Abstract The kinetics and equilibrium of experimental data of mercury (II) sorption using three different macrophytes E. crassipes, E. azurea and S. ariculata were analyzed. From the kinetic models used, the model 1, which considers the surface area of constant sorption, presents the coefficient of determination, R2, closer to the unit (0.97). Already, in the liquid phase, the best fit of the experimental data was obtained for model 2 (R2=0.96), which considers the variable surface area. The calculated values for the determination coefficients indicate that the Redlich-Peterson isotherm best describes the equilibrium (R2=0.79). The results show that the macrophyte S. ariculata surface area, which presented the highest adsorption potential (15.77x10-4m2.g-1), was far below those found in the best adsorbents. However, considering the large volume of adsorbent material required in an industrial plant and the low cost of the analyzed adsorbents, it is considered that the macrophytes investigated have a considerable potential for the removal of mercury from wastewater.

Process control represents an important tool for meeting product quality, process safety and environmental regulation. Different control strategies have been recently proposed in the literature; however, internal model control (IMC) has received great attention. Fractional calculus represents a fast growing field involving non-integer order derivatives. The aim of this work is the application of fractional calculus to develop generalized internal model control loops transfer functions, which is presented in two different approaches: firstly, the process model is considered perfect, i.e., equal to the internal model; secondly, the internal model is described by fractional transfer function. Simulation results showed that the proposed generalization could successfully control an industrial oven and a biochemical reactor described by fractional models, allowing better results when compared to integer order IMC.

High production meeting product quality, process safety and environmental regulation provide to control systems a key role in biochemical plants operation. As a suitable mathematical model is essential for process control, this work reports an alternative tool, based on the use of fractional order differential equations, for biochemical reactor identification using previously reported experimental data. Three different approaches were considered: i) solving the nonlinear set of algebraic equations obtained from the derivatives of the objective function with respect to the parameters; ii) solving a multivariable nonlinear deterministic optimization problem; iii) solving a multivariable nonlinear heuristic optimization problem. All identified models were submitted to statistical fitting tests and the second approach (ii) proved to be the most efficient for process identification, satisfying all statistical tests. Common integer order models were identified, leading to poorer data fit when compared to the fractional model, proving the usefulness and success identification tool proposed.

Avaliaram-se a taxa de acúmulo foliar (TAF), a produção total de forragem (PTF), a composição química da forragem e os valores de digestibilidade in vitro da matéria seca (DIVMS) do coastcross (Cynodon dactylon) e do amendoim forrageiro (Arachis pintoi) em pastagem consorciada. Foram avaliados os tratamentos (parcelas): coastcross + A. pintoi sem nitrogênio (CA0); coastcross + A. pintoi com 100kg de nitrogênio (CA100); coastcross com 200kg de nitrogênio (C200) e coastcross + A. pintoi com 200kg de nitrogênio (CA200), e as estações (subparcelas) do ano inverno, primavera, verão e outono. Utilizou-se um delineamento experimental em blocos ao acaso, em esquema de parcelas subdivididas no tempo, com duas repetições. Os tratamentos com os maiores níveis de adubação de nitrogênio apresentaram TAF mais alto que os demais (P<0,05). No verão ocorreu a maior PTF, seguida da primavera, outono e inverno, mas estes não diferiram entre si. Não houve diferença (P>0,05) entre os tratamentos para as variáveis proteína bruta, fibra em detergente neutro e digestibilidade in vitro de matéria seca, tanto para as frações de folhas do coastcross, como para a planta inteira do A. pintoi. A adubação nitrogenada, quando aplicada à pastagem de coastcross singular ou associada ao amendoim forrageiro, proporcionou aumento da TAF e da PTF, com maior produtividade e qualidade no verão.

Forage accumulation rate (FAR), total forage production (TFP), chemical composition and in vitro dry matter digestibility (IVDMD) of coastcross pasture mixed with Arachis pintoi (AP) were evaluated. Treatments plots were: coastcross + A. pintoi without N (CA0); coastcross + A. pintoi with 100kg of N (CA100); coastcross with 200kg of N (C200); and coastcross + A. pintoi with 200kg of N (CA200); and seasons of the year (split-plots): winter, spring, summer, and autumn were analyzed. A randomized block design was used subdivided into time plots, with two replications. Treatments with the highest fertilizer levels presented higher FAR than others (P<0.05), with higher TFP during the summer, followed by spring, autumn, and winter, with no differences among then. There were no differences (P>0.05) among treatments for CP, NDF, and IVDMD on coastcross leaf fractions and Arachis pintoi whole plant. Nitrogen fertilization, when applied to single coastcross pasture or mixed with forage peanut, increased accumulation rate and forage accumulation, with higher productivity and quality in summer.

We address this work to investigate symbolic sequences with long-range correlations by using computational simulation. We analyze sequences with two, three and four symbols that could be repeated l times, with the probability distribution p(l) ∝ 1/l µ. For these sequences, we verified that the usual entropy increases more slowly when the symbols are correlated and the Tsallis entropy exhibits, for a suitable choice of q, a linear behavior. We also study the chain as a random walk-like process and observe a nonusual diffusive behavior depending on the values of the parameter µ.

We investigate solutions, by using the Green function approach, for a system governed by a non-Markovian Fokker-Planck equation and subjected to a Comb structure. This structure consists of the axis of structure as the backbone and fingers which are attached perpendicular to the axis. For this system, we consider an arbitrary initial condition, in the presence of time dependent diffusion coefficients and spatial fractional derivative, and analyze the connection to the anomalous diffusion.

We argue that nonlocal effects represented by fractionary terms in the kinetic energy can be relevant to achieve a satisfactory phenomenological description of the thermal behavior of the specific heat of non-crystalline solids at very low temperature. We propose a simple model formed by the direct sum of two Hamiltonians, one of which is obtained by incorporating fractional derivatives in the kinetic energy of a conventional Hamiltonian, and the other one accounts for the presence of phonons in the system. Some experimental data are used to support the proposed description.

Com vistas em avaliar a dinâmica do cádmio no sistema solo-planta, instalou-se um experimento em colunas de PVC (0,10 m de diâmetro e 0,80 m de altura), preenchidas com amostras de Latossolo Vermelho distrófico típico com 320 g kg-1 de argila (elevou-se V % a 70) onde se aplicou biossólido (pH 6) contaminado com Cd, incorporado na camada de 0-0,2 m da coluna. Os tratamentos com biossólido contaminado com cádmio foram (mg kg-1): 0 (testemunha), 2.500 e 5.000 de Cd e dois adicionais (2.500 Cd + 2.500 Pb e 5.000 Cd + 5.000 Pb). Cultivou-se milho nas colunas por um período de 80 dias. As concentrações de Cd nas amostras de solo e na parte aérea do milho foram determinadas em extrato nitro-perclórico. A alta concentração do Cd no solo restringiu-se apenas à camada de incorporação, não havendo lixiviação do elemento na coluna do solo. A concentração de 12 mg kg-1 de Cd não foi suficiente para provocar sintomas visuais de fitotoxidez de Cd em milho. O Pb adicionado juntamente com o Cd não apresentou interferência no sistema solo-planta.

Cadmium dynamics in the soil-plant system were evaluated in an experiment with a Typic Hapludox (320 g kg-1 of clay) PVC columns (diameter 0.10 m, height 0.80 m) were filled with soil samples (V % elevated to 70), and the surface layer (0-0.2 m) supplemented with Cd-contaminated biosolid (sewage sludge, pH 6). The biosolid treatments were contaminated as follows (in mg kg-1): 0 (control) 2,500 of Cd, 5,000 of Cd, 2,500 of Cd + 2,500 of Pb, and 5,000 of Cd + 5,000 of Pb. The soil columns were cultivated with maize for a period of 80 days. The total Cd concentrations in the soil samples and maize shoots were determined using nitro-perchloric extraction solution. There was no percolation of Cd into the soil column, so the high amounts of cadmium remained in the surface layer. The concentration of 12 mg kg-1 of Cd in the maize shoots was not enough to cause visible toxicity symptoms in the plants. Pb, applied together with Cd, did not affect the soil-plant system.

The generalized Bose-Einstein distribution, within the dilute gas assumption, in the nonextensive Tsallis statistics is worked without approximation for the Bose-Einstein condensation (BEC). The results obtained are compared with the recent results presented in Int. J. Mod. Phys. B 14, 405 (2000) by L. Salasnich. Furthermore, in order to promote a complete analysis for the BEC in the nonextensive scenario we also find exact expression within the normalized constraints in a harmonic trap.

The collagen structure of isolated and in situ liver granuloma from Swiss Webster mice infected with Schistosoma mansoni was sequentially and three-dimensionally analyzed during different times of infection (early acute, acute, transitional acute-chronic, and chronic phases) by laser scanning confocal microscopy and electron scanning variable vacuum microscopy. The initial granuloma structure is characterized by vascular collagen residues and by anchorage points (or fiber radiation centers), from where collagenous fibers are angularly shed and self-assembled. During the exudative-productive stage, the self-assembly of these fibers minimizes energy and mass through continuous tension and focal compression. The curvature or angles between collagen fibers probably depends on the fibroblastic or myofibroblastic organization of stress fibers. Gradually, the loose unstable lattice of the exudative-productive stage transforms into a highly packed and stable architecture as a result of progressive compactness. The three-dimensional architecture of granulomas provides increased tissue integrity, efficient distribution of soluble compounds and a haptotactic background to the cells.

During Schistosoma mansoni infection, there is morphological evidence of involvement of various hematopoietic growth factors, which cause eosinophil, neutrophil, megakaryocytic and erythroid extramedullary foci in the liver, lymph nodes and omental and mesenteric milky spots. While the eosinophil metaplasia in the periphery of hepatic granulomas roughly reproduced the intensity of the medullary eosinopoiesis, the neutrophil metaplasia, on the contrary, was more intense during the period of neutrophil depression in the bone marrow. This fact suggests that extramedullary hematopoietic foci are locally regulated, and amplify and/or compensate the systemic hematopoietic response during the infection.

Twenty Calomys callosus, Rengger, 1830 (Rodentia-Cricetidae) were studied in the early stage of the acute schistosomal mansoni infection (42nd day). The same number of Swiss Webster mice were used as a comparative standard. Liver and intestinal sections, fixed in formalin-Millonig and embedded in paraffin, were stained with hematoxilin and eosin, PAS-Alcian Blue, pH = 1.0 and 2.5, Lennert's Giemsa, Picrosirius plus polarization microscopy, Periodic acid methanamine silver, Gomori's silver reticulin and resorcin-fuchsin. Immunohistological study (indirect immunofluorescence and peroxidase labeled extravidin-biotin methods) was done with antibodies specific to pro-collagen III, fibronectin, elastin, condroitin-sulfate, tenascin, alpha smooth muscle actin, vimentin and desmin. The hepatic granulomas were small, reaching only 27 of the volume of the hepatic Swiss Webster granuloma. They were composed mainly by large immature macrophages, often filled by schistosomal pigment, characterizing an exsudative-macrophage granuloma type. The granulomas were situated in the parenchyma and in the portal space. They were often intravascular, poor of extracellular matrix components, except fibronectin and presented, sometimes alpha smooth muscle actin and vimentin positive cells. The C. callosus intestinal granulomas were similar to Swiss Webster, showing predominance of macrophages. Therefore, the C. callosus acquire very well the Schistosoma mansoni infection, without developing strong hepatic acute granulomatous reaction, suggesting lack of histopathological signs of hypersensitivity.