Permeability Reduction Research Articles

Starch biocomposites preparation by incorporating organosolv lignins from potato crop residues

Plastic wastes accumulated due to food packaging pose environmental threats. This study proposes biopolymeric films containing lignins extracted from potato crop residues (PCR) through organosolv treatment as a green alternative to non-degradable food packaging. The isolation process yielded 43.9 wt% lignins with a recovery rate of 73.5 wt% achieved under optimum conditions at 180 °C with 50 % v/v ethanol. The extracted lignins were then incorporated into a starch matrix to create biocomposite films. ATR-FTIR analysis confirmed interactions between the starch matrix and extracted lignins, and XRD analysis showed the amorphous structure of lignins, reducing film crystallinity. The addition of 1 wt% of extracted lignins resulted in a 87 % reduction in oxygen permeability, a 25 % increase in the thermal stability of the film, and a 78 % enhancement in antioxidant. Furthermore, introducing 3 wt% lignins led to the lowest water vapor transmission rate, measuring 9.3 × 10−7 kg/s·m2. Morphological studies of the films demonstrated a homogeneous and continuous structure on both the surface and cross-sectional areas when the lignins content was below 7 wt%. These findings highlight the potential of using organosolv lignins derived from potato crop residues as a promising additive for developing eco-friendly films designed for sustainable food packaging.

Assessing the performance of metakaolin-enriched bio-mineralized concrete

This research paper delves into an innovative approach leveraging pozzolanic material, particularly Metakaolin (MK), as a sustainable substitute for cement in concrete production. The study explores the integration of MK at various ratios, examining its impact on the creation of eco-friendly bio-mineralized concrete. By assessing MK ratios up to 15% by weight of cement, this work identifies a threshold—10% MK—that significantly enhances concrete properties, notably reducing permeability by 23.63% at 28 days. Incorporating bacteria at a concentration of 10^5 cfu/ml further amplifies these benefits, showcasing a 19% increase in compressive strength and a remarkable 43.23% reduction in permeability through calcium carbonate deposition. This synergy between MK and bio-mineralization not only fortifies concrete but also curtails cement content while maintaining or even enhancing its durability and strength. The research underscores the potential of MK and bio-mineralization as game-changing, eco-conscious solutions for concrete manufacturing, advocating for their adoption in construction to mitigate cement's environmental impact and address waste disposal, ultimately fostering sustainable growth in the industry. The study's findings spotlight a paradigm shift toward integrating biological processes into construction engineering, paving the way for a greener, more resilient built environment.

Discrete pore and particle size distributions during pore blocking and cake filtration

Modeling membrane filtration is important for plenty industrial applications. The understanding of the phenomena and related mechanisms aims at the improvement of techniques in different areas. Therefore, different authors have proposed models to describe the mechanisms related to the filtration process involving either cake build-up or blocking processes, a few of them however have proposed both concepts simultaneously, although none considered pore and particle size distribution during the process, which is the proposal brought up in this paper. Transient solutions for filtrate volume and filter cake thickness as a function of initial pore and particle size distributions are obtained. Good matching between the studied experimental data and the proposed model was observed. In general, the results showed that permeability reduction and filtrate volume are strongly influenced by the initial pore and particle size distributions. In addition, the cake build-up rate depends on both the particle size distribution and the residual flow through blocked pores. It was observed that, after all the largest particles have blocked the smaller pores, effective permeability and flow rate vary only due to cake build-up. Finally, because the proposed empirical parameters do not depend on the pore size distribution, this model can be applied for predicting permeability decline for any feed concentration.

Transport and retention of silica nanoparticles in glass-bead columns: effects of particle size, type, and concentration of ionic species

Silica nanoparticles (SiO2 NPs) have garnered substantial attention as versatile additives in saline fluids, finding application in areas like environmental remediation, wastewater treatment, enhanced oil recovery, and carbon geo-sequestration. Despite their potential, the intricate interaction between electrolyzed nanoparticles and porous media remains inadequately researched in these contexts. This study delves into the pivotal yet underexplored aspect of silica nanoparticle absorption behavior within porous media, a key determinant of their practical effectiveness. The research focuses on silica particles with dimensions of 10 nm and 50 nm, synthesized via hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in methanol. Employing packed glass bead columns as a surrogate for porous media, the study unravels the complex mechanisms governing nanoparticle transport and deposition. Comprehensive investigations encompass variations in particle sizes, ionic strength, and ionic species, resulting in the examination of 48 distinct flooding scenarios. UV/Vis spectrophotometry is used to quantify nanoparticle concentrations in effluents, elucidating their transport behavior within the porous media. Concurrently, pressure drop alterations across the media serve as indicators of particle plugging and changes in permeability. Intriguingly, specific conditions involving a nanofluid comprising 50 nm silica nanoparticles and 10,000 ppm of magnesium chloride exhibit pronounced permeability reduction, offering potential insights for optimizing applications. Particularly noteworthy is the unique reduction in silica particle retention on glass bead surfaces as salinity increases, especially in the presence of magnesium sulfate. A concentration of 5000 ppm magnesium sulfate induces a log-jamming mechanism, resulting in an amplified final-to-intermediate permeability ratio. Experimental outcomes align with observations from scanning electron microscopy, improving understanding of porous media retention mechanisms. This study contributes to a deeper understanding of interactions between nanoparticles and porous media, paving the way for enhanced application strategies.

A highly-selective layer-by-layer membrane modified with polyethylenimine and graphene oxide for vanadium redox flow battery

ABSTRACT A selective composite membrane for vanadium redox flow battery (VRFB) was successfully prepared by layer-by-layer (LbL) technique using a perfluorosulfonic sulfonic acid or Nafion 117 (N117). The composite membrane referred as N117-(PEI/GO)n, was obtained by depositing alternating layers of positively charged polyethylenimine (PEI) and negatively charged graphene oxide (GO) as polyelectrolytes. The physicochemical properties and performance of the pristine and composite membranes were investigated. The membrane showed an enhancement in proton conductivity and simultaneously exhibited a notable 90% reduction in vanadium permeability. This, in turn, results in a well-balanced ratio of proton conductivity to vanadium permeability, leading to high selectivity. The highest selectivity of the LbL membranes was found to be 19.2 × 104 S.min/cm3, which is 13 times higher than the N117 membrane (n = 0). This was translated into an improvement in the battery performance, with the n = 1 membrane showing a 4–6% improvement in coulombic efficiency and a 7–15% improvement in voltage efficiency at current densities ranging from 40 to 80 mA/cm2. Furthermore, the membrane displays stable operation over a long-term stability at around 88% at a current density of 40 mA/cm2, making it an attractive option for VRFB applications using the LbL technique. The use of PEI/GO bilayers maintains high proton conductivity and VE of the battery, opening up possibilities for further optimization and improvement of VRFBs.

Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

AbstractNanocomposites (NC) of polypropylene (PP) and organophilic montmorillonite (oMt) are produced by reactive mixing with simultaneous grafting of maleic anhydride (MA) onto PP using organic peroxide as initiator. Five different strategies of incorporating reactants and clay into a laboratory mixer are used. The structure of composites is examined by FT‐IR spectroscopy, x‐ray diffraction and scanning electron microscopy. Rotational rheometry, thermogravimetry and oxygen permeability are used to evaluate properties. The preparation method has a remarkable influence on NC's structure. Simultaneous addition of peroxide and MA to molten PP followed by incorporation of clay 20 minutes later produces the best degree of clay exfoliation/disaggregation. The NCs obtained using this procedure are highly transparent and have very thin tactoids with interlayer spacing more than 50% larger than the original oMt. The incorporation of just 2 wt% of clay gives place to more than 30% reduction in PP oxygen permeability. Additionally, the temperature at the maximum thermal degradation rate in nitrogen reduces in about 60°C while the temperature at which the thermal degradation process begins is not affected.Highlights Highly intercalated/exfoliated PP/oMt nanocomposites are synthesized Reactive mixing procedure affects the quality of nanocomposite's structure A initial period of grafting before clay addition is the most effective method Highly transparent materials with small tactoids of d001>4 nm is generated PP oxygen permeability is highly reduced by the use of just 2 wt% of nanoclay

Assessment of enhanced strength and stiffness properties of bio-engineered coal fly ash

This study investigates the use of urease-producing bacteria for microbial induced calcite precipitation (MICP) to enhance the mechanical properties of coal fly ash (CFA). Sporosarcina pasteurii was employed to treat CFA with cementation solutions over 7, 14, and 28 days. Biotreated samples exhibited improved compressive strength, shear strength, stiffness, and cohesion. Calcite precipitation increased, and permeability decreased with treatment cycles, resulting in a 78% reduction in permeability and 8% calcite precipitation in a 28-day cycle. X-ray diffraction (XRD) and scanning electron microscope (SEM) investigations support the improved engineering properties of bioengineered coal fly ash (BCFA) samples.

Tuning the water intrinsic permeability of PEGDA hydrogel membranes by adding free PEG chains of varying molar masses.

We explore the effect of poly(ethylene glycol) (PEG) molar mass on the intrinsic permeability and structural characteristics of poly(ethylene glycol) diacrylate PEGDA/PEG composite hydrogel membranes. We observe that by varying the PEG content and molar mass, we can finely adjust the water intrinsic permeability by several orders of magnitude. Notably, we show the existence of maximum water intrinsic permeability, already identified in a previous study to be located at the critical overlap concentration C* of PEG chains, for the highest PEG molar mass studied. Furthermore, we note that the maximum intrinsic permeability follows a non-monotonic evolution with respect to the PEG molar mass and reaches its peak at 35 000 g mol-1. Besides, our results show that a significant fraction of PEG chains is irreversibly trapped within the PEGDA matrix even for the lowest molar masses down to 600 g mol-1. This observation suggests the possibility of covalent grafting of the PEG chains onto the PEGDA matrix. CryoSEM and AFM measurements demonstrate the presence of large micron-sized cavities separated by PEGDA-rich walls whose nanometric structures strongly depend on the PEG content. By combining our permeability and structural measurements, we suggest that the PEG chains trapped inside the PEGDA-rich walls induce nanoscale defects in the crosslinking density, resulting in increased permeability below C*. Conversely, above C*, we speculate that partially trapped PEG chains may form a brush-like arrangement on the surface of the PEGDA-rich walls, leading to a reduction in permeability. These two opposing effects are anticipated to exhibit molar-mass-dependent trends, contributing to the non-monotonic variation of the maximum intrinsic permeability at C*. Overall, our results demonstrate the potential to fine-tune the properties of hydrogel membranes, offering new opportunities for separation applications.

Little Ironweed and Java Tea in Herbal Toothpaste Reduced Dentine Permeability: An In Vitro Study.

To determine the effect of an herbal toothpaste containing Little Ironweed and Java Tea, on reducing dentine permeability in vitro. Dentine discs from human mandibular third molars were divided into three groups and brushed with herbal toothpaste, nonherbal toothpaste, or deionized water. Each group was immersed in artificial saliva (AS) or 6% citric acid. The permeability of each dentine disc was evaluated before and after saliva or acid challenge using a fluid filtration system. The morphology of dentine discs after treatment was observed using scanning electron microscopy (SEM). The mean permeabilities were statistically analyzed using analysis of variance and Tukey's test. The nonherbal and herbal toothpaste groups demonstrated reduced dentine permeability. AS immersion decreased dentine permeability in both toothpaste groups with values lower than the control group. Dentine permeability values increased after acid immersion in the toothpaste groups and were similar to each other. SEM revealed small granular crystal-like and round particles on the dentine surface and opening of dentinal tubules of both toothpaste groups. More dentinal tubules were opened after brushing with deionized water. The reduction of dentine permeability caused by the herbal toothpaste was similar to that of the nonherbal toothpaste after brushing and the simulated oral conditions. Both herbal plants have the possibility to alleviate clinical hypersensitivity by reducing dentine permeability. Little Ironweed and Java Tea in the toothpaste composition is a potential choice for treating hypersensitive dentine.

Study on morphological, mechanical, thermal, barrier, rheological, and biodegradation properties of poly(butylene adipate‐co‐terephthalate)/thermoplastic starch/poly(propylene carbonate)‐g‐polyurethane biodegradable films

AbstractBioplastic films with excellent physical properties and barrier properties were successfully prepared from poly(butylene adipate‐co‐terephthalate) (PBAT), thermoplastic starch (TPS), and poly(propylene carbonate)‐g‐polyurethane (PPCU). The rheological, mechanical, barrier, dynamic mechanical properties, and microstructure of the PBAT/TPS/PPCU blend films were studied. The proportion of PPCU controlled the morphology and continuous development of PBAT/TPS/PPCU blends. The increase of PPCU led to the formation of different phase morphologies of the PBAT/TPS/PPCU blends, including “island‐sea,” “quasi‐co‐continuous,” and “co‐continuous” structures. This phase transformation of PPCU emerges as a pivotal driver in the improvement of mechanical properties, resulting in a substantial enhancement from 23.4/24.7 MPa to 37.7/35.6 MPa. Furthermore, the addition of 40%PPCU led to a remarkable 29.6% reduction in the water vapor permeability of the PBAT/TPS/PPCU film. Finally, the increase of PPCU can improve the aging resistance of PBAT/TPS/PPCU films. The films exhibit good mechanical properties and barrier performance, indicating PBAT/TPS/PPCU film potential as environmentally viable substitutes for conventional plastics in the packaging domain.

Energy-Efficient Nanostructured Ion Exchange Membranes from Functionalized Poly (2,6-Dimethyl-1,4-Phenylene Oxide)

Highly energy efficient and ion permeable ion exchange membranes are in high demand in many modern sectors to clean water, transform energy, and store energy in devices like electro-dialyzer, fuel cells, and batteries. However, greater resistance and reduction in ion permeation of conventional membranes dictate the desire for nanostructured functional ion exchange membranes. This project proposes the fabrication of ion exchange membranes using electroactive nanostructured polyaniline incorporation into ion exchange materials, electrostatically interaction between polymer and nanostructured electroactive material overcomes the problem of high resistance and less ion permeation. Solution casting and post-drying techniques are used for membrane casting. Nanostructured electroactive material helps to increase ionic conduction thus reducing 17% resistance for functional cation exchange membrane (FCEM) and 12% for functional anion exchange membrane (FAEM) also assisting to increase ion permeation. Hydrophilic nanostructured polyaniline electroactive material holds more water and increases water uptake. Cross-linking increases stability as well as reduces 17% and 8% swelling degrees for FCEM and FAEM respectively. Besides the electrochemical property offers an increase limiting current density of 38%, 23% for FCEM and FAEM respectively, and 19% higher desalination performance than non-nanostructured sulfonated polyphenylene oxide (CEM) and quaternized polyphenylene oxide (AEM) membranes.

Thermo‐mechanical performance of wolframite mineral reinforced siloxane‐modified epoxy‐based intumescent coating for structural steel

AbstractThis study investigated the effects of wolframite on the fire resistance and adhesion strength of intumescent fire‐retardant coating (IFRC) using a siloxane‐modified epoxy binder. The modification of bisphenol A epoxy was confirmed via Hydrogen‐Nuclear Magnetic Resonance Analysis. The IFRC samples were developed with wolframite (0.25–2.0 wt%) and evaluated for Thermogravimetric analysis (TGA), fire resistance test, furnace fire test for char expansion, morphology and chemical composition, adhesion test and water immersion test. This study identified a coating formulation containing 2.0 wt% of wolframite that showed 57.2% improvement in the residual weight, substrate temperature of 176.7°C and produced a compact char. Field Emission Scanning Electron Microscopy showed that the addition of wolframite reduced pore size thereby increasing the char strength. X‐ray diffraction identified iron neodymium compounds in the char layers, which lowered the pore size resulting in lower substrate temperature. X‐ray photoelectron spectroscopy indicated that the antioxidant capability and the carbon content were increased by 6.9% and 50.3% respectively. The adhesion strength was reduced, however, was within the industrial standards of 2.07 MPa. The water immersion test showed a maximum 66.7% reduction (WF2.0) in the water permeation through the coating.

Influence of coupled dissolution-precipitation processes on the pore structure, characteristics, and evolution of tight sandstone: A case study in the upper Paleozoic reservoir of Bohai Bay Basin, eastern China

Due to the limitations of pore throat characterization techniques, in-depth studies on the evolution and influencing variables of tight sandstone reservoirs remain lacking, despite the importance of pore structure in evaluating their storage and seepage capacities. In this study, the effect of coupled dissolution–precipitation on the heterogeneity of the pore structure of tight sandstone was investigated using advanced techniques in conjunction with traditional geochemical analyses. The primary reasons for the variability in tight sandstone pore structure were different diagenetic processes and tectonic evolution. In tight sandstones, numerous burial phases led to a significant loss of porosity. However, tight sandstones that have been successively leached by meteoric water and deep burial organic acid have improved secondary pore space due to Yanshan tectonic uplift and Himalayan tectonic burial. The redistribution or blockage of pore space can occur as a result of dissolved material migrating and re-precipitating in tight sandstones that have been deeply buried and altered by organic acidic fluids. Furthermore, nuclear magnetic resonance cryoporometry and nuclear magnetic resonance experiments were used to provide precise and accurate quantitative analysis for discussing the evolution of pore structure by complex dissolution–precipitation process within the pore scale. The formation of good pore structure was mainly dependent on the increase in pore volume generated by dissolution in the submicron and micron range (less than 10 μm). Due to interfacial energy effects, authigenic minerals precipitated preferentially in macropores, resulting in a preponderance of microporosity and small changes in porosity but at least an order of magnitude reduction in permeability. This study provides a reliable reference for genesis analysis and evaluation of tight sandstones as well as a new perspective for understanding the formation and evolution of complex pore structures.

Diabetic Nephropathy: Pathogenesis and Drug Delivery System

Diabetic nephropathy is the leading cause of chronic kidney disease. The pathogenesis of diabetic nephropathy consists of four main pathways that indicate intracellular metabolic abnormalities identified in diabetic nephropathy, namely the activation of polyol and protein kinase C pathways, formation of advanced glycation end products, increased oxidative stress, and intraglomerular hypertension. Conventional treatment approaches for diabetic nephropathy that have been through clinical trials are, among others, the use of glucose-lowering agents, reduction of blood pressure, reduction of capillary permeability, and antioxidants. Although such treatments have been proven to slow the severity of diabetic nephropathy which leads to chronic kidney failure, their effectiveness does not cure diabetic nephropathy in patients. Thus, the modification of drug delivery systems and the widely-performed gene therapy need to be reviewed for their effectiveness with the previous treatments of diabetic nephropathy. This review article discusses the perspective of implementing the most effective diabetic nephropathy treatment system in order to achieve the therapeutic goals of diabetic nephropathy. The modification of drug delivery system and the gene therapies are expected to be able to increase the effectiveness of the drugs and guarantee their safety. The characteristics of the therapeutic targets in each kidney cell need to be understood more deeply so that the therapeutic goals can be achieved. It is hoped that the testing in the clinical phase of diabetic nephropathy by modifications of the drug delivery system and gene-based therapies will be widely carried out in the future.

Study of structural characteristics of hydrocarbon reservoir pore space based on X-ray computed tomography images

Digital studies of pore space and internal structure of hydrocarbon reservoir were conducted on the basis of multiscale X-ray computed tomography images and the analysis of heterogeneities, cavernosity, fracturing and bedding in the rock. Main results. 3D models of rock pore space were created on the basis of computed tomography images through segmentation. Porosity estimation based on the digital approach was performed. It was shown that the digitally obtained data are in good agreement with the results of laboratory measurements. Analysis and visualization of the structure of the main filtration channels in the rock were performed. Pore size distributions in the specimen were obtained, and 3D visualization of the largest pore size was shown. Conclusions. The pore space characteristics obtained on the basis of tomographic approach are valuable data for filling reservoir models and can be used in solving the problems of permeability reduction during different kinds of reservoir impacts. Application of the obtained results in combination with geomechanical tests of rocks is intended to expand existing approaches to complex analysis of core material of reservoirs, as well as to supplement and refine mathematical and operational models of the studied objects.

Reduction in Water Permeability of a Penetrating-Sealer-Incorporated Liquid Deicer

Various efforts have been made to minimize the corrosion damage of deicer. However, due to the nature of the deicer that needs to lower the freezing point, the concrete damage due to the repeated freeze-thaw cycle caused by the penetration of the deicer solution into the pores of the concrete could not be fundamentally suppressed. Therefore, a basic study was conducted to minimize the deterioration of concrete by suppressing the water permeability of the concrete surface with penetrating sealer incorporated deicer. Dynamic light scattering and zeta-potential analyses were performed to evaluate the mean diameter and degree of dispersion of the suspension in the aqueous solution of the prepared liquid deicer. Experiments confirmed the water permeability to be 44%–58% that of the untreated control group, and the mass of certain concrete specimens after freeze–thaw cycling tests tended to increase. In addition to the reduction in water permeability, in this study, an increase in the mass of the specimen in repeated freeze thaw cycle was confirmed, which is Liquid deicers with penetrating sealers have the potential to improve the durability and reduce the deterioration of concrete.

Novel resin-based material containing β-tricalcium phosphate nanoparticles for the reduction of dentin permeability

ObjectivesTo synthesize and characterize a novel dentin adhesive containing Beta-Tricalcium Phosphate (β-TCP) nanoparticles and test its ability to reduce dentin permeability (dP). MethodsExperimental adhesives were prepared by mixing Bis-GMA, TEGDMA, HEMA (50/25/25 wt.%), photo-initiators, and inhibitors. The following groups were tested: Experimental adhesives without β-TCP (Exp.); with 10 wt.% β-TCP (Exp.10 wt.% β-TCP); with 15 wt.% β-TCP (Exp.15 wt.% β-TCP), Scotchbond Multi-Purpose (SBMP) and Clearfil SE Protect Bond (CFPB). Degree of conversion (DC%, 10 and 20 s); Flexural Strength (FS), Knoop Hardness (KHN), and Cell Viability (OD%) tests were performed. dP was evaluated by hydraulic conductance, using human dentin disks (n=12), at three-time intervals: post-EDTA (T0); post-treatment (T1); and post-erosion/abrasion cycling (T2). Data were statistically analyzed (α=0.05). ResultsFor all groups, exposure time for 20 s presented a higher DC% than for 10 s. For FS, filled adhesives did not differ from unfilled and from CFPB. Experimental adhesives did not differ among them and showed lower KHN than the commercial products. Cell viability did not differ among adhesives, except Exp. 15 wt.%, which showed lower OD% than Exp., Exp. 10% and, CFPB. For dP, only Exp.10 and 15 wt.% β-TCP did not present difference between the times T1 and T2. After cycling, Exp.10 wt.% β-TCP presented lower permeability than Exp. and CFPB. ConclusionsThe incorporation of 10 wt.% β-TCP nanoparticles into the resin-based dental material did not affect its mechanical properties and biocompatibility, and promoted the greatest reduction in dentin permeability, sustaining this effect under erosive/abrasive challenges. Clinical significanceA novel resin-based dental material containing β-TCP nanoparticles was able to reduce dentin permeability, maintaining its efficacy after erosive/abrasive challenges. The synthesized material did not affect dental pulp cell viability and might be promising for other conditions that require dental remineralization, such as tooth wear and dental caries.

An Experimental Study on Modified Concrete Using Partial Replacement of Gravel and Admixtures

Abstract: This study aims to test a concrete specimen with replacement partially of 15 % of the coarse aggregate by pieces of tires and volcanic aggregates and reduce 5% of the water/cement ratio by substituting with 4% percentages of styrene butadiene rubber (SBR) and 1% of superplasticizer. The main concrete components (cement: sand: gravel) were used in weight ratios (1:1.5:3) and a water to cement 0.45 was used and it was considered as a reference sample (Mix1). A water to cement ratio 0.40 was depended for the modified mixtures. Samples were cast for testing the compression strength with sizes 150 ×150 ×150 mm for ages 7 and 28 days. the absorption rate, with a size of 100 ×100 ×100 mm at age 28 days. Moreover, 150 ×150×150 mm for depth of penetration test at the age of 28 days. Briefly, the observed results were exhibited that the partial replacement of normal aggregate in concrete with volcanic aggregate affects negatively on the workability, so 4% of the polymer SBR and 1% of the superplasticizer have improved the workability. The improvement in the workability of concrete contributed to reducing the ratio of water to cement required for mixing compared to ordinary concrete, and this in turn led to an improvement in performance of hardened concrete. In addition, the reduction of the permeability level. The results also illustrated that the replacement of the gravel in the modified mixtures (Mix 3 and Mix 2) reduces the weight of hardened concrete by (10-12%) and (7-9%) compared with conventional concrete, respectively, which makes it suitable for use in mediumweight concrete applications. Moreover, it can be concluded that the strength properties of the modified mix with volcanic aggregate improved by 19-20% compared to that of the unmodified concrete. While the modified concrete by cutting tires showed significant deterioration in the concrete's resistance 21% despite the reduction of concrete permeability.

Stress sensitivity of permeability in high-permeability sandstone sealed with microbially-induced calcium carbonate precipitation

Microbially induced carbonate precipitation (MICP) catalyzed by S. pasteurii has attracted considerable attention as a bio-cement that can both strengthen and seal geomaterials. We investigate the stress sensitivity of permeability reduction for the initially high-permeability Berea sandstone (initial permeability ∼110 mD) under various durations of MICP-grouting treatment. The results indicate that after 2, 4, 6, 8 and 10 cycles of MICP-grouting, the permeabilities decrease incrementally by 87.9%, 60.9%, 38.8%, 17.3%, and then 5.4% compared to the pre-grouting condition. With increasing the duration of MICP-grouting, the sensitivity of permeability to changes in stress gradually decreases and becomes less hysteretic. This stress sensitivity of permeability is well represented by a power-law relationship with the coefficients representing three contrasting phases: an initial slow reduction, followed by a rapid drop, culminating in an asymptotic response. This variation behavior is closely related to the movement and dislocation of the quartz framework, which is controlled by the intergranular bio-cementation strength. Imaging by scanning electron microscopy (SEM) reveals the evolution of the stress sensitivity to permeability associated with the evolving microstructures after MICP-grouting. The initial precipitates of CaCO3 are dispersed on the surfaces of the quartz framework and occupy the pore space, which is initially limited in controlling and reducing the displacement between particles. As the precipitates continuously accumulate, the intergranular slot-shaped pore spaces are initially bonded by bio-CaCO3, with the bonding strength progressively enhanced with the expanding volume of bio-cementation. At this stage, the intergranular movement and dislocation caused by compaction are reduced, and the stress sensitivity of the permeability is significantly reduced. As these slot-shaped pore spaces are progressively filled by the bio-cement, the movement and dislocation caused by compaction become negligible and thus the stress sensitivity of permeability is minimized.

Effectiveness and tolerance of multicorrective topical treatment for infraorbital dark circles and puffiness.

Treatment of infraorbital dark circles and under-eye puffiness is challenging due to its multifactorial nature and lack of broadly applicable, effective treatments. A daily skincare treatment option that is multimodal, effective, and tolerable across a broad patient population is an unmet need. A multicorrective topical eye cream (MTEC) formulated with Tetrahexyldecyl (THD) ascorbate (vitamin C), prebiotic Inula Helenium, bioavailable peptides, botanical extracts, chrysin, and caffeine is hypothesized to improve the appearance of infraorbital dark circles and under-eye puffiness by targeting microvasculature congestion and permeability, melanin accumulation and hemoglobin degradation-related pigmentation, and skin health. An IRB approved, open-label, 12-week clinical study set out to evaluate the efficacy and tolerability of the MTEC across a broad patient population including varying ethnicities and Fitzpatrick Skin Types (FST). Female subjects (n = 40) ages 35-60 years old, with moderate-to-severe under-eye dark circles, moderate under-eye puffiness, and mild-to-moderate fine lines were enrolled into the study. Objective (Chromameter, VISIA® imaging, and Laser Doppler) and subjective assessments (clinical grading and self-assessment questionnaire) were conducted at baseline and post-baseline timepoints. Thirty-seven subjects completed the study, and the MTEC efficaciously demonstrated short-term and long-term improvements in objective and subjective assessments across a broad patient population. Specifically, the MTEC demonstrated significant improvement of infraorbital dark circles, mainly by the reduction in microvasculature congestion and permeability, melanin, and hemoglobin degradation-related pigmentation. Topical application of the MTEC may offer an effective and tolerable treatment option for infraorbital dark circles and puffiness.