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A theoretical basis for evaluating safety and stability of underground engineering is to study changes in rock strength and failure. In the process of coal mining, the failure mechanical properties in coal present a complex change principle that, under various in situ stresses and in a hydrological environment, results in material failure because of its unstable state being driven by energy. Therefore, by establishing a relationship between energy change and deformation process of coal failure, it would contribute to reflecting the essential characteristics relating to coal strength and failure. In order to explore the mechanics and energy evolution characteristics of water-bearing coal under the triaxial compression process, triaxial compression mechanical experiments of coal under different water contents and confining pressures have been conducted in this paper, whose effects relating to different confining pressures, including water content on changes in total strain energy, elastic strain energy, and the dissipation energy of coal have been analysed. As coal is a porous medium containing a pore and fissure structure, the volume change law relating to coal during the deformation and failure process is characterised by porosity, consequently, a damage constitutive model for coal was established from the perspective of energy dissipation based on statistical damage theory. It is believed that this model could better reflect the deformation behaviour of coal under triaxial compression, in which the relationship between damage evolution characteristics and energy dissipation changes has been reflected in the model. Further, the methods of determining the model's parameters have been proposed to verify the rationality of the established model. Finally, the influence of confining pressure and water content on the brittleness in coal has been discussed from the position of energy evolution. Highlights: Triaxial compression experiments were conducted on coal specimens to investigate the effects of water content and confining pressure on energy evolution. Based on statistical damage theory, the constitutive model that combined energy dissipation and coal failure was established. The effects of water content and confining pressure on the coal brittleness were discussed from the aspect of energy evolution. [ABSTRACT FROM AUTHOR]

The high pressure—high velocity oxy fuel (HP-HVOF) process is a thermal spraying process (TSP) for developing the high melting point powder ceramic coating over the surface. The mixture of used rare earth, the erbium oxide is an untouched rare earth oxide in the field of metal spraying and the likes of metal spraying such as the HP-HVOF process is a recently industrial opted process; which is the modified form of the HVOF process. This paper articulates the effects of rare earth (La2O3/CeO2/Er2O3−0.4 wt% each) addition on tungsten carbide coatings developed using high pressure-high velocity oxy fuel process on Martensitic steel having grade SS410. These effects have been analyzed using surface (like scanning electron microscope (SEM), porosity, surface roughness, wettability, and energy dispersive spectroscopy (EDS) test) and mechanical (such as tensile, flexural, and hardness test) characterization has been carried out on coated and uncoated samples. The porosity level of the coating was less than one percent, and the static water contact angle for coated sample (≈130º) was higher than the substrate (≈63º). This shows that fabricated coating is hydrophobic in nature. Moreover; the identification of doped elements has been done using EDS. The comparisons between the substrate and the coated samples have been done and the result shows that the coated sample possess enhanced surface and mechanical properties. [ABSTRACT FROM AUTHOR]

Nowadays, the design of porous bone scaffolds represents a crucial issue in orthopedical applications. In this article, the mechanical properties of a multi-component scaffold with different porosity percentages were investigated. Mori–Tanaka equations were used to estimate various properties of calcium phosphate (CaP) bone cement reinforced by strontium nitrate nanoparticles (NPs) based on porosity percentages in both cases; before and after samples placement in simulated body fluid (SBF) solution. With the support of these equations, the mechanical properties of bone cement material without porosity were estimated to be used in finite element analysis (FEA); so then to assess structural stability and stress distribution, the experimental compression tests on the scaffold were simulated with the ABAQUS engineering package. The mechanical properties observation indicates that the grain and particle size increased by nitrate addition to the bone cement. The approach in this manuscript allows quantifying the effect of porosity on mechanical properties of CaP cements reinforced by the strontium nitrate NPs, to be fabricated based on the patient's needs. [ABSTRACT FROM AUTHOR]

The microstructure, corrosion resistance and mechanical properties of a binary Ti–20Zr (at. %) alloy with differing porosities were investigated. The alloys were produced following a standard powder metallurgy with sintering at 1200 °C for 4, 6, and 8 h. A space holder agent was used to obtain two ranges of relative density, i.e., 74.8–89.3% and 54.6–66.7%. Metallographic examinations were conducted by using optical microscopy and scanning electron microscopy. The confirmation of chemical composition was performed by energy dispersive spectrometry and elemental mapping analysis. Electron backscatter diffraction analysis was conducted to investigate microstructure morphology. Phase identifications were detected by X-ray diffraction. Uniaxial compressive tests were carried out and also potentiodynamic polarization was employed to understand the corrosion performances of the alloys. Experimental results showed that the pore size and pore connectivity were able to be controlled by the sintering time and a fixed amount of space holder agent. The phase constituents of the alloys were characterized as a mixture of predominant hcp α phase and some distorted hcp α′ phase. As foreseen, the ultimate compressive strength and elastic modulus of the alloys increased with increasing relative density. Results of corrosion resistance revealed adding space holder reduced the polarization resistance of Ti–20Zr (at. %) sintered for 6 h from 15.4 to 14.09 Ω. However, volume fraction of general porosity did not affect the microstructure of the alloys. In conclusion, the relative density of the alloys achieved in this study played a crucial role on the mechanical properties and corrosion properties. [ABSTRACT FROM AUTHOR]

The conventional process for CO2 conversion requires high energy and expensive catalysts, and shows poor product selectivity. In this study, we address these challenges by investigating an environmentally friendly method for CO production through the variable frequency microwave-driven CO2 Boudouard reaction over biochar. We hypothesized that tuning the microwave frequency to align with the dielectric properties of biochar, and thereby induce a resonance effect, could significantly enhance reaction efficiency. Experiments were conducted to explore the effect of microwave frequency on CO2 conversion efficiency in the variable frequency microwave reactor operating within a frequency range of 2430–6000 MHz. Results reveal a significant resonance effect at 4225 MHz resulting in an outstanding CO2 conversion of 96.3%, in sharp contrast to the complete absence of conversion observed at the conventional 2450 MHz. The resonance frequency not only facilitated exceptional conversion but also remarkably improved energy efficiency, yielding a productivity of 1427.5 µmol/kJ of CO. This represents a remarkable 474-fold increase compared to electrical heating. Furthermore, continuous microwave irradiation at this optimized frequency demonstrated remarkable stability and induced substantial enhancements in the pore structure and surface area of biochar. This innovative approach provides promising insights into sustainable and efficient CO production processes. [ABSTRACT FROM AUTHOR]

The preparation circumstances and effects of the kaolin-modified SAPO-34 molecular sieves were studied in order to support the industrial application of the cutting-edge technology for producing light olefins from syngas catalyzed by bifunctional catalyst. Additionally, their apparent morphology, crystal structure, structural features, and acid strength were tested. The results demonstrated that kaolin-based molecular sieves are thinly layered and have an acid strength and pore structure that are more conducive to reactions. The effect of the mass ratio of the oxide to the molecular sieve, the hydrogen to carbon ratio of the feed gas, and other reaction conditions on the catalytic activity of the bifunctional catalyst was investigated using modified molecular sieves. Under the reaction conditions of the oxide to molecular sieve mass ratio of 2:1, feed gas composition of n(H2)/n(CO) = 2, 400 °C, and 3 MPa, a CO conversion of 50.11% with a low CO2 selectivity of 17.01% and a light olefins yield of 24.18% could be achieved. [ABSTRACT FROM AUTHOR]

The disposal of industrial by-product tailings has become the focus of mine follow-up work and an important issue in solving environmental pollution. This study explores the potential of utilizing iron tailings and phosphogypsum as cementitious materials, guided by the concept of comprehensive utilization. The mechanical property of cementitious materials was studied under curing 7 days, 14 days, and 28 days. The characteristics of the pores and products of the cementitious material were extracted and analyzed by industrial computed tomography (CT), X-ray diffraction (XRD), and scanning electron microscope (SEM). In the presence of phosphogypsum, more ettringite was generated in the cementitious system. The macropores in the system were filled, reducing the total porosity fraction of cementitious materials from 24.56% to 18.39%. The reduction of macropores significantly enhanced the compressive strength of cementitious material. The addition of fine phosphogypsum reduced the large porosity of the cementitious materials, which revealed the importance of the size in the cementitious material system. The effect of phosphogypsum content on the pore structure of cementitious material of iron tailings was studied. The new type of low-carbon cementitious material prepared from phosphogypsum and iron tailings provided a novel perspective for the multi-solid waste collaborative disposal in this study. In addition, the large amount of consumption of tailings reduced the pollution to the environment. [ABSTRACT FROM AUTHOR]

The data on generating porous structure from PVF during PVA acetalization is presented. The main parameters comprising the average pore diameter, the ratio of open to closed pores, the apparent density, porosity, and water absorption are estimated. It is shown that the density of PVF samples is about 0.54‒0.58 kg/cm3, and the total porosity is 55–57%. The number of open pores decreases from 38% to 23% when the mixing speed grows from 800 to 1200 rpm. The time dependences of PVF water absorption are obtained and it is established that water is mainly sorbed by open pores, reaching the value of 417%. [ABSTRACT FROM AUTHOR]

Porous silicon (por-Si) is a complex multiphase material, the composition and functional properties of which greatly depend on the features of its formation. In this work, samples of porous silicon with porosity indices from 5 to 80% are obtained by electrochemical etching and their photoluminescence properties are studied. The porosity of the samples is varied by changing the current density of electrochemical anodization during the etching process. The porosity index is calculated according to the X-ray reflectometry method. The aim of our work is to establish correlations between the porosity index, composition, intensity, and mechanism of porous-silicon photoluminescence. The surface composition is controlled by ultrasoft X‑ray spectroscopy and infrared spectroscopy. An increase in the degree of oxidation of the surface of the samples with an increase in the porosity index is shown. Two well-known mechanisms of porous silicon photoluminescence associated with the composition and morphology of the surface are found, and it is established at which porosity values they prevail. It is shown that an increase in the porosity index leads to an increase in the intensity of photoluminescence. [ABSTRACT FROM AUTHOR]

Nanocellulose papers offer high tensile strength and modulus but suffer from drawbacks such as their brittle nature. We show that mercerisation of cellulose nanopapers in strong alkaline media for 2 min to 24 h results in the (partial) transformation of native cellulose I into the more ductile cellulose II allomorph. The strain to failure of mercerised nanopapers tripled compared to the original nanopapers while retaining their tensile strength in excess of 100 MPa at the expense of a slight drop in modulus resulting in a significant increase in toughness (total work of fracture). An additional advantage of mercerisation is a reduction in porosity of the nanopapers and increased transparency. [ABSTRACT FROM AUTHOR]

Permeability assessment of naturally fractured rocks and fractured rocks after fracturing is critical to the development of oil and gas resources. In this paper, based on the discrete fracture network (DFN) modeling method, the conventional discrete fracture network (C-DFN) and the rough discrete fracture network (R-DFN) models are established. Through the seepage numerical simulation of the fractured rocks under different DFN, the differences in permeability of the fractured rocks under different parameters and their parameter sensitivity are analyzed and discussed. The results show that unconnected and independent fractures in the fracture network may weaken the seepage capacity of the fractured rocks. The fractured rock permeability increases with increase in connectivity and porosity and decreases with increase in maximum branch length and fracture dip. The use of C-DFN to equate the fracture network in the fractured rocks may underestimate the connectivity of the fracture network. For the more realistic R-DFN, the promotion of gas flow by connectivity is dominant when connectivity is high, and the hindrance of gas flow by fracture roughness is dominant when connectivity is low or when it is a single fracture. The permeability of the fractured rocks with R-DFN is more sensitive to the parameters than that of the fractured rocks with C-DFN. The higher the connectivity and porosity of the fractured rocks, the more obvious the difference between the permeability of the fractured rocks evaluated by C-DFN and R-DFN. [ABSTRACT FROM AUTHOR]

The key problem in oil exploration and engineering is the lack of accurate and reliable data about the reservoir parameters of a field. Having a precise assessment of petrophysical properties can provide the ability to make decisions with a high degree of confidence about planning for production, exploitation, and further field development scenario. In this research, an artificial intelligence (AI)-based approach was developed to improve the estimation of reservoir parameters including porosity and volume of shale, which has a significant role in different stages of hydrocarbon exploration, in the Kashafrud Gas Reservoir in the northeast of Iran. For this purpose, we measured the petrophysical properties of 27 samples of the Kashafrud Formation. To increase the amount of data for employing a multilayer perceptron (MLP) artificial neural network (ANN), a geostatistical algorithm was used to increase the amount of laboratory measured data of porosity and volume of shale to 686 and 702, respectively. In addition, 2263 well-logging data from the same well were provided. The optimal MLP network with the topology of 6-7-1, and 6-8-1 was selected to estimate the porosity and shale volume with mean squared error (MSE) of 2.78731E−4, and 1.28701E−9, respectively. The training process was performed using two different sets of input data. In the first approach, all available well-logging data were used as input, ending up in high MSE. In the second approach, some selected well logs were used based on the results of sensitivity analysis which clearly improved the estimations. The ability of MLP networks made great improvements in the estimation of the both parameters up to 99.9%. The presence of valuable core data in this study significantly improved the process of comparison and conclusion. The final results prove that AI is a trusted method, also the potential of the ANN method for the reservoir characterization and evaluation associated problems should be taken into consideration. Due to the unavailability of core data along the whole wells, the application of intelligent methods, such as machine learning (ML) can be used to estimate the parameters in other oil or gas fields and wells. [ABSTRACT FROM AUTHOR]

Purpose: The present paper proposes to explore the fundamental natural frequencies of a porous functionally graded material (FGM) plates. The effect of porosity in an FGM structure is studied in an uncertain quantification domain. Method: A finite element model is developed considering isoperimetric quadratic element and evaluating the first three natural frequencies for the porous FGM plate. Hereafter, a stochastic approach is explored by incorporating Monte Carlo simulation (MCS) and application of machine learning (ML) models. A detailed comparison is conducted to evaluate the predictive efficiency of five machine learning models viz., radial basis function (RBF), linear regression (LR), Gaussian progression regression (GPR), artificial neural network (ANN), and support vector machining (SVM). Results and Conclusion: The authenticity of the models is evaluated based on the mean and standard deviation error analysis. The error analysis provides adequate confidence on the authenticity of the ML models. The predicted results are depicted in the form a three-dimensional probability density function and scatter plots. The effective results and discussion portray an efficient stochastic model to quantify the uncertainty in the porous FGM structure. [ABSTRACT FROM AUTHOR]

Improvements to nanoindentation techniques have enabled faster data acquisition and expanded data interpretation methods. Methods such as instrumented high-speed nanoindentation facilitate local mapping of nanomechanical properties. To create accurate maps, indent spacing should prevent previous indents from influencing subsequent indents. However, indents must be close enough to understand local property variations. The optimal ratio of indent spacing to indent depth (s/hc) is well established for dense materials, but not for materials with nanoscale porosity. Nanoporous gold was tested at multiple s/hc ratios, to identify optimal spacing for nanoporous structures. These are shown to have the same requirements as dense materials. [ABSTRACT FROM AUTHOR]

This study examines the bending and wave propagation in porous functionally graded (FG) nanoplates rested on the Winkler–Pasternak foundation using a four variable refined sinusoidal plate theory taking into account the two-dimensional magnetic field. The small size effect is taken into account by using the non-local elasticity theory. Porosity-dependent material properties of the porous FG nanoplate are defined to vary consistently through the thickness direction by a modified power law. From Maxwell's magnetic equations, the body force (Lorentz force) is deduced, which is applied to each particle of the structure. Hamilton's principle of variation is used to derive the equations of motion. These governing equations are solved to study the bending and wave propagation analyses of the porous FG nanoplates. The dispersion relation between frequency and wave number is obtained analytically. Numerical examples are presented to verify the accuracy of the present model by comparing it with the solutions given in the literature. Extensive numerical discussions are introduced for bending and waves in the porous FG nanoplates including the impacts of different parameters, like the magnetic parameter, power-law index, porosity factor, nonlocal parameter, plate aspect-ratio, wave number, and the side-to-thickness ratio as well as elastic foundation parameters. [ABSTRACT FROM AUTHOR]

Incised marine valleys (IMVs) are fruitful targets of stratigraphic-based exploration within low-stand system tracts (LSTs). The narrowband volumes constrain the quantification of density, velocity, thickness, lithology, and possible fluids for successful hydrocarbon exploration. This study quantified IMVs using quantitative digital tuning frequency-based seismic volume (DFSV) and tuned frequency-based instantaneous lateral porosity-decomposed inverted density reservoir simulations (LPDS). The seismic amplitudes and reflection strength attributes have imaged medium- to coarse-grained sandstone lenses along the southwestern and westernmost flanks of this gas field. The 24-Hz DFSV imaged a 35 km2 stratigraphic prospect in the aggradation parasequences of fluvial source point bars. The LPDS resolved 7-m-thick gas-bearing reservoirs through blocky gamma-ray signatures. The cross-plot of pseudo and simulated physical parameters showed an R2 of > 0.90 for developing stratigraphically-trapped IMVs in the LSTs, confirming a very high potential of clastic systems for generating hydrocarbons because the reservoir has 1.6–1.8 g/cm3 density of fractured and 23–32% highly porous reservoirs. With strong R2 of > 0.95, an extensive improvement in accommodation space was observed in the porosity range of 23–32% and thickness range of 7–10 m. As a broader implication, there were regionally developed and reduced accommodating spaces of gas-bearing reservoirs within 23–32% porosity range and ~ 10–17% porosity zones. The zones of reductions in accommodation space were under the strong influence of sea-level rise due to compacted sedimentary facies with porosity range of 10–17%, which is equally an analogy aimed at global extensional geology. [ABSTRACT FROM AUTHOR]

Under tectonic stresses, shale in different stress–strain environments will undergo structural deformation of varying mechanisms and intensities, forming various types of tectonically deformed shales (TDSs). By changing pore structures, structural deformation significantly influences shale's reservoir properties and then the resource potentials. This paper aims to reveal the evolution rules and mechanisms of micro- and mesopore structures of various TDSs. We first propose a TDS classification scheme according to the differences in deformation features and deformation mechanisms. Then, N2 and CO2 adsorption tests were conducted on the whole rock and kerogen samples of various TDSs to reveal the pore structure evolutions of shale during structural deformations and investigate the contributions of organic pore changes. Finally, we studied the mineral composition differences between various TDSs and their effects on the evolutions of shale's micro- and mesopores. Results showed that compared with undeformed shale, weakly brittle deformed shale (BDS) experienced a significant reduction in micro- and mesopores, mainly resulting from the decrease of organic matter content caused by the development of tectonic fractures and the filling of hydrothermal minerals. In strongly BDSs, there was a noticeable decrease in micro- and mesopores from undeformed shale as well. Apart from the negative effects of increasing carbonate minerals, the increased clay minerals also caused a decrease in kerogen content and organic pores. The limited increases of pores from weakly BDSs to strongly BDSs is mainly due to the emerged interparticle pores during shale fragmentation. Ductile deformed shale showed a significant decrease in micro- and mesopores; the collapse of organic pores is the dominant mechanism, with the mixing of clay minerals being an important reason as well. As for the brittle–ductile deformed shale, the evolution of micro- and mesopores is the result of the increase of carbonate minerals and the compression of kerogen. [ABSTRACT FROM AUTHOR]

In arrears to pH sensing functions, gold-supported titania nanoparticles (AuTNPs) are synthesized at a low temperature 90 °C by the sol-gel technique. Two different dyes phenol red and creosol red dye are encapsulated in AuTNPs nanocomposite. Void-free AuTNPs exhibited the particle size 45 nm which is reduced to 28 nm and 29 nm after PR and CR encapsulation. Heterogeneous bonding confirms the good interaction of PR and CR dye within AuTNPs. The transmittance decreased from 80% to 71% and 65% because of pores presence after dye encapsulation, while the refractive index increased from 1.06 to 1.07 and 1.09 at 633 nm, and bandgap energy varied from 3.17 eV to 3.1 eV and 3.42 eV of AuTNPs, PR-AuTNPs, and CR-AuTNPs, respectively. The CR-AuTNPs exhibited a color time response 0.2 s at pH 12 and a high pKa 9.9 which is greater than PR-AuTNPs' pka ~ 8 and a time response of 0.4 s. Experimental findings suggested that CR-AuTNPs possessed fast responses as pH sensors. Highlights: Phenol red and creosol red encapsulated gold-supported titania nanoparticles are synthesized at 90 °C by the sol-gel technique for pH sensing. Void-free and porous surfaces are observed before and after dye encapsulation within AuTNPs. The transmittance decreased and the refractive index increased after PR and CR encapsulation in AuTNPs. The CR-AuTNPs exhibited a color time response 0.2 s and a high pKa 9.9 which is greater than CR-AuTNPs pka ~ 8 and time response 0.4 s. Experimental findings suggested that CR-AuTNPs possessed fast responses as pH sensors. [ABSTRACT FROM AUTHOR]

This paper proposed a new approach for the manufacturing of blade preform by cross wedge rolling (CWR) process, and the sintered Ti–6Al–4V alloy prepared by PM process was taken as the billet, and the evolution behavior of residual pores under complex stress and strain state in CWR was investigated by systematic experiments and finite element (FE) simulation. The results showed that the number and size of the pores increased in the central of the rolled part due to the nucleation of new pores and growth of residual pores, and the porosity of other points is significantly lower than the initial state, indicating that the pore closure occurred. Moreover, the evolution behavior of residual pores is closely related to the three-direction principal stress state and maximum shear stress τmax of the rolled part, which are significantly affected by process parameters. Therefore, in order to obtain rolled part with higher density, the initial forming temperature T and area reduction φ should not be less than 980 °C and 50 pct, respectively, and the maximum allowable rolling speed n should be limited to 10 r/min. [ABSTRACT FROM AUTHOR]

In this study, lotus root-carbon aerogel (LR-CA) was successfully synthesized using facile hydrothermal, freeze-drying, and pyrolysis methods. Herein, under various calcination conditions, the lotus root-carbon aerogel-nitrogen (LR-CAN) materials maintained the three-dimensional structure with a well-developed hierarchical pore structure. Besides, LR-CAN materials also showed excellent adsorption capacity for ciprofloxacin (CIP) under specific conditions: 0.4 g/L catalyst, 50 mg/L CIP concentration, and pH 7 with removal efficiency and adsorption capacity reaching 97.1% and 241.1 mg/g, respectively. Notably, the presence of interfering salts (NaCl, KCl, and Na2SO4) minimally affected the CIP adsorption capacity of the material and demonstrated stable performance after five reuse cycles, albeit with a slight decrease in adsorption capacity from 242.2 to 200.9 mg/g. Moreover, the LR-CAN exhibited the highest adsorption capacity with chloroform, n-hexane, and used cooking oil at 27.1, 21.0, and 14.3 g/g, respectively. In addition, the LR-CAN performed outstanding electrochemical properties with the CV curve achieving the rectangular area and specific capacitance calculated from the GCD method reaching the maximum at 292.3 F/g at the current density of 3 A/g. In addition, the ability to maintain stable capacitance after 500 cycles, retaining an efficiency of 80.1%. These findings highlight the potential of environmentally friendly CA materials in effectively treating antibiotic pollutants and their promising application in supercapacitor electrode fabrication. [ABSTRACT FROM AUTHOR]

Enhanced levels of alloy print defects such as porosity are associated with the printing of overhang structures by laser powder bed fusion (L-PBF). This study compared the microstructure and porosity of Ti-6Al-4V overhang structures, with that observed for the bulk alloy. It was observed in the region around the overhang structure that the microstructure exhibited larger grain sizes and was less homogenous, compared to the that obtained within the bulk alloy. An increased level of porosity of up to 0.08% was also observed in the overhang print alloy, compared with the corresponding < 0.02% in the alloy bulk. It is hypothesised that these microstructural changes are associated with the excess heat generated in the overhang region, due to the decreased thermal conductivity of the powder immediately below the print layers, compared with solid alloy. During L-PBF alloy printing, in situ process monitoring of the melt pool emissions was obtained in the near-infrared range and correlated with the properties of the printed parts. This in-process data was used to assist in selecting optimal laser processing conditions, in order to help prevent melt pool overheating at the overhang. By systematically controlling the laser energy during the printing of the first fifteen layers over the overhang structure, the level of porosity was reduced, to the < 0.02% level of the bulk alloy. There was also an associated reduction in the roughness (Ra) of the overhang itself, with its Ra decreasing from 62.4 ± 7.3 to 7.5 ± 1.9 µm. [ABSTRACT FROM AUTHOR]

Polylactic acid/ZIF-8 composite membranes were prepared by polylactic acid (PLA) electrospun fibers and zeolitic imidazolate framework-8 (ZIF-8). In order to adhere inorganic particles to the fiber membrane effectively, water-soluble polyvinyl alcohol (PVA) was mixed with ZIF-8 and scraped onto the PLA fiber membrane. Furthermore, the samples were treated by steam for obtaining the rich pore structures. The coating amount of ZIF-8 and the steam treatment time of the composite membrane were determined by evaluating the adsorption performance of the acid dye. The optimal PLA/ZIF-8 membrane was selected for antibiotics adsorption testing at different temperatures. The results showed that the stable and maximum adsorption capacities of tetracycline hydrochloride (TC) and oxytetracycline (OTC) were 90.92 and 69.64 mg/g at 60 °C, respectively. The adsorption processes of the two antibiotics were in accord with the second-order kinetic models. This work provided a technology for developing the porous membranes in water treatment. [ABSTRACT FROM AUTHOR]

The synthesis of three-dimensional covalent organic frameworks with highly connected building blocks presents a significant challenge. In this study, we report two 3D COFs with the nia topology, named JUC-641 and JUC-642, by introducing planar hexagonal and triangular prism nodes. Notably, our adsorption studies and breakthrough experiments reveal that both COFs exhibit exceptional separation capabilities, surpassing previously reported 3D COFs and most porous organic polymers, with a separation factor of up to 2.02 for benzene and cyclohexane. Additionally, dispersion-corrected density functional theory analysis suggests that the good performance of these 3D COFs can be attributed to the incorporation of highly aromatic building blocks and the presence of extensive pore structures. Consequently, this research not only expands the diversity of COFs but also highlights the potential of functional COF materials as promising candidates for environmentally-friendly separation applications. The synthesis of three-dimensional (3D) covalent organic frameworks (COFs) with highly connected building blocks presents a significant challenge. Here, the authors report the synthesis of two 3D COFs with the nia topology, by introducing planar hexagonal and triangular prism nodes. [ABSTRACT FROM AUTHOR]

Purification of ethylene (C2H4) as the most extensive and output chemical, from complex multi-components is of great significance but highly challenging. Herein we demonstrate that precise pore structure tuning by controlling the network hydrogen bonds in two highly-related porous coordination networks can shift the efficient C2H4 separation function from C2H2/C2H4/C2H6 ternary mixture to CO2/C2H2/C2H4/C2H6 quaternary mixture system. Single-crystal X-ray diffraction revealed that the different amino groups on the triazolate ligands resulted in the change of the hydrogen bonding in the host network, which led to changes in the pore shape and pore chemistry. Gas adsorption isotherms, adsorption kinetics and gas-loaded crystal structure analysis indicated that the coordination network Zn-fa-atz (2) weakened the affinity for three C2 hydrocarbons synchronously including C2H4 but enhanced the CO2 adsorption due to the optimized CO2-host interaction and the faster CO2 diffusion, leading to effective C2H4 production from the CO2/C2H2/C2H4/C2H6 mixture in one step based on the experimental and simulated breakthrough data. Moreover, it can be shaped into spherical pellets with maintained porosity and separation performance. C2H4 is one of the most important chemical raw materials. Here, the authors report that tuning of pore structure shifts the multi-component gas separation function, enabling one-step production of high-purity C2H4 in the quaternary mixture. [ABSTRACT FROM AUTHOR]

Creating different pore environments within a covalent organic framework (COF) will lead to useful multicompartment structure and multiple functions, which however has been scarcely achieved. Herein we report designed synthesis of three two-dimensional COFs with amphiphilic porosity by steric-hindrance-mediated precision hydrophilic-hydrophobic microphase separation. Dictated by the different steric effect of the substituents introduced to a monomer, dual-pore COFs with kgm net, in which all hydroxyls locate in trigonal micropores while hydrophobic sidechains exclusively distribute in hexagonal mesopores, have been constructed to form completely separated hydrophilic and hydrophobic nanochannels. The unique amphiphilic channels in the COFs enable the formation of Janus membranes via interface growth. This work has realized the creation of two types of channels with opposite properties in one COF, demonstrating the feasibility of introducing different properties/functions into different pores of heteropore COFs, which can be a useful strategy to develop multifunctional materials. Creating different pore environments within a covalent organic framework (COF) leads to useful multicompartment structure and multiple functions. Here, the authors propose a strategy to construct amphiphilic COFs with separated hydrophilic and hydrophobic nanochannels by precisely controlling the distribution of hydrophilic and hydrophobic segments in two different kinds of pores. [ABSTRACT FROM AUTHOR]

Thin features are integral components of most lightweight cellular lattice structures; however, limited studies are carried out to understand their property/quality aspects. This experimental study investigates the influence of powder feedstock size, feature geometry, and process parameters on the property/quality of thin lightweight features fabricated using a laser powder bed fusion additive manufacturing (L-PBF-AM) system. Three different Ti6Al4V powder feedstocks (fine, medium, and coarse) were utilized, and the dimensions of the features were varied in the range of 0.1 to 0.5 mm. The experimental data were analyzed to gain insights into the powder feedstock-geometry-process-property/quality (PGPP/PGPQ) characteristics, which had not been previously explored but are crucial for designing lightweight structures using L-PBF-AM. The results indicated that both powder feedstock size and feature dimension significantly influenced the properties and quality of the fabricated thin features. Additionally, feature type, volumetric energy density, and their interactions exhibited varying effects on geometrical accuracy, porosity, grain size, and flexural properties. Struts showed lower success rates, grain sizes, and dimensional errors but higher mechanical properties compared to walls. However, both features exhibited similar porosity characteristics. Regarding powder feedstock size, smaller powder sizes were found to be advantageous for fabricating lower-dimensional features and improving their mechanical properties. The feature geometry type also significantly influences the final material properties. A notable observation was that the 0.1 mm wall features exhibited the lowest mechanical properties, particularly in terms of yield strength, while the 0.5 mm strut features exhibited lower mechanical properties among the struts. The findings of the study underscored the importance of understanding the compound relationships between powder feedstock, feature geometry, process parameters, and the resulting properties/quality for lightweight features in L-PBF-AM. Further research is necessary to establish the knowledge and understanding of L-PBF-AM thin features and elucidate the PGPP/PGPQ characteristics in greater detail. [ABSTRACT FROM AUTHOR]

The paper presents the methodology and results of core tests to assess the impact of colloid migration on apparent permeability under cyclic confining pressure. In the work, porous limestone cores were used. The research methodology differs from similar works in that the core was blown with nitrogen at a high pressure gradient between loading and unloading cycles to clean the pores. Blowings cause permeability dynamics that contradict classical theory, according to the results of multi-cycle core tests. Forward and reverse blowings disturb the porous medium's internal equilibrium, resulting in a change in apparent permeability between core test cycles. This phenomenon can only be explained by colloid migration, which provides pore throat blocking and unblocking during nitrogen injection. A visual comparison of micrographs before and after the tests revealed that the surface structure of the pores remained unchanged, but mobile particles ranging in size from several microns to 50 microns were observed in each observed pore. The proposed mechanism for changing apparent permeability during gas injection and cyclic confining pressure correlates well with the results of core tests. [ABSTRACT FROM AUTHOR]

Evaluating the mechanical properties of gas (primarily methane) hydrate-bearing sediments is essential for commercial production as a next-generation resource and understanding the global carbon cycle. Triaxial and uniaxial compression tests have been conducted on synthetic gas hydrate and natural core samples recovered from deep-sea beds using pressure coring techniques. The results show that four factors are vital in establishing the strength of hydrate-bearing sediments: hydrate saturation, effective confining stress, porosity, and strain rate. However, no study has evaluated these factors in a unified and quantitative manner, and even if the physical properties of the reservoir are known in detail from logging, predicting the strength has been challenging. In this study, pressure cores were drilled and recovered from the Eastern Nankai Trough in April 2018 after Japan's second offshore production test, and triaxial or uniaxial compression tests were performed on 12 pressure core samples brought back to the laboratory. The mechanical properties of the hydrate-bearing sediments were classified with previous obtained results from 53 pressure cores and 223 synthetic cores, and empirical equations for triaxial compressive strength and deformation modulus were proposed as functions of gas hydrate saturation, effective confining pressure, porosity, and strain rate. The obtained equations were found to correlate well with the experimental data and can predict the strength and deformation modulus from logging data. [ABSTRACT FROM AUTHOR]

The spatial variability of hydrogeological parameters is a significant source of uncertainty in groundwater numerical modeling and has a certain risk impact on the prediction of pollutant migration and transformation. Current research has focused on the effects of single-parameter spatial variant random fields or utilizing random sampling methods to randomly combine multiple-parameter spatial variant random fields while ignoring the correlation between parameters. This paper proposes an innovative concept of associated random variables to construct multi-parameter synergistic spatial variant random fields, ensuring both the spatial variability and inherent correlation of the parameters. A hypothetical case was constructed, and the Monte Carlo sampling experiment based on computer simulation was used to assess groundwater pollution risks with multiple associated parameters. The results show that hydraulic conductivity and porosity are the main sensitive parameters. The associated random variable allows for the representation of positive correlation, negative correlation, and no correlation between the hydraulic conductivity and porosity. The pollutant mass concentrations in each observation well conform to the generalized extreme value distribution, and the pollution risks of each water well as well as the concentration distribution intervals of pollutants with different probabilities can be obtained. The influence of associated parameters on the cumulative risk of contaminants in observation wells and pollution degree range is only related to their mathematical distribution and is independent of correlations between parameters. This study addresses the issues of spatial variability and inherent correlation of hydrogeological parameters, which are of great significance for groundwater pollution risk assessment and the promotion of sustainable water quality management of groundwater resources. [ABSTRACT FROM AUTHOR]

In this work, in situ sol–gel strategy was used to introduce silica gel in polyacrylonitrile (PAN) membrane pores, by which the pore structure of organic solvent nanofiltration (OSN) membrane prepared with thermal crosslinking was maintained well. The chemical structure, microstructure and morphology changes of membrane during sol–gel and thermal crosslinking were systematically studied by FTIR, XPS, XRD and SEM. Benefitting from the introduction of silica gel, the fusion of membrane pore structure during thermal crosslinking was effectively inhibited by supporting the pore with silica gel. Therefore, the permeances of the thermally crosslinked membranes supported by in situ silica gel were greatly improved. Furthermore, the thermally crosslinked membrane showed excellent stability of OSN performance due to the generated ladder structure of membrane during thermal crosslinking. This work showed that in situ silica gel supporting is a promising strategy to stabilize the pore structure of PAN membrane during thermal crosslinking. [ABSTRACT FROM AUTHOR]

The repair construction of bridge decks typically involves the method of half-width traffic and half-width construction, where traffic vibrations (TV) can disrupt newly laid cementitious materials on the bridge deck. Engineered cementitious composites (ECC), owing to their high ductility, are widely applied in the repair of bridge deck surfaces. While there have been studies on the fundamental performance of ECC in road surface repair projects, the impact of TV on ECC's tensile properties (TP) and pore structure (PS) remains unclear, and the mechanisms through which TV affects ECC are not well defined. To analyze the effects of TV on ECC's TP and PS, a custom-built vibration platform was utilized to simulate bridge deck TV. Experimental investigations were conducted on ECC specimens using uniaxial tensile (UT) tests and mercury intrusion porosimetry (MIP). Results indicate a significant impact of TV on the TP of freshly mixed ECC, particularly during the initial setting (IS) to final setting (FS) stages. TV-induced structural damage, resulting in identifiable cracking, increased porosity and reduced uniaxial tensile strength (UTS) by approximately 2–23%. However, TV did not substantially affect ECC strain hardening and ultra-high toughness; the tensile strain remained above 3% under different vibration parameters. Applying pulses before the IS improved the PS of ECC to some extent and enhanced UTS. Post-FS, ECC exhibited enhanced resistance to external disturbances, with minimal impact from TV. A strong correlation was observed between UTS and PS characteristics, indicating that the evolution of PS reflects the UTS of ECC. Utilizing the gray relational theory, this study investigated the influence of different vehicular vibration conditions on ECC's tensile performance and pore structure. The findings reveal a significant impact of age at which the specimens were vibrated (AV) and vibration frequencies (VF) on ECC's pore structure and tensile performance. Furthermore, gray target theory was applied to rank the effects of different TV conditions on ECC performance, revealing minimal impact post-FS. The ECC specimen subjected to vibrations at 4 Hz frequency, initiated after 36 h, and sustained for 5 h exhibited the optimal comprehensive performance. This research contributes to the design and application of ECC in practical construction scenarios, mitigating material damage during construction processes. [ABSTRACT FROM AUTHOR]

Analyzing the pore structure in carbonate reservoirs plays a crucial role in predicting fluid flow characteristics within these formations. The goal of the study was to use machine learning techniques for pore structure analysis and estimation of permeability in carbonate reservoirs. We implemented these algorithms by examining 2D scanning electron microscope (SEM) images of carbonate samples from the Jaisalmer sub-basin captured at various magnifications. In the initial stage of the analysis, various binarization algorithms were applied to determine carbonate sample porosity. Among these algorithms, the MaxEntropy algorithm gave a porosity value closely aligned with those obtained through petrography analysis. We employed the watershed algorithm to find the pore network parameters of carbonate samples at various magnifications. We observed that changes in magnification affected pore network parameters, resulting in a reduction in pore size distribution, throat radius, and grain size. Subsequently, we employed the numerical lattice Boltzmann method (LBM) to estimate the permeability of carbonate samples and compared to values derived from well logs. We employed machine learning (ML) algorithms, specifically Artificial Neural Network (ANN) and Support Vector Machine (SVM), to predict the permeability of carbonate samples. The input features for these models were the pore network parameters, while the LBM permeability values served as the output. We examine the prediction performance of these methods against the measured LBM permeability by conducting the error analysis and the coefficient of determination ( R 2 ) calculation. Our findings revealed that the ANN models outperformed the SVM models. Specifically, the ANN model displayed an impressive R2 value of 0.892, along with root mean square error (RMSE), mean squared error (MSE) and, mean absolute error (MAE) values of 1.927, 3.716 and 1.580, respectively. In contrast, the SVM model yielded an R2 value of 0.849, with RMSE, MSE and, MAE values of 2.324, 5.401 and, 2.166 respectively, when assessed on testing data of measured permeability. This study found that ANN is more dependable, robust, and precise than SVM in forecasting carbonate sample permeability. [ABSTRACT FROM AUTHOR]

Adsorbents modified solely with chlorine have limited effectiveness in removing mercury at high temperatures. This study aims to investigate the influence of various acid (HNO3, H2SO4, and H2O2) loadings on the removal efficiency of mercury from NH4Cl-modified adsorbents. The objective is to develop rice straw carbon adsorbents that are both more efficient and cost-effective. The experiments were conducted on a fixed bed experimental platform, with SEM and BET to observe the physical property changes of the modified char samples. XPS analysis was employed to analyze the effects of oxygen, chlorine, and sulfur functional groups. Additionally, a kinetic model was used to investigate the interaction mechanism between the adsorbent and mercury. The findings demonstrate that co-modification surpasses the use of NH4Cl alone, with the combination of NH4Cl and HNO3 yielding the best resu lts. Co-modification enhances the development of a more refined and compact pore structure on the char surface, promoting the physical adsorption of mercury. Moreover, an increased presence of chlorine and oxygen functional groups is observed on the char surface, particularly in the NH4Cl and HNO3 co-modified samples, further enhancing the chemical adsorption capacity of the char. The results from the kinetic analysis support this conclusion. Furthermore, the adsorption process of Hg0 relies on both external mass transfer and chemical adsorption, with the chemical adsorption process playing a more significant role as the controlling factor. [ABSTRACT FROM AUTHOR]

Due to the threat to food supply and human health posed by cadmium-contaminated wastewater, a highly effective adsorbent is under necessary development to remove cadmium from wastewater. In this study, four new types of modified biochars with different modifier concentrations were prepared from chicken manure using K2FeO4 as a modifier, and the modified biochar KFBC1 with the best adsorption effect was obtained through optimal experiments. Various characterization analyses have shown that KFBC1 has a rough surface structure, abundant pore structure, and a large number of functional groups. Additionally, iron oxides are introduced on the surface of the biochar, which provided a favorable condition for the adsorption of Cd(II) in wastewater. The adsorption performance of Cd(II) on the biochar before and after modification was investigated through batch adsorption experiments. The adsorption kinetic model of KFBC1 to Cd(II) in solution was in accordance with the quasi-secondary kinetic model, and the adsorption isothermal model was in accordance with the Langmuir model, with a maximum adsorption capacity of 330.06 mg/g, which was 5.15 fold of pristine BC. Meanwhile, the adsorption rate of Cd(II) by KFBC1 was positively correlated with dosage and pH. Pore adsorption, ion exchange, surface precipitation, interaction with -π electrons, and complexation of oxygen-containing functional groups on the surface were considered as important mechanisms for the removal of Cd(II) by KFBC1. According to the results, KFBC1 is a novel and efficient adsorbent that can be used as a treatment agent for cadmium-contaminated wastewater. [ABSTRACT FROM AUTHOR]

For complex and multi-layered clastic oil reservoir formations, modeling lithofacies and petrophysical parameters is essential for reservoir characterization, history matching, and uncertainty quantification. This study introduces a real oilfield case study that conducted high-resolution geostatistical modeling of 3D lithofacies and petrophysical properties for rapid and reliable history matching of the Luhais oil reservoir in southern Iraq. For capturing the reservoir's tidal depositional setting using data collected from 47 wells, the lithofacies distribution (sand, shaly sand, and shale) of a 3D geomodel was constructed using sequential indicator simulation (SISIM). Based on the lithofacies modeling results, 50 sets of porosity and permeability distributions were generated using sequential Gaussian simulation (SGSIM) to provide insight into the spatial geological uncertainty and stochastic history matching. For each rock type, distinct variograms were created in the 0° azimuth direction, representing the shoreface line. The standard deviation between every pair of spatial realizations justified the number of variograms employed. An upscaled version of the geomodel, incorporating the lithofacies, permeability, and porosity, was used to construct a reservoir-flow model capable of providing rapid, accurate, and reliable production history matching, including well and field production rates. [ABSTRACT FROM AUTHOR]

Nanocomposites are emerging as a new generation of materials that can be used to combat water pollution. Zeolite-based nanocomposites consisting of combinations of metals, metal oxides, carbon materials, and polymers are particularly effective for separating and adsorbing multiple contaminants from water. This review presents the potential of zeolite-based nanocomposites for eliminating a range of toxic organic and inorganic substances, dyes, heavy metals, microplastics, and ammonia from water. The review emphasizes that nanocomposites offer enhanced mechanical, catalytic, adsorptive, and porosity properties necessary for sustainable water purification techniques compared to individual composite materials. The adsorption potential of several zeolite-metal/metal oxide/polymer-based composites for heavy metals, anionic/cationic dyes, microplastics, ammonia, and other organic contaminants ranges between approximately 81 and over 99%. However, zeolite substrates or zeolite-amended soil have limited benefits for hyperaccumulators, which have been utilized for phytoremediation. Further research is needed to evaluate the potential of zeolite-based composites for phytoremediation. Additionally, the development of nanocomposites with enhanced adsorption capacity would be necessary for more effective removal of pollutants. [ABSTRACT FROM AUTHOR]

The properties of two-dimensional covalent organic frameworks (2D COFs), including porosity, catalytic activity as well as electronic and optical properties, are greatly affected by their interlayer stacking structures. However, the precise control of their interlayer stacking mode, especially in a reversible fashion, is a long-standing and challenging pursuit. Herein, we prepare three 2D copper-organic frameworks, namely JNM-n (n = 7, 8, and 9). Interestingly, the reversible interlayer sliding between eclipsed AA stacking (i.e., JNM-7-AA and JNM-8-AA) and staggered ABC stacking (i.e., JNM-7-ABC and JNM-8-ABC) can be achieved through environmental stimulation, which endows reversible encapsulation and release of lipase. Importantly, JNM-7-AA and JNM-8-AA exhibit a broader light absorption range, higher charge-separation efficiency, and higher photocatalytic activity for sensitizing O2 to 1O2 and O2•− than their ABC stacking isostructures. Consequently, JNM-8-AA deliver significantly enhanced photocatalytic activities for oxidative cross-coupling reactions compared to JNM-8-ABC and other reported homogeneous and heterogeneous catalysts. The precise control of interlayer stacking mode of 2D materials is a long-standing pursuit. Here, the authors report two 2D copper-organic frameworks that can undergo the reversible interlayer sliding through environmental stimulation. [ABSTRACT FROM AUTHOR]

In this paper, the pore structure and methane adsorption properties of the primary structural and tectonic coals of the Handan Jiulong Mine were analyzed using low-temperature nitrogen adsorption experiments and isothermal adsorption tests. The relationship between pore structure and adsorption properties was discussed. The study results show that the total pore volume and specific surface area of the tectonic coal in the Jiulong Mine are larger than those of the primary structural coal. Small pores comprise most of the pore volume in the primary structural coal, followed by micropores and medium pores. The pore volume of the tectonic coal primarily consists of small pores, followed by micropores and medium pores. Micropores and medium pores consist of approximately the same volume. The specific surface area of both the tectonic coal and the primary structural coal is primarily micropores, followed by small, and medium pores. The microporous and small pore structures of the tectonic coal have open pore morphology. The pore shapes are primarily in the shape of ink bottles. The coal sample of primary structural coal contains both open pore morphology and numerous closed pore morphology. The pore shape is mainly columnar. The pressure-boosting adsorption process of coal samples conforms to the Langmuir isothermal adsorption equation. The maximum adsorption capacity of tectonic coals is greater than that of primary structural coals. The adsorption capacity and Langmuir volume (VL) of coal samples decrease with increasing temperature, while the Langmuir pressure (PL) increases with temperature. The larger the pore volume of coal samples, especially the micropore volume, the greater the adsorption capacity, and the richer the specific surface area of micro-pores, creating a more substantial adsorption capacity. [ABSTRACT FROM AUTHOR]

The effect of slow shot speed on externally solidified crystal (ESC), porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and laboratory computed tomography (CT). Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy. The AlSi9MnMoV alloy, which was designed with trace multicomponent additions, displays a notable grain refining effect in comparison to the AlSi10MnMg alloy. Refining elements Ti, Zr, V, Nb, B promote heterogeneous nucleation and reduce the grain size of primary a-Al. At a lower slow shot speed, the large ESCs are easier to form and gather, developing into the dendrite net and net-shrinkage. With an increase in slow shot speed, the size and number of ESCs and porosities significantly reduce. In addition, the distribution of ESCs is more dispersed and the net-shrinkage disappears. The tensile property is greatly improved by adopting a higher slow shot speed. The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa (increased by 11.52%), and the elongation is enhanced from 3.72% to 6.34% (increased by 70.52%). [ABSTRACT FROM AUTHOR]

A CPB06-based Stewart-Cazacu micromechanical damage model is implemented and validated for Ti6Al4V material. It provides accurate numerical predictions in terms of macromechanical material response and damage accumulation. The Stewart & Cazacu–Tvergaard & Needleman–Thomason (SC11–TNT) based damage model presented here is developed and implemented in the finite element software Lagamine following a semi-implicit cutting plane algorithm and a well-chosen flow rule approach. The damage of the material is characterized by the porosity ratio contained within the material. It is modelled by void nucleation, growth and coalescence mechanisms. The onset of the coalescence is established by a criterion based on Thomason's approach. The macroscopic results obtained by the implemented model demonstrate a strong ability to predict the experimental elastoplastic mechanical behaviour of the material across a full deformation range and different types of loadings. At the microscopic level, the predicted accumulated porosity ratio of the material matrix at fracture exhibits a good correlation with the experimental observations. The element deletion feature, activated when a certain damage threshold is reached, provides a physical description of the loss of load-carrying capacity of the material during fracture. [ABSTRACT FROM AUTHOR]

The replacement of feldspars is commonly characterized by pseudomorphism and reaction-induced pore generation. However, the effects of compositions of feldspars and fluids on porosity generation during alteration are still poorly understood. In this study, we conducted a series of hydrothermal experiments on plagioclase replacement by 2 M KCl or NaCl aqueous solutions at 600 °C and 150 MPa for 1–8 days, using plagioclase with different compositions (anorthite, An96Ab4; labradorite, An66Ab33Or1; albite, An1Ab99) with or without quartz. Albite replacement by K-feldspar was not affected by the presence of quartz, whereas anorthite was unaltered in the quartz-absent fluid. The replacement of labradorite by KCl(aq) showed different results: in the presence of quartz, labradorite was altered by K-feldspar, whereas in the absence of quartz, alteration proceeded significantly with the generation of large pores hosted by secondary anorthite coupled with euhedral K-feldspar overgrowth. Such textural relationship and oxygen isotope-labeled experiments reveal that silica-deficient fluid enhances the uncoupled dissolution reprecipitation process. The Si and Al ions in the reacted aqueous solution diffused outside the labradorite grains and encountered K+-rich solutions to grow K-feldspar. The experiments with polycrystalline rocks composed of amphibole + labradorite using 2 M KCl aqueous solution indicated the replacement of labradorite grains by anorthite and K-feldspar overgrowth, as found in single-crystal experiments. Our results indicate that the silica concentration in the fluids has different influences on the saturation indices of albite, anorthite, and K-feldspars in saline fluids, which significantly affect the replacement textures and porosity generation in crustal rocks. [ABSTRACT FROM AUTHOR]

Electret fiber filtration materials prepared by electrostatic spinning and corona polarization have drawn significant interest in treating radioactive aerosols. In this study, a three-dimensional biomass-based electret nanofiber aerogel material with high dust capacity, high filtration efficiency and low-pressure drop was created by pore structure regulation. The results showed that aerogels with good charge capture and storage ability were obtained by regulating the concentration of tert-butanol and ethylcellulose fiber suspension, and the pre-freezing temperature. The initial surface potential and stable surface potential increased from 0.85 and 0.05 kV to 1.37 and 0.15 kV respectively. Furthermore, the purification time was reduced from 44 to 15 min. [ABSTRACT FROM AUTHOR]

In this novel research, three laser beams of equal intensities were employed to form multiple orthogonal Porous Silicon (PSi) layers on the bilateral and the front silicon substrate. The morphology of the synthesized PSi layers, composed of multi-axis of Si nanocrystallites columns, pores and mud-like structures, and perpendicular to each other. These specific Psi morphologies are created via two various laser-supporting etching pathways with an appropriate optical system consisting of different types of lenses, three laser diodes of similar power 100 mW with a short wavelength of 410 nm were employed as a photonic source during the etching process. The morphological, structural, and optical properties of the bi-lateral and top PSi layers were investigated extensively. The obtained results display the existence of ultra-high density of Si columns, pores and trenches in the front and the opposite lateral PSi layer. The grain sizes, surface morphology, PL emission and chemical bonds of the bi-lateral porous layers show a high degree of symmetry. This unique PSi layer can be suggested as an excellent choice for improving the surface area and decreasing the surface leakage current in porous silicon-based gas sensor devices. [ABSTRACT FROM AUTHOR]

Orthopedic implants play a crucial role in restoring the function and life quality of the population with musculoskeletal disorders. However, implant failure and lack of integration with the surrounding bone tissue, mainly in patients with low bone quality, remain significant challenges in biomedicine. Porous bioactive coatings have emerged as a promising approach to address these issues. This work aims to explore the feasibility of preparing porous hydroxyapatite coatings by high-velocity oxy-fuel spray (HVOF) and, as a first approach, to evaluate the performance of the porous bioactive coatings obtained in simulated body fluid for a possible application in orthopedic surfaces. This paper discusses the use of polyester as a pore-forming agent and the importance of some relevant factors, such as coating fabrication parameters and post-spraying treatments, for producing porosity in the coatings. The results display the formation of different degrees of porosity ranging from 3.8% to 38% depending on the weight fraction of the pore-forming phase employed to prepare the hydroxyapatite coatings. The coatings were evaluated in Hanks balanced solution at body temperature by employing different electrochemical techniques; interestingly, the results suggest different bioactive responses as a function of porosity. [ABSTRACT FROM AUTHOR]

Large amount of inhalation of the radon exacerbates the risk of cancer in the human body, and human beings also pay more attention to the problem of environmental pollution. With the increasing mining of underground mineral resources, coal production has increased significantly, but at the same time, it has also increased the number of underground goaf, and it has also seriously increased the potential danger of spontaneous combustion in the goaf. The influence of thermal effect on pore structure and radon exhalation characteristics was studied by means of relevant measurement. The outcomes confirmed that the radon exhalation characteristics of fly ash increased linearly with the increase of temperature and then decreased exponentially. At 400 °C, the radon exhalation rate of fly ash is the highest, which is 8.41 Bq m−2 h−1, 2.11 times that of fly ash at normal temperature. This is closely related to the change in pore structure of fly ash after heat treatment. The research results in this study are significant for assessing the radiation risk of radon in fly ash. [ABSTRACT FROM AUTHOR]

Continental sandstones of aeolian and fluvial systems are major reservoir targets for petroleum and CO2 storage in several places worldwide. The Permo-Carboniferous sandstones in Saudi Arabia are significant aeolian and fluvial, owing to their huge hydrocarbon reserves. Previous studies have documented the sedimentology, stratigraphy, and hydrocarbon potentials of the reservoirs. Nevertheless, the roles of grain-rimming illite, other clays (kaolinite and chlorite), and cements on porosity evolution of the sandstones are poorly constrained in the literature. We utilized a multi-technique approach consisting of petrography, X-ray powder diffraction, and scanning electron microscope to study the composition, textural features, diagenesis, and role of grain-rimming illite in arresting quartz cementation within aeolian and fluvial sandstones. Our findings indicate that illite coatings inhibited quartz cementation, and 40% illite-coating coverage efficiently restricted the growth of authigenic quartz cement. Intergranular illite and quartz cement were the most abundant cements that significantly impacted reservoir quality. However, porosity was chiefly reduced owing to compaction rather than cementation. Fluvial sands have poor reservoir quality due to low mechanical infiltration to emplace grain-coating clays and high amounts of co-deposited clays that occluded intergranular porosity and blocked pore throats in the sandstones. The grain size was found not to influence illite-coating coverage. Overall, carbonate and Fe-oxides (hematite) cements have less influence on reservoir quality. A total intergranular cement (clays, carbonates, and Fe-oxides) volume between 20 and 30% has a detrimental effect on intergranular porosity. The results of the study can be utilized to understand better and predict reservoir quality in sandstones of similar depositional settings around the world. [ABSTRACT FROM AUTHOR]

In this investigation, aluminum alloy (AA2024) composite reinforced with ceramic particulates, namely alumina (Al2O3) and aluminum nitride (AlN), were designed and fabricated through a semi-automatic stir casting route. The ceramics are added complementary (0–4 wt% @ step of 1%), resulting in five composite specimens, namely ON04, ON13, ON22, ON31, and ON40. The composite specimens are then analyzed for their densities, mechanical, and tribological behavior (steady-state sliding wear analysis), adopting ASTM standards. The Taguchi design of experiment technique was adopted for planning test preliminaries and input sliding wear operating parameters (like sliding velocity, sliding distance, normal load, composition, and environment temperature) optimization using ANOVA. Worn surface morphology studies were reported using a scanning electron microscope (SEM) along with energy-dispersive X-ray spectroscopy (EDS) to understand prevalent wear mechanisms in real time. Additionally, a decision-making technique such as the preference selection index (PSI) system was used to analyze the alloy composites ranking. The theoretical densities vary 2.784–2.798 g/cc, while actual densities vary 2.539–2.546 g/cc, and voids fraction vary within the 0.5–9.3 % range. The hardness varies 71.6–85.4 HRB, impact strength varies 54–170 J, and tensile strength varies 190–265 MPa. The ranking orders of the significance of input operating factors are environment temperature > normal load > sliding velocity > reinforcement content > sliding distance. It has been found that the alloy composite sample ON22 with an equal presence of both ceramics exhibits overall optimum mechanical properties as well as superior steady-state behavior, which was consistent with the results of the PSI ranking method. [ABSTRACT FROM AUTHOR]

Enhancing natural gas storage capacity by utilizing the pore space of sediments in cavern bottoms holds significant potential, particularly in high impurity salt formations. This study presents comprehensive insights into the pore structures of sediment samples through the application of X-ray computed tomography imaging. Three-dimensional reconstruction models were employed to extract and quantitatively analysed the pore network characteristics. Fluid flow simulations were conducted to investigate the non-uniform distribution of the brine velocity field, influenced significantly by particle size. Probability and cumulative distribution curves of pore equivalent radius, pore coordination number, pore throat equivalent radius, and throat length were effectively fitted using the log-normal and Boltzmann functions, respectively. Notably, the permeability of partial packings exhibited a positive correlation with porosity and displayed an upward trend in correlation with particle size. Moreover, during the debrining process, sediments comprising finer particles exhibited a higher susceptibility to blockage, thereby escalating the risk of particle clogging. These findings offer valuable insights for the development of anti-clogging strategies during debrining operations. Highlights: Expanding storage capacity: Storing natural gas in the pore space of sediments in cavern bottoms offers a significant increase in storage capacity in high impurity salt formations. X-ray computed tomography analysis: The use of X-ray computed tomography allowed for the reconstruction and quantitative analysis of the pore structures and pore network models of the sediment samples. Fluid flow simulations: Three-dimensional simulations of fluid flow in the packing samples provided insights into the non-uniform distribution of the brine velocity field and its dependence on particle size. Permeability and particle blockage: The study revealed that permeability of the partial packings exhibited a positive correlation with particle size. Fine particles were found to pose a higher risk of blockage during debrining, highlighting the importance of anti-clogging methods in the process. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of o-cresol to produce o-methyl cyclohexanol, an important chemical intermediate, is an attractive approach. The design and development of efficient non-precious metal catalysts for the selective o-cresol hydrogenation remain a great challenge. Herein, cobalt nanoparticles embedded in nitrogen-doped carbon with hollow structure (Co@HCN) were fabricated by direct pyrolysis of hollow zeolitic imidazolate framework-67 (HZIF-67), and were applied in the selective hydrogenation of o-cresol to o-methyl cyclohexanol for the first time. The pyrolysis temperature and Co(NO3)2·6H2O concentration jointly regulate the morphology and physicochemical properties of the Co@HCN-T-x catalysts (T represents the pyrolysis temperature and x represents the Co(NO3)2·6H2O concentration in octanol), and significantly affect their catalytic properties. Co@HCN-500-0.1 exhibits superior catalytic activity, which is 3.3 times higher than Co@HCN-700-0.1 and 1.3 times higher than Co@HCN-500-0.4. Large ratio of meso-/macro-porous specific surface area and pore volume, small Co size with uniform dispersion, and abundant surface Co and CoNx contents together contribute to the superior catalytic activity of Co@HCN-500-0.1. More importantly, Co@HCN-500-0.1 displays convenient magnetic recoverability, superior catalytic recyclability and universal applicability. This work provides significant insights for the design of efficient non-precious metal catalysts to be applied in the selective hydrogenation of o-cresol. Hollow Co@HCN nanospheres were synthesized by one-step pyrolysis of HZIF-67, and the morphology, pore structure, Co size and distribution, surface composition, and yield can be adjusted by the pyrolysis temperature and Co(NO3)2·6H2O concentration. The presence of the hollow shell layer not only enhances the diffusion of the reactants, but also facilitates the dispersion and exposure of Co species, which in turn improves the catalytic performance for the selective hydrogenation of o-cresol to o-methyl cyclohexanol. [ABSTRACT FROM AUTHOR]

This study investigates the influence of thermal conditions and wet-dry cycling on the pore characteristics of red sandstone, utilizing nuclear magnetic resonance spectrometry for analysis. The red sandstone samples were subjected to elevated temperatures followed by a series of wet-dry cycles. Our findings reveal a significant alteration in the porous architecture of the sandstone samples post-thermal treatment, primarily attributed to water evaporation and mineral expansion. Particularly, after 40 cycles of wetting and drying, the total porosity of the samples increased, most notably when subjected to a temperature of 800 °C, where an 88.9% increase in total porosity was observed. Furthermore, as the number of cycles increased, the internal pore connectivity improved due to water-induced effects. The volume of micropores (r < 0.1 µm) showed a decreasing trend, while mesopores (0.1 μm < r < 1 µm) remained relatively constant, and the volume of macropores (r > 1 µm) increased under the same thermal conditions. These results have important implications for rock stability monitoring and engineering protection, as they demonstrate that wet-dry cycles can significantly exacerbate the degradation of the material properties of red sandstone by increasing its effective pore volume. [ABSTRACT FROM AUTHOR]