Water is a major component of living organisms, which can be 70-85% of the weight of cells. For this reason, water is a main target of ionizing radiations and plays a central role in radiobiology. Heavy ions, electrons and photons interact with water molecules; mainly by ionization and excitation. Neutrons interact with water molecules by elastic interactions, which generate recoil ions that will create ionizations and excitations in water molecules. These fast events (~10[superscript -12] s) lead to the formation of Reactive Oxygen Species (ROS). The ROS, in particular the hydroxyl radical (¨OH), interact with neighbour molecules such as proteins, lipids and nucleic acids by chemical interaction. Microbeams can irradiate selectively either the external membrane, the cytoplasm and the cell nucleus. These studies have shown that cell survival is greatly reduced when the nucleus is irradiated, but that this is not the case when cytoplasm or cell membrane is irradiated. Thus, DNA is a very sensitive site to ionizing radiation and ROS. For this reason, DNA has long been considered the most important molecule to explain radiobiological effects such as cell death. However, this concept has been challenged recently by new experimental results that have shown that cells which have not been directly in contact with radiation are also affected. This is called the bystander effect. Further studies have shown that a group of cells and their environment reacts collectively to radiation. A hypothesis put forward to explain this radiobiological phenomenon is that a irradiated cell will secrete signalling molecules that will affect non-irradiated cells. The implicated phenomenon and molecules are poorly understood at this moment. The purpose of this work is to improve our comprehension of the phenomenon in the microsecond that follows the irradiation. To these ends, a new Monte-Carlo simulation program of water radiolysis by photons has been generated. For photons of energy <2 MeV, they interact with water mainly by Compton and photoelectric effects, which create energetic electrons in water. The created electrons are then followed by our existing programs to simulate the radiolysis of water by photons. Similarly, a new code has been built to simulate the neutrons interaction with water. This code simulates the elastic collisions of a neutron with water molecules and calculates the number and energy of recoil protons and oxygen ions. The main part of this Ph.D. work was the generation of a non-homogeneous Monte-Carlo Step-By-Step (SBS) simulation code of non-homogeneous radiation chemistry. This new program has been used successfully to simulate radiolysis of water by ions of various LET, pH, ion types ([superscript 1]H[superscript +], [superscript 4]He[superscript 2+], [superscript 12]C[superscript 6+]) and temperature. The program has also been used to simulate the dose-rate effect and the Fricke and Ceric dosimeters. More complex systems (glycine, polymer gels and HCN) have also been simulated.

We study Seifert surfaces for links, and in particular the Kakimizu complex MS(L) of a link L, which is a simplicial complex that records the structure of the set of taut Seifert surfaces for L. First we study a connection between the reduced Alexander polynomial of a link and the uniqueness of taut Seifert surfaces. Specifically, we reprove and extend a particular case of a result of Juhasz, using very different methods, showing that if a non-split homogeneous link has a reduced Alexander polynomial whose constant term has modulus at most 3 then the link has a unique incompressible Seifert surface. More generally we see that this constant term controls the structure of any non-split homogeneous link. Next we give a complete proof of results stated by Hirasawa and Sakuma, describing explicitly the Kakimizu complex of any non-split, prime, special alternating link. We then calculate the form of the Kakimizu complex of a connected sum of two non-fibred links in terms of the Kakimizu complex of each of the two links. This has previously been done by Kakimizu when one of the two links is fibred. Finally, we address the question of when the Kakimizu complex is locally infinite. We show that if all the taut Seifert surfaces are connected then MS(L) can only be locally infinite when L is a satellite of a torus knot, a cable knot or a connected sum. Additionally we give examples of knots that exhibit this behaviour. We finish by showing that this picture is not complete when disconnected taut Seifert surfaces exist.

This research is divided into three major parts. In part I, the critical supersaturations required for the homogeneous nucleation of 2,2,2-trifluorothanol (TFE) vapor have been measured over a temperature range (266-296 K) using an upward thermal diffusion cloud chamber (DCC). The measured supersaturations are in agreement with the predictions of both the classical and the scaled theory of nucleation. Moreover, the condensation of supersaturated TFE vapor on laser-vaporized magnesium nanoparticles has been studied under different experimental conditions, such as the supersaturation, the pressure and the electric field. In part II, the laser vaporization controlled condensation (LVCC) technique was used to prepare Au-Ag alloy nanoparticles in the vapor phase using designed targets of compressed Au and Ag micron-sized powder mixtures of selected composition. The results showed that the optical properties of these nanoparticles could be tuned depending on the alloy composition and the laser wavelength. Different intermetallic nanoparticles (FeAl and NiAl) from the vapor phase has also been prepared, using the same approach.In this work, the fraction of the charged particles generated during the laser vaporization process was used to prepare a new class of nanoparticle assemblies in the LVCC chamber under the influence of an electric field. The results showed that the electric field required to induce the formation of these nanoassemblies is material and field dependent. By coupling the LVCC chamber with the differential mobility analyzer, size-selected nanoparticles have been prepared in the vapor phase. The prepared nanoparticles were characterized by different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible spectroscopy. In part III, new methods were developed to prepare nanoparticle-polymer composites from the vapor phase. In the first method, the LVCC method was used to prepare a carbonaceous cross-linked resin, with different nanoparticles (Ni, Pt and FeAl) embedded inside. In the second method, free radical-thermally initiated polymerization was used to polymerize a monomer vapor of styrene on the surfaces of activated Ni nanoparticles.

A mild gasification method has been developed to provide an innovative clean coal technology. The objective of this study is to developed a numerical model to investigate the thermal-flow and gasification process inside a specially designed fluidized-bed mild gasifier using the commercial CFD solver ANSYS/FLUENT. Eulerain-Eulerian method is employed to calculate both the primary phase (air) and secondary phase (coal particles). The Navier-Stokes equations and seven species transport equations are solved with three heterogeneous (gas-solid), two homogeneous (gas-gas) global gasification reactions. Development of the model starts from simulating single-phase turbulent flow and heat transfer to understand the thermal-flow behavior followed by five global gasification reactions, progressively with adding one equation at a time. Finally, the particles are introduced with heterogeneous reactions. The simulation model has been successfully developed. The results are reasonable but require future experimental data for verification.

L’avènement de l’ère digitale a changé la façon dont les individus communiquent à travers le monde, et a amené de nouvelles problématiques en terme de vie privée. La notion d’anonymat la plus répandue pour les communications sur Internet consiste à empêcher tout acteur du réseau de connaître à la fois l’expéditeur d’un message et son destinataire. Bien que ce niveau de protection soit adéquat pour l’utilisateur d’Internet moyen, il est insuffisant lorsqu’un individu peut être condamné pour le simple envoi de documents à une tierce partie. C’est le cas en particulier des lanceurs d’alerte, prenant des risques personnels pour informer le public de pratiques illégales ou antidémocratiques menées par de grandes organisations. Dans cette thèse, nous envisageons un niveau d’anonymat plus fort, où l’objectif est de dissimuler le fait même qu’un utilisateur envoie ou reçoive des données. Pour cela, nous délaissons l’architecture client-serveur couramment utilisée dans les réseaux anonymes, en faveur d’une architecture entièrement distribuée et homogène, où chaque utilisateur remplit également le rôle de serveur relai, lui permettant de dissimuler son propre trafic dans celui qu’il relai pour les autres. Dans cette optique, nous proposons un nouveau protocole pour les communications pairs à pairs sur Internet. À l’aide de récents outils de preuves cryptographiques, nous prouvons que ce protocole réalise les propriétés d’anonymat désirées. De plus, nous montrons par une étude pratique que, bien que le protocole induise une grande latence dans les communications, il assure un fort anonymat, même pour des réseaux de petite taille. / With the development of online communications in the past decades, new privacy concerns have emerged. A lot of research effort have been focusing on concealing relationships in Internet communications. However, most works do not prevent particular network actors from learning the original sender or the intended receiver of a communication. While this level of privacy is satisfactory for the common citizen, it is insufficient in contexts where individuals can be convicted for the mere sending of documents to a third party. This is the case for so-called whistle-blowers, who take personal risks to alert the public of anti-democratic or illegal actions performed by large organisations. In this thesis, we consider a stronger notion of anonymity for peer-to-peer communications on the Internet, and aim at concealing the very fact that users take part in communications. To this end, we deviate from the traditional client-server architecture endorsed by most existing anonymous networks, in favor of a homogeneous, fully distributed architecture in which every user also acts as a relay server, allowing it to conceal its own traffic in the traffic it relays for others. In this setting, we design an Internet overlay inspired from previous works, that also proposes new privacy-enhancing mechanisms, such as the use of relationship pseudonyms for managing identities. We formally prove with state-of-the-art cryptographic proof frameworks that this protocol achieves our privacy goals. Furthermore, a practical study of the protocol shows that it introduces high latency in the delivery of messages, but ensures a high anonymity level even for networks of small size.

Au cours des dernières décennies, les produits pharmaceutiques sont devenus une nouvelle préoccupation environnementale. Les produits pharmaceutiques ont été largement détectés dans les eaux souterraines, les eaux de surface et même dans l'eau de boisson, avec une concentration allant du ng au µg L-1 dans les effluents d'eaux usées. Les stations d’épuration ne peuvent pas éliminer complètement tous les produits pharmaceutiques en raison de leur faible concentration dans l’eau et de leur résistance à la dégradation biologique. Dans les procédés d’oxydation avancée (AOP), les méthodes les plus fréquemment utilisées incluent les réactions homogènes telles que le procédé de Fenton, de type Fenton ou le procédé Photo-Fenton.Dans ce travail, un nouveau catalyseur composite BiOCl0,75I0,25 a été synthétisé par méthode de précipitation sous pression ambiante et à basse température, suivie d'une série de caractérisations. De plus, les capacités d'adsorption et de dégradation photocatalytique du catalyseur dans l'eau ont été testées sous une lumière solaire simulée en utilisant deux polluants chimiques (Acétaminophène, acide p-hydroxyphénylacétique). / In recent decades, pharmaceuticals and personal care products (PPCPs) have emerged as a new environmental concern. Pharmaceuticals have been widely detected in ground water, surface water and even drinking water with a concentration ranging from ng to µg L-1 in wastewater effluents. Sewage treatment plants (STPs) cannot remove completely all pharmaceuticals due to their low concentration in water and resistance to biological degradation. In AOPs, the most frequently used methods include homogeneous reaction such as Fenton, Fenton like or Photo-Fenton process. In this work, composite catalyst BiOCl0.75I0.25 was synthesized by precipitation method under ambient pressure and low temperature followed with a series of characterization. Moreover, the adsorption and photocatalytic degradation abilities of new bismuth catalyst in water are tested under simulated solar light using Acetaminophen, p-hydroxyphenylacetic acid and as chemical pollutant.

A agricultura no Brasil vem se destacando ao longo dos anos como uma das principais atividades econômicas do país. A grande extensão em área, o clima favorável, os investimentos em pesquisa e o aumento da população mundial, vem auxiliando o Brasil a se destacar como celeiro mundial. O grande desafio, portanto, para uma agricultura sustentável é produzir mais sem desmatar os fragmentos ainda existentes de mata original. Para isso, uma das linhas de pesquisa que apresenta grande perspectiva de desenvolvimento é a de pesquisa do uso de fertilizantes que possam promover um suprimento eficiente das exigências nutricionais das plantas respeitando a atual exigência de proteção ao meio-ambiente. Este trabalho apresenta uma metodologia de preparação de óxidos de zinco e manganês hidratados para serem utilizados em formulações de adubos foliares. Utilizou-se para isto o método de precipitação em solução homogênea utilizando o experimento fatorial fracionado saturado Placket - Burman como ferramenta de trabalho. Inicialmente estudou-se a influência de fatores como: tipo de agente precipitante, rotação do agitador mecânico, excesso do agente precipitante e ordem de adição dos reagentes, pois influenciam diretamente na precipitação dos compostos. Estudou-se a distribuição do tamanho das partículas geradas, tomando esta variável resposta como parâmetro para a otimização da metodologia de síntese. Com os resultados obtidos pelo Planejamento Placket - Burman observou-se que o fator excesso de agente precipitante pouco influenciou na variável resposta. A partir dos fatores que mais influenciaram, montou-se nova matriz, agora com planejamento fatorial completo 23. Os fatores que mais influenciaram a variável resposta foram o tipo do agente precipitante, a ordem de adição dos reagentes e rotação do agitador mecânico. Observou-se portanto, com auxilio dos efeitos, a importância de cada fator na variável resposta. Os materiais obtidos foram caracterizados, por meio de difração de raios-X (DRX), analise térmica (TG), espectroscopia de infra-vermelho com transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV) e espectrofotometria de absorção atômica por chama (AAS). A distribuição do tamanho de partículas foi de 17,01 &#956;m para o hidroxicarbonato de zinco e 5,32 &#956;m para o carbonato de manganês. O hidroxicarbonato de zinco apresentou um teor de zinco em torno de 54,0 %, e, nesta matriz experimental, foi possível chegar a um modelo com bom ajuste para esta síntese. O carbonato de manganês, por sua vez, apresentou as um teor de Manganês em torno de 44,0 % e características adequadas de granulometria para ser utilizado como adubo foliar. / The agriculture in Brazil has been standing out throughout the years as one of the main economical activities of the country. The great extension of the area, the favorable climate, the investments in research and the increase of the world population, has been assisting Brazil to stand out as a world barn. The great challenge, therefore, to a supportable agriculture is to produce more without deforesting the fragments still existing of original forest. That is, one of the methods of research which presents great perspective of development is the research of the use of fertilizer which can promote an efficient supply of the plants nutritional demanding respecting the current environmental protection demand. This work presents a methodology of mustered zinc and manganese oxide preparation to be used in formulations of leaf fertilizer. It was used for it, the precipitation in homogeneous solution method, using the fractioned factorial saturated experiment Packet-Burman as a work tool. Initially, it was studied the influence of the factors as: the type of precipitant agent, rotation of the mechanical shaker, excess of precipitant agent and the order of the addictions of the agents, for they influence directly in the compounds precipitation. It was studied the distribution of the size of the generated particles, taking this changeable response as a standard to a optimizing of the synthesis methodology. With the results obtained by the Planning Placket-Burman it was observed that the factor precipitant agent excess has little influenced the changeable response. From the factors on which most influenced them, it was set a new nuance up, now with a completed factorial planning 2.The factors which more influenced the changeable response were the type of precipitant agent, the order of reagent addiction and the rotation of the mechanic shaker. It was observed, therefore, with the help of the effects, the importance of each factor in the changeable response. The materials obtained were characterized, through the X-Ray diffraction(XRD), thermal analysis(TG), spectroscopy of infrared with transformed of Fourier(FTIR), eletronic microscopy with sweeping (MEV) and espectrophotometry of atomic absortion by flame (ASS). The distribution of the size of particles was 17,01 &#956;m to the hidroxicarbonate of zinc and 5,32 &#956;m to the carbonate of manganese. The hydroxicarbonate of Zinc has presented a level of Zinc around 54,0% and, in this experimental matrix, it was possible to get to a model with a good tunning for this synthesis. The manganese carbonate, on the other hand, has presented a level of manganese around 44,0% and adequate characteristics of particle sizes for being used as foliar fertilizer.

O efluente lácteo é o resíduo obtido no beneficiamento do leite e seus derivados, sendo considerado um passivo de alto poder poluidor. Sem o devido tratamento, quando lançado nos rios compromete a sobrevivência da biota como um todo. O objetivo deste trabalho consistiu em avaliar a eficiência e aplicação do processo Foto-Fenton, seguido por um tratamento biológico (lodo ativado), para a redução da carga orgânica do efluente em questão. A caracterização do efluente lácteo in natura e tratado foi realizada empregando-se métodos estabelecidos e otimizados [DQO, COT, DBO5, Nitrogênio (orgânico e amoniacal), Fósforo total, Ferro, e Sólidos (ST, STF, STV), fenol, análise de elementos via absorção atômica]. Por meio de planejamentos estatísticos - Taguchi, Box-Behnken e fatorial completo - foram determinados os melhores experimentos posteriores aos tratamentos fotocatalíticos e biológico, tendo como variável resposta a redução percentual de COT. Após o processo fotocatalítico, a amostra do melhor experimento foi tratada por um processo biológico (Sistema Lodo Ativado SLA), a fim de verificar a eficiência de degradação da matéria orgânica do efluente estudado através do sistema conjugado (POA- SLA). O sistema híbrido que apresentou maior eficiência teve como variáveis do processo de tratamento fotoquímico: pH = 3,5; Temperatura = 30 ºC; reagente Fenton ( 35 g H2O2 + 3,6 g Fe2+ ) e potência de radiação ultravioleta de 28 W, para um tempo de reação de 60 minutos. Para o tratamento biológico por lodo ativado, os melhores níveis das variáveis foram realizados em pH = 8 e concentração de lodo de 3,0 g L-1. Os resultados para o tratamento híbrido apresentou percentuais de reduções para COT = 94 %, DQO = 97 % e DBO = 83 %. / The dairy effluent is the residue obtained from the improvement of milk and its derivatives, being considered a high pollutant. Without the due treatment, when thrown in the rivers it puts in risk the survival of the biota as a whole. The objective of this work consisted of evaluating the efficiency and application of the process photo-Fenton followed by a biological (activated sludge) treatment for the reduction of the organic load of the effluent. The characterization of the dairy effluent in natura and treated was accomplished using established methods [COD, TOC, BOD5, Nitrogen (organic and amoniacal), Total Phosphorus, Iron, and Solids (TS, FTS, VTS), phenol, analysis of elements through atomic absorption]. Through statistical designs, Taguchi, Box-Behnken and Full Factorial, the best experiments were determined for the photocatalytic and biological treatments having the reduction of TOC as their response. After the photocatalytic process, the sample of the best experiment was treated by a biological process in order to verify the efficiency of degradation of the organic matter of the effluent studied through the conjugated (AOP - AS) system. The hybrid system that presented larger efficiency had as factors of the photochemical treatment: pH = 3,5, temperature = 30 ºC, Fenton\'s reagent (35g H2O2 + 3,6 g Fe2+) and potency of ultraviolet radiation of 28 W, for 60 minutes of reaction time. As for the biological treatment, it was accomplished in pH = 8 and concentration of sludge of 3g L-1. Obtained were of the hybrid system the percentage of reductions of TOC = 94 %, COD = 97 % and BOD = 83 %.

Submitted by admin tede (tede@pucgoias.edu.br) on 2017-08-21T12:30:58Z No. of bitstreams: 1 Celso Aurélio de Morais Lima.pdf: 2546394 bytes, checksum: 8a8908066e6f60ae202da67d1738b90d (MD5) / Made available in DSpace on 2017-08-21T12:30:58Z (GMT). No. of bitstreams: 1 Celso Aurélio de Morais Lima.pdf: 2546394 bytes, checksum: 8a8908066e6f60ae202da67d1738b90d (MD5) Previous issue date: 2017-04-27 / The main objective of this dissertation is to develop a reliability assessment applied to reparable systems in the sugar and alcohol industry. The work has a quantitative approach with a combined research method: simulation modeling with case-study. Therefore, a dynamic modeling is used to develop a case-study. For this, a Non- Homogeneous Markov Process (PNHM) model is used to represent the states transitions (operation-maintenance) of sugar centrifuges, in order to obtain reliability indicators. Integrated to the PNHM model, it will be used the Generalized Renewal Process (PRG) to describe the probabilities of failures considering imperfect repairs. The PRG is defined according to the parameters of scale, shape and rejuvenation (α, β, q), which are estimated by Bayesian Inference. In the development of the case-study, the data collection of centrifugal failures was performed and, through the simulation of the hybrid model, the case-study was conceived. The estimated availability for 5640 hours was 93.23%, whose the other 7% represents maintenances moments. For 323 hours of simulation, the reliability resulting was 50%, demonstrating high system susceptibility to failures. The results suggest the revisions of the intervals defined for preventives maintenances, which should be applied to the most observed failure mode, called malfunction of the sensing systems. / O principal objetivo desta dissertação é desenvolver uma avaliação de confiabilidade aplicada a sistemas reparáveis, na indústria sucroalcooleira. O trabalho possui abordagem quantitativa com método de pesquisa combinado: modelagem de simulação com estudo de caso. Portanto, utilizar-se-á de uma modelagem dinâmica para desenvolver um estudo de caso. Para isso, aplicar-se-á um modelo de Processos Não Homogêneos de Markov (PNHM) para representar as transições entre estados (operacional-em manutenção) das centrífugas de açúcar, visando obter indicadores de confiabilidade. Integrado ao modelo PNHM, será utilizado o Processo de Renovação Generalizado (PRG) para descrever as probabilidades de falhas considerando reparos imperfeitos. O PRG é definido em função dos parâmetros de escala, forma e rejuvenescimento ( ,!,"), que serão estimados via Inferência Bayesiana. No desenvolvimento do estudo de caso, realizou-se a coleta de dados de falhas das centrífugas e, por meio da simulação do modelo híbrido, o estudo de caso foi concebido. A disponibilidade estimada para 5640 horas foi de 93,23%, sendo os 7% complementares referentes a manutenções. A confiabilidade apresentada foi de 50% para 323 horas, demonstrando alta suscetibilidade do sistema à falhas. Os resultados sugerem revisão nos intervalos definidos para manutenção preventiva, as quais deverão ser dedicadas ao modo de falha mais observado, denominado mal funcionamento dos sistemas de sensoreamento.

The power of the McCumber theory [D. E. McCumber, Phys. Rev. 136, A954-957 (1964)] consists in its ability to accurately predict emission cross section spectra from measured absorption, and vice versa, including both absolute values and spectral shapes. While several other theories only allow the determination of integrated cross sections, the McCumber theory is unique in generating the spectral shape of a cross section without any direct measurements regarding that cross section. The present work is a detailed study of the range of validity of the McCumber theory, focussing particularly on those aspects that most critically affect its applicability to transitions of rare earth ions in glasses. To analyze the effect of the spectral broadening on the accuracy of the technique, experiments were performed at room and low temperature. The theory was tested by comparing the cross sections calculated using the McCumber relation with those obtained from measurements. At room temperature, a number of ground state transitions of three different rare earth ions (Nd, Er and Tm) in oxide and fluoride glass hosts have been studied. Special attention was paid to the consistency of the measurements, using the same experimental setup, same settings and same detection system for both absorption and fluorescence measurements. Other aspects of the experimental procedure that could generate systematic errors, like fluorescence reabsorption and baseline subtraction uncertainties in the absorption measurements, were carefully investigated. When all these aspects are properly accounted for, we find in all cases an excellent agreement between the calculated and the measured cross section spectra. This suggests that the McCumber theory is not limited to crystalinne hosts, but describes quite well the reciprocity between emission and absorption for the broader transitions of rare earths in glassy hosts. This good agreement does not hold, however, for the low temperature results. The distortion observed in this case follows the theoretically predicted behavior, and corresponds to the amplification of the gaussian wings that describes the inhomogeneous type of broadening. Our results suggest that the McCumber theory must be used with caution for temperatures below 200 K.