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The construction of traditional underground utility tunnels faces prominent challenges, including high costs, long construction cycles, and limited workspace. Although 3D printing technology offers an effective solution to these issues, its practical application is largely constrained by key performance factors such as the printability, early strength, and interlayer bonding of concrete materials. This study aims to develop a 3D-printable concrete material specifically suited for the construction of underground utility tunnels. Through collaborative optimization of parameters such as the water–binder ratio, additives, and fiber content using single-factor and orthogonal tests, the optimal mix proportion was determined: a water–binder ratio of 0.30, a 10% dosage of rapid-hardening sulphoaluminate cement (R·SAC), a sand-to-binder ratio of 1.0, 20% mineral admixtures (15% fly ash + 5% silica fume), and a 1.0% volume fraction of polypropylene fibers. The results indicate that the fresh paste achieved a flowability of 192 mm, demonstrating excellent printability. Specimens printed using a sawtooth toolpath reached a 3-day compressive strength of 37.8 MPa, with 28-day compressive and flexural strengths increasing to 56.3 MPa and 7.8 MPa, respectively, and an interlayer bond strength of 3.5 MPa. Crucially, the compressive and flexural anisotropy coefficients were as low as 0.023 and 0.066, respectively, showing a preliminary exploratory trend superior to levels reported in some literature and suggesting the potential of printed components to improve structural performance consistency. This material system not only meets the requirements of 3D printing for early strength and workability but also, by introducing R·SAC to form a low-alkalinity binder system, provides a potential pathway for enhancing long-term durability in corrosive environments. This study offers a reliable theoretical and experimental basis for the application of 3D printing technology in underground engineering. Long-term durability will remain a primary focus of subsequent research.

To overcome the limitations imposed by the anisotropy and heterogeneity of natural loess, this study establishes a novel quantitative macro–micro correlation framework for investigating the deformation mechanisms of artificial structural loess (ASL). ASL samples were prepared by mixing remolded loess with cement (0–4%) and NaCl (0–16%), followed by static compaction (95% degree) and 28-day curing (20 ± 2 °C, >90% RH) to replicate the structural properties of natural loess under controlled conditions. An integrated experimental methodology was employed, incorporating consolidation/collapsibility tests, particle size analysis, X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). A three-dimensional nonlinear model was proposed. The findings show that intergranular cementation, particle size distribution, and pore architecture are the main factors influencing loess’s compressibility and collapsibility. A critical transition from medium to low compressibility was observed at cement content ≥1% and moisture content ≤16%. A strong correlation (Pearson |r| > 0.96) was identified between the mesopore volume ratio and the collapsibility coefficient. The innovation of this study lies in the establishment of a three-dimensional nonlinear model that quantitatively correlates key microstructural parameters (fractal dimension value (D), clay mineral ratio (C), and large and medium porosity (n)) with macroscopic deformation indicators (porosity ratio (e) and collapsibility coefficient (δs)). The measured data and the model’s output agree quite well, with a determination coefficient (R2) of 0.893 for porosity and 0.746 for collapsibility, verifying the reliability of the model. This study provides a novel quantitative tool for loess deformation prediction, offering significant value for engineering settlement assessment in controlled cementation and moisture conditions, though its application to natural loess requires further validation.

To investigate the failure characteristics of 3D-printed concrete utility tunnels under loading, a 1:25 scaled model was designed using similarity theory. Vertical loading tests were conducted under soil lateral confinement, and the load–displacement curves, discrete-point strain responses, and crack evolution process were obtained. The test results show that the structure successfully undergoes an elastic stage, a crack development stage, and a plastic failure stage. The incorporated polypropylene fibers exert a bridging effect, enabling the component to retain a certain load-bearing capacity after cracking. Crack distribution was highly heterogeneous: cracks were densest on the top slab, widest on the side walls, and multi-directional on the inner wall. A clear correspondence exists between strain response and crack distribution, with tensile strain zones highly coinciding with crack opening zones. The failure mode generally agrees with the “top slab compression–side wall tensile cracking” characteristic of traditional closed-frame structures. However, the wall thickness deviations induced by the 3D printing process are amplified during internal force redistribution in the statically indeterminate structure, resulting in markedly asymmetric failure of the left and right side walls.

The quality of the sand core directly affects the quality of the casting during the casting process. The establishment of an information link between the sand core and the casting can realize the traceability of sand core production and process data in the casting production. The technology can be used when casting defects related to the sand core occur and quickly respond to the causes and optimize the manufacturing process of the sand core making process. This article describes the necessity of establishing a traceability process for sand core making information and introduces a traceability process of sand core information in casting production to ensure that each sand core has its own production process information, which is for product quality management and process optimization. It provides information supervision and promotes the development of intelligent casting manufacturing technology and management technology.

This paper reports petrological and geochemical features and zircon U-Pb age of plagiogranite from the Hongliugou-Lapeiquan ophiolitic melange belt in the northern Altyn Tagh. The zircon U-Pb dating results yield a mean ^238U/^206pb age of 512.1 ± 1.5 Ma, representing an emplacement time of the plagiogranites in the Middle Cambrian. The plagiogranites are interpreted to have derived from anatexis of hydrated amphibolites by ductile shearing during transports of the oceanic crust. Thus it is believed that the formation age of such type of plagiogranite was coeval to or slightly younger than the spreading of the Hongliugou-Lapeiquan limited oceanic basin. The new results from the plagiogranites suggest that an oceanic basin existed in the northern Altyn area during the Middle Cambrian.

The landslide which located in the northwest of the transformer substation was studied and the evaluation of the stability was contained.Through analyzing the regional geological conditions and landslide engineering conditions, summary of the reason of the landslide was made. Based on two-dimensional rigid body limit equilibrium theory, residual thrust method was used in calculation. Through the researching of the landslide, some factors that play important role were found. According to the investigation report, select the main slip profile as the basis for calculating. Combining with soil C&φ, the value of the inversion parameters can be got. Calculation process contained two engineering conditions. In the natural condition, the landslide is stable, and in the rainstorm condition, the landslide is not stable.

DDA(Discontinuous Deformation Analysis) was used to study the mechanical characteristics of coarse granular material (CGM). The numerical simulation model was found consulting the two Dimensional test of CGM,and the stress-strain curves obtained by the numerical simulation were basically in agreement with the results of laboratory test. It indicates that the numerical simulation is suitable for the mechanical characteristic research of CGM. In addition,the distribution statistic of several fabric elements about interaction between particles was also presented. Some relation between the stress-strain and fabric element change are found after analysis.

Background Mechanisms linking sarcopenia and cognitive function among middle-aged and older adults in China remain unclear. We examined whether social participation and instrumental activities of daily living (IADL) disability mediate the longitudinal association between sarcopenia status and cognitive function. Methods We included 7,114 participants from the China Health and Retirement Longitudinal Study (CHARLS) who were followed for 7 years. Associations between sarcopenia status (non-sarcopenia, possible sarcopenia, sarcopenia) and cognitive function were examined using multivariable linear regression. Parallel mediation and moderated mediation effects were tested using nonparametric bootstrapping. Results After covariate adjustment, sarcopenia was associated with poorer cognitive function compared with non-sarcopenia (B = -0.784, P  < 0.001). For possible sarcopenia, IADL disability showed an indirect-only mediating effect (B = -0.055, 95% CI: -0.091 to -0.024). For sarcopenia, both IADL disability (B = -0.133, 95% CI: -0.219 to -0.061) and social participation (B = -0.047, 95% CI: -0.115 to -0.002) partially mediated the association, accounting for 14.94% and 5.28% of the total effect, respectively. Conclusion In this observational cohort, IADL disability showed an indirect-only mediating effect for possible sarcopenia, while IADL disability and social participation partially mediated the association for sarcopenia. These findings suggest potentially relevant pathways and may inform stage-tailored strategies. Further studies are needed to confirm the proposed pathways and assess causality.

Cerebral aneurysm growth is characterized by vessel wall frailness, although the underlying cellular mechanisms are unclear. Here, we examined the relationship between inflammatory smooth muscle cells (SMCs) and endothelial cells (ECs) in cerebral aneurysms, including the mechanisms underlying inflammatory SMC-induced changes in ECs. Five saccular cerebral aneurysms were collected and five temporal artery samples were used as controls. Cells and cytokines were detected by immunohistochemistry and TUNEL (transferase dUTP nick end labeling) assays performed to evaluate apoptosis. Human umbilical vein endothelial cells (HUVECs) were seeded on collagen I, IV, and VI-coated plates for cell adhesion assays and inflammatory SMCs (iSMCs) were established by culture in flexible silicone chambers subjected to cyclic mechanical stretch. HUVECs were cultured in iSMC-conditioned medium, followed by evaluation of their viability, apoptosis, and function, and determination of VEGF (vascular endothelial growth factor) -A and integrin levels by western blotting. Aneurysm tissue contained fewer SMCs and lacked ECs. In aneurysm walls, more matrix metalloproteinase (MMP) -1, MMP-3, and apoptotic cells were detected, accompanied by decreased collagen IV and VI levels. Cell adhesion assays revealed that more HUVECs were attached in collagen IV and VI-coated plates compared with controls. iSMC-conditioned medium significantly reduced HUVEC viability and apoptosis showed an increased trend; however, the difference was not significant. iSMC medium also reduced tube formation and migration of HUVECs. Moreover, iSMC medium reduced HUVEC expression of VEGF-A, integrin α1, integrin α2, and integrin β. Our data demonstrate a lack of SMCs and ECs in aneurysm walls, accompanied by elevated MMP and decreased collagen levels. In vitro assays showed that iSMCs induced reduction in EC adhesion, and caused EC dysfunction. Understanding of the relationships among SMC, EC, and collagens during aneurysm progression provides an additional therapeutic option for prevention of cerebral aneurysm progression.

Background The regulation of vascular smooth muscle cell (VSMC) phenotype plays an important role in intracranial aneurysm (IA) formation and progression. However, the underlying mechanism remains unclear. Metformin is a 5′ AMP-activated protein kinase (AMPK) agonist that has a protective effect on vasculature. The present study investigated whether metformin modulates VSMC phenotype switching via the AMPK/acetyl-CoA carboxylase (ACC) pathway during IA pathogenesis. Methods Adult male Sprague-Dawley rats ( n = 80) were used to establish an elastase-induced IA model. The effects of metformin on AMPK activation and VSMC phenotype modulation were examined. We also established a platelet-derived growth factor (PDGF)-BB-induced VSMC model and analyzed changes in phenotype including proliferation, migration, and apoptosis as well as AMPK/ACC axis activation under different doses of metformin, AMPK antagonist, ACC antagonist, and their combinations. Results Metformin decreased the incidence and rupture rate of IA in the rat model and induced a switch in VSMC phenotype from contractile to synthetic through activation of the AMPK/ACC pathway, as evidenced by upregulation of VSMC-specific genes and decreased levels of pro-inflammatory cytokines. AMPK/ACC axis activation inhibited the proliferation, migration, and apoptosis of VSMCs, in which phenotypic switching was induced by PDGF-BB. Conclusions Metformin protects against IA formation and rupture by inhibiting VSMC phenotype switching and proliferation, migration, and apoptosis. Thus, metformin has therapeutic potential for the prevention of IA.