Dissertations / Theses: 'PCDF'

1

Yang, Yun. "Temperature dependent PCDD/PCDF product distributions from phenols." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20182.

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2

Moore, Paul 1962. "The Analysis of PCDD and PCDF Emissions from the Cofiring of Densified Refuse Derived Fuel and Coal." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc330690/.

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The United States leads the world in per capita production of Municipal Solid Waste (MSW), generating approximately 200 million tons per year. By 2000 A.D. the US EPA predicts a 20% rise in these numbers. Currently the major strategies of MSW disposal are (i) landfill and (ii) incineration. The amount of landfill space in the US is on a rapid decline. There are -10,000 landfill sites in the country, of which only 65-70% are still in use. The Office of Technology Assessment (OTA) predicts an 80% landfill closure rate in the next 20 years. The development of a viable energy resource from MSW, in the form of densified Refuse Derived Fuel (dRDF), provides solutions to the problems of MSW generation and fossil fuel depletions. Every 2 tons of MSW yields approximately 1 ton of dRDF. Each ton of dRDF has an energy equivalent of more than two barrels of oil. At current production rates the US is "throwing away" over 200,000,000 barrels of oil a year. In order to be considered a truly viable product dRDF must be extensively studied; in terms of it's cost of production, it's combustion properties, and it's potential for environmental pollution. In 1987 a research team from the University of North Texas, in conjunction with the US DOE and Argonne National Laboratory (ANL), cofired over 550 tons of dRDF and bdRDF with a high sulfur Kentucky coal in a boiler at ANL. This work examines the emission rates of polychlorinated dioxins (PCDDs) and furans (PCDFs) during the combustion of the dRDF, bdRDF, and coal. Even at levels of 50% by Btu content of dRDF in the fuel feedstock, emission rates of PCDDs and PCDFs were below detection limits. The dRDF is shown to be an environmentally acceptable product, which could help resolve one of the major social and environmental problems facing this country today.

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3

Weber, P. [Verfasser]. "Der Chlortransfer bei der Bildung von polychlorierten organischen Spurenstoffen (PCDD/PCDF) in industriellen thermischen Prozessen (Müllverbrennung) / P. Weber." Karlsruhe : KIT-Bibliothek, 2000. http://d-nb.info/1198219823/34.

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4

Stark, Marie Luise [Verfasser]. "Transfer von Dioxinen (PCDD), Furanen (PCDF) und polychlorierten Biphenylen (PCB) aus dem Futter in ausgewählte Gewebe wachsender Schafe / Marie Luise Stark." Berlin : Freie Universität Berlin, 2021. http://nbn-resolving.de/urn:nbn:de:kobv:188-refubium-31051-8.

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5

Quinn, Laura Penelope. "Persistent organic pollutants (POPs) in soil associated with an active incinerator in Potchefstroom, South Africa / L.P. Quinn." Thesis, North-West University, 2005. http://hdl.handle.net/10394/1013.

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POPs are a group of chemicals that have been extensively studied over the last few years. The main reason that these chemicals have received so much scientific attention is the myriad of negative effects they have on the environment and human health. The properties that cause the deleterious effects include a high molecular stability, rendering them highly persistent. Added to this is the lipophilic and hydrophobic nature of the compounds. POPs will thus tend to bio-accumulate and bio-magnify in the environment, causing a direct threat to humans and wildlife. To address this threat, the Stockholm Convention on Persistent Organic Pollutants, under the supervision of United Nations Environment programme (UNEP), was initiated and became legally binding on 17 May 2004. All countries, including South Africa, which ratified this agreement, will be expected to monitor and regulate the formation of POPs. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are all members of the dioxin-like family of POPs. This family of chemicals pose serious health threats such as carcinogenic effects and negative effects on reproduction. These substances, with the exception of PCBs, are formed unintentionally as by-products of industrial and thermal processes. One of the main sources of dioxin-like chemicals is medical waste incinerators. In this project the area surrounding a medical waste incinerator was monitored using a bio-assay technique. The determination of dioxin concentrations is usually preformed by chemical analysis, however, bio-assays have proven themselves to be a cheaper and time-saving screening method. The Toxic Equivalency Quotient (TEQs) determined through bio-assays can support chemical analysis in determining biologically-relevant risk assessments since bio-assay data has ecotoxicological relevance. These assays represent an integrated biological response to chemical pollutants, where biological effects are accounted for which is not possible in chemical analyses. One of the bio-assays used in the determination of the dioxin-like chemical TEQ is the H411 E reporter gene bio-assay. This assay is based on the Ah-receptor mediated toxicity of dioxin-like chemicals. Using this technique the TEQs for areas surrounding an active incinerator were determined, to indicate the distribution of these substances. The TEQs for the soil samples collected ranged between nondetectable and 154 ngTEQ/kg. There was no clear distributional pattern and the total organic carbon content in the soil did not seem to play a crucial role in the distribution of dioxin-like chemicals. Although a decrease in soil tillage showed a corresponding increase in TEQ. The predominant wind direction was taken into account but no correlation could be seen. However, meteorological parameters such as the ambient temperature and low precipitation in the area may have contributed to lower TEQ values. Cytotoxicity excluded data points and the phenomenon has to be addressed. High TEQ values in a residential area where free-range chickens are raised pose a serious concern to the level of dietary dioxin-like chemical intake. Eggs in the area could theoretically contain between 2.75 and 28.75 pgTEQ/g egg fat. Further studies are needed to determine how much dioxin-like chemicals are being transferred to humans through the consumption of free-range eggs
Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

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6

Gaus, Caroline, and n/a. "Dioxins in the Marine Environment: Sources, Pathways and Fate of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Queensland, Australia." Griffith University. School of Public Health, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030624.144111.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans(PCDFs) are two groups of lipophilic, persistent organic pollutants that are produced as by-products of various anthropogenic and industrial processes. Due to their relatively high toxic potencies and potential to bioaccumulate and biomagnify in organisms and through the food chain, the contemporary widespread distribution of these compounds is a concern to the health of the environment, wildlife and humans. This study determined the distribution, pathways and fate of PCDD/Fs in the coastal zone of Queensland, Australia, including the inshore marine environment of the World Heritage Great Barrier Reef Marine Park. This ecosystem supports unique fauna and flora such as the marine herbivorous mammal dugong (Dugong dugon) and its food source, seagrass. Elevated PCDD/Fs were present in soils and sediments along the entire Queensland coastline. Highest concentrations were found in soil from agricultural irrigation drains and in sediments near the mouths of major rivers. Elevated concentrations were associated with rural and urban types of land-use, and PCDD/Fs were present even in locations remote from anthropogenic activities. PCDD/F congener-specific analysis revealed an unusual profile in all samples, dominated by OCDD, with PCDFs present in low concentrations or below the limit of detection. Distinct HxCDD isomer patterns were observed, with the 1,2,3,7,8,9-HxCDD/1,2,3,4,6,7-HxCDD isomer pair dominating the 2,3,7,8-substituted HxCDDs. Similar congener and isomer characteristics were reported in sediments, soil and clay samples from other continents, but could not be attributed to any known source. Possible PCDD/F sources in Queensland were assessed using segmented estuarine sediment cores, for which radiochemical chronologies were established for each depth. Variations of PCDD/F concentrations in the sediment cores over several centuries of depositional history were relatively small. Elevated PCDD levels were still present in sediment slices from the early 17th century. PCDD/F homologue profiles in sediments deposited during the last 350 years were almost identical and correlated well to the characteristic profiles observed in surface sediments and soils from the entire Queensland coastline. These results suggested the presence of an unidentified PCDD source prior to the production of commercial organochlorine products. To investigate the formation of the unusual PCDD/F profiles, congener and isomer specific analyses were undertaken in soils, sediments and dated sediment cores. The results demonstrated that specific transformation processes in the environment have resulted in the observed PCDD profile characteristics. Dechlorination of OCDD was proposed to result in distinct 1,4-pattern characteristics (i.e. formation of isomers chlorinated in the 1,4,6,9-positions). Consequently, the environmental samples do not reflect the signatures of the original source. An alternative hypothesis to natural formation is discussed evaluating these processes and their implications for possible source contributions. This hypothesis explores the potential for the influence of anthropogenic PCDD precursors (e.g. pentachlorophenol) during the 1940s to 1990s. Transport of PCDD/Fs from the land-based source via impacted tributary river systems, and subsequent deposition processes are proposed to result in PCDD/F accumulation in the inshore marine ecosystem. The extent of the sediment PCDD/F contamination governs the concentrations in the extensive inshore marine seagrass meadows of Queensland. Partitioning processes in the sediment-seagrass system lead to increased toxic equivalency (TEQ) in the seagrass, compared to sediment.The relationship between contaminated inshore sediments, seagrass and dugongs were evaluated using six dugong habitat regions along the coastline. PCDD/F body burdens in dugongs are governed by sediment (and seagrass) PCDD/F concentrations in their habitat. High seagrass (and incidental sediment) ingestion rates, selective retention of toxicologically potent congeners and relatively low PCDD/F elimination capacities in dugongs are proposed to result in elevated PCDD/F concentrations and TEQ levels in adult animals. Transfer efficiencies of 4 and 27% of maternal TEQ levels to foetuses and calves (respectively) during gestation and lactation result in relatively high exposure potentials to offspring. Compared to no-observed-adverse-effect-levels in other mammals, and based on the results of this study, a tolerable daily intake (TDI) of 10-24 pg TEQ kg-1 day-1 was estimated for dugongs. The results of the present study found that dugongs from some regions along the coastline of Queensland exceed this TDI by up to 20 fold, suggesting that these populations may be at risk from PCDD/F contamination in their habitat. These results have important implications for the health of the environment, wildlife and humans and were used to develop a conceptual understanding of the sources, pathways and fate of dioxins in Queensland, Australia.

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7

Gaus, Caroline. "Dioxins in the Marine Environment: Sources, Pathways and Fate of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Queensland, Australia." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367537.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans(PCDFs) are two groups of lipophilic, persistent organic pollutants that are produced as by-products of various anthropogenic and industrial processes. Due to their relatively high toxic potencies and potential to bioaccumulate and biomagnify in organisms and through the food chain, the contemporary widespread distribution of these compounds is a concern to the health of the environment, wildlife and humans. This study determined the distribution, pathways and fate of PCDD/Fs in the coastal zone of Queensland, Australia, including the inshore marine environment of the World Heritage Great Barrier Reef Marine Park. This ecosystem supports unique fauna and flora such as the marine herbivorous mammal dugong (Dugong dugon) and its food source, seagrass. Elevated PCDD/Fs were present in soils and sediments along the entire Queensland coastline. Highest concentrations were found in soil from agricultural irrigation drains and in sediments near the mouths of major rivers. Elevated concentrations were associated with rural and urban types of land-use, and PCDD/Fs were present even in locations remote from anthropogenic activities. PCDD/F congener-specific analysis revealed an unusual profile in all samples, dominated by OCDD, with PCDFs present in low concentrations or below the limit of detection. Distinct HxCDD isomer patterns were observed, with the 1,2,3,7,8,9-HxCDD/1,2,3,4,6,7-HxCDD isomer pair dominating the 2,3,7,8-substituted HxCDDs. Similar congener and isomer characteristics were reported in sediments, soil and clay samples from other continents, but could not be attributed to any known source. Possible PCDD/F sources in Queensland were assessed using segmented estuarine sediment cores, for which radiochemical chronologies were established for each depth. Variations of PCDD/F concentrations in the sediment cores over several centuries of depositional history were relatively small. Elevated PCDD levels were still present in sediment slices from the early 17th century. PCDD/F homologue profiles in sediments deposited during the last 350 years were almost identical and correlated well to the characteristic profiles observed in surface sediments and soils from the entire Queensland coastline. These results suggested the presence of an unidentified PCDD source prior to the production of commercial organochlorine products. To investigate the formation of the unusual PCDD/F profiles, congener and isomer specific analyses were undertaken in soils, sediments and dated sediment cores. The results demonstrated that specific transformation processes in the environment have resulted in the observed PCDD profile characteristics. Dechlorination of OCDD was proposed to result in distinct 1,4-pattern characteristics (i.e. formation of isomers chlorinated in the 1,4,6,9-positions). Consequently, the environmental samples do not reflect the signatures of the original source. An alternative hypothesis to natural formation is discussed evaluating these processes and their implications for possible source contributions. This hypothesis explores the potential for the influence of anthropogenic PCDD precursors (e.g. pentachlorophenol) during the 1940s to 1990s. Transport of PCDD/Fs from the land-based source via impacted tributary river systems, and subsequent deposition processes are proposed to result in PCDD/F accumulation in the inshore marine ecosystem. The extent of the sediment PCDD/F contamination governs the concentrations in the extensive inshore marine seagrass meadows of Queensland. Partitioning processes in the sediment-seagrass system lead to increased toxic equivalency (TEQ) in the seagrass, compared to sediment.The relationship between contaminated inshore sediments, seagrass and dugongs were evaluated using six dugong habitat regions along the coastline. PCDD/F body burdens in dugongs are governed by sediment (and seagrass) PCDD/F concentrations in their habitat. High seagrass (and incidental sediment) ingestion rates, selective retention of toxicologically potent congeners and relatively low PCDD/F elimination capacities in dugongs are proposed to result in elevated PCDD/F concentrations and TEQ levels in adult animals. Transfer efficiencies of 4 and 27% of maternal TEQ levels to foetuses and calves (respectively) during gestation and lactation result in relatively high exposure potentials to offspring. Compared to no-observed-adverse-effect-levels in other mammals, and based on the results of this study, a tolerable daily intake (TDI) of 10-24 pg TEQ kg-1 day-1 was estimated for dugongs. The results of the present study found that dugongs from some regions along the coastline of Queensland exceed this TDI by up to 20 fold, suggesting that these populations may be at risk from PCDD/F contamination in their habitat. These results have important implications for the health of the environment, wildlife and humans and were used to develop a conceptual understanding of the sources, pathways and fate of dioxins in Queensland, Australia.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Public Health
Faculty of Health Sciences
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8

Lundin, Lisa. "Formation and degradation of PCDD/F in waste incineration ashes." Doctoral thesis, Umeå : Department of Chemistry, Umeå University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1395.

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9

Gao, Qiuju. "Dioxins and dioxin-like compounds in thermochemical conversion of biomass : formation, distribution and fingerprints." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-118861.

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In the transition to a sustainable energy supply there is an increasing need to use biomass for replacement of fossil fuel. A key challenge is to utilize biomass conversion technologies in an environmentally sound manner. Important aspects are to minimize potential formation of persistent organic pollutants (POPs) such as dioxins and dioxin-like compounds. This thesis involves studies of formation characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) in microwave-assisted pyrolysis (MAP) and torrefaction using biomass as feedstock. The research focuses are on their levels, distributions, fingerprints (homologue profiles and isomer patterns) and the underlying formation pathways. The study also included efforts to optimize methods for extracting chlorinated aromatic compounds from thermally treated biomass. The overall objective was to contribute better understanding on the formation of dioxins and dioxin-like compounds in low temperature thermal processes. The main findings include the following: Pressurized liquid extraction (PLE) is applicable for simultaneous extraction of PCDDs, PCDFs, PCNs, polychlorinated phenols and benzenes from thermally treated wood. The choice of solvent for PLE is critical, and the extraction efficiency depends on the degrees of biomass carbonization. In MAP experiments PCDDs, PCDFs and PCNs were predominantly found in pyrolysis oils, while in torrefaction experiments they were mainly retained in solid chars with minor fractions in volatiles. In both cases, highly chlorinated congeners with low volatility tended to retain on particles whereas the less chlorinated congeners tended to volatize into the gas phase. Isomer patterns of PCDDs, PCDFs and PCNs generated in MAP were more selective than those reported in combustion processes. The presence of isomers with low thermodynamic stability suggests that the pathway of POPs formation in MAP may be governed not only by thermodynamic stabilities but also by kinetic factors. Formation of PCDDs, PCDFs and PCNs depends not only on the chlorine contents in biomass but also the presence of metal catalysts and organic/metal-based preservatives. Overall, the results provide information on the formation characteristics of PCDDs, PCDFs and PCNs in MAP and torrefaction. The obtained knowledge is useful regarding management and utilization of thermally treated biomass with minimum environmental impact.

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10

Swiegelaar, Caitlin Reneé. "The effect of different sample preparatory protocols on the induction of the aryl hydrocarbon receptor (AhR) in the H4IIE-luc reporter gene bio-assay / Caitlin Reneé Swiegelaar." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9702.

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Concern on a global scale gave rise to the founding of the Stockholm Convention on persistent organic pollutants (POPs) with a view to restrict the use and production of these toxic chemicals. As a signatory, South Africa is legally bound to abide to the Convention’s objectives, including participating in relevant research and monitoring. However, developing countries such as South Africa have limited information concerning POPs, partially because these countries do not have sufficient analytical capabilities, and thus method development and refinement are necessary. One group of POPs consisting of polychlorinated dibenzo-pdioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs), collectively referred to as dioxins, are of particular concern due to their high toxicity and persistence. Additionally, the analysis of dioxins is recognised as one of the most analytically challenging of its kind. This study investigated the effect of different preparatory protocols on the semi-quantification of dioxins using the H4IIE-luc-reporter gene assay. The protocols evaluated were either Soxhlet or pressurised liquid extraction (PLE) combined with a manual acid digestion, gel permeation chromatography (GPC) and Florisil fractionation clean-up procedure as well as the automated Total Rapid Prep™(TRP) system which makes use of a PLE combined with a multi-layer silica, alumina and carbon column clean-up procedure. To evaluate the protocols, an eight point matrix matched calibration curve, two soil samples and a certified reference material (CRM) were used. The extracts were semi-quantified by the H4IIE-luc bio-assay. During the course of the assay, the appropriateness of different standards was investigated, and a mixed standard containing all 17 toxic PCDD/Fs was chosen for quantification. During the data review process, higher bioassay equivalent (BEQ) values were obtained from PLE compared to Soxhlet extraction, while no statistically significant difference (Kruskal-Wallis ANOVA: p > 0.05) was found between the assay quantifications for the different preparatory techniques. However, the results of the H4IIE bio-assay were larger than the expected values. The identity of the chemicals that were in all likelihood responsible for the higher response was investigated through instrumental analysis using comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). Instrumental results indicated a high level of PAHs in the extracts, which could lead to super induction of the aryl hydrocarbon receptor (AhR) and therefore, to a positive bias in the results. Instrumental screening proved that all selected preparatory protocols were inadequate at removing interfering compounds and not sufficiently selective for PCDD/Fs, although the TRP was more successful in removing interferences. The high matrix interference hindered peak identification. Additionally, as indicated by instrumental analysis, the weak recovery of PCDD/Fs could be ascribed to high evaporation temperatures. The effect of different reference standards in the H4IIE bio-assay used during semi-quantification needs further investigation; similarly, the optimisation of extraction, evaporation and clean-up protocols and the use of different GCxGC-TOFMS column combinations aimed at more efficient separation needs to be investigated. The assistance of the National Metrology Institute (funded through the Department of Trade and Industry) towards this research is hereby acknowledged.
Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

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11

Weidemann, Eva. "Waste incineration residues : Persistent organic pollutants in flue gas and fly ash from waste incineration." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-92765.

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Modern societies produce large quantities of municipal solid waste (MSW), which is commonly disposed of by incineration. This has several advantages: it reduces the waste’s volume and sterilizes it while also enabling energy recovery. However, MSW incineration has some notable disadvantages, the most widely debated of which is probably the production and release of persistent organic pollutants (POP) such as polychlorinated dibenzofurans (PCDF), dibenzo-p-dioxins (PCDD), biphenyls (PCB) and naphthalenes (PCN). Of the 210 PCDF and PCDD congeners, 17 are toxic, with hormone-disrupting and carcinogenic properties. Twelve of the 209 PCB congeners and at least 2 of the 75 PCN also exhibit such properties. These POP form in the post-combustion zones of MSW incineration plants and are removed from the flue gas using filtering devices that trap them in the fly ash This thesis concerns the formation and degradation of POP in processes related to MSW incineration. The first paper describes a case study in which PCDD were forming in filters designed to remove them from flue gases, causing emission-related issues in a full-scale MSW incineration plant. It was shown that the PCDD formation was probably due to chlorophenol condensation on the filters’ surfaces. The second paper describes the validation of a cooling probe designed to prevent POP formation during high temperature (>450 °C) flue gas sampling. The results obtained also confirmed that PCDF and PCDD formation takes place at temperatures below 600 °C. In the third paper, three different fly ashes were subjected to thermal treatment under an inert atmosphere in a rotary kiln and in sealed ampoules at 400 °C. The concentrations, degrees of chlorination and congener profiles of the POP in the treated ashes and emitted gases were compared to those for the untreated ashes. The trends observed for PCDF mirrored those for PCN, while the trends for PCDD closely resembled those for PCB. The PCDF congener profiles of the kiln ash were similar regardless of the initial ash composition, suggesting that the mechanisms of PCDF formation were similar in all cases. The fourth paper describes the surface characterization of the three fly ashes studied in paper three by SEM, EDX, XPS and XRD. In addition, the thermal desorption and subsequent degradation of POP from the ashes was studied at temperatures of 300-900 °C. The composition of the gases released as the temperature increased differed between the ashes and depended on their composition. Doping experiments using isotopically labelled PCDF and PCDD suggests that PCDD desorbed at lower temperatures than PCDF. This thesis examines several problems relating to POP formation during MSW incineration, from sampling to the ultimate fate of incineration residues. The results obtained illustrate the wide range of processes that contribute to thermal POP formation and degradation during and after MSW incineration.
Förbränning av hushållssopor är en vanlig metod för att hantera ett växande avfallsproblem. Metoden har flera fördelar, såsom minskning av volym och vikt, sterilisering och energiåtervinning. Sopförbränning har dock vissa nackdelar och det mest debatterade är sannolikt utsläpp av persistenta organiska föroreningar (POPs) som polyklorerad dibensofuran (PCDF), dibenso-p-dioxin (PCDD), bifenyl (PCB) och naftalen (PCN). Det finns totalt 210 PCDF- och PCDD- kongener, med mellan ett till åtta klor på kolskelettet, varav 17 är giftiga med hormonstörande och cancerframkallande egenskaper. Även tolv av totalt 209 PCB-kongener samt minst två av totalt 75 PCN-kongener uppvisar liknande egenskaper. Dessa klorerade organiska föroreningar bildas då rökgaserna kyls ner i sopförbränningsanläggningarna och avlägsnas från rökgaserna med hjälp av filter och hamnar i flygaskan. Denna avhandling handlar om bildning och nedbrytning av POPs i sopförbränningsrelaterade processer. Den första artikeln är en fallstudie där PCDD bildas i filtren i en fullskalig sopförbränningsanläggning. Bildningen ledde till förhöjda halter organiska föroreningar i rökgaserna, vilket ledde till ökade utsläpp. Den funna bildningsvägen för PCDD i filtren befanns sannolikt bero på kondensation av klorfenoler på filterytorna. Den andra artikeln är en valideringsstudie av en kylprob avsedd att användas vid rökgasprovtagning vid hög temperatur (> 450 °C) för att undvika bildning av POPs under provtagningen. Studien bekräftade att majoriteten av PCDF- och PCDD- bildning i rökgaser från sopförbränning sker vid temperaturer under 600 °C. I den tredje artikeln berättas om behandling av tre olika flygaskor från olika sopförbränningsanläggningar. Askorna behandlades vid 400 °C i inert atmosfär i både en roterugn och i förseglade ampuller. De resulterande koncentrationerna, kloreringsgraderna och kongenprofilerna av de organiska föroreningarna jämfördes. Likheter hittades mellan PCDF och PCN, medan PCDD och PCB betedde sig på ett annat sätt. Studien fann också att PCDF kongenprofiler i aska som behandlats i roterugnen liknade varandra, oberoende av askornas sammansättning, vilket tyder på en liknande bildningsväg. För den fjärde artikeln, genomfördes ytkarakterisering (SEM, EDX, XPS och XRD) på de tre flygaskorna från artikel tre som sedan hettades upp från 30 °C till 900 °C i vacuum. Det som frigjordes på grund av uppvärmningen samt nedbrytningsprodukter från askorna studerades med hjälp av masspektrometri och infraröd spektroskopi. Studien fann att de gaser som frigjordes när temperaturen ökade skilde mellan askorna, beroende på deras sammansättning. Studien fann också att när aska dopad med isotopmärkt PCDF och PCDD utsattes för samma behandling, frigjordes PCDD vid lägre temperatur än PCDF. Denna avhandling berör flera aspekter av problematiken kring klorerade organiska föroreningar som bildas vid sopförbränning, från provtagning till hur man ska hantera flygaskan. Avhandlingen belyser även olika typer av bildning och nedbrytning av POPs i varma processer kopplade till sopförbränning.

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Prange, Joelle, and n/a. "Origin of Dioxins in Queensland: Investigations into the Distribution and Sources of Polychlorinated Dibenzo-P-Dioxins in the Queensland Terrestrial Environment." Griffith University. School of Public Health, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040615.161651.

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Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are persistent organic pollutants of global concern as they are persistent, toxic and can biomagnify through the food chain. PCDD/Fs are generally regarded as trace contaminants in a number of chemical products and they are formed as by-products from various industrial, chemical and combustion processes. The pollution with PCDD/Fs occurs with the release of these chemicals into the environment, resulting in the contamination of various compartments including; air, soil, sediment and biota. Studies that have investigated the distribution of PCDD/Fs in the environment suggest that the highest concentrations of these pollutants are found in locations with a history of industrial or chemical PCDD/F sources. Queensland is the north-eastern state of Australia. Queensland has a low population density, few industrial activities and is considered predominantly rural. Therefore it was somewhat surprising that elevated concentrations of PCDD/Fs (in particular the higher chlorinated PCDDs) have been observed in soil and sediments samples collected from various locations along the Queensland coast. The concentrations of PCDDs in Queensland samples were comparable to or higher than concentrations in similar matrices from highly polluted regions elsewhere. To investigate the origin of PCDDs in Queensland, the geographical distribution of PCDD/Fs in topsoil was investigated in the coastal and inland environments to provide information on the potential sources and to estimate the extent of the PCDD contamination. Distinct east-west gradients were detected in topsoil collected from bushland areas across the state with elevated PCDD concentrations confined to the coastal region. Within the coastal region, the contamination could not be associated with specific land uses. In fact, the PCDD/F congener profile was similar in the majority of samples from the coastal region, with a dominance of the higher chlorinated PCDDs (in particular OCDD), whereas PCDFs were low or below the limit of detection. The similarity in the PCDD/F congener profiles in the soils along the coastal region indicated that a source of PCDDs of similar origin has resulted in the contamination of soil extending more than 3000 km and estimations suggest that more than 50 tonnes of OCDD is stored in the topsoil of Queensland.s coastal region. Investigation into the vertical distribution of PCDDs in Queensland coastal soils revealed elevated concentrations of PCDDs, (in particular OCDD) in soils to at least 3.5 m. These results indicated that the extent of the PCDD contamination is significantly greater than anticipated and it was estimated that there is in the order of 3 000 tonnes of OCDD stored in Queensland's coastal soils. The specific PCDD/F congener profile in Queensland coastal soils is unlike known PCDD/F source profiles which led to the suggestion that some yet unidentified formation mechanism may have resulted in the contamination. Potential natural sources of PCDD/Fs, including forest fires, geogenic and biogenic processes were assessed as possible origins for the PCDD contamination in Queensland. Elevated concentrations of PCDDs were detected in the atmosphere during a 'prescribed burn'. This study demonstrated that although forest fires influence atmospheric PCDD/F concentrations substantially, forest fires are not the source of PCDDs in Queensland; rather they are an important mechanism for the redistribution of PCDDs and may have attributed to the widespread PCDD contamination. In this study geological materials (oil shale and kaolin) were analysed as a proxy to assess a geogenic origin of PCDDs. Elevated concentrations of PCDDs were observed in the kaolin samples, however similar and higher concentrations were detected in surface and sub-surface soils, suggesting that specific geogenic formation processes investigated are not the source of PCDDs in Queensland. A preliminary indication for a biogenic origin of PCDDs was identified during the anaerobic incubation of sugarcane irrigation sediments. An increase in the concentration of OCDD in the anaerobic treatment, compared to the control was observed after incubation for 90 days. In these same experiments, a dechlorination of OCDD to lower chlorinated (1,4,6,9-substituted) PCDDs was also observed. Similar transformation processes were observed in other anaerobic environments in Queensland, which led to the suggestion that a biogenic formation of PCDDs (possibly from a precursor) may be responsible for the origin of PCDDs in Queensland.

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13

Prange, Joelle. "Origin of Dioxins in Queensland: Investigations into the Distribution and Sources of Polychlorinated Dibenzo-P-Dioxins in the Queensland Terrestrial Environment." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367289.

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Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are persistent organic pollutants of global concern as they are persistent, toxic and can biomagnify through the food chain. PCDD/Fs are generally regarded as trace contaminants in a number of chemical products and they are formed as by-products from various industrial, chemical and combustion processes. The pollution with PCDD/Fs occurs with the release of these chemicals into the environment, resulting in the contamination of various compartments including; air, soil, sediment and biota. Studies that have investigated the distribution of PCDD/Fs in the environment suggest that the highest concentrations of these pollutants are found in locations with a history of industrial or chemical PCDD/F sources. Queensland is the north-eastern state of Australia. Queensland has a low population density, few industrial activities and is considered predominantly rural. Therefore it was somewhat surprising that elevated concentrations of PCDD/Fs (in particular the higher chlorinated PCDDs) have been observed in soil and sediments samples collected from various locations along the Queensland coast. The concentrations of PCDDs in Queensland samples were comparable to or higher than concentrations in similar matrices from highly polluted regions elsewhere. To investigate the origin of PCDDs in Queensland, the geographical distribution of PCDD/Fs in topsoil was investigated in the coastal and inland environments to provide information on the potential sources and to estimate the extent of the PCDD contamination. Distinct east-west gradients were detected in topsoil collected from bushland areas across the state with elevated PCDD concentrations confined to the coastal region. Within the coastal region, the contamination could not be associated with specific land uses. In fact, the PCDD/F congener profile was similar in the majority of samples from the coastal region, with a dominance of the higher chlorinated PCDDs (in particular OCDD), whereas PCDFs were low or below the limit of detection. The similarity in the PCDD/F congener profiles in the soils along the coastal region indicated that a source of PCDDs of similar origin has resulted in the contamination of soil extending more than 3000 km and estimations suggest that more than 50 tonnes of OCDD is stored in the topsoil of Queensland.s coastal region. Investigation into the vertical distribution of PCDDs in Queensland coastal soils revealed elevated concentrations of PCDDs, (in particular OCDD) in soils to at least 3.5 m. These results indicated that the extent of the PCDD contamination is significantly greater than anticipated and it was estimated that there is in the order of 3 000 tonnes of OCDD stored in Queensland.s coastal soils. The specific PCDD/F congener profile in Queensland coastal soils is unlike known PCDD/F source profiles which led to the suggestion that some yet unidentified formation mechanism may have resulted in the contamination. Potential natural sources of PCDD/Fs, including forest fires, geogenic and biogenic processes were assessed as possible origins for the PCDD contamination in Queensland. Elevated concentrations of PCDDs were detected in the atmosphere during a 'prescribed burn'. This study demonstrated that although forest fires influence atmospheric PCDD/F concentrations substantially, forest fires are not the source of PCDDs in Queensland; rather they are an important mechanism for the redistribution of PCDDs and may have attributed to the widespread PCDD contamination. In this study geological materials (oil shale and kaolin) were analysed as a proxy to assess a geogenic origin of PCDDs. Elevated concentrations of PCDDs were observed in the kaolin samples, however similar and higher concentrations were detected in surface and sub-surface soils, suggesting that specific geogenic formation processes investigated are not the source of PCDDs in Queensland. A preliminary indication for a biogenic origin of PCDDs was identified during the anaerobic incubation of sugarcane irrigation sediments. An increase in the concentration of OCDD in the anaerobic treatment, compared to the control was observed after incubation for 90 days. In these same experiments, a dechlorination of OCDD to lower chlorinated (1,4,6,9-substituted) PCDDs was also observed. Similar transformation processes were observed in other anaerobic environments in Queensland, which led to the suggestion that a biogenic formation of PCDDs (possibly from a precursor) may be responsible for the origin of PCDDs in Queensland.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Public Health
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14

Aurell, Johanna. "Effects of Varying Combustion Conditions on PCDD/F Formation." Doctoral thesis, Umeå universitet, Kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1795.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are by-products emitted from combustion sources such as municipal solid waste (MSW) incineration plants. These organic compounds are recognized as toxic, bioaccumulative and persistent in the environment. PCDD/Fs are removed from flue gases before released from MSW incineration. However, the PCDD/Fs are not destroyed but retained in the residues, thus in the environment. Understanding the pathways that lead to their formation is important in order to develop ways to suppress their formation and prevent their release into the environment. Suppressing the formation can also allow less expensive air pollution control system to be used, and/or the costs of thermally treating the residues to be reduced. The main objective of the studies underlying this thesis was to elucidate process, combustion and fuel parameters that substantially affect the emission levels and formation of PCDD/Fs in flue gases from MSW incineration. The experiments were conducted under controllable, realistic combustion conditions using a laboratory-scale reactor combusting artificial MSW. The parameter found to most strongly reduce the PCDD/F emissions, was prolonging the flue gas residence time at a relatively high temperature (460°C). Increasing the sulfur dioxide (SO2) to hydrogen chloride (HCl) ratio to 1.6 in the flue gas was also found to reduce the PCDF levels, but not the PCDD levels. Fluctuations in the combustion process (carbon monoxide peaks), high chlorine levels in the waste (1.7%) and low temperatures in the secondary combustion zone (660°C) all tended to increase the emission levels. The PCDD/PCDF ratio in the flue gas was found to depend on the chlorine level in the waste, fluctuations in the combustion process and the SO2:HCl ratio in the flue gas. The formation pathways were found to be affected by the quench time profiles in the post-combustion zone, fluctuations in the combustion process and addition of sulfur. In addition, increased levels of chlorine in the waste increased the chlorination degrees of both PCDDs and PCDFs. A tendency for increased SO2 levels in the flue gas to increase levels of polychlorinated dibenzothiophenes (sulfur analogues of PCDFs) was also detected, however the increases were much less significant than the reduction in PCDF levels.

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15

Ribeiro, Renata Esteves. "Criminologia verde : crimes ambientais no Distrito Federal." reponame:Repositório Institucional da UnB, 2018. http://repositorio.unb.br/handle/10482/31906.

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Planaltina , Programa de Pós-Graduação em Ciências Ambientais, 2018.
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Estatísticas criminais constituem parte importante da atividade policial. A adoção de ferramentas mais adequadas a cada conjunto de dados pode fornecer informações úteis para a ação da polícia na sua função de apuração das infrações penais. Danos e problemas ambientais específicos são construídos através de processos sociais complexos, constituídos por uma combinação de fatores materiais e sociais. Diferentes escritores da criminologia verde, ramo que foca questões referentes a danos, transgressões e crimes ambientais, defendem uma abordagem mais conceitual, no sentido de alocar os debates em torno da interligação entre questões sociais e ambientais. Este trabalho tem como objetivos: i) Avaliar o cenário temporal e espacial dos registros de crimes ambientais entre os anos de 2009 e 2016; ii) verificar a influência das variáveis socioeconômicas sobre os registros de crimes ambientais, determinando se as teorias da criminologia tradicional se aplicam aos crimes ambientais estudados neste trabalho. Foi possível identificar uma desproporção entre o número de registros de tipos penais, explicada pela vasta presença de Unidades de Conservação no território do DF e pelos altos índices de infraestrutura sanitária e reduzido parque industrial. Há associações consistentes entre alguns tipos penais definidos na Lei de Crimes Ambientais (Lei no 9.605/1998) e algumas Regiões Administrativas (RA) do Distrito Federal e certas delegacias de polícia, explicadas pelas singularidades de cada área. Os registros de crimes ambientais ocorrem principalmente nas áreas urbanas. Homogeneidades e particularidades no uso do solo aparecem como fatores influenciadores na distribuição espacial. A frequente relação com as variáveis relacionadas à migração sugere uma possível aplicação da teoria da desorganização social aos crimes ambientais, refletindo a incapacidade da comunidade em se organizar em prol do controle comunitário.
Criminal statistics are an important part of police activity. The adoption of more appropriate tools for each set of data can provide useful information for police investigation of criminal offenses. Specific environmental damage and problems are built through complex social processes, made up of a combination of material and social factors. Different writers of green criminology, a branch that focuses on issues related to damages, transgressions and environmental crimes, advocate a more conceptual approach, in order to allocate debates around the interconnection between social and environmental issues. This study aims to: i) Evaluate the temporal and spatial scenario of environmental crime records between 2009 and 2016; ii) to verify the influence of the socioeconomic variables on the records of environmental crimes, determining if the theories of traditional criminology apply to the environmental crimes studied in this work. It was possible to identify a disproportion between the number of records of criminal types, explained by the vast presence of Conservation Units in the territory of the Federal District and by the high rates of sanitary infrastructure and reduced industrial park. There are consistent associations between some criminal types defined in the Environmental Crimes Law (Law 9605/1998) and some Administrative Regions (RA) of the Federal District and certain police stations, explained by the singularities of each area. Records of environmental crimes occur mainly in urban areas. Homogeneities and particularities in soil use appear as influencing factors in the spatial distribution. The frequent relationship with the variables related to migration suggests a possible application of the theory of social disorganization to environmental crimes, reflecting the inability of the community to organize in favor of community control.

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16

Larsson, Daniel. "Mobilisation of soil-bound dioxins at an old sawmill area : Impact of excavation on groundwater levels of PCDF/PCDDs at Norrbyskär." Thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-124420.

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17

Jansson, Stina. "Thermal formation and chlorination of dioxins and dioxin-like compounds." Doctoral thesis, Umeå universitet, Kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1881.

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This thesis contributes to an increased understanding of the formation of dioxins and dioxin-like compounds in combustion processes. Although emissions to air from waste incineration facilities have been greatly reduced by the use of efficient air pollution control measures, the resulting residues (ashes and filters) are highly toxic and are classified as hazardous waste. The main objective of the work underlying this thesis was to elucidate the formation and chlorination pathways of dioxins and dioxin-like compounds in waste combustion flue gases in the temperature range 640-200°C in a representative, well-controlled laboratory-scale reactor using artificial municipal solid waste. This could contribute to the reduction of harmful emissions to air and also reduce the toxicity of waste incineration residues, thus reducing or even eliminating the need for costly and potentially hazardous after-treatment. A comparison of four different quenching profiles showed that the formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was rapid and mainly occurred in the 640-400°C temperature region, with high dependency on sufficient residence time within a specific temperature region. Prolonged residence time at high temperatures (450/460°C) reduced the PCDD yields, even at lower temperatures along the post-combustion zone. PCDD, PCDF and PCN (polychlorinated naphthalene) isomer distribution patterns indicated contributions from chlorophenol condensation as well as chlorination reactions for all three classes of compounds. The formation of PCDDs was largely influenced by chlorophenol condensation and to some extent by chlorination reactions. For the PCDFs, chlorine substitution adjacent to the oxygen bridges was unfavoured, as demonstrated by the notably lower abundance of 1,9-substituted congeners. This was supported by bidirectional orthogonal partial least squares (O2PLS) modelling. The variable with the greatest influence on the distribution of PCDD congeners was the relative free energy (RΔGf). The O2PLS models displayed distinct clusters, dividing most of the homologues into two or three sub-groups of congeners which seemed to correspond to the probability of origination from chlorophenol condensation. The effects of injection of aromatic structures into the flue gas differed for each class of compounds. Injection of naphthalene increased the formation of monochlorinated naphthalene but the remaining homologues appeared to be unaffected. This was probably due to insufficient residence time at temperatures necessary for further chlorination. Injected dibenzo-p-dioxin was decomposed, chlorinated and re-condensated into PCDDs and PCDFs, whereas injection of dibenzofuran and fluorene reduced the PCDD levels in the flue gas.
Denna avhandling fokuserar på olika aspekter som kan bidra till en ökad förståelse av bildning av dioxiner och dioxin-lika föreningar i förbränningsprocesser. Även om utsläppen till luft från sopförbränningsanläggningar har minskat kraftigt tack vare effektiva rökgasreningsmetoder, så återstår problemet med mycket giftiga rökgasreningsprodukter (askor och filter), vilka klassificeras som farligt avfall. Det huvudsakliga syftet med arbetet bakom denna avhandling var att klarlägga bildnings- och kloreringsvägarna för dioxiner och dioxin-lika föreningar i temperaturintervallet 640-200°C i rökgaser från sopförbränning. Detta kan möjliggöra lösningar för ytterligare emissionsminskningar och en avgiftning av biprodukterna från avfallsförbränning, vilket minskar eller till och med eliminerar behovet av kostsam och riskfylld efterbehandling. Realistiska och välkontrollerade försök har utförts i en lab-skalereaktor där en artificiell hushållssopa har förbränts. En jämförelse av fyra olika temperatur- och uppehållstidsprofiler visade att bildning av polyklorerade dibenso-p-dioxiner (PCDD) och dibensofuraner (PCDF) sker snabbt och huvudsakligen inom temperaturintervallet 640-400°C. Bildningen var starkt beroende av en tillräckligt lång uppehållstid inom ett visst temperaturområde. En förlängd uppehållstid vid höga temperaturer (>450°C) resulterade i minskade halter av PCDD, vilka förhöll sig låga även senare i efterförbränningszonen. Isomermönstren av PCDD, PCDF och PCN (polyklorerade naftalener) visade alla tecken på att härröra från både klorfenolkondensation och kloreringsreaktioner. PCDD-mönstret visade tydliga indikationer på bildning från klorfenoler, och till mindre grad bildning via klorering. För PCDF var klorsubstitution i positioner angränsande till syrebryggan missgynnad, vilket bekräftades av multivariat modellering (O2PLS). Den variabel som starkast påverkade bildningen av PCDD var relativa fria energin (RΔGf). Modellerna visade på en distinkt gruppering av PCDD- och PCDF-kongenerna i två eller tre grupper för varje kloreringsgrad, och föreslås vara relaterad till sannolikheten för respektive kongen att bildas via klorfenolkondensation. Injektion av aromatiska kolstrukturer i rökgaskanalen gav upphov till skilda effekter. Injektion av naftalen ökade bildningen av monoklorerad naftalen medan resterande homologer inte verkade påverkas, sannolikt på grund av för kort uppehållstid för ytterligare klorering. Dibenso-p-dioxin spjälkades sannolikt till fenoliska fragment som klorerades och sedan återkondenserades till PCDD och PCDF, medan dibensofuran och fluoren kraftigt reducerade PCDD-koncentrationerna.

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18

Xu, Weiguang. "Risk assessment of dietary exposure to PCDD/PCDFs, DL-PCBs and NDL-PCBs of Hong Kong residents." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1407.

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19

Nording, Malin. "Rapid sample preparation and bioanalytical techniques for efficient screening of organic pollutants in the environment." Doctoral thesis, Umeå universitet, Kemi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-842.

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Large numbers of samples often need to be prepared and analysed in surveys of organic pollutants in the environment, but while the methods commonly used in such surveys can provide abundant detail they are generally costly, time-consuming and require large amounts of resources, so there is a need for simpler techniques. The work underlying this thesis assessed the potential utility of more convenient sample preparation and bioanalytical techniques for rapidly screening various environmental matrices that could be useful complements to higher resolution methods. Initially, the utility of a simplified extraction technique followed by an enzyme-linked immunosorbent assay (ELISA) for detecting polycyclic aromatic hydrocarbons (PAHs) in authentic (i.e. unspiked) contaminated soils was explored. The results showed that there are relationships between the structure and cross-reactivity among compounds that often co-occur with target PAHs. However, their potential contribution to deviations between estimates of total PAH contents of soils obtained using ELISA and gas chromatography-mass spectrometry (GC-MS) based reference methods were limited. Instead, the cross-reactivity of target PAHs and the failure to extract all of the PAHs prior to the ELISA determinations were the main reasons for these deviations. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were detected in food and feed matrices, as well as in authentic contaminated soils using different bioanalytical techniques – ELISA and two cell-based bioassays: CAFLUX and CALUX (chemically activated fluorescent/luciferase gene expression) assays. In addition, enhanced sample preparation techniques based on accelerated solvent extraction (ASE) were developed. ASE with integrated carbon fractionation (ASE-C) in combination with CAFLUX produced estimates of PCDD and PCDF contents in fish oil and fish meal that agreed well with results obtained using reference methods. Furthermore, results from ELISA and GC-high resolution MS analyses of extracts of PCDD- and PCDF-contaminated soil samples obtained using an adjusted ASE-C technique were strongly correlated. Finally, the thesis reports the first experiments in which the results of CAFLUX, CALUX, and ELISA determinations of PCDDs and PCDFs in extracts of authentic contaminated soil samples were evaluated and compared to those obtained using a reference method. All of the bioanalytical techniques were found to be sufficiently sensitive, selective, and accurate for use in screening in compliance with soil quality assessment criteria. Overall, the improved sample preparation and bioanalytical techniques examined proved to be useful potential complements to conventional methods, enhancing the analytical framework for PAHs, PCDDs, and PCDFs. However, further validation has to be undertaken before they are applied on a large-scale.

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Duclot, Florian. "Rôle de l'acétyltransférase PCAF dans la plasticité cérébrale physiologique et pathologique : analyse de souris PCAF knock-out." Montpellier 2, 2009. http://www.theses.fr/2009MON20244.

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Frýba, Lukáš. "Analýza alternativ odstraňování PCDD/F při spalování odpadů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229471.

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The thesis is focused on analyzing the current status of the technology used for cleaning flue gas from persistent organic pollutants, especially PCDD/F. For the three most commonly used methods of solution operational and energy efficiency comparison was made, where achievable energy export and the impact of the change in working conditions on the efficiency indicators of energy production and use of the energy was evaluated. In conditions we considered an alternative machine-technological solutions used for the final disposal of persistent organic pollutants resulting from the waste combustion in terms of additional operating costs and energy efficiency.

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Mateo, González Francesca. "Regulació del complex ciclina A-CDK2 per l'acetilasa PCAF." Doctoral thesis, Universitat de Barcelona, 2009. http://hdl.handle.net/10803/914.

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Els complexes ciclina-CDK són elements clau perquè el cicle cel·lular es doni de manera ordenada. Estan regulats a diferents nivells ja que les seves funcions són essencials per a la correcta progressió del cicle. El primer nivell de regulació és la interacció entre la ciclina i la CDK. En segon lloc, aquestes proteïnes poden experimentar fosforilacions i defosforilacions activadores i inhibidores. En tercer lloc, aquests complexes poden ser inhibits per la interacció amb CKIs (CDK Inhibitors). Finalment, la localització subcel·lular també és una manera de regular l'activitat d'aquests complexes, ja que només són actius al nucli de la cèl·lula.

En aquest treball presentem un nou mecanisme de regulació dels complexes ciclina-CDK. Concretament hem observat que els membres del complex ciclina A-CDK2 interaccionen amb l'acetilasa PCAF. Aquesta proteïna ha estat generalment considerada com a un co-activador transcripcional gràcies a la seva capacitat d'acetilar histones i activar la transcripció gènica. Tanmateix, també s'ha vist que és capaç d'acetilar proteïnes no-histones com ara p53 o MyoD, i com a conseqüència està implicada en altres funcions cel·lulars com la diferenciació o la resposta a dany al DNA. L'acetilasa PCAF s'uneix al complex ciclina A-CDK2 tot inhibint la seva activitat quinasa. A més, acetila la ciclina A, cosa que comporta la seva degradació pel sistema ubiquitina-proteasoma. PCAF també acetila CDK2 a la lisina 33, la qual es troba molt conservada a la família de les CDKs, ja que és un aminoàcid crucial per a la interacció amb l'ATP. L'acetilació de CDK2 a la lisina 33 comporta la inhibició de la seva activitat quinasa i la seva separació de la ciclina A.

En conclusió, els resultats d'aquesta tesi aporten un nou nivell de regulació dels complexes ciclina-CDK desconegut fins ara, i que cal tenir en compte com a possible mecanisme d'acció dels fàrmacs basats en compostos inhibidors de deacetilases els quals, d'altra banda, estan donant bons resultats en el tractament de malalties hematològiques i tumors sòlids.
"REGULATION OF CYCLIN A-CDK2 COMPLEX BY ACETYLATION"

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Cell cycle proteins are regulated in different ways, being phosphorylation one of the most important and more studied mechanisms of regulation. On the other hand, acetylation is another kind of post-translational modification that was discovered in histones and initially it was associated with transcriptionally active chromatin. However, different studies indicate that acetylation can also play a role in the regulation of non-histone proteins and it has been linked to oncogenesis and cardiovascular and neurodegenerative diseases.

In this work we report that cyclin A/cdk2 complex, which is crucial for cell cycle progression during S phase, is acetylated by the acetyltransferase P/CAF. Cyclin A directly interacts with P/CAF and is acetylated at lysines 54, 68, 95 and 112. Maximal acetylation occurs simultaneously to ubiquitylation at mitosis, indicating a role of acetylation on cyclin A stability. A non-acetylatable mutant in which these lysines were substituted by arginines (cycA 4R) cannot be ubiquitylated, is more stable than cycA wild-type and arrests cell cycle at mitosis.

Increased expression of cyclin A has been detected in many types of cancers and it has a prognostic value to predict survival or early relapse. Our results indicate that acetylation is able to cause a decrease in the levels of cyclin A, suggesting that treatment with HDAC inhibitors (which potentiate acetylation in the cell) could be considered to treat this kind of tumors.

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Ellis, Cameron B. "Tribopairs in Wellbore Drilling: A Study of PCD Tilting Pad Bearings in an Electric Submersible Pump." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/7233.

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A polycrystalline diamond was tested as a bearing material for a tilting pad thrust bearing to be used in an electric submersible pump, which elevates process fluids from the bottom of well bores. The goal of this study was to compare the PCD to a current best of technology, which is stainless steel with an engineering polymer.This study found that PCD can handle larger loads than current technology but is limited in size due to diamond sintering and manufacturing constraints. The maximum size is Ã˜75mm.

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Pucella, Riccardo R. "Investigations on relative definability in PCF." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24036.

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The focus of this thesis is the study of relative definability of first-order boolean functions with respect to the language PCF, a paradigmatic typed, higher-order language based on the simply-typed $ lambda$-calculus. The basic core language is sequential. We study the effect of adding construct that embody various notions of parallel execution. The resulting set of equivalence classes with respect to relative definability forms a supsemilattice analoguous to the lattice of degrees in recursion theory. Recent results of Bucciarelli show that the lattice of degrees of parallelism has both infinite chains and infinite antichains. By considering a very simple subset of Sieber's sequentiality relations, we identify levels in the lattice and derive inexpressibility results concerning functions on different levels. This allows us to explore further the structure of the lattice of degrees of parallelism and show the existence of new infinite hierarchies. We also identify four subsemilattices of this structure, all characterized by a simple property.

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Liljeroos, Tom. "Är saltglaseringsindustrin en källa till tidig organokloridförekomst?" Thesis, Halmstad University, School of Teacher Education (LUT), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2365.

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Abstract.

The levels of dioxin and comparable substances rose to a large extent in our environment during the second half of the 20'Th century. This was the result of the synthesis of, and careless usage of these substances in cooling fluids, hydraulics, pesticides etc.

Background levels of dioxins and furans in sealed samples prior to this era suggest that former sources of these substances existed.

Salt glazing is a method of adding a smooth acid resistant exterior to stoneware ceramics. The technique has been in use since the 16'Th century, maybe even earlier than that. Some sources date the origin of the technique to the 13'Th century. Salt glazed ceramics were the prime type of industrial vessels and it was extensively used for food preservation in households from the 17'Th century to the early/mid 20'Th century.

The method was/is primarily used by Germany, Great Britain, America and Sweden.

Salt glazing is a source of graphite structures from soot, and of chlorine gas. Hence, the formation of organochlorides should be able to occur.

The reports main objective is to highlight the question; “Could the salt glazing industry be one of the sources to early dioxin emissions?” Secondary objectives are to present an introduction to dioxin and comparable substances, methods of analysis and symptoms of exposure.

The salt glazing industry is much likely one of the anthropogenic sources of early PCDD/F emissions. Though emission levels seem to be quite low, due to the persistence of PCDD/F noticeable levels could have accumulated. When the Leblanc soda process (a known source of PCDD/F) was introduced in 1791, the salt glazing process had already been used for nearly three hundred years.

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Sewart, Andrew Paul. "The fate and behaviour of polychlorinated dibenzo-p-dioxins, dibenzofurans and polychlorinated biphenyls in sewage sludge : amended agricultural soils and their potential transfer into terrestrial foodchain via lactating cattle." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261004.

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Åberg, Annika. "Fate and exposure assessment of PCDD/Fs at contaminated sites." Licentiate thesis, Umeå University, Chemistry, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-5717.

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Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzo-furans (PCDFs) belong to the most toxic compounds known to science and they are defined as Persistent Organic Pollutants (POPs) under the Stock-holm Convention. The general human exposure to PCDD/Fs is primarily through dietary intake. The importance of contaminated sites as secondary PCDD/F sources (i.e. sources that once received its contamination from a primary source) are getting increased attention. To be able to assess the risks for human exposure at PCDD/F contaminated sites, the environmen-tal distribution of PCDD/Fs and the potential mobilization between dif-ferent environmental media (e.g. food chain transfer) must be known. The primary aim of the work presented in this thesis was to investigate human exposure pathways associated with PCDD/F contaminated sites by combining field measurements and modeling. Site specific field measurements were made at a PCDD/F contaminated site in Sweden and multimedia modeling scenarios were evaluated against site specific data and national reference data.

The results show that the congener distributions in exposure media affected by contaminated soil may differ significantly from the distribu-tions found in media from reference locations. Higher chlorinated PCDD/Fs may be transferred into food chains where they contribute to a large fraction of the toxic equivalent concentration (TEQ). Ingestion of locally produced animal food may be an important exposure pathway al-ready at low or moderate PCDD/F soil concentrations. However, the con-gener composition of the source is critical for the exposure. The signifi-cance of the individual exposure routes varies depending on e.g. the spatial distribution and magnitude of the soil contamination, the pro-perties of the exposure media and the human behavior. Multimedia mo-deling can be used in risk assessments as long as model algorithms and model parameters are representative for the superhydrophobic properties of PCDD/Fs. However, selection of physical-chemical PCDD/F properties is a challenge due to large variation in reported values. For some proper-ties, data is scattered or completely lacking

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Harrad, Stuart J. "Levels and sources of PCDDs and PCDFs in UK soils." Thesis, University of East Anglia, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327955.

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LI, ZHE. "Photocyclodehydrofluorination (PCDHF) –A synthetic method for fluorinated polynuclear aromatic hydrocarbons." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1448814689.

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Flynn, Kimberly C. Grassco Colleen E. Boorom Eric W. "Paperless Contract Folder's (PCF) DoD 5015.2 certification." Monterey, Calif. : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/JAP/2010/Jun/10Jun%5FFlynn%5FJAP.pdf.

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"Submitted in partial fulfillment of the requirements for the degree of Master of Contract Management from the Naval Postgraduate School, June 2010."
Advisor(s): Doelling, Michael C. ; Brinkley, Douglas E. "June 2010." "Joint applied project"--Cover. Joint authors: .Grasso, Colleen E. ; Boorom, Eric W. Description based on title screen as viewed on July 14, 2010. Author(s) subject terms: Paperless Contract Folder's (PCF) DoD 5015.2 certification Includes bibliographical references (p. 97). Also available in print.

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Flynn, Kimberly C., Eric W. Boorom, and Colleen E. Grasso. "Paperless Contract Folder's (PCF) DoD 5015.2 certification." Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/10522.

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Joint Applied Project
The objective of this project is to conduct an analysis of the CECOM Contracting Center's Paperless Contracting Folder program in regards to maintaining its DoD 5015.2 certification. The desired outcomes will be the creation of a File Plan and User Guide to assist with DoD 5015.2 certification.

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Da, Silva Pereira Luis Miguel. "Combinatorics of Singular Cardinals and PCF structures." Paris 7, 2007. http://www.theses.fr/2007PA077100.

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Ce travail est centré sur la théorie PCF de Shelah. Nous étudions la connexion entre la topologie des espaces PCF et les notions standard de la théorie PCF. Nous démontrons une généralisation du résultat qui dit que les espaces PCF séparables sont séquentiels et nous obtenons comme corollaire qu'il existe beaucoup de suites qui ont une vrai cofmalité modulo l'idéal des ensembles finis. Nous démontrons que ce corollaire est optimal. Nous donnons aussi une démonstration topologique d'estimatives cardinales obtenues précédemment par l'utilisation de la norme de Galvin-Hajnal. Nous étudions une conséquence de la négation de la conjecture PCF de Shelah appelé la Propriété des Ensembles Livres Approximables (PELA). Nous notons que la PELA est incompatible avec l'existence d'échelles continus en forme d'arbre et nous prouvons la consistance de ces échelles avec l'existence des plus grands des grands cardinaux établissant ainsi que la PELA n'est pas impliqué par les grands cardinaux. Nous étudions l'existence d'échelles continus en forme d'arbre et la négation de la PELA en plusieurs extensions de Prikry de l'univers
This work is centered on Shelah's PCF theory. We study the connection between the topology of PCF spaces and standard PCF theory notions. We prove a generalization of the result that says that separable PCF spaces are sequential and obtain as a corollary that there exist many sequences that have true cofinality modulo the ideal of finite sets. We prove that this corollary is optimal. We also give a topological proof of cardinal estimates previously obtained through the use of the Galvin-Hajnal norm. We study a consequence of the negation of Shelah's PCF conjecture called the Approachable Free Subset Property (AFSP). We note that AFSP is incompatible with the existence of tree-like continuous scales and prove the consistency of these scales with the largest large cardinal axioms thus establishing that AFSP is not implied by large cardinals. We study the existence of tree-like continuous scales and the negation of AFSP in several Prikry extensions of the universe

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Perearnau, Garcia Anna. "lmplicacló de p27 i PCAF en la regulació de la transcripció." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/291434.

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En el nostre grup s’ha demostrat la interacció directa entre l’inhibidor de ciclines-CDKs p27 i l’acetiltransferasa PCAF. Aquesta interacció es produeix entre el domini HAT de PCAF i la regió que compren els aminoàcids 91-120 de p27. Aquesta regió conté un PRD (Proline Rich Domain, 91-96aa), un domini característic d’interacció entre proteïnes. En aquest treball hem comprobat que PCAF acetila la lisina en posició 100 de p27 in vivo. L’acetilació de p27 afecta la seva estabilitat, afavorint-ne la seva trasnlocació del nucli al citoplasma, al inici de la fase G1, on serà degradada (Pérez-Luna et al., 2012). PCAF és un co-activador transcripcional que actúa acetilant histones, factors de trasncripció i altres proteïnes. Per altra banda, recentment s’ha descrit que p27 actúa com a regulador transcripcional, bàsicament com a repressor transcripcional de la transcripció de determinats gens diana. Així doncs, com PCAF acetila p27, en aquest treball ens hem centrat en confirmar la col·laboració de p27 i PCAF en la regulació transcripcional dels seus gens diana. Per aconseguir aquest objectiu hem identificat els programes transcripcionals regulats per p27 i PCAF en cèl·lules humanes de càncer de còlon (HCT116), mitjançant experiments de ChIP-seq. Determinem que p27 i PCAF s’uneixen a regions diferents de la cromatina en els seus gens diana. Un cop identificats els gens diana comuns de p27 i PCAF, s’ha analitzat l’expressió de 14 d’aquests gens i hem pogut concloure que p27 i PCAF en regulen la seva transcripció de forma antagònica. p27 reprimeix i PCAF activa l’expressió de la majoria dels gens diana analitzats. Aquest efecte és degut a la unió de p27 i PCAF a elements reguladors de la transcripció en la cromatina. Hem descrit que p27 s’uneix a elements amb efecte activador de la transcripció en la cromatina dels seus gens diana, inhibint-los. Per contra, PCAF s’uneix a elements amb efecte silenciador sobre la transcripció del seus gens diana. Finalment hem demostrat la interacció de p27 i PCAF amb els factors de transcripció PAX en cèl·lules HCT116.
Our group has demonstrated the direct interaction between the cyclin-CDK inhibitor p27 and the acetyltransferase PCAF. This interaction occurs between the HAT domain of PCAF and the region comprising aa 91-120 of p27. This region of p27 contains a PRD (Proline Rich Domain, 91-96aa) a characteristic protein interacting domain. In this study we found that PCAF acetylates the lysine at position 100 of p27 in vivo. The acetylation of p27 affects its stability, promoting its translocation from the nucleus to the cytoplasm early in the G1 phase, where it will be degraded (Pérez-Luna et al., 2012). PCAF acts as a transcriptional coactivator by acetylating histones, transcription factors and other proteins. On the other hand, it has been reported that p27 acts as a transcriptional regulator, basically by repressing transcription of certain target genes. Therefore, since PCAF acetylates p27, in this thesis we focus on confirming the collaboration of p27 and PCAF in the transcriptional regulation of their target genes. To pursue this goal we have identified the transcriptional programs regulated by p27 and PCAF in HCT116 cells by ChIP -seq experiments. We found that p27 and PCAF binds to different regions of the chromatin of their target genes. Once the common target genes of p27 and PCAF were identified, their expression was analyzed. We concluded that p27 and PCAF regulate the transcription of their target genes antagonistically. p27 represses and PCAF activates the expression of most of their target genes, due to its binding to transcription regulatory elements in the chromatin. p27 binds to transcription activating elements, thus inhibiting the transcription of the target gene. On the contrary, PCAF binds to transcription silencing elements, thus activating the transcription of the target gene. Finally we demonstrated the interaction of p27 and PCAF with transcription factors PAX in HCT116 cells.

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Bian, Shuning. "Real-time monitoring of ultrasound and cavitation mediated drug delivery." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:e5a774a9-5b93-4862-8dd9-0614d234ff28.

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Drug delivery plays a crucial role in the chemotherapeutic treatment of cancerous solid tumours. A drug, no matter how potent, is only truly effective when it can be delivered to all targeted cells. In recent years it has been recognised that the poor response of tumours to chemotherapy is in part due to inadequate drug delivery. Numerous strategies have been developed to overcome this issue. Of particular interest to the present work is the application of ultrasound and cavitation, which has been shown to be capable of enhancing drug delivery in solid tumours. These enhancements are attributed to the acoustic cavitation of microbubbles and the effects cavitation induces in the surrounding tissue. To better understand how ultrasound and cavitation can enhance drug delivery, an instrument was developed that is capable of monitoring in real-time and in-situ the effect of ultrasound and cavitation on drugs and drug analogues within flow channel models. The developed instrument was used to investigate the effect of ultrasound and cavitation on drug-eluting beads used for chemoembolisation, the effects of drug loading on microbubble dynamics, the effects produced by different cavitation agents, and the performance of passive acoustic mapping as a means of cavitation monitoring. The findings of the above investigations include: more physiologically relevant characterisations of drug-eluting beads pharmacokinetics, the possibility of significant changes in microbubble dynamics due to drug loading, a lack of general correlation between detected cavitation activity and induced effects, and the potential of passive acoustic mapping for monitoring cavitation and ultrasound induced effects. These and other findings also demonstrate the utility of the developed instrument for studying the many facets and applications of ultrasound and cavitation mediated drug delivery.

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Mills, Christopher Alan. "Investigations into low band-gap, semiconducting polymers." Thesis, Bangor University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340950.

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Fàbrega, Bonadona Francesc. "Physiologically-Based Pharmacokinetic (Pbpk) Modeling of Pcdd/Fs and Pfass in Humans." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/284035.

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Els models farmacocinètics (PBPK) són representacions matemàtiques del cos humà, que tenen com a objectiu calcular la concentració de compostos químics en els teixits humans. Els models PBPK poden millorar el càlcul del risc per a la salut humana, però de moment no han estat escassament utilitzats. Entre els compostos ambientals més perillosos per a la salut humana destaquen les dibenzo-p-dioxines policlorades i dibenzofurans policlorats (PCDD/Fs) i els compostos perfluorats (PFASs). L’objectiu de la present tesis es el desenvolupament de un model PBPK per calcular la concentració de PCDD/Fs i PFASs en teixits humans. Prèviament al desenvolupament del model PBPK, es va desenvolupar un índex de risc utilitzant mapes auto-organitzats (SOM), per calcular els compostos ambientals més perillosos per a la salut humana. Entre els compostos més perillosos es van trobar els PFASs. Després es va desenvolupar el model PBPK per predir les concentracions de PCDD/Fs en sang i en teixit adipós. Els resultats finals van ser altament coincidents amb els resultats experimentals trobats a l’àrea de Tarragona (NE d’Espanya), y per això es va considerar el model com a validat. A continuació el model es va adaptar per calcular les concentracions de PFASs. Per això, primer es va adaptar el model per PFOS i PFOA, que són els compostos perfluorats més estudiats en la literatura, i després es va estendre el model a 9 PFASs més. Finalment, es va fer un anàlisis de la incertesa del model PBPK, i la incertesa paramètrica es va estudiar visual i estadísticament.
Los modelos farmacocinéticos (PBPK) son representaciones matemáticas del cuerpo humano, que tienen como objetivo calcular la concentración de químicos en los tejidos humanos. Los modelos PBPK pueden mejorar el cálculo de riesgo para la salud humana, pero hasta el momento no han sido muy usados. Entre los compuestos ambientales más peligrosos para la salud humana destacan las dibenzo-p-dioxinas policloradas y los dibenzofuranos policlorados (PCDD/Fs) y los compuestos perfluorados (PFASs). El objetivo de la presente tesis es el desarrollo un modelo PBPK para calcular la concentración de PCDD/Fs y PFASs en tejidos humanos. Previo al desarrollo del modelo PBPK se desarrolló un índice de riesgo usando mapas auto-organizados (SOM), para calcular los compuestos ambientales más peligrosos para la salud humana. Los PFASs se encontraron entre los compuestos de más riesgo. Después se desarrolló el modelo PBPK para predecir las concentraciones de PCDD/Fs en sangre y en tejido adiposo. Los resultados finales fueron muy coincidentes con los resultados experimentales encontrados en el área de Tarragona (NE de España), y por esta razón el modelo se consideró como validado. A continuación el modelo se adaptó para calcular las concentraciones de PFASs. Para ello, primero se adaptó el modelo para PFOS y PFOA, que son los compuestos perfluorados más estudiados en la literatura, y después se extendió el modelo a otros 9 PFASs. Finalmente, se hizo un análisis de la incertidumbre del modelo PBPK, y la incertidumbre paramétrica se estudio visual y estadísticamente.
Physiologically based pharmacokinetic (PBPK) models are mathematic representations of the human body that aims to assess the time course distribution of chemicals in human tissues. PBPK models may improve the assessment of human health risk but until now were not well studied. Among the most harmful environmental pollutants for human health there are polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and perfluoroalkyl substances (PFASs). The objective of the present work is to develop a PBPK model to assess the time course concentration of PCDD/Fs and PFASs in human tissues. Previously to the PBPK model development, a ranking index was developed using self-organizing maps (SOM) to assess the most harmful environmental contaminants, being PFASs among the most harmful compounds. After that, the PBPK model was developed to assess and predict the concentration of PCDD/Fs in human blood and adipose tissue. The final outcomes were very coincident with the experimental data found in Tarragona County (NE of Spain), and the model was considered as a validated. After that, the model was adapted to assess the concentrations of PFASs. Firstly the model was developed for PFOS and PFOA, that are the most studied compounds in the research literature, and then the model was expended to 9 PFASs more. Finally the uncertainty analysis of the PBPK model was conducted, and the parametric uncertainty was visually and statistically studied.

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Zhu, Cailei. "Characterization of tumor suppressing function of PCAF in esophageal squamous cell carcinoma." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557480.

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祝彩磊 and Cailei Zhu. "Characterization of tumor suppressing function of PCAF in esophageal squamous cell carcinoma." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557480.

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Greyling, Neville. "An investigation into PCF-DCF behaviour of 802.11b networks." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4118.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: In recent years the demand for bandwidth has dramatically increased because of new applications for data and multimedia, and wireless technology has prevailed as a prominent technology for data connectivity, especially for home, office and last mile services. As wireless communications are dependant upon spectrum availability, which is communal, this scarce commodity in communication has to be used as efficiently as possible. Some aspects of this requirement are addressed in this project. We chose the IEEE 802.11b standard for this particular investigation because of its widespread use, the vast amount of applicable literature, the variety of software simulation tools and the ease with which equipment can be obtained. The IEEE 802.11 standard specified the Point Coordination Function as the de- terministic protocol. Recently research into this aspect has stagnated, and it was the purpose of this project to investigate how existing infrastructure networks could be improved by optimising some modes of the 802.11 protocol. The investigation also hoped to determine when to change between Distributed Coordination Function (DCF) and Point Coordination Function (PCF), and to provide an adaptive protocol to do so. This thesis presents mathematical models for the operation of DCF and PCF modes, which is compared with results from a network simulator (ns2), for theoretical veri- fication. A protocol is also proposed to dynamically switch between DCF and PCF, to harness the advantages they present.
AFRIKAANSE OPSOMMING: Die afgelope paar jaar het die aanvraag na bandwydte dramaties verhoog as gevolg van nuwe toepassings vir data en multimedia, en draadlose tegnologie het voorgekom as ’n dominante tegnologie vir data konnektiwiteit, veral vir die huis, kantoor en laaste myl dienste. Omdat draadlose kommunikasie afhanklik is van spektrum beskikbaarheid, wat gemeenskaplik is, moet hierdie skaars kommoditeit in kommunikasie so effektief moontlik gebruik word. Sekere aspekte van die vereiste sal in die tesis ondersoek word. Dit is besluit om die IEEE 802.11b standard vir die spesifieke ondersoek te gebruik as gevolg van die wye toepassing, die groot hoeveelheid beskikbare literatuur, die verskeidenheid simulasie sagteware en die gemak waarmee die toerusting bekom kan word. Die IEEE 802.11 standaard spesifiseer the Punt Koordinasie Funksie (PCF) as die deterministiese protokol vir die betrokke standaard. Onlangs het navorsing oor hierdie aspek gestagneer, en dit is die doel van die projek om te ondersoek hoe bestaande infrastruktuur netwerke moontlik verbeter kan word deur optimering van sekere modusse van die 802.11 protokol. Die ondersoek hoop ook om te bepaal wanneer die oorgang van die Distrubusie Koordinasie Funksie (DCF) en Punt Ko- ordinasie Funksie sal plaasvind, en om ’n dienooreenstemmende protokol te on- twikkel. Die tesis verskaf wiskundige modelle vir die werking van die DCF en PCF modusse, wat vergelyk word met resultate uit ’n netwerk simulator (ns2), vir teoretiese ver- ifikasie. ’n Protokol word ook voorgestel om dinamies te wissel tussen DCF and PCF, om die voordele wat die protokolle verskaf te gebruik.

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Er-Rhaimini, Karim. "Constructions par forcing d'espaces LCS et de structures PCF." Paris 7, 2009. http://www.theses.fr/2009PA077196.

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La thèse concerne la théorie PCF et l'arithmétique des cardinaux. Dans le premier chapitre, on expose une version simplifiée de la théorie PCF qui permet de donner une preuve complète du théorème de Shelah et ainsi de justifier l'étude des structures PCF. Le second chapitre concerne la fonction rho, introduite par Todorcevic. Ce chapitre permet de préparer la construction de forcing effectuée au chapitre trois. Il reprend les travaux de Todorcevic en ne gardant que ce qui est nécessaire au chapitre trois, ce qui permet de simplifier les preuves pour une lecture plus facile. Dans le troisième chapitre, qui est le cœur de la thèse, on expose tout d'abord la théorie des espaces LCS et on propose une nouvelle façon de forcer des espaces LCS de taille n'importe quel ordinal inférieur à omega_3. Enfin, on explique le lien entre espaces LCS et structures PCF et la construction de forcing exposée précédemment permet, au prix d'une modification mineure de forcer des structures PCF de taille n'importe quel ordinal inférieur à omega_3. Ce résultat améliore le précédent résultat connu, qui permettait de construire des structures PCF de taille omega_2
This thesis is about PCF theory and arithmetic cardinal. In chapter one, we give a simple but complete proof of Shelah's Theorem trough a simplified version of PCF theory. This theorem is in itself a justification for the study of PCF structures. In chapter two, we present the rho-fimction wich was introduced by Todorcevic. This chapter is a preparation to the forcing construction in chapter three. We mainly reproduce Todorcevic's work but in a simplified version, only keeping what is strictly necessary to our purpose. Thus, the proofs are simpler and make the reading easier. In chapter three, which is the main chapter of the thesis, we first expose the theory of LCS spaces and we show a new way to force LCS spaces of height any ordinal less than omega_3. At last, we explain the link between LCS spaces ans PCF structures and the previous forcing construction allows, by a slight modification, to force PCF structures of height any ordinal less than omega_3. This result improves the previous known result which permitted to force PCF structures of height omega_2

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Streiff, Gérard. "Jean Kanapa, 1921-1978 : une singulière histoire du PCF /." Paris ; Budapest ; Torino : l'Harmattan, 2001. http://catalogue.bnf.fr/ark:/12148/cb38855551c.

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Del, Rio Gomez Iliana Maria. "Reproductive outcomes in people contaminated by PCBs/PCDFs, organohalogens in the Yucheng accident." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407767.

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Cornea, Flavia. "Evaluation of an alternative extraction method of PCDD/Fs from flue gas samples." Thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-124550.

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Ashour, Hassan. "Novel DNA damage induced pathways to cancer : the role of PCAF histone acetyltransferase." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/novel-dna-damage-induced-pathways-to-cancer-the-role-of-pcaf-histone-acetyltransferase(88b6b778-6ab5-49d9-8a44-1e1d49fb3caf).html.

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Cell cycle checkpoints act as surveillance system and following DNA damage caused by ultraviolet (UV) or ionising irradiation (IR), ATM and ATR phosphorylate various downstream substrates that preserve the genome integrity. The tumor suppressor protein p53 is a target for ATM/ATR kinases and modulates the expression of target genes involved in DNA damage response and promotes DNA repair, cell cycle arrest, and apoptosis. ATM/ATR and Chk2 phosphorylates p53 at Ser15 and Ser20 respectively. PCAF belongs to histone acetyltranferases (HATs) family and they acetylate nucleosomal and free histones as well as non-histone proteins such as p53. PCAF acetylates p53 at Lys320 which enhance p53 binding affinity to target genes and increasing p53 mediated transcriptional activity respectively. Our hypothesis is that the ATM/ATR induced pathway might modulates PCAF activation since PCAF protein sequence has shown to contain four putative ATM/ATR target sites as well as two Chk1/Chk2 sites. Also, p53 contributes in PCAF regulation. Our results show that PCAF regulation is cell specific and different cellular stresses introduce different post-translational modifications on PCAF. p21 is known to be targeted by p53 and PCAF following DNA damage, and our results have shown an elevation in p21 mRNA levels in U2OS (p52+/+) cells and a decrease in Saos-2 (p53-/-) and pEBS7(ATM-/-) cells following etoposide treatment, which suggests that both ATM and p53 are required for PCAF to be fully activated in ATM induced pathway. PCAF and PCAF k-r mutant, which lack the auto-acetylation region, were over-expressed and assessed under different cellular stresses by measuring the p21 tagged promoter for luciferase (p21 luc) and p21 mRNA levels. Following UV treatment, both the p21 mRNA and p21 luc levels were highly elevated in PCAF k-r over-expression in U2OS cells. Also, PCAF defective mutant, PCAF∆HAT, has shown different impact on PCAF activity under different genetic insults in comparison to PCAF k-r mutant. . . Our findings suggest that ATM, ATR induced pathways andChk2 kinase negatively regulate PCAF activity since the co-expression of the latter kinases with PCAF, downregulated PCAF proteins abundance and p21-luc levels in etoposide treated cells following the over-expression of PCAF. In UV induced pathway, Chk1 kinase seems to have a positive effect on PCAF as p21 luc promoter levels were downregulated in U2OS cells co-expressed with Chk1 kinase dead mutant. Our chromatin immunoprecipitation data indicates that p53 is highly recruited on PCAF’s own promoter in U2OS cells following etoposide treatment, which suggests a regulatory role of p53 on PCAF regulation. Moreover, the recruitment of PCAF and p53 on p21 promoter seems to be determined by the nature of the damage signal.

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45

Hess, Philipp. "The determination and environmental significance of planar aromatic compounds in the marine environment." Thesis, Robert Gordon University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388494.

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46

Neumann, Stefan. "Reduzierte Produkte von Halbordnungen eine Verallgemeinerung der Shelahschen pcf-Theorie /." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960012982.

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47

Cheng, Yao-Chiang, and 鄭銚強. "Investigation of PCDD/PCDF Formation by Inhibitors in Laboratory-scale Experimental System." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/10442761798255006376.

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碩士
國立中央大學
環境工程研究所
92
Polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) are very toxic compounds mainly emitted from municipal solid waste incinerators(MSWI). These compounds will affect human health when inhaled. Activated carbon injection (ACI) and SCR decompostition are two major end-of-pipe pollution control technologies currently used. It is proved that addition of inhibitors (such as sulfur, SO2, urea, alkaline materials) could decrease formation of dioxins. Experimental results indicate that addition of sulfur in incineration process can reduce PCDD/F formation. PCDD/F formation can be effectively reduced when S/Cl molar ratio is about 2. Dioxins decrease dramatically at SO2/HCl ratio as 0.55. The sulfur component will react with Cl2 and convent it into HCl. In addition, S or SO2 affect dioxin formation by vulcanizating phenolic precursors and catalysis metal, thus inhibiting chlorination reaction. Calcium hydroxide can reduce dioxin formation by more than 90﹪when Ca/Cl molar ratio is over 0.5. Addition of urea can also reduce PCDD/F formation about 50~87﹪when N/Cl mole ratio is about 0.1. The role of urea is to block catalysis metal and to form complex compounds with Cu and to prevent Ullmann reaction. Inhibition of dioxins formation will be the best way to reduce dioxin emissions. The cost of applying inhibitors for reducing dioxin formation is considerably lower than that of using activated carbon injection (ACI) and SCR decompostition. Adding inhibitors technology has a good potential for controling dioxins formation and emission in the future.

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48

Liu, Chun-Hu, and 劉純湖. "The PCDD/PCDF/PCB Levels in Breast Milk Samples Collected in Tainan Area." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/ps289u.

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碩士
國立成功大學
環境醫學研究所
90
Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are broadly distributed environmental contaminants. PCDDs/PCDFs/PCBs are highly stable in the environment. They are lipophilic and can be bioaccumulated via food chain into human bodies with long half-lives of elimination. The adipose tissue, blood, and breast milk are usually analyzed for the assessment of human exposure to PCDDs/PCDFs/PCBs. Among these three types of specimen, analysis of breast milk for exposure assessment provides two specific advantages. First, the collection of breast milk is noninvasive. Second, the analytical data can be used to assess the exposure of both the mother and the infant. The objectives of the study are (1) to measure the PCDDs/PCDFs/PCBs levels in breast milk samples collected in Tainan area, and (2) to utilize these data to evaluate infant’s exposure via breast-feeding. 　　The samples were collected from NCKU, Sin-Lau, and Chi-Mei hospitals in Tainan city. Breast milk samples were collected from 41 volunteers in these hospitals in years 2000 and 2001. Breast milk lipids were extracted by ethanol and n-hexane, followed by sulfuric acid digestion. For the analysis of 17 PCDDs/PCDFs, the extracts were fractionated with ion exchange (SCX), silica (Si), and Florisil solid phase extraction columns, and the fraction containing dioxins and furans were analyzed by gas chromatography-high resolution mass spectrometry (GC-HRMS). For the analysis of PCBs, only Florisil column fractionation was used, and 36 PCB congeners were analyzed by gas chromatography electronic capture detector (GC-ECD). 　　The average age of the subjects in this study was 30 years (N = 37, SD = 3.6 yrs). The total concentration of 17 dioxin congeners in the breast milk was 213 �b 141 pg/g-lipid. The concentration can be expressed as 12.7 �b 8.40 pg-I-TEQ/g-lipid when the international toxic equivalences (I-TEQs) of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) is calculated, or 14.6 �b 9.26 pg-WHO-TEQ/g-lipid using WHO toxic equivalences (WHO-TEQs). The total concentration of 36 PCB congeners in breast milk was 96.8 �b 96.0 ng/g-lipid. The data represent these mothers’ exposure, and infants’ exposure through breast-feeding nursing can be estimated. Assuming that the breast milk intakes per day for an infant are 805 mL in the first two months after birth, 810 mL in the third month, and 925 mL from the 4th to the 6th month respectively, with an absorption efficiency of 95 %, the average infant’s dioxin/furan exposure was estimated to be 216 �b 129 pg-I-TEQ/day (or 250 �b 148 pg-WHO-TEQ/day). Due to the weight difference between boys and girls, these values translate into 34.9 �b 20.7 pg-I-TEQ/kg/day (40.5 �b 23.8 pg-WHO-TEQ/kg/ day) for boys, and 40.1 �b 23.8 pg-I-TEQ/kg/day (46.5 �b 27.3 pg-WHO-TEQ/kg/ day) for girls. Using the same model, the average infant’s exposure to 36 PCBs was estimated to be 2671 �b 2526 ng/day, or 431 �b 408 ng/kg/day for boys and 495 �b 465 ng/kg/day for girls.

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49

Wang, Hsiao-Jou, and 王曉柔. "Exposure assessment of PCDD/PCDF/Co-PCBs for workers of secondary copper smelter." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/50353486686424917961.

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碩士
國立成功大學
環境醫學研究所
93
The objective of this study was to determine the concentrations of serum PCDD/F/Co-PCBs of operation workers, the concentrations of airbrone PCDD/Fs of working environment, and the relationship between serum PCDD/F/Co-PCBs levels and health index of workers in secondary copper smelting plant. The personal exposure data and time activity pattern were collected with questionnaires. And thirteen blood biochemistry examinations, immunological index and five hormones were examined. All the results were integrated to conduct the PCDD/F/Co-PCBs exposure assessment of workers. 46 blood samples and 4 air samples were collected and analyzed in this study. The highest TEQ levels of airborne PCDD/Fs was 34.8 pg WHO-TEQ/Nm3 sampled in the casting area at plant A, and lowest was in the casting area at plant B. The partitioning of gas/particle data showed the PCDD/Fs in particle phase was higher than gas phase. All workers were grouped to foreign and local workers, then local workers were grouped to high and low-level groups by the median of serum PCDD/Fs (29.5 pg WHO98-TEQDF/g lipid). The average serum PCDD/F/Co-PCBs levels in high, low-level and foreign groups were 41.0、20.9 and 20.4 pg-WHO-TEQ/g-lipid respectively. The TEQ levels of serum PCDD/F/Co-PCBs of all workers （28.6 pg WHO98-TEQDF/g lipid）was higher than that of general populations in Taiwan. Besides the abnormal rates of glucose in low-level group and GGT in foreign group were marginally significant lower than the high-level group, there were no significant differences of blood biochemistry, hormone, and immunological index among three groups. The dominating homologue of PCDD/Fs in blood and air samples are both PeCDFs and HxCDFs, it meant that the workers were potentially exposure to higher levels of PCDD/Fs emitted from secondary copper plant. The major congeners of Co-PCBs were PCB77, PCB169 and PCB126. The regression data showed serum PCDD/F/Co-PCBs were highly correlated with seniority and the exposure indices .The lifetime average daily does （LADD） of workers were met the range of WHO daily tolerance dose. The usage of personal protective measures was suggested to effectively reduce the exposure of PCDD/F/Co-PCBs.

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50

SHU, Jing-Fang, and 許菁芳. "The relationship between blood levels of PCB/PCDD/PCDF congeners and abnormal liver function in Yu-Cheng patients." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/10364812442109420204.

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碩士
國立成功大學
環境醫學研究所
88
Polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzo-p-furans (PCDFs) are among the most widespread environmental pollutants. Accumulation in human tissues with these lipophilic compounds is often considered as a potential threat to human health. Livers are the most sensitive organs observed in toxicological animal studies and consequential liver damages caused by the toxins are commonly observed. Several epidemiological studies have shown that occupational and non-occupational human exposures of PCBs, PCDDs and PCDFs, such as those of PCBs in transformer/capacitor factories and PCDDs/PCDFs in an industrial accident occurring in Seveso, Italy, were linked to abnormalities in liver function. In these studies, levels of total PCBs/PCDDs/PCDFs, rather than levels of specific PCB/PCDD/PCDF congeners, in the blood samples are often used to study their association with the health effects. Abnormalities in liver function and liver cirrhosis were also reported in the Yu-cheng patients in Taiwan. A nested case-control design was used within a cohort of subjects, 2061 Yu-cheng patients in Taiwan, which has been followed up by Guo and his co-workers since 1991. The study aims to investigate the relationship between blood levels of PCB/PCDD/PCDF congeners and observed abnormal liver function in Yu-cheng patients by measuring the concentrations of specific congeners in the blood samples. Gas chromatography-electron capture detection (GC-ECD) and gas chromatography-high resolution mass spectrometry (GC-HRMS) are utilized for the congener-specific measurements. PCB/PCDD/PCDF congener levels in the blood of 41 Yu-cheng patients were analyzed. The average concentration of the total PCDDs/PCDFs of the blood samples was found to be 6893 pg/g-lipid and the concentration of 1,2,3,4,7,8-HxCDF (1741pg/g-lipid) was the highest among seventeen PCDD/PCDF congeners determined in the blood samples. The average total PCBs concentration in the blood samples was found to be 2921 pg/mg-lipid and the concentration of PCB 28/31 (397pg/mg-lipid) was the highest among thirty-four PCB congeners. After adjustment for cholesterol and body mass index (BMI), there were statistically significant positive correlations between liver function and some PCB levels (PCB 28/31, 44, and 189).

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