Analytical Chemistry Commons^™

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 …

Sol-Gel Resorcinarene Sorbent For Capillary Microextraction Coupled To Gas Chromatography, Abdullah Awadh Alhendal

USF Tampa Graduate Theses and Dissertations

For the first time, octahydroxyl methylresorcinarene with four hexyl groups on the lower rim was utilized in the in-situ preparation of a silica-based sol-gel organicinorganic hybrid coating for sample preconcentration by capillary microextraction (CME). Tetraethoxysilane (TEOS) was chosen as a sol-gel precursor to create a crosslinked sol-gel network via acid-catalyzed hydrolytic polycondensation reactions. Sol-gel chemistry helped in the in situ preparation of resorcinarene-containing extraction phase in the form of a surface coating. It also provided an effective means to chemically bind the coating to the inner surface of fused silica capillary via condensation of the hydroxyl groups in the sol-gel …

Analysis Of Gaba And Glutamate In The Mouse Dorsal Striatum, Stella Wisidagamage

Wayne State University Theses

ABSTRACT

ANALYSIS OF GABA AND GLUTAMATE IN MICE BRAIN

by

STELLA WISIDAGAMA

May 2011

Advisor: Dr. Tiffany Mathews

Major: Chemistry (Analytical)

Degree: Master of Science

GABA and glutamate are the predominant inhibitory and excitatory amino acid neurotransmitters in the central nervous system (CNS), respectively. However, their altered levels cause several neurological diseases including Parkinson's and Huntington's disease, schizophrenia, and epilepsy. It is important to measure their levels in the extra- and intracellular environments to better understand and develop improved therapeutics that will treat these neurological disorders. The principle aim of this study is to study the impacts of different endogenous …

Quality Characteristics Of Virgin Coconut Oil:Comparisons With Refined Coconut Oil, Fabian M. Dayrit, Ian Ken D. Dimzon, Melodina F. Valde, Jaclyn Elizabeth R. Santos, Mark Joseph Garrovillas, Blanca J. Villarino

Chemistry Faculty Publications

Virgin coconut oil (VCO) is a vegetable oil that is extracted from fresh coconut meat and is processed using only physical and other natural means. VCO was compared to refined, bleached, and deodorized coconut oil (RCO) using standard quality parameters, 31 P nuclear magnetic resonance (NMR) spectroscopy, and headspace solid-phase micro - extraction/gas chromatography mass spectrometry (SPME/GCMS). VCO tends to have higher free fatty acids (FFAs), moisture, and volatile matter and lower peroxide value than RCO. However, the range of values overlap and no single standard parameter alone can be 31 used to differentiate VCO from RCO. Using 31P NMR, …

Single Cell Analysis For The Characterization Of Cell Populations Using A Live Cell Array, Maureen Ann Walling

Legacy Theses & Dissertations (2009 - 2024)

In the past decade, the shift from whole cell population analyses towards single cell measurement methods and techniques is based on experimental results that reveal significant levels of non-genetic heterogeneity in clonal cell populations. This heterogeneity manifests in multiple aspects of cell activity and is, in part, a result of stochastic noise in processes leading to gene expression, namely transcription and translation. The growing understanding of this occurrence has led to the development of methods to monitor and analyze heterogeneity for a more thorough description of cell populations and overall activity.

Advanced Statistical Methods For Biochemical And Forensic Applications Of Raman Spectroscopy, Vitali Sikirzhytski

Legacy Theses & Dissertations (2009 - 2024)

This work is dedicated to the development and application of advanced statistical methods for biochemical and forensic applications of Raman spectroscopy. We developed a new concept of multidimensional Raman signatures for forensic identification of body fluid traces, which was successfully applied to the study of dried blood, semen, saliva, sweat and vaginal fluid stains. Several alternative advanced chemometric techniques were also successfully tested for the problems of pure body fluids discrimination and mixture analysis. Studies of body fluid mixtures with low blood and semen concentrations indicated that the detection limit of a minor contributor was as low as a few …

Identification And Characterization Of The Anti-Methicillin-Resistant Staphylococcus Aureus Wap-8294a2 Biosynthetic Gene Cluster From Lysobacter Enzymogenes Oh11, Wei Zhang, Yaoyao Li, Guoliang Qian, Yan Wang, Haotong Chen, Yue-Zhong Li, Fengquan Liu, Yuemao Shen, Liangcheng Du

Department of Chemistry: Faculty Publications

Lysobactor enzymogenes strain OH11 is an emerging biological control agent of fungal and bacterial diseases. We recently completed its genome sequence and found it contains a large number of gene clusters putatively responsible for the biosynthesis of nonribosomal peptides and polyketides, including the previously identified antifungal dihydromaltophilin (HSAF). One of the gene clusters contains two huge open reading frames, together encoding 12 modules of nonribosomal peptide synthetases (NRPS). Gene disruption of one of the NRPS led to the disappearance of a metabolite produced in the wild type and the elimination of its antibacterial activity. The metabolite and antibacterial activity were …

Accumulation, Speciation, And Distribution Of Metal(Loids) In Plants: Applications Of Synchrotron Techniques In Environmental Sciences, Hiram Castillo-Michel

Open Access Theses & Dissertations

In the last two decades, synchrotron based techniques have gained popularity and been increasingly used in environmental sciences. The present dissertation has relied significantly in the use of synchrotron based techniques to study the speciation, coordination, and distribution of toxic metal(loids) in plants. This study included three plant species: Parkinsonia florida, Prosopis juliflora, and Zea mays. P. florida is a plant species native to the semi-desert regions of North America. The cultivation characteristics of this shrub/tree suggest that it could be used for phytoremediation purposes in semiarid regions. P. florida plants were tested for their capacity to remove arsenic (As) …

High Resolution Hybrid Mass Spectrometry For The Determination Of Marine Biotoxins, Azaspiracids, And Their Biotransformation Products., Zuzana Skrabakova

Theses

Azaspiracids (AZAs), polyether marine toxins, are produced by marine microalgae and accumulate in filter-feeding bivalve molluscs, such as mussels, clams, oysters and scallops, while grazing on phytoplankton, from which they derive nutrition. Although being discovered quite recently, AZAs have caused several human intoxication events and thus became a problem for health authorities and shellfish industries. The rapid development of highly sensitive liquid chromatography multiple tandem mass spectrometry (LC-MS/MS, LC-MS") methods enabled the identification of numerous AZA analogues and added to the control of shellfish contamination. Tandem mass spectrometry techniques, while being highly selective and sensitive for determination of AZAs in …

Development, Validation And Application Of Uhplc-Ms/Ms Methods For The Detection Of Veterinary Drug Residues In Food Of Animal Origin, Michelle Whelan

Theses

Ultra high pressure liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-MS/MS) technology was utilized for the development of analytical methods for the detection of veterinary drug residues in foods of animal origin. Initial work focused on the development of the mass spectrometry (MS) method for the detection of the analytes of interest and subsequent chromatographic separation. The MS method was optimised to detect both positively and negatively ionised analytes from different classes in a single injection in a 13 minute run time at μg kg^-1levels.

Sample preparation procedures were modified to extract the residues from muscle and …

Quality Of Wastewater In The El Paso, Texas Region--Analysis Of Pharmaceuticals And Personal Care Products Using High Performance Liquid Chromatography Tandem Mass Spectrometry, Rodolfo Guerrero Jr.

Open Access Theses & Dissertations

Pharmaceuticals and Personal Care Products (PPCPs), such as household cleaning materials, prescription medication, and personal hygiene products, are pollutants of emerging concern that are found in 80% of our water system. Because of their applications, PPCPs are subsequently being released into wastewater; however, current wastewater treatment facilities are not regulated or designed to remove PPCPs. Therefore, these compounds are discharged into the environment on a continual basis. The effects of PPCPs on human health are not yet well known; however, recent research has found that exposure to these chemicals has some adverse developmental effects on aquatic species at low concentrations …

Non Aggregated Colloidal Silver Nanoparticles For Surface Enhanced Resonance Raman Spectroscopy, Aoife Power, John Cassidy, Tony Betts

Articles

Silver nanoparticles with a tuneable l max were produced as colloids by heterogeneous nucleation. The synthesis process is both fast and repeatable, producing stable PVA capped nanoparticles. The colloid’s effectiveness in the SERRS system was investigated using Rhodamine 6G, R6G, Crystal Violet, CV, and Malachite Green, MG, as probe molecules. A clear sensing trend was observed, where the Raman signal emitted was significantly enhanced by the addition of silver nanoparticles. A build up of signal intensity is observed until an optimum ratio is achieved, followed by a decline in signal intensity as the concentration of nanoparticles is further increased. The …

The Vinylguaiacol/Indole Or Vgi ("Veggie") Ratio: A Novel Molecular Parameter To Evaluate The Relative Contributions Of Terrestrial And Aquatic Organic Matter To Sediments., Michael A. Kruge, Kevin K. Olsen, Jaroslaw W. Slusarczyk, Elaine Gomez

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The organic matter (OM) fraction of estuarine sediments is often distinctive and thus diagnostically useful in determinations of sedimentary provenance. Among the most fundamental distinctions to be made is that between terrestrial and aquatic OM. To supplement the parameters commonly used for this purpose (e.g., C/N and stable isotope ratios), we proposed the Vinylguaiacol/Indole or VGI ("Veggie") ratio, defined as [vinylguaiacol / (indole + vinylguaiacol)] using data produced by analytical pyrolysis-gas chromatography/mass spectrometry of dried, homogenized sediment samples. The ratio employs the peak areas of these two compounds on the mass chromatograms of their molecular ions (m/z 150 and 117). …

Development And Validation Of A Rapid Multi-Class Method For The Confirmation Of Fourteen Prohibited Medicinal Additives In Pig And Poultry Compound Feed By Liquid Chromatography Tandem Mass Spectrometry, Mark Cronly, Patrice Behan, Barry Foley, Liam Regan, Marella Gallagher, Sean Earley, Paula Shearan, Edward Malone

Articles

A confirmatory method has been developed to allow for the analysis of fourteen prohibited medicinal additives in pig and poultry compound feed. These compounds are prohibited for use as feed additives although some are still authorised for use in medicated feed. Feed samples are extracted by acetonitrile with addition of sodium sulphate. The extracts undergo a hexane wash to aid with sample purification. The extracts are then evaporated to dryness and reconstituted in initial mobile phase. The samples undergo an ultracentrifugation step prior to injection onto the LC-MS/MS system and are analysed in a run time of 26 minutes. The …

Ultrasonic Activation Of Triacetone Triperoxide, Latravia R. Dobson

Department of Chemistry: Dissertations, Theses, and Student Research

Triacetone triperoxide (TATP) is an organic peroxide that has received widespread attention in recent years. TATP is a ketone peroxide with a high active oxygen content. It is relatively shock sensitive, with explosive decomposition easily initiated, and is therefore considered a primary explosive. However, TATP is also a powerful explosive possessing about 83 % of the power of TNT. TATP can be prepared quickly and easily from inexpensive household chemicals in the absence of any specialized facilities, making it the explosive of choice for modern day terrorists. TATP poses a major challenge for security and law enforcement services around the …

Chemical And Electronic Structure Of Surfaces And Interfaces In Compound Semiconductors, Sujitra Pookpanratana

UNLV Theses, Dissertations, Professional Papers, and Capstones

The interface formation between two different materials is important in applications for optoelectronic devices. Often, the success or performance of these devices is dependent on the formation of these heterojunctions. In this work, the surface and interfaces in such materials for optoelectronic devices are investigated by a suite of X-ray analytical techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), and X-ray emission (XES) spectroscopies to provide novel insight.

For the group III-nitrides (e.g., AlxGa1-xN) used in many light emitting devices, a significant challenge exists to form an Ohmic contact. The electron affinities and band gaps of GaN and …

Redox-Magnetohydrodynamic (Mhd) Microfluidics: Fundamentals, Optimization, And Applications To Analytical Chemistry, Melissa Christine Weston

Graduate Theses and Dissertations

Microfluidic systems are of great interest in analytical chemistry for the development of lab-on-a-chip devices. This dissertation describes fundamental investigations of magnetohydrodynamics with added redox species (redox-MHD) as a new microfluidic approach for use in analytical applications. Redox-MHD is attractive because it offers a unique combination of desirable features that are otherwise only available separately with individual micropumps. Redox-MHD is compatible with aqueous and nonaqueous solutions, does not require moving parts, easily reverses flow direction, and requires only low voltages. An ion flux is generated from the oxidation or reduction of an electroactive species at specific locations by activated electrodes …

Electrochemical Detection For The Corrosion Of Reinforcing Steel In Concrete During Immersion And Drying Cycles, Bing-Li Jia, Fa-He Cao, An-Na Chen, Jian-Qing Zhang

Journal of Electrochemistry

The corrosion behavior of reinforcing steel in concrete under dry-wet cycle condition has been studied by electrochemical noise(EN) compared with the electrochemical impedance spectroscopy(EIS),SEM micrographs and EDS.The statistical method has been employed to analyze the EN data of reinforcing steel in concrete,which revealed three different corrosion stages of reinforcing steel in concrete,including the dissolution of the passive film,the active corrosion and the cumulation of corrosion product.The wavelet transform has also been employed,which indicated that steel in concrete with pH 1 is associated with uniform corrosion,while steel in concrete with pH 3 and pH 7 are associated with localized corrosion,such as …

Jahn-Teller Coupling And Fragmentation After Core-Shell Excitation Ini Cf4 Investigated By Partial-Ion-Yield Spectroscopy, Renaud Guillemin, Wayne C. Stolte, Maria Novella Piancastelli, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

We investigate fragmentation processes induced by core-level photoexcitation in CF4 at both the carbon and fluorine K edges by means of partial-ion-yield spectroscopy. The molecule CF₄ is a textbook example of systems in which Jahn-Teller coupling strongly manifests itself in the photoabsorption spectrum. Spectral features related to Jahn-Teller and quasi-Jahn-Teller splitting are observed, and important differences in the fragmentation pathways are revealed depending on the symmetries of the core-excited states. We interpret these experimental observations on the grounds of symmetry lowering from the Td to the C3v point group as well as preferential orientation with respect …

Solvent Effects On Emission Spectra Of Carminic Acid And Determination Of Its Ground And Excited State Dipole Moments, Sarika B. Jaggannagari

All Capstone Projects

Absorption and fluorescence emission spectra of Carminic acid were recorded in solvents with different solvent parameters like polarities, dielectric constant and refractive index. The solvents used in the experiment were water, DMSO, acetonitrile, methanol, propanol and butanol. The atomic radius of the molecule was found out using Hartree-Fock method in molecular modeling using Spartan software and it is applied to find out the dipole moments. The dipole moments of Carminic acid in the ground state and excited states have been determined and Solvatochromic shift method has been used to determine the excited state dipole moments. The linear progressions were made …