Chemistry Commons^™

Doming Modes And Dynamics Of Model Heme Compounds, Dennis D. Klug, Marek Z. Zgierski, John S. Tse, Zhenxian Liu, James R. Kincaid, Kazimierz Czarnecki, Russell J. Hemley

Chemistry Faculty Research and Publications

Synchrotron far-IR spectroscopy and density-functional calculations are used to characterize the low-frequency dynamics of model heme FeCO compounds. The “doming” vibrational mode in which the iron atom moves out of the porphyrin plane while the periphery of this ring moves in the opposite direction determines the reactivity of oxygen with this type of molecule in biological systems. Calculations of frequencies and absorption intensities and the measured pressure dependence of vibrational modes in the model compounds are used to identify the doming and related normal modes.

Enantioselective Synthesis Of The C11–C17 Segment Of Soraphen A1Α Via Organoiron Methodology, Yeyu Cao, Ahmad F Eweas, William Donaldson

Chemistry Faculty Research and Publications

The C11–C17 segment of the antifungal agent soraphen A_1α was prepared from glyceraldehyde acetonide in nine steps. The C12 stereocenter is derived from glyceraldehyde, while the C17 stereocenter as introduced by 1,6-asymmetric control via the coordinated Fe(CO)₃.

The C11–C17 segment of the antifungal agent soraphen A1α, with required inverted stereochemistry at C17, was prepared. The C12 stereocenter is derived from glyceraldehyde, while the C17 stereocenter is introduced by 1,6-asymmetric induction via a coordinated Fe(CO)₃.

Development Of A Systems Engineering Model Of The Chemical Separations Process, Yitung Chen, Randy Clarksean, Darrell Pepper

Separations Campaign (TRP)

The AAA program is developing technology for the transmutation of nuclear waste to address many of the long-term disposal issues. An integral part of this program is the proposed chemical separations scheme. This process, as envisioned by Argonne National Laboratory (ANL) researchers, will be outlined later in this report.

Nearly all issues related to risks to future generations arising from long-term disposal of such spent nuclear fuel is attributable to ~1% of its content. This 1% is made up primarily of plutonium, neptunium, americium, and curium (the transuranic elements) and long-lived isotopes of iodine and technetium created as products from …

Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Abraham F. Jalbout, Hanning Chen, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnOfilms. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to (inverse of the distance from a central ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results.

Creating Nanocavities Of Tunable Sizes: Hollow Helices, Bing Gong, Huaqiang Zeng, Jin Zhu, Lihua Yuan, Yaohua Han, Shizhi Cheng, Mako Furukawa, Ruben D. Parra, Audrey Y. Kovalevsky, Jeffrey L. Mills, Ewa Skrzypczak-Jankun, Suzana Martinovic, Richard D. Smith, Chong Zheng, Thomas Szyperski, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A general strategy for creating nanocavities with tunable sizes based on the folding of unnatural oligomers is presented. The backbones of these oligomers are rigidified by localized, threecenter intramolecular hydrogen bonds, which lead to well-defined hollow helical conformations. Changing the curvature of the oligomer backbone leads to the adjustment of the interior cavity size. Helices with interior cavities of 10 Å to >30 Å across, the largest thus far formed by the folding of unnatural foldamers, are generated. Cavities of these sizes are usually seen at the tertiary and quaternary structural levels of proteins. The ability to tune molecular dimensions …

3. Otto Vogl, Gerald S. Kirshenbaum, Helga Roder

Emeritus Faculty Author Gallery

No abstract provided.

Preliminary Geochemical Evaluation Of Groundwaters From Wells Of The Nye County Early Warning Drilling Program, Irene Farnham, Klaus J. Stetzenbach, Amy J. Smiecinski

Publications (YM)

As part of the Yucca Mountain Oversight program, the Nye County Nuclear Waste Repository Project Office (NWRPO) has established a groundwater monitoring program to protect groundwater resources for the residents of Nye County in Amargosa and Pahrump Valleys. This groundwater monitoring program, referred to as the Nye County Early Warning Drilling Program (NCEWDP), involves drilling a series of wells down-gradient from Yucca Mountain for long term groundwater monitoring and also to provide much needed geologic and hydrologic information in this area. A comprehensive database of aquifer parameters in the alluvial, volcanic, and carbonate aquifers down-gradient hydrogeologically of Yucca Mountain is …

Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Scott Whittenburg

Chemistry Faculty Publications

Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnO films. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to R⁻¹ (inverse of the distance R from a central Co²⁺ ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results

Holographic Analysis Of Diffraction Structure Factors, S. Marchesini, N. Mannella, C. S. Fadley, M. A. Van Hove, J. J. Bucher, D. K. Shuh, L. Fabris, M. J. Press, M. W. West, Wayne C. Stolte, Z. Hussain

Chemistry and Biochemistry Faculty Research

We combine the theory of inside-source/inside-detector x-ray fluorescence holography and Kossel lines/x ray standing waves in kinematic approximation to directly obtain the phases of the diffraction structure factors. The influence of Kossel lines and standing waves on holography is also discussed. We obtain partial phase determination from experimental data obtaining the sign of the real part of the structure factor for several reciprocal lattice vectors of a vanadium crystal.

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

Chemistry Faculty Research & Creative Works

Short-range antiferromagnetic correlations have been studied in the layered compounds (PPh₄) [Fe^IIFe^III(ox)₃] and (NBu₄) [Fe^IIFe^III(ox)₃] by neutron polarization analysis and Mössbauer spectroscopy. Polarized neutron diffraction profiles obtained between 2 and 50 K on (d₂₀-Pph₄) [Fe^IIFe^III(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 …

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

Chemistry Faculty Research & Creative Works

Nanopowdered alloys of Pd_100-xFe_x, 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 …

Crown Ether-Modified Clays And Their Polystyrene Nanocomposites, Hongyang Jao, Jin Zhu, Alexander B. Morgan, Charles A. Wilkie

Chemistry Faculty Research and Publications

Crown ether-modified clays were obtained by the combination of sodium and potassium clays with crown ethers and cryptands. Polystyrene nanocomposites were prepared by bulk polymerization in the presence of these clays. The structures of nanocomposites were characterized by X-ray diffraction and transmission electron microscopy. Their thermal stability and flame retardancy were measured by thermogravimetric analysis and cone calorimetry, respectively. Nanocomposites can be formed only from the potassium clays; apparently the sodium clays are not sufficiently organophilic to enable nanocomposite formation. The onset temperature of the degradation is higher for the nanocomposites compared to virgin polystyrene, and the peak heat release …

Synthesis And Characterization Of Hydroxyapatite-Collagen Biocomposite Materials, Vuk Uskoković, Nenad Ignjatović, Nadejda Petranović

Pharmacy Faculty Articles and Research

Hydroxyapatite-collagen composite is a prosperous biomaterial in reconstructive surgery for the reparation of defects within human hard tissue. Within this research, three-dimensional blocks of HAp/collagen composite biomaterial were synthesized by homogenizing the HAp/collagen mixture by cold and hot (T=60oC) pressing (P=49 MPa). The changes in the system were followed by using thermal analysis (DSC & TGA), FT-IR spectroscopy and scanning electron microscopy (SEM). The identification and kinetic analysis of appearing phase transition were done. FT-IR spectrum of the biocomposite shows that neither cold nor hot pressing had significant influence on the individual components of the composite. SEM of the fracture …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems: Quarterly Progress Report (June 01 – August 31, 2002), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate target materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including Alloy HT-9, Alloy EP 823 and Type 422 stainless steel. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these materials are being evaluated in environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. Further, the localized corrosion behavior of these alloys …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Final Report -Phase I 09/01/2001-08/30/2002, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the AAA proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Bulk And Interfacial Properties Of Quadrupolar Fluids, V.B. Warshavsky, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We extend Teixeira and Telo da Gama’s density-functional approach [J. Phys.: Condens. Matter 3, 111 (1991)] to study the vapor–liquid phase equilibria and planar interfacial properties of quadrupolar fluids. The density profile, surface ordering, surface polarization, and surface tension of quadrupolar fluids are evaluated. Particular attention is given to the temperature and quadrupole-strength dependence. It is found that the interfacial molecular ordering can arise entirely due to the quadrupole–quadrupole interaction. It is also found that the bulk-phase properties of the quadrupolar fluids satisfy the law of correspondence states. The reduced surface potential and surface tension can be well correlated by …

Development Of A Systems Engineering Model Of The Chemical Separations Process: Quarterly Progress Report 5/16/02- 8/15/02, Yitung Chen, Randy Clarksean, Darrell Pepper

Separations Campaign (TRP)

Two activities are proposed in this Phase I task: the development of systems engineering model and the refinement of the Argonne code AMUSE (Argonne Model for Universal Solvent Extraction). The detailed systems engineering model is the start of an integrated approach to the analysis of the materials separations associated with the AAA Program. A second portion of the project is to streamline and improve an integral part of the overall systems model, which is the software package AMUSE. AMUSE analyzes the UREX process and other related solvent extraction processes and defines many of the process streams that are integral to …

Corrosion Of Steel By Lead Bismuth Eutectic: Quarterly Report For May-June-July 2002, John Farley

Transmutation Sciences Materials (TRP)

The goal of this project is to understand the basic science of corrosion in the steel/LBE system.

We are taking more data, typically using the newly installed X-ray Photoelectron Spectrometry (XPS) apparatus, and analyzing our existing data. Undergraduate students Denise Parsons and Julia Manzerova have helped a great deal in the analysis of the data. We can obtain the elemental composition as a function of position within the sample. This gives clues to the migration of materials, the composition of the protective oxide layer, and the basic science of the corrosion process. We found dramatic differences between the exposed and …

The 1.20 Å Resolution Crystal Structure Of The Aminopeptidase From Aeromonas Proteolytica Complexed With Tris: A Tale Of Buffer Inhibition, William Desmarais, David L. Bienvenue, Krzysztof P. Bzymek, Richard C. Holz, Gregory A. Petsko, Dagmar Ringe

Chemistry Faculty Research and Publications

The aminopeptidase from Aeromonas proteolytica (AAP) is a bridged bimetallic enzyme that removes the N-terminal amino acid from a peptide chain. To fully understand the metal roles in the reaction pathway of AAP we have solved the 1.20 Å resolution crystal structure of native AAP (PDB ID = 1LOK). The high-quality electron density maps showed a single Tris molecule chelated to the active site Zn²⁺, alternate side chain conformations for some side chains, a sodium ion that mediates a crystal contact, a surface thiocyanate ion, and several potential hydrogen atoms. In addition, the high precision of the atomic …

Determination Of Barbituric Acid, Utilizing A Rapid And Simple Colorimetric Assay, Ronald Bartzatt

Chemistry Faculty Publications

Barbituric acid is widely used in the manufacturing of plastics, textiles, polymers, and pharmaceuticals. Three assay methods are presented, which can utilize either aqueous or solid samples. The detection of as little as 10 μg of barbituric acid can be accomplished, either as an aqueous or solid sample, when using micro reaction tubes. The red–violet endpoint is easily discerned and results upon the formation of a violuric acid derivative. A Spot Test protocol is described which allows for a positive/negative indication of barbituric acid presence. The Spot Test is sensitive to as little as 18.75 μg/ml of barbituric acid. The …

Characterization And Interactions Of Mercury, Dissolved Organic Matter And Organic Sulfur In Surface Waters Of The Florida Everglades, Maria Asuncion Calero Sheils

FIU Electronic Theses and Dissertations

Two sampling stations in the Florida Everglades were selected based on the results from US Environmental Protection Agency and Florida International University Mercury Project. In both sites, most of the methylmercury is associated with the truly dissolved organic matter fraction (

A Model For Mechanochemical Transformations: Applications To Molecular Hardness, Instabilities, And Shock Initiation Of Reaction, Tadeusz Luty, Piotr Ordon, Craig J. Eckhardt

Craig J. Eckhardt Publications

A basic theoretical structure for mechanochemical transformations based on prior models for solid-state reactions and HOMO–LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) gap closing produces the concept of distortion-induced molecular electronic degeneracy (DIMED) of the highest occupied and lowest unoccupied molecular orbitals of an energetic molecule. Both intermolecular and intramolecular charge transfer are involved. The resulting distortion-induced local instability, a mechanochemical effect, leads to chemical transformations and can be analyzed by renormalization of the molecular hardness through the molecular deformation energy. Linear combinations of normal modes are shown to be useful for description of the mechanically induced reaction path. …

Heterogeneous Nucleation On Mesoscopic Wettable Particles: A Hybrid Thermodynamic/Density-Functional Theory, T.V. Bykov, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A hybrid thermodynamic and density-functional theory for heterogeneous nucleation on mesoscopic wettable particles is developed. The nonlocal density-functional theory (DFT) is on basis of the weighted-density approximation (WDA) of Tarazona. The model system consists of a Lennard-Jones (LJ) fluid and a 9–3 LJ wall for the solid particle. Effects of the droplet curvature and compressibility are accounted for in the theory. A by-product of this work is the calculation of the Tolman length using the WDA-DFT (Appendix A). Important characteristics of the heterogeneous nucleation, including the chemical potential of the liquid condensate, the free energy of droplet formation, and the …

A New Accelerator Mass Spectrometry System For 14c-Quantification Of Biochemical Samples, Ted J. Ognibene, Graham Bench, Tom A. Brown, Graham F. Peaslee, John S. Vogel

Faculty Publications

A compact accelerator mass spectrometry (AMS) system that meets our requirements for View the MathML source-quantification of biochemical samples is described. The spectrometer occupies approximately 5 m2 of floor space and can measure >300 samples per day with 3% precision. A long diffuse gas cell is used to destroy interfering molecules and to charge exchange injected negative ions. System sensitivity is <1 amol View the MathML source/mg carbon on milligram-sized samples with a dynamic range that extends over 4 orders magnitude. All components, with the exception of the ion source, are commercially available and the system operates reliably with low maintenance.

Non-Dipolar Electron Angular Distributions From Fixed-In-Space Molecules, Renaud Guillemin, Oliver Hemmers, Dennis W. Lindle, E. Shigemasa, K. Le Guen, D. Ceolin, C. Miron, N. Leclercq, P. Morin, Marc Simon, P. W. Langhoff

Environmental Studies Faculty Publications

The first indication of nondipole effects in the azimuthal dependence of photoelectron angular distributions emitted from fixed-in-space molecules is demonstrated in N₂. Comparison of the results with angular distributions observed for randomly oriented molecules and theoretical derivations for the nondipole correction first order in photon momentum suggests that higher orders will be needed to describe distributions measured in the molecular frame.

Preprogramming Of Porphyrin-Nucleic Acid Assemblies Via Variation Of The Alkyl/Aryl Substituents Of Phosphonium Tetratolylporphyrins, Pavel Kubat, Kamil Lang, Vladimir Kral, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

Cationic alkyl/arylphosphonium meso-tetratolylporphyrins aggregate in an aqueous solution to form H-aggregates, J-aggregates, and long-range assemblies. The ratio between the monomer and various types of aggregates can be controlled by the substitution in the phosphonium units and by the ionic strength. A trimethylphosphonium derivative is predominantly monomeric, dimethylphenylphosphonium forms monomers as well as low-molecular-weight H- and J-aggregates, triphenylphosphonium forms mainly H- and J-aggregates, and tri(n-butyl)phosphonium forms mainly long-range assemblies. Porphyrin monomers associate with calf thymus DNA (binding constant Kb approximate to 10(7) M-1) and oligonucleotides (K-b approximate to 10(5-)10(6) M-1). The large size of the meso-substituents prevents the intercalation between base …

Synthetic Studies Directed Toward The Phorboxazoles: Preparation Of The C3–C15 Bisoxane Segment And Two Stereoisomers, Patrick Bernard Greer, William Donaldson

Chemistry Faculty Research and Publications

A synthetic approach to the C3–C15 segment of the cytotoxic marine metabolite phorboxazoles is described. This segment consists of a methylene linked bisoxane structure. The first pyran ring was constructed by a Lewis acid catalyzed diene–aldehyde cyclocondensation. The β-C-glucoside substitution pattern of this ring was established by a stereoselective allylation. Ozonolysis of vinyl group and enantioselective allylation of the racemic aldehyde generated two separable homoallylic alcohols (−)-22 and (+)-23. The Mosher's esters of each alcohol were determined to be >90% de. Reaction of (−)-22 with acryloyl chloride, followed by ring closing metathesis gave the …

In-Situ X-Ray-Absorption Spectroscopy Study Of Hydrogen Absorption By Nickel-Magnesium Thin Films, B. Farangis, Ponnusamy Nachimuthu, T. J. Richardson, J. L. Slack, Rupert C. Perera, Eric M. Gullikson, Dennis W. Lindle, M. Rubin

Chemistry and Biochemistry Faculty Research

Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in-situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Co-deposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied …

Electron Hopping Conductivity And Vapor Sensing Properties Of Flexible Network Polymer Films Of Metal Nanoparticles, Francis P. Zamborini, Michael C. Leopold, Jocelyn F. Hicks, Pawel J. Kulesza, Marcin A. Malik, Royce W. Murray

Chemistry Faculty Publications

Films of monolayer protected Au clusters (MPCs) with mixed alkanethiolate and ω-carboxylate alkanethiolate monolayers, linked together in a network polymer by carboxylate-Cu2+-carboxylate bridges, exhibit electronic conductivities (σEL) that vary with both the numbers of methylene segments in the ligands and the bathing medium (N2, liquid or vapor). A chainlength-dependent swelling/contraction of the film's internal structure is shown to account for changes in σEL. The linker chains appear to have sufficient flexibility to collapse and fold with varied degrees of film swelling or dryness. Conductivity is most influenced (exponentially dependent) by the chainlength of the nonlinker (alkanethiolate) ligands, a result consistent …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems: Annual Progress Report (May 2001 – May 2002), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate target materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including Alloy HT-9, Alloy EP 823 and Type 422 stainless steel. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these materials are being evaluated in environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. Further, the localized corrosion behavior of these alloys …