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Abstract With the support of the sixth‐generation mobile networks (6G) technology, the Internet‐of‐Vehicle (IoV) can realize the perception and monitoring of vehicle road information. However, due to the change of network topology and various environment, the reliable performance of the communication link is facing challenges. For the sake of improving communication quality, a cooperative vehicular network (CVN) system is established, which adopts cooperative communication and multiple input multiple output (MIMO) technology. According to the signal‐to‐noise ratio (SNR) threshold of relay vehicles, using hybrid decode‐amplify‐forward (HDAF) protocol and combining with antenna selection, the analytical expression of outage probability (OP) with Meijer‐G function is obtained. For predicting the OP accurately, the sparrow search algorithm based on back‐propagation neural network (SSA‐BPNN) is put forward. The simulation results show that the cascade order of the channels has a negative effect on the OP. Meanwhile, the prediction accuracy of SSA‐BPNN is 64.8% higher than that of BPNN, and 98.96% greater than that of general regression neural network, and the convergence rate is faster than ICS‐BPNN.

Aiming at the problems of controlling the large deformation and failure of surrounding rock of deep soft-broken coal roadway, the gob-side entry driving with narrow coal pillar in the working face mined on both sides of the deep soft-broken coal seam in a mine is taken as the engineering background, which is very difficult to control the surrounding rock. The main difficulties of surrounding rock of coal roadway control are analyzed, and the large deformation and failure mechanisms of surrounding rock of gob-side entry driving with narrow coal pillar are studied in FLAC3D numerical simulation software. The results show that the stress adjustment and unloading caused by the mining disturbance at the large height working face, the overlying roof load of gob-side entry driving is mainly borne by the solid coal. It is concluded that the peak stress area of surrounding rock in gob-side entry driving with narrow coal pillar is mainly located in solid coal and its depth of shoulder angle, and its vertical stress concentration factor is as high as 3.04. It is clarified that the roof shoulder angle in solid coal, coal pillar and the shallow plasticized surrounding rock in solid coal are the key control areas. It is characterized that the maximum extension range of plastic zone of roof, solid coal and coal pillar is about 5.88 m, 2.50 m and 3.00 m respectively, and the sub-regional asymmetric failure mechanisms of surrounding rock in gob-side entry driving with narrow coal pillar are revealed. The analysis clarified that the anchoring foundation of anchor cables and other supporting components should be located in a relatively complete elastic zone in the deep part of surrounding rock during roadway support. Based on this, the sub-regional combined support technology of anchor beam mesh support + channel steel anchor cable reinforcement + grouting modification is proposed. Engineering practice has proved that the high-strength support reinforcement and grouting modification measures have effectively improved the stress state of surrounding rock in gob-side entry driving with narrow coal pillar in deep coal rock mass that is soft, broken and prone to large deformation and failure, and the deformation of the roof and two sides of gob-side entry driving in the test section are controlled within 500 mm. It ensures the safe and orderly mining of the working face with large-mining height and provides a reliable way for the effective control of the large deformation of surrounding rock in such deep soft-broken coal roadway.

Abstract In this study, a sump in the Xingdong coal mine (buried at a depth of over 1200 m) was used to analyze the surrounding rock's stability and control technology. Under the combined influences of various complex conditions, such as the burial depth of over 1200 m, ultra-high ground stress, and location under the goaf, the sump support became extremely difficult, severely restricting the efficient production of the mine. The overall pressure-relief mechanisms and degree of the sump surrounding the rock environment under the goaf were studied, and the rationality of the sump location was verified through numerical simulations and field tests. A more effective support scheme was proposed based on the deformation characteristics and failure mechanisms of the temporary sump-surrounding rock under the supporting conditions. The combined control technology employed the lengthened strong anchor bolts (cables), full-section concrete-filled steel tubular supports, and pouring full-section reinforced concrete and full-section long-hole grouting reinforcement. The field test results showed that after adopting the new support scheme, the sump-surrounding rock tended to be stable after three months. The sump roof subsidence amount, floor heave amount, and convergence of the two sidewalls of the sump were 17.2–19.2 mm, 13.9–16.5 mm, and 23.2–27.9 mm, respectively, thus satisfying the application requirements. This study provides an essential reference for deep-mine roadway support under a complex high-ground-stress environment.

AbstractTo further explore the molecular mechanism of triterpenoid biosynthesis and acquire high-value strain of Sanghuangporus baumii, the Agrobacterium tumefaciens-mediated transformation (ATMT) system was studied. The key triterpenoid biosynthesis-associated gene isopentenyl diphosphate isomerase (IDI) was transformed into S. baumii by ATMT system. Then, the qRT-PCR technique was used to analyze gene transcript level, and the widely targeted metabolomics was used to investigate individual triterpenoid content. Total triterpenoid content and anti-oxidant activity were determined by spectrophotometer. In this study, we for the first time established an efficient ATMT system and transferred the IDI gene into S. baumii. Relative to the wild-type (WT) strain, the IDI-transformant (IT) strain showed significantly higher transcript levels of IDI and total triterpenoid content. We then investigated individual triterpenoids in S. baumii, which led to the identification of 10 distinct triterpenoids. The contents of individual triterpenoids produced by the IT2 strain were 1.76–10.03 times higher than those produced by the WT strain. The triterpenoid production showed a significant positive correlation with the IDI gene expression. Besides, IT2 strain showed better anti-oxidant activity. The findings provide valuable information about the biosynthetic pathway of triterpenoids and provide a strategy for cultivating high-value S. baumii strains.

Abstract Extra‐thick coal seams are widely distributed in the Datong mine area in China. The rapid stopping of mining and the support withdrawal technology for extra‐thick coal seams need to be developed urgently. The reasonable stopping top coal caving distance, main roof's fracture line position, and large section roadway during the stopping period (LSRSP) support method of the header face of 15 m extra‐thick coal seam are systematically studied by using field measurement, experiment, numerical simulation, and similar material simulation methods. With the increase in stopping coal caving distance, the range of the medium and low displacement zone of the LSRSP overburden gradually expands. In contrast, the depth of the plastic zone decreases. The scope and intensity of the high‐stress area of the overlying rock in front gradually decrease and shift from deep to the outside, while the peak stress area shifts from the top coal area to the coal rib of the retracement channel. Comparing the stopping of medium‐thick and thick coal seam working face, the interaction between “main roof−unmined top coal−supports” is analyzed. The unique characteristics of the extra‐thick coal seam working face are derived: when the stopping coal caving distance is shorter than the length of the key block, the dropped coal body cannot effectively restrict the movement of key blocks. Mutual compression and subsidence occur between key blocks, making the broken coal rock block squeeze into the supports. By the simulation study of each index, the stopping coal caving distance of the extra‐thick coal seam is optimal when it is slightly larger than the length of the key block (i.e., the periodic weighting step), simultaneously, the main roof fracture line behind the supports is most favorable for stopping mining. After ensuring the stability of the LSRSP's overburden structure, the differentiated support scheme of “controlled zoning−strength grading” was proposed, and the scheme was modified and verified by simulating the support prestress field. After field practice, the roof of the retracement channel is better controlled in deformation under the joint horizontal and vertical support, the robust control effect of the combined anchor cable is noticeable, the integrity of the polyurethane network is more substantial, and the working face supports have successfully achieved a safe and rapid evacuation.

Abstract Close-distance coal seams are widely distributed over China, and the coal pillars left by the overlying coal seams affect the retracement channel of the underlying coal seam in the stopping stage. Based on the engineering background of close-distance seam mining in a coal mine, the reasonable position of the underlying coal seam's stopping line and the support method of the large section roadway during stopping are investigated using field measurements, similar simulation experiments, and numerical simulations. There are three types of location relationships between the stopping line of the underlying coal seam and the stopping line of the overlying coal seam: "externally staggered with the upper stopping line" (ESUL, stops mining under the overlying goaf), "overlapped with upper stopping line" (OUL), and "internally staggered with the upper stopping line" (ISUL, ISUL-SD for shorter internal staggered distances, ISUL-LD for longer ones). There are different stress arch structures in the overlying strata of the above three positions, and the stress arch evolution process exists in the process of ESUL → OUL → ISUL-SD → ISUL-LD: a front and rear double stress arch structure → the front arch gradually decreases → the front arch dies out, and the double arch synthesizes the single arch → the single-arch range expands → the nested double arch. The relationship between the stress arch structure and the position of the stopping line is evaluated as follows: (1) ESUL: the stress concentration in the roof plate of the retracement channel of the underlying coal seam is the highest, because the overburden block of the extensive collapse zone acts directly on the roof plate of the retracement channel, resulting in relative difficulties in roof support. (2) OUL: although the retracement channel roof pressure is minimal, the overlying rock structure has the potential for rotation or slippage instability. (3) ISUL-SD: the pressure on the roof of the retracement channel is small and the overburden structure is stable, which is conducive to the safe retraction of the support and not limited by the width of the end-mining coal pillar. (4) ISUL-LD: it is basically the same as the condition of stopping under the non-goaf; however, it has a limitation on the width of the end-mining coal pillar. The location of the stopping line is selected as ISUL-SD, and the retraction process of the self-excavating retraction channel was adopted. A partition asymmetric support scheme which is proven by field practice is proposed, through a comprehensive analysis of the pre-stress field simulation of the support scheme, based on the different control requirements of the roof above the support and the roof of the retracement channel in the stopping area. This method realizes safe and smooth withdrawal of the support.

Abstract This paper studies the width of narrow coal pillars, mining‐induced failure characteristics, and surrounding rock control effect of gob‐side entry driving (GED) adjacent to 2‐1208 filling working face with an approximately 900 m depth. Laboratory experiments, numerical simulations, loosening circle tests, and engineering practices are conducted. The mechanical properties of the filling body, the distribution and evolution law of the second invariant deviatoric stress (J2), and the variation in the plastic zone of the surrounding rock in GED are studied. The conditions of various coal pillar widths and the gob backfilled or not of the adjacent working face are also considered. The results of roadway driving along the filling working face in the deep coal mine are that: (1) The evolution law of J2 and the plastic zone features of the surrounding rock in GED have changed significantly. Thus, it is unreasonable to still adopt the customary theory of narrow coal pillar determination and roadway support design method of GED adjacent to nonfilling working face. (2) The plastic zone of GED has typically asymmetric distribution characteristics during driving and retreating, which is mainly concentrated at the upper corner of the virgin coal rib. And the elastic zone changes slightly by the influence of mining‐induced pressure on the working face, indicating that support in this area is easier. (3) During the stable period of roadway driving, there includes a “ring‐shaped” J2 depression zone at the upper corner of the coal pillar rib. While the peak zone distribution of J2 in the virgin coal rib of GED is approximately “crescent‐shaped,” and the peak zone is inclined to the upper corner of the virgin coal rib, which implies that this area is a crucial control region. (4) During the retreating period of panel 2‐1210, the direction of the maximum principal stress of GED gradually deflects from the direction of the gob to that perpendicular to the roof and floor, which represents that the key support area of GED has changed. Therefore, the advanced support of GED needs to be reinforced by single hydraulic props. The width of the coal pillar was determined to be 5 m, and a targeted truss anchor cable support method with bidirectional resistance function is proposed for the roof and both ribs, which realized the stability control of GED during deep filling mining.

Article highlights 1. The 3D particle geometries of typical energetic materials are scanned by X-ray CT and identified by improved watershed analysis. 2. The 2D and 3D computational geometry techniques are developed for determining seven commonly used particle shape descriptors. 3. The stereology strategy is used to obtain 2D projections of 3D particles and evaluate the effectiveness of 2D shape descriptors to infer 3D particle shapes of energetic materials.

Abstract In deep underground mining, achieving stable support for roadways along with long service life is critical and the complex geological environment at such depths frequently presents a major challenge. Owing to the coupling action of multiple factors such as deep high stress, adjacent faults, cross-layer design, weak lithology, broken surrounding rock, variable cross-sections, wide sections up to 9.9 m, and clusters of nearby chambers, there was severe deformation and breakdown in the No. 10 intersection of the roadway of large-scale variable cross-section at the − 760 m level in a coal mine. As there are insufficient examples in engineering methods pertaining to the geological environment described above, the numerical calculation model was oversimplified and support theory underdeveloped; therefore, it is imperative to develop an effective support system for the stability and sustenance of deep roadways. In this study, a quantitative analysis of the geological environment of the roadway through field observations, borehole-scoping, and ground stress testing is carried out to establish the FLAC 3D variable cross-section crossing roadway model. This model is combined with the strain softening constitutive (surrounding rock) and Mohr–Coulomb constitutive (other deep rock formations) models to construct a compression arch mechanical model for deep soft rock, based on the quadratic parabolic Mohr criterion. An integrated control technology of bolting and grouting that is mainly composed of a high-strength hollow grouting cable bolt equipped with modified cement grouting materials and a high-elongation cable bolt is developed by analyzing the strengthening properties of the surrounding rock before and after bolting, based on the Heok-Brown criterion. As a result of on-site practice, the following conclusions are drawn: (1) The plastic zone of the roof of the cross roadway is approximately 6 m deep in this environment, the tectonic stress is nearly 30 MPa, and the surrounding rock is severely fractured. (2) The deformation of the roadway progressively increases from small to large cross-sections, almost doubling at the largest cross-section. The plastic zone is concentrated at the top plate and shoulder and decreases progressively from the two sides to the bottom corner. The range of stress concentration at the sides of the intersection roadway close to the passageway is wider and higher. (3) The 7 m-thick reinforced compression arch constructed under the strengthening support scheme has a bearing capacity enhanced by 1.8 to 2.3 times and increase in thickness of the bearing structure by 1.76 times as compared to the original scheme. (4) The increase in the mechanical parameters c and φ of the surrounding rock after anchoring causes a significant increase in σ t; the pulling force of the cable bolt beneath the new grouting material is more than twice that of ordinary cement grout, and according to the test, the supporting stress field shows that the 7.24 m surrounding rock is compacted and strengthened in addition to providing a strong foundation for the bolt (cable). On-site monitoring shows that the 60-days convergence is less than 30 mm, indicating that the stability control of the roadway is successful.

This paper presents a conformal spiral antenna that is miniaturized and with dual-resonant for the wireless implantable capsule system. The spiral antenna conforms to a swallowable capsule with a radius of 3 mm and a length of 26 mm without occupying the internal space of the capsule. The compact antenna adopts two spiral arms to extend the effective current path for miniaturization. Biocompatible flexible polyimide was used as the dielectric substrate and capsule shell, achieving conformal properties of the antenna as well as compatibility with human tissue. The antenna has been simulated in different environmental models. The bandwidth of the antenna can reach 39.16 % (1.82 GHz-2.76 GHz) and 12.06 % (5.36 GHz-6.06 GHz) at 2.4 GHz and 5.8 GHz. The maximum gains of −35.2 dBi and −28.1 dBi can be achieved at 2.4 GHz and 5.8 GHz, respectively. In addition, the transmission characteristics of the antenna were experimentally verified in the minced pork and pig intestine. By analyzing the communication link, the communication distance between transceivers at 2.4 GHz and 5.8 GHz can meet 14 m and 5 m. These results show that the proposed antenna is suitable for wireless implantable capsule systems.

The rhizome of Atractylodes lancea (RAL) is a well-known Chinese herbal medicine (CHM) that has been applied in clinical settings for thousands of years. In the past two decades, cultivated RAL has gradually replaced wild RAL and become mainstream in clinical practice. The quality of CHM is significantly influenced by its geographical origin. To date, limited studies have compared the composition of cultivated RAL from different geographical origins. As essential oil is the primary active component of RAL, a strategy combining gas chromatography-mass spectrometry (GC-MS) and chemical pattern recognition was first applied to compare the essential oil of RAL (RALO) from different regions in China. Total ion chromatography (TIC) revealed that RALO from different origins had a similar composition; however, the relative content of the main compounds varied significantly. In addition, 26 samples obtained from various regions were divided into three categories by hierarchical cluster analysis (HCA) and principal component analysis (PCA). Combined with the geographical location and chemical composition analysis, the producing regions of RAL were classified into three areas. The main compounds of RALO vary depending on the production areas. Furthermore, a one-way analysis of variance (ANOVA) revealed that there were significant differences in six compounds, including modephene, caryophyllene, γ-elemene, atractylon, hinesol, and atractylodin, between the three areas. Hinesol, atractylon, and β-eudesmol were selected as the potential markers for distinguishing different areas by orthogonal partial least squares discriminant analysis (OPLS-DA). In conclusion, by combining GC-MS with chemical pattern recognition analysis, this research has identified the chemical variations across various producing areas and developed an effective method for geographic origin tracking of cultivated RAL based on essential oils.

A pair of tri-band multiple-input-multiple-output (MIMO) antennas with high isolation is investigated in this paper. The proposed antenna consists of two monopole antenna elements with an edge to edge spacing of 4 mm ($0.03~\lambda _{0}$ at 2.3 GHz). The monopole antenna element chose the bending line structure that can operate in tri-band and realize miniaturization. To achieve compact dimension and high isolation, symmetrical distribution layout is adopted to decouple the low frequency band, the U-shaped neutralization line (NL) contacting with two microstrip lines, and it can to improve the isolation in high frequency band, and the inverted U-shaped NL contacting with two radiation patch can decoupling in the middle frequency band. And then study the envelope correlation coefficient is lower, and the radiation pattern in operation bands is quasi-omnidirectional. It indicates that the antenna has obtained a satisfactory diversity performance within the whole operation bands which can be a good candidate for some portable MIMO applications.

According to the development requirements of green mining of coal resources, it is imperative to improve the extraction rate of coal and the application of safe and efficient mining technology. Pre-splitting and roof cutting technology is widely used in reducing residual coal pillars and safe pressure relief mining, which has become the crucial technology for pillar-free mining methods. Therefore, it is essential to review and discuss the research hotspots, cutting-edge methods, principles of action, and application areas of the development of this technology. Above all, the research data on pre-splitting and roof-cutting development in the past ten years are summarized and outlined. The research’s hot spots are pressure relief technology and gob-side entry retaining technology. Then, the functional forms of pre-splitting and roof cutting technology are discussed and compared, including explosive blasting (directional energy gathering blasting, liquid explosive blasting, and composite blasting), hydraulic fracturing, liquid CO2 gas fracturing, and mechanized roof cutting (chain arm saw machine and directional cutting roof rig). Through the analysis of field application cases, the application field is divided into three major areas: non-coal pillar mining (gob-side entry driving with narrow coal pillar, gob-side entry retaining with the filling body, completely gob-side entry retaining, and “N00” construction method), pressure relief at working face (thick and hard main roof cracking and end area hard roof cracking), and pressure relief at roadway (gob-side roadway pressure relief and blasting pressure relief technology for roadways). By detailing the process of each application technology one by one, the principle and mode of pre-splitting in each technology are expounded. Finally, the development prospects of pre-splitting and roof cutting in new technical methods, deep pressure relief mining, intelligent unmanned mining, and green and efficient mining are prospected, providing references for similar projects.

Gas control in the heading face of a coal roadway is an important and difficult point in coal mining in China. On the basis of analyzing the disadvantages of high gas control cost and long drainage period in the existing mine heading face, a long-distance pre-drainage method of long-distance drilling is proposed to control the gas in the heading face so as to improve the tunneling speed. Applied to the engineering geological conditions of Changcun coal mine, the technology is studied in detail. First, a gas migration model considering permeability changing with time is established, and the model is put into the numerical simulation software to study the variation law of permeability and gas pressure under the conditions of single borehole and multi-borehole drainage. The results show that with the increase of drainage time, the permeability around the borehole increases gradually, the gas pressure decreases gradually, and the permeability at the borehole boundary increases the most, reaching 1.2 times the initial permeability. In the process of multi-borehole drainage, there will be mutual influence between boreholes, but with the increase of borehole spacing, the degree of this influence gradually decreases. Second, according to the results of numerical simulation, a reasonable gas drainage scheme is designed and applied in the field. The field application shows that the technology has a good gas drainage effect, the gas drainage concentration and flow are at a high level for a long time, the drilling cuttings quantity is always lower than the critical value, and the excavation length of roadway increases by more than 50 m per month. These results indicate that this technology is a promising method to realize the safe and rapid excavation of a mine coal roadway.

Triterpenoids are secondary metabolites produced by the fungus Sanghuangporus baumii that have important pharmacological activities. However, the yield of triterpenoids is low and cannot meet market demand. Here, we treated S. baumii with several concentrations of MeJA (methyl jasmonate) and found that the total triterpenoid content was highest (23.31 mg/g) when the MeJA concentration was 250 μmol/L. qRT-PCR was used to quantify the transcription of five key genes involved in triterpenoid biosynthesis. The results showed that the relative transcription of most genes increased with increasing MeJA concentration, indicating that MeJA is a potent inducer of triterpenoid biosynthesis in S. baumii. To further explore whether other terpenoid biosynthesis pathways are also involved in the accumulation of triterpenoids induced by MeJA, we measured the contents of cis-Zeatin (cZ), gibberellins (GAs), and the transcript levels of related biosynthesis genes. We found that MeJA significantly inhibited the biosynthesis of cZ, GAs, and the transcription of related genes. The repressive effects of MeJA on cZ and GA accumulation were further confirmed by growth rate and biomass assays. In conclusion, our study provides an effective method to enhance the triterpenoid content of S. baumii, and also provides novel insights into the mechanism of MeJA-induced triterpenoid biosynthesis.

Close-distance coal seams are widely distributed in China, and the mining of overlying coal seams leads to floor damage. To grasp the properties and the fracture spans of the damaged main roof in the underlying coal seam, combining the calculation of the floor damage depth with rock damage theory and the formulas for calculating the first and periodic weighting intervals of the damaged main roof and the instability conditions of the damaged key blocks are obtained. Three interaction stability mechanics models are proposed for key blocks with different properties of the upper and lower main roof, and the instability conditions of the lower damaged key blocks are obtained when the fracture lines overlap. When combined with a specific example, the field monitoring verified the calculation results. The research results are as follows: (1) The first and periodic weighting intervals, horizontal thrust between blocks, and critical load of instability of the damaged main roof are significantly reduced. Still, there are differences in its reduction under different loads, rotation angles, and lumpiness. (2) When the fracture lines of the upper and lower main roofs overlap, the stability of the damaged key blocks is the lowest. There are three linkage stability regions in the critical load curves of the two key blocks. (3) In this case, the damage equivalent of the main roof is 0.397, which belongs to the local damage type. Its first and periodic weighting intervals are 40 m and 16 m, which is 22% and 24% less than when there is no damage. (4) A supporting load of 0.489 MPa is required to maintain the stability of the upper key block, and the lower damaged key block is prone to rotary and sliding instability during the first and periodic weighting, respectively. Thus, the supports need to bear a total of 0.988 MPa and 0.761 MPa to maintain the stability of the two key blocks simultaneously. The ground pressure data monitored on-site is in accord with the calculation results.

Sanghuangporus baumii is a traditional medicinal fungus that produces pharmacological terpenoids, but natural resources are insufficient for applications, and its growth and development mechanisms are poorly understood. Combining metabolomic and transcriptomic analyses, we found four terpenoid hormones and a central gene, isopentenyl diphosphate isomerase (IDI), involved in growth and development. Additionally, an exogenous hormone test was used to further confirm the importance of the four terpenoid hormones. Finally, hormone content determination and qRT−PCR were performed to explore the growth and development mechanism; we found thatcis-zeatin (CZ) plays a major role in the mycelia stage, trans-zeatin (TZ) and gibberellin A4 (GA4) are important in the primordia stage, GA4 is crucial for the fruiting bodies stage, and abscisic acid (ABA) may be a marker of maturity. The IDI gene was also found to affectterpenoid hormone content by regulating the relative gene transcript levels, thereby controlling morphological changes in S. baumii. Our results revealthe growth and development mechanisms of S. baumii and may promote the breeding and utilisation of high-quality varieties.

Mushrooms produce a large number of medicinal bioactive metabolites with antioxidant, anticancer, antiaging, and other biological activities. However, whether they produce flavonoids and, if so, how they synthesize them remains a matter of some debate. In the present study, we combined flavonoid-targeted metabolomics and transcriptome analysis to explore the flavonoid synthesis in the medicinal mushroom Sanghuangporus baumii. The S. baumii synthesized 81 flavonoids on a chemically defined medium. The multiple classes of flavonoids present were consistent with the biosynthetic routes in plants. However, paradoxically, most of the genes that encode enzymes involved in the flavonoid biosynthetic pathway are missing from S. baumii. Only four genes related to flavonoid synthesis were found in S. baumii, among which phenylalanine ammonia lyase gene (PAL) is a key gene regulating flavonoid synthesis, and overexpression of SbPAL increases the accumulation of flavonoids. These results suggest that the flavonoid synthesis pathway in S. baumii is different from that in known plants, and the missing genes may be replaced by genes from the same superfamilies but are only distantly related. Thus, this study provides a novel method to produce flavonoids by metabolic engineering using mushrooms.