Physical Chemistry Commons^™

Advances In Raman Hyperspectral Compressive Detection Instrumentation For Fast Label Free Classification, Quantitation And Imaging, Bharat R. Makani

Open Access Dissertations

Multiple prototypes of hyperspectral compressive detection (CD) Raman spectrometers have previously been constructed in the Ben-Amotz lab and have proven to be useful for fast, label-free chemical identification, quantitation and imaging. The CD spectrometer consists of a volume holographic grating (VHG) that linearly disperses the Raman photons into its component wavelengths and all wavelengths are focused onto a digital micromirror devise (DMD). The DMD is an optical modulator that consists of an array of programmable 10μm mirrors that can reflect photons in either +12° or -12° to the incoming light. The DMD is tilted such that the +12° photons go …

Single-Conformation Spectroscopy Of Hydrogen Bonding Networks: Solvation, Synthetic Foldamers, And Neurodegenerative Diseases, Patrick S. Walsh

Open Access Dissertations

The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as proteins, revealing secondary structure information. Bottom-up experiments are performed on small molecules, utilizing high-resolution spectroscopy to reveal underlying quantum mechanical effects. The complexity gap is formed between these two experimental regimes; between large and small molecules; between bulk and individual solvent molecules; between classical mechanics calculations and quantum chemical calculations. This dissertation will focus on the application of gas phase, …

Determination Of Kinetic Parameters Of Equilibrium Peracetic Acid And Hydrogen Peroxide To Calculate Self-Accelerating Decomposition, Ricky Mittiga

Multidisciplinary Studies Theses

Determination of Kinetic Parameters of Equilibrium Peracetic Acid and Hydrogen Peroxide to Calculate Self-Accelerating Decomposition Temperature

Peracetic acid is a simple molecule that works as a powerful oxidant in many applications including food safety and water disinfection. The synthesis of the compound is fairly well understood due to its straightforward synthesis by mixing acetic acid and hydrogen peroxide. However, the decomposition of the compound has not been well studied. Few sources are available to provide kinetic data for the decomposition along with data that shows when the compound will undergo a self-accelerated decomposition that could lead to disastrous effects.

This …

Correlation Of Polymer Performance And Hansen Solubility Parameters, Daniel Jobse Mania

Master's Theses

Ready-to-use (RTU) grout is becoming more important to the finish and remodeling construction industry. Market research shows it is a fast-growing product that not only is creating its own space, but is beginning to supplant existing technology.

The original intent of this research was to investigate formulation parameters and how they affect grout performance. It was learned that particle size and oil absorption (OA) value are important filler properties that affect performance as much as adequate packing density and optimal pigment volume concentration (PVC) without going beyond critical PVC (CPVC).

Polymer architecture was also determined to be extremely important, but …

Preparation And Characterization Of Singlet-Oxygen Generating Thiol-Ene Networks Containing Fullerene And Metallofullerene Derivatives, Emily Matthews Barker

Dissertations

This work explores the derivatization of C₆₀ and Sc₃N@C₈₀ with S-, P-, and C- centered radicals, and is the first exploration into the functionalization of Sc₃N@C₈₀ with sulfur and phosphorous. The number of addends bound to C₆₀, as a function of reaction time and molar ratios, as well as, structure-property relationships including thermal stability, solubility, and singlet oxygen generation were explored. Fullerene derivatives exhibiting enhanced solubility were incorporated into two different thiol-ene polymer matrices at varying thiol-ene monomer concentrations (1:1 or 1:0.75 molar equivalents) and at different C₆₀ loadings (0, …

Characterization Of Etbe + Cl And Isooctane + Cl Combustion Products Using Synchrotron Photoionization, Rong Yao

Master's Theses

The low temperature (298 – 700 K) oxidation characterizations of a series of fuel additives (ETBE and isooctane) were studied at advanced light source in Lawrence Berkley National lab, using a multiplexed chemical kinetics photoionization mass spectrometer with tunable synchrotron radiation. Using Cl atoms as initiators in presence of oxygen, photoionization data were collected. Data analysis was performed via characterization of the reaction species photoionization spectra and kinetic traces, from which the products and also the intermediates were identified. Relevant reaction dynamics on potential energy surfaces were calculated, reaction enthalpies of each individual step were presented using the CBS-QB3 composite …

Structural Behavior Of Nbsexte2-X Superconductors Under High Pressure, Vahe Mkrtchyan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Niobium chalcogenide compounds have recently gained a great deal of interest due to the fact that a superconducting phase coexists with the charge density wave state (CDW), as well as their potential for numerous applications. Two superconducting compositions, NbSexTe2-x (x=2, 1.5) were prepared by solid state route using high purity Nb, Se, and Te powders. Powder X-ray diffraction patterns collected at ambient conditions for NbSe2 and NbSe1.5Te0.5 showed a single phase with hexagonal crystal structure, with space group P63mmc. High-pressure X-ray diffraction measurements were performed at the Advanced Photon Source at Argonne National Laboratory to investigate structural stability up to …

Development Of Organocatalytic Reactions For The Assembly Of Complex Molecules, Chenguang Yu

Chemistry and Chemical Biology ETDs

Development of efficient organocatalytic reactions for the facile assembly of synthetically and medicinally useful molecules is an important task in modern organic synthesis. Towards this end, my Ph. D. study focuses on the development of novel organocatalytic reactions for the construction of structurally diverse molecular architectures. A chiral bifunctional amine thiourea as promoter has been developed as an efficient solution to a long standing challenging issue in atropo-enantioselective transesterification of the Bringmann lactones. This organocatalytic approach delivers the first highly enantioselective, high yielding dynamic kinetic resolution process for the preparation of axially chiral biaryl compounds with a broad substrate scope …

Molecular Structure And Exciton Dynamics In Organic Conjugated Polymers, Alan K. Thomas

Chemistry and Chemical Biology ETDs

Intermolecular electronic interactions, dipole coupling and orbital overlap, caused by π-π stacking in organic conjugated polymers lead to unique structures and properties that can be harnessed for optoelectronic applications. These interactions define structure-function relationships in amorphous and aggregated forms of polymers in the solid state and determine their efficiencies and functionality in electronic devices, from transistors to solar cells. Organic polymer electronic device performance depends critically upon electronic coupling between monomer units --mediated by conformation and packing characteristics -- that dictates electronic properties like conductivity and capacitance as well as electronic processes, such as charge carrier generation and transport. This …

Synthesis And Applications Of Lanthanide Sulfides And Oxides, Christopher Marin

Department of Chemistry: Dissertations, Theses, and Student Research

This dissertation focuses on two of the key fields where lanthanides find ready application: as optically active materials with a focus on the lanthanide sulfides, and as catalytic materials with a focus on cerium oxide.

The lanthanide sulfides have attracted considerable interest for their potential as solar energy conversion materials, pigments, infrared window materials, and phosphor host media. However, applications of these materials remain limited due to their synthetic difficulty along with their not well understood properties compounded by both their difficulty in manufacturing as well as in simulating largely due to the need to take into account f-shell electrons. …

Development Of Oligo(P-Phenylene Ehynylene)(Ope) Applications Against Chemical And Biological Threats, Suhyun Yoon

Chemistry and Chemical Biology ETDs

Four new applications of oligo-phenylene ethynylene (OPE) and poly-PE (PPE) compounds for detection and destruction of biological and chemical threats have been investigated. Mixed surfaces composed of PPEs and a thermoswitchable polymer were created, and were shown to be able to capture, kill, and reversibly release pathogenic bacteria. In order to develop fluorescent sensors for CW agents, the spectral changes of OPEs with surfactants and malathion (a simulant for nerve agents) were measured. Formation of OPE-dimers in the presence of surfactants can cause fluorescence enhancement (turn-on) or quenching (turn-off). Among six positive and negative OPEs, only OPEs with ethyl ester …

Resonance Raman Studies Of Oxygenated Forms Of Myoglobin And Cyp2b4 And Their Mutants, Ying Wang

Dissertations (1934 -)

Important oxidative heme enzymes use hydrogen peroxide or activate molecular oxygen to generate highly reactive peroxo-, hydroperoxo- and feryl intermediates resulting from heterolytic O-O bond cleavage. Members of the cytochrome P450 superfamily catalyze difficult chemical transformations, including hydroxylations and C-C bond cleavage reactions. In mammals, these enzymes function to reliably produce important steroids with the required high degree of structural precision. On the other hand, certain other mammalian P450s serve a different role, efficiently metabolizing xenobiotics, including pharmaceuticals and environmental pollutants. Though so important, the precise mechanisms involved in such transformations are incompletely understood, because of difficulties in structurally characterizing …

Synthesis, Structural Diversity, And Redox Control Of Cyclometalated Monoruthenium Complexes, Zhong-Liang Gong, Jiang-Yang Shao, Yu-Wu Zhong

Journal of Electrochemistry

Cyclometalated ruthenium complexes have received increasing attractions recently due to their excellent redox and photophysical properties. One structural feature of these complexes is that there is a ruthenium-carbon (Ru-C) σ bond presented in the molecule. Three common methods, namely, the “late metalation”, “early metalation”, and “transmetalation” methods, for the synthesis of cyclometalated ruthenium complexes are discussed and summarized. General strategies for the design of cyclometalating ligand and cyclometalated ruthenium complexes are introduced. By using different ancillary ligands, such as pyridine, imidazole, triazole, and pyrimidine, a great number of ruthenium complexes can be prepared. The presence of the Ru-C bond significantly …

Electrochemical And In Situ X-Ray Absorption Fine Structure Study Of Li-Rich Cathode Materials, Meng-Yan Hou, Hong-Liang Bao, Ke Wang, Jian-Qiang Wang, Yong-Yao Xia

Journal of Electrochemistry

A series of the lithium-rich and manganese-based layered structure xLi₂MnO₃•(1-x)LiMn_1/3Ni_1/3Co_1/3O₂ (x = 0.3,0.5,0.7) materials were synthesized by a co-precipitation method, and followed by a solid-state reaction process. By comparing the first cycle efficiency, the reversible discharge capacity, the cycling stability and the voltage decay during the charge/discharge cycling process, the material with the composition of 0.5Li₂MnO₃•0.5LiMn_1/3Ni_1/3Co_1/3O₂was found to show the best electrochemical performance. The lithium storage mechanism and thermal stability of the de-lithiated compound were also investigated …

The Progress Of Order-Structured Membrane Electrode Assembly, Shang-Feng Jiang, Bao-Lian Yi

Journal of Electrochemistry

Performances of proton exchange membrane fuel cells (PEMFCs) have been recently improved. However, the cost and Pt loading must be further reduced for the commercialization of PEMFCs. Previous researches have proved that the order-structured electrode is beneficial to the effective utilization of Pt-based catalysts, decreasing the Pt loading and increasing the three-phase boundary for reaction. Especially, the nanostructure thin films (NSTFs) electrode, an ultra-thin catalytic layer developed by 3M Company, demonstrates high performance and durability. Besides, some other researchers have employed the high conductive carbon nanotube arrays or high stable metal oxide arrays as the order-structured catalyst supports for fundamental …

Recent Progress In Solid-State Nmr Study Of Electrode/Electrolyte Materials For Lithium/Sodium Ion Batteries, Gui-Ming Zhong, Zi-Geng Liu, Da-Wei Wang, Qi Li, Ri-Qiang Fu, Yong Yang

Journal of Electrochemistry

Solid state NMR technique is a powerful tool for characterizing the local structure and compositions of solid materials quantitatively. A comprehensive understanding of the structure evolution during the electrochemical reactions of the materials for lithium/sodium ion batteries will be obtained with the combination of solid state NMR, XRD, and XAS methods. Through analyzing solid state NMR spectra, we can obtain the compositions, local structures and ion diffusion dynamics of electrodes, electrolytes and surface layers for lithium/sodium ion batteries, providing an important theoretical support for the design and development of high-performance materials for batteries. In this paper, we review the recent …

Uniform Nanoshells For Functional Materials: Constructions And Applications, Shu-Yi Duan, Wei Zhang, Jun-Yu Piao, An-Min Cao, Li-Jun Wan

Journal of Electrochemistry

As a significant protocol for materials treatment, surface modification has found broad applications in different fields including catalyst, photochemistry, and electrochemistry. Herein, we introduced the representative synthetic methodologies for the constructions of different functional materials with a focus on their core-shell structures. By taking the electrode materials in lithium ion batteries as an example, we demonstrated the importance of surface modification on the electrode materials. Different coating materials ranging from metal oxides, metal phosphates to carbon have been discussed. We also showed that an accurate control on the surface layer can be crucial for optimizing the electrochemical performances of the …

3, 4-Ethylenedioxythiophene Monomer As Safety-Enhancing Additive For Lithium Ion Batteries, Wei-Xiao Ji, Feng Wang, Jiang-Feng Qian, Yu-Liang Cao, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

Safety concern is a major obstacle hindering the wide applications of large-capacity lithium ion batteries (LIBs) in electric vehicles. In this paper, a polymerizable monomer of 3, 4-ethylenedioxythiophene (EDOT) was proposed and tested as an electrolyte additive for enhancing the safety of LIBs. The electro-oxidative polymerization behaviors and influence of PEDOT additive on the thermal behavior of LiCoO₂ cathode, as well as the safety performance and electrochemical properties of LiCoO₂-based LIBs were investigated. The results from cyclic voltammetry (CV) and transmission electron microscope (TEM) characterizations indicated that the monomer additive can be electro-oxidatively polymerized to form a …

Reduced Graphene Oxide (Rgo) Hollow Network Cages For High-Performance Electrochemical Energy Storage, Chi Zhang, Xu-Jun He, Gao-Ren Li

Journal of Electrochemistry

The reduced graphese oxide (RGO) hollow network cages were synthesized via zinc oxide (ZnO) template-assisted electrodeposition. The as-prepared RGO hollow network cages exhibited the multi-level architectures, from nano sheets, porous structures, networks, to 3D microscaled hollow cages, which can simultaneously optimize transport of electroactive species, utilization rate of electrode material, and super capacitive performance. Electrochemical measurements confirmed the superior performance of RGO hollow network cages for supercapacitors (SCs), such as high Csp (393 F⋅g^-1 at 1.0 A⋅g^-1), excellent rate capability (21.2% Csp loss from 1.0 to 20 A⋅g^-1), and superior cycling stability (< 1% Csp loss after 10000 cycles).

Electrochemiluminescence Immunosensor Based On Platinum Nanoparticles For The Determination Of Apolipoprotein A1, Ni Liao, Ying Zhuo, Ruo Yuan

Journal of Electrochemistry

In this paper, a novel electrochemiluminescence (ECL) immunosensor for the detection of apolipoprotein A1 was constructed based on flower-like platinum nanoparticles (PtNFs) via a one-pot chemical synthesis method. The PtNFs was used to immobilize the secondary antibody and enzyme (GOD). Then the prepared bioconjugates were introduced onto the electrode via sandwich immunoreactions. Accordingly, the ECL luminophore peroxydisulfate (S₂O₈^2-) was presented in the working buffer solution containing an appropriate amount of glucose. Through the ECL responses of S₂O₈^2- and O₂, a dramatically amplified ECL signal was obtained for the reason …