Estudo do potencial poluidor da atividade de revenda de combustíveis líquidos na cidade de Natal (RN): justificativas para a implantação da rotulagem ambiental (Selo Verde)

This work presents the analysis of data collected by Universidade Federal do Rio Grande do Norte and State Public Prosecution Office experts concerning to current situation of liquid fuel resale stations, its forms of storage and its technical apparatus for the performance of primary functions (supply of vehicles) and secondary (car washing, storage of used oil, oil change etc.). The data presented were analyzed in the setting of the city of Natal (RN) and considering its characteristics, potentialities and weaknesses. Thereafter, it was discussed liquid fuels resale pollution potential in the city and legal provisions directed to implementation of Green Seal. The discussion involves three agents: environmental, legal and technical ones, applied to all 110 resale fuel stations which were analyzed

Separação de cristais de estruvita de percolado de lodo por flotação por ar dissolvido

The struvite precipitation in wastewater treatments plants offer advantages to obtaining a economically viable product, containing phosphorus, nitrogen and magnesium, in a bioavailable conditions to plants. The precipitation process requires ideal conditions, but all of these aspects are difficult to obtain and may result in resistance to collect crystals during the sedimentation process. Therefore, instead find the best conditions for precipitation, we propose the dissolved air flotation as another method to retrieve the crystals. The application of dissolved air flotation method to promote separation of struvite crystals from sewage supernatant, was evaluated in a precipitation-flotation reactor (flotatest) and were compared with the precipitation-sedimentation assays (jar test). Finally, were observed that the dissolved air flotation process was as feasible as sedimentation to promote struvite crystals separation, and the pH are the most influencer factor for an efficient separation

Espectro de Polariton de Plasmons e Ondas de Luz em Quasi-Cristais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Excitações em cristais fotônicos unidimensionais

In this work, we present a theoretical study of the propagation of electromagnetic waves in multilayer structures called Photonic Crystals. For this purpose, we investigate the phonon-polariton band gaps in periodic and quasi-periodic (Fibonacci-type) multilayers made up of both positive and negative refractive index materials in the terahertz (THz) region. The behavior of the polaritonic band gaps as a function of the multilayer period is investigated systematically. We use a theoretical model based on the formalism of transfer matrix in order to simplify the algebra involved in obtaining the dispersion relation of phonon-polaritons (bulk and surface modes). We also present a quantitative analysis of the results, pointing out the distribution of the allowed polaritonic bandwidths for high Fibonacci generations, which gives good insight about their localization and power laws. We calculate the emittance spectrum of the electromagnetic radiation, in THZ frequency, normally and obliquely incident (s and p polarized modes) on a one-dimensional multilayer structure composed of positive and negative refractive index materials organized periodically and quasi-periodically. We model the negative refractive index material by a effective medium whose electric permittivity is characterized by a phonon-polariton frequency dependent dielectric function, while for the magnetic permeability we have a Drude like frequency-dependent function. Similarity to the one-dimensional photonic crystal, this layered effective medium, called polaritonic Crystals, allow us the control of the electromagnetic propagation, generating regions named polaritonic bandgap. The emittance spectra are determined by means of a well known theoretical model based on Kirchoff s second law, together with a transfer matrix formalism. Our results shows that the omnidirectional band gaps will appear in the THz regime, in a well defined interval, that are independent of polarization in periodic case as well as in quasiperiodic case

Ondas de spin em quasi-cristais magnônicos

In this paper we investigate the spectra of band structures and transmittance in magnonic quasicrystals that exhibit the so-called deterministic disorders, specifically, magnetic multilayer systems, which are built obeying to the generalized Fibonacci (only golden mean (GM), silver mean (SM), bronze mean (BM), copper mean (CM) and nickel mean (NM) cases) and k-component Fibonacci substitutional sequences. The theoretical model is based on the Heisenberg Hamiltonian in the exchange regime, together with the powerful transfer matrix method, and taking into account the RPA approximation. The magnetic materials considered are simple cubic ferromagnets. Our main interest in this study is to investigate the effects of quasiperiodicity on the physical properties of the systems mentioned by analyzing the behavior of spin wave propagation through the dispersion and transmission spectra of these structures. Among of these results we detach: (i) the fragmentation of the bulk bands, which in the limit of high generations, become a Cantor set, and the presence of the mig-gap frequency in the spin waves transmission, for generalized Fibonacci sequence, and (ii) the strong dependence of the magnonic band gap with respect to the parameters k, which determines the amount of different magnetic materials are present in quasicrystal, and n, which is the generation number of the sequence k-component Fibonacci. In this last case, we have verified that the system presents a magnonic band gap, whose width and frequency region can be controlled by varying k and n. In the exchange regime, the spin waves propagate with frequency of the order of a few tens of terahertz (THz). Therefore, from a experimental and technological point of view, the magnonic quasicrystals can be used as carriers or processors of informations, and the magnon (the quantum spin wave) is responsible for this transport and processing

Espectros fractais em sistemas nanoestruturados e cristais fotônicos

The study of the elementary excitations such as photons, phonons, plasmons, polaritons, polarons, excitons and magnons, in crystalline solids and nanostructures systems are nowdays important active field for research works in solid state physics as well as in statistical physics. With this aim in mind, this work has two distinct parts. In the first one, we investigate the propagation of excitons polaritons in nanostructured periodic and quasiperiodic multilayers, from the description of the behavior for bulk and surface modes in their individual constituents. Through analytical, as well as computational numerical calculation, we obtain the spectra for both surface and bulk exciton-polaritons modes in the superstructures. Besides, we investigate also how the quasiperiodicity modifies the band structure related to the periodic case, stressing their amazing self-similar behavior leaving to their fractal/multifractal aspects. Afterwards, we present our results related to the so-called photonic crystals, the eletromagnetic analogue of the electronic crystalline structure. We consider periodic and quasiperiodic structures, in which one of their component presents a negative refractive index. This unusual optic characteristic is obtained when the electric permissivity and the magnetic permeability µ are both negatives for the same range of angular frequency ω of the incident wave. The given curves show how the transmission of the photon waves is modified, with a striking self-similar profile. Moreover, we analyze the modification of the usual Planck´s thermal spectrum when we use a quasiperiodic fotonic superlattice as a filter.

Relação entre heterogeneidade ambiental e distribuição de espécies em uma floresta paludosa no Município de Cristais Paulista, SP, Brasil

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

A influência do fator de vibração térmica na densidade eletrônica de cristais bidimensionais

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

Síntese e caracterização de esferas monodispersas de látex e sua utilização no preparo de filmes de cristais coloidais tridimensionais

Esferas de poliestireno foram obtidas através da polimerização do estireno sem a presença de emulsificante. A suspensão foi caracterizada por Espalhamento de Luz e Microscopia Eletrônica de Transmissão apresentando monodispersidade com tamanho em torno de 463 nm. O método de deposição vertical foi utilizado para preparar filmes em substratos de vidro a partir da suspensão de esferas. Filmes de opalas de alta qualidade foram obtidos e caracterizados por Espectroscopia de Reflectância, Microscopia Eletrônica de Varredura e Microscopia Óptica.

Análise florística e estrutural do componente arbustivo-arbóreo de uma floresta de galeria no Município de Cristais Paulista, SP, Brasil

Remanescentes florestais na porção nordeste do Estado de São Paulo são ainda pouco estudados quanto à composição florística. Foi realizado o levantamento florístico e fitossociológico de uma floresta de galeria no Município de Cristais Paulista visando à caracterização da flora do remanescente e o estudo das relações florísticas com outras formações ribeirinhas. Para o levantamento fitossociológico foi utilizado o método de ponto-quadrante. em quatro transeções paralelas ao curso d'água, foram estabelecidos 90 pontos eqüidistantes em 10 metros e amostrados os indivíduos com PAP > 15 cm. Espécies em estágio reprodutivo, não amostradas no levantamento fitossociológico, foram coletadas e identificadas. Foram encontradas 68 espécies, distribuídas em 37 famílias, das quais 53 espécies e 34 famílias foram amostradas no levantamento fitossociológico. O índice de diversidade (H') para as espécies foi de 3,17 nats indivíduo-1 e as espécies mais importantes (em VI) foram Virola sebifera, Protium heptaphyllum, Tapirira guianensis e Copaifera langsdorffii. A comparação com outras florestas ribeirinhas evidenciou uma maior semelhança florística com as florestas situadas principalmente na bacia do Rio Grande, possivelmente devido às condições semelhantes de clima, e no Brasil Central, devido à rede de drenagem que atua como rota migratória das espécies. Foram encontradas também muitas espécies compartilhadas com os cerrados, evidenciando a contribuição da flora desse domínio para a floresta de galeria estudada.

Medição de viscosidade de líquidos pelo método de múltiplas reflexões acústicas com conversão de modo

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

Padrões de distribuição de líquidos obtidos com bicos TF-VS4, TJ60-11006 e TQ15006 em mesa de prova

The performance of a spray boom can be evaluated from its individual nozzle distribution patterns determined in a patternator (test table), as discussed by Perecin et al. (1994). The distribution pattern of three nozzle types obtained in a patternator at six heights were compared in order to propose a formula for determining the variation coefficient. The simulation of a spray boom was conducted from individual nozzle distribution patterns, and obtained the random variation coefficients (RVC) and the systematic variation coefficients (SVC). The results showed good performance of the TF-SV4 nozzles, with CV smaller than 10%, for nozzle spacing as large as 50 cm. The TQ15006 nozzles showed high variability in the central region of the distribution pattern, resulting in high CV from nozzle spacings as narrow as 25 cm. The TJ60-11006 behaved as intermediate between TF-VS4 and TQ15006. The formula proposed for determining the variation coefficient is [(RVC) 2+(SVC) 2] 1/2.

Activos líquidos: derechos de aguas, mercados de aguas y consecuencias para los mercados de tierras rurales

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Biocombustibles líquidos para transporte en América Latina y el Caribe

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Producción de biomasa para biocombustibles líquidos: el potencial de América Latina y el Caribe

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