Search Results (418)

The northern Vietnam shelf, particularly the area adjacent to the Red River Fault Zone, is characterized by complex geology and active neotectonics. However, the patterns of degassing and the origins of hydrocarbon gases in this region remain poorly understood. In particular, the potential links between deep-seated fluid migration, fault systems, and gas anomalies in island groundwater systems have not been systematically investigated. This study presents preliminary results of dissolved methane, its homologues (C₂–C₅), helium, hydrogen, and carbon dioxide measurements in groundwater from Co To Island (Northern Vietnam), with the aim of identifying gas origins and assessing structural controls on fluid migration. A significant methane anomaly was discovered, with concentrations reaching up to 10% by volume in the northwestern part of the island. The hydrocarbon homologous series is traced up to pentane (C₅), and CO₂ content is also elevated, with a maximum of 5.4%. The average He concentration of 10.8 ppm significantly exceeds atmospheric equilibrium values, with maximum recorded concentrations of 18 ppm for He and 34.5 ppm for H₂. Stable carbon isotope analysis of methane (δ¹³C-CH₄ values ranging from −50.2‰ to −49.7‰ VPDB), combined with the presence of a complete C₁–C₅ hydrocarbon series and elevated mantle/crustal tracers (He, H₂), indicates a predominantly thermogenic/metamorphogenic origin for the gases, ruling out a purely biogenic source. The spatial distribution of anomalies is structurally controlled, closely associated with the NE-SW trending Co To Fault system and its intersections with subsidiary faults, as corroborated by recent electrical resistivity tomography data. These findings indicate intensive, focused gas leakage from a deep-seated source, likely related to thermogenic/metamorphic processes and active fault-mediated degassing. The results highlight the significant hydrocarbon potential of the region and underscore the critical role of neotectonic activity in controlling fluid migration pathways in island aquifer systems. Full article

The comprehension of the complex dynamics of degassing is critical for volcano monitoring and assessing volcanic hazards. In this study, we apply visibility graph analysis (VGA) to a decadal, high-resolution time series of daily soil CO₂ flux recorded by a standardized monitoring network at Mt. Etna volcano (Italy). By mapping these time series into complex networks, we demonstrate that the connectivity degree distributions follow a power law described by the exponent $\gamma$, which reveals a self-similar behavior of gas emissions. We introduce the $\gamma$-deviation, namely the variation of the scaling exponent from its long-term site-specific baseline, as a novel proxy for degassing efficiency. The long-term baseline is interpreted as a site-specific measure of flux efficiency, while its variations are attributed to other factors, such as fluctuations in the sources or changes in the efficiency of fluids transport pathways. Our results identify a transition from a period of discordance across the monitoring sites (pre-2016) to a phase of network-wide concordance (after 2016). The striking correlation between topological $\gamma$-deviations and the established normalized network signal (${\Phi }_{norm}$) validates the methodology, suggesting that VGA is able to capture the same underlying magmatic drivers. This study establishes VGA as a robust and reliable tool for medium- and long-term monitoring, potentially capable of identifying the occurrence of large-scale magmatic processes and refining the characterization of fluid transport dynamics in active volcanic systems. Full article

Iron oxide–copper–gold (IOCG) deposits are widespread throughout the Carajás Province, Brazil, reflecting multiple Precambrian hydrothermal events. The Aquiri region is a relatively unexplored geological frontier in the northwestern Carajás Province. The AQW2 IOCG deposit is hosted by a Neoarchean mafic intrusive suite within metavolcano–sedimentary rocks. The pre-mineralization (Na and Na-K) and mineralization (Fe-Ca and Fe-P) hydrothermal stages appear as replacement fronts and as cement within ductile-deformed breccias. Late-mineralization (Fe-K, chlorite, and calcic-rich) assemblages occur in multidirectional veins controlled by brittle structures. Early- and main-mineralization apatite (Ap I-III) is enriched in F, Mn, and Sr, depleted in Y, shows unusually high Fe and Si (Ap III), and exhibits a pronounced positive Eu anomaly (Ap II). These characteristics indicate an alkaline fluid composition, substantial fluid–rock interaction, and episodic CO₂ degassing with the release of overpressured fluids, resulting in multiple brecciation events. A rapid decrease in temperature due to boiling is interpreted as a principal mechanism for copper precipitation. Late-mineralization apatite (Ap V–VI) is characterized by relatively higher Cl, Y, and LREE contents, lower Sr and Mn, and negative Eu-anomaly ratios, suggesting control by shallower paleostructures and more oxidizing conditions associated with the influx of basinal brines. These results highlight the evolution of the AQW2 deposit within a broader IOCG system and provide new insights into the metallogenic processes responsible for copper resources essential to the clean energy transition. Full article

The travertine formed through the precipitation of supersaturated calcium carbonate from geothermal or surface waters due to CO₂ degassing, evaporation, and biological activities not only exhibits remarkable landscape value but also holds significant scientific importance in geological research. Current conservation efforts face critical challenges including travertine degradation, increased algal biomass accumulation, and progressive marshification processes. The study focused on how Vallisneria natans (V. natans) and Ceratophyllum demersum (C. demersum) affected travertine deposition. Analyzing the physical and chemical parameters, phase structure, crystal morphology, and microbial community in the aquatic environment, it was observed that under conditions of low c (Ca²⁺) concentration in solution (≤100 mg L⁻¹), both species significantly increased the rate of travertine deposition. The effect of plant biomass was species-specific: V. natans showed the highest promotion at 70 g L⁻¹, while C. demersum performed effectively at moderate biomass levels (140 and 280 g L⁻¹). Specifically, C. demersum exhibited enhanced photosynthetic activity, elevated pH, increased dissolved oxygen (DO) content and more epibiotic microorganisms, with higher levels of Aeromonas compared to V. natans. Therefore, C. demersum demonstrated a greater capacity for travertine deposition. However, the culture environment with elevated c (Ca²⁺) ≥ 500 mg L⁻¹ or higher biomass levels (420 g L⁻¹) impeded the stable growth of submerged plants and exerted a stress effect on them, hindering travertine deposition. The morphology of travertine crystals promoted by the two submerged macrophytes was distinct. In the V. natans treatment, the crystals were square and elongated, whereas in the C. demersum treatment, they were spheraragonite, droplet-like, and petal-shaped. This study reveals the mechanisms by which submerged macrophytes promote travertine deposition and provides new insights for adopting nature-based ecological restoration strategies to sustainably maintain travertine landscapes. By leveraging the promoting effects of submerged macrophytes, travertine deposition and the aquatic environment were improved while reducing energy and chemical inputs. Such biological regulation approaches help synergistically achieve the dual objectives of geological heritage conservation and ecosystem health restoration. Full article

The Mabi Block is located in the southern Qinshui Basin, representing an underexplored region with high-rank coal seams that host significant Coalbed Methane (CBM) potential. Despite extensive CBM development in the nearby Anze and Zheng Zhuang blocks, the geological and geophysical controls on Coalbed Methane enrichment in Mabi remain insufficiently constrained. This study integrates the core data (63 samples) of isothermal adsorption tests, well-logging data from (13 wells), and 3D seismic attributes to systematically evaluate the key controlling factors, such as burial depth, roof and floor lithology, and sealing capacity, in the horizons of the No.3# and No.15# coal seams. Lithology is characterized using natural gamma ray (GR), acoustic (AC), deep resistivity (RD), compensated neutron log (CNL), and seismic wave impedance inversion. Coal quality parameters, ash content, and the Langmuir volume (V_L) are correlated with gas content, and structural controls are mapped using curvature, fault interpretation, and burial depth analysis. The results show that thick mudstone and limestone roofs, moderate burial depth (1100–1350 m), synclinal structural lows, and thicker coal seams (6–9 m) collectively enhance methane preservation. The ash content (%) exhibits a moderate negative correlation with the Langmuir volume (R² = 0.4) and gas content. Structural curvature (syncline) and fault intensity strongly govern lateral sealing integrity, where anticline zones and faulted regions display notable degassing. This integrated assessment contributes to a refined CBM optimization model for the Mabi Block and guides targeted future drilling, reservoir evaluation, and production optimization. Full article

Ultrasound has emerged as a versatile and promising tool to enhance and speed up traditional processing operations used by the food industry or to be used as an alternative food-processing method. This review provides an overview of the fundamental principles of sonication and its diverse applications in food processing. The core concepts of acoustic cavitation and the influence of power on processing outcomes are discussed in detail. The design and operation of different ultrasound systems, including direct-contact probe and indirect-contact bath systems, and their respective advantages were reviewed. Furthermore, a wide array of applications were explored, namely extraction, homogenization, degassing and deodorizing, pasteurization and vegetable blanching, drying and dehydration, freezing and thawing, brining and hydration, and cutting, highlighting how ultrasound waves can enhance process efficiency and improve product quality. The review also provides a critical analysis of the challenges and limitations associated with scaling up the technology for industrial use, including potential impacts on food quality, safety considerations, and economic viability. Finally, future perspectives and potential areas for further research are outlined to encourage the broader adoption of this technology in the food sector. Full article

Gas–liquid cyclone separators are an efficient and emerging method for air removal in hydraulic systems, yet often suffer from excessive pressure loss. A novel contracting inlet guiding structure is proposed to minimize hydraulic losses. This study adopts a comprehensive methodology combining theoretical modeling, computational fluid dynamics (CFD) using the Reynolds Stress Model (RSM), and experimental validation. A theoretical pressure-loss model incorporating the diminishing-returns effect of the contraction angle was established. Simulations revealed that increasing the contraction angle reduces energy dissipation by improving the uniformity of the tangential-velocity field. Based on the balance between pressure-loss reduction and degassing potential, a contraction angle of 11° was identified as the optimal design and experimental tests on a prototype confirmed the validity of the numerical model. The results demonstrate that, compared to the conventional straight tangential inlet, the optimized inlet reduces the pressure loss by approximately 30% under rated conditions. The experimental–numerical discrepancy decreases significantly with flow rate, achieving a relative error of approximate 10% at the design flow rate. These findings provide a theoretical basis and practical guidance for the low-energy design of hydraulic cyclone separators. Full article

Tourmaline nanoparticle-reinforced DGEBA/MTHPA epoxy nanocomposites were developed to obtain mechanically robust insulating materials with reduced dielectric loss. Composites containing 0–20 phr tourmaline were prepared by mechanical mixing, vacuum degassing, and stepwise curing, and FTIR verified successful curing and network formation. Tourmaline delivered stiffness-dominated reinforcement, increasing the flexural modulus from 2.585 to 4.07 GPa. At 5 phr, the composites reached simultaneous maxima in flexural strength and impact strength, corresponding to improvements of 5.02% and 57.4% over the unfilled resin, respectively. Moreover, the modified epoxy thermosets still maintained excellent T_g and thermal decomposition temperature. Electrical insulation improved concurrently, as volume resistivity increased from 1.36 × 10¹⁶ Ω·cm for EP-0 to 1.89 × 10¹⁶ Ω·cm for EP-20, and surface resistivity rose from 1.72 × 10¹⁵ to 2.49 × 10¹⁵ Ω, giving 9.6–39.0% and 14.2–44.9% gains for EP-5 to EP-20. Notably, at 50 Hz, 5 phr tourmaline preserved a low permittivity of 4.360 while reducing dielectric loss tangent (tan δ) from 0.0270 to 0.0190, a 29.6% decrease. Collectively, these improvements reduce dielectric heating and support reliable operation of epoxy-based insulation in power equipment. Full article

This research investigates wettability-induced, preferential, pressure-driven bubble nucleation of gases from a multi-gas dissolved liquid system in hydrophilic and hydrophobic glass vials. The hydrophobic glass surfaces were prepared using (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane (HT). Degassed deionized water in a vial, placed inside a pressure cell, was saturated with a precisely controlled mixture of CO₂ and CH₄ gases at either 6000 mbar or 3000 mbar for 24 h. To initiate the pressure-driven bubble nucleation process, a 500 mbar step-down pressure was applied to the pressure cell every 15 min until bubble nucleation was observed. CH₄ and CO₂ volume fractions were measured using micro-gas chromatography (Micro-GC), while a digital microscope was employed to observe the bubble nucleation process. No bubble nucleation was observed in the case of the hydrophilic vial even when the system pressure was brought to atmospheric pressure. In the case of the hydrophobic vial, the average onset bubble nucleation pressures were 4800 mbar and 2000 mbar for 6000 mbar and 3000 mbar saturation pressures, respectively. The average feed gas concentrations during saturation were 84.44 ± 0.14% and 15.44 ± 0.2% of CH₄ and CO₂, respectively, while at the onset pressure for bubble nucleation, the concentrations shifted to 85.24 ± 0.48% and 13.12 ± 0.52% of CH₄ and CO₂, respectively, when the saturation pressure was 6000 mbar. The average feed gas concentrations during saturation were 85.12 ± 0.28% and 14.67 ± 0.1% of CH₄ and CO₂, respectively, and the average concentrations of CH₄ and CO₂ gases at onset pressure for bubble nucleation were 86.06 ± 1.21% and 12.03 ± 1.03%, respectively, when the saturation pressure was 3000 mbar. The increase in CH₄ concentration is attributed to its preferential separation during the bubble nucleation process. Full article

Sm₂TM₁₇ sintered magnets, (where TM = Co, Fe, Cu, Zr), are typically utilised in high temperature magnetic applications due to their magnetic properties being very stable at 200–350 °C. Sm and Co are critical materials and need to be recycled to reduce reliance on virgin material supply chains. This work explored HD processing of Sm₂TM₁₇ sintered magnet production scrap as a potential recycling technique. Sintered magnet scrap was initially analysed compositionally, microstructurally and magnetically to determine issues with magnet quality. Scrap material was then HD processed at 18 bar and 2 bar at temperatures between 25–300 °C. The resultant material was characterised in terms of hydrogen content, particle size, degassing behaviour and unit cell expansion. Production scrap magnets exhibited irregular demagnetisation traces with poor domain wall pinning behaviour. Non-magnetic ZrC inclusions likely prevented cell structure formation locally and hence were poor domain wall pinning sites. Scrap material processed at 18 bar and 2 bar required temperatures of 100 °C to allow for the greatest extent of HD reaction, reaching 0.299 Wt.% and 0.323 Wt.% hydrogen respectively. The HD behaviour of production scrap material was comparable to commercial grade magnets. Therefore, HD is a potentially viable technique for recycling Sm₂TM₁₇ sintered magnet production scrap. Full article

In September 2021, significant changes in the geophysical and geochemical parameters on Vulcano Island were recorded by the surveillance network activities and periodic surveys. Between October 2021 and June 2024, additional surveys were conducted to acquire LIDAR, thermal, and RGB datasets for the generation of Digital Terrain Models (DTMs), orthophotos, and fumarole field maps. These data were collected using DJI Matrice 300 UAS platforms. Precision positioning was ensured through a POS/NAV RTK georeferencing approach. The instrumentation included Genius R-Fans-16 and DJI Zenmuse L1 laser scanners for structural mapping, alongside Zenmuse H20T infrared cameras for the thermal detection of potential instabilities on the volcano flanks, focused on the northern area and summit of Gran Cratere La Fossa, and these were subsequently repeated in May 2022, October 2022, October 2023, and June 2024. Additionally, 3D reconstruction targeted morphological variations in unstable areas like the cone top, Forgia Vecchia, and the 1988 landslide site. In May 2022, anomalous degassing in the Eastern Bay led to increased gas and hydrothermal fluid emissions, causing water whitening in front of Baia di Levante. Optical-thermal monitoring, both on land and at sea, detected multiple hydrothermal gas streams, aiding in assessing the magnitude and areal extension of fumarolic fields. These findings contribute to establishing a comprehensive monitoring approach for understanding the volcanic unrest evolution cost-effectively and safely. Full article

Potato harvesters operating in hilly and mountainous areas are often subjected to harsh working conditions such as high temperature, sun exposure, and high torque excavation. Due to the fluid sealing characteristics, closed loop hydraulic systems are prone to high temperatures during long-term continuous operation, resulting in a decrease in fluid viscosity, poor lubrication, severe wear, and power attenuation. This study investigates the hydraulic system of potato harvesters in hilly terrain, systematically analyzing its energy transfer process and identifying key heat-generating components. Based on an optimization strategy that extends the flow path of high-temperature fluid within the tank, four distinct tank designs were proposed. Computational fluid dynamics (CFD) and thermodynamic simulations were conducted to evaluate their heat dissipation performance, followed by full-machine validation testing. Results indicate that the walking and lifting systems are the primary heat sources. The dual pump contributes the highest proportion of heat (52.07%), followed by the walking motor (20.54%). The heat exchanger dissipates 72.91% of the heat, while the hydraulic oil tank accounts for 14.93%. Among the four tank designs, Tank 0 exhibited the fastest temperature rise, reaching a thermal equilibrium of 83.27 °C, whereas Tank 1 had the lowest equilibrium temperature (78.62 °C). Heat dissipation efficiencies for the tanks were 7.8%, 12.9%, 10.1%, and 11.6%, respectively. The residual gas volume fraction decreases significantly as the bubble diameter increases, due to the higher buoyancy and faster rise velocity of larger bubbles, which leads to shorter residence times and more effective precipitation. Tank 1 achieved the lowest equilibrium temperature, indicating the best thermal efficiency. Tank 3 showed the best overall degassing performance, particularly for medium-to-large bubbles. Tank 1 was selected as the optimal final design because it could offer an excellent balance, with very good cooling and competitive degassing (especially for small bubbles). Field tests confirmed a 14.8% reduction in thermal equilibrium temperature for Tank 1 (75.6 °C) compared to Tank 0 (88.7 °C). Simulation and experimental data showed strong agreement, with maximum errors of 9.2% for return fluid temperature, 12.7% for cooling return fluid temperature, 9.7% for pressure, and 8.5% for flow rate. Average errors remained below 8.4% for pressure and 7.6% for flow rate. These results validate the accuracy of the simulation model and the effectiveness of the tank optimization method. Full article

This study investigates the evolution and influencing factors of non-metallic inclusions in industrial pipeline steel during the vacuum degassing (VD) process. Steel and slag samples were systematically collected at multiple intervals throughout the vacuum treatment using an automated robotic sampler, which integrated temperature measurement and sampling functions. The results indicate that the molten steel temperature and the concentrations of nitrogen, oxygen, and sulfur exhibited an overall decreasing trend, with removal kinetics characterized by a rapid initial reduction followed by a gradual stabilization. The dominant inclusion phases were identified as Mg-Al spinel and calcium aluminates. Specifically, the top slag composition was distributed within the C₃A phase field, trending toward the liquid C₁₂A₇ region, while the endogenous inclusions transitioned from CA₂ toward CA. With prolonged vacuum treatment, the relative fraction of calcium aluminates progressively increased at the expense of Mg-Al spinel due to continuous slag-metal reactions. Furthermore, quantitative analysis reveals that the population density of small equivalent circular diameter (ECD) inclusions continuously decreased, while the average inclusion size increased, indicating that the VD process promotes the collision and coalescence of inclusions. Full article

Surface defects are frequently observed in calendered polyvinyl chloride (PVC) films. Their evaluation in production environments is typically qualitative and operator dependent. Using the common gas entrapment defects as the test case, the present study develops a four-step image-processing workflow that converts scanned film images into pixel intensity matrices and groups defect pixels using density-based clustering (DBSCAN). The procedure provides quantitative measures of defect count, size, and spatial distribution without manual labeling. The effects of roll gap, calendering speed, upstream mixing time, and plasticizer type were examined under controlled conditions. Larger roll gaps and higher speeds reduced degassing efficiency and increased both defect number and defect area. Short mixing times led to incomplete gelation and higher defect frequency. Among the tested plasticizers, TOTM produced the lowest defect counts, followed by DEHP and ESBO. Design-of-experiments analysis ranked parameter sensitivity and identified operating ranges that limit defect formation. The method provides a practical basis for routine surface inspection and supports process adjustment using measurable defect metrics rather than visual judgment alone. Full article

Electro slag remelting steel is a technology of tertiary metallurgy that can be used in the production of special structural steels where high purity is required to influence the quality of the final products. This work deals with the evolution of steel purity comparing vacuum degassing (VD) and electro slag remelting (ESR) technologies in terms of the chemical composition of non-metallic inclusions and their morphology. The present work primarily studies the creep behavior of special structural steel at two different initial material states (VD and ESR steel) tested in the range from 450 to 650 °C. A rather unique plastometric experimental methodology of accelerated creep testing, which consists of a slow plastic deformation of a material under long-term stress at an elevated temperature, was used to study the behavior of the prepared specimens. The results show that, after remelting the steel, there was an increase in micropurity due to a reduction in the average size and, in particular, a reduction in the maximum size of non-metallic inclusions. The results of creep behavior show a particular difference at 600 °C, where ESR steel shows higher relaxation phase stress values as well as higher creep strength factor values compared with VD steel. Full article