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- Nuclear Magnetic Resonance (3)
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- (±)-1-methyl-1,3,6-triphenyl-7-(2-phenylpropenyl)-1 (1)
- 2-dihydronaphthalene (1)
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- Computerized physician order entry (1)
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Articles 1 - 30 of 34
Full-Text Articles in Entire DC Network
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
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 …
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
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. …
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
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 …
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
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.
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
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 …
Isotopes Tell Sun's Origin And Operation, Oliver Manuel, Sumeet A. Kamat, Michael Mozina
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 …
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
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.
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
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 …
Thermal Analysis Of Adsorbed Poly(Methyl Methacrylate) On Silica, Frank D. Blum, Erin N. Young, Gregory Smith, Oliver C. Sitton
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. …
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
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 …
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
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 …
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
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 …
2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla
2nd Annual Undergraduate Research Conference Abstract Book, University Of Missouri--Rolla
Undergraduate Research Conference at Missouri S&T
No abstract provided.
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
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 …
Structural And Magnetic Properties Of La Mn₁₋ₓfeₓo₃ (0 < X < 1.0), X.-D. Zhou, L. R. Pederson, Qingsheng Cai, Jinbo Yang, B. J. Scarfino, M. Kim, William B. Yelon, William Joseph James, Harlan U. Anderson, C. Wang
Structural And Magnetic Properties Of La Mn₁₋ₓfeₓo₃ (0 < X < 1.0), X.-D. Zhou, L. R. Pederson, Qingsheng Cai, Jinbo Yang, B. J. Scarfino, M. Kim, William B. Yelon, William Joseph James, Harlan U. Anderson, C. Wang
Materials Science and Engineering Faculty Research & Creative Works
Electronic, structural, and magnetic properties of Mn-doped lanthanum ferrites were studied by neutron diffraction, superconducting quantum interference device, and impedance spectroscopy. Neutron diffraction refinements were performed with the constraint of full La occupancy, which showed the presence of excess oxygen when x < 0.4. Mixed valent Mn cations and cation vacancies, therefore, exist in all the samples. The samples with x > 0.7 are magnetically ordered at room temperature with orthorhombic symmetry (Pbnm). When x < 0.3 the structure is rhombohedral and magnetically disordered above 16 K. The majority carriers, electron holes, correspond to high oxidation states of Mn. The carrier concentration is determined from the Seebeck coefficients, and is a function of temperature and Fe concentration. The measurements of conductivity and Seebeck coefficients show polaron hopping at elevated temperatures.
Macrocyclic Antibiotics As Separation Agents, Daniel W. Armstrong
Macrocyclic Antibiotics As Separation Agents, Daniel W. Armstrong
Chemistry Faculty Research & Creative Works
Macrocyclic antibiotics having ring structures with at least 10 members act as separation agents in crystallization, precipitation, filtration, electrophoresis, and chromatography. The macrocyclic antibiotics include ansamacrolides, macrolides, macrocyclic peptides, polyenes and derivatives thereof. The process has been found to be especially advantageous for separation of optical isomers by electrophoresis and chromatography.
Nanometal Containing Nanocomposites And Photolithographic Polyaniline Nanofibers, Frank D. Blum, Sunil K. Pillalamarri, Lalani K. Werake, J. Greg Story, Massimo F. Bertino, Akira Tokuhiro
Nanometal Containing Nanocomposites And Photolithographic Polyaniline Nanofibers, Frank D. Blum, Sunil K. Pillalamarri, Lalani K. Werake, J. Greg Story, Massimo F. Bertino, Akira Tokuhiro
Chemistry Faculty Research & Creative Works
A report on recent progress from our laboratories on the nanostructures produced from novel synthesis techniques will be discussed. Using high-energy radiation (γ-rays) we have been able to produce conducting polymer nanofibers and nanorods of polyaniline and polypyrrole without the use of a separate template or capping agent. This technique has been extended, with the addition of metal ions, to a "one pot" synthesis, producing conducting nanocomposites. These nanocomposites contain metal nanoparticles which decorate the conducting nanofibers. We have also recently shown that these systems can be photopatterned to produce novel structures. We believe that these systems will be useful …
Reliable Electron Affinities Of Perfluorocyclopropane And Perfluorocyclobutane From Convergent Ab Initio Computations, Adel M. Elsohly, Macey L. Renault, Gregory S. Tschumper
Reliable Electron Affinities Of Perfluorocyclopropane And Perfluorocyclobutane From Convergent Ab Initio Computations, Adel M. Elsohly, Macey L. Renault, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
To resolve discrepancies concerning the magnitude of the electron affinities of perfluoro cyclopropane and perfluorocyclobutane, quantum chemical calculations have been carried out with the MP2 and CCSD(T), methods in conjunction with augmented correlation consistent basis sets (aug-cc-pVX Z, X = D, T, Q). Though no experimental values have been found for perfluoro cyclopropane, we estimate its electron affinity to be 0.17 eV (0.00 eV without zero-point vibrational energy corrections). In addition, determination of the electron affinity of perfluorocyclobutane (0.61 and 0.44 eV with and without zero-point vibrational energy corrections, respectively) is in good agreement with experimental values reported by Miller …
(±)-1-Methyl-1,3,6-Triphenyl-7-(2-Phenylpropenyl)-1, 2-Dihydronaphthalene, Yongqiang Sui, Charles Leslie Barnes, Rainer Glaser
(±)-1-Methyl-1,3,6-Triphenyl-7-(2-Phenylpropenyl)-1, 2-Dihydronaphthalene, Yongqiang Sui, Charles Leslie Barnes, Rainer Glaser
Chemistry Faculty Research & Creative Works
The crystal structure of the title compound, C38H32, presents a novel framework that combines the functionalities of a 1,6-diarene-substituted 1,2-dihydronaphthalene (DHN) with a 1,4-distyrylbenzene (DSB) to form a crossed bis-diarene. The lamellar crystal structure is held together by arene-arene interactions. While the orientations of the phenyl rings of the DSB units alternate within both the R and the S substructures, the homochiral substructures feature opposing polarity along the long axes of the DHN-based diarenes.
Adapting User Interface To Expedite Physician Order Entry: A Frontline To Ensure Patient Safety, Chiang S. Jao, Daniel B. Hier
Adapting User Interface To Expedite Physician Order Entry: A Frontline To Ensure Patient Safety, Chiang S. Jao, Daniel B. Hier
Chemistry Faculty Research & Creative Works
Preventable Medical Errors Are a Major Problem in Healthcare. Maintenance of Accurate Problem Lists and Drug Lists in the Electronic Medical Record is Critical to the Practice of Medicine and Patient Safety. We Built a Simulator of a Clinical Decision Support System that Automates the Process of Maintaining an Electronic Problem List by Processing Drug Order Requests from a Simulated Computerized Physician Order Entry System. Preliminary Results Revealed that the Productivity of the System Increased When the User Interface Was Improved. This Study Highlights the Importance of an Enhanced User Interface as a Frontline in Expediting Physician Data Entry, Streamlining …
Residual Stress Distribution, Intermolecular Force, And Frictional Coefficient Maps In Diamond Films: Processing-Structure-Mechanical Property Relationship, Sanju Gupta, Oliver Williams, R. J. Patel, Eric W. Bohannan, P. W. May
Residual Stress Distribution, Intermolecular Force, And Frictional Coefficient Maps In Diamond Films: Processing-Structure-Mechanical Property Relationship, Sanju Gupta, Oliver Williams, R. J. Patel, Eric W. Bohannan, P. W. May
Chemistry Faculty Research & Creative Works
Carbon in its various forms, specifically nanocrystalline diamond, may become a key material for the manufacturing of micro- and nano-electromechanical (M/NEMS) devices in the 21st Century. in order to utilize effectively these materials for M/NEMS applications, understanding of their microscopic structure and physical properties (mechanical, in particular) become indispensable. the micro- and nanocrystalline diamond films were grown using hot-filament and microwave chemical vapor deposition techniques involving novel CH4 / [TMB for boron doping and H2S for sulfur incorporation] in high hydrogen dilution chemistry. to investigate residual stress distribution and intermolecular forces at the nanoscale, the films were characterized using Raman …
Segmental Mobility Of Chain Ends In Poly(Methyl Acrylate)-D3, Burak Metin, Frank D. Blum
Segmental Mobility Of Chain Ends In Poly(Methyl Acrylate)-D3, Burak Metin, Frank D. Blum
Chemistry Faculty Research & Creative Works
Better control of polymeric materials can be achieved with a thorough understanding of the dynamics of their constituents. In the present study, we consider polymer chains as composed of chain middles and chain ends. Even though chain ends do not comprise much of the sample by mass, they may play a crucial role in the ultimate properties of the polymers. Although chain ends have been assigned a higher mobility, as compared to chain middles, there have not been a large number of experimental studies that directly probe their mobility. Among those, the studies of Kitahara et al.1 and Miwa et …
Separation And Quantification Of N-Acetylcysteine-Amide (Naca) By Hplc With Fluorescence Detection, Wei Wu, Glenn Goldstein, Craig D. Adams, Richard H. Matthews, Nuran Ercal
Separation And Quantification Of N-Acetylcysteine-Amide (Naca) By Hplc With Fluorescence Detection, Wei Wu, Glenn Goldstein, Craig D. Adams, Richard H. Matthews, Nuran Ercal
Chemistry Faculty Research & Creative Works
N-acetyl-l-cysteine (NAC) is a well-known antioxidant that is capable of facilitating glutathione (GSH) biosynthesis and replenishing intracellular GSH under oxidatively challenging circumstances. N-acetyl-cysteine-amide (NACA), the amide form of NAC, is a newly designed and synthesized thiol-containing compound which is believed to be more lipophilic and permeable through cell membranes than NAC. The metabolic and antioxidant effects of these compounds in vitro and in vivo are under investigation. However, an analytical method that can separate and quantify both compounds simultaneously is not yet available, to the best of our knowledge. Because of their structural similarities, the two compounds are difficult to …
Crystal And Electronic Structures Of Linh₂, Jinbo Yang, X.-D. Zhou, Qingsheng Cai, William Joseph James, William B. Yelon
Crystal And Electronic Structures Of Linh₂, Jinbo Yang, X.-D. Zhou, Qingsheng Cai, William Joseph James, William B. Yelon
Materials Science and Engineering Faculty Research & Creative Works
The crystal structure of LiNH2 was reinvestigated using powder neutron diffraction with high sensitivity. The compound crystallizes in the tetragonal space group I4 with lattice parameters α = b= 5.034 42 (24) Å, c = 10.255 58 (52) Å. It is found that H atoms occupy 8g1(0.2429, 0.1285, 0.1910) and 8g2 (0.3840, 0.3512, 0.1278) sites. The bond lengths between the nearest nitrogen and hydrogen atoms are 0.986 and 0.942 Å, respectively. The bond angle between H-N-H is about 99.97°. These results are significantly different from those of previous experiments. The electronic structure was calculated according to the revised structural …
Segmental Dynamics Of Poly(Isopropyl Acrylate)-D7 On Silica, Piyawan Krisanangkura, Frank D. Blum
Segmental Dynamics Of Poly(Isopropyl Acrylate)-D7 On Silica, Piyawan Krisanangkura, Frank D. Blum
Chemistry Faculty Research & Creative Works
For a polymer film deposited on a surface, the strength of the surfacesegment interaction affects the mobility of polymer-chain segments. The selfconsistent field lattice model of Scheutjens and Fleer,1 based on mean-field lattice models of polymer at interfaces,2 has been used to describe the distribution of conformations of polymers on surfaces. Adsorbed-polymer segments may be classified as belonging to loops, trains or tails. There are different techniques used to study the molecular motion of the polymer including modulated differential scanning calorimetry (MDSC)3 and nuclear magnetic resonance (NMR).4,5 in this work, solid-state deuterium (2H) NMR was used to characterize the polymer …
Synthesis And Thermal Behavior Of Poly(Methyl Acrylate) Attached To Silica By Surface-Initiated Atrp, Manikantan B. Nair, Frank D. Blum
Synthesis And Thermal Behavior Of Poly(Methyl Acrylate) Attached To Silica By Surface-Initiated Atrp, Manikantan B. Nair, Frank D. Blum
Chemistry Faculty Research & Creative Works
The modification of the surface of an object dictates the response of the object to an external environment.1 Surface-modified materials and nanoparticles have attracted immense interest due to the various desirable electronic, optical and magnetic properties they possess.2 Silica is widely used as an inorganic filler. Surface modification of the silica, with a variety of organic moieties, facilitates the utilization of silica in conjunction with organic systems. The resulting organic/inorganic hybrid materials have significant potential applications. This work reports the synthesis and characterization of modified silica, and poly(methyl acrylate) attached to the modified silica. An observation of the thermal behavior …
Electrochemical Deposition And Characterization Of Fe₃O₄ Films Produced By The Reduction Of Fe(Iii)-Triethanolamine, Hiten M. Kothari, Elizabeth A. Kulp, Steven J. Limmer, Philippe Poizot, Eric W. Bohannan, Jay A. Switzer
Electrochemical Deposition And Characterization Of Fe₃O₄ Films Produced By The Reduction Of Fe(Iii)-Triethanolamine, Hiten M. Kothari, Elizabeth A. Kulp, Steven J. Limmer, Philippe Poizot, Eric W. Bohannan, Jay A. Switzer
Chemistry Faculty Research & Creative Works
In this paper, we demonstrate that films of magnetite, Fe3O4, can be deposited by the electrochemical reduction of a Fe(III)-triethanolamine complex in aqueous alkaline solution. the films were deposited with a columnar microstructure and a [100] preferred orientation on stainless steel substrates. In-plane electrical transport and magnetoresistance measurements were performed on the films after they were stripped off onto glass substrates. the resistance of the films was dependent on the oxygen partial pressure. We attribute the increase in resistance in O2 and the decrease in resistance in Ar to the oxidation and reduction of grain …
Acid-Catalyzed Time-Efficient Synthesis Of Resorcinol-Formaldehyde Aerogels And Crosslinking With Isocyanates, Sudhir Mulik, Chariklia Sotiriou-Leventis, Nicholas Leventis
Acid-Catalyzed Time-Efficient Synthesis Of Resorcinol-Formaldehyde Aerogels And Crosslinking With Isocyanates, Sudhir Mulik, Chariklia Sotiriou-Leventis, Nicholas Leventis
Chemistry Faculty Research & Creative Works
Aerogels are open-cell foams derived from supercritical fluid (SCF) drying of wet gels. Their large internal void space is responsible for low thermal conductivity, high surface area and high acoustic impedance. Most aerogels are based on inorganic metal or semimetal oxide frameworks. Pekala and co-workers synthesized resorcinol-formaldehyde (RF) organic aerogels by poly-condensation of resorcinol with formaldehyde in the presence of Na2CO3 as base catalyst, followed by drying with SCF CO2. Low-density RF aerogels prepared by this method exhibit high porosities (>80%), high surface areas (400-900 m2g-1), ultrafine cell-size (<500 > Å) …
A Comparative Study Of The Properties Of Polar And Nonpolar Solvent/Solute/Polystyrene Solutions In Microwave Fields Via Molecular Dynamics, Mark J. Purdue, Macduff O. Okuom, Frank D. Blum, James M. D. Macelroy, D. F. O'Shea
A Comparative Study Of The Properties Of Polar And Nonpolar Solvent/Solute/Polystyrene Solutions In Microwave Fields Via Molecular Dynamics, Mark J. Purdue, Macduff O. Okuom, Frank D. Blum, James M. D. Macelroy, D. F. O'Shea
Chemistry Faculty Research & Creative Works
The influence of an applied microwave field on the dynamics of methylamine-dichloromethane (DCM) mixtures bound within atactic polystyrene (a-PS) over a range of polymer densities from 30 to 94 wt % polymer was examined using atomistic molecular dynamics simulations. This study is an extension of previous studies on methylamine transport in relatively polar polystyrene solutions of methanol and dimethylformamide [M. J. Purdue et al., J. Chem. Phys. 124, 204904 (2006)]. A direct comparison is made across the three types of polystyrene solutions. Consideration is given to both solvent and reagent transport within the polymer solutions under zero-field conditions and in …
Molecular Mass And Dynamics Of Poly(Methyl Acrylate) In The Glass Transition Region, Burak Metin, Frank D. Blum
Molecular Mass And Dynamics Of Poly(Methyl Acrylate) In The Glass Transition Region, Burak Metin, Frank D. Blum
Chemistry Faculty Research & Creative Works
The segmental dynamics of bulk poly(methyl acrylate) (PMA) were studied as a function of molecular mass in the glass-transition region using 2H NMR and modulated differential scanning calorimetry (MDSC). Quadrupole-echo 2H NMR spectra were obtained for four samples of methyl-deuterated PMA-d3 with different molecular masses. The resulting spectra were fit using superpositions of simulated spectra generated from the MXQET simulation program, based on a model incorporating nearest-neighbor jumps from positions on the vertices of a truncated icosahedron (soccer-ball shape). The lower molecular-mass samples, influenced by the presence of more chain ends, showed more heterogeneity (broader distribution) and lower glass transitions …