Pore System Research Articles

Hierarchical Porous Bimetallic FeMn Metal-Organic Framework Gel for Efficient Activation of Peracetic Acid in Antibiotic Degradation.

Effective techniques for eliminating antibiotics from water environments are in high demand. The peracetic acid (PAA)-based advanced oxidation process has recently drawn increasing attention for its effective antibiotic degrading capability. However, current applications of PAA-based techniques are limited and tend to have unsatisfactory performance. An additional catalyst for PAA activation could provide a promising solution to improve the performance of PAA. Bulky metal-organic framework gels (MOGs) stand out as ideal catalysts for PAA activation owing to their multiple advantages, including large surface areas, high porosity, and hierarchical pore systems. Herein, a bimetallic hierarchical porous structure, i.e., FeMn13BTC, was synthesized through a facile one-pot synthesis method and employed for PAA activation in ofloxacin (OFX) degradation. The optimized FeMn MOG/PAA system exhibited efficient catalytic performance, characterized by 81.85% OFX degradation achieved within 1 h owing to the specific hierarchical structure and synergistic effect between Fe and Mn ions, which greatly exceeded the performance of the only PAA-catalyzed system. Furthermore, the FeMn MOG/PAA system maintained >80% OFX degradation in natural water. Quenching experiments, electron spin resonance spectra, and model molecular degradation revealed that the primary reactive oxygen species responsible for the catalytic effect was R-O•, especially CH3C(=O)OO•, with minor contributions of •OH and 1O2. Overall, introduction of the MOG catalyst strategy for PAA activation achieved high antibiotic degradation performance, establishing a paradigm for the design of heterogeneous hierarchical systems to broaden the scope of catalyzed water treatment applications.

Post-evaluation of frost resistance of cement concrete entities based on pore spacing factors of hardened concrete

In this paper, the effects of water-cement ratio, air-entraining agent type, and air content on the pore characteristic parameters of hardened concrete were investigated through an extensive series of experimental studies. First of all, according to different water-cement ratios, air-entraining agent types, and air contents, the correlation between the concrete pore spacing factor and the frost resistance durability factor was revealed by using the automatic analysis and testing instrument for the pore system of hardened concrete. Then, the decision tree method was utilized to propose specific pore spacing factors for different concrete scenarios, including the non-air-entrained concrete, air-entrained concrete, concrete with unqualified frost resistance, and concrete with qualified frost resistance. In cases where the pore spacing factor measurement fell within an ambiguous range, the classification was further refined according to the water-cement ratio. On that basis, the comprehensive range of pore spacing factors for the concrete with a qualified frost resistance was determined. Finally, the post-evaluation method and standard procedure for assessing the frost resistance of concrete entities based on pore spacing factor and water-cement ratio were proposed to verify whether the frost resistance of concrete buildings meets the life expectancy requirements. This method facilitates the evaluation of the frost resistance quality of newly-built concrete projects, as well as the investigation and monitoring of frost resistance in existing structures during service.

Efficient spatial separation of charge carriers over Sv-ZnIn2S4/NH2-MIL-88B(Fe) S-scheme heterojunctions for enhanced photocatalytic H2 evolution and antibiotics removal performance

The exploration of highly efficient sunlight-assisted photocatalyst for photodegradation of organic contaminants or energy conversion is strongly encouraged. In this work, we designed a novel three-dimensional spindle-like Sv-ZIS@NMFe heterojunction made of amino functionalized NH2-MIL-88B(Fe) (NMFe) and ZnIn2S4 nanosheets with abundant sulfur vacancies (Sv-ZIS). The structural properties of NMFe materials, such as a clearly defined system of pores and cavities, were retained by the Sv-ZIS@NMFe composites. Additionally, the incorporation of sulfur vacancies, –NH2 functional groups, and well-matched energy level positions led to various synergistic effects that considerably enhanced internal electron transformation and migration, as well as improved adsorption performance. Consequently, under visible light irradiation, the optimized sample exhibited superior hydrogen production activity and tetracycline hydrochloride photodegradation performance. At last, density functional theory calculations was used to further elucidated the possible photoreactivity mechanism. This study demonstrates that the Sv-ZIS@NMFe heterojunction materials formed by ZnIn2S4 with suitable sulfur vacancies and amino functionalized Fe-MOFs have promising applications in photocatalysis.

Numerical Analysis of Rarefied Gas Flow through a System of Short Channels

The S-model kinetic equation is used to study the rarefied gas flow from a high-pressure tank to a low-pressure one through a flat membrane with a finite number of pores. The kinetic equation is solved numerically using a second-order accurate implicit conservative method implemented in the in-house code Nesvetay. For transitional and continuum flow regimes, numerical solutions of the compressible Navier–Stokes equations are obtained. The gas flow rate through the system of pores and the forces acting on the membrane bars are investigated as functions of the Knudsen number (Kn) at a pressure ratio of 2 : 1 in the tanks. The features of the flow field near the membrane and away from it are described.

Microscopic investigation of the effect of uniaxial stress on the structure of pore-fissure system and methane adsorption in lean coal

In order to study the mechanism of interaction between stress, pore-fissure system, and methane adsorption. Adopting a novel combination of experimental and simulation methods. Through uniaxial fracture experiments and X-ray micro-CT scanning experiments, it was found that the pore-fissure system of coal blocks first closed and then sharply increased with the increase of uniaxial stress. Based on relevant experiments, unit cell models under different uniaxial stresses were constructed. Through simulation calculations using Zeo++-0.3 code and Materials Studio, it was found that the pore system of unit cells first decreases and then increases with the increase of uniaxial stress, and the maximum adsorption capacity of methane first decreases and then increases. The experimental and simulation results for the evolution characteristics of the coal pore system under different uniaxial stresses were consistent. Stress affects methane adsorption in coal by altering the pore-fissure system characteristics. Stress has a significant impact on the macroscopic and molecular microscopic systems of coal pores. In front of the mining and excavation working face, the gas pressure and content increase, the coal body is damaged, and the coal body stress increases. This also explains that this area is prone to coal and gas outburst.

Estimation of Capillary‐Associated NAPL‐Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method

AbstractBy employing kinetic interface sensitive (KIS) tracers, we investigate three different types of glass‐bead materials and three natural porous media systems to quantitatively characterize the influence of the porous‐medium grain‐, pore‐size and texture on the specific capillary‐associated interfacial area (FIFA) between an organic liquid and water. By interpreting the breakthrough curves (BTCs) of the reaction product of the KIS tracer hydrolysis, we obtain a relation for the specific IFA and wetting phase saturation. The immiscible displacement process coupled with the reactive tracer transport across the fluid–fluid interface is simulated with a Darcy‐scale numerical model. Linear relations between the specific capillary‐associated FIFA and the inverse mean grain diameter can be established for measurements with glass beads and natural soils. We find that the grain size has minimal effect on the capillary‐associated FIFA for unconsolidated porous media formed by glass beads. Conversely, for unconsolidated porous media formed by natural soils, the capillary‐associated FIFA linearly increases with the inverse mean grain diameter, and it is much larger than that from glass beads. This indicates that the surface roughness and the irregular shape of the grains can cause the capillary‐associated FIFA to increase. The results are also compared with the data collected from literature, measured with high resolution microtomography and partitioning tracer methods. Our study considerably expands the applicability range of the KIS tracers and enhances the confidence in the robustness of the method.

Self‐Healing Concrete Due the Use of on Demand opening Core‐Shell Capsules

AbstractIncreasing the durability of concrete is one of the major challenges in terms of environmentally friendly concrete. To achieve this, it is necessary to develop smart materials, which are superior to the current materials in term of multi‐field requirements. These materials are characterized by their ability to detect starting damages and the ability to initialize the self‐healing process. Self‐healing concrete is subject of current research and performed in different ways. In terms of this work autonomous self‐healing due to the use of an epoxy‐resin, encapsulated in a core‐shell capsule is investigated. The opening of the capsules should be realized by irradiation with microwaves. Therefore, the shell of the capsules was functionalized with trigger materials. The on demand opening of the capsules was investigated with sub‐μ‐CT. According to the tomography a 3‐dimensional model of the pore system was calculated. Based on this model a pore size distribution was calculated to get insight in the opening of the capsules. These investigations showed a successful release of the active agent.

Modeling of heat transfer at local convection over a vertical throughflow in a two-layered air-heat generating porous system

Convective heat transfer in an air layer partially filled with a heat-generating granular porous medium is studied. There is a slow seepage of air through the layer in the vertical direction with a constant velocity. Equal temperatures are maintained at the outer solid permeable boundaries, and the heat source strength is constant within the porous sublayer and is proportional to the solid volume fraction. The permanent heat generation within the porous sublayer, combined with the vertical throughflow, causes a nonlinear thermal profile which is conducive for convection to occur. The Boussinesq approximation and Darcy's law are used to describe this convection. Numerical solution of the nonlinear convective problem is obtained on the basis of Newton's method. In the limiting case, the numerical data for the onset of convection are compared with the results of the earlier paper of the authors, where a linear stability theory and a method for constructing of the fundamental system of partial solution vectors have been applied, and with the data by other authors. The stationary regimes of local convection, which occurs in an “air – heat-generating porous medium-air” system over the basic vertical throughflow, and its effect on the heat transfer from the porous air sublayer with the growth of supercriticality are studied. It is shown that, depending on the velocity of the basic throughflow (the Peclet number), convection excitation can be both soft (due to supercritical pitchfork bifurcation) and hard (when the loss of stability of the basic throughflow is accompanied by subcritical pitchfork bifurcation that gives rise to an unstable secondary convective regime). This secondary regime is replaced by a stable tertiary convective regime with increasing supercriticality. It has been found that the total heat transfer rate for the upward basic throughflow exceeds that for the downward basic throughflow significantly, and that local convection at any direction of this throughflow increases the heat transfer rate in the system. An increase in the Nusselt number with the growth of supercriticality is recorded. However, a noticeable contribution of local convection to the total heat transfer is observed only when all values of the Pecklet number are negative and its positive values are lower than 2.

A hierarchically porous PEDOT embedded cryogel for in-syringe solid phase extraction of parabens in beverages

A hierarchically porous adsorbent was fabricated using polyethylene dioxythiophene (PEDOT) embedded in a polyvinyl alcohol cryogel. This adsorbent was designed for use in the in-syringe solid-phase extraction (IS-SPE) of parabens present in beverage samples. The creation of a hierarchical pore system was achieved through a reaction between a hydrochloric acid solution and calcium carbonate, strategically introduced during the cryogel synthesis within a needle hub. The porous structure of the cryogel allowed for efficient entrapment of adsorption materials, significantly increasing the number of available adsorption sites. Additionally, PEDOT was incorporated to enhance paraben adsorption through hydrophobic and π-π interactions. High-performance liquid chromatography was employed to quantify the extracted parabens. Under optimized conditions, the developed method exhibited detection limits ranging from 0.15 to 0.25 µg L–1 and quantification limits ranging from 0.50 to 1.0 µg L–1. The technique was successfully applied to assess parabens in various beverage samples, consistently obtaining extraction recoveries between 88.4% and 98.4%, and relative standard deviations (RSDs) below 6%. We conclude that the in-syringe extraction approach offers a straightforward and efficient method, while the composite adsorbent demonstrates ease of preparation and robust reproducibility, allowing for twelve extraction–desorption cycles.

Impact of cycling on the performance of mm-sized salt hydrate particles

Potassium carbonate is shown to be a promising salt for thermochemical heat storage. For a thermochemical reactor application, the salt hydrate is manufactured in mm-sized particles. It is known that salt hydrate particles undergo swelling and cracking during cyclic testing. Therefore, in this work the influence of cycling on structural and morphological evolution is investigated and the resulting impact on the hydration performance. It is found that the incremental volume increase during cycling is independent of the density at which a particle is produced. With lower starting relative density particles are found to be stable for more cycles compared to particles produced with high starting relative densities. Powder formation at the particle surface starts as soon as the particle density is close to values reported for percolation thresholds. The morphological changes during cycling result in formation of isolated pores and a highly tortuous pore system. As a result, the effective diffusion coefficient for cycled particles is lower compared to what is predicted for as produced particles with similar porosity resulting in lower power output than expected based on porosity. The results from this work help in understanding the reasons for swelling, cracking, powder formation and decreased performance with cycling, laying the foundation for mitigating these unwanted effects.

Investigation on the thermal control and performance of PCM–porous media-integrated heat sink systems: Deep neural network modelling employing experimental correlations

Phase change material (PCM)-based heat sinks can offer reliable and effective thermal management (TM) solutions for increasingly sophisticated applications. A critical aspect of such heat sinks is determining how long it takes them to reach a set-point temperature. However, no generalised method exists in the literature that can predict and interpret the thermal performance of a wide range of PCM–porous media-integrated heat sinks. In this regard, this study examines the heat transfer characteristics of PCM-based heat sinks integrated with various metallic foams through experimental and deep learning (DL) techniques. The experiments are performed for transient TM analysis of various PCM-based heat sinks. Diverse variables, including foam porosity (0.95–0.97), PCM fraction (0.6–0.8), heat flux (0.8–2.4 kW/m2), foam materials (Fe–Ni alloy, Ni and copper) and PCM type (RT-35HC, RT-44HC, RT-54HC and paraffin wax), are investigated in this study. The experimental data are fed to the optimal DL model using the Bayesian surrogate model-tuned hyperparameters. Utilising a correlation analysis, as exemplified by the heat map and correlation plot, in conjunction with explainable artificial intelligence, it has been deduced that the thermal performance of the heat sink is principally influenced by factors such as PCM type, PCM fraction, foam material, foam porosity, and heat flux. Comparing the model's predicted data with the empirical findings, a good agreement was observed. Specifically, the mean absolute error (MAE) for the anticipated temperature and gradient registered at 0.0438 and 0.0054, whilst the mean square error (MSE) manifested values of 0.0579 and 0.0087, respectively. The proposed model can accurately assess the heat sink's thermal performance (correlation coefficient, R2 = 0.99) for various PCM types, fractions, foam materials, applied heat flux and foam porosity.

Tracking deactivation of zeolite beta with and without a detailed structure model: XRD analysis and in situ studies

This paper introduces two versatile new models for assessing the deactivation level of the industrially useful catalyst Beta zeolite. 1) a stacking disorder (SD) model: in which supercells built from stacked layers with refined faulting probability are generated, averaged and fitted to the powder pattern, and dummy carbon atoms in the pore system allow estimation of the degree of deactivation by coke; 2) a semi-empirical (SE) model: in which a reduced tetragonal unit cell is used to fit the sharp Bragg reflections in the PXRD pattern in a Le Bail-type fit and the broad, diffuse peaks are fitted individually to obtain intensities and positions. The reduced cell gives very precise lattice parameters, which can be determined quickly for a series of in situ data, while the ratio between the scale factor of the sharp reflection part in the model and the intensity of the first broad peak gives a measure of the degree of deactivation by coke. The models are validated, and their strengths and weaknesses compared by fitting of in situ PXRD data collected during temperature programmed oxidation of coke from two Beta zeolite samples fully deactivated in the MTH process. Analysis of such data from Beta zeolites has not been demonstrated before and could provide a convenient and useful tool for the chemical industry.

Evolution Mechanism of Microscopic Pore System in Coal-Bearing Marine–Continental Transitional Shale with Increasing Maturation

The formation and evolution mechanisms of complex types and scales of marine–continental transitional shale pores are still indefinite, restricting the accurate evaluation of shale reservoir and the effective evaluation of coal-bearing marine–continental transitional shale gas resource quantity. Considering the Shanxi shale in Ordos basin of China as the research object, combining the FE-SEM images and petrophysical analysis, high-pressure mercury intrusion porosimetry, and CO2 and N2 adsorption–desorption experiments, the structure characteristics and differential evolution mechanisms of multiscale and multitype of coal-bearing shale pores were discussed. The results show that coal-bearing marine–continental transitional shales are rich in clay minerals and organic matters (OMs). Pores developed within organic matters, clay, and brittle minerals of coal-bearing shale have decreasing porosity values. OM pores are directly related to micro- and mesopores, with high specific surface areas, while the porosity of inorganic pores increases with the increasing pore diameter. The porosity of all pores shows a positive relationship with permeability, which changes periodically with the increase in maturity. Coal-bearing shale pores are mainly plate- and ink bottle-shaped, with multimodal pore size distributions. Controlled by both diagenesis and hydrocarbon generation, the evolution of coal-bearing shale pores could be mainly divided into four stages. Furthermore, the pore evolution model of coal-bearing marine–continental transitional shale was preliminarily constructed. This study would enhance the understanding of reservoir evolution of the coal-bearing shale and provide useful information for the assessment and evaluation of reservoir capacity.

Conjugate local thermal non-equilibrium heat transfer in a porous medium-filled cavity with a rotating cylinder: Analysis and insights

In this work, local thermal non-equilibrium effects are examined as they relate to conjugate natural convection heat transfer in a cavity filled with a porous medium. The investigation also considers the rotation of the central cylinder and the undulation of the cavity’s solid sides. Additionally, the analysis includes the consideration of heat transfer bifurcation occurring at the interface between the solid walls and the porous medium. The equations that govern the behavior of the fluid within the porous region and the heat transfer equations for the porous matrix and solid walls are mathematically expressed as partial differential equations. To solve these equations, the finite element method is employed. The study reports and analyzes the influence of parameters such as Darcy number, Rayleigh number, Prandtl number, and thermal conductivity ratio on flow and thermal fields. Additionally, the study examines the effect of rotational cylindrical motion on fluid flow and heat transfer via its speed rotation. The results indicate that undulated walls and rotational speed significantly impact fluid streamlines and isotherm contours within the porous space, as well as the distribution of isotherms within the solid walls. The findings of this study could have practical implications in the design and optimization of porous media-based systems involving heat transfer.

The influence of polymer powder on the ion transportation and antierosion mechanism of cement mortar: From experiments to molecular dynamics simulation

As the main product of hydration reaction of common Portland cement, calcium silicate hydrate (C-S-H) gel is a porous gel system containing capillary and gel pores. These channels act as transport channels for water molecules and ions in the cement system. The diffusion of water molecules and ions through C-S-H gel channels has significant effects on the strength, shrinkage, creep, chemical and physical reactions of the cement system. Polymer can modify cement-based materials and improve their ionic permeability resistance. In this study, emulsified asphalt powder (EAP) and vinyl acetate ethylene copolymer (VAE) redispersible polymer powder was added into the Portland cement mortar as admixtures, respectively. The influence of redispersible polymer powder on the transportation and erosion mechanism of ions in cement mortar was investigated by analyzing the pore structure, compressive strength ratio, chloride ion permeability depth and micromorphological of cement mortar. The adsorption and diffusion behaviors of ions with different concentrations and water molecules were explored by molecular dynamics simulation, and the physiochemical reactions between ions and hydration products during the transport process in cement-based materials were comprehended.

Design of a porous lignocellulose-based hydrogel-Pd nanoparticles reactor system and its in-situ simultaneous adsorption-catalysis process concept for pollutant remedy

The separation and reusability of nano-catalysts are paramount for their high-efficiency and low-cost use. Herein, lignocellulose hydrogels (LCG), were fabricated and served as the host matrix for in-situ generated palladium nanoparticles (Pd NPs), creating hydrogel-based Pd NPs reactor systems. The lignocellulose hydrogel-based Pd NPs (LCG/Pd NPs) reactor system possesses the following unique features: (1) lignin present in LCG acts as a “green” reducing agent so that Pd NPs are formed in situ; (2) the in-situ generated Pd NPs are well dispersed in the LCG structure via complexation; (3) the simultaneous adsorption-catalysis process concept is very effective for pollutant remedy: the adsorption of pollutants on the porous LCG effectively increases the pollutant concentration on the reaction sites, where the Pd NPs are co-located, enhancing the catalytic reactions; as a result, a much higher catalytic reaction rate is observed; (4) the LCG/Pd NPs reactor systems are readily reused/recycled after each use. As proof of this concept, the catalytic performance of the LCG/Pd NPs reactor system was demonstrated by the catalytic reduction of toxic heavy metal ions (Cr6+) and organic dye (methyl orange). Results showed that the novel LCG/Pd NPs reactor system exhibited much increased catalytic reduction rates: the pseudo-first-order rate constant (k) is 118 times higher (from 0.018 to 2.129 min−1 at 25 °C) for MO, and 38 times higher (from 0.008 to 0.304 min−1 at 25 °C) for Cr6+, in comparison with the control, under otherwise the same conditions.

Assembly of two trinuclear-cluster-based metal-organic frameworks: Structures and methanol electro-oxidation properties

The direct methanol fuel cell (DMFC) is an efficient and non-polluting green energy conversion device. However, the electrocatalysts for the anodic methanol oxidation reaction (MOR) in DMFC are often precious metal catalysts, which suffer from high cost, poor stability, and easy deactivation. In this work, two isostructural metal-organic frameworks (MOFs) [M3(μ3-OH)(TATB)(Nic)2(H2O)2(DMA)] (M = Co, Ni) were successfully synthesized under solvothermal conditions. Both frameworks possess a unique trinuclear cluster [M3(μ3-OH)(COO)5] secondary building unit (SBU) and a rare binodal (3,7)-connected network. Due to the high density of metal sites and prominent pore system within CTGU-36-Ni, it can serve as an effective molecular electrocatalyst for MOR, while CTGU-36-Co is an inert material. Further experimental results showed that the introduction of conductive substances could lead to a significant increase in the MOR area activity of CTGU-36-Ni. This work not only provides a non-noble metal molecular MOR electrocatalyst but also opens a new vision for the design and application of crystalline materials in various energy conversion processes.

In-situ groundwater treatment for arsenic removal: laboratory pilot scale study with 3-D tank packed porous media as subsurface

ABSTRACT The ex-situ treatment of arsenic is widely adopted; however, there are emerging concerns related to system maintenance, material replacement, and waste generation. There is a scope to explore in-situ arsenite [As (III)] remediation in the aquifers. The main objective of this study is to evaluate the performance of in-situ synthesised FeS in immobilising As (III) in the natural groundwater when transported through a three-dimensional (3-D) porous media system. In this study, a 3-D tank of 0.50 m × 0.30 m × 0.30 m (L × W × H) was packed with natural sand to represent the subsurface porous media system. The homogeneous packing and uniform flow were ensured before synthesising FeS in-situ, where a total of 1.5 pore volumes (PVs) of 20 mM sodium sulfide (Na2S) and 20 mM ferrous sulfate (FeSO4) reagent solutions were injected alternatively into the pre-saturated porous media. Finally, 300 ± 15 μg/L of As (III) spiked natural groundwater was passed through the porous media, and the samples were collected through several sampling ports for analysing for total As and Fe. The result suggests that the concentration of As (III) reaches below 11 μg/L within 644 min (4 PVs) of injection of reagents. Furthermore, almost 88.4% of As (III) get immobilised after passing 31 PVs of contaminated water. In brief, almost 406 L of As contaminated groundwater can be treated by injecting 21 L of reagents with a reagent-to-treated water ratio of 1:20.

Three‐dimensional stratigraphic architecture, secondary pore system development and the Middle Pleistocene transition, Sandy Point area, San Salvador Island, Bahamas

AbstractThe Bahamian Archipelago has been the subject of extensive studies of stratigraphy, carbonate island morphology and diagenetic overprinting for many decades. A recently‐acquired dataset comprised of high‐resolution light detection and ranging, tightly spaced cored boreholes with image logs, thin sections, porosity and permeability measurements, and isotopic geochemical analyses provides a unique opportunity to perform detailed sequence stratigraphic analysis. This multi‐faceted study first establishes a new high‐resolution sequence stratigraphic framework for the Sandy Point area of San Salvador Island, encompassing six unconformity bound sequences (exposure surfaces) representing varying lengths of missing time. The stratigraphically lowest sequence is Late Pliocene in age and is dominated by reef facies capped by an extensive laminar caliche that represents 1.5 million years of exposure. The overlying Early Pleistocene is split into two sequences, EP1 and EP2, which are both dominated by low‐energy subtidal facies. The upper three sequences are tied to the Marine Isotope Stage 11, 9 and 5e interglacials, and are distinctly different in facies composition and architecture, being dominated by higher energy facies distributed in a more complex mosaic. The new stratigraphic framework highlights significant changes in depositional style and facies architecture that can be linked to increasing sea‐level amplitude oscillations and greater climate gradient at the Mid Pleistocene Transition. The well‐constrained framework is then used to provide key context for observed complex diagenetic evolution through repeated sea‐level inundation and subaerial exposure. These results suggest that well‐developed subaerial exposure surfaces drive increases in non‐matrix features in the subsequent stratigraphic package following exposure as the well‐cemented exposure surface acts to concentrate fluid flow and dissolution. Integration of non‐matrix features within this framework highlights the importance of dissolution/cementation patterns on formation of these modified unconformity surfaces for focusing later meteoric diagenesis and creating enhanced fluid flow pathways for continued multicyclic diagenetic events.

Optimization of Piezoresistive Response of Elastomeric Porous Structures Based on Carbon-Based Hybrid Fillers Created by Selective Laser Sintering.

Recently, piezoresistive sensors made by 3D printing have gained considerable interest in the field of wearable electronics due to their ultralight nature, high compressibility, robustness, and excellent electromechanical properties. In this work, building on previous results on the Selective Laser Sintering (SLS) of porous systems based on thermoplastic polyurethane (TPU) and graphene (GE)/carbon nanotubes (MWCNT) as carbon conductive fillers, the effect of variables such as thickness, diameter, and porosity of 3D printed disks is thoroughly studied with the aim of optimizing their piezoresistive performance. The resulting system is a disk with a diameter of 13 mm and a thickness of 0.3 mm endowed with optimal reproducibility, sensitivity, and linearity of the electrical signal. Dynamic compressive strength tests conducted on the proposed 3D printed sensors reveal a linear piezoresistive response in the range of 0.1-2 N compressive load. In addition, the optimized system is characterized at a high load frequency (2 Hz), and the stability and sensitivity of the electrical signal are evaluated. Finally, an application test demonstrates the ability of this system to be used as a real-time wearable pressure sensor for applications in prosthetics, consumer products, and personalized health-monitoring systems.