Permeability Coefficient Research Articles

Differences in the permeation of Licoricchalcone A-polysaccharide self-assembled nanoparticles on healthy and DNCB-induced atopic dermatitis in Balb/c mice

Nanoformulation have been widely used in skin and transdermal drug delivery. However, the differences in integral nanoparticles absorption in healthy and diseased skin have not yet fully analyzed. The present study attempted to explore the percutaneous absorption of drugs via lesional skin by using atopic dermatitis (AD) as a model, dinitrochlorobenzene (DNCB) induced AD-like skin. In here, the small molecules of insoluble Licoricchalcone A (LA) and macromolecules glycyrrhizin polysaccharide were used to prepare LA-polysaccharide self-assembled nanoparticles (GPA-SANs) by micro-precipitation. An environment-responsive dye, P4, was loaded into SAN to track the transdermal translocation of the nanoparticles, while the drug marked with coumarin 6 (C6). Compared to healthy skin, the permeability of GPA-SANs on AD-like skin is stronger, which may be due to damage to the stratum corneum of the AD-like skin and increased intercellular spaces, resulting in an increased permeability coefficient. Therefore, the storage of nanoparticles and their diffusion at the lesion site also increased accordingly. CLSM shown that the fluorescence of P4 and C6 is observed to concentrate around the hair follicles and disseminate in the surrounding area in both AD-affected and healthy skin.It can be clearly seen that fluorescence signal of C6 in the intercellular spaces of the dermis and epidermis of AD-like skin, indicating that nano-drug on the disease skin can penetrate through the intercellular pathway to achieve therapeutic. The focus of the present study is to assess the permeability of healthy and disease skin, discuss their characteristics and discrepancy, aiming to provide a reference for the further study of nano-formulations in transdermal delivery.

Rate effects of cylindrical cavity expansion in fine-grained soil

Soil responds to cavity expansion is inherently rate-dependent, especially in the case of fine-grained soils. To better understand such rate effects, self-boring pressuremeter tests were conducted on Kunming peaty soil within a strain rate range of 0.1%/min to 5.0%/min. The results showed a clear dependence of cavity pressure and excess pore pressure (EPP) on strain rates—both increased with higher rates for a given radial displacement. In light of the experimental results, three cases of cylindrical cavity expansion were investigated using the finite element method and analytical method, partially drained expansion in Modified Cam-Clay (MCC) soil, and undrained and partially drained expansion in elastoviscoplastic (EVP) soil. The EVP behavior was and modeled using the MCC model and the overstress viscoplastic theory. The results indicated that over the strain rate range of 0.0001%/min and 50%/min, the rate response of cavity pressure for the case of partially drained expansion in MCC soil (permeability coefficient ranging from 5×10-6 m/s to 2.5×10-11 m/s) is not obvious, while the EPP response during undrained expansion in EVP soil shows rate-independent. Only the partially drained solution for cavity expansion in EVP soil captured the rate-sensitive responses of both cavity pressure and EPP, confirmed by the pressuremeter tests on the Kunming peaty soil, Saint-Herblain clay, and Burswood clay. This suggests that the rate effect results from a combination of drainage-related and time-dependent soil behavior. Parametric studies further demonstrated that both viscous behavior and the overconsolidation ratio significantly influence cylindrical cavity expansion response, and the drainage conditions during expansion can be assessed using a nondimensional velocity.

Flow stability and permeability in a nonrandom porous medium analog

The estimation of the permeability of porous media to fluids is of fundamental importance in fields as diverse as oil and gas industry, agriculture, hydrology, and medicine. Despite more than 150 years since the publication of Darcy's linear law for flow in porous media, several questions remain regarding the range of validity of this law, the constancy of the permeability coefficient, and how to define the transition from Darcy flow to other flow regimes. This study is a numerical investigation of the permeability and flow stability in a nonrandom quasi-tridimensional porous medium analog. The effect of increasing pressure gradient on the velocity field and on the estimation of Darcy and Darcy–Forchheimer coefficients is investigated for three different obstacles radius. The transition from Darcy flow to nonlinear behavior is associated with the formation of jets in the outlet of the porous medium and development of flow instabilities. Different representations of the Reynolds number proved adequate to detect deviation from the linear law. The instantaneous permeability calculated at each pressure gradient was sensitive to flow velocity, in agreement with previous studies stating that permeability cannot be conceptualized as a constant for real flows.

Impact of bacterial outer membrane and general porins on cyanide diffusion and biodegradation kinetics

The present study focuses on the analysis of the diffusion process of various cyanide compounds through general porins and outer membranes of gram-negative bacteria. We demonstrate the impact of the compound-to-porin radius ratio, the charge of cyanide ion, the Donnan potential, the intrinsic porin potential, the number and length of general porins, the fraction of open channels, and the size of bacteria on the effective diffusion coefficients and permeability coefficients of cyanide compounds. Moreover, we report, for the first time, the procedure for comparison of the rate of cyanide diffusion across the outer membrane with the rate of cyanide biodegradation that allows establishing the conditions for which the biodegradation is a diffusion-limited process or the diffusion is a significantly faster process than biodegradation. We apply this procedure to several experimental studies and predict the range of extracellular cyanide concentrations for which diffusion is a significantly faster process than biodegradation. We also demonstrate how these results affect the theoretical view of the cyanide biodegradation kinetics.

Probabilistic back analysis of reservoir landslide considering hydro-mechanical coupled observations

Precisely assessing statistical parameters to characterize spatial soil variability presents a significant challenge in probabilistic slope stability analysis, primarily due to inherent soil uncertainties and limited field-specific data. Probabilistic back analysis, recognized as an effective and reliable technique, offers a rational method for utilizing observational data to invert parameters. Nevertheless, previous investigations into parameter inversion for slope stability analysis have seldom considered the coupling of hydro-mechanical characteristics in reservoir landslides. This study proposes a novel integrated Bayesian framework to perform back analysis of reservoir landslides, incorporating the spatial variability of hydro-mechanical parameters. Within this framework, a hypoplastic constitutive model is developed to characterize the step-like deformation of the reservoir slope. The posterior knowledge of the saturated permeability coefficient and shear strength parameters is obtained by collecting field monitoring data of the underground water level and ground displacement. The Maliulin landslide, located in the Three Gorges Reservoir area of China, is used as an illustrative example to validate the proposed framework through back analysis of spatially variable soil parameters and probabilistic stability analysis. The results demonstrate that the proposed Bayesian updating framework significantly reduces the uncertainties associated with statistical values of soil parameters, providing more accurate and reasonable updated soil parameters for probabilistic slope stability analysis.

Microwave-assisted, sulfhydryl-modified β-cyclodextrin-silymarin inclusion complex: A diverse approach to improve oral drug bioavailability via enhanced mucoadhesion and permeation

The current study aimed to generate a sulfhydryl-modified β-cyclodextrin-silymarin complex (sulfhydryl-modified β-CD-SMN complex) and to evaluate the enchantment in solubility, permeability, and bioavailability of a model BCS Class IV drug silymarin (SMN). For this purpose, sulfhydryl-modified β-CD was synthesized by replacing all primary and secondary –OH groups at the β-CD backbone with sulfhydryl groups via a novel microwave-assisted technique. Afterward, sulfhydryl-modified β-CD was complexed with silymarin and characterized by FTIR and 1H NMR spectroscopy. Moreover, no. of sulfhydryl groups and their oxidative stability, solubility, safety, mucoadhesion, release, diffusion, and rheological studies were performed. Furthermore, in-vivo studies were conducted to confirm enhanced pharmacokinetic properties of silymarin. Sulfhydryl-modified β-CD showed 8291 ± 418 μmol/g sulfhydryl groups that were prone to oxidation at pH ≥ 5, however, most of the sulfhydryl groups were found stable at pH 4 having a pKa value of 8.3. Modified β-CD oligomer showed improved solubility of SMN, significantly enhanced drug transport across goat intestinal mucosa, 78-fold improved mucoadhesion, improved drug dissolution and 4.4-fold enhanced dynamic viscosity. No toxic effects were reported to Caco-2 cells at 0.5 % (m/v) concentration of sulfhydryl-modified β-CD for 24 h. The apparent permeability coefficient (Papp) of SMN was 6.9-fold enhanced on goat intestinal mucosa. Moreover, in-vivo studies confirmed a significantly enhanced oral bioavailability of SMN due to combination with sulfhydryl-modified β-CD. Based on these findings, the sulfhydryl-modified β-CD-silymarin inclusion complex can be a promising technique to enhance the bioavailability of BCS Class IV drugs via enhanced solubility, mucoadhesion, and permeability triple action.

Green power generation from the Tigris River using pressure retarded osmosis process

Sustainability including renewable energy and green power, is one of the important feature in recent years due to environmental constraints and the emission of CO2 from fossil fuel. Pressure retarded osmosis (PRO) process is considered one of the effective technology for power generation. This study assessed the application of pressure retarded osmosis to produce power from Tigris River water in Baghdad City, Iraq. Spiral wound TFC membrane was tested in the PRO process with different variables. The effect of different types of draw solutions (MgCl2, NaCl, Sodium Formate, KCl, Sodium Acetate), applied pressure (0 – 7 bar), and draw solution concentration (0.08 and 0.4 M) were tested in this work. The flux, recovery, and power density for the five draw solution in the order MgCl2 >NaCl>sodium formate>KCl>sodium acetate, while the reverse solute flux in the order MgCl2 <sodium acetate<KCl<sodium formate<NaCl. Experimentally the membrane pure water permeability (A) was found to be 4.87 L/m2.h.bar. The result revealed that the reverse solute flux and the solute permeability coefficient for MgCl2 was 0.55 g/m2.h and 8.78 × 10−8 m/s. The flux, recovery, and power density for MgCl2 with a concentration of 0.4 M and applied pressure of 7 bar was 1.69 LMH, 19 %, and 0.33 W/m2, respectively.

Study on the Performance Evaluation Method and Application of Drainage Nonwoven Geotextile in the Yellow River Sediment Filling Reclamation Area

Technical challenges associated with drainage and filling efficacy confront the Yellow River sediment filling reclamation, a novel approach to reclaiming coal-mined subsided lands. This study proposes an improved geotextile performance evaluation method to address the shortcomings of current geotextile screening methodologies in the drainage of the Yellow River sediment. This method comprehensively considers essential characteristics under working conditions, such as permeability, soil conservation, and blockage prevention properties, including indicators such as the permeability coefficient and sediment retention rate of geotextiles under pressure. Indoor flume filling and drainage experiments were implemented to verify the efficacy of geotextile drainage. The improved method identified thermal-bonded nonwoven geotextiles of 200 and 250 g·m−2 as having the highest comprehensive evaluation scores. The experimental results showed that these geotextiles significantly improved their drainage efficiency and better met the specific requirements of the Yellow River sediment filling reclamation. Traditional screening methods may be unsuitable for sediment drainage conditions, necessitating sediment interception and rapid drainage due to the streaming water–sediment mixture. Therefore, the newly established performance evaluation method is more appropriate for the specific requirements. It is recommended that a simple vibrating device be installed to maintain 20 vibrations per minute to keep drainage channels clear and provide stable drainage performance in engineering applications.

Anti-seepage performance and oxygen barrier performance of the three-layered landfill cover system comprising neutralized slag under extreme climate conditions

For acidic industrial solid wastes, an effective cover system is needed to reduce the rainwater infiltration and oxygen intrusion, thus reducing the generation of acid mine drainage (AMD) from wastes. A three-layered cover using low-permeability neutralized slag (abbreviated as TCNS) at the bottom of the traditional capillary barrier cover is proposed, in line with the novel concept of “waste protecting waste”. This study investigates the anti-seepage performance and oxygen barrier performance of TCNS under extreme climate conditions, through laboratory column test and numerical simulations. The results show that the water content of the neutralized slag (NS) layer remained stable (i.e., changed by less than 0.02) under either extremely wet condition or extremely dry condition. Under extremely wet condition (i.e., heavy rainfall corresponding to a 50-year return period), no water percolation was observed at the cover bottom; under extremely dry conditions, oxygen diffusion was greatly impeded, e.g., after 208 days of column test, the SO42− concentration in the AMD of the exposed (i.e., uncovered) waste rock was 4.6 times higher than that of the waste rock covered by TCNS. Numerical simulations considering two realistic climate conditions (i.e., humid and arid) showed that TCNS were effective in controlling water percolation and oxygen intrusion. The saturated permeability coefficient (ks) and initial saturation degree (Se) of the NS layer have significant effects on the performance of TCNS, i.e., decreasing ks or increasing Se can effectively reduce the water percolation and oxygen flux. In sum, TCNS is an effective barrier for controlling water percolation and oxygen intrusion, even in extreme climate conditions. Consequently, it can effectively minimize AMD leakage and thus reduce geological disasters such as groundwater contamination.

One-dimensional consolidation analysis of layered unsaturated soils: An improved model integrating interfacial flow and air contact resistance effects

Layered unsaturated soils exhibit complex mechanical and physical properties. Owing to the roughness between unsaturated soil interfaces and the presence of irregularly distributed micro-pores, this study explores the laminar flow of pore water and counter-cyclonic flow of pore air through these channels at low velocities. In response to the complex consolidation behavior of unsaturated soils influenced by the flow and air contact resistance, an improved model is developed. The model incorporates the flow contact transfer coefficient (Rω), flow partition coefficient (ηω), air contact transfer coefficient (Ra) and air partition coefficient (ηa). Semi-analytical solutions for pore water pressure, pore air pressure and settlement in layered unsaturated soils are derived by employing the Laplace transform and its inverse transform. The rationality of the model is validated through comparative analysis with existing solutions. Analysis of the improved model yields critical insights: the presence of flow and air contact resistance leads to the development of relative pore pressure and air pressure gradients at interfaces, which diminishes the influence of the permeability coefficients of the water phase (kω) and air phase (ka) on the consolidation process. Moreover, neglecting the flow and air contact resistance effects may lead to an overestimation of settlement.

Study on the working performance and microscopic mechanism of high-performance grouting material (HPGM) reinforced dense fine sand layer

To address the challenges of small diffusion radius, low early strength and long setting time of traditional cement grout in dense fine sand layer, based on the synergistic mechanism, a novel high-performance grouting material (HPGM) was developed using ground granulated blast-furnace slag (GGBS), ultra-fine fly ash (UFFA), and ultra-fine Portland cement (UFPC) as raw materials. Firstly, Laboratory experiments were conducted to investigate the working performance of HPGM under varying proportions. Secondly, based on the self-designed advanced small pipe grouting full-scale test device, the diffusion performance and reinforcement characteristics of HPGM under varying proportions were analyzed. Finally, the XRD and SEM testing methods were employed to elucidated the hydration mechanism of the HPGM. The test results indicate that as the mass ratio of GGBS to UFFA decreases, there is a gradual increase in hardening rate, fluidity and setting time of HPGM. Additionally, the unconfined compressive strength (UCS) initially increase before decreasing. Furthermore, with the decreased mass ratio of GGBS to UFFA, the HPGM diffused in dense fine sand layer through compaction-splitting, permeation-splitting, and splitting grouting processes. The hydration products of the HPGM primarily consist of C(-A)-S-H, AFt, and Ca(OH)2, when the mass ratio of GGBS to UFFA falls within the range of 4:2–3:3, the UFFA facilitates the AFt hydration products in significant quantities. Its cementation and filling effect lead to the formation of a dense microstructure in the soil, resulting in a substantial reduction in permeability coefficient and a marked increase in UCS. The research findings can offer high-performance grouting material for underground engineering construction while also presenting innovative ideas for resource utilization from solid wastes like GGBS and UFFA.

Technical and environmental assessment of sludge-derived slag generated from high temperature slagging co-gasification process as a sustainable construction material

Tremendous amount of sludge is generated annually from freshwater treatment or sewage. The high temperature slagging co-gasification converts the sludge to slag showing the potential application for construction material. In this study, the physico-chemical properties of 4 types of slags generated from the co-gasification of municipal solid waste (MSW) with sludge from freshwater treatment or sewage, and ashes from sludge incineration are comprehensively analyzed. Leaching performance of the sludge-derived slag and mortar (with slag as the fine aggregate), as determined based on Toxicity Characteristic Leaching Procedure (TCLP), batch leaching and column leaching tests, indicates the slag can be considered safe for reutilization. Compressive strength test demonstrates that the mortars perform excellently and have the potential to replace sand in concrete production. The consolidation coefficient of slag (1.6 – 39.1 m2/year) is lower than the sandy silt but higher than clay. Additionally, the coefficient of permeability (∼1.96 × 10-3 m/s), angle of shearing resistance (∼39°), and undrained shear strength (375.5 ± 54.8 kPa) of the slag are comparable to sand. The life cycle assessment (LCA) is also conducted to evaluate the environmental impacts and benefits of reutilizing sludge-derived slag as an alternative material for concrete production and land reclamation.

Chloride permeation resistance of sulphoaluminate cement-based composite characterized by both alternating current section and RCM methods

Sulphoaluminate cement (SAC) was widely used for rapid repair and strengthening of building structures due to its excellent quick hardening and high early strength behavior. This study developed a SAC-based engineering cement composites (ECC) with ultra-high molecular weight polyethylene (UHMWPE) and investigated its mechanical properties. Chloride ion permeability coefficient were evaluated by new alternating-current sectioning and rapid chloride migration (RCM). The mechanism of the SAC-ECC against chloride erosion were quantified using nitrogen isothermal adsorption. The results show that the fracture energy, tensile strength and strain of SAC-ECC samples are higher than that of normal ECC. The polyethylene (PE) fiber could significantly improve the flexural strength and toughness with PE fiber content of 0.75 % by volume. The hydration products generated could react with chloride ion to make it chemically stabilized, leading to reduce the chloride ion diffusion coefficient significantly. Based on microscopic analysis (SEM), the pore structure in SAC-ECC composite improved remarkedly while the volume of harmful pore decreased evidently as well. SAC-ECC developed in this paper could be poetically applied to strengthening and repair of marine concrete structures.

Elucidating the Molecular Mechanisms by which Porous Polymer Networks Affect Structure, Aging Propensity, and Selectivity of Microporous Glassy Polymer Membranes using a Multiscale Approach.

Microporous glassy polymer membranes suffer from physical aging, which adversely affects their performance in the short time frame. We show that the aging propensity of a model microporous polymer, poly(1-trimethylsilyl-1-propyne) (PTMSP), can be effectively mitigated by blending with as little as 5 wt % porous polymer network (PPN) composed of triptycene and isatin. The aging behavior of these materials was monitored via N2 pure gas permeability measurements over the course of 3 weeks, showing a 14% decline in PTMSP blended with 5 wt % PPN vs a 41% decline in neat PTMSP. Noteworthy, PPNs are 2 orders of magnitude cheaper than the porous aromatic frameworks previously used to control PTMSP aging. A variety of experimental and computational techniques, such as Positron Annihilation Lifetime Spectroscopy (PALS), free volume measurements, cross-polarization/magic angle spinning (CP/MAS) 13C NMR, transport measurements and molecular dynamics (MD) simulations were used to uncover the molecular mechanisms leading to enhanced aging resistance. We show that partial PTMSP chain adsorption into the PPN porosity reduces the PTMSP local segmental mobility, leading to improved aging resistance. Permeability coefficients were broken into their elementary sorption and diffusion contributions, to elucidate the mechanism by which the reduced PTMSP local segmental mobility affects selectivity in gas separation applications. Finally, we demonstrate that in these systems, where both chemical and physical interactions take place, transport coefficients must be corrected for thermodynamic nonidealities to avoid erroneous interpretation of the results.

Study on the Spontaneous Combustion Law of Coal Body around a Borehole Induced by Pre-extraction of Coalbed Methane.

To address the challenges associated with the high gas content, high pressure, and low permeability coefficient in deep coal seams, strategies such as infilling boreholes and increasing the negative pressure of extraction are commonly implemented to alleviate issues related to coalbed methane extraction. However, long-term mining pressure can lead to the development of cracks in the coal seam near the borehole, thereby creating air leakage channels, which could potentially impact the oxygen supply during the extraction process. This leads to secondary disasters such as the spontaneous combustion of coal and gas explosions, considerably impacting the life and health of underground workers. To solve this issue, a thermal-fluid-solid coupling model for the working surface was constructed based on numerical simulation software, taking into account the multimechanism coupling effect of coal seam gas. The laws of coal oxidation and spontaneous combustion induced by coalbed methane extraction around boreholes were studied. The variation laws of the oxygen concentration, coal temperature, and oxidation heating zone around the borehole under different extraction conditions were simulated and analyzed. The findings demonstrate that the negative extraction pressure enables the gas to penetrate the fracture zone of the borehole, leading to an increase in the oxygen consumption rate and coal temperature around the borehole with an increase in negative extraction pressure. The coal gas leakage surrounding the borehole reduces as the sealing depth increases, and both the heating rate of coal and oxygen volume fraction show a downward trend. The fitting relationship between the negative pressure of drainage, depth of sealing, and temperature change in the coal body surrounding the boreholes was identified. It was determined that the negative pressure of 13 kPa for borehole drainage and a sealing depth >18 m are the optimal extraction parameters. The range of the oxidation zone and the position of the boundary line under this parameter were predicted, and the position function of the dangerous area of oxidation heating was defined. The research results have remarkable implications for the coordinated prevention and control of gas and coal spontaneous combustion in coalbed methane predrainage boreholes, as well as for efficient prevention and control of CO in on-site gas extraction boreholes, thus ensuring efficient and safe gas extraction.

Diffusion properties and cementitious characteristics of ultrafine cement slurry in coral sand

Investigating the infiltration, diffusion and permeation of cement grouting materials in coral sand and the effects of grouting reinforcement measures can provide scientific support for coral sand foundation treatment, building settlement adjustment, and coastal geological disaster prevention and control. Permeation grouting tests were conducted on coral sand, and the effects of the water–cement ratio (w/c), permeability coefficient of coral sand (PCCS), and grouting pressure on the diffusion distance of the slurry, uniaxial compressive strength (UCS), and relative permeability coefficient (RPC) of the grouting cementitious body were analysed. In addition, the change trends in the slurry diffusion distance and slurry pressure was described, and the characteristics of the grouting cementitious body were analysed from three perspectives: UCS, RPC, and microstructure. The results showed that the slurry pressure increases nonlinearly with increasing grouting time and decreases nonlinearly with increasing slurry diffusion distance; additionally, UCS decreases with increasing slurry diffusion distance, with an “S”-shaped curve that is first concave and then convex, with an inflection point near L = 50 cm.

Experimental Study on Improving the Impermeability of Concrete under High-Pressure Water Environments Using a Polymer Coating

The concrete lining of high-pressure water conveyance tunnels permeates under high-pressure water. Dense and hydrophobic coating can effectively improve the impermeability of concrete. However, the coating exhibits varying impermeability in different high-pressure environments, which can even lead to coating detachment or damage. The objectives of this study are to improve the high-pressure impermeability of concrete by using a polymer coating, and to study the varying impermeability through experiments. This study applied a polymer coating called SCU-SD-SP-II (SSS) to concrete surfaces, and it formed a composite protective layer with an epoxy-modified silicone (EMS) coating. A series of high-pressure impermeability tests were conducted to study the seepage regulation of the coated concrete and the failure mechanism of the SSS coating under cracks in the concrete. The results indicate that the SSS coating has excellent impermeability. Pressurized water of 3 MPa could not permeate the SSS coating with a thickness of 0.5 mm within 24 h. Under both external and internal water pressure conditions, the SSS coatings improved concrete impermeability. Additionally, the average seepage height and relative permeability coefficient of the latter decreased by 49.6% and 71.2%, respectively, compared with the former. After concrete cracking, the SSS coating could withstand 3 MPa pressure on crack surfaces smaller than 1 mm. When the crack width was greater than 2 mm, the SSS coating deformed under 1 MPa pressure. As the pressure increased to 2 MPa or even 3 MPa, the SSS coating was punctured or torn due to stress concentration. This study provides new insights into the impermeability of concrete under high water pressure.

A simple model incorporating foam rheology to quantify foam penetration behaviour in EPB shield tunnelling

Fulfilling the role of a soil conditioner, foam plays a pivotal role in Earth Pressure Balance (EPB) shield tunnelling by enhancing soil properties such as lowering permeability and increasing flowability. This study introduces a macro-model designed to quantify foam penetration behaviour in saturated sand, utilising rheological properties. To validate this model, experiments were conducted to replicate the foam penetration behaviour. Six sand beds characterised by varying particle sizes, along with foam having an expansion ratio of fifteen, were employed for penetration tests under different hydraulic conditions utilising a sand column device. The rheological profile of the foam is described by the power-law model, as also found by rheometer tests, although with different parameters. The flow behaviour of foam within the sand column conforms to the flow equation that governs power-law fluids in porous media. The developed model effectively predicts the foam penetration process under varying hydraulic conditions compared with the experimental results. Furthermore, the fitting results of the experimental data indicate that the flow behaviour index of the foam remains approximately 0.09 across all tests, regardless of the type of sand used. In contrast, the model-derived generalised permeability coefficient strongly correlates with the effective particle size (d10) of the sand bed. Overall, the model effectively quantifies the foam penetration behaviour, accounting for changes in infiltration velocity and pore water pressure, which is essential for understanding the transfer of support pressure in EPB shield tunnelling.

Various steaming durations alter digestion, absorption, and fermentation by human gut microbiota outcomes of Polygonatum cyrtonema Hua polysaccharides.

Different steaming durations dramatically alter the structure of Polygonatum cyrtonema polysaccharides (PCPs). This study aimed to compare characteristics of digestion, absorption, and fermentation by gut microbiota across four representative PCPs from different steaming durations (0, 4, 8, and 12 h), each with unique molecular weights and monosaccharide profiles. Chemical composition of the four PCPs was analyzed. Digestibility was evaluated using an in vitro saliva-gastrointestinal digestion model. Absorption characteristics were assessed with a Caco-2 monolayer model, and impacts on gut microbiota composition and short chain fatty acid (SCFA) levels were analyzed using in vitro fermentation with human gut microbiota. Longer steaming durations altered the chemical profiles of PCPs, reducing carbohydrate content (84.87-49.58%) and increasing levels of uronic acid (13.99-19.61%), protein (1.07-5.43%), and polyphenols (0.05-2.75%). Four PCPs were unaffected by saliva digestion but showed enhanced gastrointestinal digestibility, with reducing sugar content rising from 4.06% (P0) to 38.5% (P12). The four PCPs showed varying absorption characteristics, with P0 having the highest permeability coefficient value of 9.59 × 10-8 cm/s. However, all PCPs exhibited poor permeability, favoring gut microbiota fermentation. The four PCPs altered gut microbiota composition and elevated SCFA production, but levels declined progressively with longer steaming durations. All PCPs significantly increased the abundance of Bacteroidota, Firmicutes, and Actinobacteriota, making them the dominant bacterial phyla. Additionally, all PCPs significantly increased the abundance of Bifidobacterium, Prevotella, and Faecalibacterium compared to the control group, which, along with Bacteroides, became the dominant microbiota. Increasing the steaming duration led to a reduction in Prevotella levels, with PCPs from raw rhizomes showing the highest relative abundance at 24.90%. PCPs from moderately steamed rhizomes (4 h) led to a significant rise in Faecalibacterium (7.73%) among four PCPs. P8 and P12, derived from extensively steamed rhizomes (≥8 h), exhibited similar gut microbiota compositions, with significantly higher relative abundances of Bacteroides (20.23-20.30%) and Bifidobacterium (21.05-21.51%) compared to P0 and P4. This research highlights the importance of adjusting steaming durations to maximize the probiotic potential of P. cyrtonema polysaccharides, enhancing their effectiveness in modulating gut microbiota and SCFA levels.

Optimal development and performance evaluation of electrolytic graphene oxide synergistic all-solid waste cementitious grouting material

The low-carbon and friendly alkali-activated cementitious (AACM) grouting material has a broad application potential in the field of grouting engineering due to its excellent workability and higher early strength and is expected to replace cement grouting material in the future. In this study, an AACM grouting material using electrolytic graphene oxide (EGO) synergistic ground granulated blast-furnace slag (GGBS)-fly ash (FA)-rice husk ash (RHA) solid waste was proposed. The optimal ratio was 0.025 % EGO, 8.13 % FA, 26.6 % RHA, and 65.27 % GGBS, which determined by the Analytic Hierarchy Process (AHP), Entropy Weight Method (EWP), and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methods. A systematic evaluation of the mechanical properties and impermeability of the proposed AACM grouting material was conducted by macro experiments (compressive strength, flexural strength and permeability) and micro experiments (XRD, SEM-EDS, Fourier Transform Infrared Spectrometer (FTIR) and Thermogravimetry Analysis (TG)). The results show that the increment of compressive strength and flexural strength for AACM grouting material with 0.025 % EGO compared to the cement water-glass grouting material were 161.2 % and 2.9 %, respectively, at 7-day. While the permeability coefficient compared to AACM grouting material without EGO decreased by 43.9 %. The XRD results show that the EGO reduced the intensity of AACM grouting material diffraction peaks, and FTIR analysis reveals that EGO increased the visibility of O-C-O characteristic peaks. These confirmed that EGO could enhance the degree of alkali activation reaction. The TG results indicate that the addition of EGO promoted the formation of carbonates, which strengthen the mechanical properties of AACM grouting material. The SEM-EDS results demonstrate that EGO increased the Ca/Si ratio, promoted the formation of highly polymerized hydration products.