Electronic, vibrational and related properties of group IV metal oxides by ab initio calculations

We present our theoretical results for the structural, electronic, vibrational and optical properties of MO(2) (M = Sn, Zr, Hf and Ti) obtained by first-principles calculations. Relativistic effects are demonstrated to be important for a realistic description of the detailed structure of the electronic frequency-dependent dielectric function, as well as of the carrier effective masses. Based on our results, we found that the main contribution of the high values calculated for the oxides dielectric constants arises from the vibrational properties of these oxides, and the vibrational static dielectric constant values diminish with increasing pressure. (c) 2008 Elsevier B.V. All rights reserved.

Ab initio study of the electronic and optical properties of sillimanite (Al(2)SiO(5)) crystal

Ab initio calculations based on the density functional theory (DFT) are used to investigate the electronic and optical properties of sillimanite. The geometrical parameters of the unit cell, which contain 32 atoms, have been fully optimized and are in good agreement with the experimental data. The electronic structure shows that sillimanite has an indirect band gap of 5.18 eV. The complex dielectric function and optical constants, such as extinction coefficient, refractive index, reflectivity and energy-loss spectrum, are calculated. The optical properties of sillimanite are discussed based on the band structure calculations. It is shown that the O-2p states and Al-3s, Si-3s states play the major role in optical transitions as initial and final states, respectively. (C) 2011 Elsevier B.V. All rights reserved.

Theoretical investigation of electronic and optical properties of andalusite within density functional theory

The electronic and optical properties of andalusite were studied by using quantum-mechanical calculations based on the density functional theory (DFT). The electronic structure shows that andalusite has a direct band gap of 5.01 eV. The complex dielectric function and optical constants, such as extinction coefficient, refractive index, reflectivity and energy-loss spectrum, are calculated. The optical properties of andalusite are discussed based on the band structure calculations. It is shown that the O-2p states and Al-3s states play a major role in optical transitions as initial and final states, respectively. (C) 2010 Elsevier Ltd. All rights reserved.

Electronic and optical properties of grossular garnet (Ca(3)Al(2)Si(3)O(12)): An ab initio study

The electronic and optical properties of grossular garnet are investigated using density functional theory (DFT) within generalized gradient approximation (GGA). The calculated lattice parameters are in good agreement with the experiment data. The electronic structure shows that grossular has a direct band gap of 5.22 eV. The dielectric functions, reflective index, extinction coefficient, reflectivity and energy-loss spectrum are calculated. The optical properties of grossular are discussed based on the band structure calculations. The O 2p states and Si 3s play a major role in these optical transitions as initial and final states, respectively. The absorption spectrum is localized in the ultraviolet range between 30 and 250 nm. Finally, we concluded that pure grossular crystal does not absorb radiation in the visible range. (c) 2009 Elsevier B.V. All rights reserved.

Cholesterol Mediates Chitosan Activity on Phospholipid Monolayers and Langmuir-Blodgett Films

The polysaccharide chitosan has been largely used in many biological applications as a fat and cholesterol reducer, bactericide agent, and wound healing material. While the efficacy for some of such uses is proven, little is known about the molecular-level interactions involved in these applications. In this study, we employ mixed Langmuir and Langmuir-Blodgett (LB) films of negatively charged dimyristoyl phosphatidic acid (DMPA) anti cholesterol as cell membrane models to investigate the role of cholesterol in the molecular-level action of chitosan. Chitosan does not remove cholesterol froth the monolayer. The interaction with chitosan tends to expand the DMPA monolayer due to its interpenetration within the film. On the other hand, cholesterol induces condensation of the DMPA monolayer. The competing effects cause the surface pressure isotherms of mixed DMPA-cholesterol films on a chitosan subphase to be unaffected by the cholesterol mole fraction, due to distinct degrees of chitosan penetration into the film in the presence of cholesterol. By combining polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and sum-frequency generation spectroscopy (SFG), we showed that chitosan induces order into negatively charged phospholipid layers, whereas the opposite occurs for cholesterol. In conclusion, chitosan has its penetration in the film modulated by cholesterol, and electrostatic interactions with negatively charged phospholipids, such as DMPA, are crucial for the action of chitosan.

Ultrafast dynamics of bis (n-butylimido) perylene thin films excited by two-photon absorption

We report a pump-probe study of the two-photon induced reflectivity changes in bis (n-butylimido) perylene thin films. To enhance the two-photon excitation we deposited bis (n-butylimido) perylene films on top of gold nanoislands. The observed transient response in the reflectivity spectrum of bis (n-butylimido) perylene is due to a depletion of the molecule`s ground state and excited state absorption.

Polymeric scaffolds for enhanced stability of melanin incorporated in liposomes

The use of melanin in bioinspired applications is mostly limited by its poor stability in solid films. This problem has been addressed here by incorporating melanin into dipalmitoyl phosphatidyl glycerol (DPPG) liposomes, which were then immobilized onto a solid substrate as an LbL film. Results from steady-state and time-resolved fluorescence indicated an increased stability for melanin incorporated into DPPG liposomes. If not protected by liposomes, melanin looses completely its fluorescence properties in LbL films. The thickness of the liposome-melanin layer obtained from neutron reflectivity data was 4.1 +/- 0.2 nm, consistent with the value estimated for the phospholipid bilayer of the liposomes, an evidence of the collapse of most liposomes. On the other hand, the final roughness indicated that some of the liposomes had their structure preserved. In summary, liposomes were proven excellent for encapsulation, thus providing a suitable environment, closer to the physiological conditions without using organic solvents or high pHs. (C) 2010 Elsevier Inc. All rights reserved.

Att inte spänna kärran framför hästen : precisering av Meads ”rollövertagande”

Not to put the cart before the horse: clarification of Mead’s ”role taking” George Herbert Mead’s “role taking” is subject to many interpretations. Some dominant definitions restrict role taking to reflective people trying to understand each other and taking on each others' roles. Other definitions restrict role taking to the stage of a developed language. Against these two types of definitions I assert that Meads concept is explanatory, not merely descriptive, functionally as well as existentially. It has a value also on elementary levels of human development, where man is socially similar to other primates. Swedish sociologists have contributed fruitfully to straighten the debate. My intention is to clarify it further, and to explicate my own interpretation. Basic role taking is a non-reflective activity going on in any place where living entities influence each other with gestures in similar ways. In human beings it gives rise to conscious discursive reflectivity, and it coincides phylogenetically and ontogenetically with development of language, rather than being created by it. Role taking emanates from breaking automatic responsivity. It introduces distance and reflectivity and results in conscious social behavior, rather than being produced by such. In this way, role taking is a major step in the development of intelligence on earth.

Da formação ludopiética à autopoiese do lazer: significados para a autoformação humanescente do profissional do lazer

The present study aimed to understand and interpret the connections between the training of graduate ludopoiética leisure and the process of autopoiesis of leisure. From the main objective, the following objectives had been formulated specific: a) To interpret more significant the ludopoiéticas experiences in the academic formation of graduandos of leisure; b) To analyze the experiences of the leisure most significant, disclosed for the group investigated, before, during and after the course; c) To describe and to interpret the process of autopoiese of the leisure and its respective meaning for the autoformação human being. The study it articulated the following metodológicas boardings: autobiogr á fica, etnogr á fica and fenomenológica. For the construction of the ludopoiéticas bridges between the academic formation proposal for the course of Leisure and Quality of Life of the CEFET-RN and the autoformação lived deeply human being as leisure for the participants of the study, we use as categories of analysis, five properties that had constituted the respective autopoiético system of the leisure. Thus, for our autopoiética reflectivity we adopt the following categories: autotelia; autoliberação; autoconectividade; autovalia and autofruição. The carried through research obtained to evidence given important of the ludopoié tica formation of these professionals of the leisure for its autoforma ç ã o human being and the autocriação of the proper leisure, that for recursividade feeds this autoformação in way permanently. Lived deeply properties of the ludopoiético system in the formation are searched with autonomy in the leisure. Thus, the learning of the autotelia, the autovalia, the autofruição and the autoconectividade lived deeply during the course of graduation in Leisure and Quality of Life is valued by the emotion of the joy and the love to the life, having become something desired by the citizens that had chosen the leisure as profession

Formação de professores, saberes, reflexividade e apropriação da cultura digital no Projeto Um Computador por Aluno (UCA)

This study investigates teacher training and cognitive practice of teachers in a Basic Education school that adopted the Project One Computer per Student (OCS) in their school routine. Its relevance consists in provide directions for the continuation of training activities on the Project and guide the teachers with their pedagogical practices using the laptop model one to one. The thesis defended is that the educator formation for social using of digital media (specially the laptops from the Project UCA) gives space to establish new sociotechnical relationships, of new social and professionals practices, new identitary components and a process of reflexivity and knowledge reconstruction to teach. We reaffirm the importance of reflexivity and appropriation of digital culture for the better development of teaching practice using the Information and Communication Technologies (ICTs), giving focus to the aspects of social and professional use of the technology. The study is part of the qualitative aspect and is a procedural tracking based on principles of ethnographic research. As procedures and methodological tools, were used: intensive observation of school environments, documental analysis, focal group, semi-structured questionnaires and semi-structured individual interviews. The research was held in a public school in the city of Parnamirim - RN. The subject sample relates to 17 teachers, coming from the elementary school I and II, Youth and Adult Education and High School, who went through the process of training UCA and having entered the laptops in their teaching. The research corpus is structured based on the messages built into the process of data collection and is analyzed based on principles of Content Analysis, specified by Laurence Bardin (2011). Was taken as theoretical reference studies by Tardif (2000; 2011), Pimenta (2009), Gorz (2004, 2005), Giddens (1991), Dewey, J. (1916), Boudieu (1994; 1999), Freire (1996; 2005), among others. The analysis indicates a process of reconstruction / revision of knowledge to teach and work in digital culture, being these knowledges guided by the experience of the subjects investigated. The reconstructed knowledges will be revealed from a categorization process. The following groups of knowledges: "technical knowledges", "didactic-methodological knowledges and knowledges of professionalization" were built on the assumption of ownership of digital culture in the educational context. The analysis confirms the appearance of new ways of sociability when acquiring other forms of acting and thinking ICTs, despite the environment adverse to the reflexivity shared among the teachers. Also reveals, based on the ownership concept present on the data analysis, the construction of meanings of belonging and transformation of individuals into social routes from the interweaving of the teaching practice with the digital culture. Emphasizes, finally, the importance of a training for use of ICTs that exceeds the instrumentation, in other words, what we call "technical knowledges", but taking on its structural basis the shared reflection, the opening for the ressignificance (new meaning) and reconstruction of new knowledges and practices and that really allows, to the teacher, the living of an experience capable of providing socio-technical transformations of their relationships

Estimativas de parâmetros genéticos e fenotípicos de características do pelame e de desempenho reprodutivo de vacas holandesas em clima tropical

Objetivou-se investigar os efeitos das características do pelame sobre a idade ao primeiro parto (IPP) e o intervalo de partos (IEP) de vacas holandesas manejadas em sistema de estabulação livre com ventiladores e aspersores e estimar os parâmetros genéticos destas características. Os dados foram analisados pelo método dos quadrados mínimos, considerando os efeitos: ano; estação; número de inseminações; origem do pai; pai dentro da origem; idade (somente para IEP); porcentagem de malhas negras; espessura do pelame; comprimento dos pêlos; número de pêlos por unidade de área da epiderme; diâmetro dos pêlos; transmitância e refletância efetiva do pelame. O método da Máxima Verossimilhança Restrita foi utilizado para estimar os componentes de (co)variância sob um modelo animal. Os resultados incluíram as estimativas de herdabilidade para IPP (0,23±0,08), IEP (0,19±0,10), malhas negras (0,75±0,08), número (0,05±0,04), espessura (0,04±0,05), comprimento (0,36±0,09) e diâmetro (0,63±0,08) de pêlos. As estimativas de correlação genética entre IPP (-0,37±0,17), IEP (0,49±0,27) e diâmetro apresentaram valores significativos e favoráveis. Entretanto, as correlações genéticas entre espessura (-0,56±0,46), número (-0,66±0,43), porcentagem de malhas negras (0,04±0,16) e IPP foram desfavoráveis para seleção conjunta para melhor adaptação e precocidade sexual. O alto valor estimado para herdabilidade e as correlações genéticas favoráveis entre diâmetro e IPP e IEP indicaram ser possível selecionar para melhorar conjuntamente a adaptação e o desempenho reprodutivo.

Taxa de absorção atmosférica sobre as cidades de Botucatu-SP e Rio de Janeiro-RJ

O segundo satélite da Missão Espacial Completa Brasileira (SCD2/MECB) foi colocado em órbita em 23 de Outubro de 1998 e carrega a bordo um experimento de células solares. Célula solar de silício é um dispositivo semicondutor, que pode medir a intensidade da radiação visível e parte da radiação infravermelha (400-1100 nm). O experimento permite medir simultaneamente a insolação direta e parte da radiação solar que é refletida pela Terra para o espaço. Os dados do experimento célula solar são transmitidos em tempo real pela telemetria do satélite e recebidos pela estação terrestre em Cuiabá, MT-Brasil (16°S; 56°W). Este fato limita a cobertura espacial para um círculo sobre a América do Sul. O albedo planetário é obtido dentro desta cobertura e seus valores podem ser agrupados em períodos temporais (anual, sazonal ou mensal), ou podem ser estudados para várias localizações (latitude e longitude) durante a vida do satélite. O coeficiente de transmissão atmosférica ou índice de claridade (Kt), medido em estações meteorológicas na superfície da Terra, junto com o valor medido simultaneamente do albedo planetário, permite calcular o coeficiente de absorção atmosférica (Ka). O método desenvolvido neste trabalho para avaliar Ka considera que o albedo planetário é composto por duas partes: uma refletividade local e uma refletividade não local. Considerando este novo conceito, é definida uma taxa de absorção atmosférica (denominada Ra) que é a razão entre Ka e a potência de irradiância solar líquida, que não atravessou a atmosfera (100%-Kt). A taxa de absorção atmosférica assim definida é independente da cobertura de nuvens. O histograma de freqüência de Ra mostra os valores de 0,86±0,07 e 0,88±0,09 sobre as cidades de Botucatu-SP e do Rio de Janeiro-RJ, durante os anos de 1999 até 2006, respectivamente.

Análise da influência de superfícies refletivas nas perdas de calor de sistema térmicos

The use of reflective surfaces functioning as thermal insulator has grown significantly over the years. Reflective thermal insulator are materials that have several characteristics such as low emissivity, low absorptivity and high reflectivity in the infrared spectrum. The use of these materials has grown a lot lately, since it contains several important radioactive properties that minimize the heat loss of thermal systems and cooling systems that are used to block the heat on the roof of buildings. A system made of three surfaces of 316 stainless steel mirror was built to analyze the influence of reflective surfaces as a way to reduce the heat loss and thereby conserve the energy of a thermal system. The system was analyzed both with and without the presence of vacuum, and then compared with a system that contained glass wool between the stainless steel mirror walls, since this isolator is considered resistive and also broadly used around the world in thermal systems. The reflectivity and emissivity of the surfaces used were also measured in this experiment. A type K thermocouple was fixed on the wall of the system to obtain the temperature of the stainless steel mirror surfaces and to analyze the thermal behavior of each configuration used. The results showed an efficiency of 13% when the reflective surfaces were used to minimize the heat loss of the thermal system. However, the system with vacuum had the best outcome, a 60% efficiency. Both of these were compared to the system made of glass wool as a thermal insulator

Ultrafast dynamics of bis (n-butylimido) perylene thin films excited by two-photon absorption

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