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Fungal Influence on Hydrophobic Organic Pollutants Dynamics within the Soil Matrices
Published in Vivek Kumar, Rhizomicrobiome Dynamics in Bioremediation, 2021
Claire Baranger, Isabelle Pezron, Anne Le Goff, Antoine Fayeulle
Soil structure is determined by the aggregation of its components, including minerals (clays and other silicates, calcium carbonate, metallic oxides) and organic matter. The relative content in particles of various size ranges defines soil texture, regardless of their chemical nature. Fungi greatly contribute to shaping the soil matrix by simultaneously promoting aggregate formation, and altering minerals and organic matter (Gadd et al. 2012, Ritz and Young 2004). In combination with organic matter content, porosity is one of the main parameters affecting the retention of contaminants. Indeed, small pores and high total pore volume mean a high surface available for adsorption, and inaccessibility to degrading organisms and solutions (Ren et al. 2018, Yu et al. 2018). HOC are known to have a greater affinity for fine particles, and tend to sorb onto clay minerals, which exhibit hydrophobic surfaces in a layered structure (Jaynes and Boyd 1991, Yu et al. 2018). As a result, pollutant retention is usually higher in soils with a finer texture (Amellal et al. 2001).
Drilling and Rock Mechanics
Published in C.P. Chugh, Ken Steele, V.M. Sharma, Design Criteria for Drill Rigs: Equipment and Drilling Techniques, 2020
C.P. Chugh, Ken Steele, V.M. Sharma
Porosity is a measure of the voids in rock and their capacity for holding water; permeability, the capacity of rocks to let water pass through, is a measure of those voids which are of sufficient size and are in communication. Mud has a high level of porosity that diminishes during its conversion first to clay and later to mudstone or shale. Even then it has a certain porosity but because of the fineness of the clay particles and, therefore, the minute dimensions of the voids, it is impermeable to water. Permeability is thus a measure both of particulate size and degree of packing and can be defined as hydraulic conductivity.
Guidance on Formulating Compressed Solids
Published in Sarfaraz K. Niazi, Handbook of Pharmaceutical Manufacturing Formulations, Third Edition, 2019
Most solid powders contain a certain void volume of empty space. This is distributed within the solid mass in the form of pores, cavities, and cracks of various shapes and sizes. The total sum of the void volume is called the porosity. Porosity strongly determines important physical properties of materials, such as durability, mechanical strength, permeability, adsorption properties, etc. The knowledge of pore structure is an important step in characterizing materials and predicting their behavior.
Assessment of column to particle diameter ratio on the hydraulic conductivity of porous media: Wall effect in Darcy Regime
Published in ISH Journal of Hydraulic Engineering, 2023
Abhishish Chandel, Faizan Fayaz, Vijay Shankar
The shape factor and porosity of the particle also play a vital role in governing the influence of the wall effect on K as the shape factor represents the surface area and the particle volume (Benyahia and O’Neill 2005; Mohanty et al. 2016; Karthik and Buwa 2017). Porosity is a function of the particle to column diameter ratio and arrangement of particles (Hou et al. 2016; Guo et al. 2017). Coarser particles have larger voids near the permeameter wall interface which results in more K compared to the finer particles (Luo et al. 2020). Shape factor is used as a correction factor for the estimation of actual values of K in the empirical relationships (Chapuis 2012). Coarser particles occupy more space which results in larger voids and creates more open space for flow to travel through porous media. Notably, a higher value of shape factor means less resistance to flow, and more K (Loth 2008).
Effect of sintering temperature on physical, mechanical, and electrical properties of nano silica particles synthesized from Indonesia local sand for piezoelectric application
Published in Journal of Asian Ceramic Societies, 2023
Muhammad Sadat Hamzah, Muhammad Waziz Wildan, Edi Suharyadi
In this study, the results of the bulk density and relative density of sintered nanosilica ceramic were obtained at each variation of the sintering temperature. The bulk density of the sintered specimens are in the range of 2.29 g/cm3 – 2.49 g/cm3 as shown in Figure 4. The bulk density and relative density increase with increasing sintering temperature from 1330 ℃ to 1390 ℃, and then decrease at 1420 ℃ to 1450 ℃. The maximum bulk density of 2.49 ± 0.03 g/cm3 and relative density of 94.03 ± 0.01% are obtained at a sintering temperature of 1390 ℃. The increase in density is due to the occurrence of inter-particle densification or greater particle pooling, while the decrease in bulk density and relative density is due to the increase in porosity, as shown in Figure 6. The presence of porosity acts as stress concentration causing a decrease in the strength of the material.
Out-of-plane permeability of 3D woven fabrics for composite structures
Published in The Journal of The Textile Institute, 2020
David May, Björn Willenbacher, Jan Semar, Keith Sharp, Peter Mitschang
The permeability of porous structures in general and technical textiles in particular is determined by several factors. The most important factor in the permeability of a porous structure is its porosity. If the porosity is reduced e.g. by compaction of the textile, then the space available for fluid flow is reduced. One of the most prominent equations describing this effect is the Kozeny–Carman-equation (Equation (2)) (Carman, 1956; Kozeny, 1927) which like Darcy’s law assumes laminar flow. Instead of a general permeability value it comprises several parameters to describe the pore space of a porous media: the particle diameter dp the porosity ε, as well as the so-called Kozeny–Carman constant C, which has to be determined empirically.