Asphaltenes correspond to the fraction of oil that is insoluble in heptane but is soluble in toluene. The aggregates of asphaltene are of interest because they cause serious problems in the production of oil. Asphaltenes contain fluorescent moieties, and as such they can be studied by fluorescence techniques. The first objective of this work was to develop methodologies to study the fluorescence of asphaltenes, and to investigate the fluorescence of asphaltenes at various concentrations. Time-resolved fluorescence studies indicate that asphaltenes have different chromophores with different lifetimes. The average lifetime of the asphaltene emission decreased when the asphaltene concentration was increased because of quenching processes occurring within the aggregates. The measurement of lifetimes at different excitation and emission wavelengths demonstrated that different components of asphaltene aggregate at different concentrations. The second objective of this work was to investigate how accessible the asphaltene aggregate is to small molecules by fluorescence quenching experiments. Nitromethane was the quencher used in the fluorescence of asphaltenes. The quenching efficiencies were found to be independent of the concentration of asphaltenes. However, the quenching efficiencies differed for different chromophores, suggesting a selective quenching for nitromethane of the excited states for the different chromophores of asphaltenes. The third objective of this thesis was to investigate the fluorescence of externally added probes that might be incorporated in asphaltene aggregates through π−π stacking. Pyrene was chosen as the probe because its fluorescence properties are strongly affected by its surroundings. The pyrene emission was quenched by nitromethane. The quenching efficiencies determined for pyrene in the absence or the presence of asphaltene aggregates were the same. This suggests that pyrene is located in an open environment, where the asphaltene aggregates do not offer any protection for pyrene from nitromethane. / Graduate

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

No description available.

The luminescence properties of Van Der Waals' dimers and clusters of pyrene and diazapyrene have been investigated. Excimers, dimeric species which are associative in an excited electronic state and dissociative in their ground state, have long been established and play an important role in many areas of photochemistry. My work here focuses on the luminescence and absorption properties of ground state dimers/aggregates, which are less understood, and allows further characterization of the ground state and excited state association of these aromatic molecules.

Understanding the thermodynamic properties of multicomponent mixtures is of critical importance in many chemical and industrial applications. Experimental measurements become progressively difficult as the number of solution components increases -- producing the need for predictive models. Problems in development of predictive models arise if the mixture has one or more components that interact through molecular complexation or association. Experimental solubilities of anthracene and pyrene dissolved in binary systems containing one or more alcohols were measured in order to address this problem. Alcohols examined in this study were: 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 3-methyl-1-butanol, and 1-octanol. In binary solvent mixtures containing only a single self-associating alcoholic solvent, the alkane cosolvents studied were: n-hexane, n-heptane, n-octane, 2,2,4-trimethylpentane, cyclohexane, methylcyclohexane, tert-butylcyclohexane. Predictive solubility equations were developed using mobile order theory. This approach differs from classical solution models by representing hydrogen bonding with a probability term rather than with expressions derived from stepwise equilibria or expressions to represent hypothetical solution aggregates. Results were compared with the predicted solubilities found from using expressions developed using the Kretschmer-Wiebe and Mecke-Kempter approaches for modeling associated solutions. It was found that the mobile order approach provided reasonably accurate predictions for the solute solubilities in the systems studied. The limitations and applications for mathematical methods of representing experimental isothermal solubility data were also studied for 72 systems. Two possible descriptive forms for this mathematical representation were suggested based on the various nearly ideal binary solvent (NIBS) and modified Wilson models.

Abstract Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic organic pollutants. Because of their highly hydrophobic property, PAHs easily absorbed by organic matters. They also display highly biological accumulation ability and toxicity. PAHs can interrupt organism¡¦s endocrine systems and some are considered bearing mutagenic or carcinogenic potentialities. Because of industrialigation, the extent of accumulated PAHs in the environment at present is significantly higher than those in the past. Therefore, while it is best to avoid further producing of these compounds if at all feasible; efforts to limit the introduction of these compounds into the environment by treating point pollution sources should always be made. The traditional approach to treat organic pollutants, including PAHs, in wastewater is mainly microbial based degradation. But recently due to its low cost and relatively high efficiency, treatment using aquatic plants combined with microbial degradation became popular. However, there have not much work done in using aquatic plant alone to treat PAHs. To study the sorption of PAHs by aquatic plant can provide information regarding the role of plant and microbial actions, and to enable such bioremediation technology more flexibile and feasible in application. Therefore, the forcus of this research is using plant solely to remove PAHs in a man-made wastewater. In this study, an aquatic plant, Ceratophyllum demersum, was used to sorb phenanthrene (Phe) with a continuous flow device. The competition effect in sorption by another PAHs, pyrene (Pyr), was also studied. In addition, another aquatic plant, Naja gramunea Del., was tested using the same system. In the batch experiment, the sorption kinetic constants of phenanthrene and pyrene for Ceratophyllum demersum are 0.19 and 0.22, respectively. Compared with Ceratophyllum demersum, Naja gramunea Del. has a higher kinetic constant. The sorption equilibrium constants of phenanthrene and pyrene for Ceratophyllum demersum are 1.36 and 19.24, respectively. Compared with Naja gramunea Del., Ceratophyllum demersum has a higher equilibrium constant for phenanthrene, but with a lower equilibrium constant for pyrene. A competition effect was observed by the delayed phenanthrene¡¦s saturation time by using pyrene as the possible background pollutant in the continuous flow system. Naja gramunea Del. was also applied in the same system for treating phenanthrene and pyrene in the same way. In conclusion, these two aquatic plants demonstrated great potentials in applications used for treating wastewaters containing PAHs due to low energy and cost of the device.

In this study,we used mangrove phytoremediation ecotechniques to treat polycyclic aromtic hydrocarbons (pyrene) contaminated soil. First, we compared the four species of mangroves in Taiwan, Kandelia candel Druce, Rhizophora stylosa Griff, Avicennia marina Vierh and Lumnitzera racemosa Willd, inoculated by endomycorrhizae in no contaminated soils. According to the experimental results, the four species of mangroves could be colonized by Glomus aggregatum and Glomus mosseae. In colonization rate and colonization intensity, Glomus aggregatum were found higher than those of Glomus mosseae. For the degradation efficiencies of pyrene in soils, according to the experimental results, we found that the Lumnitzera racemosa Willd exhibited best growing conditions among the four species. The degradation rates for all tests systems pyrene were measured above 90% . In accordance with passed study, the species of Kandelia candel Druce presented effective efficiencics for pyrene degradation. The speacis of Lumnitzera racemosa Willd and Kandelia candel Druce were planted in the artifical pyrene contaminated soils, which were incubated in a greenhouse , while the control systems without vegetation were used for comparison. After 90 days of incubation, the experimental result showed that the soils planted with Lumnitzera racemosa Willd and Kandelia candel Druce were found able to enhance the microbial and dehydrogenase activities. The addition of Glomus aggregatum could help plants to prevent from the stress of pyrene. The addition of salinity into the siols was a pressure for mangroves so the mangroves, incoculated by endomycorrhizae showed stronger dependence on mycorrhizal fungi than those in the siols of no salinity. In salty siol, mangroves exhibited high effective degradation rates for pyrene. In the siols for the illumination groups, the pyrene degradation rates for all test systems were measured about 85%. The siols for the dark groups showed that the average pyrene degradation rates were about 70%.

Thesis (M.S.)--University of North Texas, Aug., 2007. / Title from title page display. Includes bibliographical references.

The Digitization Centre has determined that pages x, 30 and 106 are not in this thesis or the vault copy. / Pyrenebutylamide-labeled poly(N-isopropylacrylamide-co-N-acryloyl-L-valine) copolymers have been prepared by two different methods and their physicochemical properties have been compared. One sample was prepared via copolymerization of N-isopropylacrylamide (NIPAM), and N-acryloyl-valine (NAV) with N-[4-(1-pyrenyl)butylacrylamide], the other by post-modification of poly(N-isopropylacrylamide-co-N-acryloyl-L-valine-co-N-acryloxysuccinimide) copolymer with pyrenebutylamine hydrochloride. The polymers were characterized by 1H NMR and FTIR spectroscopy, Differential scanning calorimetry and light Scattering. Though the use of fluorescence spectroscopy several differences between the two types of copolymers were detected. By comparing the extent of pyrene excimer emission and pyrene monomer emission from solutions of the two polymers, it was concluded that the copolymer obtained by direct copolymerization (method 1) had an inherent ''blocky" microstructure, while the copolymers obtained by the post-modification route presented a more random microstructure. Intrapolymeric interaction exists in solutions of low copolymer concentrations. At higher concentrations both inter-and intrapolymeric interactions coexist. The presence of a number carboxylic groups in the PNIP AM chain significantly modifies the conformation properties of the copolymers, compared to poly(N-isopropylacrylamide). The copolymers contract and expand in response to external conditions such as pH and temperature. Their Lower critical solution temperature (LCST) changes with pH. The interactions between polymers and fluorescence quenchers were investigated. The quenching results reveal that hydrophilic cationic quenchers interact strongly with the randomly labeled-copolymer. Hydrophobic cationic species interact strongly with ''blocky" pyrene labeled copolymer. Anionic quencher interacts quite weakly with both copolymers owing to electrostatic repulsion. / Thesis / Master of Science (MS)

Using the technology afforded by Winschel et al., cyclen-1, a high affinity, strong complexation agent for 8-hydroxypyrene-1,3,6 trisulfonate and derivatives, a new assay has been developed for fluorescently labeling proteins of interest (POIs). Ligation of the endogenous ligand for nicotinic acetylcholine receptors (nAChRs), acetylcholine, using click chemistry afforded the triazole derivative of an alkynyl-acylcholine (compound 1) with 8-azidopyrene-1,3,6 trisulfonate (compound 2). Liposomes encapsulated with Rhodamine B were used to strengthen the initial fluorophore response of compound 2, using an anchored form of cyclen-1 complex. Using a palmitoyl tail as the lipophilic moiety for liposomal amplification, the subsequent response has a fluorophore ratio of up to 1:1 million, compound 2:Rhodamine B molecules. in vitro assay using compound 2 and cyclen-1 anchored liposomes with HEK-293 cells produced a positive binding response, allowing brightly colored fluorescent images of nAChRs upon the cellular membrane. A control for nAChR binding was performed using a co-culture of HEK-293 and endothelial cell lines. Control experiments show compound 2 and liposomes weak binding endothelial cells, however, this could be do to accumulation from another mechanism, more work is necessary to prove whether or not this is correct.