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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The enzymatic release of glycosidically-bound terpenes in must

Strauss, Lindie Helene January 1989 (has links)
Bibliography: pages 79-86. / Flavour in wines is perhaps the most important factor affecting wine quality, with monoterpenoids being among the compounds contributing to flavour. In grapes there exists glycosidically-bound forms of these monoterpenes, representing a latent source of aroma. This project is a study on the ability of different enzymes to release these monoterpenes in Muscat d'Alexandrie and Weisser Riesling grapes. Different commercial enzyme preparations were characterised with respect to their catalytic properties and fractionated by ion exchange chromatography in the most active fractions. Amongst those commercial preparations tested, Rohapect C was found to be the most effective at conditions prevalent during wine making. These purified fractions were added to the above mentioned grapes to determine their effect on the release of different monoterpenes. Even though the enzymes were active on synthetic substrates, limited release of terpenes from must could be detected. Possible causes for this apparent inability to release monoterpenes were investigated. Product inhibition due to the presence of high concentrations of glucose in the must appeared to be the main cause of limited enzyme activity. In an attempt to overcome this problem, glucose in the above mentioned cultivars was oxidised to gluconic acid by glucose oxidase, prior to attempting monoterpene release by Rohapect C. Although no marked increase in the release of total terpenes occured, a significant increase in the concentrations of some individual terpenes could be observed. The effect of this on wine quality remains to be ascertained.
2

Social movement learning, student protest and higher education: An exploration of #FeesMustFall at UWC

Mdepa, Anele Arnold January 2020 (has links)
Magister Educationis (Adult Learning and Global Change) - MEd(AL) / This study examines student activism and student protests that occurred at South African higher education institutions (HEIs) during the academic years 2015 and 2016. These protests were inspired by multiple grievances experienced by students at HEIs, which included protesting against the maintenance and celebration of imperial symbols at universities as well as the unaffordability of academic and residence fees. These protests were different to previous student protests in that student discontentment and protests were popularised and advocated through social media under Twitter hashtags such as #RhodesMustFall (RMF) and #FeesMustFall (FMF).
3

Characterisation, evaluation and use of non-Saccharomyces yeast strains isolated from vineyards and must

Jolly, N. P. (Neil Paul) 03 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Wine is the product of a complex biological and biochemical interaction between grapes and different microorganisms (fungi, yeasts, lactic acid bacteria and acetic acid bacteria, as well as the mycoviruses and bacteriophages affecting them) in which yeasts play the most important role regarding the alcoholic (primary) fermentation. These wine-associated yeasts can be divided into Saccharomyces and non-Saccharomyces yeasts. During fermentation, there is a sequence of dominance by the various non-Saccharomyces yeasts, followed by Saccharomyces cerevisiae, which then completes the fermentation. This is especially evident in spontaneously fermenting must, which has a low initial S. cerevisiae concentration. Some non- Saccharomyces yeasts can also be found throughout the fermentation. The non- Saccharomyces presence in the fermentation can affect wine quality, either positively or negatively. A positive contribution could be especially useful to improve wines produced from grape varieties with a neutral flavour profile due to non-optimal climatic conditions and/or soil types. As part of a comprehensive South African research programme, the specific objectives of this study were: the isolation of indigenous non-Saccharomyces yeasts from vineyards and musts; the identification of these isolates; the characterisation and evaluation of predominant species under winemaking conditions; and the development of a protocol for their use in enhancing wine quality. Initially, 720 isolates representing 24 different species, were isolated from grape (vineyard) and must samples taken over three vintages from four distinctly different wine producing regions. The isolates were characterised and grouped utilising biochemical profiles and DNA karyotyping, whereupon representative isolates were identified. The yeast species that had the highest incidence of predominance in the vineyard was Kloeckera apiculafa. However, some vineyard samples were characterised by low numbers or absence of this yeast, which is not according to generally accepted norms. Other species that also predominated in a few of the vineyard samples were Candida pulcherrima, Kluyveromyces thermofolerans, Rhodotorula sp. and Zygosaccharomyces bailii. Generally, there was a greater diversity of yeasts in the processed must than from the vineyard samples. Furthermore, while each sample showed a different yeast population, no pattern linking species to climatic zone was observed. Four species i.e. Candida collieulosa, Candida pulcherrima, Candida stel/ata and Kloeckera apiculata, were found to predominate in grape must samples. Representative strains consequently received further attention during laboratory and small-scale winemaking trials. A protocol was developed whereby individual species could be used in co-inoculated fermentations with S. cerevisiae in the small-scale production of wine. An improvement in wine quality was achieved and it was found that there was a link between specific species and grape cultivar. The ability of C. pulcherrima to improve Chenin blanc wine quality was investigated further. Results over three vintages showed that the wine produced by the co-inoculated fermentation was superior to that of a reference wine (produced by S. cerevisiae only). The improvement in wine quality was not linked to increased ester content nor were the standard chemical analyses adversely affected. The effects of pH and wine production parameters i.e. 802, fermentation temperature and use of di-ammonium phosphate (DAP), on this yeast followed the same pattern as that known for S. cerevisiae. This study was successfully completed and the developed protocol can be used for the improvement of Chenin blanc wine where additional aroma and quality is needed. / AFRIKAANSE OPSOMMING: Wyn is die produk van 'n komplekse biologiese en biochemiese interaksie tussen druiwe en mikroorganismes (swamme, giste, melksuurbakterieë, asynsuurbakterieë, asook die mikovirusse en bakteriofage wat hul beïnvloed) waar gis die belangrikste rol speel ten opsigte van die alkoholiese (primêre) fermentasie. Die betrokke giste kan in Saccharomyces- en nie-Saccharomyces-giste verdeel word. Tydens gisting vind daar 'n opeenvolging van dominansie deur die verskillende nie-Saccharomyces giste plaas, gevolg deur Saccharomyces cerevisiae, wat dan die gisting voltooi. Dit is veral in spontaan fermenterende mos, waarin aanvanklik lae konsentrasies S. cerevisiae-gisselle voorkom, waarneembaar. Sekere nie-Saccharomyces-giste kan ook regdeur die verloop van fermentasie gevind word. Die teenwoordigheid van nie-Saccharomyces-giste kan 'n bydrae maak tot wynkwaliteit, hetsy positief of negatief. 'n Positiewe bydrae kan veral nuttig wees vir die verbetering van wyn geproduseer van druifsoorte met neutrale geurprofiele as gevolg van nie-optimale klimaatstoestande en/of grondtipes. As deel van 'n uitgebreide Suid-Afrikaanse navorsingsprogram, was die doelwitte van hierdie studie soos volg: die isolasie van inheemse nie-Saccharomyces-giste vanuit wingerde en mos; die identifikasie van hierdie isolate; die karakterisering en evaluering van spesies wat tydens wynbereiding oorheers; en die ontwikkeling van 'n protokol waarin geselekteerde nie- Saccharomyces-giste gebruik kan word vir die verbetering van wynkwaliteit. Druif- en mosmonsters is oor drie oestye vanuit vier duidelik onderskeibare wynproduserende gebiede geneem en 720 isolate, verteenwoordigend van 24 verskillende spesies, is hieruit geïsoleer. Hierdie isolate is volgens biochemiese profiele en DNA-kariotipering gekarakteriseer en gegroepeer waarna verteenwoordigende isolate geïdentifiseer is. Die gisspesie wat die meeste in wingerde voorgekom het, was Kloeckera apiculata. Sommige wingerde is egter deur lae getalle of afwesigheid van dié gis gekenmerk, In feit wat afwyk van die algemeen aanvaarde norm. Ander spesies, nl. Candida pulcherrima, Kluyveromyces thermotolerans, Rhodotorula sp. en Zygosaccharomyces bailii, het ook in enkele gevalle in die wingerdmonsters oorheers. Oor die algemeen was daar 'n groter diversiteit van giste in die geprosesseerde mos as in die wingerdmonsters. Verder is elke monster gekenmerk deur verskillende gispopulasies, maar geen verband tussen gisspesie en klimaatsone is waargeneem nie. Vier spesies, nl. Candida collieulosa, Candida pulcherrima, Candida stel/ata en Kloeckera apiculata, het in hoë getalle in die druiwemosmonsters oorheers en verteenwoordigende rasse het verdere aandag tydens laboratorium- en kleinskaalse wynmaakproewe geniet. 'n Protokol, waar hierdie rasse individueel gebruik is in gesamentlike geïnokuleerde fermentasies met S. cerevisiae vir die kleinskaalse produksie van wyn, is ontwikkel. 'n Verbetering in wynkwaliteit is verkry en daar is 'n verband tussen spesifieke gisspesies en druifvariëteit gevind. Gevolglik is die vermoë van C. pulcherrima om die gehalte van Chenin blanc wyn te verbeter, verder ondersoek. Resultate oor drie oesjare het gewys dat die wyn wat met die C. pulcherrima / S. cerevisiae kombinasie geproduseer is, beter was as 'n verwysingswyn (deur slegs S. cerevisiae geproduseer). Die waargenome verbetering in wynkwaliteit was egter nie aan 'n verhoging in esterinhoud te danke nie en die standaard chemiese analises het geen negatiewe afwyking uitgewys nie. Verder is gevind dat die effek van pH en wynproduksieparameters, nl. die gebruik van S02, fermentasietemperatuur en die gebruik van di-ammoniumfosfaat (DAP), dieselfde patroon as die bekend vir S. cerevisiae gevolg het. Die ontwikkelde protokol kan nou aangewend word waar verhoogde Chen in blanc wynaroma en kwaliteit verlang word.
4

Exploratory descriptive study of the support tissue in keloids

Arbi, Sandra January 2014 (has links)
Keloids are benign hyper-proliferative growths of fibrous tissue, where increased fibroblast activity results in abnormal collagen deposition. Scientific literature related to the morphological features of keloids especially at an ultrastructural level is outdated. Therefore the aim of this study was to reassess present knowledge of the ultrastructural features of keloids and possibly through this process identify new cellular therapeutic targets. The research was conducted on normal (control) and keloid human skin samples collected from consenting patients undergoing keloid removal and skin transplantation surgeries at the Steve Biko Academic Hospital. The tissue structure of normal/control skin and keloids as well as mast cell and collagen distribution were evaluated using histological techniques. Transmission electron microscopy techniques were undertaken in order to investigate morphological and ultrastructural features of cells of the epidermis and dermis. A further detailed analysis of the ultrastructure of keloid fibroblasts and mast cells was undertaken. The findings of this study have lead to a new hypothesis related to keloid formation. Increased fibroblast activity, intracellular collagen production and fibroblast and mast cell interactions were seen in keloid tissue. Changes in the morphology of keratinocytes and melanocytes were observed, where the cytoplasmic processes of both cells were shorter and cells were packed closer together in keloids. Keloid tissue appeared to be in a hyperproliferative state similar to that of the granulation phase of wound healing. Increased amounts of collagen were found in the extracellular matrix (ECM) of keloid tissue. This is the first study in which the abnormal accumulation of insoluble collagen fibrils was observed in the cytoplasm. Degranulation of mast cells had occurred and these cells were found in close association with fibroblasts. In some instances phagocytosis of collagen by mast cells was also observed. These observations have led to the hypothesis that transforming growth factor β (TGF-β) derived from mast cells, inhibits keratinocyte proliferation and stimulates increased collagen production through increased expression of lysyl oxidase (LOX) by fibroblasts. Intracellular insoluble collagen formation then occurs due to the rapid, intracellular removal of the C terminal pro-peptide sequence by C-proteinase which initiates the cascade of insoluble collagen fibre formation within the fibroblast. Normally this process occurs only within the ECM in response to the increasing mass of collagen and in an attempt to establish normal tissue homeostasis the mast cells engulf the bundles of collagen fibres. Increased stress on the epidermal layer causes increased keratinocyte proliferation, which results in further growth factor mediated replication of fibroblasts. This creates an endless cycle of collagen synthesis, mast cell degranulation and mast cell mediated collagen phagocytosis, physical stress on the epidermal layer and subsequent growth factor release and fibroblast activation, collagen synthesis and subsequent crowding of keratinocytes and melanocytes. In conclusion, this study identified keloid formation as a defect of procollagen synthesis and processing. Phagocytosis of collagen by mast cells indicates that accumulation of these cells may be a secondary effect to excessive collagen synthesis. In addition, the release of interleukins, mediators and growth factors may further stimulate collagen fibril formation with the imbalance toward increased synthesis. This study also identified and confirmed the findings of other studies that procollagen C-proteinase is an important therapeutic target. / Dissertation (MSc)--University of Pretoria, 2014. / tm2015 / Anatomy / MSc / Unrestricted
5

Investigation of alcoholic and malolactic fermentation using high performance liquid chromatography

Lee, Suk Hean January 2000 (has links)
No description available.
6

Využití techniky DGGE k analýze a identifikaci vybraných druhů mikroorganismů / Use of DGGE to analysis and identification of selected microorganisms

Jankeje, Kristína January 2011 (has links)
Presented diploma thesis is focused on use of DGGE to analysis and identification of selected microorganisms. PCR-DGGE is a method that allows direct characterization of the microbial community in the natural environment without necessity of cultivation. A literature review is devoted to the principle of the method, current applications and its limitations too. In experimental part microbial DNA was isolated and used as a template for PCR reaction. Microbial DNA was then amplified using the universal eukaryotic primers that target the D1/D2 domain of the 26S subunit of ribosomal DNA. To improve specificity and sensitivity of detection nested PCR was chosen using outer and inner primer pairs. Generated amplicons (250 bp) were consequently separated by DGGE. The analysis of selected microorganisms by DGGE technique was performed after optimization of electrophoresis conditions (in particular the denaturing gradient extent and separation time). Despite the optimization, mutual differentiation among individual yeast strains was not possible since each reference strain was represented by several bands in the same positions. In conclusion DGGE profile obtained from wine musts is discussed. Present bands suggest the major presence of non-Saccharomyces yeasts, yeast-like strain A. pullulans is present in the minority and Saccharomyces yeasts are probably present too. The technique remains open for further optimization, particularly as regards the conditions of polymerase chain reaction.
7

An Evaluation of Transfer Capability Limitations and Solutions for South Mississippi Electric Power Association

Brown, Nathan L 11 May 2002 (has links)
Historically, transmission transfer capability between transmission systems was typically assumed based on the thermal limits of specific transmission paths. Because electric transmission systems are becoming more and more heavily loaded, accurately evaluating transfer capability between transmission systems and maintaining minimum levels of transfer capability has become increasingly important. This Thesis evaluates the transfer capability needs and limitations of a specific small electric utility. Identified are various analysis tools and evaluation methods used to determine transfer capability. Two specific evaluation methods are analyzed and compared to determine the best method of determining transfer capability. Various solutions, including upgrading existing or installing new transmission interconnections, are identified and evaluated to determine the best overall solution to achieve and maintain the utility?s desired transfer capability level.
8

Privalomo skaitmeninės televizijos retransliavimo elektroninių ryšių tinklais teisinis reguliavimas / Legal regulation of digital television mandatory retransmission in electronic communications networks

Vitkus, Donatas 24 January 2012 (has links)
Naujųjų technologijų teisės magistro baigiamojo darbo temos aktualumas ir naujumas susijęs su besikeičiančiomis televizijos transliavimo technologijomis ir visuotiniu analoginės antžeminės televizijos išjungimu Lietuvoje ir Europos Sąjungoje. Privalomo televizijos retransliavimo elektroniniais ryšių tinklais, kitaip vadinamu „must carry“, modelis įvestas esant analoginei televizijai. Besikeičiančios technologijos verčia analizuoti teisinį reguliavimą ir ieškoti galimų geresnio ir efektyvesnio reguliavimo modelio. Skaitmeninės televizijos privalomo retransliavimo instituto svarba atskleidžiama nagrinėjant technologinę skaitmeninės televizijos pusę, pasitelkiant technologinių mokslų žinias. Išryškinami skirtumai nuo analoginės televizijos. Analizuojama privalomo retransliavimo instituto atsiradimo priežastys, aplinka, atskleidžiami instituto tikslai. Taip pat identifikuojamos transliavimo, retransliavimo, signalų siuntimo sąvokos. Analizuojant privalomo skaitmeninės televizijos retransliavimo elektroniniais ryšių tinklais teisinį reguliavimą Europos Sąjungoje pasitelkiamas loginis bei teleologinis metodai. Analizuojama Universaliųjų paslaugų direktyva, kurios 31 straipsnyje įtvirtintas privalomo televizijos retransliavimo principas. Detaliau nagrinėjama Austrijos, Vokietijos, Didžiosios Britanijos privalomo televizijos retransliavimo teisinis reguliavimas. Privalomo televizijos retransliavimo teisinis reguliavimas Lietuvoje analizuojamas nuo jo ištakų – Konstitucijoje saugomų... [toliau žr. visą tekstą] / The relevance and the novelty of the Master’s Work in New Technologies Law related to changing technology of television broadcasting and to universal analogue television turn-off in Lithuania and European Union. Television mandatory retransmission in electronic communications networks model, also called “must carry”, was created to analogue television. Changing technologies cause to analyze legal regulation and seek to create better and effective model of “must carry” regulation. Importance of the institute of digital television mandatory retransmission disclosed the analysis of digital television technology, using the knowledge of technologies science. There are highlighted differences between digital and analogue televisions. There are made analyzes of digital television mandatory retransmission establishing reasons and environment, made disclosure of the objectives of the “must carry” institute. There are also identified terms of broadcasting, retransmission, signal transporting. There are using logical ant theological methods to analyze digital television mandatory retransmission in European Union and Lithuania. In this work there is analyzed Universal Service Directive, which have “must carry” rule in 31 article. Detailed analyze made for Austrian, German, Great Britain legal regulation of digital television mandatory retransmission. Legal regulation of television mandatory retransmission in Lithuania is analyzed from the first source – from the Constitution. Comparative... [to full text]
9

Auto-triagem como instrumento para avaliação do risco nutricional em adultos hospitalizados

MORAIS, Glaucia Queiroz 25 February 2016 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-12-01T13:09:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO GLAUCIA PDF.pdf: 3704357 bytes, checksum: 1dc85b37dac1dafed212e355c1aef07d (MD5) / Made available in DSpace on 2016-12-01T13:09:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO GLAUCIA PDF.pdf: 3704357 bytes, checksum: 1dc85b37dac1dafed212e355c1aef07d (MD5) Previous issue date: 2016-02-25 / A desnutrição é um achado comum em pacientes hospitalizados e muitas vezes seu quadro é agravado pela falta de diagnóstico precoce. Cuidados nutricionais adequados começam com a identificação de pacientes em risco nutricional (RN) no momento do internamento, por intermédio de uma ferramenta de triagem. Entretanto, com o aumento de admissões hospitalares, torna-se impraticável ao profissional de saúde triar todos os pacientes em tempo hábil. O presente estudo, do tipo de avaliação, teve como objetivo avaliar a aplicabilidade de um instrumento de auto-triagem nutricional em pacientes adultos de ambos os sexos admitidos para internamento no período de julho a outubro de 2015 em um hospital público de Pernambuco. A auto-triagem nutricional foi realizada pelos pacientes elegíveis, como também pelo pesquisador, e ao final sua concordância foi avaliada pelo coeficiente Kappa. A avaliação da diferença entre a altura e o peso aferidos pelo avaliador e a altura referida e o peso aferido pelo paciente foi realizada por meio do teste de Wilcoxon, sendo construído o gráfico de Bland & Altman. Para avaliar a associação entre variáveis clínicas e sociodemográficas com o risco nutricional identificado pelo avaliador foi realizado teste do Qui-quadrado. O estudo envolveu 171 pacientes, sendo 59,1% do sexo feminino. A idade média dos pacientes foi de 51,7 ± 15,3 anos. Os resultados mostraram que um percentual elevado 47,9% (n=82) de pacientes não conseguiram realizar a auto-triagem, devolvendo o formulário ao pesquisador em branco ou incompleto, sendo o baixo grau de instrução e idade uma das principais razões. O peso médio registrado pelo paciente (68,4Kg ± 15,0) foi semelhante ao aferido pelo nutricionista (68,2Kg ± 15,1), resultado similar foi evidenciado na comparação entre a altura referida pelo paciente e a aferida pelo nutricionista, com diferencial de 0,03cm. Na comparação entre o RN avaliado pelo profissional de nutrição e o RN avaliado pelo paciente na auto-triagem, verifica-se que houve concordância no diagnóstico de RN em 91,9% dos casos e que 26,9% dos pacientes considerados sem risco pelo profissional foram incluídos como risco na auto-triagem. Na análise realizada pelo Kappa houve moderada concordância entre os dois diagnósticos (k=0,62; p=0,001). Na avaliação da concordância entre as duas aferições de peso e altura com o teste de Bland Altman, verificou-se uma boa concordância, com viés próximo a zero nas duas avaliações. De um modo geral, consideramos satisfatória, para a prática clínica, os resultados da auto-triagem. No entanto, como somente 52,1% da população foi capaz de responder o instrumento, conclui-se que ainda não é viável sua inclusão em um serviço que atenda pessoas de baixo grau de instrução, sugerindo então que novas pesquisas e adaptações para auto-triagem sejam realizadas. / Malnutrition is a common finding in hospitalized patients, and often the condition deteriorates for lack of an early diagnosis. Proper nutritional care begins with the identification of patients at nutritional risk by use of a screening tool on admission. However, as hospital admissions increase, it is impossible for health professionals to screen all patients in a timely manner. The present study aimed to assess the applicability of a nutritional self-screening tool in adult males and females admitted to a public hospital in Pernambuco between July and October of 2015. Nutritional self-screening was performed by eligible patients and by the researcher, and later their agreement was measured by the Kappa coefficient. The differences between the self-reported and measured weight and height were assessed by Wilcoxon’s test, with subsequent construction of the Bland & Altman graph. The chi-square test measured whether clinical and sociodemographic variables were associated with nutritional risk diagnosed by the researcher. The study included 171 patients, of which 59.1% were females. The mean age of the sample was 51.7 ± 15.3 years. A considerable percentage of patients (47.9%, n=82) could not screen themselves, returning the self-screening form in blank or incomplete mainly because of low education level. The mean self-reported weight (68.4 ± 15.0 Kg) was similar to the weight measured by a dietician (68.2 ± 15.1 kg). A similar result was obtained for height as the self-reported and measured heights differed by 0.03 cm. Self-assessed and professionally assessed nutritional risk agreed in 91.9% of the cases, and 26.9% of the patients considered not at risk by the professional were considered at risk according to their self-assessment.According to the Kappa coefficient, the two diagnoses had moderate agreement (k=0.62; p=0.001). The agreements between self-reported and measured weight and height according to the Bland &Altman test were good, with a bias close to zero. Generally, self-screening for clinical practice was considered satisfactory. However, since only 52.1% of the samplemanaged to answer the instrument, its use byhealth care facilities that cater to individuals with low education level is not yet viable, suggesting that new self-screening studies and adaptations are needed.
10

Etude de systèmes et scénarios électronucléaires double strate de transmutation des actinides mineurs en ADS / Study of nuclear energy systems and double strata scenarios for minor actinides transmutation in ADS

Clavel, Jean-Baptiste 30 November 2012 (has links)
La loi française du 28 juin 2006, sur la gestion des déchets radioactifs, demande une évaluation pour définir la future stratégie industrielle. L’étude présentée ici, concerne plus spécifiquement l’axe de recherche sur la transmutation des actinides mineurs. Dans ce but, un concept d’ADS (Accelerator DrivenSystem) de haute puissance a été développé à SUBATECH. Dans ce réacteur sous-critique, un faisceau de protons de 1 GeV alimente trois cibles de spallation de plomb-bismuth. L’ADS MUST (MUltipleSpallation Target) peut ainsi atteindre une puissance thermique de plus de 1 GW avec une densité de puissance élevée. Une méthode de dimensionnement de ces réacteurs a été développée et appliquée pour différents scénarios double strate. Dans ces scénarios, des réacteurs électrogènes de type SFR (Sodium Fast Reactors) ou REP (Réacteurs à Eau Pressurisée) produisent des actinides mineurs destinés à être transmutés en ADS. Dans chaque cœur, un multi-recyclage du plutonium est réalisé et dans les réacteurs sous-critiques les éléments à transmuter le sont également. Pour limiter la réactivité du cœur et améliorer la conductivité thermique, le combustible contenant les actinides mineurs est mélangé à une matrice inerte de MgO. Des filières, avec des ADS à caloporteurs plomb et sodium, ont été étudiées pour différentes durées d’irradiation, et deux stratégies de transmutation : soit l’ensemble des actinides mineurs, soit seulement l’américium est incinéré. Le dimensionnement des ADS MUST de chaque filière et de leur combustible à l’équilibre est présenté dans cette thèse. Puis l’évolution du combustible et du coefficient de multiplication, sur un cycle, est réalisée et analysée. La radiotoxicité et la puissance thermique des déchets produits sont ensuite comparées. Enfin, l’étude de scénarios double strate est effectué afin d’analyser les inventaires d’actinides mineurs et de plutonium en cycle, ainsi que les déchets produits en fonction de la stratégie de transmutation adoptées et de l’évolution de la première strate. / The French law of 28th June 2006 regarding advanced nuclear waste management requires a scientific assessment to define future industrial strategies. The present PhD thesis was carried in this framework and concerns specifically the research axis of minoractinides transmutation. A high power Accelerator Driven System (ADS) concept is developed at SUBATECH for this purpose. A 1 GeV proton beam feeds three liquid lead-bismuth spallation targets. The MUltiple Spallation Target (MUST) ADS reaches the thermal powers up to 1 GW with a high specific power. A nuclear reactor dimensioning method has been developed and applied to different double strata scenarios. In these scenarios, SFR (Sodium FastReactors) or PWR (Pressurized Water Reactors) power reactors produce minor actinides that will be transmuted into ADS. In each core (SFR and ADS), the plutonium multi-reprocessing strategy is performed while ADS subcritical core also multi-reprocesses minor actinides. To limit the core reactivity and improve the fuel thermal conductivity, the minor actinides fuel is mixed with MgO inert matrix. Nuclear branches with lead and sodium coolants for the ADS, have been studied for different irradiation times and two transmutation strategies have been assessed : whether whole minor actinides, whether americium only is tranmuted. The thesis presents precisely the MUST ADS design methodology and the calculations to get a fuel composition at equilibrium. Then a one cycle evolution is performed and analysed for the fuel and the multiplication factor. Radiotoxicity and thermal power of the waste produced are then compared. Finally, the study of double strata scenarios is performed to analyse the plutonium and minor actinides inventories in cycle and also the waste produced according to the transmutation strategies applied and the first stratum evolution.

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