Thermodynamic aspects of ion intercalation in KhFek[Fe(CN)(6)](l)center dot mH(2)O compounds: Application to the Everit's salt/Prussian Blue transition

The K+ reversible processes for ion exchange in KhFek[Fe(CN)(6)](l)center dot mH(2)O host compounds (Prussian Blue) were thermodynamically analyzed. A thermodynamic approach was established and developed based on the consideration of a lattice-gas model where the electronic contribution to the chemical potential is neglected and the ion-host interaction is not considered. The occupation fraction of the intercalation process was calculated from the kinetic parameters obtained through ac-electrogravimetry in a previous paper. In this way, the mass potential transfer function introduces a new way to evaluate the thermodynamic aspect of intercalation. Finally, based on the thermodynamic approach, the energy used to put each K+ ion into the host material was calculated. The values were shown to be in good agreement with the values obtained through transient techniques, for example, cyclic voltammetry. As a result, this agreement between theory and experimental data validates the thermodynamic approach considered here, and for the first time, the thermodynamic aspects of insertion were considered for mixed valence materials.

DNA hybridization mechanism in an interfacial environment: What hides beneath first order k (s(-1)) kinetic constant?

The scientific question addressed in this work is: what hides beneath first order kinetic constant k (s(-1)) measured for hybridization of a DNA target on a biosensor surface. Kinetics hybridization curves were established with a 27 MHz quartz microbalance (9 MHz, third harmonic) biosensor, constituted of a 20-base probe monolayer deposited on a gold covered quartz surface. Kinetics analysis, by a known two-step adsorption-hybridization mechanism, is well appropriate to fit properly hybridization kinetics curves, for complementary 20-base to 40-base targets over two concentration decades. It was found that the K-1 (M-1) adsorption constant, relevant to the first step, concerns an equilibrium between non hybridized targets and hybridized pre-complex and increases with DNA target length. It was established that k(2) (s(-1)), relevant to irreversible formation of a stable duplex, varies in an opposite way to K-1 with DNA target length. (C) 2012 Published by Elsevier B.V.

Electronic Perspective on the Electrochemistry of Prussian Blue Films

The derivative of the voltabsommetric scans, together with previous nano-electrogravimetric and X-ray diffraction results, allow different electrochemical processes to be distinguished during the Prussian blue (PB) voltammetric scan. Potassium, proton, and hydrated proton counterions involved in PB electrochemistry are related here to the electrochemical reactions of specific Fe sites. Potassium counterions show two different sites for their insertion: one located in the crystalline framework and another in ferrocyanide vacancies. From the monitoring of electroactive Fe sites, the covalent-exchange model is suggested as one of the first approaches to explain the origin of the PB magnetic ordering observed at room temperature during voltammetric scanning.

Um estudo das práticas de escrita de mulheres (escritoras ou não)

Pós-graduação em Educação - IBRC

Entre gestos e práticas: leituras de mães, professoras e meninas de um centro de referência down

Pós-graduação em Educação - FFC

Significados e sentidos dos discursos de um grupo de crianças da 3ª série do ensino fundamental sobre a profissão e os gêneros na docência

Esta pesquisa investiga os significados e sentidos dos discursos de um grupo de crianças da 3ª série do ensino fundamental sobre a profissão e os gêneros na docência, com o intuito de analisar por meio dos discursos das crianças os desdobramentos das questões de gênero no trabalho docente e no magistério. As crianças foram as minhas interlocutoras e sujeitos nesta empreitada e suas vozes foram o meu objeto de pesquisa e análise. A abordagem discursiva foi a perspectiva adotada no processo de investigação. Os instrumentos utilizados na coleta dos dados foram entrevista semi-estruturada e o uso de duas imagens fotográficas adotadas como iniciadoras do diálogo com as crianças. A pesquisa foi realizada em uma escola da rede pública municipal de Ananindeua-Pa, e no seu quadro docente atuavam de 1ª à 4ª séries no período em que a investigação foi realizada 19 professoras e 08 professores. O referencial teórico utilizado como aporte para a análise dos dados coletados está baseado nas teorizações de Mikhail Bakhtin sobre o discurso. Para relacionar as vozes das crianças com o contexto social, cultural e histórico vivenciado por estas, recorremos a autores/as como Áries, Perrot, Connell, Carvalho, Louro. As análises foram organizadas em 05 eixos-temáticos que emergiram dos discursos das crianças: 01- Os discursos ideológicos sobre a profissão docente e a definição histórica de papéis e funções para os sexos; 02- O significado da profissão e seus vínculos históricos e culturais com a maternidade; 03- Masculinidades e Feminilidades: Os múltiplos sentidos atribuídos aos gêneros na docência; 04- Relações de poder entre adultos e crianças e na prática docente; 05- O exercício da docência e as relações afetivas. Os discursos das crianças demonstram muitas continuidades e também rupturas com os papéis que foram construídos historicamente para homens e mulheres. O principal sentido da docência feminina para as crianças está na atenção e paciência e da docência masculina está na autoridade. Seus discursos também apresentam muitas expectativas e desejos para a prática de professores/as que superam binarismos e polaridades e oferecem informações significativas para (re)pensarmos a docência.

Um estudo das crônicas de Vivina de Assis Viana publicadas no Estado de Minas de 1990 a 1999

Pós-graduação em Letras - FCLAS

A representação da mulher paraguaia em contos de Josefina Plá

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A presença feminina dos estudos secundários no estado de São Paulo (1930-1947)

Pós-graduação em Educação Escolar - FCLAR

In-Flight Collision Avoidance Controller Based Only on OS4 Embedded Sensors

The major goal of this research was the development and implementation of a control system able to avoid collisions during the flight for a mini-quadrotor helicopter, based only on its embedded sensors without changing the environment. However, it is important to highlight that the design aspects must be seriously considered in order to overcome hardware limitations and achieve control simplification. The controllers of a UAV (Unmanned Aerial Vehicle) robot deal with highly unstable dynamics and strong axes coupling. Furthermore, any additional embedded sensor increases the robot total weight and therefore, decreases its operating time. The best balance between embedded electronics and robot operating time is desired. This paper focuses not only on the development and implementation of a collision avoidance controller for a mini-robotic helicopter using only its embedded sensors, but also on the mathematical model that was essential for the controller developing phases. Based on this model we carried out the development of a simulation tool based on MatLab/Simulink that was fundamental for setting the controllers' parameters. This tool allowed us to simulate and improve the OS4 controllers in different modeled environments and test different approaches. After that, the controllers were embedded in the real robot and the results proved to be very robust and feasible. In addition to this, the controller has the advantage of being compatible with future path planners that we are developing.

Risk factors for reperfusion injury after lung transplantation

OBJECTIVE: To assess the influence of recipient's and donor's factors as well as surgical events on the occurrence of reperfusion injury after lung transplantation. DESIGN AND SETTING: Retrospective study in the surgical intensive care unit (ICU) of a university hospital. METHODS: We collected data on 60 lung transplantation donor/recipient pairs from June 1993 to May 2001, and compared the demographic, peri- and postoperative variables of patients who experienced reperfusion injury (35%) and those who did not. RESULTS: The occurrence of high systolic pulmonary pressure immediately after transplantation and/or its persistence during the first 48[Symbol: see text]h after surgery was associated with reperfusion injury, independently of preoperative values. Reperfusion injury was associated with difficult hemostasis during transplantation (p[Symbol: see text]=[Symbol: see text]0.03). Patients with reperfusion injury were more likely to require the administration of catecholamine during the first 48[Symbol: see text]h after surgery (p[Symbol: see text]=[Symbol: see text]0.014). The extubation was delayed (p[Symbol: see text]=[Symbol: see text]0.03) and the relative odds of ICU mortality were significantly greater (OR 4.8, 95% CI: 1.06, 21.8) in patients with reperfusion injury. Our analysis confirmed that preexisting pulmonary hypertension increased the incidence of reperfusion injury (p[Symbol: see text]<[Symbol: see text]0.01). CONCLUSIONS: Difficulties in perioperative hemostasis were associated with reperfusion injury. Occurrence of reperfusion injury was associated with postoperative systolic pulmonary hypertension, longer mechanical ventilation and higher mortality. Whether early recognition and treatment of pulmonary hypertension during transplantation can prevent the occurrence of reperfusion injury needs to be investigated.