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This document is an editorial titled "Characterization, Applications and New Technologies of Civil Engineering Materials and Structures." It discusses the importance of accurately evaluating and predicting the mechanical behavior of civil materials and structures in order to improve infrastructure durability and maintenance management. The document highlights a special issue that includes twenty research papers and one systematic review on various topics related to civil engineering materials, such as the use of solid wastes, material properties, and mechanical behavior. The aim of the special issue is to share innovative research and application methods in order to further develop civil engineering technology. The authors of the editorial express their gratitude to the authors, peer reviewers, and staff involved in the special issue. [Extracted from the article]

Moisture migration in pavement leads to the loss of strength of asphalt mixture. However, moisture profile measurement inside of the mixture can be challenging. In this paper, a new experimental method is proposed to measure the moisture profile; this method is based on the principle that white anhydrous copper sulfate powder turns blue with water. The influences of asphalt content, gradation, indoor compaction, temperature and pressure on moisture diffusion depth and strength loss are also discussed. The results show that the proposed method successfully reveals the moisture profile of the asphalt mixture. High temperature and pressure accelerate the moisture diffusion process. A large filler-bitumen ratio and high content of coarse aggregate result in a large diffusion depth. The rolling compacted mixture demonstrates better resistance to moisture diffusion than the Marshall mixture. It is inferred that the rainfall's influence on the asphalt layer is mainly within a depth of 23 mm below the surface. The strength attenuation of asphalt mixture after damage is mainly affected by compaction method and external pressure, while filler-bitumen ratio affects the attenuation trend of the mixture strength. The proposed method in this paper has the advantages of easy operation and in-field application potential. [ABSTRACT FROM AUTHOR]

Moisture migration in pavement leads to the loss of strength of asphalt mixture. However, moisture profile measurement inside of the mixture can be challenging. In this paper, a new experimental method is proposed to measure the moisture profile; this method is based on the principle that white anhydrous copper sulfate powder turns blue with water. The influences of asphalt content, gradation, indoor compaction, temperature and pressure on moisture diffusion depth and strength loss are also discussed. The results show that the proposed method successfully reveals the moisture profile of the asphalt mixture. High temperature and pressure accelerate the moisture diffusion process. A large filler-bitumen ratio and high content of coarse aggregate result in a large diffusion depth. The rolling compacted mixture demonstrates better resistance to moisture diffusion than the Marshall mixture. It is inferred that the rainfall's influence on the asphalt layer is mainly within a depth of 23 mm below the surface. The strength attenuation of asphalt mixture after damage is mainly affected by compaction method and external pressure, while filler-bitumen ratio affects the attenuation trend of the mixture strength. The proposed method in this paper has the advantages of easy operation and in-field application potential. [ABSTRACT FROM AUTHOR]

Investigating the mechanical properties of the surrounding rock of the caves is crucial for the preservation of grotto heritage sites. To comprehend the mechanical characteristics of conglomerates in the Dunhuang region of China, various experiments were utilized, including Scanning Electron Microscope, X-ray Diffraction, CT scanning, nanoindentation, and mechanical tests. These methods enabled the exploration of morphological features and mechanical properties of the grotto conglomerate at both micro and mesoscales. Additionally, numerical simulations were employed to conduct a cross-scale study of the micro-meso-macro mechanical properties of conglomerate samples, establishing connections between the uniaxial compression strengths at different scales. The results indicate that conglomerates are highly heterogeneous rock formations with complex compositions, exhibiting noticeable mechanical variability. As the size increases, this variability gradually diminishes. Furthermore, nanoindentation tests revealed that the hardness of conglomerate particles is tens of times higher than that of the cementing material. In the preservation of cave structures, particular attention should be given to maintaining or enhancing the bonding capacity of the cementing material within conglomerates. This study provides a feasible approach for conducting cross-scale analysis on rock samples with complex compositions and poor homogeneity, especially in scenarios involving limited test samples. The findings offer theoretical insights into the preservation of cave cliff structures. • A cross-scale analysis on the mechanical properties of conglomerates is carried out. • Nanoindentation was utilized to provide microscale properties of the conglomerate. • Numerical simulations were employed for upscaling from microscale to macroscale. [ABSTRACT FROM AUTHOR]

Asphalt pavement experiences various wet-dry histories in the service stage. However, the influence of wet-dry history on asphalt mixture is unknown. Therefore, to clarify the performance degradation mechanism and predict the performance of asphalt mixture under the action of wet-dry history, the creep-recovery test, indirect tensile stiffness modulus test and indirect tensile strength test were conducted at different temperatures. The finite element method was adopted to analyze the moisture diffusing profile inside the specimen after wet-dry cycles. A moisture damage model considering the soaking time and repeated characteristics was developed to predict the damaged properties. Results show that wet-dry cycles cause a slight mass loss of asphalt mixture. Wet-dry cycling action leads to the increment in high-temperature deformation, and reductions in stiffness modulus and tensile strength. The increase of high-temperature deformation is primarily caused by viscoplastic component. Even if the soaking time is short, high moisture damage occurs while the wet-dry cycle is sufficient. Numerical simulations show that the moisture concentration profiles inside asphalt mixture vary under different wet-dry histories, leading to variations in the damage zone. The degree of damage is also closely related to the acting time of moisture. The critical immersion time of the dense asphalt mixture (about 43 hours) was determined in this study. When the immersion period is shorter than the critical immersion time, the strength loss is greater than the modulus. On the contrary, the degree of modulus damage is higher than that of strength. Considering the actual rainfall climate in China, the strength damage of the on-site asphalt mixture in the field predominates. The proposed model could reflect the weakening trends of modulus and strength. It has good universal applicability in predicting the damaged Marshall stability, modulus, and strength at different temperatures. • A wet-dry cycling experiment for asphalt mixture was designed. • Effect of wet-dry history on the high, medium and low temperature properties of dense asphalt mixture was investigated. • An accumulative moisture damage model was developed and validated. [ABSTRACT FROM AUTHOR]

Apart from low-temperature cracking, asphalt pavement may also suffer from thermal fatigue cracking. To clarify the impact of cold waves on the thermal fatigue performance of asphalt mixtures, the typical atmospheric temperature characteristics of different regions in China from 2012 to 2019 were analyzed, and the frequency of cold waves in these regions was determined. The viscoelastic parameters of an asphalt mixture are determined through an indirect tensile relaxation test. The thermal stress of the asphalt mixture is simulated and analyzed by using the finite element method. The effect of cold waves on the thermal fatigue life of the asphalt mixture was evaluated. The results show that the frequency of cold waves is different from region to region in China, and the cold waves mainly occurred from October of one year to February of the next year. Northeast China has the most frequency and the largest temperature drop amplitude, followed by North China. The maximum thermal stress increases with the decrease in temperature drop and initial temperature and is unrelated to the duration of cold waves. The thermal stress calculated based on the atmospheric thermal boundary is higher than the value using the road surface temperature. The thermal fatigue lives of asphalt mixtures in North China and Northeast China are very short, while the thermal fatigue life of the mixture in Central China is the longest. To meet the requirement of thermal fatigue damage caused by cold waves during the designed service stage, the recommended threshold for thermal stress is 0.39–0.77 MPa. [ABSTRACT FROM AUTHOR]

• The processes and mechanisms of cracking and flaking damage in mural were studied. • A numerical method was used to investigate the moisture-induced cracking of mural. • The simulation result reproduced the process of surface shrinkage and cracking. • Nanoindentation test was used to measure the mechanical parameters of mural. Under various environmental conditions, including fluctuations in humidity, murals may undergo degradation processes, such as craquelures and flaking, reducing their cultural significance. This study employs the RFPA numerical simulation method, integrating humidity, stress, and damage factors to explore the response of the color layer of the Mogao Grottoes mural in China to moisture-induced cracking. To achieve this, a numerical model was constructed, encompassing both the color layer and the plaster layer. The simulation results accurately reproduce the surface shrinkage, cracking, and flaking. Findings indicate that the development of craquelures and flaking in the mural is linked to humidity gradient-induced shrinkage and material properties of the color layer and plaster layer. Moreover, factors like surface drying speed, color layer thickness, and binder content influence the cracking process. This research provides novel insights into the developmental processes and mechanisms underlying surface craquelures and flaking degradation in ancient cultural relics, such as murals. [ABSTRACT FROM AUTHOR]

A built-up I-section with web stiffeners and complex edge stiffeners is expected to have better performance to resist against local and distortional buckling compared to conventional built-up I-section. In order to study the influence of perforations on compression behavior of above section forms, a series of pin-ended compression tests and numerical analysis on perforated double-limb cold-formed steel built-up I-section columns with complex edge stiffeners and web stiffeners were conducted. The test specimens contained 12 concentrically loaded specimens and 8 eccentrically loaded specimens with two cross-section shapes, respectively. The test results were found that the web stiffeners could obviously increase the ultimate bearing capacity of the built-up members, especially for stub and medium-long columns. The ultimate bearing capacity of two cross-section shaped medium-long columns decreased gradually with the increase of eccentricity. Two adjacent single-limb webs of conventional built-up I-section could provide support to each other. The web stiffeners restricted the deformation of the plate around the holes effectively, but it also weakened the composite action between the single-limb webs. A finite element model was developed and verified against experiments of perforated built-up columns. Furthermore, a total of 96 parametric analyses were completed to investigate the optimal ratio of the hole depth to web sub-element in the Σ-shaped built-up I-section perforated columns. Finally, two types of direct strength method formulas were used to calculate the ultimate bearing capacity of perforated built-up specimens. The appropriateness of those direct strength method was compared. It was shown that the existing direct strength method formulas were both valid for perforated built-up I-section columns with complex edge stiffeners. [ABSTRACT FROM AUTHOR]

Highlights • Effects of salt and freeze-thaw cycles on asphalt-aggregate interface were investigated. • A power model was suitable for estimating the coupled effects of different factors. • DIP technology was employed to identify the cohesive and adhesive failure areas. Abstract Snowmelt salts and deicing additives which are used to remove the snow/ice in winter make the pavement experience diverse and complex actions such as freeze-thaw (F-T) cycles and salt immersion. Meanwhile, interface damage of asphalt-aggregate is a major reason for the decay of mixture properties. So, the interface properties under the impacts of snowmelt salt and F-T cycles were investigated in this paper. Three factors including salt concentration, soaking time and F-T cycles were considered based on the service condition of the pavement. 'Sandwich' specimens of asphalt-aggregate were prepared in the laboratory. Also, pull-off tensile test was conducted by universal test machine. Digital image processing technology was employed to analyze the interface failure mode. Results indicated that the selected three factors presented significant effects on moisture absorption and pull-off tensile strength (POTS). All of the POTS at low, medium and high temperatures decreased after conditioning. And the pull-off tensile strength loss (POTSL) after salt solution soaking and F-T cycles were all higher than the pure water soaking one. The power model can be used to describe the composite damage degree imposed by different factors. The coupling actions of salt immersion and F-T cycles would induce the failure mode variety. Adhesive failure was prone to occur at low temperature under the condition of low salt concentration and F-T cycles. Erosion effect of high concentration solution would induce the adhesive failure at medium temperature. [ABSTRACT FROM AUTHOR]

• The morphological characteristics of BSCs on the earthen sites were analyzed. • We obtained the mechanical properties of BSCs on the earthen sites. • The research strategy to determine the effect of plant development in the surface layers of the earthen sites was proposed. Earthen sites are cultural and have rich historical significance. However, most earthen sites have been damaged or even destroyed during historic preservation. To reduce the damage caused by rain, snow erosion, freezing and thawing, these sites should be protected using vascular plant capping technology, which has great research value and application prospects. However, the effect of biological soil crusts (BSCs) on the shallow surfaces of these sites is scarcely understood. Therefore, this study aimed to explore the soil consolidation characteristics of BSCs on the shallow surfaces of earthen sites through laboratory experiments. First, the species, morphology and geometric characteristics of BSCs were studied using observation with a high–resolution digital microscope and analyses of the fractal and topological dimensions of rhizoids. The results showed that the dominant population of BSCs was composed of Didymodon vinealis , and the rhizoid type exhibited herringbone architecture. In addition, the effect of rhizoid anchoring was greater than that of rhizoid wedging. Second, the mechanical properties of the soil consolidation of the rhizoid–soil composite were investigated using tensile strength tests of single rhizoids and shear strength tests of rhizoid–soil composites. It was concluded that moss rhizoids could improve the shear strength of the surface soil. Additionally, the surface roughness of the rhizoids affected their anchorage characteristics. Finally, we discussed the disadvantages of generally classifying plants as "potentially harmful", and emphasized the necessity of constructing a heterogeneous research model highlighting specific environmental factors, plants, and earthen sites. [ABSTRACT FROM AUTHOR]

Short fibers have been widely used to prepare the fiber reinforced asphalt concrete (FRAC). However, internal interactions between fiber and other phases of asphalt concrete are unclear although experimental methods have been used to design the FRAC successfully. In this paper, numerical method was used to investigate the reinforced mechanism of FRAC from microperspective. 2D micromechanical model of FRAC was established based on Monte Carlo theory. Effects of fiber length and content on stress state of asphalt mortar, effective modulus, and viscoelastic deformation of asphalt concrete were investigated. Indirect tensile stiffness modulus (ITSM) test and uniaxial creep test were carried out to verify the numerical results. Results show that maximum stress of asphalt mortar is lower compared to the control concrete when the fiber length is longer than 12 mm. Fiber reduces the stress level of asphalt mortar significantly. Fiber length has no significant influence on the effective modulus of asphalt concrete. Fiber length and content both have notable impacts on the viscoelastic performance of FRAC. Fiber length should be given more attention in the future design of FRAC except the content. [ABSTRACT FROM AUTHOR]

The gradation of asphalt concrete affects the properties of pavement significantly. It is an important parameter for the design of asphalt mixture. So the planar gradation of asphalt concrete was investigated using the digital image processing techniques in this paper. Then the planar gradation was transformed to the three dimensional gradation by stereological method. The aggregate was assumed as ellipsoidal particle in stereological conversion. And stereological coefficients of ellipsoidal particle were determined using numerical method. The results indicated that aspect ratio of aggregate affected stereological coefficients significantly. There was a good agreement between the estimated and the control gradations when the improved assumption was used. The estimated errors of proposed method were less than that of other methods. Aggregate was suggested to be assumed as ellipsoidal particle in stereological conversion. And the combined method of digital image processing and stereological conversion is a universal, fast and accurate method for gradation estimation. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the compound effects of diatomite and glass fiber on asphalt mixture. The diatomite and glass fiber compound modified asphalt mixture (DGFMAM) was prepared in laboratory. Performances of DGFMAM were investigated by experimental method. Wheel tracking test, low temperature indirect tensile test, indirect tensile fatigue test (ITFT) and indirect tensile stiffness modulus test (ITSM) were carried out. The statistical analysis of variance (ANOVA) method and statistical regression method were used to evaluate the effects of diatomite and glass fiber on properties of asphalt mixture. Results indicate that diatomite and glass fiber improve the rutting resistance and fatigue properties of control asphalt mixture. Diatomite has a significant effect on the stiffness modulus of asphalt mixture. Disadvantage of diatomite on low temperature deformation property of asphalt mixture is solved by glass fiber. DGFMAM has better travelling performances than the control mixture. It will provide a reference for the design of compound modified asphalt mixture. [ABSTRACT FROM AUTHOR]

The self-healing ability of asphalt–aggregate bonding interfaces can maintain the mechanical properties of asphalt mixtures. However, the interface's healing ability will also be affected by moisture and aging. In order to clarify the influence of moisture and aging on the healing ability of a bonding interface, the effects of healing period and temperature on the self-healing level of interfacial strength were measured. The healing master curve of the strength was established. Thereafter, the effects of soaking time, salt solution concentration, and thermal aging on the healing degree of interfacial strength were measured. Based on digital image processing technology and the meso-finite element method, the influence of the interface on the healing performance of the mixture was simulated and analyzed, which was then verified by the beam bend healing test. The results show that the healing index of bonding strength increases with the ascent of healing temperature and period. Healing index gradually decreases with the extension of soaking period, and the higher the concentration of salt in the solution, the worse the healing performance of interfacial strength. After asphalt aging, the healing potential of the interface is weakened. There is a good linear relationship between the healing level of an asphalt–aggregate interface and the level of strength and fracture energy of the mixture. However, the actual healing level of an asphalt mixture is obviously lower than that of the interface, due to the addition of mineral filler. This paper provides a method for predicting the recovery performance of asphalt pavement. [ABSTRACT FROM AUTHOR]

Abstract: A method of realization of multi-documents Automatic Abstracting based on text clustering and semantic analysis is brought forward, aimed at overcoming shortages of some current methods about multi-documents. The method makes use of semantic analysis and can realize Automatic Abstracting of multi-documents. The algorithm of twice word segmentation based on the title and first-sentences in paragraphs is brought forward. Its precision and recall is above 95%. For a specific domain on plastics, an Automatic Abstracting system named TCAAS is implemented. The precision and recall of multi-document’s Automatic Abstracting is above 75%. And experiments do prove that it is feasible to use the method to develop a domain Automatic Abstracting system, which is valuable for further study in more depth. [Copyright &y& Elsevier]

Abstract: Semantic Web technologies bring new benefits to knowledge-based question answering system. Especially, ontology is becoming the pivotal methodology to represent domain-specific conceptual knowledge in order to promote the semantic capability of a QA system. In this paper we present a QA system in which the domain knowledge is represented by means of ontology. In addition, personalized services are enabled through modeling users’ profiles in the form of pervasive agent ontology, and a Chinese Natural Language human–machine interface is implemented mainly through a NL parser in this system. An initial evaluation result shows the feasibility to build such a semantic QA system based on pervasive agent ontology, the effectivity of personalized semantic QA, the extensibility of pervasive agent ontology and knowledge base, and the possibility of self-produced knowledge-based on semantic relations in the pervasive agent ontology. [Copyright &y& Elsevier]

Abstract: The need for providing learners with web-based learning content that match their accessibility needs and preferences, as well as providing ways to match learning content to user’s devices has been identified as an important issue in accessible educational environment. For a web-based open and dynamic learning environment, personalized support for learners becomes more important. In order to achieve optimal efficiency in a learning process, individual learner’s cognitive learning style should be taken into account. Due to different types of learners using these systems, it is necessary to provide them with an individualized learning support system. However, the design and development of web-based learning environments for people with special abilities has been addressed so far by the development of hypermedia and multimedia based on educational content. In this paper a framework of individual web-based learning system is presented by focusing on learner’s cognitive learning process, learning pattern and activities, as well as the technology support needed. Based on the learner-centered mode and cognitive learning theory, we demonstrate an online course design and development that supports the students with the learning flexibility and the adaptability. The proposed framework utilizes data mining algorithm for representing and extracting a dynamic learning process and learning pattern to support students’ deep learning, efficient tutoring and collaboration in web-based learning environment. And experiments do prove that it is feasible to use the method to develop an individual web-based learning system, which is valuable for further study in more depth. [Copyright &y& Elsevier]

• Effect of basalt fiber on mixed mode fracture of asphalt mixture was investigated. • Asymmetric semi-circular bend test was carried out. • Critical stress intensity factor and fracture energy were determined. • GMTS criterion is suitable for the prediction of fracture initiation angle. • Linear empirical fracture criterion has good applicability to asphalt mixture. Basalt fiber could effectively improve the crack resistance of asphalt mixture. However, most cracks in asphalt pavement present complex fracture characteristics. Effect of basalt fiber on the mixed mode fracture resistance of asphalt mixture is still unknown. Thus, the asymmetric semi-circular bend test was used to study the mode I and II fracture properties of the control and basalt fiber reinforced asphalt mixtures (BFRAM) at low and medium temperatures. Influences of basalt fiber on the critical stress intensity factor and critical fracture energy of asphalt mixture were investigated. The applicability of different fracture criterions to asphalt mixture also was discussed. Results indicate that the critical stress intensity factors of BFRAM first decreases and then increases with the rise of Me (which describes different fracture modes) at medium and low temperatures. Basalt fiber soundly improves the critical fracture energy of asphalt mixture at medium and low temperature even though it reduces the critical stress intensity factor at 20 ℃. The reinforcing effect of basalt fiber is optimal for the mixed mode fracture. Generalized maximum tangential stress (GMTS) criterion is suitable for the prediction of fracture initiation angle. The linear empirical fracture criterion has good applicability to the control and basalt fiber reinforced asphalt mixtures. This work can be used to analyze the mixed modes fracture of asphalt layers. [ABSTRACT FROM AUTHOR]

• Temperature and pressure dependences of diffusion coefficients were tested. • Influence of temperature history on moisture diffusion was analyzed using 2D FEM. • Impact of hydrodynamic pressure on moisture diffusion was estimated. Asphalt pavement is inevitably affected by the rainfall in service stage. The interaction between vehicle and rainfall would cause the hydrodynamic pressure. What's more, pavement temperature also is changing with time. Temperature history and hydrodynamic pressure would influence the moisture diffusion in the pavement. Thereby, moisture uptake of stone, asphalt mortar and mixture at different temperatures and pressures were obtained by weighing. A pressured device was developed to evaluate impact of pressure on the moisture uptake. Diffusion coefficients of those materials were determined based on Fick's second law. And then, 2D micro mechanical FE model of asphalt mixture was developed with the help of digital image processing technology. Effects of temperature and pressure on moisture diffusion depth were analyzed using FEM. Results showed that the rise in temperature and pressure caused the increment of diffusion coefficient. This also resulted in the ascending of moisture diffusing depth. Influence of mortar characteristic on moisture diffusion was more significant than that of aggregate. Under the actions of wet-dry cycles, the moisture concentration in the deep part of mixture risen monotonously, while it varied periodically in the shallow part. The longer the drying period was, the lower the moisture concentration. Moisture concentration of asphalt pavement may be largest at 0.2–0.5 times the layer thickness after intermittent rainfalls. Although pressure can accelerate the diffusion, influence of hydrodynamic pressure on the diffusing depth was not outstanding since the actuation duration of the tire on pavement was too short. [ABSTRACT FROM AUTHOR]

• Effect of fibers on the low temperature performances of asphalt mixture were investigated comprehensively through IDT test. • Elastic moduli of FRAC under different modes were compared. • Anti-cracking action of fibers was revealed using failure strain, fracture time and energy. • Digital image correlation (DIC) technique was adopted to measure the full-field strain and deformation. Fibers have been commonly used to enhance the cracking resistance of asphalt mixtures. However, the reinforcing actions of different fibers have presented diverse effects. Therefore, three kinds of fibers, including glass fibers, basalt fibers and steel fibers, were selected to investigate their influences on the low temperature properties and cracking resistance of asphalt mixtures in this paper. Indirect tensile testing (IDT) was conducted to obtain basic properties such as the Poisson's ratio and moduli. The digital image correlation (DIC) technique was employed to measure the deformation and strain. The crack inhibition action was evaluated by the failure time. The results showed that the fiber type has no influence on the Poisson's ratio of the mixture. However, the addition of fibers remarkably affects the mixture modulus. The modulus and ultimate tensile strength of the reinforced mixture decline after the addition of fibers. The gaps between the compressive and tensile moduli are also increased by the addition of fibers. Moreover, the addition of fibers not only substantially improves the mixture ductility but also delays the fracture process. The fiber reinforced asphalt concrete (FRAC) presents a higher fracture energy (FE) and dissipated creep strain energy (DCSE) than that of the control concrete. Among the selected fibers, basalt fibers exhibit optimal crack resistance performance, while steel fibers are not recommended due to their smooth appearance. [ABSTRACT FROM AUTHOR]

In this paper, Fourier-transform infrared (FTIR) spectroscopy was used to evaluate the effects of diatomite on aging properties of an asphalt binder. The modified asphalts included 5%, 10%, and 15% diatomite, and were prepared in the laboratory. The changes in functional groups of asphalt were employed to investigate the aging mechanisms of the modified and control asphalts. Effects of diatomite on the anti-aging properties of asphalt were analyzed via the changes in intensity of the absorption peaks. Results showed that there were no new functional groups generated after diatomite mixing with asphalt. This indicated that the process of diatomite modification was just physical mixing. Furthermore, parts of saturates and aromatics were volatilized in the aging process of modified asphalt. Polar molecules reacted with oxygen in aging. Meanwhile, carbonyl (C=O) and sulfoxide (S=O) were also generated. The aging resistance of modified asphalt was the best when the diatomite content was 10%. The work of this paper may provide a new perspective to evaluate asphalt aging. [ABSTRACT FROM AUTHOR]

Based on the research results and practical engineering experience pertaining to the protection and reinforcement of the cliff of the Mogao Grottoes in Dunhuang, China, this paper presents a method that is mainly based on the analytic hierarchy process (AHP) to evaluate the preservation state and risk of the Mogao cliff, a means that numerical simulation was conducted to quantitatively evaluate the stability and effectiveness of protective measures for the Mogao cliff, a set of reinforcement methods which integrate the key protection techniques based on propping, anchoring, grouting, and anti-weathering and the quality control measures based on assessing their effectiveness for surrounding rocks of the grottoes, and a set of methods for monitoring and warning based on risk theory throughout the entire reinforcement process. The four above-mentioned techniques complement and support with each other, and every stage is based on research. Additionally, the protection and reinforcement concepts implemented at the Mogao cliff are summarized in this paper. Finally, preventive protection and reinforcement techniques for sandy conglomerate grottoes were established based on the research, evaluation, calculation, and monitoring. The techniques presented in this paper can be used as a theoretical foundation and provide technical guidance for the protection and reinforcement of similar cultural heritage sites all over the world. [ABSTRACT FROM AUTHOR]

Saline soil used in embankment construction causes dissolution falling and salt swelling, which results in embankment cracking. Therefore, saline soils should be stabilized in engineering. The unconfined compressive strength test, triaxial compressive test, splitting tensile test, and fatigue test were conducted on six types of stabilized soils. Subsequently, scanning electron microscopy test, X-ray diffraction test, Fourier transform infrared spectroscopy test, and thermogravimetric analysis were performed to discover the stabilizing mechanism. Test results indicated that the mechanical properties of saline soil were improved by adding lime, cement, fly ash, and SH agent (SH). In particular, after soaking, the strength of the stabilized soil with SH was significantly enhanced, the deviatoric stress-strain curves transformed from strain softening to strain hardening, and the tensile property and fatigue resistance were improved as well. The SH generated a film and silk-like web, wrapped the soil particles, and filled the soil pores, which improved the strength and anti-deformation abilities of the stabilized soils. [ABSTRACT FROM AUTHOR]

The Mogao Grottoes is famous around the world for its exquisite wall paintings and colorful painted sculptures, and was inscribed in the UNESCO World Heritage List in 1987. Although the site is located in an arid area, water is still one of the main factors threatening the long-term preservation of cultural relics. The relationship between rainfall infiltration and wall painting deterioration was investigated as part of efforts to develop conservation strategies to prevent deterioration caused by atmospheric precipitation. This was done through artificial rainfall simulation experiments and high-density electrical non-destructive test. Areas prone to wall painting deterioration, as evidenced by periodic condition assessment, showed an association between further deterioration and natural heavy rainfall. The results show that the covering layer above the grottoes has a small runoff coefficient, and the rainfall infiltration is much larger than the volume of runoff produced. The rainwater migrates preferentially along the rock fractures in the form of gas or through the gaps between the grotto eaves and the rock, or through cracks in the form of liquid. This is the main mechanism for activation of salt damage and deterioration of the wall paintings. The covering layer above the grottoes is thin, and the through-cracks in the surrounding rock or external wooden eaves are particularly vulnerable to rainfall infiltration. This indicates that more attention should be paid to the system of preventive protection by rainwater disposal. This research has important practical value in improving preventive protection of the Mogao Grottoes. [ABSTRACT FROM AUTHOR]

In the Mogao Grottoes of Dunhuang, China, the ambient relative humidity (RH) fluctuation in the caves is the main cause for the deterioration that has been observed, especially the deterioration of the earthen plaster and wall paintings linked to the presence of NaCl and Na2SO4 salt contaminants. To help identify the mechanism responsible for this salt-related deterioration and provide a theoretical basis for the development of a preventive conservation regime, this study addressed the basic moisture adsorption mechanisms of earthen plaster with soluble salts by taking an experimental approach. It is shown that, as ambient RH increases, the moisture adsorption process of the plaster containing the soluble salts can be regarded to have three basic stages, as evidenced by the results of the moisture adsorption tests performed on earthen plaster samples with different NaCl or Na2SO4 contents at various humidity levels. The moisture adsorption mechanism and its determining factors at each stage are also analysed. In addition, it is suggested that the hygroscopicity of the plaster structure and the interaction between the different kinds of salts in the plaster, which makes the dissolution or hydration of the salt in the plaster pores much easier, should be considered more seriously regarding increases in the ambient RH in the caves. [ABSTRACT FROM AUTHOR]

The Dunhuang Mogao Grottoes are a significant cultural heritage site in the Silk Road, famous for its wonderful murals and statues. The rainfall causes the changes of humidity in the caves, which can easily activate the salts diseases of murals. In order to prevent the deterioration of the murals, the environmental monitoring tests were conducted to analyze the microclimate changes of the cave in rainfall weather, and proposed the risk prevention measures and suggestions. The results indicate that the temperature of caves has small change, but the humidity shows a clear trend of increase. The humidity and the duration of high humidity increases with the increase of the rainfall grade and frequency. The optimal starting time for environment control in the cave is when aatm and acave are consistent, and the relative humidity is controlled below 62%. The caves with lower layer, larger degree of openness and small volume are most vulnerable to water vapour diffusion. The environment monitoring should pay more attention to the continuous rainfall weather and the vulnerable caves. The research has great significance for the prevention of ancient mural deterioration. [ABSTRACT FROM AUTHOR]

Numerous cretaceous sandstone grottoes in Longdong area have been suffering from serious weathering, and the weathering is proceeding at a considerable rate, resulting in severe challenges for conservation practice. However, relatively little is known about the weathering behavior and mechanism of cretaceous sandstone in Longdong Area. In this study, cretaceous sandstone in North Grotto Temple was selected as a typical case, and the weathering characteristics from the surface to the interior in real environment were studied by field investigation and laboratory analysis (particle and pore size distribution, soluble salt content, microstructure, mineral and chemical composition). Cretaceous sandstones are mainly litharenite and feldspathic litharenite at the North Grotto Temple (NGT). Efflorescence and subflorescence were confirmed as the main weathering forms for litharenite and feldspathic litharenite, respectively. Sodium sulfate and sodium chloride observed from the SEM images were the most active soluble salts tend to accumulate at the certain depth below the surface (1 cm for litharenite and 3 cm for feldspathic litharenite). The salts migration kinetics inside the cliff were concluded based on the distribution of salts. The K-feldspar increased from the surface to the interior with the kaolinite, illite decreasing, indicating the corresponding alteration of K-feldspar in the surface layer. The weathering indexes indicated that the weathering degree along the depth was nonlinear, whereas the weathering degree was firstly increased and then decreased from the surface to the interior. The experimental results in this study can provide a better understanding for the weathering mechanisms of cretaceous sandstone in Longdong Area. • The weathering mechanism of Cretaceous sandstone from the surface to the interior was investigated; • Nonlinear deterioration pattern of Cretaceous sandstone from the surface to the interior is obtained; • The salts migration kinetics inside the vertical cliff were concluded. [ABSTRACT FROM AUTHOR]

A Si doped interlayer was introduced into the GaAs barrier layer to study optical properties of InGaAs/GaAs surface quantum dots (SQDs). Photoluminescence (PL) measurements show that luminescence of InGaAs/GaAs SQDs is strongly dependent on Si doping concentration. With increasing the Si doping concentration, InGaAs/GaAs SQDs show clearly different luminescence characteristics, including: PL peak position of SQDs shifts to red at first and then to blue; the dependence of PL peak energy on the cubic root of excitation intensity changes from linear to nonlinear; configuration interaction method shows reduced blue shift for PL band; time-resolved PL indicates a transition from nonlinear decay of type-II QDs to linear decay of type-I QDs. These experimental results indicate that Si doping fill the surface states and modify the surface Fermi level pinning effect, thus changing the luminescence characteristics of InGaAs/GaAs SQDs. This research provides a support for understanding and tailing the surface-sensitive characteristics of InGaAs SQDs for development of sensors. [ABSTRACT FROM AUTHOR]

Designated as a world heritage site by UNESCO in 1987, the Mogao Grottoes is famous for its cultural relics, in particular, the superb murals and painted sculptures. Moisture has been confirmed as the most active factor that could result in mural diseases. Therefore, ascertaining the moisture distribution of the cliff is of great significance for preventing the deterioration of murals and painted sculptures. In this study, a multi-electrode resistivity survey is applied atop the cliff of Mogao Grottoes. By deploying survey lines in two main study areas, the moisture distribution of the cliff is reflected by the resistivity profiles qualitatively. The results show that there is a mutually verifying relationship between the resistivity profiles and the water content of the exploratory well. In general, the resistivity of the cliff body is low in the distribution range of 1–300 Ω·m. It shows that the moisture content of these gullies atop the cliff is even lower. Besides, four potential danger areas are determined on the cliff face. Murals in these caves, which are excavated in these areas, will suffer more serious deterioration due to the moisture migration. The result also ascertains that the resistivity of the cliff could determine the moisture distribution inside the cliff. Moreover, this study can provide a firm scientific basis for protecting the valuable murals and painted sculptures in the caves. [ABSTRACT FROM AUTHOR]

Cracking of asphalt pavement is mostly caused by the mixed fracture of asphalt concrete. Determining a simple, repeatable, and accurate method is necessary for evaluating the fracture resistance of asphalt concrete. To explore the mixed fracture performance of asphalt concrete and determine the feasibility of different semicircular bend methods, the mixed fracture performances of asphalt concrete at medium and low temperatures were measured. The mixed fracture modes were realized through changing the position of the support and notch or changing the notch angle. After that, the crack propagating characteristics, crack initiation angle, and fracture toughness were analyzed. Results show that temperature has a significant impact on the fracture path, and crack initiation angle at low temperature follows the generalized maximum tangential stress (GMTS) theory. The measured fracture toughness ratios are lower than the theoretical value of GMTS criterion, but the established empirical model has higher accuracy. In the semicircular bend method, changing the positions of the support and notch is stable and repeatable. Therefore, this method may be preferred to evaluate the mixed fracture performance of asphalt concrete in the future. [ABSTRACT FROM AUTHOR]

The ramming technique is a traditional method used to improve the compactness of soil with impact and vibration energy. Based on the measured data of ramming force transmission and dissipation, this study reveals the mechanism of energy transfer and dissipation of single-layer ramming as well as the law of variation with ramming quality, laying thickness, and ramming times. It also establishes the ramming model and empirical formula of ramming quality, laying thickness, and ramming times, introduces the ramming layer changes associated with the constitutive relationship (elastic to elastoplastic parts) as a function of ramming times, and determines the influence depth and horizontal range based on real-time data monitoring. It was found that as the mass of the rammer increases, the range of influence of the impact stress inside the earth also increases proportionally, and this effect is more pronounced vertically. However, the dissipation rate of energy in horizontal direction is much greater than in the vertical direction. The traditional stacked ramming technique of "chong hai wo, hang yin ding" can effectively eliminate the defects of horizontal reversal upwelling impact and unevenness of the ramming layer during the ramming process. The research results provide a theoretical basis for evaluating the quality of the traditional ramming technique. [ABSTRACT FROM AUTHOR]

Asphalt aging has a direct influence on the durability of asphalt mixture. In order to improve thermal oxidizing aging resistance of asphalt, the commercial antioxidants including Irganox 1010 and Irgafos 168 were selected to modify base asphalt and SBR asphalt. The basic properties of modified asphalt before and after the rolling thin film oven test (RTFOT) are evaluated by penetration, softening point, ductility, and viscosity. The Fourier transform infrared spectroscopy (FTIR) test was applied to determine the antiaging mechanism of modified and unmodified asphalt. According to the test result, Irganox 1010 not only reduces the aging degree of asphalt but also has little adverse effect on other properties. Irgafos 168 with a content of 1% improves the low temperature ductility of asphalt and improves the antiaging performance of asphalt significantly. After RTFOT, the content of oxygen-containing functional groups (carbonyl group and sulfoxide group) declines significantly in antioxidation modified asphalt, and Irganox 1010 and Irgafos 168 inhibit oxidizing reaction in the aging procedure. This study can provide a useful reference for improving the aging property of asphalt in highway construction. [ABSTRACT FROM AUTHOR]

A series of Sm 3+ , Eu 3+ , and Sm 3+ /Eu 3+ doped LiBaB 9 O 15 are synthesized by a high temperature solid-state method. LiBaB 9 O 15 :Eu 3+ can produce red emission ( λ ex = 395 nm), and the peak locates at 616 nm, which is attributed to 5 D 0 → 7 F 2 transition of Eu 3+ . LiBaB 9 O 15 :Sm 3+ can create orange–red emission ( λ ex = 395 nm), and the peak locates at 599 nm, which is assigned to 4 G 5/2 → 6 H 7/2 transition of Sm 3+ . The energy transfer from Sm 3+ to Eu 3+ in LiBaB 9 O 15 is confirmed by decay times of Sm 3+ . When the temperature is 150 °C, the emission intensity of Eu 3+ in LiBaB 9 O 15 :0.05Sm 3+ , 0.1Eu 3+ is decreased to 76% of the initial intensity at room temperature, and the activation energy is calculated to be 0.268 eV, which prove good thermal stability of LiBaB 9 O 15 :Sm 3+ , Eu 3+ . The emission intensity of LiBaB 9 O 15 :Sm 3+ , Eu 3+ can be tuned by tuning Eu 3+ content, and Commission International de I’Eclairage (CIE) chromaticity coordinates of LiBaB 9 O 15 :Sm 3+ , Eu 3+ are located in the red region. [ABSTRACT FROM AUTHOR]

A yellow emitting phosphor Sr 2 ZnMoO 6 :Dy 3+ is synthesized by a solid state reaction at 1250 °C for 4 h, and its luminescent properties are investigated. Its phase formation is carried out with X-ray powder diffraction analysis, and there has no crystalline phases other than Sr 2 ZnMoO 6 . Sr 2 ZnMoO 6 :Dy 3+ can produce yellow emission under the 272 and 387 nm radiation excitation, and the prominent luminescence in yellow (575 nm) due to the 4 F 9/2 – 6 H 13/2 transition of Dy 3+ . For the 575 nm emission, the excitation spectrum present one broad band and some narrow bands, and the peaks locate at 272, 324, 350, 365, 387, 426 and 474 nm, respectively. Its emission intensity is influenced by the Dy 3+ doping concentration, and the concentration quenching effect is also observed. The CIE chromaticity coordinates values of Sr 2 ZnMoO 6 :Dy 3+ show the almost same results with the different Dy 3+ concentration, and locate in the yellow region. [ABSTRACT FROM AUTHOR]

A series of Ca 2 PO 4 Cl:Ce 3+ , Mn 2+ phosphors are synthesized by a high temperature solid state reaction method, and their luminescent properties are investigated. Ca 2 PO 4 Cl:Ce 3+ , Mn 2+ has an obvious absorption in the region of 300–350 nm, and energy transfer from Ce 3+ to Mn 2+ in Ca 2 PO 4 Cl has been validated, and proved to be a resonant type via a dipole–dipole interaction. Orange red emission intensity of Mn 2+ can be obviously enhanced via the efficient energy transfer from Ce 3+ to Mn 2+ , and critical distance of energy transfer is also calculated by concentration quenching method, and about 14.1 Å. The results show that Ce 3+ ion may be an available sensitizer for Ca 2 PO 4 Cl:Mn 2+ , and Ca 2 PO 4 Cl:Ce 3+ , Mn 2+ may have potential application in white light emitting diodes. [ABSTRACT FROM AUTHOR]

A series of Ca4- y Y6- x O( SiO4)6: x Ce3+, y Eu2+ samples are synthesized by a high-temperature solid-state method. Under 356 nm excitation, Ca4 Y6 O( SiO4)6: Ce3+ presents a strong blue emission band at 426 nm which are assigned to 4 f05 d1→4 f1 transition of Ce3+ ion. Ca4 Y6 O( SiO4)6: Eu2+ shows green emission under 380 nm radiation excitation, and the peak locates at 527 nm which is mainly due to transitions of Eu2+ from 4 f7 ground state to 4 f65 d1 excited state. Under 356 nm excitation, a remarkable energy transfer from Ce3+ to Eu2+ exists in Ca4 Y6 O( SiO4)6, and the result reveals that the mechanism of energy transfer is a resonant type via a nonradiative dipole-dipole interaction. The hues of Ca4 Y6 O( SiO4)6: Ce3+, Eu2+ can be adjusted by the energy transfer from Ce3+ to Eu2+ ions, and a white emission can be achieved by tuning the ratio of Ce3+ to Eu2+. The results mean that Ce3+ may be the effective sensitizer for Eu2+-doped Ca4 Y6 O( SiO4)6. [ABSTRACT FROM AUTHOR]

Highlights: [•] Eu2+, Tb3+ and Mn2+ doped BaMg2(PO4)2 emits blue, green and red light, respectively. [•] Energy transfer from Eu2+ to Tb3+ and Mn2+ in BaMg2(PO4)2 occurs. [•] BaMg2(PO4)2:Eu2+, Mn2+, Tb3+ can emit warm white light. [ABSTRACT FROM AUTHOR]

• Combined MIP-CT method was developed to explore pore evolution at Mogao Grottoes. • Pores > 355 μm (undetectable by MIP) make up most of pore volume in conglomerate. • Median/mean pore diameters increased by 8–10 times during conglomerate weathering. • Loss of calcite and clay minerals decreased cementation degree during weathering. • Wind erosion and salt weathering caused major cement loss and porosity generation. Numerous conglomerate grottoes have been excavated and preserved in the arid and alkaline regions of NW China. After millennia of weathering, these conglomerate grottoes have suffered from various weathering issues (such as seepage and collapse) that are internally governed by the distribution of pore networks and the degree of cementation. However, studies on conglomerate weathering have mostly been reported in humid and tropical climates, where intensive chemical weathering occurs. Additionally, characterizations of pore evolution during conglomerate weathering have been restricted due to limitations in detecting pore size and pore type using a single pore characterization method. To fill this gap, this study jointly used mercury intrusion porosimetry (MIP) and computed tomography (CT) to characterize the pore evolution process during conglomerate weathering at Mogao Grottoes, a world heritage site in NW China. Mineralogical, hydrological, mechanical and microscopic characterization were also conducted to understand the changes in compositions of bulk samples and cements during weathering. Results revealed that the majority of pores in conglomerate are concentrated in macropores > 5 μm, followed by mesopores and micropores. During weathering, volume fraction of macropores significantly increases and that of micropores decreases, with median/average pore diameters experiencing an 8- to 10-fold increase. Permeability, porosity and fractal dimension exhibited strong positive linear correlations with median/average pore diameters. Throughout weathering, the abundances of calcite and clay minerals show notable decrease, particularly in cements, resulting in an enrichment of feldspars. Frequently occurring sand-carrying wind activities and salt weathering in arid regions are inferred to be responsible for the major cement loss and porosity generation through physical processes. Our combined MIP-CT method for pore network characterization is also applicable to other lithologies with a wide range of pore sizes. The proposed mechanism of pore evolution and cementation failure provides a scientific base for protecting stone heritages in arid zones. [ABSTRACT FROM AUTHOR]

Enzyme-induced calcium carbonate precipitation (EICP) and microbially-induced calcium carbonate precipitation (MICP) techniques represent emerging trends in soil stabilization. However, the impact of soil density on biomineralization, particularly in historical earthen sites, remains unclear. This study compares the consolidation effects of EICP and MICP on cylindrical samples (10 cm × 5 cm) with three densities (1.5 g/cm3, 1.6 g/cm3, and 1.7 g/cm3) derived from the soil near the UNESCO World Cultural Heritage Site of Suoyang Ancient City, Gansu Province, China. Results showed that calcium carbonate production increased across all densities through bio-cementation, with higher densities producing more calcium carbonate. MICP-treated specimens exhibited larger increases in calcium carbonate production compared to those treated with EICP. Specimens with a density of 1.7 g/cm³ showed a wave velocity increase of 3.26% (EICP) and 7.13% (MICP), and an unconfined compressive strength increase of 8% (EICP) and 26% (MICP). These strength increases correlated with the generation of calcium carbonate. The findings suggest that biomineralization can be effectively utilized for in situ consolidation of earthen sites, emphasizing the importance of considering soil density in biologically-based conservation technologies. Furthermore, MICP shows potential advantages over EICP in providing stronger, compatible and more sustainable soil reinforcement. [Display omitted] • Higher initial soil densities lead to greater CaCO 3 production via bio-cementation. • 1.7 g/cm³ specimens show significant increases in wave velocity and strength after treatments. • The reinforcement effects and compatibility of MICP are superior to EICP. [ABSTRACT FROM AUTHOR]

The theoretical model of a photorefractive optical switch, which is implemented by adjusting the polarization of the readout beam to control the diffraction efficiency of volume grating in a Ce:KNSBN crystal, is proposed. The experimentally measured diffraction efficiency with an extraordinarily polarized readout beam is about 20 times that with an ordinarily polarized readout beam, which agrees with the theoretical prediction and indicates that Ce:KNSBN possesses excellent optical switching properties. [Copyright &y& Elsevier]

• 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]

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]

Dryland regions are exposed to extreme environmental conditions that create hotspots of weathering and erosion. Many earthen heritage sites are located in these dryland regions and experience extensive deterioration driven by interactions with environmental processes, however previous research has focused largely on the role of rain as a driver of deterioration. This study combines approaches from geomorphology with understandings of earthen materials from heritage science to investigate the relative importance of wind and rain in driving earthen heritage deterioration in drylands. We use geomorphological signatures to infer the environmental histories of earthen walls with a range of known ages at Suoyang Ancient City, China, using semi-quantitative deterioration assessments. We find rain-driven deterioration features to be associated with the loss of larger volumes of material and to have higher persistence than wind-driven deterioration features. However, we argue that the high frequency nature of wind events means that wind is an important initiator of deterioration across the site. In addition, walls exposed to the prevailing wind are dominated by wind-driven deterioration features. Outcomes from this study present an opportunity for earthen heritage conservation to investigate potential strategies to minimise wind speed at earthen heritage sites in drylands. • Geomorphological signatures reveal drivers of earthen heritage deterioration. • High frequency of wind events in drylands causes substantive cumulative impact. • Wind-driven deterioration features typically have low persistence. • Wind is an important initiator of earthen heritage deterioration. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present a theoretical study of the linewidth and contrast of electromagnetically induced transparency (EIT). The EIT is associated with a homogenously broadened three-level system interacting with a couple and a probe laser field in a Λ configuration. The optical Bloch equation is solved, from which analytic solutions for the EIT linewidth and contrast are derived. It is shown that the analytical results are in good agreement with the numerical calculation of the EIT spectrum and gives a satisfactory account of the power-broadening behavior for a broad range of the couple laser Rabi frequency where the EIT evolves from a narrow spectral hole into well-separated dynamic Stark doublet. [Copyright &y& Elsevier]

Keywords: Sandstone; Rock-hewn; Cave-temple; Deterioration patterns; Karsten tube; Sorptivity; Equotip hardness tester; Surface hardness EN Sandstone Rock-hewn Cave-temple Deterioration patterns Karsten tube Sorptivity Equotip hardness tester Surface hardness 2915 2920 6 06/05/20 20200601 NES 200601 Introduction Rock-hewn cave-temples are a form of Buddhist temple architecture. Second, the hardness of each sandstone bed (up to 1.5 m above the ground) at four sites (three niches and the natural rock face to the north of the NGT façade) was measured using a Proceq Equotip 3 hardness tester (with D probe) (see Figs. In addition, it is worth noting that where alveolar weathering is found, surface hardness values are slightly greater than the average surface hardness of all beds at that measurement location, such as layer d at niche 101. Sandstone, Rock-hewn, Cave-temple, Deterioration patterns, Karsten tube, Sorptivity, Equotip hardness tester, Surface hardness. [Extracted from the article]

Carrier dynamics including carrier relaxation and tunneling within a coupled InAs quantum dot (QD) – In 0.15 Ga 0.85 As quantum well (QW) hybrid nanostructure are investigated using photoluminescence (PL) spectroscopy. This coupled hybrid nanostructure shows a single PL peak from the QD emission at low excitation intensity and a band filling behavior is observed as the excitation intensity increases, suggesting that there exists a channel to capture carriers from the QW to the QDs. Time resolved PL (TRPL) measurements extract a carrier tunneling time of 103.7 ps, which is only one third of the theoretical prediction. A double-channel resonant carrier tunneling mechanism from the QW to the wetting layer and to the fifth excited state of the QDs and then carrier relaxation into lower discrete QD energy states is proposed to explain this fast carrier tunneling. The double-channel resonant carrier tunneling mechanism is qualitatively supported through the analysis of the excitation-dependent PL spectra as well as the PL excitation spectra. These results enrich our understanding of carrier dynamics in coupled QD and QW hybrid structures. [ABSTRACT FROM AUTHOR]

The optical properties have been investigated for the GaAs/Al 0.2 Ga 0.8 As quantum dot-ring hybrid nanostructures grown by droplet epitaxy, in which each nanostructure consists of four quantum dots (QDs) sitting on a distinct ring of GaAs. A blueshift and narrowing of the photoluminescence (PL) spectra along with the nonlinear decay of the time-resolved PL curves of the QDs have been observed. These abnormal PL behaviors are caused by the unique state filling effect correlated with the quantum dot-ring structure feature, which is strongly affected by carrier transfer from smaller dots to larger dots via the wetting ring in the GaAs/Al 0.2 Ga 0.8 As hybrid structure. [ABSTRACT FROM AUTHOR]