Fluid Permeability Research Articles

Modelling of Fluid Permeability at the Interface of the Metal-to-Metal Sealing Surface

This paper presents a method for modelling the permeability of fluid at the interface formed between flat parallel plates and the sharp-edged ridges of a metal gasket. This work was divided into three stages. In the first stage, numerical calculations simulating the deformation (compression of the gasket) were performed. The calculations were carried out using thermomechanical static analysis with commercial software. The purpose of these calculations was to determine the contact area of the gasket ridges with the plates, the deformation of the gasket ridges, and the reaction force resulting from the degree of compression of the gasket. In the second part of this work, analytical calculations were performed to estimate the tightness level. The analytical model proposed in this paper was based on Darcy’s equation, simulating fluid flow through a ring-shaped porous layer. The analytical model also took into account the shape of the roughness profile of the sealed surfaces. A mathematical Ausloos–Berman function based on fractal theory was used to represent it. In the last part of this work, experimental tests were carried out to determine the actual fluid permeability and thus verify the numerical and analytical calculations.

Transcriptomic profiling of Schlemm’s canal cells reveals a lymphatic-biased identity and three major cell states

Schlemm’s canal (SC) is central in intraocular pressure regulation but requires much characterization. It has distinct inner and outer walls, each composed of Schlemm’s canal endothelial cells (SECs) with different morphologies and functions. Recent transcriptomic studies of the anterior segment added important knowledge, but were limited in power by SEC numbers or did not focus on SC. To gain a more comprehensive understanding of SC biology, we performed bulk RNA sequencing on C57BL/6 J SC, blood vessel, and lymphatic endothelial cells from limbal tissue (~4,500 SECs). We also analyzed mouse limbal tissues by single-cell and single-nucleus RNA sequencing (C57BL/6 J and 129/Sj strains), successfully sequencing 903 individual SECs. Together, these datasets confirm that SC has molecular characteristics of both blood and lymphatic endothelia with a lymphatic phenotype predominating. SECs are enriched in pathways that regulate cell-cell junction formation pointing to the importance of junctions in determining SC fluid permeability. Importantly, and for the first time, our analyses characterize three molecular classes of SECs, molecularly distinguishing inner wall from outer wall SECs and discovering two inner wall cell states that likely result from local environmental differences. Further, and based on ligand and receptor expression patterns, we document key interactions between SECs and cells of the adjacent trabecular meshwork (TM) drainage tissue. Also, we present cell type expression for a collection of human glaucoma genes. These data provide a new molecular foundation that will enable the functional dissection of key homeostatic processes mediated by SECs as well as the development of new glaucoma therapeutics.

Transcriptomic profiling of Schlemm's canal cells reveals a lymphatic-biased identity and three major cell states.

Schlemm's canal (SC) is central in intraocular pressure regulation but requires much characterization. It has distinct inner and outer walls, each composed of Schlemm's canal endothelial cells (SECs) with different morphologies and functions. Recent transcriptomic studies of the anterior segment added important knowledge, but were limited in power by SEC numbers or did not focus on SC. To gain a more comprehensive understanding of SC biology, we performed bulk RNA sequencing on C57BL/6 J SC, blood vessel, and lymphatic endothelial cells from limbal tissue (~4,500 SECs). We also analyzed mouse limbal tissues by single-cell and single-nucleus RNA sequencing (C57BL/6 J and 129/Sj strains), successfully sequencing 903 individual SECs. Together, these datasets confirm that SC has molecular characteristics of both blood and lymphatic endothelia with a lymphatic phenotype predominating. SECs are enriched in pathways that regulate cell-cell junction formation pointing to the importance of junctions in determining SC fluid permeability. Importantly, and for the first time, our analyses characterize three molecular classes of SECs, molecularly distinguishing inner wall from outer wall SECs and discovering two inner wall cell states that likely result from local environmental differences. Further, and based on ligand and receptor expression patterns, we document key interactions between SECs and cells of the adjacent trabecular meshwork (TM) drainage tissue. Also, we present cell type expression for a collection of human glaucoma genes. These data provide a new molecular foundation that will enable the functional dissection of key homeostatic processes mediated by SECs as well as the development of new glaucoma therapeutics.

Emerging magnetic-responsive hydrogel actuators with anisotropic shape for intracardiovascular directional motion

A magnetically responsive valve actuator inspired by the starfish shape and fabricated with hydrophilic and hydrophobic surfaces was developed. The surface morphology and wettability of the magnetically responsive colloidal crystal hydrogel actuator were characterized using scanning electron microscopy and contact angle measurements. The actuator, resembling a flower, consists of Poly(HEMA-co-AAm)/Fe3O4/PDMS, exhibiting distinct Janus wettability with hydrophobic Fe3O4/PDMS and hydrophilic Poly(HEMA-co-AAm) surfaces. The directional movement of water droplets on the V-shaped structured film confirmed the anisotropic wetting behavior, influenced by the film’s wettability and structural dimensions. Moreover, the actuator demonstrated responsive angular and positional adjustments under varying magnetic fields, facilitated by embedded Fe3O4 particles aligning with magnetic lines of force. In experimental setups simulating intravascular applications, the actuator exhibited controlled movement within tubes and demonstrated effective adhesion to heart valve injuries under magnetic guidance. Additionally, a layered inverse opal film within the actuator showed promising capabilities for unidirectional fluid permeation, enhancing its functional versatility. These findings underscore the potential of the magnetically responsive colloidal crystal hydrogel actuator for biomedical applications, particularly in minimally invasive cardiac interventions requiring precise actuation and adhesive functionalities.

Computational influences of convection micropolar fluid influx and permeability on characteristics of heating rate and skin friction over vertical plate

This manuscript merits at examining of an embedded orthogonal plate inside porous domain exposed to uniform heat influx to elaborate on how micro polar fluid factors and permeability characteristic affect the local skin friction, heating rate, and angular velocity inside boundary layer. The plate is subjected to forced convective micro polar fluid influx under steady, incompressible, and viscous circumstances. To facilitate dependable numerical solution, similarity approach is implemented to mutate set of coupled governing equations relevant to the adopted study into a constrained dimensionless differential equations. Computational analysis has been executed hiring Runge-Kutta scheme by Matlab function bvp4c to settle the governing equations. Study's results are highlighted graphically the impact of micro polar fluid factors on the local skin friction, heating rate, and angular velocity curves. High degree of acceptability of present findings compare with prior research results. It is found that the rising of Darcy parameter drives to decrease linearly both heating rate and local skin friction. Among the examined factors, the benchmark parameter of decreasing skin friction is the porosity. Additionally, it is found that an increasing of Prandtl number and micro rotation element lead to enhance Nusselt number. Once curves of micro rotation are interfered at certain distance from the plate due to increase in porosity, Darcy, Forchheimer's, and microelement rotation, the micro rotation curves are inverted.

Physical properties of industrially produced carbon nanotube yarns for use in structural nanocomposites

Industrially-produced carbon nanotube (CNT) networks are a promising base for high-performance, continuous CNT nanocomposites, motivating widespread use in research and application development. Floating catalyst chemical vapor deposition (FCCVD) is a scalable, widely-adopted approach for synthesis of CNT networks; however, FCCVD can yield networks with organic impurities which complicate their characterization and processing. Herein, we analyze two varieties of FCCVD-synthesized commercial CNT yarn to explore the effects of densification and purification as they relate to forming infiltrated polymer composites. First, the fluid permeabilities and porosities of neat roving and chemically-stretched CNT yarns (CSYs) are estimated and compared to gas adsorption studies, which suggest high-tenacity CSYs are largely impermeable, leading to dry-core composites when polymer infiltration is attempted. Next, the presence and effects of oxygen-rich amorphous carbon impurities in the CSYs are identified and found to exist at the scale of CNT bundles, wherein the amorphous carbon behaves like a hygroscopic polymer matrix in a composite. Removal of the amorphous carbon phase in a 130%-increase in specific surface area, as quantified by BET analysis, and a statistically significant reduction in tensile properties. We discuss challenges in estimating yarn alignment and crystallinity resulting from these factors, and place our results in context of past studies analyzing intrinsic organic coatings in FCCVD-synthesized CNT networks.

Fractal permeability model for power-law fluids in embedded tree-like branching networks based on the fractional-derivative theory

The investigation of permeability in tree-like branching networks has attracted widespread attention. However, most studies about fractal models for predicting permeability in tree-like branching networks include empirical constants. This paper investigates the flow characteristics of power-law fluids in the dual porosity model of porous media in embedded tree-like branching networks. Considering the inherent properties of power-law fluids, non-Newtonian behavior effects, and fractal properties of porous media, a power-law fluids rheological equation is introduced based on the fractional-derivative theory and fractal theory. Then, an analytical formula for predicting the effective permeability of power-law fluids in dual porous media is derived. This analytical formula indicates the influences of fractal dimensions and structural parameters on permeability. With increasing length ratio, bifurcation series, and bifurcation angle, as well as decreasing power-law exponent and diameter ratio, the effective permeability decreases to varying degrees. The derived analytical model does not include empirical constants and is consistent with the non-Newtonian properties of power-law fluids, indicating that the model is an effective method for describing the flow process of complex non-Newtonian fluids in porous media in natural systems and engineering. Therefore, this study is of great significance to derive analytical solutions for the permeability of power-law fluids in embedded tree-like bifurcation networks.

Transcriptomic profiling of Schlemm's canal cells reveals a lymphatic-biased identity and three major cell states.

Schlemm's canal (SC) is central in intraocular pressure regulation but requires much characterization. It has distinct inner and outer walls, each composed of Schlemm's canal endothelial cells (SECs) with different morphologies and functions. Recent transcriptomic studies of the anterior segment added important knowledge, but were limited in power by SEC numbers or did not focus on SC. To gain a more comprehensive understanding of SC biology, we performed bulk RNA sequencing on C57BL/6J SC, blood vessel, and lymphatic endothelial cells from limbal tissue (~4500 SECs). We also analyzed mouse limbal tissues by single-cell and single-nucleus RNA sequencing (C57BL/6J and 129/Sj strains), successfully sequencing 903 individual SECs. Together, these datasets confirm that SC has molecular characteristics of both blood and lymphatic endothelia with a lymphatic phenotype predominating. SECs are enriched in pathways that regulate cell-cell junction formation pointing to the importance of junctions in determining SC fluid permeability. Importantly, and for the first time, our analyses characterize 3 molecular classes of SECs, molecularly distinguishing inner wall from outer wall SECs and discovering two inner wall cell states that likely result from local environmental differences. Further, and based on ligand and receptor expression patterns, we document key interactions between SECs and cells of the adjacent trabecular meshwork (TM) drainage tissue. Also, we present cell type expression for a collection of human glaucoma genes. These data provide a new molecular foundation that will enable the functional dissection of key homeostatic processes mediated by SECs as well as the development of new glaucoma therapeutics.

Fractal study on the permeability of power-law fluid in a rough and damaged tree-like branching network

Fractal study on the permeability of power-law fluid in a rough and damaged tree-like branching network

Rapid and Controllable Multilayer Cell Sheet Assembly via Biodegradable Nanochannel Membranes

AbstractThe ability to precisely arrange and control the assembly of diverse cell types into intricate 3D structures remains a critical challenge in tissue engineering. Herein, a versatile and programmable 3D cell sheet assembly is described technology by developing a biodegradable nanochannel (BNC) membrane to fulfill this unmet need. This membrane, hierarchically assembled from 2D nanomaterial aggregates, exhibits both exceptional fluid permeability and rapid biodegradation under physiological conditions. The unique properties of the BNC membrane enable precise spatial and temporal control over cell assembly, facilitating the creation of complex 3D cellular architectures. The BNC membrane is integrated with a programmable negative‐pressure‐based cell assembly strategy to form single and multicellular 3D sheets in a highly controllable manner. To demonstrate the feasibility and translatability of this technology in the field of tissue engineering approaches to screen stem cell‐derived therapeutics with “core–shell” macrophage‐fibroblast multicellular patterns and treat murine diabetic skin wounds via scaffold‐free 3D adipose‐derived mesenchymal stem cell (ADMSC) sheets are devised. In summary, the results demonstrate that the BNC membrane‐based 3D cell sheet assembly approach significantly advances current tissue engineering capabilities, offering substantial potential for both regenerative medicine applications and the development of physiologically relevant disease models.

Microstructural and transport characteristics of triply periodic bicontinuous materials

Three-dimensional (3D) bicontinuous two-phase materials are increasingly gaining interest because of their unique multifunctional characteristics and advancements in techniques to fabricate them. Because of their complex topological and structural properties, it still has been nontrivial to develop explicit microstructure-dependent formulas to predict accurately their physical properties. A primary goal of the present paper is to ascertain various microstructural and transport characteristics of five different models of triply periodic bicontinuous porous materials at a porosity ϕ1=1/2: those in which the two-phase interfaces are the Schwarz P, Schwarz D and Schoen G minimal surfaces as well as two different pore-channel structures. We ascertain their spectral densities, pore-size distribution functions, local volume-fraction variances, and hyperuniformity order metrics and then use this information to estimate certain effective steady-state as well as time-dependent transport properties via closed-form microstructure–property formulas. Specifically, the recently introduced time-dependent diffusion spreadability is determined exactly from the spectral density. Moreover, we accurately estimate the fluid permeability of such porous materials from a closed-form formula that depends on the second moment of the pore-size function and the formation factor, a measure of the tortuosity of the pore space, which is exactly obtained for the three minimal-surface structures. We also rigorously bound the permeability from above using the spectral density. For the five models with identical cubic unit cells, we find that the permeability, inverse of the specific surface, hyperuniformity order metric, pore-size second moment and long-time spreadability behavior are all positively correlated and rank order the structures in exactly the same way. We also conjecture what structures maximize the fluid permeability for arbitrary porosities and show that this conjecture must be true in the extreme porosity limits by identifying the corresponding optimal structures.

A Fractal Model of Fracture Permeability Considering Morphology and Spatial Distribution

Summary In fractured reservoirs, the fracture system is considered to be the main channel for fluid flow. To better investigate the impacts of fracture morphology (tortuosity and roughness) and spatial distribution on the flow capacity, a fractal model of fracture permeability was developed. Based on micro-computed tomography (CT) images, the 3D structure of the fracture was reconstructed, and the fractal characteristics were systematically analyzed. Finally, the control of permeability by fracture morphology and spatial distribution in different fractured reservoirs was identified. The results demonstrate that the complexity of the fracture distribution in 2D slices can represent the nature of the fracture distribution in 3D space. The permeability fractal prediction model was developed based on porosity (φ), spatial distribution fractal dimension (Df), tortuosity fractal dimension (DT), and opening fractal dimension of the maximum width fracture (Db). The permeability prediction results of the fractal model for Samples L-01 (limestone), BD-01 (coal), BD-02 (coal), S-01 (sandstone), M-01 (mudstone), and C-01 (coal) are 0.011 md, 0.239 md, 0.134 md, 0.119 md, 1.429 md, and 27.444 md, respectively. For different types of rocks, the results predicted by the model show good agreement with numerical simulations (with an average relative error of 2.51%). The factors controlling the permeability of fractured reservoirs were analyzed through the application of the mathematical model. The permeability is positively exponentially correlated with the fractal dimension of spatial distribution and negatively exponentially correlated with the fractal dimension of morphology. When Df < 2.25, the fracture spatial structure is simple, and the morphology and spatial distribution jointly control the seepage capacity of fractured reservoirs. When Df > 2.25, the fracture spatial structure is complex, and the impact of morphology on seepage capacity can be disregarded. This work can effectively lay the foundation for the study of fluid permeability in fractured reservoirs by investigating the effects of fracture morphology (tortuosity and roughness) and spatial distribution on flow capacity.

Radial basis kernel harmony in neural networks for the analysis of MHD Williamson nanofluid flow with thermal radiation and chemical reaction: An evolutionary approach

The current investigative exploration exemplifies the conceptualization of a novel design intelligent computing paradigm based on artificial neural networks (ANNs) by utilizing radial basis function (RBF) to analyze magnetohydrodynamic (MHD) Williamson nanofluid two-dimensional flow along a stretchable sheet under the effect of chemical reaction as well as thermal radiation in a porous medium. This newly designed technique is an amalgam of a well-known reliable global solver named genetic algorithms (GAs) and a swift convergence generated local solver named sequential quadratic programming (SQP) used in ANNs by taking RBF as a kernel function i.e. ANNs-RBF-GASQP solver. The PDEs demonstrating the current nanofluid problem flow are transformed into the system of non-linear ODEs through a relevant similarity transformation and subsequently solved using ANNs-RBF-GASQP solver to investigate thermohydraulic properties by manipulating the values of various system parameters present in the ODEs. Moreover, the simulation results show that increasing the heat source parameter leads to a significant decrease in temperature. Additionally, an increase in the porosity parameter causes a decrease in the velocity of nanofluid, as a higher value of porosity increases fluid permeability and greater resistance to flow. The efficacy of the suggested solver is scrutinized through various statistical and convergence analyses.

A Reverse Nonequilibrium Molecular Dynamics Algorithm for Coupled Mass and Heat Transport in Mixtures.

We present a new method for introducing stable nonequilibrium concentration gradients in molecular dynamics simulations of mixtures. This method extends earlier reverse nonequilibrium molecular dynamics (RNEMD) methods, which use kinetic energy scaling moves to create temperature or velocity gradients. In the new scaled particle flux (SPF-RNEMD) algorithm, energies and forces are computed simultaneously for a molecule existing in two nonadjacent regions of a simulation box, and the system evolves under a linear combination of these interactions. A continuously increasing particle scaling variable is responsible for the migration of the molecule between the regions as the simulation progresses, allowing for simulations under an applied particle flux. To test the method, we investigate diffusivity in mixtures of identical but distinguishable particles and in a simple mixture of multiple Lennard-Jones particles. The resulting concentration gradients provide Fick diffusion constants for mixtures. We also discuss using the new method to obtain coupled transport properties using simultaneous particle and thermal fluxes to compute the temperature dependence of the diffusion coefficient and activation energies for diffusion from a single simulation. Lastly, we demonstrate the use of this new method in interfacial systems by computing the diffusive permeability of a molecular fluid moving through a nanoporous graphene membrane.

Investigating the vaporization mechanism's effect on interfacial tension during gas injection into an oil reservoir

In gas injection, which is one of the fascinating enhanced oil recovery techniques, the main mechanism involves decreasing interfacial tension (IFT). Although various mechanisms can affect the IFT of a system, in most experimental and numerical studies, condensation is considered the dominant mechanism among condensation-vaporization and vaporization. Investigating the impact of each mechanism is crucial as they can influence the IFT of the system and, consequently, the effectiveness of the gas injection method. This study introduces a novel model to assess the influence of different mechanisms on system IFT. The model defines system IFT, adjusts fluid relative permeability to represent miscible, immiscible, and near-miscible states, and utilizes the Buckley–Leverett method to analyze gas fractional flow and saturation profiles when injecting carbon dioxide (CO2), methane (CH4), and nitrogen (N2). Furthermore, the research explores the impact of injection pressure and IFT at minimum miscible pressure (IFT0) on gas injection efficiency. Based on our results, for both live and dead oil, the condensation mechanism reduces IFT and near-miscible pressure; switching to a condensing-vaporizing mechanism increases these parameters. This trend was consistent across all gases studied (N2, CO2, CH4), with a more significant effect observed on the CH4-live oil system compared to N2 and CO2. Controlling the condensing mechanism in IFT measurements enhances gas flow rate and relative permeability curve within the medium. Higher injection pressure in the condensing mechanism and IFT0 = 0.5 leads to faster fluid movement and improved relative permeability due to increased driving forces. Higher IFT0 accelerates the relative permeability of fluids and gas movement within the medium by promoting miscibility sooner. The impact of IFT0 was more pronounced on the dead oil–gas system compared to the live oil–gas system in this study.

Hyperuniformity classes of quasiperiodic tilings via diffusion spreadability.

Hyperuniform point patterns can be classified by the hyperuniformity scaling exponent α>0, that characterizes the power-law scaling behavior of the structure factor S(k) as a function of wave number k≡|k| in the vicinity of the origin, e.g., S(k)∼|k|^{α} in cases where S(k) varies continuously with k as k→0. In this paper, we show that the spreadability is an effective method for determining α for quasiperiodic systems where S(k) is discontinuous and consists of a dense set of Bragg peaks. It has been shown in [Phys. Rev. E 104, 054102 (2021)10.1103/PhysRevE.104.054102] that, for media with finite α, the long-time behavior of the excess spreadability S(∞)-S(t) can be fit to a power law of the form t^{-(d-α)/2}, where d is the space dimension, to accurately extract α for the continuous case. We first transform quasiperiodic and limit-periodic point patterns into two-phase media by mapping them onto packings of identical nonoverlapping disks, where space interior to the disks represents one phase and the space in exterior to them represents the second phase. We then compute the spectral density χ[over ̃]_{_{V}}(k) of the packings, and finally compute and fit the long-time behavior of their excess spreadabilities. Specifically, we show that the excess spreadability can be used to accurately extract α for the one-dimensional (1D) limit-periodic period-doubling chain (α=1) and the 1D quasicrystalline Fibonacci chain (α=3) to within 0.02% of the analytically known exact results. Moreover, we obtain a value of α=5.97±0.06 for the two-dimensional Penrose tiling and present plausible theoretical arguments strongly suggesting that α is exactly equal to six. We also show that, due to the self-similarity of the structures examined here, one can truncate the small-k region of the scattering information used to compute the spreadability and obtain an accurate value of α, with a small deviation from the untruncated case that decreases as the system size increases. This strongly suggests that one can obtain a good estimate of α for an infinite self-similar quasicrystal from a modestly sized finite sample. The methods described here offer a simple and general procedure to characterize accurately the large-scale translational order present in quasicrystalline and limit-periodic media in any space dimension that are self-similar. Moreover, the scattering information extracted from these two-phase media encoded in χ[over ̃]_{_{V}}(k), can be used to estimate their physical properties, such as their effective dynamic dielectric constants, effective dynamic elastic constants, and fluid permeabilities.

Relationship between the Nonuniformity of Packed Structure and Fluid Permeability in a Model Scrap Preheating Vessel

Relationship between the Nonuniformity of Packed Structure and Fluid Permeability in a Model Scrap Preheating Vessel

Numerical modeling and performance analysis of anode with porous structure for aluminum-air batteries

Aluminium-air batteries have been considered as one of the most promising next-generation energy storage devices. In this work, based on COMSOL Multiphysics, we firstly explored the effect of 3D pore size structure change on the permeation performance of the solution. The results showed that enhancing the permeation stroke of permeable solutions was beneficial to expanding the electrode reaction contact area, but it would reduce the permeation and corrosion resistance effects. For this reason, we further carried out a secondary study of TPMS structure on fluid permeation and its electrochemical performance based on the TPMS structure modelling mechanism. The results showed that the TPMS structure possessed both good solution permeation reaction rate and good corrosion resistance. Additionally, in order to further verify the validity of the simulation data, we carried out the validation of the self-corrosion rate, discharge properties, and electrochemical properties. From the final data, the discharge voltage of the TPMS structure was only 1.43 V, but its corrosion current and polarisation impedance were 2.207 × 10−2 A/cm2 and 2.2 Ω∙cm2, respectively. At the same time, the structure also had good solution permeability. Therefore the porous anode structure design for aluminium-air batteries in three-dimensional state is preferred.

Characteristics of the Antitumor Effect of Doxorubicin and Pegylated Hyaluronidase on Models of Rat Brain Tumors.

Hyaluronidase increases tissue permeability and diffusion of the extracellular fluid by cleaving hyaluronan, the primary component of the extracellular matrix. Hyaluronidase pegylation (Hyal-PEG) decreases its clearance and enhances biodistribution. The pro- and anticancer activity of Hyal-PEG and a combination of Hyal-PEG with doxorubicin were studied in vitro (morphological analysis of rat glioblastoma 101.8 spheroids) and in vivo (by the survival time of rats after intracerebral transplantation of the tumor and morphological analysis). In the presence of doxorubicin and Hyal-PEG in the culture medium in vitro, spheroids lost their ability to adhere to the substrate and disintegrate into individual cells. Intracerebral transplantation of the tumor tissue with Hyal-PEG did not accelerate glioblastoma growth. The mean survival time for animals receiving transplantation of the tumor alone and in combination with Hyal-PEG was 13 and 20 days, respectively. In one rat with transplanted tumor and Hyal-PEG, this parameter increased by 53%. The survival time of rats receiving systemic therapy with doxorubicin and Hyal-PEG significantly increased (p=0.003). Antitumor effect of therapeutic doses of doxorubicin combined with Hyal-PEG was demonstrated on the model of rat glioblastoma 101.8 in vitro. Hyal-PEG inhibited adhesion of tumor cells, but did not cause their death. Transplantation of Hyal-PEG-treated tumor did not reduce animal survival time. Systemic administration of therapeutic doses of doxorubicin with Hyal-PEG increased survival time of rats with glioblastoma 101.8.

Investigation of pore structure evolution and damage characteristics of high temperature rocks subjected to liquid nitrogen cooling shock

Liquid nitrogen (LN2) can be utilized in the development of enhanced geothermal systems, as well as for deep/ultra-deep hydrocarbon reservoir stimulation, fire suppression, and other high-temperature geological projects. It is a crucial issue in the utilization of LN2 to investigate the pore structure evolution, permeability, and damage characteristics of high-temperature rocks under the influence of LN2 cooling shock. These rocks were first slowly heated to 150∼600°C and held for 2 h, followed by LN2 or natural cooling. The evolution of pore volume in high-temperature rocks affected by liquid nitrogen cooling was quantified. T2 cutoff values were determined through centrifugal tests, while the contents of irreducible and mobile fluids were estimated. Based on the aforementioned analysis as well as changes in irreducible fluid saturation, pore throat, tortuosity, and permeability, this study examines the closure and development of pores along with permeability behavior. The findings suggest that, despite a more pronounced decrease in porosity at lower heating temperatures, LN2 cooling specimens exhibit superior pore connectivity and permeability compared to those cooled naturally. LN2 stimulation not only induces crack initiation and propagation but also results in further cooling induced densification based on heating densification. 225°C is considered to be the optimal temperature for cooling contraction induced densification in this study. At higher heating temperatures, the damage to rock cooled with LN2 is more severe than that of naturally cooled. This results in a greater increase in porosity, movable fluid content and proportion, and permeability of LN2 cooled specimens compared to naturally cooled specimens. The damage mechanism can be better understood by the constructed damage model that coordinates the pore increase/decrease and mutual pore transformation from the perspective of pore evolution.