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The green, clean and efficient utilization of coal is an important way for the sustainable development of coal industry. Shaanxi province is rich in coal resources, which are mainly distributed in the five coal fields in the north of Shaanxi province, and the oil-rich coal resources rank first in China. In this paper, the distribution characteristics of oil-rich coal in Shaanxi Province and the geological factors affecting the tar yield of coal are discussed by collecting the previous geological exploration data and the coal core of a coal mine in Yushen mining area of northern Shaanxi Province. The results show that the Jurassic coal field in northern Shaanxi is the best oil-rich coal in Shaanxi Province, and the tar yield is distributed in the range of 7.6%-15.3%. Material composition, oil generation potential, thermal evolution degree and coal-forming environment control the size and distribution of tar yield in coal. The desmocollinite content, volatile matter content, H element content and H/C atomic ratio were positively correlated with the tar yield of coal, and the correlation coefficient was high. There is a high correlation between the hydrocarbon index and tar yield in rock pyrolysis parameters, which can be used as an index to quickly identify tar yield in coal. The tar yield of coal increases first and then decreases with the increase of thermal evolution degree, and reaches the maximum value when Ro is about 0.9%. The higher the coal tar yield value is in the peat swamp facies with micro-flow, strong reduction and shallow overlying water-micro-flow in sedimentary environment. The research results provide reference for geological prediction of oil-rich coal.

At present, the technology of embedded channels in shield tunnel segments has been applied in subway tunnels, achieving significant economic benefits. However, it has not yet been implemented in high-speed railway shield tunnels, mainly because of the strict requirements of the overhead contact system, where the embedded channel is intended solely for the contact network. The low utilization of full-ring embedded channels leads to considerable waste. This study focuses on the precise positioning and installation of embedded channels in high-speed railway shield tunnels, aiming to optimize the use of embedded channels, improve on-site construction, and enhance subsequent operation and maintenance. The research is of considerable importance. Based on the Zhanjiang Bay Submarine Tunnel Project of the Guangzhou - Zhanjiang High-speed Railway, a comprehensive technical analysis was conducted. Simplifications and standardization of the contact network anchor segment joints and suspension types were carried out. The appropriate embedded channel lengths and segment combinations were determined according to the different needs of the contact network. Assembly points and corresponding channel segment blocks that met the requirements were proposed, along with recommended assembly points. Through on-site assembly tests and expert reviews, the general suspension of individual embedded channel segments for the contact network, as well as the precise positioning and assembly of locally embedded channel segments in multiple rings for center anchoring and anchoring, and suspension anchor, were successfully validated. The feasibility of precise positioning and assembly of locally embedded channels in large-diameter shield tunnels for high-speed railways was verified. This approach was applied in the 7.55 km shield section of the entire tunnel. According to the assembly results, different types of embedded channel segments were assembled to the specified design positions, achieving a 100% assembly pass rate, and fulfilling the requirements of the contact network and relevant specifications. [ABSTRACT FROM AUTHOR]

This study investigates pore distribution and permeability behavior of tar-rich coal following high-temperature pyrolysis at 500°C using X-ray computed tomography (CT) scanning. Coal samples post-pyrolysis were CT scanned, generating 1755 cross-sectional slices for three-dimensional reconstruction. An axial algorithm extracted pore distribution features, and geometric parameters were computed. An Equivalent Pore Network Model analyzed permeability characteristics. The results show that Post-pyrolysis pore distribution in tar-rich coal exhibited nonuniformity with a significant range in pore size distribution. Pores displayed concentrated spatial patterns. Total porosity was 14.24%, with 12.34% being connected. Most pores in Representative Elementary Volume (REV) regions fell within 10-50 μιτι in width and 20-60 pm in length, constituting over 40% of the total. Pore surface area peaked between 200-100 pm2, also comprising over 40% of the total. The Pore Network Model showed distinct characteristics in two REV regions: REV-1 demonstrated an early stage of development with poor connectivity, while REV-2 displayed a well-developed network with a bimodal coordination number histogram. The study highlights nonuniform post-pyrolysis pore distribution and significant pore size variations in tar-rich coal. This study is crucial for understanding permeability behavior in tar-rich coal after high-temperature pyrolysis. [ABSTRACT FROM AUTHOR]

A multi-physics numerical method coupling fluid flow, heat transfer, and a chemical reaction was used to determine the temperature distribution and the conversion rate of a coal seam during underground pyrolysis. The coal seam was fractured to enhance the heat and mass transfer. The influences of the pyrolysis pressure on the heat transfer, oil and gas production, and pyrolysis time were also analyzed. When the injection gauge pressure was increased to 14 MPa, the conversion rate on the 120th day was 98.8% and the promotion was not obvious any more at further higher pressures for the model without a fracture. For the model with a fracture, the pyrolysis was completed in only 90 days at the much lower pressure of 4 MPa, which is beneficial for both reducing the heating period and enabling the rapid harvesting of oil. Then, the fractured zone was designed and optimized by investigating different radii of the fractured zone at both the inlet and the outlet of the domain. The dead zones around the two corners at the right side of the computational domain near the outlet well were reduced effectively with an increase in the diameter of the fractured region. The heat and mass transfer were enhanced with a larger area of the fractured region at the outlet well for the reason that the flowing dead zones experienced a longer effective heating time. [ABSTRACT FROM AUTHOR]

In this paper, a POD reduced-order interpolation model for solving the in situ pyrolysis process of tar-rich coal is employed to predict the flow and heat transfer performance in the porous media region so as to save computational resources and realize fast calculations. Numerical simulation using the finite volume method (FVM) is firstly used to obtain sample data, based on the samples through the primary function and spectral coefficients of the solutions. The physical field information and parameter distribution under different conditions of inlet temperature, inlet velocity and permeability are predicted. The results are compared with those of FVM to verify the accuracy of the calculated results. The relative mean deviation (RME) of the results of the POD prediction of each parameter for each working condition was synthesized to be no more than 5%. The performance of in situ pyrolysis of tar-rich coal is then investigated, and the oil and gas production are predicted. As the inlet velocity increases from 0.3 m/s to 0.9 m/s, the fraction of high-quality oil and gas production reaches 0.47 and then decreases to 0.38. Increasing the inlet temperature and permeability has a negative effect on the fraction of high-quality hydrocarbon production, after which the quality fraction of high-quality oil and gas dropped sharply to about 0.22. Porosity has a positive impact on the oil and gas production. When the porosity reaches 0.3, the quality fraction of high-quality oil and gas can reach 0.27. [ABSTRACT FROM AUTHOR]

The Lower Paleozoic reservoir in the Micangshan tectonic belt is a new shale gas exploration area with excellent potential. However, the black shale's sedimentary environment and tectonic setting and their effects on pore-scale fluid flow have not been thoroughly elucidated and urgently require further research. A large amount of trace and rare earth element data of black shale in this area was tested to analyze the sediment's provenance, tectonic setting, and coupling process, and nuclear magnetic resonance was applied for fluid flow ability determination. The characteristics of trace elements and rare earth elements in shale samples were drilled from the Upper Sinian Doushantuo Formation, the Lower Cambrian Niutitang Formation, and the Lower Silurian Longmaxi Formation in the Micangshan tectonic belt. The results reveal that the provenance of the shales was dominated by island arc volcanic rocks and some ancient fine-grained sediments. The provenances of shale in the Micangshan, Huijunba, and Zhenba areas may have a strong genetic relationship with the igneous rocks from the nearest Hannan massif. The provenance of the Niutitang shale in the Ningqiang area may comprise sediments derived from the Longmenshan continental rift system. The provenance of the shale tends to transition from the island arc to the continental margin from the depositional stage of the Doushantuo Formation to the Longmaxi Formation. The Micangshan tectonic belt inherited the tectonic evolution of the South China block, North China block, and Qinling, and those blocks provided the igneous provenance of the shale by island arcs, which were formed due to weathering caused by the process of subduction and collision orogeny. The movable fluid distribution of the Longmaxi Formation and Niutitang Formation is relatively uniform, and excessive pursuit of large amount of movable fluid will be counterproductive to the shale reservoir. The proportion of the cracks was generally less than 3% except for one sample from the Doushantuo Formation with 12.06%. Based on the centrifugation force in this research, the low fluid flow limits were less than 1.47, and there are strong positive relationships between movable fluid saturation and saturated porosity. In this study, the coupling relationship between the material source and pore scale flow is discussed for the first time, and the results can provide theoretical references for local provenance analysis and tectonic movement. [ABSTRACT FROM AUTHOR]

Biomass from agricultural production is a renewable energy source with a high-volatile content. Semicoke (SC) and gasification residual carbon, which are ultralow volatile carbon-based fuels (LVFs), are by-products of the coal chemical industry, which are over capacity and urgently need to be cleanly and effectively consumed. Biomass and LVFs exhibit complementary fuel characteristics, particularly the volatile content, which can potentially be coprocessed efficiently. Furthermore, oxyfuel combustion technology can not only realize carbon dioxide (CO2) capture and benefit from carbon neutrality, but also effectively reduce NOx emissions. The cocombustion of biomass and ultralow volatile fuel under oxyfuel conditions can both use individual benefits and effectively control pollutant emissions. However, the cofiring characteristics and interaction mechanisms of LVF with biomass in an oxyfuel atmosphere are yet to be fully understood. In this study, three ultralow volatile fuels and one typical biomass were selected to explore the oxyfuel cocombustion characteristics via thermogravimetric experiments. The experimental results indicated that blending with wheat straw (WS) improved the overall combustion performance, the ignition point was close to that of WS, and the burnout temperature was close to the average value of the two individual fuels. An increase in the oxygen content can effectively enhance the combustion feature of ultralow volatile fuels while it has little effect on the burnout performance of biomass. In the presence of high-content CO2 , the decomposition of carbonate in ultralow volatile fuel is impeded and the decomposition temperature is slightly increased. The present investigation can promote the efficient co-utilization of inferior LVFs and biomass, which also benefits CO2 capture, carbon neutrality, and even negative carbon emissions. [ABSTRACT FROM AUTHOR]

This study aims to show how fractal analysis can be effectively used to characterize the pore structure of porous tar-rich coal. In this study, tar-rich coal pores were obtained by mercury intrusion porosimetry (MIP). The results showed that the sample had a high porosity and large pore diameter after pyrolysis, and the porosity of tar-rich coal was more than 35% at 600°C. The pore-throat ratio at high temperature was large, resulting in the high mercury retention rate. The pore distribution curves of samples at pyrolysis temperatures of 500 and 600°C were unimodal, and those of samples at room temperature and 150, 300, and 400°C were bimodal. The models for calculating fractal dimension based on MIP include Menger sponge model and thermodynamic model. Experiments show that the Menger sponge method is more reasonable when the pore size is less than 50 μm and greater than 350 nm. For the fractal dimension calculation of the whole pore curve section, the thermodynamic method was more reasonable. The use of fractal analysis in conjunction with the results of classical characterization methods leads to a better understanding of pore evolution in the pyrolysis process of tar-rich coal. The average fractal dimension could also be used as a valid parameter to monitor the textural evolution of the coals. [ABSTRACT FROM AUTHOR]

The direct results of mining damage are overburden fracture and surface subsidence, which may induce groundwater seepage and surface vegetation degradation. Therefore, it is essential to research the factors and mechanisms influencing mining damage. Based on the geological characteristics of the Xiaobaodang minefield in the Yushen Mine area in China, the engineering detection of fractured zone height (FZH), sampling tests of rock mechanical properties, and field measurements of the surface settlement were carried out. Firstly, the factors influencing the FZH were screened by correlation analysis and partial correlation analysis. Next, a model for predicting the maximum height of the fracture zone with the BP neural network (BPNN) was established and trained with Python. Finally, the FLAC3D numerical simulation experiment was adopted to reveal the variation law of overburden stress during coal mining, and the relationship between stress and overburden fracture was analyzed. The results show the following: When the average mining thickness in the study area is 5.8 m, the maximum height of the fractured zone is 157.46 m, and the maximum surface subsidence is 3715 mm. Further, the mining thickness, mining depth, the compressive strength of overburden, the width of the working face, and the mining velocity are the main factors affecting the maximum height of the fractured zone. Additionally, the goodness of fit of the BPNN model can reach 97.22%, meaning that it can effectively predict the maximum height of the fractured zone caused by coal mining. Finally, the area where the stress changes markedly above the goaf is the area where the fractures develop rapidly. Meanwhile, there is a positive correlation between the surface subsidence and the FZH. The research results obtained provide new ideas for reducing mining damage and will be helpful for the green and sustainable development of the mine. [ABSTRACT FROM AUTHOR]

Backgrounds: Kidney biomarkers in urine appear to be useful in differential diagnosis between acute tubular necrosis and other types of acute kidney injury (AKI) in cirrhosis. In clinical practice, prerenal azotemia (PRA) is often distinguished from other types of AKI by volume expansion therapy. The aim of the current study was to investigate the accuracy of urinary biomarkers in the differential diagnosis between PRA and other types of AKI. Methods: A total of 65 patients with hepatitis B cirrhosis were prospectively included and divided into AKI and non-AKI groups. Patients with hepatitis B cirrhosis and AKI discontinue diuretics, vasodilators, and nephrotoxic drugs and give volume expansion therapy. The efficacy was judged after 48 h of treatment. Urinary biomarkers were measured at the time of diagnosis of AKI and 48 h after volume expansion therapy. Univariate and multivariate analyses were used to identify independent risk factors for nonresponse to volume expansion therapy. Results: Of the 65 patients, 49 patients with newly diagnosed AKI were screened in the study, and 16 hospitalized patients with hepatitis B cirrhosis without AKI at the same period were screened as the control group. In patients with cirrhosis and AKI, 29 (59.18%) patients were in the response group and 20 (40.81%) patients were in the nonresponse group. The mortality rate in the nonresponse group was significantly higher than that in the response group (75% vs. 13.8% p < 0.001). After logistic regression analysis, urinary neutrophil gelatinase-associated lipocalin (NGAL) and serum creatinine (SCr) at diagnosis of AKI showed significant association with nonresponse to volume expansion therapy. The cutoff values for SCr and urinary NGAL were 128.50 µmol/L and 90.75 ng/ml, respectively. The area under the receiver operating curve (AUC) for SCr and urinary NGAL was 0.815 and 0.831. Conclusion: Elevated urinary NGAL can reflect the degree of kidney injury and is an independent risk factor for nonresponse to volume expansion therapy in patients with hepatitis B cirrhosis and AKI. [ABSTRACT FROM AUTHOR]

Coal reservoirs are highly heterogeneous, and different macrolithotypes of coal have differences in material composition and pore structure, resulting in different coalbed methane (CBM) adsorption/desorption performance and gas-water migration characteristics. In order to explore the pore development characteristics of different macrolithotypes in low-rank coal and their influence on adsorption and desorption, the low-rank coal of the Yan'an Formation in the Huanglong coalfield is taken as the sample of the research object. Vitrain and durain are collected and then separated. The results show that the porosity of coal is 2.92%–11.81%, and the total porosity is relatively developed. The porosity of durain is slightly higher than that of vitrain, the pore throat of durain is thicker, and the macropores are more developed. The Brunauer-Emmett-Teller (BET) specific surface area (SSA) and Barrett-Joyner-Halenda (BJH) total pore volume (TPV) of vitrain is slightly larger than durain, the micropores are more developed, and most of them are semiclosed and ink-bottle-shaped pores. The pore-fracture connectivity of the durain is better than vitrain via nuclear magnetic resonance (NMR). Vitrain has more developed micropores than durain, with larger specific surface area and stronger adsorption capacity. In the process of methane adsorption/desorption, the phenomenon of desorption hysteresis generally exists. Moreover, the pore connectivity of durain is relatively good, the degree of desorption hysteresis is weaker than vitrain, and the theoretical desorption efficiency is higher than vitrain. Temperature has a significant influence on adsorption and desorption of methane. The increase in temperature is beneficial to desorption and weakens the hysteresis effect of desorption. At the same temperature, the isosteric adsorption heat in the desorption process is greater than the adsorption process, which further explains the incomplete reversibility of the adsorption and desorption process. Under the same conditions, the isosteric adsorption heat of vitrain in the adsorption process is greater than durain, and adsorption capacity of vitrain is stronger than durain. Similarly, the isosteric adsorption heat of vitrain in the desorption process is greater than durain, and desorption needs to absorb more heat. The desorption capacity is weaker than durain. [ABSTRACT FROM AUTHOR]

The study of the relationship of in-situ stress and permeability is of great necessity to understand the formation mechanism of high-permeability coal reservoir. However, characteristics of in-situ stress and its relationship with permeability in low-rank CBM blocks of China is poorly understood. This study employs permeability and in-situ stress test experiment to analyze the vertical variation law of in-situ stress and permeability and the control mechanism of in-situ stress on permeability in the Binchang block of southwestern Ordos Basin. It is concluded that the permeability varies from 0.11–6.84 mD, and the entire coal reservoir is in a state of relative tension in the Binchang block. The extended Somerton stress–permeability model composed of six stress parameters and the geological model of in-situ stress–permeability were established. The modeling results indicate that permeability is most sensitive to the maximum horizontal stress and its derived parameters, and least sensitive to vertical stress. This model indicates that highly permeability develop in the two-stage turning burial depth section (480–800 m), which is consistent with the minimum value of stress parameters such as the lateral pressure coefficient, which indicate that the relative tension stress zone in the depth profile provides structural conditions that are conducive to the development of permeability. [ABSTRACT FROM AUTHOR]

The theory of coalbed methane distribution controlled by tectonism is a hot issue in the field of geofluid-geotectonic interaction research. Taking the geological structure in the scale range of the 1302 working face of a Guojiahe wellfield in a Yonglong mining area as the background, this paper focuses on the basic research problem of the influence of geological structure on the control of coal reservoir gas content and uses a THM coupling model to analyze the change of coalbed gas content and distribution characteristics of different tectonic positions. The change of CBM content and permeability in the anticline, syncline, and faults is analyzed. Accordingly, the variation distance of gas content and reservoir permeability controlled by tectonism of different geological structures is quantified to provide guidance for the selection of CBM-favorable areas. The research results show that the gentle dip syncline hinge zone is a potential gas-rich area with heat preservation and low permeability, while the gentle dip anticline hinge zone is a gas-poor area with low temperature and low pressure and high permeability. The thick coal seam zone of the syncline hinge zone is the potential gas accumulation zone, and the high-permeability area is near the fault plane of a normal fault. The coal matrix near the normal fault is subjected to tensile tectonic stresses to form tensional fissures, and the coal seam in the fault plane area is susceptible to coalbed gas dispersion and increases the permeability of the coal reservoir. The variation distance of gas content and reservoir permeability controlled by the normal fault within the Guojiahe wellfield is 37 m and 54 m from the fault plane, respectively. [ABSTRACT FROM AUTHOR]

In this study, to investigate the mechanical properties and microscopic geological features, a series of uniaxial compression, petrophysical properties, X-ray diffraction, elements, and conductivity tests were conducted. The results indicate that quartz and plagioclase are essential minerals determining Upper Triassic sandstone compositions, while quartz plays a dominant role in the Lower Permian sandstones. Due to microcracks, the relationships between porosity and permeability of Upper Triassic sandstones are better than those of Lower Permian sandstones. Observations have shown that silicon and aluminum are the main elements of those rocks. The rocks which have large porosity and permeability have a strong capacity of anticompression resistance. There are good consistencies between the mechanical behavior and the high proportion of rigid minerals. Similarly, the rocks which have abundant silicon and aluminum could better support the structural integrity of rocks. High pore structure heterogeneity and abundant clay minerals have positive influence on the mechanical resistance. Shales have distinct plastic deformation features when compared with the sandstones. [ABSTRACT FROM AUTHOR]

During reservoir evaluation, the microscopic pore structure of low-rank coal is mainly characterized in order to study the coalbed methane diffuse and migration mechanisms and control. The low-rank coals are very different in pore type and size, so it is necessary to use various techniques to describe their pore structure. For vitrain and durain of the Coal Member of the Yan'an Formation from Huanglong Coalfield, their chemical composition and microscopic pore structure characteristics were studied, and the factors of influencing the pore size distribution (PSD) were explored. Obviously, vitrain and durain are different in chemical composition. Vitrain has higher moisture content, volatile yield, and vitrinite group content than durain. Vitrain and durain mainly contain vitrinite and inertinite, respectively. The pore structure characteristics (e.g., pore types and PSD) of vitrain and durain were systematically by mercury intrusion porosimetry (MIP), low-temperature nitrogen adsorption, and carbon dioxide (CO2) adsorption. The vitrain and durain samples with a micropore size of <2 nm were mainly tested on their specific surface area (SSA) and pore volume (PV). The results show that microporous vitrain has larger SSA and PV than microporous durain, while mesoporous and macroporous vitrain has smaller SSA and PV than mesoporous and macroporous durain. SSA is very positively correlated with PV. The ash content is negatively correlated with SSA and PV. The ash content influences microporous vitrain more greatly than microporous durain, but mesoporous and macroporous durain more greatly than mesoporous and macroporous vitrain. SSA is positively correlated with the vitrinite content of durain and negatively correlated with the inertinite and exinite contents of durain. However, SSA is negatively correlated with the vitrinite and exinite contents of vitrain and positively correlated with the inertinite content of vitrain. Vitrain has higher methane adsorption capacity, desorption rate, and recovery ratio than durain. There are parameters that are obviously affected by the micropore characteristics. [ABSTRACT FROM AUTHOR]

Micrometer-scale pore and fracture structures of coal seams are the crucial parameters in the case of enhanced coalbed methane (CBM) recovery as they determine permeability and productivity. A significant study has been made in fracture characteristics; however, the detailed structural and fractal characteristics of micro-fractures and micro-pores of tectonically deformed coals are poorly understood. To get deep insight into the variability and heterogeneity of micro-pores and micro-fractures in different tectonically deformed coals collected from the Guojiahe coal mine, the multifractal analysis using the Menger sponge and box-counting model was employed to study deformed coals based on mercury injection porosimetry and scanning electron microscopy. The results show that tectonic deformation changed the structure of the micro-pores by increasing their diameter and that of the micro-fractures by expanding, intersecting, and creating additional microfracture networks at any scale. For the coals investigated in this study, permeability was nonlinearly correlated with their structural fractal. For undeformed coals, with the increase in the fractal dimension of micro-pores, the distribution of coal permeability exhibits a U-shape. However, it exhibited an inverted U-shape as the fractal dimension of micro-fractures increased. The distribution of the permeability of deformed coal samples is characterized by a U-shape as the fractal dimension of micro-fractures increased, while the fractal dimension of micro-pores decreased. Thus, the structural proportional odds of micro-pores and micro-fractures are vital in defining the maximum value of permeability. As a whole, deformed coals have a relatively high permeability as local micro-pores and micro-fractures are well connected. We suggest that coal seams with brittle deformation at syncline, anticline, and folded areas are favorable for CBM exploitation. [ABSTRACT FROM AUTHOR]

The world is rich in tar-rich coal resources, which have broad exploration and development prospects. At present, the academic community has relatively weak research on the impact of shock waves on the permeability of target coal bodies. This article focuses on the development technology of controllable shock waves in tar-rich coal reservoirs. Firstly, a systematic analysis was conducted on the drilling situation and physical parameters of the target coal seam. Secondly, the impact of shock waves on permeability of target coal was systematically analyzed. Thirdly, a systematic summary was conducted on the process parameters and measures of coal seam operations. Research has shown that: (a) The permeability of coal samples after shock wave action is much greater than the permeability of coal samples in their original state. (b) Under the same axial and confining pressure conditions, as the gas pressure increases, the increase in the permeability of coal under the action of shock waves shows a decreasing trend. (c) The shock wave generates a large number of crack structures inside the coal body. These cracks will undergo very obvious closure under external pressure. (d) Under different axial and confining pressures, when the gas pressure is 1 MPa, the maximum increase in permeability of coal samples under shock wave action can reach 90–200 times. When the gas pressure is 2 MPa, the increase in permeability before and after shock wave action is the smallest, reaching 30–90. • The impact of shock waves on the permeability of target coal is analyzed. • The process parameters and measures of coal seam operations is revealed. • In-situ development of oil-rich coal on-site testing operation process is discussed. [ABSTRACT FROM AUTHOR]

Research on the relationships among tectonics, micropores, microfractures, and coalbed methane (CBM) content is important for the optimal selection of CBM production areas. In this study, micropore-microfracture structural parameters of coal samples from the Guojiahe coalfield are determined through the use of X-ray photography, an image recognition algorithm, and a liquid nitrogen adsorption method. The relationship between the micropore-microfracture characteristics of the reservoir and the gas content is quantitatively assessed using the Grassberger and Procaccia (GP) algorithm to calculate the correlation dimension of the parameters. Micropore-microfracture development varies in different tectonic zones. Additionally, the CBM content varies according to the characteristic parameters of hysteresis loops and the pore diameter. The correlation dimension is an effective indicator of the nonlinear relationship between reservoir micropore-microfracture characteristics and the gas content. [ABSTRACT FROM AUTHOR]

AbstractTar-rich coal has the features of high tar yield and great potential for oil production. The underground in-situ pyrolysis technology is an effective way to accomplish the green and efficient utilization of tar-rich coal resources. The pore structures of coal seam have great change in the actual in-situ pyrolysis process. Hence, the physical properties of coal seam also vary with pyrolysis temperature, which affects the heat transfer performance of coal seam. However, previous studies on heat transfer characteristics of coal seam have been seldom paid attention to the physical property dynamic change during the in-situ pyrolysis, which possibly causes deviation between the simulated heat transfer characteristics and the actual performance. It is still unclear whether the deviation is acceptable in practical engineering practice at present. In this article, a modification scheme for the physical property dynamic change of coal seam was proposed. The effects of physical property dynamic change on heat transfer characteristics of coal seam during in-situ pyrolysis of tar-rich coal were analyzed using numerical simulation approach. In addition to single factor correction, the effects of three-factor coupling modification on heat transfer performance of coal seam were also systematically investigated. The simulation results indicated that both the average temperature and the effective heating area of the coal seam increased after the specific heat capacity was corrected individually. Whereas, the heat transfer of coal seam was weakened after the endothermic effect of pyrolysis and the thermal conductivity coefficient were modified, respectively. When the three factors were coupled for correction in the single well and single fracture mode, the correction factor that played a leading role was the thermal conductivity coefficient, accounting for 90%. However, an increase in the number of cracks enhanced the heat transfer, resulting in the specific heat capacity was dominant among the three correction factors. The present study can offer theoretical guidance and technical support for realizing large-scale in-situ pyrolysis of tar-rich coal. [ABSTRACT FROM AUTHOR]

AbstractA large amount of pyrolysis residue is left in the coal seam after the in-situ pyrolysis of tar-rich coal, which contains rich heat energy. However, there are few numerical simulations on waste heat utilization from in-situ pyrolysis of tar-rich coal at present. This paper mainly focused on the temperature field distribution and heat transfer characteristics of the coal seam in the process of waste heat utilization of tar-rich coal in large spatial scale and over a long period. The effects of cooling medium type, cooling fluid velocity, cooling fluid temperature, fracture distribution and well pattern on temperature field distribution and heat transfer performance of tar-rich coal seam were analyzed by Fluent numerical simulation. The present study can offer theoretical guidance and technical support for large-scale utilization of residual heat from pyrolysis residue of tar-rich coal. [ABSTRACT FROM AUTHOR]

The separation of low-temperature coal tar (LTCT) containing solid particles by vacuum distillation is essential in various applications, such as in-situ pyrolysis. However, the separation characteristics of solid-containing LTCT using vacuum distillation have yet to be fully understood. Therefore, explorations were conducted with variations in pressure and solid particle concentration by analyzing pitch with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The FTIR demonstrated that the organic constituents exhibit greater regularity at higher temperatures, leading to a 2 % reduction in the tightly bound cyclic OH tetramers, an intricate hydrogen bonding. The structural parameters indicate a 2 % decrease in f ar H, alongside a decline in AR from 0.332 to 0.293. This suggests that the low-pressure distillation conditions contribute to an increased retention of aromatic hydrocarbons in pitch, potentially complicating its subsequent utilization. The reduction in F from 2.273 to 2.029 signifies a shorter aliphatic chain, indicative of an intensified degradation effect. The elevated content of solid particles results in a more rigid texture of pitch in micromorphology. This study examined LTCT pitch to clarify the separation mechanism of solid-containing LTCT, offering insights into appropriate vacuum distillation conditions for LTCT separation and aiding in the effective utilization of pitch products. [Display omitted] • Analyzing pitch using FTIR and SEM reveals the LTCT vacuum distillation procedure. • Elevated distillation temperatures lead to deeper deoxygenation of the pitch. • Organic components are arranged more regularly at elevated temperatures. • Too low distillation pressure results in aromatic hydrocarbons remaining in pitch. • Increasing solids content makes the pitch harder and less friable texture. [ABSTRACT FROM AUTHOR]

Background: Data on viral kinetics and variants affecting the duration of viral shedding were limited. Our objective was to determine viral shedding in distinct severe acute respiratory syndrome coronavirus 2 variants, including Omicron BA.4/5 and BF.7, and to identify the relevant influencing factors., Methods: We carried out a longitudinal cohort study at Beijing Xiaotangshan Fangcang shelter hospital from May to June 2022 (Omicron BA.4/5) and from November to December 2022 (Omicron BF.7). Nucleocapsid protein (N) and open reading frame (ORF) genes were considered as the target genes of the reverse transcription PCR. The daily results of cycle threshold (CT), including lowest ORF1ab-CT values for days 1-3 post-hospitalisation and lowest N-CT values for days 1-3 post-hospitalisation (CT3minN) and demographic and clinical characteristics were collected., Results: 1433 patients with coronavirus disease 2019 (COVID-19) were recruited from the Fangcang shelter hospital, in which 278 patients were diagnosed with Omicron BA.4/5 and 1155 patients with Omicron BF.7. Patients with BF.7 infection showed a longer duration of viral shedding. The duration of viral shedding was associated with the variants age, alcohol use, the severity of COVID-19 and CT3minN. Moreover, the nomogram had excellent accuracy in predicting viral shedding., Conclusions: Our results indicated that patients with Omicron BF.7 had a longer period of contagiousness than those with BA.4/5. The duration of viral shedding was affected by a variety of factors and the nomogram may become an applicable clinical instrument to predict viral shedding. Furthermore, we developed a new COVID-19 viral shedding predicting model that can accurately predict the duration of viral shedding for COVID-19, and created a user-friendly website to apply this prediction model (https://puh3.shinyapps.io/CVSP&#95;Model/)., Competing Interests: Conflict of interest: The authors declare that they have no conflict of interest., (Copyright ©The authors 2024.)

Background: Lianhuaqingwen (LHQW), a traditional Chinese medicine comprised of 13 herbal extracts renowned for their robust heat-clearing and detoxifying properties, has gained widespread utilization in China but has yet to garner similar recognition abroad. It is believed to exhibit efficacy in ameliorating symptoms in individuals afflicted with coronavirus disease 2019 (COVID-19). However, the precise impact of LHQW on viral shedding (VS), particularly in the context of mild or asymptomatic infections caused by the Omicron BF.4/5 or BF.7 variants of COVID-19, remained inadequately elucidated. Consequently, a real-world study was conducted, involving patients diagnosed with COVID-19, with the primary objective of ascertaining the effectiveness of LHQW in this specific clinical context., Methods: We conducted an investigation on Omicron-infected patients through a single-center, propensity score-matched real-world study conducted at Xiaotangshan Fangcang Hospital from May to November 2022. A total of 3,368 COVID-19 patients were enrolled in the study, all of whom presented mild or asymptomatic infections caused by either BF.4/5 or BF.7 strains of the virus. Demographic and clinical data were systematically collected from medical records. Patients were allocated to receive treatment with LHQW (designated as the treatment group) or received no LHQW treatment (designated as the not-treated/no-treatment group). Viral load was quantified utilizing quantitative real-time PCR (qPCR), and the duration of VS was defined as the time interval between the initial negative test result and the date of COVID-19 diagnosis or symptom onset., Results: The study encompassed a cohort of 3,368 patients, and following propensity score matching, a subset of 296 patients was meticulously chosen for subsequent analysis. Notably, baseline characteristics exhibited disparities between the treatment and not-treated/no-treatment groups. However, post-matching, these characteristics achieved a commendable level of comparability. Our findings unequivocally demonstrated that there existed no statistically significant disparity in VS. This holds true when comparing patients subjected to LHQW treatment against those not administered LHQW, as well as when contrasting individuals presenting asymptomatic and mild COVID-19 manifestations., Conclusion: No statistically significant difference in VS was observed between patients who underwent LHQW treatment and those who did not. Additional investigations are imperative to provide a comprehensive assessment of LHQW's efficacy, particularly in patients afflicted with severe COVID-19 or those infected with viral strains distinct from BF.4/5 or BF.7., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Gai, Yan, Wu, Duan, Fan, Yuan, Yang, Bao, Jing, Cai, Ma, Zhang and Sun.)

Aim: It is challenging to predict the outcome of patients with hepatitis B virus related acute-on-chronic liver failure (HBV-ACLF) through existing prognostic models. Our aim was to establish a novel dynamic model to improve the predictive efficiency of 30-day mortality in HBV-ACLF patients., Methods: 305 patients who were diagnosed as HBV-ACLF (derivation cohort, n=211; validation cohort, n=94) were included in this study. The HBV-ACLF dynamic (HBV-ACLFD) model was constructed based on the daily levels of predictive variables in 7 days after diagnosis combined with baseline risk factors by multivariate logistic regression analysis. The HBV-ACLFD model was compared with the Child-Turcotte-Pugh (CTP) score, end-stage liver disease (MELD) score, and MELD within corporation of serum sodium (MELD-Na) score by the area under the receiver-operating characteristic curves (AUROC)., Results: The HBV-ACLFD model demonstrated excellent discrimination with AUROC of 0.848 in the derivation cohort and of 0.813 in the validation cohort (p=0.620). The performance of the HBV-ACLFD model appeared to be superior to MELD score, MELD-Na score and CTP score (P<0.0001)., Conclusion: The HBV-ACLFD model can accurately predict 30-day mortality in patients with HBV-ACLF, which is helpful to select appropriate clinical procedures, so as to relieve the social and economic burden., Competing Interests: CONFLICTS OF INTEREST No potential conflicts (financial, professional, or personal) is relevant to the manuscript.

This study aimed to determine if the immunoscore (IS) staging system would be a potential prognostic factor in hepatitis B virus-related hepatocellular carcinoma (HBV-HCC) in China.IS was performed in a consecutive cohort of HBV-HCC patients (n= 92). CD3+, CD8+, and CD45RO+ T cells were quantified by immunohistochemical analyses. The patients were stratified into 5 IS groups: I0, I1, I2, I3, I4 for every 2 cell phenotypes (IS1 (CD8/CD45RO, IS2 (CD3/CD8), and IS3 (CD3/CD45RO), respectively. ImagePro Plus software was used in the calculation of the paraffin-embedded tumor sections.The staining of CD3+, CD8+, and CD45RO+ cells in the HBV-HCC tissue demonstrated that there were higher density and larger area of lymphocytes in the invasive margins (IM) region than in the center (CT). Univariate analysis showed that preoperative TNM staging (P = .01), serum gamma-glutamyl transpeptidase (GGT) level (P = .03), vascular invasion (P = .00), and density of CD3+T (CT) (P = 0.01) were correlated significantly with disease-free survival (DFS); serum alpha-fetoprotein (AFP) level (P = .02), tumor size (P = .00), serum cholinesterase (CHE) (P = .04), and GGT level (P = .01), density of CD3+T(CT) (P = .00), CD8+T(CT)(P = .00), CD45RO+T(CT) (P = .00), and CD45RO+T (IM) (P = .02) were correlated with overall survival (OS). Multivariate analysis showed that TNM staging was not an independent prognostic factor of DFS and OS. Our results showed ISs did not have a significantly correlation with DFS (P = .35, .19, and .07, respectively), but it was correlated significantly with OS (P = .00, .00, and .00, respectively). There were statistical differences among the OS of every ISs subgroup except I0 and I1 by the Cox regressions analysis.The IS staging was closely related to the outcome of patients. It can compensate the TNM tumor classification system in predicting the prognosis of HBV-HCC patients.