The Brazilian semi-arid region is composed of a landscape mosaic that reflects a complex and diversified soil cover. In this context, research that integrates geology and geomorphology can efficiently guide pedological investigations in heterogeneous environments. This research was aimed at evaluating the soil-landscape relationships and their correlation with soil attributes in a toposequence over granites in the semi-arid region (Caatinga) of Northeastern Brazil. A transect was delimited in the landscape, and in each slope segment, a soil profile was described and sampled, namely: a) summit (P1); b) shoulder (P2); (c) backslope (P3), and; footslope (P4). Physical and chemical attributes were evaluated. Mineralogical analyses of sand, silt, and clay fractions were conducted by X-ray diffraction, and the total contents of major elements were determined by X-ray fluorescence. An E horizon in the upper third confirms that argilluviation is an active process in this landscape segment. Elutriation and argillization (in situ clay formation) also form the textural gradient, including in the foothill segment, producing Lixisols with strong rubification in the Bt horizon. Expansive clays (e.g., montmorillonite) contribute to vertisolization and the higher exchangeable and total calcium and magnesium contents in the top and foothill segments (Vertisols). At the summit, the melanization of the Bw diagnostic horizon is also evident. The variation in morphological, physical, chemical, and mineralogical attributes under similar parent materials confirms the role of relief in the distribution of materials along the toposequence and in the genesis of soils.
Brazil is the world’s leading producer of sugarcane, and its bagasse constitutes a substantial biomass resource with a strong potential for renewable energy production via pyrolysis. The development of mathematical models capable of accurately representing pyrolysis phenomena is, therefore, essential for advancing process understanding and optimization. In this study, the influence of biomass particle injection location on pyrolysis conversion rates in a spouted bed reactor was investigated. A CFD Eulerian-Lagrangian model was developed and implemented in OpenFOAM. Model validation involved two preliminary steps: the simulation of single-particle pyrolysis to evaluate reaction kinetics and the simulation of the inert particle bed dynamics. Subsequently, three pyrolysis simulations were performed, varying the biomass injection point: the annular region, the fountain region, and the region above the fountain. Numerical results were validated against experimental data from the literature. Tar and gas production and particle temperature evolution were analyzed for each configuration, all exhibiting characteristic spouted bed behavior. The results demonstrated that biomass injection into the fountain region yielded the highest performance, resulting in a conversion rate of 54.65
This study evaluated the long-term effects of contrasting crop systems on soil physical properties in a tropical Planosol after 12 years of continuous management. The experimental design included a Crop–Livestock–Forest Integration (CLFI) system, two monocropping systems (MFS1 and MFS2), and a natural ecosystem (as reference), with soil samples collected at three depths (0–10, 10–20, and 20–30 cm) to assess the interaction between management and profile position. A comprehensive set of physical attributes was measured, including texture, bulk density, compaction indicators, macroporosity, total porosity, water-filled pore space, mean weight diameter, and water-stable aggregates. The results demonstrated strong interactive effects between crop system and soil depth, with the surface layer being the most responsive to management-induced changes. The CLFI improved porosity and aggregation while reducing bulk density relative to the conventional system, particularly in the upper 10 cm. Subsurface layers exhibited more conservative behavior, with weaker structural development and limited response to management. Multivariate analyses (PCA and Canonical Discriminant Analysis) revealed clear separation among systems, with native vegetation forming a distinct structural signature characterized by higher macroporosity and aggregate stability. A Soil Physical Quality Index (SPQI) synthesized multiple indicators and confirmed the superior structural condition of CLFI when compared with monocropping system, while both the MFS1 and MFS2 exhibited the lowest physical quality across all depths. Diversified systems promoted improvements in soil physical functioning by enhancing biogenic porosity and aggregation processes. These findings highlight the importance of integrated crop–livestock–forest strategies for sustaining soil physical quality in semiarid tropical environments and demonstrate the value of multivariate approaches for detecting complex management effects.
The increasing demand for sustainable paving technologies has driven research into bio-based additives capable of reducing energy consumption and improving asphalt mixture performance. This study evaluated the chemical, empirical physical, and rheological behavior of asphalt binders modified with pequi oil (Caryocar brasiliense), a native Brazilian bio-oil, aiming to assess its potential as an additive for asphalt mixtures. Petroleum asphalt cement with a 50/70 penetration grade (PAC 50/70) was modified with 1, 2, and 3
This study evaluated the synergistic effect of ultrasound pretreatment and insoluble solids removal on the fermentation of pea protein concentrate (Pisum sativum L.) by Lactobacillus gasseri and its implications for the kinetic, fermentative, and rheological properties of the system. Four experimental treatments were investigated: protein fermented by L. gasseri (P-LG), protein pretreated by ultrasound and fermented by L. gasseri (P-US-LG), soluble protein fermented by L. gasseri (S-LG), and soluble protein pretreated by ultrasound and fermented by L. gasseri (S-US-LG). The growth kinetics, based on total cell counts determined in a Neubauer chamber, was modeled using a modified Gompertz equation for the growth phase, whereas the post-peak phase was described only descriptively with an exponential decay function. Acidification was modeled using a four-parameter logistic equation. The rheological properties were evaluated using flow and oscillatory testing, with shear-sweep data fitted to the Ostwald-de Waele model. The results indicated that the removal of insoluble solids was associated with higher µmax values and a shorter time to reach pH < 5.5, characterizing faster acidification in kinetic terms, while ultrasound modulated the microbial adaptation time in a manner dependent on the protein fraction. The non-centrifuged systems showed greater consistency and predominantly elastic viscoelastic behavior, while the soluble fractions exhibited lower viscosity and less organized structures. Radar visualization highlighted the distinct functional profiles among treatments. Taken together, the findings demonstrate that combined strategies of physical processing and lactic fermentation enable modulation of the techno functional properties of fermented plant proteins.
