Dissertations / Theses on the topic 'Gaston Co., N.C'

Hormis la préparation de l’acide salicylique et de l’urée, peu de tentatives ont été réalisées jusqu’à présent pour promouvoir la formation de liaisons C–C et C–N à partir du CO₂. Cette thèse présente de nouveaux procédés catalytiques permettant la formation de molécules organiques azotées grâce à la création de liaisons C–N et C–C par transformation catalytique du CO et du CO₂. Les cibles retenues sont les amides ainsi que les alkylamines qui sont essentiels en chimie organique fine et sont souvent d’origine pétrosourcés. Dans un premier temps, la synthèse d’amide par carbonylation formelle de la liaison C–N d'amine sera étudiée grâce à des catalyseurs à base de métaux carbonyles. Dans un second temps, des procédés d’homologation des amines seront décrits grâce à l’utilisation de catalyseurs métalliques. La première stratégie impliquera l’utilisation de catalyseur de cobalt, en présence de CO et de silanes et permettra l’homologation sélective des liaisons N-méthyle en N-éthyle sous de faible pression de CO (P = 8 bar) et jusqu’au N-pentyle sous de fortes pressions. Dans un second temps, l’utilisation d’un catalyseur de ruthénium en présence d’un gaz de synthèse (CO/H₂) nous permettra de démontrer la possibilité de l’homologation de la diphénylamine. Enfin, la compréhension de ce système nous permettra de transposer cette réaction à l’utilisation du CO₂ comme substitut du CO
Apart from the preparation of salicylic acid and urea, few attempts have been made so far to promote the formation of C-C and C-N bonds from CO₂. This thesis describes new catalytic processes allowing the formation of nitrogen compounds through the creation of C-N and C-C bonds by catalytic transformations of CO and CO₂. The chosen targets are the amides and the alkylamines which are essential in fine organic chemistry and yet prepared from petrochemicals. In a first part, the amide synthesis by formal carbonylation of the C-N bond HAS been studied using catalysts based on first row transition metal carbonyl complexes. In a second part, methods enabling homologation of amines are described through the use of metal catalysts. The first strategy involved the use of cobalt catalysts in presence of CO and hydrosilanes which allow the selective homologation of N-methyl into N-ethyl derivatives under a low CO pressure (P= 8 bar). Also, the alkyl chain can be homologated under elevated CO pressures to reach N-pentyl derivatives. Finally, the use of a ruthenium catalyst in presence of a synthesis gas (CO / H₂) allowed us to demonstrate the possibility of the homologation of the diphenylamine. Understanding this system led to translate the amine homologation with syngas to the use of CO₂ as a substitute for CO

Theoretische Berechnungen sagen für tetragonal gedehntes Fe-Co eine hohe magnetokristalline Anisotropie voraus, wie sie für seltenerdfreie Dauermagnetwerkstoffe vorteilhaft wäre. In dieser experimentellen Arbeit werden epitaktische Fe-Co-Schichten strukturell und magnetisch charakterisiert. Zur Untersuchung der Dehnung in diesen Schichten eignen sich AuxCu100-x-Pufferschichten besonders, da über die Stöchiometrie (x) deren lateraler Gitterparameter eingestellt werden kann. Wird Fe-Co auf einer solchen Pufferschicht abgeschieden, erfolgt aufgrund dessen hoher elastischer Energie schon in den ersten Monolagen eine vollständige Relaxation der pufferinduzierten Dehnung. In ternären Fe-Co-X-Schichten, in denen kleine X-Atome (X = B, C oder N) Oktaederlücken besetzen, wird jedoch eine spontane tetragonale Dehnung c/a bis zu 1,05 beobachtet. Entlang der gedehnten c-Achse tritt eine uniaxiale magnetokristalline Anisotropie auf, die für B- oder C-Zulegierungen von 2 at% eine maximale Anisotropiekonstante von 0,4 MJ/m³ zeigt. Wird der X-Gehalt weiter erhöht, nehmen die Kristallinität der Schichten und die magnetische Anisotropie ab. Neben der magnetokristallinen Anisotropie des Schichtvolumens wird an den Fe-Co(-X)-Schichten eine hohe Grenzflächenanisotropie beobachtet. Der Beitrag der freien Oberfläche übersteigt den der Au-Cu-Grenzfläche dabei deutlich
Theoretical calculations predict a high magnetocrystalline anisotropy for tetragonally strained Fe-Co, which would be beneficial for rare-earth free permanent magnet materials. In this experimental work, epitaxial Fe-Co films are investigated structurally and magnetically. AuxCu100-x buffer layers are very suitable to study the strain in these films since their in-plane lattice parameter can be tailored via the applied stoichiometry (x). However, when Fe-Co is deposited on such a buffer layer, the induced strain of the Fe-Co lattice relaxes completely within the first monolayers, due to its high elastic energy. In ternary Fe-Co-X films, where small atoms X like B, C or N occupy octahedral interstitial sites, a spontaneous strain c/a up to 1.05 is observed. A uniaxial magnetocrystalline anisotropy along the strained c axis appears. Their maximum anisotropy constant is 0.4 MJ/m³ for B or C contents of 2 at%. If the X content is further increased, the crystallinity and thus, the magnetic anisotropy of the films degrade. Together with the magnetocrystalline anisotropy of the films’ volumes, a high interface anisotropy is observed for the Fe-Co(-X) films. The contribution of the free surface clearly exceeds the contribution of the Au-Cu interface

Thesis (M.S.)--University of Toledo, 2008.
Typescript. "Submitted as partial fulfillments of the requirements for The Master of Science in Biology." "A thesis entitled"--at head of title. Bibliography: leaves 35-40.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In order to develop a new Pt-free reducing agents for oxygen reduction reaction (ORR), the ligands 1 - (2-Pyridylazo)-2-naphthol (PAN) and 4-(2-pyridylazo)-resorcinol (PAR) were studied as nitrogen sources complexing with Fe (II) and Co (II) ions, supported on carbon nanoparticles (10 wt. % metal loading) and heat treated at temperature of 500, 700 and 900°C. The synthesized complexes ([ML₂]; M²⁺= Fe, Co; L = PAN, PAR) were characterized by UVVis and Infrared spectroscopies before impregnation step. By cyclic voltammetric technique it was found that all eletrocatalysts showed an increase of performance for ORR after heat treated and that the highest efficiency were reached by: Fe-PAN/C -700°C (0,818 V x ENH), Fe-PAN/C- 900 °C (0,786V x ENH), Co-PAN/C - 500 °C (0,657V x ENH) e Co-PAN/C - 700°C (0.673 V x ENH), e Co-PAN/C - 900°C (0.612 V x ENH), Co-PAR/C - 700°C (0.588 V x ENH), Co-PAR/C - 900°C (0.623 V x ENH) e Fe-PAR/C - 700°C (0.598 V x ENH). With EDR studies, it was possible to calculate, with Koutecký Levich equation, the number of electrons involved in the ORR for each catalyst at potentials of 0.1, 0.2, 0.3 and 0.4 V. Except COPAR-700 °C which the adopted method did not allow the the number of electrons, the other catalysts, which were calculated were nearer the behavior of a mechanism via 2 and 4e- while others saw.
Com o intuito de desenvolver um novo agente redutor livre de platina para reacção de redução de oxigênio (RRO), os ligantes de 1 - (2-Piridilazo)-2-naftol (PAN) e 4 - (2-piridilazo)- resorcinol (PAR) foram estudados como fontes de nitrogenio complexantes com os íons Fe (II) e Co (II), suportados em nanopartículas de carbono (10% de carga de metais) e tratados termicamente a uma temperatura de 500, 700 e 900 °C. Os complexos sintetizados ([ML₂]; M²⁺ = Fe, Co, L = PAN, PAR) foram caracterizados por UV-Vis e espectroscopia de infravermelho antes da etapa de impregnação. Pela técnica de voltametria cíclica, verificou-se que todos os catalisadores mostraram um aumento de desempenho para a RRO após o tratamento térmico e que a maior eficiência foram alcançados por: Fe-PAN/C -700°C (0,818 V x ENH), Fe-PAN/C- 900 °C (0,786V x ENH), Co-PAN/C - 500 °C (0,657V x ENH) e Co-PAN/C - 700°C (0.673 V x ENH), e Co-PAN/C - 900°C (0.612 V x ENH), Co-PAR/C - 700°C (0.588 V x ENH), Co- PAR/C - 900°C (0.623 V x ENH) e Fe-PAR/C - 700°C (0.598 V x ENH). Com os estudos de EDR, foi possível calcular, com a equação de Koutecky-Levich, o número de eletrons envolvidos na RRO para cada catalisador nos potenciais de 0,1, 0,2, 0,3 e 0,4V. Com exceção do CoPAR-700°C o qual o método adotado não permitiu que fosse calculado o número de elétrons, os demais catalisadores, apresentaram comportamento próximos do mecanismo via 2e- enquanto outros via 4e-.

Cette these presente la synthese et la caracterisation de nouveaux complexes monomeres du fer en serie pentaphenylcyclopentadienyle (c#5ph#5)fe(co)(l), (l = co, pme#3) et de complexes homobimetalliques du fer en serie pentaphenyl- et pentamethyl- cyclopentadienyle a ligands pontants bis-acetylure. Les complexes alkyle fonctionnels, obtenus par addition nucleophile sur le complexe carbenique (c#5ph#5)fe(co)(pme#3)(=chome)pf#62, presentent un centre metallique stereogenique, et un atome de carbone c# chiral. Ces complexes sont isoles avec une bonne diastereoselectivite (85/15). Les composes fonctionnels obtenus de type (c#5ph#5)fe(co)(pme#3)(ch(ome)r) constituent des briques elementaires pour acceder a de nouveaux complexes bimetalliques. La synthese de nouveaux synthons organometalliques a ligand aromatique azote et a ligand acetylure, de formule generale (c#5ph#5)fe(co)(l)((co)#ncc)#xy) (l = co, pme#3 ; n = 0, 1 ; x = 1, 2) a ete realisee. Ces composes peuvent aussi permettre l'elaboration de nouveaux complexes bimetalliques. La reaction des monomeres (c#5ph#5)fe(co)#2(cc-cch) 18 et (c#5me#5)fe(dppe)cl conduit au complexe binucleaire polarise (c#5ph#5)fe(co)#2(-cc-cc)fe(c#5me#5)(dppe) 25. La voltammetrie cyclique met en evidence l'interaction du greffon (c#5me#5)fe(dppe) sur le greffon (c#5ph#5)fe(co)#2 par l'intermediaire du pont butadyinediyle. Le derive bimetallique 25 est facilement oxyde par un sel de ferricinium, permettant l'obtention du complexe stable (c#5ph#5)fe(co)#2(-cc-cc)fe(c#5me#5)(dppe)pf#6 27. La bande d'intervalence, de faible intensite, de ce dernier montre l'existence d'un couplage entre les deux centres metalliques. Les complexes (c#5ph#5)fe(co)#2(-cc-cc)fe(c#5me#5)(dppe) 25 et (c#5ph#5)fe(co)#2(-cc-cc)fe(c#5me#5)(dppe)pf#6 27, fortement polarises, pourraient presenter des proprietes en optique non lineaire

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia
Due to the increase of animal production throughout the world, also increase the amount of dairy cattle manure and consequently the environmental impacts associated with their inadequate management. One of the treatment techniques more adequate is the anaerobic digestion, which allows obtaining two valorizable products: biogas which can be used as a source of energy and a digested efluent that can be used as agricultural fertilizer. This work aims to study the potential use of a cattle farm effluent on AD. Therefore, it was necessary to collect data relating to the flow analysis and then, make the experimental design according to the needs inherent to this type of farming. For waste treatment from a cattle farming unit for milk production by AD, it was expected that the process had low viability owning the residue characteristics. Therefore it was used an agricultural waste for the process of anaerobic co-digestion. The residue selected as cosubstrate to the mixture of manure / washing waters, was a liquid residue from a surplus harvest of Pear Rocha from the region of Mafra. From the results it can be concluded that the co-digestion of these two residues can contribute to a sustainable management at a farm scale level. We can deduce this since it we proved the viability of the process.

PhD
The overall objective of this thesis is to provide additional data to assist clinicians and experimental neurologists alike in the quest for better understanding, more accurately diagnosing and more successfully treating patients suffering from Parkinson’s disease (PD). The general theme of the thesis is the interaction between certain environmental stimuli, including the exposure to adverse events during early central nervous system (CNS) development and the manifestation of elements of neurodegeneration, whether by means of neurochemical changes or expressed as a dysfunctional voluntary motor system. The first chapter provides a general introduction to the research theme of the thesis. This includes, in particular, a discussion on current understanding concerning the etiology and clinical profile of PD, the relative contribution made by genetic factors compared to environmental ones, and current treatment strategies for treating the disease. Mention is also made of the failure of these therapeutic applications for reversing or protecting against the disease, due to the side-effects associated with them. The material covered in chapter 1 provides the basis for the more complete discussion concerning these various aspects, contained in the chapters to follow. The overall aim was also to characterise the effects of commonly used toxin-induced animal models of PD, and the extent of vulnerability that the CNS displays towards them. The destruction of dopaminergic neurons following the administration of 6-OHDA at targeted points along the nigrostriatal tract is used extensively to model PD pathology in rats and is an established animal model of the disease. However, mature or even aged animals are mainly used in these studies, while the effects that the toxin might have on the developing CNS remain unclear. The study reported in chapter 4 aimed to elucidate some of 6-OHDA’s actions on the young adolescent (35 days-old) CNS by comparing the motor and biochemical effects of a unilateral infusion of the toxin into two anatomically distinct basal ganglia loci: The medial forebrain bundle (MFB) and the striatum. Animals were randomly assigned to receive either a direct delivery of 6-OHDA (12μg/4μl) into the MFB or an indirect injection, into the striatum. Although both lesion types were used, the MFB model is considered a more accurate portrayal of end-stage PD, while the striatum-model better reflects the long-term progressive pathology of the disease. The different lesions’ effects on motor function were determined by observing animal’s asymmetrical forelimb use to correct for weigh shifting during the vertical exploration of a cylindrical enclosure. Following the final behavioral assessment, the concentration of dopamine (DA) and DA metabolites remaining in the post-mortem brains were determined using 4 HPLC electrochemistry (HPLC-EC) and the levels compared between the two groups. The HPLC-EC results revealed a compensatory effect for DA production and DA turnover on the lesioned hemisphere side of the toxin-infused animal group. Thus, following 6-OHDA treatment, there appears to be extensive adaptive mechanisms in place within the remaining dopaminergic terminals that may be sufficient for maintaining relatively high extracellular and synaptic concentrations of DA. However, since substantial changes in motor-function were observed, it is suggested that the capacity of the remaining dopaminergic neurons to respond to increased functional demands may be limited. In addition, the behavioral results indicate that the distinct indices relating to different functional deficits depend on the lesioning of anatomically distinct structures along the nigrostrial tract. It has long been known that far fewer women are diagnosed with PD than men are. This seeming protection offered to females against degenerative disease of the CNS may relate to estrogen, although the hormone’s mechanism of action on the dopaminergic system is poorly defined. With an estimated 10-15 million women using oral contraceptives (OCs) in the United States alone, the aim of chapter 2 was to examine the evidence for a possible relationship between PD and the female reproductive hormone estrogen. A review of the current literature available on the topic was performed by consulting Medline, and by performing a search of the case-reports contained within the World Health Organization’s (WHO) International Drug Monitoring database, for possible PD-related symptoms that may arise from estrogen replacement therapy (ERT). The results, whilst conflicting, seem to suggest that estrogen protects women from obtaining the disease, or at least some features of it. Intensive research efforts are called for, with sufficient power to establish the relationship between ERT and the onset and development of parkinsonism. Chapter 3 reports on the results obtained from an experiment that subjected young Sprague-Dawley rats, 35 days of age, to a lower and a higher dose of 6-OHDA delivered to the MFB. Control rats received equivalent saline infusions. At 14 days post-surgery, the rats were evaluated for forelimb akinesia. For the higher dose of 6- OHDA the female rats were less impaired than males in making adjustment steps in response to a weight shift and in the vibrissae-evoked forelimb placing test. In addition, Tyrosine hydroxylase (TH) immunoreactivity was significantly higher for the female rats. Early gender differences in cell survival factors and/or other promoters of neuroplasticity may have contributed to the beneficial outcome seen in the females. For example, nerve growth factor (NGF) was found to be higher in the female rats following administration of the DA neurotoxin. It is unclear whether gonadal steroids are involved, and, if so, whether female hormones are protective or whether male hormones are prodegenerative. Determining the mechanisms for the improved outcome seen in the young female rats may lead to potential treatment strategies against PD. 5 Many studies have shown that early life stress may lead to impaired brain development, and may be a risk factor for developing psychiatric diseases, including clinical depression. However, few studies have investigated the impact that early stress may have on the onset and development of neurodegenerative disorders such as PD. The study reported on in chapter 5 conjointly subjected rat pups to a maternal separation (MS) paradigm that is a well characterised model of adverse early life events, and a unilateral, intrastriatal injection of 6- OHDA. The combined effects of these models on motor deficits and brain protein levels were investigated. Specifically, the animals were assessed for behavioral changes at 28 days postlesion with a battery of tests that are sensitive to the degree of DA loss sustained. The results show that animals that had been subjected to MS display poorer performance in the vibrissae and single-limb akinesia test compared to non-MS control animals (that had also been subjected to the toxin exposure). In addition, there was a significant increase in the loss of TH staining in MS rats compared to non-MS ones. The results from this study therefore suggest that exposure to adverse experiences during the early stages of life may contribute towards making dopaminergic neurons more susceptible to subsequent insults to the CNS occurring during mature stages of life. Therefore, taken together, early exposure to stress may predispose an individual towards the onset and development of neurodegenerative disease, which especially becomes a threat during the later stages of adult life. Moreover, within the framework of these characteristics, the capacity of a widely-used pharmacological agent (statins) was tested for possible future therapeutic application in PD (chapter 7). Although the precise cause of sporadic PD remains an enigma, evidence suggests that it may associate with defective activity of complex I of the mitochondrial electron transport chain. Mitochondrial DNA transmit and express this defect in host cells, resulting in increased oxygen free radical production, depressed antioxidant enzyme activities, and greater susceptibility to apoptotic cell death. Simvastatin is a member of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) group of drugs that are widely used for lowering cholesterol levels in patients who display elevated concentrations of low-density lipoprotein cholesterol. The study aimed to investigate the effects that statin-treatment have on motor-function and at the mitochondrial-protein level, using rotenone, a mitochondrial complex I inhibitor, as a rat-model of PD. Adult male Sprague-Dawley rats were treated either with simvastatin (6mg/day for 14 days) or with a placebo. Two different tests to assess motor function were used: The apomorphine-rotation test, and the vibrissae-elicited forelimb placement test. Following the drug administration protocol, the nigrostriatal tract was unilaterally lesioned with either rotenone (3 μg/4 μl) or, for the controls, were sham-operated by infusing the vehicle (DMSO:PEG) only. Five days later the rats were killed and a highly purified concentration of isolated mitochondria was prepared from the substantia nigra (SN) sections. 2- 6 Dimensional electrophoresis (2-DE) with subsequent identification of the spots using electronspray ionization quadruple time-of-flight mass spectrometrical (ESI-Q-TOF MS) was performed and the results BLAST-searched using bio-informatics tools for naming the identified peptides. The motor test results indicate that while unilateral rotenone causes behavioral asymmetries, treatment with simvastatin improved motor function relative to the rotenoneinduced ones. Mass Spectroscopy identified 23 mitochondrial proteins that differ significantly in protein expression (p < 0.05) following simvastatin treatment. The altered proteins were broadly classified according to their cellular function into 6 categories, with the majority involved in energy metabolism. This study effectively illustrated how neuroproteomics, with its sophisticated techniques and non-biased ability to quantify proteins, provides a methodology with which to study the changes in neurons associated with neurodegeneration. As an emerging tool for establishing disease-associated protein profiles, it also generates a greater understanding as to how these proteins interact and undergo post-translational modifications. Furthermore, due to the advances made in bioInformatics, insight is created concerning their functional characteristics. Chapter 4 summarises the most prominent proteomics techniques and discuss major advances made in the fast-growing field of neuroproteomics in PD. Ultimately, it is hoped that the application of this technology will lead towards a presymptomatic diagnosis of PD, and the identification of risk factors and new therapeutic targets at which pharmacological intervention can be aimed. The final chapter (chapter 8) provides a retrospective look at the academic work that had been performed for the purpose of this thesis, recaps on the main findings, and also highlights certain aspects of the project and provides relevant suggestions for future research. Lastly, the appendix provides a detailed overview of the methods followed for the experiments described in this thesis. It provides not only a comprehensive description of the techniques that had been followed, but provides information concerning the care taken with the animals (i.e. post-surgery) in order to control for the potential influence of experimental variables on the results.

El presente informe tiene como objetivo analizar el recurso de anulación de laudo, respecto a la causal c) del Decreto Legislativo N°1071, es decir que, por algún motivo, las actuaciones arbitrales no se han llevado a cabo conforme a lo acordado por las partes o al reglamento arbitral aplicable. Para ello, se parte del contenido de la Resolución N° 11, de fecha 27 de agosto de 2020, recaída en el Exp. N° 00677-2018-0-1817-SP-CO-01, emitida por la Primera Sala Civil con Subespecialidad Comercial de la Corte Superior de Justicia de Lima. En dicha resolución se declara fundado el recurso de anulación de Laudo, dado que, conforme al criterio de la Sala, dicho laudo carece de motivación o incurre en motivación aparente lo que genera una vulneración al debido proceso, derecho constitucional continente de la debida motivación. Se ha realizado una investigación multimodal: se han abordado todos los temas fundamentales desde un enfoque cualitativo y cuantitativo, con la finalidad de establecer la adecuada relación de aquellas instituciones procesales, cuyo origen radica del ordenamiento constitucional y/o procesal civil y que pueden trasladarse, con los adecuados matices, al arbitraje. En ese sentido, se ha revisado tanto, textos académicos elaborados por la doctrina más cercana a las materias analizadas, jurisprudencia y normas pertinentes a fin de responder los principales problemas jurídicos identificados. Finalmente, se ha llegado a la conclusión de la importancia de la motivación, deber transversal por su carácter constitucional, el cual no puede eludir ningún órgano decisor de carácter jurisdiccional.
The objective of this report is to analyze the appeal for annulment of the award, regarding cause c) of Legislative Decree No. 1071, that is to say that, for some reason, the arbitration proceedings have not been carried out in accordance with what was agreed by the parties or the applicable arbitration rules. For this, the content of Resolution No. 11, dated August 27, 2020, falls on Exp. No. 00677-2018-0-1817-SP-CO-01, issued by the First Civil Chamber with Subspecialty Commercial of the Superior Court of Justice of Lima. In said resolution the appeal for annulment of the Award is declared founded, since, according to the criteria of the Chamber, said award lacks motivation or incurs apparent motivation, which generates a violation of due process, a constitutional right containing due motivation. A multimodal investigation has been carried out: all the fundamental issues have been addressed from a qualitative and quantitative approach, in order to establish the appropriate relationship of those procedural institutions, whose origin lies in the constitutional and / or civil procedural order and that can be transferred, with the appropriate nuances, to arbitration. In this sense, academic texts prepared by the doctrine closest to the analyzed subjects, jurisprudence and pertinent norms have been reviewed in order to answer the main legal problems identified. Finally, it has come to the conclusion of the importance of motivation, a transversal duty due to its constitutional nature, which cannot be avoided by any decision-making body of a jurisdictional nature.

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Systems whose spectra are fractals or multifractals have received a lot of attention in recent years. The complete understanding of the behavior of many physical properties of these systems is still far from being complete because of the complexity of such systems. Thus, new applications and new methods of study of their spectra have been proposed and consequently a light has been thrown on their properties, enabling a better understanding of these systems. We present in this work initially the basic and necessary theoretical framework regarding the calculation of energy spectrum of elementary excitations in some systems, especially in quasiperiodic ones. Later we show, by using the Schr?odinger equation in tight-binding approximation, the results for the specific heat of electrons within the statistical mechanics of Boltzmann-Gibbs for one-dimensional quasiperiodic systems, growth by following the Fibonacci and Double Period rules. Structures of this type have already been exploited enough, however the use of non-extensive statistical mechanics proposed by Constantino Tsallis is well suited to systems that have a fractal profile, and therefore our main objective was to apply it to the calculation of thermodynamical quantities, by extending a little more the understanding of the properties of these systems. Accordingly, we calculate, analytical and numerically, the generalized specific heat of electrons in one-dimensional quasiperiodic systems (quasicrystals) generated by the Fibonacci and Double Period sequences. The electronic spectra were obtained by solving the Schr?odinger equation in the tight-binding approach. Numerical results are presented for the two types of systems with different values of the parameter of nonextensivity q
Sistemas cujos espectros s?o fractais ou multifractais t?m sido bastante estudados nos ?ltimos anos. O entendimento completo do comportamento de muitas propriedades f?sicas destes sistemas ainda est? longe de ser completamente efetivado devido ? complexidade dos pr?prios sistemas. Desta maneira, novas aplica??es e novos m?todos de estudo dos seus espectros t?m sido feitos, possibilitando uma melhor compreens?o acerca desses sistemas. Apresentamos neste trabalho de disserta??o inicialmente todo o arcabou?o te?rico b?sico e necess?rio no tocante ? obten??o dos espectros de energia de excita??es elementares em alguns sistemas, mais especificamente nos sistemas quasiperi?dicos. Posteriormente mostramos, usando a equa??o de Schrodinger na aproxima??o de liga??o forte, os resultados para o calor espec?fico de el?trons com a mec?nica estat?stica de Boltzmann-Gibbs para sistemas quasiperi?dicos unidimensionais tipo Fibonacci e Per?odo Duplo. Estruturas desse tipo j? foram bastante exploradas, no entanto o uso da mec?nica estat?stica n?o-extensiva proposta por Constantino Tsallis ? bem adequado para sistemas que apresentam de alguma forma um perfil fractal, e portanto nosso principal objetivo foi aplic?-la para o c?lculo de grandezas termodin?micas ampliando um pouco mais a compreens?o das propriedades desses sistemas. Neste sentido, calculamos anal?tica e numericamente o calor espec?fico generalizado de el?etrons em sistemas quasiperi?dicos unidimensionais (quasicristais) gerados pelas sequ?ncias de Fibonacci e Per?odo Duplo. Os espectros eletr?nicos foram obtidos fazendo-se uso tamb?m da equa??o de Schrodinger na aproxima??o de liga??o forte. Resultados num?ricos s?o apresentados para os dois tipos de sistemas com diferentes valores do par?metro de n?o-extensividade q

Algae that are grown in wastewater treatment lagoons could be an important substrate for biofuel production; however, the low C/N ratio of algae is not conducive to anaerobic digestion of algae with economically attractive methane production rates. Increasing the C/N ratio in anaerobic, laboratory scale, batch reactors by blending algal biomass with sodium acetate resulted i increased methane production rates as the C/N ratio increased. The highest amount of methane was produced when the C/N was 21/1. When the C/N was 24/1, the biogas production rate decreased. Batch experiments were done to evaluate the effect of optimizing the C/N ratio on methane production from algae and to identify the most essential information needed to conduct research on co-digestion of algal biomass using the continuous, high-rate, up-flow anaerobic sludge blanket (UASB) reactor system. Based on the results obtained from batch reactor experiments, anaerobic co-digestion of algal biomass, obtained by continuous centrifugation from the Logan City, Utah, 5th stage wastewater treatment lagoon, and sodium acetate was conducted using laboratory scale UASB reactors with the C/N ratio in the feedstock adjusted to 21/1. Duplicate, 34 L UASB reactor systems were built of poly(methyl methacrylate). Both reactors were seeded with 11 L of anaerobic sediment from the 3rd stage lagoon. The pH of the feedstock was adjusted to the neutral range. The feedstock was initially introduced at a low organic loading rate of 0.9 g/L.d with a hydraulic retention time (HRT) of 7.2 days and then increased up to 5.4 g/L.d and a HRT of 5.5 days. These organic loading rates corresponded to an initial influent chemical oxygen demand (COD) of 6.25 g/L and increased to 27.2 g/L. Methane production increased from 270 mL/g to 349 mL/g COD biodegraded. COD removal efficiency was 80% and biogas methane composition was 90% at steady state. Algal biomass contributed 33-50% of the COD in the feed stock depending on the COD of the algae paste from centrifugation. The shortest HRT at which steady state was not affected was 5.5 days. At lower HRT all monitored parameters showed a slight decrease after the 75th day of operation.

Ce travail est centré sur la synthèse de complexes du rhodium contenant un ligand azoté et leur mise en œuvre dans la réaction catalytique de carbonylation du méthanol en acide acétique. Dans une première partie, nous nous intéressons à la préparation de complexes neutres de formule générale [RhI2(CO)(L)] (L = amines, imidazoles et pyrazoles) et à quelques homologues chlorés. Ces complexes plans carrés manifestent une réactivité directement liée à l’encombrement stérique du ligand azoté L dans la réaction d’addition oxydante de l’iodomethane suivie de la cis-migration du groupement méthyle pour former l’espèce acétyle. Dans une deuxième partie, les complexes précédents ont été engagés dans des essais catalytiques de carbonylation du méthanol dans les conditions du procédé industriel. Comme il s’est avéré que les complexes neutres se transforment en espèce [RhI2(CO)2]- pour laquelle les contre-cations associés sont constitués du ligand azoté protoné ou methylé, nous avons effectué la préparation et la caractérisation des complexes [HNR3][RhI2(CO)2] ou [MeNR3][RhI2(CO)2]. Par IR, RMN et électrochimie, nous nous sommes intéressés aux phénomènes d’appariement d’ions et nous montrons qu’il s’agit dans le meilleur des cas d’interactions hydrogènes. Celles-ci influent la vitesse de la réaction oxydante de CH3I. Dans la dernière partie, nous avons complété une étude, précédemment initiée au laboratoire, sur le mécanisme, qui dans la dernière étape du cycle catalytique permet de passer de l’espèce acétyle [RhI3(COCH3)(CO)2]- à l’espèce active [RhI2(CO)2]- avec production de l’iodure d’acyle. A l’inverse du concept admis d’élimination réductrice de CH3COI suivie de son hydrolyse immédiate en CH3COOH et HI, nous montrons, avec l’appui de calculs théoriques (DFT) qu’en fait un ligand I- est substitué par un ligand acetate pour conduire à l’espèce [RhI2(OAc)(COCH3)(CO)2]-. L’élimination réductrice produit alors l’anhydride acétique qui est hydrolysé en CH3COOH régénérant [RhI2(CO)2]-. Un tel mécanisme opère en présence d’ions acetate dans les milieux faiblement hydratés visés par l’industriel
This study focuses on the synthesis and reactivity of rhodium complexes bearing N- containing ligands or counter-cations for the [Rh]-catalyzed methanol carbonylation reaction to produce acetic acid under the industrial Celanese Acid Optimization (AO) process conditions. In a first part, full synthesis and characterization of neutral Rh(I) square planar cis- [RhX(CO)2(L)] (X = Cl or I) complexes have been described, for which L is an N-ligand belonging to the amine, imidazole or pyrazole family. For the [RhI(CO)2(L)] complexes, variable-temperature 13C{1H} NMR spectroscopy has put in evidence a fluxional behavior for the different sized L ligands involved. The rate of this fluxional process reveals to be related to both electronic and steric contributions brought by L to the Rh center. These parameters (mainly steric), supported by single-crystal X-ray analyses in the solid state, also influence significantly the kinetics of the methyl iodide oxidative addition reaction followed by rapid CO migratory insertion, the overall being the rate determining step of the [Rh]-catalyzed methanol carbonylation cycle. In absence of CO, this reaction gives rise to the corresponding neutral Rh(III) acetyl complex, which immediately dimerizes to afford [Rh(μ- I)I(COMe)(CO)(L)]2 complex, for which several X-ray crystal structures have been obtained and studied. In addition, the surprising C-H activation in the case of a tBu-pyrazole ligand giving rise to a cyclometalated Rh dimer is reported. In a second part, the reactivity of the latter neutral Rh(I) [RhI(CO)2(L)] complexes as potential precursors has been investigated by batch experiments for the methanol carbonylation reaction. Mechanistic understanding via VT-HP-NMR experiments enabled to detect mainly anionic Rh(I) [RL][RhI2(CO)2] (R = H or CH3 according to the working conditions) complexes formed by decoordination followed by quaternization of the L ligand. Despite this result, the pyrazole family ligands showed better stability under the harsh process conditions. Thus, it cannot be ruled out that equilibrium between neutral and anionic species co-exist in the reaction medium at high temperatures and that [RL]I salt dissociation occurs, restoring the L ligand into the Rh coordination sphere. At this stage we focused on the anionic Rh(I) complex and prepared a series of [XNR3][RhI2(CO)2] (X = H or CH3) species, which have been fully characterized. Infrared, NMR, conductivity experiments and DFT model calculations together put in evidence ion interactions according to the nature of the ammonium counter-cation. Protonated cations significantly impact on the kinetics of the methyl iodide oxidative addition presumably due to H-interactions with the Rh square plane. The final part deals with the mechanism of the reductive elimination reaction, the last step of the [Rh]-catalyzed methanol carbonylation cycle, which from complex [RhI3(COCH3)(CO)2]-, regenerates [RhI2(CO)2]-. In contrast to the classically admitted mechanism of reductive elimination of CH3COI followed by subsequent hydrolysis to form AcOH and HI, we demonstrate from experimental DFT calculation that substitution of an iodo ligand by an acetate ion occurs to give rise to the [RhI2(OAc)(COCH3)(CO)2]- species. Thus, reductive elimination regenerates [RhI2(CO)2]- and produces acetic anhydride, which after hydrolysis affords two molecules of acetic acid. Such a mechanism operates under process conditions at low water content with a significant amount of acetate ions

Photocatalytic reactions with first-row transition metals are presented as a method for sustainable chemistry with great potential for new forms of reactivity and mechanistic pathways. Chapters 2 and 3 of this thesis discuss mechanism and reactivity of photoinduced, copper-catalyzed bond constructions. The Peters and Fu groups have reported that a variety of couplings of nitrogen, sulfur, oxygen, and carbon nucleophiles with organic halides can be achieved under mild conditions (−40 to 30 °C) through the use of light and a copper catalyst. Insight into the various mechanisms by which these reactions proceed may enhance our understanding of chemical reactivity and facilitate the development of new methods. We apply an array of tools (EPR, NMR, transient absorption, and UV−vis spectroscopy; ESI−MS; X-ray crystallography; DFT calculations; reactivity, stereochemical, and product studies) to investigate the photoinduced, copper-catalyzed coupling of carbazole with alkyl bromides. Our observations are consistent with pathways wherein both an excited state of the copper(I) carbazolide complex ([Cu^I(carb)₂]⁻) and an excited state of the nucleophile (Li(carb)) can serve as photoreductants of the alkyl bromide. The catalytically dominant pathway proceeds from the excited state of Li(carb), generating a carbazyl radical and an alkyl radical. The cross-coupling of these radicals is catalyzed by copper via an out-of-cage mechanism in which [Cu^I(carb)₂]⁻ and [Cu^II(carb)₃]⁻ (carb = carbazolide), both of which have been identified under coupling conditions, are key intermediates, and [Cu^II(carb)₃]⁻ serves as the persistent radical that is responsible for predominant cross-coupling. This study underscores the versatility of copper(II) complexes in engaging with radical intermediates that are generated by disparate pathways, en route to targeted bond constructions.

In Chapter 3, we establish that photoinduced, copper-catalyzed alkylation can also be applied to C−C bond formation, specifically, that the cyanation of unactivated secondary alkyl chlorides can be achieved at room temperature to afford nitriles, an important class of target molecules. In the presence of an inexpensive copper catalyst (CuI; no ligand coadditive) and a readily available light source (UVC compact fluorescent light bulb), a wide array of alkyl halides undergo cyanation in good yield. Our initial mechanistic studies are consistent with the hypothesis that an excited state of [Cu(CN)₂]⁻ may play a role, via single electron transfer, in this process. This investigation provides a rare example of a transition metal-catalyzed cyanation of an alkyl halide, as well as the first illustrations of photoinduced, copper-catalyzed alkylation with either a carbon nucleophile or a secondary alkyl chloride.

Chapter 4 presents a mechanistic study of the photocatalytic reduction of nitrite to nitrous oxide with the use of an Ir photocatalyst ([Ir(ppy)₂(phen)][PF₆]) and a bimetallic CoMg co-catalyst with a diimine-dioxime ligand platform. Insights into the mechanism of this reaction may enhance our current understanding of N–N coupling processes relative to other pathways of reactivity for nitrosyl ligands, such as nitroxyl (HNO) dimerization. We propose a mechanism in which a coordinated and an uncoordinated •NO are coupled at a single Co center. One electron reduction of [(Cl)(NO)Co(^Medoen)Mg(Me₃TACN)(H₂O)][BPh₄] ({CoNO}⁸), a species we show to be catalytically relevant, forms a {CoNO}⁹ species that is characterized by UV-Vis, EPR, and FT-IR spectroscopy and whose electronic structure is supported by density functional theory (DFT). We formulate the {CoNO}⁹ as a 5-coordinate, S = 3/2 Co(II) antiferromagnetically coupled with an anionic S = 1 ³NO^– ligand. Experimental data suggest a mechanism in which this {CoNO}⁹ intermediate can release •NO, thereby reducing the Co(II) center to Co(I). This free •NO can react with another {CoNO}⁹ complex to generate a Co(NONO) intermediate which was observed by step-scan time-resolved IR spectroscopy and whose assignment was supported with DFT calculations. This Co(NONO) species, which can generate N₂O and H₂O, is formulated as a neutral hyponitrite intermediate with significant neutral radical character on both nitrosyl nitrogen atoms and a weak N–N bond.

Yes
We report the synthesis of halido Os(II) p-cymene complexes bearing bidentate chelating phenylazobenzothiazole (AZBTZ) ligands. Unlike the analogous phenylazopyridine (AZPY) complexes, AZBTZ-NMe2 is capable of both N,N-coordination to Os(II) and cyclometalation to form N,C-coordinated species. N,C-Coordination occurs via an azo nitrogen and an ortho carbon on the aniline ring, as identified by 1H NMR and X-ray crystallography of [Os(p-cym)(N,N-AZBTZ-NMe2)Cl]PF6 (1a), [Os(p-cym)(N,N-AZBTZ-NMe2)Br]PF6 (2a), [Os(p-cym)(N,C-AZBTZ-NMe2)Br] (2b), and [Os(p-cym)(N,C-AZBTZ-NMe2)I] (3b). The N,C-coordinated species is more stable and is not readily converted to the N,N-coordinated complex. Analysis of the crystal structures suggests that their formation is influenced by steric interactions between the p-cym and AZBTZ-NMe2 ligands: in particular, larger monodentate halide ligands favor N,C-coordination. The complexes [Os(p-cym)(N,N-Me2-AZBTZ-NH2)Cl]PF6 (4) and [Os(p-cym)(N,N-Me2-AZBTZ-NH2)I]PF6 (5) were synthesized with methyl groups blocking the ortho positions on the aniline ring, forcing an N,N-coordination geometry. 1H NMR NOE experiments confirmed hindered rotation of the arene ligand and steric crowding around the metal center. Complex 2b exhibited unexpected behavior under acidic conditions, involving regiospecific deuteration of the aniline ring at the meta position, as observed by 1H NMR and high-resolution ESI-MS. Deuterium exchange occurs only under acidic conditions, suggesting an associative mechanism. The calculated partial charges on 2b show that the meta carbon is significantly more negatively charged, which may account for the regiospecificity of deuterium exchange.
ERC, EPSRC, The Royal Society

博士
國立高雄應用科技大學
化學工程與材料工程系博碩士班
105
TiO2 is a good photocatalyst and plays a role in the photodegradation of dyes in industrial wastewater. When TiO2 is doped with In2O3, a TiO2-In2O3 (Ti-In) composite material is formed, which can decrease the band gap in TiO2 and increase its photocatalytic activity. This study employed the sol-gel method to prepare Ti-In composite materials. Ti-In was then co-doped with carbon-nitrogen (C-N) and sulfur-nitrogen (S-N) to form new Ti-In-C-N and Ti-In-S-N composite catalysts, respectively, with the aim of increasing the photocatalytic efficiency of Ti-In. The precursors of TiO2 and In2O3 were titanium tetrachloride and indium chloride, respectively. The sources of the C, N, and S dopants were activated carbon powder, urea, and sodium thiosulfate, respectively. L-cysteine was used as a precursor for the modification of SN. The study employed a 2-step process to prepare the Ti-In-S-N composite catalysts. The first step was to prepare the Ti-In-S, before the Ti-In-S-N was synthesized with urea. During the preparation of the Ti-In-SN catalyst by doping L-cysteine, the Ti-In was modified to Ti-In-SN, in order to compare the photocatalytic activity of the two catalysts (Ti-In-S-N and Ti-In-SN). XRD analysis showed that the anatase crystalline phase ratios in Ti-In-SN, Ti-In-S-N, and Ti-In-C-N were 100 %, 64 %, and 63 %, respectively; they were all higher than Ti-In (30 %). The particle sizes of Ti-In-C-N, Ti-In-S-N, and Ti-In-SN were 33, 33, and 13 nm, respectively, all lower than Ti-In (57 nm). The band gap values of Ti-In, Ti-In-C-N, Ti-In-S-N, and Ti-In-SN were 2.97, 2.86, 2.82, and 2.75 eV, respectively, showing that co-doping Ti-In with C-N, S-N, and SN achieved the aim of decreasing the band gap of Ti-In. SEM images of Ti-In-C-N, Ti-In-S-N, and Ti-In-SN all showed a high tendency to agglomerate and all have a lamellar porous structure. TEM images showed that the particle dimensions of Ti-In-C-N, Ti-In-S-N, and Ti-In-SN were 25-50 nm, 20-50 nm, and 15-80 nm, respectively. The XPS analysis showed that Ti-In-C-N contains Ti-O-N, Ti-N-O, and Ti-O-C bonds; Ti-In-S-N contains Ti-O-N, Ti-N-O, and Ti-O-S bonds; and Ti-In-SN was verified to be formed Ti-N-O, Ti-O-N, and Ti-O-S bonds. A Brunauer-Emmett-Teller (BET) analysis was used to quantitate the specific surface areas of Ti-In, Ti-In-C-N, Ti-In-S-N, and Ti-In-SN. The resulting values were 35.7, 35.6, 42.3, and 48.6 m2/g, respectively. C.I. Reactive red 2 (RR2) was used as a target pollutant for photocatalysis reactions to compare the photocatalytic activity of various catalysts. A 254 nm UV lamp was used as a light source and the experiment was carried out at pH 3 and 25 °C. The photodegradation reactions of the prepared Ti-In, Ti-In-C-N, Ti-In-S-N, and Ti-In-SN composite catalysts were observed to obey pseudo-first-order kinetics, with rate constants of 0.43, 1.68, 1.70, and 0.68 h-1, respectively. The specific oxygen uptake rates of RR2 photodegradation were 4.4, 7.3, and 5.3 mg O2/g-MLVSS-h, respectively. The results showed that the photoactivity of the Ti-In-C-N, Ti-In-S-N, and Ti-In-SN composite catalysts, obtained from the co-doping of Ti-In, were all higher than Ti-In, and the toxicities of the treated effluent were all lower than Ti-In. Although the photocatalytic activity of Ti-In-S-N based on a two-step synthesis was higher than Ti-In-SN, the synthesis process was relatively time-consuming.

Theoretische Berechnungen sagen für tetragonal gedehntes Fe-Co eine hohe magnetokristalline Anisotropie voraus, wie sie für seltenerdfreie Dauermagnetwerkstoffe vorteilhaft wäre. In dieser experimentellen Arbeit werden epitaktische Fe-Co-Schichten strukturell und magnetisch charakterisiert. Zur Untersuchung der Dehnung in diesen Schichten eignen sich AuxCu100-x-Pufferschichten besonders, da über die Stöchiometrie (x) deren lateraler Gitterparameter eingestellt werden kann. Wird Fe-Co auf einer solchen Pufferschicht abgeschieden, erfolgt aufgrund dessen hoher elastischer Energie schon in den ersten Monolagen eine vollständige Relaxation der pufferinduzierten Dehnung. In ternären Fe-Co-X-Schichten, in denen kleine X-Atome (X = B, C oder N) Oktaederlücken besetzen, wird jedoch eine spontane tetragonale Dehnung c/a bis zu 1,05 beobachtet. Entlang der gedehnten c-Achse tritt eine uniaxiale magnetokristalline Anisotropie auf, die für B- oder C-Zulegierungen von 2 at% eine maximale Anisotropiekonstante von 0,4 MJ/m³ zeigt. Wird der X-Gehalt weiter erhöht, nehmen die Kristallinität der Schichten und die magnetische Anisotropie ab. Neben der magnetokristallinen Anisotropie des Schichtvolumens wird an den Fe-Co(-X)-Schichten eine hohe Grenzflächenanisotropie beobachtet. Der Beitrag der freien Oberfläche übersteigt den der Au-Cu-Grenzfläche dabei deutlich.
Theoretical calculations predict a high magnetocrystalline anisotropy for tetragonally strained Fe-Co, which would be beneficial for rare-earth free permanent magnet materials. In this experimental work, epitaxial Fe-Co films are investigated structurally and magnetically. AuxCu100-x buffer layers are very suitable to study the strain in these films since their in-plane lattice parameter can be tailored via the applied stoichiometry (x). However, when Fe-Co is deposited on such a buffer layer, the induced strain of the Fe-Co lattice relaxes completely within the first monolayers, due to its high elastic energy. In ternary Fe-Co-X films, where small atoms X like B, C or N occupy octahedral interstitial sites, a spontaneous strain c/a up to 1.05 is observed. A uniaxial magnetocrystalline anisotropy along the strained c axis appears. Their maximum anisotropy constant is 0.4 MJ/m³ for B or C contents of 2 at%. If the X content is further increased, the crystallinity and thus, the magnetic anisotropy of the films degrade. Together with the magnetocrystalline anisotropy of the films’ volumes, a high interface anisotropy is observed for the Fe-Co(-X) films. The contribution of the free surface clearly exceeds the contribution of the Au-Cu interface.

碩士
國立中山大學
材料與光電科學學系研究所
103
In the first part, predominant C-Si-H doped Co1-xO particulates/nanocondensates and minor turbostratic graphene, faceted graphite and Co(OH)2 tubes/belts, were formed by pulsed laser ablation (PLA) of Co plate in TEOS without appreciable transformation into Co3O4 which would otherwise be stable below ca. 900oC under open air condition. The C-Si-H doped Co1-xO particles are ~(100) and {111} faceted for (hkl)-specific coalescence and contain paracrystalline distribution of defect clusters with interspacing ca. 2.5 times that of the host lattice parameter as well as abundant planar defects, i.e. 1-D 3x and 5x{111} commensurate superstructures occasionally mixed with alternating Co close packed interlayer. UV-visible absorbance spectrum of the resultant colloidal suspension indicates the particles and nanocondensates have multiple absorptions in UV-visible range corresponding to a minimum band gap of 3.1 to 3.7 eV. In the second part, PLA of Co plate in aqueous solution of ammonium hydroxide (0.25 M NH4OH) caused the predominant formation of N-H-doped Co3-δO4 particulates and nanocondensates with paracrystalline distribution of defect clusters and larger lattice parameter than the ambient value of undoped bulk Co3-δO4, indicating that N enters the interstitial site in the spinel-type structure. The 3x3x3 spinel-type derived superstructure, due to tramp Co3+, N and H+ doping, along with Co3-δO4 and Co1-xO domains were also found in the rapidly solidified particulates. The co-existing Co layer-double hydroxide ribbons are optically birefringent and vulnerable to electron irradiation; whereas the hexagonal Co2O3 and triclinic cobalt nitrate were not favored by the present PLA process in aqueous ammonia. The N-H doped cobalt oxide particulates/nanocondensates showed characteristic bonding states of the constituent elements in the XPS as well as a significant violet absorbance corresponding to a minimum band gap of 2.9 eV for potential optocatalytic applications.