Search Results (92)

Multi-stage fractured horizontal wells (MSFHWs) represent a crucial development approach for low-permeability reservoirs, where accurate productivity prediction is essential for production operations. However, existing models suffer from limitations such as inadequate characterization of complex flow mechanisms within the reservoir or computational complexity. This study subdivides the flow process into three segments: matrix, fracture, and wellbore. By employing discretization concepts, potential distribution theory, and the principle of potential superposition, a productivity prediction model tailored for MSFHWs in low-permeability reservoirs is established. Moreover, this model provides a clearer characterization of fluid seepage processes during horizontal well production, which aligns more closely with the actual production process. Validated against actual production data from an offshore oilfield and benchmarked against classical models, the proposed model demonstrates satisfactory accuracy and reliability. Sensitivity analysis reveals that a lower Threshold Pressure Gradient (TPG) corresponds to higher productivity; a production pressure differential of 10 MPa yields an average increase of 22.41 m³/d in overall daily oil production compared to 5 MPa, concurrently reducing the overall production decline rate by 26.59% on average. Larger stress-sensitive coefficients lead to reduced production, with the fracture stress-sensitive coefficient exerting a more significant influence; for an equivalent increment, the matrix stress-sensitive coefficient causes a production decrease of 1.92 m³/d (a 4.32% decline), while the fracture stress-sensitive coefficient results in a decrease of 4.87 m³/d (a 20.93% decline). Increased fracture half-length and number enhance production, with an initial productivity increase of 21.61% (gradually diminishing to 7.1%) for longer fracture half-lengths and 24.63% (gradually diminishing to 5.22%) for more fractures; optimal critical values exist for both parameters. Full article

To enhance the speed control performance of the permanent magnet synchronous motor (PMSM) servo system, an improved sliding mode control method integrating a torque observer is presented. The current loop uses current feedback decoupling PID control, and the speed loop applies sliding mode control. In comparison to previous work in hybrid SMC using fuzzy logic and torque observers, this p proposes a hyperbolic tangent function in replacement of the signum function to solve the conflict between rapidity and chattering in the traditional exponential reaching law, and fuzzy and segmental self-tuning rules adjust relevant switching terms to reduce chattering and improve the sliding mode arrival process. A load torque observer is designed to enhance the system’s anti-interference ability by compensating the observed load torque to the current loop input. Simulation results show that compared with traditional sliding mode control with a load torque observer (SMC + LO), PID control with a load torque observer (PID + LO), and Active Disturbance Rejection Control (ADRC), the proposed strategy can track the desired speed in 0.032 s, has a dynamic deceleration of 2.7 r/min during sudden load increases, and has a recovery time of 0.011 s, while the others have relatively inferior performance. Finally, the model experiment is carried out, and the results of the experiment are basically consistent with the simulation results. Simulation and experimental results confirm the superiority of the proposed control strategy in improving the system’s comprehensive performance. Full article

The pore–fracture structure of ultra-deep coal is critical for evaluating resource potential and guiding the exploration and development of deep coalbed methane (CBM). In this study, a coal sample was obtained from the Gaogu-4 well at a depth of 4369.4 m in the Shengli Oilfield of Shandong, China. A comprehensive suite of characterization techniques, including Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD), Mercury Intrusion Porosimetry (MIP), Low-temperature Nitrogen Adsorption (LT-N₂GA), and Low-pressure CO₂ Adsorption (LP-CO₂GA), were employed to investigate the surface morphology, mineral composition, and multi-scale pore–fracture characteristics of the ultra-deep coal. Based on fractal geometry theory, four fractal dimension models were established, and the pore structure parameters were then used to calculate the fractal dimensions of the coal sample. The results show that the ultra-deep coal surface is relatively rough, with prominent fractures and limited pore presence as observed under FE-SEM. Energy Dispersive Spectrometer (EDS) analysis identified the elements such as C, O, Al, Si, S, and Fe, thus suggesting that the coal sample contains silicate and iron sulfide minerals. XRD analysis shows that the coal sample contains kaolinite, marcasite, and clinochlore. The multi-scale pore–fracture structure characteristics indicate that the ultra-deep coal is predominantly composed of micropores, followed by mesopores. Macropores are the least abundant, yet they contribute the most to pore volume (PV), accounting for 70.9%. The specific surface area (SSA) of micropores occupies an absolute advantage, accounting for up to 97.46%. Based on the fractal model, the fractal dimension of the coal surface is 1.4372, while the fractal dimensions of the micropores, mesopores, and macropores are 2.5424, 2.5917, and 2.5038, respectively. These results indicate that the surface morphology and pore–fracture distribution of the ultra-deep coal are non-uniform and exhibit statistical fractal characteristics. The pore–fracture structure dominated by micropores in ultra-deep coal seams provides numerous adsorption sites for CBM, thereby controlling the adsorption capacity and development potential of deep CBM. Full article

China is one of the countries most seriously affected by soil salinization, while the impact of salt-controlled irrigation on the relationship between soil dissolved organic matter (DOM) and microbial in farmland affected by salinization remains largely unexplored. We conducted a comprehensive survey of soil DOM and a microbial survey of Ordos’s salinized farmland in China before and after salt-controlled irrigation. Our findings reveal a reduction of 18.4 mg/L in surface soil (0–10 cm) DOC following irrigation, whereas the subsurface soil (20–40 cm) DOC increased by 20.7 mg/L. Moreover, irrigation led to an increase in the aromaticity and humification of the soil, with the salt content of the subsurface soil rising from 2.7 to 3.7 mg/g. Additionally, the total dissolved solids (TDS) in the drained water were 2463 mg/L higher than in the irrigation water (1416.3 mg/L). This suggests that the DOM and salts from the surface soil either leached into deeper layers or were lost via runoff. Furthermore, SEM analysis and a Mantel test revealed that microbial composition significantly influenced soil DOM contents, especially increased levels of Marmoricola and MND1, which are associated with decomposing organic matter and may contribute to the leaching of soil DOM in deep layers following irrigation. Full article

Bacillus subtilis NCD-2 demonstrates exceptional biocontrol potential against cotton Verticillium wilt. While previous studies have established its direct antifungal activity (e.g., inhibiting Verticillium dahliae mycelial growth and spore germination), our work reveals a novel mechanism: NCD-2 primes systemic resistance in cotton by activating plant immune-signaling pathways. Firstly, transcriptional profiling uncovered that NCD-2 triggers a defense response in roots analogous to V. dahliae infection, allowing cotton to maintain a more balanced state when confronted with pathogen attacks. Meanwhile, the mutant strains ∆fen and ∆srf—defective in lipopeptide synthesis—also improved cotton resistance to Verticillium wilt by activating partially identical defense pathways in cotton roots. Furthermore, the application of lipopeptide compounds derived from NCD-2, particularly surfactin and fengycin, could enhance host resistance to V. dahliae. Using an RT-qPCR approach, we found that numerous resistance-related genes were induced by these lipopeptide compounds. The up-regulation of SA/JA pathway markers (e.g., NPR1, ICS1, COI1, and LOX1) revealed NCD-2’s activation of plant immune signaling. Using virus-induced gene silencing (VIGS), we conclusively linked SA and JA signaling to NCD-2-induced defense priming. Silencing either pathway abolished resistance, highlighting their indispensable coordination. By bridging mechanistic insights and agricultural applicability, our work positions NCD-2 as a sustainable alternative to conventional fungicides, addressing both crop productivity and environmental health. Full article

As a large number of wind turbine blades reach the end of their service life, effectively utilizing decommissioned blades has become a major challenge for the wind energy industry. Among existing treatment technologies, pyrolysis is considered the most promising. This paper, based on the Web of Science database, employs bibliometric methods to analyze research trends in this field. The results indicate a significant increase in the number of published papers, with China leading in publication volume and making a substantial contribution to the field’s development. Keyword analysis highlights the central role of pyrolysis technology. Therefore, this paper discusses the application of both conventional and microwave pyrolysis technologies in this field, outlining the advantages, disadvantages, processes, performance, and economic analysis of fiber recovery. Finally, the challenges faced by pyrolysis technology and future development trends are discussed. Full article

Recently, a new phase, ω–Fe, has been observed in martensitic substructures, providing a new path for studying the position and evolution of nitrogen in high-nitrogen steels. In this paper, the density functional method was used to investigate the thermodynamic and dynamic stability of N atoms in the phases of ω–Fe, α–Fe, and γ–Fe in martensite, as well as the influence of magnetic order on them. The calculated results show that in the pure Fe phases, ferromagnetic α–Fe is a stable phase both in thermodynamics and dynamics. ω–Fe and γ–Fe are most stable in ferrimagnetism and show dynamic stability, while in ferromagnetic state they are unstable in both thermodynamics and dynamics. N-atom doping of 25% (Fe₃N) makes γ–Fe and ω–Fe thermodynamically and dynamically stable in ferromagnetic state. However, a higher N content is not conducive to the stability of ω–Fe and γ–Fe. The electronic structure shows that as the content of N atoms becomes higher than 25%, the 2p orbitals of N atoms move towards the Fermi level and become more dispersed, resulting in a large contribution of the density of states at the Fermi level. In addition, N atoms are not conducive to the stability of α–Fe, as they relax to the structure of γ–Fe at 25% N content (Fe₃N), while α–Fe in higher N contents (Fe₃N₂ and FeN) relaxes to the structure of ω–Fe correspondingly. Obviously, N tends to stabilize in the ω and γ phases in martensite, and our study provides a new clue for the formation mechanism of nitrides and martensitic transformation in Fe–N alloys. Full article

(1) Background: Volumetric modulated arc therapy (VMAT) can deliver more accurate dose distribution and reduce radiotherapy-induced toxicities for postoperative cervical and endometrial cancer. This study aims to retrospectively analyze the relationship between dosimetric parameters of organs at risk (OARs) and acute toxicities and provide suggestions for the dose constraints. (2) Methods: A total of 164 postoperative cervical and endometrial cancer patients were retrospectively analyzed, and the endpoints were grade ≥ 2 acute urinary toxicity (AUT) and acute lower gastrointestinal toxicity (ALGIT). The normal tissue complication probability (NTCP) model was established using the logistic regression model. Restricted cubic spline (RCS) curves were used to explore the association between dosimetric parameters and toxicities. The receiver operating characteristic (ROC) curve, calibration curve, Akaike’s corrected information criterion (AICc), decision curve analysis (DCA), and clinical impact curve (CIC) were analyzed to evaluate the performance of NTCP models. (3) Results: Bladder V_40Gy was identified to develop the NTCP model of AUT, and the mean AUC was 0.69 (CI: 0.58–0.80). Three candidate predictors, namely the small intestine V_30Gy, colon D_45%, and rectum D_55%, were identified to develop the NTCP model of ALGIT, and the mean AUC was 0.71 (CI: 0.61–0.80). Both models were considered to have relatively good discriminative accuracy and could provide a high net benefit in clinical applications. (4) Conclusions: We developed NTCP models to predict the probability for grade ≥ 2 AUT and ALGIT. We recommend that bladder V_40Gy, the small intestine V_30Gy, colon D_45%, and rectum D_55% be controlled below 42%, 20.4%, 16.9 Gy, and 32.0 Gy, respectively. Full article

Ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) that can be absorbed and utilized by plants are heterogeneously distributed in soil, which affects plant growth and bacterial communities in the roots. To investigate the effects of single and mixed nitrogen (N) on bacterial communities in the rhizospheres and root surfaces of Cunninghamia lanceolata (CR, CRS) and Schima superba (SR, SRS), we subjected three different ratios of NH₄⁺-N to NO₃⁻-N 2:0, 1:1 (control, CK), 0:2 to cultivate the seedlings. Compared with the CK, the ratio of 0:2 increased the number, diversity, and composition of bacteria in CR, whereas the ratios of 2:0 and 0:2 both decreased in CRS, SR, and SRS. The bacterial diversities were both R > RS in two tree species, but there was no discernible trend between the two tree species in the rhizosphere and root surface. Proteobacteria and Bacteroidota were the dominant bacterial phyla in CR and CRS, whereas Proteobacteria and Acidobacteriota dominated in SR and SRS. Patescibacteria and Planctomycetota promoted the aboveground growth of C. lanceolata but negatively drove root growth. Patescibacteria and Cyanobacteria in SR were related to its root growth, whereas the Actinobacteriota in SR and SRS, and the Patescibacteria and Cyanobacteria in SRS, promoted its aboveground growth. Overall, the mixed N addition was more conducive to bacterial community proliferation than single N on rhizospheres compared to root surfaces. The opposite reactions were observed from the aboveground and underground growth, which were driven by a few dominant bacterial phyla. Full article

The natural gas industry has developed rapidly in recent years, with gas storage playing an important role in regulating winter and summer gas consumption and ensuring energy security. The Ke7010 sand body is a typical edge water condensate gas reservoir with an oil ring, and the construction of gas storage has been started. In order to clarify the feasibility of synergistic storage building for gas injection and production, the fluid characteristics during the synergistic reservoir building process were investigated through several rounds of drive-by experiments. The results show that the oil-phase flow capacity is improved by increasing the number of oil–water interdrives, and the injection and recovery capacity is improved by increasing the number of oil–gas interdrives; the reservoir capacities of the high-permeability and low-permeability rock samples increase by about 4.84% and 7.26%, respectively, after multiple rounds of driving. Meanwhile, a numerical model of the study area was established to simulate the synergistic storage construction scheme of gas injection and extraction, and the reservoir capacity was increased by 7.02% at the end of the simulation period, which was in line with the experimental results. This study may provide a reference for gas storage construction in the study area. Full article

Raman spectroscopy plays a critical role in planetary exploration by providing detailed analysis of mineralogical and chemical compositions. However, the conventional point-focused Raman systems, while precise, are limited by their time-consuming nature, which hampers efficiency in space missions. This study compares a line-focused Raman spectroscopy system equipped with a cylindrical mirror array to a traditional point-focused system by testing various lunar-analogue minerals. The results demonstrate that the line-focused mode significantly reduces mineral detection time while covering larger sample surface areas, albeit with a slightly higher detection limit compared to the point-focused mode. Both modes exhibit similar capabilities in mineral identification and compositional analysis, with the line-focused system offering a more practical solution for rapid, high-throughput analysis in large-scale planetary geological surveys. These findings suggest that the line-focused Raman system could be a valuable tool in accelerating geochemical data collection during future deep space exploration missions. Full article

As the main method of secondary development, water injection has been widely used in fractured vuggy carbonate reservoirs. By using an evaluation index system combined with an integrated approach to objectively evaluate and support targeted and operational adjustments of water injection development effects in fractured vuggy carbonate reservoirs, a comprehensive evaluation method is established in this study. The CRITIC method is used as the main approach, and the analytic hierarchy process, the entropy weight method, and the coefficient of variation method are used as sub-methods. Additionally, the clustering centres are divided using the clustering method to reduce the error caused by the irrational distribution of the relevant evaluation index data. The method is used to evaluate and analyse the effects of water injection development, using the F_I7 fault zone of the Halahatang oilfield as an example. The application results show that the evaluation method is feasible and effective for cases with small data volume, fewer computational resources, and less time. This study has a certain reference significance for the evaluation of the effect of water injection development in similar fractured vuggy reservoirs. Full article

Heat stress adversely affects poultry production and meat quality, leading to economic losses. This study aimed to investigate the effects of adding tributyrin on growth performance, meat quality, muscle oxidative status, and gut microbiota of Taihe silky fowls under cyclic heat stress (CHS) conditions. In this study, 120-day-old Taihe silky fowls (male) were randomly divided into six dietary treatments. These treatments included a normal control treatment (NC, fed a basal diet), a heat stress control treatment (HS, fed a basal diet), and HS control treatments supplemented with 0.04%, 0.08%, 0.16%, and 0.32% tributyrin, respectively. The NC treatment group was kept at 24 ± 1 °C, while the HS treatment birds were exposed to 34 ± 1 °C for 8 h/d for 4 weeks. Results showed that CHS decreased growth performance and compromised the meat quality of broilers (p < 0.05). However, tributyrin supplementation improved ADG and FCR in broilers exposed to CHS (p < 0.05). Additionally, tributyrin supplementation resulted in increased shear force value and GSH-Px activity, as well as a decrease in drip loss, ether extract content, and MDA content of the breast muscle in broilers under CHS (p < 0.05). Furthermore, tributyrin supplementation up-regulated the mRNA expressions of Nrf2, NQO1, HO-1, SOD, and GSH-Px of the breast muscle in broilers exposed to CHS (p < 0.05). Based on these positive effects, the study delved deeper to investigate the impact of 0.16% tributyrin supplementation (HS + 0.16%T) on the cecum microbiota. The HS + 0.16%T treatment showed an increase in the relative abundance of Rikenellaceae_RC9_gut_group (p < 0.05) and a trend towards an increase in Lactobacillus (p = 0.096) compared to the HS treatment. The results indicate that supplementation successfully improved the growth performance and meat quality of Taihe silky fowls. Furthermore, tributyrin supplementation, particularly at levels of 0.16%, improved meat quality by enhancing muscle antioxidant capacity, which is believed to be associated with activation of the Nrf2 signaling pathway. Full article

Epidermal wax is strategically situated at the interface between plants and air; therefore, it plays a key role in plants’ interactions with their surroundings. It is also unstable and susceptible to light intensity. Hosta plants are shade-loving herbs with admirable flowers and leaves. Hosta ‘Halcyon’ and Hosta ensata F. Maek. are two species of Hosta with a glaucous and a glossy appearance, respectively. Light intensity can affect the composition of epicuticular wax on the leaf surface, which influences the leaf color phenotype and ornamental value. In this paper, the crystal micromorphology, content, and components of epicuticular wax on the leaves of two species of Hosta under different light conditions (10%-, 30%-, 50%-, 70%-, and 100%-intensity sunlight, relative light intensity (RLI)) have been studied using pot experiments. The results indicate that the epicuticular wax crystals of H. ‘Halcyon’ and H. ensata are tubular and platelet-like, respectively. The wax crystals of H. ‘Halcyon’ melted and formed a thick crust under 100% RLI, and those of H. ensata melted and formed a thick crust under 70% and 100% RLI conditions. The primary ingredients of the epicuticular wax of the two species of Hosta contained primary alcohols, alkanes, fatty acids, and esters; β-diketones were only detected in H. ‘Halcyon’. The quantity of epicuticular wax of H. ‘Halcyon’ reduced at first and then increased with an RLI increase, achieving its lowest value at 50% RLI, but that of H. ensata declined little by little. The amounts of C28 primary alcohols, C31 alkanes, and C18 fatty acids were significantly higher than those of other carbon atoms in the two genotypes of Hosta. The C31β-diketones content decreased with the increase in light intensity, which caused the white frost phenotype to gradually weaken in H. ‘Halcyon’. Full article

Meconopsis integrifolia is an endangered Tibetan medicinal plant with significant medicinal and ornamental value. Understanding its genetic diversity and structure is crucial for its sustainable utilization and effective conservation. Here, we develop a set of SSR markers based on transcriptome data to analyze the genetic diversity and structure of 185 individuals from 16 populations of M. integrifolia. The results indicate that M. integrifolia exhibits relatively high genetic diversity at the species level (the percentage of polymorphic bands PPB = 91.67%, Nei’s genetic diversity index He = 0.2989, Shannon’s information index I = 0.4514) but limited genetic variation within populations (PPB = 12.08%, He = 0.0399, I = 0.0610). The genetic differentiation among populations is relatively high (the coefficient of gene differentiation GST = 0.6902), and AMOVA analysis indicates that 63.39% of the total variation occurs among populations. This suggests that maintaining a limited number of populations is insufficient to preserve the overall diversity of M. integrifolia. Different populations are categorized into four representative subclusters, but they do not cluster strictly according to geographical distribution. Limited gene flow (Nm = 0.2244) is likely the main reason for the high differentiation among these populations. Limited seed and pollen dispersal abilities, along with habitat fragmentation, may explain the restricted gene flow among populations, highlighting the necessity of conserving as many populations in the wild as possible. Full article