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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Applications of X-ray crystallography : studies into the structural perturbations of peri-substituted naphthalene derivatives

Fuller, Amy L. January 2010 (has links)
The majority of research in this thesis uses X-ray crystallography to investigate the structural features of peri-substituted naphthalene compounds. X-ray crystallography is introduced in chapter one, followed by a discussion on modes of distortion peri-substituted naphthalene derivatives can undergo, in chapter two. In chapter three, compounds having non-bonded -SPh and -EPh (E = S, Se, or Te) peri-substituents are compared. These similar compounds react differently when oxidized with bromine. The oxidation products are used to discuss a recently proposed mechanism and a more specific mechanism is suggested. In chapter four, a one-pot synthesis for naphtho[1,8-c,d]-1,2-diselenole (Se₂naph) is reported. Substituents were added to Se₂naph to form two new naphthalene compounds. The substituents are found to distort the Se-Se bond and influence packing. In chapter five, several diselenium-containing compounds are used as ligands in platinum(II)-bisdiphosphine complexes. The preference for platinum(II) to stay square planar dictates the geometry around the metal center, not the rigidity of the naphthalene backbone. Chapter six introduces (8-phenylsulfanylnaphth-1-yl)diphenylphosphine, a peri-substituted naphthalene containing -SPh and -PPh₂ substituents, and several derivatives. This ligand is used in a variety of complexes containing platinum(II), ruthenium(II), and copper(I) metal halides, whose coordination geometries are discussed in chapter 7. The naphthalene-based ligands in Cu(I) and Ru(II) seem to determine the geometry around the metal, whereas the metal center d-orbitals dominate in the Pt(II) examples. Chapters eight and nine deviate from the naphthalene theme. In chapter eight, X-ray analysis of sulfoxide compounds is used to discuss the structural environment around the sulfur. Various intra- and inter-molecular interactions were discovered in crystal packing. Finally, chapter 9 uses STANDARD (St ANDrews Automated Robotic Diffractometer) to statistically analyze numerous E₂Ph₂ (E = S, Se, or Te) crystals to determine chirality. It is intriguing that Te₂Ph₂ shows a preference for one enantiomer over the other.
62

Functional Neural Toxicity and Endocrine Responses in Mice Following Naphthalene Exposure

Colbert, Crystal 08 1900 (has links)
Polycyclic aromatic hydrocarbons (PAHs) are a well studied and diverse class of environmental toxicants. PAHs act via the aryl hydrocarbon receptor (AhR), and studies have suggested that PAHs may elicit neurological and estrogenic effects. Doses of PAHs between 50 to 150 ppm may elicit neurotoxicity in rodent models. The present study investigated the effects of naphthalene on in vivo steroidogenesis in Swiss Webster male mice, and in vitro neural function of Balb-C/ICR mice frontal cortex neurons. These data suggest that naphthalene may not elicit steroidogenic effects at concentrations ranging from 0.2 to 25 mg/kg/day, following a 7 day subcutaneous dosing regime. In addition, naphthalene may cause functional toxicity of frontal cortex neurons at concentrations of 32 to 160 ppm naphthalene.
63

Sorption of napththalene in soil, soil organic matter and polymers /

Pujari, Shilpa 01 January 2001 (has links) (PDF)
No description available.
64

Solubility of aromatic compounds in mixed solvents.

Morris, Kenneth Robert. January 1988 (has links)
The solubilities of benzene, naphthalene and anthracene were measured in five binary solvent systems. These systems consised of water and one of the following water miscible organic solvents: acetone, acetonitrile, methanol, ethanol, and isopropanol. The measurements were made at intervals of 0.1 volume fractions of the organic cosolvent. Solubility data were also collected for the above solutes in mixed cosolvents. solvent systems containing three In addition, the solubilities of and six five other aromatic solutes were measured in the binary solvent systems of methanol/water and acetone/water. The data was used to test the log-linear solubility model of Yalkowsky (1981). The model predicts a linear relationship between the solubility of a solute in a binary solvent system (S(m)) and the volume fraction of cosolvent present (f(c)) log S(m) = σf(c) + log S(w) Where S(w) is the solubility of the solute in water and σ is the proportionality constant and slope of the curve. The model is easily extended to multiple mixed solvents by combining the σ values from the binary solvent systems. log (S(m)/S(w)) = Σ₁ (σ₁£₁) A method was developed to estimate σ in a given binary solvent system from the octanol-water partition coefficient of the solute. Combining this method with the generalized solubility equation of Yalkowsky to estimate S(w), allows a priori estimates of solubility in mixed solvents. Maximum deviations in the binary solvent systems studied were related to maxima in excess density. In the alcoholic binary solvent systems the minima were related to minima in the heats of mixing of the two cosolvents. The herbicide atrazine deviated dramatically from the model. The system was examined for possible changes in the crystal structure of atrazine. It was found that some crystal modification occured in the presence of mixed solvents. The rate of the change appears to be dependant on the concentration of the cosolvent. A change or modification in the crystal violates one of the basic assumptions of the log-linear model. The assumption is that the crystal contributes equally to the solubility behavior irrespective of the solvent system. It was determined that atrazine undergoes a polymorphic transition in the systems studied. It is postulated that this polymorphism is responsible for the anomolous solubility behavior observed for atrazine.
65

Low cost aqueous batteries with organic electrode materials for renewable energy storage / Matériaux d'électrode organiques pour batterie aqueuse à bas coût pour le stockage des énergies renouvelables

Perticarari, Sofia 07 November 2018 (has links)
La gestion des sources renouvelables est probablement l'un des enjeux majeurs du 21ème siècle. La part croissante de ces ressources intermittentes et fluctuantes telles que les énergies solaires, éoliennes et marines connectées au réseau électrique requiert des systèmes de stockage efficaces pour sécuriser et réguler l'approvisionnement électrique. L'objectif principal de cette thèse est donc la création de batteries aqueuses écologiques et durables à base de matériaux organiques à faible coût. En particulier, ce projet avait pour but d’identifier des stratégies pour synthétiser, comprendre et modifier des matériaux redox idoines pour en optimiser les réactions électrochimiques et chimiques. De plus, cette technologie a nécessité une mise en oeuvre particulière de ces matériaux mettant en jeu des électrodes millimétriques jamais réalisées à ce jour. Une nouvelle famille de molécules redox de type p/n a été identifiée. Leur comportement électrochimique, rationalisés par de nombreuses caractérisations physiques, a mis en évidence l’échange simultané de cations et d’anions ce qui n’a jamais été montré dans le domaine des batteries. En outre ce matériau permet une cyclabilité remarquable notamment dans l’eau de mer. La synthèse et le comportement électrochimique de différents dérivés du TEMPO en tant que matériaux actifs d'électrode positive ont également été évalués. Sur la base de ces découvertes des résultats très encourageants ont été obtenus avec les batteries aqueuses organiques complètes composées d'électrodes millimétriques. / The management of renewable sources is probably one of the major issues of the 21st century. The increasing share of these intermittent and fluctuating sources such as solar, wind and marine energies connected to the electrical grid pushes towards the need for efficient storage systems to secure and regulate the supply of electricity. The main target of this thesis is therefore the creation of a low cost and sustainable full-organic aqueous cell. In particular, this project consisted in identifying strategies for synthesizing, understanding and modifying various organic redox materials to optimize their electrochemical and chemical behavior. In addition, the economic viability of this (new) technology required a particular implementation of organic materials according to industrially scalable processes, in millimeter thick electrodes ever made to date. As a result, a new p-/n-type redox active molecule and its electrochemical behavior in aqueous electrolyte has been presented. Further improvements have been achieved by modifying the previous compound into an oligomeric p-/n-type assembly which shows remarkable performance as cutting-edge negative electrode active material. This is the first redox material in the field of batteries able to exchange both anions and cations simultaneously. Extended cycling has been obtained in various electrolytes, including ocean water. The synthesis and the electrochemical behavior of different TEMPO derivatives as possible positive electrode active materials have been also evaluated. Finally, very encouraging results have been obtained by assembling full organic aqueous batteries composed of millimeter thick electrodes.
66

The Hydrolysis of Naphthalene Diimides

Kim, Michelle B 06 August 2007 (has links)
The hydrolyses of naphthalene diimides (NDIs) bearing aliphatic side chains with N-methylpyrrolidinium groups placed two (1) and three (5) atoms from the central core were studied. The Ka values for the first and second hydrolyses for 1 were 2.5 ± 0.2 x 105 M-1 and 2.0 ± 0.1 x 102 M-1, respectively; for 5 they were 1.4 ± 0.1 x 105 M-1 and 44 ± 2 M-1, respectively. NDI 1 hydrolyzed 6.8 times faster than did 5. The rates for the first and second hydrolyses of 1 at 100 mM hydroxide measured by stopped-flow were 17.0 ± 0.2 s-1 and 53.0 ± 0.1 x 10-2 s-1, respectively. NMR showed both the syn and anti isomers of the diamide species. Syntheses of other derivatives are reported. Overall, this study shows that the rate of hydrolysis of NDIs is increased when the cationic charge is moved closer to the NDI core.
67

Advances in DNA binding by threading polyintercalation

Smith, Amy Rhoden 24 February 2015 (has links)
Chemistry / Although molecules that bind DNA have the potential to modify gene expression, the reality of targeting DNA in a sequence-specific manner is still a problematic but worthwhile goal. The Iverson lab has been exploring DNA recognition through a motif known as threading polyintercalation based on connecting intercalating naphthalene diimide (NDI) units, which are molecules that insert themselves between DNA base pairs, together with peptide linkers. These polyintercalators interact with both DNA grooves by “threading” or winding through the DNA, like a snake might climb a ladder. Initially, two different bisintercalator modules with altered sequence specificities and different groove binding topologies were discovered and used to inspire the design of a hybrid NDI tetraintercalator. Surprisingly enough, this tetraintercalator bound sequence-specifically with a dissociation half-life of 16 days to its preferred 14 bp site, a record at the time it was reported for a synthetic DNA-binding molecule. The work reported here expands on the capabilities of this modular threading polyintercalation motif. Chapter 2 describes the ability of a new hybrid NDI tetraintercalator, where the bisintercalator modules are connected together in a different way compared to the previously studied tetraintercalator, to subtly discriminate between similar binding sites. Chapter 3 offers a structural understanding, through NMR analysis, for the sequence recognition abilities of this new tetraintercalator. Chapter 4 analyzes the binding abilities of an un-optimized NDI octaintercalator and proposes how to approach the second-generation design of longer polyintercalators. Chapter 5 describes the optimization of the originally designed NDI tetraintercalator by serially lengthening one of the linkers to produce a tetraintercalator with a 57 day dissociation half-life from its 14 bp sequence, a new record for a synthetic DNA-binding molecule. Using the optimized linker in the context of an NDI hexaintercalator allows for binding to a 22 bp designed site, a record for a synthetic non-nucleic acid molecule. Chapter 6 recounts a focused library screening to search for bisintercalators with new sequence specificities. These efforts have laid the groundwork to progress toward studies aimed at understanding how these molecules might function to prevent transcription in a sequence-dependent manner in vivo. / text
68

Development of a method to determine vapor pressure data of low volatile chemicals from a Knudsen effusion technique

Harshman, Andrew R 01 June 2007 (has links)
Vapor pressure data are vital to understanding impacts that substances, specifically pesticides, may exert on the environment. They enter into atmospheric deposition models for such chemicals which determine the fate and transport of these species in the environment. At normal application temperatures (i.e. room temperature) the vapor pressures of many of these chemicals are too low to be determined by conventional means. An isothermal Knudsen effusion technique was designed and developed in our laboratory for such measurements. The effusion mass as a function of time is measured in our technique using a thickness shear mode (TSM) acoustic wave sensor, which allows for extremely high (few nanograms) sensitivity. This sensitivity allows for much more rapid determination of low vapor pressures (10-1 to 10-5 Pa) than is possible by other Knudsen effusion techniques. Basing the effusion mass measurement on the TSM sensor as in our apparatus eliminates the typically seen dependence on vibration in conventional microbalance-based effusion techniques. Full design details of our apparatus and specifically the Knudsen cell, based on original equations derived by Knudsen, and many corrections that have been noted in the literature for cell and effusion-hole dimensions, are presented. The accuracy of our methodwas tested by a comparison of published vapor pressure data to vapor pressure data acquired in our laboratory with measurements on naphthalene and catechol.
69

Exploiting aromatic donor-acceptor recognition in the folding and binding of naphthyl oligomers

Gabriel, Gregory John 28 August 2008 (has links)
Not available / text
70

Evaluating Naphthalene Sorption to Cement-Based Solidification/Stabilization Additives

Searle, S. Jill 20 August 2010 (has links)
Solidification/Stabilization (S/S) is a low cost remedial technology that is being used with success to remediate sites that contain higher molecular weight organic compounds, leading to a need to research the interaction of organic contaminants with cement-based S/S materials. The objective of this study was to examine the sorption levels of naphthalene to cement-based S/S materials. Batch testing was performed with S/S materials containing different amounts of organic carbon to investigate the sorption of naphthalene. It was found that sorption values varied, but appear to be dependent on the organic carbon present. Dynamic leach test (ANS16.1 methodology) and SPLP analysis results are presented for intact cement-based S/S materials. Contaminant migration modeling was performed to use the information obtained in the study to compare the sorption capacity of cement-based S/S systems. It was shown that cement-based S/S remediation systems can provide long-term protection against naphthalene contaminant migration.

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