M.Sc. / Emulsions are not widely used in industry for wear-metal-in-oil determinations and this study was undertaken in order to evaluate such a possibility. The use of emulsified standards was compared to aqueous standards for the calibration of an emulsified used lubricating oil sample. The traditionally used methods of ashing in a muffle furnace and dilution with the organic solvent, xylene were also evaluated in comparison with the emulsion methodology. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the wear-metal-in-oil analysis. The performance characteristics of each method were compared for the following metals: AI, Cr, Cu, Fe, Ni, and Pb. The used oil sample and emulsified standards were acid treated and emulsified in water {1% wlw) using tetralin as solvent and triton X-100 as surfactant. This evaluation included the calibration characteristics, precision and accuracy obtained, as well as the results of recovery studies. The emulsification method was found to be comparable to the ashing and dilution methods in terms of calibration and only Cr, Cu, Fe and Pb concentrations were found. The precision of the emulsification method was found, in general, to be close to or less than 2% RSD. The used oil matrix also contained leaked petroleum from a problem car engine. An accurate determination of lead was consequently impossible since the high lead content led to sedimentation. The use of the internal standard, indium, was evaluated for its effectiveness in correcting possible matrix effects that were evident from the results obtained in the recovery studies. The recovery studies showed the Cr and Pb determinations to be adversely affected by internal standardization. An alternative approach for matrix effect correction, the common analyte internal standardization (CAIS) method was also investigated. This method held promise for allowing the use of aqueous standards, instead of oil or emulsion standards, for the calibration of the emulsified oil samples. Three different applications of the CAIS technique were investigated and all proved unsuccessful.

Polymeric nanoparticles were synthesized and loaded with Cu²⁺ to explore the therapeutic potential for catically active transition metal ions and complexes other than cisplatin. Two types of nanoparticles were synthesized to show the potential for polymer based vectors. Copper loading and release were characterized via inductively coupled plasma mass spectrometry (ICP MS), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and elemental analysis. Results demonstrated that Cu could be loaded to the nano-sized carriers in an aqueous environment, and that the release was pH-dependent. The toxicity of these particles was measured in HeLa cells where significant toxicity was observed in vitro via dosing of high Cu-loaded nanoparticles. No significant toxicity was observed in cells dosed with Cu-free nanoparticles.

This dissertation focused on developing an integrated surface – subsurface hydrologic simulation numerical model by programming and testing the coupling of the USGS MODFLOW-2005 Groundwater Flow Process (GWF) package (USGS, 2005) with the 2D surface water routing model: FLO-2D (O’Brien et al., 1993). The coupling included the necessary procedures to numerically integrate and verify both models as a single computational software system that will heretofore be referred to as WHIMFLO-2D (Wetlands Hydrology Integrated Model). An improved physical formulation of flow resistance through vegetation in shallow waters based on the concept of drag force was also implemented for the simulations of floodplains, while the use of the classical methods (e.g., Manning, Chezy, Darcy-Weisbach) to calculate flow resistance has been maintained for the canals and deeper waters. A preliminary demonstration exercise WHIMFLO-2D in an existing field site was developed for the Loxahatchee Impoundment Landscape Assessment (LILA), an 80 acre area, located at the Arthur R. Marshall Loxahatchee National Wild Life Refuge in Boynton Beach, Florida. After applying a number of simplifying assumptions, results have illustrated the ability of the model to simulate the hydrology of a wetland. In this illustrative case, a comparison between measured and simulated stages level showed an average error of 0.31% with a maximum error of 2.8%. Comparison of measured and simulated groundwater head levels showed an average error of 0.18% with a maximum of 2.9%.

Orientador: Newton Cesário Frateschi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-28T23:46:00Z (GMT). No. of bitstreams: 1 Rezende_GuilhermeForniasMachadode_M.pdf: 3592220 bytes, checksum: e91127c5e777f7e4dfeeff9c5257f907 (MD5) Previous issue date: 2015 / Resumo: Microrressonadores óticos são blocos fundamentais para a integração fotônica. A busca por transmissão de sinais cada vez mais rápidos (atualmente, em dezenas de Gbps) faz com que novos projetos de combinações topológicas entre microanéis sejam exigidos constantemente. Quando aplicados ao processamento de sinais fotônicos, as características de um microrressonador ¿ a saber, espaçamento espectral livre, fator de qualidade e finesse ¿ costumam funcionar como figuras de mérito para avaliar sua capacidade de processamento, filtragem e modulação. Uma estratégia para o aumento da densidade espectral de resposta de transmissão utilizada neste trabalho consiste em acoplar microanéis menores no interior de um maior, mantendo-se o tamanho compacto original do ressonador maior. Neste trabalho, elaboramos uma ferramenta de projeto objetivando prever e descrever as características espectrais deste tipo de dispositivo. Para tanto, foram utilizados o Método de Matriz de Espalhamento, a Teoria de Modos Acoplados e a generalização e sistematização da Regra de Mason para o Ganho de Grafos Direcionais. Nossa ferramenta permite compreender as diferentes combinações de caminhos óticos executados pela luz no interior das cavidades, resolve analiticamente o espectro de transmissão de microanéis acoplados e providencia uma análise da potência ótica no interior de cada cavidade, provendo uma comparação eficiente com os resultados da Teoria de Modos Acoplados. Comparando as previsões teóricas com medidas de caracterização de dispositivos fabricados, encontramos a necessidade de reformulação das ideias dos chamados modos escuros ¿ os quais não são excitados dependendo da forma na qual o sistema é bombeado ¿ para descrição destes sistemas fotônicos / Abstract: Microring resonators are building block for photonic integration. The demand for faster signal transfer (nowadays, in the orders of Gbps) constantly requires new designs of topological combinations between microrings. When applied to photonic signal processing, their characteristics of free spectral range, quality factor and finesse are used as figure of merit in order to evaluate their capacity of processing, filtering and modulation. A strategy for enhancing the spectral density of transmission response, used in this work, consists in coupling smaller microrings inside a bigger one, keeping the original compact size of the bigger resonator unchanged. In this work, we elaborated a design tool in order to predict and describe the behavior of spectral characteristics of this kind of device. For that purpose, it was used the Scattering Matrix Method, the Coupled Mode Theory and the generalization and systematization of Mason¿s Rule for the Gain of Directional Graphs. Our tool provides a full understanding of all combinations of optical path inside the cavities, solve analytically the transmission spectrum of the coupled microrings and provides an optical power analysis inside each cavity, implying an efficient comparison with the results of Coupled Mode Theory. By comparing theoretical predictions with the measurements of characterization of fabricated devices, we found the necessity of reformulation of the ideas of the so-called dark states ¿ those which are not excited depending the way the system is pumped ¿ for describing theses photonic systems / Mestrado / Física / Mestre em Física / 131434-6/2013 / CNPQ

This diploma thesis deals with an optimization technique for the determination of semimetals in selected samples of food, which consists of sample digestion, preconcentration and detection of the elements. Preconcentration is usually chosen because these elements are contained in foods only in trace amounts, which are undetectable for some techniques. This work also made characteristics of semimetals, in terms of their functions in the body, of the occurrence in food and the consequences for the organism on their surplus or shortage. The chosen technique of preconcentration in this work was the preconcentration of titanium dioxide. When optimizing the techniques, however, was unlike the results published in literature, obtained low yield of elements sorbed on titanium dioxide, therefore the samples were measured by inductively coupled plasma mass spectrometry directly after their mineralization, wet digestion with low temperature. The results of this work indicate that the elements arsenic, boron and selenium are given technique detectable without preconcentration, whilst set germanium content in all samples failed, due to very low concentrations and therefore in these cases would be required preconcentration.

There is a need for reliable rules of thumb for various applications in the area of biochemistry, supramolecular chemistry and material sciences. Simultaneously, the amount of information, which we can gather from X-ray crystal geometries about the nature of recognition processes, is limited. Deeper insight into the noncovalent interactions playing the most important role is needed in order to revise these universal rules governing any recognition process. In this thesis, systematic development and study of the accuracy of the computational chemistry methods followed by their applications in protein DNA and host guest systems, are presented. The non-empirical quantum mechanical tools (DFT-D, MP2.5, CCSD(T) etc. methods) were utilized in several projects. We found and confirmed unique low lying interaction energies distinct from the rest of the distributions in several amino acid−base pairs opening a way toward universal rules governing the selective binding of any DNA sequence. Further, the predictions and examination of changes of Gibbs energies (ΔG) and its subcomponents have been made in several cases and carefully compared with experiments. We determined that the choline (Ch+) guest is bound 2.8 kcal/mol stronger (calculated ΔG) than acetylcholine (ACh+) to self-assembled triple helicate rigid...

The purpose of this study is to analyze the foundation beam linked between two shear walls in the presence of lateral loads. Mat foundation with shear walls is one of the most commonly used reinforced concrete structural systems to resist the lateral load. When two independent walls are connected with a link beam, also known as the coupling beam, the overturning resistance of the building is largely increased. However, the coupling beams are relatively weaker structures and can develop larger stresses. When there is a mat foundation, or pile cap in case of pile foundation, the part of the foundation which is right below the coupling beam where no shear wall is present, will also get large stresses due to the highly rigid nature of adjacent shear walls. Most of the lateral deformations are imposed only on the coupling beams and foundation beam. There is not much literature or design procedure found in books and codes to mitigate the high risks associated with the foundation beam between shear walls on its design vulnerability. This thesis is focused on the risks associated with exceptionally high forces on the foundation beam due to earthquake forces.

A feedwater heater is a typical component in power plants which increases the cycle efficiency. Over the last decade, renewable energies have significantly developed and been employed in the power grid. However, weather conditions are inconsistent and therefore produce variable power. Fossil fuel power stations are often required to supplement the variable renewable energies, which increased the rate of power cycling to an unforeseeable extent over the past decade. Power cycling results in changes in the flow rate, pressure, and temperature of a feedwater heater’s inlet flows. In a tubesheet-type feedwater heater, these transients induce cycling stress in the tubesheet and failures due to thermal fatigue occur. The header-type feedwater is currently employed in high pressure applications as it is more resistant to thermal fatigue compared to the tubesheet-type. However, the tubesheet-type is more cost effective to construct and maintain. It would be advantageous if the cyclic thermal stresses in the tubesheet can be better analysed and alleviated to support the use of the tubesheet-type. A detailed transient temperature distribution of the tubesheet is required to understand the thermal fatigue. Normally, engineers opt towards a full CFD to obtain such results. However, the size and complexity of a feedwater heater is immense and cannot be simulated practically solely using CFD spatial elements. This study developed a multiscale approach that thermally couples 1D network elements, CFD spatial elements, and macroscopic heat transfer correlations to reduce the computational expense substantially. The combination of the various selected techniques and the specific application of this methodology is unique. This approach is capable of obtaining the detailed transient temperature distribution of the tubesheet in a reasonable time, as well as include the effects of the upstream and downstream components within the network model. The methodology was implemented using Flownex and Ansys Fluent for the 1D network and CFD solvers, respectively. The internal tube flow was modelled using 1D network elements, while the steam was modelled with CFD. Thermal discretisation, mapping, and convergence were considered to create a robust methodology not limited to feedwater heaters only. Additionally, a method was developed to analyse flow maldistribution in tube-bundles using the coupled 1D-3D approach. The implementation of the methodology consists of two parts, of which one is for development purposes, and the other serves as a demonstration. The development was done on a simple TEMA-FU heat exchanger which is representative of a feedwater heater. The methodology was tested by varying the primary fluid’s flow rates, changing the fluid media, and conducting transient simulations. The temperature distributions obtained were compared against a full CFD model and corresponded very well with errors less than 4%. A reduction in computational time of more than 40% was achieved but is highly dependent on the specific problem. Improvements to be made in future studies include the accuracy of the laminar case method and the stability of the flow maldistribution algorithm. The methodology was demonstrated by applying it to an existing industrial feedwater heater. No plant data was available to use for input conditions and therefore were assumed. The steam in the DSH was modelled using 3D CFD elements and the tube flow with 1D network elements. The condensing zone’s heat transfer was approximated using an empirical correlation. A steady state case was simulated and the outlet temperatures corresponded well with the manufacturer’s data. The temperature distribution of the tubesheet and surrounding solids were obtained. Finally, assumed sinusoidal transient perturbations to the inlet conditions were imposed. It was evident that the thermal gradients of both sides of the tubesheet were misaligned which highlights the thermal lag and inertia that cause differential temperatures. The 1D-CFD methodology was developed successfully with results that proved to correspond well, for a wide range of conditions, to full CFD. The methodology was applied and can be, in future work, validated with experimental results or extended by modelling upstream and downstream components in the network solver. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2019. / Mechanical and Aeronautical Engineering / MEng (Mechanical Engineering) / Unrestricted

Thesis advisor: Gabor Kalman / Complex plasma systems have been studied for a long time. In this thesis we focus on a quasi-2D layer system. In fact, most experimental studies of complex plasmas are based on 2D systems, because it is easy to use camera to record the in-plane movement of particles. Unfortunately, due to the finite confining strength, the system is not a strictly 2D layer, it is a quasi-2D layer. We firstly studied the density profile of such a quasi-2D system by density functional theory(DFT). From the density profile research result, we found that the system can form a trilayer structure with proper parameters. Then we studied the dynamical properties of a trilayer system, and for simplicity, we only studied an ideal three layer model, both in liquid and lattice case. In lattice case, we firstly searched the stable lattice structure at different inter-layer distance. Then we used lattice sites summation to construct the dynamical matrix and solve the dispersion relation. For liquid case, we did the theoretical prediction for the collective dispersion by quasi localized charge approximation(QLCA), then we extracted the collective mode information from the molecular dynamics(MD) simulation. The QLCA and MD results were compared and discussed. The reason for the previous gap discrepancy problem is discovered. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

This dissertation presents theoretical and experimental investigations into the dynamical behavior of Micro electromechanical systems (MEMS) resonators and their exploitation for filtering, sensing, and logic applications. The dissertation is divided into two parts: MEMS coupled structures and MEMS dynamic logic devices. First, a theoretical and experimental investigation is presented on both electrostatically and mechanically coupled resonator. Static and dynamic analysis is presented for weakly electrostatically coupled silicon microbeams and also for strongly mechanically coupled polyimide microbeams. The static analysis focuses on revealing pull-in characteristics, while the dynamic analysis focuses on the frequency response of the system and its exploitation for potential applications in filtering and amplification. Next, the phenomenon of mode localization is explored theoretically and experimentally on both electrostatically and mechanically weakly coupled resonators. Eigenvalue analysis is conducted and the dynamic response of the coupled system under different external perturbations is investigated. It is observed, that the exploitation of mode localization depends on the choice of the resonator to be under direct excitation, its stiffness to be perturbed, and which resonator is used to record the output results. These understandings will potentially help improve the performance of MEMS mode-localized sensors. Finally, three techniques to realize cascadable MEMS logic devices are presented. MEMS logic device vibrates at two steady states; a high on-resonance state (1) and a low off-resonance state (0). First, a MEMS logic device is presented capable of performing the AND/NAND logic gate and a tri-state logic gate using mixed-frequency excitation. This work is based on the concept of activation (1) and deactivation (0) of combination resonances due to the mixing of two or more input signals. Second, exploitation of subharmonic resonance under an AC only excitation to perform AND logic operation is presented. Finally, another MEMS logic device is presented working on the principal of activation (1) and deactivation (0) of second resonant mode of a clamped-clamped microbeam. This device is capable of performing OR, XOR and NOT gate. Experimental demonstration of the cascadability is shown for this case cascading OR and NOT gate to perform a logically complete NOR logic gate.