A DFT Study of Structural and Electronic Properties of ZnS Polymorphs and its Pressure-Induced Phase Transitions

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mudanças climáticas: o discurso da mídia sobre o aquecimento global

This research is aimed at discussing the ways in which social agents influence global warming, analyzing the discourse of social actors involved in the debate on climate change, since there is a wide divergence in the scientific community about how man is able to modify the climate on a global scale. In fact the debate that permeates the issues beyond the limits of science and enter into a political-economic framework that takes extraordinary proportions. This emphasis can be very unscientific in the fundamental design concepts, or even creating a trivialization of the media. The main way to convey these concepts is to disclose them in the media, but the media has enormous power to transform the concepts and often manipulate the news by creating a common sense goes against the interests of the scientific community. Thus was conducted extensive research in major newspapers and magazines that move in the country. We surveyed the first two papers which were: “Folha de S. Paulo” and “O Estado de S. Paulo”, during the period from January 2000 to December 2008, totaling 3285 units for the newspaper Folha and 2555 for the newspaper Estadão. Subsequently a survey was made of data published in two journals that move at the national level, and these are the magazines VEJA and ÉPOCA for the same period. By performing these steps, it was concluded that several factors involving the media and climate change, such as topic relevance, types of approaches, perspectives of analysis, the staff development, supplies, among other factors of utmost importance for building news. As a result we can say that the media in fulfilling its role of mediator scientific, disclosing only a vision that permeates the scientific debate. The newspaper media, especially newspapers, has an informative and instantaneous. Often this preoccupation...(Complete abstract, click electronic access below)

Production and Characterization of Composite Material Useful as a Protective Barrier in Electronic Applications

This work describes the production and characterization of a selective membrane useful for electronic devices. The membrane was a composite made by a thin film of plasma-polymerized HFE (methyl nonafluoro(iso)butyl ether) immersed in plasma-polymerized HMDS (hexamethyldisilazane) film, a third phase being 5 µm starch particles included in this matrix. The film was deposited on silicon substrates and its physical, chemical and adsorption characteristics were determined. Infrared and x-ray photoelectron spectroscopy analyses showed fluorine and carboxyl groups on the bulk and the surface, respectively. SEM results indicate the film is conformal even if starch is present. Optical microscopy analysis showed good resistance toward acid and base solutions. Quartz crystal microbalance indicated adsorption of polar organic compounds on ppm range. This thin film is environment-friendly and can be used as a protective layer or in electronic devices due to adsorption of volatile organic compounds.

Capacitive DNA detection driven by electronic charge fluctuations in a graphene nanopore

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

Electronic structure calculations of ESR parameters of melanin units

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

Microfluidic electronic tongue

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

Theoretical study of molecular and electronic structures of 5(1) knot systems: two-layered ONIOM calculations

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

The correlation between electronic structure and antimalarial activity of tetrahydropyridines

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

A joint experimental and theoretical study on the electronic structure and photoluminescence properties of Al-2(WO4)(3) powders

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A relationship between structural and electronic order-disorder effects and optical properties in crystalline TiO2 nanomaterials

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

Local order and magnetic field effects on the electronic properties of disordered binary alloys in the quantum site percolation limit

Electronic properties of disordered binary alloys are studied via the calculation of the average Density of States (DOS) in two and three dimensions. We propose a new approximate scheme that allows for the inclusion of local order effects in finite geometries and extrapolates the behavior of infinite systems following finite-size scaling ideas. We particularly investigate the limit of the Quantum Site Percolation regime described by a tight-binding Hamiltonian. This limit was chosen to probe the role of short range order (SRO) properties under extreme conditions. The method is numerically highly efficient and asymptotically exact in important limits, predicting the correct DOS structure as a function of the SRO parameters. Magnetic field effects can also be included in our model to study the interplay of local order and the shifted quantum interference driven by the field. The average DOS is highly sensitive to changes in the SRO properties and striking effects are observed when a magnetic field is applied near the segregated regime. The new effects observed are twofold: there is a reduction of the band width and the formation of a gap in the middle of the band, both as a consequence of destructive interference of electronic paths and the loss of coherence for particular values of the magnetic field. The above phenomena are periodic in the magnetic flux. For other limits that imply strong localization, the magnetic field produces minor changes in the structure of the average DOS. © World Scientific Publishing Company.

A new approach to the electronic structure of two dimensional disordered alloys

We propose a novel method to calculate the electronic Density of States (DOS) of a two dimensional disordered binary alloy. The method is highly reliable and numerically efficient, and Short Range Order (SRO) correlations can be included with no extra computational cost. The approach devised rests on one dimensional calculations and is applied to very long stripes of finite width, the bulk regime being achieved with a relatively small number of chains in the disordered case. Our approach is exact for the pure case and predicts the correct DOS structure in important limits, such as the segregated, random, and ordered alloy regimes. We also suggest important extensions of the present work. © 1995.

First-principles simulation of elastic constants and electronic properties of GaN

The electronic and structural properties and elastic constants of the wurtzite phase of GaN, was investigated by computer simulation at Density Functional Theory level, with B3LYP and B3PW hybrid functional. The electronic properties were investigated through the analysis of the band structures and density of states, and the mechanical properties were studied through the calculus of the elastic constants: C11, C33, C44, C12, and C13. The results show that the maximum of the valence band and the minimum of the conduction band are both located at the Γ point, indicating that GaN is a direct band gap semiconductor. The following constants were obtained for B3LYP and B3PW (in brackets): C11 = 366.9 [372.4], C33 = 390.9 [393.4], C44 = 99.1 [96.9], C12 = 143.6 [155.2], and C13 = 107.6 [121.4].

Multifunctional current reference generation strategy for grid-tied power electronic converter

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

Estados emocionais e atividade física em idosos: contribuições da literatura brasileira

This study with qualitative nature aims to analyze the impact of external factors on mood states, considering physical activity as an important factor to improve not only the physical, but also psychological factors, especially when we think of the activities performed in-group. Thus, a literature review was conducted in order to investigate in books, journals, scientific papers published in magazines, newspapers and electronic platforms the influence of exercise on emotional states of elderly people. The terms used across the curriculum contributed to the conformity of ideas on the subject. By checking some researches, it can be seen that external factors such as music, local infrastructure, professional relationship with the elderly people and other factors have been suggested as possible influencers of humor in physical activity. Knowing the preferences beyond the close contact with the elderly student, is the best way to affect possible aspects of the activity beyond just preventing circumvention of activity, avoiding sedentary lifestyle that will bring risks to the health of the elderly people