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This study delves into the mechanical properties of steep and rocky slopes subjected to long-term freeze-thaw actions. Considering the unique climatic conditions in cold regions, especially the significant impact of seasonal and diurnal temperature variations on slope excavation, the research focuses on a high-cold region iron ore mine. Four types of rocks commonly found in the mining area are thoroughly examined, taking into account the hydrogeological conditions of the mining area. The study systematically analyzes the mechanisms of various factors such as weathering, freeze-thaw cycles, and ice-water phase changes on the stability of cold region fractured rock masses. The research reveals that under prolonged freeze-thaw actions, crack water within the rock continuously undergoes ice-water phase changes, generating substantial freeze expansion forces that result in structural damage to the rock mass. This damage is evident not only in the development of existing microcracks but also leads to the generation of new fractures, ultimately causing deterioration in the rock mass structure. The study of the evolution patterns of freeze-thaw forces contributes to a better understanding of slope stability issues in cold region mineral resource extraction, offering crucial insights for the design, construction, and operation of related engineering projects. [ABSTRACT FROM AUTHOR]

In high-cold regions, the instability of precarious rock masses in open-pit mines is often exacerbated by the effects of freeze-thaw cycles, posing a significant threat to the continuous production of open-pit mining operations. To address this issue effectively, we conducted an in-depth study on the precarious rock masses in the near-slope of a mining area in a high-cold region using a fracture mechanics-based stability analysis method. We analyzed the impact of freezethaw cycles on the engineering stability. Introducing a novel approach, we established the temperature field at different time points to determine whether the freeze-thaw depth influences the generation of freeze-thaw forces on the controlling structural surfaces. Employing the maximum circumferential stress criterion, we conducted a comprehensive analysis of tension cracks in the slope and derived corresponding safety factor expressions. Focusing on retrogressive rock slopes, we divided the slope's precarious rock masses into n potentially unstable approximate rectangular rock bodies. Based on this, we developed a fracture mechanics-based slope stability calculation method considering the combined effects of freeze-thaw forces, crack water pressure, and gravity. Through relevant numerical examples, we successfully calculated the safety factors of the segmented rock bodies, revealing the varying influence of freezethaw forces on rock mass stability. By integrating the calculation results with practical engineering considerations, we validated the feasibility of our proposed method. Lastly, aligning with pertinent precarious rock stability assessment criteria, we provided corresponding remediation measures based on the distinct stability conditions of the rock masses. Through comprehensive research and an effective computational approach, we offer a scientifically viable solution for the stability of precarious rock masses in open-pit mines in high-cold regions, thereby providing robust technical support for the sustainable production of mining enterprises. [ABSTRACT FROM AUTHOR]

The oceans, serving as some of the most extensive reservoirs of mercury (Hg) on Earth, play an essential role in the global Hg biogeochemical circulation, as a sink for atmospheric deposits and surface runoff while simultaneously emitting Hg to the atmosphere. Clarifying the mechanisms during cycling of Hg in marine ecosystems is a crucial segment in elucidating global Hg behavior and assessing its risks to wildlife and humans. The stable Hg isotope technique has emerged as a powerful tool for identifying potential sources and certain processes of Hg. Herein, the research advances in marine Hg biogeochemical cycling were reviewed from an isotopic tracing perspective, including sources of marine Hg, isotopic fingerprints across various marine media, and applications of Hg isotopes in pathways, transport, and transformation mechanisms associated with marine environments. The knowledge gaps and challenges were further discussed in the development of ultratrace level and species-specific isotopic analytical methods, the isotope fractionation mechanisms in reactions and processes, and the integration of multiple approaches and cross disciplines. These future studies would advance our understanding of Hg behavior in oceanic environments, its authentic function, and interactions with other ecosystems in the global Hg cycle, and evaluate its response to environmental changes. [ABSTRACT FROM AUTHOR]

To investigate the influence of the different substituents in the main ligands on the electronic structures, phosphorescent properties, and organic light-emitting devices (OLEDs) performance, three iridium(III) complexes 1, 2, and 3 are studied by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). Ionization potential, electron affinities, and reorganization energy have also been obtained to evaluate the charge transfer and balance properties between hole and electron for the three complexes. The lowest energy absorption wavelength calculated for complex 1 is in very good agreement with the experimental value. The lowest energy emissions of complexes 1,2, and 3 are localised at 492, 565, and 510 nm, respectively, at M052X level. It is expected that this work might provide a way to develop potential iridium(III) phosphors with good electroluminescent performance. Key words: DFT, TDDFT, OLEDs, iridium, phosphorescence. En vue d'etudier l'influence des differents substituants des principaux ligands sur les structures electroniques, les proprietes de phosphorescence et la performance des diodes electroluminescentes organiques (DELO), nous avons examine trois complexes d'iridium(III), les complexes 1, 2 et 3, au moyen de theorie de la fonctionnelle de la densite et de sa variante dependante du temps (DFT/TDDFT). Nous avons egalement determine le potentiel d'ionisation, les affinites electroniques et l'energie de reorganisation afin d'evaluer dans les trois complexes le transfert de charge et les proprietes d'equilibre entre le trou et l'electron. La longueur d'onde d'absorption de plus faible energie calculee pour le complexe 1 concorde tres bien avec la valeur experimentale. Les emissions de plus faible energie des complexes 1, 2 et 3 se situent a 492, 565 et 510 nm, respectivement, au niveau M052X. Ces travaux devraient permettre de creer des luminophores a base d'iridium(III) offrant une bonne performance electroluminescente. [Traduit par la Redaction] Mots-cles: DFT, TDDFT, DELO, iridium, phosphorescence., Introduction Along with the advances in the fields of device science and device fabrication, the organic light-emitting devices (OLEDs) technology has been an important competitor to liquid crystals and liquid [...]