Search Results (259)

As global demand for rare earth elements (REEs) increases, maintaining the production and supply chain is critical. Technologies capable of being used in the field and in situ in the subsurface for rapid REE detection and quantification facilitates the efficient mining of known resources and exploration of new and unconventional resources. Laser-induced breakdown spectroscopy (LIBS) is a promising technique for rapid elemental analysis both in the laboratory and in the field. Multiple articles have been published evaluating LIBS for detection and quantification of REEs; however, REEs in their natural deposits have not been adequately studied. In this work, detection and quantification of two REEs, La and Nd, have been studied in both synthetic and natural mineral matrices at concentrations relevant to REE extraction. Measurements were performed on REE-containing rock and coal samples (natural and synthetic) utilizing different LIBS instruments and techniques, specifically a commercial benchtop instrument, a custom benchtop instrument (single- and double-pulse modes), and a custom LIBS probe currently being developed for in situ, subsurface, borehole wall detection and quantification of REEs. Plasma expansion, emission intensity, detection limits, and double-pulse signal enhancement were studied. The limits of detection (LOD) were found to be 10/14 ppm for La and 15/25 ppm for Nd in simulated coal/rock matrices in single-pulse mode. Signal enhancement of 3.5 to 6-fold was obtained with double-pulse mode as compared to single-pulse operation. Full article

The growing global demand for energy necessitates the efficient utilization of unconventional petroleum resources, particularly heavy oil reserves. However, extracting, transporting, and processing these resources remain challenging due to their low mobility, low API gravity, and significant concentrations of resins, asphaltenes, heteroatoms, and metals. In recent years, various in situ upgrading techniques have been explored to enhance heavy oil quality, with catalytic aquathermolysis emerging as a promising approach. The effectiveness of this process largely depends on the development of cost-effective, environmentally friendly catalysts. This study investigates the upgrading performance of water-soluble ammonium alum, (NH₄)Al(SO₄)₂·12H₂O, for an extra-heavy oil sample from the Zarafshan Depression, located along the Tajikistan–Uzbekistan border. Comprehensive analyses demonstrate that the catalyst facilitates the breakdown of heavy oil components, particularly resins and asphaltenes, into lighter fractions. As a result, oil viscosity was significantly reduced by 94%, while sulfur content decreased from 896 ppm to 312 ppm. Furthermore, thermogravimetric (TG-DTG) analysis, coupled with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), revealed that the thermal decomposition of ammonium alum produces catalytically active Al₂O₃ nanoparticles. These findings suggest that ammonium alum is a highly effective water-soluble pre-catalyst for hydrothermal upgrading, offering a viable and sustainable solution for the development of extra-heavy oil fields. Full article

This study evaluates the performance of nine satellite and model-based daily surface soil moisture products, encompassing sixteen algorithm versions across mainland China to support sustainable land and water management. The assessment utilizes 2018 in situ measurements from over 2400 stations in China’s Automatic Soil Moisture Monitoring Network. All products were standardized to a 0.25° × 0.25° grid in the WGS-84 coordinate system through reprojection and resampling for consistent comparison. Daily averaged station observations were matched to product pixels using a 10 km radius buffer, with the mean station value as the reference for each time series after rigorous quality control. Results reveal distinct performance rankings, with SMAP-based products, particularly the SMAP_IB descending orbit variant, achieving the lowest unbiased root mean square deviation (ubRMSD) and highest correlation with in situ data. Blended products like ESA CCI and NOAA SMOPS, alongside reanalysis datasets such as ERA5 and MERRA2, outperformed SMOS and China’s FY3 products. The SoMo.ml product showed the broadest spatial coverage and strong temporal consistency, while FY3-based products showed limitations in spatial reliability and seasonal dynamics capture. These findings provide critical insights for selecting appropriate soil moisture datasets to enhance sustainable agricultural practices, optimize water resource allocation, monitor ecosystem resilience, and support climate adaptation strategies, therefore advancing sustainable development across diverse geographical regions in China. Full article

Earth observation data serve as a fundamental resource in Earth system science. The rapid advancement of remote sensing and in situ measurement technologies has led to the generation of massive volumes of data, accompanied by a growing body of geographic textual information. Efficient and accurate classification and management of these geographic texts has become a critical challenge in the field. However, the effectiveness of traditional classification approaches is hindered by several issues, including data sparsity, class imbalance, semantic ambiguity, and the prevalence of domain-specific terminology. To address these limitations and enable the intelligent management of geographic information, this study proposes an efficient geographic text classification framework based on large language models (LLMs), tailored to the unique semantic and structural characteristics of geographic data. Specifically, LLM-based data augmentation strategies are employed to mitigate the scarcity of labeled data and class imbalance. A semantic vector database is utilized to filter the label space prior to inference, enhancing the model’s adaptability to diverse geographic terms. Furthermore, few-shot prompt learning guides LLMs in understanding domain-specific language, while an output alignment mechanism improves classification stability for complex descriptions. This approach offers a scalable solution for the automated semantic classification of geographic text for unlocking the potential of ever-expanding geospatial big data, thereby advancing intelligent information processing and knowledge discovery in the geospatial domain. Full article

To promote environmentally sustainable remediation and resource recovery from ion-adsorption rare earth tailings (IRET), this study comprehensively investigated the previously isolated strain REO-01 by examining its sulfate-reducing performance, Cd(II) immobilization potential, and physiological and biochemical responses under varying environmental conditions. Strain REO-01 was identified as a Gram-negative facultative anaerobe with strong sulfate-reducing activity and effective Cd(II) immobilization capacity. During a 96 h incubation period, the strain entered the exponential growth phase within 36 h, after which the OD₆₀₀ values plateaued. Concurrently, the culture pH increased from 6.83 to 7.5, and the oxidation-reduction potential (ORP) declined to approximately −300 mV. Cd(II) concentrations decreased from 0.2 mM to 3.33 μM, corresponding to a removal efficiency exceeding 95%, while sulfate concentrations declined from 1500 mg/L to 640 mg/L, with a maximum reduction efficiency of 66.16%. The strain showed optimal growth at 25–40 °C and near-neutral pH (6–7), whereas elevated Cd(II) concentrations (≥0.2 mM) significantly inhibited cell growth. A sulfate concentration of 1500 mg/L was found to be optimal for cellular activity. Among the tested carbon sources, sodium lactate at 4.67 g/L yielded the most favorable results, reducing ORP to −325 mV, increasing pH to 7.6, and lowering Cd(II) and sulfate concentrations to 3.33 μM and 510 mg/L, respectively. These findings highlight the strong potential of strain REO-01 for simultaneous sulfate reduction and Cd(II) remediation, supporting its application in the in situ bioremediation and resource utilization of rare earth tailings. Full article

A technique has been proposed and experimentally tested for measuring the hydrogen concentration in an inert atmosphere within a closed system. This method utilizes a metal-oxide-semiconductor field-effect capacity-type (MOSFEC) sensor under harsh conditions such as exposure to inert gases, pressure fluctuations, and varying temperatures. The measurement is performed during the thermal decomposition of metal hydrides in a liquid sodium environment. The developed measurement technique for determining hydrogen concentration released from metal hydride samples in a system with a closed gas path is cost-effective compared to standardized, resource-intensive open-volume flow measurement methods. The use of the developed MOSFEC sensor technique allows for rapid and efficient investigation of the in situ real-time dynamics of gas release from various metal hydride materials differing in their hydrogen content within a small closed volume. Additionally, this approach enables precise determination of the specific gas release temperatures. Full article

Fused filament fabrication (FFF) is a 3D printing technology that has been successfully demonstrated aboard the International Space Station (ISS), proving its suitability for space applications. In this study, we aimed to apply FFF to the 3D printing of recycled space beverage packaging, made of LDPE and a PET-Aluminum-LDPE (PAL) trilaminate. To minimize material waste and optimize the experimental process, we first conducted numerical simulations of additive manufacturing. Using Digimat-AM 2021.1 software, we analyzed residual stresses and warpage in an LDPE/PAL composite with a 10 wt% filler content, processed through the FFF technique. Three key printing parameters, including printing speed and infill pattern, were varied across different levels to assess their impact. Once the optimal combination of parameters for minimizing residual stresses and warpage was identified, we proceeded with the experimental phase, printing objects of increasing complexity to validate the correlation between numerical predictions and the 3D-printed models. The successful fabrication of all geometries under optimized conditions confirmed the numerical predictions, particularly the reduction in warpage and residual stress, validating the material’s viability for additive manufacturing. These findings support the potential application of the LDPE/PAL composite for in situ resource utilization strategies in long-term space missions. Full article

Seawater transparency provides critical insight into marine ecological dynamics and serves as a foundational indicator for fisheries management, environmental monitoring, and coastal resource development. Among various indicators, the Secchi disk depth (SDD) is widely used to quantify seawater transparency in marine environmental monitoring. This study develops a remote sensing inversion model for estimating the SDD in the coastal waters of Qinhuangdao, utilizing Sentinel-3 OLCI satellite imagery and in situ measurements. The model is based on the CIE hue angle and demonstrates high accuracy (R² = 0.93, MAPE = 7.88%, RMSE = 0.25 m), outperforming traditional single-band, band-ratio, and multi-band approaches. Using the proposed model, we analyzed the monthly and interannual variations of SDD in Qinhuangdao’s coastal waters from 2018 to 2024. The results reveal a clear seasonal pattern, with SDD values generally increasing and then decreasing throughout the year, primarily driven by the East Asian monsoon and other natural factors. Notably, the average annual SDD in 2018 was significantly lower than in subsequent years (2019–2024), which is closely associated with comprehensive water management and pollution reduction initiatives in the Bohai Sea region. These findings highlight marked improvements in the coastal marine environment and underscore the benefits of China’s ecological civilization strategy, particularly the principle that “lucid waters and lush mountains are invaluable assets.” Full article

This review examines advancements in Mars habitation technologies, emphasizing Earth-based analog missions and closed-loop life support systems critical for long-duration human presence on the Red Planet. The paper categorizes major simulation projects—including Biosphere 2, Yuegong 1 (Lunar Palace 1), SAM, MaMBA, and CHAPEA—and analyzes their contributions to habitat design, psychological resilience, and environmental control. Technological domains such as in situ resource utilization (ISRU), habitat automation, and extraterrestrial health care are evaluated with respect to current limitations and future scalability. Additionally, the paper explores regulatory, economic, and international cooperation aspects, highlighting their significance in enabling sustainable settlement. By integrating empirical data from terrestrial experiments and recent space initiatives, this review offers a comprehensive assessment of readiness and gaps in Mars habitation strategies. Full article

Oil shale, an unconventional oil and gas resource, can generate the required hydrocarbons through high-temperature pyrolysis. In situ conversion extraction technology utilizes downhole heaters to directly inject high-temperature heat into the oil shale layer to achieve the effect of oil and gas recovery. For the metal material components of the combustion heaters, the uneven temperature fields experienced during the start of operations, processing, and end of operations can lead to fatigue conditions, such as high-temperature creep, micro-damage, and micro-deformation due to thermal effects. To prevent the occurrence of the aforementioned issues, it is necessary to conduct fatigue life analysis of downhole combustion heaters. By combining actual combustion heater operation experiments with finite element simulation, this paper analyzes the impact of temperature, structure, and stress amplitude on the fatigue life of heaters. The results indicate that the fatigue life of the heaters is most significantly influenced by the metal gaskets, and the higher the exhaust gas temperature, the lower the fatigue life of the heater. Heating operations significantly reduce the fatigue life of the heater, while cooling operations have almost no effect on the fatigue life. Circular-pore metal gaskets have a higher fatigue life than those with a square hole shape. Considering only the thickness of the metal gaskets, the thicker the gasket, the higher the fatigue life. Stress amplitude has the most significant impact on the fatigue life of the heater; when the stress amplitude is doubled, the metal gaskets quickly undergo fatigue damage. Full article

The determination of the dynamic angle of repose (DAR) of lunar regolith simulants is essential for modeling material behavior during in situ resource utilization (ISRU) processes and lunar surface operations. This study presents a methodology and dedicated test rig employing digital image processing to measure DAR for seven lunar regolith simulants, representing both Mare and Highland regions. Experiments were conducted under terrestrial gravity at rotational drum speeds of 2, 5, and 10 RPM, with standardized material fill and image capture procedures. For each simulant, lower, higher, and total DAR values were recorded, indicating complex dependencies on particle size distribution, mineralogy, and rotational speed. These measurements provide a critical dataset for numerical model calibration and the simulation of regolith handling systems under lunar conditions. The findings emphasize the necessity of selecting appropriate DAR parameters based on regolith type and operational scale to ensure accurate predictions of granular flow behavior in extraterrestrial environments. Full article

Porous carbons for CO₂ capture were synthesized from a sulfur-rich bituminous coal via a one-step method concurrently including carbonization and KOH activation. The activation parameters were controlled by varying KOH/coal mass ratios (1:1, 2:1, and 3:1) and temperatures (700 °C, 800 °C, and 900 °C) to optimize their CO₂ capture performance. The surface physicochemical structural properties of these porous carbons were characterized by applying a Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, and Raman spectroscopy. The results show that the S_BET of sample SCC-800-3 is as high as 2209 m²/g, the CO₂ adsorption capacity of sample SCC-700-2 at normal temperature and pressure reaches 3.46 mmol/g, and the CO₂/N₂ selectivity of sample SCC-700-1 reaches 24. The synergistic effect of moderate activation conditions ensures optimal pore evolution without compromising sulfur species retention. Furthermore, these porous carbons also demonstrate excellent cycling stability and thermal stability. The fitting of the adsorption isotherm model for all samples were further conducted. Adsorption isotherm modeling demonstrated superior fitting accuracy with the dual-parameter Freundlich and tri-parametric Redlich–Peterson formulations across all samples, indicating that the CO₂ capture by high-sulfur coal-based porous carbons belongs to multilayer adsorption and the carbon surface is heterogeneous. The CO₂ adsorption on porous carbon exhibits spontaneous, exothermic behavior according to the thermodynamic data. These findings confirm the great potential of high-sulfur coal-based porous carbons on the capture of CO₂. The presenting research provides a strategy that leverages the synergistic effect of in situ sulfur doping and milder activation conditions, achieving the high-efficiency utilization of high-sulfur coal resources and developing low-cost CO₂ capture materials. Full article

The sustainable valorization of lignocellulosic biomass into high-value platform chemicals presents a crucial pathway for reducing reliance on fossil resources. Gamma (γ)-valerolactone (GVL) has gained recognition as a versatile bio-derived compound with broad applications in renewable energy systems and green chemical synthesis. While conventional GVL production strategies from carbohydrate biomass typically depend on noble metal catalysts paired with high-pressure hydrogen gas, these approaches face substantial technical barriers including catalyst costs, hydrogen storage requirements, and operational safety concerns in large-scale applications. This work develops an innovative catalytic system utilizing earth-abundant iron for in situ hydrogen generation through water splitting, integrated with Raney Ni as the hydrogenation catalyst. The designed two-stage process enables direct conversion of cellulose—first through acid hydrolysis to levulinic acid (LA) followed by catalytic hydrogenation to GVL without intermediate purification. Through systematic parameter optimization, a remarkable 61.9% overall GVL yield from cellulose feedstock was achieved. Furthermore, the methodology’s versatility was demonstrated through wheat straw conversion experiments, yielding 24.6% GVL. This integrated methodology explores a technically feasible pathway for direct cellulose-to-GVL conversion utilizing abundant water as the hydrogen source, effectively overcoming the critical limitations associated with conventional hydrogenation technologies regarding hydrogen infrastructure and process safety. Full article

With the advancement of space exploration, the development of sustainable construction technologies has become essential for the establishment of enduring extraterrestrial habitats. In Situ Resource Utilization (ISRU) assumes a pivotal role by facilitating the use of indigenous materials on celestial bodies such as the Moon and Mars, thereby reducing reliance on terrestrial resources. This review provides a comprehensive analysis of the latest ISRU-based construction technologies, with particular emphasis on biocementation techniques. It further examines the challenges associated with the application of biocementation in extreme space environments and outlines prospective research directions. The continued advancement of ISRU technologies through interdisciplinary collaboration remains crucial for the realization of viable and cost-efficient extraterrestrial construction solutions. Full article

Today, open-source Cloud Computing platforms are valuable for geospatial image analysis while the combination of the Google Earth Engine (GEE) platform and new satellite launches greatly facilitate the monitoring of national-scale lake Water Quality (WQ). The main aim of this research is to assess the transferability and performance of published general, natural-only and artificial-only lake WQ models (Chl-a, Secchi Disk Depth-SDD- and Total Phosphorus-TP) across Greece’s WFD (Water Framework Directive) lake sampling network. We utilized Landsat (7 ETM +/8 OLI) and Sentinel 2 surface reflectance (SR) data embedded in GEE, while subjected to different atmospheric correction (AC) methods. Subsequently, Carlson’s Trophic State Index (TSI) was calculated based on both in situ and modelled WQ values. Initially, WQ models employed both DOS1-corrected (Dark Object Subtraction 1; manually applied) and GEE-retrieved respective SR data from the year 2018. Double WQ values per lake station were inserted in a linear regression analysis to harmonize the AC differences, separately for Landsat and Sentinel 2 data. Yielded linear equations were accompanied by strong associations (R² ranging from 0.68 to 0.98) while modelled and GEE-modelled TSI values were further validated based on reference in situ WQ datasets from the years 2019 and 2020. The values of the basic statistical error metrics indicated firstly the increased assessment’s accuracy of GEE-modelled over modelled TSIs and then the superiority of Landsat over Sentinel 2 data. In this way, the hereby adopted methodology was evolved into an efficient lake management tool by providing managers the means for integrated sustainable water resources management while contributing to saving valuable image pre-processing time. Full article