Neste trabalho descreve-se uma rota de preparação de nanopartículas de ródio (4 nm diâmetro médio) dispersas no líquido iônico tetrafluoroborato de 1-n-butil-3-metilimidazólio (BMI.BF4) e suportadas na rede de sílica pelos métodos sol-gel e grafting. Na preparação pelo método sol-gel (ácido ou básico) obteve-se materiais com diferentes quantidades de líquido iônico encapsulado e diferente morfologia da matriz de sílica. A quantidade de ródio suportado nos xerogéis resultantes foi (0,1% m/m). A condição ácida de preparação resultou em sílica com maior quantidade de líquido iônico encapsulado e com diâmetro de poro maior, podendo ser considerada como responsável pela atividade catalítica observada na hidrogenação de alcenos. A alta quantidade de líquido iônico incorporado pode ser importante para garantir a estabilidade das nanopartículas. O material catalítico preparado pelo método sol-gel pode ser recuperado por decantação e reutilizado por 10 vezes sem perda da atividade catalítica. As micrografias obtidas por microscopia eletrônica de transmissão do catalisador isolado depois de dez recargas mostraram que o material recuperado não apresentou sinais aparentes de aglomeração. A combinação (líquido iônico encapsulado/nanopartículas de ródio/sílica) exibe um excelente efeito sinérgico que aumenta a atividade catalítica e a robustez das nanopartículas de ródio para hidrogenação. Todos os sistemas suportados preparados foram mais ativos do que nanopartículas isoladas. / This work describes a route of preparation of rhodium nanoparticles (4 nm mean diameter) dispersed in an ionic liquid (1-n-butyl-3-methylimidazolium tetrafluoroborate) and supported within a silica network, prepared by the sol-gel method and grafting method. The sol-gel preparation method (acid or basic) gives materials with different contents in encapsulated ionic liquid and different silica morphology. The rhodium content in the resulting xerogels was (0.1 wt%). However, acidic conditions afforded higher contents of encapsulated ionic liquid and xerogels with larger pore diameters, which could be considered as responsible for the higher catalyst activity in hydrogenation of the alkenes. The catalytic material prepared by the sol gel method can be recovered by simple decantation and re-used at least ten times without any significant loss in catalytic activity. Transmission electron microscopy (TEM) of the catalyst isolated after ten recharges showed that the recovered material did not present apparent signs of agglomeration. The combination (ionic liquid/rhodium nanoparticles/silica) exhibits an excellent synergistic effect that enhances the activity and robustness of the rhodium hydrogenation catalysts. All the supported systems were more active than isolated rhodium nanoparticles for the hydrogenation of alkenes.

Neste trabalho é apresentado um novo método para a preparação de nanopartículas de metais de transição em solução. O método consiste na redução por hidrogênio molecular de sais metálicos imobilizados em líquidos iônicos derivados do cátion 1,3-dialquilimidazólio. Nanopartículas de Rh(0) com tamanho entre (2,1+-0,1)nm foram obtidas pela redução de RhCl3 em líquidos iônicos derivados do cátion n-butilmetilimidazólio BMI.X (X=BF4, PF6, CF3SO3), e aplicados como catalizadores para as reações de hidrogenação de olefinas e aromáticos. Nanopartículas de Pd(0) com tamanho entre (4,9+-1,5)nm foram obtidas pela redução de Pd(acac)2 em BMI.PF6 e aplicadas como catalisadores para a reação de hidrogenação de 1,3-butadieno em regime heterogêneo e suportadas em BMI.X (X=BF4, PF6). Nanopartículas bimetálicas de Pd-Rh(0) com tamanho entre (9,1+-0,8)nm também foram obtidas pela redução concomitante de PdCl2 e RhCl3 em líquidos iônicos BMI.X (X=BF4, PF6) e aplicadas como catalisadores para a hidrogenação de 1,5-ciclo-octadieno. Os resultados obtidos sugerem que o líquido iônico deve ser o responsável pela estabilização das nanopartículas e está intimamente relacionado com a atividade catalítica das nanopartículas. A aglomeração e a sistemática perda de atividade catalítica das nanopartículas parecem ser devidas à presença de hidrogênio molecular no meio reacional. Além disso, os resultados obtidos na síntese de nanopartículas bimetálicas indicam que a sua composição pode ser regulada pelas condições da reação de síntese. As reações de hidrogenação foram utilizadas como sondas químicas para o estudo das propriedades catalíticas das nanopartículas. Os resultados obtidos sugerem um mecanismo de reação de superfície, típico de sistemas heterogêneos clássicos. / In this work we present a new method for the preparation of soluble transition-metal nanoparticles. The method consists in the reduction by molecular hydrogen of metallic salts immobilized in ionic liquids derived from the 1,3-dialkylimidazolium cation. Nanoparticles of Rh(0) with size of (2,1 ± 0,1) run were synthesized from the reduction of RhCl3 in ionic liquids derived from the n-butylmethylimidazolium cation BMI.X (X = BF 4, PF 6, CF3SO3), and applied as catalysts for the hydrogenation of olefins and aromatics. Nanoparticles of Pd(0) with size of (4,9 ± 1,5)nm were synthesized from Pd(acac)2 immobilized in BMI.PF6 and applied as catalyst for the hydrogenation of 1,3-butadiene in both heterogeneous system and supported by ionic liquids BMI.X (X= BF4, PF6). Bimetallic nanoparticles of Pd-Rh(O) with size of (9,1 ± 0,8) were also synthesized from the reduction of PdCl2 and RhCl3 in ionic liquids BMI.X (X = BF4, PF6) and applied as catalysts for the hydrogenation of 1,5-cyclooctadiene. The results suggest that the ionic liquid must be the responsible for the nanoparticles stabilization and is closely related with the catalytic activity and selectivity of the nanoparticles. The agglomeration and systematic loss of activity of the nanoparticles seems to be due to the presence of hydrogen in the reactional medium. Furthermore, the results obtained in the synthesis of bimetallic nanoparticles show that their composition can be regulated by the reaction conditions. The hydrogenation reactions were used as chemical probes in the study of the catalytic properties of the nanoparticles. The results suggest a surface-like kinetic mechanism, typical of classical heterogeneous catalysis.

Neste trabalho é apresentado um novo método para a preparação de nanopartículas de metais de transição em solução. O método consiste na redução por hidrogênio molecular de sais metálicos imobilizados em líquidos iônicos derivados do cátion 1,3-dialquilimidazólio. Nanopartículas de Rh(0) com tamanho entre (2,1+-0,1)nm foram obtidas pela redução de RhCl3 em líquidos iônicos derivados do cátion n-butilmetilimidazólio BMI.X (X=BF4, PF6, CF3SO3), e aplicados como catalizadores para as reações de hidrogenação de olefinas e aromáticos. Nanopartículas de Pd(0) com tamanho entre (4,9+-1,5)nm foram obtidas pela redução de Pd(acac)2 em BMI.PF6 e aplicadas como catalisadores para a reação de hidrogenação de 1,3-butadieno em regime heterogêneo e suportadas em BMI.X (X=BF4, PF6). Nanopartículas bimetálicas de Pd-Rh(0) com tamanho entre (9,1+-0,8)nm também foram obtidas pela redução concomitante de PdCl2 e RhCl3 em líquidos iônicos BMI.X (X=BF4, PF6) e aplicadas como catalisadores para a hidrogenação de 1,5-ciclo-octadieno. Os resultados obtidos sugerem que o líquido iônico deve ser o responsável pela estabilização das nanopartículas e está intimamente relacionado com a atividade catalítica das nanopartículas. A aglomeração e a sistemática perda de atividade catalítica das nanopartículas parecem ser devidas à presença de hidrogênio molecular no meio reacional. Além disso, os resultados obtidos na síntese de nanopartículas bimetálicas indicam que a sua composição pode ser regulada pelas condições da reação de síntese. As reações de hidrogenação foram utilizadas como sondas químicas para o estudo das propriedades catalíticas das nanopartículas. Os resultados obtidos sugerem um mecanismo de reação de superfície, típico de sistemas heterogêneos clássicos. / In this work we present a new method for the preparation of soluble transition-metal nanoparticles. The method consists in the reduction by molecular hydrogen of metallic salts immobilized in ionic liquids derived from the 1,3-dialkylimidazolium cation. Nanoparticles of Rh(0) with size of (2,1 ± 0,1) run were synthesized from the reduction of RhCl3 in ionic liquids derived from the n-butylmethylimidazolium cation BMI.X (X = BF 4, PF 6, CF3SO3), and applied as catalysts for the hydrogenation of olefins and aromatics. Nanoparticles of Pd(0) with size of (4,9 ± 1,5)nm were synthesized from Pd(acac)2 immobilized in BMI.PF6 and applied as catalyst for the hydrogenation of 1,3-butadiene in both heterogeneous system and supported by ionic liquids BMI.X (X= BF4, PF6). Bimetallic nanoparticles of Pd-Rh(O) with size of (9,1 ± 0,8) were also synthesized from the reduction of PdCl2 and RhCl3 in ionic liquids BMI.X (X = BF4, PF6) and applied as catalysts for the hydrogenation of 1,5-cyclooctadiene. The results suggest that the ionic liquid must be the responsible for the nanoparticles stabilization and is closely related with the catalytic activity and selectivity of the nanoparticles. The agglomeration and systematic loss of activity of the nanoparticles seems to be due to the presence of hydrogen in the reactional medium. Furthermore, the results obtained in the synthesis of bimetallic nanoparticles show that their composition can be regulated by the reaction conditions. The hydrogenation reactions were used as chemical probes in the study of the catalytic properties of the nanoparticles. The results suggest a surface-like kinetic mechanism, typical of classical heterogeneous catalysis.

Nuclear magnetic resonance (NMR) spectroscopy has proven to be an invaluable tool for the modern chemist, despite being a relatively insensitive spectroscopic technique. However, it is precisely this insensitivity that limits characterization of low-receptivity nuclides, which make up the bulk of transition metal nuclides, in particular. In this work, high-fields were used to collect the first 61Ni solid-state NMR (SSNMR) spectra of diamagnetic nickel compounds, specifically, bis(1,5-cyclooctadiene)nickel(0) (Ni(cod)2), tetrakis(triphenylphosphite)nickel(0) (Ni[P(OPh)3]4), and tetrakis(triphenylphosphine)nickel(0) (Ni(PPh3)4). This was complemented by NMR study of the co-ordinated ligands and 61Ni density functional theory (DFT) computations. 61Ni SSNMR spectra of Ni(cod)2 were used to determine its isotropic chemical shift (δiso = 965 ± 10 ppm), span (Ω = 1700 ± 50 ppm), skew (κ = -0.15 ± 0.05), quadrupolar coupling constant (CQ = 2.0 ± 0.3 MHz), quadrupolar asymmetry parameter (η = 0.5 ± 0.2), and the relative orientation of the chemical shift and EFG tensors. Solution study of Ni(cod)2 saturated in C6D6 yielded a narrow 61Ni signal, and the temperature dependence of δiso(61Ni) was assessed (δiso being 936.5 ppm at 295 K). The solution is proposed as a secondary chemical shift reference for 61Ni NMR in lieu of the extremely toxic Ni(CO)4 primary reference. For Ni[P(OPh)3]4, 61Ni SSNMR was used to infer the presence of two distinct crystallographic sites and establish ranges for δ¬iso in the solid state, as well as an upper bound for CQ (3.5 MHz for both sites). For Ni(PPh3)4, fitting provided a δiso value of 515 ± 10 ppm, Ω of 50 ± 50 ppm, κ of 0.5 ± 0.5, CQ of 0.05 ± 0.01 MHz, and η of 0.0 ± 0.2. Ni(cod)2 was chosen for study as it is a ubiquitous source of nickel(0), used for both further synthesis of nickel(0) compounds and directly as a catalyst. The study of Ni[P(OPh)3]4 and Ni(PPh3)4 demonstrated the utility of 61Ni SSNMR given the lack of a previously reported crystal structure for both and the transient nature of Ni(PPh3)4 in solution. The work begins in Chapter 1 by introducing the interactions fundamental to NMR spectroscopy, before moving on to briefly review the field of transition metal nuclide NMR, the chemistry of nickel (with an emphasis on homogeneous catalysis with nickel(0)), and the literature with respect to nickel NMR up to this point. In Chapter 2, the theory and practice of NMR are explained, including solid-state NMR, as well as the basic principles of density functional theory NMR computations. The specific experimental and computational methods of this work are also introduced. Lastly, in Chapter 3 the results are discussed in the context of the concepts presented and literature reviewed, and highlight the use of 61Ni NMR as a means to gain novel information about the chemistry of the compounds studied.

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No description available.

The TOPEX/POSEIDON Project is a joint U.S. and French mission to develop and operate an Earth orbiting satellite capable of making accurate measurements of the mean sea level in a way that allows the study of ocean dynamics. The understanding of ocean dynamics is very important in order to study events such as El Nino. Soon after the launch of the TOPEX satellite, some unusually high, but localized, values of the ocean's radar cross section, sigma-0, were observed by scientists at the NASA Goddard Space Flight Center. These phenomena have been referred to as sigma-0 blooms, and are accompanied by an increase in noise in the significant wave height (SWH) and altitude measurements. Since approximately 5% of all data recorded by the satellite contains sigma-0 blooms, it is important to understand their causes so that corrective measures can be taken by NASA. This thesis investigates two possible origins of the sigma-0 blooms: a surface containing a step discontinuity in sigma-0, and a surface containing slick or calm areas. Models corresponding to the theoretical returns from these two types of surfaces are developed and studied. / Master of Science

The next-generation of radio interferometer arrays - the proposed Square Kilometre Array (SKA) and its precursor instruments, The Karoo Array Telescope (MeerKAT) and Australian Square Kilometre Pathfinder (ASKAP) - will produce radio observation survey data orders of magnitude larger than current sizes. The sheer size of the imaged data produced necessitates fully automated solutions to accurately locate and produce useful scientific data for radio sources which are (for the most part) partially hidden within inherently noisy radio observations (source extraction). Automated extraction solutions exist but are computationally expensive and do not yet scale to the performance required to process large data in practical time-frames. The DUCHAMP software package is one of the most accurate source extraction packages for general (source shape unknown) source finding. DUCHAMP's accuracy is primarily facilitated by the à trous wavelet reconstruction algorithm, a multi-scale smoothing algorithm which suppresses erratic observation noise. This algorithm is the most computationally expensive and memory intensive within DUCHAMP and consequently improvements to it greatly improve overall DUCHAMP performance. We present a high performance, multithreaded implementation of the à trous algorithm with a focus on `desktop' computing hardware to enable standard researchers to do their own accelerated searches. Our solution consists of three main areas of improvement: single-core optimisation, multi-core parallelism and the efficient out-of-core computation of large data sets with memory management libraries. Efficient out-of-core computation (data partially stored on disk when primary memory resources are exceeded) of the à trous algorithm accounts for `desktop' computing's limited fast memory resources by mitigating the performance bottleneck associated with frequent secondary storage access. Although this work focuses on `desktop' hardware, the majority of the improvements developed are general enough to be used within other high performance computing models. Single-core optimisations improved algorithm accuracy by reducing rounding error and achieved a 4 serial performance increase which scales with the filter size used during reconstruction. Multithreading on a quad-core CPU further increased performance of the filtering operations within reconstruction to 22 (performance scaling approximately linear with increased CPU cores) and achieved 13 performance increase overall. All evaluated out-of-core memory management libraries performed poorly with parallelism. Single-threaded memory management partially mitigated the slow disk access bottleneck and achieved a 3.6 increase (uniform for all tested large data sets) for filtering operations and a 1.5 increase overall. Faster secondary storage solutions such as Solid State Drives or RAID arrays are required to process large survey data on `desktop' hardware in practical time-frames.

Orchestration of learning involves the real-time management of activities performed by educators in learning environments, with a particular focus on the effective use of technology. While different educational settings present unique problems, the common challenges have been noted to primarily be as a result of multiple heterogeneous activities and their associated intrinsic and extrinsic constraints. In addition to these challenges, this thesis argues that the complexities of orchestration are further amplified due to the ad hoc nature of the approaches and techniques used to orchestrate learning activities. The thesis proposes a streamlined approach to technology-driven orchestration of learning, in order to address these challenges and complexities. Specifically, the thesis proposes an organised approach that focuses on three core aspects of orchestration: activity management, resource management and sequencing of learning activities. Orchestration was comprehensively explored in order to identify the core aspects essential for streamlining technology-driven orchestration. Proof-of-concept orchestration toolkits, based on the proposed orchestration approach, were implemented and evaluated in order to assess the feasibility of the approach, its effectiveness and its potential impact on the teaching experience. Comparative analysis and guided orchestration controlled studies were conducted to compare the effectiveness of ad hoc orchestration with streamlined orchestration and to measure the orchestration load, respectively. In addition, a case study of a course that employed a flipped classroom strategy was conducted to assess the feasibility of the proposed approach. The feasibility was further assessed by integrating a workflow, based on the proposed approach, that facilitates the sharing of reusable orchestration packages. The results from the studies suggest that the streamlined approach is more effective when compared to ad hoc orchestration and has a potential to provide a positive user experience. The results also indicate that the approach imposes acceptable orchestration load during scripting of learning activities. Case studies conducted in authentic educational settings suggest that the approach is feasible, and potentially applicable to useful practical usage scenarios. The long-term implications are that streamlining of technology-driven orchestration could potentially improve the effectiveness of educators when orchestrating learning activities.

Bakgrund: En organtransplantation är en livräddande operation när ett organ har slutat fungera eller fungerar dåligt. En organtransplantation ändrar barnets livskvalitet men komplikationer och medicinering orsakar ofta lidande. Det är en omvälvande upplevelse för föräldrar att gå genom ett barns organtransplantation. Sjuksköterskan kan hjälpa både barn och föräldrar genom processen genom att vara lyhörd för familjens behov. Syfte: Att belysa föräldrars upplevelser av att ha ett barn som genomgått organtransplantation. Metod: Studien var en allmän litteraturstudie innehållande tio vetenskapliga artiklar vilka bearbetades med inspiration från innehållsanalys. Resultat: Tre huvudkategorier framkom: (i) upplevelser av den nya vardagen, (ii) upplevelser av relationer, (iii) upplevelser av oro inför framtiden. Konklusion: Föräldrarna upplevde att barnets organtransplantation gjorde livet lättare än innan men den sågs också som ett falskt hopp om ett bättre liv. Det sociala livet begränsades och det fanns både en negativ och positiv påverkan på föräldrarnas relationer. Föräldrarna upplevde även oro inför att inte veta vad framtiden skulle innebära. Föräldrar behöver stöd och information från sjuksköterskan för att klara av att ta hand om och vårda ett svårt sjukt barn som genomgått en organtransplantation. / Background: An organ transplant is a life-saving operation when an organ has stopped working or is working inadequate. An organ transplant changes a child's quality of life, but complications and medication can often cause suffering. It is a transformative experience for parents to go through a child's organ transplant. The nurse can help both children and parents through the process by being sensitive to the needs of the family. Aim: To shed light on parents’ experiences of having a child who has undergone an organ transplant. Method: The study is a general literature study containing ten scientific articles. The articles were processed with inspiration from content analysis. Result: Three main categories emerged: (i) experiences of the new everyday life, (ii) experiences of relationships, (iii) experiences of anxiety about the future. Conclusion: The parents felt that the child's organ transplant made life easier, but it was also seen as a false hope for a better life. The social life was limited and there were both a negative and positive impact on the parents’ relationships. The parents also experienced anxiety about not knowing what the future would entail. Parents need support and information from the nurse to cope with looking after and caring for a seriously ill child who has undergone an organ transplant.