Pore Level Research Articles

New insights into hierarchical pore size and level of concentration in efficient removal of toluene vapor by activated carbon

The hierarchical pore structure of nanoporous carbon and gaseous toluene concentration co-mediated adsorption mechanism was examined. The KOH-activated carbons with tailorable high surface area (1126–3148 m2/g), large pore volume (0.446–2.08 cm3/g) and broadening average pore width (0.873–2.68 nm) were prepared. Dynamic adsorption was used to determine breakthrough curves and adsorption isotherms of toluene by as-prepared KOH-activated carbons and commercial activated carbons. The experimental results showed that the breakthrough time is positively correlated with ultramicropore volume of all activated carbons. The equilibrium amounts adsorbed (qe) for toluene at 100 ppmv were as high as 454 mg/g on KOH-activated carbons. The qe for toluene at P/P0 < 0.017 dominated by ultramicropore volume of all activated carbons were attributed to the enhanced superposition of adsorption force field between adjacent ultramicropore walls. A large adsorption affinity is imperative to achieve high amounts adsorbed for toluene at low concentration. The toluene was firstly filled in ultramicropores then gradually occupied in wide micropores at 0.017 <P/P0 < 0.1 and the qe were linearly correlated with micropore volume. The qe of toluene at P/P0 > 0.1 were linearly correlated with volume of micropore and small mesopore. The governing porosity in adsorbing toluene is varied with the intruding concentration. These results provided new insights into adsorption mechanism and development of novel materials.

Characterization of Residual Oil Distribution in Sandstone by NMR: A Microscopic View on Oil Recovery by Miscible CO2 Flooding

Abstract Miscible CO2 flooding gains rising popularity due to high displacement efficiency and potential carbon negativity. It is well documented that pore-level heterogeneity is one of the dominant mechanisms responsible for the variation in oil recovery efficiencies of miscible CO2 flooding. However, owing to a lack of understanding of miscible CO2 displacement behaviors at pore level, quantitative analysis of the mechanisms for the influence of pore-level heterogeneity on the oil recovery efficiency of miscible CO2 flooding remains problematical. Recently, NMR has been widely used to investigate microscopic residual oil distribution and pore-level displacement behaviors of various agents. Nevertheless, current NMR-based methods for determining microscopic residual oil distribution require the use of fluorinated oil, Mn2+ solution, or heavy water for eliminating the mutual interference of oil and water NMR signals. The differences in properties of reservoir fluids and additional agents could give rise to the change in displacement characteristics and consequently affect the analysis results on pore-level displacement behaviors. In this study, a method to determine microscopic residual oil distribution in sandstone during gas floodings based on NMR T2 spectrum without additional agents except reservoir fluids is proposed. Using the method, we can avoid the possible changes in the displacement characteristics caused by additional agents. Miscible CO2 flooding experiments are conducted with ultra-low and extra-low permeability cores. The T2 spectra of cores before and after flooding are measured using a 23 MHz low-field NMR instrument. Residual oil distributions in cores are quantitatively characterized using the proposed method, and then, oil recovery efficiencies from different-sized pore throats are evaluated. It is found that for both cores about 60% of the residual oil is distributed in pore throats with &amp;lt;0.26 μm radius. Oil residing in pore throats with &amp;gt;0.03 μm radius is displaceable for miscible CO2 flooding, which indicates that the thickness of the raffinate layer in the pore should be less than 0.015 μm. More than 30% of the residual oil is distributed in unswept areas, and thus, the sweep efficiency improvement is expected to effectively enhance the oil recovery of miscible CO2 flooding. The sweep efficiency is negatively affected by the pore-size heterogeneity. For the ultra-low and extra-low permeability cores, the standard deviation of pore size is 0.39 and 1.15, respectively, and correspondingly, the sweep efficiency is 84.33% and 72.84%, respectively. In the core, the oil recovery efficiencies from swept pore throats with &amp;lt;3 μm radius are similar and exceed 50%. Pore throats with &amp;gt;3 μm radius can form a preferred flow path, which will significantly reduce the oil displacement efficiency from swept pore throats with &amp;lt;3 μm radius. The findings of this study can help for better understanding of the microscopic CO2 miscible displacement behaviors and the mechanisms for the influence of pore-level heterogeneity on the oil recovery efficiency of miscible CO2 flooding.

Fabrications and Applications of Micro/Nanofluidics in Oil and Gas Recovery: A Comprehensive Review

Understanding fluid flow characteristics in porous medium, which determines the development of oil and gas oilfields, has been a significant research subject for decades. Although using core samples is still essential, micro/nanofluidics have been attracting increasing attention in oil recovery fields since it offers direct visualization and quantification of fluid flow at the pore level. This work provides the latest techniques and development history of micro/nanofluidics in oil and gas recovery by summarizing and discussing the fabrication methods, materials and corresponding applications. Compared with other reviews of micro/nanofluidics, this comprehensive review is in the perspective of solving specific issues in oil and gas industry, including fluid characterization, multiphase fluid flow, enhanced oil recovery mechanisms, and fluid flow in nano-scale porous media of unconventional reservoirs, by covering most of the representative visible studies using micro/nanomodels. Finally, we present the challenges of applying micro/nanomodels and future research directions based on the work.

Structural basis for cannabinoid-induced potentiation of alpha1-glycine receptors in lipid nanodiscs

Nociception and motor coordination are critically governed by glycine receptor (GlyR) function at inhibitory synapses. Consequentially, GlyRs are attractive targets in the management of chronic pain and in the treatment of several neurological disorders. High-resolution mechanistic details of GlyR function and its modulation are just emerging. While it has been known that cannabinoids such as Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent in marijuana, potentiate GlyR in the therapeutically relevant concentration range, the molecular mechanism underlying this effect is still not understood. Here, we present Cryo-EM structures of full-length GlyR reconstituted into lipid nanodisc in complex with THC under varying concentrations of glycine. The GlyR-THC complexes are captured in multiple conformational states that reveal the basis for THC-mediated potentiation, manifested as different extents of opening at the level of the channel pore. Taken together, these structural findings, combined with molecular dynamics simulations and functional analysis, provide insights into the potential THC binding site and the allosteric coupling to the channel pore.

RSM Based Process Variables Optimization of Restructured Fish Meat

ABSTRACT The present study aimed to develop a ready-to-eat restructured European sea bass (Dicentrarchus labrax) meat product. The response variables have been addressed as a function of MTGase addition (0, 0.16, 0.32%), pressure weight (0, 2.54, 5.09 gf/cm2), and setting time (4, 14, 24 h) at 4°C to restructured fish meat using response surface methodology (RSM) based design of experiments. The optimizing process was characterized by using two physical (deviation in diameter, pore) and two sensorial (appearance, texture) analyses. In addition to image processing and sensory analysis, microbiological quality, water activity, pH value, and variations after heat application were examined. The use of MTGase and pressure weight combination improved textural properties and sensory results. The RSM study demonstrated that 17.72 hours of setting time, 3.46 gf/cm2 of pressure weight, and 0.30% MTGase were the optimal parameters of restructured fish meat product. Optimum product results were statistically matched with the solutions; pore level: %0.89±0.01, deviation in diameter: %1.94±0.00, appearance: 8.55±0.07, and texture: 8.45±0.05. These results were also supported by microstructure findings and other quality parameters. The restructured fish product that meets with the positive appreciation of the consumer can be improved by adding spices, forming different shapes, and available for commercial production.

Pore-level structural optimization of porous foams for enhancing heat transfer and reducing pressure drop simultaneously

In this work, the structure of porous foams is optimized for enhancing heat transfer and reducing pressure drop simultaneously at pore level. The optimization model consists of the pyoptsparse package integrates with an adjoint method. The flow and heat transfer characteristics are compared between the original and optimized foams. The influence of the inlet velocity (uin = 0.2, 1.0 and 5.0 m/s) on optimization is first analyzed. The results show that the pressure drop is significantly reduced, and the maximum decrease of the pressure drop is over 27% after optimization. For the heat transfer enhancement, when the inlet velocity of the fluid is low, the effect of optimization is slight due to the saturation of heat transfer; when the inlet velocity is high, the heat transfer enhancement is obvious, and the maximum increase of the outlet dimensionless temperature is over 12%. Finally, the effect of the porosity on optimization is analyzed, and the results indicate, it is easy to achieve significant pressure drop reduction for all porosities, and heat transfer enhancement can be only achieved for higher inlet velocity. The present work can provide useful guidance for improving the performance of porous materials in thermal applications.

Morphological analysis of porosity and sound absorption in sustainable materials from rice husk

This study proposes a composite material that incorporates rice husk. This research focuses on an experimental analysis of the physical, mechanical and acoustic performance of composite materials made of rice-husk waste. Various ratios of rice husk/resins have been employed. Complementary, X-ray computed tomography technique has been used to characterise a representative and extensive volume of material at the pore level, ranging from pore sizes of 100 μm to several millimetres Furthermore, detailed information of key factors of pore properties inside the matrix (pore size, sphericity, position, tortuosity and permeability) has been provided. All the compositions present high sound-absorption coefficients, with noise-reduction coefficients ranging from 0.39 to 0.52, and suitable compressive strength (&gt;1 MPa). From the results, when the rice husk/resin ratio was decreased, the pore size fell between 1 and 4 mm, and the permeability reduced; in contrast, the compressive strength increased, although the sound absorption capacity diminished.

Modelling articular cartilage: the relative motion of two adjacent poroviscoelastic layers.

In skeletal joints two layers of adjacent cartilage are often in relative motion. The individual cartilage layers are often modelled as a poroviscoelastic material. To model the relative motion, noting the separation of scales between the pore level and the macroscale, a homogenization based on multiple scale asymptotic analysis has been used in this study to derive a macroscale model for the relative translation of two poroviscoelastic layers separated by a very thin layer of fluid. In particular the fluid layer thickness is essentially zero at the macroscale so that the two poroviscoelastic layers are effectively in contact and their interaction is captured in the derived model via a set of interfacial conditions, including a generalization of the Beavers-Joseph condition at the interface between a viscous fluid and a porous medium. In the simplifying context of a uniform geometry, constant fixed charge density, a Newtonian interstitial fluid and a viscoelastic scaffold, modelled via finite deformation theory, we present preliminary simulations that may be used to highlight predictions for how oscillatory relative movement of cartilage under load influences the peak force the cartilage experiences and the extent of the associated deformations. In addition to highlighting such cartilage mechanics, the systematic derivation of the macroscale models will enable the study of how nanoscale cartilage physics, such as the swelling pressure induced by fixed charges, manifests in cartilage mechanics at much higher lengthscales.

Conductivity and permeability of graphite foams: Analytical modelling and pore-scale simulation

Graphite foams with excellent effective thermal conductivity and large surface area have primarily constituted a new area for the emerging fields of energy conversion, conservation, and management, potentially crucial for reaching the goals of carbon neutrality and emission peak. For such energy applications, graphite foam's thermal conductivity and permeability pave the physical foundation for understanding, designing, and operating thermofluidic flows inside the porous medium. However, previous prediction models of conductivity and permeability seldomly considered the effects of random distributions of pore shape and size intrinsically induced during processing of the graphite foam. To rectify this problem, analytical models of permeability and effective thermal conductivity for graphite foam are derived based on fractal theory, being duly accounted for random distributions of pore shape and size. In parallel, pore-scale numerical simulations are carried out, providing cross-validation and shedding light on transport mechanisms at pore level. Analytical model predictions and numerical simulation results are compared with existing experimental data. Results revealed that fractal analytical models accurately predicted the permeability and conductivity of graphite foams in a porosity range from 0.686 to 0.918, with different parent ligament materials and filling fluids (e.g., air and paraffin wax).

Pore level foam generation in the presence of residual oil in porous media

CO2 sequestration into depleted oil and gas reservoirs is gaining traction as one of the enablers of the energy transition. Foaming the injected CO2 has the potential to increase the amount of trapped CO2 in the porous medium. In this paper, we study the effect of trapped, emulsified oil on the requirement for the geometrical criterion for Roof snap-off in a porous medium. We extend an existing hydrodynamic pore-level model to describe the wetting-liquid accumulation in an appropriately-sized pore in the presence of oil. The effect of oil on liquid flow is simulated by adjusting the pore shape to be asymmetrical as observed in microfluidic experiments with residual oil. We alter the boundary and initial conditions of the problem to test various scenarios. Specifically, four cases are presented. The liquid accumulation is presented when the amount of wetting liquid volume connected to the pore is altered through changing the boundary conditions (cases 1 and 2). Moreover, the effect of drier surrounding medium and/or drier pores is also tested by increasing either the capillary pressure surrounding the pore or the capillary pressure of the pore itself (cases 3 and 4). We find that the presence of residual oil affects the liquid accumulation times when there is no external liquid pressure gradient applied. Additionally, residual oil presence makes the Roof snap-off criterion for liquid accumulation stricter. That is, the size of pore constrictions that allow snap off, as gauged by the ratio of throat to body size, decreases. To augment our pore-level study, we use a statistical pore network to observe the effect of the microscopic changes observed in our pore-level model macroscopically. Our results indicate that a stricter Roof snap-off criterion leads to fewer germination sites for lamellae generation. Our pore network analysis computes the generation rate constant to be as much as four times larger in the absence of oil than in its presence. Results suggest that changes to the shape of pore constrictions by emulsified oil reduce the effectiveness of foam generation.

Three-dimensional high-resolution image inversion and pore level CFD characterisation of effective thermal conductivity of replicated microcellular structures

Metallic-based microcellular structures are widely used in heat and mass transfer processes owing to their unique combination of high porosity, high surface area, fixed pore morphology and high Young modulus, enabling their suitability as heat pipes in oil and gas processing equipment, biomedical materials for bone repair and bone substitution, solar collectors, fuel cells, impact loading, soundproofing materials and metallurgical processing. Accurate representation of the effective thermal conductivity of these materials is imperative in understanding their heat transfer mechanisms leading to the design and optimisation of system performance. Due to the limited availability of experimental and predictive data on heat transport phenomena across the interstices of low-porosity microcellular structures - numerically simulated data of effective thermal conductivity for conduction heat transfer in metal foam-fluid systems have been compared for structures typified by near-circular pore walls and openings, i.e. “bottleneck-type” structures and foam porosity ranging between 0.65 and 0.78. A three-dimensional high-resolution image inversion and computational fluid dynamics modelling and simulation of conductive heat transfer for both the fluid and solid domains at pore level is used to estimate effective thermal conductivity for these structures. This approach is extended to structurally-adapted metal foam-fluid systems by broadening the pore volume fraction beyond 0.90 – resulting in the quantification of the fluid phase contribution for heat transfer enhancement and the proposition of empirical constants to support models developed by Calmidi & Mahajan [9]. Findings in this work offer strong support to the supposition that geometrical adaptions of microcellular structures can be used to modulate their effective thermal conductivity and that generalised values of empirical constants may be ambiguous to fully describe conduction heat transfer phenomena in microcellular structures. This approach may prove useful in the design of low-porosity metallic components for applications specific to conduction heat transfer.

Finite-size effects on heat and mass transfer in porous electrodes

In thin electrode applications, as the ratio of the obstacle size with respect to the system size increases, issues such as finite-size effects become more influential in the transport of heat and mass within a porous structure. This study presents a numerical approach to evaluate the finite-size effects on the heat and mass transfer in porous electrodes. In particular, numerical simulations based on the lattice Boltzmann method (LBM) are employed to analyze the pore-scale transport phenomena. Analyzing the results at both the electrode level and the pore level shows that the mass transfer performance is more influenced by the finite-size effects compared to the transfer of heat. The numerical simulations show that as the parameter m being the ratio of the electrode thickness to the particle diameter is halved, the effective diffusivity increases by 20% while the effective conductivity remains unchanged. We propose a novel analytical tortuosity–porosity (τ−ϕ) correlation as τ=[1−(1−ϕ)m+1]/ϕ where the finite-size effects are taken into account via the parameter m. Besides, particles of small size provide more uniform distributions of temperature and concentration within the porous structure with standard deviations of approximately half of the values obtained from the case made up of large particles. Our findings at the electrode level are compared with the commonly used macroscopic porosity-dependent correlations found in the literature. At the end, by performing a systematic assessment, we provide guidelines for efficient design of porous electrodes.

Eu-Doped Pyrochlore Crystal Nano-Powders as Fluorescent Solid for Fingerprint Visualization and for Anti-Counterfeiting Applications.

Undoped Y2Sn2O7 and Eu3+ doped Y2Sn2O7 samples with doping concentrations 7%, 8%, 9%, and 10% are successfully synthesized by the co-precipitation method. A complete structural, morphological, and spectroscopic characterization is carried out. XRD measurements reveal that samples crystallize in the pure single pyrochlore phase and Eu3+ ions occupy sites with D3d symmetry. After mechanical grinding, the average crystallite size is less than 100 nm for all compositions. Optical characterization shows emission from the 5D0 level towards the lower lying 7F0,1,2,3,4 levels. The CIE color coordinates of all the pyrochlore phosphors are very close to those of the ideal red light. For the visualization of latent fingerprints, different surfaces are tested, including difficult ones (wood and ceramic), with excellent results. All three levels of fingerprint ridge patterns are visualized: core (Level 1), bifurcation and termination (Level 2), and sweat pores (Level 3). Moreover, our nano-powders are used to prepare a stable fluorescent ink.

Electro-Acupuncture Pretreatment Ameliorates Anesthesia and Surgery-Induced Cognitive Dysfunction Via Inhibiting Mitochondrial Injury and nEuroapoptosis in Aged Rats.

Postoperative cognitive dysfunction (POCD) remains one of the most common complications following anesthesia and surgery (AS) in the elderly population. Calcium-mediated mitochondrial injury has been proved to induce cognitive impairment in a variety of neurologic diseases. In the current study we determined whether electro-acupuncture (EA) pretreatment ameliorated AS-induced POCD in aged rats, as well as the underlying mechanism. Eighty SD rats (18months, male) were randomly assigned into four groups (n = 20): C, C + EA, POCD and EA + POCD. Rats in Group POCD and EA + POCD were subjected to exploratory laparotomy under sevoflurane anesthesia. Rats of Group C + EA and EA + POCD received a 5-day EA stimulation at Hegu, Neiguan and Zusanli acupoints before AS. At 3rd day after AS, open field test along with Morris water maze test were employed to examine the cognitive function of aged rats. Then hippocampal tissues were stripped and hippocampal neuronal amount, expression level of cleaved caspase-9 level, cytochrome c (Cyt C), cleaved caspase-3 level, Bcl-2, Bax, ROS expression level, apoptosis rate, mitochondrial membrane potential (MMP), cytosolic calcium concentration ([Ca2+]c), opening level of mitochondrial permeability transition pore (mPTP) and ultrastructure of hippocampal neurons were detected separately. EA pretreatment inhibited AS-induced cognitive dysfunction. Furthermore, EA pretreatment decreased level of [Ca2+]c, MMP, mPTP, ROS and hippocampal mitochondrial disruption and enhanced neuronal amount. In addition, EA pretreatment notably reduced the AS-induced increased level of cleaved caspase-9, cleaved caspase-3 and expression of Cyt c, Bax/Bcl-2 ratio, as well as neuronal apoptosis rate in aged rats. EA pretreatment ameliorates AS-induced POCD in aged rats, the potential mechanism may be associated with inhibiting calcium overload and ameliorating mitochondrial injury and neuroapoptosis in hippocampal neurons.

Natural bone-mimicking nanopore-incorporated hydroxyapatite scaffolds for enhanced bone tissue regeneration

BackgroundA considerable number of studies has been carried out to develop alloplastic bone graft materials such as hydroxyapatite (HAP) that mimic the hierarchical structure of natural bones with multiple levels of pores: macro-, micro-, and nanopores. Although nanopores are known to play many essential roles in natural bones, only a few studies have focused on HAPs containing them; none of those studies investigated the functions of nanopores in biological systems.MethodWe developed a simple yet powerful method to introduce nanopores into alloplastic HAP bone graft materials in large quantities by simply pressing HAP nanoparticles and sintering them at a low temperature.ResultsThe size of nanopores in HAP scaffolds can be controlled between 16.5 and 30.2 nm by changing the sintering temperature. When nanopores with a size of ~ 30.2 nm, similar to that of nanopores in natural bones, are introduced into HAP scaffolds, the mechanical strength and cell proliferation and differentiation rates are significantly increased. The developed HAP scaffolds containing nanopores (SNPs) are biocompatible, with negligible erythema and inflammatory reactions. In addition, they enhance the bone regeneration when are implanted into a rabbit model. Furthermore, the bone regeneration efficiency of the HAP-based SNP is better than that of a commercially available bone graft material.ConclusionNanopores of HAP scaffolds are very important for improving the bone regeneration efficiency and may be one of the key factors to consider in designing highly efficient next-generation alloplastic bone graft materials.

Study on the mechanism of W/O emulsion flooding to enhance oil recovery for heavy oil reservoir

W/O emulsion is able to effectively improve the sweep volume and oil recovery factor during the waterflooding due to its strong mobility control ability, it has a great EOR appliance for heavy oil reservoirs. In this study, emulsion stability, droplet size distribution (DSD) and rheological behavior at different water content and salinity were investigated. Then core flooding experiments was conducted to study the oil displacement efficiency of W/O emulsion formed at different water content, and a visual micromodel was designed to observe the mechanisms of W/O emulsion flooding at the pore-throat scale. Results showed that W/O emulsion had the characteristics of the pseudoplastic fluid, exhibiting shear thinning behavior. Emulsion stability and DSD uniformity became worse with the increment of water content. Emulsion viscosity increased with water content varying from 20% to 40%, and then decreased as water content rose from 40% to 90%. Whereas Emulsion stability decreased slightly with the salinity increasing due to its high content of polar components inherent in heavy crude oil. The piston-like displacement could be formed due to its high mobility control ability caused by high viscosity. Meanwhile, the adverse effects caused by formation heterogeneity and viscosity fingering could be inhibited. After subsequent water breakthrough, emulsion droplets produced viscoelastic deformation during waterflooding. The emulsification carrying-on, block, and drag effect were the main mechanism of W/O emulsion flooding at the pore level. The findings of this study are significant for the enhanced oil recovery in heterogeneous heavy oil reservoirs.

Characteristics of effective thermal conductivity of porous materials considering thermal radiation: A pore-level analysis

Porous materials have attracted considerable attention in the fields of heat transfer and solar energy harvesting. Due to the complicated pore structures and multiple reflections of radiation beams at interior interfaces, the analysis of coupled radiative and conductive heat transfer in porous materials is complex and challenging. In this paper, heat transfer characteristics in porous materials considering the coupled modes of conduction and radiation are studied at pore level. A discrete ordinate ray-tracing (DORT) method is proposed to solve the radiative heat transfer in porous materials, which is then combined with the finite volume method to solve the energy balance equation. The geometry of porous structure is represented by the implicit function, which ensures the calculation accuracy of interface normal vectors during the solution of radiative heat transfer. A dimensional analysis is conducted and a governing dimensionless parameter (NSRC) is introduced, which well characterizes the scaling characteristics of the effective thermal conductivity (ETC). The proposed approach is demonstrated to be an effective way to simulate the coupled radiative-conductive heat transfer in porous materials at pore level. Due to the thermal radiation, the ETC for open-cell porous materials increases more dramatically with NSRC than that for closed-cell porous materials. A simple thermal network model is developed for both open- and closed-cell porous materials, which predicts the trends of the ETC with NSRC very well.

Anatomy promotes neutral coexistence of strains in the human skin microbiome

What enables strains of the same species to coexist in a microbiome? Here, we investigate whether host anatomy can explain strain co-residence of Cutibacterium acnes, the most abundant species on human skin. We reconstruct on-person evolution and migration using whole-genome sequencing of C.acnes colonies acquired from healthy subjects, including from individual skin pores, and find considerable spatial structure at the level of pores. Although lineages (sets of colonies separated by <100 mutations) with invitro fitness differences coexist within centimeter-scale regions, each pore is dominated by a single lineage. Moreover, colonies from a pore typically have identical genomes. An absence of adaptive signatures suggests a genotype-independent source of low within-pore diversity. We therefore propose that pore anatomy imposes random single-cell bottlenecks; the resulting population fragmentation reduces competition and promotes coexistence. Our findings suggest that therapeutic interventions involving pore-dwelling species might focus on removing resident populations over optimizing probiotic fitness.

Pore level characterization of Micro-CT images using percolation theory

Flow through porous media depends strongly on the spatial distribution of the geological heterogeneities which appear on all length scales. We lack precise information about heterogeneity distribution on various scales, from pore level to reservoir scale. However, some sources provide suitable information. At pore scale, for example, the micro-CT images show considerable insights into pore space structures and play valuable role in porous media characterization. The consequence of all geological heterogeneities is a great deal of uncertainty in dynamic performance of porous media which can be investigated using percolation theory. The main percolation quantities include the connected pore fraction; P, the backbone fraction; B, the dangling ends fraction; D, and the effective permeability; Keff. By finite size scaling within percolation theory, these quantities (i.e. P,B,D,Keff) become some functions of total pore fraction; p, and the system dimensionless length; L. In this work we examine the functional forms of percolation quantities on two-dimensional micro-CT images and develop new correlations for such quantities in three-dimensions. The results show good agreement on micro-CT samples with different pore size distribution and wide level of connectivity.

Исследование функциональных характеристик мезопористых электродов суперконденсаторов на основе кремний-углеродных пленок

The study of the supercapacitor electrodes based on silicon-carbon films obtained by electrochemical deposition from solutions with different ratios of methanol/hexamethyldisilane and addition of manganese and nickel salts was carried out using cyclic voltammetry, electrochemical impedance spectroscopy and impedance hodograph simulation by equivalent circuits method. The predominance of mesopores in the electrode samples was confirmed by the functional density method. According to a scanning electron microscopy study, the surface morphology of the silicon-carbon films is highly developed due to the presence of three-dimensional agglomerates and "foliated" structures. The best retention of specific capacity after 450 charge/discharge cycles is observed for electrode samples containing manganese and nickel. Simulation of equivalent circuits showed that all types of electrodes have hierarchical pore structure, after 450 charge/discharge cycles an increase in pore storage resistance and a decrease in transport pore resistance due to the activation of deeper pore levels is observed. The applicability of Peukert's law for this type of electrodes for prediction of electrode discharge time is shown.