Sedimentology, sequence stratigraphy and facies analysis have for many years been disciplines rather separate from diagenesis which is concerned with processes occurring after deposition. Prediction ...of rock properties as a function of burial depth in sedimentary basins requires that these disciplines become more integrated. Compaction of sedimentary rocks is driven towards increased density (lower porosity) and higher rock velocity as functions of burial depth (effective stress) and temperature. Both the mechanical and chemical compaction of sedimentary rocks are functions of the primary textural and mineralogical composition of the sediments at the time of deposition and after shallow burial diagenesis. This is controlled by the provenance, transport and depositional environment. Many published sedimentological studies, however, contain little information about the mineralogical and textural composition of the sedimentary sequences.
Near the surface, sediments are in an open geochemical system due to groundwater flow, diffusion and evaporation. Here their composition may be changed by mineral dissolution and transport of the dissolved components. At greater depth, below the reach of significant meteoric water flow, the porewater has an exceedingly low mobility and capacity to transport solids in solution. The porewater will gradually approach equilibrium with the minerals present, reducing the concentration gradients in the porewater and the potential for both advective and diffusive transport of solids in solution. Significant increased porosity (secondary porosity) is dependent on the dissolution and removal of solids in solution which may occur during freshwater flushing at shallow depth dissolving feldspar and precipitating kaolinite. Below the reach of freshwater the porewater flow is limited and represents a geochemically nearly closed system. The porewater will in most marine sediments be in equilibrium with calcite, even if it occurs in small amounts. Prediction of rock properties such as porosity and seismic velocity at a certain depth in a sedimentary basin must be based on the burial history (effective stress and temperature), but the primary mineralogical and textural composition of the sediments is equally important. Studies of depositional environments and provenance should therefore be integrated with diagenesis and be a part of basin analysis which is used for basin modelling.
Photocatalytic self-cleaning coatings with a high surface area are important for a wide range of applications, including optical coatings, solar panels, mirrors, etc. Here, we designed a highly ...porous TiOsub.2 coating with photoinduced self-cleaning characteristics and very high hydrophilicity. This was achieved using the swelling-assisted sequential infiltration synthesis (SIS) of a block copolymer (BCP) template, which was followed by polymer removal via oxidative thermal annealing. The quartz crystal microbalance (QCM) was employed to optimize the infiltration process by estimating the mass of material infiltrated into the polymer template as a function of the number of SIS cycles. This adopted swelling-assisted SIS approach resulted in a smooth uniform TiOsub.2 film with an interconnected network of pores. The synthesized film exhibited good crystallinity in the anatase phase. The resulting nanoporous TiOsub.2 coatings were tested for their functional characteristics. Exposure to UV irradiation for 1 h induced an improvement in the hydrophilicity of coatings with wetting angle reducing to unmeasurable values upon contact with water droplets. Furthermore, their self-cleaning characteristics were tested by measuring the photocatalytic degradation of methylene blue (MB). The synthesized porous TiOsub.2 nanostructures displayed promising photocatalytic activity, demonstrating the degradation of approximately 92% of MB after 180 min under ultraviolet (UV) light irradiation. Thus, the level of performance was comparable to the photoactivity of commercial anatase TiOsub.2 nanoparticles of the same quantity. Our results highlight a new robust approach for designing hydrophilic self-cleaning coatings with controlled porosity and composition.
The electrical double-layer supercapacitance performance of the nanoporous carbons prepared from the Phyllanthus emblica (Amala) seed by chemical activation using the potassium hydroxide (KOH) ...activator is reported. KOH activation was carried out at different temperatures (700-1000 °C) under nitrogen gas atmosphere, and in a three-electrode cell set-up the electrochemical measurements were performed in an aqueous 1 M sulfuric acid (Hsub.2SOsub.4) solution. Because of the hierarchical pore structures with well-defined micro- and mesopores, Phyllanthus emblica seed-derived carbon materials exhibit high specific surface areas in the range of 1360 to 1946 msup.2 gsup.−1, and the total pore volumes range from 0.664 to 1.328 cmsup.3 gsup.−1. The sample with the best surface area performed admirably as the supercapacitor electrode-material, achieving a high specific capacitance of 272 F gsup.−1 at 1 A gsup.−1. Furthermore, it sustained 60% capacitance at a high current density of 50 A gsup.−1, followed by a remarkably long cycle-life of 98% after 10,000 subsequent charging/discharging cycles, demonstrating the electrode's excellent rate-capability. These results show that the Phyllanthus emblica seed would have significant possibilities as a sustainable carbon-source for the preparing high-surface-area activated-carbons desired in high-energy-storage supercapacitors.
This paper presents the elastic buckling and static bending analysis of shear deformable functionally graded (FG) porous beams based on the Timoshenko beam theory. The elasticity moduli and mass ...density of porous composites are assumed to be graded in the thickness direction according to two different distribution patterns. The open-cell metal foam provides a typical mechanical feature for this study to determine the relationship between coefficients of density and porosity. The partial differential equation system governing the buckling and bending behavior of porous beams is derived based on the Hamilton’s principle. The Ritz method is employed to obtain the critical buckling loads and transverse bending deflections, where the trial functions take the form of simple algebraic polynomials. Four different boundary conditions are considered in the paper. A parametric study is carried out to investigate the effects of porosity coefficient and slenderness ratio on the buckling and bending characteristics of porous beams. The influence of varying porosity distributions on the structural performance is highlighted to shed important insights into the porosity design to achieve improved buckling resistance and bending behavior.
SUMMARY
Increasing mesophyll conductance of CO2 (gm) is a strategy to improve photosynthesis in C3 crops. However, the relative importance of different anatomical traits in determining gm in crops is ...unclear. Mesophyll conductance measurements were performed on 10 crops using the online carbon isotope discrimination method and the ‘variable J’ method in parallel. The influences of crucial leaf anatomical traits on gm were evaluated using a one‐dimensional anatomical CO2 diffusion model. The gm values measured using two independent methods were compatible, although significant differences were observed in their absolute values. Quantitative analysis showed that cell wall thickness and chloroplast stroma thickness are the most important elements along the diffusion pathway. Unexpectedly, the large variability of gm across crops was not associated with any investigated leaf anatomical traits except chloroplast thickness. The gm values estimated using the anatomical model differed remarkably from the values measured in vivo in most species. However, when the species‐specific effective porosity of the cell wall and the species‐specific facilitation effect of CO2 diffusion across the membrane and chloroplast stoma were taken into account, the model could output gm values very similar to those measured in vivo. These results indicate that gm variation across crops is probably also driven by the effective porosity of the cell wall and effects of facilitation of CO2 transport across the membrane and chloroplast stroma in addition to the thicknesses of the elements.
Significance Statement
The variation of mesophyll conductance across crops is independent of classical anatomical characteristics. Mesophyll conductance variation across crops is probably driven by the effective porosity of the cell wall and effects of facilitation of CO2 transport across the membrane and chloroplast stroma in addition to the thicknesses of the elements.
Analyzing and mastering the fractal features of coal-measure sedimentary rocks is crucial for accurately describing the pore structure of coalbed methane resources. In this work, mercury intrusion ...porosimetry (MIP) and nuclear magnetic resonance (NMR) are performed on coal-measure sedimentary rocks (i.e., shale, mudstone, and sandstone) to analyze their pore structure. Pore size distributions (PSDs) and the multifractal dimensions of the investigated samples are discussed. Moreover, multivariable linear regression models of multifractal dimensions are established through a comprehensive analysis of multifractal characteristics. The results show that sandstone (SS-1) and clay rocks are dominated by nanopores of 0.01 to 1 μm, while sandstone (SS-2) is mostly mesopores and macropores in the range of 1 to 10 μm. The fractal characteristics of the investigated rock samples show a prominent multifractal characteristic, in which Dsub.A reflects the surface structure of micropores, while Dsub.S represents the pore structure of macropores. Multifractal dimension is affected by many factors, in which the Dsub.A is greatly influenced by the pore surface features and mineral components and the Dsub.S by average pore diameters. Moreover, multivariate linear regression models of adsorption pore and seepage pore are established, which have a better correlation effect on the multifractal dimension.
•Flood modelling in real urban areas is a challenge for differential anisotropic porosity models.•Direction-dependent, cell-based conveyance porosity is not trivial to estimate.•A method is proposed ...to extract conveyance porosity fields from building footprints.•Straightforward application to complex urban layouts provides accurate results.•A Fortran numerical implementation of the proposed method is made available.
In the framework of porosity models for large-scale urban floods, this work presents a method to compute the spatial distribution of the porosity parameters of complex urban areas by analyzing the footprints of buildings and obstacles. Precisely, an algorithm is described that estimates the four parameters required by the differential, dual-porosity formulation we recently presented. In this formulation, beside the common isotropic porosity accounting for the reduced storage volume due to buildings, a cell-based conveyance porosity is introduced in the momentum equations in tensor form to model anisotropic resistances and alterations in the flow direction due to presence of preferential pathways such as streets. A cell-averaged description of the spatial connectivity in the urban medium and of the preferential flow directions is the main ingredient for robust and mesh-independent estimates. To achieve this goal, the algorithm here presented automatically extracts the spatially distributed porosity fields of urban layouts relying only on geometrical information, thus avoiding additional calibration effort. The proposed method is described with the aid of schematic applications and then tested by simulating the flooding of complex urban areas using structured Cartesian grids. A Fortran implementation of the algorithm is made available for free download and use.
The construction of single‐atom catalysts (SACs) with high single atom densities, favorable electronic structures and fast mass transfer is highly desired. We have utilized metal‐triazolate (MET) ...frameworks, a subclass of metal–organic frameworks (MOFs) with high N content, as precursors since they can enhance the density and regulate the electronic structure of single‐atom sites, as well as generate abundant mesopores simultaneously. Fe single atoms dispersed in a hierarchically porous N‐doped carbon matrix with high metal content (2.78 wt %) and a FeN4Cl1 configuration (FeN4Cl1/NC), as well as mesopores with a pore:volume ratio of 0.92, were obtained via the pyrolysis of a Zn/Fe‐bimetallic MET modified with 4,5‐dichloroimidazole. FeN4Cl1/NC exhibits excellent oxygen reduction reaction (ORR) activity in both alkaline and acidic electrolytes. Density functional theory calculations confirm that Cl can optimize the adsorption free energy of Fe sites to *OH, thereby promoting the ORR process. The catalyst demonstrates great potential in zinc‐air batteries. This strategy selects, designs, and adjusts MOFs as precursors for high‐performance SACs.
A Zn/Fe‐bimetallic metal‐triazolate framework (MET) modified with 4,5‐dichloroimidazole (dcIm) was used to prepare the Fe single‐atom catalyst FeN4Cl1/NC. In the oxygen reduction reaction (ORR), the catalyst offers fast mass transfer and high catalytic activity because of abundant mesopores (pore:volume ratio 0.92), a high Fe loading (2.78 wt %), and defined FeN4Cl1 sites with a distinct electronic structure.
Zirconia ceramic foams with ultra‐high porosity of 96%–98% have been fabricated using sodium dodecyl sulfate (SDS) as the particle stabilizer of zirconia particles for the first time. The wet foams ...stabilized by zirconia particles are ultra‐stable due to partially hydrophobic zirconia particles modified by SDS. Zirconia foams exhibit close cells with thin cell wall and small grain size. Increasing SDS concentration favors the foamability of the suspension, and further increases the porosity of ceramic foams. Zirconia ceramic foams with porosity of 98.1% have compressive strength of 0.26 ± 0.05 MPa. Decreasing solid loading leads to the porosity of ceramic foams. The compressive strength could be improved significantly by increasing the sintering temperature. Zirconia ceramic foams with porosity of 97.9% has low thermal conductivity of 0.027 ± 0.004 W·(m·K)−1, which could be used as thermal insulation and refractory material.
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