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23 pages, 4361 KiB  
Article
Novel Visible Light-Driven Ho2InSbO7/Ag3PO4 Photocatalyst for Efficient Oxytetracycline Contaminant Degradation
by Jingfei Luan and Tiannan Zhao
Molecules 2025, 30(15), 3289; https://doi.org/10.3390/molecules30153289 - 6 Aug 2025
Abstract
In this study, a Z-scheme Ho2InSbO7/Ag3PO4 (HAO) heterojunction photocatalyst was successfully fabricated for the first time by ultrasound-assisted solvothermal method. The structural features, compositional components and morphological characteristics of the synthesized materials were thoroughly characterized by [...] Read more.
In this study, a Z-scheme Ho2InSbO7/Ag3PO4 (HAO) heterojunction photocatalyst was successfully fabricated for the first time by ultrasound-assisted solvothermal method. The structural features, compositional components and morphological characteristics of the synthesized materials were thoroughly characterized by a series of techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. A comprehensive array of analytical techniques, including ultraviolet-visible diffuse reflectance absorption spectra, photoluminescence spectroscopy, time-resolved photoluminescence spectroscopy, photocurrent testing, electrochemical impedance spectroscopy, electron paramagnetic resonance, and ultraviolet photoelectron spectroscopy, was employed to systematically investigate the optical, chemical, and photoelectronic properties of the materials. Using oxytetracycline (OTC), a representative tetracycline antibiotic, as the target substrate, the photocatalytic activity of the HAO composite was assessed under visible light irradiation. Comparative analyses demonstrated that the photocatalytic degradation capability of the HAO composite surpassed those of its individual components. Notably, during the degradation process, the application of the HAO composite resulted in an impressive removal efficiency of 99.89% for OTC within a span of 95 min, along with a total organic carbon mineralization rate of 98.35%. This outstanding photocatalytic performance could be ascribed to the efficient Z-scheme electron-hole separation system occurring between Ho2InSbO7 and Ag3PO4. Moreover, the adaptability and stability of the HAO heterojunction were thoroughly validated. Through experiments involving the capture of reactive species and electron paramagnetic resonance analysis, the active species generated by HAO were identified as hydroxyl radicals (•OH), superoxide anions (•O2), and holes (h+). This identification provides valuable insights into the mechanisms and pathways associated with the photodegradation of OTC. In conclusion, this research not only elucidates the potential of HAO as an efficient Z-scheme heterojunction photocatalyst but also marks a significant contribution to the advancement of sustainable remediation strategies for OTC contamination. Full article
(This article belongs to the Special Issue Nanomaterials in Photochemical Devices: Advances and Applications)
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18 pages, 674 KiB  
Article
Oil Extraction Systems Influence the Techno-Functional and Nutritional Properties of Pistachio Processing By-Products
by Rito J. Mendoza-Pérez, Elena Álvarez-Olmedo, Ainhoa Vicente, Felicidad Ronda and Pedro A. Caballero
Foods 2025, 14(15), 2722; https://doi.org/10.3390/foods14152722 - 4 Aug 2025
Viewed by 42
Abstract
Low-commercial-value natural pistachios (broken, closed, or immature) can be revalorised through oil extraction, obtaining a high-quality oil and partially defatted flour as by-product. This study evaluated the techno-functional and nutritional properties of the flours obtained by hydraulic press (HP) and single-screw press (SSP) [...] Read more.
Low-commercial-value natural pistachios (broken, closed, or immature) can be revalorised through oil extraction, obtaining a high-quality oil and partially defatted flour as by-product. This study evaluated the techno-functional and nutritional properties of the flours obtained by hydraulic press (HP) and single-screw press (SSP) systems, combined with pretreatment at 25 °C and 60 °C. The extraction method significantly influenced flour’s characteristics, underscoring the need to tailor processing conditions to the specific technological requirements of each food application. HP-derived flours presented lighter colour, greater tocopherol content, and higher water absorption capacity (up to 2.75 g/g), suggesting preservation of hydrophilic proteins. SSP-derived flours showed higher concentration of protein (44 g/100 g), fibre (12 g/100 g), and minerals, and improved emulsifying properties, enhancing their suitability for emulsified products. Pretreatment at 25 °C enhanced functional properties such as swelling power (~7.0 g/g) and water absorption index (~5.7 g/g). The SSP system achieved the highest oil extraction yield, with no significant effect of pretreatment temperature. The oils extracted showed high levels of unsaturated fatty acids, particularly oleic acid (~48% of ω-9), highlighting their nutritional and industrial value. The findings support the valorisation of pistachio oil extraction by-products as functional food ingredients, offering a promising strategy for reducing food waste and promoting circular economy approaches in the agri-food sector. Full article
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17 pages, 7820 KiB  
Article
Visible Light Activation of Anatase TiO2 Achieved by beta-Carotene Sensitization on Earth’s Surface
by Xiao Ge, Hongrui Ding, Tong Liu, Yifei Du and Anhuai Lu
Catalysts 2025, 15(8), 739; https://doi.org/10.3390/catal15080739 - 1 Aug 2025
Viewed by 178
Abstract
Photocatalytic redox processes significantly contribute to shaping Earth’s surface environment. Semiconductor minerals exhibiting favorable photocatalytic properties are ubiquitous on rock and soil surfaces. However, the sunlight-responsive characteristics and functions of TiO2, an excellent photocatalytic material, within natural systems remain incompletely understood, [...] Read more.
Photocatalytic redox processes significantly contribute to shaping Earth’s surface environment. Semiconductor minerals exhibiting favorable photocatalytic properties are ubiquitous on rock and soil surfaces. However, the sunlight-responsive characteristics and functions of TiO2, an excellent photocatalytic material, within natural systems remain incompletely understood, largely due to its wide bandgap limiting solar radiation absorption. This study analyzed surface coating samples, determining their elemental composition, distribution, and mineralogy. The analysis revealed enrichment of anatase TiO2 and β-carotene. Informed by these observations, laboratory simulations were designed to investigate the synergistic effect of β-carotene on the sunlight-responsive behavior of anatase. Results demonstrate that β-carotene-sensitized anatase exhibited a 64.4% to 66.1% increase in photocurrent compared to pure anatase. β-carotene sensitization significantly enhanced anatase’s electrochemical activity, promoting rapid electron transfer. Furthermore, it improved interfacial properties and acted as a photosensitizer, boosting photo-response characteristics. The sensitized anatase displayed a distinct absorption peak within the 425–550 nm range, with visible light absorption increasing by approximately 17.75%. This study elucidates the synergistic mechanism enhancing the sunlight response between anatase and β-carotene in natural systems and its broader environmental implications, providing new insights for research on photocatalytic redox processes within Earth’s critical zone. Full article
(This article belongs to the Special Issue Advancements in Photocatalysis for Environmental Applications)
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18 pages, 6409 KiB  
Article
MICP-Treated Coral Aggregate and Its Application in Marine Concrete
by Rui Xu, Baiyu Li, Xiaokang Liu, Ben Peng, Guanghua Lu, Changsheng Yue and Lei Zhang
Materials 2025, 18(15), 3619; https://doi.org/10.3390/ma18153619 - 1 Aug 2025
Viewed by 217
Abstract
In marine engineering applications, substituting conventional crushed stone coarse aggregates with coral aggregates offers dual advantages: reduced terrestrial quarrying operations and minimized construction material transportation costs. However, the inherent characteristics of coral aggregates—low bulk density, high porosity, and elevated water absorption capacity—adversely influence [...] Read more.
In marine engineering applications, substituting conventional crushed stone coarse aggregates with coral aggregates offers dual advantages: reduced terrestrial quarrying operations and minimized construction material transportation costs. However, the inherent characteristics of coral aggregates—low bulk density, high porosity, and elevated water absorption capacity—adversely influence concrete workability and mechanical performance. To address these limitations, this investigation employed microbial-induced carbonate precipitation (MICP) for aggregate modification. The experimental design systematically evaluated the impacts of substrate concentration (1 mol/L) and mineralization period (14 days) on three critical parameters, mass gain percentage, water absorption reduction, and apparent density enhancement, across distinct particle size fractions (4.75–9.5 mm, 9.5–20 mm) and density classifications. Subsequent application trials assessed the performance of MICP-treated aggregates in marine concrete formulations. Results indicated that under a substrate concentration of 1 mol/L and mineralization period of 14 days, lightweight coral aggregates and coral aggregates within the 4.75–9.5 mm size fraction exhibited favorable modification effects. Specifically, their mass gain rates reached 11.75% and 11.22%, respectively, while their water absorption rates decreased by 32.22% and 34.75%, respectively. Apparent density increased from initial values of 1764 kg/m3 and 1930 kg/m3 to 2050 kg/m3 and 2207 kg/m3. Concrete mixtures incorporating modified aggregates exhibited enhanced workability and strength improvement at all curing ages. The 28-day compressive strengths reached 62.1 MPa (11.69% increment), 46.2 MPa (6.94% increment), and 60.1 MPa (14.91% increment) for the 4.75–9.5 mm, 9.5–20 mm, and continuous grading groups, respectively, compared to untreated counterparts. Full article
(This article belongs to the Section Construction and Building Materials)
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22 pages, 1916 KiB  
Article
Freeze-Dried Probiotic Fermented Camel Milk Enriched with Ajwa Date Pulp: Evaluation of Functional Properties, Probiotic Viability, and In Vitro Antidiabetic and Anticancer Activities
by Sally S. Sakr and Hassan Barakat
Foods 2025, 14(15), 2698; https://doi.org/10.3390/foods14152698 - 31 Jul 2025
Viewed by 306
Abstract
Noncommunicable diseases (NCDs) like diabetes and cancer drive demand for therapeutic functional foods. This study developed freeze-dried fermented camel milk (FCM) with Ajwa date pulp (ADP), evaluating its physical and functional properties, probiotic survival, and potential benefits for diabetes and cancer. To achieve [...] Read more.
Noncommunicable diseases (NCDs) like diabetes and cancer drive demand for therapeutic functional foods. This study developed freeze-dried fermented camel milk (FCM) with Ajwa date pulp (ADP), evaluating its physical and functional properties, probiotic survival, and potential benefits for diabetes and cancer. To achieve this target, six FCM formulations were prepared using ABT-5 starter culture (containing Lactobacillus acidophilus, Bifidobacterium bifidum, and Streptococcus thermophilus) with or without Lacticaseibacillus rhamnosus B-1937 and ADP (12% or 15%). The samples were freeze-dried, and their functional properties, such as water activity, dispersibility, water absorption capacity, water absorption index, water solubility index, insolubility index, and sedimentation, were assessed. Reconstitution properties such as density, flowability, air content, porosity, loose bulk density, packed bulk density, particle density, carrier index, Hausner ratio, porosity, and density were examined. In addition, color and probiotic survivability under simulated gastrointestinal conditions were analyzed. Also, antidiabetic potential was assessed via α-amylase and α-glucosidase inhibition assays, while cytotoxicity was evaluated using the MTT assay on Caco-2 cells. The results show that ADP supplementation significantly improved dispersibility (up to 72.73% in FCM15D+L). These improvements are attributed to changes in particle size distribution and increased carbohydrate and mineral content, which facilitate powder rehydration and reduce clumping. All FCM variants demonstrated low water activity (0.196–0.226), indicating good potential for shelf stability. The reconstitution properties revealed that FCM powders with ADP had higher bulk and packed densities but lower particle density and porosity than controls. Including ADP reduced interstitial air and increased occluded air within the powders, which may minimize oxidation risks and improve packaging efficiency. ADP incorporation resulted in a significant decrease in lightness (L*) and increases in redness (a*) and yellowness (b*), with greater pigment and phenolic content at higher ADP levels. These changes reflect the natural colorants and browning reactions associated with ADP, leading to a more intense and visually distinct product. Probiotic survivability was higher in ADP-fortified samples, with L. acidophilus and B. bifidum showing resilience in intestinal conditions. The FCM15D+L formulation exhibited potent antidiabetic effects, with IC50 values of 111.43 μg mL−1 for α-amylase and 77.21 μg mL−1 for α-glucosidase activities, though lower than control FCM (8.37 and 10.74 μg mL−1, respectively). Cytotoxicity against Caco-2 cells was most potent in non-ADP samples (IC50: 82.22 μg mL−1 for FCM), suggesting ADP and L. rhamnosus may reduce antiproliferative effects due to proteolytic activity. In conclusion, the study demonstrates that ADP-enriched FCM is a promising functional food with enhanced probiotic viability, antidiabetic potential, and desirable physical properties. This work highlights the potential of camel milk and date synergies in combating some NCDs in vitro, suggesting potential for functional food application. Full article
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36 pages, 1502 KiB  
Review
A Critical Review on the Role of Lactic Acid Bacteria in Sourdough Nutritional Quality: Mechanisms, Potential, and Challenges
by Youssef Mimoune Reffai and Taoufiq Fechtali
Appl. Microbiol. 2025, 5(3), 74; https://doi.org/10.3390/applmicrobiol5030074 - 29 Jul 2025
Viewed by 298
Abstract
Sourdough fermentation, driven by the biochemical activity of lactic acid bacteria (LAB), presents a scientifically promising approach to addressing nutritional limitations in cereal-based staples. This review critically examines both the underlying mechanisms by which LAB enhance the nutritional profile of sourdough and the [...] Read more.
Sourdough fermentation, driven by the biochemical activity of lactic acid bacteria (LAB), presents a scientifically promising approach to addressing nutritional limitations in cereal-based staples. This review critically examines both the underlying mechanisms by which LAB enhance the nutritional profile of sourdough and the translational challenges in realizing these benefits. Key improvements explored include enhanced mineral bioavailability (e.g., up to 90% phytate reduction), improved protein digestibility, an attenuated glycemic response (GI ≈ 54 vs. ≈75 for conventional bread), and the generation of bioactive compounds. While in vitro and animal studies extensively demonstrate LAB’s potential to reshape nutrient profiles (e.g., phytate hydrolysis improving iron absorption, proteolysis releasing bioactive peptides), translating these effects into consistent human health outcomes proves complex. Significant challenges hinder this transition from laboratory to diet, including the limited bioavailability of LAB-derived metabolites, high strain variability, and sensitivity to fermentation conditions. Furthermore, interactions with the food matrix and host-specific factors, such as gut microbiota composition, contribute to inconsistent findings. This review highlights methodological gaps, particularly reliance on in vitro or animal models, and the lack of long-term, effective human trials. Although LAB hold significant promise for nutritional improvements in sourdough, translating these findings to validated human benefits necessitates continued efforts in mechanism-driven strain optimization, the standardization of fermentation processes, and rigorous human studies. Full article
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23 pages, 1907 KiB  
Article
Lacmellea oblongata and Other Undervalued Amazonian Fruits as Functional, Antioxidant, and Antimicrobial Matrices
by Elena Coyago-Cruz, Gabriela Méndez, Ruth Escobar-Quiñonez, Marco Cerna and Jorge Heredia-Moya
Antioxidants 2025, 14(8), 924; https://doi.org/10.3390/antiox14080924 - 29 Jul 2025
Viewed by 303
Abstract
The Amazon represents a key source of food biodiversity and is home to native fruits with high nutritional and functional potential, many of which remain largely unstudied. This research aimed to evaluate the presence of bioactive compounds, as well as the antioxidant and [...] Read more.
The Amazon represents a key source of food biodiversity and is home to native fruits with high nutritional and functional potential, many of which remain largely unstudied. This research aimed to evaluate the presence of bioactive compounds, as well as the antioxidant and antimicrobial activity of Miconia crenata, Grias neuberthii, Lacmellea oblongata, Pourouma cecprofiilia, and Annona edulis. Physical and chemical parameters, mineral content (atomic absorption), vitamin C, organic acid, carotenoids, chlorophylls, and phenols (liquid chromatography), antioxidant activity (ABTS, DPPH), and antimicrobial activity (against Candida albicans, Candida tropicalis, Escherichia coli, Staphylococcus aureus, and Streptococcus mutans) were determined. High concentrations of calcium, syringic acid, and antioxidant activity were found in the fruits of Miconia crenata; malic and caffeic acids in Grias neuberthii; citric acid, naringenin, and antioxidant activity in Lactuca oblongata; potassium, chlorogenic acid, and ferulic acid in Pourouma cecropiifolia; and tartaric acid and gallic acid in Annona edulis. Additionally, low antimicrobial activity was observed in M. crenata against E. coli (2.7 mg/mL), G. neuberthii against S. aureus (10.3 mg/mL), and L. oblongata against S. mutans (10.4 mg/mL), C. albicans (20.8 mg/mL), and C. tropicalis (20.8 mg/mL). The results confirm that these Amazonian fruits are a relevant source of functional bioactive compounds, highlighting their potential for use in the food, pharmaceutical, and biotechnology sectors. Full article
(This article belongs to the Special Issue Polyphenolic Antioxidants in Food)
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15 pages, 4581 KiB  
Article
Co-Culture with Two Soil Fungal Strains Enhances Growth and Secondary Metabolite Biosynthesis in Cordyceps takaomontana
by Junyi Chen, Minghao Ding, Donglan He, Dengxian Zhang, Ming Wang, Yulan Xiang and Tianya Liu
J. Fungi 2025, 11(8), 559; https://doi.org/10.3390/jof11080559 - 29 Jul 2025
Viewed by 352
Abstract
Cordyceps takaomontana is a medicinal fungus with significant pharmacological value, but how soil microbes promote its growth remains unclear. We established a solid-state co-culture system involving C. takaomontana synnemata and its native soil fungi of Fusarium paeoniae and Bjerkandera minispora. Both F. [...] Read more.
Cordyceps takaomontana is a medicinal fungus with significant pharmacological value, but how soil microbes promote its growth remains unclear. We established a solid-state co-culture system involving C. takaomontana synnemata and its native soil fungi of Fusarium paeoniae and Bjerkandera minispora. Both F. paeoniae and B. minispora significantly promoted synnematal growth and enhanced antioxidant enzyme activities. Total triterpenoid content increased substantially. F. paeoniae markedly elevated levels of ergosterol peroxide, whereas B. minispora boosted accumulation of L-arabinose, ergotamine, and euphol. Metabolomics revealed that both fungi activated key metabolic pathways (including ABC transporters, mineral absorption, and protein digestion/absorption). F. paeoniae uniquely upregulated phenylalanine metabolism. This work elucidates the metabolic mechanisms underlying growth promotion of C. takaomontana mediated by F. paeoniae and B. minispora as well as deciphers potential pharmacologically active metabolites. These findings provide a foundation for strategically improving artificial cultivation and developing functional microbial inoculants. Full article
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22 pages, 5507 KiB  
Article
Experimental Study on the Pore Structure Evolution of Sandstone Under Brine Erosion
by Kang Peng, Tao Wu, Kun Luo, Song Luo, Jiaqi Zhou and Yuanmin Wang
Materials 2025, 18(15), 3500; https://doi.org/10.3390/ma18153500 - 25 Jul 2025
Viewed by 271
Abstract
The mechanical properties of sandstone, a common building material, are influenced by a variety of factors. In the coastal areas of China, groundwater has gradually become salinized into brine, which inevitably alters the original microstructure of rocks and affects the stability of underground [...] Read more.
The mechanical properties of sandstone, a common building material, are influenced by a variety of factors. In the coastal areas of China, groundwater has gradually become salinized into brine, which inevitably alters the original microstructure of rocks and affects the stability of underground structures. To clarify the evolution of the rock microstructure under brine erosion, this study used NMR technology to investigate the pore evolution characteristics of red sandstone under brine erosion. The experimental results show that the water absorption capacity of sandstone is influenced by the solution environment, with the lowest absorption rate occurring in regard to brine. The pores in red sandstone undergo significant changes after brine erosion. Factors such as the composition of the brine and soaking time affect sandstone porosity, with transformations of mini-pores and meso-pores leading to changes in porosity. In addition, XRD tests were carried out on the soaked red sandstone samples to analyze the changes in the main mineral components of the sandstone after brine erosion. Full article
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28 pages, 115558 KiB  
Article
A Knowledge-Based Strategy for Interpretation of SWIR Hyperspectral Images of Rocks
by Frank J. A. van Ruitenbeek, Wim H. Bakker, Harald M. A. van der Werff, Christoph A. Hecker, Kim A. A. Hein and Wijnand van Eijndthoven
Remote Sens. 2025, 17(15), 2555; https://doi.org/10.3390/rs17152555 - 23 Jul 2025
Viewed by 258
Abstract
Strategies to interpret short-wave infrared hyperspectral images of rocks involve the application of analysis and classification steps that guide the extraction of geological and mineralogical information with the aim of creating mineral maps. Pre-existing strategies often rely on the use of statistical measures [...] Read more.
Strategies to interpret short-wave infrared hyperspectral images of rocks involve the application of analysis and classification steps that guide the extraction of geological and mineralogical information with the aim of creating mineral maps. Pre-existing strategies often rely on the use of statistical measures between reference and image spectra that are scene dependent. Therefore, classification thresholds based on statistical measures to create mineral maps are also scene dependent. This is problematic because thresholds must be adjusted between images to produce mineral maps of the same accuracy. We developed an innovative, knowledge-based strategy to perform mineralogical analyses and create classifications that overcome this problem by using physics-based wavelength positions of absorption features that are invariant between scenes as the main sources of mineral information. The strategy to interpret short-wave infrared hyperspectral images of rocks is implemented using the open source Hyperspectral Python package (HypPy) and demonstrated on a series of hyperspectral images of hydrothermally altered rock samples. The results show how expert knowledge can be embedded into a standardized processing chain to develop reproducible mineral maps without relying on statistical matching criteria. Full article
(This article belongs to the Section Remote Sensing in Geology, Geomorphology and Hydrology)
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36 pages, 8968 KiB  
Article
Stabilization of High-Volume Circulating Fluidized Bed Fly Ash Composite Gravels via Gypsum-Enhanced Pressurized Flue Gas Heat Curing
by Nuo Xu, Rentuoya Sa, Yuqing He, Jun Guo, Yiheng Chen, Nana Wang, Yuchuan Feng and Suxia Ma
Materials 2025, 18(15), 3436; https://doi.org/10.3390/ma18153436 - 22 Jul 2025
Viewed by 197
Abstract
Circulating fluidized bed fly ash (CFBFA) stockpiles release alkaline dust, high-pH leachate, and secondary CO2/SO2—an environmental burden that exceeds 240 Mt yr−1 in China alone. Yet, barely 25% is recycled, because the high f-CaO/SO3 contents destabilize conventional [...] Read more.
Circulating fluidized bed fly ash (CFBFA) stockpiles release alkaline dust, high-pH leachate, and secondary CO2/SO2—an environmental burden that exceeds 240 Mt yr−1 in China alone. Yet, barely 25% is recycled, because the high f-CaO/SO3 contents destabilize conventional cementitious products. Here, we presents a pressurized flue gas heat curing (FHC) route to bridge this scientific deficit, converting up to 85 wt% CFBFA into structural lightweight gravel. The gypsum dosage was optimized, and a 1:16 (gypsum/CFBFA) ratio delivered the best compromise between early ettringite nucleation and CO2-uptake capacity, yielding the highest overall quality. The optimal mix reaches 9.13 MPa 28-day crushing strength, 4.27% in situ CO2 uptake, 1.75 g cm−3 bulk density, and 3.59% water absorption. Multi-technique analyses (SEM, XRD, FTIR, TG-DTG, and MIP) show that FHC rapidly consumes expansive phases, suppresses undesirable granular-ettringite formation, and produces a dense calcite/needle-AFt skeleton. The FHC-treated CFBFA composite gravel demonstrates 30.43% higher crushing strength than JTG/TF20-2015 standards, accompanied by a water absorption rate 28.2% lower than recent studies. Its superior strength and durability highlight its potential as a low-carbon lightweight aggregate for structural engineering. A life-cycle inventory gives a cradle-to-gate energy demand of 1128 MJ t−1 and a process GWP of 226 kg CO2-eq t−1. Consequently, higher point-source emissions paired with immediate mineral sequestration translate into a low overall climate footprint and eliminate the need for CFBFA landfilling. Full article
(This article belongs to the Section Advanced Composites)
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10 pages, 404 KiB  
Article
Flotation Separation of Chalcopyrite and Molybdenite by Eco-Friendly Microorganism Depressant Bacillus tropicus
by Guanghua Ai, Guosheng Xiao and Bo Feng
Minerals 2025, 15(7), 762; https://doi.org/10.3390/min15070762 - 21 Jul 2025
Viewed by 252
Abstract
In this study, Bacillus tropicus (BT), a non-toxic and eco-friendly microorganism, was employed to substitute traditional inorganic depressants in the flotation separation of copper-molybdenum sulfides. Single mineral flotation tests were performed to examine BT’s impact on the flotation behavior of molybdenite and chalcopyrite. [...] Read more.
In this study, Bacillus tropicus (BT), a non-toxic and eco-friendly microorganism, was employed to substitute traditional inorganic depressants in the flotation separation of copper-molybdenum sulfides. Single mineral flotation tests were performed to examine BT’s impact on the flotation behavior of molybdenite and chalcopyrite. The results indicated that excessive BT inhibited the flotation of both minerals, reducing their recoveries below 40%. At a BT dosage of 2.5 kg/t and pH 9.0, chalcopyrite recovery was 74.10%, while molybdenite recovery was 20.47%, achieving an effective separation of the two minerals. BT’s adsorption mechanism on molybdenite and chalcopyrite was analyzed through contact angle tests, thermogravimetric analysis, and Fourier transform infrared spectroscopy. These analyses revealed that increased BT absorption on molybdenite enhanced its surface hydrophilicity. This research offers a novel perspective on utilizing microorganisms as efficient flotation reagents. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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18 pages, 2570 KiB  
Article
Applicability of Visible–Near-Infrared Spectroscopy to Predicting Water Retention in Japanese Forest Soils
by Rando Sekiguchi, Tatsuya Tsurita, Masahiro Kobayashi and Akihiro Imaya
Forests 2025, 16(7), 1182; https://doi.org/10.3390/f16071182 - 17 Jul 2025
Viewed by 262
Abstract
This study assessed the applicability of visible–near-infrared (vis-NIR) spectroscopy to predicting the water retention characteristics of forest soils in Japan, which vary widely owing to the presence of volcanic ash. Soil samples were collected from 34 sites, and the volumetric water content was [...] Read more.
This study assessed the applicability of visible–near-infrared (vis-NIR) spectroscopy to predicting the water retention characteristics of forest soils in Japan, which vary widely owing to the presence of volcanic ash. Soil samples were collected from 34 sites, and the volumetric water content was measured at eight levels of matric suction. Spectral data were processed by using the second derivative of the absorbance, and regression models were developed by using explainable boosting machine (EBM), which is an interpretable machine learning method. Although the prediction accuracy was limited owing to the small sample size and soil heterogeneity, EBM performed better under saturated conditions (R2 = 0.30), which suggests that vis-NIR spectroscopy can capture water-related features, especially under wet conditions. Importance analysis consistently selected wavelengths that were associated with organic matter and hydrated clay minerals. The important wavelengths clearly shifted from free-water bands in wet soils to mineral-related absorption bands in dry soils. These findings highlight the potential of coupling vis-NIR spectroscopy with interpretable models like EBM for estimating the hydraulic properties of forest soils. Improved accuracy is expected with larger datasets and stratified models by soil type, which can facilitate more efficient soil monitoring in forests. Full article
(This article belongs to the Section Forest Soil)
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33 pages, 167102 KiB  
Article
Influence of Mineralogical and Petrographic Properties on the Mechanical Behavior of Granitic and Mafic Rocks
by Muhammad Faisal Waqar, Songfeng Guo, Shengwen Qi, Malik Aoun Murtaza Karim, Khan Zada, Izhar Ahmed and Yanjun Shang
Minerals 2025, 15(7), 747; https://doi.org/10.3390/min15070747 - 17 Jul 2025
Viewed by 363
Abstract
This study investigates the impact of mineralogical and petrographic characteristics on the mechanical behavior of granitic and mafic rocks from the Shuangjiangkou (Sichuan Province) and Damiao complexes (Hebei Province) in China. The research methodology combined petrographic investigation, comprising optical microscopy and Scanning Electron [...] Read more.
This study investigates the impact of mineralogical and petrographic characteristics on the mechanical behavior of granitic and mafic rocks from the Shuangjiangkou (Sichuan Province) and Damiao complexes (Hebei Province) in China. The research methodology combined petrographic investigation, comprising optical microscopy and Scanning Electron Microscopy–Energy-Dispersive X-ray Spectroscopy (SEM-EDS) methods, with methodical geotechnical characterization to establish quantitative relationships between mineralogical composition and engineering properties. The petrographic studies revealed three lithologic groups: fine-to-medium-grained Shuangjiangkou granite (45%–60% feldspar, 27%–35% quartz, 10%–15% mica), plagioclase-rich anorthosite (more than 90% of plagioclase), and intermediate mangerite (40%–50% of plagioclase, 25%–35% of perthite). The uniaxial compressive strength tests showed great variations: granite (127.53 ± 15.07 MPa), anorthosite (167.81 ± 23.45 MPa), and mangerite (205.12 ± 23.87 MPa). Physical properties demonstrated inverse correlations between mechanical strength and both water absorption (granite: 0.25%–0.42%; anorthosite: 0.07%–0.44%; mangerite: 0.10%–0.25%) and apparent porosity (granite: 0.75%–0.92%; anorthosite: 0.20%–1.20%; mangerite: 0.29%–0.69%), with positive correlations to specific gravity (granite: 1.88–3.03; anorthosite: 2.67–2.90; mangerite: 2.43–2.99). Critical petrographic features controlling mechanical behavior include the following: (1) mica content in granite creating anisotropic properties, (2) extensive feldspar alteration through sericitization increasing microporosity and reducing intergranular cohesion, (3) plagioclase micro-fracturing and alteration to clinozoisite–sericite assemblages in anorthosite creating weakness networks, and (4) mangerite’s superior composition of >95% hard minerals with minimal sheet mineral content and limited alteration. Failure mode analysis indicated distinct patterns: granite experiencing shear-dominated failure (30–45° diagonal planes), anorthosite demonstrated tensile fracturing with vertical splitting, and mangerite showed catastrophic brittle failure with extensive fracture networks. These findings provide quantitative frameworks that relate petrographic features to engineering behavior, offering valuable insights for rock mass assessment and engineering design in similar crystalline rock terrains. Full article
(This article belongs to the Special Issue Characterization of Geological Material at Nano- and Micro-scales)
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19 pages, 2720 KiB  
Article
Application of Ice Slurry as a Phase Change Material in Mine Air Cooling System—A Case Study
by Łukasz Mika, Karol Sztekler and Ewelina Radomska
Energies 2025, 18(14), 3782; https://doi.org/10.3390/en18143782 - 17 Jul 2025
Viewed by 303
Abstract
Fossil fuels, including coal, are a basis of energy systems in many countries worldwide. However, coal mining is associated with several difficulties, which include high temperatures within the coal mining area. It causes a need for cooling for safety reasons and also for [...] Read more.
Fossil fuels, including coal, are a basis of energy systems in many countries worldwide. However, coal mining is associated with several difficulties, which include high temperatures within the coal mining area. It causes a need for cooling for safety reasons and also for the comfort of miners’ work. Typical cooling systems in mines are based on central systems, in which chilled water is generated in the compressor or absorption coolers on the ground and transported via pipelines to the air coolers in the areas of mining. The progressive mining operation causes a gradual increase in the distance between chilled water generators and air coolers, causing a decrease in the efficiency of the entire system and insufficient cooling capacity. As a result, it is necessary to increase the diameter of the chilled water pipelines and increase the cooling capacity of the chillers, which is associated with additional investment and technical problems. One solution to this problem may be the use of so-called ice slurry instead of chilled water in the existing mine cooling system. This article presents the cooling system, located in the mine LW Bogdanka S.A., based on ice slurry. The structure of the system and its key parameters are presented. The results show that switching from cooling water to ice slurry allowed the cooling capacity of the entire system to increase by 50% while maintaining the existing piping. This demonstrates the very high potential for the use of ice slurry, not only in mines, but wherever further increases in piping diameters to maintain the required cooling capacity are not possible or cost-effective. Full article
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