Archean Phosphorus Liberation Induced By Iron Redox Geochemistry, 2018 University of South Florida
Archean Phosphorus Liberation Induced By Iron Redox Geochemistry, Barry Herschy, Sae Jung Chang, Ruth Blake, Aivo Lepland, Heather Abbott-Lyon, Jacqueline Sampson, Zachary Atlas, Terence P. Kee, Matthew A. Pasek
The element phosphorus (P) is central to ecosystem growth and is proposed to be a limiting nutrient for life. The Archean ocean may have been strongly phosphorus-limited due to the selective binding of phosphate to iron oxyhydroxide. Here we report a new route to solubilizing phosphorus in the ancient oceans: reduction of phosphate to phosphite by iron(II) at low (<200 >°C) diagenetic temperatures. Reduction of phosphate to phosphite was likely widespread in the Archean, as the reaction occurs rapidly and is demonstrated from thermochemical modeling, experimental analogs, and detection of phosphite in early Archean rocks. We further demonstrate that the ...200>
The Effect Of Semiconductor Materials On Solar Cell Efficiency, 2018 Rockdale Magnet School
The Effect Of Semiconductor Materials On Solar Cell Efficiency, Shivam Vohra
The International Student Science Fair 2018
The purpose of this project was to increase the efficiency of solar cells through the use of quantum dots and nanoparticles. These substances would increase the efficiency of the semiconductor. The research hypothesis stated that if lead iodide was applied to the semiconductor, then the average voltage, amperage, power, and efficiency of the solar cells would increase. The procedure for this project involved creating a lead iodide and titanium dioxide mixture with dimethylformamide, ethanol, acetylacetone, and Triton X-100 in an autoclave. Then, two milliliters of each solution were applied to cadmium selenide quantum dots to make four different solutions. Each ...
The Effect Of Distance And Angle On Electronic Couplings Between F8bt-Based Oligomers, 2018 DePaul University
The Effect Of Distance And Angle On Electronic Couplings Between F8bt-Based Oligomers, Jacob H. Wat
Organic semiconductors are often used as light-absorbers in photovoltaic devices and studying the energy flow through these materials is an important field of research. The energy flow is controlled by electronic coupling between the organic semiconductor molecules, which is affected by the distance between the molecules and their relative orientation. Here we calculated the couplings as a function of distance and relative orientation based on semi-empirical calculations of the low-lying excited states of pairs of organic semiconductor molecules. We showed that as distance increased, electronic couplings approach zero. Electronic couplings calculated as a function of rotation were maximized as the ...
Synthesis Of A Bipyridine Ligand For Metal-Triggered Supramolecular Polymers, 2018 DePaul University
Synthesis Of A Bipyridine Ligand For Metal-Triggered Supramolecular Polymers, Andrew D. Gould
Intermolecular forces, such as H-bonding, ionic interactions and metal chelation between small molecules, can lead to the assembly of higher-order supramolecular nanostructures. A metal chelator, 2-(Pyridin-2-yl) pyridine-5-carboxylic Acid (a bipyridine derivative), is expected to aid in the formation of supramolecular structures as part of amphiphilic molecules that self-assemble in solution in the presence of metal ions. The bipyridine ligand currently under synthesis can be prepared through a five-step synthesis scheme. The second reaction of this synthesis (the coupling of two pyridine rings) resulted in a combination of the desired 1,2,5-isomer, as well as an unforeseen 1,2 ...
Investigation On The Dissociative Photoionization Mechanism Of Furfural, Investigation Of The Absolute Photoionization Cross Sections Of Three Potential Propargylic Fuels, And Ab Initio Analysis On Potential Superbases Of Several Hyperlithiated Species: Li3f2o And Li3f2(Oh)N (N = 1, 2, 3), 2018 University of San Francisco
Investigation On The Dissociative Photoionization Mechanism Of Furfural, Investigation Of The Absolute Photoionization Cross Sections Of Three Potential Propargylic Fuels, And Ab Initio Analysis On Potential Superbases Of Several Hyperlithiated Species: Li3f2o And Li3f2(Oh)N (N = 1, 2, 3), Matthew Winfough
This thesis presents the study photoionization cross sections of three different propargylic biofuels; dipropargyl ether, propargyl alcohol, and propargylamine, in chlorine radical-initiated combustion experiments at the Chemical Dynamics Beamline (9.0.2) at the Advanced Light Source of the Ernest Orlando Berkeley National Laboratory in Berkeley, California. Additionally, the unimolecular dissociative photoionization mechanism of furfural was studied using photoelectron photoionization coincidence (PEPICO) spectroscopy at the vacuum ultraviolet beamline at the Swiss Light Source of the Paul Scherrer Institut in Villigen, Switzerland. Dissociation products and mechanisms for furfural were identified over a photon energy range of 10.9 to 14.5 ...
Analytical And Toxicological Evaluation Of Flavor Chemicals In Electronic Cigarette Refill Fluids, 2018 University of California, Riverside
Analytical And Toxicological Evaluation Of Flavor Chemicals In Electronic Cigarette Refill Fluids, Rachel Z. Behar, Wentai Luo, Kevin J. Mcwhirter, James F. Pankow, Prue Talbot
Chemistry Faculty Publications and Presentations
Thousands of electronic cigarette refill fluids are commercially available. The concentrations of nicotine and the solvents, but not the flavor chemicals, are often disclosed on product labels. The purpose of this study was to identify and quantify flavor chemicals in 39 commercial refill fluids that were previously evaluated for toxicity. Twelve flavor chemicals were identified with concentrations ≥1 mg/ml: cinnamaldehyde, menthol, benzyl alcohol, vanillin, eugenol, p-anisaldehyde, ethyl cinnamate, maltol, ethyl maltol, triacetin, benzaldehyde, and menthone. Transfer of these flavor chemicals into aerosols made at 3V and 5V was efficient (mean transfer = 98%). We produced lab-made refill fluids containing ...
X-Ray-Absorption Spectral Study Of The R2Fe17-XMX Solid Solutions (R=Ce, Nd And M=Al, Si), 2018 Missouri University of Science and Technology
X-Ray-Absorption Spectral Study Of The R2Fe17-XMX Solid Solutions (R=Ce, Nd And M=Al, Si), Denis Vandormael, Fernande Grandjean, Valérie Briois, D. P. Middleton, K. H. Buschow, Gary J. Long
Gary J. Long
The x-ray-absorption near-edge structure (XANES) spectra obtained at the cerium LIII edge of the Ce2Fe17-xAlx solid solutions and Ce2Fe14Si3, show two absorption peaks characteristic of the 4f1 and 4f0 configurations of cerium, peaks which indicate that cerium is in a mixed valent state in these compounds. All the XANES spectra have been consistently and excellently fit with one sigmoidal function and two Gaussianbroadened Lorentzian functions. The cerium spectroscopic valence obtained from the relative areas of the two peaks decreases from 3.64 to 3.43 between x=0 and 9 in Ce2Fe17-x,Alx, and correlates linearly with the cerium site ...
Synthesis And Characterization Of Two Metallic Spin-Glass Phases Of Femo4Ge3, 2018 Missouri University of Science and Technology
Synthesis And Characterization Of Two Metallic Spin-Glass Phases Of Femo4Ge3, Peter J. Baker, Peter D. Battle, Stephen J. Blundell, Fernande Grandjean, Thomas M. Lancaster, Gary J. Long, Sophie E. Oldham, Timothy John Prior
Gary J. Long
Polycrystalline samples of FeMo4Ge3 have been synthesized by the reduction of an oxide mixture at 1248 K and characterized by a combination of diffraction, muon spin relaxation (µ+SR), Mössbauer spectroscopy, magnetometry, transport, and heat-capacity measurements. The compound adopts a tetragonal W5Si3 structure (space group I4/mcm); the iron and molybdenum atoms are disordered over two crystallographic sites, 16k and either 4a or 4b. The synthesis conditions determine which fourfold site is selected; occupation of either leads to the presence of one-dimensional chains of transition metals in the structure. In both cases, the electrical resistivity below 200 K is ~175 ...
Structural, Magnetic, And Mössbauer Spectral Properties Of Pr2Fe17HX Where X Is 1, 2, And 3, 2018 Missouri University of Science and Technology
Structural, Magnetic, And Mössbauer Spectral Properties Of Pr2Fe17HX Where X Is 1, 2, And 3, Fernande Grandjean, Dimitri Hautot, Gary J. Long, Olivier Isnard, Salvatore Miraglia, Daniel Fruchart
Gary J. Long
The 295 K unit cell parameters of Pr2Fe17Hx, where x is 0, 1, 2, and 3, have been determined by x-ray diffraction. Upon hydrogenation, the unit cell volume expands anisotropically with a 1.2% expansion of the a axis and no expansion of the c axis for x=3. The Curie temperatures are 286, 374, 440, and 484 K, for x=0, 1, 2, and 3, respectively. The Mössbauer spectra have been measured between 4.2 and 295 K, and the spectra of Pr2Fe17H and Pr2Fe17H2, obtained above 80 K, and those of Pr2Fe17H3, obtained above 120 K, have been ...
Structural And Magnetic Properties Of Y(Al₁₋ₓFeₓ)₁₂, 2018 Missouri University of Science and Technology
Structural And Magnetic Properties Of Y(Al₁₋ₓFeₓ)₁₂, Ying-Chang Yang, Gary J. Long, William Joseph James, R. Yeh
Gary J. Long
In order to investigate the magnetic behavior of 3d atoms in the ThMn12‐type structure, the structured and magnetic properties of Y(Al1-xFex)12 were studied by Mössbauer spectroscopy and magnetization measurements. The Y(Al1-xFex)12 intermetallic compounds crystallize in the ThMn12‐type structure for x in the range of 0.3-0.5. The results can be explained on the basis of the preferential atomic ordering observed in the ternary compounds. The compounds are ferromagnetic with Curie temperatures of 130, 170, and 280 K, respectively, for x values of 0.3, 0.4, and 0.5.
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, 2018 Missouri University of Science and Technology
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Gary J. Long
The magnetic, electronic, and Mössbauer spectral properties of Fe 2L(µ-OAc)2ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm ...
Reply To "Comment On 'Mössbauer Effect Study Of Filled Antimonide Skutterudites'", 2018 Missouri University of Science and Technology
Reply To "Comment On 'Mössbauer Effect Study Of Filled Antimonide Skutterudites'", Gary J. Long, Gary J. Long, Dimitri Hautot, Fernande Grandjean, Donald T. Morelli, Gregory P. Meisner
Gary J. Long
The temperature dependence of the isomer shift of α-iron between 4.2 and 990 K and of Dy3Fe5O12 between 4.2 and 550 K has been analyzed in terms of the Debye model for the second-order Doppler shift, a model in which an additional parameter, the effective vibrating mass, is included. This mass is found equal to 57 g/mol in the ionic compound, Dy3Fe5O12, and equal to 60 g/mol in metallic α-iron. The deviation of this mass from 57 g/mol is a measure of the covalency of the metallic bonding in α-iron. The inadequacy of the graphical ...
One-Step Processing Of Spinel Ferrites Via The High-Energy Ball Milling Of Binary Oxides, 2018 Missouri University of Science and Technology
One-Step Processing Of Spinel Ferrites Via The High-Energy Ball Milling Of Binary Oxides, V. G. Harris, D. J. Fatemi, J. O. Cross, E. E. Carpenter, V. M. Browning, J. P. Kirkland, Amitabh Mohan, Gary J. Long
Gary J. Long
MnZn ferrites have been produced via the high-energy ball milling of binary oxide precursors. The milled ferrites have a nonequilibrium cation site distribution, with an unusually high population of Zn cations on the octahedral sites. The particle size distribution drops precipitously with milling time from 60±1 to ∼14±1 nm at 10 h, but increases to 18.5±1 nm after long durations (20–40 h) concurrent with the formation of nearly pure ferrite. A 1 h anneal at 673 K facilitates a redistribution of cations to their near equilibrium sites. This processing approach circumvents the need for deleterious ...
Polarized Neutron Diffraction And Mössbauer Spectral Study Of Short-Range Magnetic Correlations In The Ferrimagnetic Layered Compounds (Pph4) [FeIiFeIii(Ox)3] And (Nbu4) [FeIiFeIii(Ox)3], 2018 Missouri University of Science and Technology
Polarized Neutron Diffraction And Mössbauer Spectral Study Of Short-Range Magnetic Correlations In The Ferrimagnetic Layered Compounds (Pph4) [FeIiFeIii(Ox)3] And (Nbu4) [FeIiFeIii(Ox)3], Simon G. Carling, Dirk W. Visser, Dimitri Hautot, Ian D. Watts, Peter Day, Jürgen Ensling, Phillip Gütlich, Gary J. Long, Fernande Grandjean
Gary J. Long
Short-range antiferromagnetic correlations have been studied in the layered compounds (PPh4) [FeIIFeIII(ox)3] and (NBu4) [FeIIFeIII(ox)3] by neutron polarization analysis and Mössbauer spectroscopy. Polarized neutron diffraction profiles obtained between 2 and 50 K on (d20-Pph4) [FeIIFeIII(ox)3] show no magnetic Bragg scattering; the lack of such scattering indicates the absence of long-range magnetic order. However, a broad asymmetric feature observed at a Q of ca. 0.8 Å-1 is attributed to two-dimensional short-range magnetic correlations, which are described by a Warren function. The correlation length is ca. 50 Å between 2 and 30 K and then ...
Mössbauer Spectral Study Of The Magnetocaloric Femnp1-XAsX Compounds, 2018 Missouri University of Science and Technology
Mössbauer Spectral Study Of The Magnetocaloric Femnp1-XAsX Compounds, Raphäel P. Hermann, Ojied Tegus, Ekkehard H. Brück, K. H. J. Buschow, Frank R. De Boer, Gary J. Long, Fernande Grandjean
Gary J. Long
The magnetic phase transitions in the FeMnP1-xAsx compounds with x= 0.25, 0.35, 0.45, 0.50, and 0.55, have been studied by iron-57 Mössbauer spectroscopy. The ferromagnetic and antiferromagnetic spectra have been analyzed with a model that takes into account the random distribution of the P and As near-neighbor anions of a given iron site. This distribution is a binomial distribution of the contributions to the spectra of each iron with n As near neighbors. A magnetostriction model has been used to characterize the temperature induced paramagnetic to ferromagnetic first-order phase transition and order parameters, ηF=2 ...
Mössbauer-Effect And X-Ray-Absorption Spectral Study Of Sonochemically Prepared Amorphous Iron, 2018 Missouri University of Science and Technology
Mössbauer-Effect And X-Ray-Absorption Spectral Study Of Sonochemically Prepared Amorphous Iron, Gary J. Long, Dimitri Hautot, Quentin A. Pankhurst, Denis Vandormael, Fernande Grandjean, Jean Pierre Gaspard, Valérie Briois, Taeghwan Hyeon, Kenneth S. Suslick
Gary J. Long
The Mössbauer spectra of amorphous iron, prepared by using sonochemical methods, exhibit a broad magnetic hyperfine sextet at both 78 and 295 K. The spectra do not change with time if the amorphous iron is not exposed to oxygen or moisture. An analysis of the spectra with the method of Lines and Eibschütz yields average magnetic hyperfine fields of 29.1 and 25.9 T at 78 and 295 K, respectively. The corresponding moments of 1.9B and 1.7B agree well with values obtained from earlier magnetization studies and, further, provide strong experimental support for earlier calculations ...
Mössbauer Spectral Study Of The Magnetic Properties Of Ce2Fe17HX (X=0, 1, 2, 3, 4, And 5), 2018 Missouri University of Science and Technology
Mössbauer Spectral Study Of The Magnetic Properties Of Ce2Fe17HX (X=0, 1, 2, 3, 4, And 5), Dimitri Hautot, Gary J. Long, Fernande Grandjean, Olivier Isnard
Gary J. Long
The Mössbauer spectra of Ce2Fe17Hx, where x=0, 1, 2, 3, 4, and 5, have been measured and analyzed between 4.2 and 295 K. Because Ce2Fe17 exhibits a helical magnetic order between 225 and 90 K and a fan magnetic order below 90 K, its Mössbauer spectra were fit with a distribution of hyperfine fields and θ angles for four of the eight magnetically inequivalent sites. Because the hydrides exhibit a magnetization within the basal plane of the hexagonal cell, their Mössbauer spectra were fit with seven sextets. The four isomer ...
Mössbauer And Neutron Diffraction Studies Of Y2(Fe1-XMnX)14B, 2018 Missouri University of Science and Technology
Mössbauer And Neutron Diffraction Studies Of Y2(Fe1-XMnX)14B, Oran Allan Pringle, Gaya Kanishka Marasinghe, Gary J. Long, William Joseph James, William B. Yelon, Decai Xie, Fernande Grandjean
Gary J. Long
We have used Mössbauer spectroscopy and neutron diffraction to study a series of Y2(Fe1-xMnx)1 4B samples in the composition range from x=0.0 to 0.4. Y 2(Fe0.6Mn0.4)14B is paramagnetic at both room temperature and 85 K. The iron quadrupole splitting in this paramagnetic compound allows us to place an upper limit on the quadrupole shift in the magnetic Y2(Fe1-xMnx) 14B alloys. Refinement of Y2(Fe 1-xMnx)14B neutron diffraction data have been used to give the site occupancies of manganese on the transition-metal sublattice. Both neutron diffraction patterns and Mössbauer effect ...
Mössbauer Effect Study Of Filled Antimonide Skutterudites, 2018 Missouri University of Science and Technology
Mössbauer Effect Study Of Filled Antimonide Skutterudites, Gary J. Long, Dimitri Hautot, Fernande Grandjean, Donald T. Morelli, Gregory P. Meisner
Gary J. Long
The iron-57 Mössbauer spectra of a series of Ce-filled antimonide skutterudites, CexFe4-yCoySb12, where x varies from 0.22 to 0.98 and y varies from 0 to 3.5, have been measured at 295 K. In addition, the spectra of Ce0.60Fe2Co2Sb12 and Ce0.82Fe3CoSb12 have been measured from 85 to 295 K and the spectra of Ce0.35FeCo3Sb12 and Ce0.98Fe4Sb12 have been measured from 4.2 to 295 K. The spectra, all of which consist of a simple quadrupole doublet, show no evidence for any long-range magnetic ordering of any Fe magnetic moments. The 295-K quadrupole splitting increases ...
Morphologic And Magnetic Properties Of Pd100-XFeX Nanoparticles Prepared By Ultrasound Assisted Electrochemistry, 2018 Missouri University of Science and Technology
Morphologic And Magnetic Properties Of Pd100-XFeX Nanoparticles Prepared By Ultrasound Assisted Electrochemistry, Maribel Guzman, Jean Luc Delplancke, Gary J. Long, Jacques P. Delwiche, Marie Jeanne Hubin-Franskin, Fernande Grandjean
Gary J. Long
Nanopowdered alloys of Pd100-xFex, with x=4, 6, 8, and 12, have been prepared by ultrasound assisted electrochemistry. The composition of the individual particles, as determined by x-ray fluorescence, and the bulk composition, as determined by atomic absorption, are in agreement within experimental error. Transmission electron microscopy indicates that the nanopowders consist of agglomerates of small grains with a radius of approximately 5 nm, a radius which is confirmed by the broadening of the reflections in the x-ray powder diffraction patterns. X-ray fluorescence analysis of individual grains indicates a homogeneous distribution of palladium and iron throughout the grains. The x-ray ...