1 nm thick layer. …

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Generating Long-Lasting ¹H And ¹³C Hyperpolarization In Small Molecules With Parahydrogen-Induced Polarization, Thorsten Jonischkeit, Ute Bommerich, Jorg Stadler, Klaus Woelk, Heiko G. Niessen, Joachim Bargon May 2006

Generating Long-Lasting ¹H And ¹³C Hyperpolarization In Small Molecules With Parahydrogen-Induced Polarization, Thorsten Jonischkeit, Ute Bommerich, Jorg Stadler, Klaus Woelk, Heiko G. Niessen, Joachim Bargon

Chemistry Faculty Research & Creative Works

Recently, Levitt and co-workers demonstrated that conserving the population of long-lasting nuclear singlet states in weak magnetic fields can lead to a preservation of nuclear spin information over times substantially longer than governed by the (high-field) spin-lattice relaxation time T1. Potential benefits of the prolonged spin information for magnetic resonance imaging and spectroscopy were pointed out, particularly when combined with the parahydrogen induced polarization (PHIP) methodology. In this contribution, we demonstrate that an increase of the effective relaxation time by a factor up to three is achieved experimentally, when molecules hyperpolarized by PHIP are kept in a weak …

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Magnetic And Electronic Properties Of Eu₄Sr₄Ga₁₆Ge₃₀, Gerald T. Woods, Joshua B. Martin, Matthew Beekman, Raphäel P. Hermann, Fernande Grandjean, Veerle M. Keppens, Olaf Leupold, Gary J. Long, George S. Nolas May 2006

Magnetic And Electronic Properties Of Eu₄Sr₄Ga₁₆Ge₃₀, Gerald T. Woods, Joshua B. Martin, Matthew Beekman, Raphäel P. Hermann, Fernande Grandjean, Veerle M. Keppens, Olaf Leupold, Gary J. Long, George S. Nolas

Chemistry Faculty Research & Creative Works

Magnetization, static and ac magnetic susceptibility, nuclear forward scattering, and electrical resistivity measurements have been performed on polycrystalline Eu4Sr4Ga16Ge30, a type I clathrate that has divalent strontium and europium ions encapsulated within a Ga-Ge framework. These data are compared with those of type I clathrates Eu8Ga16Ge30 and Eu6Sr2Ga16Ge30. The ferromagnetic ordering of these Eu-containing clathrates is substantially altered by the incorporation of strontium, as compared to Eu8Ga16Ge30. Ferromagnetism, accompanied by a relatively large …

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Identification Of The Binding Region Of The [2fe-2s] Ferredoxin In Stearoyl-Acyl Carrier Protein Desaturase: Insight Into The Catalytic Complex And Mechanism Of Action, Pablo Sobrado, Karen S. Lyle, Steven P. Kaul, Michelle M. Turco, Ida Arabshahi, Ashok Marwah, Brian G. Fox Apr 2006

Identification Of The Binding Region Of The [2fe-2s] Ferredoxin In Stearoyl-Acyl Carrier Protein Desaturase: Insight Into The Catalytic Complex And Mechanism Of Action, Pablo Sobrado, Karen S. Lyle, Steven P. Kaul, Michelle M. Turco, Ida Arabshahi, Ashok Marwah, Brian G. Fox

Chemistry Faculty Research & Creative Works

Stearoyl-acyl carrier protein desaturase (Δ9D) catalyzes the O 2 and 2e- dependent desaturation of stearoyl-acyl carrier protein (18:0-ACP) to yield oleoyl-ACP (18:1-ACP). The 2e- are provided by essential interactions with reduced plant-type [2Fe-2S] ferredoxin (Fd). We have investigated the protein-protein interface involved in the Fd-Δ9D complex by the use of chemical cross-linking, site-directed mutagenesis, steady-state kinetic approaches, and molecular docking studies. The treatment of the different proteins with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide revealed that carboxylate residues from Fd and lysine residues from Δ9D contribute to cross-linking. The single substitutions of K60A, K56A, and K230A on Δ9D decreased the k …

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2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla Apr 2006

2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla

Undergraduate Research Conference at Missouri S&T

No abstract provided.

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Large Scale Growth And Magnetic Properties Of Fe And Fe₃O₄ Nanowires, Jinbo Yang, H. Xu, Shaoxin You, X.-D. Zhou, C. S. Wang, William B. Yelon, William Joseph James Apr 2006

Large Scale Growth And Magnetic Properties Of Fe And Fe₃O₄ Nanowires, Jinbo Yang, H. Xu, Shaoxin You, X.-D. Zhou, C. S. Wang, William B. Yelon, William Joseph James

Materials Science and Engineering Faculty Research & Creative Works

Fe and Fe3O4 nanowires have been synthesized by thermal decomposition of Fe(CO)5, followed by heat treatments. The Fe wires are formed through the aggregation of nanoparticles generated by decomposition of Fe(CO)5. A core-shell structure with an iron oxide shell and Fe core is observed for the as-prepared Fe wires. Annealing in air leads to the formation of Fe2O3/Fe3O4 wires, which after heat treatment in a N2/alcohol atmosphere form Fe3O4 wires with a sharp Verwey [Nature (London) 144, 327 (1939)] transition at 125 K. The Fe3O4 wires have coercivities of 261 and 735 Oe along the wire axis at RT and …

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