Interactions of colloidal particles with surfaces occur in natural and engineered systems, and they influence the transport of contaminants through diffusion, aggregation, filtration, and sedimentation. To quantify the transport and fate of colloidal particles and their influence on environmental systems, it is important to understand their interactions with surfaces. These interactions are influenced by physical and chemical surface properties such as hydrophobicity, charge density, and roughness, as well as environmental conditions such as relative humidity (RH). In atmospheric systems, RH induces the capillary force and also influences the contributions of van der Waals and electrostatic forces. To investigate the role of surface properties and RH in the interaction of colloidal particles with surfaces, atomic force microscopy was employed to measure the adhesion and friction forces of colloidal particles including Bacillus thuringiensis spores, silica, and gold at various experimental conditions with several types of surfaces including mica, silica, and radioactive gold. Contributions to the adhesion force by van der Waals, capillary, and electrostatic forces were theoretically calculated and compared to measured forces. Through experimental results and theoretical studies, it was identified how surface properties of interacting surfaces and experimental conditions influence the interfacial interactions of colloidal particles in atmospheric systems. The role of RH in adhesion and friction depends on the hydrophobicity or contact angles of interacting surfaces and surface roughness. Relative humidity also influences the contribution of electrostatic force to the total adhesion force by screening the strength of surface potential or providing a passage for charge leakage. The results of this thesis provide a better understanding of particulate processes that are influenced by the interactions of colloidal particles with surfaces and can be useful in monitoring and control of contamination in atmospheric systems.

Nuclear safety is the main concern for the licensing of nuclear power plants, not only in the Republic of South Africa but also worldwide. The design of the nuclear power plant plays an important role in the licensing process, which includes probabilistic and deterministic analysis of a set of design or Licensing basis events. This study was about the deterministic analysis for the sensitivity of licensing basis events radiological consequences to different radiological pathways. The study was done for the Pebble Bed Modular Reactor (PBMR), which is a nuclear power plant, still in its early phase of design approaching its detailed design phase. An abnormal event or an accident could lead to a release of radioactive particles and gases from a Pebble Bed Modular Reactor and could give rise to radiation exposure to workers and the surrounding population. Therefore nuclear events due to PBMR, which are Licensing Basis Events or Design Basis Accidents, must be analysed in order to demonstrate that accidental and routine releases of radioactivity are kept As Low As Reasonably Achievable (ALARA) and that the design basis meets offsite dose requirements with adequate safety margins. In this work, it is also shown that collectively the risk criteria are satisfied in the fundamental safety requirements of National Nuclear Regulator (NNR) of the Republic of South Africa (RSA) and similar risk criteria of the other countries in which it has to be employed. Furthermore the various pathways through which radioactivity can reach the public are analysed. The focus of the study was to determine which pathways deliver the greatest radiation exposure if there is an accident due to an event happening in PBMR and also to provide a LBE analysis process as a step in confirming that the design meets the licensing requirements. / Thesis (M.Sc. ARST) North-West University, 2004

The quantal Boltzmann&ndash / Langevin equation is used to obtain a dispersion relation for the growth rates of instabilities in infinite nuclear matter. The dispersion relation is solved numerically for three different potentials. The quantal results are compared with the semi-classical solutions. It is seen that with the inclusion of the quantal effects the growth rates of the fastest growing modes in the system are reduced and these modes have the tendency to occur at longer wavelengths for all the potentials considered. Furthermore, the boundaries of the spinodal region is determined by the phase diagrams using the same three potentials and it is observed that the expanding nuclear matter undergoes liquid-gas phase transition at reduced temperatures when the quantum effects are included.

Leptonic decay modes of Z-boson constitute one of the important class of the decays for checking predictions and improving parameters of the standard model. In next generation of the accelerators, it will be produced more than 10^8 Z-boson pear year. Therefore, It appears real possibility to analyze the rare decays of Z, which are absent at tree level in standard model. Moreover, the rare decays are quite sensitive to the existence of new physics beyond the standard model. One of the possible source for the new physics is noncommutative theories (NC). Noncommutative theories have rich phenomenological implications due to the appearance of new interactions, which are forbidden in standard model. In this thesis, we examine the Z $rightarrow nu bar{nu} gamma$ decay in noncommutative standard model. We study the sensitivity of the decay width on the noncommutative scale parameter Lambda and parameters $C_{0i}$ and $C_{ij}$, which defines the direction of background electric and magnetic fields.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

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Agradecemos a compreensão. on 2016-05-18T14:27:24Z (GMT) / Submitted by JULIANA APARECIDA GALHARDI null (julianagalhardi@yahoo.com.br) on 2016-05-18T14:31:46Z No. of bitstreams: 1 Tese_Doutorado_JulianaAparecidaGalhardi_GMA2.pdf: 7291998 bytes, checksum: e20e8ae35419de9453e2aac0d008f1fe (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-05-18T16:45:06Z (GMT) No. of bitstreams: 1 galhardi_ja_dr_rcla.pdf: 7291998 bytes, checksum: e20e8ae35419de9453e2aac0d008f1fe (MD5) / Made available in DSpace on 2016-05-18T16:45:06Z (GMT). No. of bitstreams: 1 galhardi_ja_dr_rcla.pdf: 7291998 bytes, checksum: e20e8ae35419de9453e2aac0d008f1fe (MD5) Previous issue date: 2016-04-06 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O carvão mineral representa a maior fonte de combustível não renovável no Brasil para geração de energia elétrica. Em Figueira, Paraná, o carvão extraído pela Companhia Carbonífera do Cambuí abastece a termelétrica do município e faz parte da maior reserva ainda em exploração no estado, tendo sido lá registrada a ocorrência anômala de urânio. Para a avaliação de impactos radiológicos associados às atividades de extração, beneficiamento e queima do carvão mineral na área, foi realizada uma avaliação da composição das águas e solos amostrados na área em termos químicos e radiométricos, além do uso de organismos como biomonitores para a verificação dos níveis de contaminação atmosférica e dos solos. Por meio das análises, realizadas no Laboratório de Isótopos e Hidroquímica - Unesp, Rio Claro, Brasil, e no Laboratório de Física Nuclear Aplicada - Universidade de Sevilha, Sevilha, Espanha, foi observado que efluentes ácidos são originados a partir da oxidação de minerais de sulfeto e resultam em um acréscimo da taxa de solubilização de radionuclídeos nas águas subterrâneas e superficiais da região. À jusante da área da mineração, o pH nas águas dos rios foi mais ácido e o teor de algumas espécies químicas mais elevado, o que pode ser devido à descarga de efluentes ácidos provenientes da mineração. O mesmo comportamento foi verificado para os solos. Nas águas subterrâneas, as concentrações de atividade dos radionuclídeos foram notavelmente mais elevadas nas áreas de processamento do carvão, de disposição dos rejeitos e à jusante da planta da mina. Por meio do biomonitoramento, a eficácia de algumas espécies de líquens e musgos como bioindicadores da qualidade do ar em áreas afetadas por mina de carvão e termelétrica foi testada e comprovada, sendo que o 210Po foi o radionuclídeo que apresentou as maiores concentrações de atividade nas espécies investigadas. Por meio das razões 234U/238U foi possível verificar a infiltração de efluentes ácidos nas águas subterrâneas, assim como uma contribuição das cinzas lançadas pela termelétrica para o conteúdo dos radionuclídeos nos solos, sedimentos e também para os líquens, musgos, soja e trigo. O transporte dos radionuclídeos reflete a importância do monitoramento da concentração de suas atividades nas águas naturais, solos e na biota, devido aos riscos que a radioatividade pode representar para a saúde humana. / Coal represents the largest source of non-renewable fuels in Brazil for electric power generation. In the city of Figueira, Paraná State, the coal extracted by Cambuí Company supplies the thermal power plant in the city and is part of the largest reserve that is nowadays being exploited in the area, where it was registered anomalous occurrence of uranium. For the evaluation of radiological impacts associated with the extraction, processing and burning of coal in the area, it was carried out an investigation of the water and soil chemical and radiological composition and some organisms were evaluated as biomonitors for the investigation of the air and soil pollution. Through the analysis, carried out in the Laboratório de Isótopos e Hidroquímica - Unesp, Rio Claro, Brazil, and Laboratorio de Física Nuclear Aplicada - Universidad de Sevilla, Spain, it was observed that acid effluents are generated from the oxidation of sulfide minerals and can result in an increase in the solubilization rate of radionuclides, enhancing the possibility of groundwater and soil contamination at levels of difficult treatment and recovery. Downstream of the mining area, the pH in the rivers waters was more acidic and the content of some chemical species was higher, probably due to the discharge of acid effluent from the mine. The same behavior was observed for the soils. In groundwater, the radionuclides activity concentrations were significantly higher in the areas of the coal industrial processing and in the tailings pile and downstream of the mine. Through the biomonitoring, the efficiency of some species of lichens and mosses as bioindicators of the air quality in areas affected by coal mine and thermal power plant has been tested and proven. 210Po was the radionuclide that showed the highest activity concentration in the investigated species. Through the 234U/ 238U rates it was observed the infiltration of acidic effluents into the groundwater, as well as a contribution of the fly ashes from the thermal plant for the radionuclides content in soils, sediments and also in lichens, mosses, soybeans and wheat. The radionuclides transport reflects the importance of monitoring the concentration of its activities in natural waters, soil and also in the biota due to the risks that radioactivity can represents to human health.

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La miniaturisation croissante des transistors MOS a rendu les mémoires RAM de plus en plus sensibles aux particules alpha émises par les éléments radioactifs naturellement présents dans les matériaux utilisés dans la fabrication de ces mémoires. En effet, au niveau du sol, le taux d'erreurs logiques déclenchées par ces particules est comparable à celui déclenché par les neutrons issus du rayonnement cosmique. L'objectif principal de ce travail de thèse est la mise au point de méthodes d'évaluation de ce taux et permettre par la suite de proposer des solutions technologiques. Ainsi, dans le cadre d'une approche théorique, nous avons développé des modèles permettant d'évaluer le taux des erreurs logiques déclenchées par les chaines de l'uranium et du thorium dans un état d'équilibre séculaire mais aussi de déséquilibre. Ceci passe par une identification des radioéléments critiques, c'est-à-dire ceux qui sont capables d'augmenter l'émissivité (et ainsi le taux d'erreurs d'aléas logiques) à des niveaux inacceptables pendant la durée de vie du composant. La prise en compte de l'état de déséquilibre des chaines de désintégration radioactive dans ce volet théorique permet une approche réaliste de la contamination. Nous avons également proposé une méthode expérimentale pour analyser l'évolution de l'état radioactif dans les matériaux utilisés dans la fabrication des mémoires. Dans cette approche expérimentale, nous avons combiné trois techniques de mesure complémentaires: la spectroscopie alpha, la spectroscopie gamma et l'ICPMS. / The increasing miniaturisation of MOS transistors has made RAM memories more and more sensitive to alpha particles emitted by radioactive elements naturally present in the materials used for memory fabrication. Indeed, at ground level, the soft error rate triggered by these particles is comparable to that triggered by neutrons from cosmic rays. The main purpose of this work aims to develop methods to evaluate this rate allowing thereafter suggesting technologies mitigations. Thus, in the context of a theoretical approach, we have developed models to estimate soft errors rate triggered by uranium and thorium chains in secular equilibrium but also disequilibrium state. This requires identification of critical radionuclides those are able to increase the emissivity (and thus the soft error rate) to unacceptable levels during device lifetime. Taking into account disequilibrium state of decay chains in theoretical study provides a realistic approach to the contamination. We have also proposed an experimental method to analyze the radioactive state evolution in materials used for memory fabrication. In this experimental approach, we have combined three complementary measurement techniques: alpha spectroscopy, gamma spectroscopy and ICPMS.

Por considerar que o uso das tecnologias de informação e comunicação às práticas pedagógicas, aliadas à abordagem dos assuntos nucleares é tema relevante, desafiador e ainda pouco explorado, o presente projeto visou criar um espaço de reflexões acerca das relações de aprendizagem e o papel do professor em sala de aula no contexto escolar de nível médio. Para o desenvolvimento dessa pesquisa, utilizou-se metodologia qualitativa. Como instrumentos de coleta de dados utilizaram-se gravações de áudio e vídeo, anotações em diários de aula, produções textuais dos sujeitos investigados e arquivos de registro da navegação realizada no ambiente do software educativo. A utilização de recursos digitais e, principalmente, do software educativo Cidade do Átomo, possibilitou a realização do exercício de representações de papéis, cujo objetivo é abordar assuntos científicos e tecnológicos polêmicos, tal como os relacionados à produção de energia elétrica a partir da energia nuclear. Nessa atividade, os estudantes interpretam diversos papéis de um mesmo contexto, defendendo e debatendo os pontos de vista convergentes de seus personagens. Foi possível evidenciar na participação dos estudantes por meio de questionamentos e relações estabelecidas entre seus pares e com os recursos tecnológicos a formação de um ambiente de interação proveitoso. Esta constatação evidencia a potencialidade do espaço educativo formado, que resultou em reforço do processo ensino-aprendizagem. / By considering that the use of information technology and pedagogical practices communication allied with an approach of nuclear subject it’s a relevant, challenging and yet not well developed theme, the present project aimed to create speculative space about the learning relationship and the role of the educator in a middle school context. To the development of this research were used a qualitative methodology. As data collecting instrument were used audio and video recordings, diary class annotations, textual productions of the analyzed subjects and navigation record files of the educational software ambient. Use of digital resources, mainly the educative software “Cidade do Átomo”, enabled the roleplaying game, whose objective is the approach of scientific and technologic polemic subjects, such as the nuclear energy production. In this exercise, the students played various roles on the same context, defending and debating their characters point of view. By the use of questions and discussion of the peer relationship with the technological resource, was possible to bespeak a beneficial interactive environment. This statement endorses the potentiality of the educative space, which resulted in a reinforcement of the teaching-learning process.