Skeleton Structure Research Articles

Design and motion control of a tendon-driven continuum robot for aerospace applications

Continuum robots are flexible and compliant. Compared to the case in conventional articulated manipulators, the driving unit can be placed outside the workspace of the robot, so that the motion orientation has a relatively complete linear configuration flow, which can be applied to a special environment with narrow and multiple obstacles such as aerospace. This study presents the development process of a tendon-driven continuum robot (TCR) with a high length-diameter ratio. The skeleton structure which imitates a snake is composed of continuous joints in series. The driving device is operated by using a tendon-driven method, which reduces the complexity of the driving box and control system significantly. The diameter of the robot is designed to be 5 mm, which enables it to work in a narrow and slender space with certain flexibility. Subsequently, a kinematic model of the robot is established. The mode function backbone method is applied to realize TCR trajectory planning. An idea of segmented solving is adopted to achieve trajectory tracking control of the continuum robot. Finally, a prototype of the continuum robot is produced, and the rationality of the robot design and the effectiveness of the motion control method are verified through trajectory simulations and experiments. The robot can perform inspection tasks within a narrow gap of 20 mm with good environmental adaptability.

Polydopamine bridging encapsulated laccase on MOF-based mixed-matrix membrane for selective dye/salt separation

Mixed-matrix membranes (MMMs) exhibit significant potential for dye/salt separation. However, overcoming the “trade-off” between permeability and selectivity, as well as membrane fouling, remains a formidable task. In this work, a biocatalytic membrane was prepared using polydopamine (PDA) as a “bridge” connecting the metal-organic framework (MOF)-based MMM and immobilized laccase. The MOF-based MMM featured an interconnected MOF anchoring on the polyvinylidene fluoride (PVDF) skeleton structure, effectively mitigating the “trade-off” phenomenon and enabling efficient separation of dyes and salts. Enzyme-MOF was in situ grown on the MOF-based MMM via coordination reactions between PDA and metal ion, effectively degrading the adhesion of organic pollutants and fouling, ensuring the long-term stable operation of the membrane. The Lac-MOF@PDA MMM exhibited excellent water permeability of 142.4 L·m−2·h−1, 100 % rejection for dye, and less than 10 % rejection for NaCl. Furthermore, the separation mechanism of Lac-MOF@PDA MMM was systematically investigated, and the results suggested a synergistic combination of rejection, adsorption and catalysis processes. This biocatalytic membrane with multiple sieving and biological catalysis is expected to pave a promising way for efficient wastewater treatment applications.

Insight into hemostatic performance and mechanism of natural mixed-dimensional Attapulgite clay

Clay minerals have attracted wide attention as biomedical materials due to the unique crystal structure, abundant morphology and good biocompatibility. However, the relevant studies on the abundant natural mixed clay deposits were scarcely reported. Herein, the hemostatic performance of natural mixed-dimensional attapulgite clay (MDAPT) composed of one-dimensional attapulgite and multiple two-dimensional clay were systematically investigated based on the structural evolution using oxalic acid for different time. The results of hemostatic evaluation showed that MDAPT leached by oxalic acid with 1 h presented the shortest clotting time (134 ± 12.17 s), a 15.09 % and 41.74 % reduction of relative hemoglobin absorbance at 180 s and 120 s when compared with the control group, respectively, and an increase of 19.45 % of the blood clotting index in vitro, as well as MDAPT obtained the shortest bleeding time (158.5 ± 6.9 s), nearly 66 % and 31 % reduction blood loss as compared to the blank group and the YNBY group in vivo. This improvement was primarily ascribed to the synergistic effect of lamellar non-expandable illite, and nano rod-like attapulgite. Furthermore, the rapid hemostasis of MDAPT was also due to the joint effect of superhydrophobic property toward blood, minimizing blood loss, surface negative charge, metal ions from MDAPT structural skeleton, promoting an average increase of 21 % for platelet activation. The results suggested that MDAPT could be served as a promising efficient inorganic hemostatic materials, which provided a feasible strategy to realize the high-valued utilization of natural mixed clay resources.

A puzzle questions form training for self-supervised skeleton-based action recognition

This paper proposed a novel pretext task to address the skeleton-based video representation for self-supervised action recognition tasks. Instead of exploiting only the whole body, various levels of the skeleton structure (e.g., upper body, lower body, left arm, left leg, right arm, right leg, and torso) are employed to extract essential coarser-grained characteristics. This involves computing statistical representations like motion, orientation, trajectory, and magnitude shift from unlabeled skeleton configurations. Then a learning model is built and trained to yield these statistical representations given the sequence configuration as the input. Our approach is question-driven, where each question acts as a puzzle piece contributing to a deeper understanding of the skeleton joint configuration. It's inspired by the ability of the cognitive system observed in individuals to hypothesize unseen actions. This is accomplished by posing pertinent questions and envisioning plausible scenarios to recognize the actions taking place. The answers to these devised questions are derived from the statistical representation of skeleton configurations. To this end, we made 44 questions designed to encompass the broadest overview to the finest detail. Our experiments on the NTU RGB-D, NW-UCLA, and PKU-MMD datasets demonstrate outstanding results in action recognition, proving the superiority of our approach in learning discriminative characteristics.

Novel atmospheric pressure drying method for silica-based aerogel insulation: Inspired with the adult process of damselflies

The high production cost and extremely weak mechanical properties of SiO2 aerogels have been two major challenges hindering its widespread application. Atmospheric pressure drying (APD) has always been regarded as the optimal process to reduce costs. However, traditional APD is cumbersome, still uses a large amount of expensive raw materials, and is extremely immature. In this study, a novel APD was developed, inspired by the wing changes during adult damselfly process. Inorganic silica source/water was used as the raw material, and CO2 was used instead of low surface tension solvent to stabilize the aerogel skeleton structure in situ, and ultimately aerogel material was obtained. The thermal conductivity of pure aerogels was as low as 0.0264 W/(m·K), the porosity reached 94.7 %, and the preparation cycle was only 28.5 h. The thermal stability of the skeleton structure and the chemical stability of surface were investigated and showed the hydrophobicity to withstand temperatures up to 400 °C. Aerogel composites feature low thermal conductivity of 0.0283 W/(m·K), and prominent thermal insulation properties over a wide temperature range of 50–300 °C. For traditional APD, this method shortens preparation cycle by 1–6 times. Compared with the commercial aerogel, the cost is reduced by 38.2 %, and the process is simple and environmentally friendly under the premise of ensuring excellent performance.

Unified chemical synthesis of cephalotaxus diterpenoids: A biosynthetic reversed strategy

In this work, we present the details of the first unified chemical synthesis of cephalotaxus diterpenoids with three distinct carbon skeleton structures. Drawing on our previous synthesis of cephalotane-type C18 dinorditerpenoid and inspired by the proposed biosynthetic synthesis pathway, we formulated a biosynthetic reversed chemical synthetic strategy. This strategy facilitated the conversion of C18 dinorditerpenoid into troponoid-type C19 norditerpenoid and intact cephalotane-type C20 diterpenoid through pivotal one-carbon introduction and ring expansion reactions. In the synthesis of troponoid-type C19 norditerpenoid, we utilized TMSCHN2 as one-carbon unit and meticulously examined the selective regulatory effect of halogen substituents in ring expansion and rearrangement reactions. This endeavor culminated in the successful synthesis of natural product molecules within this subclass, notably including cephinoid H and fortalpinoid C, marking the first chemical total synthesis in this line of research. In the investigation of intact cephalotane-type C20 diterpenoid synthesis, while adhering to the overall synthesis strategy, we initially pursued a ring expansion before carbon introduction approach, which proved unsuccessful. Subsequently, we explored a synthetic route of introducing carbon first and then expanding the ring, leading to a successful outcome and resulting in the first chemical total synthesis of the representative molecule cephanolide E within this subclass. Various challenges such as establishing crucial quaternary carbon stereocenters, selecting appropriate one-carbon units, and controlling ring expansion reactions were effectively addressed throughout this process. Moreover, enantioselective synthesis of natural products within this family was achieved through the development of asymmetric Michael reactions.

Lightweight polyimide composite foams with anisotropic hierarchical pore structure for enhanced mechanical, flame retardancy and thermal insulation purposes

In this study, lightweight polyimide foam (PIF) with anisotropic pore structure were fabricated by adopting microwave-assisted foaming technique. Afterward, lightweight PIF/PI aerogel/silica aerogel (PIF/PIA/SiA) composite foams with anisotropic hierarchical pore structures was prepared by impregnation and directional freeze-drying method. The directional growth of foam pores and ice crystals endowed PIF/PIA/SiA composite foams with anisotropic skeleton structures and hierarchical porous filling structures, leading to anisotropic mechanical and thermal insulation performances. PIF/PIA/SiA composite foams presented mechanical robustness in vertical direction and mechanical flexibility in horizontal direction due to its unique pore structure. In addition, PIF/PIA/SiA composite foams showed outstanding thermal stability and flame retardancy, suggesting a promising application in the field of high temperature fire protection. The PIF/PIA/SiA composite foams exhibited superior thermal insulation performance with thermal conductivities ranging from 0.0253 to 0.0523 W/(m·K) between 25 and 300 °C. Therefore, a facile strategy was developed to fabricate PIF-based composite foams for mechanical, flame retardancy and thermal insulation applications in high-end engineering fields.

Effect of pre-heat treatment and carbonization temperature on comprehensive properties of melamine-derived carbon foam

Carbon foams (CFs), which can be manufactured from melamine foam (MF) via direct carbonization, are promising spacecraft thermal insulation material due to their excellent performance of sound absorption, low density, high porosity and heat resistance. Carbonization temperature, heating rate and carbonization time are three key elements during the melamine carbon foam process. As an improvement, this study simultaneously researches the impacts of pre-heat treatment on the microstructure, structure parameter, mechanical properties and heat-shielding performance of the melamine-derived carbon foam (MDCF), aiming to explore the best process of MDCF production. The results showed that the cross-linking degree and defects of MF samples were directly improved by pre-heat treatment. Additionally, all MDCF samples retained the three-dimensional mesh open-cell skeleton structure. The MDCF samples obtained by carbonization at 900 °C had the smallest average pore size structure, which performed the compressive stress of 16.8 kPa at 10 % strain and lowest thermal conductivity of 0.0252 W m−1 K−1. To further study the mechanical property and thermal conductivity performance of MDCF samples, the mechanics relationships of the buckling strength and shape variables, as well as thermal conductivity and pore size structure were researched.

Study on the degree of influence of coal chemical structure on its wetting characteristics

The wettability of coal plays a crucial role in determining the effectiveness of mine dust reduction, coal flotation, and coal water slurry preparation. This property is influenced by various factors, including coal structure and liquid properties. To investigate the impact of coal’s chemical properties on its wetting behavior, we employed different experimental to characterize the chemical structures of six types of coal. Utilizing contact angle experiments and gray slope correlation analysis, we determined the correlation between each chemical structure parameter and the wetting characteristics of the coal samples. Our findings revealed that 6#Yangquan anthracite has the lowest wettability and its contact angle is 85.3°. Within the coal’s functional group structure, the CH2 symmetric stretching vibration exhibited the highest correlation (0.944) with coal wetting properties. Regarding the elemental composition of coal, oxygen exhibited a higher correlation with coal-wetting properties (carbonyl oxygen structure, 0.788; phenol hydroxyl and ether oxygen bond, 0.798; carboxyl oxygen structure, 0.734). In the carbon skeleton structure of coal, the protonated aryl carbon exhibited the highest correlation degree of 0.944. These results offer insights into the selection of evaluation indices for assessing the influence of coal wetting characteristics and optimizing the hydrophilic and hydrophobic features of the coal surface.

Effect of wet-dry cycle on triaxial mechanical properties and constitutive models of solid waste cemented backfill

As the environmental requirements of underground mine backfilling processes have been promoted, solid waste cemented backfilling (SWCB) technology is widely exploited in goaf backfilling. Due to the groundwater circulation and geothermal drying effects, the SWCB is often exposed to the cycle period of wetting and drying state. To study the influence of wet-dry state transformation on the mechanical properties of SWCB, a series of triaxial compression tests were carried out on SWCB specimens treated with wet-dry cycle. As the cycle numbers increased, first, mass-loss behavior occurred and then hydration damage gradually accumulated in the SWCB specimen, where the maximum mass loss rate (Rw-d) was 7 %. The triaxial compressive strength (TCS) and elastic modulus of SWCB increased with the increase in confining pressure but decreased with the increase in cycle numbers. In low cycle numbers, the wet-dry cycle treatment did not damage the skeleton structure, and the SWCB specimen could still bear external load after failure. A constitutive model considering residual strength was established to describe the stress state and failure process of SWCB specimens. In high cycle numbers, hydration damage occurred and was widely distributed in the SWCB specimen. A rheology constitutive model was established to reflect the stress-strain relationship and flow failure characteristic. From the scanning electron microscopy (SEM) results after SWCB specimen failure, main cracks and many partial microcracks appeared in the low and high cycle numbers, which verified the applicability for two constitutive models. Aiming at the negative effect of wet-dry cycle on the mechanical properties of SWCB, isolating water source and protecting SWCB were proposed to prevent and control the large deformation of SWCB and surface subsidence induced by rheological behavior.

A New Family of SO42–‐Templated 3d‐4f High‐Nuclearity Clusters: Syntheses, Structures, and Magnetic Properties†

Comprehensive SummaryThe precise syntheses of transition–rare‐earth metal clusters with desired structures remain a great challenge. Herein, by utilizing SO42– anion released by in‐situ decomposition of sodium dodecyl sulfate (SDS) as a template, a series of novel high‐nuclearity 3d‐4f clusters, formulated as [Ni24Pr22(μ3‐OH)31(pida)24(SO4)4(NO3)9(CH3COO)3]·Br4·(NO3)11·16H2O·25CH3OH (1, H2pida = N‐phenyliminodiacetic acid), [Ni24Nd22(μ3‐OH)31(pida)24(SO4)4(NO3)9(CH3COO)3]·Br4·(NO3)11·14H2O·24CH3OH (2) and [Ni24Gd22(μ3‐OH)36(bida)24(SO4)7(NO3)3(CH3COO)3]·(SO4)·Br4·(NO3)4·31H2O·32CH3OH (3, H2bida = N‐benzyliminodiacetic acid), have been successfully isolated. X‐ray crystal structure analyses reveal that all the cationic {Ni24RE22} cores in 1—3 possess a ball‐like structure with C3v symmetry, and can be viewed as consisting of an inner {RE22} core and an outer {Ni24} shell. From 1 and 2 to 3, due to the lanthanide contraction effect, the coordination numbers for rare‐earth metal centers in {RE22} are different, resulting in different number of SO42– and NO3– anions to support and stabilize the skeleton structures. Meanwhile, the magnetic properties of complexes 1—3 were also studied. The result revealed that complexes 1—3 show antiferromagnetic/ferrimagnetic interactions, and 3 exhibits magneto‐caloric effect at ultralow temperatures with a maximum –ΔSm (magnetic entropy change) value of 33.03 J·kg−1·K−1 at 3.0 K and 7 T.

Robust-flexible and highly-thermostable polyimide-silica aerogels with adjustable fiber skeleton structure for efficient aerospace thermal protection

The rapid growth of the aerospace industry presents significant challenges in developing lightweight and flexible thermal protective materials for spacecraft and related equipment. One longstanding challenge has been the preparation of high-thermostable and highly flexible aerogels, which limits their practical application in flexible thermal protection. In this work, through a rational 'chain-sphere' dual-combination structure design, polyimide-silica aerogels with integrated properties of the adjustable aerogel-fiber skeleton structure, robust flexibility and high thermostable have been prepared. By incorporating 2,2-dimethylbenzidine (DMBZ), we achieve a more solid aerogel network. The aerogel membrane retains its original shape without creases or cracks even after undergoing 500 folding and unfolding tests. Additionally, the silicon nanoparticles surrounding the aerogel exhibit superior performance at high temperatures. The unique structure and components of the composite enable it to possess lightweight (0.075–0.11 g/cm−3), low thermal shrinkage (300℃∼6 %), excellent thermostability (95 % weight retention at 474℃∼557℃), and promising thermal insulating performance below 600℃. The integrated performances of the aerogel make it suitable for high-temperature thermal protection applications that require both efficient thermal insulation and robust flexibility.

Exploring an eco-friendly approach to improve soil tensile behavior and cracking resistance

Soil tensile strength is a critical parameter governing the initiation and propagation of tensile cracking. This study proposes an eco-friendly approach to improve the tensile behavior and crack resistance of clayey soils. To validate the feasibility and efficacy of the proposed approach, direct tensile tests were employed to determine the tensile strength of the compacted soil with different W-OH treatment concentrations and water contents. Desiccation tests were also performed to evaluate the effectiveness of W-OH treatment in enhancing soil tensile cracking resistance. During this period, the effects of W-OH treatment concentration and water content on tensile properties, soil suction and microstructure were investigated. The tensile tests reveal that W-OH treatment has a significant impact on the tensile strength and failure mode of the soil, which not only effectively enhances the tensile strength and failure displacement, but also changes the brittle failure behavior into a more ductile quasi-brittle failure behavior. The suction measurements and mercury intrusion porosimetry (MIP) tests show that W-OH treatment can slightly reduce soil suction by affecting skeleton structure and increasing macropores. Combined with the microstructural analysis, it becomes evident that the significant improvement in soil tensile behavior through W-OH treatment is mainly attributed to the W-OH gel's ability to provide additional binding force for bridging and encapsulating the soil particles. Moreover, desiccation tests demonstrate that W-OH treatment can significantly reduce or even inhibit the formation of soil tensile cracking. With the increase of W-OH treatment concentration, the surface crack ratio and total crack length are significantly reduced. This study enhances a fundamental understanding of eco-polymer impacts on soil mechanical properties and provides valuable insight into their potential application for improving soil crack resistance.

Promoting Sustainable Coal Gas Development: Microscopic Seepage Mechanism of Natural Fractured Coal Based on 3D-CT Reconstruction

Green mining is an effective way to achieve sustainable development in the coal industry. Preventing coal and gas outburst dynamic disasters are essential for ensuring sustainable and safe mining. The numerous microscopic pores within the coal serve as the primary storage space for gas, making it critical to explore the structural distribution and seepage characteristics to reveal the disaster mechanism. Under mining stress, gas within the micropores of the coal migrates outward through cracks, with these cracks exerting a significant control effect on gas migration. Therefore, this study focuses on utilizing natural fractured coal bodies as research objects, employing a micro-CT imaging system to conduct scanning tests and digital core technology to reconstruct sample pore and fracture structures in three dimensions, and characterizing the pores, cracks, skeleton structure, and connectivity. A representative elementary volume (REV) containing macro cracks was selected to establish an equivalent model of the pore network, and a seepage simulation analysis was performed using the visualization software. Revealing the seepage characteristics of fractured coal mass from a microscopic perspective. The research results can provide guidance for gas drainage and dynamic disaster early warning in deep coal mines, thus facilitating the sustainable development of coal mining enterprises.

#2474 TPPP3 maintains the stability of foot cytoskeleton architecture

Abstract Background and Aims Podocytes have a unique cytoskeleton architecture, and the disturbance of the skeleton architecture can lead to foot processes fusion and then proteinuria. Actin microfilaments dominate the cytoskeleton of the foot process, and microtubules and intermediate filaments dominate the synapses of the foot cells. The structural destruction of foot process actin is closely related to the injury of podocytes. The microtubule and actin often work together in cellular processes through stable connections. As the core structure of the skeleton network, microtubules play a key role in supporting and maintaining the skeleton network. However, the mechanism of microtubule structure destruction and podocyte injury remains unclear. Method Immunofluorescence and western blot were used to confirm the correlation between actin injury and decreased acetylation of tubulin in podocytes in vitro and in vivo. Single-cell RNA sequencing comprehensively characterized the expression of TPPP3 in human glomeruli. Immunofluorescence, immunohistochemical, western blot were used to determine the expression of TPPP3, α-tubulin, acetylated tubulin, actin microfilaments. Results In the case of podocyte injury, the acetylation level of tubulin decreased (P < 0.05). Reducing tubulin acetylation can lead to microfilaments injury (P < 0.05) and weakened podocyte motility (P < 0.05). TPPP3 was specifically expressed in human glomerular podocytes, and its expression level was significantly decreased after podocyte injury (P < 0.05). Knockdown of TPPP3 leaded to the level of microtubule acetylation decreased (P < 0.05) and microfilaments were damaged (P < 0.05) in podocytes. High acetylation levels of tubulin can partially restore actin microfilament damage caused by TPPP3 reduction in vivo and in vitro (P < 0.05). Conclusion TPPP3 is involved in maintaining the normal morphology and function of podocytes by stabilizing the actin microfilament skeleton structure by regulating the acetylation level of microtubules.

Tailored 2D conjugated polymers for pseudocapacitive proton storage

2D conjugated polymers (2D-CPs) are currently attracting substantial attention as host materials in electrochemical energy storage. They show some intriguing properties, such as high conductivity (by elevating the conjugated degree), adjustable redox activity (by controlling the monomers), and stable skeleton structure (low solubility in electrolytes). Herein, two aza-based 2D-CPs with different conjugation degrees are designed and developed for pseudocapacitive proton storage. The detailed electrochemical analysis shows that the highly conjugated 2D-CP (2D-HCP) demonstrates an inferior performance compared to partially conjugated 2D-CP (2D-PCP), especially in terms of the high-rate performance. Though combining various in-situ/ex-situ spectroscopy analyses and theoretical simulation, the reason behind this performance is revealed and is associated with the different solid-state proton diffusion kinetics in these two 2D-CPs. We believe this new understanding can be leveraged to design and develop more suitable 2D-CPs for electrochemical energy storage.

LMNB1/CDKN1A Signaling Regulates the Cell Cycle and Promotes Hepatocellular Carcinoma Progression.

Hepatocellular carcinoma (HCC) is one of the most aggressive malignancies in the world. Lamin B1 (LMNB1) is a key component of the nuclear skeleton structure. Recent studies have found that LMNB1 is overexpressed in tumor tissues and is associated with the prognosis of patients. However, the underlying mechanism remains unclear in HCC. This study aims to explore the clinical significance and molecular mechanisms of LMNB1 in HCC. The expression level of LMNB1 and its clinical values were analyzed with public databases, and the level of LMNB1 in HCC tissues and adjacent normal tissues was confirmed by qRT-PCR and IHC. Functional assays were conducted to explore the impact of LMNB1 knockdown on cell proliferation both in vivo and in vitro. Additionally, Genes and Genomes enrichment analysis, recovery analysis, and ChIP assays were employed to investigate its underlying molecular mechanisms. Finally, we carried out an analysis of the relationship between LMNB1 and immune cell infiltration in HCC. LMNB1 was found to be overexpressed in HCC and correlated with the pathological stage and unfavorable prognosis. Functional assays demonstrated that LMNB1 promotes HCC proliferation both in vitro and in vivo. Further analysis revealed that LMNB1 promotes the progression of HCC by regulating CDKN1A expression. Furthermore, the infiltration of immune cells in HCC tissues suggests a potential correlation between immune infiltration cell markers and the expression of LMNB1. LMNB1 emerged as a promising therapeutic target and prognostic biomarker for HCC, with its expression showing a correlation with several immune infiltration cell markers.

Discovery of Antibacterial Compounds against Xanthomonas citri subsp. citri from a Marine Fungus Aspergillus terreus SCSIO 41202 and the Mode of Action.

Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a severe citrus disease. Currently, copper-containing pesticides are widely used to manage this disease, posing high risks to the environment and human health. This study reports the discovery of naturally occurring anti-Xcc compounds from a deep-sea fungus, Aspergillus terreus SCSIO 41202, and the possible mode of action. The ethyl acetate extract of A. terreus was subjected to bioassay-guided isolation, resulting in the discovery of eight anti-Xcc compounds (1-8) with minimum inhibitory concentrations (MICs) ranging from 0.078 to 0.625 mg/mL. The chemical structures of these eight metabolites were determined by integrative analysis of various spectroscopic data. Among these compounds, Asperporonin A (1) and Asperporonin B (2) were identified as novel compounds with a very unusual structural skeleton. The electronic circular dichroism was used to determine the absolute configurations of 1 and 2 through quantum chemical calculation. A bioconversion pathway involving pinacol rearrangement was proposed to produce the unusual compounds (1-2). Compound 6 exhibited an excellent anti-Xcc effect with a MIC value of 0.078 mg/mL, which was significantly more potent than the positive control CuSO4 (MIC = 0.3125 mg/mL). Compound 6 inhibited cell growth by disrupting biofilm formation, destroying the cell membrane, and inducing the accumulation of reactive oxygen species. In vivo tests indicated that compound 6 is highly effective in controlling citrus canker disease. These results indicate that compounds 1-8, especially 6, have the potential as lead compounds for the development of new, environmentally friendly, and efficient anti-Xcc pesticides.

Enhancement mechanism of asphalt mixture skeleton structures due to morphological characteristics of steel slag

Uncertainty still exists about the enhancement mechanism of the skeleton structure brought about by the steel slag, and the relationship between skeleton structure of steel slag asphalt mixture and the mechanical properties is still ambiguous. This study quantified the skeleton structure of steel slag asphalt mixture and explored the enhancement mechanism of skeleton structure brought about by the steel slag. The relationship between skeleton parameters and mechanical properties of steel slag asphalt mixture was also established. The results show that recycling steel slag as aggregate improves the skeleton quality of mix. The slag particles are not susceptible to be oriented tending to the horizontal direction. The abundant angularity of steel slag increased the contact number while the rough texture and non-spherical shape of steel slag enhanced the contact length. This project provided new insight and a notable opportunity to advance the comprehension of the skeleton structure of asphalt mixture containing steel slag.

Deterioration micro-mechanism of graded aggregates with different gradations under vibratory compaction using X-CT testing

This study aims to explore the compaction deterioration micro-mechanism of high-speed railway graded aggregate (HRGA) fillers and further improve the compaction quality of HRGA fillers, contributing to improving subgrade service performance. Firstly, based on the vibratory compaction experiments, the compaction deterioration macro-characteristics of HRGA fillers with different gradations were revealed from the mechanical properties (i.e., dynamic stiffness Kd and subgrade reaction modulus K20). Secondly, X-ray Computed Tomography (X-CT) testing was conducted based on the multiple typical compaction stages selected from the Kd curve. The internal microstructure (i.e., particles and voids) characteristics within HRGA fillers with different gradations were measured by high-precision image processing approaches. Finally, the evolution characteristics of Kd, K20, and microstructure were used to reveal the compaction deterioration micro-mechanism of HRGA fillers with different gradations, and further explore the relationship between filler gradation and compaction deterioration. The results indicated that compaction deterioration characteristics of HRGA fillers with different gradations could be characterized by the inflection points of Kd and K20 curves. Besides, during compaction deterioration, particle abrasion crushing and the increase in surface edges and corners of the void reduced the stability of the skeleton structure within HRGA fillers with different gradations, resulting in a gradual decrease of Kd and K20. Furthermore, the relationship between Kd, K20, and microstructure with gradation could be quantitatively characterized by quadratic functions. Hence, based on X-CT measurement, it was feasible to reveal the compaction deterioration mechanism of HRGA fillers from macro- and micro-perspectives. This study contributes to establishing a theoretical framework for revealing the compaction deterioration of high-speed railway subgrade fillers and improving the quality of vibratory compaction for on-site subgrade construction.