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Brammer, Jeffrey M. "Organellar DNA Polymerases Gamma I and II in Arabidopsis thaliana." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2534.
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Plants have two organelles outside the nucleus which carry their own DNA, mitochondria and chloroplasts. These organelles are descendants of bacteria that were engulfed by their host according to the endosymbiotic theory. Over time, DNA has been exchanged between these organelles and the nucleus. Two polymerases, DNA Polymerases Gamma I and II, are encoded in the nucleus and remain under nuclear control, but are transported into the mitochondria and chloroplasts. DNA polymerases gamma I and II are two organelle polymerases which have been studied through sequence analysis and shown to localize to both mitochondria and chloroplasts. Little has been done to characterize the activities of these polymerases. Work in tobacco showed the homology of these polymerases to each other and to DNA Polymerase I in bacteria. They have been characterized as being part of the DNA Polymerase A family of polymerases. In my research I have studied the effect of T-DNA insertions within the DNA Polymerase Gamma I and II genes. Since these DNA Polymerases are targeted to the mitochondria and chloroplasts, I studied the effect of knocking out these genes. A plant heterozygous for an insert in DNA Polymerase Gamma I grows slightly slower than wild type plants with an approximately 20% reduction in mitochondrial and chloroplast DNA copy number. A plant homozygous for an insert in this same gene has a drastic phenotype with stunted plants that grow to around 1 inch tall, with floral stems, and have an approximately 50-55% reduction in mitochondrial and chloroplast DNA copy number. Wild type plants can grow to a height of 12-18 inches with floral stems as a comparison. A plant heterozygous for an insert in the DNA Polymerase Gamma II gene grows slightly slower than wild type plants and has an approximately 15% reduction in mitochondrial DNA copy number and a 50% reduction in chloroplast DNA copy number. These plants also produce much less seed than do other mutants and wild type plants.
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Bakthavatchalu, Vasudevan. "MnSOD AND AUTOPHAGY IN PREVENTION OF OXIDATIVE MITOCHONDRIAL INJURIES INDUCED BY UVB IN MURINE SKIN." UKnowledge, 2012. http://uknowledge.uky.edu/toxicology_etds/2.
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UVB radiation is a known environmental carcinogen that causes DNA damage and increase ROS generation in mitochondria. Accumulating evidence suggests that mtDNA damage and increased ROS generation trigger mitochondrial translocation of p53. Within mitochondria, p53 interacts with nucleoid macromolecular complexes such as mitochondrial antioxidant MnSOD, mitochondrial DNA polymerase Polγ, and mtDNA. Mitochondria are considered to be a potential source for damage-associated molecular patterns (DAMPs) such as mtDNA, cytochrome C, ATP, and formyl peptides. Intracytoplasmic release of DAMPs can trigger inflammasome formation and programmed cell death processes. Autophagic clearance of mitochondria with compromised integrity can inhibit inflammatory and cell death processes.
In this study we investigated whether and how MnSOD plays a protective role in UVB-induced mitochondrial damage. The possibility of MnSOD participating in the mtDNA repair process was addressed in vivo using transgenic and pharmacological approaches. The results demonstrate that MnSOD functions as a fidelity protein that maintains the activity of Polγ by preventing UVB-induced nitration and inactivation of Polγ and that MnSOD coordinates with p53 to prevent mtDNA damage.
We also investigated whether autophagy is an adaptive response mechanism by which skin cells respond to mitochondrial injury, using mouse keratinocytes (JB6 cells) and C57/BL6 mice as in vitro and in vivo models. The results demonstrate that UVB induces autophagy initiation in murine skin tissues and that down regulation of AKTmTOR levels triggers initiation of autophagy processes. These results suggest that autophagy may play a role in scavenging damaged mitochondria.
Taken together, the results from these studies suggest that MnSOD plays a protective role against UVB-induced mitochondria injury beyond its known antioxidant function. Within the mitochondrial matrix, MnSOD acts as an antioxidant and fidelity protein by prevention of UVB-induced nitration of Polγ. The functions of MnSOD may be to enhance mitochondrial membrane integrity and to prevent the genesis of oxidatively damaged mitochondrial components and subsequent intracytoplasmic spillage. Activation of autophagy serves as an additional response that scavenges damaged mitochondria.
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Hill, Donna. "Isolation & Characterization of DNA Polymerase Alpha and Gamma from Turnips (Brassica rapa) and Etiolated Soybeans (Glycine max)." TopSCHOLAR®, 1988. https://digitalcommons.wku.edu/theses/2483.
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DNA polymerase alpha, the enzyme involved in nuclear DMA replication, and DNA polymerase gamma, the enzyme involved in organellular DNA replication, were isolated and purified from soybean and turnip. The enzymes were characterized following ammonium sulfate precipitation, DEAF-cellulcse, phosphocelluloca, and hydroxylapatite chromatography, and by non-denaturing polyacrylamide gel electrophoresis. Protein banct were electropluted and the enzymes characterized using kinetic studies and sensitivity to divalent cations and inhibitors. Molecular weight and subunit composition studies indicated a molecular weight for the catalytic subunit of DNA polymerase alpha in soybean and turnip to be 46kDa. DNA polymeraqe gamma was composed of a catalytic subunit with a molecular weight of 66kDa. Although the two enzymes appear to share common subunits, characterization of their genetic origin remains to be determined before alpha and gamma can be classified as isoenzymes.
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Cupp, John D. "Characterization of the Cellular and Organellar Dynamics that Occur with a Partial Depletion of Mitochondrial DNA when Arabidopsis Organellar DNA Polymerase IB is Mutated." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3747.
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Plant mitochondrial genomes are large and complex, and the mechanisms for maintaining mitochondrial DNA (mtDNA) remain unclear. Arabidopsis thaliana has two DNA polymerase genes, polIA and polIB, that have been shown to be dual localized to mitochondria and chloroplasts but are unequally expressed within primary plant tissues involved in cell division or cell expansion. PolIB expression is observed at higher levels in both shoot and root apexes, suggesting a possible role in organelle DNA replication in rapidly dividing or expanding cells. It is proposed that both polIA and polIB are required for mtDNA replication under wild type conditions. An Arabidopsis T-DNA polIB mutant has a 30% reduction in mtDNA levels but also a 70% induction in polIA gene expression. The polIB mutant shows an increase relative to wild type plants in the number of mitochondria that are significantly smaller in relative size, observed within hypocotyl epidermis cells that have a reduced rate of cell expansion. These mutants exhibit a significant increase in gene expression for components of mitorespiration and photosynthesis, and there is evidence for an increase in both light to dark (transitional) and light respiration levels. There is not a significant difference in dark adjusted total respiration between mutant and wild type plants. Chloroplast numbers are not significantly different in isolated mesophyll protoplasts, but mesophyll cells from the mutant are significantly smaller than wild type. PolIB mutants exhibit a three-day delay in chloroplast development but after 7dpi (days post-imbibition) there is no difference in relative plastid DNA levels between the mutant and wild type. Overall, the polIB mutant exhibits an adjustment in cell homeostasis, which enables the maintenance of functional mitochondria but at the cost of normal cell expansion rates.
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Kampira, Elizabeth. "Pharmacogenetics of stavundine : role of genetic variation in mitochondrial DNA and polymerase gamma among adult Malawian HIV/AIDS patients." Doctoral thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/3168.
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Includes abstract.Includes bibliographical references.
Infectious diseases are endemic in Africa, especially tuberculosis (TB), malaria and human immunodefiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). Genomics research has the potential to improve the health of Africans through identification of genetic markers associated with either disease susceptibility or therapeutic drug response. This project was set to investigate the genetic correlates for drugs associated with mitochondrial toxicity that are used as part of HIV therapy, especially nucleoside reverse transcriptase inhibitors (NRTIs). Toxicity from NRTIs manifests through metabolic diseases such as peripheral neuropathy, lipodystrophy, lactic acidosis and hyperlactatemia but show interpatient variability. Studying African populations is likely to open the door for the population to benefit from novel diagnostic tools and drugs developed on the basis of pharmacogenomics knowledge. In an effort to contribute to this knowledge, the role of variation in mitochondrial DNA (mtDNA) and polymerase gamma (POL-γ) on how patients respond to stavudine-containing antiretroviral therapy (ART) among adult Malawian HIV/AIDS patients was investigated.
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AQUINO, SIMONE. "Efeitos da radiacao gama no crescimento de Aspergillus flavus produtor de aflatoxinas e no emprego da tecnica da Reacao em Cadeia da Polimerase (PCR) em amostras de graos de milho inoculadas artificialmente." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11253.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Aquino, Simone. "Efeitos da radiação gama no crescimento de aspergillus flavus produtor de aflatoxinas e no emprego da técnica da reação em cadeia da polimerase (PCR) em amostras de grãos de milho inoculadas artificialmente." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-16042012-105910/.
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O presente trabalho teve como objetivos verificar os efeitos da radiação gama em grãos de milho contaminados artificialmente com Aspergillus flavus Link produtor de aflatoxinas; demonstrar a aplicação da técnica da Reação em Cadeia da Polimerase (PCR) no diagnóstico de A. flavus, bem como verificar o efeito da radiação no perfil das bandas de DNA. Vinte amostras de grãos de milho com 200 g cada foram irradiadas individualmente com 20 kGy, para eliminar a contaminação microbiana. Em seguida, as amostras foram inoculadas com A. flavus toxigênico (1 x 106 esporos / ml), incubadas por 15 dias a 25 °C em ambiente com umidade relativa ao redor de 97,5% e irradiadas com 0; 2; 5 e 10 kGy. As amostras, 5 para cada dose de irradiação, foram analisadas individualmente quanto ao número de células fúngicas, atividade de água, teste de viabilidade (diacetato de fluoresceína e brometo de etídio), PCR e detecção de aflatoxinas (AFB). Os resultados demonstraram que as doses utilizadas foram efetivas na redução do número de Unidades Formadoras de Colônias (UFC/g), principalmente as doses de 5 e 10 kGy. Em adição, o teste de viabilidade mostrou uma diminuição de células viáveis com o aumento das doses de irradiação. A redução de AFB1 e AFB2 foi mais eficiente com o emprego de 2 kGy, comparativamente à dose de 5 kGy, enquanto a dose de 10 kGy degradou totalmente as aflatoxinas. Além disso, observou-se que AFB2 apresentou-se mais radiosensível. O emprego da técnica de PCR revelou a presença de bandas de DNA em todas as amostras.The aim of this present study was to verify the effects of gamma radiation on the growth of Aspergillus flavus Link aflatoxins producer; to demonstrate the application of Polymerase Chain Reaction (PCR) technique in the diagnostic of A. Flavus, as well to verify the effect of radiation in the profile of DNA bands. Twenty samples of grains maize with 200 g each were individually irradiated with 20 kGy, to eliminate the microbial contamination. In following, the samples were inoculated with an toxigenic A. flavus (1x106 spores/ml), incubated for 15 days at 25 °C with a relative humidity of around 97,5% and irradiated with 0; 2; 5 and 10 kGy. The samples, 5 to each dose of irradiation, were individually analyzed for the number of fungal cells, water activity, viability test (fluorescein diacetate and ethidium bromide), PCR and aflatoxins (AFB) detection. The results showed that the doses used were effectives in reducing the number of Colony Forming Units (CFU/g) mainly the doses of 5 and 10 kGy. In addition, the viability test showed a decrease of viable cells with increase of irradiation doses. The reduction of AFB1 and AFB2, was more efficient with the use of 2 kGy in comparison with the dose of 5 kGy, while the dose of 10 kGy, degraded the aflatoxins. Thereby, it was observed that AFB2 showed to be more radiosensitive. The use of PCR technique showed the presence of DNA bands, in all samples
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Meissner-Roloff, Madelein. "The occurrence of mitochondrial DNA polymerase gamma gene mutations in mitochondrial deficiencies, in a selection of South African paediatric patients / Madelein Meissner-Roloff." Thesis, North-West University, 2009. http://hdl.handle.net/10394/5095.
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Mitochondria are the "power houses" of each cell, sustaining the cell's energy demands by providing energy in the form of adenosine triphosphate (ATP). ATP is produced inside the mitochondria during cellular oxidative phosphorylation (OXPHOS). During this process, numerous reducing agents work together to finally produce ATP by the last enzyme of the OXPHOS system. Oxygen acts as the final electron acceptor in the electron transport chain (ETC), which is composed by the first four enzymes of the OXPHOS system.
The OXPHOS system is an electrochemical pump situated in the mitochondrial inner membrane. It contains subunits that are encoded by nuclear and mitochondrial DNA respectively. Mitochondrial DNA (mtDNA) encodes 13 peptides (part of the OXPHOS system), 22 transfer RNAs and 2 ribosomal RNAs. Disorders of this system can arise from mutations in either mitochondrial or nuclear DNA and are responsible for the most prevalent inborn (inherited) errors of metabolism in children. Various disorders with ranging severity have been linked to mitochondrial disorders that affect the energy production of the cell. This is especially evident when mutations in mtDNA occur. Therefore, the integrity of mtDNA is of utmost importance to primarily ensure the sufficient production of ATP within each cell.
Mitochondrial DNA polymerase gamma (mtDNA POLG or POLG) is the only nuclear encoded DNA polymerase involved in the replication of mtDNA. It has recently been shown that there is a high probability of POLG1 gene mutations (~25%) in mitochondrial disorders.
Very little is known about the aetiology of mitochondrial disorders in the South African population. This study is part of a collaborative study initiated in order to investigate the aetiology of mitochondrial disorders in South African paediatric patients. Patients were previously diagnosed on clinical presentation and/or biochemical enzyme analysis only, without the support of genetic testing. This study was undertaken to elucidate the role of possible mutations in the mtDNA POLG1 gene in a clinically selected paediatric target patient group (TPG). The clinical selection of eight patients from a group of 38 paediatric patients was mainly based on the occurrences of impaired eye function which has previously been associated with possible POLG malfunctioning. The aim of this study was to determine the POLG1 genetic sequence in the selected target patient group and to determine the relative mitochondrial copy number (RMCN) of the entire group of 38 patients.
Results obtained from RMCN analysis of the larger paediatric patient group, suggests that the clinical selection of patients for possible POLG mutations is inadequate. No pathogenic mutations, insertions or deletions were found in the selected TPG, but eight known intronic single nudeotide polymorphisms (SNPs), which include two insertion-deletions, were detected.
No mutations were found in the POLG gene of patients that, based on their clinical profiles, were suspected to have POLG malfunctioning. However, the number of patients investigated in this study was small and therefore these results are not representative of all South African patients. It is therefore suggested that all the South African patients with confirmed mitochondrial disorders should be sequenced for possible POLG gene mutations, before any final conclusions can be drawn.Thesis (M.Sc. (Biochemistry))--North-West University, Potchefstroom Campus, 2009.
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Xia, Yang. "The localisation and regulation of phosphatidylinositol-4-phosphate 5-Kinase gamma splice variants and the discovery of a new mammalian splice variant, PIP5KIγ_v6." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/240633.
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Type I PIP kinases (phosphatidylinositol 4-phosphate 5-kinases, PIP5Ks) catalyse the majority of cellular synthesis of PI(4,5)P2. To date, three mammalian isoforms (r1, r2, r3) have been found. PIP5KIr is subject to complex C-terminal splice variation, enhancing its transcriptional diversity through evolution and producing at least 5 known spliceoforms in the mammals. This study addresses several important questions. (1) Several remarkable differences have been discovered between the neuronal splice variant PIP5KIr_i3 and its close variant, Ir_i2, whose peptide lacks a 26-AA insert near its C-terminus. This study attempts to map these behavioural differences onto motifs within the peptide insert. Furthermore, a site of point mutation is identified near the activation loop, which amplifies the above differences. (2) This study documents properties of the more recently discovered PIP5KIr_i3, about which relatively little is known, for example, the regulation of its subcellular localisation, kinase activity and post-translational modifications. By site-directed mutagenesis and examining more closely several crucial motifs, insight is gained into the putative relationship between the enzyme’s phosphorylation state, cellular localisation, lipid kinase activity and autophosphorylation. (3) The discovery of a new PIP5KIr splice variant, Ir_v6, is described. First discovered in rodents, PIP5KIr_i6 encompasses the 26-AA insert of Ir_i3, but lacks the common C-terminus of Ir_i2 and Ir_i3 which contains peptide motifs that have several roles in vivo. A polyclonal antibody against the C-terminus of Ir_i6 was also developed. Preliminary characterisation of Ir_i6 demonstrates a similar subcellular localisation, but a wider expression profile than its close relative, Ir_i3, suggesting potentially differential functions across tissues and at various developmental stages. (4) The existence of Ir_v3 and Ir_v6 is also confirmed in humans. In light of recent findings of other novel human spliceoforms, this is shown to be a case of intra-exonic splicing producing “alternative 5’ splice site” exons in the human. Overall, this thesis should help to better understand the regulation and physiological roles of PIP5KIr and, specifically, its different splice variants.
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Chehtane, Mounir. "REAL TIME REVERSE TRANSCRIPTION-POLYMERASE CHAIN REACTION FOR DIRECT DETECTION OF VIABLE MYCOBACTERIUM AVIUM SUBSPECIES PARATUBERCULOSIS IN CROHN S DISEASE PATIENTS and ASSOCIATION OF MAP INFECTION WITH DOWNREGUALTION IN INTERFERON-GAMMA RECEPTOR (INFG." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4281.
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Association of Mycobacterium avium subspecies paratuberculosis (MAP) with Crohn's disease (CD) and not with ulcerative colitis (UC), two forms of inflammatory bowel disease (IBD), has been vigorously debated in recent years. This theory has been strengthened by recent culture of MAP from breast milk, intestinal tissue and Blood from patients with active Crohn's disease. Culture of MAP from clinical samples remained challenging due to the fastidious nature of MAP including its lack of cell wall in infected patients. The advent of real time PCR has proven to be significant in infectious disease diagnostics. In this study, real time reverse transcriptase PCR (RT-PCR) assay based on targeting mRNA of the IS900 gene unique to MAP has been developed. All variables included in RNA isolation, cDNA synthesis and real time PCR amplification have been optimized. Oligonucleotide primers were designed to amplify 165 bp specific to MAP and the assay demonstrated sensitivity of 4 genomes per sample. In hope this real time RT-PCR may aid in the detection of viable MAP cells in Crohn's disease patients, a total of 45 clinical samples were analyzed. Portion of each sample was also subjected to 12 weeks culture followed by standard nested PCR analysis. The samples consisted of 17 cultures (originated from 13 CD, 1 UC and 3 NIBD subjects), 24 buffy coat blood (originated from 7 CD, 2 UC, 11 NIBD and 4 healthy subjects) and 4 intestinal biopsies from 2 CD patients. Real time RT-PCR detected viable MAP in 11/17 (65%) of iii suspected cultures compared to 12/17 (70%) by nested PCR including 77% and 84% from CD samples by both methods, respectively. Real time RT-PCR detected MAP RNA directly from 3/7 (42%) CD, 2/2 (100%) UC and 0/4 healthy controls similar to results following long term culture incubation and nested PCR analysis. Interestingly, real time RT-PCR detected viable MAP in 2/11 (13%) compared to 4/11 (26%) by culture and nested PCR in NIBD patients. For tissue samples, real time RT-PCR detected viable MAP in one CD patient with the culture outcome remains pending. This study clearly indicates that a 12-hr real time RT-PCR assay provided data that are similar to those from 12 weeks culture and nested PCR analysis. Consequently, use of real time In our laboratory, we previously demonstrated a possible downregulation in the Interferon-gamma receptor gene (IFNGR1) in patients with active Crohn's disease using microarray chip analysis. In this study, measurement of RNA by real time qRT-PCR indicated a possible downregulation in 5/6 CD patients compared to 0/12 controls. The preliminary data suggest that downregulation in INFGR1 gene, and the detection of viable MAP in CD patients provides yet the strongest evidence toward the linkage between MAP and CD etiology.M.S.
Department of Molecular Biology and Microbiology
Burnett College of Biomedical Sciences
Molecular Biology and Microbiology
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Waters, R. D. "Effects of gamma radiation on biomedical polymers." Thesis, Liverpool John Moores University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378506.
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Cui, Zhenpeng. "Radiation Induced Synthesis of Conducting Polymers and their Metal Nanocomposites." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS165/document.
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L‘objectif du présent travail est de démontrer la versatilité de méthodologie radiolytique et de l‘étendre à la synthèse de différents PCs dans l‘eau. Le poly(3,4-ethylènedioxythiophène), PEDOT, et le polypyrrole, PPy, ont ainsi été préparés avec succès et caractérisés en solution aqueuse, ou après dépôt sur substrat, par des techniques spectroscopiques et microscopiques. La stabilité thermique et la conductivité électrique de ces matériaux radio synthétisés ont été étudiées et comparées aux propriétés des PCs produits par les méthodologies traditionnelles. Nous avons étudié l‘influence de la nature des espèces radiolytiques oxydantes, de la force ionique du milieu, du pH de la solution et de la présence de surfactants, sur le mécanisme de croissance des PCs, sur le rendement de polymérisation, sur la morphologie des matériaux radio synthétisés ainsi que sur les propriétés optiques et électriques de ces derniers. Nous avons utilisé la radiolyse pour la synthèse de nano composites hybrides à base de PCs et de métaux de transition. Plusieurs voies de synthèse ont été développées : synthèse en une ou deux étapes, par oxydation ou réduction des monomères. La nouvelle stratégie de synthèse par radiolyse, qui est décrite dans ce manuscrit, ouvre la voie à la préparation de très nombreuses familles de PCs et de leurs composites, que ce soit en solution aqueuse ou dans des environnements alternatifs (en milieu organique, sur support, en milieu hétérogène), ce qui laisse augurer de nombreuses applications fort prometteusesThe aim of the present work is to demonstrate the versatility of the gamma (γ)-rays based radiolytic method and to extend our methodology to the synthesis of various conducting polymers (CPs) in water in different experimental conditions. Poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) conjugated polymers were successfully prepared and characterized in solution and after deposition by complementary spectroscopic and microscopic techniques. Also their thermal stability and their electrical conductivity were studied and compared with those of CPs prepared by conventional methods. The influence of the nature of radiation-induced oxidizing radicals, of the ionic strength, of the medium, of the pH, of the presence of surfactant-based soft templates on the growth mechanism, on the efficiency of polymerization, on the morphology of the obtained CPs as well as on their absorption and conducting properties was checked. Also, the radiolytic method was extend to the synthesis of CPs/noble metal nanocomposites. Different preparation methodologies were developed based on two-step method and one-pot method, by using oxidation route or reduction route. Our new radiolytic strategy described and extended in this manuscript opens the way for the preparation of different kinds of CPs and CPs nanocomposites not only in aqueous solutions but also in various environments foreshadowing many promising applications
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Soane, Robert J. "Bioadhesive polymers as intranasal drug delivery systems for peptide and protein drugs." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298078.
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Ramos, Neto Antonio. "Estudo da degradação causada pela radiação gama em polímeros utilizados em serviços de radioterapia." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/747.
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Em serviços de radioterapia são utilizados acessórios confeccionados com diversos tipos de polímeros para auxiliar no posicionamento dos pacientes durante o tratamento e na execução das rotinas de trabalho. A radiação gama pode causar nos polímeros degradação de sua estrutura molecular que além de reduzir sua eficiência na assepsia e seu tempo de vida útil, pode também eliminar compostos orgânicos nocivos ao ambiente de trabalho. Neste trabalho é apresentado o estudo da degradação causada pela exposição à radiação gama em polímeros utilizados em serviços de radioterapia. Amostras de policarbonato (PC), polipropileno (PP), polimetilmetacrilato (PMMA) e compósito de poliuretana derivada de óleo de mamona com juta (PU-Juta), foram expostas a doses de radiação gama de 5 kGy (dose de algumas semanas de rotinas de radioterapia) a 25 kGy (dose de esterilização), sendo analisadas por espectrometria de absorção na região do infravermelho, indentação instrumentada, ângulo de contato e análise termogravimétrica. O PU-Juta mostrou-se o mais adequando para utilização, pois apresenta fragilização no material somente com doses acima de 20 kGy, por não perder sua característica hidrofílica permitindo assepsia de forma eficiente e por não possuir compostos orgânicos voláteis nocivos em sua composição. O PC apresentou indícios de fragilização a partir de 5 kGy, reduzindo drasticamente o tempo de vida útil e sendo o menos indicado em serviços onde haja exposição à radiação ionizante.Radiotherapy Services uses many different types of polymeric accessories to assist in the positioning of patients during treatment and work routines. Gamma radiation can cause material degradation and allow that harmful compounds are released into the air. Also can harm the efficiency of sterilization and reduce the accessories useful life. This paper presents the study of the degradation caused by exposure to gamma radiation in polymers used in radiotherapy services. Samples of polycarbonate (PC), polypropylene (PP), polymethylmethacrylate (PMMA) and a composite of polyurethane derived from castor oil with Jute (PU-Jute) were exposed to gamma radiation doses of 5 kGy (few weeks of routines radiotherapy) to 25 kGy (sterilization dose) and analyzed by infrared spectroscopy, instrumented indentation, contact angle and thermal analysis. The PU-Jute samples proved to be the most fitting for use in places with radiation exposure. The material embrittlement was detected above 20 kGy doses. Also does not change their hydrophilic characteristic allowing aseptic procedures efficiently and has no harmful volatile compounds in the composition. The PC samples showed signs of embrittlement with 5 kGy reducing drastically their lifetime. Therefore is not suited for radiotherapy services.
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Smith, Christine. "The effects of gamma-irradiation on additives in food-contact polymers." Thesis, Sheffield Hallam University, 1989. http://shura.shu.ac.uk/20370/.
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A range of antioxidants (BHT, Irganox 1010, 1076, 1330 and Irgafos 168) were incorporated into polymers (polyethylene, polypropylene, polystyrene and polyvinyl chloride) and subjected to increasing doses of gamma-irradiation (1,5,10,20,25,35 and 50 kGy) from a cobalt-60 source. The amount of extractable antioxidant from the stabilised polymers was determined chromatographically and a gradual diminution in the total extractable levels of each antioxidant was observed as irradiation progressed, the extent depending on the nature of both the antioxidant and the polymer 2,6-Di-t-butyl-1,4-benzoquinone was shown to be an extractable degradation product, arising from the effects of gamma-irradiation on the phenolic antioxidants. The extractable degradation product arising from the phosphite antioxidant, Irgafos 168, was identified as tris(2,4-di-t-butylphenyl)phosphate. It was demonstrated using 14C-labelled Irganox 1076 that degradation products formed during gamma-irradiation are becoming covalently bound to the polymer, as a result of radical coupling processes. There is a pronounced increase in the extent of covalent binding from 0.4% before irradiation to a minimum of 12.4% after an exposure to 50 kGy. Evidence has also been presented of covalent binding of the degradation product of Irgafos 168 to the polypropylene matrix, via polymeric radicals formed during irradiation. Finally, the effects of gamma-irradiation on the extent of migration of antioxidants from polyolefins into food simulants was studied. It was found that irradiation leads to a decrease in the extent to which hindered phenolic antioxidants migrate from polyolefins into fatty media, consistent with the reduction in extractable antioxidant levels and the increase in the extent of antioxidant-polymer binding.
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ALMEIDA, ARLETE T. "Obtencao de superficies hemocompativeis por meio da modificacao de materiais polimericos pela radiacao ionizante." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10834.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP
FAPESP:97/05333-3
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Kinalir, Kerim Gokhan. "A Study On The Effects Of Gamma Radiation On The Properties Of Polycarbonate." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613020/index.pdf.
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This thesis aims to investigate the effects of gamma radiation on the properties of polycarbonate, an engineering thermoplastic which has a wide range of applications. A commercial grade polycarbonate resin, after being shaped into the required specimen forms by injection molding, was irradiated with different doses up to 180 kGy. Tensile strength was found to decrease with increasing dose. The lowest values of tensile modulus, flexural modulus and flexural strength were obtained at 96 kGy, which is also the dose at which molecular weight values showed a minimum. No remarkable changes in Shore D hardness values and NMR spectra were observed. The ATR-FTIR spectra showed that irradiation was effective on carbonyl groups in the structure. The glass transition temperatures of the specimens irradiated up to the maximum dose were lower than those of the non-irradiated specimens. The onset of weight loss at lower temperatures and steeper weight loss behavior in the TGA curves indicated decreasing thermal stability of the polymer with increasing dose.
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PANZARINI, LUZ C. G. A. "Estudo da enxertia e heparinizacao simultaneas do poli(cloreto de vinila), via radiacao gama." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11217.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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ZULLI, GISLAINE. "Desenvolvimento de uma matríz polimérica para incorporação e liberação controlada de papaina." reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11500.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Adebayo, Olajumoke O. "Evaluation of bacterial polymers as protective agents for sensitive probiotic bacteria." Thesis, University of Wolverhampton, 2018. http://hdl.handle.net/2436/621096.
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Probiotics are live microorganisms which when administered in adequate amounts confer one or more health benefits on the host. Different processing conditions, the acidic condition of the stomach and exposure to hydrolytic enzymes affect the viability and efficacy of probiotic organisms. This study investigated the protective effects of two biopolymers poly-gamma-glutamic acid (γ-PGA) and bacterial cellulose (BC) on probiotics during freeze drying and during exposure to simulated intestinal juices and bile salts. The antibacterial property of Bifidobacterium strains was also investigated against four pathogenic bacteria. γ-PGA, a naturally occurring biopolymer was produced by two bacteria (Bacillus subtilis ATCC 15245 and B. licheniformis ATCC 9945a) in GS and E media, γ-PGA yields of about 14.11g/l were achieved in shake flasks and molecular weight of up to 1620 k Da was recorded, γ-PGA production was scaled up in a fermenter with B. subtilis using GS medium. BC, an edible biopolymer was produced by Gluconacetobacter xylinus ATCC 23770 in HS medium and a modified HS (MHS) medium. A yield of about 1.37g/l was recorded and BC production with MHS medium was used for probiotic application. B. longum NCIMB 8809 B. breve NCIMB 8807 and B. animalis NCIMB 702716 showed the best antimicrobial properties against the investigated pathogens. Survival of Bifidobacterium strains was improved when protected with powdered BC (PBC) although γ-PGA offered better protection than PBC. Viability of B. longum NCIMB 8809, B. breve NCIMB 8807 and B. animalis NCIMB 702716 in simulated gastric juice (SGJ) and simulated intestinal juice with bile salts was improved when protected with 5% γ-PGA and 5% γ-PGA+PBC with a reduction of < 1 Log CFU/ml while a reduction of ≤2 Log CFU/ml was recorded in PBC protected cells. Protecting Bifidobacterium strains with γ-PGA, PBC or a novel γ-PGA + PBC combination is a promising method to deliver probiotic bacteria to the target site in order to confer their health benefits on the host.
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Baratéla, Fernando José Costa. "Estudo das propriedades biocompatíveis de arcabouços poliméricos derivados de óleos vegetais para aplicação na engenharia de tecidos." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-18092015-150510/.
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A engenharia de tecidos e a medicina regenerativa possuem como objetivo principal o restabelecimento morfológico/funcional de tecidos e órgãos lesionados com a utilização de células, matrizes celulares e células tronco, controlando as respostas imunológicas/bioquímicas promovidas pelo organismo. Adicionalmente, a ciência dos materiais busca desenvolver biomateriais biocompatíveis que não promovam reações imunológicas indesejadas e proporcionem o reestabelecimento das funções do tecido/órgão. Polímeros de origem natural destacam-se como biomateriais por assemelharem-se a macromoléculas biológicas, similaridade com a matriz extracelular, menor possibilidade de estimulação de inflamação crônica e baixa ou ausência de toxicidade. O presente trabalho teve como objetivo desenvolver matrizes macromoleculares originadas do óleo de soja epoxidado (OSE), analisando a relação estrutura química/atividade biológica das matrizes macromoleculares para uso como biomaterial na engenharia de tecidos. A síntese do OSE foi efetuada pela rota oleoquímica, cuja eficiência foi determinada por espectroscopia de infravermelho e o rendimento da reação de 85% determinado por ressonância magnética nuclear de prótons. A partir da análise por calorimetria exploratória diferencial, detectou-se uma diminuição da temperatura de transição vítrea do polímero do óleo de soja (POSE) em relação ao OSE, sugerindo aumento do crescimento das cadeias poliméricas do POSE. Através da análise termogravimétrica, foi possível definir o perfil de degradação do OSE, com degradação em duas etapas, e do POSE, que degrada em apenas uma etapa e demonstra maior estabilidade térmica do POSE pelo aumento das interações moleculares. A reticulação e a hidrofilicidade do POSE foram promovidas com a adição de metacrilato de 2-hidroxietila (HEMA) à formulação por enxertia do monômero pela irradiação gama. Os resultados obtidos identificaram aumento da estabilidade mecânica, da gelificação e da absorção de água com o aumento do conteúdo de HEMA. Por fim, o grau de cristalinidade estimado para esses polímeros enxertados com HEMA de 27,5% foi definido através da difratometria de raios-X. A segunda etapa caracterizou-se pelo (i) desenvolvimento de POSEs com a enxertia de HEMA nas proporções OSE/HEMA 90:10 e 65:35 com irradiação por raios gama nas doses de 50 e 100kGy, (ii) caracterização físico-química dos POSE-HEMA e (iii) análise biológica desses materiais. Através da espectroscopia de infravermelho, pode-se detectar as regiões epoxidadas do POSE, assim como o sucesso da enxertia do monômero HEMA em todas as concentrações e doses de radiação utilizadas. Através da calorimetria exploratória diferencial, calculou-se a energia de ativação (Ea) dos polímeros. A cristalinidade dos materiais foi definida por difratometria de raios-X, mostrando caráter amorfo do material, bem como um pequeno incremento na porcentagem da cristalinidade com o aumento da intensidade das doses de radiação durante a síntese e um decréscimo dessa cristalinidade com o aumento na concentração de HEMA. A análise da citotoxicidade das amostras mostrou a ausência de toxicidade dos POSE-HEMA, confirmando a eficiência das lavagens dos polímeros para retirada de resíduos do processamento. A análise da hemocompatibilidade mostrou ausência de adesão de plaquetas e os testes de crescimento celular nas matrizes foram positivos. Através dos resultados obtidos nesta pesquisa, pôde-se concluir pelo potencial de utilização dos POSE-HEMA na engenharia de tecidos.Tissue engineering and regenerative medicine have as main objective the morphologic/functional reestablishment of injured tissues and organs using cells, scaffolds, stem cells and control of immunological/biochemical responses promoted by the body. In addition, materials science seeks to develop biocompatible biomaterials that do not promote unwanted immune responses and provide the re-establishment of the functions of the tissue/organ. Polymers of natural origin stand out as biomaterials to resemble biological macromolecules, similarity to the extracellular matrix, reduced chance of inflammation and chronic pacing low or no toxicity. This study aimed the development of macromolecular arrays originated from epoxidized soybean oil (OSE), analyzing the relationship between the chemical structure/biological activity of the macromolecular arrays for use as biomaterials in tissue engineering. The synthesis of OSE was performed through the oleochemical route, whose efficiency was determined by infrared spectroscopy and the reaction yield of 85%, determined by nuclear magnetic resonance spectroscopy. From the analysis by differential scanning calorimetry, it was detected a decrease of the glass transition temperature of the epoxidized soybean oil polymer (POSE) compared with OSE, suggesting an increase of the growth of polymer chains of POSE. Thermogravimetric analysis was performed to define the OSE degradation profile, which degrades in two steps. The POSE degrades in just one step and shows higher thermal stability by the increased molecular interactions. The hydrophilicity and crosslinking of POSE was promoted by the addition of 2-hydroxyethyl methacrylate (HEMA) with the monomer grafting by gamma irradiation. The results showed an increased mechanical stability, gelation and water absorption with the HEMA content increasing. Finally, the degree of crystallinity for such polymers grafted with HEMA was 27.5%, estimated by X-ray diffractometry. The second stage was characterized by (i) developing POSEs with the grafting of HEMA in the proportions OSE / HEMA 90:10 and 65:35 irradiated by gamma rays at doses of 50 and 100kGy, (ii) physico-chemical characterization of POSE-HEMA and (iii) analysis of biological materials. By infrared spectroscopy, it was detect the epoxidized regions of POSE, as well as the successful grafting of the monomer HEMA concentrations with all radiation doses. By differential scanning calorimetry, the activation energy was calculated (Ea) of the polymers. The crystallinity of the material was defined by X-ray diffraction, showing tendency of amorphous material as well as a small percentage of the increase in crystallinity with increasing intensity of radiation doses during this synthesis and a decrease in crystallinity with the increasing concentration of HEMA. The analysis of the samples did not show cytotoxicity on POSE-HEMA and confirmed the efficiency of polymer washings to remove the processing waste. The analysis of hemocompatibility showed any platelet adhesion and the cell growth on the scaffolds was positive. From the results obtained in this research, we concluded by the potential use of POSE-HEMA in tissue engineering.
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Heffner, Kenneth Henry. "Radiation Induced Degradation Pathways for Poly (Methyl Methacrylate) and Polystyrene Polymers as Models for Polymer Behavior in Space Environments." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000175.
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Hacioglu, Firat. "Degradation Of Epdm Via Gamma Irradiation And Possible Use Of Epdm In Radioactive Waste Management." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612391/index.pdf.
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In this study, degradation of ethylene propylene diene terpolymer (EPDM) via gamma radiation and possible use of EPDM in radioactive waste management were investigated. In estimation of radiation stability and possible use of EPDM in radioactive waste management, dose rate (both high and low), irradiation environment (in water and in air), additives (carbon black, zinc oxide, plasticizer) used in formulation, peroxide type (either aliphatic or aromatic) and content were parameters which were analyzed.
Three EPDM samples having different peroxides were irradiated in water and in air with two different dose rates (993 Gy/h, 54 Gy/h) to 2163 kGy (for high dose rate) and 1178 kGy (for low dose rate). Irradiation periods for low dose rate were 2.5 years (last sample) which have not been observed in literature. Characterization of irradiated EPDM samples were done by mechanical (tensile, hardness, compression), dynamic mechanical (DMA), thermal (TGA-FTIR) and morphological (ATR-FTIR, XRD, SEM) tests. High dose rate irradiations were done in predicting how far EPDM resist to radiation and which dose rate emitted waste can be immobilized and stored in EPDM for 300 years. Low dose rate irradiations were carried out in determining morphological changes in structure, thermal stability, oxygen effect and types of reactions (crosslinking, chain scisson) which were dominant in irradiated samples.
According to the test results, improvement in thermal properties and decrease in elasticity on EPDM via radiation were recorded from thermal and mechanical tests respectively. Moreover, structural changes were monitored from ATR-FTIR, SEM and XRD analysis. Mechanical tests showed that irradiated EPDM samples, which were differentiated with respect to peroxide type (aliphatic, aromatic), could resist up to total absorbed doses of 3750 kGy and 3955 kGy respectively. Up to 1178 kGy in low dose irradiation, there were not much structural changes, which were observed in ATR-FTIR analysis, in EPDM chain.
It was concluded that EPDM rubber used in this study were radiation stable polymer so that they could possibly be used in conditioning of radioactive waste.
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CREDE, RICARDO G. "Estudos dos efeitos da radiação gama e de aceleradores de elétrons na detecção de grãos de milho (Zea mays) geneticamente modificado." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11369.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
25
Vismara, Marcus Vinícius Gonçalves [UNESP]. "Estudo das propriedades dosimétricas de polímeros conjugados." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/99657.
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vismara_mvg_me_bauru.pdf: 1607998 bytes, checksum: 8efc51b01e3badc0e6233d3ef3f7d4ab (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Este trabalho teve como objetivo a investigação da interação de radiação gama com três polímeros: o polímero Poli(2-metóxi, 5-(2'-etil-hexilóx)-1,4- fenileno vinileno) (MEH-PPV)n e os polímeros solúveis em água Poly {[2,5-bis(2-(N,N-diethylamino)ethoxy) -1,4 -phenylene]-alt-1,4-phenylene} e o Poly [(2,5-bis (2 - (N,N - diethylammonium bromide) ethoxy) - 1,4 -phenylene) - alt - 1,4-phenylene]. O polímero MEH-PPV foi dissolvido nos solventes orgânicos clorofórmio e bromofórmio, já os outros dois polímeros, em água destilada e solução de HCI 1M. As amostras foram preparadas em várias concentrações e irradiadas com doses que variaram desde 0,01 Gy, sendo que cada amostra foi irradiada com apenas uma dose. Os resultados foram avaliados com técnicas espectroscópicas, sendo elas, espectroscopia de absorção óptica UV-visível e espectroscopia de fluorescência. Foi avaliada a alteração na posição do pico principal de absorção óptica com a dose absorvida pelas amostras. Como resultado principal, observou-se que os polímeros solúveis em água não apresentam alteração espectral após serem irradiados. Não sendo interessante para aplicação dosimétrica. Já para as amostras do polímero MEH-PPV diluídas em bromofórmio apresentaram alta sensibilidade para doses inferiores a 1 Gy, e apresentaram certa linearidade com a dose recebida (fator importante para aplicação dosimétrica). Para as amostras em clorofórmio, não foi observado deslocamento significativo do escpectro de absorção para doses inferiores a 1 Gy. No entanto para doses de 1 Gy à 90 Gy, o comportamento observado pode ser descrito por duas regiões lineares: uma com maior inclinação da reta para doses até cerca 30 Gy, e outro com inclinação da reta menor para doses entre 30 Gy e 90 Gy. O comportamento linear, assim como a inclinação da reta, do deslocamento da posição...
The subject of this work is the investigation of gamma radition interaction with tree polymers: the polymer Poli(2-metóxi, 5-(2'-etil-hexilóx)-1,4- fenileno vinileno) (MEH-PPV)n e os polímeros solúveis em água Poly {[2,5-bis(2-(N,N-diethylamino)ethoxy) -1,4 -phenylene]-alt-1,4-phenylene} e o Poly [(2,5-bis (2 - (N,N - diethylammonium bromide) ethoxy) - 1,4 -phenylene) - alt - 1,4-phenylene]. The MEH-PPV polymer was dissolved in organic solvents, choloroform and bromoform, the other two polymers in distilled water and 1 M aqueous HCI solution. The samples were prepared at various concentrations and irradiated with doses ranging from 0.01 Gy to 90 Gy. The results were evaluated by spectroscopic techniques, which were, UV-visible absorption spectroscopy and fluorescence spectroscopy. They were evaluated the changes in the position of main optical absorption peak with the dose absorbed by the samples. As main result, it was observed that water-soluble polymers did not show spectral change after being irradiated. For dosimetric application this results are not interesting. For the MEH-PPV polymer samples diluted in bromoform presented highly sensitive to doses below 1 Gy, and showed some linearity with the dose received. For samples in chloroform, doses below 1 Gy did not showed significant shift in the absorption spectra. However, the samples irradiated with doses from 1 Gy to 90 Gy, the behavior can be described by two linear regions: one with a higher slope for doses up to about 30 Gy, and another with a lower slope for doses between 30 Gy and 90 Gy. A greater slope to doses up to about 30 Gy, and another with lower slope to doses between 30 and 90 Gy. The linear behavior and the slope of the main peak position is a important factor for dosimetric application. At the same time, a study of stability of the samples was performed. It was observed that the MEH-PPV samples in bromoform... (Complete abstract click electronic access below)
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Gaston, Fanny. "Impact des rayonnements γ sur les films plastiques utilisés pour des applications biopharmaceutiques et biotechnologiques." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4704.
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Les systèmes plastiques à usage unique sont destinés aux industries biopharmaceutiques et biotechnologiques. Ils sont composés de polymères et sont appréciés pour leurs propriétés barrières au gaz et à la vapeur d’eau assurant une préservation des solutions contenues dans ces systèmes. Ces dispositifs présentent de nombreux avantages pour les industriels : ils permettent d’éviter un nettoyage des cuves en inox et ainsi de limiter des risques de contamination croisée. En vue de leur utilisation, ces dispositifs sont stérilisés par irradiation γ. Le but de cette étude est de mettre en évidence l'impact de la stérilisation γ sur certains polymères et sur certains antioxydants utilisés dans la fabrication des polymères. Plusieurs échantillons sont analysés avant et après la stérilisation en utilisant différentes doses de rayonnement γ et au cours du temps (vieillissements naturels). Les modifications de structure des polymères γ-irradiés (EVA, PE et EVOH) ont été caractérisées par diverses méthodes analytiques : IRTF, spectroscopie Raman, RPE, chromatographie… Les résultats sont traités en utilisant des méthodes chimiométriques, comme l’ACP (Analyse en Composantes Principales), l’AComDim (ANOVA Common Dimensions) et SIMPLISMA (Simple-to-use interactive self-modeling mixture analysis). L’ACP a permis de mettre en évidence l’impact de la dose d’irradiation sur le polymère. L’AComDim a conduit à identifier les facteurs responsables de l’évolution des structures (la dose γ, les temps et l’interaction dose γ × temps), alors que les différents lots n’induisent pas de déviation. Enfin, la méthode de résolution de courbe SIMPLISMA a été appliquée pour l’étude du cœur du matériauThe single use plastic systems are designed for biopharmaceutical and biotechnology industries. They are principally made of polymers and they are very appreciated for their barrier properties to gas and water vapor ensuring preservation of the solutions contained in these single-use systems. These devices have many advantages for industrial: they avoid cleaning stainless steel tanks and thus limit the risk of cross-contamination. In view of their future use, these devices are sterilized by γ-irradiation. The purpose of this study is to highlight the impact of γ sterilization on some polymers and on some antioxidants used in the manufacture of polymers. The samples are analyzed before and after sterilization using different γ-doses and over time (natural ageing). The structural modifications of γ-irradiated polymers (EVA, EVOH and PE) were characterized by various analytical methods: FTIR, Raman spectroscopy, ESR, chromatography… Some results are analyzed using chemometric methods such as PCA (Principal Component Analysis), AComDim (ANOVA Common Dimensions), and SIMPLISMA (Simple-to-use interactive self-modeling mixture analysis). The PCA allowed to highlight the impact of the irradiation dose on the polymer. The AComDim method led to the identification of the factors contributing to the evolution of structures (γ-dose, ageing and γ × ageing interaction), whereas the several lots do not involve variation. Finally, the curve resolution method, SIMPLISMA, was applied to the study of the core of the material
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Kamenopoulou, Vassiliki. "Proprietes dosimetriques des fibres textiles : application a la dosimetrie par resonance paramagnetique electronique d'un accident d'irradiation gamma." Toulouse 3, 1987. http://www.theses.fr/1987TOU30172.
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Hérodin, Francis. "Contribution a l'etude des effets d'une reaction inflammatoire et d'une irradiation gamma ou neutron-gamma globale chez la souris." Paris 6, 1988. http://www.theses.fr/1988PA066295.
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Un modele de granulome inflammatoire induit chez la souris par injection souscutanee de microbilles de polyacrylamide est utilise pour etudier la physiopathologie de souris soumises, avant ou apres l'induction du processus inflammatoire local, a une exposition globale a des radiations ionisantes. L'effet suppresseur des radiations ionisantes. Une reaction inflammatoire locale induite depuis 24 h s'accompagne d'un effet radioprotecteur important, qui pourrait etre partiellement explique par une stimulation notable de la myelopoiese
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CARDOSO, ELISABETH C. L. "Desenvolvimento de espumas parcialmente biodegradáveis a partir de blendas de PP/HMSPP com polímeros naturais e sintéticos." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10635.
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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LUGAO, ADEMAR B. "Estudos da sintese por irradiacao, da estrutura e do mecanismo de formacao de polipropileno com alta resistencia do fundido." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11212.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
31
Altinsoy, Sule. "Polymerization And Characterization Of N-vinyl-2-pyrrolidone." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611238/index.pdf.
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N-vinyl-2-pyrrolidone, NVP, was polymerized by �
&
#56394
-radiation in the presence of atmospheric oxygen and under vacuum at different periods. Polymerization also conducted by using chemical initiator, &
#56256
&
#56466
-Azoisobutyronitrile, AIBN, in bulk at different temperatures and times. The activation energy for polymerization was found from Arrhenius plot as 31,8 kJ/mol. By using the Fox-Flory equation T&
#56256
&
#56394
and k values calculated for each polymerization methods. The polymer obtained was white gel type. The different types of polymer obtained were investigated by FT-IR, 1H-NMR and 13C-NMR, DSC, TGA and viscosity measurement methods. According to the FT-IR and NMR results, the polymerizations proceeded via vinyl group. As expected, solution viscosity measurements and DSC results showed that the glass transition temperature of polymer increases with increasing molecular weight.
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Mollier, Henri. "Synthèse de polyamines et de polyphosphonates : complexation d'ions paramagnétiques et d'émetteurs [gamma] : applications biomédicales." Grenoble 1, 1990. http://www.theses.fr/1990GRE10144.
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La synthese et l'etude physicochimique de complexes techneties et d'ions paramagnetiques par des ligands phosphoniques et phosphiniques constituent l'objet essentiel de ce travail. Les complexes techneties tc(sn)ttmp et tc(sn)btmp de ces ligands sont des vecteurs osteotropes qui se sont reveles d'excellents marqueurs lors des essais sur l'animal. L'extension a l'homme a revele qu'ils sont cependant moins performants que ceux actuellement commercialises. Les complexes ferriques fe ttmp et fe#3btmp sont des agents de contraste, pour l'imagerie par rmn a tropisme hepatobiliaire, augmentant la visualisation de tumeurs implantees. Les stchiometries et la stabilite en fonction du ph ont ete precisees. La determination des constantes de stabilite par une methode originale, la rmn #3#1p, conduit a des valeurs elevees. La rmn #3#1p a egalement permis de mettre en evidence leur grande stabilite au ph physiologique. La relaxivite spin reseau des protons de l'eau induite par fe ttmp et fe#3 btmp (230 s##1 mol##1 l et 580 s##1 mol##1 l) indique qu'aucune molecule d'eau n'est coordonnee a l'ion paramagnetique. La cinetique de decomplexation par les ions cn# de complexes phosphoniques, etudiee en uv, visible est compatible avec un mecanisme voisin de celui propose pour une serie d'acides carboxyliques amines homologues
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Vismara, Marcus Vinícius Gonçalves. "Estudo das propriedades dosimétricas de polímeros conjugados /." Bauru : [s.n.], 2011. http://hdl.handle.net/11449/99657.
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Resumo: Este trabalho teve como objetivo a investigação da interação de radiação gama com três polímeros: o polímero Poli(2-metóxi, 5-(2'-etil-hexilóx)-1,4- fenileno vinileno) (MEH-PPV)n e os polímeros solúveis em água Poly {[2,5-bis(2-(N,N-diethylamino)ethoxy) -1,4 -phenylene]-alt-1,4-phenylene} e o Poly [(2,5-bis (2 - (N,N - diethylammonium bromide) ethoxy) - 1,4 -phenylene) - alt - 1,4-phenylene]. O polímero MEH-PPV foi dissolvido nos solventes orgânicos clorofórmio e bromofórmio, já os outros dois polímeros, em água destilada e solução de HCI 1M. As amostras foram preparadas em várias concentrações e irradiadas com doses que variaram desde 0,01 Gy, sendo que cada amostra foi irradiada com apenas uma dose. Os resultados foram avaliados com técnicas espectroscópicas, sendo elas, espectroscopia de absorção óptica UV-visível e espectroscopia de fluorescência. Foi avaliada a alteração na posição do pico principal de absorção óptica com a dose absorvida pelas amostras. Como resultado principal, observou-se que os polímeros solúveis em água não apresentam alteração espectral após serem irradiados. Não sendo interessante para aplicação dosimétrica. Já para as amostras do polímero MEH-PPV diluídas em bromofórmio apresentaram alta sensibilidade para doses inferiores a 1 Gy, e apresentaram certa linearidade com a dose recebida (fator importante para aplicação dosimétrica). Para as amostras em clorofórmio, não foi observado deslocamento significativo do escpectro de absorção para doses inferiores a 1 Gy. No entanto para doses de 1 Gy à 90 Gy, o comportamento observado pode ser descrito por duas regiões lineares: uma com maior inclinação da reta para doses até cerca 30 Gy, e outro com inclinação da reta menor para doses entre 30 Gy e 90 Gy. O comportamento linear, assim como a inclinação da reta, do deslocamento da posição... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: The subject of this work is the investigation of gamma radition interaction with tree polymers: the polymer Poli(2-metóxi, 5-(2'-etil-hexilóx)-1,4- fenileno vinileno) (MEH-PPV)n e os polímeros solúveis em água Poly {[2,5-bis(2-(N,N-diethylamino)ethoxy) -1,4 -phenylene]-alt-1,4-phenylene} e o Poly [(2,5-bis (2 - (N,N - diethylammonium bromide) ethoxy) - 1,4 -phenylene) - alt - 1,4-phenylene]. The MEH-PPV polymer was dissolved in organic solvents, choloroform and bromoform, the other two polymers in distilled water and 1 M aqueous HCI solution. The samples were prepared at various concentrations and irradiated with doses ranging from 0.01 Gy to 90 Gy. The results were evaluated by spectroscopic techniques, which were, UV-visible absorption spectroscopy and fluorescence spectroscopy. They were evaluated the changes in the position of main optical absorption peak with the dose absorbed by the samples. As main result, it was observed that water-soluble polymers did not show spectral change after being irradiated. For dosimetric application this results are not interesting. For the MEH-PPV polymer samples diluted in bromoform presented highly sensitive to doses below 1 Gy, and showed some linearity with the dose received. For samples in chloroform, doses below 1 Gy did not showed significant shift in the absorption spectra. However, the samples irradiated with doses from 1 Gy to 90 Gy, the behavior can be described by two linear regions: one with a higher slope for doses up to about 30 Gy, and another with a lower slope for doses between 30 Gy and 90 Gy. A greater slope to doses up to about 30 Gy, and another with lower slope to doses between 30 and 90 Gy. The linear behavior and the slope of the main peak position is a important factor for dosimetric application. At the same time, a study of stability of the samples was performed. It was observed that the MEH-PPV samples in bromoform... (Complete abstract click electronic access below)
Orientador: Carlos Frederico de Oliveira Graeff
Coorientador: Marco Antonio Rodrigues Fernandes
Banca: Armando Beltran Flors
Banca: Antonio Ricardo Zanatta
O programa de Pós graduação em Ciência e Tecnologia de Materiais, PosMat, tem carater institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp
Mestre
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FERREIRA, HENRIQUE P. "Modificação e poli(fluoreto de vinilideno) induzida por radiação gama para aplicação como compósito ionomérico de metal-polímero." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10131.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Bazani, Dayana Luiza Martins. "Caracterização de polímeros semicondutores para o uso em sensores de radiação gama." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-13082008-094925/.
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Este trabalho tem por objetivo investigar as propriedades ópticas de sistemas poliméricos luminescentes submetidos a diferentes doses de radiação gama. Foram preparadas soluções de poli[2-metóxi-5-(2\'etil-hexilóxi)-p-fenilenovinileno] - MEHPPV em clorofórmio e filmes finos depositados a partir de soluções deste polímero sobre substrato de vidro. As soluções e filmes finos tiveram suas propriedades investigadas por meio de medidas de absorção ultravioleta-visível (UV-VIS). Os filmes finos também foram analisados por medidas de espectroscopia de infravermelho (FTIR) além da cromatografia HPSEC. Os resultados experimentais foram analisados buscando elucidar tanto os efeitos da radiação nas propriedades ópticas dos polímeros, como também o estudo da viabilidade destes materiais como elementos ativos de dosímetros para baixas doses de radiação gama (< 1 kGy) especialmente para aplicações no tratamento de esterilização de bolsas de sangue (~ 25 Gy) e altas doses de radiação gama (até 25 kGy) para aplicações como esterilização de materiais médicos hospitalares.This work aims the investigation of the optical properties of luminescent polymeric systems when submitted to different gamma radiation doses. Solutions of poly[2-methoxi-5-(2\'etil-hexiloxi)-p-phenilenevinilene] - MEH-PPV in chloroform were prepared. From those solutions, thin film layers of MEH-PPV were deposited on glass substrates. The polymer solutions and the thin-film samples of MEHPPV had their properties investigated by ultraviolet-visible (UV-Vis) absorption spectroscopy. The thin-film prepared samples were, additionally, investigated by InfraRed Fourier Transform (FTIR) spectroscopy and HPSEC chromatography. The experimental results were investigated to elucidate the radiation effects on the optical properties of these polymeric systems. From the experimental results, the feasibility of using this material as active element in gamma radiation dosimeters was investigated. The research was conducted aiming the low dose gamma radiation (< 1 kGy) specifically for application in the sterilization treatment of blood bags (~ 25 Gy) and high gamma radiation doses (up to 25 kGy) as used for the sterilization of medical and hospital supplies.
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TERENCE, MAURO C. "Obtencao de um sistema de liberacao controlada de drogas a partir do PVAL irradiado com radiacao gama." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10984.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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MOURA, ESPERIDIANA A. B. de. "Avaliação do desempenho de embalagens para alimentos quando submetidas a tratamento por radiação ionizante." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11427.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Papet, Gérard. "Etude cinetique du vieillissement radiochimique du polyethylene." Paris, ENSAM, 1987. http://www.theses.fr/1987ENAM0009.
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Etude de la radiolyse gamma du polyethylene basse densite dans l'air et a temperature ambiante. Les profils de distribution dans l'epaisseur de la concentration en carbonyles presentent une decroissance a une profondeur d'environ 180 microns. Determination des parametres cinetiques dans le cas ou la diffusion ne controle pas le vieillessement. Etude de modeles theoriques et de l'evolution des proprietes mecaniques pendant la degradation radiochimique
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Bakioglu, Levent. "Polymerization And Characterization Of Poly(ethyl Methacrylate)." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1081363/index.pdf.
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In this study, ethyl methacrylate was polymerized by free radical polymerization at 600C, 700C, 800C at open atmosphereatom transfer radical polymerization, (ATRP), at 800C in vacuum and in gamma irradiation in vacuum. The polymer obtained was white, hard material. The kinetic curves for free radical polymerization and ATRP by gamma radiation were S-type. However, the curve for polymerization by gamma irradiation raises more smoothly. For ATRP by thermal initiation gives a lineer change of conversion with time. It was observed that the molecular weight can be controlled and low molecular weight polymer could be obtained by ATRP method. The characterization of polymers were made by FTIR, DSC, 1H and 13C NMR techniques.
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MARTIN, SANDRA R. S. "Recuperação/reciclagem de compostos de borrachas butílica e halobutílica por meio de radiação ionizante." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10549.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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FERRAZ, CAROLINE C. "Desenvolvimento de uma membrana nanoestruturada à base de poliacrilamida para veiculação de proteínas." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10539.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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KIYAN, LUDMILA de Y. P. "Aplicação da radiação gama para incorporação do pó de borracha em formulações de borracha EPDM e nitrílica." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23177.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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FERRETO, HELIO F. R. "Estudo da sintese copolimero olefínico à base de politetrafluoroetileno (PTFE) por meio da enxertia induzida por radiação gama." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11420.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
44
Rose, Marcus, Andreas Notzon, Maja Heitbaum, Georg Nickerl, Silvia Paasch, Eike Brunner, Frank Glorius, and Stefan Kaskel. "N-Heterocyclic carbene containing element organic frameworks as heterogeneous organocatalysts." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138636.
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A bifunctional imidazolium linker was used for the production of highly crosslinked element organic frameworks by Suzuki-coupling with tetrafunctional boronic acids. The resulting porous materials are good heterogeneous organocatalysts in the N-heterocyclic carbene-catalyzed conjugated umpolung of α,β-unsaturated cinnamaldehydeDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Ngono, Yvette. "Comportement à long terme des résines thermodurcissables en milieu irradiant : rôle et action de l'eau." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10131.
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Ce travail base sur l'etude de l'effet simultane de l'eau et des rayonnements ionisants a ete fait sur deux resines epoxydes susceptibles d'etre utilisees dans l'industrie nucleaire. Les objectifs poursuivis sont d'une part de determiner l'evolution des materiaux sous l'action des rayonnements ionisants (en presence ou en absence d'eau) et d'autre part de suivre leur comportement a l'hydratation en fonction de la dose absorbee. Les deux methodes spectroscopiques utilisees dans cette etude, d'une part l'infrarouge appliquee a la caracterisation des defauts chimiques d'irradiation et a l'etude de l'hydratation et d'autre part la rmn 1 3c haute resolution en phase solide appliquee a la caracterisation des defauts d'irradiation et au suivi de la mobilite locale des groupements de la resine, se sont revelees tres precieuses. L'action des rayonnements ionisants sur les resines etudiees conduit d'une part a la formation de produits d'oxydation que sont les amides, acides carboxyliques, cetones et esters et d'autre part a des ruptures de chaine avec formation de phenol. Lors d'une irradiation en milieu humide, la proportion d'esters formes est plus faible alors que les ruptures des chaines sont plus importantes. Par ailleurs, le suivi de la mobilite locale, par rmn haute resolution en phase solide, montre une diminution des mouvements par irradiation avec des rayons , attribuee a la rigidification des resines concernees. Apres irradiation, la capacite d'absorption d'eau des resines augmente. Il n'existe pratiquement pas de difference d'absorption entre les resines dgeba/ddm irradiees en milieu humide et celles irradiees en milieu sec, a des doses d'irradiation similaires. Avant irradiation, la fixation de molecules h 2o sur d'autres molecules h 2o se fait dans l'environnement des alcools. Par contre, apres irradiation, de telles associations s'etablissent pres des c = o.
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Lage, Laércio Gomes. "Poliuretanas: caracterização, avaliação estrutural e efeito induzido pela radiação gama." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-28032018-113201/.
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Poliuretana (PUR) é uma classe de polímeros que possui grupos uretânicos [-O-C(=O)-NH-] em sua estrutura e encontra diversas aplicações, inclusive na área biomédica. Esta versatilidade é devida ao uso de diferentes monômeros em sua síntese. O uso de isocianatos cicloalifáticos, um dos monômeros da PUR, é mais vantajoso em aplicações que requeiram uma maior estabilidade térmica e à radiação ultravioleta e maior resistência à hidrólise. Quando processadas inapropriadamente, as PUR baseadas em isocianatos aromáticos produzem compostos carcinogênicos, fato não observado para as PUR com isocianatos cicloalifáticos. Visando a aplicação biomédica, a PUR tem sido modificada através da incorporação de grupos iônicos à cadeia polimérica, formando ionômeros. A esterilização de materiais de uso biomédico é feita pelo emprego de óxido de etileno ou da radiação gama. Neste trabalho, visou-se a síntese e caracterização da PUR e do ionômero sultanado desta, baseadas em isocianato cicloalifático, além do estudo do efeito da radiação gama nos polímeros. Foi observado através da espectroscopia vibracional e análise elementar que se formam ligações de alofanato, uma ramificação da PUR linear. Comparando-se a PUR sintetizada com uma amostra comercial de PUR linear de uso biomédico, amorfa, verificou-se que a primeira apresentava cristalinidade. O estudo da cinética de decomposição térmica da PUR permitiu estabelecer o mecanismo com o qual acontece a decomposição. A estabilidade térmica e cristalinidade da PUR sulfonada são maiores que para a PUR, devendo estar relacionadas à contribuição dos grupos sulfonato. A PUR sulfonada tem um maior tempo de vida estimado que a PUR, nas temperaturas estudadas. A irradiação das amostras permitiu a verificação da oxidação do segmento do poliol e/ou extensor de cadeia, por meio da diminuição de intensidade das bandas relacionadas a este segmento nos espectros vibracionais e diminuição da cristalinidade por DSC.Polyurethane (PUR) is a class of polymers that possesses urethane groups [O-C(=O)-NH-] in its structure and that find many applications, including biomedical ones. This variety is due to the use of different monomers in its synthesis. The use of aliphatic isocyanates, one of PUR monomers, is more valuable in applications that demand stability to UV radiation, resistance to hydrolysis, and a greater thermal stability. The aromatic isocyanate-based PUR produces, when processed incorrectly, carcinogenic compounds, a fact that is not observed in the cycloaliphatic isocyanate-based PUR. The PUR modification to use it in biomedical artifacts has been made, among some procedures, through the incorporation of ionic groups into the polymer chain, forming ionomers. The biomedical materials sterilization is made employing ethylene oxide or gamma radiation. The objectives of this work are the synthesis and characterization of PUR and its sulfonated ionomer, both based on a cycloaliphatic isocyanate, as well as the study of the effect of gamma radiation in the polymers. It has been observed the formation of allophanate linkages through the analysis of vibrational spectra and elemental analysis data. Comparing the synthesized PUR and a commercial, amorphous, linear PUR used in biomedical artifacts, it has been noted that the former has crystallinity. The kinetic study of thermal decomposition of PUR allowed to establish the decomposition mechanism of PUR. The thermal stability and crystallinity of sulfonated PUR are greater than of PUR, probably due to the contribution of sulfonic groups. The lifetime of sulfonated PUR is greater than that of PUR, in the temperature range studied. The samples irradiation has permitted the observation of poliol and/or chain extender oxidation, by means of the decreasing of the intensity of the vibrational bands related to these groups and the decreasing of crystallinity in DSC.
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Moura, Esperidiana Augusta Barretos de. "Avaliação do desempenho de embalagens para alimentos quando submetidas a tratamento por radiação ionizante." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-22032012-172658/.
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No presente trabalho foram estudadas as propriedades mecâncias (resistência à tração e porcentagem de alongamento na ruptura e resistência à perfuração), propriedades ópticas, permeabilidade ao gás oxigênio e ao vapor d\'água, migração total em simulante aquoso (ácido acético 3%) e gorduroso (n- heptano), e a formação de produtos voláteis da radiólise, com vistas à avaliar o efeito da radiação ionizante (raios gama e feixe de elétrons) em filmes flexíveis mono e multicamadas comerciais, fabricados no Brasil para a indústria de produtos cárneos. Os filmes estudados foram: um monocamada de polietileno de baixa densidade (LDPE) e um multicamadas coextrusado composto de polietileno de baixa densidade (LDPE), copolímero de etileno e álcool vinílico (EVOH) e poliamida (PA), ou seja, a estrutura: LDPE/EVOH/PA. As irradiações foram realizadas em uma fonte de 60Co do tipo Gammacell e em um acelerador de elétrons do tipo eletrostático (l,5MeV), com doses de até 30 kGy, na temperatura ambiente e presença de ar. As alterações nas propriedades foram avaliadas de acordo com a dose de radiação aplicada, oito dias após a irradiação e novamente, dois a três meses após a irradiação. Os resultados mostraram que as reações de cisão predominaram sobre as reações de reticulação para ambos os filmes estudados, irradiados com raios gama ou com feixe de elétrons. As variações observadas em função da irradiação, nas propriedades avaliadas não limitam a aplicação final desses filmes, uma vez que não ultrapassaram o limite de segurança especificado pelo fabricante em nenhuma dose e período em que foram estudadas. Concluiu-se que os filmes estudados podem ser utilizados, sob o ponto de vista das propriedades avaliadas, como embalagens para produtos pasteurizáveis por radiação e radioesterilizáveis usando irradiadores gama ou aceleradores de elétrons, nas doses de radiação estudadas.In this study the mechanical properties (tensile strength and percentage elongation at break and penetration resistance), optical properties, gas oxygen and water vapor permeability, the overall migration tests into aqueous food simulant (3% aqueous acetic acid) and fatty food simulant (n-heptane), as well as the formation of volatile radiation product tests were used to evaluate the effects of ionizing radiation (gamma irradiation or electron-beam irradiation) on commercial monolayer and multilayer flexible plastics packaging materials. These films are two typical materials produced in Brazil for industrial meat packaging, one of them is a monolayer low-density polyethylene (LDPE) and other is a multilayer co extruded low-density polyethylene (LDPE), ethylene vinyl alcohol (EVOH), polyamide (PA) based film (LDPE/EVOH/PA). Film samples were irradiated with doses up to 30 kGy, at room temperature and in the presence of air with gamma rays using a 60Co facility and electron beam from 1.5 MeV electrostatic accelerator. Alterations of these properties were detected according to the dose applied initially eight day after irradiation took place and new alterations of these values when the properties were evaluate two to three months after irradiation process. The results showed that scission reactions are higher than cross-linking process for both studied films, irradiated with gamma rays and electron beam. The evaluated properties of the irradiated films were not affected significantly with the dose range and period studied. The monolayer Unipac PE-60 and the multilayer Lovaflex CH 130 films can be used as food packaging materials for food pasteurization and in the sterilization process of by ionizing radiation using a gamma facilities and electron beam accelerators in commercial scale.
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Rose, Marcus, Andreas Notzon, Maja Heitbaum, Georg Nickerl, Silvia Paasch, Eike Brunner, Frank Glorius, and Stefan Kaskel. "N-Heterocyclic carbene containing element organic frameworks as heterogeneous organocatalysts." Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27766.
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A bifunctional imidazolium linker was used for the production of highly crosslinked element organic frameworks by Suzuki-coupling with tetrafunctional boronic acids. The resulting porous materials are good heterogeneous organocatalysts in the N-heterocyclic carbene-catalyzed conjugated umpolung of α,β-unsaturated cinnamaldehyde.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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CUNHA, TATIANA F. da. "Aplicação do poli(epsilon-caprolactona) com estrutura estrelada para obtenção de microesferas biorreabsorvíveis." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10544.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
50
Fel, Elie. "Mise en oeuvre de mélanges de polyoléfines compatibilisées par ajout de copolymères ou à l'aide d'irradiation gamma : Caractérisation d'espèces réactives par Résonance Paramagnétique Electronique (RPE)." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0049/document.
Full textAbstract:
Des procédés innovants basés sur l’extrusion à haute vitesse et l’irradiation sous rayonnement γ, ont été étudiés en vue d’améliorer la compatibilisation de deux polyoléfines non miscibles : le polypropylène PP et le polyéthylène PE. Dans un premier temps, l’étude de la distribution des temps de séjour de polypropylènes dans l’extrudeuse à haute vitesse a été réalisée. L’impact des conditions opératoires (débit et vitesse de rotation des vis) ainsi que l’impact du profil de vis et de la viscosité du polypropylène d’étude ont été mis en avant. Certains résultats expérimentaux sont souvent en accord avec ceux du logiciel de simulation d’extrusion bi-vis Ludovic, bien qu’il puisse y avoir des écarts pour les hautes vitesses de rotation des vis. Dans un deuxième temps, une fois l’écoulement caractérisé, nous avons réalisé des mélanges PP/PE, les paramètres qui ont varié sont la quantité d’énergie apportée durant le mélange (vitesse de rotation des vis) ainsi que la présence ou non de copolymère préformé et le type d’atmosphère utilisée durant l’extrusion. Faire varier le taux de cisaillement ne permet pas la modulation des propriétés finales du mélange surtout lorsque l’on extrude sous atmosphère inerte. L’utilisation de copolymère préformé, de type éthylène-octène, permet d’améliorer considérablement les propriétés de notre mélange en créant une interphase "cœur-couronne" entre la matrice PP, le compatibilisant et la phase dispersée PE. Pour terminer, une étape d’irradiation γ a été ajoutée au procédé de mise en œuvre classique de nos mélanges. En première partie de cette étude, la simulation de spectres RPE a permis d’identifier et quantifier les différentes espèces radicalaires créées. Dans la deuxième partie, l’influence de la place de la séquence d’irradiation a été étudiée : avant extrusion, entre extrusion et injection, après injection et avant recuit. Les meilleures améliorations ont été obtenues lorsque l’irradiation est suivie d’un traitement thermique. En conclusion, il est possible d’améliorer la compatibilité d’un mélange PP/PE en jouant essentiellement sur l’ordre des étapes de production sans avoir à modifier la formulation de ce dernierInnovative processes, based on high shear twin screw extrusion and γ-irradiation, have been used to increase the compatibility of two immiscible polyolefins: polypropylene PP and polyethylene PE. In a first part, the residence time distribution of polypropylenes in the twin screw extruder (TSE) has been investigated. The impact of the processing conditions (throughput and screw rotation speed), the screw profile and the polypropylene viscosity were underlined. Some of the experimental results are often in good agreement with those predicted by simulation software of twin screw extrusion (Ludovic), except for some experiments at high screw rotation rates. In a second part, once polymer flow was characterised in the TSE, we realized PP/PE blends. The impact of the mechanical energy (screw rotation speed), the presence or absence of copolymers and the nature of the extrusion atmosphere were analysed. Using high shear rate does not allow modulating the final properties of the blends particularly once inert atmosphere is used. The use of ethylene-octene copolymers increases significantly the final properties of the PP/PE blends by creating a “core-shell” morphology between the PP matrix, the copolymer and the PE dispersed phase. To finish, a γ-irradiation process step has been added to the classical processing of PP/PE blends. In a first part of this study, the simulations of ESR spectra have permitted to identify and quantify the different radicals created. In a second part, the sequence order of the γ-irradiation has been investigated: before extrusion, between extrusion and injection, and after injection followed by a thermal treatment. The best results were obtained once γ-irradiation is followed by a heat treatment. As a conclusion, the compatibility of immiscible polyolefins can be improved only by changing the order of the different processing steps without changing the formulation