A procura de novas escalas de simples utilização para mensurar a função motora é um objetivo comum aos centros de atendimento de doenças neuromusculares. A nova escala de avaliação MFM (Bèrard et al., 2005), validada no Brasil por Iwabe et al. (2008), foi aplicada em 33 pacientes com DMD, com idades entre seis e dezesseis anos, cadeirantes e deambulantes, que estavam em seguimento no ambulatório de doenças neuromusculares do HCFMUSP, recebendo corticoterapia. Os objetivos foram: verificar a aplicabilidade da escala e analisar a evolução da função motora dos pacientes com DMD em corticoterapia. Os pacientes foram avaliados em cinco visitas ao longo de um período de aproximadamente 18 meses (V0, V1, V2, V3, V4 e V5). A V0 correspondeu à avaliação inicial antes do início da corticoterapia, ocorrendo um intervalo de tempo de aproximadamente três meses até a V2. Entre V3, V4 e V5, o intervalo de tempo foi de quatro meses. A MFM avalia três dimensões: D1, relativa à posição ereta e transferências, com 13 itens; D2, relativa à motricidade proximal e axial, com 12 itens; D3 que refere-se à motricidade distal, com sete itens, e o escore total que engloba todas as três dimensões. A fim de analisar funções motoras especificas de acordo com a fase de evolução da doença, foram constituídos três grupos de pacientes: deambulantes, cadeirantes e pacientes que perderam a marcha ao longo do seguimento. Os resultados demonstraram que nos pacientes deambulantes ocorreu manutenção do quadro motor até 10 a 14 meses após início do tratamento na D1 e escore MFM total. Notou-se melhora da função motora de D2 nos primeiros seis meses, com conseqüente piora após 14 meses, e ganhos funcionais para D3 em todo o seguimento. Nos pacientes que perderam a marcha e cadeirantes ocorreram perdas funcionais nas últimas visitas, exceto para a motricidade distal (D3) que se manteve estável ao longo de todo o seguimento de 18 meses. Concluímos que a escala MFM demonstra-se eficaz para monitorar a evolução da doença, valorizando períodos de melhora, assim como de estabilidade funcional frente a tratamentos específicos, detectando alterações a curto prazo, e assim facilitando a adoção de intervenções adequadas ao momento da reavaliação do paciente. A D1 da escala MFM demonstra-se adequada no acompanhamento dos pacientes que mantêm a marcha, sendo útil para prever perdas futuras da função motora do paciente com DMD / The research for new simple evaluation scales has been a common aim among neuromuscular disease rehabilitation centers. We used the new MFM scale (Bèrard et al., 2005), which was validated in Brazil by Iwabe et al. (2008) to evaluate 33 patients with DMD aged 6-16 years, both ambulant and non-ambulant. All of them were receiving corticosteroid treatment in neuromuscular disorder center at HCFMUSP. Objectives: to verify the MFM scale applicability and to analyze the motor function evolution in DMD patients treated by corticosteroids. The patients were evaluated through five visits spread out over a period of about 18 months (V0, V1, V2, V3, V4 e V5). The V0 was related to evaluation before the beginning of corticosteroids treatment at intervals of about 3 months until V2. The interval time among V3, V4 and V5 was about 4 months. The MFM scale evaluates 3 dimensions: D1, relates to standing and transfers by 13 items; D2, related to axial and proximal motor capacity by 12 items; D3 related to distal motor capacity by 7 items and the total score which includes all of the three dimensions. In order to analyze the specific motor function according to the evaluation stage, the patients were divided into 3 groups: ambulatory, non-ambulatory and those who lost the ability to walk during the study. The results showed that there was stability in the ambulatory motor function patients about 10-14 months after the beginning of corticosteroids treatment in D1 and total score MFM. We saw improvements in D2 for the first six months followed by some loss after 14 months, and improvement for D3 during all the study. In those patients who lost the ability to walk and were non-ambulatory, there was functional loss in the last visits, except for distal motor capacity (D3), which kept stable during 18 months. We conclude that the MFM scale is an effective tool for detecting the disease progression showing some improvements periods as well as the stability moments due to specifics treatments. It is possible to detect changes in a short interval which helps the choices for the adequate management at the patients revaluation. The D1 subscore of MFM scale shows to be appropriate in monitoring ambulant patients, which is useful for predicting future loss of motor function of patients with DMD

Magnetic permalloy nanostructures were fabricated onto a silicon wafer using electron beam lithography and a liftoff process. The lithography was performed with a Hitachi SU-70 SEM retrofitted with a Nabity NPGS lithography conversion kit. PMMA of 950kDa molecular weight was used as the photoresist. Features were either nanowires, nanodots, or elliptical or rectangular nanostructures. The nanowires had dimensions of 15µm x 200nm x 40nm, the nanodots had diameters of 145nm and thickness of 12nm, and the ellipses and rectangles had dimensions of 110nm x 50nm x 13nm. Characterization of the nanostructures was performed using the same Hitachi SEM as well as a Digital Instruments DI 3100 Nanoscope IIIa AFM used in magnetic force imaging mode. The SEM was used to measure lateral dimensions of the features and to capture images of features for proper documentation and for external simulation studies. The MFM was used to capture magnetic images of the samples to determine the magnetic state of the nanowires or arrays.

<p>The magnetic properties of transition metal compounds have been studied using SQUID-magnetometry, magnetic force microscopy and Lorentz transmission electron microscopy. New magnetic materials have been found and their magnetic properties have been determined. How the magnetic properties of a material can be changed through e.g. chemical substitution of magnetic and nonmagnetic atoms and shape and size effects have also been studied. Three different sets of samples have been investigated: three new Mn-compounds, two substitution series of layered magnetic structures and ferromagnetic micronsized thin film elements.</p><p>The three Mn-compounds, Mn₃IrSi, IrMnSi and Mn₈Pd₁₅Si₇, show different magnetic ordering. Mn₃IrSi orders 'antiferromagnetically' at 210 K. IrMnSi forms a double cycloidal spin spiral below 460 K. Mn₈Pd₁₅Si₇ only shows short-range magnetic ordering.</p><p>Substituting Se with S in TlCo₂Se_2-xS_x changes the magnetic order from a spin spiral to a colinear ferromagnet for a composition of <i>x</i>=1.75. An intermediate region exists where the compound is neither a pure ferromagnet, nor purely a spin spiral, as evidenced by the magnetization versus field measurements for the <i>x</i>=1.3 and 1.5 samples. This is also seen in the temperature dependent susceptibility measurements. For the TlCu_2-xFe_xSe₂ compounds it was found that the ordering temperature and saturation magnetic moment per Fe-atom changed with composition <i>x</i>.</p><p>Ferromagnetic micronsized thin film elements in permalloy, Fe₂₀Ni₈₀, and epitaxial Fe/Co multilayers were studied. For the Fe/Co multilayer thin film elements it was found that it is possible to change the magnetization reversal process, by aligning the easy shape anisotropy axis with either the easy or the hard magnetocrystalline anisotropy axis. In the permalloy elements the effect of inter-elemental distance was found to determine the interval of fields where multidomain states were stable, so that for shorter inter-elemental distances multidomain states were stable for a shorter interval of fields. The domain structure of permalloy elements in rotating magnetic fields was also studied. Higher applied fields led to a broader interval of angles in which saturated states were stable.</p>

The local corrosion behavior of duplex stainless steel (DSS)is affected by a wide variety of factors. Localized corrosionof DSS frequently starts at micrometer scale inclusions orprecipitates, which are often segregated in theaustenite-ferrite boundary regions. Moreover, due to thepartitioning of the key alloying elements of ferrite (Cr andMo) and austenite (N and Ni), the local interactions betweenthe phases must also be considered. The aim of this doctoral study was to increase the knowledgeabout the local dissolution behavior of DSS in acidic-chlorideenvironments. The recent developments of new local probingtechniques have opened a new frontier in corrosion science,providing valuable local information not accessible in thepast. The local techniques used include electrochemicalscanning tunneling microscopy (EC-STM), scanning probe forcemicroscopy (SKPFM), magnetic force microscopy (MFM), andscanning Auger electron Spectroscopy (SAES), all withmicrometer or sub-micrometer resolution. With EC-STM, it was possible to monitor local dissolutionprocesses on DSS in situ, and in real time. MFM was capable ofimaging the phase distribution in DSS without the need of thetraditional surface etching, while SKPFM revealed that theVolta potential difference between the two phases wasmeasurable and significant. SAES showed that the compositiongradient at the phase boundaries is narrower than 2µm. Different types of DSSs have been studied, from low-alloyedDSS to superduplex. Higher contents of Cr, Mo and Nstrengthened both phases as well as the phase boundaries,resulting in phases having similar corrosion resistance thatshowed a more uniform dissolution behavior. However, the Voltapotential difference between the phases proved to be of thesame order for all the DSSs studied. Austenite was in generalassociated to regions displaying a more noble Volta potentialthan ferrite, resulting in a higher dissolution rate of theferrite next to the austenite phase. <b>Key words:</b>In situ, local dissolution, electrochemical,STM, SKPFM, MFM, SAES, duplex stainless steel, acidic-chloridesolution.

A microwave reflection method has been used to measure the spin excitations corresponding to the translational mode of magnetic vortices in samples containing either one or two vortices. Experimental findings are complemented by micromagnetic simulations. One-vortex systems are investigated in micron-sized circular and elliptical cylinders. For ellipses, the resonance frequency can effectively be tuned by applying static magnetic fields and the field dependence of the frequency is significant for fields applied along the short axes but negligible when applied along the long axes of the ellipses. This is contrary to the circular case, where virtually no field dependence was found. This can be understood by considering the shape of the vortex potential well. Further, it is found that the resonance frequency is independent on the direction of the excitation field for the one-vortex systems. Ellipses containing two interacting vortices are also investigated. It is shown that the relative vortex core polarizations dominate the vortex translational mode and cause, in the case of opposite polarizations, a dependence on the excitation field direction. For parallel core polarizations, no dependence on the excitation field direction is found. The dependence of the resonance frequencies on applied static fields along the long and short axes are also experimentally mapped out and compared with micromagnetic simulations, where the possible eigenmodes are determined. Another section of the thesis introduces the dawning of a device based on patterned magnetic elliptical elements for the manipulation and movement of magnetic particles on a surface. The controlled movement and separation of individual particles are successfully demonstrated. Contributions to micromagnetic standard problems and simulations on magnetization switching in nanoscale particles have also been performed. The standard problems highlight some important aspects of choosing the discretization cell sizes and the finite temperature simulations show that thermal fluctuations can alter the magnetization reversal paths.

Imaging of current in internal conductors through magnetic field detection by magnetic force microscopy (MFM) is of growing interest in the analysis of integrated circuits (ICs). This thesis presents a systematic study of the MFM based mapping of current in model circuits by using force and force gradient techniques. In comparing these two techniques, force was found to have a much higher signal to noise ratio (from ~150 to ~580 times) than force gradient at large tip-sample distances considering the presence of thick overlayers in ICs. As a result, force will have better sensitivity and can therefore be used to detect much smaller minimum currents. We have achieved a sensitivity of ~0.64 µA per square-root Hertz in air and ~0.095 µA per squre-root Hertz in vacuum for force with a pinning field with a probe-circuit separation of 1.0 µm. We conclude that the force technique is superior for the application of MFM current imaging of buried conductors, albeit with reduced spatial resolution. Numerical modeling of the MFM images has shown that the simple point probe approximation is insufficient to model MFM images. An extended model, which considers realistic MFM probe geometries and the forces acting on the whole probe, has been shown to be necessary. Qualitative and quantitative comparisons of the experimental and simulation results with this model are in agreement to within experimental uncertainty. The comparisons suggested that the CoCr film thickness is not uniform on the probe, which was verified by scanning electron microscope cross-section images of the probes cut by a focused ion beam. Most notably, the CoCr film was 1.5 times thicker on the cantilever than on the tip. Based on the simulation and experimental results, we have devised a method to accurately locate the current path from MFM images with submicrometer uncertainty. The method was tested for different patterns of model conducting lines. It was shown to be a useful technique for fault location in IC failure analysis when current flows through the devices buried under overlayers and no topographic features are on the surface to provide clues about the positions of the devices. / October 2007

<p>The local corrosion behavior of duplex stainless steel (DSS)is affected by a wide variety of factors. Localized corrosionof DSS frequently starts at micrometer scale inclusions orprecipitates, which are often segregated in theaustenite-ferrite boundary regions. Moreover, due to thepartitioning of the key alloying elements of ferrite (Cr andMo) and austenite (N and Ni), the local interactions betweenthe phases must also be considered.</p><p>The aim of this doctoral study was to increase the knowledgeabout the local dissolution behavior of DSS in acidic-chlorideenvironments. The recent developments of new local probingtechniques have opened a new frontier in corrosion science,providing valuable local information not accessible in thepast. The local techniques used include electrochemicalscanning tunneling microscopy (EC-STM), scanning probe forcemicroscopy (SKPFM), magnetic force microscopy (MFM), andscanning Auger electron Spectroscopy (SAES), all withmicrometer or sub-micrometer resolution.</p><p>With EC-STM, it was possible to monitor local dissolutionprocesses on DSS in situ, and in real time. MFM was capable ofimaging the phase distribution in DSS without the need of thetraditional surface etching, while SKPFM revealed that theVolta potential difference between the two phases wasmeasurable and significant. SAES showed that the compositiongradient at the phase boundaries is narrower than 2µm.</p><p>Different types of DSSs have been studied, from low-alloyedDSS to superduplex. Higher contents of Cr, Mo and Nstrengthened both phases as well as the phase boundaries,resulting in phases having similar corrosion resistance thatshowed a more uniform dissolution behavior. However, the Voltapotential difference between the phases proved to be of thesame order for all the DSSs studied. Austenite was in generalassociated to regions displaying a more noble Volta potentialthan ferrite, resulting in a higher dissolution rate of theferrite next to the austenite phase.</p><p><b>Key words:</b>In situ, local dissolution, electrochemical,STM, SKPFM, MFM, SAES, duplex stainless steel, acidic-chloridesolution.</p>

The high degree of modification through chemical substitution afforded by the perovskite crystal structure and its related counterparts allows a systematic study of structure-property relationships critical to understand the wide variety of exotic phenomena observed in these materials where the spin, charge, orbital, and lattice degrees of freedom are highly correlated. From the multiple phenomena observed in these materials, which includes multiferroicity, catalytic activity, and high temperature superconductivity, this study is concerned with a material that displays colossal magnetoresistance (CMR), La₂₋₂xSr₁₊₂xMn₂O₇; this is a naturally bilayered manganite that exhibits CMR at a paramagnetic to ferromagnetic transition that coincides with an insulator to metal transition. The strong correlation between different degrees of freedom in the material leads to considerable variation in its magnetic properties due to doping even in the small range studied of 0.32 [less than or equal to] x [less than or equal to] 0.4, where the easy axis of magnetization changes from the c-axis to the ab plane. Magnetic force microscopy (MFM) was used for this part of the work, to visualize the local variation of the out of plane (c-axis) magnetization or magnetic microstructure of La₂₋₂xSr₁₊₂xMn₂O₇ for 0.32 [less than or equal to] x [less than or equal to] 0.4 at the exposed ab surface and its evolution due to an applied magnetic field at 4 K. For the x = 0.32 composition, which is close to the out of plane to in plane magnetization transition, a strong preferred magnetization direction within the ab plane or magnetocrystalline anisotropy was observed. The stray magnetic field of the MFM tip perturbs the magnetic microstructure of low coercivity materials like diluted magnetic semiconductors, making it unsuitable for the study of such materials. For this reason, as part of this project a scanning Hall probe microscope (SHPM), a magnetic imaging technique complementary to MFM that uses a Hall sensor that provides a magnetically non-invasive calibrated measurement of the stray fields at the surface of a sample with good resolution (~ 1 [micrometer]), was designed. The construction of a compact cryogenic variable-temperature (77 - 300 K) SHPM, highlighting its features, is described. / text

The magnetic properties of transition metal compounds have been studied using SQUID-magnetometry, magnetic force microscopy and Lorentz transmission electron microscopy. New magnetic materials have been found and their magnetic properties have been determined. How the magnetic properties of a material can be changed through e.g. chemical substitution of magnetic and nonmagnetic atoms and shape and size effects have also been studied. Three different sets of samples have been investigated: three new Mn-compounds, two substitution series of layered magnetic structures and ferromagnetic micronsized thin film elements. The three Mn-compounds, Mn3IrSi, IrMnSi and Mn8Pd15Si7, show different magnetic ordering. Mn3IrSi orders 'antiferromagnetically' at 210 K. IrMnSi forms a double cycloidal spin spiral below 460 K. Mn8Pd15Si7 only shows short-range magnetic ordering. Substituting Se with S in TlCo2Se2-xSx changes the magnetic order from a spin spiral to a colinear ferromagnet for a composition of x=1.75. An intermediate region exists where the compound is neither a pure ferromagnet, nor purely a spin spiral, as evidenced by the magnetization versus field measurements for the x=1.3 and 1.5 samples. This is also seen in the temperature dependent susceptibility measurements. For the TlCu2-xFexSe2 compounds it was found that the ordering temperature and saturation magnetic moment per Fe-atom changed with composition x. Ferromagnetic micronsized thin film elements in permalloy, Fe20Ni80, and epitaxial Fe/Co multilayers were studied. For the Fe/Co multilayer thin film elements it was found that it is possible to change the magnetization reversal process, by aligning the easy shape anisotropy axis with either the easy or the hard magnetocrystalline anisotropy axis. In the permalloy elements the effect of inter-elemental distance was found to determine the interval of fields where multidomain states were stable, so that for shorter inter-elemental distances multidomain states were stable for a shorter interval of fields. The domain structure of permalloy elements in rotating magnetic fields was also studied. Higher applied fields led to a broader interval of angles in which saturated states were stable.

Imaging of current in internal conductors through magnetic field detection by magnetic force microscopy (MFM) is of growing interest in the analysis of integrated circuits (ICs). This thesis presents a systematic study of the MFM based mapping of current in model circuits by using force and force gradient techniques. In comparing these two techniques, force was found to have a much higher signal to noise ratio (from ~150 to ~580 times) than force gradient at large tip-sample distances considering the presence of thick overlayers in ICs. As a result, force will have better sensitivity and can therefore be used to detect much smaller minimum currents. We have achieved a sensitivity of ~0.64 µA per square-root Hertz in air and ~0.095 µA per squre-root Hertz in vacuum for force with a pinning field with a probe-circuit separation of 1.0 µm. We conclude that the force technique is superior for the application of MFM current imaging of buried conductors, albeit with reduced spatial resolution. Numerical modeling of the MFM images has shown that the simple point probe approximation is insufficient to model MFM images. An extended model, which considers realistic MFM probe geometries and the forces acting on the whole probe, has been shown to be necessary. Qualitative and quantitative comparisons of the experimental and simulation results with this model are in agreement to within experimental uncertainty. The comparisons suggested that the CoCr film thickness is not uniform on the probe, which was verified by scanning electron microscope cross-section images of the probes cut by a focused ion beam. Most notably, the CoCr film was 1.5 times thicker on the cantilever than on the tip. Based on the simulation and experimental results, we have devised a method to accurately locate the current path from MFM images with submicrometer uncertainty. The method was tested for different patterns of model conducting lines. It was shown to be a useful technique for fault location in IC failure analysis when current flows through the devices buried under overlayers and no topographic features are on the surface to provide clues about the positions of the devices.