Effects of self-assembly process of latex spheres on the final topology of macroporous silica

This paper surveys the topology of macroporous silica prepared using latex templates covering the submicrometric range (0.1-0.7 mu m). The behavior of latex spheres in aqueous dispersion has been analyzed by dynamic light scattering (DLS) measurement indicating the most appropriate conditions to form well-defined cubic arrays. The optical behavior of latex spheres has been analyzed by transmittance and reflectance measurements in order to determine their diameter and filling factor when they were assembled in bidimensional arrays. Macroscopic templates have been obtained by a centrifugation process and their crystalline ordering has been confirmed by porosimetry and scanning electron microscopy. These self-assembled structures have been used to produce macroporous silica, whose final topology depends on the pore size distribution of the original template. It has been seen that latex spheres are ordered in a predominant fcc arrangement with slipping of tetragonal pores due to the action of attractive electrostatic interactions. The main effect is to change the spherical shape of voids in macroporous silica into a hexagonal configuration with possible applications to fabricate photonic devices with novel optical properties. (c) 2005 Elsevier B.V. All rights reserved.

Comparative analysis between experimental characterization results and numerical fdtd modeling of self-assembled photonic crystals

This paper presents a comparative analysis between the experimental characterization and the numerical simulation results for a three-dimensional FCC photonic crystal (PhC) based on a self-assembly synthesis of monodispersive latex spheres. Specifically, experimental optical characterization, by means of reflectance measurements under variable angles over the lattice plane family [1,1, 1], are compared to theoretical calculations based on the Finite Di®erence Time Domain (FDTD) method, in order to investigate the correlation between theoretical predictions and experimental data. The goal is to highlight the influence of crystal defects on the achieved performance.

Deposition and photo-induced electrical resistivity of dip-coated NiO thin films from a precipitation process

Thin films of the semiconductor NiO are deposited using a straightforward combination of simple and versatile techniques: the co-precipitation in aqueous media along with the dip- coating process. The obtained material is characterized by gravimetric/differential thermal analysis (TG-DTA) and X-ray diffraction technique. TG curve shows 30 % of total mass loss, whereas DTA indicates the formation of the NiO phase about 578 K (305 C). X-ray diffraction (XRD) data confirms the FCC crystalline phase of NiO, whose crystallinity increases with thermal annealing temperature. UV-Vis optical absorption measurements are carried out for films deposited on quartz substrate in order to avoid the masking of bandgap evaluation by substrate spectra overlapping. The evaluated bandgap is about 3.0 eV. Current-voltage (I-V) curves measured for different temperatures as well as the temperature-dependent resistivity data show typical semiconductor behavior with the resistivity increasing with the decreasing of temperature. The Arrhenius plot reveals a level 233 meV above the conduction band top, which was attributed to Ni2+ vacancy level, responsible for the p-type electrical nature of NiO, even in undoped samples. Light irradiation on the films leads to a remarkable behavior, because above bandgap light induced a resistivity increase, despite the electron-hole generation. This performance was associated with excitation of the Ni 2+ vacancy level, due to the proximity between energy levels. © 2012 Springer Science+Business Media New York.

Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation

Carbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd: Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3-5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd: Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown that the mechanism for ethanol electro-oxidation is dependent on catalyst composition, leading to different reaction products, such as acetaldehyde and acetate, depending on the number of electrons transferred. Experiments on a single ADEFC were conducted between 50 and 900 C, and the best performance of 44 mW cm-2 in 2.0molL-1 ethanol was obtained at 850C for the Pd:Au 90:10 catalysts. This superior performance is most likely associated with enhancement of ethanol adsorption on Pd, oxidation of the intermediates, the presence of gold oxide-hydroxyl species, low mean particle diameters and better distribution of particles on the support. © 2013 Elsevier Ltd. All rights reserved.

Método do look ahead modificado para estudos de colapso de tensão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise energética em refino de petróleo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Questões teóricas e metodológicas das pesquisas com crianças: algumas reflexões

Thinking about research with children, giving time and voice to them is a discussion that is still fresh. Thus, in order to establish some reflections on the theoretical and methodological issues in research with children, we hope with this article to give visibility to the theoretical assumptions of authors who are concerned to place the child and childhood in the center of the research process. Thus, contributing to this discussion, this text is divided into three stages: initially bring some contributions of sociology of childhood and the various fields of knowledge to think about research with children. Secondly, we propose to discuss some methods and procedures that may favor the development of research with children. When we trace the historical development related to research with children and recover the concept of childhood and child while being active and producer of culture, we headed for the third time this work presents some results and conclusions, which can direct our gaze on pursuit of research instruments that capture what children think, feel and build in the world that they live and live together.

Ensino Fundamental de nove anos: articulações necessárias com a Educação Infantil

This article leads to reflect on the analysis of contexts of early Childhood Education and Elementary School concerning the space for playtime in the educational routine with groups of children between five and six years old. There was a reflection on official documents about the extension of Elementary School and the presuppositions from the Cultural- -Historical Theory. Actions related to bibliographical research, questionnaire application, photographic and written documentation of playful practices observation, collective meetings with teachers and construction of a toy library have been taken. Specifically on the studied aspect, the make-believe play is the main child activity and may be considered as a mediator from the learning and from the humanization possibilities until about six years old. With this understanding, this issue deserves attention from the government (expressed in public policies), from the teachers and from the school staff in order to offer better conditions of success on the full formation during childhood.

Didática para a Educação Infantil: implicações do materialismo histórico dialético e da Teoria Histórico-Cultural

In this article, we discuss the contributions of Didactics for intentional pedagogical action of teachers devoted to children education. In this sense, we initially say to be essential the reflections which aim to search for foundations focused on the mobilization of future teachers for the action-reflection-action about the educational phenomena, aiming at the unveiling, with rigor and objectivity, of its multiple determinations within the capitalist relations . We believe that such unveiling is only possible in the light of a world view, a method and a praxis constituted in unison with historical materialism and its dialectic. Afterwards, we reflect on some of the principles of the Historical-Cultural Theory to understand of the active and mediator role teachers have in the process of humanization of young children and contributions of dialectical materialism to this reflection. Finally are detailed some aspects of a Didactics focused on training teachers for Children and early elementary school years’ education, which have guided our actions as teachers of the Pedagogy Course and reiterated by teachers’ narratives about their experience both in life and teaching, in search of new systematization modes, targeting an educational praxis due to the redefinition (theorization) and on the teaching practice by its very subjects.

Resolução de conflitos e agressividade: escala sobre a percepção de educadores

This study aime to estimate the properties of the Escala de percepção de professores dos comportamentos agressivos de crianças na escola. The research was conducted in a socio-educational institution in two phases. In the first one different educators completed the scale concerning the children and teenagers who attended the institution (N = 100). In the second, the children and teenagers with the highest or the lowest scores on the scale above (n = 60) responded to the Children’s Action Tendency Scale, which investigates strategies of conflict resolution. The results demonstrated adequate reliability of the scale of perception. However, they indicated that the educators’ evaluation did not correspond to how children and teenagers judged the hypothetical conflicts since the boys were rated as more aggressive than girls on the perception scale.

Adesão ao valor justiça em crianças e adolescentes

This search is part of a larger study conducted at the Carlos Chagas Foundation (SP-Brazil), which aims to build a scale to assess adhesion to moral values by basic education students and their teachers. This text addresses only the value of justice. The responses of 111 10-13 year old children and 121 teenagers between 14 and 17 years of age at public and private schools in the city of São Paulo (SP-Brazil) were compared. Among the various topics addressed, some issues of distributive, retributive and commutative justice were selected. In the questionnaire, the alternatives offered were built in increasing stages of decentration from a social perspective inspired by Kohlberg. The results confirmed the two hypotheses that had been raised: there was a progression in the choice of the answers concerning the stages between children and teenagers and there were differences between the three forms of justice considered, in relation to the achievement of higher levels.

WiMAX interoperabilidade mundial para acesso de microondas

This paper presents a technique dubbed WiMAX radio link, the IEEE 802.16 was completed in October 2001 and published on April 8, 2002 and is constantly updated, this technology specifies an interface for wireless metropolitan networks (WMAN) and is under control of the WiMAX Forum, which is a group of companies responsible for the dissipation of this technology in the world, the great benefit of this standard is to offer broadband Internet connection in areas where there is no infrastructure such as fiber optics that has a cost higher. The main purpose of this paper is to present the theoretical and technical characteristics of this technology for both the standard for fixed and mobile standard, regulation of frequency bands by the FCC and description of the physical layer, through to basic concepts are used in many other types of radio link and technologies have been adapted and updated for this little-known standard, allowing a greater range and speed, which are specified and differentiate these advancements is one of the contributions of the work done here. After the theoretical conceptualization stage, a real case study has been inserted in this work to demonstrate the effectiveness of this technology deployed. The idea of presenting this case study is linked to a better view of the use of standard in the market, nationwide

Reformas educacionais e avaliação: mecanismos de regulação docente

Our main concern was to investigate the forms and rationalities implicit in the social regulation/autonomy of the management processes of learning, historically established in the 1971 through 2002 educational reforms, via assessment guidelines of school performance in the state of São Paulo. We used a socio-historical approach, relying on speeches and official documents as our primary source and on studies and research work about teacher assessment and performance as secondary sources. As central categories we considered continuity and rupture in the patterns and mechanisms of social regulation/autonomy of educational work. The results help to clarify how educational policies, instituted in contexts of social reproduction/transformation, influence the management of educational processes within the school.

Bullying: dimensões psicológicas no desenvolvimento moral

Understanding and assessing the extent of psychological mechanisms that operate in actions of specific violence acts such as bullying can contribute to the discussion of educational interventions that promote moral education as desired by educational institutions. The current research aimed toD correlateD this form of violence called bullying to representations of the self and even to the ways in which the subjects self-regulate themselves in hypothetical situations which pose the problem, thus identifying their moral commitments or non-commitments. The procedures followed to check the presence of these correlationsDindicate that subjects whose self-representations are individualistic are less morally committed and more likely to be perpetrators in bullying situations. This shows that more than a social problem, the issues of coexistence should be treated from a moral perspective.