Recentemente foi demonstrado que a técnica de ressonância magnética nuclear no domínio do tempo (RMN-DT) é uma importante ferramenta analítica que é passível de ser acoplada com a eletroquímica (EQ-RMN). No entanto, como foi demonstrado nesse presente trabalho, a técnica de RMN não é passiva, ou seja, ela atua sobre as reações eletroquímicas aumentando a velocidade das reações realizadas in situ quando essas são limitadas por transporte de massas e/ou transferência de cargas. Essa alteração da taxa de reação é ocasionada por um fenômeno conhecido por magnetoeletrólise, que tem como principal resultante a força de Lorentz, que é o produto vetorial entre o campo magnético e o fluxo de íons gerado durante a eletrólise. O efeito do campo magnético sobre diferentes sistemas eletroquímicos foi comprovado na presença de campo magnético de equipamentos de RMN de baixa e alta resolução. Além do foco dado para a magnetoeletrólise durante o acoplamento EQ-RMN, novas células eletroquímicas foram miniaturizadas para a utilização com a RMN a partir de um método simples, rápido e robusto. Também foram feitas medições de velocimetria utilizando a técnica de imagem por spin eco com as quais foi possível visualizar e quantificar o efeito do campo magnético atuando sobre a reação de eletrodeposição de cobre realizada in situ. Esse trabalho foi o primeiro a utilizar o campo magnético do espectrômetro de RMN para estudar a magnetoeletrólise. Além disso, esse trabalho de doutorado foi o primeiro a utilizar um espectrômetro de RMN de bancada de alta resolução para o acoplamento com a eletroquímica. / Recently it was demonstrated that time domain Magnetic Nuclear Resonance (TD-NMR) is an important analytical technique which can be coupled to electrochemistry (EC-NMR). However, it was demonstrated in this work that NMR is not a passive technique, in other words it affects the electrochemical reactions performed in situ by increasing the reaction rate of mass transport and/or charge transfer limited reactions. This change in the reaction rate is caused by a phenomenon known as magnetoeletrolysis, it has as main resultant the Lorentz force, which is the vectorial product between the magnetic field vector and the ion flow produced during the electrolysis. The magnetic field effect on different electrochemical systems has been shown in the presence of magnetic fields of low and high resolution NMR spectrometers. In addition to the focus given to magnetoelectrolysis during the EC-NMR coupling, novel electrochemical cells were miniaturized for coupling with NMR by using a simple, rapid and robust method. Velocimetry measurements were also made using the spin-echo imaging technique with which it was possible to visualize and quantify the effect of the magnetic field acting on the in situ copper electrodeposition reaction. This work was the first to use the magnetic field of the NMR spectrometer to study magnetoelectrolysis. In addition, this doctoral thesis was the first to use a bench-top high resolution NMR spectrometer for coupling with electrochemistry.

Recentemente foi demonstrado que a técnica de ressonância magnética nuclear no domínio do tempo (RMN-DT) é uma importante ferramenta analítica que é passível de ser acoplada com a eletroquímica (EQ-RMN). No entanto, como foi demonstrado nesse presente trabalho, a técnica de RMN não é passiva, ou seja, ela atua sobre as reações eletroquímicas aumentando a velocidade das reações realizadas in situ quando essas são limitadas por transporte de massas e/ou transferência de cargas. Essa alteração da taxa de reação é ocasionada por um fenômeno conhecido por magnetoeletrólise, que tem como principal resultante a força de Lorentz, que é o produto vetorial entre o campo magnético e o fluxo de íons gerado durante a eletrólise. O efeito do campo magnético sobre diferentes sistemas eletroquímicos foi comprovado na presença de campo magnético de equipamentos de RMN de baixa e alta resolução. Além do foco dado para a magnetoeletrólise durante o acoplamento EQ-RMN, novas células eletroquímicas foram miniaturizadas para a utilização com a RMN a partir de um método simples, rápido e robusto. Também foram feitas medições de velocimetria utilizando a técnica de imagem por spin eco com as quais foi possível visualizar e quantificar o efeito do campo magnético atuando sobre a reação de eletrodeposição de cobre realizada in situ. Esse trabalho foi o primeiro a utilizar o campo magnético do espectrômetro de RMN para estudar a magnetoeletrólise. Além disso, esse trabalho de doutorado foi o primeiro a utilizar um espectrômetro de RMN de bancada de alta resolução para o acoplamento com a eletroquímica. / Recently it was demonstrated that time domain Magnetic Nuclear Resonance (TD-NMR) is an important analytical technique which can be coupled to electrochemistry (EC-NMR). However, it was demonstrated in this work that NMR is not a passive technique, in other words it affects the electrochemical reactions performed in situ by increasing the reaction rate of mass transport and/or charge transfer limited reactions. This change in the reaction rate is caused by a phenomenon known as magnetoeletrolysis, it has as main resultant the Lorentz force, which is the vectorial product between the magnetic field vector and the ion flow produced during the electrolysis. The magnetic field effect on different electrochemical systems has been shown in the presence of magnetic fields of low and high resolution NMR spectrometers. In addition to the focus given to magnetoelectrolysis during the EC-NMR coupling, novel electrochemical cells were miniaturized for coupling with NMR by using a simple, rapid and robust method. Velocimetry measurements were also made using the spin-echo imaging technique with which it was possible to visualize and quantify the effect of the magnetic field acting on the in situ copper electrodeposition reaction. This work was the first to use the magnetic field of the NMR spectrometer to study magnetoelectrolysis. In addition, this doctoral thesis was the first to use a bench-top high resolution NMR spectrometer for coupling with electrochemistry.

This dissertation addresses the design, simulation, prototype, and test of a new energy generation system, which transforms rotational motion into electricity by the use of an innovative turbine-generator. The system is divided in two assembled subsystems that interact to finally transform kinetic energy into electricity. The first subsystem is a miniaturized notched impulse turbine system, and the second one is a millimeter permanent magnet generator (PMG) assembled into the turbine. The conversion of biomechanical energy to electric energy, using clean and free energy produced by a living organism, is being increasingly researched [1]-[11]. These are all viable options, but advantages and disadvantages of each type of energy conversions should be evaluated individually to determine key factors such as efficiency as an energy harvesting method, the implementation cost, size, and the final applications where they will be used. Through this dissertation, a new option of green energy conversion is made available; focusing on the use of turbines to extract energy from microfluidics, with diverse application in biomedical, military/aerospace, and home areas. These systems have the potential of converting mechanical movement energy, and hydraulic energy into electric energy that may be sufficient for self-powering nano/micro devices and nano/micro systems. A flow, with constant pressure, a magnetic generator, and a novel impulse turbine design are combined to form a self-contained miniaturized generator system. The turbine consists of two main parts: a bearingless rotor and the enclosure or casing; while the miniaturized magnetic generator is a permanent magnet brushless machine, consisting of permanent magnets in a ring configuration and radial coils. A permanent pressure, from microfluidic pressure system, is the force used to move the blades. This rotational motion of the turbine is transformed into electricity using magnetic induction, formed by permanent magnets on the rotor and nine coils fixed in the holder of the turbine. The electricity is generated when the magnetic field rotates and moves past the conductor, which induces a current according to Faraday's Law [1-3]. The system has potential uses not only in medical equipment, but in automotive applications, home appliances, and aquatic and ventilation systems.

Integration of more communication standards in one microwave wireless device created a demand on developing compact, low-cost, and robust multi-band microwave components. This dissertation presents three studies for designing miniaturized and multi-band circuits that can be used for multi-band radio frequency (RF) front-ends. These three studies are the design of dual-band and tunable bandpass filters as well as dual- and triple-band equal-split power dividers/combiners. The dual-band filter is based on split ring resonators and double slit complemantary split ring resonators. A dual-band prototype three-stage Chebyshev filter, with a fractional bandwidth of 2% at 0.9 GHz and a fractional bandwidth of 3% at 1.3 GHz with equal-ripple of 0.4 dB at both passbands, is presented. The overall size of the dual-band filter is three times smaller compared to edge-coupled microstrip filters. Good out-of-band signal rejection (< 38 dB) and insertion losses (< 4.9 dB for the lower passband and <2.7 dB for the upper passband) are achieved. The proposed tunable filter is designed from varactor loaded split ring resonators. The size of the tunable filter is reduced by a factor of 3.5 compared to quarter wavelength-based coupled line filters.The power divider is based on composite right- and left-handed transmission lines. Dual-band and triple-band power divider prototypes are designed, fabricated, and tested. The passbands of the triple-band Wilkinson power divider are centered at 0.8 GHz, 1.3 GHz, and 1.85 GHz, and the passbands of the dual-band Wilkinson power divider are centered at 0.7 GHz, 1.5 GHz. The triple-band divider has a length of 0.66 wavelength in the substrate and its size is reduced to 3/4 of right-handed transmission line-based Wilkinson power dividers. The dual-band power divider has wide fractional bandwidths ( 20% at the lower passband and 41% at the upper passband). Excellent input matchings (input return losses < 29 dB), output matchings (output return losses < 23 dB), and output port isolations (< 24 dB) are achieved at all passbands of the power dividers. The proposed filters and power dividers are compact and low-cost, and are promising candidates for the miniaturization and cost-reduction of multi-band microwave wireless system.

<p>This thesis deals with the peroxyoxalate chemiluminescence (POCL) reaction and its application as a detection technique in flow systems for chemical analysis. Particularly, miniaturized flow systems aimed for separation of molecules. In such systems, a high light intensity and a rapid development of the emission are the desired reaction characteristics, for reasons discussed in this text. The work tries to develop an understanding of the chemical processes involved in POCL, with special emphasis to the species favoring or hindering a rapid light evolution. Hence, is the focus placed on the nature of catalysis and the desired properties of substances acting as catalysts in this reaction. Consequently, the scientific papers on which this work is founded includes both systematic stopped-flow studies of catalyst candidates and of the causes for diminished light emission. In addition, multivariate strategies for reaction optimization in practical analysis situations are treated, and the application of the POCL technique to detection of serum-extracted neuroactive steroids, derivatized with fluorescent moieties, is presented.</p><p>From the experiments in this thesis it is clear nucleophilic catalysts are the most efficient enhancing compounds, which means that they must possess a carefully balanced characteristics of nucleophilicity, leaving group ability, and basicity. The investigations also conclude that the feature of basicity efficiently can be delegated to a non-nucleophilic co-catalyst, which allow the use of nucleophilic catalysts that need to be deprotonated to be active. This thesis also shows the importance of minimizing the amount of competing nucleophiles at the site of reaction to maintain the emission. This implies that also solvents and buffer substances should be carefully chosen not to interfere with the emission process.</p><p>The most promising combination of catalysts found in this work was 4,5- dichloroimidazole together with 1,2,2,6,6-pentamethylpiperidne. This arrangement was capable of speeding the reaction more than tenfold while increasing the maximum emission intensity by about the same factor.</p>

This thesis deals with the peroxyoxalate chemiluminescence (POCL) reaction and its application as a detection technique in flow systems for chemical analysis. Particularly, miniaturized flow systems aimed for separation of molecules. In such systems, a high light intensity and a rapid development of the emission are the desired reaction characteristics, for reasons discussed in this text. The work tries to develop an understanding of the chemical processes involved in POCL, with special emphasis to the species favoring or hindering a rapid light evolution. Hence, is the focus placed on the nature of catalysis and the desired properties of substances acting as catalysts in this reaction. Consequently, the scientific papers on which this work is founded includes both systematic stopped-flow studies of catalyst candidates and of the causes for diminished light emission. In addition, multivariate strategies for reaction optimization in practical analysis situations are treated, and the application of the POCL technique to detection of serum-extracted neuroactive steroids, derivatized with fluorescent moieties, is presented. From the experiments in this thesis it is clear nucleophilic catalysts are the most efficient enhancing compounds, which means that they must possess a carefully balanced characteristics of nucleophilicity, leaving group ability, and basicity. The investigations also conclude that the feature of basicity efficiently can be delegated to a non-nucleophilic co-catalyst, which allow the use of nucleophilic catalysts that need to be deprotonated to be active. This thesis also shows the importance of minimizing the amount of competing nucleophiles at the site of reaction to maintain the emission. This implies that also solvents and buffer substances should be carefully chosen not to interfere with the emission process. The most promising combination of catalysts found in this work was 4,5- dichloroimidazole together with 1,2,2,6,6-pentamethylpiperidne. This arrangement was capable of speeding the reaction more than tenfold while increasing the maximum emission intensity by about the same factor.

No description available.

Artificial Magnetic Materials (AMMs) are a subgroup of metamaterials which are engineered to provide desirable magnetic properties not seen in natural materials. These artificial structures are designed to provide either negative or enhanced positive (higher than one) relative permeability. AMMs with negative permeability are used to develop Single Negative (SNG), or Double Negative (DNG) metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave frequencies where the natural magnetic materials fail to work efficiently. AMMs are realized by embedding metallic resonators in a host dielectric. These inclusions provide desirable magnetic properties near their resonance frequency. Artificial magnetic materials used as SNG, or DNG have many applications such as: sub-wavelength cavity resonators, sub-wavelength parallel-plate wave guides, sub-wavelength cylindrical and spherical core–shell systems, efficient electrically small dipole antennas, super lenses, THz active devices, sensitivity enhancement near-field probes using double and single negative media, and mutual coupling reduction between antennas. On the other hand, artificial magnetic materials used as magneto-dielectrics have other applications in developing enhanced bandwidth efficient miniaturized antennas, low profile enhanced gain antennas using artificial magnetic superstrates, wide band woodpile Electromagnetic Band Gap (EBG) structures, EBGs with enhanced in-phase reflection bandwidth used as artificial magnetic ground planes. In this thesis, several advances are added to the existing knowledge of developing artificial magnetic materials, in terms of analytical modeling, applications, realization, and experimental characterization. To realize AMMs with miniaturized unit cells, new inclusions based on fractal Hilbert curves are introduced, and analyzed. Analytical models, numerical full wave simulation, and experimental characterization are used to analyze, and study the new structures. A comprehensive comparison is made between the new inclusions, and perviously developed inclusions in terms of electromagnetic properties. The new inclusions have advantages of miniaturization, and less dispersion when compared to the existing structures in the literature. To realize multi-band AMMs, unit cells with multiple inclusions are proposed, designed, and analyzed. The new unit cells can be designed to give the desired magnetic properties either over distinguished multiple frequency bands, or over a single wide frequency band. Numerical full wave simulation is used to verify the proposed concept, and analytical models are provided for design, and optimization of the new unit cells. Unit cells with different configurations are optimized to get a wideband responce for the effective permeability. Space mapping technique is used to provide a link between analytically optimized structures, and full wave numerical simulation results. Two new methods are proposed for experimental characterization of artificial structures using microstrip, and strip line topologies. Using numerical results, the effect of anisotropy on the accuracy of the extracted parameters are investigated, and a fitting solution is proposed, and verified to address this challenge. New structures based on 2nd , and 3rd order fractal Hilbert curves are fabricated, and characterized using microstrip line, and strip line fixtures. Experimental results are presented, and compared with numerical results. The new experimental methods have advantages of lower cost, easier to fabricate and measure, and smaller sample size when compared to the existing methods in the literature. A new application is proposed for use of magnetic materials to develop wide band artificial magnetic conductors (AMC). Analytical models, and numerical analysis is used to validate the concept. A new ultra wideband AMC is designd, and analysed. The designed AMC is used as the ground plane to develop a low profile high gain ultra wide band antenna. The designed antenna is simulated, and its return loss, and gain is presented over a wide range of frequencies. A comprehensive study is presented on the performance of AMMs for the application of miniaturized antennas. A miniaturized antenna, using fractal Hilbert metamaterials as substrate, is fabricated, and measured. Measurement results are presented, and compared with numerical results. A parametric study is presented on the effect of the constitutive parameters of the artificial substrate on the performance of the miniaturized antenna. In this study, the effect of magnetic loss of AMM on the gain, and efficiency of the antenna, as well as the effect of dispersion of AMM on the bandwidth of the antenna is investigated.

Artificial Magnetic Materials (AMMs) are a subgroup of metamaterials which are engineered to provide desirable magnetic properties not seen in natural materials. These artificial structures are designed to provide either negative or enhanced positive (higher than one) relative permeability. AMMs with negative permeability are used to develop Single Negative (SNG), or Double Negative (DNG) metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave frequencies where the natural magnetic materials fail to work efficiently. AMMs are realized by embedding metallic resonators in a host dielectric. These inclusions provide desirable magnetic properties near their resonance frequency. Artificial magnetic materials used as SNG, or DNG have many applications such as: sub-wavelength cavity resonators, sub-wavelength parallel-plate wave guides, sub-wavelength cylindrical and spherical core–shell systems, efficient electrically small dipole antennas, super lenses, THz active devices, sensitivity enhancement near-field probes using double and single negative media, and mutual coupling reduction between antennas. On the other hand, artificial magnetic materials used as magneto-dielectrics have other applications in developing enhanced bandwidth efficient miniaturized antennas, low profile enhanced gain antennas using artificial magnetic superstrates, wide band woodpile Electromagnetic Band Gap (EBG) structures, EBGs with enhanced in-phase reflection bandwidth used as artificial magnetic ground planes. In this thesis, several advances are added to the existing knowledge of developing artificial magnetic materials, in terms of analytical modeling, applications, realization, and experimental characterization. To realize AMMs with miniaturized unit cells, new inclusions based on fractal Hilbert curves are introduced, and analyzed. Analytical models, numerical full wave simulation, and experimental characterization are used to analyze, and study the new structures. A comprehensive comparison is made between the new inclusions, and perviously developed inclusions in terms of electromagnetic properties. The new inclusions have advantages of miniaturization, and less dispersion when compared to the existing structures in the literature. To realize multi-band AMMs, unit cells with multiple inclusions are proposed, designed, and analyzed. The new unit cells can be designed to give the desired magnetic properties either over distinguished multiple frequency bands, or over a single wide frequency band. Numerical full wave simulation is used to verify the proposed concept, and analytical models are provided for design, and optimization of the new unit cells. Unit cells with different configurations are optimized to get a wideband responce for the effective permeability. Space mapping technique is used to provide a link between analytically optimized structures, and full wave numerical simulation results. Two new methods are proposed for experimental characterization of artificial structures using microstrip, and strip line topologies. Using numerical results, the effect of anisotropy on the accuracy of the extracted parameters are investigated, and a fitting solution is proposed, and verified to address this challenge. New structures based on 2nd , and 3rd order fractal Hilbert curves are fabricated, and characterized using microstrip line, and strip line fixtures. Experimental results are presented, and compared with numerical results. The new experimental methods have advantages of lower cost, easier to fabricate and measure, and smaller sample size when compared to the existing methods in the literature. A new application is proposed for use of magnetic materials to develop wide band artificial magnetic conductors (AMC). Analytical models, and numerical analysis is used to validate the concept. A new ultra wideband AMC is designd, and analysed. The designed AMC is used as the ground plane to develop a low profile high gain ultra wide band antenna. The designed antenna is simulated, and its return loss, and gain is presented over a wide range of frequencies. A comprehensive study is presented on the performance of AMMs for the application of miniaturized antennas. A miniaturized antenna, using fractal Hilbert metamaterials as substrate, is fabricated, and measured. Measurement results are presented, and compared with numerical results. A parametric study is presented on the effect of the constitutive parameters of the artificial substrate on the performance of the miniaturized antenna. In this study, the effect of magnetic loss of AMM on the gain, and efficiency of the antenna, as well as the effect of dispersion of AMM on the bandwidth of the antenna is investigated.

Superconducting microelectronics (SME) technology has the potential of realizing very high speed digital receivers capable of performing direct digitization of radio frequency signals with very low power consumption. The SME receiver is implemented on a single chip using Niobium based low temperature superconductive (LTS) Josephson Junction (JJ) technology by HYPRES. Analogue RF filters are still required at the receiver front end and are key components of the overall superconductor digital receiver. SME receivers usually require two types of RF filters; a wideband bandpass filter and a bandstop filter (a notch filter). The notch filter is required to eliminate interference and unwanted signals in the passband. In this thesis, design of highly miniaturized lumped element wideband and bandstop filters is investigated and some challenges are addressed. The filters are fabricated by the HYPRES process and therefore can be integrated with the SME receiver on the same chip. In a wideband filter, the coupling between the adjacent resonators is high. Achieving such a strong coupling is one of the challenges of designing wideband filters. The wideband filters realized with distributed elements usually suffer from very low spurious frequency. As the bandwidth of the filter becomes wider, the spurious peak of the second harmonic gets closer to the passband of the filter. In the first part of this work, the possibility of realizing lumped element superconducting bandpass filters (BPF) with a relative bandwidth of 80% is investigated. In the second part of the thesis, design and realization of lumped element superconducting bandstop filters (BSF) is discussed. The challenge for designing a bandstop filter is providing a good match over a wide frequency range. So narrowband inverters cannot be used. Instead, usually λ/4 matched transmission lines provide 90° phase shift between the resonators of a notch filter. The possibility of replacing the long transmission line with other means or eliminating the inverters and using both shunt and series resonators are investigated. Having both series and shunt resonators introduces some new challenges that are addressed in the thesis and discussed thoroughly. A tunable notch resonator is presented. The tunability is provided by a superconducting MEMS varactor that is realized in our group by doing some post processing on the device fabricated by HYPRES. The tunability range of the device at cryogenic temperatures is investigated. A 3-pole tunable BSF is also designed that uses the same tunable resonators. The tunability of the filter is investigated through simulation.