Chemistry Commons^™

Preparation And Characterization Of Biomimetic Hydroxyapatite-Resorbable Polymer Composites For Hard Tissue Repair, Kristopher R. Hiebner

Department of Chemistry: Dissertations, Theses, and Student Research

Autografts are the orthopedic “gold standard” for repairing bone voids. Autografts are osteoconductive and do not elicit an immune response, but they are in short supply and require a second surgery to harvest the bone graft. Allografts are currently the most common materials used for the repair of segmental defects in hard tissue. Unlike autografts, allografts can cause an undesirable immune response and the possibility of disease transmission is a major concern. As an alternative to the above approaches, recent research efforts have focused on the use of composite materials made from hydroxyapatite (HA) and bioresorbable polymers, such as poly-L-lactide …

A Mild One-Pot Conversion Of Alkenes Into Amines Through Tandem Ozonolysis And Reductive Amination, Shivakumar Kyasa, Thomas J. Fisher, Patrick Dussault

Patrick Dussault Publications

The selective reduction of hydroperoxyacetals to aldehydes by sodium triacetoxyborohydride provides the basis for a mild one-pot synthesis of amines from alkenes.

Includes Supplementary Materials.

Analytic Energy Gradients In Combined Second Order Møller-Plesset Perturbation Theory And Conductorlike Polarizable Continuum Model Calculation, Dejun Si, Hui Li

Hui Li Publications

The analytic energy gradients in combined second order Møller-Plesset perturbation theory and conductor-like polarizable continuum model calculations are derived and implemented for spin-restricted closed shell (RMP2), Z-averaged spin-restricted open shell (ZAPT2), and spin-unrestricted open shell (UMP2) cases. Using these methods, the geometries of the S0 ground state and the T₁ state of three nucleobase pairs (guanine-cytosine, adenine-thymine, and adenine-uracil) in the gas phase and aqueous solution phase are optimized. It is found that in both the gas phase and the aqueous solution phase the hydrogen bonds in the T₁ state pairs are weakened by ∼1 kcal/mol as compared …

Combinatorial Catalysis Assisted By A Visible Enzymatic Beacon In Real Time: New Synthetically Versatile (Pseudo)Halometalation/Carbocyclizations, Jacob A. Friest, Sylvain Broussy, Woo Jin Chung, David B. Berkowitz

David Berkowitz Publications

Combinatorial approaches to catalysis have made an impact in targeted transformation development, including Ag-mediated carbene insertion,^[1] Sc-pybox-based asymmetric cyclopropanation,^[2] and Rh/Ir-based asymmetric hydrogenation.^[3] Useful design elements have emerged from these studies, e.g. the value of ligand self assembly,^[4] or of the inclusion of peptide-like structural elements^[5],[6],[7] in building ligand arrays. Efficient screening methods are of paramount importance for such efforts. Methods based on fluorescence,^[8] REMPI^,[9] MS,^[10] NMR,^[11] and IR thermography^[12] have appeared. A chromophore may be installed into the substrate^[13] or product^[14] of the reaction under study. Alternatively, …

High Yield Synthesis Of Positron Emission Tomography Ligands For Metabotropic Glutamate Receptor Imaging, Saraanne E. Hitchcock

Department of Chemistry: Dissertations, Theses, and Student Research

Positron Emission Tomography (PET) is a powerful and non-invasive imaging technique used for human and animal organ imaging. Currently, the market for PET is project to reach $5.4 billion per year by 2015.5 This research focuses on the direct incorporation of [18F]-fluoride into PET ligands. The widespread use of PET imaging is currently frustrated, in part, by the lack of efficient fluorination chemistry.

Glutamate, one of the 20 most abundant naturally occurring amino acids, serves as a neurotransmitter in the central nervous system. Glutamate functions in this capacity by binding to ionotropic and metabotropic receptors. Metabotropic receptors are Gcoupled proteins …

Comparative Analysis Of Peak-Detection Techniques For Comprehensive Two-Dimensional Chromatography, Indu Latha, Stephen E. Reichenbach, Qingping Tao

School of Computing: Faculty Publications

Comprehensive two-dimensional gas chromatography (GC×GC) is a powerful technology for separating complex samples. The typical goal of GC×GC peak detection is to aggregate data points of analyte peaks based on their retention times and intensities. Two techniques commonly used for two-dimensional peak detection are the two-step algorithm and the watershed algorithm. A recent study [4] compared the performance of the two-step and watershed algorithms for GC×GC data with retention-time shifts in the second-column separations.In that analysis,the peak retention-time shifts were corrected while applying the two-step algorithm but the watershed algorithm was applied without shift correction. The results indicated that the …

Assessing Secondary And College Students’ Implicit Assumptions About The Particulate Nature Of Matter: Development And Validation Of The Structure And Motion Of Matter Survey, Marilyne Stains, Marta Escriu-Sune, Myrna Lisseth Molina Alvarez De Santizo, Hannah Sevian

Department of Chemistry: Faculty Publications

Development of learning progressions has been at the forefront of science education for several years. While understanding students’ conceptual development toward “big ideas” in science is extremely valuable for researchers, science teachers can also benefit from assessment tools that diagnose their students’ trajectories along the learning progressions. In this paper, we describe the development and validation of a teacher-friendly survey, the Structure and Motion of Matter (SAMM) survey, designed to measure students’ trajectories along aspects of a research-based learning progression on the particulate nature of matter. Specifically, the survey assesses students’ implicit assumptions about four concepts: the structure of solute …

Phytosterol Stearate Esters Elicit Similar Responses On Plasma Lipids And Cholesterol Absorption But Different Responses On Fecal Neutral Sterol Excretion And Hepatic Free Cholesterol In Male Syrian Hamsters, Mark M. Ash, Jiliang Hang, Patrick Dussault, Timothy P. Carr

Patrick Dussault Publications

The dietary impact of specific phytosterols incorporated into phytosterol fatty acid esters has not been elucidated. Therefore, we tested the hypothesis that phytosterol esters containing different sterol moieties (sitosterol, sitostanol, or stigmasterol) but the same fatty acid moiety (stearic acid) produce different effects on cholesterol metabolism. Male Syrian hamsters were fed sitosterol, sitostanol, and stigmasterol stearate esters (25 g/kg diet) in an atherogenic diet containing cholesterol (1.2 g/kg) and coconut oil (80 g/kg). The phytosterol stearates produced no decrease in cholesterol absorption or plasma non–high-density lipoprotein cholesterol despite a reduction in liver free cholesterol in hamsters fed both sitosterol and …

Unprecedented Directing Group Ability Of Cyclophanes In Arene Fluorinations With Diaryliodonium Salts, Joseph W. Graskemper, Bijia Wang, Linlin Qin, Kiel D. Neumann, Stephen G. Dimagno

Stephen DiMagno Papers

For the first time it is shown that exceptionally electron-rich arene rings can be fluorinated exclusively during the reductive elimination reactions of diaryliodonium fluorides. The 5-methoxy[2.2]paracyclophan-4-yl directing group simultaneously reduces unproductive aryne chemistry and eliminates ligand exchange reactions by a combination of steric and electronic effects. Use of the cyclophane directing group permits an unprecedented degree of control in fluorination reactions of diaryliodonium salts.

Includes Supporting Information (50 pp.)

An Assessment Of Stable Hydrogen-Isotope Analysis Methods To Assign Geographic Origin To Migratory Red-Tailed Hawks (Buteo Jamaicensis), Carla Marie Ahlschwede

Department of Environmental Studies: Undergraduate Student Theses

Stable-hydrogen isotopes are becoming an increasingly popular method of studying migratory birds, though sample preparation methods may affect results.  In this study I examined feathers from red-tailed hawks (Buteo jamaicensis) to determine the relationship between measure of δD due to inter-feather variation or drying methods, assessed the accuracy of results by using two birds of known-origin and estimated possible natal origins of migratory red-tailed hawks.  Two feathers per individual were taken from 81 wild hawks caught at Hitchcock Nature Center near Crescent IA and from 2 rescued red-tailed hawks, Raptor Recovery Nebraska near Eagle, NE. 119 of the …

Characterization Of Novel Macrocyclic Polyether Modified Pseudostationary Phases For Use In Micellar Electrokinetic Chromatography And Development Of A Chemiluminescence Presumptive Assay For Peroxide-Based Explosives, Raychelle Burks

Department of Chemistry: Dissertations, Theses, and Student Research

This work describes the first use and characterization of macrocyclic polyether (MP) modified sodium dodecyl sulfate (SDS) pseudostationary phases (PSPs) for use in micellar electrokinetic chromatography (MEKC), as well as the development of a presumptive chemiluminescence assay for peroxide-based explosives. In MEKC separation and detection, resolution is optimized by using various PSPs or by altering the properties of a single PSP using different class I or II modifiers. Class I modifiers target the PSP through direct interaction with micelles, while class II organic modifiers operate by altering the BGE. The of MPs 18-crown-6, 15-crown-5, and 12-crown-4 were used to modify …

Purification Of Lysine Decarboxylase: A Model System For Plp Enzyme Inhibitor Development And Study, Leah C. Zohner

Department of Chemistry: Dissertations, Theses, and Student Research

Pyridoxal phosphate (PLP) dependent enzymes have the ability to manipulate amino acid substrates, serving variously as (i) racemases, transaminases, and beta- or gamma eliminases (all involving Cα-H bond cleavage); (ii) decarboxylases (Cα-CO2- bond cleavage), or (iii) retroaldolases (Cα-Cβ bond cleavage). Dunathan posited that stereoelectronics govern the key C-X bond cleavage step across the class of PLP enzymes; namely by aligning the scissile bond of the substrate with the extended pi system of the substrate-PLP imine that bond is weakened. A mechanistic understanding of electron flow in this enzymatic class has motivated many groups, including the Berkowitz group, to develop mechanism-based …

Resorbable Polymer-Hydroxyapatite Composites For Bone Trauma Treatment: Synthesis And Properties, Troy E. Wiegand

Department of Chemistry: Dissertations, Theses, and Student Research

Contemporary therapies for hard tissue replacement involve allographs, where the donor and recipient are of the same species, or the use of xenogenic transplants.  Intraspecies materials are often in short supply and interspecies materials are subject to immunological barriers such as disease and tissue rejection.  Synthetic composites are unencumbered by these limitations.  Poly lactic acid (PLLA) and its copolymers have been used in medicine due to their ability to be resorbed by the body without adverse effects.  PLLA’s are currently most commonly used in resorbable sutures and gauzes, but there is increasing interest in using them in conjunction with hydroxyapatite …

Optimization And Implementation Of Entrapment: A Novel Immobilization Technique For High-Performance Affinity Chromatography, Abby J. Jackson

Department of Chemistry: Dissertations, Theses, and Student Research

The proper use of high performance affinity chromatography (HPAC) in the study of biologically-related systems requires that careful attention be paid to the nature in which the affinity ligand is incorporated into the stationary phase.  Ideally, the behavior of the immobilized ligand should mimic the behavior of the ligand in its natural environment.  Retaining the soluble form of the ligand, by avoiding covalent immobilization completely, is one effective way to retain the activity of the ligand.  Previously, noncovalent immobilization techniques that do not modify the ligand of interest have included physical entrapment onto low performance supports.

This dissertation introduces an …

N5-Phosphonoacetyl-L-Ornithine (Palo): A Convenient Synthesis And Investigation Of Influence On Regulation Of Amino Acid Biosynthetic Genes In Saccharomyces Cerevisiae, Brad Johnson, Rachel Steadman, Krista D. Patefield, Jeffrey J. Bunker, Audrey L. Atkin, Patrick Dussault

Patrick Dussault Publications

A scalable four-step synthesis of the ornithine transcarbamylase inhibitor N⁵-phosphonoacetyl-L-ornithine (PALO) is achieved through boroxazolidinone protection of ornithine. Investigations in the model organism Saccharomyces cerevisiae found that, in contrast to a previous report, PALO did not influence growth rate or expression of genes involved in arginine metabolism.

Transformation Of Fusarium Verticillioides With A Polyketide Gene Cluster Isolated From A Fungal Endophyte Activates The Biosynthesis Of Fusaric Acid, Yunxuan Xie, Wei Zhang, Yaoyao Li, Mingzi Wang, Ronald Cerny, Yue Shen, Liangcheng Du

Liangcheng Du Publications

A large number of bioactive natural products have been isolated from plant endophytic fungi. However, molecular mechanisms for the biosynthesis of these metabolites have lagged behind because genetic and biochemical studies are difficult to perform within many of the endophytes. In this work, we describe our attempt to express a putative mycoepoxydiene (MED) biosynthetic gene cluster in Fusarium verticillioides, which has a well-developed genetic system for the study fungal polyketide biosynthesis. MED was isolated from Phomopsis sp. A123, a fungal endophyte of the mangrove plant, Kandelia candel. It has several unusual structural features and interesting biological activities. Integration of …

Synthesis And Isolation Of {110}-Faceted Gold Bipyramids And Rhombic Dodecahedra, Michelle L. Personick, Mark R. Langille, Jian Zhang, Nadine Harris, George C. Schatz, Chad A. Mirkin

Department of Chemistry: Faculty Publications

Two {110}-faceted gold nanostructures—rhombic dodecahedra and obtuse triangular bipyramids—have been synthesized via a Ag-assisted, seed-mediated growth method. The combination of a Cl−-containing surfactant with a low concentration of Ag+ plays a role in the stabilization of the {110} facets. To the best of our knowledge, this is the first reported synthesis of a {110}-faceted bipyramid structure.

Reversible Collapse Of The Langmuir Films Of A Series Of Triphenylsilyl Ether-Terminated Amphiphiles, Christine A. Devries, James J. Haycraft, Qiang Han, Farhana Noor-E-Ain, Joseph Raible, Patrick Dussault, Craig J. Eckhardt

Patrick Dussault Publications

The Langmuir films of a series of triphenylsilyl ether (TPSE)-terminated amphiphiles were investigated in order to explore the bulge amphiphile model developed by Haycraft et al. [Thin Solid Films, 515 (2007) 2990]. The TPSE series was examined using surface pressure– surface area isotherms over a range of temperatures (287–298 K) with simultaneous acquisition of Brewster angle microscopy images. The Langmuir films of the TPSE series exhibit the reversible collapse process characteristic of bulge amphiphiles, including an observation consistent with the reversed cybotactic cluster model and increased entropy upon collapse. No solid-like monolayer phases were found over the temperature …

Evaluation Of The Sensitivity Of Inventory And Monitoring National Parks To Nutrient Enrichment Effects From Atmospheric Nitrogen Deposition Northern Great Plains Network (Ngpn), T. J. Sullivan, T. C. Mcdonnell, G. T. Mcpherson, S. D. Mackey, D. Moore

United States National Park Service: Publications

Northern Great Plains Network (NGPN)

National maps of atmospheric N emissions and deposition are provided in Maps A and B as context for subsequent network data presentations. Map A shows county level emissions of total N for the year 2002. Map B shows total N deposition, again for the year 2002.

There are three parks in the Northern Great Plains Network that are larger than 100 square miles: Badlands (BADL), Missouri (MNRR), and Theodore Roosevelt (THRO). In addition, there are 10 other smaller parks.

Total annual N emissions, by county, are shown in Map C for lands in and surrounding …

Ligand Fluorination To Optimize Preferential Oxidation Of Carbon Monoxide By Water-Soluble Rhodium Porphyrins, Justin C. Biffinger, Shriharsha Uppaluri, Haoran Sun, Stephen G. Dimagno

Stephen DiMagno Papers

Catalytic, low temperature preferential oxidation (PROX) of carbon monoxide by aqueous [5,10,15,20-tetrakis- (4-sulfonatophenyl)-2,3,7,8,12,13,17,18-octafluoroporphyrinato]- rhodium(III) tetrasodium salt, (1[Rh(III)]) and [5,10,15, 20-tetrakis(3-sulfonato-2,6-difluorophenyl)-2,3,7,8,12,13, 17,18-octafluoroporphyrinato]rhodium(III) tetrasodium salt, (2[Rh(III)]) is reported. The PROX reaction occurs at ambient temperature in buffered (4 ≤ pH ≤ 13) aqueous solutions. Fluorination on the porphyrin periphery is shown to increase the CO PROX reaction rate, shift the metal centered redox potentials, and acidify ligated water molecules. Most importantly, β-fluorination increases the acidity of the rhodium hydride complex (pK_a = 2.2 ± 0.2 for 2[Rh-D]); the dramatically increased acidity of the Rh(III) hydride complex precludes proton reduction …

A P38Α-Selective Chemosensor For Use In Unfractionated Cell Lysates, Cliff I. Stains, Elvedin Luković, Barbara Imperiali

Cliff Stains Publications

Recent efforts have identified the p38α Ser/Thr kinase as a potential target for the treatment of inflammatory diseases as well as non-small cell lung carcinoma. Despite the significance of p38α, no direct activity probe compatible with cell lysate analysis exists. Instead, proxies for kinase activation, such as phosphospecific antibodies, which do not distinguish between p38 isoforms, are often used. Our laboratory has recently developed a sulfonamido-oxine (Sox) fluorophore that undergoes a significant increase in fluorescence in response to phosphorylation at a proximal residue, allowing for real-time activity measurements. Herein we report the rational design of a p38α-selective chemosensor using this …

Bottom-Up Synthesis Of Gold Octahedra With Tailorable Hollow Features, Mark R. Langille, Michelle L. Personick, Jian Zhang, Chad A. Mirkin

Department of Chemistry: Faculty Publications

Gold octahedra with hollow features have been synthesized in high yield via the controlled overgrowth of preformed concave cube seeds. This Ag+-assisted, seed-mediated synthesis allows for the average edge length of the octahedra and the size of the hollow features to be independently controlled. We propose that a high concentration of Ag⁺ stabilizes the {111} facets of the octahedra through underpotential deposition while the rate of Au⁺ reduction controls the dimensions of the hollow features. This synthesis represents a highly controllable bottom-up approach for the preparation of hollow gold nanostructures.

Structure Function Analysis Of An Adp-Ribosyltransferase Type Iii Effector And Its Rna-Binding Target In Plant Immunity, Byeong-Ryool Jeong, Yan Lin, Anna Joe, Ming Guo, Christin Korneli, Huirong Yang, Ping Wang, Min Yu, Ronald Cerny, Dorothee Staiger, James R. Alfano, Yanhui Xu

Ronald Cerny Publications

Background: HopU1 ADP-ribosylates GRP7, suppressing plant immunity.

Results: The HopU1 structure has two novel loops required for GRP7 recognition, and HopU1 ribosylates GRP7 at an arginine in position 49 disrupting its function.

Conclusion: HopU1 targets a conserved arginine in GRP7, disabling its ability to bind immunity-related RNA.

Significance: The mechanistic details of how HopU1 recognizes its substrate reveal how HopU1 contributes to pathogenesis.

A Turn-On Split-Luciferase Sensor For The Direct Detection Of Poly(Adp-Ribose) As A Marker For Dna Repair And Cell Death, Jennifer L. Furman, Pui-Wing Mok, Shengyi Shen, Cliff I. Stains, Indraneel Ghosh

Cliff Stains Publications

Designed sensors comprising split-firefly luciferase conjugated to tandem poly(ADP-ribose) binding domains allow for the direct solution phase detection of picogram quantities of PAR and for monitoring temporal changes in poly(ADP-ribosyl)ation events in mammalian cells.

Includes Supplementary Material.

Searching The Protein Structure Database For Ligand-Binding Site Similarities Using Cpass V.2, Robert Powers, Jennifer C. Copeland, Jaime L. Stark, Adam Caprez, Ashu Guru, David R. Swanson

Robert Powers Publications

Background: A recent analysis of protein sequences deposited in the NCBI RefSeq database indicates that ~8.5 million protein sequences are encoded in prokaryotic and eukaryotic genomes, where ~30% are explicitly annotated as “hypothetical” or “uncharacterized” protein. Our Comparison of Protein Active-Site Structures (CPASS v.2) database and software compares the sequence and structural characteristics of experimentally determined ligand binding sites to infer a functional relationship in the absence of global sequence or structure similarity. CPASS is an important component of our Functional Annotation Screening Technology by NMR (FAST-NMR) protocol and has been successfully applied to aid the annotation of a number …

I, An Improved Procedure For Alkene Ozonolysis. Ii, Exploring A New Structural Paradigm For Peroxide Antimalarials., Charles Edward Schiaffo

Department of Chemistry: Dissertations, Theses, and Student Research

The use of ozone for the transformation of alkenes to carbonyls has been well established. The reaction of ozone with alkenes in this fashion generates either a 1,2,4-trioxolane (ozonide) or a hydroperoxyacetal, either of which must undergo a separate reduction step to provide the desired carbonyl compound. There is considerable interest in being able to perform a reductive ozonolysis to directly provide the carbonyl. Previous reports from the Dussault lab have shown that amine N-oxides are able to perform a reductive ozonolysis. In the course of efforts to expand this reaction to other oxyanions it was realized that water was …

Fabrication And Catalytic Property Of Cerium Oxide Nanomaterials, Keren Jiang

Department of Chemistry: Dissertations, Theses, and Student Research

Cerium oxide, or ceria (CeO_x: x = 1.5 to 2), has been widely used as a heterogeneous catalyst. Ceria has several properties make it high catalytic active: the fluctuating valence of cerium, the high oxygen storage capacity and high oxygen mobility in the nonstoichiometric ceria. With the high abundance of cerium on earth crust, ceria is a highly effective alternative of the noble metal catalysts. Research has been focused on designing nanostructured ceria and ceria related materials in recent years. The catalytic activity of ceria can be enhanced by the nanoscale effect which can be applied for various …

Ultrafast Rempi In Benzene And The Monohalobenzenes Without The Focal Volume Effect, Timothy D. Scarborough, James Strohaber, David B. Foote, Collin J. Mcacy, Cornelis J. Uiterwaal

C.J.G.J. Uiterwaal Publications

We report on the photoionization and photofragmentation of benzene (C₆H₆) and of the monohalobenzenes C₆H₅–X (X = F, Cl, Br, I) under intense-field, single-molecule conditions. We focus 50-fs, 804-nm pulses from a Ti:sapphire laser source, and record ion mass spectra as a function of intensity in the range ~10¹³ W/cm² to ~10¹⁵ W/cm². We count ions that were created in the central, most intense part of the focal area; ions from other regions are rejected. For all targets, stable parent ions (C₆H₅X+) are …

Transition From One-Dimensional Water To Ferroelectric Ice Within A Supramolecular Architecture, Hai-Xia Zhao, Xiang-Jian Kong, Hui Li, Yi-Chang Jin, La-Sheng Long, Xiao Cheng Zeng, Rong-Bin Huang, Lan-Sun Zheng

Xiao Cheng Zeng Publications

Ferroelectric materials are characterized by spontaneous electric polarization that can be reversed by inverting an external electric field. Owing to their unique properties, ferroelectric materials have found broad applications in microelectronics, computers, and transducers. Water molecules are dipolar and thus ferroelectric alignment of water molecules is conceivable when water freezes into special forms of ice. Although the ferroelectric ice XI has been proposed to exist on Uranus, Neptune, or Pluto, evidence of a fully protonordered ferroelectric ice is still elusive. To date, existence of ferroelectric ice with partial ferroelectric alignment has been demonstrated only in thin films of ice grown …

Elastic Properties Of Poly(Vinyldene Fluoride) (Pvdf) Crystals: A Density Functional Theory Study, Yong Pei, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We computed structural and elastic properties of totally nine phases of poly(vinyldene fluoride) (PVDF) crystals using the density-functional theory (DFT) method with and without inclusion of the dispersion corrections. In addition to the four known crystalline forms, mechanic properties of five theoretically predicted crystalline forms of PVDF are also investigated. The all-trans form I_p exhibits the largest cohesive energy, bulk, and Young’s modulus among the nine crystalline forms. The DFT calculations suggest that the δ crystalline forms (III_au, III_pu, III_pd, and III_ad) possess poor chain rigidity among the nine PVDF …