Photoinduced hole-transfer in semiconducting polymer/low-bandgap cyanine dye blends: evidence for unit charge separation quantum yield

Power-conversion efficiencies of organic heterojunction solar cells can be increased by using semiconducting donor-acceptor materials with complementary absorption spectra extending to the near-infrared region. Here, we used continuous wave fluorescence and absorption, as well as nanosecond transient absorption spectroscopy to study the initial charge transfer step for blends of a donor poly(p-phenylenevinylene) derivative and low-band gap cyanine dyes serving as electron acceptors. Electron transfer is the dominant relaxation process after photoexcitation of the donor. Hole transfer after cyanine photoexcitation occurs with an efficiency close to unity up to dye concentrations of similar to 30 wt%. Cyanines present an efficient self-quenching mechanism of their fluorescence, and for higher dye loadings in the blend, or pure cyanine films, this process effectively reduces the hole transfer. Comparison between dye emission in an inert polystyrene matrix and the donor matrix allowed us to separate the influence of self-quenching and charge transfer mechanisms. Favorable photovoltaic bilayer performance, including high open-circuit voltages of similar to 1 V confirmed the results from optical experiments. The characteristics of solar cells using different dyes also highlighted the need for balanced adjustment of the energy levels and their offsets at the heterojunction when using low-bandgap materials, and accentuated important effects of interface interactions and solid-state packing on charge generation and transport.

The use of software Mapavox for teaching graphics and games to blind and low vision students: a development through practices

Current policies on education to visually impaired point for a growing trend of including students with special educational needs in regular schools. However, most often this inclusion is not accompanied by an appropriate professional trained or infrastructure, which has been presented as a big problem for regular school teachers who have students with visual impairments in their classroom. Based on this situation, the Group of Extension in Tactile Cartography from UNESP - University of the State of São Paulo - Campus de Rio Claro - SP - Brazil has been developing educational material of geography and cartography to blind students at a special school. Among the materials developed in this study highlight the development of graphics and board games provided with sound capabilities through MAPAVOX, software developed in partnership with UFRJ - Federal University from Rio de Janeiro - RJ - Brazil. Through this software, sound capabilities can be inserted into built materials, giving them a multi-sensory character. In most cases the necessary conditions for building specific materials to students with visual impairments is expensive and beyond the reach of features from a regular school, so the survey sought to use easy access and low cost materials like Cork, leaf aluminum, material for fixing and others. The development of these materials was supported by preparation in laboratory and its subsequent test through practices involving blind students. The methodology used on the survey is based on qualitative research and non comparative analysis of the results. In other words, the material is built based on the special students perception and reality construction, not being mere adaptations of visual materials, but a construction focused on the reality of the visually impaired. The results proved were quite successful as the materials prepared were effective on mediating the learning process of students with disabilities. Geographical and cartographic concepts were seized by the students through the technology used, associated with the use of materials that took into account in its building process the perception of the students.

Demonstração didática da interação entre correntes elétricas

Apresentamos a primeira experiência crucial de Ampère mostrando a interação entre dois fios metálicos conduzindo correntes elétricas. Discutimos sua importância na história da física. Descrevemos uma reprodução moderna dos procedimentos e observações de Ampère com materiais de baixo custo.

Desenvolvimento e otimização de materiais nanocristalinos para células solares sensibilizadas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biossorção do corante DR 23 por Saccharomyces cerevisiae imobilizada em serragem de peroba (Aspidosperma polyneuron) tratada com PEI (polietilenoimina)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adequação de demandas funcionais de atividades para a participação escolar de crianças com disfu'nções neuromotoras

The school participation is a prerequisite for the construction of knowledge, learning and development. Neurological deficits may affect child's ability to explore the environment and engage in typical activities. Considering the importance of encouraging professionals in the field of education to conduct simple adjustments in school activities of daily life, this study aimed to adapt, with low cost materials, resources of entertainment and educational for children with neuromotor disorders . It was objects of this study eight resources prescribed and designed for three children diagnosed with cerebral palsy: domino, puzzle, memory game, moving magnetized alphabet, crossword, doll body scheme, adaptation of pencils for writing and bracelet sinker.The analysis of these resources occurred in the parameters of conventional design and management skills, followed by identifying the limiting conditions of the motor skills of the cases observed, indicating the materials used in the adaptation and possible uses. This study provides subsidy for implementation of teaching strategies in the care of students with neuromotor disorders.

Características da base de conhecimentos de professores no ensino de biologia celular a partir de um curso de formação continuada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O ensino de física nos primeiros anos da educação básica: possibilidades lúdicas e experimentais

We discuss in the work the importance of experiential activities for Physics Teaching in the first years at Elementary Education. For this we start from the experience provided by the Teaching Project Initiation under Pibid CAPES, linked to the Department of Education from the Institute of Biosciences and activities of the Graduate Diploma in Physics Supervised, at Rio Claro Campus, São Paulo State, in partnership with Basic Education schools of the city. Based on some patterns and studies on the Teaching of Science in Elementary Education and particularly in the Ferreira’s work with Instrumentation for Physics Teaching, Electrostatic was chosen as base theme. We opted for the use of didactic experiments that provided in its construction the utilization of low cost materials, easy access and portability. Teaching strategies were aimed at inserting experiential activities during Elementary School I (first and third years of elementary school), intending to rescue the trial of Physics Education and Science for Basic Education. These experimental teaching activities were analyzed in this paper from the perspective of playfulness. We argue that experimentation with recreational attributes when properly used provides the interaction of individuals with the knowledge of Physical Sciences

O uso de experimentos didáticos como ferramenta para o ensino de física nos anos iniciais da educação básica

When it comes to teaching physics in the early years of elementary school, the first question is: but there are opportunities to teach concepts to children of such complexity? This study sought to examine approaches and strategies to enter the Basic Education in Physics. To this end, we used low cost materials testing, taking as its starting point the work of Ferreira (1978) instrumentation for Teaching Physics, particularly with the theme electrostatics. The present study was made from the use of prototypes developed with the materials cited. Observations were made in the classroom looking for, from the records of teaching, analyzing the behavior of children and their arguments, possibilities for Physics Teaching this age group as well as some evidence of their cognitive development. In teaching discussions were held with students of the early years of elementary school involving conceptual and phenomenological aspects, adapting such knowledge at the level of logical and mathematical thinking that was still under development. The work shows that it is possible to work on electrostatic physical concepts with children belonging to the age group of nine to ten years. With the support of the group Pibid Physics city of Rio Claro, I realize my observations and practices at the Municipal School Marcelo Schmidt, which proved to be available and open for acceptance of this proposal

O experimento e o lúdico: reflexões sobre atividades didáticas experimentais para o ensino de Física e a ludicidade

In this work, is discussed the importance of experimental activities in Education of Physics in Basic Education from the experience of Supervised Stage and the work with the Initiation of Teaching in the Program PIBID CAPES, in this case linked to the Department of Education of the Institute of Biosciences, Campus Rio Claro, São Paulo State, in partnership with three schools of basic education in the city. At first, based on the work of Ferreira with Instrumentation for Teaching Physics, consider the electrostatic theme. The focus is the searching for equipments constructed with low cost materials and easy access. Were developed and promoted strategies of the use of such materials in Physics’ Teaching, with a view to reintroducing experimental teaching activities in Public Basic Education, in the form Workshop Learning and Teaching of Physics, as well as lessons of Laboratory with the help of script and also in the form of an Experiments Library. These experimental activities were critically analyzed with a focus on playfulness. The focus of work in experimental activities for the Physics’ Teaching allowed to redeem, critically, didactic materials. From the standpoint of playfulness, playful moments and interaction of individuals with the knowledge that provides the experimental material when used strategically, they seem to be of great relevance to the Physics’ Teaching in Basic Education. It is possible to use experiments in Physics’ Teaching in public schools

Física Moderna no Ensino Médio: um experimento para abordar o efeito fotoelétrico

Considering the importance of the inclusion of Modern and Contemporary Physics in the curriculum of Physics in High School, it is proposed in this work an experimental activity, made with low- cost materials, which presents the photoelectric effect. This activity can be used articulating this phenomenon with some technological applications experienced by the students in their daily lives. When working the experiment, the teacher can encourage students to investigate what happens during its execution and, through questions, get them to express their ideas in the previous attempt to explain its operation. This articulation linked to social interaction in the classroom can arouse the students’curiosity and motivation of students to learn the subject taught in classroom.

Photo-induced electron trapping in indirect bandgap AlxGa1-xAs : Si at low temperature

A variation of photoconductivity excitation with wavelength is applied to Si-doped Al0.56Ga0.44As (indirect bandgap material) for a wide range of temperature. The lower the temperature the lower the photocurrent below 70 K. In the range 13-30 K there is a decrease in the photoconductivity spectrum slightly above the bandgap transition energy, followed by another increase in the conductivity. We interpret these results in the light of existing models and confirm the trapping by the X-valley effective mass state. which is responsible for attenuation of persistent photoconductivity below 70 K. A DX0 intermediate state which has non-negligible lifetime is proposed as responsible for the decrease in the photoconductivity with about 561 nm of wavelength of exciting light, in the investigated 13-30 g range.

Bandgap voltage reference with low susceptibility to electromagnetic interference (EMI)

In this paper, the susceptibility of a current-mode bandgap voltage reference to electromagnetic interference (EMI) superimposed to the power supply is investigated by simulation. Designed for AMS 0.35 CMOS process, the circuit provides a stable voltage reference in the temperature range of -40-150°C. When EMI disturbances are present, the circuit exhibits only 6.7 mV of offset for interfering signals in the frequency range of 150 kHz-1 GHz. © 2011 ACM.

Treatment of PVC using an alternative low energy ion bombardment procedure

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

FeNbP in ultra-low carbon Nb-added steel containing high P

Precipitation of FeTiP is reported to occur in Ti-added IF steels containing high P during thermomechanical processing. An ultra-low carbon (ULC) Nb-added steel ingot containing a higher P content (< 0.8 wt-%) was produced via aluminothermic reduction of Fe2O3 followed by double electron beam melting (EBM). FeNbP coarse precipitates were observed in the as-cast microstructure. After soaking at 1050C for 1 h, the plate was hot rolled from 31 mm down to 7 mm in thickness (total reduction of 77%). During cold rolling of these hot bands we observed embrittlement. We believe that this embrittlement can be attributed to the presence of the FeNbP precipitates. Light optical and scanning electron microscopy (SEM/EDS) were used to characterize the microstructure of this ULC steel. (C) 2000 Elsevier B.V. All rights reserved.