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Aiming at the disadvantage that the traditional creep model cannot describe the nonlinear creep acceleration stage (third-order creep stage) of rock. This paper explains the creep process of salt rock from a microscopic perspective based on the Riemann–Liouville type fractional-order calculus operator theory and acoustic emission (AE) theory, and describes the creep process of salt rock with the improved fractional-order derivatives. The results of uniaxial creep damage tests on rock salt specimens under quasi-static loading conditions are given, complete creep damage curves are obtained, and a creep model based on fractional-order derivatives for viscoelastic damage of salt rock is proposed, and finally, the best variable values are fitted to determine the optimum values. The AE characteristic parameter curves were compared with the creep strain curves, and it was found that the AE characteristic curves could predict the time point when the salt rock enters the accelerated creep stage in advance. According to this time point, the model is fitted in sections and compared with the experimental results. The predicted value of the model is in good agreement with the test results, and can better describe the nonlinear accelerated creep stage of salt rock. It is believed that the fractional-order model can simulate the whole process of rock creep well and has good practical application value.Highlights•Established a viscoelastic-plastic damage creep model of rock salt based on fractional derivative.•Based on AE technique, the creep process of rock salt was explained from the microscopic perspective and the damage evolution was obtained.•The AE characteristic curve can predict the time point when the salt rock enters the accelerated creep stage in advance, and the model can be fitted to the segment according to this time point, which can better describe the nonlinear accelerated creep stage of the salt rock.•Segmental fitting can well simulate the whole process of salt rock creep, has good superiority and reliable, which can predict engineering disaster in advance.

The development and extension of microcracks in rocks affect the integrity and stability of rock mass construction. External dynamic loads with different loading rates lead to different dynamic fracture characteristics of rock fractures. In this study, a large-sized PMMA specimen with an arc boundary was proposed. The time at which the crack started and spread was determined using drop hammer impact testing and crack growth meter testing. Subsequently, the microscopic characteristics of the crack fracture surfaces were analyzed using a scanning electron microscope. Finally, the dynamic fracture toughness of the crack tip of the PMMA specimen was calculated using the finite-element method. Both experimental and numerical studies indicated that the arc boundary of the specimen demonstrated effective capabilities for arresting propagating cracks, and as the loading rate increased, the crack velocity also increased, while the crack initiation time decreased. The crack no longer propagated along the original crack surface after the crack arrest. The peak compressive stress along the crack trajectories increased with the loading rate. During the early stages of crack propagation, the highest compressive stress was observed for the 65° specimen. Conversely, during the later stages of the crack propagation, the 125° specimen exhibits the highest compressive stress. The dynamic arrest toughness of the crack is greater than the dynamic initiation and propagation toughness of the crack. As the loading rates increased, the dynamic initiation and propagating toughness of the crack also increased, while the dynamic arrest toughness of the crack changed little with the loading rate.

The Laoheba Phosphate Mine Area in the Sichuan Basin stands as one of China’s primary locations for phosphate extraction, boasting a diverse array of rock types and complex rock layers. In recent years, frequent geological disasters, notably landslides, have occurred in the mining area. The safe extraction of phosphate rock faces significant challenges, necessitating an in-depth exploration of the physical and mechanical properties of the rocks within the mining area. This study employs nuclear magnetic resonance (NMR) and X-ray diffractometer (XRD) testing on six typical rock specimens, contrasting and analyzing their physical traits, thus unveiling the impact of rock composition and microstructure on their mechanical properties. The MTS815 Flex Test GT rock mechanics testing system was employed to perform uniaxial compression, triaxial compression, Brazilian disk splitting, and triaxial penetration tests. The study systematically examined the mechanical characteristics of typical rocks in the mining area. The correctness of the experiments was mutually validated by four types of tests. Finally, an analysis of rock failure modes and patterns was conducted. Research suggests that phosphate ore exhibits the highest porosity and permeability. Phosphate ore exhibits significant development of original joints and cracks internally, along with numerous defects, leading to its minimal compressive and tensile strength. Phosphate ore is typically situated in regions of weakened rock mass strength. Real-time monitoring of confining pressure is essential during mining operations to prevent the collapse of surrounding rock formations. The findings of this study offer theoretical backing for secure mining operations in the Laoheba Mining Area of the Sichuan Basin while also furnishing fundamental physical and mechanical parameters for regional geomechanical analysis.

In patients with HIV-1 infection, the virus is recognized by innate immune sensors that trigger the production of type I interferons (IFNs), which are well-known cytokines that exert broad antiviral effects by inducing the expression of antiviral genes. By comparing the gene expression profiles of untreated patients and healthy donors, we systematically identified OTOF as a new antiviral gene induced by IFN-α in primary macrophages and dendritic cells (DCs). In humans, HIV-1 infection induces innate immune responses mediated mainly by type I interferon (IFN). Type I IFN restricts HIV-1 replication by upregulating the expression of IFN-stimulated genes with diverse anti-HIV properties. In this study, we report that the cell membrane protein otoferlin (OTOF) acts as a type I IFN-induced effector, inhibiting HIV-1 entry in myeloid lineage macrophages and dendritic cells (DCs). OTOF is significantly induced by type I IFN in macrophages and DCs but not in CD4 + T lymphocytes. Silencing OTOF abrogates the IFN-mediated suppression of HIV-1 infection in macrophages and DCs. Moreover, OTOF overexpression exhibits anti-HIV activity in macrophages and CD4 + T cells. Further evidence reveals that OTOF inhibits HIV-1 entry into target cells at the cell membrane. Collectively, OTOF is a downstream molecule induced by type I IFN to inhibit HIV-1 entry in macrophages; it is a new potential agent for the treatment of HIV infection. IMPORTANCE In patients with HIV-1 infection, the virus is recognized by innate immune sensors that trigger the production of type I interferons (IFNs), which are well-known cytokines that exert broad antiviral effects by inducing the expression of antiviral genes. By comparing the gene expression profiles of untreated patients and healthy donors, we systematically identified OTOF as a new antiviral gene induced by IFN-α in primary macrophages and dendritic cells (DCs). Additionally, silencing OTOF alleviates IFN-α-induced resistance to HIV-1 infection in both myeloid cell lineage macrophages and DCs. In contrast, OTOF overexpression potently restricts HIV-1 transmission in macrophages. We further explored the molecular mechanism through which OTOF inhibits the HIV-1 virion across the cell membrane. Overall, OTOF is a newly identified type I IFN-induced antiviral factor that inhibits the transmembrane activity of HIV-1 in myeloid cells.

The double-disc straight-groove (DDSG) grinding method is a new precision machining method for the rolling surface of bearing cylindrical rollers by using a flat grinding disc and a straight-groove grinding disc as machining tools. The machining principle of bearing cylindrical rollers based on the DDSG grinding method is experimentally investigated in this study. A circulating grinding platform has been constructed. The grinding test of the cylindrical rollers was performed with W40 white corundum abrasive. Under the experimental conditions of the grinding disc rotation speed of 7.5 rpm, the machining load of 110 N, and the eccentricity of the straight groove of 6 mm, 2000 cylindrical rollers (AISI 52100) were synchronously ground by the DDSG grinding method. The average diameter, surface roughness, and roundness of the ground rollers were investigated. Experimental results show that the material removal rate of the rollers is uniform. After 270 grinding cycles, the average diameter decreased from 5.99082 to 5.94135 mm, with an average material removal rate of 0.183 microns per cycle. The average roundness of ground cylinders reduced from 9.64 to 2.78 μm. The diameter variation decreased significantly from 14.5 to 6.0 μm. The average roughness reduced from 0.258 to 0.137 μm, and the fluctuation range of the roughness decreased from 0.143 to 0.033 μm. Experimental results demonstrate that the DDSG grinding method can improve the bearing cylindrical rollers’ dimensional consistency, roundness, and surface quality.

Background Invasive pulmonary fungal infections (IPFIs) pose significant diagnostic challenges, particularly in immunocompromised patients. Accurate and timely diagnosis is crucial to improve outcomes. While metagenomic next-generation sequencing (mNGS) is widely utilized, it is expensive and affected by host DNA interference. Targeted next-generation sequencing (tNGS) offers a cost-effective and efficient alternative for fungal pathogen detection. Methods We developed the Fi-tNGS assay, a targeted next-generation sequencing method, specifically designed to detect 64 fungal species. Analytical performance was validated by assessing its limit of detection (LoD), reproducibility, and resistance to host DNA interference. Subsequently, a prospective clinical study was conducted, enrolling 104 patients with suspected IPFIs. Clinical diagnostic performance was evaluated by comparing Fi-tNGS, mNGS, and conventional microbial culture against a comprehensive diagnostic standard. Results Fi-tNGS detected 109 pathogens, compared to 110 for mNGS and 77 for culture. The sensitivity and specificity of tNGS were 89.7% and 94.2%, respectively, outperforming culture (65.8% sensitivity, 100% specificity). Combining culture with tNGS or mNGS significantly improved sensitivity to 94.8% and 94.0%, respectively. These findings demonstrate the added diagnostic value of NGS methods for IPFIs. Conclusions tNGS provides accurate and efficient fungal pathogen detection, with sensitivity comparable to mNGS and superior to culture. Its cost-effectiveness and shorter turnaround time highlight its potential as a practical tool for the rapid and precise diagnosis of IPFIs in clinical settings.

Geothermal power is being regarded as depending on techniques derived from hydrocarbon production in worldwide current strategy. However, it has artificially been developed far less than its natural potentials due to technical restrictions. This paper introduces the Enhanced Geothermal System based on Excavation (EGS-E), which is an innovative scheme of geothermal energy extraction. Then, based on cohesion-weakening-friction-strengthening model (CWFS) and literature investigation of granite test at high temperature, the initiation, propagation of excavation damaged zones (EDZs) under unloading and the EDZs scale in EGS-E closed to hydrostatic pressure state is studied. Finally, we have a discussion about the further evolution of surrounding rock stress and EDZs during ventilation is studied by thermal-mechanical coupling. The results show that the influence of high temperature damage on the mechanical parameters of granite should be considered; Lateral pressure coefficient affects the fracture morphology and scale of tunnel surrounding rock, and EDZs area is larger when the lateral pressure coefficient is 1.0 or 1.2; Ventilation of high temperature and high in-situ stress tunnel have a significant effect on the EDZs scale; Additional tensile stress is generated in the shallow of tunnel surrounding rock, and the compressive stress concentration transfers to the deep. EDZs experiences three expansion stages of slow, rapid and deceleration with cooling time, and the thermal insulation layer prolongs the slow growth stage.

SARS-CoV-2 evolution in persistent infection, which may induce long COVID-19, is predominantly manifested in immunocompromised hosts, who act as the viral reservoirs for future outbreaks. Therefore, understanding the evolutionary mechanisms of novel variants that can evade preexisting immune responses is critical to guide public health measures and develop vaccines tailored for vulnerable populations. We used next-generation sequencing and phylogenetic methods to delineate the evolutionary and mutational profiles of SARS-CoV-2 variants using serial oropharyngeal swab samples from 5 individuals with persistent infections. Our results revealed that the intra-host evolutionary patterns of different variants varied significantly, and the evolutionary rate in 3 immunocompromised hosts was 20 times higher than in 2 other patients. These variations likely stem from differences in immune suppression status, the strength of preexisting immune responses, and the extent of error-generating mutations. There were 15 intra-host single-nucleotide variants (iSNVs) in the spike gene among at least two variants, suggesting convergent evolution. Although most new iSNVs do not reach fixation, some of them belong to lineage-defined mutations in variants of concern (VOCs) and recent variants of interest (VOIs). The observations indicate that persistent infections serve as sources for novel, potentially harmful variants, whereas the viral evolutionary dynamics are impacted by virological, immunological, and genetic factors. Thus, there is an urgent need for individualized monitoring and management of immunocompromised hosts to prevent outbreaks caused by the viral seeds generated from them and to study viral factors associated with post-acute COVID-19 sequelae.

To study the characteristics of rock fracture in deep underground under blast loads, some numerical models were established in AUTODYN code. Weibull distribution was used to characterize the inhomogeneity of rock, and a linear equation of state was applied to describe the relation of pressure and volume of granite elements. A new stress initialization method based on explicit dynamic calculation was developed to get an accurate stress distribution near the borehole. Two types of in situ stress conditions were considered. The effect of heterogeneous characteristics of material on blast-induced granite fracture was investigated. The difference between 2D models and 3D models was discussed. Based on the numerical results, it can be concluded that the increase of the magnitude of initial pressure can change the mechanism of shear failure near the borehole and suppress radial cracks propagation. When initial lateral pressure is invariable, with initial vertical pressure rising, radial cracks along the acting direction of vertical pressure will be promoted, and radial cracks in other directions will be prevented. Heterogeneous characteristics of material have an obvious influence on the shear failure zones around the borehole.

Water contents in rocks vary with local hydrogeological conditions and may significantly affect the stability of rock mass engineering. For example, geological disasters are usually occurring after rainfall, such as landslides, karst collapse. In this paper, drop plate impact (DPI) tests were performed on single cleavage triangle (SCT) red sandstone specimens with dry, natural, absorbed and saturated conditions, which has a great guiding significance for deep understanding of dynamic failure of rock materials. The crack initiation time was obtained by crack propagation gauges (CPGs), and crack propagation speeds were computed by fractal method. The dynamic stress intensity factors (DSIFs) were calculated by ABAQUS code. Meanwhile, the microstructure of the fracture surface was scanned and was analyzed. The results show that the average critical DSIFs and crack propagation speeds vary with water content significantly. For the dry sandstone, the average critical DSIF is the highest, whereas the average crack speed is the lowest. For the natural sandstone, the average critical DSIF is the lowest, whereas the average crack speed is the highest. For the water-bearing sandstone, i.e., the natural, absorbed and saturated sandstone, the average critical DSIF increases with water content, whereas the crack speed decreases with increasing water content.