Preocupações com o acúmulo de lixo plástico e seu consequente impacto ambiental levaram os cientistas e a indústria química, nas últimas décadas, a uma busca por plásticos biodegradáveis e plásticos produzidos com matérias-primas de fontes renováveis. Entre eles, encontram-se o poli(ácido lático), o poli(?-caprolactona), os poli(hidroxialcanoatos), os polímeros de amido e os polímeros sintéticos que recebem aditivos que facilitam a degradação, conhecidos como oxi-biodegradáveis. Em decorrência dos processos de produção e uso de aditivos e corantes, os plásticos podem conter constituintes que não fazem parte das moléculas do polímero. Por esta razão, o objetivo do trabalho foi determinar os elementos químicos presentes em amostras de polímeros biodegradáveis, sacolas oxi-biodegradáveis e sacolas de amido distribuídas em supermercados, empregando-se análise por ativação neutrônica instrumental (INAA) e espectroscopia de fluorescência de raios X (XRF). A identificação dos polímeros das sacolas de supermercado foi realizada por espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR). Os resultados das análises químicas dos polímeros não processados evidenciaram baixas concentrações dos elementos químicos. Já os plásticos das sacolas apresentaram altas concentrações de cálcio, sódio, zinco e titânio, provenientes do uso de cargas minerais, corantes e outros aditivos. Em algumas amostras, as concentrações de zinco, cobalto, cromo, molibdênio e chumbo excederam os limites estabelecidos pela norma ABNT NBR 15448-2:2008 para polímeros biodegradáveis. As análises também indicaram que os aditivos pró-oxidantes utilizados nas sacolas oxi-biodegradáveis são baseados em compostos químicos que contêm ferro. Os resultados obtidos comprovam que os plásticos biodegradáveis podem ser utilizados de forma segura em embalagens e outras aplicações, desde que se evitem os aditivos contendo elementos químicos tóxicos e outras substâncias perigosas / Concerns about the accumulation of plastic waste and its consequent environmental impact have led scientists and chemical industry, in recent decades, to search for biodegradable plastics and plastics made with renewable raw materials. Among them are included poly (lactic acid), polycaprolactone, polyhydroxyalkanoates, starch polymers and synthetic polymers having additives which facilitate degradation, known as oxo-biodegradable. Due to production processes and use of additives and dyes, plastics may contain small amounts of chemical elements that are not part of the polymer molecules. For this reason, the objective of this study was to determine chemical elements in samples of biodegradable polymers, oxy-biodegradable and starch bags distributed in supermarkets by instrumental neutron activation analysis (INAA) and X-ray fluorescence spectroscopy (XRF). The polymers of plastic bags were identified by Fourier transform infrared spectroscopy (FTIR). Results of chemical analysis of unprocessed polymers have shown low concentrations of chemical elements. On the other hand, plastic bags have high concentrations of calcium, sodium, zinc and titanium, from the use of mineral fillers, dyes and other additives. In some bag samples, the concentration of zinc, cobalt, chromium, molybdenum and lead exceeded the limits established by the ABNT NBR 15448-2:2008 for biodegradable polymers. The analysis also indicated that the pro-oxidant additives used in the oxy-biodegradable bags are based on chemical compounds that contain iron. These results demonstrate that biodegradable plastics can be safely used in packaging and other applications, provided additives containing toxic chemical elements and other hazardous substances are avoided

by Yee-Lok Wong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

8-oxo-7,8-dihydroguanine (8oxoG) is one of the most important base lesions formed during oxidative damage of DNA. The aim of the present research was to investigate the effects of DNA concentration, G content, and the nature of oxidizing species on the kinetics of 8oxoG in model DNA solutions by using HPLC. The experimentally obtained yields of 8oxoG were typically in the range of 2-2.5% of total concentration of guanine. The ratios of the rate constant of hole diffusion in DNA to the rate constant of conversion of the hole into 8oxoG (kd/kr) were calculated from the experimental data using the diffusion model of charge transfer in DNA to be in the range of 200-300, in agreement with previously reported kd/kr ratios in the duplex DNA oligonucleotides (GGA)n or (GGTT)n. Our current diffusion model cannot satisfactorily explain the absence of the G content dependence of the 8oxoG yields, which indicates that a more advanced model is required.

Highly reactive iron-oxo intermediates play important roles as active oxidants in enzymatic and synthetic catalytic oxidation. Many transition metal catalysts are designed for biomimetic studies of the predominant oxidation catalysts in Nature, namely cytochrome P450 enzymes. In this work, a series of iron(IV)-oxo porphyrins [FeIV(Por)O] and manganese(IV)-oxo porphyrins [MnIV(Por)O] have been successfully produced in two electron-deficient ligands by photochemical and chemical methods, and spectroscopically characterized by UV-vis, and 1H-NMR. With iodobenzene diacetate [PhI(OAc)2] as the oxygen source, iron(III) porphyrin and manganese(III) porphyrin complexes converted to the corresponding metal(IV)-oxo species as oxygen atom transfer (OAT) agents. In addition, a new photochemical method was developed to generate the same species by visible light irradiation of highly photo-labile porphyrin-iron(III) bromate or porphyrin-manganese(III) chlorate precursors. Furthermore, the kinetics of oxygen transfer atom reactions with alkene, active hydrocarbons and aryl sulfides by photo-generated and chemical-generated [FeIV(Por)O]were studied in CH3CN solutions. Apparent second-order rate constants determined under pseudo-first-order conditions for sulfide oxidation reactions are (9.8 ± 0.1) × 102 − (3.7 ± 0.3) × 101 M-1s-1, which are 3 to 4 orders of magnitude greater in comparison with those of alkene epoxidations and activated C-H bond oxidations by the same oxo species.

The aim of this research project was to study the possible synthesis of the morphine analog 3-oxo-5-phenylmorphan via the photochemical cyclization of the acyl azide of 1-phenylcyclohexaneacetic acid.

<p>Radiotherapy is one of the most common therapeutic methods for treatment of many types of cancer. Despite many decades of development and experience there is much to improve, both in efficacy of treatment and to decrease the incidences of adverse healthy tissue reactions. Around 20 % of the radiotherapy patients show a broad range in the severity of normal tissue reactions to radiotherapy, and dose limits are governed by severe reactions in the most radiosensitive patients (< 5 %). Identification of patients with low, moderate or high clinical radiosensitivity before commencing of radiotherapy would allow individual adaptation of the maximum dose with an overall increase in the cure rate. Characterization of factors that may modify the biological effects of ionizing radiation has been a subject of intense research efforts. Still, there is no assay currently available that can reliably predict the clinical radiosensitivity. The aim of this work has been to investigate the role of oxidative stress in individual radiosensitivity and evaluate novel markers of radiation response, which could be adapted for clinical use.</p><p>8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a general marker of oxidative stress, is one of the major products of interaction of ionizing radiation with DNA and the nucleotide pool of the cell. As 8-oxo-dG is highly mutagenic due to incorrect base pairing with deoxyadenosine, various repair mechanisms recognize and remove 8-oxo-dG. The repaired lesions are released from cells to the extracellular milieu (serum, urine and cell culture medium) where they can be detected as markers for free radical reactions with the nucleic acids.</p><p>Significant variations in background levels as well as in radiation induced levels of 8-oxo-dG in urine have been demonstrated in breast cancer patients (paper 1). Two major patterns were observed: high background and no therapy-related increase vs. low background and significant increase during radiotherapy for the radiosensitive and non radiosensitive patients respectively.</p><p>Studies in paper 2 indicated major contribution of the nucleotide pool to the extracellular 8-oxo-dG levels. The results also implicated induction of prolonged endogenous oxidative stress in the irradiated cells. RNA “knock-down” experiments on the nucleotide pool sanitization enzyme hMTH1 in paper 3 lend further experimental evidence to this assumption.</p><p>The applicability of 8-oxo-dG as a diagnostic marker of oxidative stress was demonstrated in paper 4. Studies on dialysis patients revealed a good correlation between inflammatory responses (known to be associated with persistent oxidative stress) and extracellular 8-oxo-dG.</p><p>In summary, our results confirm that extracellular 8-oxo-dG is a sensitive <i>in vivo</i> biomarker of oxidative stress, primarily formed by oxidative damage of dGTP in the nucleotide pool with a potential to become a clinical tool for prediction of individual responses to radiotherapy.</p>

Radiotherapy is one of the most common therapeutic methods for treatment of many types of cancer. Despite many decades of development and experience there is much to improve, both in efficacy of treatment and to decrease the incidences of adverse healthy tissue reactions. Around 20 % of the radiotherapy patients show a broad range in the severity of normal tissue reactions to radiotherapy, and dose limits are governed by severe reactions in the most radiosensitive patients (&lt; 5 %). Identification of patients with low, moderate or high clinical radiosensitivity before commencing of radiotherapy would allow individual adaptation of the maximum dose with an overall increase in the cure rate. Characterization of factors that may modify the biological effects of ionizing radiation has been a subject of intense research efforts. Still, there is no assay currently available that can reliably predict the clinical radiosensitivity. The aim of this work has been to investigate the role of oxidative stress in individual radiosensitivity and evaluate novel markers of radiation response, which could be adapted for clinical use. 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a general marker of oxidative stress, is one of the major products of interaction of ionizing radiation with DNA and the nucleotide pool of the cell. As 8-oxo-dG is highly mutagenic due to incorrect base pairing with deoxyadenosine, various repair mechanisms recognize and remove 8-oxo-dG. The repaired lesions are released from cells to the extracellular milieu (serum, urine and cell culture medium) where they can be detected as markers for free radical reactions with the nucleic acids. Significant variations in background levels as well as in radiation induced levels of 8-oxo-dG in urine have been demonstrated in breast cancer patients (paper 1). Two major patterns were observed: high background and no therapy-related increase vs. low background and significant increase during radiotherapy for the radiosensitive and non radiosensitive patients respectively. Studies in paper 2 indicated major contribution of the nucleotide pool to the extracellular 8-oxo-dG levels. The results also implicated induction of prolonged endogenous oxidative stress in the irradiated cells. RNA “knock-down” experiments on the nucleotide pool sanitization enzyme hMTH1 in paper 3 lend further experimental evidence to this assumption. The applicability of 8-oxo-dG as a diagnostic marker of oxidative stress was demonstrated in paper 4. Studies on dialysis patients revealed a good correlation between inflammatory responses (known to be associated with persistent oxidative stress) and extracellular 8-oxo-dG. In summary, our results confirm that extracellular 8-oxo-dG is a sensitive in vivo biomarker of oxidative stress, primarily formed by oxidative damage of dGTP in the nucleotide pool with a potential to become a clinical tool for prediction of individual responses to radiotherapy.

In der vorliegenden Arbeit wird die Synthese von Bismut- und Neodymsilanolaten beschrieben. Durch partielle Hydrolyse ausgewählter Bismutsilanolate konnten neue Bismut-oxo-cluster synthetisiert werden. Die Darstellung von heterometallischen Bismut-Neodym-oxo-clustern ausgehend von Bismut- und Neodymsilanolaten wurde untersucht, ergaben jedoch keine definierten Cluster. Das Thermolyseverhalten der Silanolate und Oxo-cluster wurde beschrieben und die erhaltenen Zersetzungsprodukte charakterisiert. Weiterhin wurden in dieser Arbeit Koordinationspolymere von Bismuthalogeniden mit Phosphonsäureestern synthetisiert. Die so erhaltenen ein- und zweidimensionalen Koordinationspolymere wurde in Hinsicht auf ihr Verhalten unter thermischer Belastung untersucht. Das Hauptaugenmerk der vorliegenden Arbeit lag auf der strukturellen Charakterisierung der synthetisierten Verbindungen insbesondere durch Einkristallröntgenstrukturanalysen. Weiter Methoden wie NMR-Spektroskopie in Lösung und im Festkörper, DTA-TG, IR-Spektroskopie, Pulverröntgendiffraktometrie und Elektronenmikroskopie wurden zur Charakterisierung zur Hilfe genommen. / The present thesis deals with the synthesis of bismuth- and neodym silanolates. The partial hydrolysis of selected bismuth silanolates gave a series of novel bismuth-oxo-clusters. The synthesis of heterometallic bismuth-neodymium-oxo-clusters starting from bismuth- and neodymium silanolates has been assayed but did not give defined clusters. In addition the behavior of the silanolates and oxo-clusters towards thermal decomposition has been studied and the decomposition products have been characterized. In the second part of this work the synthesis of coordination polymers starting from bismuth halides and phosphonic acid esters is presented. Several one- and two-dimensional coordination polymers have been synthesized, structurally characterized and analyzed with respect to their thermally induced decomposition. The main focus of this work was to characterize the novel compounds in particular by single crystal X-ray diffraction analysis. Aditionally, NMR spectroscopy in solution and the solid state, DTA-TG, IR spectroscopy, powder X-ray diffraction and SEM-EDX have been used for the characterization of the products.

A través del presente Plan de Negocio, queremos mostrar la Viabilidad técnica, económica y financiera para la producción y comercialización de bolsas oxo-degradables y bolsas de papel en el Perú. En la actualidad el incremento del uso de bolsas plásticas está presente en nuestra vida diaria más que ningún otro elemento. Cuando vamos a algún mall o supermercado y compramos cualquier artículo es casi seguro que nos proporcionará una bolsa plástica. El uso intensivo de los desechos plásticos como las bolsas de plástico convencionales está generando un problema bastante grave, ya que no son susceptibles de asimilarse de nuevo en la naturaleza, porque su material tarda aproximadamente unos 400 años en degradarse, convirtiéndose en el responsable de gran parte de la contaminación medioambiental y el calentamiento global. Buscado una solución a la problemática ambiental encontrada, nace un nuevo mercado cuya necesidad es utilizar un producto con las mismas características y propiedades de las bolsas de plástico convencionales, pero que no contamine, o por decirlo de otro modo, que sea un plástico totalmente degradable. Focalizado en este nuevo mercado se propone producir y comercializar bolsas oxo-degradables y bolsas de papel, con materiales que puedan descomponerse, pero que no pierdan sus propiedades como: flexibilidad, resistencia, transparencia, impermeabilidad y facilidad de impresión. Asimismo, para la producción de estos productos se utilizará plástico reciclado para la fabricación de bolsas oxo-degradables y bagazo de caña usado para la fabricación de bolsas de papel. Adicionalmente se tendrá un impacto positivo ya que se introducirá al mercado un producto alternativo y totalmente amigable en beneficio del desarrollo sostenible y medioambiente del país. Establecida la demanda y estrategia de mercado a seguir, se plantea la instauración y desarrollo de la empresa con el que se busca lograr el posicionamiento en el mercado, y a la vez cubrir los requerimientos y necesidades de los futuros clientes. Por último, creemos y pronosticamos que la rentabilidad del proyecto a futuro será acorde a lo planificado, determinando así la viabilidad del proyecto de creación de la empresa denominada Biobags S.A.C. / Trabajo de investigación

Thorium(IV) and uranium(IV) coordination complexes have been studied for the last 60 years. They have shown interesting reactivity that is often divergent from that of transition metal complexes, and that also provides an insight into some unanticipated differences between thorium(IV) and uranium(IV). An introduction to thorium(IV) and uranium(IV) organometallic chemistry supported by carbocyclic and N-donor ligands is given in Chapter One. The reactivity of actinide alkyl, amide and alkynyl complexes towards small molecules is discussed and select examples provided. The redox chemistry of thorium and uranium is also introduced. Chapter Two describes the alkylation and amination chemistry of uranium(IV) and thorium(IV) trans-calix[2]benzene[2]pyrrolide ((L)2-) complexes, [(L)AnCl2], yielding new actinide(IV) complexes of the type [M(L-2H)An(R)] (M = Li or K, R = Me, CH2SiMe3, CH2Ph, N(SiMe3)2), where (L)2- undergoes further deprotonation to (L-2H)4-. Additionally, the lability of the [M(L-2H)An(R)] “ate”-complexes towards M+ ion exchange is addressed. Further, the selective ligand reprotonation of (L-2H)4- to (L)2- using HSiR'3 (R' = Me, iPr) and [Et3NH][BPh4] yielding [(L)An(C≡CSiR'3)2] and [(L)An(R)][BPh4] respectively, is explained. The reactivity of these complexes towards amines, silanes, alkenes, tin hydrides, silicone grease, tBuNC, H2, CO, CO2 or CS2 is described. Crystallographic characterisation shows that [(L)Th(N(SiMe3)2)][BPh4] contains an unusual example of a thorium(IV) bis-arene coordination mode. The reactivity of [(L)Th(C≡CSiMe3)2] towards a number of substrates including alkenes, [Ni(COD)2], [Pt(norbornene)3], P4, CO2 or H2 is also discussed. Activation of CO2 by [(L)Th(C≡CSiMe3)2] at 80 °C results in (L)2- functionalisation and abstraction to yield a new tricyclic organic molecule with the general formula LCO. The addition of [Ni(COD)2] to [(L)Th(C≡CSiMe3)2] and PR''3 (R'' = phenyl, cyclohexyl) yields heterobimetallic complexes [(L)Th(C≡CSiMe3)2·Ni(PR''3)]; these products display both dipyrrolic and bis-arene coordination. The changes in ligand coordination mode are discussed alongside DFT computational analyses that have been carried out by collaborators. The substitution reactions of [(L)AnCl2] with NaBH4 to form actinide(IV) borohydride complexes [(L)An(BH4)2] and subsequent attempted abstractions of BH3 from [(L)Th(BH4)2] are presented. Conclusions are provided at the end of the chapter. Chapter Three focusses on the oxidation chemistry of uranium(IV) within the (L)2- and (L-2H)4- ligand framework, prompted by the isolation of a uranium(V) complex [Li[(L)UO2]·LiI] from the oxidation of the uranium(IV) complex [Li(L-2H)U(Me)]. Conclusions are provided at the end of the chapter. Experimental methods and characterising data are given in Chapter Four.