Search Results (972)

The northwestern Amazonian Craton exposed in eastern Colombia preserves a complex Proterozoic tectonothermal history. In this study, we present new zircon and apatite U–Pb geochronological data from orthogneisses of the Guaviare Complex (Termales Gneiss unit) to constrain the timing of crust formation, metamorphism, and subsequent thermal events. Zircon U–Pb data define a dominant concordant population at ca. 1.30 Ga, interpreted as the crystallization age of an igneous protolith. This age is consistent with Mesoproterozoic A-type magmatism previously recognized in the region and consistent with emplacement under intracratonic extensional conditions, as suggested by previous studies. A limited number of discordant zircon analyses indicate Pb loss and/or partial isotopic resetting between ~1.0 and 0.6 Ga, although no well-defined metamorphic zircon population is identified. Meanwhile, apatite U–Pb analyses from key samples yield consistent lower intercept ages between 633 ± 16 Ma and 543 ± 8 Ma, indicating a widespread Ediacaran thermal disturbance that may have affected the Guaviare Complex, temporally overlapping with alkaline magmatism in the northwestern Amazonian Craton, including the San José del Guaviare Nepheline Syenite. However, alternative mechanisms such as fluid-assisted Pb mobility, regional reheating, or prolonged cooling cannot be excluded. Finally, the combined zircon–apatite dataset highlights the value of multi-chronometer approaches for resolving complex thermal histories in cratonic domains. Full article

Total nitrogen (TN) is a critical indicator of water eutrophication. Conventional detection methods (e.g., alkaline potassium persulfate digestion and the Kjeldahl method) suffer from complex sample preparation, time-consuming operations, and reagent-induced pollution. Laser-induced breakdown spectroscopy (LIBS) offers unique advantages for rapid water quality analysis, yet it predominantly relies on costly actively Q-switched lasers, with passive Q-switching rarely explored due to multi-pulse output instability. This study employed a passively Q-switched laser as the excitation source for water TN measurement. By optimizing the multi-pulse trigger position, the signal-to-background ratio (SBR) was effectively enhanced. Combined with the substrate liquid–solid conversion method, key parameters (trigger delay, laser energy, argon flow rate) were optimized. Laboratory measurements of KNO₃ standard solutions (0–25 mg/L) using cyanogen (CN) molecular spectral lines yielded a coefficient of determination (R²) of 0.98, and a limit of detection (LoD) of 2.19 mg/L. Tests on actual water samples showed relative deviations ranging from 3.93% to 6.39%. These results demonstrate that passively Q-switched LIBS is a viable, cost-effective solution for rapid water nitrogen detection. Full article

Perylene bisimide derivatives are typical n-type semiconductors as well as redox-active materials. However, it has been difficult to produce thin films by solution processes because of their low solubilities in organic solvents. Perylene bisimide derivatives bearing oligosiloxane moieties exhibit columnar phases over wide temperature ranges, including room temperature and high solubilities in organic solvents. The columnar phases are stabilized by nanosegregation between crystal-like one-dimensional π-stacks and liquid-like mantle consisting of oligosiloxane moieties. The electron mobility at room temperature exceeded 0.1 cm²V⁻¹s⁻¹ in the ordered columnar phases of perylene bisimide derivatives bearing four disiloxane chains. Uniaxially aligned thin films of the perylene bisimide derivatives bearing oligosiloxane moieties could be produced by a spin-coating method. The spin-coated films of the perylene bisimide derivatives bearing cyclotetrasiloxane rings could be insolubilized via in situ ring-opening polymerization by the exposure of the thin films to trifluoromethanesulfonic acid vapors. Uniaxially aligned thin films of perylene bisimide derivatives bearing an ethylene oxide chain as well as cyclotetrasiloxane rings could be doped in an aqueous solution of sodium dithionate, resulting in an anisotropic electrical conductivity. Polymerized thin films of perylene bisimide derivatives bearing a crown ether ring exhibited electrochromism in electrolyte solutions. These compounds formed 1:1 complexes with lithium triflate, exhibiting columnar phases at room temperature. The nanostructures of the complexes were stabilized by the electrostatic interaction between cationic crown-metal units and triflate anions. Full article

Marine hydrogen production systems deployed on ships and floating platforms are inevitably subjected to complex multi-degree-of-freedom motions induced by waves and wind, which may influence electrolyzer performance. However, experimental investigations under realistic marine motion conditions remain limited. In this study, a laboratory-scale alkaline water electrolyzer was installed on a six-degree-of-freedom (6-DOF) motion platform to experimentally investigate the influence of marine sloshing on polarization characteristics. The experimental design focuses on the fluctuation of cell polarization behavior under dynamic conditions using a single-cell configuration. Typical single-degree-of-freedom (SDOF) and coupled multi-degree-of-freedom (MDOF) motions were reproduced to simulate representative marine operating environments. The results show that sloshing motion leads to a moderate increase in cell voltage compared with static conditions. Under SDOF conditions, the voltage increase remains within 7%, with sway and roll identified as the dominant disturbance modes. Under coupled MDOF conditions, the voltage increase is further amplified but remains below 10.2% even under 6-DOF motion. The results also reveal that the effect of coupled motions is nonlinearly weaker than the linear superposition of individual motions. This study provides experimental evidence that alkaline electrolyzers can maintain stable operation under realistic marine dynamic conditions. These deviations correspond to limited efficiency losses and remain within typical engineering tolerances, suggesting that marine motion has a manageable impact on electrolyzer performance and offers practical guidance for offshore system design and control. Full article

Niobium is a strategic critical mineral that supports emerging energy and high-end manufacturing. The geophysical parameters of carbonatite-alkaline rock-type niobium deposits constitute essential baseline data for regional geophysical exploration and prospecting target delineation. To clarify the geophysical response characteristics and exploration the significance of the Dagele niobium deposit in the Eastern Kunlun Region (western China). This study focuses on drill hole ZK3202. Samples from ore bodies, mineralized zones, and wall rocks of different lithologies were continuously measured. Combined with 1001.8 m of full-hole core digital logging data, statistical methods, including box plots, histograms, multi-parameter cross-plots, and correlation coefficient analysis, were applied to quantitatively investigate the physical property responses of lithologies such as calcite-biotite rock (ore body), calcite-bearing pyroxenite (mineralized zone) and amphibolite in the vertical profile. Lithological identification thresholds were established to divide the drill-hole into lithological and mineralized ore layers. The results show that the ore-bearing lithofacies exhibit a distinctive geophysical signature characterized by high density, strong magnetism, medium-low resistivity, high polarizability, and slightly elevated natural radioactivity, which clearly distinguishes them from surrounding from wall rocks. Based on five key parameters—density, magnetic susceptibility, resistivity, polarizability, and natural gamma—a lithological identification model for amphibolite and mineralized altered rock assemblages was established. This study also summarizes the multi-parameter coupling mechanism of ore-bearing lithofacies, which can effectively delineate favorable niobium-bearing horizons. This work fills a gap in the geophysical property characterization of carbonatite-alkaline complex-type niobium deposits in the Eastern Kunlun region and provides data support and regional reference for integrated gravity-magnetic-electrical-radioactive geophysical exploration, prospecting target delineation, and the exploration of similar niobium deposits in western China. Full article

Siderophores are high-affinity iron-chelating metabolites that underpin microbial survival in iron-limited environments and play central roles in metal homeostasis, ecological competition, and pathogenesis. Traditionally viewed as dedicated Fe(III) scavengers, siderophores are now recognized as structurally and functionally versatile coordination agents whose donor-set architectures—particularly catecholate and α-hydroxycarboxylate motifs—permit conditional interactions beyond iron. In iron- and boron-rich niches, especially marine and mildly alkaline systems where borate availability increases, certain siderophores are chemically capable of forming reversible borate complexes through cis-diol coordination. Although Fe(III) exhibits substantially higher thermodynamic affinity and remains the primary biological target, boron binding represents a predictable secondary property arising from shared oxygen-donor chemistry. This dynamic interplay allows siderophores to cycle between iron-bound, boron-bound, and apo states depending on local redox conditions, pH, and metal availability. Here, we synthesize current knowledge on the structural classes of microbial siderophores, their transport and regulatory mechanisms, and emerging evidence for boron coordination within catecholate and carboxylate systems. By integrating coordination chemistry with microbial ecology, we propose an expanded model in which siderophores function not only as iron acquisition molecules but also as modulators of boron speciation and environmental sensing. This functional plasticity positions siderophores at the intersection of iron and boron biogeochemical cycles and highlights new directions for understanding microbial adaptation in complex metal-rich environments. Full article

The Arganaty Massif in the Eastern Balkhash region (Kazakhstan) is located in a key sector of the Central Asian Orogenic Belt, but its petrogenesis and relationship to neighboring Late Palaeozoic intrusions remain poorly constrained. This study presents the first U–Pb zircon age and whole-rock geochemical data for the Arganaty granites, combined with a comparison with massifs of the Northern Balkhash region and Alatau Mountains (East Kazakhstan and Western Xinjiang, NW China). The Arganaty granites have a concordant U–Pb age of 281.5 ± 2.1 Ma. They are high-K calc-alkaline, metaluminous to slightly peraluminous I-type granites with low Mg# (0.22–0.33) and Nb/Ta ratios (10.2–17.3). Geochemical comparison indicates close affinity to the Lepsy complex intrusions and eastern plutons of Alatau mountains, rather than to the Katbar complex of Northern Balkhash. The new age and geochemical data show that the Arganaty granites formed in a post-collisional setting after the closure of the Junggar–Balkhash Ocean. Their mixed crust–mantle signature and depth estimates (~30 km) are consistent with lower crustal melting triggered by slab break-off. These results clarify the post-collisional magmatic evolution of the region and contribute to the understanding of Late Palaeozoic crustal growth in the CAOB. Full article

Sunflower (Helianthus annuus L.) production is severely hindered by continuous cropping obstacles, leading to soil degradation and significant yield declines. This study compared soybean–sunflower (G-H) and maize–sunflower (Z-H) rotations against sunflower monoculture (H-H) to elucidate the mechanisms of soil health restoration associated with crop rotation. Our results demonstrated that Z-H and G-H rotations led to a profound yield increase of 103.19% and 82.35%, respectively, with Z-H improving the 100-grain weight by 52.63%. Soil biological revitalization was evidenced by a 98.29% increase in sucrase activity and a 28.92% rise in alkaline phosphatase activity. Metagenomic analysis revealed that the rotation sequences increased bacterial Chao1 richness by 35.29% and fungal Shannon diversity by 20.17%. Specifically, the rotation treatments proactively recruited beneficial taxa such as Pontibacter (Log₂FC > 3.0) and Panaeolus (Log₂FC = 6.88), while effectively suppressing pathogens such as Ceratobasidiaceae. Co-occurrence network analysis identified a complex bacterial scaffold (199 nodes, 53 modules) that provided greater structural robustness than the fungal network (27 nodes). It is concluded that diversified rotations effectively mitigate continuous cropping obstacles by reactivating nutrient cycling and restructuring the rhizosphere into a stable, modular microbial interactome. This study provides a quantitative framework for utilizing biological strategies to restore soil health in degraded agroecosystems. Full article

Saline–alkaline water constitutes a vital strategic non-traditional fishery resource in China, characterized by high pH values, elevated carbonate alkalinity, and complex ionic compositions. These extreme environmental conditions impose significant stress on aquatic animals, mainly by inducing ionic toxicity and disrupting acid–base regulatory mechanisms. Such disruptions subsequently lead to osmotic imbalance, metabolic dysregulation, and immunosuppression, thus restricting the survival and growth of aquatic species in aquaculture systems. Consequently, the sustainable development of the saline–alkaline aquaculture is imperative for enhancing production efficiency and promoting the utilization of marginal land and water resources. This review comprehensively summarizes the current status of saline–alkaline aquaculture and highlights the stress-inducing impacts of salinity, alkalinity, and specific ionic ratios on teleost fishes and crustaceans. It further explores key adaptive mechanisms, including osmoregulatory and ionoregulatory strategies, bioenergetic trade-offs related to oxygen consumption and ammonia excretion, coordinated antioxidant and innate immune responses, as well as recent findings from multi-omics research. This review aims to offer a scientific foundation for the selection and breeding of saline–alkaline-tolerant strains, the precise regulation of aquaculture water environments, and the development of ecological aquaculture models in saline–alkaline regions, thereby facilitating the sustainable utilization of saline–alkaline land and water resources. Full article

Land-use change contributes significantly to climate change mitigation through biophysical changes (albedo, α) and biogeochemical (greenhouse gases, GHG) emissions (here refers to methane, CH₄, and nitrous oxide, N₂O). While the impact of grassland–cropland conversion on global warming potential (GWP) is well-documented globally, research remains scarce in the saline-alkaline agropastoral transition zone (APTZ) of the western Songnen Plain, Northeast China, an ecotone uniquely characterized by soil-crusting and seasonal inundation. We conducted in situ bi-weekly measurements of N₂O and CH₄ fluxes (June–September) to acquire growing season ${\mathrm{GWP}}_{{\mathrm{N}}_2\mathrm{O}}$ and ${\mathrm{GWP}}_{{\mathrm{C}\mathrm{H}}_4}$, alongside α. The study compared an undisturbed fenced meadow (FMD) with three adjacent land-use types, clipped meadow (CMD), saline-alkaline meadow (SAL), and paddy rice field (PDY), converted from FMD from 2018 to 2022. Annual α-induced GWP (GWPΔα) was positive across all converted sites (CMD, SAL, and PDY), indicating a warming effect due to lower α compared to FMD. The PDY exhibited the highest CH₄ emission (5.04 kg CO₂ m⁻² yr⁻¹), exceeding other land uses by three orders of magnitude (p < 0.05). Conversely, N₂O emissions remained consistently minimal and stable across all sites. When integrating the net ecosystem exchange of CO₂ (NEE), the PDY functioned as a net warming source. In contrast, the warming effects of α and non-CO₂ GHGs were effectively offset by the NEE in other land uses. Machine learning identified soil water content (SWC) as the dominant predictor of α across all land uses in growing season. However, a mechanistic divergence was observed, i.e., α in low saline-alkali ecosystems (FMD, CMD and PDY) was shaped by coupled biotic and soil moisture controls, whereas in the degraded SAL ecosystem, α is almost exclusively abiotic-driven. These findings demonstrate that land-use conversion in the Songnen Plain governs complex land-surface feedbacks through distinct pathways. This study provides a quantitative framework for integrating biophysical and biogeochemical impacts to optimize land management for climate resilience in saline-alkaline agropastoral ecotones. Full article

The Dibaya Granitic and Migmatitic Complex (DGMC), located in the Kanyiki–Kapangu sector of the Kasaï Shield (Congo–Kasaï Craton, Democratic Republic of the Congo), represents a key exposure of Neoarchean continental crust in Central Africa. Despite its geological importance, information on its petrology, geochronology, geochemistry, and structural evolution remains dispersed across historical studies. This contribution presents a structured geological synthesis based exclusively on previously published cartographic, petrographic, structural, and isotopic data. No new analytical data are introduced; rather, existing datasets are systematically compiled, critically reassessed, and integrated into a coherent tectono-thermal framework. Published Rb–Sr and U–Pb ages indicate high-grade metamorphism and widespread migmatitization at ca. 2.72 Ga, followed by granitoid emplacement at ca. 2.65 Ga. Documented mineral assemblages (garnet–biotite–plagioclase–quartz ± K-feldspar ± amphibole) and the absence of reported high-pressure index minerals support high-temperature, moderate-pressure metamorphism consistent with intracrustal reworking. Reported regional geochemical characteristics suggest high-K calc-alkaline, weakly to moderately peraluminous granitoids derived predominantly from reworking of older TTG-type crust. Structural relationships, particularly along the Malafudi corridor, demonstrate strong coupling between deformation, anatexis, and magma emplacement. Collectively, this synthesis formalizes a Neoarchean intracrustal reworking model and provides a structured analytical basis for future high-resolution petrochronological and geochemical investigations. Although no new quantitative datasets are presented, this study provides the first systematic integration of dispersed geological and isotopic information for the Dibaya Complex, establishing a transparent analytical framework for future high-resolution investigations. Full article

The growing consumer trend toward plant-based diets is prompting the food industry to seek alternatives to animal protein. Chickpea protein (CPP) stands out for its high protein content (14.9–24.6%) and represents a sustainable alternative. Therefore, this study evaluated and compared the techno-functional performance of CPP and whey protein isolate (WPI), with a focus on their emulsifying capabilities for plant-based food development. CPP was extracted via alkaline extraction and isoelectric precipitation. The techno-functional properties were evaluated, including solubility index (%), foaming capacity (%), emulsion activity index (EAI), gelling, and interfacial properties. Additionally, CPP was used as an emulsifier in plant-based emulsions, and the emulsion stability was compared with WPI for two months. Although CPP exhibited a lower solubility index (60 ± 1.0%) than WPI (95 ± 0.3%), its foaming capacity was identical (CPP: 57 ± 6%; WPI: 58 ± 4%) and exhibited a significantly higher emulsion activity index (22 ± 0.3 m²/g) than WPI (15 ± 0.8 m²/g). In terms of gelation, WPI formed stronger gels (1.2–2.1 N) than CPP (0.05–0.06 N), at the same concentrations. Interfacial tension measurements showed that, while CPP exhibited a higher interfacial saturation concentration (0.055 g/L vs. 0.023 g/L), it was more effective at reducing equilibrium interfacial tension than WPI. Finally, emulsion stability over two months was similar when using CPP or WPI as emulsifiers. CPP demonstrates a competitive functional profile; however, its implementation as a sustainable ingredient will require physical or chemical modifications to improve its functional properties for complex food matrices. Full article

High-concentrate diets are widely used to enhance growth performance in fattening beef cattle; however, they often compromise rumen epithelial integrity, increasing the risk of rumenitis and systemic inflammation. Supplementation with alkaline mineral complex (AMC) has been shown to alleviate these adverse effects, although the underlying mechanisms remain largely unexplored. In this study, AMC supplementation was associated with improved rumen epithelial integrity and remodeling of the rumen microbiota, characterized by a reduction in Bacteroidota and Prevotella, and an enrichment of Sarcina sp. DSM11001 and Fibrobacter spp., with the latter identified as a key microbial biomarker in the AMC group. Integrated metabolomic and transcriptomic analyses revealed activation of the tryptophan metabolism pathway and accumulation of several anti-inflammatory metabolites, including sulfinpyrazone, Thr-Leu, and 4-guanidinobutyric acid. These metabolomic changes were correlated with the upregulation of tight junction pathways and increased expression of related proteins, which in turn were associated with enhanced epithelial barrier integrity and reduced systemic inflammation in the AMC group. Collectively, these findings suggest that AMC supplementation may protect rumen epithelial integrity by modulating the microbial community and altering ruminal metabolite profiles. This study provides insights into nutritional strategies to prevent epithelial damage under high-concentrate feeding conditions and support the potential use of AMC to maintain rumen health in fattening cattle. Full article

Salophen-type Schiff base ligands derived from salicylaldehyde and naphthalene aldehydes were synthesized and coordinated to Ni(II) to obtain three nickel complexes (NiL1–NiL3), which were evaluated as heterogeneous electrocatalysts for the methanol electro-oxidation reaction (MOR) in alkaline media. The ligands and complexes were fully characterized by FT-IR, ¹H NMR, EPR, DART-MS, and elemental analysis, confirming tetradentate coordination through imine nitrogen and phenoxide oxygen donors. Electrochemical studies were carried out using carbon paste electrodes modified with 15 wt % of each complex. Cyclic voltammetry revealed that the electrocatalytic activity is mediated by the Ni(II)/Ni(III) redox couple, with Ni(III) oxohydroxide species acting as the active sites for methanol oxidation. Among the evaluated systems, NiL1@CPE showed superior performance at low methanol concentrations, while NiL2@CPE and NiL3@CPE exhibited higher current densities at elevated methanol concentrations. Scan-rate studies indicated that the oxidation process is diffusion-controlled, and a linear response to methanol concentration was observed over a wide concentration range. The results demonstrate that ligand structure and coordination geometry play a crucial role in modulating the electrocatalytic behavior of Ni(II) Schiff base complexes, highlighting their potential as cost-effective molecular catalysts for alkaline methanol oxidation. Full article

Marine invertebrates produce a remarkable diversity of polyhydroxylated steroids and secosteroids whose structural features—particularly vicinal (1,2-)diols, 1,3-diols, and clustered hydroxyl arrays—make them well suited for coordination with boron species. In the marine environment, where boron is abundant, chemically stable, and predominantly present as borate under mildly alkaline conditions, such interactions are not only plausible but may be widespread. This review examines the chemistry of boron–steroid complexation in marine systems, emphasizing how rigid steroidal frameworks preorganize diol motifs to form reversible yet stable borate esters under environmentally relevant conditions. We discuss how polyhydroxy steroids may exist in dynamic equilibria between free and boron-bound forms, with speciation governed by pH, boron concentration, and local microenvironmental factors rather than enzymatic control. Boron complexation can modulate key physicochemical properties, including solubility, conformation, and membrane affinity, thereby influencing the biological activity of marine steroids without covalent modification of the carbon framework. By integrating examples from sponges, echinoderms, and corals together with well-characterized model polyols, this review highlights boron complexation as an underrecognized but potentially important factor influencing the structure, function, and bioactivity of marine steroid metabolites. Full article