Output Impedance Correction Circuit (OICC): A New Concept to Improve the Dynamic Response of DC/DC Converters with Additional Energy Path

El desarrollo da las nuevas tecnologías permite a los ingenieros llevar al límite el funcionamiento de los circuitos integrados (Integrated Circuits, IC). Las nuevas generaciones de procesadores, DSPs o FPGAs son capaces de procesar la información a una alta velocidad, con un alto consumo de energía, o esperar en modo de baja potencia con el mínimo consumo posible. Esta gran variación en el consumo de potencia y el corto tiempo necesario para cambiar de un nivel al otro, afecta a las especificaciones del Módulo de Regulador de Tensión (Voltage Regulated Module, VRM) que alimenta al IC. Además, las características adicionales obligatorias, tales como adaptación del nivel de tensión (Adaptive Voltage Positioning, AVP) y escalado dinámico de la tensión (Dynamic Voltage Scaling, DVS), imponen requisitos opuestas en el diseño de la etapa de potencia del VRM. Para poder soportar las altas variaciones de los escalones de carga, el condensador de filtro de salida del VRM se ha de sobredimensionar, penalizando la densidad de energía y el rendimiento durante la operación de DVS. Por tanto, las actuales tendencias de investigación se centran en mejorar la respuesta dinámica del VRM, mientras se reduce el tamaño del condensador de salida. La reducción del condensador de salida lleva a menor coste y una prolongación de la vida del sistema ya que se podría evitar el uso de condensadores voluminosos, normalmente implementados con condensadores OSCON. Una ventaja adicional es que reduciendo el condensador de salida, el DVS se puede realizar más rápido y con menor estrés de la etapa de potencia, ya que la cantidad de carga necesaria para cambiar la tensión de salida es menor. El comportamiento dinámico del sistema con un control lineal (Control Modo Tensión, VMC, o Control Corriente de Pico, Peak Current Mode Control, PCMC,…) está limitado por la frecuencia de conmutación del convertidor y por el tamaño del filtro de salida. La reducción del condensador de salida se puede lograr incrementando la frecuencia de conmutación, así como incrementando el ancho de banda del sistema, y/o aplicando controles avanzados no-lineales. Usando esos controles, las variables del estado se saturan para conseguir el nuevo régimen permanente en un tiempo mínimo, así como el filtro de salida, más específicamente la pendiente de la corriente de la bobina, define la respuesta de la tensión de salida. Por tanto, reduciendo la inductancia de la bobina de salida, la corriente de bobina llega más rápido al nuevo régimen permanente, por lo que una menor cantidad de carga es tomada del condensador de salida durante el tránsito. El inconveniente de esa propuesta es que el rendimiento del sistema es penalizado debido al incremento de pérdidas de conmutación y las corrientes RMS. Para conseguir tanto la reducción del condensador de salida como el alto rendimiento del sistema, mientras se satisfacen las estrictas especificaciones dinámicas, un convertidor multifase es adoptado como estándar para aplicaciones VRM. Para asegurar el reparto de las corrientes entre fases, el convertidor multifase se suele implementar con control de modo de corriente. Para superar la limitación impuesta por el filtro de salida, la segunda posibilidad para reducir el condensador de salida es aplicar alguna modificación topológica (Topologic modifications) de la etapa básica de potencia para incrementar la pendiente de la corriente de bobina y así reducir la duración de tránsito. Como el transitorio se ha reducido, una menor cantidad de carga es tomada del condensador de salida bajo el mismo escalón de la corriente de salida, con lo cual, el condensador de salida se puede reducir para lograr la misma desviación de la tensión de salida. La tercera posibilidad para reducir el condensador de salida del convertidor es introducir un camino auxiliar de energía (additional energy path, AEP) para compensar el desequilibrio de la carga del condensador de salida reduciendo consecuentemente la duración del transitorio y la desviación de la tensión de salida. De esta manera, durante el régimen permanente, el sistema tiene un alto rendimiento debido a que el convertidor principal con bajo ancho de banda es diseñado para trabajar con una frecuencia de conmutación moderada para conseguir requisitos estáticos. Por otro lado, el comportamiento dinámico durante los transitorios es determinado por el AEP con un alto ancho de banda. El AEP puede ser implementado como un camino resistivo, como regulador lineal (Linear regulator, LR) o como un convertidor conmutado. Las dos primeras implementaciones proveen un mayor ancho de banda, acosta del incremento de pérdidas durante el transitorio. Por otro lado, la implementación del convertidor computado presenta menor ancho de banda, limitado por la frecuencia de conmutación, aunque produce menores pérdidas comparado con las dos anteriores implementaciones. Dependiendo de la aplicación, la implementación y la estrategia de control del sistema, hay una variedad de soluciones propuestas en el Estado del Arte (State-of-the-Art, SoA), teniendo diferentes propiedades donde una solución ofrece más ventajas que las otras, pero también unas desventajas. En general, un sistema con AEP ideal debería tener las siguientes propiedades: 1. El impacto del AEP a las pérdidas del sistema debería ser mínimo. A lo largo de la operación, el AEP genera pérdidas adicionales, con lo cual, en el caso ideal, el AEP debería trabajar por un pequeño intervalo de tiempo, solo durante los tránsitos; la otra opción es tener el AEP constantemente activo pero, por la compensación del rizado de la corriente de bobina, se generan pérdidas innecesarias. 2. El AEP debería ser activado inmediatamente para minimizar la desviación de la tensión de salida. Para conseguir una activación casi instantánea, el sistema puede ser informado por la carga antes del escalón o el sistema puede observar la corriente del condensador de salida, debido a que es la primera variable del estado que actúa a la perturbación de la corriente de salida. De esa manera, el AEP es activado con casi cero error de la tensión de salida, logrando una menor desviación de la tensión de salida. 3. El AEP debería ser desactivado una vez que el nuevo régimen permanente es detectado para evitar los transitorios adicionales de establecimiento. La mayoría de las soluciones de SoA estiman la duración del transitorio, que puede provocar un transitorio adicional si la estimación no se ha hecho correctamente (por ejemplo, si la corriente de bobina del convertidor principal tiene un nivel superior o inferior al necesitado, el regulador lento del convertidor principal tiene que compensar esa diferencia una vez que el AEP es desactivado). Otras soluciones de SoA observan las variables de estado, asegurando que el sistema llegue al nuevo régimen permanente, o pueden ser informadas por la carga. 4. Durante el transitorio, como mínimo un subsistema, o bien el convertidor principal o el AEP, debería operar en el lazo cerrado. Implementando un sistema en el lazo cerrado, preferiblemente el subsistema AEP por su ancho de banda elevado, se incrementa la robustez del sistema a los parásitos. Además, el AEP puede operar con cualquier tipo de corriente de carga. Las soluciones que funcionan en el lazo abierto suelen preformar el control de balance de carga con mínimo tiempo, así reducen la duración del transitorio y tienen un impacto menor a las pérdidas del sistema. Por otro lado, esas soluciones demuestran una alta sensibilidad a las tolerancias y parásitos de los componentes. 5. El AEP debería inyectar la corriente a la salida en una manera controlada, así se reduce el riesgo de unas corrientes elevadas y potencialmente peligrosas y se incrementa la robustez del sistema bajo las perturbaciones de la tensión de entrada. Ese problema suele ser relacionado con los sistemas donde el AEP es implementado como un convertidor auxiliar. El convertidor auxiliar es diseñado para una potencia baja, con lo cual, los dispositivos elegidos son de baja corriente/potencia. Si la corriente no es controlada, bajo un pico de tensión de entrada provocada por otro parte del sistema (por ejemplo, otro convertidor conectado al mismo bus), se puede llegar a un pico en la corriente auxiliar que puede causar la perturbación de tensión de salida e incluso el fallo de los dispositivos del convertidor auxiliar. Sin embargo, cuando la corriente es controlada, usando control del pico de corriente o control con histéresis, la corriente auxiliar tiene el control con prealimentación (feed-forward) de tensión de entrada y la corriente es definida y limitada. Por otro lado, si la solución utiliza el control de balance de carga, el sistema puede actuar de forma deficiente si la tensión de entrada tiene un valor diferente del nominal, provocando que el AEP inyecta/toma más/menos carga que necesitada. 6. Escalabilidad del sistema a convertidores multifase. Como ya ha sido comentado anteriormente, para las aplicaciones VRM por la corriente de carga elevada, el convertidor principal suele ser implementado como multifase para distribuir las perdidas entre las fases y bajar el estrés térmico de los dispositivos. Para asegurar el reparto de las corrientes, normalmente un control de modo corriente es usado. Las soluciones de SoA que usan VMC son limitadas a la implementación con solo una fase. Esta tesis propone un nuevo método de control del flujo de energía por el AEP y el convertidor principal. El concepto propuesto se basa en la inyección controlada de la corriente auxiliar al nodo de salida donde la amplitud de la corriente es n-1 veces mayor que la corriente del condensador de salida con las direcciones apropiadas. De esta manera, el AEP genera un condensador virtual cuya capacidad es n veces mayor que el condensador físico y reduce la impedancia de salida. Como el concepto propuesto reduce la impedancia de salida usando el AEP, el concepto es llamado Output Impedance Correction Circuit (OICC) concept. El concepto se desarrolla para un convertidor tipo reductor síncrono multifase con control modo de corriente CMC (incluyendo e implementación con una fase) y puede operar con la tensión de salida constante o con AVP. Además, el concepto es extendido a un convertidor de una fase con control modo de tensión VMC. Durante la operación, el control de tensión de salida de convertidor principal y control de corriente del subsistema OICC están siempre cerrados, incrementando la robustez a las tolerancias de componentes y a los parásitos del cirquito y permitiendo que el sistema se pueda enfrentar a cualquier tipo de la corriente de carga. Según el método de control propuesto, el sistema se puede encontrar en dos estados: durante el régimen permanente, el sistema se encuentra en el estado Idle y el subsistema OICC esta desactivado. Por otro lado, durante el transitorio, el sistema se encuentra en estado Activo y el subsistema OICC está activado para reducir la impedancia de salida. El cambio entre los estados se hace de forma autónoma: el sistema entra en el estado Activo observando la corriente de condensador de salida y vuelve al estado Idle cunado el nuevo régimen permanente es detectado, observando las variables del estado. La validación del concepto OICC es hecha aplicándolo a un convertidor tipo reductor síncrono con dos fases y de 30W cuyo condensador de salida tiene capacidad de 140μF, mientras el factor de multiplicación n es 15, generando en el estado Activo el condensador virtual de 2.1mF. El subsistema OICC es implementado como un convertidor tipo reductor síncrono con PCMC. Comparando el funcionamiento del convertidor con y sin el OICC, los resultados demuestran que se ha logrado una reducción de la desviación de tensión de salida con factor 12, tanto con funcionamiento básico como con funcionamiento AVP. Además, los resultados son comparados con un prototipo de referencia que tiene la misma etapa de potencia y un condensador de salida físico de 2.1mF. Los resultados demuestran que los dos sistemas tienen el mismo comportamiento dinámico. Más aun, se ha cuantificado el impacto en las pérdidas del sistema operando bajo una corriente de carga pulsante y bajo DVS. Se demuestra que el sistema con OICC mejora el rendimiento del sistema, considerando las pérdidas cuando el sistema trabaja con la carga pulsante y con DVS. Por lo último, el condensador de salida de sistema con OICC es mucho más pequeño que el condensador de salida del convertidor de referencia, con lo cual, por usar el concepto OICC, la densidad de energía se incrementa. En resumen, las contribuciones principales de la tesis son: • El concepto propuesto de Output Impedance Correction Circuit (OICC), • El control a nivel de sistema basado en el método usado para cambiar los estados de operación, • La implementación del subsistema OICC en lazo cerrado conjunto con la implementación del convertidor principal, • La cuantificación de las perdidas dinámicas bajo la carga pulsante y bajo la operación DVS, y • La robustez del sistema bajo la variación del condensador de salida y bajo los escalones de carga consecutiva. ABSTRACT Development of new technologies allows engineers to push the performance of the integrated circuits to its limits. New generations of processors, DSPs or FPGAs are able to process information with high speed and high consumption or to wait in low power mode with minimum possible consumption. This huge variation in power consumption and the short time needed to change from one level to another, affect the specifications of the Voltage Regulated Module (VRM) that supplies the IC. Furthermore, additional mandatory features, such as Adaptive Voltage Positioning (AVP) and Dynamic Voltage Scaling (DVS), impose opposite trends on the design of the VRM power stage. In order to cope with high load-step amplitudes, the output capacitor of the VRM power stage output filter is drastically oversized, penalizing power density and the efficiency during the DVS operation. Therefore, the ongoing research trend is directed to improve the dynamic response of the VRM while reducing the size of the output capacitor. The output capacitor reduction leads to a smaller cost and longer life-time of the system since the big bulk capacitors, usually implemented with OSCON capacitors, may not be needed to achieve the desired dynamic behavior. An additional advantage is that, by reducing the output capacitance, dynamic voltage scaling (DVS) can be performed faster and with smaller stress on the power stage, since the needed amount of charge to change the output voltage is smaller. The dynamic behavior of the system with a linear control (Voltage mode control, VMC, Peak Current Mode Control, PCMC,…) is limited by the converter switching frequency and filter size. The reduction of the output capacitor can be achieved by increasing the switching frequency of the converter, thus increasing the bandwidth of the system, and/or by applying advanced non-linear controls. Applying nonlinear control, the system variables get saturated in order to reach the new steady-state in a minimum time, thus the output filter, more specifically the output inductor current slew-rate, determines the output voltage response. Therefore, by reducing the output inductor value, the inductor current reaches faster the new steady state, so a smaller amount of charge is taken from the output capacitor during the transient. The drawback of this approach is that the system efficiency is penalized due to increased switching losses and RMS currents. In order to achieve both the output capacitor reduction and high system efficiency, while satisfying strict dynamic specifications, a Multiphase converter system is adopted as a standard for VRM applications. In order to ensure the current sharing among the phases, the multiphase converter is usually implemented with current mode control. In order to overcome the limitation imposed by the output filter, the second possibility to reduce the output capacitor is to apply Topologic modifications of the basic power stage topology in order to increase the slew-rate of the inductor current and, therefore, reduce the transient duration. Since the transient is reduced, smaller amount of charge is taken from the output capacitor under the same load current, thus, the output capacitor can be reduced to achieve the same output voltage deviation. The third possibility to reduce the output capacitor of the converter is to introduce an additional energy path (AEP) to compensate the charge unbalance of the output capacitor, consequently reducing the transient time and output voltage deviation. Doing so, during the steady-state operation the system has high efficiency because the main low-bandwidth converter is designed to operate at moderate switching frequency, to meet the static requirements, whereas the dynamic behavior during the transients is determined by the high-bandwidth auxiliary energy path. The auxiliary energy path can be implemented as a resistive path, as a Linear regulator, LR, or as a switching converter. The first two implementations provide higher bandwidth, at the expense of increasing losses during the transient. On the other hand, the switching converter implementation presents lower bandwidth, limited by the auxiliary converter switching frequency, though it produces smaller losses compared to the two previous implementations. Depending on the application, the implementation and the control strategy of the system, there is a variety of proposed solutions in the State-of-the-Art (SoA), having different features where one solution offers some advantages over the others, but also some disadvantages. In general, an ideal additional energy path system should have the following features: 1. The impact on the system losses should be minimal. During its operation, the AEP generates additional losses, thus ideally, the AEP should operate for a short period of time, only when the transient is occurring; the other option is to have the AEP constantly on, but due to the inductor current ripple compensation at the output, unnecessary losses are generated. 2. The AEP should be activated nearly instantaneously to prevent bigger output voltage deviation. To achieve near instantaneous activation, the converter system can be informed by the load prior to the load-step or the system can observe the output capacitor current, which is the first system state variable that reacts on the load current perturbation. In this manner, the AEP is turned on with near zero output voltage error, providing smaller output voltage deviation. 3. The AEP should be deactivated once the new steady state is reached to avoid additional settling transients. Most of the SoA solutions estimate duration of the transient which may cause additional transient if the estimation is not performed correctly (e.g. if the main converter inductor current has higher or lower value than needed, the slow regulator of the main converter needs to compensate the difference after the AEP is deactivated). Other SoA solutions are observing state variables, ensuring that the system reaches the new steady state or they are informed by the load. 4. During the transient, at least one subsystem, either the main converter or the AEP, should be in closed-loop. Implementing a closed loop system, preferably the AEP subsystem, due its higher bandwidth, increases the robustness under system tolerances and circuit parasitic. In addition, the AEP can operate with any type of load. The solutions that operate in open loop usually perform minimum time charge balance control, thus reducing the transient length and minimizing the impact on the losses, however they are very sensitive to tolerances and parasitics. 5. The AEP should inject current at the output in a controlled manner, thus reducing the risk of high and potentially damaging currents and increasing robustness on the input voltage deviation. This issue is mainly related to the systems where AEP is implemented as auxiliary converter. The auxiliary converter is designed for small power and, as such, the MOSFETs are rated for small power/currents. If the current is not controlled, due to the some unpredicted spike in input voltage caused by some other part of the system (e.g. different converter), it may lead to a current spike in auxiliary current which will cause the perturbation of the output voltage and even failure of the switching components of auxiliary converter. In the case when the current is controlled, using peak CMC or Hysteretic Window CMC, the auxiliary converter has inherent feed-forwarding of the input voltage in current control and the current is defined and limited. Furthermore, if the solution employs charge balance control, the system may perform poorly if the input voltage has different value than the nominal, causing that AEP injects/extracts more/less charge than needed. 6. Scalability of the system to multiphase converters. As commented previously, in VRM applications, due to the high load currents, the main converters are implemented as multiphase to redistribute losses among the modules, lowering temperature stress of the components. To ensure the current sharing, usually a Current Mode Control (CMC) is employed. The SoA solutions that are implemented with VMC are limited to a single stage implementation. This thesis proposes a novel control method of the energy flow through the AEP and the main converter system. The proposed concept relays on a controlled injection of the auxiliary current at the output node where the instantaneous current value is n-1 times bigger than the output capacitor current with appropriate directions. Doing so, the AEP creates an equivalent n times bigger virtual capacitor at the output, thus reducing the output impedance. Due to the fact that the proposed concept reduces the output impedance using the AEP, it has been named the Output Impedance Correction Circuit (OICC) concept. The concept is developed for a multiphase CMC synchronous buck converter (including a single phase implementation), operating with a constant output voltage and with AVP feature. Further, it is extended to a single phase VMC synchronous buck converter. During the operation, the main converter voltage loop and the OICC subsystem capacitor current loop is constantly closed, increasing the robustness under system tolerances and circuit parasitic and allowing the system to operate with any load-current shape or pattern. According to the proposed control method, the system operates in two states: during the steady-state the system is in the Idle state and the OICC subsystem is deactivated, while during the load-step transient the system is in the Active state and the OICC subsystem is activated in order to reduce the output impedance. The state changes are performed autonomously: the system enters in the Active state by observing the output capacitor current and it returns back to the Idle state when the steady-state operation is detected by observing the state variables. The validation of the OICC concept has been done by applying it to a 30W two phase synchronous buck converter with 140μF output capacitor and with the multiplication factor n equal to 15, generating during the Active state equivalent output capacitor of 2.1mF. The OICC subsystem is implemented as single phase PCMC synchronous buck converter. Comparing the converter operation with and without the OICC the results demonstrate that the 12 times reduction of the output voltage deviation is achieved, for both basic operation and for the AVP operation. Furthermore, the results have been compared to a reference prototype which has the same power stage and a fiscal output capacitor of 2.1mF. The results show that the two systems have the same dynamic behavior. Moreover, an impact on the system losses under the pulsating load and DVS operation has been quantified and it has been demonstrated that the OICC system has improved the system efficiency, considering the losses when the system operates with the pulsating load and the DVS operation. Lastly, the output capacitor of the OICC system is much smaller than the reference design output capacitor, therefore, by applying the OICC concept the power density can be increased. In summary, the main contributions of the thesis are: • The proposed Output Impedance Correction Circuit (OICC) concept, • The system level control based on the used approach to change the states of operation, • The OICC subsystem closed-loop implementation, together with the main converter implementation, • The dynamic losses under the pulsating load and the DVS operation quantification, and • The system robustness on the capacitor impedance variation and consecutive load-steps.

Muro cortina modular con marco de baja transmitancia térmica integrado en el vidrio aislante a través de adhesivos estructurales = Unitised curtain wall with low thermal transmittance frame integrated within the insulating glass unit through structural adhesives

Los muros cortina modulares están constituidos por paneles prefabricados que se fijan al edificio a través de anclajes a lo largo del borde del forjado. El proceso de prefabricación garantiza buena calidad y control de los acabados y el proceso de instalación es rápido y no requiere andamiaje. Por estas razones su uso está muy extendido en torres. Sin embargo, el diseño de los marcos de aluminio podría ser más eficiente si se aprovechara la rigidez de los vidrios para reducir la profundidad estructural de los montantes. Asimismo, se podrían reducir los puentes térmicos en las juntas si se sustituyeran los marcos por materiales de menor conductividad térmica que el aluminio. Esta investigación persigue desarrollar un muro cortina alternativo que reduzca la profundidad estructural, reduzca la transmisión térmica en las juntas y permita un acabado enrasado al interior, sin que sobresalgan los montantes. La idea consiste en conectar un marco de material compuesto de fibra de vidrio a lo largo del borde del vidrio aislante a través de adhesivos estructurales para así movilizar una acción estructural compuesta entre los dos vidrios y lograr una baja transmitancia térmica. El marco ha de estar integrado en la profundidad del vidrio aislante. En una primera fase se han efectuado cálculos estructurales y térmicos preliminares para evaluar las prestaciones a un nivel esquemático. Además, se han realizado ensayos a flexión en materiales compuestos de fibra de vidrio y ensayos a cortante en las conexiones adhesivas entre vidrio y material compuesto. Con la información obtenida se ha seleccionado el material del marco y del adhesivo y se han efectuado cambios sobre el diseño original. Los análisis numéricos finales demuestran una reducción de la profundidad estructural de un 80% y una reducción de la transmisión térmica de un 6% en comparación con un sistema convencional tomado como referencia. El sistema propuesto permite obtener acabados enrasados. ABSTRACT Unitised curtain wall systems consist of pre manufactured cladding panels which can be fitted to the building via pre fixed brackets along the edge of the floor slab. They are universally used for high rise buildings because the factory controlled assembly of units ensures high quality and allows fast installation without external access. However, its frame is structurally over-dimensioned because it is designed to carry the full structural load, failing to take advantage of potential composite contribution of glass. Subsequently, it is unnecessarily deep, occupying valuable space, and protrudes to the inside, causing visual disruption. Moreover, it is generally made of high thermal conductivity metal alloys, contributing to substantial thermal transmission at joints. This research aims to develop a novel frame-integrated unitised curtain wall system that will reduce thermal transmission at joints, reduce structural depth significantly and allow an inside flush finish. The idea is to adhesively bond a Fibre Reinforced Polymer (FRP) frame to the edge of the Insulated Glass Unit (IGU), thereby achieving composite structural behaviour and low thermal transmittance. The frame is to fit within the glazing cavity depth. Preliminary analytical structural and numerical thermal calculations are carried out to assess the performance of an initial schematic design. 4-point bending tests on GFRP and single-lap shear tests on bonded connections between GFRP and glass are performed to inform the frame and adhesive material selection process and to characterise these materials. Based on the preliminary calculations and experimental tests, some changes are put into effect to improve the performance of the system and mitigate potential issues. Structural and thermal numerical analysis carried out on the final detail design confirm a reduction of the structural depth to almost one fifth and a reduction of thermal transmission of 6% compared to a benchmark conventional system. A flush glazed appearance both to the inside and the outside are provided while keeping the full functionality of a unitised system.

O PRINCÍPIO DA GRATUIDADE ATIVA NO PROGRAMA DE ASSISTÊNCIA ESTUDANTIL DO INSTITUTO FEDERAL DE EDUCAÇÃO, CIÊNCIA E TECNOLOGIA DE SÃO PAULO (IFSP) – CAMPUS CUBATÃO

Este trabalho realizado, inicialmente, com base na análise de alguns documentos referentes à legislação educacional brasileira vigente tem por objetivo desenvolver uma investigação acerca da aplicabilidade da Assistência Estudantil dentro do Instituto Federal de Educação, Ciência e Tecnologia de São Paulo (IFSP). A partir da questão do Direito à Educação de todo cidadão, que está garantido em nossa Constituição Federal, o governo elaborou, no ano de 2010, o Programa Nacional de Assistência Estudantil (PNAES). Respaldados nesse Programa, o IFSP criou, em 2011, o Programa de Assistência Estudantil (PAE), dando validade e continuidade às ações desenvolvidas nos Campi para minimizar a evasão e o fracasso escolar, com vistas a garantir a permanência dos educandos no referido Instituto. Embora o PAE tenha sido implementado em todos os Campi do IFSP, no decorrer do presente trabalho analisamos e estudamos, exclusivamente, o Campus Cubatão, localizado na região da Baixada Santista devido a, dentre outros fatores, ter sido a primeira unidade descentralizada dos Institutos Federais do país. Assim, neste estudo, temos como objetivo analisar a estrutura de funcionamento do IFSP com o intuito específico de investigar o Campus de Cubatão, verificar as questões de Vulnerabilidade Social encontradas na destacada instituição, averiguar as ações do PAE que nascem do PNAES, observar a aplicabilidade desse programa com base no princípio da Gratuidade Ativa e do Direito à Educação de todo cidadão. Para tanto, utilizamos, fundamentalmente, além da legislação já mencionada, o princípio da Gratuidade Ativa de Melchior (2011) e o conceito de Vulnerabilidade Social proposto por Alves (1994) e por Abramovay (2002).

Epitopes close to the apolipoprotein B low density lipoprotein receptor-binding site are modified by advanced glycation end products

Advanced glycation end products (AGEs) are thought to contribute to the abnormal lipoprotein profiles and increased risk of cardiovascular disease of patients with diabetes and renal failure, in part by preventing apolipoprotein B (apoB)-mediated cellular uptake of low density lipoproteins (LDL) by LDL receptors (LDLr). It has been proposed that AGE modification at one site in apoB, almost 1,800 residues from the putative apoB LDLr-binding domain, may be sufficient to induce an apoB conformational change that prevents binding to the LDLr. To further explore this hypothesis, we used 29 anti-human apoB mAbs to identify other potential sites on apoB that may be modified by in vitro advanced glycation of LDL. Glycation of LDL caused a time-dependent decrease in its ability to bind to the LDLr and in the immunoreactivity of six distinct apoB epitopes, including two that flank the apoB LDLr-binding domain. ApoB appears to be modified at multiple sites by these criteria, as the loss of glycation-sensitive epitopes was detected on both native glycated LDL and denatured, delipidated glycated apoB. Moreover, residues directly within the putative apoB LDLr-binding site are not apparently modified in glycated LDL. We propose that the inability of LDL modified by AGEs to bind to the LDLr is caused by modification of residues adjacent to the putative LDLr-binding site that were undetected by previous immunochemical studies. AGE modification either eliminates the direct participation of the residues in LDLr binding or indirectly alters the conformation of the apoB LDLr-binding site.

Impaired liver regeneration in inducible nitric oxide synthasedeficient mice

The mechanisms that permit adult tissues to regenerate when injured are not well understood. Initiation of liver regeneration requires the injury-related cytokines, tumor necrosis factor (TNF) α and interleukin (IL) 6, and involves the activation of cytokine-regulated transcription factors such as NF-κβ and STAT3. During regeneration, TNFα and IL-6 promote hepatocyte viability, as well as proliferation, because interventions that inhibit either cytokine not only block hepatocyte DNA synthesis, but also increase liver cell death. These observations suggest that the cytokines induce hepatoprotective factors in the regenerating liver. Given evidence that nitric oxide can prevent TNF-mediated activation of the pro-apoptotic protease caspase 3 and protect hepatocytes from cytokine-mediated death, cytokine-inducible nitric oxide synthase (iNOS) may be an important hepatoprotective factor in the regenerating liver. In support of this hypothesis we report that the hepatocyte proliferative response to partial liver resection is severely inhibited in transgenic mice with targeted disruption of the iNOS gene. Instead, partial hepatectomy is followed by increased caspase 3 activity, hepatocyte death, and liver failure, despite preserved induction of TNFα, IL-6, NF-κβ, and STAT3. These results suggest that during successful tissue regeneration, injury-related cytokines induce factors, such as iNOS and its product, NO, that protect surviving cells from cytokine-mediated death.

Rho-stimulated Contractility Contributes to the Fibroblastic Phenotype of Ras-transformed Epithelial Cells

Oncogenic transformation of cells alters their morphology, cytoskeletal organization, and adhesive interactions. When the mammary epithelial cell line MCF10A is transformed by activated H-Ras, the cells display a mesenchymal/fibroblastic morphology with decreased cell–cell junctions but increased focal adhesions and stress fibers. We have investigated whether the transformed phenotype is due to Rho activation. The Ras-transformed MCF10A cells have elevated levels of myosin light chain phosphorylation and are more contractile than their normal counterparts, consistent with the activation of Rho. Furthermore, inhibitors of contractility restore a more normal epithelial phenotype to the Ras-transformed MCF10A cells. However, inhibiting Rho by microinjection of C3 exotransferase or dominant negative RhoA only partially restores the normal phenotype, in that it fails to restore normal junctional organization. This result prompted us to examine the effect that inhibiting Rho would have on the junctions of normal MCF10A cells. We have found that inhibiting Rho by C3 microinjection leads to a disruption of E-cadherin cytoskeletal links in adherens junctions and blocks the assembly of new adherens junctions. The introduction of constitutively active Rho into normal MCF10A cells did not mimic the Ras-transformed phenotype. Thus, these results lead us to conclude that some, but not all, characteristics of Ras-transformed epithelial cells are due to activated Rho. Whereas Rho is needed for the assembly of adherens junctions, high levels of activated Rho in Ras-transformed cells contribute to their altered cytoskeletal organization. However, additional events triggered by Ras must also be required for the disruption of adherens junctions and the full development of the transformed epithelial phenotype.

A platelet–endothelium interaction mediated by lectin-like oxidized low-density lipoprotein receptor-1

One crucial role of endothelium is to keep the innermost surface of a blood vessel antithrombotic. However, the endothelium also expresses prothrombotic molecules in response to various stimuli. The balance between the antithrombotic and prothrombotic nature of the endothelium is lost under certain conditions. During atherosclerosis, the attachment of platelets to the vessel surface has been suggested to promote the proliferation of smooth muscle cells and intimal thickening as well as to affect the prognosis of the disease directly through myocardial infarction and stroke. Dysfunctional endothelium, which is often a result of the action of oxidized low-density lipoprotein (OxLDL), tends to be more procoagulant and adhesive to platelets. Herein, we sought the possibility that the endothelial lectin-like OxLDL receptor-1 (LOX-1) is involved in the platelet–endothelium interaction and hence directly in endothelial dysfunction. LOX-1 indeed worked as an adhesion molecule for platelets. The binding of platelets was inhibited by a phosphatidylserine-binding protein, annexin V, and enhanced by agonists for platelets. These results suggest that negative phospholipids exposed on activation on the surface of platelets are the epitopes for LOX-1. Notably, the binding of platelets to LOX-1 enhanced the release of endothelin-1 from endothelial cells, supporting the induction of endothelial dysfunction, which would, in turn, promote the atherogenic process. LOX-1 may initiate and promote atherosclerosis, binding not only OxLDL but also platelets.

Protection against hemorrhagic shock in mice genetically deficient in poly(ADP-ribose)polymerase

Hemorrhagic shock (HS) and resuscitation leads to widespread production of oxidant species. Activation of the enzyme poly(ADP-ribose) polymerase (PARP) has been shown to contribute to cell necrosis and organ failure in various disease conditions associated with oxidative stress. We tested the hypothesis whether PARP activation plays a role in the multiple organ dysfunction complicating HS and resuscitation in a murine model of HS and resuscitation by using mice genetically deficient in PARP (PARP−/−) and their wild-type littermates (PARP+/+). Animals were bled to a mean blood pressure of 45 mmHg (1 mmHg = 133 Pa) and resuscitated after 45 min with isotonic saline (2× volume of shed blood). There was a massive activation of PARP, detected by poly(ADP-ribose) immunohistochemistry, which localized to the areas of the most severe intestinal injury, i.e., the necrotic epithelial cells at the tip of the intestinal villi, and colocalized with tyrosine nitration, an index of peroxynitrite generation. Intestinal PARP activation resulted in gut hyperpermeability, which developed in PARP+/+ but not PARP−/− mice. PARP−/− mice were also protected from the rapid decrease in blood pressure after resuscitation and showed an increased survival time, as well as reduced lung neutrophil sequestration. The beneficial effects of PARP suppression were not related to a modulation of the NO pathway nor to a modulation of signaling through IL-6, which similarly increased in both PARP+/+ and PARP−/− mice exposed to HS. We propose that PARP activation and associated cell injury (necrosis) plays a crucial role in the intestinal injury, cardiovascular failure, and multiple organ damage associated with resuscitated HS.

Defective regulatory volume decrease in human cystic fibrosis tracheal cells because of altered regulation of intermediate conductance Ca2+-dependent potassium channels

The cystic fibrosis transmembrane conductance regulator (CFTR) protein has the ability to function as both a chloride channel and a channel regulator. The loss of these functions explains many of the manifestations of the cystic fibrosis disease (CF), including lung and pancreatic failure, meconium ileus, and male infertility. CFTR has previously been implicated in the cell regulatory volume decrease (RVD) response after hypotonic shocks in murine small intestine crypts, an effect associated to the dysfunction of an unknown swelling-activated potassium conductance. In the present study, we investigated the RVD response in human tracheal CF epithelium and the nature of the volume-sensitive potassium channel affected. Neither the human tracheal cell line CFT1, expressing the mutant CFTR-ΔF508 gene, nor the isogenic vector control line CFT1-LC3, engineered to express the βgal gene, showed RVD. On the other hand, the cell line CFT1-LCFSN, engineered to express the wild-type CFTR gene, presented a full RVD. Patch-clamp studies of swelling-activated potassium currents in the three cell lines revealed that all of them possess a potassium current with the biophysical and pharmacological fingerprints of the intermediate conductance Ca2+-dependent potassium channel (IK, also known as KCNN4). However, only CFT1-LCFSN cells showed an increase in IK currents in response to hypotonic challenges. Although the identification of the molecular mechanism relating CFTR to the hIK channel remains to be solved, these data offer new evidence on the complex integration of CFTR in the cells where it is expressed.

Role of the cystic fibrosis transmembrane conductance regulator in innate immunity to Pseudomonas aeruginosa infections

Chronic Pseudomonas aeruginosa infection occurs in 75–90% of patients with cystic fibrosis (CF). It is the foremost factor in pulmonary function decline and early mortality. A connection has been made between mutant or missing CF transmembrane conductance regulator (CFTR) in lung epithelial cell membranes and a failure in innate immunity leading to initiation of P. aeruginosa infection. Epithelial cells use CFTR as a receptor for internalization of P. aeruginosa via endocytosis and subsequent removal of bacteria from the airway. In the absence of functional CFTR, this interaction does not occur, allowing for increased bacterial loads in the lungs. Binding occurs between the outer core of the bacterial lipopolysaccharide and amino acids 108–117 in the first predicted extracellular domain of CFTR. In experimentally infected mice, inhibiting CFTR-mediated endocytosis of P. aeruginosa by inclusion in the bacterial inoculum of either free bacterial lipopolysaccharide or CFTR peptide 108–117 resulted in increased bacterial counts in the lungs. CFTR is also a receptor on gastrointestinal epithelial cells for Salmonella enterica serovar Typhi, the etiologic agent of typhoid fever. There was a significant decrease in translocation of this organism to the gastrointestinal submucosa in transgenic mice that are heterozygous carriers of a mutant ΔF508 CFTR allele, suggesting heterozygous CFTR carriers may have increased resistance to typhoid fever. The identification of CFTR as a receptor for bacterial pathogens could underlie the biology of CF lung disease and be the basis for the heterozygote advantage for carriers of mutant alleles of CFTR.

An increased risk of Crohn's disease in individuals who inherit the HLA class II DRB3*0301 allele.

The role of inflammatory T cells in Crohn's disease suggests that inherited variations in major histocompatibility complex (MHC) class II genes may be of pathogenetic importance in inflammatory bowel disease. The absence of consistent and strong associations with MHC class II genes in Caucasian patients with inflammatory bowel disease probably reflects the use of less precise typing approaches and the failure to type certain loci by any means. A PCR-sequence-specific oligonucleotide-based approach was used to type individual alleles of the HLA class II DRB1, DRB3, DRB4, and DRB5 loci in 40 patients with ulcerative colitis, 42 Crohn's disease patients, and 93 ethnically matched healthy controls. Detailed molecular typing of the above alleles has previously not been reported in patients with inflammatory bowel disease. A highly significant positive association with the HLA-DRB3*0301 allele was observed in patients with Crohn's disease (P = 0.0004) but not in patients with ulcerative colitis. The relative risk for this association was 7.04. Other less significant HLA class II associations were also noted in patients with Crohn's disease. One of these associations involved the HLA-DRB1*1302 allele, which is known to be in linkage disequilibrium with HLA-DRB3*0301. These data suggest that a single allele of an infrequently typed HLA class II locus is strongly associated with Crohn's disease and that MHC class II molecules may be important in its pathogenesis.

Feedback circuitry within a song-learning pathway.

The song system of birds consists of several neural pathways. One of these, the anterior forebrain pathway, is necessary for the acquisition but not for the production of learned song in zebra finches. It has been shown that the anterior forebrain pathway sequentially connects the following nuclei: the high vocal center, area X of lobus parolfactorius, the medial portion of the dorsolateral thalamic nucleus, the lateral magnocellular nucleus of anterior neostriatum (IMAN), and the robust nucleus of the archistriatum (RA). We now show in zebra finches (Taeniopygia guttata) that IMAN cells that project to RA also project to area X, forming a feedback loop within the anterior forebrain pathway. The axonal endings of the IMAN projection into area X form cohesive and distinct domains. Small injections of tracer in subregions of area X backfill a spatially restricted subset of cells in IMAN, that, in turn, send projections to RA that are arranged in horizontal layers, which may correspond to the functional representation of vocal tract muscles demonstrated by others. We infer from our data that there is a myotopic representation throughout the anterior forebrain pathway. In addition, we suggest that the parcellation of area X into smaller domains by the projection from IMAN highlights a functional architecture within X, which might correspond to units of motor control, to the representation of acoustic features of song, or both.

Hepatic expression of mature transforming growth factor beta 1 in transgenic mice results in multiple tissue lesions.

Aberrant expression of transforming growth factor beta 1 (TGF-beta 1) has been implicated in a number of disease processes, particularly those involving fibrotic and inflammatory lesions. To determine the in vivo effects of overexpression of TGF-beta 1 on the function and structure of hepatic as well as extrahepatic tissues, transgenic mice were generated containing a fusion gene (Alb/TGF-beta 1) consisting of modified porcine TGF-beta 1 cDNA under the control of the regulatory elements of the mouse albumin gene. Five transgenic lines were developed, all of which expressed the Alb/TGF-beta 1 transgene selectively in hepatocytes. The transgenic line 25 expressing the highest level of the transgene in the liver also had high (> 10-fold over control) plasma levels of TGF-beta 1. Hepatic fibrosis and apoptotic death of hepatocytes developed in all the transgenic lines but was more pronounced in line 25. The fibrotic process was characterized by deposition of collagen around individual hepatocytes and within the space of Disse in a radiating linear pattern. Several extrahepatic lesions developed in line 25, including glomerulonephritis and renal failure, arteritis and myocarditis, as well as atrophic changes in pancreas and testis. The results from this transgenic model strongly support the proposed etiological role for TGF-beta 1 in a variety of fibrotic and inflammatory disorders. The transgenic model may also provide an appropriate paradigm for testing therapeutic interventions aimed at neutralizing the detrimental effects of this important cytokine.

Análise de acetona em ar exalado: desenvolvimento de método eletroanalítico e algoritmo para processamento de sinais

Propõe-se método novo e completo para análise de acetona em ar exalado envolvendo coleta com pré-concentração em água, derivatização química e determinação eletroquímica assistida por novo algoritmo de processamento de sinais. Na literatura recente a acetona expirada vem sendo avaliada como biomarcador para monitoramento não invasivo de quadros clínicos como diabetes e insuficiência cardíaca, daí a importância da proposta. Entre as aminas que reagem com acetona para formar iminas eletroativas, estudadas por polarografia em meados do século passado, a glicina apresentou melhor conjunto de características para a definição do método de determinação por voltametria de onda quadrada sem a necessidade de remoção de oxigênio (25 Hz, amplitude de 20 mV, incremento de 5 mV, eletrodo de gota de mercúrio). O meio reacional, composto de glicina (2 mol·L-1) em meio NaOH (1 mol·L-1), serviu também de eletrólito e o pico de redução da imina em -1,57 V vs. Ag|AgCl constituiu o sinal analítico. Para tratamento dos sinais, foi desenvolvido e avaliado um algoritmo inovador baseado em interpolação de linha base por ajuste de curvas de Bézier e ajuste de gaussiana ao pico. Essa combinação permitiu reconhecimento e quantificação de picos relativamente baixos e largos sobre linha com curvatura acentuada e ruído, situação em que métodos convencionais falham e curvas do tipo spline se mostraram menos apropriadas. A implementação do algoritmo (disponível em http://github.com/batistagl/chemapps) foi realizada utilizando programa open source de álgebra matricial integrado diretamente com software de controle do potenciostato. Para demonstrar a generalidade da extensão dos recursos nativos do equipamento mediante integração com programação externa em linguagem Octave (open source), implementou-se a técnica da cronocoulometria tridimensional, com visualização de resultados já tratados em projeções de malha de perspectiva 3D sob qualquer ângulo. A determinação eletroquímica de acetona em fase aquosa, assistida pelo algoritmo baseado em curvas de Bézier, é rápida e automática, tem limite de detecção de 3,5·10-6 mol·L-1 (0,2 mg·L-1) e faixa linear que atende aos requisitos da análise em ar exalado. O acetaldeído, comumente presente em ar exalado, em especial, após consumo de bebidas alcoólicas, dá origem a pico voltamétrico em -1,40 V, contornando interferência que prejudica vários outros métodos publicados na literatura e abrindo possibilidade de determinação simultânea. Resultados obtidos com amostras reais são concordantes com os obtidos por método espectrofotométrico, em uso rotineiro desde o seu aperfeiçoamento na dissertação de mestrado do autor desta tese. Em relação à dissertação, também se otimizou a geometria do dispositivo de coleta, de modo a concentrar a acetona num volume menor de água gelada e prover maior conforto ao paciente. O método completo apresentado, englobando o dispositivo de amostragem aperfeiçoado e o novo e efetivo algoritmo para tratamento automático de sinais voltamétricos, está pronto para ser aplicado. Evolução para um analisador portátil depende de melhorias no limite de detecção e facilidade de obtenção eletrodos sólidos (impressos) com filme de mercúrio, vez que eletrodos de bismuto ou diamante dopado com boro, entre outros, não apresentaram resposta.

Considerações sobre os métodos de dimensionamento estrutural de pavimentos com camadas recicladas a frio com espuma de asfalto.

A reciclagem profunda com espuma de asfalto tem sido uma alternativa de sucesso para a restauração de pavimentos degradados. Em relação às soluções tradicionais de reabilitação, como os recapeamentos, tem a vantagem de proporcionar a correção de defeitos em camadas inferiores, com a manutenção ou pequena elevação do greide da pista, além de ganhos ambientais, como um menor consumo de materiais virgens da natureza e redução do volume de material descartado. Entretanto, no Brasil não há método para dimensionamento estrutural para esta tecnologia, o que dificulta seu emprego. Para o desenvolvimento de um procedimento de dimensionamento que contemple este tipo de solução, foram estudados métodos presentes na bibliografia internacional: guia da AASHTO de 1993 e Caltrans, dos EUA, TRL386 e TRL611, da Inglaterra, as duas versões do guia sul-africano TG2 e os métodos oriundos do Austroads, tanto o procedimento interino de 2011 como adaptações de órgãos da Austrália e Nova Zelândia. Observou-se divergência de opiniões quanto ao comportamento do material reciclado com espuma de asfalto. Alguns órgãos e autores consideram o comportamento do mesmo mais próximo às misturas asfálticas, sendo o mecanismo de falha o trincamento, e outros o definem como semelhante a um material granular modificado com alta coesão e ruptura devido às deformações permanentes. Correlaciona-se tal associação ao teor de espuma usualmente utilizado nas obras rodoviárias. Outros aspectos que se destacam para este tipo de base são o ganho de resistência ao longo do tempo devido à cura, mesmo com início da operação da rodovia e a importância da infraestrutura remanescente no dimensionamento. Tais fatos foram corroborados pelos estudos de caso e resultados do trecho experimental construído na Rodovia Ayrton Senna - SP 070, monitorado por meio de ensaios deflectométricos com FWD durante um ano. Como resultado do trabalho, foi proposto um procedimento para o dimensionamento estrutural de pavimentos com camadas recicladas a frio com espuma de asfalto utilizando dados deflectométricos que atende o método do Manual de Pavimentação do Departamento Nacional de Infraestrutura de Transportes (DNIT) e incorpora diferentes aspectos na análise mecanicista. Outras conclusões são a viabilidade técnica a longo prazo da solução mencionada e a importância do controle tecnológico, com ênfase para o monitoramento deflectométrico nos primeiros meses de operação do pavimento para averiguar a evolução da cura do material.