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Articles 1 - 21 of 21
Full-Text Articles in Physical Sciences and Mathematics
Weak Ferromagnetism In Fe₁₋ₓcoₓsb₂, Rongwei Hu, Raphäel P. Hermann, Fernande Grandjean, Yong Jae Lee, John B. Warren, Vesna F. Mitrovic, Cedomir Petrovic
Weak Ferromagnetism In Fe₁₋ₓcoₓsb₂, Rongwei Hu, Raphäel P. Hermann, Fernande Grandjean, Yong Jae Lee, John B. Warren, Vesna F. Mitrovic, Cedomir Petrovic
Chemistry Faculty Research & Creative Works
Weak ferromagnetism in Fe1-xCoxSb2 is studied by magnetization and Mössbauer measurements. A small spontaneous magnetic moment of the order of ~ 10-3µB appears along the b axis for 0.2 ≤ x ≤ 0.4. Based on a structural analysis, we argue against extrinsic sources of weak ferromagnetism. We discuss our results in the framework of the nearly magnetic electronic structure of the parent compound FeSb2.
Ammonia Elimination From Protonated Nucleobases And Related Synthetic Substrates, Ming Qian, Shuo Yang, Hong Wu, Papiya S. Majumdar, Nathan D. Leigh, Rainer Glaser
Ammonia Elimination From Protonated Nucleobases And Related Synthetic Substrates, Ming Qian, Shuo Yang, Hong Wu, Papiya S. Majumdar, Nathan D. Leigh, Rainer Glaser
Chemistry Faculty Research & Creative Works
The results are reported of mass-spectrometric studies of the nucleobases adenine 1h (1, R = H), guanine 2h, and cytosine 3h. The protonated nucleobases are generated by electrospray ionization of adenosine 1r (1, R = ribose), guanosine 2r, and deoxycytidine 3d (3, R = deoxyribose) and their fragmentations were studied with tandem mass spectrometry. In contrast to previous EI-MS studies of the nucleobases, NH3 elimination does present a major path for the fragmentations of the ions [1h + H]+, [2h + H]+, and …
⁵⁷Fe Mössbauer Spectral And Muon Spin Relaxation Study Of The Magnetodynamics Of Monodispersed Γ-Fe₂O₃ Nanoparticles, Leïla Rebbouh, Raphäel P. Hermann, Fernande Grandjean, Taeghwan Hyeon, Kwangjin An, Alex Amato, Gary J. Long
⁵⁷Fe Mössbauer Spectral And Muon Spin Relaxation Study Of The Magnetodynamics Of Monodispersed Γ-Fe₂O₃ Nanoparticles, Leïla Rebbouh, Raphäel P. Hermann, Fernande Grandjean, Taeghwan Hyeon, Kwangjin An, Alex Amato, Gary J. Long
Chemistry Faculty Research & Creative Works
The Mössbauer spectra of monodispersed iron oxide nanoparticles with diameters of 4, 7, 9, and 11 nm have been measured between 4.2 and 315 K and fitted within the formalism for stochastic fluctuations of the hyperfine Hamiltonian. In this model, the hyperfine field is assumed to relax between the six ±x, ±y, and ±z directions in space with a distribution of relaxation rates that is temperature dependent. Muon spin relaxation measurements have been carried out on the 9 nm particles between 4.2 and 295 K. Both techniques reveal three regimes in the magnetic dynamics of these nanoparticles. In the low-temperature …
Antimony Vibrations In Skutterudites Probed By ¹²¹Sb Nuclear Inelastic Scattering, Hans Christian Wille, Raphäel P. Hermann, Ilya Sergueev, Olaf Leupold, Peter Van Der Linden, Brian C. Sales, Fernande Grandjean, Gary J. Long, Rudolf Rüffer, Yuri V. Shvyd'ko
Antimony Vibrations In Skutterudites Probed By ¹²¹Sb Nuclear Inelastic Scattering, Hans Christian Wille, Raphäel P. Hermann, Ilya Sergueev, Olaf Leupold, Peter Van Der Linden, Brian C. Sales, Fernande Grandjean, Gary J. Long, Rudolf Rüffer, Yuri V. Shvyd'ko
Chemistry Faculty Research & Creative Works
The specific lattice dynamic properties of antimony in the unfilled CoSb3 and filled EuFe4Sb12 skutterudites have been determined by nuclear inelastic scattering at the 121Sb nuclear resonance energy of 37.1298(2) keV with a 4.5 meV high-resolution backscattering sapphire monochromator. The Sb partial vibrational density of states (DOS) shows a maximum centered at 17 and 16 meV in CoSb3 and EuFe4Sb12, respectively. The difference between the Sb DOSs of CoSb3 and EuFe4Sb12 reveals that upon filling there is a transfer of 10% of the vibrational states toward …
Crystal And Electronic Structures Of The Complex Hydride Li₄Bn₃H₁₀, Jinbo Yang, X. J. Wang, Qingsheng Cai, William B. Yelon, William Joseph James
Crystal And Electronic Structures Of The Complex Hydride Li₄Bn₃H₁₀, Jinbo Yang, X. J. Wang, Qingsheng Cai, William B. Yelon, William Joseph James
Physics Faculty Research & Creative Works
The crystal structure of Li4BN3H10 was investigated using powder neutron diffraction with high sensitivity. The compound crystallizes in the cubic space group 213 with lattice parameters a=10.645 19(52) Å with an ordered arrangement of [NH2]−1 and [BH4]−1 anions in a molar ratio of 3:1. The bond lengths between the nearest nitrogen and hydrogen atoms are 1.04(4) and 1.14(4) Å. The bond angle between H(1)-N-H(2) is about 126(6)°, while those between H(3)-B-H(3) and H(3)-B-H(4) are about 109(6)°-110(7)°. There are three different Li sites surrounded by [NH2]−1 and [BH4]−1 anions in distorted tetrahedral configurations. The Li(3)-B and Li(3)-N bond distances are about …
Additive-Assisted, Cerium-Based, Corrosion-Resistant E-Coating, James O. Stoffer, Thomas J. O'Keefe, Eric L. Morris, Xuan Lin, Scott A. Hayes, Pu Yu
Additive-Assisted, Cerium-Based, Corrosion-Resistant E-Coating, James O. Stoffer, Thomas J. O'Keefe, Eric L. Morris, Xuan Lin, Scott A. Hayes, Pu Yu
Chemistry Faculty Research & Creative Works
Corrosion resistance of metallic components such as stainless steel components of vehicles, and especially aluminum- based components of aircraft, is enhanced by application of an e-coat paint or primer which is enhanced by incorporation of cerium ions into the e-coat electrolytic bath. The resulting overall coating includes a cerium-based layer under a cerium-enhanced e-coat paint or primer layer.
A Polymorph Of K₄Ge₄Se₁₀, Amitava Choudhury, Sabine Strobel, Peter K. Dorhout
A Polymorph Of K₄Ge₄Se₁₀, Amitava Choudhury, Sabine Strobel, Peter K. Dorhout
Chemistry Faculty Research & Creative Works
A new monoclinic polymorph, ?-K4Ge4Se10 (tetra-potassium deca-selenidotetra-germanate), that crystallizes in space group P21/c has been isolated. The structure contains isolated super-tetra-hedral adamantane [Ge4Se10]4- clusters identical to those in the known K4Ge4Se10 polymorph (P21/m), held together in in the crystal structure by ionic inter-action with the K+ ions. The adamantane unit, [Ge4Se10] 4-, is formed by corner-sharing of four GeSe4 tetra-hedra, with average Ge -. Se distances of 2.378 and 2.281 Å for (Ge - Se)endo and (Ge - Se)exo, respectively. There are four crystallographically distinct K + ions in ?-K4Ge4Se10 having coordination numbers of 5, 7. and …
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
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 …
Unleaded Drinking Water: Equilibrium Potential Measurements For Monochloramine Disinfectant, Brandi Clark
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 …
Polymer Gels: Mimickin G Biological Environments, Joshua Carey
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.
Effects Of Monochloramine And Free Chlorine On Copper Dissolution In Drinking Water, Ryan C. Abington
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.
Photosensitization Of Photoconductive And Photorefractive Composites Through The Inclusion Of Semiconductor Nanocrystals, Tyler Martin Fears
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 …
Water Borne Film-Forming Compositions, Michael R. Van-De-Mark, Nantana Jiratumnukul
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 …
Crosslinking 3d Assemblies Of Silica Nanoparticles (Aerogels) By Surface-Initiated Free Radical Polymerization Of Styrene And Methylmethacrylate, Nicholas Leventis, Chariklia Sotiriou-Leventis, Sudhir Mulik
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 …
A Mössbauer Spectral Study Of The Gdco₄₋ₓfeₓb Compounds, Fernande Grandjean, Raphäel P. Hermann, Eustachy S. Popiel, Gary J. Long
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 …
Irradiation And Metal-Containing Conjugated-Polymer Nanocomposites, Frank D. Blum, Zhe-Fei Li, Sunil K. Pillalamarri, Massimo F. Bertino
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 …
Synthetic Methods For Biologically Relevant Organofluorine Compounds, Meher Perambuduru
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.
Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony
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.
Mesoporous Matrices For Quantum Computation With Improved Response Through Redundance, T. E. Hodgson, Massimo F. Bertino, Nicholas Leventis, Irena D'Amico
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 …
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.
Physical Analysis Of Human Hair, Lea Marie Dankers
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.