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Abstract Many historic buildings are at serious risk of deterioration due to changes in the moisture content of the soil under the buildings. Based on the typical deterioration problems of the Grand Deliverance Hall and the cultural relics in the hall, this study analyzes and concludes that the main factor affecting the generation and development of deterioration is groundwater erosion through environmental monitoring and geotechnical engineering investigation. The impact of changes in moisture content on the water-holding properties and pore distribution of the soil under the cultural-relics buildings was further assessed. Then, combined with the soil property, our study provides a novel and effective way to monitor and reflect the water-holding properties of the soil using electrochemical detection. The connected pore resistance and matrix suction decrease with the increase in the moisture content, both showing a power function law. Changes in moisture content cause changes in the thickness of the double electric layer, which in turn affects the connected pore resistance and matrix suction of soil. The greater the connected pore resistance, the greater the matrix suction and the water holding capacity. Finally, based on the research of this study and the conservation ideology of cultural relics that respects the original and minimizes intervention, protection recommendations to prevent groundwater erosion are proposed in order to provide guidance for future research. Graphical Abstract

Lime is a widely used construction and building material. As an alkali activator, lime can reduce costs, improve safety of on-site construction, and ensure environmental benefits. In this study, the effects of different lime contents on the physicomechanical characteristics and the hydration properties of circulating fluidized bed fly ash-blast furnace slag-based cementitious materials (CBCM) were evaluated. The results revealed that flowability and setting time of CBCM decreased with the increasing lime content. The mechanical properties first showed an increasing trend and then declined, achieving their optimal levels at 20 % lime content. Similar to the mechanical properties, the density of CBCM increased first and then decreased with the increase of lime content, enriching its maximum at the same lime amount. The main hydration products of CBCM are ettringite and C-(A)-S-H gel. Ettringite is mainly generated in large quantities within 3 days, which is the main reason for the early strength of CBCM. The highest reaction degree of calcium hydroxide was obtained at the lime content of 20 %, and a significant amount of dense foil-like C-(A)-S-H gel was formed. The calcium hydroxide precipitated once the lime content exceeded 20 %. The hydration reaction was blocked, and the hydration products were relatively reduced.

Purposes As the "world's oldest overpass", the Flying Bridge across Fish Ponds in Jinci Temple highlights the cultural characteristics of ancient buildings in Shanxi. Methods In this paper, the compressive strength of the stone pillars of the Flying Bridge across Fish Ponds in Jinci Temple was tested with the rebound meter. AutoCAD software was used for three-dimensional modeling according to the mapping paper, and Abaqus finite element analysis software was used to simulate and analyze the overall stability under static load and seismic action. Findings The results show that under static action, for the Flying Bridge across Fish Ponds, the stress of the components is much less than the allowable value, and the settlement of the foundation is small and tends to be stable. Under the action of earthquake, the structural force is uniform and symmetrical, the top surface displacement is the largest, the third main stress of the stone column is mainly concentrated on the foot and the top of the column, and along the seismic wave loading direction, the oblique section develops, the stress is also less than the allowable value, and has good seismic stability. The results of this work can provide a reference for future conservation work of the Flying Bridge across Fish Ponds.

This study utilizes polymers based on coal gangue and blast furnace slag to solidify engineering slurry with high silt content. Response surface methodology was employed to investigate the effects of polymer composition, alkali activator modulus, and coal gangue calcination temperature on the unconfined compressive strength of stabilized soil. Additionally, the study comprehensively characterized the thermal stability, pore structure, molecular bonds, mineral composition, and micro-morphology of the stabilized soils, and explored the mechanisms governing their strength development. The results demonstrate that the highest strength of stabilized soils is achieved with a slag to coal gangue ratio of 2.5:7.5, a water glass modulus of 1.2, and a coal gangue calcination temperature of 750°C. Formation of calcium-aluminum-silicate-hydrate (C-A-S-H) and sodium-aluminum-silicate-hydrate (N-A-S-H) contributes significantly to the strength development. The presence of slag promotes early strength through C-A-S-H formation, while coal gangue facilitates N-A-S-H formation, supporting later-stage strength development by filling micropores. By applying alkali-activated calcined coal gangue-slag based cementitious materials to solidify engineering slurry, this research not only elucidates the mechanism of alkali-activated calcined coal gangue-granulated blast furnace slag in slurry solidification but also promotes the utilization of industrial solid waste, providing new insights for environmental protection and resource recovery.

Purposes This work is conducted to achieve the objectives of carbon emission reduction and resource utilization of solid waste. Methods Geopolymer concrete was prepared from red mud and coal-metakaolin, and the effect of four factors on its mechanical properties was investigated with an orthogonal test method. Findings The water-binder ratio was found to have a significant effect on the strength of the geopolymer concrete, followed by Na2O/H2O, while the curing conditions and the aggregate-binder ratio have lesser effect, according to the ANOVA. On the basis of the experimental results, the mathematical model of compressive strength and splitting tensile strength of geopolymer concrete was established, and the fitting effects of the equations were favourable. Further analysis obtained the optimal ratio of geopolymer concrete, and the compressive strength and splitting tensile strengthes of the cube specimens cured for 28 d were 43.6 MPa and 2.87 MPa, respectively. Then, the pore structures of the geopolymer concretes with different W/B ratios were characterised with low-field NMR tests. The results indicate that the geopolymer concrete is predominantly microporous internally. The increased content of evaporable free water increases the porosity and coarsens the pore structure, which macroscopically manifests as a reduction in strength of the material. This study can provide some theoretical guidance for the promotion and engineering application of geopolymer concrete.

In order to promote energy conservation and facilitate the utilization of solid wastes, red mud, coal metakaolin, and alkaline activators were used as main raw materials to prepare red mud-coal metakaolin based geopolymer (RCG). The effects of glass fiber, basalt fiber, polypropylene fiber, and polyvinyl alcohol fiber on the compressive strength, peak strain, elastic modulus, compressive toughness, energy absorption, flexural strength, and microstructure of RCG were investigated. The toughening mechanism of four kinds of fiber on RCG was expounded, and the results indicate that incorporation of fibers can enhance the mechanical properties of RCG and improve its toughness and ductility. Among them, basalt fibers and polyvinyl alcohol fibers have similar effects on strength enhancement, but polyvinyl alcohol fibers can effectively change the brittle failure modes of RCG and enhance the compression toughness and energy absorption capacity of RCG. Through microscopic morphology analyses, polyvinyl alcohol fiber has high moisture regain, and the bonding effect with the matrix was found to outperform other fibers, so the physical and mechanical properties of RCG are improved better.

Lamprey underwent biliary atresia (BA) at its metamorphosis stage. In contrast to patients with BA who develop progressive disease, lamprey can grow and develop normally, suggesting that lamprey has several adaptations for BA. Here we show that adaptive changes in bile acid and cholesterol metabolism are produced after lamprey BA. Among 1102 differentially expressed genes (DGEs) after BA in lamprey, many are enriched in gene ontology (GO) terms and pathways related to steroid metabolism. We find that among the DGEs related to bile acids and cholesterol metabolism, the expression of cytochrome P450 family 7 subfamily A member 1 (CYP7A1), sodium-dependent taurine cotransport polypeptide (NTCP) are significantly downregulated, whereas nuclear receptor farnesoid X receptor (FXR), multidrug resistance-associated protein 3 (MRP3), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), sterol O-acyltransferase 1 (SOAT1), and ATP binding cassette subfamily A member 1 (ABCA1) are remarkably upregulated. The changes in expression level are also validated by RT-qPCR. Furthermore, the level of high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) in juvenile serum is higher compared to larvae. Taken together, the findings collectively indicate that after BA, lamprey may maintain bile acids and cholesterol homeostasis in liver tissue by inhibiting bile acids synthesis and uptake, promoting its efflux back to circulation, and enhancing cholesterol esterification for storage as lipid droplets and its egress to form nascent HDL (nHDL). Understanding the possible molecular mechanisms of lamprey metabolic adaptation sheds new light on the understanding of the development and treatment of diseases caused by abnormal bile acid and cholesterol metabolism in humans.

The wetting deformation of coarse-grained materials can seriously affect the safety of earth and rock dams during initial water storage. The wetting model formulas are expressed in various forms and have complex parameters. Only a small amount of test data is fitted by mathematical statistics, and the universality of the obtained wetting model is unknown. Duncan-Chang E-B constitutive model cannot accurately reflect the wetting deformation characteristics of coarse-grained materials. Through the double-line wetting test of coarse-grained materials, the wetting model proposed by predecessors was verified and analyzed. Based on the indoor wetting test data, the parameters of each wetting model were fitted to analyze the accuracy of each wetting model in describing the wetting deformation characteristics. According to the P-Z model in the elastic-plastic theory and the wetting model formula, the P-Z wetting model is established, and the BP artificial neural network is introduced to establish the artificial neural network wetting deformation prediction model based on the P-Z model. The results show that the relationship between wetting axial strain and wetting stress level is best expressed by the exponential function. The relationship between wetting volumetric strain and wetting stress level is best described by Cheng’s linear function. The relative errors between the predicted and experimental values of the proposed neural network prediction model are all within 6%. The relationship between wetting axial strain and wetting stress level is exponential function, and the relationship between wetting volumetric strain and wetting stress level is linear function. The P-Z wetting model proposed in this research can better reflect the wetting deformation characteristics of coarse-grained materials under complex stress paths. The artificial neural network prediction model based on P-Z wetting model is more reliable and accurate, which can meet the prediction requirements of actual engineering for wetting deformation of coarse-grained materials.

The exploitation of underground space is accompanied by complex geotechnical problems. The development of electromagnetic exploration technology provides a new perspective for preventing and avoiding these problems. In this work, electrochemical impedance spectroscopy (EIS) was used to test the single-phase and mixed-phase medium. Based on the unsaturated soil theory and the dual-water conductivity theory, an equivalent circuit model to describe the electrochemical characteristics and microstructure of silty soil with temperature changes through comparative research. The results indicate that the resistance of near-water layer is not affected by temperature, the resistance of silty soil increases mainly results from the influence of the far-water layer until which increases significantly after freezing. The capacitance change of silty soil is mainly affected by the slowing down of the orientation movement of polar molecules in the far-water layer. Based on the fitting data, a mathematical model for calculating the unfrozen water content of frozen soil was proposed, which reasonably verified the relationship between the unfrozen water content and electrical resistance. By improving the testing conditions of electrochemical impedance spectroscopy, this method may provide new insights for future research of soil electromagnetic testing technology.

In this paper, the solidification of Cu2+-contaminated kaolin by high belite sulphoaluminate cement (HBSC) combined with red mud (RM) and fly ash (FA) was investigated. The effects of solidification/stabilization (S/S) and its electrochemical responses were experimentally explored by mixing RM and FA as the main raw materials with small amounts of low-energy HBSC and quicklime serving as solidifiers of heavy metal contaminated soil. The solidification mechanism of the solidifier on Cu2+ and its solidification effect were then systematically investigated by analyzing the unconfined compressive strength (UCS) of the solidified body, toxic leaching, permeation characteristics, and surfaces morphologies. The study of the electrochemical response of the solidified body during the solidifying and remediation process allowed the development of an evaluation method for repairing the effect of Cu2+-contaminated kaolin based on electrochemical impedance spectroscopy (EIS). The results showed that the strength, impermeability, and leaching toxicity of solid waste co-HBSC solidifying of contaminated soil met industrial requirements. The incorporation of low energy consumption HBSC generated a mass ratio of RM to FA of 8:2 with the best solidification effect. Heavy metals can be absorbed by chemical precipitation, displacement reactions, and encapsulation by hydration gels. In addition, the electrochemical impedance characteristics of the solidified bodies were found consistent with the conventional evaluation of the solidification effect. In sum, HBSC synergistic solid waste solidifier looks very promising for use in the S/S remediation of Cu2+-contaminated soil.

The main purpose of this work was to study a new method for evaluating the solidification of contaminated soil based on electrochemical impedance spectroscopy (EIS). To explore how the EIS parameters were affected by the pore structure and mesostructure of the cured system, the physical and mechanical properties, leaching toxicity, microstructure, and EIS of the stabilized contaminated soil were tested after 7, 28, 60, and 90 days of curing. Based on the EIS results, a physical and equivalent circuit model of the stabilized contaminated soil's impedance response was established to reveal the mechanism of binder-heavy metal ion-soil interaction. The results showed that as the red mud (RM)-fly ash (FA) mass ratio and curing age increased, the strength and structural compactness of the solidified body also increased. The best curing effect was achieved with an RM-FA mass ratio of 7:3 after curing for 90 days. The equivalent circuit model of the solidified body obtained by EIS was Rs (Q1 (Rct1W) Q2Rct2). The pore solution resistance Rs, solid-liquid interface ion transfer resistance Rct 1, and unconfined compressive strength (UCS) qu all showed an increasing trend with increasing RM-FA mass ratio and increasing curing time. Fitting the model demonstrated that both Rs and Rct1 were closely correlated with the strength of the solidified bodies. These conclusions were further verified by scanning electron microscope (SEM) experiments. Overall, this work demonstrates that the strength characteristics of solidified bodies can be evaluated by EIS and reveals the microscopic mechanism of the solidification of Cu2+-contaminated soil.

In this paper, the electrochemical corrosion behavior of X70 steel in saline soil under capillary water was simulated by a Geo-experts one-dimensional soil column instrument. A volumetric water content sensor and conductivity test were used to study the migration mechanism of water and salt (sodium chloride) under the capillary water. The electrochemical corrosion behavior of the X70 steel in the corrosion system was analyzed by electrochemical testing as well as the macroscopic and microscopic corrosion morphology of the steel. The test results showed that the corrosion behavior of X70 steel was significantly influenced by the rise of capillary water. In particular, the wetting front during the capillary water rise meant that the X70 steel was located at the three-phase solid/liquid/gas interface at a certain location, which worsened its corrosion behavior. In addition, after the capillary water was stabilized, the salts were transported with the capillary water to the top of the soil column. This resulted in the highest salt content in the soil environment and the most severe corrosion of the X70 steel at this location.

Let {r(n)}n≥0 be the Rudin-Shapiro sequence, and let ρ(n):=max{∑j=ii+n−1r(j)∣i≥0}+1 be the abelian complexity function of the Rudin-Shapiro sequence. In this note, we show that the function ρ(n) has many similarities with the classical summatory function Sr(n):=∑i=0nr(i). In particular, we prove that for every positive integer n, 3≤ρ(n)n≤3. Moreover, the point set {ρ(n)n:n≥1} is dense in [3,3].

We study the Hankel determinant generated by a singularly perturbed Jacobi weight w(x,s):=(1−x)α(1+x)βe−s1−x,x∈[−1,1],α>0,β>0s≥0. If s=0, it is reduced to the classical Jacobi weight. For s>0, the factor e−s1−x induces an infinitely strong zero at x=1. For the finite n case, we obtain four auxiliary quantities Rn(s), rn(s), R˜n(s), and r˜n(s) by using the ladder operator approach. We show that the recurrence coefficients are expressed in terms of the four auxiliary quantities with the aid of the compatibility conditions. Furthermore, we derive a shifted Jimbo–Miwa–Okamoto σ-function of a particular Painlevé V for the logarithmic derivative of the Hankel determinant Dn(s). By variable substitution and some complicated calculations, we show that the quantity Rn(s) satisfies the four Painlevé equations. For the large n case, we show that, under a double scaling, where n tends to ∞ and s tends to 0+, such that τ:=n2s is finite, the scaled Hankel determinant can be expressed by a particular PIII′.

In this study, the effects of high-sulphur fly ash on the properties of lightweight cement-treated materials (LCMs) immersed in sodium sulphate solutions were studied. The unconfined compressive strength of LCMs corroded by sulphate was tested. The microscopic properties were characterised by X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The results show that high-sulphur fly ash has an adverse effect on the structural strength of LCMs after corrosion, but when the content of fly ash is less than 75%, the effect of fly ash on the strength is small. A small amount of high-sulphur fly ash can improve the density of the material structure; the internal pore structure of LCMs provides space for the growth of ettringite and other corrosive substances and relieves the expansion pressure. LCMs mixed with high-sulphur fly ash have a certain resistance to sodium sulphate corrosion.

Primary vegetation covering was a rising technology for restoring surface diseases of earthen sites. However, the mechanism of herbs on the infiltration, runoff and sediment producing were unclear. In the in-situ artificial rainfall experiments in Jinyang Ancient City, the effects of different plant growth conditions in different periods on earthen sites slopes were compared with. The conclusions were as follows. The rainfall of 13.4mm was the threshold for changes in soil volume moisture content at depth in 0.5m. The fluctuation amplitude and the peak migration rate of soil moisture were positively correlated with soil porosity. The time of initial peak of soil surface volume moisture content was negatively correlated with its initial value before rainfall and rainfall intensity. The rainfall intercepted by plants was in a dynamic equilibrium state. Root splitting fissures and unstable water storage spaces not only had the function of water storage, but also had the one of reducing runoff velocity. For fresh herbs and withered herbs, interception yield before runoff producing Q0 was negatively correlated with runoff starting time T0, and the interception effect of withered herbs was better than fresh ones. The impact of rainfall intensity on the percentage of runoff production Cro of fresh herbs decreased over time, and the impact of rainfall intensity on the percentage of sediment production Csy of fresh herbs increased over time. Fresh herbs and withered herbs enhanced the erosion resistance by intercepting and increasing the infiltration rate of rainfall and reducing the kinetic energy of rainwater. The stems and leaves blocked sunlight, regulating and creating a relatively stable microclimate environment to reduce evaporation of primary vegetation covering. It confirmed that fresh herbs and withered herbs had regulatory effects on conservation of earthen sites in Jinyang Ancient City. It would provide data support for the protection of earthen sites in large scales. [ABSTRACT FROM AUTHOR]

Metal phthalocyanine, a synthetic porphyrin-like compound, has several applications in catalysis. Supported metal phthalocyanine catalysts have attracted increasing attention. In this study, glutaraldehyde (GA) was used for modifying polyvinyl alcohol (PVA) nanofibers by acetalization to improve the water resistance. Subsequently, cobalt tetra (2,4-dichloro-1,3,5-triazine) aminophthalo-cyanine (Co-TDTAPc) was prepared and reacted with OH groups on the surface of the PVA nanofibers to produce Co-TDTAPc–PVA nanofibers. The water resistance test results show that the GA-treated nanofibers demonstrate no significant change in fiber appearance after being soaked in water for 24 h, thus indicating the excellent water resistance of the PVA nanofibers. Moreover, Co-TDTAPc–PVA nanofibers considerably accelerate the degradation of azo fluorescent peach red in the hydrogen peroxide aqueous solution system, and the degradation rate exceeds 98% in 60 min. Furthermore, the nanofibers maintain high catalytic activity after five cycles of tiontesting. These findings indicate that the modified Co-TDTAPc–PVA nanofibers as a navel supported catalyst have a potential application in dye wastewater treatment. [ABSTRACT FROM AUTHOR]

The size of soil particles can change the conducting channels through which an electrolyte solution flows in a soil mass, which has an influence on the tortuosity of pores in soil mass, thus further changing the conductivity of the soil mass. By carrying out laboratory tests, the influences of moisture and particle size of sandy soil on the resistivity of sandy soil polluted with sodium chloride were evaluated. Furthermore, the models for analyzing relationships linking the resistivity of sandy soil polluted with sodium chloride with moisture and particle size of sandy soil under experimental conditions were separately established. The test results showed that the resistivity of sandy soil polluted with sodium chloride at different moisture contents linearly decreases with increasing particle size. Based on the Archie resistivity model, the influence of particle size on the resistivity of polluted sandy soil was explored by carrying out laboratory tests. On this basis, the formula (ρ = [(3 - 2ω)(3ω - 35)][(ω + 3) + g]) for predicting the resistivity of polluted sandy soil with changes in moisture content and the particle size of the system of sandy soil is established, where ω, g, and ρ separately refer to the moisture content, particle size, and resistivity of the system, respectively. Finally, by analyzing the influence of particle size on tortuosity, a resistivity model (ρ=Aρωτe(θ)θ) for analyzing the influence of tortuosity on the resistivity of sandy soil is established, where τe(θ), θ, and ρω separately refer to tortuosity, porosity, and resistivity of pore water, respectively. [ABSTRACT FROM AUTHOR]