Methods for the 11C-labeling of carbonyl compounds applicable in the preparation of radiotracers for Positron Emission Tomography (PET) are described. To this end [11C]carbon monoxide at low concentration was used in transition metal- mediated reactions. Stille couplings were employed in the synthesis of [carbonyl-11C]ketones from methyl and aryl halides with [11C]carbon monoxide. The synthesized [carbonyl-11C]ketones were obtained from the corresponding organostannanes with analytical radiochemical yields up to 98%. A number of synthetic routes were designed using [11C]carbon monoxide and rhodium complexes. Nitrene intermediates were generated from azides and reacted via a rhodium-mediated carbonylation reaction as a general synthetic route to [carbonyl-11C]isocyanates, versatile precursors. [carbonyl-11C]Isocyanate reacted via nucleophilic attack of an amine to form N,N’-diphenyl[11C]urea in 82% analytical radiochemical yield, ethyl phenyl[11C]carbamate was synthesized by the same route, using ethanol as the nucleophile, in 70% radiochemical yield. [11C]Isocyanate was also able to react in a [2+3] cycloaddition with ethylene oxide to form 3-phenyl[carbonyl-11C]oxazolidin-2-one in over 80% analytical radiochemical yield. This method was applied to the synthesis of a potential efflux system tracer [11C]hydroxyurea in 38% isolated radiochemical yield and the derivative 1-hydroxy-3-phenyl[11C]urea in 35% isolated radiochemical yield. Carbene intermediates, generated from diazo compounds, were reacted with [11C]carbon monoxide in the rhodium-mediated synthesis of [carbonyl-11C]ketenes. [carbonyl-11C]Ketene intermediates were utilised in the synthesis of diethyl[carbonyl-11C]malonate, from ethyl diazoacetate and ethanol. The product was obtained with a 20% isolated radiochemical yield. Alkylation of diethyl[carbonyl-11C]malonate, with ethyliodide and tetrabutylammonium fluoride, was successfully accomplished and diethyl diethyl[carbonyl-11C]malonate was synthesized in 50% analytical radiochemical yield. Several (carbonyl-13C)compounds were also synthesized using the described methods as a way of characterizing the position of the label using 13C-NMR.

Physisorption of CO and N2O on surfaces of ceria (CeO2) was investigated by means of high-level quantum-mechanical embedded cluster calculations. Both systems have high relevance in the field of environmental chemistry and heterogeneous catalysis. The CO/CeO2 system, has been investigated in a couple of both experimental and theoretical studies, but for the N2O/CeO2 system, this is the first study in the literature, experimental or theoretical. In physisorption, the interaction relies entirely on classical electrostatic interactions and electron dispersion forces. No covalent bond is formed between the molecule and the surface. A proper description of the dispersion requires some of the most accurate quantum-mechanical methods available, such as MP2 or CCSD(T). Moreover, even the most sophisticated methods cannot heal errors anywhere else in the theoretical treatment. Standard periodic models cannot be used with methods such as CCSD(T), but embedded cluster models can, and have been thoroughly explored in this thesis. In this thesis, embedded cluster models were constructed for the CeO2(110) and (111) surfaces. Using a range of assessment tests, it was verified that the electronic structure of the central region of a large and fully embedded surface cluster agrees well with the corresponding region in a periodic system. CO physisorption was investigated at the CCSD(T) level. Due to the prohibitively large expenses (in computer time) for standard CCSD(T) calculations, the method of increments, previously used in the literature for bulk systems, was extended to adsorption problems. It was found that, electron correlation contributes by 30 - 80% to the molecule-surface interaction and that the contribution depends on the topology of the surface. The calculated CO-ceria interaction energy is 20 kJ/mol for the (111) surface and 27 kJ/mol for the (110) surface. In low temperature TPD experiments for the N2O/CeO2(111) system, one surface species was found with an adsorption energy of about 29 kJ/mol. IR measurements showed stretching frequencies that are typically assigned to N2O adsorption with the O-end directed towards surface cations. However, theoretical calculations up to the MP2 level predicted two equally favorable adsorption species. Improvements in the structural model (larger clusters, consideration of molecule-induced relaxation) or the computational method (larger basis sets) did not affect this result. Only at the CCSD(T) level was one dominating surface species found, namely N2O adsorbed over a Ce ion, with the O-end of the molecule directed towards the surface. The calculated stretching vibrational frequency shifts (with respect to the gas phase) for this adsorbed species agree well with the measured IR spectra.

Background: Carbon monoxide (CO) is a toxic gas, but it is also produced endogenously when haem is degraded. When produced in vivo, CO is believed to have positive biological effects. For example it activates the production of cyclic guanosine mono-phosphate and causes vasodilatation. CO is also believed to have anti-inflammatory properties by binding to Mitogen activated protein (MAP) kinase. Several studies in cells, mice and rats support this opinion regarding both the circulatory as well as the anti-inflammatory properties. However, studies in larger animals regarding circulatory effects have demonstrated contradictory results. The only study in humans regarding anti-inflammatory properties of CO could not demonstrate such effects. Methods: This thesis consists of four different models. In paper I a method for analysis of CO in blood was developed using gas chromatography. In paper II a porcine model was used to investigate the elimination time for CO. The pigs in paper II had a high concentration of CO administered via blood, and CO concentrations were followed over time and kinetically parameters calculated. Circulatory parameters were also measured to evaluate if there were any circulatory changes after CO administration. In paper III CO´s anti-inflammatory properties were investigated in an endotoxin-induced systemic inflammatory model in pigs. Paper III was a randomized study where one group inhaled CO and the other group served as controls. Plasma cytokine concentrations were measured and followed over time as an indication of the inflammatory state. In paper IV, CO concentrations in blood from blood donors at the Blood Centre in Umeå were investigated. The blood donors also completed a questionnaire about age, smoking history and other possible sources for exogenous contamination of CO in the blood. Results and conclusions: In paper I we developed a method suitable for analysis of low concentrations of CO in blood. The half-life of CO at levels of 250 µM in pigs was found to be 60 minutes. CO did not show anti-inflammatory effects after an endotoxin-induced systemic inflammation in pigs. In banked blood CO was present at concentrations up to six times higher than normal concentrations. This could be a risk when transfusing such blood to susceptible patients.

Metal-organic frameworks are a new class of porous materials that have potential applications in gas storage, separations, catalysis, sensors, non-linear optics, displays and electroluminescent devices. They are synthesized in a "building-block" approach by self-assembly of metal or metal-oxide vertices interconnected by rigid linker molecules. The highly ordered nature of MOF materials and the ability to tailor the framework's chemical functionality by modifying the organic ligands give the materials great potential for high efficiency adsorbents. In particular, MOFs that selectively adsorb CO₂ over N₂, and CH₄ are very important because they have the potential to reduce carbon emissions from coal-fired power plants and substantially diminish the cost of natural gas production. Despite their importance, MOFs that show high selective gas adsorption behavior are not so common. Development of MOFs for gas adsorption applications has been hindered by the lack of fundamental understanding of the interactions between the host-guest systems. Knowledge of how adsorbates bind to the material, and if so where and through which interaction, as well as how different species in adsorbed mixture compete and interact with the adsorption sites is a prerequisite for considering MOFs for adsorptive gas separation applications. In this work, we seek to understand the role of structural features (such as pore sizes, open metal site, functionalized ligands, pore volume, electrostatics) on the adsorptive separation of CO₂, CO and N₂ in prototype MOFs with the help of molecular modeling studies (GCMC simulations). Our simulation results suggest that the suitable MOFs for CO₂ adsorption and separation should have small size, open metal site, or large pore volume with functionalized groups. Some of the experimental challenges in the MOF based adsorbents for CO₂ capture include designing MOFs with smaller pores with/without open metal sites. Constructing such type of porous MOFs can lead to greater CO₂ capacities and adsorption selectivities over mixtures of CH₄ or N₂. Therefore, in the second project, we focused on design and development of small pore MOFs with/without open metal sites for adsorptive separation of carbon dioxide from binary mixtures of methane and nitrogen. We have synthesized and characterized several new MOFs (single ligand and mixed ligand MOFs) using different characterization techniques like single-crystal X-ray diffraction, powder X-ray diffraction, TGA, BET, gravimetric adsorption and examined their applicability in CO₂/N₂ and CO₂/CH₄ mixture separations. Our findings from this study suggest that further, rational development of new MOF compounds for CO₂ capture applications should focus on enriching open metal sites, increasing the pore volume, and minimizing the size of large pores. Flue gas streams and natural gas streams containing CO₂ are often saturated by water and its presence greatly reduces the CO₂ adsorption capacities and selectivities. So, in the third project, we investigated the structural stability of the developed MOFs by measuring water vapor adsorption isotherms on them at different humid conditions to understand which type of coordination environment in MOFs can resist humid environments. The results of this study suggest that MOFs connected through nitrogen-bearing ligands show greater water stability than materials constructed solely through carboxylic acid groups.

Compounds labelled with 11C (β+, t1/2 = 20.4 min) are used in positron emission tomography (PET), which is a quantitative non-invasive molecular imaging technique. It utilizes computerized reconstruction methods to produce time-resolved images of the radioactivity distribution in living subjects. The feasibility of preparing [11C]methyl iodide from [11C]methane and iodine via a single pass through a non-thermal plasma reactor was explored. [11C]Methyl iodide with a specific radioactivity of 412 ± 32 GBq/µmol was obtained in 13 ± 3% decay-corrected radiochemical yield within 6 min via catalytic hydrogenation of [11C]carbon dioxide (24 GBq) and subsequent iodination, induced by electron impact. Labelled ethyl-, propyl- and butyl iodide was synthesized, within 15 min, via palladium-mediated carbonylation using [11C]carbon monoxide. The carbonylation products, labelled carboxylic acids, esters and aldehydes, were reduced to their corresponding alcohols and converted to alkyl iodides. [1-11C]Ethyl iodide was obtained via palladium-mediated carbonylation of methyl iodide with a decay-corrected radiochemical yield of 55 ± 5%. [1-11C]Propyl iodide and [1-11C]butyl iodide were synthesized via the hydroformylation of ethene and propene with decay-corrected radiochemical yields of 58 ± 4% and 34 ± 2%, respectively. [1-11C]Ethyl iodide was obtained with a specific radioactivity of 84 GBq/mmol from 10 GBq of [11C]carbon monoxide. [1-11C]Propyl iodide was synthesized with a specific radioactivity of 270 GBq/mmol from 12 GBq and [1-11C]butyl iodide with 146 GBq/mmol from 8 GBq. Palladium-mediated hydroxycarbonylation of acetylene was used in the synthesis of [1-11C]acrylic acid. The labelled carboxylic acid was converted to its acid chloride and subsequently treated with amine to yield N-[carbonyl-11C]benzylacrylamide. In an alternative method, [carbonyl-11C]acrylamides were synthesized in decay-corrected radiochemical yields up to 81% via palladium-mediated carbonylative cross-coupling of vinyl halides and amines. Starting from 10 ± 0.5 GBq of [11C]carbon monoxide, N-[carbonyl-11C]benzylacrylamide was obtained in 4 min with a specific radioactivity of 330 ± 4 GBq/µmol.

<p>Zr-based materials have found their main application in the nuclear field having high corrosion resistance and low neutron absorption cross-section. The oxide layer that is formed on the surface of these alloys is meant to be the barrier between the metal and the corrosive environment. The deterioration of this protective layer limits the lifetime of these alloys. A better understanding of the transport phenomena, which take place in the oxide layer during oxidation, could be beneficial for the development of more resistant alloys.</p><p>In the present study, oxygen and hydrogen transport through the zirconia layer during oxidation of Zr-based materials at temperatures around 400C have been investigated using the isotope-monitoring techniques Gas Phase Analysis and Secondary Ion Mass Spectrometry. The processes, which take place at oxide/gas and oxide/metal interface, in the bulk oxide and metal, have to be considered in the investigation of the mechanism of hydration and oxidation. Inward transport of oxygen and hydrogen species can be influenced by modification of the surface properties. We found that CO molecules adsorbed on Zr surface can block the surface reaction centers for H₂ dissociation, and as a result, hydrogen uptake in Zr is reduced. On the other hand, coating the Zr surface with Pt, resulted in increased oxygen dissociation rate at the oxide/gas interface. This generated enhanced oxygen transport towards the oxide/metal interface and formation of thicker oxides. Our results show that at temperatures relevant for the nuclear industry, oxygen dissociation efficiency decreases in the order: Pt > Zr₂Fe > Zr₂Ni > ZrCr₂ ≥ Zircaloy-2.</p><p>Porosity development in the oxide scales generates easy diffusion pathways for molecules across the oxide layer during oxidation. A novel method for evaluation of the gas diffusion, gas concentration and effective pore size of oxide scales is presented in this study. Effective pore sizes in the nanometer range were found for pretransition oxides on Zircaloy-2.</p><p>A mechanism for densification of oxide scales by obtaining a better balance between inward oxygen and outward metal transport is suggested. Outward Zr transport can be influenced by the presence of hydrogen in the oxide/metal substrate. Inward oxygen transport can be promoted by oxygen dissociating elements such as Fe-containing second phase particles. The results suggest furthermore that a proper choice of the second-phase particle composition and size distribution can lead to the formation of dense oxides, which are characterized by low oxygen and hydrogen uptake rates during oxidation.</p>

The impacts of emissions sources of carbon monoxide and particulate matter pollution levels for projected level conformity assessment and National Environmental Policy Act (NEPA) analyses are usually estimated through computer-aided models. Because of the involvement and interaction of a large number of variables that affect formation of CO and PM hot spots, exhaustive impact assessment studies can be time consuming. This is especially true for complex urban projects consisting of numerous roadways whose potential CO and PM impacts on surrounding neighborhoods must be disclosed. A highway project may consist of hundreds of roadway links, therefore undertaking project level conformity analysis without screening tools can be computationally resource intensive. CALINE4, a line source emission modeling tool, is used to predict downwind CO and PM concentrations for various receptors to generate a learning dataset for development of screening rules. This research has developed statistical screening criteria based on Classification and Regression Tree modeling that can be used to eliminate those links from the CALINE4 analysis whose contribution of pollutant concentration to a particular receptor site are insignificant. For the purpose of this study, any link that contributes a concentration of 0 ppm of CO or 0 µg/m3 of PM to a particular receptor site is termed insignificant for the corresponding pollutant. The model uses seven predictor variables, namely wind speed, wind directional variability, linear emission flux, link length and receptor polar coordinates. Response vector has two classes of pollutant concentrations namely significant and insignificant which are obtained by conversion of numerical values of pollutant concentration according to above mentioned criterion, thereby converting a regression problem into categorical or classification problem. The developed rules based on constructed model were validated through test samples and can be applied to future dataset to classify and screen out the insignificant links in highway planning analyses. The screening tool also allows analysts to prepare gridded pollution concentration predictions for use in environmental justice analyses.

Wood pellets have become a solid biomass fuel of choice because they are a standardized product with known quality properties. However, the self-heating and off-gassing tendencies during storage of wood pellets threatens the consistency of the pellets’ quality properties. The aim of this thesis was to increase the body of knowledge towards understanding of the off-gassing of wood pellets. The effects of total wood extractive content and types of extractives in the raw material on off-gassing of wood pellets were investigated through two separate studies. In the first study, the pellets were produced from fresh and pre-treated Scots pine sawdust. The pre-treatments involved storing, extraction and adding additive oils. The second study used synthetic pure cellulose that was pre-treated by adding different additive oils. The pellets were subjected to off-gassing tests under controlled conditions. The results from the first study showed that the total amount of extractives in the raw material has little effect on off-gassing. While gas emissions were reduced for stored and acetone extracted pine pellets, the coefficients of determination (R2) from the linear correlation analysis between off-gassing and the total extractive content of the raw materials were below 0.5 for all the three off-gasses indicating no correlation. The results of cellulose pellets with added additive oils in the second study showed that the off-gassing is highly dependent on the type of extractives in the raw material. The highest mean concentrations of the carbon oxides and methane were recorded from cellulose pellets with added linseed oil. Pellets with added linseed oil had higher off-gas emissions due to the high content of unsaturated fatty acids of 73.9% linolenic and 7.6% linoleic. Based on these results, it was concluded that one of the main causes of off-gassing during storage of wood pellets is the α-oxidation of unsaturated fatty acids. The other notable effect was that methane formation is dependent on anaerobic conditions, whereas formation of carbon oxides can occur both under aerobic and anaerobic conditions. / Wood pellets have over the years become a solid biomass fuel of choice for heat and power generation because they are a standardized product with known quality properties. However, the self-heating and off-gassing tendencies of wood pellets threatens the consistency of the quality properties. Self-heating and off-gassing can cause disintegration of the pellets resulting in dry matter losses and reduction in quality properties. Additionally, self-heating may lead to fires while off-gassing of toxic gasses such as carbon monoxide is a human health and environmental hazard. The aim of this thesis was to increase the body of knowledge towards the understanding of off-gassing of wood pellets. The results showed that total amount of extractives in the raw material has little effect on off-gassing. One of the main causes of off-gassing of carbon oxides by wood pellets is the α-oxidation of unsaturated fatty acids and other triglyceride oils that are chemically unstable. The other notable effect was that methane formation is dependent on anaerobic conditions, whereas formation of carbon oxides can occur both under aerobic and anaerobic conditions. / <p>This study was part of the project on secure and well-characterised raw materials and products through innovative adaption of pellets manufacturing processes (SVINPELS, project no 47997–1). This was a collaborative research project between Karlstad University and the Swedish University of Agricultural Sciences, SLU and was funded by the Swedish Energy Agency.</p>

Understanding the quality of the air we breathe is critical in quantifying the impact that atmospheric chemistry has on health. Poor air quality increases the risk of heart and lung diseases as well as having a detrimental effect on climate, ecology and the built environment. The burning of fossil fuels and plant matter (biomass burning) creates large quantities of gases and particulate matter that impact air quality and the air we breathe. Biomass burning is estimated to contribute 400 Tg of non-methane organic compounds, 40 Tg of methane and 7.1 Tg of nitrogen oxides to the atmosphere each year. This thesis aims to better understand the role of biomass burning on air quality and tropospheric chemistry. The in depth analysis presented here addresses of the impact of boreal biomass burning in North America on air quality, in particular, carbon monoxide (CO) and ozone (O3). By using a number of different modelling techniques along with data collected from a field campaign and satellites the transport and chemistry of biomass burning emissions were analysed and quantified. The first research chapter of the thesis used the GEOS-Chem atmospheric chemistry transport model to interpret aircraft measurements of CO in biomass burning outflow taken during the 2011 BORTAS-B campaign over Canada. The model has some skill reproducing the observed variability, but has a positive bias for observations < 100 ppb and a negative bias for observations > 300 ppb. It was found that observed CO variations are largely due to fires over Ontario, with smaller and less variable contributions from fossil fuel combustion from eastern Asia and NE North America. To help interpret observed variations of CO an effective physical age of emissions (¯A) metric was developed. It was found that during BORTAS-B the age of emissions intercepted over Halifax, Nova Scotia is typically 4–11 days, and on occasion as young as two days. The analysis shows that ¯A is typically 1–5 days older than the associated photochemical ages inferred from co-located measurements of different hydrocarbons. It is argued that a robust observed relationship between CO and black carbon aerosol during BORTAS-B (r² > 0.7), form the basis of indirect evidence that aerosols co-emitted with gases during pyrolysis markedly slowed down the plume photochemistry during BORTAS-B with respect to photochemistry at the same latitude and altitude in clear skies. The second research chapter focuses on O3 production downwind from boreal biomass burning. Using the GEOS-Chem model, the O3 chemistry within a biomass burning plume from a fire on 17 July 2011 in mid-Canada was examined. The model shows a significant positive bias (~20 ppb) in reproducingO3 mixing ratios over North America for July 2011 when compared to observations. Reducing NO emissions from lightning and fossil fuel by 50% and 54% respectively reduced this bias to ~10 ppb. The cause of the remaining bias is uncertain. Using a novel technique with the model, the centre of the biomass burning plume was tracked and O3 concentrations and chemistry was extracted from the centre of the plume. The biomass burning enhanced O3 concentrations throughout the plume by between 1 – 20 ppb when compared with the same plume path with no biomass burning. The plume was characterised as being NOx-rich for the initial four days of transport. The sensitivity of the O3 chemistry to different emissions was calculated and it was found that the O3 is initially highly sensitive to NO emissions from biomass burning and then to NO emissions from fossil fuels as it travels across an urban area surrounding Quebec City. The O3 net production was found to initially decrease with an increase in NO but increase further downwind. The final research chapter of the thesis uses long-term satellite observations to evaluate natural variability in CO concentrations over the North Atlantic. 15 years of MOPITT CO column observations were used along with modelled CO from the GEOS-Chem model. The model was evaluated against the MOPITT overpass and shows a negative bias of between -8% and -24% over the northern mid-latitudes with the largest bias seen in spring. The model has a large positive bias (8% – 40%) over the Amazon,West Africa and Indonesia through all seasons. Using Empirical Orthogonal Function (EOF) analysis on the MOPITT and GEOS-Chem CO columns shows the largest mode of variability seen in the North Atlantic to be the oxidation of methane for winter and spring, biomass burning during summer and fossil fuel combustion from East Asia during autumn.

Orientador: Antonio Carlos Dias Ângelo / Banca: Aguinaldo Robinson de Souza / Banca: Luiz Henrique Dall'Antonia / Resumo: A oxidação de pequenos compostos orgânicos, tais como: gás natural, metano, propano, metanol e etc., tem gerado um grande interesse para a utilização em células a combustível, pois, o hidrogênio pode ser obtido por reforma catalítica dos mesmos e ou por oxidação direta dos combustíveis. Porém, o eletrocatalisador mais utilizado para a oxidação, a platina, é facilmente envenenado pela adsorção química do monóxido de carbono (CO). O CO se adsorve de duas maneiras; a primeira, de forma linear, utilizando um sítio de platina e, a segunda, em forma de ponte, utilizando dois sítios, fazendo com que o rendimento e eficiência da célula a combustível seja comprometido. Assim torna-se necessário o desenvolvimento de eletrocatalisadores que sejam mais tolerantes ao envenenamento por CO. Uma alternativa seria os materiais intermetálicos, que são um tipo especial de liga metálica, formada de platina e outros metais M (M = Mn, Pb, Sb e Sn)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The oxidation of small organic compounds such as natural gas, methanol, ethanol etc.m has highly increased interest for utilization of such compounds in fuel cells, once the hydrogen can be easily obtained by catthalitic reform of the compounds or by direct oxidation of such fuels. However, platinum, which is the most used electrocatalyst is easily poisoned by chemical adsortion of carbon monoxide (CO). CO is adsorption in two different ways: in the first one, in a linearly configuration, the adsorption is performed using a platinum site, while in the second one it is performed, in a bridge configuration, using two sites, compromising performance and the efficiency of the fuel cell. For such a reason, the development of electrocatalyst which are more tolerant to CO poisoning is necessary. A potential alternative would be the intermetallic materials, which are special metallic alloy, formed by platinum and other...(Complete abstract, click electronic address below) / Mestre