Search Results (2,663)

This study assessed the changes in the mechanical and surface properties of the transition zone in multilayered translucent monolithic zirconia subjected to long-term hydrothermal aging. A total of 360 disk-shaped specimens (diameter: 15.0 mm; thickness: 1.2 mm) were prepared using conventional (3Y-TZP in LT; ZL, 4Y-TZP in MT; ZM) and multilayered translucent zirconia (5Y-TZP in MT Multi; ZT, 3Y/5Y-TZP in Prime; ZP) among IPS e.max ZirCAD blocks. Specimens were divided into three groups (n = 30) and aged in the autoclave at 134 °C under 0.2 MPa for 0 h (control group), 5 h (first aged group), and 10 h (second aged group). The mechanical and surface properties of the transition zone in the multilayered translucent zirconia were investigated, followed by statistical analysis (α = 0.05). Before and after aging, ZL (1102.64 ± 41.37 MPa) and ZP (1014.71 ± 139.86 MPa) showed the highest biaxial flexural strength (BFS); ZL showed the highest Weibull modulus (31.46) and characteristic strength (1121.63 MPa); and ZT exhibited the highest nanoindentation hardness (20.40 ± 1.80 GPa) and Young’s modulus (284.90 ± 20.07 GPa). After aging, ZL (116.75 ± 9.80 nm) exhibited the highest surface roughness (Ra); the monoclinic phase contents in ZL and ZP increased; and surface uplifts, microcracks, and irregular defects caused by phase transformation appeared on ZL and ZP surfaces. The 3Y/5Y-TZP transition zone exhibited flexural strength, Vickers hardness, phase distribution changes, and surface microstructure changes similar to those of 3Y-TZP before and after aging; however, the surface roughness was lower than that of 3Y-TZP and higher than those of 4Y-TZP and 5Y-TZP after aging. The mechanical and surface characteristics, excluding BFS and Vickers hardness, were influenced by the yttrium oxide content in each zone and the aging process. Full article

Pectin is a complex and versatile polysaccharide crucial for various industries. It functions as a thickener, gelling agent, emulsifier, and low-calorie food. Its anti-inflammatory and immunomodulatory properties have attracted biomedical interest, while its biodegradability and biocompatibility make it valuable for biomaterial applications. The effectiveness of these applications depends on the quality of pectin extraction procedures. While traditional extraction methods exist, green methodologies and alternative techniques have improved pectin’s physicochemical properties—a significant advantage for industrial applications. Pectin can be extracted from various sources, with its molecular structure and functional groups analyzed through different characterization techniques. Modern green extraction methods include ultrasound-assisted extraction, pulsed ultrasound-assisted extraction, pulsed electric field, moderate electric field mediated extraction, microwave-assisted extraction, subcritical water extraction, enzyme-assisted extraction, ohmic heating-assisted extraction, ultrasound-assisted microwave extraction, ultrasound-assisted ohmic heating extraction, hydrothermal processing, high-pressure processing extraction, and dielectric barrier discharge extraction. This review examines these methods’ advantages and disadvantages, along with their applications and future possibilities; it serves as a comprehensive guide for researchers exploring new pectin-rich sources and green extraction technologies for commercial applications. Full article

This study introduced a novel type of biochar–titanate nanosheet (BC@TNS) composite for the selective adsorption of Pb(II) from wastewater containing various heavy metal ions. The biochar derived from lignin–carbon pyrolysis forms the scaffold, while titanate nanosheets coat it via an alkaline hydrothermal reaction. The synthesis was confirmed through analytic characterizations, revealing a distinctive morphology of TNS nanoflowers consisting of numerous nanosheets incorporated into the BC support. BC@TNS achieved maximum adsorption capacities of 37.89 mg/g for Pb(II), 13.38 mg/g for Cd(II), and 8.47 mg/g for Zn(II), demonstrating its remarkable selectivity for Pb(II). Kinetic studies using Weber–Morris, PFO, and PSO models indicated that Pb(II) adsorption was primarily driven by chemisorption, whereas Cd(II) and Zn(II) adsorption were predominantly governed by physisorption. Isotherm analysis using Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin models revealed that Pb(II) adsorption involved both monolayer and multilayer processes, while Cd(II) and Zn(II) adsorption were primarily monolayer. Detailed insights from scanning electron microscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses further elucidated these mechanisms. The superior selectivity of BC@TNS for Pb(II) was further validated in multicomponent simulated HMs containing 10 co-existing metal ions, maintaining a high Pb(II) adsorption efficiency of 75.68%, highlighting its potential for selective Pb recovery. Moreover, the adsorbent demonstrated excellent regeneration capacity and recyclability. The BC@TNS adsorbent shows great potential for the selective and efficient removal of Pb(II) ions from wastewater, offering a sustainable solution for environmental protection. Full article

Mineral resources, particularly copper, are crucial for the sustained economic growth of developing countries like Kazakhstan. Over the past four decades, the diversity and importance of critical minerals for high technology and environmental applications have increased dramatically. Today, copper is a critical metal due to its importance in electrification. Porphyry deposits are important sources of copper and other critical metals. Conventional exploration methods for mapping alteration zones as indicators of high-potential zones in porphyry deposits are often associated with increased cost, time and environmental concerns. Remote sensing imagery is a cutting-edge technology for the exploration of minerals at low cost and in short timeframes and without environmental damage. Kazakhstan hosts several large porphyry copper deposits, such as Aktogay, Aidarly, Bozshakol and Koksai, and has great potential for the discovery of new resources. However, the potential of these porphyry deposits has not yet been fully discovered using remote sensing technology. In this study, a remote sensing-based mineral exploration approach was developed to delineate hydrothermal alteration zones associated with Aktogay porphyry copper mineralization in eastern Kazakhstan using Landsat-8 and ASTER satellite sensors. A comprehensive suite of image processing techniques was used to analyze the two remote sensing datasets, including specialized band ratios (BRs), principal component analysis (PCA) and the Crosta method. The remote sensing results were validated against field data, including the spatial distribution of geological lineaments and petrographic analysis of the collected rock samples of alteration zones and ore mineralization. The results show that the ASTER data, especially when analyzed with specialized BRs and the Crosta method, effectively identified the main hydrothermal alteration zones, including potassic, propylitic, argillic and iron oxide zones, as indicators of potential zones of ore mineralization. The spatial orientation of these alteration zones with high lineament density supports their association with underlying mineralized zones and the spatial location of high-potential zones. This study highlights the high applicability of the remote sensing-based mineral exploration approach compared to traditional techniques and provides a rapid, cost-effective tool for early-stage exploration of porphyry copper systems in Kazakhstan. The results provide a solid framework for future detailed geological, geochemical and geophysical studies aimed at resource development of the Aktogay porphyry copper mineralization in eastern Kazakhstan. The results of this study underpin the effectiveness of remote sensing data for mineral exploration in geologically complex regions where limited geological information is available and provide a scalable approach for other developing countries worldwide. Full article

Following the abrupt geochemical and geophysical variations that occurred on the island of Vulcano in September 2021, the search for previous multidisciplinary data on decades-long time spans became necessary to contextualize the newly recorded anomalous variations, which represented a serious threat for the local population. Our analyses of ‘vintage’ reports, old documents and analogue seismograms, broaden our understanding of crustal seismic activity. The results unravel the predominant role of Vulcano’s hydrothermal system with respect to tectonic processes in the generation of seismicity in the analyzed sector. Earthquakes were generally located offshore and achieved a maximum M4.6. A 2D strain release map and DBSCAN application highlight seismogenic volumes to the NW, SW and E offshore of the island and trending NNW-SSE inshore, in agreement with structural patterns. Two major volcano unrests in 1985 and 1988 had seismicity mostly confined to the island. In comparison, the longer duration and typology of seismic signals recorded between 2021 and 2022 make this latest episode peculiar in the context of Vulcano’s past seismic activity. Full article

Sugarcane is a popular crop whose cultivation generates a wide range of by-products. The aim was to optimize the hydrothermal extraction of hemicellulose from sugarcane straw using response-surface methods with a two-factor composite design and to assess its functional qualities. Three process parameters were subject to optimization: solid/liquid ratio (1:6–1:18), temperature (143–186 °C), and extraction time (20–60 min). A xylooligosaccharide (XOS)-enriched extract was characterized regarding its chemical composition, molecular weight, and antioxidant and antimicrobial potential. The optimized extraction yield was 24.46 g/100 g of straw with a polymerization degree of 17.40. Both hemicellulose and XOS demonstrated notable antioxidant properties, with antioxidant effects of 73% and 85%, respectively. Regarding skin enzyme activity, hemicellulose inhibited elastase by more than 50%, while XOS showed no significant effect. However, both extracts exhibited collagenase (MMP1) inhibition comparable to the positive control. In terms of production feasibility, the estimated costs were 130.5 EUR/kg for hemicellulose and 272.5 EUR/kg for XOS. Overall, the optimized XOS-enriched sugarcane straw extract demonstrated promising anti-aging, antioxidant, and preservative properties, highlighting its potential for cosmetic applications. Full article

The cost of producing organic crops is increasing. Agricultural wastes can be used as biostimulants to increase plant growth and productivity and reduce the dependence on chemical fertilizers. A pouch assay and a potted greenhouse experiment were conducted to investigate the effect of pyroligneous acid (PA) and sea lettuce (SL) on kale (Brassica oleracea subsp. acephala (DC.) Metzg) seed germination and growth. Although previous studies have demonstrated that these two biostimulants could promote plant germination and growth, there is little research to compare their effects on seed germination and plant growth. The pouch assay showed that PA liquid affected the seed germination rate under different concentrations; the seed germination rate decreased as the concentration of PA liquid increased. However, the effect of seed germination was less pronounced in SL liquids. Kale seeds treated with 0.01% PA showed the best elongation and seedling growth performance. Moreover, the greenhouse experiment indicates that SL liquids significantly (p < 0.05) affected kale growth production, while PA liquid had less difference on kale growth under various concentrations. The 0.25% PA and 1% SL increased the aboveground fresh weight by ca. 26% and 29%, respectively. Also, the phytochemical contents of kale leaves, including phenolics, flavonoids, ascorbate, and protein, were significantly increased with 0.25% PA and 1% SL application. These results suggest that low concentrations of PA are more suitable for seedling root growth in kale and 1% SL had the most significant growth-promoting effect on kale. Hydrothermal carbonization sea lettuce liquid can be used as a good biostimulant for agricultural production to improve kale germination and growth. Full article

Converting agricultural and forestry waste into high-value-added bio-oil via hydrothermal liquefaction (HTL) reduces incineration pollution and alleviates fuel oil shortages. Current research focuses on adjusting HTL parameters like temperature, time, catalyst, and pretreatment. Few studies explore raw material composition and its interactions with bio-oil properties, limiting guidance for future multi-material hydrothermal co-liquefaction. In view of the above problems, the lignocellulosic model in this paper used cellulose, hemicellulose, lignin, and protein as raw materials. At a low hydrothermal temperature (220 °C), the yield and properties of hydrothermal bio-oil were used as indicators to explore the influence of the proportional content of different model components on the interaction in the hydrothermal process through its simple binary blending and multivariate blending. Then, compared with the hydrothermal liquefaction process of cotton stalk, the interaction between components in the hydrothermal process of real lignocellulose was explored. The results demonstrated significant interactions among cellulose, lignin, and hemicellulose in cotton stalks. The relative strength of component interactions was ranked by yield (wt.%) and property modulation as follows: cellulose–lignin (C-L, 6.82%, synergistic enhancement) > cellulose–hemicellulose (C-X, 1.83%, inhibitory effect) > hemicellulose–lignin (X-L, 1.32%, non-significant interaction). Glycine supplementation enhanced bio-oil yields, with the most pronounced effect observed in cellulose–glycine (C-G) systems, where hydrothermal bio-oil yield increased from 2.29% to 4.59%. Aqueous-phase bio-oil exhibited superior high heating values (HHVs), particularly in hemicellulose–glycine (X-G) blends, which achieved the maximum HHV of 29.364 MJ/kg among all groups. Meanwhile, the characterization results of hydrothermal bio-oil under different mixing conditions showed that the proportion of model components largely determined the composition and properties of hydrothermal bio-oil, which can be used as a regulation method for the synthesis of directional chemicals. Cellulose–lignin (C-L) interactions demonstrated the strongest synergistic enhancement, reaching maximum efficacy at a 3:1 mass ratio. This study will deepen the understanding of the composition of lignocellulose raw materials in the hydrothermal process, promote the establishment of a hydrothermal product model of lignocellulose, and improve the yield of bio-oil. Full article

As an important neurotransmitter, the concentration of dopamine (DA) reflects certain physiological conditions and DA-related diseases. Rapid monitoring of DA levels is of great significance in regulating body health. However, regular electrochemical DA sensors suffer from poor sensitivity, low selectivity and interference immunity, as well as a complex preparation process. Herein, we developed an accessible and cost-effective electrochemical sensor with a copper indium selenide (CuInSe2 or CIS)-modified screen-printed carbon electrode for DA discrimination. This DA sensor was developed using a facile one-step hydrothermal method without high-temperature quenching. Benefitting from the inherent merits of CIS and the conversion of Cu²⁺ and Cu⁺ during the catalytic reaction, the sensor attained both excellent sensitivity (2.511 μA·µM⁻¹·cm⁻¹) and selectivity among multiple substances interfering with DA. This work demonstrates the potential to improve the analytical performance of traditional electrochemical sensors. Full article

The sulfide Pb–Zn deposits in the Aksai Chin region of Xinjiang have long been subject to debate regarding their genetic classification due to the unclear origin of the ore-forming components. This study focuses on the Sachakou Pb–Zn deposit, the most representative deposit in the region, and integrates field investigations, petrographic observations, in situ LA-ICP-MS trace element analysis, and in situ S–Pb isotope analysis. The deposit is hosted within the siliceous rock and silicified limestone of the Lower Jurassic Bagongbulansha Formation, with ore bodies controlled by structural and stratigraphic factors. Three mineralization stages have been identified in the Sachakou deposit: a red–brown sphalerite mineralization stage (S1), a light-brown sphalerite stage (S2), and a galena mineralization stage (S3). The trace elements in sphalerite indicate that the mineralization process is unrelated to magmatic activity. The mineralization temperature, determined using a GGIMFis geothermometer, ranges from 294 °C to 121 °C. The δ³⁴S_V-CDT values of sulfides range from −4.93‰ to 1.24‰, suggesting that the Jurassic gypsum layer served as the sulfur source. The lead isotope ratios of ²⁰⁶Pb/²⁰⁴Pb range from 18.308 to 18.395, of ²⁰⁷Pb/²⁰⁴Pb—from 15.669 to 15.731, and of ²⁰⁸Pb/²⁰⁴Pb—from 38.595 to 38.776, indicating that the ore-forming metals were predominantly sourced from the upper crust. Based on geological and geochemical characteristics, the Sachakou Pb–Zn deposit is classified as a sedimentary-hosted epizonogenic hydrothermal deposit. Full article

Siliceous minerals with the property of resistance to diagenetic alteration precipitate during the migration of hydrothermal fluids through strike-slip faults and the interaction of these fluids with host rocks during fault activity. Based on petrological analyses and U-Pb dating of siliceous minerals, the stages of strike-slip faulting of the ultra-deep-burial Ordovician in the Fuman oilfield were subdivided and their evolutionary process was discussed in combination with seismic interpretation. The results reveal the following: (1) the strike-slip faults contain hydrothermal siliceous minerals, including cryptocrystalline silica, crystalline silica, and radial silica. (2) Based on the twelve U-Pb ages of siliceous minerals (ranging from 458 ± 78 Ma to 174 ± 35 Ma) and five U-Pb ages of calcite, the activity of the strike-slip faults was divided into six stages: the Middle Caledonian, Late Caledonian, Early Hercynian, Middle Hercynian, Late Hercynian, and Yanshanian, corresponding to twelve siliceous U-Pb ages ranging from 458 ± 78 Ma to 174 ± 35 Ma, and five calcitic U-Pb ages. The Late Caledonian and Early Hercynian were the main periods of strike-slip fault activity, while the Late Hercynian period marked the final period of the fault system. (3) Later-stage faults inherited and developed from pre-existing faults. Steep linear strike-slip faults formed during the Middle and Late Caledonian movements. During the Late Hercynian and Yanshanian movements, mid-shallow faults, branch faults, and shallow echelon faults developed on the foundation of these linear faults. The methods and results of this study can guide future hydrocarbon exploration in the Fuman oilfield and can be applied to areas with similar tectonic backgrounds. Full article

The hydrothermal carbonization (HTC) of biomass presents a sustainable approach for waste management and production of value-added materials such as hydrochar, which holds promise as an adsorbent and support matrix for bacterial immobilization applied, e.g., for bioremediation processes of sites contaminated with phthalate ester plasticizers such as diethyl phthalate (DEP). In the present study, hydrochar was synthesized from vine shoots (VSs) biomass employing the following parameters during the HTC process: 260 °C for 30 min with a 1:10 (w/v) biomass-to-water ratio. The resulting vine shoots hydrochar (VSs-HC) was characterized for porosity, elemental composition, and structural properties using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Raman spectroscopy. Elemental analysis confirmed the presence of key elements in the VSs structure, elements essential for char formation during the HTC process. The VSs-HC exhibited a macroporous structure (>0.5 μm), facilitating diethyl phthalate (DEP) adsorption, bacterial adhesion, and biofilm formation. Adsorption studies showed that the VSs-HC achieved a 90% removal rate for 4 mM DEP within the first hour of contact. Furthermore, VS-HC was tested as a support matrix for a bacterial consortium (Pseudomonas spp. and Microbacterium sp.) known to degrade DEP. The immobilized bacterial consortium on VSs-HC demonstrated enhanced tolerance to DEP toxicity, degrading 76% of 8 mM DEP within 24 h, compared with 14% by planktonic cultures. This study highlights VSs-HC’s potential as a sustainable and cost-effective material for environmental bioremediation, offering enhanced bacterial cell viability, improved biofilm formation, and efficient plasticizer removal. These findings provide a pathway for mitigating environmental pollution through scalable and low-cost solutions. Full article

Hydrothermal carbonization (HTC) is an efficient method for converting lignocellulosic biomass into biofuels. However, traditional Brønsted acid-catalyzed HTC processes face challenges such as high costs and limited catalytic efficiency. In this study, the catalytic carbonization mechanism was investigated within the temperature range of 180–220 °C by analyzing the evolution of functional groups in hydrochar under lanthanide (III)-catalyzed and non-catalyzed conditions. The results indicate that compared to acid catalysis, lanthanide (III) exhibits superior catalytic performance during the low-temperature HTC of cellulose. At 200 °C, lanthanide (III) accelerates the conversion of cellulose into char microparticles, while at 220 °C, it promotes the complete hydrolysis of cellulose into char microparticles enriched with furan structures. Characterization analyses revealed that lanthanide (III) enhances the formation of HMF (5-hydroxymethylfurfural), suppresses its conversion to LA (levulinic acid), promotes the polymerization of HMF into char microparticles, and indirectly accelerates the hydrolysis of cellulose into oligosaccharides. Full article

This article provides an overview of various microwave-assisted techniques, such as microwave-assisted extraction (MAE), microwave-assisted organic synthesis (MAOS), microwave-assisted pyrolysis (MAP), microwave-assisted hydrothermal treatment (MAHT), microwave-assisted acid hydrolysis (MAAH), microwave-assisted organosolv (MAO), microwave-assisted alkaline hydrolysis (MAA), microwave-assisted enzymatic hydrolysis (MAEH), and microwave-assisted fermentation (MAF). Microwave-assisted biomass pretreatment has emerged as a promising method to improve the efficiency of biomass conversion processes, in particular microwave-assisted pyrolysis (MAP). The focus is on microwave-assisted pyrolysis, detailing its key components, including microwave sources, applicators, feedstock characteristics, absorbers, collection systems, and reactor designs. Based on different studies reported in the literature and a mathematical model, a mechanical design of a microwave oven adapted for pyrolysis is proposed together with a computer-aided design and a finite element analysis. The semi-continuous system is designed for a 40 L capacity and a power of 800 W. The material with which the vessel was designed is suitable for the proposed process. The challenges, opportunities, and future directions of microwave-assisted technologies for the sustainable use of biomass resources are presented. Full article

The connection between crustal anatexis and magmatism is key to understanding the mechanisms that drive the evolution of the continental crust. Isotope geology and lithochemistry are important tools for reconstructing links between these processes, as field evidence of their connection is often obliterated by deformation in high-grade terrains. Thus, this study proposes new insights into the connection between the Mesoarchean regional metamorphism, crustal anatexis, and plutonism in the northern sector of the Carajás Province (i.e., Carajás Domain), in the Amazonian Craton, around 2.89 to 2.83 Ga. The widespread crustal anatexis in the Carajás Domain involved the water-fluxed melting of banded orthogneisses of the Xingu Complex and Xicrim-Cateté Orthogranulite (crystallization age at ca. 3.06–2.93 Ga), producing metatexites and diatexites with stromatic, net, schollen, and schlieren morphologies and coeval syntectonic leucosomes with composition similar to tonalites, trondhjemites, and granites. These leucosomes yielded crystallization ages of 2853 ± 5 Ma (MSWD: 0.61), 2862 ± 13 Ma (MSWD: 0.1), and 2867 ± 7 Ma (MSWD: 1.3). Their lithochemical data are similar to those of several diachronous Mesoarchean granitoids of the Carajás Domain in terms of major, minor, and trace elements and magmatic affinity. In addition, binary log–log vector diagrams (e.g., La vs. Yb; Rb vs. Yb), Sr/Y vs. Y, and Eu/Eu* vs. Yb plots indicate that plagioclase fractionation preceded melt extraction, establishing evolving source-to-sink trends between leucosomes and granites. These results show that the interplay between high-grade metamorphism, crustal anatexis, and magmatism may have shaped the evolution of the Mesoarchean continental crust in the Carajás Province, developing a petrotectonic assemblage associated with collisional orogens. The Mesoarchean geodynamic setting played a critical role in the development of coeval ca. 2.89 Ga magmatic–hydrothermal copper deposits in the Carajás Province, as well as Neoarchean world-class iron oxide–copper–gold deposits linked to post-orogenic extensional rebound. Full article