The main aim of this thesis is to examine the agenda setting effects of Twitter users by exploring the use of hashtag #UgandaDecides and the retweet (RT) activity during the 2016 presidential election. I do this by applying the first level agenda setting theory which holds that the news media sets the public agenda. I apply a qualitative analysis using #UgandaDecides as a unit of analysis to collect tweets that received the most retweets to establish the actors tweeting during the study period. I conduct content analysis to establish the key issues/topics that received the most attention as per their level of frequency and prominence received through their retweet activity. Results in this thesis show that different actors were involved in determining the topics/issues on the twitter public agenda during the 2016 Uganda presidential election. For the pre-election period, the news media set the agenda by influencing the topics/issues for discussion as seen by the number of the retweets from their tweets. However, on Election Day, the public mainly ordinary citizens were more active in determining what topics/issues were discussed on Twitter, manifesting signs of reverse agenda setting. In this thesis, I thus conclude that Twitter can be empowering as it provides a space for ordinary citizens to participate in political discourse and that in a restrictive media environment, both media and public can use twitter as a participatory platform. The aspects of reversed agenda setting shown in this study are indicative of the changing media environment and how new power relations between different actors calls for the revision of the traditional agenda setting theory that the news media sets the public agenda.

Orientador: Carol Hollingworth Collins / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T17:56:06Z (GMT). No. of bitstreams: 1 Nome_RenataCristiano_D.pdf: 3193413 bytes, checksum: 499dd8e787afa50c91a2295212001ca4 (MD5) Previous issue date: 2014 / Resumo: Este trabalho apresenta o desenvolvimento de fases estacionárias (FE) para utilização em Cromatografia Líquida em Alta Eficiência em Fase Reversa (CLAE-FR) a partir da sorção e imobilização de poli(metiltetradecilsiloxano) (PMTDS) sobre suportes de sílica metalizada com alumínio.O preparo dos suportes de sílica aluminizada e a sorção/imobilização do PMTDS sobre o suporte por tratamentos térmicos foram otimizados com planejamento experimental. Uma reação de capeamento com trimetilclorosilano e hexametildisiloxano foi realizada para o preparo de FE capeadas. Os suportes, bem como as FE capeadas e não capeadas foram caracterizadas por técnicas físico-químicas e cromatográficas. Observou-se que para os suportes a base de sílica aluminizada apresentarem características de suportes adequados para a cromatografia, os mesmos devem ser constantemente agitados por vortex. As FE não capeadas (Si-Al(PMTDS)) submetidas a um planejamento de experimentos foram avaliadas com o objetivo de determinar a temperatura e tempo necessário de imobilização do polímero que resultasse em melhor desempenho cromatográfico. Observou-se que independentemente do modo de imobilização as novas FE apresentam eficiências baixas de aproximadamente 30000 pratos por metro, porém as colunas recheadas apresentam boa separação, com picos simétricos para compostos apolares. A presença de alumínio em novas FE não capeadas (Si-Al(PMTDS) foi confirmada pelo baixo desempenho na separação de compostos básicos, os quais apresentarem alta retentividade. Por outro lado, as FE capeadas (Si-Al(PMTDS)ec) mostraram-se mais adequados para separação de compostos de caráter ácido ou básico, apresentando picos mais simétricos para o composto N,N-dimetilanilina (pKa > 9,0). O aumento da estabilidade química das novas FE ((Si-Al(PMTDS) e Si-Al(PMTDS)ec) a base de sílica modifica com alumínio foi confirmada pelo uso prolongado de fases móveis em condições drásticas de pH (pH < 2,0 e pH > 10,0) quando comparado com FE sem modificação metálica. As novas FE foram testadas na separação de uma ampla série de fármacos (pKa > 9,0) e agrotóxicos e os resultados indicam que podem ser potencialmente utilizadas nestas separações / Abstract: This work describes the development of stationary phases (SP) for Reversed Phase High Performance Liquid Chromatography (RP-HPLC) through sorption and immobilization of poli(methyltetradecylsiloxane) (PMTDS) over silica supports metalized with alumina. The preparation of aluminized silica supports and PMTDS sorption/immobilization by thermal treatment were both optimized by experimental planning. A capping reaction with trimethylchlorosilane and hexamethyldisiloxane was performed to prepare capped SP. Supports, capped SP as well as non capped SP were all characterized by physicochemical and chromatographic techniques. It was observed that constant vortex stirring of the support was necessary to yield aluminized silica-based supports suitable for chromatographic applications. The non capped SP (Si-Al(PMTDS)) were submitted to experimental planning to define the temperature and time needed to immobilize the polymer and to lead to better chromatographic performance. Regardless of the type of immobilization, it was observed that the new SP exhibited low efficiency of approximately 30000 plates per meter. However, the resulting columns exhibited good separation with symmetrical peaks for polar compounds. The presence of aluminum in the non capped SP (Si-Al(PMTDS)) was confirmed by the poor performance in the separation of basic compounds, which exhibited high retention. On the other hand, the capped SP (Si-Al(PMTDS)ec) were more suitable for the separation of acidic or basic compounds, with more symmetric peaks for N,N-dimethylaniline (pKa > 9,0). The increase in chemical stability of the new SP ((Si-Al(PMTDS) and Si-Al(PMTDS)ec) based on aluminized silica was confirmed through the extended use of mobile phases in drastic pH conditions (pH < 2,0 and pH < 10,0) when compared with SP without metalic modification. The new SP were tested for the separation of a wide range of pharmaceutical compounds (pKa > 9,0) and agrochemicals, and the results indicate that the new SP may be potentially used for such separations / Doutorado / Quimica Analitica / Doutora em Ciências

Orientador: Marco Aurélio Cremasco / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-27T20:23:51Z (GMT). No. of bitstreams: 1 Ramos_AlexMartins_D.pdf: 2631980 bytes, checksum: 6ae843a3d8311ad1d248269d9eb22659 (MD5) Previous issue date: 2014 / Resumo: O piperonal é uma molécula de grande valor econômico, pois é utilizado como matéria-prima nas indústrias de cosméticos e de fármacos. Uma das formas de obtenção do piperonal é por meio de síntese cujo substrato é o safrol. O safrol é o principal constituinte químico do óleo essencial de pimenta-longa (Piper hispidinervum, C. DC), espécie que é abundante na região Amazônica. Após os processos de síntese aplicados diretamente no óleo de pimenta longa, obtém-se o piperonal, como produto principal, e os coprodutos safrol, isosafrol glicol, cis-isosafrol, trans-isosafrol e terpinoleno. O rendimento dessa rota sintética é cerca de 84% de piperonal. Por este motivo, e considerando o alto valor agregado ao piperonal é que se propôs separá-lo por cromatografia líquida de alta eficiência (CLAE) com injeção empilhada. Nesse tipo de separação são essenciais as definições de tempo de ciclo e tempo de coleta. Para isso, foram empregadas duas abordagens: a abordagem experimental, na qual o tempo de ciclo e o tempo de coleta foram obtidos diretamente do cromatograma e a abordagem teórica que surgiu em decorrência do modelo proposto nesta Tese, onde os tempos de ciclo e coleta foram obtidos a partir dos parâmetros da curva gaussiana. Para essa última abordagem, são necessárias as constantes de equilíbrio e os parâmetros de transferência de massa (Dp, Def, Ds e Eb), que foram obtidos experimentalmente. Foram empregados três sistemas cromatográficos de separação: o primeiro e segundo foi constituido de fase móvel acetonitrila/água ¿ 70/30 (v/v) a 25 e 35 oC e o terceiro, de fase móvel etanol/água ¿ 70/30 (v/v) a 35 oC, com detecção em 245 nm para todos os sistemas. Utilizou-se coluna analítica de 25 x 0,46 cm e coluna semipreparativa de 25 x 1,0 cm recheadas com fase estacionária C18 cujo tamanho médio de partícula foi 20 ?m. Na coluna analítica foram determinadas a porosidade total e as constantes de equilíbrio do piperonal, safrol, isosafrol e terpinoleno, nas vazões de 0,6 ¿ 1,4 mL.min-1. Na coluna semipreparativa foram determinadas a porosidade total bem como os parâmetros de transferência de massa, nas vazões de 4,0 ¿ 6,0 mL.min-1. Para realização da abordagem teórica, foi preparado uma solução na qual a concentração foi de 0,2 g.L-1. Já na abordagem experimental, preparou-se uma solução de 9,50 g.L-1. Os resultados quanto aos parâmetros cromatográficos e às constantes de equilíbrio mostraram que os componentes têm a seguinte ordem crescente de eluição: piperonal, safrol, isosafrol e terpinoleno. O piperonal tem a menor afinidade com a fase estacionária C18 enquanto o terpinoleno possui a maior. Quanto aos parâmetros de transferência de massa, todos os valores foram próximos àqueles previsto na literatura, sendo o coeficiente de difusão efetivo da ordem de 10-6 cm2.s-1 e o coeficiente de dispersão axial da ordem de 10-3 cm2.s-1. Em relação à abordagem experimental, o piperonal apresentou pureza e recuperação superiores a 98% e 97%, respectivamente, em que a fase móvel acetonitrila/água à 25 oC, constitui-se como o melhor sistema de separação. O mesmo resultado foi obtido para a abordagem teórica quanto ao sistema de separação, sendo a pureza e recuperação de aproximadamente 100% de piperonal. A CLAE semipreparativa com injeção empilhada mostrou-se bastante eficiente em termos de produção de piperonal com elevado grau de pureza. Os resultados indicaram também que uma quantidade maior de amostra pode ser injetada e as informações operacionais bem como os parâmetros determinados neste estudo podem ser facilmente implementados em cromatografia preparativa, tanto em batelada quanto contínua, para obter grandes quantidades de piperonal puro / Abstract: Piperonal is a molecule of great economic value because it is used as raw material in the cosmetic and pharmaceutical industries. One way of obtaining piperonal is through synthesis which substrate is safrole. Safrole is main constituents of the essential oil of long pepper (Piper hispidinervum, C. DC), specie that is abundant in Amazon region. After synthesis processes applied directly to the long pepper oil, piperonal is obtained as the main product and coproducts safrole, isosafrole glycol, isosafrole cis, trans-terpinolene, and isosafrole. The throughput for this synthetic route is about 84% of piperonal. For this reason, and considering the high added value at the piperonal is proposed that separate it by High Performance Liquid Chromatography with stacked injection. For this, two approaches were used: the experimental approach, in which the cycle time and the time of collection were obtained directly from the chromatogram in concentrated solution and the theoretical approach that arose due to proposed model in the thesis on condition of infinite dilution, where cycle times and collection were obtained from the parameters of the gaussian curve. In this last approach, the equilibrium constants and parameters of mass transfer (Dp, Def, Ds and Eb), which were obtained experimentally are needed. Três chromatographic separation systems were used: the first and second, consisted of mobile phase acetonitrile/water ¿ 70/30(v/v) at 25 and 35 oC and the third, ethanol/water ¿ 70/30 (v/v) at 35 oC, with detection in 245 nm all systems. It was used analytical column of 25 x 0,45 cm and semipreparative column of 25 x 1,0 filled with stationary phase C18 which size particle is 20 ?m. In analytical column were determined the total porosity and equilibrium constants of piperonal, safrole, isosafrole and, terpinoleno, in flow rate of 0.6 ¿ 1.4 mL.min-1. In semipreparative column were determined the total porosity as well as the parameters of mass transfer, in flow rates 4.0 ¿ 6.0 mL.min-1. For the performance of theoretical approach, was prepared a solution in which the concentration 9.50 g.L-1. The results regarding to chromatographic parameters and equilibrium constants showed that the components has a followed ascending order of elution: piperonal, safrole, isosafrole, terpinolene. The piperonal has a lowest affinity in respect to stationary phase C18 while terpinoleno has the greatest. Regarding mass transfer parameters, all values are close to those predicted in the literature, the effective diffusion coefficient of about 10-6 cm2.s-1 and the axial dispersion coefficient of the order of 10-3 cm2.s-1. With respect to experimental approach, piperonal presented purity and recovery greater than 98% and 97%, respectively, in which mobile phase acetonitrile/water at 25 ° C, was established as the best separation system. The same result was obtained to theoretical approach regarding to separation system, being purity and recovery about 100% of piperonal. The semipreparative HPLC with stacked injection proved to be very efficient in terms of producing piperonal with high purity. The results also indicate that a greater amount of sample may be injected, and the operational information¿s and the parameters determined in this study may be easily implemented in preparative chromatography, either batch or continuous, to obtain large quantities of pure piperonal / Doutorado / Engenharia de Processos / Doutor em Engenharia Química

The closed loop supply chain concept has been argued to be one vital sustainability solution to prevent waste and aid humanitarian concerns. At the same time, over a third of the food resources for human consumption is being converted to food waste, contributing to malnutrition, starvation and countless deaths. Previous studies have indicated problematic barriers and constraints preventing corporations to engage in CLSC in the perceived absence of urgency and financial motives.   The purpose of this thesis is to identify how companies within the food retail industry utilise closed loop supply chain solutions to reduce waste, and contribute with knowledge in the area of CLSC solutions applicable to the food retail industry. Our study investigates the use of CLSC in the food retail industry in Sweden, and the possible constraints and advantages of CLSC in the context of reducing food waste. A qualitative study was deemed most suitable in order to try to understand and explore the complexity of the CLSC concept in a different industry environment. Three Swedish companies active in the food retail industry participated in semi-structured interviews to expand our understanding of CLSC use and incentives applicable to reducing food waste. The findings of this thesis indicates that the firms in the Swedish food retailing industry are cognisant and aware of CLSC processes. However, in the perspective of the store managers, sustainable processes and activities that theoretically constitute core components within CLSC were simply identified as fundamental processes, incentives and activities in their daily operations towards working more sustainably to minimise food waste. Advantages of CLSC included the interplay and cooperation between corporate efforts and societal stakeholders, serving as a beacon for a brighter and more sustainable future benefiting not only firms and customers but arguably everyone. However, standards, policies and regulations were identified as a limiting factor, regarding to what extent companies can engage in certain CLSC activities. Although, it was identified that all of the case companies were eager to continue their work towards CLSC and sustainable operations, arguably indicating a long-term commitment to circular activities and endeavours.

Reversed-phase liquid chromatography (RPLC) is a commonly used separation technique in chemistry. Nevertheless, the mechanistic interactions at the molecular level among the eluent, analyte, and the stationary phase are not fully understood. Because of this limited understanding, optimization of the separation must be done experimentally. Learning more about molecular interactions should aid in improving separations. We are currently using second-harmonic generation (SHG) spectroscopy to investigate how analytes adsorb to the surface. SHG is a spectroscopic technique that produces signal only at places of non-isotropic symmetry; this typically occurs at surfaces. SHG can be used to produce surface isotherms of test analytes adsorbed to a model C18 stationary phase surface. Fitting these isotherms with a Langmuir model produces an adsorption equilibrium constant. However, the equilibrium constant can only be accurately determined if the true bulk concentration is known; this thesis describes an approach to ensure this. The equilibrium constant relates to Gibbs free energy and is the start to obtaining other thermodynamic information. The long equilibration times of analytes with the stationary phase observed in this study emphasize the importance of both thermodynamic information and kinetic values for understanding retention. Once equilibrium constants and other parameters are accurately obtained, this information can be used to improve predictions and calculations from numerical models.

G-protein coupled receptors (GPCRs) play a key role in a broad range of biological processes by binding to a wide variety of signaling molecules, which have resulted in 34% of all FDA-approved drugs which target GPCRs. The human genome encodes for approximately 800 GPCR members of which about 140 non-olfactory receptors remain orphans with an unknown function and endogenous ligand. Despite prolonged efforts to deorphanize the unresolved receptors, they remain orphans until this day. By studying scientific publications, this thesis has clarified the challenges with the deorphanization of GPCRs to explain why there are still so many orphan GPCRs when they have confirmed involvement in so many human disorders.

Preterm birth is a global health challenge and the leading cause of neonatal mortality. Each year, about 15 million babies are born preterm globally. Traditional tools that have been exploited for the detection of preterm birth biomarkers are expensive, time consuming, or lack multiplexing capabilities. The work described in this dissertation highlights techniques developed to detect preterm birth biomarkers rapidly and accurately in the effort to mitigate preterm birth risk. In this dissertation, I first demonstrated the use of stereolithography digital light processing-based 3D printing and microfluidics for the development of microfluidic devices that had microvalves for fluid control. I then used these devices for microchip electrophoresis and fluorescence detection of five preterm birth biomarkers from a published panel. Next, I presented developments in 3D printed microchip electrophoresis device design. I separated amino acids and preterm birth biomarkers in a serpentine device design, obtaining good resolution, separation efficiency, and improved preterm birth biomarker peak capacity. Finally, I demonstrated the integration of solid-phase extraction with microchip electrophoresis in 3D printed microfluidic devices. These integrated devices enabled a seamless transition from preterm birth biomarker enrichment and labeling to microchip electrophoresis separation and fluorescence detection. The work described in this dissertation shows promise in advancing key tools needed to address preterm birth risk rapidly and effectively.

Doctor of Philosophy / Department of Chemical Engineering / Keith L. Hohn / To characterize surface properties by current techniques, metal oxides typically have to be pre-treated at high temperature to remove surface absorbents. Therefore, a new low temperature method which can provide information on the surface chemistry is desired. In this work, the surface properties of metal oxide samples were studied by tetrakis(dimethylamino)ethylene (TDE) chemiluminescence (CL). This chemiluminescent method was also employed in probing the properties of reversed microemulsions. It was found that the emission intensity vs. reaction time curve (I[subscript]t) of catalyzed TDE CL on MgO was affected by the distributions and types of surface hydroxyl groups. Isolated hydroxyls with lower coordination were found to have higher catalytic reactivity for the emission of TDE CL. Although hydrogen bonded hydroxyls also catalyze the TDE oxidation reaction, the influence on the light emission was negative. Because the properties of surface hydroxyls are associated with specific orientations of adjacent ions, information on surface hydroxyls can provide information about some general surface characteristics of a metal oxide. When characterizing surface hydroxyls on Al[subscript]2O[subscript]3 by TDE CL, it was found that the catalytic reactivity of isolated hydroxyl groups is strongly associated with the stretching frequency of isolated hydroxyl. The stretching frequency of an isolated hydroxyl group is related to the modification of the adjacent ions and the coordination of the isolated hydroxyl. The results showed that the blue-shifts in the stretching frequencies of isolated hydroxyls led to increases in the catalytic reactivity of Al[subscript]2O[subscript]3 surfaces for the emission of TDE CL. TDE CL was further applied in characterizing the surfaces of other metal oxides and chemically grafted Al[subscript]2O[subscript]3. The results indicated that the isolated hydroxyl groups with fewer adjacent ions likely have higher affinity for the binding of grafting agents. Higher emission intensities were obtained from catalyzed TDE CL on metal oxides featuring higher percentages of isolated hydroxyls. The determination of a surfactant’s critical micellar concentration was accomplished by measuring the decay rate of the emission of TDE CL in a reversed microemulsion system. In this study, the CMC values of non-ionic and ionic surfactants were measured in different non-polar solvents.

<p>LC-MS of protein drugs requires new ideas in bonded phase design rather than adapting bonded phases from the realm of small-molecule drugs. The polymer-shell bonded phase is designed to interact with larger molecules and to shield proteins from the silica substrate. The particles consist of a core of solid silica and a shell of dense polymer brush. The polymer layer is thick enough to protect the protein from interactions with silanols to reduce peak tailing. The polymer contains multiple functional groups that introduce more selectivity. This design gives unprecedented LC resolution and MS sensitivity. Our group has developed polymer shell bonded phases for hydrophobic interaction chromatography (HIC-MS) of antibody-drug conjugates (ADCs), hydrophilic interaction liquid chromatography (HILIC-MS) of glycoproteins, and reversed-phase liquid chromatography (RPLC-MS) of monoclonal antibodies. Since HIC is not in-line compatible with MS due to the high salt levels, it is laborious to identify the constituents of HIC peaks. An MS-compatible alternative to HIC is reported here: native reversed phase liquid chromatography (nRPLC). This employs a mobile phase 50 mM ammonium acetate for high sensitivity in MS, and elution with a gradient of water/isopropanol. The nRPLC-MS data show that all ADC species, ranging from drug-to-antibody ratios of 1 to 8, remained intact and native on the column. As we adapt this concept to intact proteins, we find that lysozyme and α-chymotrypsinogen A are both eluted in their native conformations. We also use the polymer-shell concept to resolve IgG1 free thiol variants by RPLC-MS with 0.5% formic acid. Since there are always other variants besides the intended ones, the need for high MS sensitivity is desired to distinguish subtle mass change between disulfide bond and free thiols. Overall, MS sensitivity increases 10X relative while all of the thiol variants are well resolved by the polymethylmethacrylate bonded phase.</p>

A transição do sistema radiográfico convencional para os sistemas radiográficos digitais, ao longo de vinte anos, tem transformado as salas de laudos nos Serviços de Diagnóstico por Imagem tanto na Medicina quanto na Medicina Veterinária. Atualmente, com a introdução do sistema radiográfico computadorizado na rotina de alguns hospitais e laboratório de imagem, o uso das ferramentas do pós-processamento tem se tornado mais freqüente. Diante das vantagens e desvantagens destas ferramentas e da escassez de trabalhos a cerca dos filtros utilizados em imagens radiográficas digitais, o objetivo deste trabalho foi testar o uso dos filtros convencional, realce de borda e invertido, assim como a associação deles na detecção dos padrões pulmonares de cães e gatos. Foram selecionados 40 exames radiográficos do tórax de cães e gatos contendo as três projeções de eleição. Três observadores com diferentes graus de experiência e familiaridade com o sistema radiográfico computadorizado analisaram os filtros individualmente e depois em associação na detecção geral dos padrões pulmanres e individualmente. Obteve-se melhores valores de sensibilidade e especificidade, em geral, quando os observadores experientes utilizaram os três filtros em associação e, para o iniciante, os melhores resultados da sensibilidade e especificidade, em geral, foram no filtro convencional. Os resultados deste trabalho permitiram concluir que houve diferença estatística entre os observadores com distintos graus de experiência e familiaridade com o sistema digital. E que o uso em associação dos filtros pode incrementar o desempenho do radiologista na avaliação radiográfica do parênquima pulmonar. / The transition of the conventional radiographic system to the digital one has been transforming the radiographic routine human and veterinary medicine over the last twenty years. Currently, the introduction of the computed radiography system in some hospitals and imaging services has increased the use of post processing tools. Considering the advantages and disadvantages of these tools and the lack of knowledge about the filters used in digital radiographic images, the aim of this study was to test efficacy of the standard, edge enhancement and gray scale reversed filters and their association to detect pulmonary patterns of cats and dogs. This work selected forty canine and feline sets of thoracic radiographs, including three projections. Three different observers with different degrees of experience and familiarity with the computed radiographic system analyzed the filters individually and then associated in order to detect pulmonary patterns. The best results in sensibility and specificity were related to the more experienced observers using the three associated filters. However, for the beginner, the best sensibility and specificity results was reached with the use of the standard filter in general results. In conclusion were statistical differences between more experienced and familiarized observers with the digital system and the use of filters can increase the radiologist performance when evaluating the pulmonary patterns on the radiography.