Dissertations / Theses on the topic 'Chemicals'
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ATZORI, LUCIANO. "Chemical Recycling of Carbon Dioxide to Chemicals and Fuels." Doctoral thesis, Università degli Studi di Cagliari, 2018. http://hdl.handle.net/11584/255982.
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The increasing attention toward climate change is promoting research in the development of suitable strategies for CO2 emissions mitigation. Among these, Carbon Capture and Utilisation strategies (CCUs) appear as the most promising, as they permit to reduce the carbon dioxide emitted in atmosphere, at the same time satisfying the requirements for a sustainable development. Currently, the amount of carbon dioxide consumed in chemical recycling processes represents a very small fraction of the total emissions, thus a net increase in CO2 exploitation through the development of efficient processes and catalysts is required.
In this context, the present work deals with the study of different processes aiming to convert CO2 into cyclic carbonates, methane, and methanol, which can cover a very important role in terms of CCUs impact. For each process, suitable heterogeneous catalysts were prepared and extensively characterised by means of different experimental techniques.
Cyclic carbonates synthesis through CO2 reaction with epoxides was studied by using imidazolium-based catalysts prepared by means of a one-pot immobilisation procedure over Al_SBA-15 supports having different Si/Al molar ratios. All the catalysts were found highly active in the conversion of both epichlorohydrin and styrene oxide under different reaction conditions. Unlike styrene oxide, epichlorohydrin was found to favour the detachment of the imidazolium moieties more weakly bonded to the surface supports; however, leaching phenomena were observed to occur only during the first catalytic run, highlighting that the prepared materials can be successfully used in multiple catalytic cycles.
NiO/CeO2 mixed oxides prepared through two unconventional synthesis procedures were tested for the CO2 hydrogenation to methane under different reaction conditions. A first series was prepared through the “Hard-Template” method, while the second one was obtained by means of the “Soft-Template” strategy. All the prepared materials were found very active and selective toward methanation. The pivotal role of ceria both as promoter and active component was clearly observed; in fact, besides to improve the reducibility and the dispersion of NiO species, ceria is also responsible for the activation of CO2 through the formation of oxygenated intermediates. In addition, the presence of strong Ni-Ce interactions was found to be crucial in ensuring a high catalytic performance also in unfavourable reaction conditions.
CO2 hydrogenation to methanol was studied on two different series of Cu-based catalysts, prepared from hydrotalcitic precursors or by the “Soft-Template” approach. The influence of different supports and promoters such as ZnO, Al2O3, ZrO2, and CeO2 on the catalytic performance was investigated. Promising catalytic results were observed by using the catalysts prepared from hydrotalcitic precursors. ZrO2 and CeO2 were found to increase CO2 conversion and CH3OH selectivity, respectively, suggesting that beneficial effects could be obtained by optimizing their concentration. The catalytic results observed by using the Soft-Templated Cu-based samples confirmed the crucial role of ZnO, whose efficient interaction with Cu is needed in order to get high catalytic performances.
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Ekaireb, Sally Elizabeth. "Dispersion of chemicals and reactions of dispersed chemicals." Thesis, City University London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254963.
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Johal, Amrit. "Chemicals from lignin." Thesis, University of Nottingham, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716671.
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This Thesis investigates the production of high-value chemicals, such as vanillin and guaiacol, by the decomposition and oxidation of lignin in high temperature water. Currently, there is significant global interest in developing chemical production methods that utilise biorenewable feedstocks in place of crude oil and natural gas. Lignin, a complex set of biopolymers found in wood, straw and similar plant materials, is a viable biorenewable raw material for the production of aromatic chemicals. However, currently lignin is mostly used as a low-value fuel in pulp mills. Chapter 1 highlights the concerns that have led to the current demand for greater utilisation of biomass. In that respect, the potential uses of lignin are described. Supercritical water is discussed in relation to green chemistry and specifically as a medium for carrying out oxidation reactions on methyl aromatics. The equipment and methodology used for carrying out experiments and the instruments used for product analysis are described in Chapter 2. Preliminary work that was carried out is described in Chapter 3. These experiments look at the stabilities and oxidation of monomeric aromatic aldehydes, acids and phenols in high temperature water. These substrates each contained either a p-hydroxyphenyl, guaiacyl or syringyl unit. The work in Chapter 4 examined the use of metal bromides and hydrobromic acid as catalysts in the oxidation of three lignin model compounds; 2-methoxy-4-methylphenol, 4-ethyl-2-methoxyphenol and eugenol. These reactions were performed in the near-critical to supercritical region of water. Lignin samples from both Kraft pulping and sulfite pulping sources were shown to breakdown to vanillin, vanillic acid and guaiacol through oxidative treatment in a high temperature water continuous-flow reactor. This work is described in Chapter 5. The overall conclusions of this Thesis are summarised in Chapter 6.
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Mustarichie, Resmi. "Chemicals from biomass." Thesis, Mustarichie, Resmi (1986) Chemicals from biomass. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/51172/.
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Agricultural and forest residues as well as urban waste derived from forest products contain significant amounts of cellulose which could be converted into ethanol, a liquid fuel. To realize this potential it is necessary to hydrolyze the cellulose-bearing materials to sugars.
The present state of knowledge of the biomass conversion and structure and its hydrolysis was reviewed. A detailed study of the gaseous hydrogen chloride hydrolysis was made to examine the possibility of producing ethanol from biomass with a simple process. Such information using jarrah (Eucalyptus marginata), pine (Pinus radiata), and wheat (Triticum vulgare var. Egret) straw as typical substrates provided worthwile data relating to Australian conditions and led to a better understanding of biomass hydrolysis. Under optimum conditions a sugar yield of 92% of theoretical was achieved from whole biomass without pretreatment.
A model was developed to describe the hydrogen chloride-wood reaction process which consists of three consecutive major steps: (a) precooling involving adsorption of gaseous hydrogen chloride, (b) the main hydrolysis, and (c) completion of the reaction by posthydrolysis. Conditions and associated problems of each temperature controlled step were fully investigated. Thermodynamic calculations concerning heating temperature and mass balance calculations were The made. effect of pretreatments on the hydrolysis was studied. Infrared spectroscopic as well as electron microscopic methods were used to understand the process.
Biomass analysis was fully studied with the result that considerable improvements were made in the procedures for analyzing cellulose. hemicellulose, and lignin and for analyzing the hydrolysis and degradation products from those polysaccharides. It is proposed, for example, that saturated hydrogen chloride replace the usual 72 % sulphuric acid in the standard cellulose analysis procedure.
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Bailey, Trevor. "Chemical management in research laboratories : South-Eastern Australia, 1997." Thesis, Federation University Australia, 1997. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/164876.
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"Through a comprehensive literature review this project examines the necessary components of a laboratory chemical safety program, including requirements under the new hazardous substance regulations. It also examines, via a survey, the problems associated with the laboratory use of chemicals and with compliance with the new regulations. Finally the current situation in Australia and the approach research laboratories must take in the future to achieve compliance with the new regulatory package are reviewed."Master of Applied Science
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Cunningham, William. "Catalytic conversion of terpene feedstocks into value-added chemicals and commodity chemicals." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760985.
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There is currently much interest in developing biorenewable alternatives to the multitude of bulk and fine chemicals required by a modern society that are currently sourced from non-renewable petroleum sources. However many of the biomass sources that have been considered as replacement chemical feedstocks for oil such as cellulosic materials or fatty acids are highly oxygenated and are not well suited to constructing the aromatic rings present in many drug molecules. Terpenes, on the other hand, are an abundant class of biomass derived hydrocarbons that are deoxygenated and amenable to aromatisation. Monoterpenes in particular can be easily separated from aqueous environments and can potentially be upgraded into a range of commodity, fine chemicals and drug molecules; complimenting the other biomass chemical sources. Epoxidation is an especially useful transformation for the formation of important intermediates in the synthesis of fine and bulk chemicals such as pharmaceuticals and polymers. We have optimized a selective, solvent free epoxidation process based upon a tungsten polyoxometalate catalyst that works for a broad range of commonly available terpenes, including crude sulphate turpentine, having expanded its scope and developed an optimal protocol that enables epoxidation in shorter reaction times, with fewer additives, at milder temperatures and without the need for undesirable solvents compared to previous epoxidation protocols. We have also investigated various other catalytic methods to selectively epoxidize the other alkene substitution patterns present in a wide variety of terpene substrates that enables access to a number of key terpene bis-epoxides and this is discussed in chapter 2.We have also combined the optimal catalytic protocol with flow engineering, to develop a sustainable, catalytic flow epoxidation protocol that is suitable for both laboratory and industrial scale synthesis of biomass derived terpene epoxides. In particular, targeting the replacement of stoichiometric and expensive reagents and environmentally polluting solvents with green H2O2 and solvent free conditions and this is discussed in chapter 3.This catalytic epoxidation protocol was then adapted to enable the sustainable production of terpene and non-terpenoid anti-diols without the need for toxic co-solvents, corrosive acid or time consuming neutralisation steps. These anti-diol substrates are promising monomers for polymerisation and have other important applications such and this is discussed in chapter 4.Chapter 5 discusses the development of synthetic routes to sustainable paracetamol via the pharmaceutical intermediate 4-hydroxyacetophenone that is economically comparable with current petrochemical routes. Chapter 6 discusses the development of a number of selective synthetic routes to a number of isomers of the mosquito repellent, p-menthane-3,8-diol, with a novel all-cis isomer, made with excellent selectivity, that has the potential to have enhanced repellent properties. Ultimately, this PhD concerns the development of protocols for the conversion of terpene feedstocks into value-added chemicals that will be used as precursors for the synthesis of commodity drug targets such as paracetamol (pain relief); for the synthesis of renewable polymer epoxide and diol monomers and for the synthesis of biologically active molecules such as p-menthane-3,8-diol (insect repellent).
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Mathews, Karen Lesley. "The Chemical and Cellular Basis of Allergic Reactions to Drugs and Chemicals." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507509.
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Carway, Eugene Vincent. "Toxic chemical syndrome: body burden and immune parameters affected by environmental chemicals." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc332749/.
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The purpose of the present study was to determine: (1) that dental office personnel would be exposed to more toxic chemicals in the workplace than the non-dental office controls; (2) that exposure should lead to a reduction in the efficiency of the immune system in the individuals in the dental office; and (3) the immunological deficit should manifest itself in psychological and/or physiological pathology as measured on the Profile of Mood States (POMS) and Bender Gestalt.
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Bian, Junxing. "Skin permeation enhancement using chemical enhancers and polymeric microneedles for chemicals and peptides." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23624.
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It is often a challenge to effectively deliver drugs through the skin into the internal environment. Compared with oral administration and other dosage forms, transdermal administration has multiple advantages. Among the various transdermal administration approaches, microneedles emerge as a powerful tool in recent years, owing to its simple concept and proven efficacy. In this project, we aim to develop a hot-embossing method using menthol as the carrier material to fabricate drug-laden microneedle patches. We compared the transdermal delivery of several drugs with different dosage forms and tried to enhance their transdermal absorption by chemical and physical enhancers including this menthol-based microneedle method. It is hypothesized that this approach can be used for chemicals with various properties to enhance their percutaneous absorption. For chemical drugs, we studied the transdermal absorption of cromolyn sodium in propylene glycol (PG) and the transdermal absorption of diclofenac diethylamine gels. For peptides, we studied an anti-pigmentation peptide with strong polarity, which has extremely low skin permeation. We esterified the peptide molecule to increase its lipophilicity for skin permeation. Following esterification, we studied the transdermal absorption of the peptide and its derivative in PG with chemical penetration enhancers. Apart from chemical permeation enhancement, we also used dissolving microneedles (MNs) as the physical method to enhance transdermal delivery of the chemicals and peptides. The transdermal experiments were carried out by using vertical Franz diffusion cells and cadaverous human skin samples. The results showed that in PG solution, the cumulative permeated amount of hydrophilic cromolyn sodium was very limited. In contrast, the lipophilic diclofenac showed much higher skin permeation than cromolyn sodium. For the native peptide in PG with or without permeation enhancers, the skin permeation was not detectable. However, after molecular modification, due to the enhancement of lipophilicity of peptide, its skin absorption was improved. Two penetration enhancers, namely oleic acid and camphor did not enhance the transdermal absorption of the esterified peptide while another chemical enhancer, namely, menthol, increased the skin absorption of the esterified peptide. For the physical enhancement, drug laden MN patches increased the skin permeation of all four permeants.
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Zhang, Jin. "In silico Identification of Thyroid Disrupting Chemicals : among industrial chemicals and household dust contaminants." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-125631.
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Thyroid disruptions by xenobiotics have been associated with a broad spectrum of severe adverse human health effects, such as impaired brain development and metabolic syndrome. Ingestion of indoor dust and contact with industrial chemicals are two significant human exposure routes of thyroid hormone disrupting chemicals (THDCs), raising serious concerns for human health. However, it is a laborious and costly process to identify THDCs using conventional experimental methods, due to the number of chemicals in commerce and the varieties of potential disruption mechanisms. In this thesis, we are aimed at in silico identification of novel THDCs targeting transthyretin (TTR) and thyroid hormone receptor (THR) among dust contaminants and commonly used industrial chemicals. In vitro assays were used to validate the in silico prediction results. Co-crystallization and molecular dynamics (MD) simulations were applied to reveal binding modes of THDCs at the studied biological targets and to explain their intermolecular recognition. The main findings presented in this thesis are: 1. Over 144 environmental pollutants have been confirmed as TTR-binders in vitro and these cover a wide range of environmental pollutants and show distinct chemical profiles including a large group of halogenated aromatic compounds and a second group of per- and polyfluoroalkyl substances. (Paper I) 2. In total 485 organic contaminants have been reported to be detected in household dust. The developed QSAR classification model predicted 7.6% of these dust contaminants and 53.1% of their metabolites as potential TTR-binders, which emphasizes the importance of metabolic bioactivation. After in vitro validation, four novel TTR binders with IC50 ≤ 10 µM were identified, i.e. perfluoroheptanesulfonic acid, 2,4,2',4'-tetrahydroxybenzophenone (BP2), 2,4,5-trichlorophenoxyacetic acid, and 3,5,6-trichloro-2-pyridinol. (Paper II) 3. The development of a robust structure-based virtual screening (VS) protocol resulted in the prediction of 31 dust contaminants as potential binders to THRβ1 including musk compounds, PFASs, and bisphenol A derivatives. The in vitro experiments confirmed four compounds as weak binders to THRβ1, i.e. 2,4,5-trichlorophenoxyacetic acid, bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) ether, 2,4,2',4'-tetrahydroxybenzophenone, and 2,4-dichlorophenoxyacetic acid. (Paper III) 4. We revealed the binding conformations of perfluorooctanesulfonic acid, perfluorooctanoic acid, and BP2 in the thyroxine binding sites (TBSs) of TTR by co-crystallizing TTR with the three compounds. A VS protocol was developed based on the TTR complex structures that predicted 192 industrial chemicals as potential binders to TTR. Seven novel TTR binders were confirmed by in vitro experiments including clonixin, 2,6-dinitro-p-cresol (DNPC), triclopyr, fluroxypyr, bisphenol S, picloram, and mesotrione. We further co-crystallized TTR with PBS, clonixin, DNPC, and triclopyr, and their complex structures showed that the compounds bind in the TBSs as proposed by the VS protocol. In summary, 13 indoor dust contaminants and industrial chemicals were identified as THDCs using a combination of in silico and in vitro approaches. To the best of our knowledge, none of these compounds has previously been reported to bind to TTR or THR. The identifications of these THDCs improve our understanding on the structure-activity relationships of THDCs. The crystal structures of TTR-THDC complexes and the information on THDC-Target intermolecular interactions provide a better understanding on the mechanism-of-actions behind thyroid disruption. The dataset compiled and in silico methods developed serve as a basis for identification of more diverse THDCs in the future and a tool for guiding de novo design of safer replacements.
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Alessio, Caretto. "Green transformations of bio-based chemicals." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12727.
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The thesis was focused on the development of green chemical technologies for the upgrading of platform molecules obtainable from renewable feedstocks. The platforms were chosen among those considered as the most promising for the development a new, sustainable, chemical industry. Levulinic acid was converted into compounds with a higher degree of oxygenation without actually using oxidizing agents. This was achieved by using dimehtyl carbonate (DMC), a green reagent and solvent, in basic catalysis. Bio-derived lactones (γ-valero-, γ-butyro-, δ-valero- and ε-capro-lactone) were reacted with three dialkylcarbonates (DMC, diethyl- and dibenzylcarbonate) to yield α-alkylated derivatives (from the 5-membered rings) or the highly oxygenated acyclic monomeric derivatives (from 6- and 7-membered rings). γ-valerolactone was used as a model to study acid catalysed ring-opening reactions. A novel reactivity was discovered in the presence of DMC; a mechanism was proposed. The 4-methoxy pentanoyl moiety was thus accessible by a green route. The reaction was then extended to a continuous flow process with solid acid catalysts. The selectivity towards the mentioned moiety or methyl pentenoate was tuned by optimising the parameters. Bio-derived diols were efficiently upgraded using organic carbonates in tandem with ionic liquids as organocatalysts. The study investigated the parameters that control the selectivity towards cyclic- or linear di-carbonates. The derivatisation of fatty acids methyl esters in conditions of on-water catalysis was investigated, aiming to develop a green strategy to reduce the cloud point of biodiesels. A new branched additive was synthesised, the thermal characteristics of which were analysed. The effect of reagents structure on on-water catalysis was investigated. The model reactions between cyclopentadiene and alkyl vinyl ketones allowed to demonstrate that little increases of the alkyl chain of a reactant have a dramatic influence on the catalytic effect.
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Fung, Ka Yip. "Process development of specialty chemicals /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CENG%202006%20FUNG.
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Colquhoun, K. O. "Microbial degradation of xenobiotics chemicals." Thesis, Nottingham Trent University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383652.
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Mohd, Ghazi Tinia Idaty. "Heterogeneous photocatalysis for chemicals manufacture." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614672.
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Simner, Janni. "Shocking Plants Produces Useful Chemicals." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/622090.
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de, Albuquerque Fragoso Danielle Munick. "Lignin conversion to fine chemicals." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30847/.
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The large availability of Kraft lignin as an industrial by-product and its polyaromatic characteristic, is ideal to consider the potential for recycling it into fine chemicals. To depolymerise lignin, solvolysis and hydrogenolysis experiments were performed. This research considered whether the low yields of products (fine chemicals) were related to the low content of β-O-4 bonds or if it was also associated to the dissolution of lignin in the solvent solution employed in the reactions. The type of solvents chosen to check the dissolution effect were those with low cost and were more sustainable than traditional solvents. Water, ethanol, isopropanol (IPA) and acetone were used. The water mixtures were applied in the tests in various proportions (25:75, 50:50, 75:25 solvent/water v:v). Due to their ability to break C-C and C-O bonds in lignin model compounds [1][2], the efficiency of platinum and rhodium in these reactions supported on alumina was also studied. It was found that the non-catalysed (solvolysis) and catalysed reactions showed different selectivities but similar overall yields ~ 10 % wt of monomeric phenols. The difficulty in increasing yields was mainly associated with the highly condensed character of Kraft lignin and re-polymerisation issues. To achieve an understanding of Kraft lignin depolymerisation, isotopic labelling reactions were completed in the presence of deuterated solvents as well as deuterium gas. This gave information on how Kraft lignin depolymerises, the influence of solvent to products formation and the involvement of hydrogen in the rate determining steps in the reactions. These results have led to an initial mechanistic understanding on how this complex molecule may yield alky-phenolic compounds. It was revealed that the solvent was directly involved in the products’ formation and that they were not generated by simple thermolysis. In addition, the presence of catalysts and hydrogen influenced product formation. The compounds showed different kinetic isotopic values, suggesting that each of these molecules came from individual mechanisms, highlighting the complexity of their formation. This was a relevant study as most of lignin depolymerisation mechanistic insights are based on model compounds and not on lignin itself. It was of interest to this project to explore not only different catalysts and their relationship to lignin depolymerisation, but also different lignin types. A simple pre-treatment for lignin extraction using sawdust (from oak and birch wood) in a Parr autoclave reactor in the presence of hydrogen, solvent and high temperature was developed. The lignins obtained after the pre-treatment were named parr-lignin and successfully resulted in polyaromatic molecules with less condensed character compared to lignins from Soda or Kraft pulping. Reactions were carried out with these lignins and a sugar-cane lignin. 4 5 Different catalytic systems with these lignins were investigated and how depolymerisation was affected by the metal and support used. The catalysts involved in the reactions included platinum, rhodium, nickel and iron. Various supports such as alumina, zirconia and carbon were tested along with the metals described. It was found that the supports were not inert in these experiments presenting catalytic activity. Materials with low surface area (zirconium catalysts) gave a poor performance compared to the others. In addition, nickel, a non-noble metal, showed as good a catalytic effect in the depolymerisation of these lignins as Pt and Rh. The components in the system influenced the reactions to different extents, especially product distribution. The catalysts had different selectivities and the solvents were not only dissolving lignin but also influencing the results. GPC analysis was performed to give an overview of the condensed level of these lignins and degrees of depolymerisation compared to the original material. GC-MS enabled the identification and quantification of 18 monomeric compounds. The post reaction characterisation of selected alumina catalysts (Pt/Al2O3, Ni/Al2O3 and Al2O3) was performed using XRD, BET, CHN, TPO and Raman Analysis to study the nature of the carbonaceous layer deposited on these materials. The work showed that after reaction the catalysts turned black in colour and the carbon laydown consisted of not only one simple type of carbon, and included graphitic species. The amount of carbon deposited depended on the type of lignin. Oak and birch parr-lignins had the highest and lowest amount of carbon over the catalysts respectively. No obvious trend relating to the type of catalyst, lignin and solvent used to the carbon nature was identified. This work showed that lignins with less condensed nature were less susceptible to solvolysis and more to hydrogenolysis. For example, sugar-cane lignin gave 3.9% of phenolic compounds in the solvolysis while reaction with Rh/Al2O3 gave 12.9% of products. This indicated that more selective cleavage of bonds were promoted by heterogenous catalysts. The results suggested that some compounds were mainly generated via dealkylation and hydrodeoxygenation, allowing a future possibility to generate target molecules. These results were mainly due to the presence of more labile bonds, vulnerable to hydrogenolysis. Highlighting that prior to depolymerisation, the pre-treatment used to extract lignin must be appropriate to avoid depletion of the alkyl-aryl ether bonds (β-O-4 bonds, especially) relevant for fine chemicals generation.
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Hartmann, R. (Robert). "Flotation using cellulose-based chemicals." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526219806.
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Abstract Flotation is a well-known and widely used technique for the separation of particles smaller than 250 µm, but efficient performance requires the use of various synthetic chemicals which can potentially damage the health of humans and animals and pollute the environment. Consequently, their replacement through a more environment-friendly and sustainable alternative has been demanded. One promising candidate is cellulose, which is an abundant natural polymer that is environment-friendly and can be treated chemically and physically to yield tailored properties and thus a potential for use in processes such as flotation. This work focuses on the use of cellulose-based reagents in flotation processes to replace the often harmful conventional reagents derived from mineral oil, plant oils or animal fats. The physico-chemical properties of cellulose differ from those of conventional reagents, leading to differences in performance during flotation. In particular, the chemical and morphological heterogeneity of cellulose affects its properties and thus its interaction with minerals and water. Consequently, its use requires the study of the fundamentals of flotation and their application including the physico-chemical heterogeneity of cellulose to determine the optimum conditions and enable efficient performance. This work focuses on the determination of the thermodynamic surface energetics of solid particles and changes in this after reagent adsorption, using the inverse gas chromatography technique in a dry atmosphere. Furthermore, interactions between cellulose and minerals immersed in water are investigated using the DLVO theory, the interaction forces between cellulose and the minerals being derived and correlated with flotability. The importance of free surface charges is then considered by investigating the electric surface potential of cellulose-coated minerals in connection with particle-bubble attachment efficiency. At the same time, conventional amphiphilic reagents are used and its performances are related to cellulose-based reagentsTiivistelmä Vaahdotus on kaivannaisteollisuudessa laajasti käytössä oleva prosessi, jonka avulla saadaan erotettua tehokkaasti pieniä, alle 250 µm kokoisia partikkeleita. Vaahdotuksen apuaineena käytetään erilaisia synteettisiä kemikaaleja, jotka voivat aiheuttaa harmia ympäristölle. Siksi niiden korvaaminen ympäristöystävällisemmillä vaihtoehdoilla on tärkeää. Yksi lupaava vaihtoehto korvaavaksi materiaaliksi on selluloosa. Selluloosa on uusiutuva ja ympäristöystävällinen luonnonpolymeeri, josta voidaan valmistaa kemiallisesti ja fysikaalisesti käsittelemällä erilaisia biokemikaaleja. Näitä voidaan soveltaa erilaisissa prosesseissa, myös vaahdotuksessa. Tässä työssä keskitytään selluloosapohjaisten kemikaalien käyttöön vaahdotuksessa tavanomaisten, usein haitallisten synteettisten kemikaalien korvaamiseksi. Selluloosan fysikaaliskemialliset ominaisuudet eroavat synteettisten vaahdotuskemikaalien ominaisuuksista, mikä vaikuttaa niiden vuorovaikutukseen mineraalien ja veden kanssa. Erityisesti selluloosan kemiallinen ja morfologinen heterogeenisuus on keskeinen tekijä. Selluloosan hyödyntäminen tulevaisuuden vaahdotuskemikaalina edellyttää selluloosan ja mineraalien vuorovaikutuksen syvällistä ymmärtämistä. Tässä työssä tutkitaan selluloosan ja mineraalien vuorovaikutusta sekä IGC-menetelmän avulla, että DLVO-teorian että pintavarausmittausten avulla. Lisäksi tutkitaan selluloosan ja mineraalien vuorovaikutusvoimien yhteyttä vaahdotusprosessin onnistumiseen ja saavutettuja tuloksia verrataan kaupallisten reagenssien toimintaan
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Strawson, Steven William. "Fine chemicals from plant extracts." Thesis, Bangor University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539908.
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Stewart-Perry, Randall. "Biological chemicals in rock coatings /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6733.
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Chun, Wang. "Erosion-corrosion mitigation using chemicals." Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/747/.
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The presence of entrained sand in oil and gas production is becoming increasingly prevalent as wells age and this is leading to erosion-corrosion in C02-saturated conditions becoming a major mechanism of material attack. Its understanding, prediction and control are key challenges to sound facilities design. The use of carbon steel in conjunction with corrosion inhibitors in preventing erosioncorrosion has been observed as an economically viable solution for oil and gas piping systems. In order to produce highly effective corrosion inhibitors, it is important to understand how inhibitors act on each of the components of erosion-corrosion. Although research into corrosion inhibition has been extensively conducted, there is less documentation of inhibitors in retarding erosion-corrosion. This thesis has attempted to construct a quantitative structure relationship between erosion, corrosion and their synergistic effects to investigate erosion-corrosion and inhibition mechanisms with four fully formulated CO2 inhibitors (CGO, CRO, CRW8 and CRW9) along with some mechanistic studies involving single components from inhibitor formulations. Two experimental set-ups were used: a rotating cylinder electrode (RCE) and a submerged impinging jet (SIJ). In both experimental methodologies, gravimetric measurement, cathodic polarisation, Linear Polarisation and AC impedance techniques were used to ascertain the extent of corrosion as a function of conditions and inhibitor dosing/type. Both RCE and SIJ test samples were studied using surface analysis techniques such as scanning electron microscope (SEM), Light microscope, Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). In this thesis, through integration of electrochemical analysis and gravimetric measurements the damage has been identified as being associated with mechanical erosion, electrochemical corrosion or interactive electrochemical/mechanical processes. The role that inhibitors can play in reducing damage in addition to that caused by corrosion, namely by erosion and their synergistic action has been shown. Under both configurations. erosion-corrosion interactions play a major role in damage with corrosion being a controlling parameter. The thesis has made substantial advances in the understanding of the extent to which corrosion inhibitors could be used to control erosion-corrosion damage and in understanding the mechanisms of how this can be achieved.
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Thivhafuni, Phumudzo Olga. "Managing chemicals at the University of Limpopo : A safety perspective." Thesis, University of Limpopo (Turfloop Campus), 2008. http://hdl.handle.net/10386/842.
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Thesis (MBA.) --University of Limpopo, 2008Chemicals are found to be enormously dangerous on the health and safety criteria. In academic laboratories, chemical safety has always been a major concern. Safety risks are either not perceived at all, or perceived to be less dangerous than what they actually are. The climate of safety in any organization consists of employees’ attitudes towards, and perceptions of safety behaviour. In academic departments, safety is influenced by factors such as the organisational environment, management attitude and commitment, the nature of the job or task, and the personal attributes of the individual. This study is concerned with safety climate and chemical management practices in academic departments. More specifically, it investigates the safety perceptions, attitudes, and chemical management behaviours of university employees. It represents the empirical results of a questionnaire survey administered in a university department and direct observations of safe and unsafe chemical management behaviours, targeting employees who work with chemicals. Based upon the survey analysis results, this study demonstrates that employees in the academic departments under study have a good degree of risk awareness and a relatively high degree of safety consciousness. The results also reveal employees’ intentional unsafe chemical management behaviours. Further, it was found, empirically, that overall employees’ intentional unsafe behaviours seem to be best explained by employees’ perceptions of management attitude and commitment to safety, social and physical work environment, priority for safety, as well as their perception of the risk they are generally exposed to in their work environment. The study, thus, establishes that perceptions of management attitudes and actions have a direct effect on employees’ behaviour. There is a positive correlation between workers’ safety climate and chemical management safe behaviour in academic departments.
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Jacobson, Aaron. "Diffusion of Chemicals into Green Wood." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10516.
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Mass transport of chemicals into wood is important in kraft pulping. This thesis models small wood particles as cylinders and monitors how tritiated water and sulfide diffuse into the water-filled pores. Tritiated water diffusion is Fickian and diffuses completely into the water contained in the wood. Tortuosity values of the aspen and pine are tabulated. As particle size decreases, the tortuosity of the particles increases. As sulfide diffuses into wood, it is occluded from some water filled areas. Charge exclusion is a possible explanation for this. Sulfide and hydroxide transport into wood chips was displayed using indicators for each component. Pictures show sulfide ingress into the chip core faster, thus confirming the diffusion results. Fractionated sawdust was pulped to determine particle size effect on cooking and pulp properties.
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Sadek, Garboui Samira. "Plant-Derived Chemicals as Tick Repellents." Doctoral thesis, Uppsala universitet, Systematisk zoologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9368.
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Ixodes ricinus is the main vector of Lyme borreliosis and Tick-borne encephalitis in Europe. Repellents provide a practical means of protection against tick bites and can therefore reduce transmission of tick-borne diseases. In laboratory tests, pieces of cloth treated with MyggA Natural® (a commercial insect repellent) or with the essential oils of Corymbia citriodora (30%), Lavandula angustifolia (1 and 30%), Pelargonium graveolens (1 and 30%), Hyptis suaveolens (10%), Salvadora persica, Pistacia atlantica, Juniperus phoenicea (20%) and methyl jasmonate (MJ) (0.5%, 1.0%, 2.0% and 5.0%) showed strong repellent activity against I. ricinus nymphs. In a tick-infested woodland in east-central Sweden, we tested by randomized, standardised methodology the potential anti-tick repellent activity of MyggA Natural® (roll-on), two concentrations of MyggA Natural® spray, RB86 (a commercially available insect repellent for horses), the essential oil of C. citriodora and three concentrations of MJ. Each substance was dissolved in acetone and applied separately to 1 m2 cloths which were then pulled over vegetation. Nymphal tick numbers on the cloths were recorded at 10-m intervals and differed significantly between treated cloths and the untreated control and also between collectors. Volatile compounds from fresh and dried leaves of H. suaveolens and the essential oils of H. suaveolens (from Laos and Guinea Bissau) and S. persica, P. atlantica and J. phoenicea (from Libya) were collected by solid phase micro-extraction (SPME) and the constituents were identified by gas chromatography - mass spectrometry (GC-MS). Two main sesquiterpene hydrocarbons in the H. suaveolens oil were β-caryophyllene and humulene. These were modified by oxidation and sulphidation to obtain effective tick repellent compounds with lower volatility. In all three oils from Libyan plants the main monoterpene hydrocarbons were α-pinene, sabinene, β-pinene, myrcene, α-phellandrene, 4-carene, β-phellandrene and γ-terpinene. The selected plant species contained numerous volatiles known to have insecticidal, acaricidal, and/or insect repellent properties.
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Sherazi, Aisha. "Multiple hormonal activities of industrial chemicals." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324553.
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Fry, C. V. "Solids for control in chemicals production." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637014.
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Solid support catalysts for three reactions were explored. It was desirable to cause the Diels-Alder reaction of cyclopentadiene and methyl acrylate to be Exo selective. Shape selection catalysis was to be used. None of the solids tested induced the desired product selectivity. However, H Mordenite was found to alter the reaction selectivity, producing far more Exo adduct than is normally found. Also, Synclyst 25 was found to promote production of the Endo adduct. Reaction in the presence of this solid was rapid and highly selective. The Prins reactions of formaldehyde with 1-pentene, 2-pentene and 2-methyl-2-butene were studied. Prins reactions give a mixture of products and use soluble acid catalysts. It was intended that solid support materials should be used as acid catalysts and to exert shape selectivity in these reactions. The chosen Prins reactions were promoted by some of the solids tested but none were as effective as sulphuric acid. Solid supports were used to influence the outcome of the bromination of naphthalene by tertiary butyl hypobromite. This reaction is catalysed by acids. The acidity of the solids tested was used to promote the reaction rate, whilst the solids' shapes were investigated for their ability to control the product distribution. Of the two possible monobromination products usually only 1-bromonaphthalene is formed in free solution as a significant product. A solid was sought that would induce selectivity in favour of 2-bromonaphthalene. Zeolite HL was found to achieve this partially. The reaction still generated 1-bromonaphthalane as the major product but a significant portion of the product was 2-bromonaphthalene. H Mordenite was found to promote the rate of the reaction whilst allowing exclusive production of 1-bromonaphthalene. This was a significant discovery as free-solution bromination of naphthalene usually generates a small portion of 2-bromonaphthalene.
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Benites, Galbiati Martín. "A silicon laboratory: chemistry without chemicals." Revista de Química, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/99186.
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El Premio Nobel de Química de 2013 ha sido otorgado a A. Warshel, M. Levitt y M. Karplus debido al desarrollo de métodos híbridos de cálculo para química computacional. En este artículo se presentará una breve introducción del uso de los métodos de química computacional. Se describirá cómo se desarrollaron, y por qué, los métodos híbridos de cálculo, conocidos como QM/MM (Quantum Mechanics/Molecular Mechanics) para el estudio de sistemas macromoleculares, sobre todo para el caso de su aplicación en enzimas y bioquímica. Finalmente, se comentarán los alcances y expectativas futuras para estos métodos, desarrollados en los años 70.The 2013 Nobel Prize in chemistry was awarded to A.Warshel, M.Levitt and M.Karplus for their contribution to the development of hybrid methods for computational chemistry. In this article a brief introduction about computational chemistry methods is presented. This paper will show the order in which the QM/MM (Quantum Mechanics/Molecular Mechanics) methods were developed for the study of macromolecular systems and specially their application in enzymes and biochemistry. Finally, the reach and future prospects of these methods originally developed by A. Warshel, M.Levitt and M. Karplus in the seventies will be discussed.
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Wojciechowski, Kristin Lynn. "Developing Platform Chemicals from Renewable Resources." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26852.
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The Department of Energy has listed 5-hydroxymethylfurfural (HMF) and 2,5-furandicarboxylic acid (FDCA) as two of the twelve building blocks derived from cellulosic biomass. HMF can serve as a renewable platform for the production of fuels and chemicals. Our research goal is to develop novel methods for the conversion of renewable resources to feedstock chemicals for polymer synthesis. The Diels-Alder reaction, the cycloaddition of alkenes and dienes, has become one of the most important synthetic methods used in organic chemistry. We were interested in carrying out Diels-Alder reactions with derivatives of HMF. Naphthalene analogs of terephthalic acid were synthesized by reacting HMF derivatives with benzyne which could lead to the formation of bio-based polyethylene terephthalate (PET) analogs.
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Narvaez, Dinamarca Ana Lorena. "Integrated production of chemicals and energy." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5623.
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Polygeneration technologies based on synthesis gas allow for the simultaneousproduction of intermediate chemicals and the generation of electricity. The study ofthe integrated production of chemicals and power has different approachesdepending on the products and their demands. This study focuses on the combinedproduction of methanol or dimethyl ether and electricity considering a small tomedium scale production plant to provide chemicals (for applications such astransportation fuel or LPG substitute) and electricity for a small to medium-sizedpopulation. Methanol or dimethyl ether and electricity production were estimated to meet a localtransportation fuel market and off-peak load electricity demand for a small town. The methanol and dimethyl ether synthesis were simulated assuming both asynthesis loop and a once-through configuration. The effect of lower catalyticperformances on the polygeneration system performances was tested in methanoland dimethyl ether production. In addition, direct DME synthesis was assessed atdifferent catalyst loading ratios and also different H2/COx ratios. The flexibility of thecombined systems was studied assuming different approaches to cope with achange on the demand for chemical or electricity. These approaches involvedchanging operating conditions such as the recycle ratio or the synthesis gas feedrate. The feasibility of the polygeneration systems was determined through thecomparison with separate stand-alone configurations for chemical production andpower generation considering requirements of fresh synthesis gas, heating/coolingutilities, and compressor duties. In general, the simulations of the integrated system based on once-throughconfiguration for both MeOH and DME synthesis cases showed lower powerconsumptions and lower fresh synthesis gas requirements compared to theequivalent stand-alone and loop configurations. Finally, the once-throughpolygeneration system is an attractive scheme to produce chemicals and powerbecause of the simplicity of the chemical plant and its lower capital and operatingcosts.
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Caretto, Alessio <1986>. "Green transformations of bio-based chemicals." Doctoral thesis, Università Ca' Foscari Venezia, 2014. http://hdl.handle.net/10579/5616.
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This thesis work was focused on the development of green chemical technologies for the upgrading of platform molecules obtainable from renewable feedstocks through a biorefinery scheme. The feedstocks were chosen among those considered as the most promising for the development a new, sustainable, chemical industry.
Levulinic acid (LA) can be converted into new derivatives with a higher degree of oxigenation (methyl levulinate and its 4,4-dimethyl ketal, dimethyl succinate and dimethyl 3-methylsuccinate), without actually using oxidizing agents. This result was achieved by using dimehtyl carbonate (DMC), a green reagent and solvent, in conditions of basic catalysis (K2CO3).
Bio-derived lactones such as gamma-valerolactone, gamma-butyrolactone, delta-valerolactone and epsilon-caprolactone were reacted with three dialkylcarbonates (DMC, diethyl- and dibenzylcarbonate). The five-membered ring lactones yielded the corresponding alpha-alkylated derivatives with high selectivity and yields. The six- and seven-membered ringed lactones afforded highly oxygenated acyclic monomeric derivatives otherwise hardly accessible by previous chemistry.
Gamma-valerolactone was chosen as a model to study acid catalyzed ring-opening reactions. A novel reactivity of the molecule was discovered in the presence of DMC. The 4-methoxy pentanoyl moiety was thus accessible by a green route. A reaction mechanism, supported by experimental and computational data, was proposed. The reaction was then extended to a continuous flow process, with solid acid catalysts. In such conditions, the selectivity towards methyl 4-methoxy pentanoate or methyl pentenoate, monomer for the production of polymers, can be tuned by optimising the operating parameters:
Bio-derived diols were efficiently upgraded using organic carbonates in tandem with ionic liquids as organocatalysts. The study investigated the parameters that control the selectivity towards cyclic- or linear di-carbonates.
The derivatisation of fatty acids methyl ester in conditions of on-water catalysis was investigated whilst at the University of Sydney, with the aim of developing a green strategy to reduce the cloud point of biodiesels. A new branched additive was synthesised, the thermal characteristics of which were analysed, both pure and blended with biodiesel.
The study of on-water catalysis continued by investigating the mechanism and the effect of reagent structure on on-water catalysis. It was demonstrated, by using the model reactions between cyclopentadiene (cp) and alkyl vinyl ketones, that little changes of the alkyl chain of a reactant have a dramatic influence on the catalytic effect. In particular, the reaction between ethyl vinyl ketone and cp was demonstrated to be on-water catalysed. When vinyl ketones bearing a longer or bulkier alkyl chain were tested, the catalytic effect was not observed, and the reactions were as fast as in neat conditions.
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Campalani, Carlotta <1993>. "Masked phosphonium ilydes for fine chemicals." Master's Degree Thesis, Università Ca' Foscari Venezia, 2018. http://hdl.handle.net/10579/12656.
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Lo scopo del presente lavoro è stato lo studio della reattività del trifenilmetil fosfonio metilcarbonato per una sintesi più "verde" e sostenibile della Rosuvastatina, uno dei farmaci "blockbuster" per il trattamento del colesterolo alto e di disturbi cardiovascolari. L'attuale procedura per la sintesi di questo farmaco prevede una reazione di Wittig tradizionale basata sull'uso di una base forte e di organo alogenuri.
Il trifenilmetil fosfonio metilcarbonato è un agente vinilante di Wittig mascherato che non necessita di basi o alogenuri aggiuntivi. La tesi è iniziata con l'investigazione della reazione tra il sale di fosfonio e vari carbossilati attivi per la sintesi di un reagente di Wittig più complesso indipensabile per la sintesi della Rosuvastatina. Per questo scopo sono state usate diverse condizioni e substrati, come cloruri acilici, anidridi, esteri attivi e metossicarbonil esteri. é stato poi svolto uno studio meccanicistico per capire la reattività del sale di fosfonio con alcuni substrati ossigenati e per spiegare i risultati della reazione proposta.
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Plahuta, Joseph Matthew. "Development of a novel environmentally friendly starch-based aircraft deicer." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Thesis/Spring2010/j_plahuta_041610.pdf.
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Thesis (M.S. in environmental engineering)--Washington State University, May 2010.Title from PDF title page (viewed on June 18, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 28-29).
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Jarvis, J. "Occupational allergy to low molecular weight organic chemicals : the role of structure in determining chemical hazard." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/28300.
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A number of low molecular weight (LMW) organic chemicals are known to cause occupational respiratory or skin sensitisation. A set of 200 LMW organic skin and 75 respiratory sensitisers was identified by systematic search and critical appraisal of published cases and epidemiologic literature. In addition a set of 302 control chemicals was selected from known hazardous LMW organic chemicals for which no reports of respiratory sensitisation could be found. Several approaches based on chemical structure and using a case-control methodology were investigated to differentiate between asthmagens and controls, or asthmagens and skin sensitisers (by chemical structure alone) were investigated. These comprised hazardous fragment identification by calculating odds ratios for hazard (HOR's), cluster analysis and logistic regression analysis. Of these methods the most effective approach was the logistic regression analysis. Using these methods several known or suspected hazardous substructures were confirmed to present statistically significant occupational asthma (OA) hazard. These included isocyanates, acid anhydrides, acrylates and (oligo)-amines. Many hazardous compounds contained pairs of hazardous substructures. Furthermore, certain sub-structural fragments such as chlorine atoms appeared to provide a protective effect from OA hazard. For differentiating between skin sensitizers and asthmagens it was noted that fragments with carbon double bonded to nitrogen or oxygen atoms were significantly more prevalent in the respiratory sensitisers set. A predictive model of chemical asthma hazard was created using logistic regression and the model tested on a validation set of chemicals yielded a predictive kappa value of 0.7. This model is available for predictive testing of compounds for asthma hazard via the World Wide Web. This work demonstrates that simple structural information may, in conjunction with a well designed methodology, be used to identify occupational sensitisers with reasonable reliability.
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Cota, Iuliana. "New basic catalysts for fine chemicals synthesis." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8591.
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En los últimos años, existe un creciente interés en la sustitución de viejas tecnologías por alternativas catalíticas más limpias para el desarrollo de procesos respetuosos con el medio ambiente para la industria química. De esta manera, es un desafío continuo encontrar nuevos catalizadores básicos capaces de realizar, con alta actividad y selectividad, las reacciones para la síntesis de productos de alto valor añadido tanto químicos como farmacéuticos. La investigación descrita en esta Tesis se ha centrado en el estudio de nuevos protocolos de síntesis para catalizadores básicos. Nuevos materiales con basicidad controlada, tipo hidrotalcita, se han sintetizado a lo largo de esta Tesis. Por otra parte, se ha desarrollado un nuevo protocolo de síntesis para líquidos iónicos alifáticos de cadena corta. Además, se presenta un amplio estudio de las propiedades físico-químicas de los líquidos iónicos sintetizados. Las propiedades básicas de los catalizadores desarrollados se han caracterizado por diversas técnicas y así como mediante el empleo de reacciones modelo. Por consiguiente, el trabajo realizado en esta Tesis permite avanzar en el diseño de nuevos sistemas catalíticos más activos y eficientes para su utilización en procesos de química fina.In the last years, there is an increasing interest in substituting old technologies by cleaner catalytic alternatives to afford more environmental friendly processes in the chemical industry. In this way, it is a continuous challenge to find new base catalysts able to perform, with high activity and selectivity, reactions for the synthesis of pharmaceutical and fine chemicals.
The research described in this thesis has focused on the study of new synthesis protocols for base catalysts. New types of hydrotalcite-like materials with controlled basicity were obtained. Also, a new synthesis protocol for short aliphatic chain ionic liquids and an extensive study of their physico-chemical properties is presented. Their basic properties have been characterized by several techniques and by illustrative test reactions. The work done in this thesis can be regarded as a progress in the design of new catalytic systems, more active and efficient for use in fine chemical processes.
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Nygren, Cathrine. "Recovery of chemicals in xylan extraction process." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17775.
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Food packages containing products such as fruit juices, coffee, snacks and spices need to have barriers that can prevent oxygen, aroma substances and grease to diffuse through the packages in order to maintain or extend a certain quality of the product. Today those barriers consist of aluminium and ethylene-vinyl alcohol (EVOH) plastics, based on petroleum. The prices for these materials are raising and the growing shortage of fossil fuels eager the needs for an alternative to existing barriers.
It has been shown that hemicelluloses can be treated to form films with low permeability to oxygen, greases and aroma substances. Hemicelluloses are one of the must abundant biopolymers and can be isolated from for example annual plants. Isolation of hemicelluloses is preferably performed with alkali extraction, by recycling and reusing of alkali, the production process could be more cost effective and less burdensome for the environment. The alkali is separated from the hemicelluloses by ultrafiltration.
The study was divided in two parts. The purpose of the first part was to examine how the oxygen permeability of the barrier was affected when alkali was recovered directly from an effluent waste stream from the ultrafiltration and with the addition of some fresh alkali reused for extraction in another batch. The second part of the study was dedicated to investigate how nanofiltration membranes could be used to recover pure alkali from the effluent stream. The membranes studied were NF97, NF99 and NF99HF, all three manufactured by Alfa Laval. By varying pressure, flow and temperature it was investigated which membrane that gave the highest fluxes through the membrane, the permeate fluxes, and highest concentrations of alkali.
Recycling alkali directly from one batch to the following could not be proved to affect the oxygen permeability negatively, although the concentration of the recovered alkali was rather low. The nanofiltration membrane that gave the highest permeate fluxes was NF99 while NF97 gave the highest concentrations of alkali.
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Eriksson, Lennart. "A strategy for ranking environmentally occuring chemicals." Doctoral thesis, Umeå universitet, Kemiska institutionen, 1991. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100716.
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A systematic methodology for quantitative structure-activity relationship (QSAR) development in environmental toxicology is provided. The methodology is summarized in a strategy with six sequential steps. The strategy rests on two cornerstones, namely (1) the use of statistical design to select a series of representative compounds (the so-called training set) on which to base a QSAR, and (2) the multivariate modelling of the relationship between physicochemical and biological properties of the training set compounds. The first step of the strategy is the division of chemicals into classes of structurally similar compounds. Briefly, steps 2 to 6 are: (2) physico-chemical and structural characterization of the compounds in a class, (3) selection of a training set of representative compounds, (4) biological testing of the selected training set, (5) QSAR model development, and (6) experimental validation of the QSAR and predictions for non-tested compounds. The thesis summarizes the results obtained from the application of the strategy to the class of halogenated aliphatic compounds. Biological measurements were made in four biological test systems, reflecting acute toxicity, mutagenicity, relative cytotoxicity and genotoxicity. QSARs were developed relating each biological endpoint to the structural descriptors of the compounds. Multivariate PLS modelling was used in the data analysis. The developed QSARs were used for predicting the biological activity pattern of the non-tested compounds in the class. These predictions may be used as a starting point for a priority ranking for further biological testing of these compounds. The strategy has not been developed solely for establishing QSARs for the halogenated aliphatics class. On the contrary, this work is intended to demonstrate a generally applicable QSAR methodology.Diss. (sammanfattning) Umeå : Umeå universitet, 1991
digitalisering@umu
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De, Braganza Radek Messias. "Fine chemicals from cashew nut shell liquid." Thesis, Bangor University, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409441.
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Meyer, Stephanie Kristen. "Effects of oestrogenic chemicals on the liver." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3654.
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Our environment and diet contains a variety of man-made endocrine disrupting chemicals which may pose a significant health threat for wildlife and humans. In particular, there is increasing concern regarding the adverse effects caused by xenoestrogens which are believed to trigger many endocrine-related diseases. Since high systemic levels of oestrogens are cholestatic, it was investigated whether xenoestrogens are able to cause adverse hepatic effects in vivo in mouse models and whether these effects are mediated by interaction with the murine oestrogen receptors (ERs). The food dye tartrazine has previously been shown to activate the human ERα and intraperitoneal injection caused cholestasis in mice. In this study, tartrazine failed to activate murine ERα and two murine ERβ variants in vitro suggesting that cholestasis occurred independent of the ERs. Data indicate, however, that tartrazine, its major metabolites and a contaminant inhibited murine dopamine sulfotransferase. Considering the role of sulfotransferases in bile acid secretion, these findings suggest that impairment of bile acid sulfation and subsequent secretion may be a key event in tartrazine-mediated cholestasis. Oral exposure to tartrazine caused inflammation in the liver and gastrointestinal tract in vivo in mice without evidence of cholestatic effects. Several soil extracts prepared from soil samples collected from around an urban landfill site activated human and murine ERα and two murine ERβ variants in vitro. Pooled oestrogenic soil extracts had mild cholestatic effects in a mouse model. Given the cholestatic features of the liver disease primary biliary cholangitis (PBC), which is linked to exposure to xenobiotics associated with a toxic environment and proximities to waste sites, environmental xenoestrogens could be a component of a xenobiotic insult that triggers PBC. These findings indicate that if significant exposure to environmental xenoestrogens occurs, they can have adverse hepatic effects and may be part of a trigger process in cholestatic liver diseases.
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Myers, Travis R. (Travis Ray). "Active hyperspectral imaging of chemicals on surfaces." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/112385.
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Thesis: S.M. in Materials Science, Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 90-92).
Active hyperspectral imaging (HSI) is a promising technique for the detection of chemicals at standoff distances. In active HSI, a target is illuminated by a laser source at many different wavelengths and a camera obtains an image of the illuminated scene at each wavelength. In this research, the feasibility of hyperspectral imaging for the detection of particles on surfaces was demonstrated using potassium chlorate particles on car panels at distances of 5 m, 10 m, and 20 m. Using the Adaptive Cosine Estimation (ACE) algorithm which compares the observed reflectance spectra to a reference spectrum, potassium chlorate fingerprints are easily visible at many different sample angles. However, in general, there is a large amount of variation in the shape and magnitude of spectra in a hyperspectral image that depend on factors such as particle size, viewing geometry, and surface reflectivity. Thus, Mie Theory calculations are performed on simulated materials and combined with information from sources such as Hapke [4], [20] to give qualitative insight into the expected shape and magnitude of reflectance spectra from sparse particles on a surface. The shape of the spectra depends on whether the particles are strongly absorbing or weakly absorbing. Strongly absorbing particles tend to have reflectance maxima near the resonant frequency, whereas weakly absorbing particles tend to have reflectance minima. For highly reflective substrates, the reflectance decreases sharply as the sample angle increases and becomes dominated by backward scattering from the particle which has a flatter spectrum around the Christiansen frequency, the frequency at which the refractive index of the particle is closest to one. The double interaction model, which uses Mie Theory to calculate the contributions to the reflectance along two different light paths, is used to accurately account for how the shape and magnitude of the reflectance spectra of sodium chlorate particles on gold and silica surfaces changes as a function of sample angle and laser angle. A method for approximating the mean particle size based on the location of the peak near the Christiansen frequency is derived. This method, when applied to the sodium chlorate sample, yields a result for the mean particle diameter that is approximately half of the value determined using a microscope. The Hapke Isotropic Multiple Scattering Approximation (IMSA), combined with Mie Theory, is used to give qualitative insight into the expected shape and magnitude of reflectance spectra from bulk powders. Compared with the reflectance spectra from sparse particles, the spectra from bulk powders are much simpler and less dependent on the viewing geometry. The Hapke IMSA model is able to accurately account for the observed changes in the reflectance from bulk sodium chlorate powder at multiple sample angles and laser angles. A final scenario of interest is thin films on rough or porous surfaces. Using a model that takes into account diffusely reflected and specularly reflected light, the observed reflectance spectra from diethyl phthalate (DEP) on a brick is fitted to a high degree of accuracy. This suggests a promising method for using hyperspectral imaging to determine the thickness of liquids on porous surfaces. Finally, the issue of speckle in hyperspectral imaging was examined using simulations based on Fourier optics and information from sources such as Goodman [6], [17]. Speckle is a limiting factor in hyperspectral imaging because it is noise that scales with the signal, and thus cannot be eliminated by increasing the signal strength. Equations from various sources are presented that describe the reduction in speckle contrast for spatial, spectral, polarization, temporal, and angular averaging. Original equations for the reduction in contrast for spectral and angular averaging are derived.
by Travis R. Myers.
S.M. in Materials Science
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Gao, Xiaoqian. "Environmental Endocrine Disrupting Chemicals and Cardiac Arrhythmogenesis." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1427799826.
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Oliveira, Rhaul. "Effects assessment of chemicals used in aquaculture." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/16297.
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Doutoramento em BiologiaAquaculture provides food and income for millions of families worldwide being an activity with a high growth rate and with a strong potential for further expansion. Both producers and consumers are interested in a sustainable model of aquaculture development covering social, economic and environmental aspects. Such model implies to cope with the environmental impacts generated by aquacultures. The main objective of this work was to evaluate the use of chemicals applied in aquaculture farms and their harmful effects to aquatic organisms. Since more than 80% of global production of aquatic organisms is concentrated in Southwest Asia, special attention was given to the aquaculture in this region, particularly Thailand. Three different types of aquaculture scenarios were studied: shrimp farms and tilapia farms in cages and in earth ponds. Surveys and monitoring campaigns were conducted in several farms and the fate, use and application patterns of chemicals were identified. In cage farms the results indicated overuse/misuse of antibiotics, in shrimp farms the major group of chemicals used were disinfectants whereas in earth pond farms 1,7α-methyltestosterone (MT) was the most used. The results from the monitoring campaigns showed that the excessive use of chemicals was correlated to contamination of the surrounding environment namely with the antibiotics oxytetracycline (OTC) and enrofloxacin (ENR) in the cage farms, and with MT in the earth pond farms. In the laboratory, ecotoxicity assays were performed with antibiotics, disinfectants and pesticides using organisms belonging to different trophic levels. The disinfectants benzalkonium chloride (BKC), chlorhexidine gluconate (ChD) and glutaraldehyde (GA) were tested. BKC and ChD demonstrated to be very toxic to primary and secondary consumers. Moreover, an approach based on the species sensitivity distributions (SSD) was used to estimate the hazardous concentrations for 5 and 50 % of the species after BKC and GA exposure highlighting the sensitivity of primary producers to BKC exposure (HC5 = 10.8 μg/l). In the case of GA, different trophic levels showed similar sensitivities and a general HC5 = 300 μg/l was obtained. Additionally, a probabilistic environmental risk assessment was performed indicating a PAF (potentially affected fraction) of species > 5% for adverse effects of BKC in effluents and surface water. Concerning pesticides, both trichlorfon (TCF) and ivermectin (IVM) were studied. TCF showed to be extremely toxic to daphnids (48h- LC50 = 0.29 μg/l) and affected the acetilcolinesterase activity in D. magna and D rerio. IVM showed to be acutely toxic to D. rerio life stages (96h-LC50 = 18.5 μg/l for juveniles) and affected their development and biomarkers. In chronic exposures, IVM led to changes in the behaviour and growth of D. rerio juveniles (21d-LOEC < 0.25 μg/l). The antibiotics amoxicillin and OTC were not acutely toxic to aquatic organisms but both induced oxidative stress related enzymes of adults and embryos of D. rerio. Globally, most of the tested chemicals showed to compromise at least a particular group of organisms or sub-lethal parameters, requiring further long term studies so that the environmental risk assessment of these compounds can be refined. Lethal and sub lethal effects obtained to non-target organisms suggest a potential biodiversity loss in the aquatic ecosystems which might, thus, compromise the services provided by the ecosystems in a near future. Since the aquaculture relies directly on these services (e.g. high water quality) to succeed, there is an urgent need of control/education measures both in the use of chemicals in aquaculture and monitoring/mitigation of adverse impacts in natural ecosystems.
A aquacultura fornece sustento para milhões de famílias, sendo uma actividade em crescimento e com um forte potencial de expansão em todo o mundo. Há um interesse por parte de produtores e consumidores em desenvolver modelos sustentáveis de aquacultura abrangendo aspectos sociais, económicos e ambientais. Tais modelos implicam lidar com os impactos ambientais gerados pela aquacultura. O principal objectivo deste trabalho foi estudar o uso de produtos químicos usados nas aquaculturas e avaliar os seus efeitos nocivos para organismos aquáticos. Uma vez que mais de 80% da produção mundial de organismos aquáticos está concentrada no sudoeste da Ásia, foi dada especial atenção à aquacultura nessa região, particularmente na Tailândia. Três diferentes cenários foram considerados: aquaculturas de camarão, aquaculturas de tilápias cultivadas em gaiolas e em tanques escavados no solo. Em cada tipo foram realizados inquéritos e campanhas de monitoramento em várias aquaculturas nas quais foram averiguados o uso, destino e forma de aplicação de químicos. Os resultados indicaram o uso excessivo/inapropriado de alguns compostos, nomeadamente de antibióticos (em aquaculturas em gaiolas), de desinfectantes (em aquaculturas de camarão) e de 1,7α-metiltestosterona (MT) (em aquacultura de tilápias em tanques escavados). Os resultados das campanhas de monitorização mostraram que o uso excessivo de produtos químicos resulta na contaminação do meio ambiente com antibióticos (oxitetraciclina (OTC) e enrofloxacina (ENR)) nas aquaculturas em gaiola, e com MT nas aquaculturas de tilápias em tanques escavados. No laboratório, foram realizados ensaios de ecotoxicidade com antibióticos, desinfectantes e pesticidas usando organismos modelo pertencentes a diferentes níveis tróficos. Foram testados os desinfectantes, cloreto de benzalcónio (BKC), gluconato de clorexidina, e glutaraldeído (GA) sendo que os dois primeiros demonstraram ser muito tóxico para consumidores primários e secundários. Para uma análise integrada foi utilizada uma abordagem baseada nas distribuições de sensibilidade das espécies (DSE) com a qual se estimaram as concentrações perigosas (CP) para 5% e 50% das espécies após e exposição ao BKC e GA. O grupo dos produtores primários foi o grupo mais sensível à exposição ao BKC com CP5% = 10,8 μg/l enquanto para GA não foram encontradas diferenças de sensibilidade entre os grupos tróficos e, assim sendo, um valor geral de CP5% = 300 μg/l foi obtido. Além disso, uma análise probabilística dos riscos ambientais indicou uma fracção de espécies potencialmente afectada (FAPE) pelo BKC > 5% em efluentes e águas superficiais. Os pesticidas estudados foram o trichlorfon (TCF) e a ivermectina (IVM). O TCF foi extremamente tóxico para dafnídeos (48h-LC50 = 0,29 μg/l) e afectou também a actividade de acetilcolinesterase em D. magna e D. rerio. A IVM foi tóxica para adultos, juvenis e embriões de D. rerio (96h- CL50 = 18,5 μg/l para os juvenis) afectando o seu desenvolvimento e actividade de biomarcadores. Em exposições crónicas, IVM causou alterações no comportamento e crescimento em D. rerio juvenis (21d-LOEC <0,25 μg/l). Os antibióticos amoxicilina e OTC apresentam baixa toxidade para os organismos aquáticos, mas ambos induziram enzimas relacionadas estresse oxidativo em adultos e embriões de D. rerio. Em geral, a maioria dos químicos testados apresentaram toxicidade para algum grupo de organismo da cadeia trófica ou tiveram efeito a nível de parâmetros sub-letais, sendo portanto recomendados estudos de exposição crónica para que se possa refinar a avaliação de risco ambiental destes compostos. Os efeitos letais e sub-letais observados nos organismos não-alvo sugerem que pode haver uma perda da biodiversidade nos ecossistemas aquáticos, e assim, comprometer os serviços prestados pelos ecossistemas num futuro próximo. Sendo o sucesso da aquacultura dependente directo destes serviços (por exemplo, água de alta qualidade), há uma necessidade urgente de medidas de controlo/educação, tanto no uso de produtos químicos na aquacultura e monitoramento/mitigação dos impactos negativos destes nos ecossistemas naturais.
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Vilariño-Güell, Carles. "Analysis of germline mutations induced by chemicals." Thesis, University of Leicester, 2002. http://hdl.handle.net/2381/9415.
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The high abundance of chemical pollutants in the environment represents a genetic risk to humans. The development of reliable and sensitive tests for the analysis of the genetic effects of exposure to chemical mutagens is required. Previous work has shown that expanded simple tandem repeat (ESTR) loci provide a sensitive system for monitoring radiation-induced mutation in the mouse germline. Here, the results of the first systematic study on germline mutation induction at mouse ESTR loci by chemical mutagens are presented. Mutation rates at two ESTR loci were studied in the germline of male mice exposed to two monofunctional alkylating agents, ethyl-nitrosourea (ENU) and isopropyl methanesulfonate (iPMS), as well as to the topoisomerase-II inhibitor, etoposide (ET). Pre-meiotic exposure to alkylating agents resulted in a highly significant increase in ESTR mutation rate, but did not alter post-meiotically exposed cells. Pre-meiotic mutation induction by ENU and iPMS was linear within the interval of doses from 12.5 mg/kg to 25 mg/kg and reached a plateau at higher concentrations. Paternal exposure to etoposide resulted in ESTR mutation induction at meiotic stages but did not affect post- or pre-meiotic cells. The pattern of ESTR mutation induction after pre-meiotic and meiotic exposure to chemical mutagens was similar to that previously obtained by various traditional approaches for monitoring germline mutation in mice. Using microarrays, the analysis of the pattern of changes in gene expression in the testis of male mice exposed to ENU was studied. This analysis revealed that exposure to this chemical mutagen does not result in detectable changes in gene expression. The results of this study show that ESTR loci provide a new and efficient biomonitoring system for assessing the genetic effects of chemical mutagens, capable of detecting increases in mutation rates at very low doses and in small sample sizes.
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Levandoski, Karen A. "Transference of occupational chemicals through breast milk." Online version, 2002. http://www.uwstout.edu/lib/thesis/2002/2002levandoskik.pdf.
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Siordia, Jimena Carolina. "Analysis of Toxic Chemicals Affecting the Oocyte." Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/192989.
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Wang, Guangyao (Sam), Randy Norton, and Shawna Loper. "Choosing Harvest Aid Chemicals for Arizona Cotton." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2012. http://hdl.handle.net/10150/225859.
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Jana, S. K. "Synthesis of fine chemicals using heterogenous catalysts." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2001. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2337.
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Cabana, Teri. "The Total Picture: Multiple Chemical Exposures to Pregnant Women in the US – An NHANES Study of Data from 2003 through 2010." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3504.
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INTRODUCTION: Chemical exposures to US pregnant women have been shown to have adverse health impacts on both mother and fetus. A prior paper revealed that US pregnant women in 2003-2004 had widespread exposure to multiple chemicals. The goal of this research is to examine how environmental chemical exposures to US pregnant women have changed from 2003 to 2010 and to look further at the extent of simultaneous exposure to multiple chemicals in US pregnant women using biomonitoring data available through NHANES (the National Health and Nutritional Examination Survey). METHODS: Using available NHANES data from the following cycles (2003-2004, 2005-2006, 2007-2008, 2009-2010), we analyzed how environmental chemical exposures changed over time. Covariates were used and data was weighted to reflect the population of pregnant US women. Each cycle was then compared to the 2003-2004 cycle in order to assess how exposures have changed over time. We then looked at the data in an entirely different fashion. We examined the total number of chemicals detected in a given pregnant woman by chemical group. Finally, we looked at the total number of detects across various chemical groups and used the Fisher Exact Test to study how the distribution of detections changed in 2009-2010 compared to 2003-2004. RESULTS: While at least one-third of the chemicals analyzed showed one cycle that differed, exposure rates of individual chemicals were generally not increasing from 2003-2010. Median number of detections over chemical groups also did not show much difference over time. However, analysis of the change in frequency distributions revealed that, for some chemical groups, the frequency of detects in US pregnant woman significantly increased in 2010 compared to 2003. CONCLUSIONS: Widespread chemical exposures were seen in US pregnant women from 2003 through 2010. The number of chemical analytes detected in US pregnant women’s bodies is rising. Many chemicals studied had similar mechanisms of action and/or similar adverse health outcomes upon exposure which is known to result in a cumulative health effect. This research suggests that we need to focus not only on exposure rates of individual chemicals but also on the overall number of chemicals detected when assessing the overall picture of environmental chemical exposures to pregnant women in the US.
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Chung, Elena Yin-Yin. "Investigation of Chemical Looping Oxygen Carriers and Processes for Hydrocarbon Oxidation and Selective Alkane Oxidation to Chemicals." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469182957.
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Casa, Maria V. "Accumulation of Emerging Chemicals in Southern Hemisphere Humpback Whales (Megaptera novaeangliae) and Species-specific Chemical Effect Assessment." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/411890.
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Millions of hazardous chemicals are synthesized each year. Their release often represents a risk for the environment and biota. As part of a broader effort to investigate the accumulation and effect of emerging chemicals of concern in the Antarctic sea-ice ecosystem, this thesis focuses upon exposure and effect assessment in southern hemisphere (SH) humpback whales (Megaptera novaeangliae). Cetaceans traditionally represent ideal targets for exposure assessment to Persistent Organic Pollutants (POPs), that is chemicals identified as persistent, bioaccumulative, toxic and capable of long-range environmental transport. Their extended life span and high proportion of body fat render cetaceans susceptible to accumulation of elevated burdens. Southern hemisphere humpback whales feed almost exclusively on Antarctic krill (Euphasia superba) and thus represent second order consumers of the Antarctic sea-ice ecosystem. Exposure assessment consisted of targeted analysis of short-chain chlorinated paraffins (SCCPs) included under the Stockholm Convention (SC) in 2017, and brominated structures listed in 2009 as well as novel, naturally occurring brominated structures, already detected at lower trophic levels of the Antarctic sea-ice ecosystem. SCCPs were targeted in stranded specimens and were detected in 77.7 % of samples, representing the first detection of SCCPs in any mysticetes or any Antarctic foraging marine mammal.Blubber samples from free-swimming and stranded specimens were dedicated to the analysis of the modern category of POPs, polybromodiphenilethers (PBDEs), and a naturally occurring brominated compound, 2,4,6-tribromoanysole (TBA), the chemical structure of which closely resembles PBDEs, flagging the possibility of similar toxic action. Humpback whale PBDEs profiles were dominated by tetra- and penta- congeners, supporting a single previous study on PBDE accumulation in Southern hemisphere humpback whales feeding in the Antarctic Peninsula region. Further, the detection of decaBDE adds support for the local emissions or particle bound transport to Antarctica. PBDE congeners were detected in all samples analysed, whilst TBA was 88 detected in 80% of samples. Upon establishing accumulation of three novel chemical groups in the Antarctic sea-ice ecosystem, species-specific effect assessment was performed through cytotoxicity assessment implementing the newly established immortalized humpback whale fibroblast cell line (HuWaTERT). Two endpoints were targeted, namely membrane integrity and metabolic activity following 24h exposure to an SCCP cocktail, BDE-47, BDE-99, TBA. Each assay also incorporated the assay reference chemical, p,p’-DDE. The four chemicals did not show a dose-dependent response comparable to the one produced by the reference chemical. Whilst p,p’-DDE induced a decrease of both metabolic activity and membrane integrity, the cell response to BDE-99 indicated a positive, or potentially hermetic relationship with regards to the metabolic activity, warranting further investigation of underlying mechanisms.The final thesis chapter explores the unique potential of HuWaTERT for the generation of induced pluripotent stem cells (iPSCs). The main objective of this work was to generate a source of a number of different cell lines from the iPSCs, that could be applied for a more tailored approach to in-vitro chemical effect evaluation to fill the gap currently existing in the field of cetacean toxicology. The re-generation trial involved the use of the Sendai virus, which induces the de-differentiation mechanism in HuWaTERT to become iPSCs without integrating into the cell genome. After successfully generating a number of iPC colonies, the cells ultimately did not thrive, likely due to a fungal infection. Overall, this thesis combines both chemical exposure and effect assessment of novel chemical groups, for unique insight into chemical accumulation and impact in the Antarctic sea-ice ecosystem. The work provides new information regarding the range of chemicals that Antarctic consumers are exposed to, a reflection of hemispheric chemical usage and local input, and also contributes invaluable species-specific in vitro toxicity assessment data, which represents a critical research gap for cetacean chemical impact assessment.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Adesina, Olumide, Cassandra T. Eagle, Ayobami Olukanni, and Reza Mohseni. "Purification of Cyclohexene for Cyclopropanation Reactions." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/143.
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Environmentally friendly reactions yielding cis-cyclopropanes are desired in the insecticide industry as these are most effective at reducing the population of insects while remaining benign to the environment. We are exploring the best parameters for the most effective cis-cyclopropanation reactions. An alkene and a diazo compound react together in the presence of a dirhodium catalyst to produce cyclopropanes. First however, the starting materials must be pure. Alfa Aesar supplies cyclohexene which is reported to be 99% pure, however, Gas column chromatography/Mass spectroscopy reveals that the sample is only 3% cyclohexene. Using an adopted published procedure, we discovered that distillation under nitrogen produces cyclohexene in greater than 95% pure. This is suitable for use in cyclopropanation reactions.
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Lough, Kerry Frances. "The Short and Long-term Effects of Herbicide Application in Maine Clearcuts on Ant Communities (Hymenoptera: Formicidae)." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/LoughKF2003.pdf.
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