Pressure-induced charge orders and their postulated coupling to magnetism in hexagonal multiferroic LuFe\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e

Hexagonal LuFe2O4 is a promising charge order (CO) driven multiferroic material with high charge and spin-ordering temperatures. The coexisting charge and spin orders on Fe3+/Fe2+ sites result in magnetoelectric behaviors, but the coupling mechanism between the charge and spin orders remains elusive. Here, by tuning external pressure, we reveal three charge-ordered phases with suggested correlation to magnetic orders in LuFe2O4: (i) a centrosymmetric incommensurate three-dimensional CO with ferrimagnetism, (ii) a non-centrosymmetric incommensurate quasi-two-dimensional CO with ferrimagnetism, and (iii) a centrosymmetric commensurate CO with antiferromagnetism. Experimental in situ single-crystal X-ray diffraction and X-ray magnetic circular dichroism measurements combined with density functional theory calculations suggest that the charge density redistribution caused by pressure-induced compression in the frustrated double-layer [Fe2O4] cluster is responsible for the correlated spin-charge phase transitions. The pressure-enhanced effective Coulomb interactions among Fe-Fe bonds drive the frustrated (1/3, 1/3) CO to a less frustrated (1/4, 1/4) CO, which induces the ferrimagnetic to antiferromagnetic transition. Our results not only elucidate the coupling mechanism among charge, spin, and lattice degrees of freedom in LuFe2O4, but also provide a new way to tune the spin-charge orders in a highly controlled manner

Assessing Sea Surface Temperatures Estimated from Fused Infrared and Microwave Data

Sea surface temperature (SST), a critical parameter of the global ocean–atmosphere system, is an essential element in the study and in the application of marine science. Satellite–infrared observations currently represent the only available method for continuous, large-scale observation of SST. Although passive microwave observations are not blocked by clouds, allowing for data collection in all weather conditions, this technological tool is characterized by low spatial resolution. Conversely, infrared observations offer high resolution but are susceptible to cloud obscuration. Accordingly, a technique that effectively fuses microwave and infrared satellite observations into a high-resolution SST field with global coverage close to the actual distribution is of practical significance. This paper describes fusing MODIS infrared remote sensing and AMSR-2 microwave remote sensing SST data with an optimal interpolation (OI) approach to produce a high-resolution SST data. The study chose the coastal Kuroshio region of China to establish an appropriate scale for examining the spatial structure of SST and attaining a more realistic picture of SST observations and impacts. The included discussion of the sources of error in the fusion process provides a reference for improving the accuracy of fused marine remote sensing data. The study also compared the fused SST results and the current international mainstream multi-temporal resolution of the three using the OI algorithm. We compared the fusion product with ARGO data with and without typhoon impact to explore and practice the OI in SST fusion when evaluating the accuracy of different data in the case of external disturbance being present. The research results have great significance for improving regional SST forecast accuracy while ensuring the applicability of various approaches to fusing SST data by incorporating the influence of typhoons in the offshore region of the East China Sea (ECS). Implications for the future development of SST fusion data are also included in the discussion

Analysis of 1D large strain consolidation of structured marine soft clays

Structured soft clays are widely distributed in the coastal regions of China. The characteristics of the natural structure greatly influence the compressibility and permeability of marine soft clays and should be considered in the theory of their consolidation. When a large surcharge load is applied to a structured clay deposit, large strains can be induced in the clay layer due to the high compressibility, where the consolidation process follows the large strain assumption. However, there are few published theories of consolidation in which both the natural structure of marine soft clays and the large strain assumption can be considered simultaneously. In this study, a novel large strain consolidation model for structured marine soft clays was developed by considering the variation of structural yield stress with depth and using different calculation methods for initial effective stress of structured clay deposits in the Lagrangian coordinate system. The corresponding solution was derived by the finite difference method. Finally, the influences of the natural structure of soft clays and different geometric assumptions on consolidation behavior were investigated. The results show that the dissipation rate of excess pore water pressure of structured clays under the large strain assumption is expected to be faster than that under the small strain assumption, and the difference in consolidation behavior between the two assumptions increases with the strain level of natural structured clays. If the strain level in the clay layer is more than 15%, the difference in consolidation behavior between the large and small strain assumptions must be considered

Recent Studies on the Fabrication of Multilayer Films by Magnetron Sputtering and Their Irradiation Behaviors

Multilayer films with high-density layer interfaces have been studied widely because of the unique mechanical and functional properties. Magnetron sputtering is widely chosen to fabricate multilayer films because of the convenience in controlling the microstructure. Essentially, the properties of multilayer films are decided by the microstructure, which could be adjusted by manipulating the deposition parameters, such as deposition temperature, rate, bias, and target–substrate distance, during the sputter process. In this review, the influences of the deposition parameters on the microstructure evolution of the multilayer films have been summarized. Additionally, the impacts of individual layer thickness on the microstructure evolution as well as the irradiation behavior of various multilayer films have been discussed

Study on the Regulation Mechanism of 1-MCP Combined with SO₂ Treatment on Postharvest Senescence of Bamboo Shoots (<i>Chimonobambusa quadrangularis</i>) in Karst Mountain Area

Fresh bamboo shoots (Chimonobambusa quadrangularis) are subjected to senescence (e.g., lignification and browning) during postharvest storage. This study investigated the effects of 1-MCP and SO2 treatment on bamboo shoot senescence and its regulation mechanism in order to extend bamboo shoot storage time. 1-MCP and SO2 treatments significantly inhibited the browning and lignification of fresh bamboo shoots during storage, according to the results. Its lower browning index and lignin content are directly related to its lower lignin content compared to the CK control group. The browning index and lignin content of the 1-MCP + SO2 treatment during the late storage period were 90.55% and 81.50% of the CK treatment, respectively. The result of the in-depth analysis suggested that 1-MCP and SO2 treatments reduced nutrient loss and maintained the nutritional value of bamboo shoots by inhibiting respiration and physiological metabolism. The PPO activity was inhibited to inhibit the browning process. Moreover, the scavenging ability of ROS was enhanced, the accumulation of MDA was inhibited, and the senescence of bamboo shoots was delayed after higher contents of total flavonoids and ascorbic acid were maintained and the activities of ascorbic acid peroxidase and superoxide dismutase were stimulated. Furthermore, lignin biosynthesis was hindered, and the lignification of bamboo shoots was delayed after the activities of POD and PAL were inhibited. In brief, 1-MCP + SO2 treatment is capable of inhibiting the physiological metabolism, browning, and lignification of bamboo shoots, maintaining good quality during storage, and delaying the senescence of bamboo shoots. Clarifying the senescence mechanism of bamboo shoots is of great significance for expanding the bamboo shoot industry and slowing down rocky desertification in karst mountainous areas

Manipulation of the Ferromagnetism in LaCoO3 Thin Films Through Cation‐Stoichiometric Engineering

Spin-state transitions are an important research topic in complex oxides with the diverse magnetic states involved. In particular, the low-spin to high-spin transition in LaCoO3 thin films has drawn a wide range of attention due to the emergent ferromagnetic state. Although various mechanisms (e.g., structural distortion, oxygen-vacancy formation, spin-state ordering) have been proposed, an understanding of what really underlies the emergent ferromagnetism remains elusive. Here, the ferromagnetism in LaCoO3 thin films is systematically modulated by varying the oxygen pressure during thin-film growth. Although the samples show dramatic different magnetization, their cobalt valence state and perovskite crystalline structure remain almost unchanged, ruling out the scenarios of both oxygen-vacancy and spin-ordering. This work provides compelling evidence that the tetragonal distortion due to the tensile strain significantly modifies the orbital occupancy, leading to a low-spin to high-spin transition with emergent ferromagnetism, while samples grown at reduced pressure demonstrate a pronounced lattice expansion due to cation-off-stoichiometry, which suppresses the tetragonal distortion and the consequent magnetization. This result not only provides important insight for the understanding of exotic ferromagnetism in LaCoO3 thin films, but also identifies a promising strategy to design electronic states in complex oxides through cation-stoichiometry engineering

Manipulation of the Ferromagnetism in LaCoO3 Thin Films Through Cation‐Stoichiometric Engineering

Spin-state transitions are an important research topic in complex oxides with the diverse magnetic states involved. In particular, the low-spin to high-spin transition in LaCoO3 thin films has drawn a wide range of attention due to the emergent ferromagnetic state. Although various mechanisms (e.g., structural distortion, oxygen-vacancy formation, spin-state ordering) have been proposed, an understanding of what really underlies the emergent ferromagnetism remains elusive. Here, the ferromagnetism in LaCoO3 thin films is systematically modulated by varying the oxygen pressure during thin-film growth. Although the samples show dramatic different magnetization, their cobalt valence state and perovskite crystalline structure remain almost unchanged, ruling out the scenarios of both oxygen-vacancy and spin-ordering. This work provides compelling evidence that the tetragonal distortion due to the tensile strain significantly modifies the orbital occupancy, leading to a low-spin to high-spin transition with emergent ferromagnetism, while samples grown at reduced pressure demonstrate a pronounced lattice expansion due to cation-off-stoichiometry, which suppresses the tetragonal distortion and the consequent magnetization. This result not only provides important insight for the understanding of exotic ferromagnetism in LaCoO3 thin films, but also identifies a promising strategy to design electronic states in complex oxides through cation-stoichiometry engineering