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Background Cellulose and hemicellulose are the two largest components in lignocellulosic biomass. Enzymes with activities towards cellulose and xylan have attracted great interest in the bioconversion of lignocellulosic biomass, since they have potential in improving the hydrolytic performance and reducing the enzyme costs. Exploring glycoside hydrolases (GHs) with good thermostability and activities on xylan and cellulose would be beneficial to the industrial production of biofuels and bio-based chemicals. Results A novel GH10 enzyme (XynA) identified from a xylanolytic strain Bacillus sp. KW1 was cloned and expressed. Its optimal pH and temperature were determined to be pH 6.0 and 65 °C. Stability analyses revealed that XynA was stable over a broad pH range (pH 6.0–11.0) after being incubated at 25 °C for 24 h. Moreover, XynA retained over 95% activity after heat treatment at 60 °C for 60 h, and its half-lives at 65 °C and 70 °C were about 12 h and 1.5 h, respectively. More importantly, in terms of substrate specificity, XynA exhibits hydrolytic activities towards xylans, microcrystalline cellulose (filter paper and Avicel), carboxymethyl cellulose (CMC), cellobiose, p-nitrophenyl-β-d-cellobioside (pNPC), and p-nitrophenyl-β-d-glucopyranoside (pNPG). Furthermore, the addition of XynA into commercial cellulase in the hydrolysis of pretreated corn stover resulted in remarkable increases (the relative increases may up to 90%) in the release of reducing sugars. Finally, it is worth mentioning that XynA only shows high amino acid sequence identity (88%) with rXynAHJ14, a GH10 xylanase with no activity on CMC. The similarities with other characterized GH10 enzymes, including xylanases and bifunctional xylanase/cellulase enzymes, are no more than 30%. Conclusions XynA is a novel thermostable GH10 xylanase with a wide substrate spectrum. It displays good stability in a broad range of pH and high temperatures, and exhibits activities towards xylans and a wide variety of cellulosic substrates, which are not found in other GH10 enzymes. The enzyme also has high capacity in saccharification of pretreated corn stover. These characteristics make XynA a good candidate not only for assisting cellulase in lignocellulosic biomass hydrolysis, but also for the research on structure–function relationship of bifunctional xylanase/cellulase.

Muddy siltstone combines the characteristics of both sandstone and mudstone, and is prone to instability over time. To study the long-term stability of tunnel engineering in this stratum, this article taking the cross-river metro tunnel section as the engineering background, and conducting research on the stress and deformation of the tunnel surrounding rock. Firstly, uniaxial compression creep tests were conducted on muddy siltstone to study the creep deformation law under graded loading. Secondly, a nonlinear damage creep model was established based on the Burgers model, and the experimental results were fitted. Finally, the proposed creep model was applied to the COMSOL Multiphysics numerical simulation software to perform multi field coupled calculations on the operation of metro tunnels. The research results show that: (1) Muddy siltstone undergoes the entire process of decaying creep, steady creep and accelerated creep. (2) The proposed nonlinear damage creep model can accurately describe the creep characteristics of muddy siltstone, especially in the accelerated creep stage. (3) Applying nonlinear damage creep model to tunnel numerical simulation calculation, it was found that the most obvious part of tunnel rock creep deformation is the tunnel arch crown. By comparing with on-site monitoring data, indicated that the established creep-fluid-structure coupling tunnel model can be used to predict surrounding rock deformation. The creep-fluid-structure coupling tunnel model proposed in this study provides a new perspective for the design and safety assessment of cross river tunnels in soft rock formations, which helps to achieve more accurate long-term stability prediction.

In the field of mining engineering, ensuring the safe operation of mines is of utmost importance, and the stability of the backfill materials plays a pivotal role. This research comprehensively analyzes the strain field evolution and crack development in cemented paste backfill (CPB) specimens made from whole tailings under various backfill mix designs by using uniaxial compressive strength (UCS) testing, digital image correlation, and computer vision recognition (CVR) technology. The experimental outcomes reveal that the UCS of the CPB decreases with reductions in cement-to-tailings ratio, filling concentration, and curing age, while the rate of principal strain field evolution significantly accelerates. The developed computer vision recognition model (HSV-CVR), based on hue, saturation, and value color patterns, processes strain field data to quantify the proportions of various strain regions. By applying the first derivative of these proportions, the model enables early crack prediction. This approach overcomes the limitations and subjectivity of traditional artificial vision methods for crack identification, providing precise quantification of CPB strain evolution. The research enhances understanding of mining backfill materials behavior and provides a strong scientific basis for design, monitoring, and risk management, crucial for improving mining safety and efficiency.

Rock mass engineering serves as a critical foundation for infrastructure construction and resource development [...]

During the excavation of the shaft, the inlet air temperature undergoes seasonal variations and is influenced by geothermal effects and air compression heat. Merely augmenting the inlet air volume fails to mitigate the extreme temperatures encountered at the deep working face. Consequently, the implementation of refrigeration and cooling technologies becomes imperative to manage the heat-induced issues. To address the high-temperature challenge during shaft excavation at the Sanshandao Gold Mine, a ventilation system model was developed utilizing Fluent simulation software. This model facilitated the prediction of the temperature field dynamics at the working face, taking into account project progression and seasonal shifts. Through a comprehensive analysis of factors encompassing cooling capacity deterioration, energy consumption for cooling, and the installation and maintenance requirements of refrigeration units across various systems, a surface-based centralized refrigeration system was devised. Furthermore, a simulation analysis was conducted to evaluate the refrigeration technology, offering valuable technical insights for the calculation of cooling capacity, as well as the selection and application of appropriate refrigeration systems. The results indicated that subsequent to excavating the shaft to a depth of 1600 m, the working face temperature fluctuated with seasonal variations but consistently remained above 28°C. At a depth of 1800 m, the temperature peaked, reaching a maximum of 40.19°C. Following the implementation of the surface centralized refrigeration system, with an inlet air volume of 22.6 m3/s and an inlet air temperature maintained below 10°C, the working face temperature was effectively reduced to below 27°C. This study presents a comprehensive suite of refrigeration and cooling methodologies, encompassing temperature field prediction, refrigeration parameter calculation, simulation analysis of cooling performance, refrigeration system design, and their application in deep shaft excavation. These methods provide a technical foundation for mitigating heat-induced damage in deep shafts.

This study, with the engineering background of the design of a stope involving a sublevel mining method in a certain underground metal mine, explored the application of stress-solving methods based on the complex variable function theory in actual engineering. Three mathematical calculation models based on the functions of a complex variable were established. Through triangle interpolation, mapping functions of a plane with a roadway section and a plane with the stope section were determined. An improved Schwarz alternating method was adopted to study the stability of the roadway and the influence of an adjacent roadway from the perspective of the stress field. In addition, in light of the distribution characteristics of a gangue in the stope, the design parameters of a pillar were optimized, with the pillar’s optimal dimensions determined. The results showed that when the magnitudes of two far-field principal stresses in the rock mass are relatively close, the distribution of the surrounding rock stress around the roadway is more uniform, and tensile stress is less likely to occur. The excavation of a neighboring roadway exacerbates to some extent the side stress of the other roadway, especially the compressive stress concentration on the side closer to the neighboring roadway. However, when the distance between the two roadways is significantly larger than the roadway size, this effect is not pronounced. In the engineering case studied in this research, the thickness of the pillar is approximately linearly positively correlated with the safety factor of the pillar approximately linearly negatively correlated with the recovery rate. Overall, this research explored the application of the complex variable function theory in an underground mine design, demonstrating its accuracy and practicality.

Severe asthma (SA) is a heterogeneous disease with unmet therapeutic needs. Metabolic dysregulation involving glycolysis and cholesterol synthesis is implicated in its pathogenesis. This study aimed to systematically profile the glycolysis-cholesterol synthesis axis in SA to identify distinct metabolic subtypes and explore their potential therapeutic implications. We analyzed sputum mRNA expression from 93 SA patients and 16 healthy controls (HC) in the U-BIOPRED cohort (GSE76262). First, differentially expressed genes (DEGs) in the glycolysis-cholesterol synthesis axis were identified between SA patients and HC. Unsupervised consensus clustering was then applied to these DEGs within the SA cohort to define metabolic subtypes. Immune microenvironment features were characterized using single-sample gene set enrichment analysis. A random forest (RF) model was built to distinguish subtypes, and candidate therapeutic compounds were screened for each subtype via the Connectivity Map (CMap) database based on subtype-specific gene signatures. This study revealed that, 47 genes in the glycolysis-cholesterol synthesis axis were dysregulated in SA when compared to HC. Clustering of SA based on these DEGs revealed two distinct metabolic subtypes (Cluster 1, n=52; Cluster 2, n=41). Cluster 1 exhibited an up-regulated axis with an immune landscape enriched for NK and gamma-delta T cells, linked to oxidative phosphorylation. Conversely, Cluster 2 displayed a down-regulated axis with enrichment of eosinophils, neutrophils, mast cells, and Th17 cells, associated with calcium and cAMP signaling. An RF model utilizing PPP2CB and SEH1L achieved accurate subtype discrimination (AUC=0.888), validated by decreased protein expression in an SA murine model. Exploratory drug screening suggested dipeptidyl peptidase inhibitor and mTOR inhibitor were identified as candidate compounds for Cluster 1, while leukotriene receptor antagonist and calcium channel blocker were suggested for Cluster 2 via CMap analysis. This study reveals two novel metabolic subtypes in SA, which offers a classification model and suggests potential targeted therapeutics for personalized management.

Introduction: Psittacosis is a well-recognized zoonotic infectious disorder caused by Chlamydia psittaci (C. psittaci). Human-to-human transmission of C. psittaci has rarely been reported previously, especially in the case of healthcare-associated infections. Case report: A 32-year-old man was admitted to the intensive care unit with severe pneumonia. An intensive care unit healthcare worker contracted pneumonia 7 days after performing endotracheal intubation on the patient. The first patient, a duck feeder, had been closely exposed to ducks, while the second patient had not been exposed to any birds, mammals or poultry. C. psittaci sequences were obtained by metagenomic next-generation sequencing analyses of bronchial alveolar lavage fluid of both the patients, and they were diagnosed with psittacosis. Therefore, healthcare-associated human-to-human transmission between both cases took place. Conclusions: Our findings have implications for managing patients with suspected psittacosis. stringent protective measures are needed to prevent healthcare-associated human-to-human transmission of C. psittaci.

The interval section of the Liuyang River flood control levee project of the Changsha Metro Line 6 is used as the engineering background of this study. A three-dimensional finite element numerical model of a tunnel shield containing complex interfaces is established by using the multifield coupling software COMSOL. The paper studied the deformation of flood control levees under shield tunnel excavation working conditions. The results show that when the left line shield machine is excavated below the Liuyang River flood control levee, the deformation of the flood control levee and the surrounding rock of the tunnel is biased towards the built right line tunnel. And it has an impact on the bridge pile near the tunnel. When the shield of the left line crosses the flood control levee, it can easily cause a large deformation and displacement of the levee above the area between the two shields. To ensure the controlled deformation of the levee, the construction should ensure the spacing between the two tunnel palm faces as far as possible and should be far away from other structures on the levee. When the shield crosses the levee, the deformation that occurs at the base of the levee is significantly higher than the deformations that occur at other locations of the levee. Displacement monitoring and secondary reinforcement at the base of the flood control levee appear to be necessary. The numerical simulation results validate the feasibility of using the multifield coupling software COMSOL to study the construction modeling of shield tunnels through rivers and its advantages. This method provides a practical framework for similar tunnel performance engineering or displacement monitoring in future projects.

The management of rock mass deformation in high-stress roadways is a pivotal aspect of deep geotechnical engineering. Given the fruitful outcomes of research in rock mechanics regarding traditional confining pressure control methods, scholars have increasingly turned their attention to exploring pressure-relieving techniques, including borehole pressure relief and blasting pressure relief. However, there is limited research on pressure relief methods for deep-buried hard rock tunnels. This article commences with an overview of pressure relief in the roadway and conducts a detailed study on the parameters and methods of pressure relief in the roadway. To address safety and mining efficiency challenges, such as severe deformation leading to support failures, this study conducted a parameter analysis using the Sanshandao Gold Mine as a case study. Based on existing support methods, a strategy for arranging pressure relief roadways at varying distances from the main roadway is proposed, significantly enhancing the stress environment there. Numerical simulation software was employed to model two scenarios: (1) excavating the pressure relief roadway, main roadway, and maintenance roadway simultaneously and (2) first excavating the pressure relief roadway, followed by the main roadway and the maintenance roadway simultaneously. Simulation results indicated that the first pressure relief approach outperforms the second. The optimal position for both pressure relief roadways is 15 m from the main roadway, resulting in maximum deformation of the main roadway within 100 mm. These findings align with on-site stress monitoring data and satisfy safety production criteria. The research offers a theoretical foundation for similar pressure relief techniques in deeply buried, high-stress roadways.