Estimating weakening on hillslopes caused by strong earthquakes

The weakening of hillslopes during strong earthquakes increases landsliding rates in post-seismic periods. However, very few studies have addressed the amount of coseismic reduction in shear strength of hillslope materials. This makes estimation of post-seismic landslide susceptibility challenging. Here we propose a method to quantify the maximum shear-strength reduction expected on seismically disturbed hillslopes. We focus on a subset of the area affected by the 2008 Mw 7.9 Wenchuan, China earthquake. We combine physical and data-driven modeling approaches. First, we back-analyze shear-strength reduction at locations where post-seismic landslides occurred. Second, we regress the estimated shear-strength reduction against peak ground acceleration, local relief, and topographic position index to extrapolate the shear-strength reduction over the entire study area. Our results show a maximum of 60%–75% reduction in near-surface shear strength over a peak ground acceleration range of 0.5–0.9 g. Reduction percentages can be generalized using a data-driven model.</p

Engineering band structures and topological invariants by transformation optics

By introducing the transformation optics method to periodic systems, we show the tunability of the band structures by comparing the results from original spaces and transformed spaces. Interestingly, we find the topological invariant Chern number will change sign when the orientation of the Brillouin zone flipped. The new platform we provided for engineering the band diagram and topological invariant might lead to the development of both transformation optics and photonic topological states.Comment: 6 pages, 3 figure

Vortex-induced Shear Polaritons

Hyperbolic shear polaritons (HShPs) emerge with widespread attention as a new class of polariton modes with broken symmetry due to shear lattices. In this letter, we find a new mechanism of generating HShPs. When utilizing vortex waves as excitation sources of hyperbolic materials without off-diagonal elements, HShPs will appear. In addition, this asymmetric HShPs can be recovered as symmetric modes away from the source, with a critical transition mode between the left-skewed and right-skewed HShPs, via tuning the magnitude of the off-diagonal imaginary component and controlling the topological charge of vortex source. It is worth mentioning that we explore the influence of parity of topological charges on the field distribution and demonstrate these exotic phenomena from numerical and analytical perspectives. Our results will promote new opportunities for both HShPs and vortex waves, widening the horizon for various hyperbolic materials based on vortex sources and offering a new degree of freedom to control various kinds of polaritons

An in-situ method for assessing soil aggregate stability in burned landscapes

Due to soil repellency in burned areas, slope runoff and soil erodibility escalates following forest fires, increasing the vulnerability to post-fire debris flows. Soil aggregate stability is a critical determinant of soil infiltration capacity and erosion susceptibility. The prevalent method of assessing soil aggregate stability in burned areas, the counting the number of water drop impacts (CND) method, is time-intensive and impractical for in-situ measurements. In response, this study introduces a novel technique based on the shock and vibration damage (SVD) effect for evaluating soil aggregate stability in burned areas. Thirteen distinct soil aggregate types were meticulously prepared for indoor simulated fire testing, with due consideration to factors such as bulk weight, organic matter content, and water repellency, which influence stability of soil aggregates. Employing a custom-built test apparatus, the mass loss rate (MLR) of soil aggregates was determined through orthogonal experiments using the SVD method and compared against the standard CND technique's quantification of water droplet-induced aggregate destruction. The findings demonstrated that SVD method, employing Test Scheme 6 (testing 20 aggregates, 1-meter impact height, 40% water content, and five impacts), exhibits excellent agreement (Kendall coefficient = 0.797) and correlation (R2 = 0.634) with CND method outcomes. This testing scheme, characterized by rapid determination and effective discrimination, is identified as the optimal testing approach. The SVD testing apparatus is straightforward, portable, and easily disassembled, rendering it suitable for on-site use. It can be used to distinguish the stability level of soil aggregates swiftly and quantitatively under various fire intensities in burned areas in situ, which is an important guiding significance for the study of soil erosion, erosion control, and post-fire debris flow initiation mechanism in burned areas

Effect and Repair Mechanism of Nano Ag Sponge Dressing Combined with Gelatin-Bletilla Striata Gum/Salvia Miltiorrhiza on Refractory Orthopedic Wounds

Objective. To explore the effect and mechanism of the sponge dressing on the healing of refractory orthopedic wound, and the gelatin-Bletilla striata gum/Salvia miltiorrhiza nano Ag (GBS-Ag) sponge dressing was prepared. Methods. GBS-Ag sponge dressing was prepared by the freeze-drying method. Twenty male SD rats were randomly divided into the control group (Ctrl group) and GBS-Ag group, with 10 rats in each group, and the rats in the two groups were established a model of back wound infection. The Ctrl group was treated with gauze, while the GBS-Ag group was treated with GBS-Ag sponge dressing. Wound healing rate, blood immune indexes, Ag content in each organ, morphological changes of wound, and expression of transforming growth factor-β1 (TGF-β1) in wound transformation were detected in the two groups of rats. Results. The mechanical properties of GBS-Ag sponge dressing were all in line with the standard, and it had good killing effect on the conventional strain after being incubated for 24 hours. Compared with the Ctrl group, the healing rate and lymphocyte percentage in the GBS-Ag group were significantly increased on day 4 and day 10 (P<0.05), while the total number of white blood cells and the percentage of neutrophils were significantly decreased (P<0.05). Compared with Ctrl group, the Ag content in liver, spleen, and kidney of rats in the GBS-Ag group was significantly increased (P<0.05). The histological results showed that the Ctrl group lacked collagen fibers in the dermis, and the angiogenesis was not rich, accompanied by a large number of inflammatory cell infiltration. The epidermal repair of rats in the GBS-Ag group was complete and partially keratinized, the dermis was rich in collagen fibers, with elastic fibers and new blood vessels, inflammatory cells were rare, and new hair follicles and thick-walled blood vessels were also observed. The expression of TGF-β1 protein in the wounds of rats in the GBS-Ag group was higher than that of the Ctrl group. Conclusion. GBS-Ag sponge dressing had multiple effects of sterilization and promoting wound healing, and its mechanism may be related to promoting the TGF-β1 protein expression

Potential effects of Sargassum kjellmanianum as a dietary supplement on the growth performance, immunity response, antioxidant status, and ammonia resistance of yellow catfish (Pelteobagrus fulvidraco)

This study aimed to investigate the potential effects of seaweed Sargassum kjellmanianum (SK) as a dietary supplement on the growth performance, blood biochemistry, immunology, antioxidants, and ammonia stress resistance of yellow catfish, Pelteobagrus fulvidraco. Four diets containing 0 % SK (control), 2.5 % SK, 5 % SK, and 10 % SK were fed to fish for 8 weeks. After the feeding trial, the fish were exposed to ammonia for 72 h and their mortality was recorded. Compared with the control group, the growth performance was significantly increased in the 2.5 % and 5 % SK groups (P < 0.05). Serum albumin levels were significantly increased (P < 0.05), meanwhile serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels were significantly decreased in fish fed with 2.5 % and 5 % SK (P < 0.05). Interestingly, the serum AST and ALT activities were significantly increased in the 10 % SK group (P < 0.05). Additionally, serum lysozyme, acid phosphatase, and complement 4 levels were all significantly increased in all SK groups than those of the control group (P < 0.05). In addition, serum malondialdehyde levels were significantly decreased (P < 0.05). Meanwhile, the total antioxidant capacity, superoxide dismutase, and catalase levels were significantly increased in the 2.5 % and 5 % SK groups with relative to the control group (P < 0.05). Notably, the cumulative mortality rate was significantly higher (46.67 %) in the control fish than those fed the SK diets (35–38.33 %) (P < 0.05). Taken together, the results indicated that adding SK to the diet of yellow catfish can enhance growth performance, stimulate immune responses, improve antioxidant status, and increase resistance to ammonia stress. It is recommended to use concentrations between 2.5 % and 5.0 % in present study

Regulation of inflammatory cytokines for spinal cord injury recovery

Spinal cord injury (SCI) is one of the most destructive traumatic diseases in human beings. The balance of inflammation in the microenvironment is crucial to the repair process of spinal cord injury. Inflammatory cytokines are direct mediators of local lesion inflammation and affect the prognosis of spinal cord injury to varying degrees. In spinal cord injury models, some inflammatory cytokines are beneficial for spinal cord repair, while others are harmful. A large number of animal studies have shown that local targeted administration can effectively regulate the secretion and delivery of inflammatory cytokines and promote the repair of spinal cord injury. In addition, many clinical studies have shown that drugs can promote the repair of spinal cord injury by regulating the content of inflammatory cytokines. However, topical administration affects only a small portion of inflammatory cytokines. In addition, different individuals have different inflammatory cytokine profiles during spinal cord injury. Therefore, future research should aim to develop a personalized local delivery therapeutic cocktail strategy to effectively and accurately regulate inflammation and obtain substantial functional recovery from spinal cord injur

Predictive model of regional coseismic landslides’ permanent displacement considering uncertainty

Coseismic landslides are common secondary earthquake geohazards in meizoseismal areas. Newmark sliding block permanent displacement method has been widely adopted to develop regional coseismic landslide hazard maps. However, uncertainties from the slope parameters (e.g., cohesion, pore water pressure, and block thickness) are not commonly considered in the ground displacement predictions. This study proposes a novel framework that consists of two uncertainty assessment methods of Monte Carlo and logic tree simulations (MCS and LTS) with seven different displacement regression functions to predict the regional coseismic landslides' permanent displacement. Compared with the existing methods, the proposed framework is argument-driven, avoiding huge number of repetitive simulations. The Jiuzhaigou earthquake, in China, is considered as an illustrative example to compare the performance of the framework with considered regression functions. The corresponding results show that using LTS, with a certain regression function, leads to better predictions compared to using MCS. It is demonstrated that the proposed framework can provide a meaningful measure for making informed decisions to diminish the potential risk of earthquake induced landslides, and/or generating emergency strategies to mitigate post-earthquake consequences. It should be noted that the application of the proposed method for deposits where the soil strength parameter values do not fit the normal distribution may be limited as only normal distribution for soil strengths is considered in this study

Fluorine gas treatment improves surface degradation inhibiting property of alumina-filled epoxy composite

Epoxy resins blended with micro-sized alumina show more compact surface condition and exhibit lower light emission after modified in fluorinated atmosphere. Surface morphology reflected by atomic force microscope shows that the fluorinated surface layer can overlap alumina particles inlayed in the original surface and a smoother and more compact surface condition is generated. Thermally stimulated current test exhibits that surface fluorination is able to bring more shallow traps to surface states, and the trap amount increases with the extension of fluorinating time. The photon counting technique illustrates that the fluorinated surface has lower light emission which indicates better aging inhibition properties. Therefore, we believe that the surface fluorination technique may have potential significance in modifying epoxy based insulators used in high voltage applications