Shallow Levels Research Articles

UV-random lasing of ZnO films decorated with Au nanoparticles and modification of lasing threshold by surface plasmon effect

Threshold energy values for random lasing action are determined from spectral and temporal coherence studies in systems with incoherent feedback. Zinc oxide films with and without their surface having been decorated with gold nanoparticles stand simultaneously for the active and the scattering medium, whereas pumping is carried out by a conventional laser system operating at the picosecond pulse regime. The influence of the gold surface on both the threshold and the intensity of the optical response is investigated. Whenever localized surface plasmon resonances are supported, electron mobility at the gold boundaries facilitates reinsertion of the trapped electrons into shallow defect levels to the conduction band. In consequence the characteristic visible emission from ZnO (green) due to transitions from such levels is suppressed, thus lowering the pumping threshold prerequisite for random lasing emission. The tunning of the random lasing threshold is achievable by means of control on the morphology and size effects of the gold nanoparticles. This contribution shows that specific post-thermal treatments could be exploited to adjust the lasing properties of novel metal decorated systems, which already feature random lasing before decoration. In principle, the extension of the decoration should be rather small to minimize response losses due to screening side effects of the metal phase, which obtrudes direct contact of the pumping photons with the semiconductor system.

Enhanced bifunctional photocatalytic CO2 reduction and H2 evolution utilizing Cu-doped ZnIn2S4 nanosheets via cation exchange reaction

In this study, Cu-doped ZnIn2S4 nanosheets were synthesized through cation exchange reactions to enhance the dual-functional photocatalytic processes of CO2 reduction and hydrogen evolution. The optimized Cu doping levels in Cu-ZIS samples significantly improved the photocatalytic performance, resulting in enhanced H2-evolution rates and increased selectivity in CO2 reduction, particularly in the production of C2H4 and CO. Characterization techniques confirmed the successful integration of Cu into the ZIS lattice, thereby improving charge transfer and separation within the material. Mechanistic studies indicated that Cu doping enhanced light absorption, charge transfer efficiency, and introduced shallow energy levels, consequently reducing charge carrier recombination and improving overall catalytic performance. These findings highlight the substantial potential of Cu-doped ZnIn2S4 nanosheets for sustainable dual-functional applications in solar energy conversion.

Multi-year climate memory in shallow lake water levels

Landscape hydrologic memory of meteorological cycles can have an important impact on catchment hydrological responses by propagating clustering of wet or dry conditions into extreme events. The non-linear and hysteretic hydrologic response functions driven by memory are often only studied at shorter temporal scales (event, season) despite larger interannual hydrologic responses evident in some systems. Within the Canadian Boreal, lakes and lake water levels provide an important indicator that can be used to assess the role of landscape memory on catchment hydrological function. Landscape memory has also been hypothesised to control the hydrological dynamics of shallow lake ecosystems that are also important biogeochemically and ecologically. Here we combine measurements of lake water levels in 26 lakes of varying type at varying temporal frequencies within the glaciated sub-humid Boreal Plain, to examine the impact and variability of interdecadal, decadal, multi-year, and intra-annual memory on lake water levels. We show multi-annual hysteresis of precipitation-lake water levels with varied characteristics in space and time. These spatial variations in landscape memory are driven by differences in storage capacities controlled by heterogeneity in glacial landforms, wetland-forest landcover and lake properties. Thus, the propensity for drought years or wet years to persist or accumulate into extreme landscape drying or wetting varies significantly between different lake-landscape characteristics. We show how landscape memory is crucial to project lake water levels by defining spatial variability of the impact of periods of meteorological drought and deluge vital for understanding system sensitivity, duration of recovery and in turn infer resilience on Boreal Plain hydrology.

Late Palaeozoic high-K calc-alkaline to shoshonitic series magmatism and related W(–Mo–Cu–Au) metallogeny of the Kyrgyz Tien Shan, Central Asia

In the Kyrgyz Tien Shan, numerous high-K calc-alkaline to shoshonitic series intrusions are associated with the large fault system known as the ‘Major structural line of Tien Shan’, or ‘Nikolaev Line’. During the Carboniferous, this lineament represented a zone of intracontinental, possibly back-arc rifting associated with a north-dipping subduction, whereas in the Late Carboniferous to Permian it was part of a larger continental collision structure. These Late Paleozoic high-potassic intrusions comprise numerous intrusive phases that vary in composition from the early mafic (monzogabbro, monzodiorite) through intermediate (monzonite, syenite, quartz syenite) to late stage and more evolved (quartz monzonite, granodiorite, monzogranite, leucogranite–alaskite) members locally intersected by monzodiorite–porphyry and lamprophyre dykes. They can be related to low degrees (from ∼1–2 to 2–2.5 vol%) of partial melting of metasomatically enriched upper mantle followed by magma fractionation and emplacement at shallower crustal levels. In summary, the high-K magmas formed in continental- and post-collisional arc settings with a progressive input of crustal material. From the west to the east, the potassic intrusions contain progressively higher Nb and Y concentrations, reflecting their derivation in a post-collisional setting. The A-type granite signatures also become more distinct in this direction. This is consistent with the tectonic model implying the ‘scissor-like’ closure of the Late Paleozoic Turkestan palaeo-ocean from east to west. These high-potassic intrusions are accompanied by W–Mo–Cu–Au skarn/porphyry to Au(–W) replacement-style deposits, which are part of the extended Au (Au–W–Mo–Cu) metallogenic belt of Tien Shan. The association of skarn and porphyry-style W–Mo to Mo–Cu–Au–W mineralization defines these ‘porphyry–skarn’ systems as a distinct group containing strongly oxidized andradite-dominant skarns. An early W partitioning into magmatic–hydrothermal fluid, together with Mo and Cu, is typical of this magmatic–hydrothermal system and can be explained by an early H 2 O saturation of the parental magma. The late-stage mafic dykes including lamprophyres probably reflect the presence of another, but concealed, mafic intrusion releasing CO 2 and metals, such as Au, As, Sb, Bi and Te, into the hydrothermal mineral system.

Performance analysis of perovskite solar cell in presence and absence of defects

Studies of the effect of defects in any solar cell are important in achieving a satisfactory level of its performance. A comparative study with a defect-free against the defect-induced cell carries instant and ready information on laboratory/industry-based fabricated cell performance, which is prone to unavoidably induced defects. In spite of good deal of works on defects of cells such a study in an organized and comparative way remains absent to the knowledge of the authors. Ready and classified presentation of such a study, therefore, is considered to be significant. Present work is a result of motivation to fulfil this gap. This article presents a study of the effects of bulk and interface defects in perovskite solar cells. On examining the effects of deep and shallow defect levels on key performance metrics such as open-circuit voltage, short-circuit current density, and fill factor, the resulting study discusses an analysis of the impact of the defects on cell efficiency. A defect-free cell with optimal perovskite, hole-transport layer (HTL), and electron-transport layer (ETL) dimensions are analysed simultaneously to assess the level at which the defects can degrade the performance of a defect-free cell. It is observed that the defects, particularly in the deep levels, significantly impair the performance of a cell, including the open circuit voltage, short circuit current density, fill factor, and efficiency, compared to those in shallow levels.

Colour change and long-persistent properties of a new phosphor YBaZn3GaO7:Bi3+/Eu3+

Ion doping is one of the most effective strategies to induce interesting luminescence properties of materials. In this work, the Bi3+ and Eu3+ are introduced into a ‘114’ host material YBaZn3GaO7 (YBZG) to generate photoluminescence (PL), long-persistent luminescence (LPL) and colour change properties. The co-doped YBZG:0.003Bi3+/yEu3+ can generate multi-color emissions from green, through yellow to orange with the increasing of Eu3+ concentration. There are F-like color centers around conduction band (CB) of YBZG host with shallow or deep energy levels. The electrons trapped by deep levels response to the PC properties, whereas these for shallow levels response to the LPL properties. The PC process from white to apricot is reversible. By alternating thermal treatment and irradiation, YBZG:0.003Bi3+ was proved to have a good fatigue resistance of 3.1 %. For YBZG:0.003Bi3+/0.05Eu3+, it shows bright orange LPL emission when the irradiation is removed after 24 min. The achievement of this paper provides a design idea that if the host structure of a phosphor is of flexible and easy to occur defect, not only PL property, but also PC and LPL properties are probably able to realize.

Shallow water table rise and fluctuation between 1977 and 2010 in Madinah City, Saudi Arabia

Madinah City in Saudi Arabia is rapidly growing with high population growth, water demand, sewage generation, and agricultural activities. The hydrogeological layering sequence in Madinah City reveals that there are three main layers that extend within the areas between wadi systems. The shallow water table rise (SWTR) problem has risen in several areas of the city, and the fluctuations in the piezometric water observed from the shallow aquifer systems. The research aims to investigate the changes in shallow groundwater levels within the Madinah City. Sources of water table rise and fluctuations are investigated through an extensive field hydro-geological survey comprising wells drilling and water level monitoring, which indicated the following results between 1977 and 2010 including those of newly drilled wells: (i) water flow is partially blocked along wadi Alaqiq and this has caused an increased regional flow moving from west along wadi Alaqiq towards the central area; (ii) groundwater levels have changed in the agricultural areas as indicated by 15–26 m rise along wadi Alaqiq; (iii) groundwater level fluctuations as indicated by 590 m amsl (1977) against less than 575 m amsl (2010) in the east and southeast of the study area as a result of increased heavy pumping since past 37 years. The overall flow phenomenon is reflected in the groundwater gradients on an increasing trend with orientation from the western region along the wadi Alaqiq towards the central area and southeast which has invariably resulted in the overall declining of water levels throughout the affected area.

Exhumation of ultra-high pressure (UHP) rocks modulated by rifted margin-subduction feedback: Implications for their preservation in old collisional orogens

In continental subduction, rifted margins can be carried to mantle depths (> 90 km) where ultra-high pressure (UHP) metamorphism above coesite stability is attained. Although different exhumation mechanisms for UHP rocks have been discussed, none of them integrate the recent understanding of rifted continental margins. Here, we perform high-resolution thermomechanical numerical experiments to demonstrate that segments of magma-poor rifted margins that reach UHP conditions can efficiently exhume back to shallower levels, while segments of magma-rich rifted margins cannot. This is because the thick layer of rocks with a basaltic composition in magma-rich margins becomes negatively buoyant during metamorphism, preventing their exhumation. This new concept might be pivotal for explaining why exhumed UHP rocks, a key feature of modern-style continental orogens, only appeared and became common late in Earth's history. We suggest that higher mantle potential temperatures and fertility in Earth's early history favored magma-rich rifted margins, making exhumation of UHP crust inefficient. Conditions for magma-poor rifted margins may have arisen during Earth's middle age (1.5–0.8 Ga) due to a colder, more refractory mantle that limited melting and magmatism. We argue that at the end of Neoproterozoic, these colder and positively buoyant magma-poor rifted margins were then subducted and efficiently exhumed to form the large collisional orogens of Gondwana where Earth's oldest coesite-bearing UHP rocks have been unequivocally found. Since then, UHP rocks have become a key and ubiquitous feature of continental orogens.

A reaction–diffusion model of major emerging infectious diseases in a spatially heterogeneous environment and case study

During the outbreak of major emerging infectious diseases, virus droplets can survive in the environment as aerosols for hours to days, and their impact on human infectious diseases is often overlooked. In addition, the speed of transmission of infectious diseases is often closely related to transportation. Therefore, studying the impact of environmental viruses and transportation on disease development is significant for effective infectious disease prevention and control. We proposed a degenerate reaction–diffusion infectious disease model ([Formula: see text]) considering environmental virus interference and established a well-posedness and threshold system for this model. We have obtained the system solution approaches the disease-free equilibrium ([Formula: see text]) when the basic reproduction number [Formula: see text]. The system has at least one positive steady state solution (PSS) when [Formula: see text]. This paper used a non-standard finite difference method discretization model while data fitting and parameter estimation were performed based on data provided by the Health Commission. Further sensitivity analysis was conducted on [Formula: see text]. At the same time, we also discussed the impact of various parameters in the early stages of the outbreak of major emerging infectious diseases on the development of the disease. Research found that even if the contact rate between people is controlled at a shallow level, the disease may persist. In the early stages of major emerging outbreak of infectious diseases, immediately reducing the use of transportation can effectively reduce the speed of disease spread.

Interlinking the Fe doping concentration, optoelectronic properties, and photocatalytic performance of ZnO nanostructures

Doping is one of the effective strategies to modulate the optoelectronic properties and photocatalytic activity of photocatalysts. In this study, the effect of Fe doping (0–10 %) on morphology, optical and electronic properties, and photocatalytic activity of ZnO nanostructures is studied. The X-ray diffraction analysis shows that >5 % Fe doping, ZnFe2O4 is segregated as a secondary phase. The crystalline size decreases from 50.8 nm to 21.4 nm and the micro-strain increases with increasing the Fe concentration. The Fe doping-induced electronic restructuring facilitates visible light absorption through the O 2p → Fe 3d transition and the suppression of charge recombination by efficiently trapping conduction band electrons. Density functional theory (DFT) calculations are employed to unravel the underlying electronic changes induced by Fe doping in ZnO. The formation of shallow donor levels below the conduction band originates from the Fe 3d state. Photoluminescence spectra of pristine and Fe-doped ZnO nanostructures show characteristic emission peaks at approximately 384 nm and 570 nm, indicating the recombination of free excitons and oxygen interstitial defects, respectively. The results of the photocatalytic activity tests confirm that the 1 % Fe-doped ZnO nanostructures can exhibit the highest efficiency compared to the heavily doped ZnO nanostructures. The high efficiency in photocatalytic activity of 1 % Fe-doped ZnO nanostructures is ascribed to the modulated electronic structure and defect density. The adsorption affinity of methylene blue and water molecules to the surfaces of pristine and Fe-doped ZnO is simulated using the Monte-Carlo method. This study emphasizes the importance of controlling the dopant concentration to enhance the photocatalytic activity of various photocatalysts.

PORPHYRY COPPER RECURRENCE IN THE ANDES OF CHILE AND ARGENTINA

Abstract Porphyry Cu deposits in the Chilean and Argentinian central Andes occur in a series of orogen-parallel magmatic arcs, which migrated episodically eastward since the Early Cretaceous. The three Cenozoic belts, corresponding to Paleocene-early Eocene, middle Eocene-early Oligocene, and Miocene-early Pliocene epochs, cut obliquely across a composite belt of subeconomic porphyry Cu mineralization formed at several times during the Late Carboniferous to Triassic interval. Based mainly on U-Pb zircon and Re-Os molybdenite ages, 10 Cenozoic porphyry Cu centers, including major deposits in all three of the Cenozoic belts, occupy the same sites as late Paleozoic-Triassic porphyry Cu mineralization where their respective magmatic arcs cross one another. The sites of recurrent porphyry Cu mineralization are believed to be underlain by long-lived dike conduits that were utilized at least twice—first in the late Paleozoic-Triassic and then again in the Cenozoic—to rapidly transmit hydrous magma from deep to shallow levels of the crust. Contenders for preferential dike localization include arc-oblique fault and subjacent ductile shear zones—transcrustal discontinuities—long hypothesized to be present in the region, particularly where they intersect magmatic arcs and associated porphyry Cu belts. Regardless of the controls on porphyry Cu recurrence, alteration zones hosted by late Paleozoic-Triassic volcanic and plutonic rocks in the central Andes of Chile and Argentina must be considered prime exploration targets for potentially large, high-grade Cenozoic porphyry Cu deposits.

Crystallization Sequence of the Spodumene-Rich Alijó Pegmatite (Northern Portugal) and Related Metasomatism on Its Host Rock

The Barroso–Alvão region is an excellent setting for studying Li mineralization associated with granitic pegmatites and developing Li exploration techniques. Among the distinguished pegmatite types in this pegmatite field, the spodumene-bearing dyke from Alijó is a representative example of an Iberian Li–Cs–Ta (LCT) pegmatite currently under exploitation. In this work, we examine the internal evolution of the Alijó dyke and its external metasomatic effect on the surrounding metasediments, contributing to lithium exploration techniques. Electron microprobe analyses provided clues about the crystallization conditions and the degree of differentiation of the pegmatitic melt, whereas the external metasomatism induced by the spodumene-bearing pegmatite was studied through whole-rock geochemistry. The obtained results indicate that the primary crystallization of the studied dyke likely occurred at temperatures between 450–500 °C, with emplacement at shallow crustal levels of about 2–3 kbar. The high concentrations of trace elements such as Li, Cs, Rb, Be, Sn, Nb, Ta, Ge, U, and Tl in the pegmatitic melt suggests high availability of these elements, allowing their partitioning into an early exsolved fluid phase. The exsolution of this fluid phase, subtracting components such as F and B, from the pegmatitic melt would cause a significant undercooling of the melt. Moreover, the interaction of this expelled fluid with the country rock generated a metasomatic overprint in the surrounding metasedimentary host rocks. The metasomatic effect in Alijó is strongly influenced by the nature of the host metasediments, with a significantly higher grade of metasomatism observed in pelitic (mica-rich) samples compared to psammitic (mica-poor) samples collected at same distances from the dyke. The greisen developed close to the pegmatite contact reflects this metasomatic signature, characterized by the mobilization of at least B, F, Li, Rb, Cs, Sn, Be, Nb, Ta, and Tl. We cautiously suggest that whole rock Li concentrations greater than 300 ppm, combined with a minimum value of 1000 ppm for the sum of B, F, Li, Rb, Cs, and Sn in pelitic metasediments of Barroso–Alvão, may be indicative of a mineralized pegmatite in this region.

Study on bubble behaviors and heat transfer at shallow liquid boiling over open rectangular microchannels

The heat transfer performance of shallow liquid boiling differs from that of deep liquid boiling owing to distinct bubble venting mechanisms. Since the liquid level is of the same order of magnitude as the bubble departure diameter, bubble detachment is restricted by the surface tension of the free interface, which causes an untimely liquid reflux toward the nucleate site. Consequently, shallow liquid boiling has a high heat transfer coefficient (HTC) at a liquid height below the critical liquid level but at the expense of limited critical heat flux (CHF). This study aims to improve the CHF of shallow liquid boiling by utilizing open rectangular microchannels surface (ORMS), which can provide separated vapor–liquid pathways to facilitate the liquid return. The boiling heat transfer curves and bubble behavior of distilled water at shallow liquid levels are investigated using the ORMS. A critical liquid level of 5 mm was achieved with heat fluxes of approximately 15 W/cm2, 25 W/cm2, and 35 W/cm2 over ORMS. Compared to a plain copper surface (PCS), ORMS improves the upper limit of the heat flux for the critical liquid level. A simplified and efficient analytical model with two-sphere bubble is established to predict the critical liquid level for the ORMS by considering the dynamic and static force balance. The critical liquid level is approximately twice the bubble departure diameter, which may aid in designing the liquid filling rates for phase-change heat sinks for HTC improvement.

The thermal structure of the Colombian lithosphere: A regional and basin-scale analysis

It is well-established that the thermal state of the lithosphere strongly influences various regional and local geological processes, including crustal deformation, hydrocarbon maturation, hydrogen generation, and geothermal phenomena. Moreover, the thermal structure exhibits high sensitivity to tectonic features, a property of particular significance in Colombia, where three main tectonic plates converge, and lithospheric tearing has been documented. In this contribution, we focus on elucidating the impact of plate architecture on the thermal field in central-eastern Colombia at both shallow and deep levels. To accomplish this, we constructed a series of two-dimensional profiles and derived a numerical solution of the heat equation using the conservative finite difference method. As constraints, we incorporate an inferred distribution of rocks in the deep crust and upper mantle based on global and local lithospheric thickness models. Material parameters for the various rocks, both exposed and inferred, were obtained from the literature. Additionally, we used superficial heat flow estimates and apparent geothermal gradients compiled by the Colombian Geological Survey.Our results suggest a significant influence of the lithospheric Caldas tear on the thermal state of Colombia, with the breaking off occurring in the Nazca plate under the Eastern Cordillera range around 5°N. The modeled asthenospheric heat flow remains approximately 25 mWm−2, except in the northern Eastern Cordillera range, where the background heat flow increases rapidly to 40 mWm−2. Consequently, our model predicts partial melting in the lower crust to the north and a thermally unstable lower crust to the south of the Caldas tear. The material parameters that best fit the surface data suggest the presence of a basement moderately enriched in radioactive elements in the Eastern Llanos basin. After accounting for compaction, we also confirm a strong influence of the tectonic setting on the thermal state of sedimentary basins.

Evolution of Devonian and Carboniferous pre-Andean arc magmatism in the Frontal Cordillera (27°-35°S), Argentina: Insights from U–Pb zircon and isotopic studies

We propose a conceptual model for the magmatic system that gave rise to the Devonian and Carboniferous subduction-related magmatism in the Frontal Cordillera of Argentina, (representing the pre-Andean margin of SW Gondwana), integrating previous geochronological studies with new geochronological data from granitoids and subvolcanic dikes, which include reported petrological, geochemical, and isotopic data. This conceptual magmatic system postulates an extended magmatic activity, similar to that reported in a previous study for the Devonian foreland magmatism located in the present-day Sierras Pampeanas of Argentina. The geochronological data play a central role in the model, and lead us to postulate the presence of a deep mush reservoir, where a prolonged magmatic activity, permitted the extended crystallization of Devonian (ca. 400 ± 3 and 414 ± 3 Ma) and Carboniferous antecrysts (334 ± 2 Ma, 341 ± 2, and 348 ± 2, where the age of 348 Ma maybe considered as derived from the source, i.e. xenocrysts). Migration of the parental magma from the mush reservoir zone occurred near the time of emplacement and culminated in the formation of an ephemeral magma chamber located in shallow levels, where Devonian and Carboniferous zircon autocrysts crystallized (382 ± 5 Ma and 325 ± 2 Ma, respectively). Age spectra reported within individual sample, favors the idea of a massive migration of magma when conditions were favorable (e.g., thermally matured crust). Notably, the Carboniferous geochronological data is strongly consistent with previous geochronological data recently reported for the granitic rocks of the Tabaquito batholith. Although this model supports a protracted magmatic system for the Devonian and Carboniferous subduction-related magmatism, previous and new isotopic data reveal a significant difference in the petrogenetic processes. While the Carboniferous arc magmatism shows significant juvenile material contribution, this is not the case for the Devonian magmatic arc, where isotopic data suggest an older continental lithosphere as the dominant source. These different sources are attributed to two contrasting geodynamic settings, with advancing and retreating oceanic slabs, respectively.

Shallow groundwater quality around the area Kaligending final processing site in Kebumen Regency, Central Java Province

Abstract The location of the Kaligending final Processing site is in Kraminan, Kaligending Village, Karangsambung District, Kebumen Regency which is the place for final waste processing. The Kaligending final processing site which is located in the hills can have an environmental impact on the area located below it. One of the impacts is the condition of groundwater in the area. The purpose of this study is to determine the condition and quality of shallow groundwater in the area. To find out groundwater conditions especially position and the pattern of shallow groundwater flow in the area is measured in the shallow ground water level which is then made a map of shallow groundwater and shallow groundwater flow direction patterns, while groundwater quality is measured by electrical conductivity and total dissolve solid (TDS) shallow groundwater in several wells. The results of the map pattern of shallow groundwater flow directions in the area come from the east and northeast, groundwater quality based on electrical conductivity is still suitable for use. The quality of shallow groundwater in residents’ wells in the Kraminan area is based on total dissolved solids, there are 4 wells that exceed the upper limit of drinking water quality standards (wells 3, 4, 5 and 6) which are located close to the Krembeng River

Migration and focusing of porphyry deposit-forming fluids through aplitic mush of the Saginaw Hill cupola, Arizona, United States

Porphyry-type Cu ± Au ± Mo deposits form in the upper (ca. 2–5 km deep) parts of large, long-lived magmatic-hydrothermal systems in which mineralising fluids are thought to be derived from mid-to shallow-crustal magma chambers. Increasingly, however, magmatic systems are viewed as consisting of mush with minor and transient lenses of magma, with mush being a variably packed framework of crystals with interstitial melt and magmatic volatile phase (MVP). In this context, questions remain as to the source (mainly depth) and mechanisms of transport and focussing of the vast volumes of fluids required for shallow level porphyry-type mineralisation. Even more problematic is a paucity of first-order textural evidence for the presence of mush in magmatic-hydrothermal systems, including those which host porphyry-type deposits. To address this, we have studied the aplitic porphyry cupola of the Saginaw Hill magmatic system, Tuscon, Arizona, United States, where magmatic-hydrothermal features are exceptionally well exposed, including a massive silica cap, quartz unidirectional solidification textures (USTs), stockworks of multiple generations of variably mineralised quartz veins and mineralised miarolitic cavities. From field-to micro-scale textural and geochemical studies, particularly observations of vermiform quartz between earlier generations of magmatic quartz and feldspar, we evidence the development of fluid pathways through mush at the magmatic-hydrothermal transition. These are shown to connect and provide fluids and ore constituents to the mineralised miarolitic cavities and early quartz vein stockworks. We suggest that this process should be considered in all new genetic, exploration and numerical models for porphyry and similar types of magmatic-hydrothermal ore-deposits.

Enhancing efficiency and stability of inverted perovskite solar cells through synergistic suppression of multiple defects via poly(ionic liquid)-buried interface modification

The stability of perovskite solar cells (PSCs) is adversely affected by nonradiative recombination resulting from buried interface defects. Herein, we synthesize a polyionic liquid, poly(p-vinylbenzyl trimethylammonium hexafluorophosphate) (PTA), and introduce it into the buried interface of PSCs. The quaternary ammonium cation (N(–CH3)3+) in PTA can fill the vacancies of organic cations within the perovskite structure and reduce shallow energy level defects. Additionally, the hexafluorophosphate (PF6−) in PTA forms a Lewis acid-base interaction with Pb2+ in the perovskite layer, effectively passivating deep energy level defects. Furthermore, hydrogen bonding can be established between organic cations and the PF6− anion, preventing the formation of shallow energy level defects. Through this synergistic mechanism, the deep and shallow energy level defects are effectively mitigated, resulting in improved device performance. As a result, the resulting treated inverted PSC exhibits an impressive power conversion efficiency (PCE) of 24.72 %. Notably, the PTA-treated PSCs exhibit remarkable stability, with 88.5 % of the original PCE retained after undergoing heat aging at 85 °C for 1078 h, and 89.1 % of the initial PCE maintained following continuous exposure to light for 1100 h at the maximum power point. Synergistically suppressing multiple defects at the buried interface through the use of polyionic liquids is a promising way to improve the commercial viability of PSCs.

Photobiocidal Activity of TiO2/UHMWPE Composite Activated by Reduced Graphene Oxide under White Light.

Herein, we introduce a photobiocidal surface activated by white light. The photobiocidal surface was produced through thermocompressing a mixture of titanium dioxide (TiO2), ultra-high-molecular-weight polyethylene (UHMWPE), and reduced graphene oxide (rGO) powders. A photobiocidal activity was not observed on UHMWPE-TiO2. However, UHMWPE-TiO2@rGO exhibited potent photobiocidal activity (>3-log reduction) against Staphylococcus epidermidis and Escherichia coli bacteria after a 12 h exposure to white light. The activity was even more potent against the phage phi 6 virus, a SARS-CoV-2 surrogate, with a >5-log reduction after 6 h exposure to white light. Our mechanistic studies showed that the UHMWPE-TiO2@rGO was activated only by UV light, which accounts for 0.31% of the light emitted by the white LED lamp, producing reactive oxygen species that are lethal to microbes. This indicates that adding rGO to UHMWPE-TiO2 triggered intense photobiocidal activity even at shallow UV flux levels.

Magmatic sulfide oxidation drives crustal PGE mobilization: Implications for hydrothermal PGE mineralization

Platinum-group elements (PGEs) have a strong affinity for sulfur and tend to accumulate in the deep continental crust, either concentrated within magmatic Cu-Ni-PGE deposits or dispersed throughout disseminated sulfides. However, PGE enrichment in shallow magmatic-hydrothermal systems implies an obscure link to deep sulfide destabilization, which releases PGEs into ore-forming fluids. To bridge this gap, our study investigates the PGE composition of magmatic sulfides with oxidative textures in dacitic rocks from the southwestern Okinawa Trough. We identified three groups of magmatic sulfides, primarily precipitated as Cu-poor monosulfide solid solution (MSS), which formed at distinct stages of magma evolution from deep to shallow crustal levels. Group A sulfides manifest as small-sized inclusions (<30 μm) within most high-Mg olivines, whereas Group B and C sulfides are larger (50–500 μm) and occur within cognate xenoliths of mafic cumulate rocks and the groundmass of host dacites. Group B and C sulfides exhibit distinct oxidative textures and newly-formed mineral assemblages, including magnetite, hematite, goethite, and magnetite ± pyrite, alongside hydrothermal silicate minerals, respectively. We attribute the oxidation process to the infiltration of orthomagmatic fluids exsolved from mafic magma that had underplated the sulfide-bearing felsic magma reservoir, which was nearly solidified. By comparing the chemical compositions between pristine sulfides and their oxidative remnants, we observed extensive mobilization of Pd, Pt, Cu, Ag, Ni, and Co from the altered sulfides of Group B, while Au enrichment occurred as nanoparticles under high oxidation states. In contrast, Au was extracted along with other mobile metals from the altered sulfides of Group C, with Pt remaining in place under more reduced conditions. These distinct scenarios may lead to the formation of PGE-rich and Au-rich fluids, respectively. The formation of deep crustal MSS and subsequent hydrothermal oxidation under varying redox conditions thus provides a viable mechanism for trans-crustal PGE mobilization and inter-element fractionation, typical of PGE-rich magmatic-hydrothermal deposits.