Search Results (1,451)

In the absence of appropriate tools and a knowledge base for exploring high-grade metamorphic terrains, felsic gneiss complexes at granulite facies have long been considered barren and have remained undermapped and understudied. This was the case of the Bondy gneiss complex in the southwestern Grenville Province of Canada which consists of 1.39–1.35 Ga volcanic and plutonic rocks metamorphosed under granulite facies conditions at 1.19 Ga. Iron oxide–apatite and Cu-Ag-Au mineral occurrences occur among gneisses rich in biotite, cordierite, garnet, K-feldspar, orthopyroxene and/or sillimanite-rich gneisses, plagioclase-cordierite-orthopyroxene white gneisses, magnetite-garnet-rich gneisses, garnetites, hyperaluminous sillimanite-pyrite-quartz gneisses, phlogopite-sillimanite gneisses, and tourmalinites. Petrological and geochemical studies indicate that the precursors of these gneisses are altered volcanic and volcaniclastic rocks with attributes of pre-metamorphic Na, Ca-Fe, K-Fe, K, chloritic, argillic, phyllic, advanced argillic and skarn alteration. The nature of these hydrothermal rocks and the ore deposit model that best represents them are further investigated herein through lithogeochemistry. The lithofacies mineralized in Cu (±Au, Ag, Zn) are distinguished by the presence of garnet, magnetite and zircon, and exhibit pronounced enrichment in Fe, Mg, HREE and Zr relative to the least-altered rocks. In discrimination diagrams, the metamorphosed mineral system is demonstrated to exhibit the diagnostic attributes of, and is interpreted as, a metasomatic iron and alkali-calcic (MIAC) mineral system with iron oxide–apatite (IOA) and iron oxide copper–gold (IOCG) mineralization that evolves toward an epithermal cap. This contribution demonstrates that alteration facies diagnostic of MIAC systems and their IOCG and IOA mineralization remain diagnostic even after high-grade metamorphism. Exploration strategies can thus use the lithogeochemical footprint and the distribution and types of alteration facies observed as pathfinders for the facies-specific deposit types of MIAC systems. Full article

The development of mining operations in high-altitude regions is associated with a number of geomechanical challenges caused by increased rock fracturing, adverse climatic conditions, and high seismic activity. These issues are particularly relevant for the exploitation of gold ore deposits, where the stability of open-pit slopes directly affects both safety and extraction efficiency. The aim of this study is to develop and practically substantiate a comprehensive approach to assessing and ensuring slope stability, using the Bozymchak gold ore deposit—located in a high-altitude and seismically active zone—as a case study. The research involves the laboratory testing of rock samples obtained from engineering–geological boreholes, field shear tests on rock prisms, laser scanning of pit slopes, and digital geomechanical modeling. The developed calculation schemes take into account the structural features of the rock mass, geological conditions, and the design contours of the pit. In addition, special bench excavation technologies with pre-shear slotting and automated GeoMoS monitoring are implemented for real-time slope condition tracking. The results of the study make it possible to reliably determine the strength characteristics of the rocks under natural conditions, identify critical zones of potential collapse, and develop recommendations for optimizing slope parameters and mining technologies. The implemented approach ensures the required level of safety. Full article

Glycated hemoglobin (HbA1c) is an important biomarker applied for the diagnosis, evaluation, and management of diabetes; therefore, its accurate determination is crucial. In this study, an innovative nanoplatform was developed, integrating carbon nanotubes (CNTs) with enhanced hydrophilicity achieved through cyclodextrin (CD) functionalization, and combined with gold nanoparticles (AuNPs) electrochemically deposited onto a screen-printed carbon electrode. The nanomaterials significantly improved the analytical performance of the sensor due to their increased surface area and high electrical conductivity. This nanoplatform was employed as a substrate for the covalent attachment of thiolated ferrocene-labeled HbA1c specific aptamer through Au-S binding. The electrochemical signal of ferrocene was covered by a stronger oxidation peak of Fe²⁺ from the HbA1c structure, leading to the elaboration of a nanostructured aptasensor capable of the direct detection of HbA1c. The electrochemical aptasensor presented a very wide linear range (0.688–11.5%), an acceptable limit of detection (0.098%), and good selectivity and stability, being successfully applied on real samples. This miniaturized, simple, easy-to-use, and fast-responding aptasensor, requiring only a small sample volume, can be considered as a promising candidate for the efficient on-site determination of HbA1c. Full article

100 nm thick TiO₂/TiN bilayers with varying thickness ratios were deposited via reactive sputtering of a Ti target in controlled oxygen and nitrogen atmospheres. Post-deposition annealing in air at 600 °C was performed to induce nitrogen diffusion through the oxygen-deficient TiO₂ layer. The resulting changes in morphology and chemical environment were investigated in detail using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectroscopy. Detailed TEM and XPS analyses have confirmed nitrogen diffusion across the TiO₂ layer, with surface nitrogen concentration and the ratio of interstitial to substitutional nitrogen dependent on the TiO₂/TiN mass ratio. Optical studies demonstrated modifications in optical constants and a reduction of the effective bandgap from 3.2 eV to 2.6 eV due to new energy states introduced by nitrogen doping. Changes in surface free energy induced by nitrogen incorporation showed a correlation to nitrogen doping sites on the surface, which had positive effects on overall photocatalytic activity. Photocatalytic activity, assessed through methylene blue degradation, showed enhancement attributed to nitrogen doping. Additionally, deposition of a 5 nm gold layer on the annealed sample enabled investigation of synergistic effects between nitrogen doping and gold incorporation, resulting in further improved photocatalytic performance. These findings establish the TiO₂/TiN bilayer as a versatile platform for supporting thin gold films with enhanced photocatalytic properties. Full article

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these giant deposits remain poorly understood. Mafic microgranular enclaves (MMEs), mafic dikes, and multiple porphyries have been documented in the Saindak mining area. This work examines both the ore-rich and non-ore intrusions in the Saindak porphyry Cu-Au deposit, using methods like molybdenite Re-Os dating, U-Pb zircon ages, Hf isotopes, and bulk-rock geochemical data. Geochronological results indicate that ore-fertile and barren porphyries yield ages of 22.15 ± 0.22 Ma and 22.21 ± 0.33 Ma, respectively. Both MMEs and mafic dikes have zircons with nearly identical ²⁰⁶Pb/²³⁸U weighted mean ages (21.21 ± 0.18 Ma and 21.21 ± 0.16 Ma, respectively), corresponding to the age of the host rock. Geochemical and Sr–Nd–Hf isotopic evidence indicates that the Saindak adakites were generated by the subduction of the Arabian oceanic lithosphere under the Eurasian plate, rather than through continental collision. The adakites were mainly formed by the partial melting of a metasomatized mantle wedge, induced by fluids from the dehydrating subducting slab, with minor input from subducted sediments and later crust–mantle interactions during magma ascent. We conclude that shallow subduction of the Arabian plate during the Oligocene–Miocene may have increased the flow of subducted fluids into the sub-arc mantle source of the Chagai arc. This process may have facilitated the widespread deposition of porphyry copper and copper–gold mineralization in the region. Full article

Mining and analyzing information from multiple sources—such as geophysics and geochemistry—is a key aspect of big data-driven mineral prediction. Clustering, which groups large datasets based on distance metrics, is an essential method in multidimensional data analysis. The Two-Step Clustering (TSC) approach offers advantages by handling both categorical and continuous variables and automatically determining the optimal number of clusters. In this study, we applied the TSC method to mineral prediction in the northeastern margin of the Jiaolai Basin by: (i) converting residual gravity and magnetic anomalies into categorical variables using Ward clustering; and (ii) transforming 13 stream sediment elements into independent continuous variables through factor analysis. The results showed that clustering is sensitive to categorical variables and performs better with fewer categories. When variables share similar distribution characteristics, consistency between geophysical discretization and geochemical boundaries also influences clustering results. In this study, the (3 × 4) and (4 × 4) combinations yielded optimal clustering results. Cluster 3 was identified as a favorable zone for gold deposits due to its moderate gravity, low magnetism, and the enrichment in F1 (Ni–Cu–Zn), F2 (W–Mo–Bi), and F3 (As–Sb), indicating a multi-stage, shallow, hydrothermal mineralization process. This study demonstrates the effectiveness of combining Ward clustering for variable transformation with TSC for the integrated analysis of categorical and numerical data, confirming its value in multi-source data research and its potential for further application. Full article

The Tuztaşı low-sulfidation epithermal Au–Ag deposit (Biga Peninsula, Türkiye) records a multi-stage hydrothermal history that can be interpreted through the trace and rare-earth-element (REE) chemistry of quartz. High-precision LA-ICP-MS analyses of five representative quartz samples (23 ablation spots; 10 analytically robust) reveal two fluid stages. Early fluids were cold, dilute meteoric waters (δ¹⁸O₍H₂O₎ ≈ −6.8 to +0.7‰), whereas later fluids circulated deeper, interacted with felsic basement rocks, and evolved in composition. Mineralized quartz displays marked enrichment in As (raw mean = 2854 ± 6821 ppm; filtered mean = 70 ± 93 ppm; one spot 16,775 ppm), K (498 ± 179 ppm), and Sb (57.8 ± 113 ppm), coupled with low Ti/Al (<0.005) and elevated Ge/Si (0.14–0.65 µmol mol⁻¹). Chondrite-normalized REE patterns show pronounced but variable LREE enrichment ((La/Yb)_n ≤ 45.3; ΣLREE/ΣHREE up to 10.8) and strongly positive Eu anomalies (δEu ≤ 9.3) with slightly negative Ce anomalies (δCe ≈ 0.29); negligible Ce–Eu covariance (r² ≈ 0.05) indicates discrete redox pulses. These signatures indicate chemically evolved, reducing fluids conducive to Au–Ag deposition. By contrast, barren quartz is characterized by lower pathfinder-element contents, less fractionated REE profiles, higher Ti/Al, and weaker Eu anomalies. A composite exploration toolkit emerges: As > 700 ppm, As/Sb > 25, Ti/Al < 0.005, Ge/Si > 0.15 µmol mol⁻¹, and δEu ≫ 1 reliably identify ore-bearing zones when integrated with δ¹⁸O data and fluid-inclusion microthermometry from earlier studies on the same vein system. This study provides one of the first systematic applications of integrated trace-element and REE analysis of quartz to a Turkish low-sulfidation epithermal system, offering an applicable model for vectoring mineralization in analogous settings worldwide. Full article

The increasing demand for critical raw materials, such as antimony—a semimetal with strategic relevance in fire-retardant applications, electronic components, and national security—has made the identification of European sources essential for the European Union’s strategic autonomy. Remote sensing offers a valuable tool for detecting alteration minerals associated with subsurface gold and antimony deposits that reach the surface. However, the coarse spatial resolution of the most freely available satellite data remains a limiting factor. The PlanetScope satellite constellation presents a promising low-cost alternative for the academic community, providing 3 m spatial resolution and eight spectral bands. In this study, we evaluated PlanetScope’s capacity to detect Fe³⁺-bearing iron oxides—key indicators of hydrothermal alteration—by applying targeted band ratios (BRs) in northern Portugal. A comparative analysis was conducted to validate its performance using established BRs from Sentinel-2, ASTER, and Landsat 9. The results were assessed through relative comparison methods, enabling both quantitative and qualitative evaluation of the spectral similarity among sensors. Spatial patterns were analyzed, and points of interest were identified and subsequently validated through fieldwork. Our findings demonstrate that PlanetScope is a viable option for mineral exploration applications, capable of detecting iron oxide anomalies associated with alteration zones while offering finer spatial detail than most freely accessible satellites. Full article

Background: Periodontitis is a chronic inflammatory disease characterized by the destruction of periodontal tissues due to biofilm deposits and altered host immune response. Non-surgical periodontal therapy (NSPT) still represents the gold standard for treatment; however, its effectiveness in deep periodontal pockets is limited. Probiotics seem to modulate both oral microbiota and inflammatory response and have been proposed as an adjunctive therapy to NSPT. Methods: An electronic search was conducted on PubMed, Scopus, Medline, and Google Scholar to identify English randomized controlled trials (RCTs) evaluating probiotics as adjunctive treatments to NSPT. Studies were selected based on inclusion and exclusion criteria, and clinical outcomes such as probing depth (PD) and clinical attachment level (CAL) were extracted and analyzed. Results: Seven RCTs met the inclusion criteria. These studies showed significant improvements in PD and CAL when probiotics were used, specifically with Lactobacillus and Bifidobacterium species. However, outcomes ranged depending on the strain, dosage, and delivery method. Conclusions: Probiotics may be used as an adjunct treatment to NSPT; however, further studies are needed to define valid clinical guidelines. Full article

This study investigates the effects of substrate flexibility and metal deposition methods on piezoelectric-enhanced Surface-Enhanced Raman Scattering (SERS) in metal-deposited ZnO nanorod (NR) nanocomposites (NCPs). ZnO NRs were grown on both rigid (ITO–glass) and flexible (ITO-PET) substrates, followed by gold (Au) deposition by pulsed-laser-induced photolysis (PLIP) or silver (Ag) deposition by thermal evaporation. Structural analysis revealed that ZnO NRs on flexible substrates exhibited smaller diameters (60–80 nm vs. 80–100 nm on glass), a higher density, and diverse orientations that enhanced piezoelectric responsiveness. Optical characterization showed distinct localized surface plasmon resonance (LSPR) peaks at 420 nm for Ag and 525 nm for Au systems. SERS measurements demonstrated that Ag-ZnO NCPs achieved superior detection limits (10⁻⁹ M R6G) with enhancement factors of 10⁸–10⁹, while Au-ZnO NCPs reached 10⁻⁸ M detection limits. Mechanical bending of flexible substrates induced dramatic signal enhancement (50–100-fold for Au-ZnO/PET and 2–3-fold for Ag-ZnO/PET), directly confirming piezoelectric enhancement mechanisms. This work establishes quantitative structure–property relationships in piezoelectric-enhanced SERS and provides design principles for high-performance flexible sensors. Full article

The Mazenod Lake region of the southern Great Bear Magmatic Zone (GBMZ) of the Northwest Territories, Canada, comprises the north-central portion of the Faber volcano-plutonic belt. Widespread and abundant surface exposure of several coalescing hydrothermal systems enables this paper to document, without ambiguity, the relationships between geology, structure, alteration, and mineralization in this well exposed iron-oxide–copper–gold (IOCG) mineral system. Mazenod geology comprises rhyodacite to basaltic-andesite ignimbrite sheets with interlayered volcaniclastic sedimentary rocks dominated by fine-grained laminated tuff sequences. Much of the intermediate to mafic nature of volcanic rocks is masked by low-intensity but pervasive metasomatism. The region is affected by a series of coalescing magmatic–hydrothermal systems that host the Sue–Dianne magnetite–hematite IOCG deposit and several related showings including magnetite, skarn, and iron oxide apatite (IOA) styles of alteration ± mineralization. The mid to upper levels of these systems are exposed at surface, with underlying batholith, pluton and stocks exposed along the periphery, as well as locally within volcanic rocks associated with more intense alteration and mineralization. Widespread alteration includes potassic and sodic metasomatism, and silicification with structurally controlled giant quartz complexes. Localized tourmaline, skarn, magnetite–actinolite, and iron-oxide alteration occur within structural breccias, and where most intense formed the Sue–Dianne Cu-Ag-Au diatreme-like breccia deposit. Magmatism, volcanism, hydrothermal alteration, and mineralization formed during a negative tectonic inversion within the Wopmay Orogen. This generated a series of oblique offset rifted basins with continental style arc magmatism and extensional structures unique to GBMZ rifting. All significant hydrothermal centers in the Mazenod region occur along and at the intersections of crustal faults either unique to or put under tension during the GBMZ inversion. Full article

The Shabaosi gold field is located in the western Mohe Basin, part of the northern Great Xing’an Range, NE China, and contains multiple gold deposits. However, the sources of the ore-forming materials, the fluid evolution, and the genesis of these gold deposits have been disputed, especially regarding the classification of these deposits as either epithermal or orogenic gold systems. Based on detailed field geological investigations and previous research, we conducted systematic research on the Shabaosi, Sanshierzhan, Laogou, and Balifang gold deposits using fluid inclusion and H-O-S-Pb isotope data, with the aim of constraining the fluid properties, sources, and mineralization processes. Fluid inclusion analyses reveal diverse types, including vapor-rich, vapor–liquid, CO₂-bearing, CO₂-rich, and pure CO₂. Additionally, only a very limited number of daughter mineral-bearing fluid inclusions have been observed exclusively in the Laogou gold deposit. During the early stages, the peak temperature primarily ranged from 240 °C to 280 °C, with salinity concentrations between 6 and 8 wt% NaCl equiv., representing a medium–low temperature, low salinity, and a heterogeneous CO₂-CH₄-H₂O-NaCl system. With the influx of meteoric water, the fluids evolved gradually into a simple NaCl-H₂O system with low temperatures (160–200 °C) and salinities (4–6 wt%). The main mineralization stage exhibited peak temperatures of 220–260 °C and salinities of 5–8 wt% NaCl equiv., corresponding to an estimated formation depth of 1.4–3.3 km. The δD_V-SMOW values (−138.3‰ to −97.0‰) and δ¹⁸O_V-SMOW values (−7.1‰ to 16.2‰) indicate that the magmatic–hydrothermal fluids were progressively diluted by meteoric water during mineralization. The sulfur isotopic compositions (δ³⁴S = −0.9‰ to 1.8‰) and lead isotopic ratios (²⁰⁸Pb/²⁰⁴Pb = 38.398–38.579, ²⁰⁷Pb/²⁰⁴Pb = 15.571–15.636, and ²⁰⁶Pb/²⁰⁴Pb = 18.386–18.477) demonstrate that the gold predominantly originated from deep magmatic systems, with potential crustal contamination. Comparative analyses indicate that the Shabaosi gold field should be classified as a epizonal orogenic gold system, which shows distinct differences from epithermal gold deposits and corresponds to the extensional tectonic setting during the late-stage evolution of the Mongol–Okhotsk orogenic belt. Full article

This work presents a high-performance novel photodetector based on two-dimensional boron nitride (BN) nanosheets functionalized with gold nanoparticles (Au NPs), offering ultra-broadband photoresponse from 0.25 to 5.9 μm. Operating in both photovoltaic and photoconductive modes, the device features rapid response times (<0.5 ms), high responsivity (up to 1015 mA/W at 250 nm and 2.5 V bias), and thermal stability up to 100 °C. The synthesis process involved CO₂ laser exfoliation of hexagonal boron nitride, followed by gold NP deposition via RF sputtering and thermal annealing. Structural and compositional analyses confirmed the formation of a three-dimensional network of atomically thin BN nanosheets decorated with uniformly distributed gold nanoparticles. This architecture facilitates plasmon-enhanced absorption and efficient charge separation via heterojunction interfaces, significantly boosting photocurrent generation across the deep ultraviolet (DUV), visible, near-infrared (NIR), and mid-infrared (MIR) spectral regions. First-principles calculations support the observed broadband response, confirming bandgap narrowing induced by defects in h-BN and functionalization by gold nanoparticles. The device’s self-driven operation, wide spectral response, and durability under elevated temperatures underscore its strong potential for next-generation broadband, self-powered, and wearable sensing and optoelectronic applications. Full article

The development of stable, non-toxic electrolytes is essential for electrodepositing large-area coatings. This study presents a novel low-cyanide electrolyte, offering a viable alternative to traditional cyanide-based solutions for the electroplating of gold–copper alloys. Compared to conventional baths, the new formulation offers safer handling and environmental compatibility without compromising performance. Electrolyte compositions were optimized via cyclic voltammetry, and coatings were deposited using direct current, pulse current, and reverse pulse current methods. The novel low-cyanide electrolyte system achieved a 99.1% reduction in cyanide use compared with the commercial formulation. Coatings produced with pulse current and reverse pulse current deposition exhibited structural, morphological, and mechanical properties comparable to those obtained from cyanide-based electrolytes. Overall, the low-cyanide electrolyte represents a safer, high-performance alternative to traditional cyanide-based systems. Full article

Mineralogical variability exerts a profound influence on the flotation performance of Platinum Group Metal (PGM) ores, particularly those from the Platreef deposit, where complex associations and textures influence recovery, grade, and kinetics. This study integrates the Mode of Occurrence (MOC) and mineral associations into a modified Kelsall flotation kinetics model, optimized using a Particle Swarm Optimization (PSO) algorithm, to improve prediction accuracy. Batch flotation tests were conducted on eight samples from two lithologies—Pegmatoidal Feldspathic Pyroxenite (P-FPX) and Feldspathic Pyroxenite (FPX)—with mineralogical characterization performed using MLA, QEMSCAN, and XRD. PGMs in liberated (L) and sulfide-associated (SL) forms accounted for up to 90.6% (FPX1), exhibiting high fast-floating fractions (θ_f = 0.77–0.84) and fast flotation rate constants (K_f = 1.45–1.78 min⁻¹). In contrast, PGMs locked in silicates (G class) showed suppressed kinetics (K_f < 0.09 min⁻¹, K_s anomalies up to 8.67 min⁻¹) and were associated with lower recovery (P-FPX3 = 83.25%) and increased model error (P-FPX4 = 57.3). FPX lithologies achieved the highest cumulative recovery (FPX4 = 90.35%) and the best concentrate grades (FPX3 = 116.5 g/t at 1 min), while P-FPX1 had the highest gold content (10.45%) and peak recovery (94.37%). Grade-recovery profiles showed steep declines after 7 min, particularly in slow-floating types (e.g., P-FPX2, FPX2), with fast-floating lithologies stabilizing above 85% recovery at 20 min. The model yielded R² values above 0.97 across all samples. This validates the predictive power of MOC-integrated flotation kinetics for complex PGM ores and supports its application in geometallurgical plant design. Model limitations in capturing complex locked ore textures (SAG, G classes) highlight the need for reclassification based on floatability indices and further integration of machine learning methods. Full article