Search Results (9)

The ocean is a significant global reservoir of uranium (U) and thorium (Th). These elements can be incorporated into marine sediments through processes involving organic matter (OM), redox conditions, terrigenous inputs, and mineral interactions. Helium generated through the radioactive decay of U and Th within geological formations represents a critical potential resource. Marine black shales, which are rich in U and Th, are widespread in the Ediacaran Doushantuo Formation of the Upper Yangtze Platform, making them a key target for helium exploration. However, there is limited research on the mechanisms behind U and Th accumulation in these shales. This study focuses on shales from the Doushantuo Formation in Chongqing, China, aiming to explore the mechanisms of U and Th accumulation and assess the potential for helium generation, and argillaceous dolomites are included for comparative analysis. The results show that the average U and Th content in the black shales (17.58 and 9.78 ppm, respectively) is higher than that of argillaceous dolomites (3.52 and 2.75 ppm, respectively). Uranium mainly comes from authigenic precipitation and hydrothermal inputs, while thorium is primarily sourced from terrigenous and hydrothermal inputs. The semi-humid climate in the provenance area facilitated parent rock weathering, with atmospheric precipitation and river systems transporting U and Th to the ocean. However, excessive terrigenous input can dilute the U and Th content in the sediments. In the shales, uranium is primarily adsorbed and/or complexed by organic matter (OM), with the anoxic–euxinic sedimentary environment and high OM content (TOC = 0.06–34.58 wt.%, r = 0.95) promoting U accumulation. Thorium accumulation is largely controlled by adsorption onto clay minerals. The total amount of helium generated from the Doushantuo shales is estimated to be 7.20 × 10¹⁰ m³. Full article

The International Convention for the Safety of Life at Sea (SOLAS) stipulates that all ships must be equipped with lifesaving devices. The freefall lifeboat has the advantages of simple operation, fast release speed, and good safety performance, so it is widely used. The interaction between the hull and the water body of the freefall lifeboat during the water entry process is a complex fluid–structure interaction process that has great influence on the motion characteristics and structural force of the lifeboat. In order to improve the safety of lifeboats used in the lifesaving process, this paper establishes a 3D, full-scale model of a lifeboat and the fluid area, uses the ALE method to deal with the fluid–structure interaction problem, and numerically simulates the water entry of a lifeboat. Key information such as the hull motion trajectory, motion speed, and impact load are obtained, and three typical modes of lifeboat movement are summarized. At the same time, the influence of different skid angles, skid heights, and skid lengths on the lifeboat launch process is explored. The results show that increasing the angle, height, and length of the skid to a certain extent is conducive to the rapid escape of the lifeboat from a danger zone. The research results of this paper can provide a reference for the design of lifesaving systems for offshore floating facilities such as ships, which is of great significance for ensuring the safety of marine personnel. Full article

This study conducted numerical simulations of three-dimensional vortex-induced vibrations (VIV) on cylindrical bodies with various surface protrusion coverage rates, systematically investigating the impact of coverage and protrusion height on the vibrational response of flexible cylinders. The fluid forces on the surface of the riser were resolved using the finite volume method, while the structural forces were solved with the finite element method. A strongly coupled approach was employed for iterative updates between the flow field and structural field data, achieving a bidirectional flow–structure coupling simulation of VIV in a marine environment. The study further explored the performance of surface protrusions in suppressing VIV and considered protrusion heights of 0.1 times the cylinder diameter (0.1D) under coverage rates (CR) of 0%, 10%, 20%, 30%, and 40%, as well as seven different protrusion heights of 0.05D, 0.1D, and 0.15D at a 20% coverage rate. The mechanism of VIV suppression by surface protrusions was identified as altering the separation point of the shear layer and the frequency of vortex shedding through the vortices formed between the surface protrusions. It was found that a 20% coverage rate with a protrusion height of 0.01D (CR20) effectively suppressed the VIV of the cylinder, showing the best performance in VIV suppression, with an efficiency of 30.04%. These results provide a theoretical basis for designing more efficient VIV suppression devices and contribute to enhancing the resistance of marine structures against vortex-induced vibrations. Full article

In ocean engineering, interactions between ocean currents and risers lead to regular vortex shedding on both sides of the riser, causing structural deformation. When the frequency of vortex shedding approaches the natural frequency of the structure, resonance occurs, significantly increasing deformation. This phenomenon is a critical cause of riser failure. Therefore, the dynamic response of flexible risers to vortex-induced vibrations (VIV) is crucial for their structural safety. This paper employs the finite-volume method to integrate over control volumes to solve for forces, such as pressure and shear stress, on the surface of the riser, while the finite-element method discretizes the continuous structural body into elements and nodes to solve for structural displacements and stresses. A strongly coupled method is utilized at each timestep to iteratively transfer load-displacement data between the fluid and structural fields, updating the boundary conditions of the fluid domain to achieve a bidirectional fluid–structure interaction simulation of vortex-induced vibrations in a seawater environment for flexible risers. The study finds that the three-dimensional flexible riser exhibits multi-frequency vibration phenomena and broadband vibration response characteristics under high flow velocity conditions. As the flow velocity increases, the vortex-shedding mode is observed to transition from the simple two single (2S) mode to the more complex pair + single (P + S) and two pair (2P) modes. In addition, the stiffness at the ends is enhanced by the fixed boundary conditions, and the coupling between the natural frequency of the ends and the vortex-shedding frequency triggers complex vortex-shedding phenomena in these regions. At higher flow velocities, these boundary effects result in more complex vortex-shedding modes and stronger vibration responses at both ends of the riser. Full article

(1) Background: Traditional dressings can only superficially cover the wound, they have widespread issues with inadequate bacterial isolation and liquid absorption, and it is simple to inflict secondary wound injury when changing dressings. Therefore, it is crucial for wound healing to develop a new kind of antimicrobial colloidal dressing with good antibacterial, hygroscopic, and biocompatible qualities. (2) Methods: Ag-montmorillonite/chitosan (Ag-MMT/CS) colloid, a new type of antibacterial material, was prepared from two eco-friendly materials—namely, montmorillonite and chitosan—as auxiliary materials, wherein these materials were mixed with the natural metal Ag, which is an antibacterial agent. The optimum preparation technology was explored, and Ag-MMT/CS was characterized. Next, Staphylococcus aureus, which is a common skin infection bacterium, was considered as the experimental strain, and the in vitro antibacterial activity and cytocompatibility of the Ag-MMT/CS colloid were investigated through various experiments. Subsequently, a rat skin infection model was established to explore the in vivo antibacterial effect. (3) Results: In vitro studies revealed that the Ag-MMT/CS colloid had a good antibacterial effect on S. aureus, with an inhibition zone diameter of 18 mm and an antibacterial rate of 99.18%. After co-culture with cells for 24 h and 72 h, the cell survival rates were 88% and 94%, respectively. The cells showed normal growth and proliferation, and no evident dead cells were observed under the laser confocal microscope. After applying the colloid to the rat skin infection model, the Ag-MMT/CS treatment group exhibited faster wound healing and better local exudation and absorption in the wound than the control group, suggesting that the Ag-MMT/CS colloid exhibited a better antibacterial effect on the S. aureus. (4) Conclusions: Ag⁺, chitosan, and MMT present in the Ag-MMT/CS colloid dressing exert synergistic effects, and it has good antibacterial effects, cytocompatibility, and hygroscopicity, indicating that this colloid has the potential to become a next-generation clinical antibacterial dressing. Full article

As consumers pursue higher display quality, Mini-LED backlight technology has become the focus of research in the current display field. With its size advantage (100–200 μm), it can achieve one-thousand-level divisional dimming, and it can also be combined with quantum dot technology to greatly improve the contrast, color gamut, dark state and other element of the display performance of LCD displays. Mini-LED backlight technology is undoubtedly the most ideal solution to realize a highly dynamic range display of LCD displays, and has been widely commercialized in many fields such as TVs, tablet computers, notebook computers, and car monitors. This review mainly introduces the efforts made by researchers to eliminate the halo effect, thinning of the backlight module and reducing the backlight power consumption. The application of quantum dot technology in backlight is also presented. We predict that the number of Mini-LED backlight partitions is expected to reach a level of more than 3000 in the future, further utilizing the advantages of the small size in local dimming, but it will also inevitably be challenged by some issues such as power consumption and heat dissipation. Full article

Optical detection is of great significance in various fields such as industry, military, and medical treatment, especially ultraviolet (UV) photodetectors. Moreover, as the demand for wearable devices continues to increase, the UV photodetector, which is one of the most important sensors, has put forward higher requirements for bending resistance, durability, and transparency. Tin oxide (SnO₂) has a wide band gap, high ultraviolet exciton gain, etc., and is considered to be an ideal material for preparing UV photodetectors. At present, SnO₂-based UV photodetectors have a transparency of more than 70% in the visible light region and also have excellent flexibility of 160% tensile strain. Focusing on SnO₂ nanostructures, the article mainly summarizes the progress of SnO₂ UV photodetectors in flexibility and transparency in recent years and proposes feasible optimization directions and difficulties. Full article

Taxilli Herba (TH) is a well-known traditional Chinese medicine (TCM) with a wide range of clinical application. However, there is a lack of comprehensive research on its chemical composition in recent years. At the same time, Taxillus chinensis (DC) Danser is a semi parasitic plant with abundant hosts, and its chemical constituents varies due to hosts. In this study, the characterization of chemical constituents in TH was analyzed by ultra-fast liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (UFLC-Triple TOF-MS/MS). Moreover, partial least squares discriminant analysis (PLS-DA) was applied to reveal the differential constituents in TH from different hosts based on the qualitative information of the chemical constituents. Results showed that 73 constituents in TH were identified or tentatively presumed, including flavonoids, phenolic acids and glycosides, and others; meanwhile, the fragmentation pathways of different types of compounds were preliminarily deduced by the fragmentation behavior of the major constituents. In addition, 23 differential characteristic constituents were screened based on variable importance in projection (VIP) and p-value. Among them, quercetin 3-O-β-D-glucuronide, quercitrin and hyperoside were common differential constituents. Our research will contribute to comprehensive evaluation and intrinsic quality control of TH, and provide a scientific basis for the variety identification of medicinal materials from different hosts. Full article

Licochalcone A (LicA), a flavonoid isolated from the famous Chinese medicinal herb Glycyrrhiza uralensis Fisch, has wide spectrum of pharmacological activities. In this study, the anti-cancer effects and potential mechanisms of LicA in non-small cell lung cancer (NSCLC) cells were studied. LicA decreased cell viability and induced apoptosis in a dose-dependent manner in NSCLC cells. LicA inhibited lung cancer cells growth by blocking cell cycle progression at the G2/M transition and inducing apoptosis. LicA treatment decreased the expression of MDM2, Cyclin B1, Cdc2 and Cdc25C in H460 and A549 cancer cell lines. In addition, LicA induced caspase-3 activation and poly-ADP-ribose polymerase (PARP) cleavage, which displayed features of apoptotic signals. Furthermore, LicA increased the expression of endoplasmic reticulum (ER) stress related proteins, such as p-EIF2α and ATF4. These data provide evidence that LicA has the potential to be used in the treatment of lung cancer. Full article