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Polyvinyl alcohol (PVA) as an additive has been widely concerned in soil improvement. In the past, the consolidation effect of the PVA in various soils showed obvious differences. However, the reasons for the difference remain unclear. Clay mineral and soluble salt are important components of the soil. Therefore, this study mainly discussed the effects of clay mineral and chloride salt on the unconfined compressive strength (UCS) of PVA-treated soil. The results indicated that CaCl2 and MgCl2 significantly increased the UCS of the PVA-treated soil, whereas NaCl decreased the UCS. Illite and kaolinite had little effect on the UCS, while the UCS first decreased and then increased with the increase in the montmorillonite content. When the MgCl2 or CaCl2 content approached 3%, the soil samples cracked after curing at room temperature for 28 days due to the formation of crystalline water, which sometimes decreased the UCS of the samples. According to the results of multiple linear regression, for the effect of the UCS of the PVA-treated soil, MgCl2 > NaCl > CaCl2 > montmorillonite > kaolinite > illite. The effects of clay mineral and chloride salt on the UCS of the PVA-treated soil mainly depended on the changes in the soil structure, hydrogen bonding, and cross-linking reactions according to the results of the microscopic tests. The PVA as a consolidation material is not suitable for the seaside, and it should be applied to the soil with no more than 2% MgCl2 or CaCl2. [ABSTRACT FROM AUTHOR]

In large eddy simulations (LESs) and scalar filtered mass density functions, a gradient diffusion model is generally used for subgrid-scale (SGS) scalar flux modeling. However, this hypothesis is known to generate evident errors under certain conditions, particularly when the counter-gradient scalar transport effect dominates. Herein, a joint subgrid velocity-scalar filtered mass density function (VSGSSFMDF) method is developed to address this problem. The exact FMDF transport equation is derived in detail. Based on the order of the magnitude analysis and simply Langevin model, the FMDF transport equation is modeled, and a system of stochastic differential equations is, thus, proposed. Theoretical derivation and analysis suggest that both the first- and second-order moments are consistent. A compressible mixing layer and hydrogen/air-reactive mixing layer are simulated to verify the proposed method. Based on the diffusion model, a direct numerical simulation and an LES are performed for comparative verification. A generally reasonable SGS velocity distribution is obtained using the proposed VSGSSFMDF method. Consequently, the counter-gradient scalar transport effect is effectively simulated using this method. Overall, the VSGSSFMDF produces better results than the SFMDF and LES in both cases, particularly in the reactive case. [ABSTRACT FROM AUTHOR]

• The spatial features of rammed pits of the Ming Great Wall were explored. • The representative micro slopes with true rammed pit morphology were found by RF. • The shapes and distribution of rammed pits show more regularity than randomness. • The regularity of rammed pits is derived from the standardized ramming technique. • The rounded heads and rough surfaces of rammers are reflected by rammed pit shapes. In Northwestern China, the Ming Great Wall generally involves multiple layers of rammed earth, and rammed pits with regular spatial characteristics are always distributed on the horizontal interfaces between rammed layers. Obviously, the spatial regularity of rammed pits cannot only reflect the level of ramming technique in the Ming dynasty, but also control the geotechnical properties of rammed layer interfaces (RLIs). Hence, in the present study, one typical RLI with visible rammed pits was obtained from the Ming Great Wall in Yongchang County, Northwestern China, and the corresponding point cloud data were collected by 3D scanning technique. Then, this RLI was reconstructed using numerous micro slopes in ArcGIS, and the distribution maps of micro-slope heights, angles, plan curvatures and profile curvatures were produced as well. Based on these distribution maps and Random Forest (RF) algorithm, those micro slopes which can reflect the true rammed pit morphology (called the representative micro slopes) were identified, and ten zones where the representative micro slopes concentrate were selected as effective analysis domains. Furthermore, within effective analysis domains, the contour lines were generated to show the outline features of rammed pits, and the values of micro-slope heights, angles, plan curvatures and profile curvatures were statistically analyzed to reveal the surface features of rammed pits. Moreover, the distribution features of rammed pits were exhibited by their centroid positions, which can be calculated by the corresponding contour line shapes. Ultimately, this study indicates that rammed pits of the Ming Great Wall show more regularity than randomness in terms of geometric shapes and spatial distribution. Concretely, the outlines of most rammed pits approximate the circular or elliptical shapes. All the rammed pit surfaces are rough rather than smooth, and most of them can be mathematically expressed by quadratic polynomial equations. As for the distribution features, rammed pits are overall distributed in the triangular shapes, and distances between the equivalent centroids of adjacent rammed pits range from 8.95 cm to 17.86 cm. These findings prove that standardized ramming technique was applied in the Ming dynasty, resulting in high-quality construction of the Great Wall. Meanwhile, the rammers used to compact earthen materials possess rounded heads. However, the imperfect polishing of rammers and the inevitable operational errors could also lead to slight spatial randomness of rammed pits. [Display omitted] [ABSTRACT FROM AUTHOR]

Earthen sites with important historical, cultural, artistic, social, and scientific values have been seriously damaged. Basal erosion, which is caused by soluble salts, water runoff, and sand-driving wind, is an extremely threatening erosion pattern for earthen sites. A cushion layer which has a damp-proofing function and good physical and mechanical properties can effectively decrease basal erosion. The primary aim of this study is to investigate material selection for the hydrophobic cushion layer for earthen sites in northwest China. The results indicate that cooked tung oil and sticky rice liquid, traditionally used in China, cannot meet the fundamental requirements of sufficient hydrophobicity for the cushion layer. Although polyvinyl alcohol (PVA) solution and tung oil exhibit similar properties in terms of soil hydrophobicity, water vapour permeability, water resistance, surface hardness, and colour difference for samples with 0.0-1.0% content, the PVA solution is significantly better than tung oil in unconfined compressive strength, deformation modulus, wave velocity, and viscosity. Therefore, the PVA solution should be preferentially selected as a hydrophobic cushion layer material according to the results of this work. When the mixing method is adopted, 0.6-1.0% PVA content is the best choice. [ABSTRACT FROM AUTHOR]

Rammed earth ruins can be regarded as a special soil mass made by humans. Generally, the stability of rammed earth ruins is largely controlled by the morphological characteristics of rammed layer interfaces (RLIs), which have not been well studied yet. In this paper, the Yongchang Section of the Ming Great Wall, a representative of rammed earth ruins in northwestern China, was selected as the study area, and morphological data from three typical RLIs were collected uisng a handheld 3D scanner. For each typical RLI, within three concentric analysis domains with different sizes, the spatial characteristics of microslopes were explored by ArcGIS, and the 3D roughness values along eight analysis directions were calculated. Ultimately, this study indicates that the most notable characteristic of RLIs is the morphological regularity provided by the rammed pits. Thus, within the analysis domains employed here, the spatial characteristics of microslopes and 3D roughness values are size-independent overall. Moreover, the distributions of 3D roughness are basically more isotropic than anisotropic. Additionally, minor bumps on the RLIs were formed by construction, fracturing, and weathering, and they contribute to the limited heterogeneity of the RLI morphology. Thereinto, the weathering-induced can further be divided into minor bumps caused by wind erosion and rainfall erosion. On the whole, RLIs that have undergone wind erosion have significantly higher surface hardness values (60–90 HA) than rainfall-eroded RLIs (< 50 HA). [ABSTRACT FROM AUTHOR]

Erosion diseases often appear on the upper part of the Great Wall of China. Low precipitation, intense solar radiation, and severe soil salinization occur in northwest China, and the migration of salt and damage can be described with respect to the rainfall-radiation cycle. Rainfall and radiation conditions were simulated in the laboratory, and reproduced samples were subjected to cyclic experiments to determine salt migration and the damage progress. Surface hardness and ultrasonic velocity were used to measure the surface damage, and the microstructure damage was determined by computed tomography and scanning electronic microscopy. The results show that under the rainfall-radiation cycle, most of the salt in the upper part, including sulfate, migrates to an area 2–3 cm from, while a small part of the salt, including chloride, moves down into the lower half of the sample. In areas where salt is concentrated, the soil density decreases, cracks develop, and a vulnerable zone appears, reducing the surface hardness and ultrasonic velocity. The concentration of salt causing destruction of the soil structure is the main factor leading to erosion of the upper walls of earthen sites. Infiltration of rainwater is required for the migration of soluble sulfate and the damage to soil on the upper wall. Increasing radiation intensity would greatly accelerate the migration of soluble sulfate and damage to the soil structure. [ABSTRACT FROM AUTHOR]

Background: There have been many studies on the relationship between circRNAs and fat deposition. Although the liver is a central organ for fat metabolism, there are few reports on the relationship between circRNAs in the liver and fat deposition. Methods: In this study, we systematically analyzed circular RNAs in the liver of Ningxiang pigs, at four time points after birth (30 days, 90 days, 150 days and 210 days). Results: A total of 3705 circRNAs were coexpressed in four time periods were found, and KEGG analysis showed that the significantly upregulated pathways were mainly enriched in lipid metabolism and amino acid metabolism, while significantly downregulated pathways were mainly related to signal transduction, such as ECM–receptor interaction, MAPK signaling pathway, etc. Short time-series expression miner (STEM) analysis showed multiple model spectra that were significantly enriched over time in the liver. By constructing a competing endogenous RNA (ceRNA) regulatory network, 9187 pairs of networks related to the change in development time were screened. Conclusions: The expression profiles of circRNAs in Ningxiang pig liver were revealed at different development periods, and it was determined that there is differential coexpression. Through enrichment analysis of these circRNAs, it was revealed that host genes were involved in metabolism-related signaling pathways and fatty acid anabolism. Through STEM analysis, many circRNAs involved in fat metabolism, transport, and deposition pathways were screened, and the first circRNA–miRNA–mRNA regulation network map in Ningxiang pig liver was constructed. The highly expressed circRNAs related to fat deposition were verified and were consistent with RNA-Seq results. [ABSTRACT FROM AUTHOR]

• Dissolution of calcite, plagioclase and K-feldspar caused major elemental loss (to solutions) of Na, K and Ca in the BTG. • Weathering patterns were linked to seasonal hydrological changes affected by both reservoir filling and groundwater system. • More evidence for surface illitization of smectite in natural alkaline environments was provided. Alkaline environments are common in arid and semi-arid regions in northwestern China and have preserved quantities of rock heritages along the Silk Road. In contrast to the frequently reported weathering mechanism of stone heritages in acidic conditions, mineral weathering mechanism (especially the transformation mechanism of smectite) in natural alkaline environments still remains to be evaluated. To deepen the understanding of weathering in such an environment, research idea from critical zone science was applied to investigate the element transport and mineral transformation from protolith (interbedded sandstone and conglomerate) to regolith in a world cultural heritage, Bingling Temple Grottoes (BTG), in northwestern China. From geochemical and mineralogical characterizations on boreholes, excavated profiles, fractures and cliff surface, we found that dissolution of calcite, plagioclase (anorthite, albite) and K-feldspar (orthoclase) caused major elemental loss of Na, K and Ca (to aqueous solution) in the BTG, and elements of Mg and Fe mostly retained in solid materials. Characterizations on the cliff surface demonstrated higher extents of element depletion and mineral weathering and lower ultrasonic P -wave velocities in sandstone than in conglomerate, and in the bottom sandstone layers (located in the capillary zone and exposure to rain scouring) than in upper sandstone layers (located in the cave and free of precipitation). The transformation of smectite from protolith to regolith follows the sequential reactions: dehydrated smectie → bihydrated smectite → randomly interstratified illite/smectite → illite. Such transformation pathway is favored by alkaline pH and wetting–drying cycles frequently occurred at the BTG. Typical weathering patterns such as clay swelling damage, efflorescence, salt precipitation, etc., are highly-linked to seasonal changes in the hydrological process influenced by both reservoir construction and groundwater system. Our study provides more evidence for the illitization of smectite in natural alkaline environments and highlights the hydrological impacts on weathering patterns of rock grottoes. [ABSTRACT FROM AUTHOR]

Earthen plasters have been widely used in historical buildings such as grottoes, which have high historical, artistic, scientific, social, and cultural values. In order to study the influence of the material composition of plasters on its physical performance, a total of seven different types of earthen plaster specimens were made using Dengban clay and six admixtures (quartz sand, two types of vegetal fibers, and three types of hydraulic limes), and the surface water absorption properties, hygrothermal properties, surface strength (surface hardness, surface cohesion, and surface impact resistance), color difference, and radial shrinkage of all plasters were systematically investigated and compared. The results show that the addition of sand, vegetal fibers, and hydraulic limes all changed the surface water absorption, thermal conductivity, and water vapor permeability of plaster, and inhibit the radial shrinkage during the curing process. Compared to the other admixtures, sand had the least effect on the overall performance of plasters. Both types of vegetal fibers can greatly improve the impact resistance of plaster surface, but due to the formation of microcracks on the surface of the plaster with wheat straw fibers, its water absorption is much higher than that of the plaster with hemp fibers. The addition of three types of hydraulic limes changed the surface color of the plaster to some extent, and the water repellency of the plaster surface will be enhanced due to the carbonation of hydraulic lime. • The physical performance of seven types of earthen plasters was investigated. • The carbonation process enhances the water repellency of the plasters with hydraulic lime added. • The addition of vegetal fibers has greatly improved the impact resistance of the plaster surface. • The addition of hydraulic lime has an effect on the surface color (ΔE > 3). [ABSTRACT FROM AUTHOR]

Having extremely high artistic, scientific and social values, earthen sites are widely distributed in China and are important human cultural relic resources. Due to accumulated natural erosions (from rain and wind) and human activities (destructive activities of human beings in history and modern times), however, earthen sites have been greatly damaged, and many sections have even been absent, so that they are seriously threatened by extinction. Under these circumstances, acquiring the conservation status of earthen sites is a vital prerequisite for the subsequent targeted protection. In this paper, as a world-renowned heritage site, the castles of the Ming Great Wall located in Qinghai Province were selected as the research object. A novel indicator, namely the linear absent section ratio (L-ASR), was proposed, and its value was classified into five levels to quantitatively characterize the specific conservation status of such sites, including excellent (E) (0–10%), good (G) (10–25%), fair (F) (25–50%), poor (P) (50–75%), and very poor (VP) (75–100%). Based on the assessment results, the castles with excellent status constituted the minimum proportion, while the castles with very poor status represented the largest percentage, reflecting the grave situation of earthen sites. Furthermore, by applying population distribution models to the linear fitting combined with the population density (PD), a positive correlation between PD and L-ASR was obtained to reveal the anthropogenic influence on the destruction of earthen sites. Principal component analysis (PCA) was utilized to provide a far richer understanding of which factors correlate most strongly with deterioration. This study provides a new thought to quantitatively characterize the preservation conditions of earthen sites and also indicates the effect of human activities on the damage of earthen sites from a population density perspective, which is potentially used for the analysis of more various types of architecture with different construction techniques. Hence, this approach is beneficial to the overall damage assessment of earthen sites, and also meaningful to their further preservation and protective planning. [ABSTRACT FROM AUTHOR]

To clarify the sliding mechanism of a landslide, the shear behavior characteristics of slip zone soil are always vital. In the Northwest of China, thousands of landslides generally develop in three main types of slip zone soil, i.e., Quaternary loess, weathered Mesozoic-Cenozoic mudstone, and weathered Mesozoic-Paleozoic phyllite. In the present study, the shear behavior characteristics of these three kinds of slip zone soil were investigated through direct shear tests and their implications for the sliding mechanisms of landslide were also discussed. It was found that, in general, an abrupt failure of loess landslide could be related to the strong strain-softening behavior of loess in the direct shear test, while the ductile shear behavior of weathered mudstone and phyllite coincided with the creep deformation of the corresponding landslides. The residual friction angle of slip zone soil varied with the soil type and its mineral composition, and the lowest residual friction angle about 11.5° could be found in weathered phyllite (SET) with graphite. Compared with the previous research, it is interesting to find that the residual friction angles of mudstone and phyllite in the present study accorded reasonably with the empirical correlations proposed by Wen et al. (2007) for weak rocks in the Three Gorges area, China. [ABSTRACT FROM AUTHOR]

Earthen sites with historical, scientific, social, cultural, and artistic values can be destroyed by weathering. Chemical consolidation is an effective method to protect earthen sites, and organic–inorganic composites are often considered ideal. The primary aim of this study was to investigate the effect of polyvinyl alcohol (PVA) with a high degree of alcoholysis on the expansion and cracking behaviour of quicklime-treated soil. The expansion and surface cracking behaviour of the composite soil were investigated with a Crack Image Analysis System. Changes inside the soil samples were observed and analysed by X-ray computed tomography and ImageJ. The results indicated that the expansion of quicklime-treated soil decreased with increasing PVA content, and the cracking behaviour on the surface was different from the inside of the samples. Surface cracks were significantly weakened when PVA was added to soil with a quicklime content ≤ 5%. As the quicklime content increased to 10% or more, the PVA transformed long and wide surface cracks into short and narrow cracks. The development of internal cracks was not as evident as those developing at the surface. Soil samples with 1.0% PVA had no obvious internal cracks at 0–25% lime content. Samples with 0.5% PVA content had internal cracks only when the quicklime content was ≥ 20%. A mechanism for the cracking phenomenon was proposed considering the results obtained from X-ray diffractometry. Soil particles were cemented together through physicochemical reactions with PVA, and these soil particles shared the expansion resulting from the hydration reaction of quicklime instead of through local expansion. [ABSTRACT FROM AUTHOR]

The Ming Great Wall distributed in Qinghai Province is a significant part of the Great Wall, which is the most world-renowned heritage site in China. However, compared to the Great Wall sections in other provinces, this section has not been systematically researched due to the later complete investigation and not enough attention paid from the public. It is of importance to study the Ming Great Wall Military Defense System (M-GWMDS), as it is the premise and foundation for further systematic researches about the Ming Great Wall. To supplement and improve the whole M-GWMDS in China, the authors researched the M-GWMDS in Qinghai Province from a new perspective, namely the castle-based military settlement. By consulting and summarizing related literature, the architectural features and military functions of castles have been clarified. After that, the castle-based military settlement in Qinghai Province was further analyzed, including its spatial distribution, troops deployment, three defense districts, and the reachable domain of troops. Finally, the authors explored to comprehensively research the military defense system, which contains four elements, i.e., the Great Wall mainline, military settlements, beacon tower system, and the relay system. Such components have made up a close network to defense, attack, and transfer vital information/staff with practical cooperation, which revealed the scientificity and practicability of Chinese ancient military thoughts. This study is helpful to enrich the systematic research on the Ming Great Wall and meaningful to expand the analysis of local history and ethnology of Qinghai Province. [ABSTRACT FROM AUTHOR]

Some of the largest and best-preserved Buddhist art treasure houses in the world, namely the Mogao Grottoes, are located at the northwest edge of the region of the Qinghai-Tibet plateau and are adjacent to the Altun and Qilian mountains, where the geotectonic activity is intense and large earthquakes have occurred. Future earthquakes are one of the major threats to the caves of the Mogao Grottoes; therefore, it is important that their dynamic performance is studied when an earthquake occurs. To understand the dynamic performance of the densely distributed caves under the effect of earthquakes, as well as the long-term stability of the Mogao Grottoes, the stress distribution, deformation characteristics, and peak-acceleration amplification factor were analysed under rare-earthquake conditions using a finite-difference element. The numerical study revealed that the most dangerous state of the caves is the initial time when an earthquake occurs. The obvious tensile stress concentration appeared at the top and the bottom of the caves of the middle floor; the main damage was caused by the shear failure towards the direction of the free face and not by the tensile failure. A large permanent horizontal displacement of the caves occurred after an earthquake, mostly at the densely distributed caves of the middle floor. The acceleration amplification effect of the middle-floor caves was significant; the Fourier amplitudes of the acceleration (which were monitored in all caves) were significantly magnified at the frequencies of 3 ~ 4 Hz and 7 ~ 9 Hz, whereas the Fourier amplitudes of the acceleration which were monitored in the middle-floor caves were almost amplified within the entire frequency range. Although the maximum stress was within the allowed limit and no tensile failure occurred, great permanent inhomogeneous horizontal displacements and large accelerations could have a negative effect on the stability of caves and the preservation of wall paintings. Moreover, it was assumed that the calculation results could serve as a type of guidance and as advice on the preventive protection of the Mogao Grottoes. [ABSTRACT FROM AUTHOR]

The Green-Ampt (GA) model has been widely used to evaluate soil water infiltration. While a simple piston profile is commonly used, the wetting profile of a soil changes during infiltration and a quarter-ellipse has been found to better describe its evolution. This study aims to improve the GA model and discuss the model parameters when the quarter-ellipse profile is utilized. The soil column is divided into three zones: saturated, transient and dry. The variable γ is introduced to express the ratio of the saturated zone depth to the wetting front depth. A modified GA model is derived via mathematical methods, but an exact solution is difficult to obtain. Therefore, a simplified (SGA) model is developed via a segmented method. Compared with the measured results, the SGA model is more accurate than the traditional model. Finally, the model parameters are discussed and a value of γ = 0.5 is recommended. [ABSTRACT FROM AUTHOR]

The Subashi Buddhist Temple Ruins, which contain a lot of coarse-grained soils, have been severely damaged by surface weathering. Modified polyvinyl alcohol (SH) which can improve the mechanical properties of fine-grained earthen ruins has never been reported in the protection of coarse-grained earthen ruins, and thus, it is of great practical significance to investigate the impregnation and consolidation effects of SH solution on coarse-grained soils. First, the characteristic changes obtained by SH impregnation with respect to consolidation radius, impregnation rate, impregnation time, and cumulative impregnation were analysed for soil specimens with different dry densities and grain gradations. Then, disintegration, drying–wetting cycle, and freeze–thaw cycle experiments were carried out, and the results of these experiments were analysed. Finally, the impregnation and consolidation effects of the SH solution were evaluated together. The feasibility of protecting the Subashi Buddhist Temple Ruins with SH by impregnation was studied, and it is suggested that the methods of surface spraying and borehole impregnation for anti-weathering should be combined to protect these ruins. [ABSTRACT FROM AUTHOR]

Calcined ginger nut (CGN) has been applied in grouting mortars for anchoring unstable earthen sites, but the lack of scientific research limits its application. In this study, CGN-based grouts admixed with fly ash (F), quartz sand (S), or both are evaluated. To explore the optimal mixture ratios, three types of mixing groups (five proportion gradients in each group) are established. All the grout specimens are buried and maintained outdoors, and their physical (shrinkage rate, density, elastic wave velocity, and permeability) and mechanical properties are continuously examined over 180 days. The solidification processes at different ages are simultaneously observed by means of scanning electron microscopy (SEM) images. The results indicate that the physical properties of grouts are influenced significantly by initial moisture content but then remain steady for approximately 15 days. Quartz sand can effectively reduce the shrinkage rate of grouts as well as adjust their density and permeability, and might be considered as an ideal mixing material for CGN. In the solidification process, grouts are rapidly solidified after the initial hydration reaction, and the carbonation reaction in the later stage constantly improves their mechanical strength, with physical properties kept relatively stable. SEM images show fly ash and quartz sand particles are cemented by CaCO 3 crystals. Through comprehensive comparison, the grouts with the mass ratio of CGN and S at 1:1 are found to better satisfy requirements that grouts should be compatible with earthen sites. [ABSTRACT FROM AUTHOR]

Numerous ancient sandstone grottoes remain in northwest and central China, and weathering issues have significantly influenced their preservation conditions. The dramatic naturally cyclic changes in water content and temperature in the environment have been considered to be the main drivers of the physical weathering that commonly occurs at these archaeological sites. Therefore, comparing and understanding the behaviors of sandstone with different weathering degrees under variable environmental conditions would be helpful for further study on predicting the type, location and extent of deterioration of sandstone relics in a small region (such as the surrounding rock of grottoes). This study examines Cretaceous sandstones with two weathering degrees from Bingling Temple Grottoes, China. Standard thin section photomicrographs provide petrographic and mineralogical data and show that the sandstones have identical lithologies. Three types of specifically designed frost weathering tests are then conducted on the samples. After every six weathering cycles, the weathering processes are suspended, and the corresponding parameters, such as dry weight loss, dry density, effective porosity, porosity, P wave velocity, surface hardness and drilling resistance, are measured. At the end of the weathering cycles, the sample variations in grain size distributions are compared, and statistical tests are performed to show the statistical significance of the results. The results indicate that similar deterioration patterns occur on the samples with two weathering degrees under the same weathering tests. The increase in effective porosity surpasses that of the porosity only when the weathering effect is large enough. Furthermore, sandstone with a high degree of weathering might be more susceptible to changes in the internal pores due to its greater initial interconnectivity. In an open system, physical weathering (frost–thaw and dry–wet cycles) would cause the superficial grain size distributions of different rocks to become relatively uniform. Finally, when exposed to the same weathering process, the decreases in the overall mechanical strength in the two sandstones do not differ significantly, but the loss of superficial strength may be different. [ABSTRACT FROM AUTHOR]

Exact quantum dynamics calculations of the eigenstate energy levels and wavefunctions for all bound rovibrational states of the Ne3 trimer (J = 0-18) have been performed using the ScalIT suite of parallel codes. These codes employ a combination of highly efficient methods, including phase-space optimized discrete variable representation, optimal separable basis, and preconditioned inexact spectral transform methods, together with an effective massive parallelization scheme. The Ne3 energy levels and wavefunctions were computed using a pair-wise Lennard-Jones potential. Jacobi coordinates were used for the calculations, but to identify just those states belonging to the totally symmetric irreducible representation of the G12 complete nuclear permutation-inversion group, wavefunctions were plotted in hyperspherical coordinates. 'Horseshoe' states were observed above the isomerization barrier, but the horseshoe localization effect is weaker than in Ar3. The rigid rotor model is found to be applicable for only the ground and first excited vibrational states at low J; fitted rotational constant values are presented. [ABSTRACT FROM AUTHOR]

Soil wettability is an important property that affects the behaviour of fine-grained soils. Previous studies have shown that hydrophobicity induced by organic or silane additives may affect the soil-water retention curve (SWRC). However, current findings regarding the effect of hydrophobicity on the SWRC are controversial. Previously, organic or silane additives were assumed to change only the soil wettability. Nevertheless, this study shows that polyvinyl alcohol (PVA) can change the hydrophobicity, pore size distribution (PSD), and specific surface area (SSA) of soil, thus affecting the SWRC. PVA-treated soil is hydrophobic when cured at 20 ℃, but hydrophilic when cured at 100 ℃. No thermal degradation is indicated in the PVA at 100 ℃ based on thermogravimetric analysis and a comparison of mass loss, and the sole difference between the PVA-treated soils cured at 20 and 100 ℃ is their wettability. This study managed to make the hydrophobicity caused by PVA to become an independent variable separated from the PSD and SSA by controlling the ambient temperature. The wetting and drying curves are measured under isopiestic humidity control in the high-suction domain (2.7–298.7 MPa), whereas pressure plates are used for the drying curves in the low-suction domain (0–800 kPa). The results obtained indicate that soil hydrophobicity significantly accelerates drainage when the matric suction is between 100 and 400 kPa, and an increase in PVA content increases the water retention capacity of soil. When the matric suction exceeds 2.7 MPa, the effect of soil hydrophobicity on the SWRC of the soil weakens. At this time, the SWRC is dominated by the van der Waals force, and the SSA contributes significantly to the process. Additionally, this study enables some controversial findings from previous studies to be explained, which is of great significance in soil and agriculture sciences. • A new method to isolate effect of hydrophobicity from other factors is proposed. • Soil hydrophobicity enhances water drainage in the low-suction domain. • Soil hydrophobicity has a weak effect in the high-suction domain. • The reason for the controversial conclusions in past studies is discussed. [ABSTRACT FROM AUTHOR]

Water-salt migration is an important reason for the development of basal erosion which seriously threatens the conservation of earthen sites. Studies in cutting-off or redirection of the water-salt migration path become vital. Polyvinyl alcohol (PVA) composite soil with extreme hydrophobicity shows the potential as the cushion layer with the damp-proof function, but the feasibility of preventing basal erosion based on the PVA cushion layer still lacks verification. In this study, for the embedded and non-embedded PVA cushion layers, water-salt distribution and morphology of earthen wall after repeated injection of salt solution were compared. The results showed that PVA cushion layer changed the water-salt migration path and promoted the accumulation of soluble salt on the ground outside the wall rather than the bottom of cushion layer, which effectively prevented basal erosion. A numerical model based on HYDRUS-2D confirmed that a partial laying of hydrophobic cushion layer under the wall cannot effectively prevent the water-salt migration, and a full laying of cushion layer should be adopted to prevent basal erosion. The cushion layer was recommended to extend towards the direction of the earthen wall instead of towards the sides, which also resisted the destructive effects of sand-driving wind and runoff erosion. • Basal erosion caused by water-salt migration is directly confirmed. • Water-salt distribution for models with/without PVA cushion layer is explored. • PVA cushion layer can inhibit basal erosion. • Reasonable laying modes of the hydrophobic cushion layer is presented. [ABSTRACT FROM AUTHOR]

The vacuum ultraviolet pulsed field ionization (PFI)-photoelectron (PFI-PE) spectrum of CO[sub 2] has been measured in the energy region of 19.0-20.0 eV. The PFI-PE vibrational bands resolved for CO[sup +, sub 2] are overwhelmingly dominated by the origin band along with weak vibrational bands corresponding to excitations of the v[sup +, sub 1] (symmetric stretching), v[sup +, sub 2] (bending), and v[sup +, sub 3] (antisymmetric stretching) modes. The simulation of the rotational contour resolved in the origin PFI-PE band yields a value of 19.3911±0.0005 eV for the ionization energy of CO[sub 2] to form CO[sup +, sub 2](C [sup 2]&Zigma;[sup +, sub g])./ A PFI-PE peak is found to coincide with each of the 0 K dissociation thresholds for the formation of O[sup +]([sup 4]S) + CO(X [sup 1]&Zigma;[sup +]) and CO[sup +] (X ²&Zigma;[sup +] ) +O(³P). This observation is tentatively interpreted to result from the lifetime switching effect, arising from the prompt dissociation of excited CO[sub 2] in high-n (n ≥ 100) Rydberg states prior to PFI. We have also examined the decay pathways for state-selected CO[sup +, sub 2] in the internal energy range of 5.2-6.2 eV using the PFI-PE-photoion coincidence scheme. The coincidence TOF data show unambiguously the formation of O[sup +]([sup 4]S) + CO(X 1&Zigma;[sup +]; v″ = 0,1) and CO[sup +](X ²&Zigma;[sup +] ; v[sup +] = 0,1) + O(³P). Analysis of the kinetic energy releases of fragment ions suggests that the dissociation of excited CO[sup +, sub 2] involved is nonstatistical and proceeds with an impulsive mechanism. Potential energy functions (PEFs) for the CO[sup +, sub 2] (C ²&Zigma;[sup +, sub g]) state and the lowest quartet states of CO[sup +, sub 2], together with their spin-orbit interactions, have been calculated using the complete active space self-consistent field and internal contracted multireference configuration... [ABSTRACT FROM AUTHOR]

Vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for OCS have been obtained in the energy range 15.0-19.0 eV, covering the vibronic bands of OCS[sup +] (A ²Π, B ²Σ[sup +], and C ²Σ[sup +]). The ionization energies for the formation of the ground vibrational levels of OCS[sup +] (A ²Π[sub &frac32;], A ²Π[sub ½, B ²Σ[sup +], and C ²Σ[sup +]) from the ground OCS(X ¹Σ[sup +]) state have been determined as 15.0759±0.0005 eV, 15.0901±0.0005 eV, 16.0403±0.0005 eV, and 17.9552±0.0005 eV, respectively. We have also generated the theoretical adiabatic three dimensional potential energy functions (PEFs) for OCS[sup +](A ²Π) by employing the complete active space self-consistent field and internally contracted multireference configuration interaction methods. Using these PEFs, the spectroscopic constants and low-lying rovibronic energy levels for OCS[sup +](A ²Π) are calculated variationally. These calculations have made possible the identification of many PFI-PE vibronic bands for OCS[sup +](A ²Π), which are originated from vibronic and Fermi resonance interactions. Owing to the different equilibrium geometries between the OCS[sup +](A ²Π) and OCS(X ¹&Sigma[sup +]) states, the PFI-PE spectrum for OCS[sup +](A ²Π) exhibits a long vibronic progression extending well above the OCS[sup +](B ²&Sigma[sup +]) state. On the contrary, the PFI-PE spectra for OCS[sup +] (B ²&sSigma[sup +] and C ²&Sigma[sup +]) are overwhelmingly dominated by the ground (0,0,0) bands, exhibiting only weak vibrational progressions. [ABSTRACT FROM AUTHOR]

Water and salt migration properties are important in many disciplines, including engineering construction, natural disaster prevention, agricultural irrigation and wastewater disposal. Relevant research into unsaturated loess caters to the development needs of the cities located on it. The objective of this study is to identify the water flow dynamics and consequent salt migration and redistribution (as well as their influence on microstructure alteration of the soil) during long-term seepage in unsaturated loess. In this experimental study, a long-term and one-dimensional seepage simulation test is conducted in a loess column. Probes are buried at different depths along the vertical profile to monitor and record the variations of volume water content and electrical conductivity. After the seepage test, soils at different depths are analyzed with different methods to make further investigation, including use of a pressure-plate apparatus to obtain soil-water characteristic curves, ion chromatography to determine the soluble salt components, and scanning electron microscopy to observe the microstructure changes. Good consistency between the different tests is obtained. Based on those results, the water and salt migration patterns and their influence on loess are analyzed and concluded. [ABSTRACT FROM AUTHOR]

Highlights • A technique to improve the consolidation effect used on earthen sites. • The RGB color space was applied to evaluate the colour changes of the treated samples. • The concept of composite reinforcement was proposed. • The sequence of consolidation of organic and inorganic materials was critical in the composite materials. Abstract Conservation practices employed thus far have proven that single materials cannot suitably protect earthen sites. This study compares the effectiveness of single and composite materials, to explore whether composite materials are potential candidates for use in conservation. Soils from the Great Wall of Yongchang, Gansu Province, China, were treated with five types of materials, namely, inorganic materials, organic products, composite materials composed of organic and inorganic materials in different orders, and ethanol. Changes in the colour, weight, mechanical properties, water resistance, microstructures, and element composition were evaluated after treatment. Better reinforcing effects were obtained by applying an organic material and then using an inorganic material. Results showed that a composite material with reasonable reinforcing sequence can greatly improve the properties of soils; hence, composite materials are promising for use in the protection of cultural relics in the future. [ABSTRACT FROM AUTHOR]

Grottoes are widely distributed along the ancient Silk Road in Northwest China, and wall paintings are among the most precious cultural relics in these grottoes. On-site investigation of some grottoes has revealed that these wall paintings are painted on earthen plaster and that most of them have a double-layer structure of plaster, i.e., a base coarse plaster layer (with wheat straw added) and a surface fine plaster layer (with hemp fibers added). Meanwhile, studies regarding the improvement in shrinkage and cracking behaviors via ancient plaster craftsmanship have been scarce. To investigate the specific effects of different material compositions on the shrinkage and cracking properties of plaster during desiccation, a series of laboratory shrinkage and cracking tests is conducted on plaster specimens composed of Dengban clay and quartz sand, vegetal fibers, and a potential restoration material (i.e., calcined ginger nut), respectively. The results show that adding sand and vegetal fibers can significantly increase the shrinkage limit of Dengban clay and inhibit its volume shrinkage and that vegetal fibers play an important role in the inhibition of surface cracking on plaster. Sand inhibits shrinkage by forming a skeleton in soil and reducing the formation of primary cracks. Fibers inhibit soil shrinkage by overcoming the suction between soil particles and preventing the formation of primary cracks. However, wheat straw cannot deform with the shrinkage of soil (e.g., hemp fibers); consequently, many subcracks appear around the wheat straw on the surface of coarse plaster. As a typical lime-based restoration material, calcined ginger nut paste presents slight shrinkage and a low surface crack ratio during desiccation, which demonstrates its good application prospect in plaster restoration. • Different types of plaster specimens are prepared based on the original composition. • Sand and vegetal fibers can significantly increase the shrinkage limit of Dengban clay. • Vegetal fibers are more effective in inhibiting surface cracking. • Calcined ginger nut paste shows slight shrinkage and a low surface crack ratio during drying. [ABSTRACT FROM AUTHOR]

• Sticky rice can inhibit the carbonation reaction of lime-treated soil. • The outer part of the sample had a higher carbonation than the inner part. • Binding and inhibition effects of sticky rice adjusted strength of lime-treated soil. Earthen sites with important historical, artistic, social, cultural, and scientific values have suffered serious damage due to long-term influences from various natural factors. The sticky rice and lime composite shows the potential to be applied to the protection of earthen sites. The carbonation of lime has a significant impact on the engineering properties of earthen sites. The main purpose of this study is to investigate the effect of sticky rice on the carbonation reaction of lime-treated soil in earthen sites. The results indicated that sticky rice can inhibit the carbonation reaction of lime, resulting in a reduced calcium carbonate content. The inhibition effect of sticky rice on carbonation reaction of lime could be attributed to the limitation of gaseous water and CO 2 gas diffusion. Sticky rice had both binding effect and inhibition effect on lime-treated soil, and its mechanical properties depended on the dominant effect after these effects cancelled each other. When the lime content was ≤6%, the addition of sticky rice can increase the strength of soil. When the lime content was >6%, however, the addition of sticky rice resulted in a decrease in strength. In addition, the carbonation of the outside of the cylindrical sample was higher than that of the inside. These findings can increase the understanding of protecting earthen sites with sticky rice and lime composite, and optimize the application of sticky rice and lime composite. [ABSTRACT FROM AUTHOR]

The soil water characteristic curve (SWCC) describes the relationship between matric suction and moisture of soil, the testing process of which is time-consuming. The test time of particle size distribution (PSD), in contrast, is relatively short. Thus, it is quite important to establish a proper model for PSD to forecast SWCC. This paper analyzed PSD of 25 groups of loess by way of laser diffraction technique (LD) and sieve-settlement method. Works were carried out on fitting analysis on PSD with Logarithmic model, Fredlund model, Jaky model, and Gompertz model. Statistical method was used to explain the fitting performance. Meanwhile, an empirical model was put forward. Compared to the four models, the empirical model has fewer parameters, simple model form, and smaller fluctuations of parameters. Results of LD showed higher clay content but lower silt content. It is suggested that Fredlund model or the empirical model be adopted to forecast SWCC of Malan loess. [ABSTRACT FROM AUTHOR]

The Mogao Grottoes are among the most famous sites on the World Heritage list. Several large-scale preservation projects were implemented in 1962, 1982, and 2008, respectively, to improve their preservation conditions. According to field investigation and assessment in recent years, the cliff is stable on the whole because of the reinforcement projects. Among them, there are still 42 potentially dangerous bodies, which may not be stable in some conditions. For the purpose of building the monitoring and early warning system and the long-term preventive preservation of the Mogao Grottoes, an innovative analytical method based on the Analytic Hierarchy Process (AHP) and Fuzzy-AHP was applied to assess the hazard of potentially dangerous bodies within the cliff. Firstly, the hazard was classified into six groups: very high, high, moderate, low, very low, and no hazard, in this study. Secondly, the AHP method was applied to calculate the impact index of each causative factor, and then the hazard assessment of dangerous bodies was made based on statistical analysis. Finally, the Fuzzy-AHP method was applied to calculate the correlation of each factor and determine the comprehensive hazard class. The results indicate that Fuzzy-AHP seems to be more accurate than AHP in hazard assessment. Meanwhile, there is a very high risk body that can threaten 10 caves, three high risk bodies that can threaten 13 caves, and 15 moderate risk bodies can threaten 69 caves in total, while the remaining bodies are defined as low or very low grades. Overall, the results of this study provide much data and a theoretical model in the construction of a monitoring and early warning system currently. Furthermore, the new numerical simulation method also holds the potential application to assess the hazards of other types of heritage sites. [ABSTRACT FROM AUTHOR]

In the northwest of China, many loess landslides have occurred without clear triggering factors (i.e., rainfall, earthquake, human activities, etc.). To better understand and analyze the hydro-mechanical properties of these slopes and then provide evidence for their stability analysis subjected to matric suction, it is essential to clarify the soil-water characteristic curve (SWCC). In this study, we conducted a set of experimental trials to examine the influences of initial dry density, water content upon the SWCCs of a loess soil taken from a loess landslide area, by using a conventional volumetric pressure plate extractor. Two common SWCC models have been investigated to evaluate which one is better for loess soil. The suction stress characteristic curves (SSCCs) were also estimated and analyzed. We found that behaviors of SWCCs would be different when the matric suction was greater than a certain value. The two SWCC equations have approximately the same performance in describing the SWCC. The rates of desorption decrease and residual water content increases with increasing the initial dry density, while the initial dry density has little, if any, influence on the air-entry value (AEV). The specimen compacted under higher initial water content would exhibit a higher AEV value and residual water content but lower rate of desorption as compared with the lower initial water content. The magnitude of suction stress had an approximately linear relationship with matric suction before the AEV value, the SSCC shapes will be markedly varied with the initial dry density and water content. [ABSTRACT FROM AUTHOR]

• The capillary barrier effect was applied to mitigate the secondary salt deterioration in the restored earthen sites. • Arya-Paris model and Fredlund-Xing's model were combined to predict the capillary barrier effect at the interface between earthen site soil and repair soil. • The prediction results were verified by water-salt migration test and mercury intrusion porosimetry. • Increasing the content of coarse particles in repair soil can effectively reduce the risk of secondary salt deterioration in the restored earthen site. Basal erosion is one of the most typical salt deteriorations of earthen sites in arid and semi-arid areas. Its formation is mainly related to the water and salt migration and enrichment at the bottom of earthen sites walls, and can cause collapse of site walls. Rammed roof-propping reinforcement is the main repair technology for the basal erosion of the earthen sites, but there is a risk of secondary salt deterioration in the repaired area due to the subsequent water and salt migration. Based on the capillary barrier theory, this study regulates the particle size composition of repair soil to explore repair materials that can effectively mitigate the secondary salt deterioration. Firstly, Arya-Paris model and Fredlund-Xing's model were used to convert the particle size distribution curves (PSDC) of soil with different particle composition into soil–water characteristic curves (SWCC), to preliminarily judge the capillary barrier potential of different soil structures. Then carry out water-salt migration test and mercury intrusion porosimetry test to verify the predictions. The research shows that when repair soil is coarser than earthen site soil, it can form an effective capillary barrier to block the capillary rise of water and salt, thus reducing the secondary salt deterioration in the repaired area. When repair soil is finer than earthen site soil, it will promote the capillary rise of water and salt, thus aggravating the salt deterioration in the repaired area. It is proposed to use the repair material of adding 20% sand on the basis of the original earthen site soil particle composition for the rammed roof-propping reinforcement of the earthen sites. [ABSTRACT FROM AUTHOR]

Earthen sites (i.e., ancient earthen buildings) with important historical, cultural, artistic, social, and scientific value have been seriously damaged. Soil treatment with chemical additives can decrease the degradation rate of earthen sites. In the past, polyvinyl alcohol (PVA) and quicklime as chemical additives were studied separately for the protection of earthen sites. In arid and semi-arid northwest China, the early strength of the lime-treated soil may be insufficient due to an inappropriate reaction environment, and the PVA as the additive can quickly increase the soil strength. However, calcium carbonate has been proven to not be decomposed for hundreds of years, while there is still a lack of experimental evidence to show that the PVA cannot be decomposed in decades. The PVA and lime as the additives show the potential to make up for the defects each other. Therefore, the physical and mechanical properties of the PVA and lime composite soil are analysed, and the microscopic properties of the composite soil are discussed in this study. The results show that the addition of the PVA decreases water vapour permeability and pore size, which causes a delay in the carbonization reaction of lime, but it acts as a cementing agent to improve soil strength before the lime appropriately reacts. The addition of quicklime can decrease the hydrophobicity of the PVA-treated soil. The mixing of these two materials is conducive to the colour control of the sample. For the composite soil applied to earthen sites in northwest China, the optimal ratio is 10% lime and 1.0% PVA. [ABSTRACT FROM AUTHOR]

Several types of deterioration have developed at earthen sites of the Ming Great Wall in Qinghai Province, including cracks, gullies, collapses, sapping, and scaling off, the first four of which could threaten the wall's stability. The correlations of these types of deterioration with each other and with other factors were explored. The authors selected 16 sampling points from nine typical earthen sites of the wall to investigate its deterioration. Linear fitting of the data on the types of deterioration was conducted to determine their correlations. Then, indoor tests of these samples were systematically performed to clarify the physical, water-related, and mechanical properties of the rammed earth, and meteorological data for each county were collected. Finally, the linear fitting was carried out among the deterioration indices, engineering-related parameters of the rammed earth, and meteorological data to determine the influence of these factors on the development of each type of deterioration. This research illustrates the mechanisms involved in such deterioration and its evolution from a macro perspective. [ABSTRACT FROM AUTHOR]

Sandstone was widely used in the construction of monuments and sculptures in ancient times; numerous archaeological sites still remain along the Silk Road. Deterioration of the archaeological sites is one of the most serious problems that needs urgent attention. Organosilicon material has been considered to be an effective type of chemical consolidant for heritage structures that need strengthening. In recent years, the negative effects of organic materials have gradually been realized, e.g., shorter life and poorer compatibility. Therefore, inorganic materials have been re-evaluated by conservation researchers because of their long-lasting effects and good compatibility with stone substrates. An innovative inorganic silicate solution based on a potassium silicate solution, a high mole ratio potassium silicate solution, was developed. This paper describes the characterization of the new material as well as results from testing after treatment with different concentrations and consolidation times. In this study, the authors aim to explore if the newly developed inorganic consolidant has potential for future use in sandstone treatment. The effectiveness of the new inorganic consolidant was evaluated in terms of absorbed consolidant amount, mechanical properties (e.g., surface hardness, ultrasonic wave velocity, elasticity modulus and compressive strength modulus), and salt crystallization resistance. The treated groups showed better mechanical strength than the control group. The salt-resistant ability of the treated samples was also greatly improved. According to the laboratory tests, the new inorganic silicon consolidant holds great potential for reinforcing weathered sandstone. [ABSTRACT FROM AUTHOR]

• The protective effects of sticky rice and lime composite are evaluated. • The relationship between macroscopic properties and microstructure is established. • The feasibility of protecting earthen sites with sticky rice and lime is discussed. Earthen sites have important historical, artistic, social, cultural, and scientific values. However, due to the extreme natural environment, they have suffered serious damage. The sticky rice and lime composite is one of the most important technological inventions in Chinese architectural history, which is an alternative material for the protection of earthen sites. In the past, the mechanical and microscopic properties of sticky rice and lime composite as binding material have been discussed. However, these properties are not sufficient to evaluate the feasibility of protecting earthen sites with sticky rice and lime composite. In this study, 25 groups of soil samples were prepared at five different lime contents (i.e. 0%, 3%, 6%, 9% and 12% by dry weight of sample) and five different sticky rice contents (i.e. 0.0%, 0.5%, 1.0%, 1.5% and 2.0% by dry weight of sample), and several important characteristics of the samples such as drying shrinkage, colour difference, surface hardness, unconfined compressive strength (UCS), and water vapour permeability are investigated comprehensively. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were used to study the microstructure of samples. Then, the feasibility of protecting earthen sites with sticky rice and lime composite was systematically evaluated. The results indicate that the effectiveness of sticky rice and lime composite is better than that of their individual application. The optimal formula is 6% lime and 0.5% sticky rice for the protection of earthen sites when above indicators are compared. The surface fractal dimension builds bridges between microstructure and macroscopic properties of the soil with sticky rice and lime. Surface hardness and UCS are positively related to the surface fractal dimension, while water vapour permeability is negative related to the surface fractal dimension. This research further provides insights into the potential application of traditional Chinese inorganic–organic composite for protecting earthen sites in arid and semi-arid regions of northwest China. [ABSTRACT FROM AUTHOR]

In this study, calcined ginger nuts (CGN) grouts admixed by fly ash (F) and quartz sand (S) was investigated on its suitability for anchoring use in earthen sites. According to requirement for the consistency of grout, the mix proportions were determined with 0.45 for CGN_F, 0.33 for CGN_S and 0.35 for CGN_F_S, by mass, to study their physical and mechanical property and durability. Test results indicated that use of fly ash can prolong the initial setting time of grout and admixture by fly ash and quartz sand leaded to lowest density and shrinkage, higher porosity, and highest strength. Accelerated aging tests indicated that admixture by fly ash led to a high resistance to fluctuation of temperature and humidity, sulfate attack and alkali environment; meanwhile, admixture by quartz sand resulted in high resistance to freeze-thaw action and water environment. As a compromise, CGN_F_S can get predominant durability. The paper shows that CGN_F_S grout is basically compatible to earthen sites and suitable for anchoring use in the conservation of earthen sites in terms of workability and durability. [ABSTRACT FROM AUTHOR]

• PVA-treated soil is confirmed to prevent water-salt capillary rise. • Effectiveness of 1.0% PVA-treated soil is best. • Interface effects are proposed to explain experimental phenomena. • Capillary rise of layered soil is described by modified Green-Ampt model. In the loess region of northwest China, the accumulation of soluble salt in the soil due to the capillary rise of water often damages earthen buildings. Thus, studies on the cutting off of the capillary-rise path are vital. As a hydrophobicity inducer, polyvinyl alcohol (PVA) solution with water as the solvent has the potential to function as a barrier. This study mainly aims to evaluate the feasibility of using PVA-treated soil as a waterproof layer to prevent water-salt capillary rise through soil column experiments, and the effects of the waterproof layer thickness, waterproof layer position, PVA content, ambient temperature, and type of salt solution on the capillary action. The results indicate that a 1.0% PVA-treated soil with extreme water repellency (i.e. dried at 20 °C) can perfectly prevent the water-salt from migrating to the top of the sample, regardless of the waterproof layer position, waterproof layer thickness, and type of soluble salt. For a 0.5% PVA-treated soil dried at 20 °C, the lower waterproof layer prevents the water-salt capillary rise, while the middle and upper layers exhibit less effectiveness. However, the PVA-treated soil that loses its hydrophobicity after a treatment at 100 °C cannot prevent the water-salt capillary rise, confirming that the prevention of capillary rise is due to the soil hydrophobicity. The waterproof layer thickness and type of soluble salt are less significant than the waterproof layer position, PVA content, and ambient temperature. This study proposes a modified Green-Ampt model to describe the capillary rise, and the hydraulic conductivity and pore size are obtained using the modified model. These parameters and the interface effect are used to explain the experimental results. Finally, the application of PVA-treated soil as a waterproof layer to inhibit water-salt capillary rise is illustrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Properties of CGN- and NHL-based pastes were investigated and compared. • The UCS of the CGN-based specimens improved significantly after aging for 90 days. • CGN-based pastes exhibited similar pore size distribution to the original plaster. • The strength mainly depended on the morphology of the hydrate and carbonate. In order to study the consolidation mechanism of traditional lime-based binders in the restoration of earthen plaster, the mechanical strength, hydration kinetics, and microstructure properties of calcined ginger nut (CGN)- and natural hydraulic lime (NHL)-based pastes were systematically investigated and compared. The results showed that CGN had good compatibility with clayish earth. Compared with the NHL-based pastes, the CGN-based pastes exhibited a higher late-stage compressive strength, lower heat release, denser microstructure and similar pore size distribution compared to the original plaster. [ABSTRACT FROM AUTHOR]

Owing to the advantages of cost-effectiveness, compactness, and the avoidance of complicated camera synchronization, single-camera three-dimensional (3D) digital image correlation (DIC) techniques have gained increasing attention for deformation measurement of materials and structures. In the traditional single-camera 3D-DIC system, the left and right view images can be recorded by a single camera using diffraction grating, a bi-prism, or a set of planar mirrors. To further improve the measurement accuracy of single-camera 3D-DIC, this paper introduces a single-camera four-view imaging technique by installing a pyramidal prism in front of the camera. The 3D reconstruction of the measured points before and after deformation is realized with eight governing equations induced by four views, and the strong geometric constraints of four views can help to improve the measurement accuracy. A static experiment, a rigid body translation experiment, and a four-point bending experiment show that the proposed single-camera 3D-DIC method can achieve higher measurement accuracy than the dual-view single-camera 3D-DIC techniques and that the single-camera 3D-DIC method has advantages in reducing both random error and systematic error. [ABSTRACT FROM AUTHOR]

On the premise of following the concept of culture heritage conservation, the technique of wooden bolt anchorage plays an important role in the conservation of rammed earthen sites. The existing researches on single anchoring cannot reflect the mechanical behaviors of an anchor group. To solve this problem, this study proposes a load-transfer method achieved by a universal joint combined with a load-bearing platform. Three rammed earth models were tested by continuous loading, with embedded length, bolt interval, and margin as variables. The failure mode, ultimate pulling resistance, load–displacement relationship, and interfacial strain distribution of the anchorage system were analyzed. Results show that the two bolts present sequential failure. Meanwhile, the failure of wooden bolts is not in a single mode; instead both interfacial debonding and soil-bearing capacity loss were observed in soil at the same time. The bolts are mostly in plastic-slipping state under working conditions. The strain is unevenly distributed at the bolt—grout interface and highest near the loading side. Spacing effect and marginal effect are important factors affecting the pulling resistance of two bolts, and their importance is higher than the quality of a single bolt. In addition, numerical simulations on behaviors of two wooden bolts, considering the interval distance, margin distance, embedment length, and layered property of rammed earth, were established by "interface" element, which supplemented and expanded the model test results. Results of this paper could provide deeper understanding of the macroscopic performance and internal mechanism of a two-bolts group. [ABSTRACT FROM AUTHOR]

Ina previous article [J. Theor. Comput. Chem.2010, 9, 435], all rovibrational boundstates of HO2were systematically computed, for all totalangular momentum values J= 0–10. In thisarticle, the high-Jrovibrational states are computedfor every multiple-of-ten Jvalue up to J= 130, which is the point where the centrifugal barrier obliteratesthe potential well, and bound states no longer exist. The resultsare used to assess the importance of Coriolis coupling in this floppysystem and to evaluate two different J-shifting schemes.Though not effective for multiply vibrationally excited bound states,vibrational-state-dependent J-shifting obtains modestlyaccurate predictions for the lowest-lying energies [J. Phys.Chem. A2006, 110, 3246]. However,much better performance is obtainedespecially for large Jvalues, and despite substantial Coriolis couplingusinga second, rotational-state-dependent J-shifting scheme[J. Chem. Phys.1998, 108, 5216], for which the rotational constants themselves depend on Jand K. The latter formalism also yieldsimportant dynamical insight into the structure of the strongly Coriolis-coupledeigenstate wave functions. The calculations were performed using ScalIT, a suite of codes enabling quantum dynamicscalculations on massively parallel computing architectures. [ABSTRACT FROM AUTHOR]

The eigenvalue/eigenvector and linear solve problems arising in computational quantum dynamics applications (e.g. rovibrational spectroscopy, reaction cross-sections, etc.) often involve large sparse matrices that exhibit a certain block structure. In such cases, specialized iterative methods that employ optimal separable basis (OSB) preconditioners (derived from a block Jacobi diagonalization procedure) have been found to be very efficient, vis-à-vis reducing the required CPU effort on serial computing platforms. Recently,1,2 a parallel implementation was introduced, based on a nonstandard domain decomposition scheme. Near-perfect parallel scalability was observed for the OSB preconditioner construction routines up to hundreds of nodes; however, the fundamental matrix-vector product operation itself was found not to scale well, in general. In addition, the number of nodes was selectively chosen, so as to ensure perfect load balancing. In this paper, two essential improvements are discussed: (1) new algorithm for the matrix-vector product operation with greatly improved parallel scalability and (2) generalization for arbitrary number of nodes and basis sizes. These improvements render the resultant parallel quantum dynamics codes suitable for robust application to a wide range of real molecular problems, running on massively parallel computing architectures. [ABSTRACT FROM AUTHOR]

Abstract: The linear solve problems arising in chemical physics and many other fields involve large sparse matrices with a certain block structure, for which special block Jacobi preconditioners are found to be very efficient. In two previous papers [W. Chen, B. Poirier, Parallel implementation of efficient preconditioned linear solver for grid-based applications in chemical physics. I. Block Jacobi diagonalization, J. Comput. Phys. 219 (1) (2006) 185–197; W. Chen, B. Poirier, Parallel implementation of efficient preconditioned linear solver for grid-based applications in chemical physics. II. QMR linear solver, J. Comput. Phys. 219 (1) (2006) 198–209], a parallel implementation was presented. Excellent parallel scalability was observed for preconditioner construction, but not for the matrix–vector product itself. In this paper, we introduce a new algorithm with (1) greatly improved parallel scalability and (2) generalization for arbitrary number of nodes and data sizes. [Copyright &y& Elsevier]

The filtered mass density function (FMDF) model has been employed for large-eddy simulations (LES) of compressible high-speed turbulent mixing and reacting flows. However, the mixing model remains a pressing challenge for FMDF methods, especially for compressible reactive flows. In this work, a temporal development mixing layer with two different convective Mach numbers, M c = 0.4 and M c = 0.8 , is used to investigate the mixing models. A simplified one-step reaction and a real hydrogen/air reaction are employed to study the mixing and turbulence-chemistry interaction. Two widely used mixing models, interaction by exchange with the mean (IEM) and Euclidean minimum spanning tree (EMST), are studied. Numerical results indicate that no difference is observed between the IEM and EMST models in simple reaction flows. However, for hydrogen/air reactions, the EMST model can predict the reaction more accurately in high-speed flow. For mixing models in compressible reactive flows, the requirement of localness preservation tends to be more essential as the convective Mach number increases. With the increase of compressibility, the sensitivity of the mixing model coefficient is reduced significantly. Therefore, the appropriate mixing model coefficient has a wider range. Results also indicate that a large error may result when using a fixed mixing model coefficient in compressible flows. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hoeffding Tree is a promising landslide susceptibility model based on ROC and AUC. • Bayes Network and Logistic Model Tree were applied for comparison. • Correlation analysis of conditioning factors was completed by Frequency Ratio. • Landslide susceptibility maps of Muchuan County and the county town were produced. Landslides, one of the most common hazards around the world, have brought about severe damage to life and property of human. To prevent and mitigate landslides, various models have been introduced to assess landslide susceptibility. In this paper, Hoeffding Tree (HT), a prevailing data stream mining algorithm, was employed to predict landslide susceptibility in Muchuan County, China for the first time. Meanwhile, Logistic Model Tree (LMT) and Bayes Network (BN) were applied to produce landslide susceptibility maps for comparison. The model performances were evaluated by Receiver Operating Characteristic (ROC) curves and areas under the curves (AUC). To obtain landslide inventory map, 279 landslides data was collected, and training and validation datasets were randomly divided with a proportion of 70% to 30%. Furthermore, twelve conditioning factors (altitude, slope angle, profile curvature, plan curvature, slope aspect, distance to roads, distance to rivers, TWI, NDVI, soil, land use and lithology) were selected to construct landslide susceptibility models. Moreover, correlations between conditioning factors and landslides were analyzed using Frequency Ratio (FR). The results showed landslides are prone to occur in areas where human activities concentrate, and all three models exhibited satisfying performances. Concretely, for training dataset, LMT model showed the highest AUC (0.854), followed by HT (0.726) and BN (0.709). However, for validation dataset, LMT and BN models generated similar AUC values (0.761 and 0.764 respectively), and the highest AUC value belonged to HT (0.802). The distributions of landslide susceptibility zones revealed that the interior of county town is mainly seated in low and very low susceptibility zones, whereas regions close to the border suffer high and very high landslide risk. The results acquired in this paper are significant to landslide prevention and urban planning in Muchuan, China. Additionally, this study proved that HT model is a promising classifier for landslide susceptibility modeling. [ABSTRACT FROM AUTHOR]

Abstract: Linear systems in chemical physics often involve matrices with a certain sparse block structure. These can often be solved very effectively using iterative methods (sequence of matrix–vector products) in conjunction with a block Jacobi preconditioner [B. Poirier, Numer. Linear Algebra Appl. 7 (2000) 715]. In a two-part series, we present an efficient parallel implementation, incorporating several additional refinements. The present study (paper II) indicates that the basic parallel sparse matrix–vector product operation itself is the overall scalability bottleneck, faring much more poorly than the specialized, block Jacobi routines considered in a companion paper (paper I). However, a simple dimensional combination scheme is found to alleviate this difficulty. [Copyright &y& Elsevier]

Abstract: Linear systems in chemical physics often involve matrices with a certain sparse block structure. These can often be solved very effectively using iterative methods (sequence of matrix–vector products) in conjunction with a block Jacobi preconditioner [Numer. Linear Algebra Appl. 7 (2000) 715]. In a two-part series, we present an efficient parallel implementation, incorporating several additional refinements. The present study (paper I) emphasizes construction of the block Jacobi preconditioner matrices. This is achieved in a preprocessing step, performed prior to the subsequent iterative linear solve step, considered in a companion paper (paper II). Results indicate that the block Jacobi routines scale remarkably well on parallel computing platforms, and should remain effective over tens of thousands of nodes. [Copyright &y& Elsevier]

While the macroscopic mechanical properties of earthen-site soils have undergone extensive experimental and modeling studies, few research efforts focus on the relationship between the overall mechanical behavior and micro-pore structure. We developed a microstructure-based finite element model to investigate the influence of micro-pore structure on the macroscopic mechanical behavior of earthen-site soils. Scanning electron microscopy images of the untreated and consolidated soils were processed to compare the changes in equivalent diameter, sphericity, and porosity of the soils after consolidation. According to the pore parameter range of the untreated and consolidated soils, the effects of micro-pores on the soil behavior are specifically conducted under both static and dynamic loads. The relationships between pore characteristics and stiffness, strength, and ultrasonic wave velocity are established. [ABSTRACT FROM AUTHOR]

• A SMOTE approach was proposed to handle imbalanced data of hazards levels. • SMOTE was integrated with Gaussian process for the prediction of hazards levels. • A real-world example is used to illustrate and validate the proposed approach. • Results from different data generation approaches are compared with that of SMOTE. • Results from different machine learning methods are compared with that of GP. Cultural soil heritages (CSHs) are artifacts with historical, artistic, and scientific significance; however, they are vulnerable to various hazards, such as weathering, fractures, hollowing, collapses, and gullies. This is especially true for those CSHs exposed to the outdoors. Due to the large number of CSHs sites within China, managing and protecting these heritages with the aid of detailed on-site investigations is time-consuming and expensive. Consequently, evaluating the spatial distribution and degree of hazards developed in all these heritages becomes impractical. To address this issue, this paper developed a Gaussian process classification (GPC) method to predict the spatial distribution of typical hazards (i.e., weathering, fractures, hollowing, collapses, and gullies) and the development level of each hazard from eight environmental factors (e.g., annual relative humidity and annual sunshine time) and a limited number of investigation data. As the number of investigation data for different levels of each hazard is usually imbalanced and sparse, this study proposed a synthetic minority oversampling technique (SMOTE) with GPC to form the SMOTE-GPC method. A real-world example is used to illustrate this approach. Results from real-world data demonstrated that the proposed method achieved an F 1 score, precision, recall, and Cohen's kappa with values greater than 0.93 in both the training and testing datasets, indicating its good performance. [ABSTRACT FROM AUTHOR]

Many studies reported the chlorite dissolution kinetics in acidic pH—resulting in the development of chlorite dissolution rate law covering the pH and temperature dependence—but they rarely discussed how various intrinsic factors, including chlorite types, structural complexity, and surface roughness (refers specifically to the ratio between Brunauer–Emmett–Teller surface area, BET SA, and geometric surface area, GSA, in this paper), influenced the chlorite dissolution rate or the mechanism for dissolution congruency. In this study, results obtained from mixed-flow reactor experiments performed on a Mg-rich chlorite, over a pH range of 2–6 at 25 °C and 95 °C, indicated that pH and temperature control not only the chlorite dissolution rate but also the congruency of element release. Low pH facilitated the dissolution of Fe from chlorite interlayers and caused incongruent element release rates at 25 °C, while higher temperature experiments at the same pH overcame the differences in surface reactivity between the interlayer and the tetrahedral-octahedral-tetrahedral (TOT) layer, and finally evolved into congruent dissolution. The lower pH also made chlorite dissolution more resistant to varying flow rates. A dissolution rate constant of 10–10.51 mol/m2/s, a reaction order of 0.32, and activation energy of 42.03 kJ/mol were determined for the Mg-rich chlorite dissolution kinetics at 25 °C, in an acid-enhanced mechanism. Longer-term reactive transport modeling (RTM) on the chlorite dissolution demonstrated that low pH and large specific surface area (SSA) decreased the chlorite percentage, bulk surface area, and saturation index quicker, and in a non-linear fashion. Chlorite with higher SSA lost more bulk surface area (BSA) than that with lower SSA, when the same mass of chlorite was dissolved. Through tabulating and recalculating a series of data from the literature, the combined effects of intrinsic and extrinsic factors—including chlorite type, BET SA/GSA ratio, and temperature—were explored. Fe-rich chlorite dissolves faster than Mg-rich chlorite in acid and neutral pH, due to the oxidative dissolution mechanism. The chlorite dissolution rate constant is linearly and positively correlated to BET SA/GSA for the same type of chlorite (Fe-rich and Mg-rich). Higher temperatures help reduce the effects of extrinsic and intrinsic factors on chlorite dissolution rates. • Dissolution kinetics for a type of Mg-rich chlorite was determined in the acid pH range. • Effects of temperature and crystal structure on chlorite dissolution congruency were assessed. • RTM was applied to simulate chlorite dissolution under different pH and SSA. • Effects of intrinsic factors on chlorite dissolution kinetics in the acidic pH were explored. [ABSTRACT FROM AUTHOR]