Chemistry Commons^™

Transverse Susceptibility Study Of The Effect Of Varying Dipolar Interactions On Anisotropy Peaks In A Three-Dimensional Assembly Of Soft Ferrite Nanoparticles, Pankaj Poddar, Marienette B. Morales, Natalie A. Frey, Shannon A. Morrison, Everett E. Carpenter, Hariharan Srikanth

Chemistry Publications

Collective magnetization dynamics in nanoparticle assemblies is of current interest as it forms the basis of high density storage media. It is important to understand how interparticle interactions in a three-dimensional (3D) arrangement of superparamagnetic nanoparticles would affect the overall effective magnetic anisotropy of the system. We have studied the influence of varying strengths of dipolar interaction on the static and dynamic magnetic properties of surfactant-coated monodispersed manganese zinc ferrite nanoparticles using reversible transverse susceptibility. We track the evolution of the anisotropy peaks with varying magnetic field, temperature, and interaction strength. The blocking temperature shows an increase from 28 to …

[Link Foundation Fellowship Final Report], Alex Martinson

Link Foundation Energy Fellowship Reports

Efficient conversion of solar radiation into electricity is a compelling scientific and economic goal. As the world’s energy demands continue to grow it has become clear that burning fossil fuels for energy is unsustainable and detrimental to global health and geopolitics. More than any other renewable resource, solar energy conversion has the potential to meet human energy needs with a total yearly insolation of 120,000 TW/year.1 While organic photovoltaics (PVs) are currently not as efficient as their inorganic counterparts, their efficiencies have been steadily increasing over the past decade. The most significant advances are attributable to greater control over the …

Online Chemistry Tutoring System, Michael A. Janusa

Faculty Presentations

No abstract provided.

A Polarizable Force-Field Model For Quantum-Mechanical-Molecular-Mechanical Hamiltonian Using Expansion Of Point Charges Into Orbitals, P. K. Biswas, Valentin Gogonea

Chemistry Faculty Publications

We present an ab initio polarizable representation of classical molecular mechanics (MM) atoms by employing an angular momentum-based expansion scheme of the point charges into partial wave orbitals. The charge density represented by these orbitals can be fully polarized, and for hybrid quantum-mechanical-molecular-mechanical (QM/MM) calculations, mutual polarization within the QM/MM Hamiltonian can be obtained. We present the mathematical formulation and the analytical expressions for the energy and forces pertaining to the method. We further develop a variational scheme to appropriately determine the expansion coefficients and then validate the method by considering polarizations of ions by the QM system employing the …

Role Of Transcription Factor Mef2a In Development Of Coronary Artery Disease (Cad) And Myocardial Infarction (Mi), Maniragava Sai Bhagavatula

ETD Archive

Coronary artery disease (CAD) and myocardial infarction (MI) are the leading cause of death in developed countries. Genetic factors play an important role in the pathogenesis of CAD and MI. The revolutionary advances in molecular genetics have provided new insights into the genetic pathways involved in this disease. Recently, our laboratory used linkage analysis to map the first disease-causing gene for CAD and MI to chromosome 15q26 in a large family and subsequently mutation analysis identified a 7-amio acid deletion in MEF2A, a gene encoding a transcription factor. Later we identified three novel mutations N263S, P279L, G283D in four other …

New Insights Into Molecular Mechanisms Of Fludarabine, Alina D. Bulgar

ETD Archive

Nucleotide analogs (e.g. fludarabine) are antimetabolites used in the treatment of a wide variety of hematological malignancies and solid tumors. Upon being metabolized to their active triphosphate form, these agents are incorporated into DNA. Among other molecular targets, their incorporation may lead to activation of base excision repair (BER) pathway. The molecular mechanism of BER recognition and repair of the incorporated fludarabine has not yet been elucidated. The main focus of this research was to study the involvement of BER pathway in the response to fludarabine induced DNA damage. Also, the possibility of enhancing antineoplastic activity of fludarabine by inhibition …

Quadrupole Magnetic Field-Flow Fractionation;A Novel Technique For The Characterization Of Magnetic Particles, Francesca Carpino

ETD Archive

In the last few decades, the development and use of nanotechnology has become of increasing importance. Magnetic nanoparticles, because of their unique properties, have been employed in many different areas of application. They are generally made of a core of magnetic material coated with some other material to stabilize them and to help disperse them in suspension. The unique feature of magnetic nanoparticles is their response to a magnetic field. They are generally superparamagnetic, in which case they become magnetized only in a magnetic field and lose their magnetization when the field is removed. It is this feature that makes …

Hydrogenase Inhibition By O2: Density Functional Theory/Molecular Mechanics Investigation, Daniela Dogaru

ETD Archive

[Fe-Fe]-hydrogenases are enzymes that reversibly catalyze the reduction of protons to molecular hydrogen, which occurs in anaerobic media. In living systems, [Fe-Fe]-hydrogenases shift the reversible reaction towards H2 formation. The [Fe-Fe]-hydrogenase H-cluster is the active site, which contains two iron atoms (Fep-Fed, i.e., proximal and distal iron). Because most experimental and theoretical investigations confirm that the structure of di-iron air inhibited species is FepII-FedII-O-O-H-, O2 has to be prevented from binding to Fed in all di-iron subcluster oxidation states in order to retain a catalytically active enzyme. By understanding the catalytic processes of metalloenzymes, researches are enabled to produce an …

Identification And Analysis Of Prohibitin In B16 Mouse Melanoma Cells, Christopher Francis

Theses, Dissertations and Capstones

Prohibitin, a highly conserved protein found in eukaryotic cells, has been found in recent years to possess a wide variety of functions in the cell. Whereas the mechanisms by which the protein functions are still largely unknown, it is clear that prohibitin possesses very strong anti-proliferative properties in the cell, as well as potentially both nuclear and mitochondrial functions based upon its movement and localization upon apoptotic signaling. Upon treatment with retinoic acid, transformed B16 mouse melanoma cells also indicate a differential expression of prohibitin in which production of the protein is increased. The purpose of this work was to …

Polystyrene As A Medium In Reverse-Phase Separation Of Polycyclic Aromatic Hydrocarbons, Madhavi Mantha

Browse all Theses and Dissertations

The purpose of the research was to design a method using high-performance liquid chromatography (HPLC) that would separate the sixteen polycyclic aromatic hydrocarbons (PAHs) designated by Environmental Protection Agency (EPA) as priority pollutants on two different kinds of polystyrene (PS) in the reversed phase. One was a zirconia-based column coated with polystyrene. The other was a polystyrene divinylbenzene (PS-DVB) column. The idea behind using these columns was to take advantage of extreme retention of PAHs by these columns by using high temperatures or temperature programming in order to reduce the amount of organic modifier in the mobile phases to perform …

Investigation Into The Synthesis Of Turmeric Derivatives, Jessica Kisunzu

Capstone Research Projects

Curcumin is a dye obtained by extraction from turmeric (Curcuma Longa L}. Derivatives of curcumin have been synthesized, mainly involving additions at the carbon between the two carbonyl groups. This research attempted to add an indole at both positions β to the ketone carbonyls to form 1,7-bis(indolyl)curcumin. The catalyst free, "on-water" synthesis was implemented and the resulting solid analyzed. A three step synthesis was then executed which involved the formation of an acylindole derivative and its subsequent reaction with a diketone to produce the desired product.

Parameterizing A Simple Potential Energy Function Appropriate For Vibrational Frequencies Using Molecular Dynamics, Carl W. David

Chemistry Education Materials

A Maple scheme for quickly parameterizing vibrational potential energy functions is presented. As an example, the potential energy function's parameters for the vibrational motions in H_2O_2 are obtained assuming the simplest potential energy function.

This paper was originally written as a research paper, but rejected by the referees. It is therefore being edited into an ``educational'' paper for student usage.

Kinetic Evaluation Of Highly Active Supported Gold Catalysts Prepared From Monolayer-Protected Clusters: An Experimental Michaelis-Menten Approach For Determining The Oxygen Binding Constant During Co Oxidation Catalysis, Cormac G. Long, John D. Gilbertson, G. Vijayaraghavan, K. J. Stevenson, Christopher J. Pursell, Bert D. Chandler

Chemistry Faculty Research

Thiol monolayer-protected Au clusters (MPCs) were prepared using dendrimer templates, deposited onto a high-surface-area titania, and then the thiol stabilizers were removed under H2/N2. The resulting Au catalysts were characterized with transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy of adsorbed CO. The Au catalysts prepared via this route displayed minimal particle agglomeration during the deposition and activation steps. Structural data obtained from the physical characterization of the Au catalysts were comparable to features exhibited from a traditionally prepared standard Au catalyst obtained from the World Gold Council (WGC). A differential kinetic study of CO oxidation catalysis by the …

Protein Adsorption Onto Organically-Modified Silica Glass Leads To A Different Structure Than Sol-Gel Encapsulation, Daryl K. Eggers, B, Menaa, C. Torres, M. Herrero, V. Rives, A. R.W Gilbert

Faculty Publications, Chemistry

The secondary structures of two proteins were examined by circular dichroism spectroscopy after adsorption onto a series of organically modified silica glasses. The glasses were prepared by the sol-gel technique and were varied in hydrophobicity by incorporation of 5% methyl, propyl, trifluoropropyl, or n-hexyl silane. Both cytochrome c and apomyoglobin were found to lose secondary structure after adsorption onto the modified glasses. In the case of apomyoglobin, the α-helical content of the adsorbed protein ranged from 21% to 28%, well below the 62% helix found in solution. In contrast, these same glasses led to a striking increase in apomyoglobin structure …

A Promising Change In The Selection Of The Circular Polarization Excitation Used In The Measurement Of Eu(Iii) Circularly Polarized Luminescence, K. Do, F. C. Muller, Gilles Muller

Faculty Publications, Chemistry

A judicious change in the selected transition used for circular polarization excitation will overcome the low oscillator strength limitation of the currently allowed magnetic-dipole 5D1 ← 7F2 (Eu(III)) transition chosen for circularly polarized luminescence (CPL) measurement. The proposed allowed magnetic-dipole 5D1 ← 7F0 (Eu(III)) transition will facilitate the detection of CPL from the Eu(III) systems of interest. CPL on the acetonitrile solution of the chiral tris complex of Eu(III) with (R,R)-N,N′-bis(1-phenylethyl)-2,6-pyridinedicarboxamide ([Eu((R,R)-1)3]3+), recently suggested as an effective and reliable CPL calibrating agent, confirms the feasibility of the proposed experimental procedure. A comparable CPL activity exhibited by the acetonitrile solution of …

Flash: A Rapid Method For Prototyping Paper-Based Microfluidic Devices, Andres W. Martinez, Scott T. Phillips, Benjamin J. Wiley, Malancha Gupta, George M. Whitesides

Chemistry and Biochemistry

This article describes FLASH (Fast Lithographic Activation of Sheets), a rapid method for laboratory prototyping of microfluidic devices in paper. Paper-based microfluidic devices are emerging as a new technology for applications in diagnostics for the developing world, where low cost and simplicity are essential. FLASH is based on photolithography, but requires only a UV lamp and a hotplate; no clean-room or special facilities are required (FLASH patterning can even be performed in sunlight if a UV lamp and hotplate are unavailable). The method provides channels in paper with dimensions as small as 200 μm in width and 70 μm in …

Novel Calixarene-Schiff Bases That Bind Silver(I) Ion, Mary Deasy, Bernadette Creaven, Brian A. Murray, John Mcginley, Paul M. Flood

Articles

Two novel calix[4]arene-Schiff base receptors have been synthesized. One of the new compounds has two pendant aldimines, while the second has been prepared by two-point attachment of a calixarene-dialdehyde onto a calixarene-diamine to form a “calix-tube”. Preliminary binding studies with AgClO₄ show large complexation-induced shifts in ¹H NMR positions.

Favourable Influence Of Hydrophobic Surfaces On Protein Structure In Porous Organically-Modified Silica Glasses, Daryl K. Eggers, B. Menaa, M. Herrero, V. Rives, M. Lavrenko

Faculty Publications, Chemistry

Organically-modified siloxanes were used as host materials to examine the influence of surface chemistry on protein conformation in a crowded environment. The sol–gel materials were prepared from tetramethoxysilane and a series of monosubstituted alkoxysilanes, RSi(OR′)3, featuring alkyl groups of increasing chain length in the R-position. Using circular dichroism spectroscopy in the far-UV region, apomyoglobin was found to transit from an unfolded state to a native-like helical state as the content of the hydrophobic precursor increased from 0 to 15%. At a fixed molar content of 5% RSi(OR′)3, the helical structure of apomyoglobin increased with the chain length of the R-group, …

Singlet Oxygen Chemistry In Water. 2. Photoexcited Sensitizer Quenching By O2 At The Water−Porous Glass Interface, Jovan Giaimuccio, Matibur Zamadar, David Aebisher, Gerald J. Meyer, Alexander Greer

Faculty Publications

Insight into the O2 quenching mechanism of a photosensitizer (static or dynamic) would be useful for the design of heterogeneous systems to control the mode of generation of 1O2 in water. Here, we describe the use of a photosensitizer, meso-tetra(N-methyl-4-pyridyl)porphine (1), which was adsorbed onto porous Vycor glass (PVG). A maximum loading of 1.1 × 10−6 mol 1 per g PVG was achieved. Less than 1% of the PVG surface was covered with photosensitizer 1, and the penetration of 1 reaches a depth of 0.32 mm along all faces of the glass. Time-resolved measurements …

Singlet Oxygen Chemistry In Water:  A Porous Vycor Glasssupported Photosensitizer, David Aebisher, Nikolay S. Azar, Matibur Zamadar, Naveen Gandra, Harry D. Gafney, Roumei Gao, Alexander Greer

Faculty Publications

Singlet molecular oxygen [1O2 (1Δg)] is generated cleanly in aqueous solution upon irradiation of a heterogeneous complex, meso-tetra(N-methyl-4-pyridyl)porphine (1) adsorbed onto porous Vycor glass (PVG). The cationic photosensitizer 1 tightly binds onto PVG and gives a stable material, which does not dissociate 1 into the surrounding aqueous phase. The production of 1O2 was measured by monitoring the time-resolved 1O2 (1Δg) phosphorescence at 1270 nm. Indirect analysis of 1O2 generation was also carried out with the photooxidation oftrans-2-methyl-2-pentenoate anion, which afforded the corresponding hydroperoxide. Sensitizer-1-impregnated PVG gives rise to a new singlet …

Poly(D,L-Lactide-Co-Glycolide) Microcomposite Containing Magnetic Iron Core Nanoparticles As A Drug Carrier, Sweta Naik, Everett E. Carpenter

Chemistry Publications

Today many potent anticancer drugs like cisplatin are available which carry a number of side effects. A promising way of reducing the side effects is to target the drug to tissue sites by coating it with biocompatible materials like Poly (dl-lactide-co-glycolide) (PLGA) polymer where controlled drug release is achieved during the biodegradation of the polymer. Also the efficacy of anticancer drugs like cisplatin increases at elevated temperatures, so if local heating can be achieved where the drug is targeted. Local heating can be achieved by introducing iron core nanoparticles in the composites along with the drug, which can be heated …

Modeling The Physical Properties Of A Homologous Series On The Melting Temperatures And Densities Of N-Alkanes And Their Simple Alkyl-Derivatives, Antun Rubčić, Jasna Rubčić, James Chickos

Chemistry & Biochemistry Faculty Works

No abstract provided.

Synthesis Of Phenoxides With Pendant Amines And Catalytic Intramolecular Hydroaminations, Kenneth Awasung

Undergraduate Review

One core focus of my research project, (my 2007 summer research) is to make structural analogs of substituted phenols to support the titanium catalysis of organic compounds. The synthesis and study of these and related ligands, (pyrrolyls, aldimines, salens, and other nitrogen/oxygen heterocycles) is a major field of organometallic chemistry. Bulky phenols and their analogs serve as highly effective ligands to support catalysis due to their sterics and electronics. I have been designing and have begun synthesizing phenol analogs using a series of aldol condensations and michael additions and other organic chemistry methodology to generate new substituted phenols. Our method …

Zeolite Activation Of Organometallics: Revisiting Substitution Kinetics Of [Mo(Co)6] With Chemisorbed Pme3 In Dehydrated Na56Y Zeolite, Anthony L. Fernandez, Jianbin Hao, Roberta L. Parkes, Anthony J. Poë, Eduardo J.S. Vichi

Chemistry & Biochemistry Faculty Publications

Reactions of [Mo(CO)₆] under vacuum in α-cages of Na₅₆Y zeolite fully loaded with chemisorbed PMe₃ form cis-[Mo(CO)₄(PMe₃)₂] but mixtures of [Mo(CO)₅(PMe₃)] and cis-[Mo(CO)₄(PMe₃)₂] are formed under CO. Reactions under vacuum exhibit low enthalpic and very negative entropic factors (ΔH = 71.4 ± 3.5 kJ mol^-1 and ΔS = -102 ± 11 J K^-1 mol^-1) compared with much higher enthalpic and positive entropic factors for CO dissociative reactions with P(n-Bu) …

The Tropical Forest And Fire Emissions Experiment: Laboratory Fire Measurements And Synthesis Of Campaign Data, Robert J. Yokelson, Ted J. Christian, T. G. Karl, Alex Guenther

Chemistry and Biochemistry Faculty Publications

As part of the Tropical Forest and Fire Emissions Experiment (TROFFEE), tropical forest fuels were burned in a large. biomass-fire simulation facility and the smoke was characterized with open-path Fourier transform infrared spectroscopy (FTIR), proton-transfer reaction mass spectrometry (PTR-MS), gas chromatography (GC), GC/PTR-MS, and filter sampling of the particles. In most cases, about one-third of the fuel chlorine ended up in the particles and about one-half remained in the ash. About 50% of the mass of non-methane organic compounds (NMOC) emitted by these fires could be identified with the available instrumentation. The lab fire emission factors (EF, g compound emitted …

A Theoretical Study For The Reactivation Of O2 Inhibited [Fe-Fe]-Hydrogenase, Stefan Motiu

ETD Archive

The current investigation presents a reactivation pathway of the exogenously inhibited H-cluster (viz., by O2, or OH-, which metabolizes to H2O), for both vacuum and aqueous enzyme phase. The H-cluster is the catalytic site of [Fe-Fe]-hydrogenase, with the latter extracted from Desulfovibrio desulfuricans (Dd) bacteria. It consists of proximal iron, Fep, and distal Fed subunit, [Fep-Fed], which is bridged by di(thiomethyl)amine (DTMA) ligand, and a proximal cubane subunit, [Fe4-S4]2+p. [Fep-Fed] is coordinated by two cyanides (CN-), two terminal carbonyls (COt), and a bridging carbonyl (COb)*. An Fe atom from [Fe4-S4]2+p connects Fep through a cysteinyl sulfur (of Cys382). Density functional …

Constructing Explicit Magnetic Analogies For The Dynamics Of Glass Forming Liquids, Jacob D. Stevenson, Aleksandra M. Walczak, Randall W. Hall, Peter G. Wolynes

Collected Faculty Scholarship

By defining a spatially varying replica overlap parameter for a supercooled liquid referenced to an ensemble of fiducial liquid state configurations, we explicitly construct a constrained replica free energy functional that maps directly onto an Ising Hamiltonian with both random fields and random interactions whose statistics depend on the liquid structure. Renormalization group results for random magnets when combined with these statistics for the Lennard-Jones glass suggest that discontinuous replica symmetry breaking would occur if a liquid with short range interactions could be equilibrated at a sufficiently low temperature where its mean field configurational entropy would vanish, even though the …

Ua66/1/5 Icset - Institute For Combustion Science & Environmental Technology, Wku Ogden College Of Science & Engineering

WKU Administration Documents

History and overview of the work of the WKU Institute for Combustion Science & Environmental Technology through 2008.

Mass Spectrometric Analysis Of Environmental Contaminants, Protein Structure And Expression, Ian E. Atkinson

ETD Archive

There are a wide array of sciences at our disposal to further our understanding of the roles of toxins in the environment and their effects on living organisms. Of these disciplines, the field of mass spectrometry offers a powerful analytical means to identify compounds in varying and complex sample media. The presence of altered expressions of biomolecules upon exposure to toxins, the effects that these toxins may have on biomolecule structure and the identity of toxins in the sample all can be determined by mass spectrometry. In this study mass spectrometric analysis has been applied to environmental toxicological problems. First, …

Factor Va Directs Catalysis By Factor Xa During Prothrombin Activation, Michael Anthony Bukys

ETD Archive

Hemostasis occurs through the controlled activation and inactivation of clotting factors resulting in the arrest of bleeding without blockage to the vasculature, while thrombosis is the undesired formation of vascular blood clots, which adversely affects millions of people annually. Clotting factors circulate in blood as inactive zymogens, which are proteolytically activated in response to vascular injury, assembled into enzymatic complexes and in turn activate additional coagulation factors culminating in the production of thrombin from the enzymatic complex prothrombinase. The prothrombinase complex is composed of the activated enzymatic component factor Xa (fXa) complexed to the activated cofactor portion factor Va (fVa) …