Multiscale Investigation Research Articles

Investigation on physico-mechanical properties and microstructural evolution patterns of heated granite after liquid nitrogen cooling

Liquid nitrogen (LN2) fracturing is recognized as an innovative reservoir enhancement technique, demonstrating significant potential in establishing high permeability pathways in geothermal development. Understanding the physico-mechanical properties and microscopic mechanisms of hot dry rock post LN2 cooling treatment is pivotal for promoting the effective deployment of LN2 fracturing. This study undertook physical and mechanical testing on a quintessential hot dry rock type-granite-post various temperature and LN2 cooling treatments. Subsequently, a multi-scale investigation was conducted on the thermal fracture-pore structure's morphological features and the evolution of mineral components. The experimental findings indicated that LN2 cooling exerts a pronounced impact on the physico-mechanical properties of high-temperature granite. Temperature-induced damage to granite can be delineated into three phases: initial phase up to 200 °C where its effects are relatively imperceptible; an intermediate phase from 200 to 500 °C characterized by gradual deterioration; and a pronounced degradation phase evident at 600 °C. Correlations between the changes in the micro pore-fracture structure of granite and its physico-mechanical property degradation were subsequently established. As temperature escalated, the area of micro-defects in the CT-reconstructed spatial distribution increased progressively. The volumetric porosity damage ratio and fractal dimensions were quantitatively introduced to characterize the fractal geometric features and distribution patterns of internal thermal fractures in granite post thermal shock. Concurrently, NMR experiments indicated that with the escalation of temperature, micropore develop and interlink to form mesopore and macropore, enhancing rock porosity connectivity. These macropores significantly influence granite's physico-mechanical and permeability characteristics. A mineral stability analysis revealed that various minerals undergo physico-chemical reactions, such as dehydration, phase transitions, decomposition, and chemical bond fractures at elevated temperatures, altering mineralogical composition and mineral strength, thus impacting the rock's macroscopic properties. Ultimately, the study delved into the damage mechanisms of granite's physico-mechanical properties from both heating and cooling perspectives during various temperature phases. The insights garnered from this investigation offer novel value in comprehending the thermal damage characteristics induced by LN2 cooling.

A Novel Approach towards Assessing the Impact of Air Quality and Major Public Health Emergencies on Light Industry: A Multiscale Investigation towards Improving the Risk Prevention System

Measuring the systemic impact of major public health emergencies on the light industry and preventing various uncertain future external risks have become the key challenges to ensuring the stability of the light industry. This paper takes the occurrence of major public health emergencies as the background and focuses on environmental issues such as air pollution and indoor air quality degradation during emergencies. And to explore the multiscale impact of major public health emergencies on the light industry, typical light industry subsectors, and light industry enterprises. The findings of our study reveal that major public health emergencies have a negative impact on the light industry, particularly in the form of a short-term decline in exports, which tends to converge in the long run. Further, it is also revealed that there is heterogeneity in the impact on environmentally sensitive industries, labor-intensive industries, and others. At the microfirm level, major public health emergencies have shown a negative effect, especially the recent pandemic, which has a longer duration and a wider reach. Through multiscale research, this paper provides policy suggestions to improve the macrogovernance mechanism and risk prevention system for the light industry.

Genetic insights into the dissolution of dioecy in diploid persimmon Diospyros oleifera Cheng

BackgroundDioecy, a sexual system of single-sexual (gynoecious/androecious) individuals, is rare in flowering plants. This rarity may be a result of the frequent transition from dioecy into systems with co-sexual individuals.ResultsIn this study, co-sexual expression (monoecy and hermaphroditic development), previously thought to be polyploid-specific in Diospyros species, was identified in the diploid D. oleifeara historically. We characterized potential genetic mechanisms that underlie the dissolution of dioecy to monoecy and andro(gyno)monoecy, based on multiscale genome-wide investigations of 150 accessions of Diospyros oleifera. We found all co-sexual plants, including monoecious and andro(gyno)monoecious individuals, possessed the male determinant gene OGI, implying the presence of genetic factors controlling gynoecia development in genetically male D. oleifera. Importantly, discrepancies in the OGI/MeGI module were found in diploid monoecious D. oleifera compared with polyploid monoecious D. kaki, including no Kali insertion on the promoter of OGI, no different abundance of smRNAs targeting MeGI (a counterpart of OGI), and no different expression of MeGI between female and male floral buds. On the contrary, in both single- and co-sexual plants, female function was expressed in the presence of a genome-wide decrease in methylation levels, along with sexually distinct regulatory networks of smRNAs and their targets. Furthermore, a genome-wide association study (GWAS) identified a genomic region and a DUF247 gene cluster strongly associated with the monoecious phenotype and several regions that may contribute to andromonoecy.ConclusionsCollectively, our findings demonstrate stable breakdown of the dioecious system in D. oleifera, presumably also a result of genomic features of the Y-linked region.

Multi-scaling analysis of turbulent boundary layers over an isothermally heated flat plate with zero pressure gradient

A meticulous investigation into turbulent boundary layers over an isothermally heated flat plate with zero pressure gradient has been conducted. Eight distinct turbulence models, including algebraic yPlus, standard k-ω, standard k-ε, length-velocity, Spalart-Allmaras, low Reynolds number k-ε, shear stress transport, and v2-f turbulence models, are carefully chosen for numerical simulation alongside thermal energy and Reynolds-Averaged Navier-Stokes equations. A comparative analysis has determined that the Spalart-Allmaras model exhibits remarkable agreement with the results from direct numerical simulation, making it a reliable tool for predicting turbulent heat transfer and fluid flow, particularly at higher Prandtl and Reynolds numbers. Subsequently, a multi-scale investigation employs a comprehensive four-layer structure scheme and encompasses various momentum thickness Reynolds numbers of 1432, 2522, and 4000, and Prandtl numbers of 0.71, 2, and 5. The subsequent investigation reveals the governing non-dimensional numbers' substantial impact on the distribution and magnitude of mean thermal and flow characteristics. Notably, the scaling of mean thermal and momentum fields discloses the existence of a meso or intermediate layer characterized by a logarithmic nature unique to itself. The multi-scaling analysis of the flow field demonstrates greater conformity with the selected scaling variables primarily relying on the Reynolds number. Furthermore, the scaling of the energy field yields compelling outcomes within the inner and intermediate layers. However, according to the four-layer theory, minor discrepancies are observed in the outer layer when using the current scaling.

Multivariate and multiscale investigation of ammonia production and emission mechanisms during membrane-covered cattle manure/wheat straw aerobic composting

Ammonia (NH3) emissions accompanying aerobic composting cause significant atmospheric pollution and nitrogen losses. Understanding the mechanisms of NH3 production and emission can help optimize composting strategies. Here, environmental parameters, microbial communities, microbial metabolism, and organic component degradation were characterized at the pile and particle scales during atmospheric aerobic composting and in two membrane-covered aerobic composting (MCAC) systems. Pile-scale results showed that NH3 emission was concentrated in the thermophilic phase; MCAC significantly increased the relative abundances of aerobic lignocellulose-degrading bacteria, carbohydrate-degrading enzymes, and deaminases (P < 0.05); MCAC increased microbial ammonification and carbon source use. The degradation and distribution of organic components in compost particles were visualized for the first time by Fourier transform infrared microspectroscopy: MCAC increased the degradation of polysaccharide-like substances and glycoside-like substances in the particles, and accelerated the degradation of proteins to amide-like substances within the outer layer ∼ 25 μm of particles. We speculated that the micro-positive pressure (∼500 Pa) created by MCAC enhanced the dissolution–diffusion of oxygen into compost particles, thereby facilitating aerobic degradation of organic components. Taken together, micro-positive pressure in the MCAC systems promoted the co-degradation of carbon and nitrogen substrates, which probably increased NH3 production potential, while the water films attached to the inside and outside of the semi-permeable membrane in MCAC were effective in reducing NH3 release by 7.11 %–12.42 %. These findings provide new insights for MCAC improvement.

Driving sustainable energy storage: A multi-scale investigation of methane hydrate formation with green promoters and innovative reactor design

Synthetic Gas hydrates are promising materials for safe and compact energy storage but their wide-scale application is hindered by slow formation kinetics. We investigated the effect of green kinetic promoters of H-SSZ-13 zeolite, L-tryptophan, L-leucine, and L-methionine in a novel reactor design to accelerate hydrate formation at 6 MPa. In (NSR), H-SSZ-13 and L-tryptophan showed superior performance over L-leucine and L-methionine. While H-SSZ-13 showed the lowest average (t90) of 286 mins and the highest volumetric capacity of 115 V/V at 283 K, its kinetic performance, along with other promoters, dropped significantly at 293 K. We introduced a new (FBR) equipped with light (MFP) to increase gas diffusion and thermal conductivity. The combined effect of (FBR)-(MFP) reactor with zeolite significantly improved the kinetics overcoming (NSR) drawbacks. At 293.15 K, H-SSZ-13 zeolite promoter showed superior performance reducing the induction time and (t90) to 3 and 154 mins, respectively. Furthermore, it exploited 88.6%, and 96% of the sII clathrates volumetric storage capacity at 293 K and 283 K, respectively. Finally, we showed that the synthesized hydrates can be stored at atmospheric pressure for 4 months without significant methane loss. This multi-scale approach is paving the way for scaling up green and economical gas hydrate technology.

Controlling the Formation of Electroactive Graphene-Based Cementitious Composites: Towards Structural Health Monitoring of Civil Structures.

The development of composites combining multiple components each one imparting a specific function to the ensemble is highly sought after for disruptive applications in chemistry and materials science, with a particular importance for the realization of smart structures. Here, we report on the development of an unprecedented multifunctional cementitious composite incorporating reduced graphene oxide (rGO). By design, this material features significantly enhanced electrical properties while retaining the excellent cement's hydration and microstructure. The multiscale investigation on the chemical and physical properties of the dispersion made it possible to establish an efficient preparation protocol for rGO aqueous dispersion as well as rGO-based cementitious composites using a commercial poly(carboxylate ether)-based superplasticizer. The conduction mechanisms within the matrix of rGO containing mortars were unraveled by electrochemical impedance spectroscopy revealing conductive paths originating from bulk cement matrix and rGO nanosheets in composites with rGO loadings as low as 0.075 wt. %. For this rGO loading, we observed the reduction of the resistivity of bulk cement mortar layers from 18.3 MΩ cm to 2.8 MΩ cm. Moreover, the addition of 0.2 wt. % of rGO resulted in the formation of rGO conductive paths with the resistivity of 51.1 kΩ cm. These findings represent a major step forward towards the practical application of graphene-based materials in structural health monitoring of concrete structures.

Galactic ‘Snake’ IRDC G11.11−0.12: a site of multiple hub–filament systems and colliding filamentary clouds

ABSTRACT To probe star formation processes, we present a multiscale and multiwavelength investigation of the ‘Snake’ nebula/infrared dark cloud G11.11−0.12 (hereafter, G11; length ∼27 pc). Spitzer images hint at the presence of subfilaments (in absorption), and reveal four infrared-dark hub–filament system (HFS) candidates (extent &amp;lt; 6 pc) towards G11, where massive clumps (&amp;gt; 500 M⊙) and protostars are identified. The 13CO(2–1), C18O(2–1), and NH3(1,1) line data reveal a noticeable velocity oscillation towards G11, as well as its left part (or part-A) around Vlsr of 31.5 km s−1, and its right part (or part-B) around Vlsr of 29.5 km s−1. The common zone of these cloud components is investigated towards the centre of G11 housing one HFS. Each cloud component hosts two subfilaments. In comparison to part-A, more APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) clumps are observed towards part-B. The JWST near-infrared images discover one infrared-dark HFS candidate (extent ∼0.55 pc) around the massive protostar G11P1 (i.e. G11P1-HFS). Hence, the infrared observations reveal multiple infrared-dark HFS candidates at multiscale in G11. The Atacama Large Millimeter/submillimeter Array (ALMA) 1.16-mm continuum map shows multiple finger-like features (extent ∼3500–10 000 au) surrounding a dusty envelope-like feature (extent ∼18 000 au) towards the central hub of G11P1-HFS. Signatures of forming massive stars are found towards the centre of the envelope-like feature. The ALMA H13CO+ line data show two cloud components with a velocity separation of ∼2 km s−1 towards G11P1. Overall, the collision process, the ‘fray and fragment’ mechanism, and the ‘global non-isotropic collapse’ scenario seem to be operational in G11.

Multiscale physiological responses to nitrogen supplementation of maize hybrids.

Maize (Zea mays) production systems are heavily reliant on the provision of managed inputs such as fertilizers to maximize growth and yield. Hence, the effective use of nitrogen (N) fertilizer is crucial to minimize the associated financial and environmental costs, as well as maximize yield. However, how to effectively utilize N inputs for increased grain yields remains a substantial challenge for maize growers that requires a deeper understanding of the underlying physiological responses to N fertilizer application. We report a multiscale investigation of five field-grown maize hybrids under low or high N supplementation regimes that includes the quantification of phenolic and prenyl-lipid compounds, cellular ultrastructural features, and gene expression traits at three developmental stages of growth. Our results reveal that maize perceives the lack of supplemented N as a stress and, when provided with additional N, will prolong vegetative growth. However, the manifestation of the stress and responses to N supplementation are highly hybrid-specific. Eight genes were differentially expressed in leaves in response to N supplementation in all tested hybrids and at all developmental stages. These genes represent potential biomarkers of N status and include two isoforms of Thiamine Thiazole Synthase involved in vitamin B1 biosynthesis. Our results uncover a detailed view of the physiological responses of maize hybrids to N supplementation in field conditions that provides insight into the interactions between management practices and the genetic diversity within maize.

Tailoring crack width control of LC3-based engineered cementitious composites (ECC) via fiber hybridization: From micromechanics design to macro investigation

As a class of strain-hardening cement-based material, Engineered Cementitious Composites (ECC) feature high tensile ductility and multiple cracking. However, ECCs reinforced with hydrophobic fibers attain high ductility but also exhibit larger crack widths caused by the weak bonding of the fiber/matrix interface, attenuating the durability potential of resulting infrastructures. This research aims at tailoring the crack width control ability of ECC through hybridizing hydrophilic PVA and hydrophobic PP fiber. A systematic design procedure was proposed based on the micromechanical analysis with a multi-scale investigation. Experimental results verified the hypothesized composite ductility enhancement by PP fiber and strength enhancement and crack width reduction by PVA fiber. Tight crack width of 50 μm at 2 % tensile strain can be achieved by a fiber hybridization ratio of 1:1 to ensure extreme durability. Changes in the microstructure of the matrix, associated with fresh property alteration due to fiber hybridization, were captured by micro CT scanning. Finally, the trade-off between mechanical performance, durability, and material sustainability was investigated for optimal material design. This research demonstrates that hybridizing PVA fiber with PP fiber holds promise to enhance material sustainability while maintaining the advantageous characteristics of ductile ECC and tight crack width for extreme durability.

Multi-Scale Ground Deformation Analysis and Investigation of Driver Factors Based on Remote Sensing Data: A Case Study of Zhuhai City

Ground deformation poses an imminent threat to urban development. This study uses the multiscale geographically weighted regression (MGWR) model to investigate the spatial heterogeneity in factors influencing ground deformation, thereby elucidating the drivers behind regional variations in ground deformation patterns. To gain insights into the characteristics of ground deformation in Zhuhai, China, and its spatial relationship with natural and anthropogenic features, we initially utilized the small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method to collect data on ground deformation and its distribution across the entire area. Concurrently, remote sensing imagery was used to identify the various mechanisms affecting ground deformation during the same period, including geotectonic conditions, geographic environment, and human activities. Subsequently, we used the MGWR model to quantitatively estimate the effects of these driving force factors on ground deformation in Zhuhai. Our findings reveal significant ground deformation in specific areas, including Baijiao Town (Doumen District), Hongqi Town (Jinwan District), the Gaolan Port Economic Zone, and the northern part of Hengqin Town, with peak deformation rates reaching 117 mm/y. Key drivers of ground deformation in Zhuhai include NDVI, groundwater extraction intensity, and soft soil thickness. The application of the MGWR model, with an R-sq value of 0.910, outperformed both the global regression model ordinary least squares (OLS), with an R-sq value of 0.722, and the local regression model geographically weighted regression (GWR), with an R-sq value of 0.770, in identifying driving forces. This study can provide valuable insights for government policies aimed at mitigating the disaster risks associated with urban ground deformation.

Visualization of Self-Assembly and Hydration of a β-Hairpin through Integrated Small and Wide-Angle Neutron Scattering.

Fundamental understanding of the structure and assembly of nanoscale building blocks is crucial for the development of novel biomaterials with defined architectures and function. However, accessing self-consistent structural information across multiple length scales is challenging. This limits opportunities to exploit atomic scale interactions to achieve emergent macroscale properties. In this work we present an integrative small- and wide-angle neutron scattering approach coupled with computational modeling to reveal the multiscale structure of hierarchically self-assembled β hairpins in aqueous solution across 4 orders of magnitude in length scale from 0.1 Å to 300 nm. Our results demonstrate the power of this self-consistent cross-length scale approach and allows us to model both the large-scale self-assembly and small-scale hairpin hydration of the model β hairpin CLN025. Using this combination of techniques, we map the hydrophobic/hydrophilic character of this model self-assembled biomolecular surface with atomic resolution. These results have important implications for the multiscale investigation of aqueous peptides and proteins, for the prediction of ligand binding and molecular associations for drug design, and for understanding the self-assembly of peptides and proteins for functional biomaterials.

Experimental and multiscale investigation of the elastic and impact properties of glass fibers/Elium acrylic modified nanoparticles laminate composites

The mechanical behavior of the laminate composites based Nanostrength®M53 or Graphistrength® CW2-L A1 at different weight fractions (wt%) was studied. An experimental procedure and a numerical simulation were used for the characterization of the microstructures. The Young modulus decreased with the addition of Nanostrength whereas it increased up to 2 wt% and then decreased, in the presence of Graphistrength. The impact response at 10 wt% of the Nanostrength was better in terms of load peak and absorbed energy. The variation of the Young modulus mainly depended on the weight fraction of the nanoparticles, the dispersion state and their initial characteristics. The same observations have been mentioned for the low velocity impact response.

Multi-scale investigation on gas transport behaviour of compacted granular bentonite under partially saturated states

Compacted bentonites with high swelling potential and low permeability are under consideration as buffer/backfill materials in deep geological repositories of radioactive nuclear waste [1]. Within the short-term service period, the bentonite undergoes progressive saturation developing the swelling pressure, due to the water received from the host rock. Since the progressive saturation first occurs at the boundaries near the host rock, the bentonite close to the fuel canister could remain partially saturated for a long time. Within the long-term running stage, bentonite will withstand the accumulation and transport of gases such as H2 (mainly generated by the anaerobic corrosion of the metallic overpack of canisters) [2]. The accumulated volume of gas can produce a gas pressure build-up that could break through the bentonite, damaging its microstructural integrity and isolation capacity for radionuclides and contaminants [3]. This issue may be improved by adopting granular bentonite (GB) with an extended particle size distribution (maximum grain sizes of the order of mm) [4]. The compacted GB has a high initial macroporosity, which might permit gas transport at low pressures with less impact on the microstructure. However, up to now, few investigations have focused on the gas transport behaviour of partially saturated compacted GB within a multi-scale perspective.&#x0D; To this end, gas injection tests were performed on partially saturated compacted MX-80 type GB at different hydro-mechanical states. Effective gas permeability was measured in samples at the as-compacted state and in samples prepared at the as-compacted state and then partially saturated under isochoric conditions without additional vertical stress apart from the generated due to swelling. Additionally, the tests were also conducted on these two types of samples but subjected to initial vertical stress of 3.8 MPa. X-ray micro-tomography in combination with mercury intrusion porosimetry was employed to observe the microstructural characteristics of samples before and after gas injection. The results highlight that the pore network of compacted GB is constituted of inter-granular, inter-aggregate and intra-granular/aggregate pores. Increasing the as-compacted degree of saturation Sr reduces the proportion of inter-granular pores and the effective gas permeability Ka.eff (Figure 1(a)). For the as-compacted sample, gas transport can induce the size of inter-granular/aggregate pores to extend (Figure 1(b)). When the initial vertical stress is applied on the as-compacted sample, Ka.eff decreases, with the closure of inter-granular/aggregate pores. Although the progressive saturation of the as-compacted samples under constant volume causes the reduction of inter-granular/aggregate pores, they are mainly filled with the low-density bentonite gel and the accumulated gas pressure is able to reopen and connect them to form fissures (Figure 1(b)). Thereby, at a given Sr resulting from this saturation process, Ka.eff is similar to that at the same as-compacted Sr (Figure 1(a)). However, the decrease in Ka.eff is significant, when the progressive saturation is conducted under vertical stress. This is because many inter-granular/aggregate pores collapse during the saturation process, and the vertical stress restrains the formation of fissures driven by gas pressure. On the other hand, gas transport does not affect the distribution of intra-granular/aggregate pores within the studied hydro-mechanical states.&#x0D; The current outcomes provide multi-scale insights into the gas transport behaviour of partially saturated compacted GB and emphasise its microstructural response to gas transport under different hydro-mechanical states. The values of Ka.eff measured in the tested GB are higher than those obtained in powder bentonites but comparable to those of sand/bentonite mixtures at an equivalent porosity [5, 6]. The reason is the GB material presents the granular-type microstructure, with many interconnected inter-granular/aggregate pores, even at high Sr. Once the progressive saturation increases Sr to a value close to 1, Ka.eff will sharply drop, attributed to the significant microstructural modification [7]. Therefore, the initial microstructure (before gas injection) of compacted GB plays a critical role in the gas transport behaviour. This microstructural effect was also confirmed in previous investigations of other soil types [8]. Furthermore, the present work underlines the microstructure of compacted GB is modified during gas transport, dependent on hydro-mechanical states, which can further affect the gas transport behaviour.&#x0D;

A multiscale investigation into the role of collagen-hyaluronan interface shear on the mechanical behaviour of collagen fibers in annulus fibrosus – Molecular dynamics-cohesive finite element-based study

Multi-directional deformation exhibited by annulus fibrosus (AF) is contributed by chemo-mechanical interactions among its biomolecular constituents’ collagen type I (COL-I), collagen type II (COL-II), proteoglycans (aggrecan and hyaluronan) and water. However, the nature and role of such interactions on AF mechanics are unclear. This work employs a molecular dynamics-cohesive finite element-based multiscale approach to investigate role of COL-I–COL-II interchanging distribution and water concentration (WC) variations from outer annulus (OA) to inner annulus (IA) on collagen-hyaluronan (COL-HYL) interface shear, and the mechanisms by which interface shear impacts fibril sliding during collagen fiber deformation. At first, COL-HYL interface atomistic models are constructed by interchanging COL-I with COL-II and increasing COL-II and WC from 0 to 75%, and 65%–75% respectively. Thereafter, a multiscale approach is employed to develop representative volume elements (RVEs) of collagen fibers by incorporating COL-HYL shear as traction-separation behaviour at fibril-hyaluronan contact. Results show that increasing COL-II and WC increases interface stiffness from 0.6 GPa/nm to 1.2 GPa/nm and reduces interface strength from 155 MPa to 58 MPa from OA to IA, contributed by local hydration alterations. A stiffer and weaker interface enhances fibril sliding with increased straining at the contact - thereby contributing to reduction in modulus from 298 MPa to 198 MPa from OA to IA. Such reduction further contributes to softer mechanical response towards IA, as reported by earlier studies. Presented multiscale analysis provides deeper understanding of hierarchical structure-mechanics relationships in AF and can further aid in developing better substitutes for AF repair.

Multiscale numerical investigation of ratchet growth damage effects in PBX 9502

AbstractThis paper presents results of numerical experiments conducted on the high explosive PBX 9502 to investigate how recently observed grain‐scale damage mechanisms of ratchet growth [1] affect uniaxial compression measurements. Simulations are multiscale in the sense of directly resolving grains, pores, cracks, and grain‐interfaces based upon scanning electron microscope (SEM) images of damaged and undamaged samples. The combined finite‐discrete element method (FDEM) is utilized to resolve both grain‐scale microfracture and elastoplastic deformation of solid grains. Pristine (undamaged) and damaged microstructures are compared in simulation of unconfined compression tests of the same material from the literature. The simulation results show the observed microscale mechanisms of damage, specifically microfracture predominantly around and sometimes through grains and crack‐associated pore growth, can well‐explain the effective degradation of strength and stiffness observed in the laboratory measurements.

Performance evaluation and multiscale investigation of deodorant on mechanism of rubber modified asphalt

Asphalt fume emission caused by high-temperature is large during the production and construction of rubber modified asphalt, and the toxic and odor gas contained seriously pollutes the environment. This paper prepared rubber modified asphalt (RMA) and deodorant rubber modified asphalt (DRMA) and evaluated the impact of deodorants on the environmental and physical properties. Modern testing techniques, such as gel permeation chromatography, are used to explore the microscopic morphology of RMA, DRMA, and crumb rubber extracted from RMA and DRMA, so as to reveal the mechanism of deodorant in asphalt. Meanwhile, the effect of deodorant was monitored from macro scales by applying electrochemical sensing technology. The results show inhibiting the degradation of rubber in asphalt is the main mechanism of deodorant. Deodorant can not only promote the swelling of rubber in asphalt and improve the stability of sulfur elements, but also capture the odor particles in asphalt fume, reduce the concentration of polluting organic and H2S, realize the application of rubber modified asphalt environmentally-friendly, and promote the recycling of waste tires and the sustainability of pavements for pollution and carbon reduction.

Construction of a new n-body potential and multi-scale investigations of the direct alloying behaviors for immiscible W/Cu system

Achieving direct alloying at the tungsten/copper (W/Cu) interface is crucial for the fabrication of laminar metal matrix composite (LMMC) plasma-facing components (PFCs) of fusion reactors based on immiscible W/Cu systems. Our previous work has accomplished direct alloying between immiscible W and Cu, forming a diffusion layer with a thickness of approximately 22–32 nm at the interface. The performance of the interface directly affects the lifetime and reliability of W/Cu LMMC. Multi-scale calculations are designed since some interface properties cannot be directly measured or observed experimentally in real-time and in situ. Firstly, a new potential is constructed to overcome the limitations that the existing W/Cu potential cannot accurately describe the W/Cu alloying process. Secondly, molecular dynamics (MD) simulations use the new potential to study interfacial properties and calculate the diffusion depth at the W/Cu interface. Lastly, combining MD, FEM, and image visualization techniques, a multi-scale method of the crack propagation rate at the W/Cu interface is used to predict the thermal fatigue life of W/Cu LMMC PFCs prepared by nano-active structure-induced alloying. Our simulation results agree with experimental values and literature results, demonstrating the reliability of the new W/Cu potential and the accuracy of our designed multi-scale method. Directly alloyed W/Cu LMMCs have the potential to be utilized in fusion reactors.

Efficient multiscale investigation of mechanical behavior in Nb3Sn superconducting accelerator magnet based on self-consistent clustering analysis

The High Luminosity Large Hadron Collider (HL-LHC) is one of the large-scale projects currently being developed at the European Organization for Nuclear Research (CERN). Many Nb3Sn superconducting magnets are employed in this project, which exhibit complicated multiscale characteristics. The mechanical behaviors of magnets, which are directly related to the safety and stability of the overall structure, are affected by the electromagnetic–mechanical-thermal loading in actual service conditions. However, detailed modeling of magnets requires significant computing resources. A reduced-order method named self-consistent clustering analysis (SCA) has been proposed recently to reduce the cost. We have combined the SCA and finite element method (FEM) as an efficient multiscale framework, which is utilized to analyze the mechanical behaviors of accelerator magnets. Firstly, the computation results by presented framework are compared with direct numerical simulation (DNS) and existed experimental data to validate the accuracy and efficiency. Then, the FEM-SCA2 framework is utilized to study the mechanical behaviors of MQXFS accelerator magnet model under assembly, cool-down and excitation steps. The influences of material parameters, friction coefficient and stiffness degradation are also discussed. This paper provides an efficient multiscale analysis framework for investigating mechanical behavior in Nb3Sn accelerator magnet, which could be employed to study other magnets.

Stabilising compressed earth materials with untreated and thermally treated recycled concrete: A multi-scale investigation

This paper presents a novel process to recycle the fine fraction of ground concrete waste as a construction binder. The fine fraction of ground concrete is rich of partly hydrated cementitious products, whose binding capacity is further enhanced by treatment at relatively moderate temperatures. The viability of the recycled binder has been demonstrated through the stabilisation of two earth building materials with kaolinitic and illitic clay fractions, respectively. At the microstructural level, X-ray diffractometry tests, mid-infrared spectroscopy tests and thermogravimetric tests have been performed to investigate the mineralogical composition and chemical bonds of the stabilising phase. At the macrostructural level, unconfined compression tests have been performed to evaluate the influence of stabilisation on the elastic modulus, peak strength and energy at failure. Results show that the addition of untreated recycled concrete to both earth types induces an average increase of 4% in apparent elastic modulus, 52% in compressive strength and 108% in failure energy relative to the unstabilised material. The addition of thermally treated recycled concrete induces an even larger increase of 30% in apparent elastic modulus, 93% in compressive strength and 187% in failure energy relative to the unstabilised earth. This is due to the higher hydration capacity of the thermally treated recycled concrete and the consequent formation of stronger inter-particle bonds. These preliminary results indicate a promising way to recycle concrete waste into earth stabilisers, which would ease difficulties associated to the disposal of demolition waste while, at the same time, improving the sustainability of current building practices.