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Search Results: 1 - 10 of 34828 matches for " Gil Nonato Santos "
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Theoretical Investigation on the Solubilization in Water of Functionalized Single-Wall Carbon Nanotubes
Michael Mananghaya,Emmanuel Rodulfo,Gil Nonato Santos,Al Rey Villagracia
Journal of Nanotechnology , 2012, DOI: 10.1155/2012/780815
Abstract: An important technique to increase the solubility and reactivity of carbon nanotube is through functionalization. In this study, the effects of functionalization of some single-walled carbon nanotubes (SWCNTs) were investigated with the aid of density functional theory. The SWCNT model used in the study consists of a finite, (5, 0) zigzag nanotube segment containing 60 C atoms with hydrogen atoms added to the dangling bonds of the perimeter carbons. There are three water-dispersible SWCNTs used in this study that were functionalized with (a) formic acid, as a model of carboxylic acid, (b) isophthalic acid, as a model aromatic dicarboxylic acid, and (c) benzenesulfonic acid, as a model aromatic sulfonic acid. Binding energies of the organic radicals to the nanotubes are calculated, as well as the HOMO-LUMO gaps and dipole moments of both nanotubes and functionalized nanotubes. Binding was found out to be thermodynamically favorable. The functionalization increases the electrical dipole moments and results in an enhancement in the solubility of the nanotubes in water manifested through favorable changes in the free energies of solvation. This should lower the toxicity of nanotubes and improve their biocompatibility. 1. Introduction Single-walled carbon nanotubes (SWCNTs) are allotropes of carbon and possess various novel properties that make them useful in the field of nanotechnology and pharmaceuticals. SWCNTs are tubular in shape, made of graphite, nanometers in diameter, and several millimeters in length and have a very broad range of electronic, thermal, and structural properties. These properties vary with the kind of nanotubes defined by its diameter, length, chirality or twist, and wall nature. Their unique surface area, stiffness, strength, and resilience have led to much excitement in the field of pharmacy. Nanostructured materials hold promise for a wide range of technological applications and are increasingly studied, not only for their possible applications in electronics, optics and mechanical materials, but also specifically having enormous potential in nanomedicine [1–11]. Because of this, it is imperative to examine the toxicity of these carbon-based nanostructures. Previous toxicological evaluations of single-walled carbon nanotubes have been conducted, both in cell culture and in vivo. One example, using an SWCNT surfactant stabilized system where the Fe content was significantly high, reported an elevated cytotoxic response [12]. Warheit et al. [13] observed an increase in inflammatory response in the lung cavities of rats. While these
Theoretical Investigation on Single-Wall Carbon Nanotubes Doped with Nitrogen, Pyridine-Like Nitrogen Defects, and Transition Metal Atoms
Michael Mananghaya,Emmanuel Rodulfo,Gil Nonato Santos,Al Rey Villagracia,Alvin Noe Ladines
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/104891
Abstract: This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs) with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i) (10, 0) and (5, 5) SWCNT doped with nitrogen (CNxNT), (ii) (10, 0) and (5, 5) SWCNT with pyridine-like defects (3NV-CNxNT), (iii) (10, 0) SWCNT with porphyrine-like defects (4ND-CNxNT). Models (ii) and (iii) were chemically functionalized with 14 transition metals (TMs): Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT), stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed.
A escrita nas formas do trabalho docente
Gomes-Santos, Sandoval Nonato;
Educa??o e Pesquisa , 2010, DOI: 10.1590/S1517-97022010000200002
Abstract: the production of writing at school is a highly respected object of study for several of the domains in the field of language and education. pursued under different theoretical perspectives and disciplinary traditions, most of the academic reflection on the subject writing, in brazil, has been concerned with the learning processes of writing by pupils of various age groups, levels of literacy, and schooling within specific sociocultural and institutional contexts. along a different, but complementary, direction, the present study focuses on the ways in which writing is constituted in the teaching practice, and through which is becomes a taught object (dolz; ronveaux; schneuwly, 2007). to such end, the article is based on a corpus comprised of audio and video recordings of episodes of the teaching of writing produced in different institutional and sociocultural contexts. the way in which the relation is established between the objects of teaching, the professional gestures, and the didactic devices is analyzed (aeby daghé; dolz, 2007; gomes-santos; almeida, 2009; schneuwly, 2000; 2001). from a theoretical and methodological viewpoint, the questions of the study are illuminated by the contribution of researches on the description of the modes of organization and functioning of language in school interactions, and by studies that center on the specifically didactic dimension of those interactions. the investigation of writing in the practices of teaching has enriched the reflection about the didactic devices needed at the heart of the teaching/learning practices in order to develop active ways to facilitate the access to symbolic goods.
Modos de apropria??o do gênero debate regrado na escola: uma abordagem aplicada
Gomes-Santos, Sandoval Nonato;
DELTA: Documenta??o de Estudos em Lingüística Teórica e Aplicada , 2009, DOI: 10.1590/S0102-44502009000100002
Abstract: the genre debate has its own particular rules. this study describes and analyses the production process of the genre debate in the mother language teaching and learning context, in high school juniors groups of a public school in belém (pa). the aim of the study is to understand how this genre, as a teaching object, assumes the role of discipline content, that is, its status in the portuguese language class. students' productions, specifically the roles they assume to perform in this genre, are focused on. this focus implies considering not only the ways in which students learn the genre, but also their perceptions about the tasks they are involved in achieving.
Produ o científica: por que medir? o que medir?
Raimundo Nonato Macedo dos Santos
Revista Digital de Biblioteconomia e Ciência da Informa??o , 2003,
Abstract: A ciência, quanto atividade, é uma constru o social, complexa, que requer ousadia e altos investimentos. N o é neutra, nem extemporanea; gra a na concentra o do seu labor, o que, em conseqüência, favorece o monopólio econ mico dos seus resultados. Elitiza-se, materializa-se no efeito S o Mateus: a quem tem, mais lhe será dado. Portanto, boas inten es e contradi es requerem reflex es, questionamentos, discuss es, crítica e massa crítica, área de concentra o da "Ciência das Ciências" contemplada neste trabalho.
Novas tecnologias, educa o e contemporaneidade
Emanuel do Rosário Santos Nonato
Práxis Educativa , 2006,
Abstract: This paper addresses the problem of the Post Modernism and its consequences and inter-relations with the dynamics of Contemporary Education, mainly after the advent of the new Technologies of Information and Communication in the process of restructuring of Capitalism and the implementation of the Information mode of Production substituting the Industrial Mode of Production. It is a discussion about the place of Post Modernism in the Contemporary Society and the conceptual bases that define it, as they are confronted to the situation of Capitalism now a day. It is also a discussion about the implications of the new technologies of Information and Communication in the human cognitive processes.
Pergunta-resposta: como o par dialógico constrói uma aula na alfabetiza??o
Gomes-Santos, Sandoval Nonato;Almeida, Patrícia Sousa;
Revista Brasileira de Linguística Aplicada , 2009, DOI: 10.1590/S1984-63982009000100007
Abstract: this paper have as main goal to analyze the dialogic unity question-answer, which is fundamental for speech organization, in the interactions kept into a literacy class, occurred in a singular school environment the dialogic pair is examined in relation to professional teacher gestures, in order to observe the teacher's movement and his/her teaching style in the construction of this specific class. in the end, the focus on the questions is justified regardless the answers.
Pergunta-resposta: como o par dialógico constrói uma aula na alfabetiza o Question-answer: how the dialogic pair makes a literacy class
Sandoval Nonato Gomes-Santos,Patrícia Sousa Almeida
Revista Brasileira de Linguística Aplicada , 2009,
Abstract: Este artigo tem como pretens o analisar a unidade dialógica Pergunta-Resposta, fundamental para a organiza o conversacional, nas intera es mantidas em uma aula de alfabetiza o ocorrida em um contexto escolar singular. O par dialógico é examinado em rela o aos gestos profissionais docentes, de modo a observar o movimento da professora e seu estilo de docência na constru o da aula em quest o. Ao final, justifica-se o foco nas perguntas em detrimento das respostas. This paper have as main goal to analyze the dialogic unity Question-Answer, which is fundamental for speech organization, in the interactions kept into a literacy class, occurred in a singular school environment the dialogic pair is examined in relation to professional teacher gestures, in order to observe the teacher's movement and his/her teaching style in the construction of this specific class. In the end, the focus on the questions is justified regardless the answers.
Produtividade científica: impactos na normaliza o e na comunica o científica / Scientific productivity: impacts on standardization and scientific communication
Célia Maria Ribeiro,Raimundo Nonato Macedo dos Santos
ETD : Educa??o Temática Digital , 2006,
Abstract: Analisar das novas tendências na área de normaliza o no que se refere à apresenta o dos trabalhos acadêmicos do tipo teses e disserta es. O universo da pesquisa é a área de ciências biológicas da Universidade Estadual de Campinas, no período de 1999 a 2005. Dada a importancia da padroniza o para que a comunica o científica se efetive, destaca-se a necessidade de formular diretrizes mais consistentes para orientar os pesquisadores, de forma a atender tanto aos critérios de avalia o de produtividade científica como aos requisitos da qualidade formal das publica es. A aplica o de método qualitativo, por meio de entrevistas com os coordenadores de pós-gradua o e bibliotecários da área leva a algumas reflex es sobre o papel do bibliotecário, das agências de normaliza o e dos órg os de financiamento da pesquisa nesse novo cenário. The aim of this work is to analyze the new trends on standardization of academic publications, thesis and dissertations. The scope of the study is the Biological Sciences of The State University of Campinas from 1999 to 2005. Taking into consideration the importance of standardization to make scientific communication effective, it emphasizes the need to create more elaborated rules in order to help researchers, permitting them to attend both evaluation criteria of scientific production and quality requirements of publications. The use of the qualitative method, through interviews with the coordinators of graduate courses and librarians of the major studied brought some thinking about the librarian role, national organizations of standardization responsibility and also a brief comment on the legislation of Brazilian scientific dissemination.
Bibliometric study of the descriptor “Ergonomics” in LISA database Estudio bibliométrico del descriptor “Ergonomía” en la base LISA Estudo bibliométrico do descritor “Ergonomia” na base LISA
Eliana Maria dos Santos Bahia,Raimundo Nonato dos Santos Macedo,Ursula Blattmann
Biblios , 2011, DOI: 10.5195/biblios.2011.8
Abstract: Objective: The study analyzes the scientific literature on Eergonomics using the database Library and Information Science Abstracts (LISA). The LISA database, initiated in 1969, remains subject coverage in the area of Library and Information Science. Method: The study used the method of applied bibliometrics to verify the indexed scientific production. Results: The results of the search terms indexed in LISA database, found 503 items with the term "Ergonomics", 352 articles with the word "Design "; 111 items with the descriptor "Systems"; 110 items with the term "Work", and 98 articles with the term "Evaluation. ". Out the 34 titles of journals, 4 titles covered 79% of the articles dealing with Ergonomics in LISA database. The other 30 titles of journals magazines coveredring 21% of the articles indexed under that topic. Conclusions: This study evaluated a possible overview of how Ergonomics is perceived in the area of Library and Information Science. Objetivo: El estudio analiza la producción científica sobre ergonomía utilizando la base de datos Library and Information Science Abstracts (LISA). La base de datos LISA, iniciada en 1969, mantiene su cobertura temática en el área de Biblioteconomía y Ciencia de la Información. Método: En el estudio se utilizó el método de la bibliometría aplicada para verificar la producción científica indexada. Resultados: Entre los resultados de la búsqueda de términos indexados en la base de datos LISA, se encontraron 503 artículos con el término “Ergonomic”; 352 artículos, con la expresión “Design”; 111 artículos con el descriptor “Systems”; 110 artículos con el término “Work”; y , 98 artículos con el término “Evaluation”. De entre los 34 títulos de revistas, 4 títulos cubren un 79% de los artículos que tratan sobre Ergonomía en la base LISA. Los demás 30 títulos de revistas cubren un 21% de los artículos indexados bajo esa temática. Conclusiones: El presente estudio bibliométrico ofrece un panorama de cómo la ergonomía es percibida en el área de Biblioteconomía y Ciencia de la Información. Objetivo: O estudo analisa a produ o científica sobre ergonomia utilizando a base de dados Library and Information Science Abstracts (LISA). A base de dados LISA, iniciada em 1969, mantém sua cobertura temática na área de Biblioteconomia e Ciência da Informa o. Método: No estudo utilizou-se o método da bibliometria aplicada para verificar a produ o científica indexada. Resultados: Entre os resultados da busca de termos indexados na base de dados LISA, encontraram-se 503 artigos com o termo “Ergonomic”; 352 artigos, com a express
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