Search

Multiphase flow in porous matrix with embedded free-flowing regions has wide application in industry, environment and biological systems. Due to its permo-porosity characteristics, the free-flow regions, represented by fractures and vugs embedded within the porous matrix, make multiphase flow modeling challenging. This study compares different approaches that can be used to describe two-phase flow through vugular porous media. Brinkman equation is used to describe physical phenomena considering both flow through the porous matrix and through free-flow regions. The predictions obtained with Brinkman model are compared with two different Darcy models: heterogeneous and homogeneous. In the heterogeneous Darcy model, the vugular region is characterized as a porous medium with high porosity and permeability. In the homogeneous Darcy model, the complex two-phase flow through the vugular domain is represented by an equivalent absolute permeability and relative permeability curves. The accuracy of the homogenization procedure is evaluated as a function of vug configuration. [ABSTRACT FROM AUTHOR]

This study aims to address the harmful effects of excessive nitrogen fertilizer by investigating the mobility retardance effect of zeolite on nitrate movement in loam soil columns. Disturbed and undisturbed soil columns, treated with zeolite, as well as control soil columns, were analysed over a span of three years. Breakthrough curves generated from the experiments were evaluated using the HYDRUS1D code with mobile–immobile water (MIM) and dual-permeability (DP) models. Our findings highlight that zeolite application significantly reduced nitrate mobility, with recovery rates decreasing by 8% in disturbed and 11% in undisturbed columns. The DP model, which accurately reflects real soil water flow conditions, outperformed the MIM model in predictive accuracy. This research offers a novel long-term perspective on the benefits of zeolite in enhancing soil properties and mitigating nitrate leaching, recommending the DP model for superior prediction of contaminant transport in structured soils within the vadose zone. [ABSTRACT FROM AUTHOR]

Water vapour diffusion through textile fabrics plays a crucial role in maintaining body comfort. Developing and producing comfortable textiles is a major challenge for manufacturers of fibres, yarns and fabrics. This study aims to develop a simple model to predict the water vapour permeability of textile fabrics as a function of their structural parameters to assist manufacturers in developing comfortable fabrics. To achieve this goal, geometric modeling of the woven structure was proposed to calculate porosity at the micro-and macro-pores level. Two mathematical models were introduced based on the principle of diffusion of water vapour through a textile fabric. To validate the two models, a series of 18 samples was prepared with three basic fabric structures: Plain, Twill and Turc Sateen. To vary the compactness of the structures, three weft densities were chosen: 18, 21 and 24 picks/cm. In addition, since the material influences water vapour diffusion, two types of weft yarns were inserted: 50% CO/50% PET and 100% PET. The results show that the two models are reliable for predicting water vapour resistance (Ret) depending on the structural parameters of the textile fabric. [ABSTRACT FROM AUTHOR]

During casting, two kinds of porosities are generally found, viz., macroporosity and microporosity. Macroporosity or shrinkage cavity is a major casting defect affecting the yield and quality of the product. The evolution of macroporosity during solidification is governed by complex physics. Apart from the transport of momentum, energy, and species, it is affected by the thermodynamics and kinetics of solidification. It has been an active area of research for quite some time now, despite which, our understanding of macroporosity is far from satisfactory. The possibility of the formation of many patterns of macropores from the same casting system makes the task of analysis difficult. In the present study, a combined numerical and experimental analysis of the evolution of shrinkage cavity in aluminum alloys is carried out. An Al-4.5% Cu alloy slab was solidified under laboratory conditions, and the formation of the shrinkage cavity was observed and quantified. A 3-dimensional full-scale conjugate CFD model of the experimental setup was developed and simulated using a commercial finite-volume-based solver. The model was validated by comparing it with the experimental results. Further, a reduced-order 2D CFD model was developed by applying reasonable assumptions but maintaining the model accuracy as compared to the full-scale 3D model. The 2D model developed in such a way shows a close correspondence with the actual experimental results in terms of depth and shape of shrinkage cavity. The model has a potential to predict shrinkage cavity formation in an industrial setting with low computational efforts. [ABSTRACT FROM AUTHOR]

Alveolar cellular foams are widely used in a wide range of applications, from aeronautics and filtration systems to chemical and transformation processes. Their porous characteristics make them a prime candidate for reactions, radiative transfer and flow. Geopolymeric foams, which have their origins in civil engineering, are materials with promising potential in terms of mechanical, thermal and acoustic resistance. As they are mainly used in civil engineering, the structures currently being developed are mainly closed-pore matrices. However, if they are to invert the field of photocatalytic oxidation processes, solar collectors or concentrated solar power plants, the supports need to develop a high exchange surface area. Metal alveolar foams have been identified as ideal but very costly supports. Geopolymeric foams could meet these requirements, but their surface areas are currently too limited for photoreactors. In this study, it is proposed to develop and optimize the operating conditions for geopolymer foam synthesis in order to impart macroporous properties and an interconnected alveolar structure. Based on two well-established synthesis methods (direct foaming and replication), operating conditions such as foaming agent and surfactant content, and drying and calcination conditions, are studied. Geopolymer foams are produced with different macroporous characteristics. We aim to define the synthesis conditions required to produce interconnected macroporous alveolar foams with milimetric pores. In civil engineering, these materials have the advantage of being easy to design, use and shape according to the application.

Different types of soil macropores respond differently to various tillage practices, owing to disparities in origin, scale, morphology, and function, consequently exerting distinct effects on soil structure. This study aimed to investigate the response mechanisms of three different soil pore types (total macropores, non-biopores, and biopores) to two distinct tillage practices: smash-ridging tillage (T) and no-tillage (NT) in sugarcane fields. The parameters characterizing soil pore treatments in two and three dimensions were obtained using X-ray computed tomography scanning technology. ImageJ and MATLAB software were employed to analyze the data and separate soil macropores into biopores and non-biopores categories. The results showed that non-biopores predominated in two-dimensional cross-sectional areas in NT treatment, whereas biopores were more dominant in T treatment. Biopores in T treatment had a higher proportion of two-dimensional pores compared to NT treatment. A three-dimensional analysis indicated that total macropores had larger mean diameters (MD) and macroporosity, with more continuous tubular pores in T treatment than that in NT treatment. However, NT treatment had more numerous non-biopores with broader spatial distribution and complex morphology. Additionally, biopores in T treatment had larger MD and branching length density (LD). These vertically developed biopores, along with high macropore connectivity and under smash-ridging tillage, could improve soil water and pore conductivity. Therefore, smash-ridging tillage was more beneficial for sugarcane growth compared to no-tillage in Guangxi of China. [ABSTRACT FROM AUTHOR]

Advanced oxidation processes, including photocatalysis, have been proven effective at organic dye degradation. Tailored porous materials with regulated pore size, shape, and morphology offer a sustainable solution to the water pollution problem by acting as support materials to grafted photocatalytic nanoparticles (NPs). This research investigated the influence of pore and particle sizes of photocatalytic MICROSCAFS® on the degradation of methyl orange (MO) in aqueous solution (10 mg/L). Photocatalytic MICROSCAFS® are made of binder-less supported P25 TiO2 NPs within MICROSCAFS®, which are silica–titania microspheres with a controlled size and interconnected macroporosity, synthesized by an adapted sol–gel method that involves a polymerization-induced phase separation process. Photocatalytic experiments were performed both in batch and flow reactors, with this latter one targeting a proof of concept for continuous transformation processes and real-life conditions. Photocatalytic degradation of 87% in 2 h (batch) was achieved, using a calibrated solar light simulator (1 sun) and a photocatalyst/pollutant mass ratio of 23. This study introduces a novel flow kinetic model which provides the modeling and simulation of the photocatalytic MICROSCAFS® performance. A scavenger study was performed, enabling an in-depth mechanistic understanding. Finally, the transformation products resulting from the MO photocatalytic degradation were elucidated by high-resolution mass spectrometry experiments and subjected to an in silico toxicity assessment. [ABSTRACT FROM AUTHOR]

Adsorption storage utilizing activated carbon is acknowledged as a promising approach for hydrogen storage duo to its high efficiency. This study compares the activated carbon adsorption storage method with the conventional empty tank storage approach. Finite element simulation is conducted to analyze the hydrogen charging process. Results reveal that under conditions with an initial temperature of 281 K and a storage pressure of 50 MPa, the adsorption tank exhibits a higher system volumetric capacity compared to the empty tank, with an increase of 12.6%. Furthermore, the influence of activated carbon's macroporosity and adsorption performance on storage capacity is investigated. It is indicated that increasing macroporosity effectively enhances storage capacity. Additionally, a comparison between the hydrogen storage performance of AX-21 activated carbon and carbon nanotubes (CNTs) highlights the significant impact of adsorption performance of the adsorbent materials on the storage capacity and temperature distribution. [Display omitted] • The adsorption tank has a 12.6% higher system volumetric capacity compared to the empty tank. • The maximum temperature in the adsorption tank is lower than that in the empty tank. • The hydrogen storage capacity in the adsorption tank increases with the increase in the macroporosity of activated carbon. • The hydrogen storage capacity of the AX-21 adsorption tank is 50% higher than that of the CNTs adsorption tank. [ABSTRACT FROM AUTHOR]

Soil tillage is widely acknowledged to affect soil characteristics and agricultural productivity. This research investigates the short‐term effects of various tillage methods on soil physical properties and crop yields at a Central German field site with a dry climate (mean temperature 9.5°C; annual precipitation 470 mm). Three tillage approaches were evaluated: conventional plough tillage (25 cm depth), cultivator tillage (18 cm depth), and double‐layer plough tillage (15 and 30 cm depth). We assessed soil physical properties through standard laboratory analyses, compression tests, soil pore structure via X‐ray computed tomography (X‐ray CT) and crop yields over 3 years. The results indicate that cultivator tillage approach increased soil bulk density relative to conventional tillage, especially in the second year, though this effect diminished over time. Double‐layer plough tillage emerged as a viable short‐term alternative to conventional tillage, achieving comparable soil bulk density. Saturated hydraulic conductivity values were generally higher for soils under conventional tillage or double‐layer plough tillage than for cultivator tillage, highlighting their soil loosening effect. Classical soil analysis methods combined with X‐ray computed tomography provided valuable insights into tillage induced changes to soil structure. Cultivator tillage resulted in a distinct pore structure with reduced macroporosity and pore connectivity. Despite notable soil property variations, crop yields remained consistent across the tillage methods. Overall, double‐layer plough tillage presents a sustainable option, moderately improving soil physical properties while maintaining crop yields. This study highlights the need to assess the short‐term effects of tillage on soils and contributes to the broader dialogue on optimizing tillage strategies for effective soil management and crop production. [ABSTRACT FROM AUTHOR]

Agricultural landscape management and climate seasonality can influence soil structure, hydraulic conductivity, and air permeability within the context of soil water and soil gas mobility. To investigate this, in situ and laboratory-based data were collected from three agricultural landscape positions within a watershed in eastern Ontario, Canada during a growing season. Macropore classification, water infiltration tests, and air permeability measurements were conducted in situ and standard soil characterizations were carried out on soil samples. Hydraulic conductivity of the soil matrix, based on grain size data, indicated that the highest values were consistently measured in the B horizon at each landscape setting. Macropores were found to be more abundant within uncultivated drainage ditch bank soils, compared to the adjacent cropped fields. Macropores in the ditch bank soils were exclusively consisted of circular biopores, while both circular and linear macropores were observed in the cultivated field soils. Air permeability, vertical hydraulic conductivity, and horizontal hydraulic conductivity were also greater in the uncultivated soils, relative to the cultivated soils. Field saturated hydraulic conductivity measurements offered evidence of anisotropy, likely due to the vertical nature of the macropore features. Macropore disposition and extent varied over the growing season, especially in the cultivated field soils where tillage and field trafficking are physically disruptive. Seasonality of macropore development will influence temporal changes in advection-based mass exchange of gas and water in the vadose zone. Modeling of mass exchange in agricultural soils should consider time variability in macroporosity to more realistically characterize infiltration and soil gas emissions. [ABSTRACT FROM AUTHOR]

Abstract The terracing is important for erosion processes control in agricultural areas. However, agricultural terraces are being removed from the production areas under no-tillage systems. There are still uncertainties about the terracing effects on the soil saturated hydraulic conductivity (Ks) and macroporosity (Macro), which represent the functionality of the system. We aimed to evaluate the magnitude and spatial distribution of Ks and Macro and the correlation between these soil properties in two paired megaplots, of 1.923 ha, one with terraces (T) and another without terraces (WT). Ks and Macro were determined at 0.00-0.10 m, 0.10-0.20 m, 0.20-0.30 m, and 0.30-0.40 m soil layers and submitted to descriptive statistical, geostatistics, and Spearman correlation analysis. Ks was highest in the 0.00-0.20 m and lowest in the 0.20-0.40 m layers in T. In WT, Ks was highest in the 0.00-0.10 m and lowest in the 0.10-0.40 m layers. However, the Macro was highest in the 0.00-0.10 m and lowest in the 0.10-0.40 m layers in both megaplots. Ks and Macro had a positive correlation in both megaplots. The spatial distribution of Ks and Macro had a positive correlation, with regions with higher Ks coinciding with regions with higher Macro in both megaplots. The spatial distribution of Ks and Macro in WT did not have a clear trend, while in T there was a slight stratification in strips interspersed with higher and lower Ks and Macro. These initial trends are not conclusive considering the short term between terraces removal and Ks and Macro evaluation.

In the Brazilian Amazon, logging is primarily restricted to the driest months of the year by law. Even so, the dry season in the humid tropics is susceptible to considerable rain events, with rain occurring monthly. Therefore, an experiment was established in unentered Central Amazonian old-growth forest to compare skid trail use in the wet season, when logging operations are not permitted, as well as in the dry season. This was done to investigate the differences in soil compaction for the season closed to logging versus the season open to logging. A randomized complete block design (RCBD) was utilized with three blocks composed of seven sub-blocks each, which contained a control, 1, 3 and 12 tractor cycles in both the wet and dry seasons. A Caterpillar track-type tractor model D6D was used for experimental skid trail establishment. Regardless of season the initial machine cycle caused the greatest increase in soil bulk density (BD) and penetration resistance (PR), as well as the greatest decrease in macroporosity. In fact, the initial dry season cycle caused more severe compaction than the wet season. Nevertheless, after 3 cycles, increases to BD and PR were similar for both seasons, with the end result after 12 cycles nearly identical. To the contrary, macroporosity was substantially reduced in the dry season versus the wet season. Overall, the site impacts were similar in both seasons. Thus, skidding operations could be permissible during the wet season with similar impacts caused in the dry season. [ABSTRACT FROM AUTHOR]

Alternatives to improve some physical-chemical properties of soils affected by high levels of Na+. To evaluate the effect of gypsum in a soil with a high Na+ content of natural origin, two experiments were installed on a pasture of Festuca arundinacea: in Experiment 1, four rates were evaluated (0, 1, 2 and 3 Mg ha-1) from two commercial sources of agricultural gypsum and in Experiment 2, three commercial sources of gypsum and one source of sulfur (S). In Experiment 1, after 420 days of applying the treatments, exchangeable Na decreased by 22% while exchangeable Ca increased by 10% in plots with gypsum in the first 20 cm of the profile. In addition, in these plots the soil presented greater penetrability and humidity and the pasture yielded 50% more dry matter than the plots without gypsum. While in Experiment 2, the pasture presented greater absorption of S in the soil with amendments (gypsum or S), compared to the control plots, but no differences were observed among the amendments. It is concluded that agricultural gypsum was effective in reducing exchangeable Na in the soil depth studied, increasing yield and improving pasture quality. [ABSTRACT FROM AUTHOR]

The behavior of primarily isolated human stromal cells including dermal fibroblasts and mesenchymal stem/stromal cells (MSCs) upon interaction with ceramic materials based on tricalcium phosphate (TCP) with different pore sizes is studied. The effect of the emulsifier on the rheological characteristics of photosensitive emulsions based on calcium phosphate is investigated. The dependence of the conditions of preparation of photosensitive emulsions on the pore size in ceramic materials based on Ca3(PO4)2 is demonstrated. Studies of the biocompatibility of macroporous bioceramics upon cultivation of human stromal cells and effect of the samples of the material with different pore sizes on the in vitro transcriptional activity of MSCs are carried out. [ABSTRACT FROM AUTHOR]

This paper reports the mechanical properties of graded macroporous β-Ca3(PO4)2-based ceramic materials produced by stereolithographic 3D printing. We demonstrate the feasibility of using photocurable emulsions for the preparation of ceramic materials with porosity above 80% and controlling the pore size distribution. Graded-porosity ceramic materials with tailored pore size are produced using 3D printing of photocurable tricalcium phosphate-based emulsions. We examine the effect of emulsifier content on the average pore size in ceramic scaffolds with tailored architecture and the effects of porosity, average pore size, and 3D architecture on the strength characteristics of the macroporous ceramic materials. [ABSTRACT FROM AUTHOR]

Multicomponent oxide microspheres with interconnected macroporosity (MICROSCAFS®) are new materials with great potential as support materials for photocatalysis, optimized for real life applications and for other uses that are still being explored. They are obtained from an adapted sol–gel process combined with phase separation phenomena that occur within the water droplets of an emulsion. We present here a methodology based on cryogenic scanning electron microscopy (cryo-SEM) that allows, with minimal specimen preparation, the direct and in situ visualization of 'wet' alkoxide-derived microstructures, for the mechanistic study of the complex process of MICROSCAFS® generation. It is simultaneously combined with energy dispersive X-ray spectroscopy (EDS) to visualize phase separation phenomena and study the chemical elemental composition at specific regions of the sample and reaction times. [ABSTRACT FROM AUTHOR]

The main goal of this study was to examine the possibility for obtaining macroporous scaffolds with defined properties based on calcium phosphate doped with magnesium, copper and zinc ions, coated with gelatin, which would potentially provide controlled conditions for the formation of new bone tissue after implantation. As a first, multi-doped nanoparticles of hydroxyapatite (HAp), which represents the main component of the inorganic part of bone tissue, was synthesized by autoclaving the precursor solution obtained at a Ca/P molar ratio of 1.52. Calcium in the initial solution was partially replaced by ions of magnesium (5 mol.%), copper (0.4 mol.%) and zinc (0.4 mol.%). Obtained powder was further calcinated, the changes in the morphology of the powders during calcination at 1000 ̊ C were reflected in the transition of spherically agglomerated needle-like nanoparticles of the multi-doped hydroxy-apatite powder to a spherical grained morphology. Macroporous bioceramic structures were obtained using the sponge replica method, green macroporous samples made of calcinated multi-doped powder, polyvinyl alcohol and water were sintered at 1.370°Ϲ and 1.430°Ϲ. X-ray diffraction analysis deter-mined that the presence of magnesium in the structure of hydroxyapatite favors the phase transformation of HAp into b-tricalcium-phosphate (b-TCP), which contributed to the formation of the biphasic HAp/b-TCP system during the calcination of the powders, but also during the sintering of macroporous beads. Examination of the antimicrobial activity of the obtained macroporous supports against E. coli showed a more effective degree of inhibition compared to S. aureus. A significant increase in the compressive strength of sintered macroporous scaffolds was obtained after the formation of coating based on 7.5% gelatin solution.

Iron mining tailings raise several concerns regarding their deposition and the decommissioning of storage dams, particularly regarding the limitations of this substrate for plant establishment, including poor substrate aggregation and limited availability of nutrients. The objective of this study was to evaluate the effect of the interaction of pelleting and fertilization on the physical and chemical conditioning of the root environment for the growth and development of plants in technosol formed by the deposition of iron mining tailings. Three experimental trials were carried out using indicator plants (Urochloa brizantha Hochst. ex A. Rich., Eucalyptus grandis W. Hill ex Maiden, and Phaseolus vulgaris L.), in a randomized block design, and the treatments distributed in a factorial arrangement (5 × 2): five levels of technosol pelleting (0, 25, 50, 75, and 100% m/m), with and without fertilization, with five replications. Fertilization promoted the growth of all plants and demonstrated that the supply of nutrients is fundamental for plant growth in this technosol, mainly by promoting root development, which in turn favored substrate porosity. Pelleting mainly increased the technosol macroporosity in all tests. However, it was only effective in providing better growth conditions and enhancing the supply of nutrients for Eucalyptus grandis. While pelleting improves the physical conditions of the root environment, the availability of nutrients was found to be the main limiting factor for plant growth in the technosol formed by iron mining tailings. With adequate fertilization, the plants had less difficulty developing in this substrate under vase conditions. [ABSTRACT FROM AUTHOR]

Functional refractory remains critical due to its intrinsic properties such as: saving space, lightweight and excellent thermal stability to achieve the trade-off between insulating and overall performances. The present study deals with the production of low carbon footprint and lightweight refractory matrices, with controllable pores structures, thermally stable and having low thermal conductivities. The lightweight refractory products were obtained through the direct foaming of geopolymer pastes and sintered from 900 to 1200 °C. The mechanism of pores formation, pores structures and the effect of both sintering temperature and foaming agent ratio on the thermal insulation, physical and microstructural characteristics were evaluated. The results showed that the produced matrices could be described as low thermal conductors, with thermal conductivity values between 0.49 and 0.18 W/mK. The 3D internal pore structures under laser microscopy observations confirms the mechanism of pore enlargement when high concentration of the foaming agent was added. Furthermore, the decomposition of kyanite particles within the matrices, at high temperature, favoured the extend reduction in porosity and the limitation of the liquid phase, by ensuring the formation of macro-porosities sized between 360 μm and 2 mm. The formation of the refractory crystalline phases namely: cordierite, mullite, enstatite, leucite, as well as, kalsilite, acting as filler, ensure thermal stability of the matrices. The produced materials provide an energy-saving, lightweight ceramic foams with high-strength and low thermal conductivities, potential candidates for refractory applications. [ABSTRACT FROM AUTHOR]

Due to the harsh flight environment of hypersonic platforms, Ultra-High Temperature Ceramics (UHTCs) imbued with macroscale porosity have been introduced as candidates for providing thermal insulation of sensitive on-board components. This study employs an oxidized state approach for modeling the coupled effects of surface oxidation and continuum damage in the effective thermomechanical response of such materials within the framework of computational micromechanics. Using an in-house Material Point Method (MPM) computational tool, two-dimensional plane strain simulations were performed on representative hexagonal structures of TiB2 with 10%, 40% and 70% macroporosity. Oxide layers ranging from 5 to 50 μm were applied to the structures in place of a transient, diffusion-based oxidation solver. Simulations with applied compressive strains of up to 30% were then performed on hexagonal structures with and without the oxide layer present. A range of dynamic thermal gradients were also applied to investigate the damage due to thermal expansion coefficient mismatch. Finally, the oxidized state modeling approach was applied to large porous structures derived from micro computed tomography images of TiB2 foam.

The influence of a disperse medium (paraffin oil) on the pore size distribution in Ca3(PO4)2-based ceramic materials designed for bioresorbable implants is studied. The pore size is found to affect the mechanical properties of such materials. The use of photocurable emulsions for the preparation of ceramic materials with a porosity higher than 50% is shown to be promising. The possibility of controlling the pore size distribution is demonstrated. The pore size decreases from 275 to 100 μm as the emulsifier content in the emulsion increases from 0.035 to 0.25 wt %. The uniaxial ultimate compressive strength of the ceramics with a relative density of 52% and an average pore size of 250 μm is 2.87 MPa. [ABSTRACT FROM AUTHOR]

Local drug delivery systems are an effective approach in the treatment of purulent–septic inflammation of bone tissue. Chemically bonded multiphase ceramics based on calcium-deficient carbonate-substituted hydroxyapatite combine resorbability, osteoconductivity, and the possibility of volumetric incorporation of antibiotics. Macroporosity is regulated by the concentration of polyethylene glycol granules introduced into the initial powder composition, followed by their extraction. The selected conditions for the consolidation of the ceramic matrix and the extraction of PEG granules retain the activity of vancomycin, which is confirmed by the results of microbiological studies. The concentration of vancomycin and the porosity affect the local concentration and release of the antibiotic. The incorporation method provides a prolonged release of the antibiotic for up to 31 days. In vivo experiments with bone implantation have shown that chemically bound macroporous ceramics with incorporated vancomycin are a therapeutically effective carrier of the substance during the healing of bone defects in conditions of surrounding purulent–septic inflammation, and can be considered as a carrier for local antibacterial therapy, at the site of implantation.

Sugarcane areas show a reduction in soil physical quality. However, few studies demonstrate the effect of sugarcane straw maintenance on soil physical quality along the crop cycle. This study aimed to evaluate and compare the soil physical quality in areas cultivated with sugarcane where straw was kept on soil, after the first and fourth harvests, with that of an area under native forest. Two areas cultivated with sugarcane, representative of the beginning and end of the production cycle, were evaluated in a clayey Oxisol. One area was evaluated after the first mechanical harvest (C1), while the other was evaluated after the fourth harvest (C4). These areas were compared to an area of native forest (NF). The data were subjected to multivariate principal component analysis. Agricultural areas cultivated with sugarcane showed reduction in soil physical quality compared to NF, presenting higher soil penetration resistance (SPR), soil bulk density (Sd) and microporosity (Mic). Sd was 13.7% higher in the C1 area, while in the C4 area such increase was only 5.1% compared to NF. The negative impact of sugarcane cultivation on soil physical quality is reduced after four harvests in areas with mechanical harvesting and where straw was kept on the soil, especially in the 0.00–0.20 m layer. [ABSTRACT FROM AUTHOR]

This paper investigates the metallurgical factors that contributed to the failure of several cast U-clamps made of HK40 steel U-clamps during the installation of a pre-startup heater in a petrochemical plant. The presence of extensive macro/micro-shrinkage porosity is identified as the root cause of the failure. The severe shrinkage-related porosity in the material, confirmed by metallographic examination and non-destructive X-ray radiography testing and evidenced by a severe loss in tensile ductility, resulted in a unique fully dendritic fracture surface characteristic. It was found that the loss of structural integrity associated with macro-shrinkage voids and loss of toughness associated with microporosity led to premature failure of U-clamps when subjected to bending forces during installation. The casting process should be designed to guarantee a higher Niyama criterion value, defined as the local thermal gradient divided by the square root of the local cooling rate, in the casting to produce a sound U-clamp. [ABSTRACT FROM AUTHOR]

In Canterbury, New Zealand, there has been a widespread conversion of dryland sheep grazing to more intensive irrigated dairying. We determined the effects of these land uses on soil physical properties, and water release characteristics, on adjacent sites: a centre-pivot sprinkler-irrigated dairy farm site, a dryland sheep site, and a non-grazed, non-irrigated control site. Despite the Pallic Soil being well drained, greater soil compaction occurred at the dairy site than at other sites, to at least 30 cm depth. The dairy site typically had significantly lower total porosity and macroporosity, and greater bulk density and volumetric water content, than the other sites. Available water capacity varied but was greater at the dairy site (0–30 cm) than at the sheep site and control site. Further research is required across more farms and soils to confirm these results in other conditions. [ABSTRACT FROM AUTHOR]

Based on carbonate-substituted hydroxyapatite (HAP) containing vancomycin, a method is developed for the preparation of macroporous matrices that combine bioresorbability, osteoconductivity, and the possibility for the volumetric impregnation of antibiotics without loss of their activity and their prolonged release. The technology includes treatment with supercritical CO2 as the final stage in the preparation of a matrix, which makes it possible to completely remove the organic solvent that serves as an extractant for the pore formation additive, i.e., polyethylene glycol (PEG) granules, and to increase the biocompatibility of the matrix, as confirmed by the results of histological tests during subcutaneous implantation. The activity of vancomycin after its volumetric incorporation into the calcium phosphate matrix is demonstrated in the regions of inhibiting the growth of bacterial cultures. As proven in in vivo experiments on the implantation of bones, the matrix is a therapeutically effective carrier of antibacterial substances in the treatment of septic purulent inflammations of bone tissues. [ABSTRACT FROM AUTHOR]

The material used is recycled aluminum alloy. The ship’s propeller is cast through a steel mold. The macroporosity, misrun, and cold shut defects formed in the cast products of the ship’s propellers were observed for their location, geometric shape, and size. Defects are generally formed at the tip of the blade with various geometries and sizes, and shrinkage cavity defects are observed at the butt of the blade. No defects were found in the product when die mold was preheated.

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The possibility of obtaining highly porous hydrogel composite materials for biomedical applications based on tricalcium phosphate in a polyethylene glycol diacrylate matrix, aimed at repairing bone defects, has been studied. The effect of different content of inorganic filler particles exerted on the mechanical characteristics of highly porous hydrogel composites β-Ca3(PO4)2/polyethylene glycol diacrylate has been studied. It is demonstrated that the preparation of highly porous composite materials with specified elastic properties is quite possible. The viscoelastic properties of the obtained materials are shown to depend on the preset pore size. Varying the tricalcium phosphate fraction in the highly porous hydrogel material makes it possible to control the relative stiffness of the composite. [ABSTRACT FROM AUTHOR]

Local drug delivery systems are an effective approach in the treatment of purulent–septic inflammation of bone tissue. Chemically bonded multiphase ceramics based on calcium-deficient carbonate-substituted hydroxyapatite combine resorbability, osteoconductivity, and the possibility of volumetric incorporation of antibiotics. Macroporosity is regulated by the concentration of polyethylene glycol granules introduced into the initial powder composition, followed by their extraction. The selected conditions for the consolidation of the ceramic matrix and the extraction of PEG granules retain the activity of vancomycin, which is confirmed by the results of microbiological studies. The concentration of vancomycin and the porosity affect the local concentration and release of the antibiotic. The incorporation method provides a prolonged release of the antibiotic for up to 31 days. In vivo experiments with bone implantation have shown that chemically bound macroporous ceramics with incorporated vancomycin are a therapeutically effective carrier of the substance during the healing of bone defects in conditions of surrounding purulent–septic inflammation, and can be considered as a carrier for local antibacterial therapy, at the site of implantation. [ABSTRACT FROM AUTHOR]

Increasing pasture biomass production through nitrogen fertilization enables greater stocking rate and grazing intensification in pastoral livestock production systems. However, grazing intensification can compromise the soil physical quality if stocking rates exceed the soil bearing capacity to support treading. The objective was to quantify the impact of long-term (12 years) intensified grazing of Panicum maximum Jacq. cv. IPR-86 Milênio on the physical quality of a sandy soil (Luvisol Ferric soil) under subtropical climate. The 12-year field experiment was arranged in a completely randomized split-plot design with four replicates. The approach for moving the animals in and out of the paddocks varied across harvests. In the first five harvests, the period of use and rest was fixed with each paddock being occupied for 5 days followed by 35 days of rest (i.e., 40-day grazing cycle). In the subsequent harvests, the timing for moving animals in and out of each paddock was based on pasture height, with entry set at 0.90 m and exit at 0.40 m. Grazing intensification levels (IL) consisted of different animal stocking rates, grazing cycles, and forage biomass, which varied depending on the nitrogen application doses: 0 (IL-0), 150 (IL-150), 300 (IL-300), and 450 (IL-450) kg of N ha−1 year−1. Undisturbed soil samples were taken at four depths (0–0.10, 0.10–0.20, 0.20–0.30, and 0.30–0.40 m) in two sampling positions (under plants vs. between plants) and used to measure several soil physical properties (e.g., bulk density, macroporosity, mesoporosity, microporosity, water and air storage capacity, available water, pore size distribution, and water retention curve). The impact of grazing intensification on soil physical quality was minor, occurring only between plants and at the 0–0.10 m depth, where an increase in soil bulk density and a decrease in microporosity was observed. Grazing intensification also increased the water retention capacity between plants. Regardless of the sampling position and the grazing IL, water and air storage capacity was not detrimental to plant development. Overall, the increased animal stocking rate resulting from the greater pasture biomass production due to improved nitrogen fertilization does not degrade soil physical quality. [Display omitted] • Soil physical properties were measured under different grazing intensities. • Grazing intensification impact was minimal and limited to the topsoil. • Plant available water was not compromised by intensification of grazing. • Increased forage production enabled intensified grazing without soil degradation. [ABSTRACT FROM AUTHOR]

The ongoing climate warming is likely to increase the frequency of freeze-thaw cycles (FTCs) in cold-temperate peatland regions. Despite the importance of soil hydro-physical properties in water and carbon cycling in peatlands, the impacts of FTCs on peat properties as well as carbon sequestration and release remain poorly understood. In this study, we collected undisturbed topsoil samples from two drained lowland fen peatlands to investigate the impact of FTCs on hydro-physical properties as well as dissolved organic carbon (DOC) fluxes from peat. The soil samples were subject to five freeze-thaw treatments, including a zero, one, three, five, ten cycles (FTC0, FTC1, FTC3, FTC5, and FTC10, respectively). Each FTC was composed of 24 h of freezing (−5°C) and 24 h of thawing (5°C) and the soil moisture content during the freeze-thaw experiment was adjusted to field capacity. The results showed that the FTCs substantially altered the saturated hydraulic conductivity (Ks) of peat. For peat samples with low initial Ks values (e.g., < 0.2 × 10−5 m s−1), Ks increased after FTCs. In contrast, the Ks of peat decreased after freeze-thaw, if the initial Ks was comparably high (e.g., > 0.8 × 10−5 m s−1). Overall, the average Ks values of peatlands decreased after FTCs. The reduction in Ks values can be explained by the changes in macroporosity. The DOC experiment results revealed that the FTCs could increase DOC concentrations in leachate, but the DOC fluxes decreased mainly because of a reduction in water flow rate as well as Ks. In conclusion, soil hydraulic properties of peat (e.g., Ks) are affected by freezing and thawing. The dynamics of soil hydraulic properties need to be explicitly addressed in the quantification and modelling of the water flux and DOC release from peatlands.

Al-Fe-Cu base metallic foams were produced without the need of blowing agents or space holders (“In-Situ” route). The porosity formation mechanism and the effect of the icosahedral phase in the Al80Cu17Fe3 and Al58Cu27Fe15 alloy compositions are presented and discussed. These alloys were melted in an induction furnace under an argon atmosphere. Subsequently, the alloys were slowly solidified inside the furnace crucible, i.e., 0.12 °C/s. Several heat treatments were carried out to obtain the highest percentage of porosity and thus to find out the mechanism associated with the porosity formation. To obtain the heat treatment temperatures, a DTA study was performed. The crystallographic phases were identified by means of X-ray diffraction and scanning electron microscopy. The selected temperatures for the heat treatments were 705 °C and 850 °C for the Al79Cu15Fe6 and Al62Cu28Fe10 alloys, respectively. The XRD showed that the Al79Cu15Fe6 alloy was mainly constituted by Al, ω-Al7Cu2Fe, and θ-Al2Cu phases, generating a porosity of 0.54%. The highest percentage of porosity (60%) was obtained for the Al62Cu28Fe10 alloy, heat-treated at 850 °C for 3 h. SEM images showed that the microstructure was mainly constituted of ι-Al6Cu2Fe and β-AlFe phases. Inside the pores, the ι-Al6Cu2Fe phase was also found as clusters of fivefold symmetry quasicrystals. According to the microstructural analysis, it was found that the porosity formation mechanism could be related to a reaction that involves the interaction between the Liquid, λ-Al13Fe4, and ω-Al7Cu2Fe phases resulting in the formation of ι-Al6Cu2Fe phase (ternary peritectic reaction) and a highly porous structure. [ABSTRACT FROM AUTHOR]

Capacity-based indicators of soil physical quality (SPQ) and pore distribution parameters were proposed to assess the effects of compost amendment but their determination was limited to desorption water retention experiments. This study also considered the pore size distribution obtained from adsorption experiments to establish the effectiveness of compost amendment in modifying the physical and hydrological attributes of a sandy loam soil. Repacked soil samples with different compost to soil ratios, r, were subjected to a wetting–drying cycle, and the water retention data were fit to the van Genuchten model to obtain the pore volume distribution functions. The soil bulk density was minimally affected by the wetting–drying cycle but a significant negative correlation with r was obtained. The sorption process involved larger and more heterogeneous pores than the desorption one thus resulting in an estimation of the air capacity SPQ indicators (Pmac and AC) that were higher for the wetting–water retention curve (WWRC) than the drying one (DWRC). The opposite result was found for the water storage SPQ indicators (PAWC and RFC). In general, SPQ indicators and pore distribution parameters were generally outside the optimal range but estimates from the DWRC were closer to the reference values. The water entry potential increased and the air entry potential decreased with an increase in the compost rate. Significant correlations were found between the SPQ indicators estimated from the DWRC and r but the same result was not obtained for the WWRC. It was concluded that compost addition could trigger positive effects on soil hydrological processes and agronomic service as both water infiltration during wetting and water storage during drying are favored. However, the effectiveness of the sorption process for evaluating the physical quality of soils needs further investigation. [ABSTRACT FROM AUTHOR]

The paper describes the impact and importance of preprocessing methods of fabric image for detection of inter-thread pores (ITP), which is a new method of individual ITP identification. The aim of this experiment is to identify precisely every individual ITP of fabric structure by using optimal preprocessing algorithm for further quantitative, morphometric structural analysis of specialized fabrics (barriers, industrial filters, composites, others) in context of air permeability, flow resistance, UV radiation, viruses penetration, thermal comfort by estimation fabric porosity, especially macroporosity parameters and cover factor. The correct identification of individual ITP depends on the acquisition method and the preprocessing algorithm. It was conducted by analyzing the adaptation of digital image preprocessing methods for two structures of plain weave fabric in two magnification zooms, 1.25 and 0.8. Preprocessing operations were performed in the area of spatial operations of the image. The optimal preprocessing algorithm includes low-pass filtering, histogram equalization, nonlinear filtering, thresholding, and morphological operation. This algorithm was selected based on the factors developed by the author (ITP detection, RID factor—a difference between the real and model ITP areas) which rely on the ITP size, shape, and location. The graphic view of the ITP contour position on the fabric image is a verification element in the optimal preprocessing algorithm. The presented results of the air permeability of two different plain weave structures confirm the need to optimize the algorithm of pre-image processing methods to precisely detect each individual ITP in the fabric image.

Soil tillage is a high-cost operation in the replanting of sugarcane fields. Thus, measures to reduce this cost are desirable, provided that they promote good physical conditions for sugarcane development. The objective of this study was to evaluate the effect of chiseling in total area and in the planting row on the physical attributes of Oxisol and Ultisol after soil tillage and after sugarcane planting. The experimental design was in large and uniform plots, with two treatments and ten replicates. The Oxisol and Ultisol had clay contents of 590 and 168 g kg−1 in the 0.00–0.40 cm layer. Treatments consisted of soil tillage with chiseling in the planting row and with chiseling in total area. After soil chiseling and after planting, undisturbed soil samples were collected in each experimental plot, in three layers (0.00–0.10; 0.10–0.20 and 0.20–0.40 m) and at two sampling sites (row and interrow). In both soils, chiseling in total area was efficient to reduce soil density and increase macroporosity in sugarcane interrows, compared to chiseling in the row. The values of the physical attributes of the soils evaluated, in rows and interrows, were similar in the areas with chiseling in total area and row chiseling after sugarcane planting. Changes in Oxisol and Ultisol structure due to chiseling did not persist after sugarcane planting. The soil under row chiseling system has physical quality similar to that of the soil under total area chiseling system, regardless of texture. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Soil compaction can decrease potential crop yield and is frequently found in no-till cultivation systems, but there is little information on the critical limits of soil physical properties in these conditions, especially in subtropical soils. The objectives of this study were to evaluate the influence of tractor traffic on soil physical properties and identifies critical limits of soil bulk density, soil compaction degree, macro, and microporosity on crop yield of corn and black oat assessed in situ in a Xanthic Hapludox in Southern Brazil. Tractor machine traffic (0, 2, 5 and 20 passes) was established in no-till soil to create different soil compaction levels. Undisturbed soil samples were collected at depths of 0.00-0.05, 0.07-0.12 and 0.17-0.22 m just after tractor traffic in two moments: before corn cultivation, and then before black oat cultivation. Under the conditions of this experiment, the 10% higher yields of corn and black oats were obtained with macroporosity above 0.10 m3 m-3 and 0.13 m3 m-3, respectively. Similarly, the soil compactness degrees of 90% and 86% were considered critical for the corn and black oat, respectively. In addition, soil compaction by machine traffic reduced maize yield up to 33% and black oat biomass yield up to 44%. Our results demonstrate that growers should be aware of the consequences of machine traffic on soil properties, as it can severely compromise crop yields, especially of corn and black oats cultivated in very clayey soil like the one evaluated in this study.

The effect of the pore size of macroporous ceramic materials based on β-Ca3(PO4)2 on their biological activity was studied. The formation conditions of macroporous ceramics with a porosity of >50% and a specified pore size were determined. The effect of components of the light-curing emulsion on the pore size in the final macroporous ceramics was studied. The biocompatibility of β-Ca3(PO4)2-based macroporous ceramics was demonstrated in in vitro biomedical assays. The effect of pore size of macroporous ceramic materials on mesenchymal stromal cell proliferation and viability was established. [ABSTRACT FROM AUTHOR]

[Display omitted] • Macroporous Ni/Al 2 O 3 catalysts are employed for dry reforming of methane (DRM). • Geometrical effect of the macroporous Al 2 O 3 structure promotes NiAl 2 O 4 formation. • Ni exsolution from NiAl 2 O 4 in H 2 reduction results in highly dispersed Ni nanocluster. • The macroporous Ni/Al 2 O 3 catalysts significantly enhance their catalytic performance in DRM. • Coke formation is strongly inhibited over macroporous Ni/Al 2 O 3 catalysts in DRM. This study aimed to investigate the geometrical effect of macroporosity on the performance of Ni-based catalysts in the dry reforming of methane (DRM). For this, macroporous Ni/Al 2 O 3 catalysts with different Ni contents were synthesized. Characterization experiments on the macroporous Ni/Al 2 O 3 catalysts revealed that the macroporous Al 2 O 3 structure enhanced NiAl 2 O 4 formation by facilitating efficient interactions between the Ni species and accessible Al 2 O 3 sites on the macroporous wall surface during calcination. In a subsequent reduction step, Ni exsolution from the NiAl 2 O 4 structure generated highly dispersed Ni nanoclusters over the macroporous Al 2 O 3. Conversely, non-macroporous Ni/Al 2 O 3 catalysts presented substantial amounts of large isolated Ni nanoparticles at an Ni content of 20 wt%, owing to limited NiAl 2 O 4 formation caused by the lack of accessible Al 2 O 3 sites. The highly dispersed Ni nanoclusters surrounded by oxygen vacancies on the macroporous Ni/Al 2 O 3 catalysts significantly enhanced their catalytic performance in the DRM, evidenced by their high CO 2 and CH 4 conversions and strong resistance to coking. Moreover, the superior coke resistance ability of the macroporous Ni/Al 2 O 3 catalysts was attributed to the gasification of the coke precursor on Ni nanoclusters surrounded by oxygen vacancies during the DRM. [ABSTRACT FROM AUTHOR]

Macroporous silica ceramic was obtained using clay and diatomite. Boric acid as a low-cost additive in the amount of 1 wt% was used. These porous materials were obtained at low forming pressure (40-80 MPa) and lower sintering temperature (850-1300 ºC) for 4h in air. The influence of boric acid, forming pressure, and sintering temperature on the microstructure, porosity parameters, and mechanical properties of obtained porous monoliths were investigated. As-received and the modified samples were characterized by X-ray diffraction, FTIR, SEM, and mercury porosimetry measurements. As for modified clay and diatomite, they were pressed at 60 MPa and then sintered at 1150 ºC, obtaining porosities of about 10 % and 60 %, respectively. Both of the analyzed samples had the pore diameter in the range of macroporous materials. The pore diameters of clay samples are ranging from 0.1-10 μm, whereas the pore diameter of diatomite samples was slightly lower with values ranging from 0.05-5 μm. Modified diatomite samples have a lower Young modulus in comparison to modified clay samples.

The problem of producing biodegradable implants based on calcium phosphate porous ceramics is being solved. Highly porous ceramics with a uniform distribution of pores of a specified size is fabricated by slip casting from a suspension containing tricalcium phosphate Ca3(PO4)2 and polymeric granules 50–100 μm in size in amounts of 20 and 50 vol %, respectively, followed by heat treatment. For the chosen sintering parameters, the porosity of the ceramics is not lower than 40% and its tensile strength and biocompatibility satisfy the corrsponding requirements. [ABSTRACT FROM AUTHOR]

This study presents a new route for the synthesis of carbon gels with a structure that includes aligned fibers of the same material. A modification of the heating process during polymerization of resorcinol and formaldehyde produces a combination of the classical polymeric nodules in carbon gels with arrays of totally aligned fibers. This new morphology, produced through a very simple process, opens up new application possibilities to the already numerous existing ones for carbon gels. Highlights: Combination of polymeric nodules and aligned fibers are produced by one-pot sol-gel process. Formation of fiber arrays is favoured at late polymerization point under acid catalysis. The fiber arrays lead to materials with very good combination of porosity and surface area. [ABSTRACT FROM AUTHOR]

Cover crops promote nutrient cycling, and lime and gypsum can alter the soil physical attributes. This study aimed to evaluate the effect of lime and gypsum rates applied to a no-tillage system with addition of residues of three cover crops on the soil physical attributes. This experiment was carried out in chapadão do sul-ms. The treatments were comprised of three cover crops (Urochloa ruziziensis, fallow, and Pennisetum glaucum), with gypsum (0, 2.3 and 4.6 Mg ha-1) and lime applied at a dose of 0, 2, 4, 6 Mg ha-1).The attributes evaluated were: soil density, macroporosity, microporosity, total porosity and penetration resistance. The soil of the experiment was classified an Oxisol. Cover crops and lime and gypsum improved macroporosity, microporosity and total porosity at all depths, 0-0.2 m. Millet presented lower values for penetration resistance with the lime application and without gypsum application. No residual effect on soil density was detected for lime and gypsum application or cover crops in the 0.1-0.2 m layer. Brazilian Cerrado producers will have a well-defined management system to follow aiming at improving the soil physical attributes.

We have developed a method for the preparation of macroporous carbonate hydroxyapatite-based matrices with the use of the technology of self-setting cements for surgical osteology. Macroporosity of osteoconductive calcium phosphate matrices was produced by adding paraffin granules to a dry cement mixture, followed by organic solvent extraction of the granules from matrices hydrated in an aqueous solution. In vivo tests of the resultant materials demonstrated high biocompatibility with pronounced angiogenesis, which was achieved via additional treatment with supercritical carbon dioxide. [ABSTRACT FROM AUTHOR]

Synthetic calcium phosphate (CaP) ceramics represent the most widely used biomaterials for bone regenerative treatments due to their biological performance that is characterized by bioactivity and osteoconductive properties. From a clinical perspective, injectable CaP cements (CPCs) are highly appealing, as CPCs can be applied using minimally invasive surgery and can be molded to optimally fill irregular bone defects. Such CPCs are prepared from a powder and a liquid component, which upon mixing form a paste that can be injected into a bone defect and hardens in situ within an appropriate clinical time window. However, a major drawback of CPCs is their poor degradability. Ideally, CPCs should degrade at a suitable pace to allow for concomitant new bone to form. To overcome this shortcoming, control over CPC degradation has been explored using multiple approaches that introduce macroporosity within CPCs. This strategy enables faster degradation of CPC by increasing the surface area available to interact with the biological surroundings, leading to accelerated new bone formation. For a comprehensive overview of the path to degradable CPCs, this review presents the experimental procedures followed for their development with specific emphasis on (bio)material properties and biological performance in pre-clinical bone defect models. Image, graphical abstract [ABSTRACT FROM AUTHOR]