Cogeneration in integrated first and second generation ethanol from sugarcane

Sugarcane bagasse and trash are used as fuels in cogeneration systems for bioethanol production, supplying steam and electricity, but may also be used as feedstock for second generation ethanol. The amount of surplus lignocellulosic material used as feedstock depends on the energy consumption of the production process; residues of the pretreatment and hydrolysis operations (residual cellulose, lignin and eventually biogas from pentoses biodigestion) may be used as fuels and increase the amount of lignocellulosic material available as feedstock in hydrolysis. The configuration of the cogeneration system (boiler pressure, lignocellulosic material consumption and steam production, turbines efficiencies, among others) has a significant impact on consumption of fuel and electricity output; in the integrated first and second generation, it also affects overall ethanol production. Simulations of the integrated first and second generation ethanol production processes were carried out using Aspen Plus, comparing different configurations of the cogeneration systems and pentoses use (biodigestion and fermentation). Economic analysis shows that electricity sale can benefit second generation ethanol, even in relatively small amounts. Environmental analysis shows that the integrated first and second generation process has higher environmental impacts in most of the categories evaluated than first generation.     

Phase‐dependent binary interaction parameters in industrial low‐density polyethylene separators

In the production process of low‐density polyethylene (LDPE), an important step is the flash separation of monomers and other small molecules from the polymer produced. The process is carried out adiabatically in two stages. To improve the performance of thermodynamic models, it is very important to analyze the use of model binary interaction parameters (BIP) dependent on the phase characteristics for each phase (phase‐dependent BIP). In this work the PC‐SAFT (perturbed‐chain statistical associating fluid theory) equation of state (EOS) is applied to the flash simulation of LDPE industrial separators using eight different resins. The main numerical aspects are examined with emphasis on the optimization strategy for the EOS BIP that explicitly characterizes each phase involved separately. The results demonstrate good predictive behavior. As a result of improved and more consistent modeling, a new strategy for optimized operation can be envisaged for the sequence of separators. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2106–2117, 2013     

Influence of operational parameters on the performance of PEMFCs with serpentine flow field channels having different (rectangular and trapezoidal) cross-section shape

The effect of operational parameters on the performance of PEMFCs by using serpentine flow field channels with different (rectangular and trapezoidal) cross-section shape has been investigated. More than cell temperature and pressure, reactant humidification temperature (T_ha,c) has a significant influence on the effect of serpentine channels with trapezoidal cross-section on cell performance. The high capability of water removal by serpentine channels with trapezoidal cross-section positively affects the fuel cell performance when the water content in the system is high, as in the case of the reactant humidification temperature higher than cell temperature (T_c). On the contrary, when the water content in the cell is low, as in the case of T_ha,c = T_c, the high ability of water removal of serpentine channels with trapezoidal cross-section results in a less effective membrane/cathode hydration. Conversely, the effect of T_ha,c on the performance of the cell with serpentine channels with rectangular cross-section is negligible.     

Classification of juices and fermented beverages made from unripe,ripe and senescent apples based on the aromatic profile using chemometrics

The aim of this study was to assess differences between apple juices and fermented apple beverages elaborated with fruits from different varieties and at different ripening stages in the aroma profile by using chemometrics. Ripening influenced the aroma composition of the apple juice and fermented apple. For all varieties, senescent fruits provided more aromatic fermented apple beverages. However, no significant difference was noticed in samples made of senescent or ripe fruits of the Lisgala variety. Regarding the juices, ripe Gala apple had the highest total aroma concentration. Ethanal was the major compound identified in all the samples, with values between 11.83 mg/L (unripe Lisgala juice) and 81.05 mg/L (ripe Gala juice). 3-Methyl-1-butanol was the major compound identified in the fermented juices. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied and classified the juices and fermented juices based on physicochemical and aroma profile, demonstrating their applicability as tools to monitor the quality of apple-based products.     

Modulatory effects of yerba maté (Ilex paraguariensis) on the PI3K‐AKT signaling pathway

The aim of this study was to evaluate the effects of yerba maté (YM) extract on the phosphatidylinositol 3‐kinase (PI3K)‐AKT signaling pathway in vivo. The mice were introduced to either standard‐ or high‐fat diet (HFD). After 8 weeks on an HFD, mice were randomly assigned to one of the two treatment conditions, water or yerba maté extract at 1.0 g/kg. After treatment, glucose blood level and hepatic insulin response were evaluated. Liver tissue was examined to determine the mRNA levels using the PI3K‐AKT PCR array. The nuclear translocation of forkhead box O1 (FOXO1) was determined by an electrophoretic mobility‐shift assay. Our data demonstrated that yerba maté extract significantly decreased the final body weight, glucose blood levels, and insulin resistance of mice. Molecular analysis demonstrated that an HFD downregulated Akt2, Irs1, Irs2, Pi3kca, Pi3kcg, and Pdk1; after yerba maté treatment, the levels of those genes returned to baseline. In addition, an HFD upregulated Pepck and G6pc and increased FOXO1 nuclear translocation. The intervention downregulated these genes by decreasing FOXO1 nuclear translocation. The results obtained demonstrate for the first time the specific action of yerba maté on the PI3K‐AKT pathway, which contributed to the observed improvement in hepatic insulin signaling.     

Revitalization and analysis of operation of the autonomous photovoltaic system of the Uacari Floating Lodging House,Amazon‐Brazil

This paper presents the main problems found in photovoltaic systems in the Amazon Region and the actions to be performed for restructuring and correcting the operation of such systems. These problems and solutions are exemplified on the basis of the diagnosis and revitalization of the 2.5‐kWp photovoltaic installation that belongs to the central module of the Uacari Floating Lodging House. The paper was accomplished as part of the agreement between the Group of Studies and Development of Energy Alternatives (GEDAE) and the Mamirauá Institute of Sustainable Development to assess several photovoltaic facilities in the area covered by the institute. Concluding the paper, some operational results of the revitalized system are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Morphometric,quantitative, and three‐dimensional analysis of the heart muscle fibers of old rats: Transmission electron microscopy and high‐resolution scanning electron microscopy methods

This research investigated the morphological, morphometric, and ultrastructural cardiomyocyte characteristics of male Wistar rats at 18 months of age. The animals were euthanized using an overdose of anesthesia (ketamine and xylazine, 150/10 mg/kg) and perfused transcardially, after which samples were collected for light microscopy, transmission electron microscopy, and high‐resolution scanning electron microscopy. The results showed that cardiomyocyte arrangement was disposed parallel between the mitochondria and the A‐, I‐, and H‐bands and their M‐ and Z‐lines from the sarcomere. The sarcomere junction areas had intercalated disks, a specific structure of heart muscle. The ultrastructural analysis revealed several mitochondria of various sizes and shapes intermingled between the blood capillaries and their endothelial cells; some red cells inside vessels are noted. The muscle cell sarcolemma could be observed associated with the described structures. The cardiomyocytes of old rats presented an average sarcomere length of 2.071 ± 0.09 μm, a mitochondrial volume density (Vv) of 0.3383, a mitochondrial average area of 0.537 ± 0.278 μm², a mitochondrial average length of 1.024 ± 0.352 μm, an average mitochondrial cristae thickness of 0.038 ± 0.09 μm and a ratio of mitochondrial greater length/lesser length of 1.929 ± 0.965. Of the observed mitochondrial shapes, 23.4% were rounded, 45.3% were elongated, and 31.1% had irregular profiles. In this study, we analyzed the morphology and morphometry of cardiomyocytes in old rats, focusing on mitochondria. These data are important for researchers who focus the changes in cardiac tissue, especially changes owing to pathologies and drug administration that may or may not be correlated with aging. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Laminar and turbulent free convection in a composite enclosure

Turbulent natural convection in a two-dimensional horizontal composite square cavity, isothermally heated at the left side and cooled from the opposing surface, is numerically analyzed using the finite volume method. The composite square cavity is formed by three distinct regions, namely, clear, porous and solid region. The development of a numerical tool able to treat all these regions as one computational domain is of advantage for engineering design and analysis of passive thermal control systems. Governing equations are written in terms of primitive variables and are recast into a general form. It was found that the fluid begins to permeate the porous medium for values of Ra greater than 10⁶. Nusselt number values show that for the range of Ra analyzed there is no significant variation between the laminar and turbulent model solution. When comparing the effects of Ra, k_s/k_f and Da on Nu, results indicate that the solid phase properties have a greater influence in enhancing the overall heat transferred trough the cavity.     

Computation of turbulent heat transfer in a moving porous bed using a macroscopic two-energy equation model

Heat transfer between phases in a moving porous bed is analyzed. This work proposes a set of transport equations for solving problems involving turbulent flow and heat transfer in a moving bed equipment. The device is modeled as a saturated porous matrix in which the solid phase moves with a steady imposed velocity. Additional drag terms appearing the momentum equation, as well as interfacial heat transfer between phases, are assumed to be a function of the relative velocity between the fluid and solid phases. Turbulence transport equations are here also dependent on the speed of the solid material. Results indicate that, as the phases attain velocities of equal order, turbulence in damped and heat transfer between solid and fluid occurs mainly by conduction mechanism.