Chemistry Commons^™

Comparison Between The Ultraviolet Emission From Pulsed Microhollow Cathode Discharges In Xenon And Argon, Isfried Petzenhauser, Leopold D. Biborosch, Uwe Ernst, Klaus Frank, Karl H. Schoenbach

Bioelectrics Publications

We measured the dynamic I–V characteristics and vacuum ultraviolet (VUV) emission lines of the second continuum in xenon (170 nm) and argon (130.5 nm) from pulsed microhollow cathode discharges (MHCD). For pulse lengths between 1 and 100 μs the dynamic I–V characteristics are similar in both inert gases. Only the time variation of the VUV emission line at 170 nm for xenon can be related to the dimer excited states. In argon the energy transfer between the Ar*₂ dimers and the oxygen impurity atoms is responsible for a qualitatively different time behavior of the resonance line at 130.5 nm. …

Design And Synthesis Of Constrained Dipeptide Units For Use As Β-Sheet Promoters, Umut Oguz

LSU Doctoral Dissertations

The study of factors promoting beta-sheet formation has recently gained interest due to the suspected involvement of beta-sheets in brain degenerative diseases such as Alzheimer's disease (AD), Creutzfeldt-Jacob disease (CJD) and bovine spongiform encephalopathy. Understanding beta-sheet formation and the factors that stabilize beta-sheet structure may serve as a basis for future drug design. The extended structure of a beta-sheet can be stabilized by constrained amino acid analogs that are pre-organized to adopt the extended conformation. In this dissertation using innovative synthetic organic chemistry methods, two dipeptide units are designed and synthesized that are constrained to form the extended conformation and …

Synchrotron Radiation As A Probe Of Chemical Information Using Novel Experimental Configurations, George Farquar

LSU Doctoral Dissertations

Determination of chemical information with synchrotron radiation is an area of great scientific interest, and expanding the range of available techniques is the topic of this dissertation. The experimental methods described herein allows for a significant advancement of the availability of subtle chemical information. This dissertation uses ionizing radiation to study three chemical systems. First, the l=3 shape resonance in CO is investigated using a cryogenically cooled gas jet. Shape resonant effects have been studied for many years. Previously, this was accomplished on the vibrational structure of molecules with a limited ability to determine the rotational substructure effects. A dramatic …

Dynamics Of Bulk And Adsorbed Poly(Vinyl Acetate), Frank D. Blum, Robert D. O'Connor

Materials Science and Engineering Faculty Research & Creative Works

We have recently completed a series of experiments on methyl-labeled poly(vinyl acetate)-d3, (PVAc-d3)1 and poly(methyl acrylate)-d3 (PMA-d3).234 the systems have been studied as a function of the adsorbed amount, molecular weight, and presence of a protonated overlayer. Using deuterium line shape analysis, we have found that around the glass transition temperature, the adsorbed polymers show the presence of a motional gradient. Polymer segments near the silica-polymer interface have less mobility than the bulk polymer and those near the polymer-air interface are more mobile than those of the bulk polymer. A schematic representation of the motional gradient is shown in Figure …

Stably Folded De Novo Proteins From A Designed Combinatorial Library, David Moffet

Chemistry and Biochemistry Faculty Works

Binary patterning of polar and nonpolar amino acids has been used as the key design feature for constructing large combinatorial libraries of de novo proteins. Each position in a binary patterned sequence is designed explicitly to be either polar or nonpolar; however, the precise identities of these amino acids are varied extensively. The combinatorial underpinnings of the "binary code" strategy preclude explicit design of particular side chains at specified positions. Therefore, packing interactions cannot be specified a priori. To assess whether the binary code strategy can nonetheless produce well-folded de novo proteins, we constructed a second-generation library based upon a …

Chemical Vapor Deposited Diamond Films For Self-Referencing Fiber Optic Raman Probes, Sacharia Albin, Jianli Zheng, Bing Xiao, John B. Cooper, Robert B. Jeffers, Sonia Antony

Chemistry & Biochemistry Faculty Publications

Diamond thin films grown by the microwave plasma enhances chemical vapor deposition (CVD) process have been investigated as an internal reference in fiber optic remote Raman sensing. The growth parameters have been optimized for diamond thin films on quarts substrates using a gas mixture of methane, carbon dioxide, and hydrogen. The resulting films exhibit essentially no Raman spectral background while exhibiting a strong Raman peak at 1332 cm^-¹. The films are used as an internal reference in the quantitative measurement of chemical concentration using remote fiber optic Raman sensing. Internal referencing is accomplished by normalizing all spectral intensities …

Resonance Two Photon Ionization Study Of Binary Clusters Of Styrene With Polar Molecules, Hatem Ahmed Mahmoud

Theses and Dissertations

One-color resonance two-photo ionization (R2PI) spectra of mixed clusters of styrene molecule (S) with polar molecules [water (W), methanol (M), ethanol (E), and trifuoroethanol (T)] were measured through the S1←S0 transition of the styrene molecule. The spectra reveal a rapid increase in complexity with the number of polar molecules in the cluster, associated with van der Waal modes and isomeric forms. The spectral shifts of the cluster origins from the S1-S0 transition of the bare styrene molecule reflect the nature of the intermolecular interactions within the binary clusters. The obtained R2PI spectra xv were compared with the spectra of the …

Sonogashira Coupling Routes To Ortho-Alkynl-And- Fused-Ring Sydnones, Andrew John Weisner

Browse all Theses and Dissertations

In the present work, suitably functionalized arylsydnones were used to synthesize a variety of ortho-alkynyl sydnones both as potential precursors to novel sydnoquinolines and to provide non-linear optical (NLO) species of interest to Wright-Patterson Air Force Base (WPAFB). The versatile intermediate, 3-(2-(trimethylsilylethynyl)phenyl)sydnone, was prepared in good yield by the coupling of 3-(2-iodophenyl)sydnone with trimethylsilyl acetylene under Sonogashira conditions. From this intermediate, several ortho-alkynyl sydnones were prepared via a one-pot desilylation with tetrabutylammonium fluoride and Sonogashira coupling with para-substituted aryl iodides. In addition, a three-reaction-in-one-pot procedure was developed to access some of these species directly from 3-(2- iodophenyl)-sydnone. Subsequent reaction of …

Nitroalkane Anomaly: Computational Study With Cluster And Continuum Modeling, H. Yamataka, Salai Cheettu Ammal

Faculty Publications

The origin of anomalous relation between rates and equilibria for the proton-transfer reactions of nitroalkanes, known as nitroalkane anomaly, was investigated by theoretical calculations with a cluster model, in which three water molecules are explicitly considered in the system, as well as the PCM solvent continuum model. For the CH3NO2/CH3CH2NO2 system, B3LYP and MP2 computations reproduced the anomaly, and the imbalance in the charge distribution at the transition state (TS) was observed. In contrast, although the TS imbalance was detected for the substituted phenylnitromethane system, the Brønsted plots did not show any anomaly. The experimentally observed abnormally large Brønsted coefficient …

Adsorption And Reaction Of Benzaldehyde On Porous Glass Studied By Ftir And Tpd, Steven Michael Badger Ii

Dissertations and Theses @ UNI

Benzaldehyde was dosed onto porous borosilicate glass in order to better understand the catalytic behavior of the surface of the porous glass. 18,000 L of benzaldehyde was dosed onto the porous glass at approximately 50 K and heated to a temperature of 470 K. The reactions that occurred were studied using FTIR spectroscopy and Temperature Programmed Desorption (TPD). The FTIR spectrum of the porous glass confirmed the presence of isolated surface hydroxyl groups (Si-OH), seen in the spectrum at 3750 cm1 , and the presence of isolated boron-OH groups, seen in the spectrum at 3700 cm1 . Neighboring surface hydroxyl …

Application Of The Chan-Evans Diaryl Ether Synthesis To The Formation Of Bis(Bibenzyls), Eric Rosenthal

Honors Theses

Alkene (6) was produced in three steps from 3-hydroxybenzaldehyde (8), and 3-bromobenzyl bromide (10). A variety of strategies were employed to synthesize the desired boronic acid (13), but as of this time none have been successful. The synthesis of this boronic acid is necessary to study the feasibility of applying the Chan-Evans copper mediated formation of diaryl ethers to a bis(bibenzyl) synthesis. In seeking to exploit the advantages of the Chan-Evans ether synthesis over the Ullman ether synthesis, we have encountered some of the associated difficulties. The utilization of an arylboronic acid to produce a diaryl ether first requires the …

Approaches To The Synthesis Of Novel Triptycene Dendrimers And Hyperbranched Poly(Phenylene Sulfides) And Poly(Phenylene Sulfones), Alfredo Mellace

Seton Hall University Dissertations and Theses (ETDs)

.

Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Allen L. Johnson, Dale L. Perry

Transmutation Sciences Materials (TRP)

Materials for transmuter systems must be able to tolerate high neutron fluxes, great temperatures, and chemical corrosion. For lead bismuth eutectic (LBE) systems, there is an additional challenge in that the corrosive behaviors of materials in LBE are not well understood. Most of the available information on LBE systems has come from the Russians, who have over 80 reactor-years experience with LBE coolant in their Alpha-class submarine reactors. The Russians found that the presence of small amounts of oxygen (on the order of parts per million) in the LBE significantly reduced corrosion. However, a fundamental understanding and verification of its …

Surface Studies Of Corrosion Of Stainless Steel By Lead Bismuth Eutectic, Daniel Koury, Brian D. Hosterman, John Farley, Dale L. Perry, D. Parsons, J. Manzerova, Allen L. Johnson

Transmutation Sciences Materials (TRP)

Why is Lead Bismuth Eutectic Important?

• Changing national security stances have led to reexamination of nuclear waste reprocessing

• Dangerous actinides can be separated and

• Transmuted into safer products, creating a waste form dangerous for only hundreds of years, in addition to the production (up to 1/3 of the original fission energy) of useful energy

• Non-moderating coolants or spallation targets for production of fast neutrons is required for transmutation

• Russian experience with LBE coolants in their nuclear submarine fleet makes LBE an attractive possible transmutation coolant technology

• Corrosion of steel by LBE is an important …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials, Ajit K. Roy, Brendan O'Toole, Zhiyong Wang, David W. Hatchett

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the potential for the environmentally-assisted cracking of candidate target materials for applications in spallation-neutron-target systems, such as accelerator-driven system for the transmutation of waste. The materials selected for evaluation and characterization are martensitic stainless steels (SS) including Alloys HT- 9, EP 823 and Type 422 stainless steel.

More recently, this experimental program has been expanded to evaluate the effect of molten lead-bismuth eutectic (LBE) on the corrosion behavior of target materials in the presence of oxygen. Since the materials performance laboratory (MPL) at UNLV currently cannot accommodate this type of testing, …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The corrosion of structural materials is a major concern for the use of lead-bismuth eutectic (LBE) systems for nuclear applications such as in transmuter targets or fast reactors. Corrosion in liquid metal systems can occur through various processes, including, for example, dissolution, formation of inter-metallic compounds at the interface, and penetration of liquid metal along grain boundaries. Predicting the rate of these processes depends on numerous system operational factors: temperature, system geometry, thermal gradients, solid and liquid compositions, and velocity of the liquid metal, to name a few. Corrosion, along with mechanical and/or hydraulic factors, often contributes to component failure. …

Modeling Of Corrosion In Oxygen Controlled Lead Bismuth Eutectic Systems With The Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen, Kanthi Kiran Dasika, Chao Wu

Transmutation Sciences Materials (TRP)

Objectives:

• To simulate a 2-D model of the Materials Test Loop by approximating it to be a toroid with a pie cross section for the purpose of comparing the simulated results with the analytical results.
• The temperature and concentration profiles on the wall boundaries imposed are similar to the actual test model.
• Geometry effects have great influence on local corrosion rate.
• A 2-D benchmark problem and a sudden expansion case are studied which show good consistency to analytical solution.
• Results from 2-D sudden expansion problem are similar to experimental data obtained by other researchers.

Nuclear Criticality, Shielding, And Thermal Analyses Of Separations Processes For The Transmutation Fuel Cycle, William Culbreth, Denis Beller

Separations Campaign (TRP)

The first step in any transmutation strategy is the separation of radionuclides in used nuclear fuel. The current separation strategy supporting the Advanced Fuel Cycle Initiative (AFCI) program is based on the use of a solvent extraction separation process to separate the actinides, fission products, and uranium from used commercial nuclear fuel, and on the use of pyrochemical separation technologies to process used transmuter fuels. To separate the fission products and transuranic elements from the uranium in used fuel, the national program is developing a new solvent extraction process, the Uranium Extraction Plus, or UREX+, process, based on the traditional …

Evaluation Of Fluorapatite As A Waste-Form Material, Dennis W. Lindle, Dale L. Perry

Separations Campaign (TRP)

Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal is for renewal of the UNLV portion of a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF₄, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and …

Evaluation Of Fluorapatite As A Waste-Form Material, Dennis W. Lindle, Dale L. Perry

Separations Campaign (TRP)

Argonne National Laboratory has proposed a new extraction procedure to handle TRISO-coated fuels, the Fluoride Extraction Process, or FLEX. The FLEX process is designed to separate the uranium in the fuel from the actinides and most fission products by taking advantage of the unique properties of uranium hexafluoride (UF₆). In the FLEX process, the used TRISO fuel is reacted with zirconium fluoride salt, forming UF₆ and the fluoride salts of the actinides and fission products. At process temperatures, the UF6 volatizes into a gas, and is released from the molten salt mixture. This leaves behind the actinides …

The Synthesis Of 2-(1-Indenyl)-Phenol: A Potential Ligand For Metallocene Polymerization Catalysts; And, Ω-Iodoalkyl(Methyl) Malonate Esters: Synthesis And Application In Bioconjugate Chemistry, Sara E. Bendler

Masters Theses

Chapter I:

Metallocene catalysis is an important division of polymerization chemistry. The design of appropriate ligands for metallocene catalysts has focused on stereochemical control and structural diversity. The synthesis of the potential ligand 2-(1-indenyl)-phenol has been developed. Indenyl phenol ligands offer advancements over cyclopentadienyl ligands because the steric and electronic properties of the catalyst could be tailored to suit individual polymerization reactions. 2-(1-Indenyl)-phenol was synthesized with an overall yield of 4% and characterized with ¹H NMR and ¹³C NMR.

Chapter II:

A large percentage of breast malignancies overexpress the nuclear estrogen receptor (ER) protein. Binding to nuclear receptors …

Solving Chemical Problems Of Environmental Importance Using Cavity Ring-Down Spectroscopy, Dean B. Atkinson

Chemistry Faculty Publications and Presentations

Cavity ring-down (CRD) is a sensitive variant of traditional absorption spectroscopy that has found increasing use in a number of chemical measurement applications. This review focuses on applications of cavity ring-down spectroscopy that will be of interest to environmental chemists and analytical chemists working on environmental problems. The applications are classified into direct monitoring approaches, indirect analysis methods and ancillary studies and a differentiation is made between field-tested instruments and proof of principle studies.

Diffusion Of A Rodlike Virus In Complex Solutions, Randall Charles Cush

LSU Doctoral Dissertations

Entanglement phenomena in concentrated polymer solutions remain an interesting and challenging problem. It is still unclear how entanglement onset affects polymer chain motion at small distance scales. One way to study such motion is to follow the diffusion of a probe particle while increasing the concentration of the polymer. Many such studies have been done using probes ranging from linear and star polymers to various colloidal particles; however, relatively few studies have used rodlike probes. Rodlike probes are potentially more interesting due to the added information that may be gained by following rotational as well as translational diffusion. The anisotropic …

Solid-Phase Dna Sequencing Reactions Performed In Micro-Capillary Reactors And Solid-Phase Reversible Immobilization In Microfluidic Chips For Purification Of Dye-Labeled Dna Sequencing Fragments, Yichuan Xu

LSU Doctoral Dissertations

The research presented in this dissertation involves micro-capillary reactors for solid phase DNA sequencing, the identification of dye terminator sequencing fragments with time-resolved methods, and purification of dye-labeled DNA fragments using solid- phase reversible immobilization in microfluidic chips. Solid-phase micro-reactors have been prepared for DNA sequencing applications using slab gel electrophoresis. A PCR product was immobilized to the interior wall of a fused-silica capillary tube via a biotin-streptavidin linkage. Solid-phase sequencing was carried out in micro-capillary reactors using a four-lane, single color dye primer chemistry strategy. The read length was found to be 589 bases. The complementary DNA fragments generated …

Genome Analysis: Mutation Analysis Using Near Infrared Laser-Induced Fluorescence (Nir-Lif) And Single Molecule Detection In Microfluidic Devices, Musundi Ben Wabuyele

LSU Doctoral Dissertations

A number of genotyping methods have been developed for mutation analysis, each of which has its own unique advantage. DNA amplification via polymerase chain reaction (PCR) provides an unlimited supply of material for subsequent genetic analysis even in case where only a single copy of the DNA molecule is present in the sample. Research presented in this dissertation first examines the efficiency of in vitro amplification of single copy DNA with subsequent sequencing analysis of PCR product. The PCR products (amplicons) were investigated for possible alteration, distortions or mutations due to the amplification process. The sequencing data for single copy …

Nanocomposites Based On Poly (Ε-Caprolactone) (Pcl)/Clay Hybrid: Polystyrene, High Impact Polystyrene, Abs, Polypropylene And Polyethylene, Xiaoxia Zheng, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of polystyrene, high impact polystyrene, acrylonitrile–butadiene–styrene terploymer, polypropylene and polyethylene have been prepared using an organically-modified clay that contains polycaprolactone—PCL-modified clay. Depending upon the mode of preparation of the PCL-modified clay, all three types of nanocomposites, immiscible, intercalated and exfoliated, may be produced. The materials have been characterized by X-ray diffraction, transmission electron microscopy, cone calorimetry, thermogravimetric analysis, and the evaluation of mechanical properties.

Molecular Recognition Of No/No+ Via Multicenter (Charge-Transfer) Binding To Bridged Diarene Donors. Effect Of Structure On The Optical Transitions And Complexation Thermodynamics, Sergiy V. Rosokha, Sergey V. Lindeman, Rajendra Rathore, Jay K. Kochi

Chemistry Faculty Research and Publications

Bridged diarenes form very strong [1:1] complexes with nitrosonium/nitric oxide in which the NO moiety is optimally sandwiched in the cleft between a pair of cofacial aromatic rings which act as a molecular “Venus flytrap”. The spectral features of these associates are generally similar to those for [1:1] and [2:1] nitrosonium complexes with mononuclear alkyl-substituted benzenes, and they are appropriately described within the LCAO molecular-orbital methodology and the Mulliken (charge-transfer) formulation of donor/acceptor electronic transitions. The thermodynamics study indicates that the efficient binding is determined by (i) the close matching of the donor/acceptor redox potentials and (ii) the ability of …

An Xps Investigation Of Thermal Degradation And Charring On Poly(Vinyl Chloride)–Clay Nanocomposites, Jianxin Du, Dongyan Wang, Charles A. Wilkie, Jiangqi Wang

Chemistry Faculty Research and Publications

More information concerning the thermal degradation and charring of nanocomposites of poly(vinyl chloride), dioctyl phthalate and clay has been obtained by the use of X-ray photoelectron spectroscopy and the acquisition of the carbon (C1s), chlorine (Cl2p), and oxygen (O1s) spectra. In the cases of polystyrene–clay and poly(methyl methacrylate)–clay nanocomposites, it has been shown that the clay migrates to the surface as the temperature is raised and the polymer degrades, thereby confirming the barrier properties as a mechanism by which these materials function. For PVC–clay nanocomposites the surface at high temperatures is dominated by carbon, and not the oxygen of the …

A Stibonium-Modified Clay And Its Polystyrene Nanocomposite, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Triphenylhexadecylstibonium trifluoromethylsulfonate has been prepared and ion-exchanged with sodium montmorillonite to obtain a new organically-modified clay. The clay has higher thermal stability than an ammonium clay; only a portion of the alkyl chain is lost during degradation and all of the antimony is retained. This clay has been used to prepare a polystyrene nanocomposite in which the clay is not uniformly distributed throughout the polymer. Nonetheless the polymer does insert into the clay layers and the d-spacing of the clay expands from 2.0 to 3.0 nm. The enhanced thermal stability of this system may mean that it could be …

In Situ Reactive Blending To Prepare Polystyrene-Clay And Polypropylene-Clay Nanocomposites, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of polystyrene and polypropylene with organically-modified clay may be prepared by melt blending in a Brabender mixer the clay and the polymer. The presence of maleic anhydride increases the likelihood of nanocomposite formation for polystyrene but is less important for polypropylene. The materials that result are immiscible materials, in that the clay is not uniformly distributed throughout the polymer matrix, but there is polymer inserted between the clay layers. The results from cone calorimetry suggest that nanocomposite formation has occurred, since there is a significant reduction in the peak heat release rate.