Search

The complex fracture network provides the main channel for coalbed methane seepage, and its structural characteristics significantly affect the productivity of coalbed methane. In view of the lack of fracture network connectivity in existing coalbed methane seepage models, based on topological graph theory, the connectivity characteristics of fracture network were analyzed, and the expression of power law relation of fracture branch length was derived. Combined with fractal geometry, a permeability model considering fracture network structure characteristics was established on the basis of classical cubic law. The model shows that the permeability of fracture network is a function of fractal dimension, porosity, tortuosity fractal dimension, scale coefficient, connectivity, maximum fracture branch length, azimuth angle, dip angle and feature length. The permeability evolution of fracture network under true triaxial stress was analyzed. The results show that with the increase of the principal stresses σ1, σ2 and σ3, the fractures in coal are gradually compressed and the gas seepage channel becomes narrow. The permeability of fracture network shows a negative exponential decrease with the increase of the principal stresses σ1, σ2 and σ3. Based on the experimental rules and results, the fracture network fractal permeability model and S&D model (Shi-Durucan) were combined to establish the fracture network permeability calculation model under true triaxial stress. The effectiveness of the model was verified by the experimental data. The obtained permeability variation trend is consistent with the process of loading the three principal stresses, which can reflect the influence trend of the change of three-way stress on the permeability. Compared with the S&D model, it can better reflect the anisotropy characteristics of the permeability of the fracture network.

The interactions between lignin oligomers and solvents determine the behaviors of lignin oligomers self-assembling into uniform lignin nanoparticles (LNPs). Herein, several alcohol solvents, which readily interact with the lignin oligomers, were adopted to study their effects during solvent shifting process for LNPs’ production. The lignin oligomers with widely distributed molecular weight and abundant guaiacyl units were extracted from wood waste (mainly consists of pine wood), exerting outstanding self-assembly capability. Uniform and spherical LNPs were generated in H2O-n-propanol cosolvent, whereas irregular LNPs were obtained in H2O-methanol cosolvent. The unsatisfactory self-assembly performance of the lignin oligomers in H2O-methanol cosolvent could be attributed to two aspects. On one hand, for the initial dissolution state, the distinguishing Hansen solubility parameter and polarity between methanol solvent and lignin oligomers resulted in the poor dispersion of the lignin oligomers. On the other hand, strong hydrogen bonds between methanol solvent and lignin oligomers during solvent shifting process, hindered the interactions among the lignin oligomers for self-assembly.

The accurate elucidation and prediction of coal permeability evolution under stress loading conditions are crucial for coalbed methane production. In this study, flow experiments were conducted on six cylindrical coal samples and four cubic coal samples under both confining and true triaxial stress loading conditions, respectively. The structure and characteristic parameters of the fractures inside each coal sample were obtained using the computed tomography scanning system and image processing technologies. The coal permeability under both types of loading processes was calculated through the transient pulse method. A mathematical model was developed to assess the evolution of coal permeability under true triaxial loading based on the current true triaxial permeability model and fractal theory. The results revealed that during the confining pressure loading, the coal permeability decreased exponentially with effective stress and was effectively described using the SD model. Additionally, the coal permeability initially rapidly decreased, followed by a gradual decrease, and eventually stabilized at a constant value. Particularly, during the first three loading steps, the fracture aperture and corresponding permeability of the six cylindrical coal samples decreased by ∼51.79%–57.83% and ∼38.06%–42.12%, respectively. However, during the final three loading steps, the fracture aperture and corresponding permeability of the six coal samples decreased by ∼18.26%–23.08% and ∼22.15%–26.93%, respectively. Moreover, owing to the various crossing angles of complex fracture networks with each principal stress, the effect of each principal stress on the coal permeability evolution was highly anisotropic during triaxial stress loading. Particularly, the permeability of the ST1 sample decreased by 43.08%, 14.84%, and 42.08% during the loading of each principal stress. Similarly, the permeability of the ST2 sample decreased by ∼65.74%, 14.29%, and 19.97%. The permeability reductions for the ST3 sample were ∼34.03%, 55.85%, and 10.12%, while those for the ST4 sample were ∼35.97%, 46.51%, and 17.52%. The SD model failed to describe these anisotropic effects. Compared with the SD model, the improved model, based on the current true triaxial permeability model and fractal theory, effectively described the anisotropic effect of each principal stress on the permeability of coal samples with complex fracture networks under triaxial stress conditions.

In this study, the critical need for precise and accurate prediction of intra‐tumor heterogeneity related to the enhanced permeability and retention effect and spatial distribution of nanoprobes is addressed for the development of effective nanodrug delivery strategies. Current predictive models are limited in terms of resolution and accuracy, prompting the construction of a high‐resolution prediction network (HRPN) that estimates the microdistribution of quantum dots, factoring in tumor vascular and nuclear features. The HRPN algorithm is trained using 27 780 patches and validated on 4920 patches derived from 4T1 breast cancer whole‐slide images, demonstrating its reliability. The HRPN model exhibits minimal error (mean square error = 1.434, root mean square error = 1.198), satisfactory goodness of fit (R2 = 0.891), and superior image quality (peak signal‐to‐noise ratio = 44.548) when compared to a generative‐adversarial‐network‐structured model. Furthermore, the HRPN model offers improved prediction accuracy, broader prediction intervals, and reduced computational resource requirements. Consequently, the proposed model yields high‐resolution predictions that more closely resemble actual tumor microdistributions, potentially serving as a powerful analytical tool for investigating the spatial relationship between the tumor microenvironment and nanoprobes.

Abstract Abnormal lipid metabolism and chronic low-grade inflammation are the main traits of obesity. Especially, the molecular mechanism of concomitant deficiency in steroidogenesis-associated enzymes related to testosterone (T) synthesis of obesity dominated a decline in male fertility is still poorly understood. Here, we found that in vivo, supplementation of pyrroloquinoline quinone (PQQ) efficaciously ameliorated the abnormal lipid metabolism and testicular spermatogenic function from high-fat-diet (HFD)-induced obese mice. Moreover, the transcriptome analysis of the liver and testicular showed that PQQ supplementation not only inhibited the high expression of proprotein convertase subtilisin/Kexin type 9 (PCSK9) but also weakened the NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated pyroptosis, which both played a negative role in T synthesis of Leydig Cells (LCs). Eventually, the function and the pyroptosis of LCs cultured with palmitic acid in vitro were simultaneously benefited by suppressing the expression of NLRP3 or PCSK9 respectively, as well the parallel effects of PQQ were affirmed. Collectively, our data revealed that PQQ supplementation is a feasible approach to protect T synthesis from PCSK9-NLRP3 crosstalk-induced LCs’ pyroptosis in obese men.

Abstract In underground engineering such as mining and tunnel excavation, the rock mass is often subjected to repeated loading and unloading stress environments. Herein, true triaxial cyclic loading and unloading tests are carried out on fine sandstone and medium‐fine sandstone specimens with cracks of different angles. The test results show that the mechanical properties of fine sandstone and medium‐fine sandstone samples show obvious differences, and the crack angle has a significant effect on the mechanical properties of the sandstone specimen. During the experimentation, the expansion phenomenon of medium‐fine sandstone is more obvious than that of fine sandstone, and its brittleness is also weaker. The damage law of the sample has nothing to do with the type of sandstone. The damage caused by the stress in the σ1 direction varies linearly with the cumulative damage of the specimen, however, the damage caused by the directions of σ2 and σ3 grow nonlinearly in terms of the cumulative damage of the specimen. The hysteretic loop dissipated energy of the same type of sandstone specimens at different angles are dissimilar, and the dissipated energy increases with the increase of the crack angle. Based on the equivalent irreversible strain and the hysteretic loop dissipated energy, the damage law of the rock strength is analyzed. The obtained results reveal that the index based on the equivalent irreversible strain is helpful in exploring the damage degree of rock in the initial stage of cyclic loading and unloading. Furthermore, the damage index established based on the energy dissipation concept is beneficial to predicting the damage and failure law of rock in the advanced stage of loading.

Abstract The enriched collagens in the extracellular matrix (ECM) of breast cancer substantially impede drug delivery. Halofuginone (HF), a potent antifibrotic agent, was effective to deplete the collagens and remodel the ECM by inhibiting the TGFβ pathway. However, the application of HF was hindered by its strong liver toxicity. Herein, mesoporous platinum (mPt) nanoparticles were constructed to load HF as theranostic nanoplatforms. mPt had a uniform spherical structure with a diameter of 79.83 ± 6.97 nm and an average pore diameter of 20 nm and exhibited good photothermal conversion efficiency of 62.4%. The obtained HF‐loaded nanoplatform (PEG@mPt‐HF) showed enhanced cytotoxicity through the combination of photothermal therapy and the anti‐TGFβ effect induced by HF. The animal imaging and histochemical assays confirmed the PEG@mPt‐HF could efficiently deliver HF to tumors (monitored by CT) and remodel the ECM by TGFβ pathway inhibition, which resulted in increased anti‐cancer efficacy. Importantly, the liver toxicity observed in HF‐treated mice was negligible in those treated by PEG@mPt‐HF. Overall, this study designed a theranostic nanoplatform to remodel the ECM with remarkably reduced systematic toxicity and enhance the therapeutic efficacy through combination treatment.

Colorful dissolved organic matter (CDOM) is an optically important active substance in marine habitats that feature significant biochemical conservatism. Additionally, CDOM is an important tracer and indicator of pollution status in marine water masses. In this study, we use sampling data collected in September 2020 and May 2021 from the marine areas around the Leizhou Peninsula. This information is combined with the Delft 3D numerical simulation analysis to carry out a study on the relationship between the ag (355) in the marine areas and to determine the regional marine pollution levels. The results show that (1) the nearshore areas of the Leizhou Peninsula in spring and autumn are mainly lightly polluted. Compared with the same period in history, the pollution level has significantly decreased, and the ag (355), DIN, and DIP concentrations show a trend of high near the shore and low far from shore. The peak concentrations are mainly in the Zhanjiang Bay, Qiongzhou Strait, Wailuo Port, Liusha Port and Guangxi Tieshan Port. (2) ag (355) can be used as an indicator to characterize the degree of water pollution in the nearshore waters of the Leizhou Peninsula. In spring, the ag (355) interval of [0.115, 0.200] m−1, [0.201, 0.245] m−1 and [0.246, 0.484] m−1 can be considered clean, lightly polluted, and moderately polluted water, respectively. In autumn, the ag (355) interval of [0.180, 0.275] m−1, [0.276, 0.478] m−1, [0.479, 0.642] m−1, [0.643, 0.921] m−1 can be considered clean, lightly polluted, moderately polluted and heavily polluted water, respectively. (3) The response models between the ag (355) and pollutant dispersion trends were constructed in the Zhanjiang Bay and Tieshan Port. The RMSEs of the ag (355) validation points in the models were lower than 0.12 mg/L, and the MAPEs were lower than 30 %, the pollution traceability of CDOM is verified.

Abstract The effect of crack angle on energy evolution during sandstone failure subjected to true triaxial cyclic loading and unloading is of great concern. However, the energy consumed in the crack initiation and compaction process is generally referred to the dissipated energy, which is inaccurate. To reveal the energy law in the breaking process of sandstone, a complex cyclic loading and unloading test is carried out on precast angled sandstone samples by employing the triaxial test system. The area integral methodology is exploited to evaluate the evolution of total energy density, elastic energy density, dissipated energy density, and plastic energy density of the rock samples of different crack angles. The variations of these four energy density levels in terms of the number of loading and unloading cycles and the upper limit of stress are explained and discussed. The obtained results reveal that during the entire cycle of loading and unloading, the variations of the above‐mentioned factors of the rock sample fairly do not rely on the crack angle. The energy density increases with the number of cycles, and the total energy density and elastic energy density significantly increase faster than the consumption mode. The growth rate of the dissipative energy density is greater than that of the plastic energy density. Additionally, the aforementioned four energy quantities grow in a quadratic manner as a function of the upper limit of the loading stress. The releasable elastic energy gradually magnifies by increasing the upper limit of the loading stress. The plasticity density first decreases and then increases, reflecting the change law of the irreversible plastic deformation caused by newly developed cracks in the rock sample. The elastic energy density, the fitting coefficient of the dissipated energy density, and the total energy density are employed to define the characteristic coefficients of the rock energy storage and energy dissipation. The results indicate that the larger the rock crack angle, the stronger the energy storage energy and the weaker the energy dissipation capacity. It also explains that how the strength of the rock sample becomes higher as the crack angle increases.

Operation lifetime, as an important parameter, determines the performance of phosphorescent organic light-emitting diodes (OLEDs). Unveiling the intrinsic degradation mechanism of emission material is crucial for improving the operation’s lifetime. In this article, the photo-stabilities of tetradentate transition metal complexes, the popular phosphorescent materials, are explored by means of density functional theory (DFT) and time-dependent (TD)-DFT, aiming to illustrate the geometric signatures as important factors to control the photo-stabilities. Results indicate that for the tetradentate Ni(II), Pd(II), and Pt(II) complexes, the coordinate bonds of the Pt(II) complex exhibit stronger strength. It seems that the strengths of coordinate bonds are closely related to the atomic number of the metal center in the same group, which could be attributed to the various electron configurations. The effect of intramolecular and intermolecular interactions on ligand dissociation is also explored here. The large intramolecular steric hindrance and strong π-π interaction between the Pd(II) complexes caused by aggregation could effectively raise the energy barriers of the dissociation reaction, leading to an unfeasible reaction pathway. Moreover, the aggregation of Pd(II) complex can change the photo-deactivation mechanism as compared to that of monomeric Pd(II) complex, which is favored for avoiding the TTA (triplet-triplet annihilation) process.

The disturbance due to coal mining causes the surrounding rock to undergo a complex process of stress changes during which the axial pressure and the confining pressure usually change accordingly at the same time. Existing studies generally investigated this process from a static perspective, which was not rigorous. The mechanical characterization of rock is very important to understand the failure of rock mass and the safety of mining during mining disturbance. Based on theoretical analysis, we conducted axial loading and radial unloading tests on the cracked sandstone, which was combined with the ultrasonic testing technology to examine its failure rules and to characterize and analyze its failure process using longitudinal wave velocity. The results demonstrated that crack length and angle had a significant impact on the strength and mechanical properties of sandstone, and the former had a greater impact on the strength of sandstone than the latter. As the crack length increased, the strength, elastic modulus, and deformation modulus of sandstone decreased, and the strength of sandstone increased as the crack angle increased. Elastic and deformation moduli first decreased and then increased. Furthermore, Poisson’s ratio increased slowly, then decreased slowly, and finally increased rapidly as the lateral pressure coefficient diminished, and Poisson’s ratio was more sensitive to changes in the angle. In this study, the change of longitudinal wave velocity reflected the whole process of sandstone failure. When the wave velocity was stable, the rock was at the yield limit point. Moreover, when the wave velocity was unstable, the sandstone was in a progressive failure period, and as a result, the wave velocity decreased and the sandstone cracked.

Abstract Traditional methods of controlling hard roofs have a limited scope of action and cannot effectively release the strong ground pressure behavior (SGPB) induced by high‐position hard roofs (HHRs) in extra‐thick coal seam mining (ETCSM). Thus, an innovative control technology of fracturing HHRs by vertical‐well stratified fracturing (VWSF) has been proposed. However, the key parameters of VWSF, namely fracturing horizon and fracturing thickness of HHRs, which have a significant influence on stope stability, remain uncertain. In this study, a mechanical model of the “coal wall–hydraulic support–gangue” support system is established by considering the effective loading acting on HHRs, through which modified expressions for the periodic breaking span and impact kinetic energy of the stope are deduced. Based on the self‐bearing of bulking rocks, the stability principle of the surrounding rock, and energy dissipation theories, the criteria for determining the fracturing horizon and thickness of the HHR are obtained. Next, a numerical model of ETCSM, which accounts for the supporting effect of gangue, is constructed in FLAC3D. The support load and energy released by stratum breakage are determined through modeling under various hard roof parameters, thus verifying the correctness of the determination criteria. The results show that the energy released by a hard roof, average support load, and critical support load are positively correlated with thickness, and first increase before declining with respect to an increase in the fracturing horizon. The key parameters for a real coal mine are obtained by theoretical calculations and numerical simulations. A field application demonstrates that the support load and advance roadway deformation can be decreased using the proposed parameterization. This provides theoretical support for determining the key parameters of HHRs for VWSF and facilitates the widespread application of VWSF technology in HHR control.

(1) Background: Colorectal cancer (CRC) is a common gastrointestinal malignancy, accounting for the second largest gastrointestinal tumor. MORC2, a newly discovered chromatin remodeling protein, plays an important role in the biological processes of various cancers. However, the potential mechanistic role of MORC2 in promoting proliferation of CRC carcinoma remains unclear. (2) Methods: The Cancer Genome Atlas database was analyzed using bioinformatics to obtain gene expression and clinical prognosis data. The cell proliferation was assessed by CCK8 and EdU assays, as well as xenograft. SA-beta-gal staining, Western blot, and ELISA assay were using to assess the cell senescence and potential mechanism. (3) Results: Our data showed that MORC2 expression was elevated in CRC patients. Depletion of MORC2 inhibited cellular proliferation both in vivo and in vitro. Further studies showed that the depletion of MORC2 enhanced p21 and p53 expression through decreasing HDAC4 and increasing pro-inflammatory factors IL-6 and IL-8, thus, promoting cellular senescence. (4) Conclusions: We concluded that increased MORC2 expression in CRC might play a critical role in tumorigenesis by regulating the cellular senescence, in addition, MORC2 could be a novel biomarker for clinical outcomes and prognosis and a treatment target for CRC.

Structural deterioration in the roof in an underground mine can easily cause roof fall, and deterioration is difficult to detect. When drilling holes for roof bolts, there is a relationship between the vibration of the drill rod and the properties of the rock being drilled. This paper analyzes transverse, longitudinal, and torsional vibrations in the drill rod by using vibration theory. Characteristic indexes for three kinds of vibration are determined. Using the finite element analysis software ABAQUS, a model for drill rod vibration during the drilling of roof bolt holes was established based on the geological and mining conditions in the Guyuan Coal Mine, northern China. Results from the model determined that the transverse and the longitudinal vibration decrease as the rock hardness decreases. In descending order, sandstone, sandy mudstone, mudstone, and weak interbeds cause progressively less vibration when being drilled. The ranking for strata that cause decreasing torsional vibration is slightly different, being, in descending order, mudstone, sandstone, sandy mudstone, and weak interbeds. These results provide a theoretical basis for predicting dangerous roof conditions and the presence of weak interbeds to allow for adjusting bolt support schemes. Keywords: Roof bolt holedrilling, Drill rod vibration, Vibration radius, Vibration point amplitude, Negative angular acceleration

Our study explored the effect of perceived inclusive leadership on job performance of university teachers and the serial mediation effect of perceived school support and psychological empowerment among those teachers. Using the questionnaire method, data were collected from a valid sample of 895 university teachers in China. The findings indicated that perceived inclusive leadership significantly and positively affects university teachers' job performance. Among university teachers, both perceived school support and psychological empowerment have a partial mediation effect on the relationship between perceived inclusive leadership and job performance. Perceived school support and psychological empowerment have a serial mediation effect between perceived inclusive leadership and job performance. This study provides theoretical and empirical evidence for research related to job performance of university teachers.

This study investigated the use of frequent metre-scale resolution Pléiades satellite imagery to monitor water quality parameters in the highly turbid Gironde Estuary (GE, SW France). Pléiades satellite data were processed and analyzed in two representative test sites of the GE: 1) the maximum turbidity zone and 2) the mouth of the estuary. The main objectives of this study were to: (i) validate the Dark Spectrum Fitting (DSF) atmospheric correction developed by Vanhellemont and Ruddick (2018) applied to Pléiades satellite data recorded over the GE; (ii) highlight the benefits of frequent metre-scale Pléiades observations in highly turbid estuaries by comparing them to previously validated satellite observations made at medium (250/300 m for MODIS, MERIS, OLCI data) and high (20/30 m for SPOT, OLI and MSI data) spatial resolutions. The results show that the DSF allows for an accurate retrieval of water turbidity by inversion of the water reflectance in the near-infrared (NIR) and red wavebands. The difference between Pléiades-derived turbidity and field measurements was proven to be in the order of 10%. To evaluate the spatial variability of water turbidity at metre scale, Pléiades data at 2 m resolution were resampled to 20 m and 250 m to simulate typical coarser resolution sensors. On average, the derived spatial variability in the GE is lower than or equal to 10% and 26%, respectively, in 20-m and 250-m aggregated pixels. Pléiades products not only show, in great detail, the turbidity features in the estuary and river plume, they also allow to map the turbidity inside ports and capture the complex spatial variations of turbidity along the shores of the estuary. Furthermore, the daily acquisition capabilities may provide additional advantages over other satellite constellations when monitoring highly dynamic estuarine systems.

Density functional theory (DFT) calculations at the TPSSh-D3(BJ)/def2-TZVP (SMD, water) level of theory were performed to understand the mechanism of redox-neutral depolymerization of four types of lignin-derived aryl ether dimers catalyzed by rhodium-terpyridine ([Rh]) and a binuclear Rh complex ([2Rh]). The cleavage of the Cβ–O bond in the β-O-4 model compound was initiated by the dehydrogenation of the alcohol moiety into a ketone intermediate, followed by the reductive cleavage of the ether bond, producing phenol and aromatic ketone products. The [Rh]–OH intermediate, generated by the interaction between the Rh-complex and NaOH, facilitated the transformation of the alcohol group to a C=O group in the lignin model compound and subsequent H-transfer, selectively forming rhodium-H active species and the ketone intermediate. The [2Rh]–H complex exhibited high reactivity, with energy barriers for a rate-determining Cβ–O bond breakage of 35.3 kcal mol−1. In contrast to 1-phenylethan-1-ol and H2, lignin itself acted as a good hydrogen source to generate [Rh]–H species. The transformation of β-O-4 model compounds with the γ-OH group occurred via the elimination of the γ-OH group, reduction of the C=C bond, and Cβ–O bond cleavage steps. However, since lignin itself was unable to supply enough hydrogen to form [Rh]–H species, the aromatic products were obtained in low yields, as observed in the experiment. [ABSTRACT FROM AUTHOR]